Constituents of Feed and its Effect on Boilers Performance

Babikir Mohamed Elbashir Ahmed

B.Sc. (General) In Chemistry and Botany Faculty of Science University of Khartoum (1971)

A Thesis Submitted to the University of Gezira in Fulfillment of the Requirements for the Award of the Degree of Master of Science

In Department of Engineering Technology Faculty of University of Gezira

Jan. 2016

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Constituents of Feed Water and its Effect on Boilers Performance

Babikir Mohamed Elbashir Ahmed

Supervision Committee: Name Position Signature Dr. Mutasim Abdalla Ahmed Main Supervisor: …………….. Dr. Musa Eltayeb Babiker Co. Supervisor: …………….. Dr. Mohamed Osman Babiker Co. Supervisor: ……………..

Date: /12/2015

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Constituents of Feed Water and its Effect on Boilers Performance

Babikir Mohamed Elbashir Ahmed

Examination Committee: Name Position Signature Dr. Mutasim Abdalla Ahmed Chairperson …………….. Dr. Ahmad Ibrahim ahmad External Examiner …………….. Dr. Imad Eldeen Abdel moniem Internal Examiner ……………..

Date of Examination: 15 /01 /2016

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DEDICATION

This thesis is dedicated to my family, wife, sons, and daughter, relative's colleges and friends

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ACKNOWLEDGEMENT

Thanks to Allah who gave me the will and strength to study, write and complete this thesis. Thanks to senior supervisor Dr. Mutasim for his overall guidance throughout the study. Thanks to co-supervisor Dr. Musa Eltayeb Babiker for his sincere assistant, and encouragement thanks to Dr. Mohamed Osman Babikir for his valuable and useful information. My thanks are also due to the staff of chemistry laboratory and the staff of higher studies Laboratory in the Faculty of Technical Engineering for their continuous help during the study. Thanks to the old colleges in Blue Nile Textiles and Gematex Textiles for their co- operation and thanks to the technical staff in both Kenana Sugar Cane and Khartoum Refinery Companies for their full co-operation and the valuable information they submitted to me. Lastly, I would like to express my thanks to Miss Aiyda Yousif for her patience in typing this manuscript.

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Constituents of Feed Water and its Effect on Performance of Boilers

Babikir Mohamed Elbashir Ahmed

ABSTRACT Boilers are devices used for the generation of steam in huge quantities. The steam is utilized for the generation of heat or electric power. The objective of this study is to highlight the importance and necessity of adequate treatment of feed water before entering the boiler to avoid problems. In this work samples of boiler feed water were collected from four different locations. These locations are factories or companies with different specializations. Analytical methods of testing were carried out for the water samples namely total hardness, pH, electric conductivity and total dissolved solids. Also they were tested for the presence of calcium cation and the chloride, carbonate, bicarbonate, sulphate anions. The total hardness, and the were detected volumetrically while the sulphate ions was detected gravimetrically. The results were analyzed using statistical methods. From the results obtained some samples showed high levels of total hardness, calcium, chloride, carbonate, bicarbonate and sulphate in their boiler feed water. This was due to the fact that these companies were not used to treat their boiler feed water properly. This behavior led to problems associated with efficiency. Other samples showed low levels of these constituents in their feed water, they were free from the problems mentioned above. It is concluded that unless the boiler feed water is thoroughly treated and conditioned and that all other ancillary units like deaerator, alkalizer, scavenger and economizer were functioning, then definitely the boiler will face serious problems. The boiler may be deficient and the cost of running will be high. It is recommended for more certainty that these constituents should be removed totally from the water. Reverse osmosis process is to be implemented as it removes most of the anions and cations, from the water. Also micro processing digital units are to be fixed in – line with the process of boiling to ensure more instant chemical check of the boiler feed water.

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محتويات ماء تغذية الغاليات، وأثرها علي كفاءة الغالية

بابكر محمد البشير أحمد

ملخص الدراسة

الغاليات عبارة عن أجهزة لتوليد البخار بكميات كبيرة والبخار الناتج يستخدم في توليد الحرارة او الكهرباء الغرض من هذه الدراسة هو أن ماء التغذية ألي غالية تنتج البخار الستخدامه في توليد الكهرباء أو بغرض الحرارة يجب أن يعالج بدقة عالية ،وتجرى له كافة العمليات المطلوبة قبل دخوله للغالية لتفادي المشكالت. في هذه الدراسة جمعت عينات من مياه تغذية الغاليات من أربع مناطق مختلفة . هذه المناطق هي مصانع أو شركات بمختلف التخصصات. لقد تم إجراء طرق تحليلية الختبار عينات الماء من حيث العسر الكامل وكذلك األس الهيدروجيني والموصلية الكهربائية والمواد الصلبة الكلية الموجودة. كذلك تم اختبار وجود بعض االيونات مثل الكالسيوم والكلوريد والكربونات والبيكربونات والكبريتات. الكالسيوم واأليونات األخرى تم تحليلها حجمياً بينما تم تحليل وتحديد الكبريتات وزنياً ومن ثم تم تحديد تركيزات هذه المواد كجزء من المليون. هذه النتائج تم تحليلها بإستخدام طرق إحصائية. لقد وضح من النتائج المتحصل عليها من البحث أن مياه بعض العينات أظهرت وجود نسب عالية من العسر الدائم في ماء الغالية الخاص بها وكذلك كميات أكبر من عناصر الكالسيوم والكربونات والبيكربونات. ولقد وجد أن سبب ذلك يعود الي أن بعض هذه الشركات ال تقوم بعمل معالجة كاملة لماء الغالية بطريقة دقيقة ، هذا السلوك أدى إلي مشكالت خطيرة مرتبطة بكفاءة الغالية مثل ترسيب القشور. عينات اخرى أظهرت مقادير قليلة من العسر الدائم وكذلك من األيونات األخرى ،والسبب المباشر في ذلك يعود الي ان هذه الشركات تجري عمليات معالجة شاملة وتامة لماء الغالية ولذا فقد سلمت من المشكالت المذكورة آنفاً. خلصت الدراسة إلى أنه ما لم تتم معالجة تامة لماء الغالية وتهيئتها لهذا الغرض وأن كل األجزاء الملحقة لعملية معالجة ماء الغالية مثل أجهزة طرد الهواء وطرد األكسجين والمعالج القلوي ومسترجع البخار المتكثف تعمل بصورة متناغمة مع عملية إنتاج البخار ،فإنه بدون ذلك نجد أن الغالية تواجه بمشكالت خطيرة وربما تصبح متدنية الكفاءة وأن تكلفة التشغيل سوف ترتفع كثيراً ، عليه فإنه من المهم لضمان أكبر تأكيد إلزالة المواد الغريبة من ماء تغذية الغالية فالبد من إدخال نظام التناضح العكسي في المعالجة لضمان إزالة كافة األيونات الموجودة في الماء ، أيضاً يجب استعمال األجهزة الحديثة والتي توضع في خط واحد مع خط عملية التبخير وذلك لكي تعطي قراءات فورية رقمية لكمية العناصر الموجودة في الماء.

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LIST OF CONTENT

Page Dedication…………………………..………………………….………...… Iv Acknowledgment………………………..……………………………...….. V Abstract ……………………………….....…………………………...... Vi Arabic Abstract ………………………………..………………………...... Vii List of Content ………………...…………………..……………….…….. viii List of Table …………………………………………..…………………… Xi List of Figure …………………………………………..…………………… Xii List of Abbreviations …………………………………..…………………… xiii CHAPTER ONE ………..…….……………………..…………………… 1 INTRODUCTION …..……………………...…….………………… 1 1.1. General introduction ……………………………………………. 1 1.2. Statement of the problem…...…………………………………… 1 1.3. Objectives of the research…………………...…………………... 3 1.3.1. General objective..……………………..……………….. 3 1.3.2. Specific objectives……………………...………………. 3 CHAPTER TWO…...... …………………………………..…..…………… 4 LITERATURE REVIEW…………………….……….……….….. 4 2.1. Structure of water………..……………………………...………. 4 2.2. Physical and chemical properties of water:……………...…….. 5 2.3. Occurrence of water………………………………………...…… 5 2.4. Natural water cycle…………………………………………..….. 6 2.4.1. Evaporation – transpiration, condensation…………..…. 7 2.5. Composition of water………………………………………….... 7 2.6. Wet textiles engineering (WTE)………………………………… 8 2.6.1. Processes of (WTE) …………………………………..... 8 2.6.2. The role of water in wet – textile processing (WTPs)...... 12 2.6.3. The properties of water required by (WTPs)……...……. 13 2.6.4. The effect of effluent (WTPs) on environment……...…. 13 2.6.5. The effect of the constituents of the boiler feed water on production cost…………………………………………. 13 2.6.6. Researches workshops related to steam boiler and boiler feed water…………………………………………………… 15 2.6.7. New development in the chemical detection of the boiler feed water………………………………………... 16 2.6.8. Characteristics of boiler feed water…………………….. 17 2.7. Properties of ground water………………………………………. 19 2.7.1. Electrical conductivity (E.C)…………………………… 19 2.7.2. pH………………………………………………………. 19 2.7.3. Total alkalinity………………………………………...... 19 2.7.4. Total dissolved solids (TDS)…………………………… 20 2.7.5. ……………………………………………… 20

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2.7.5.1. Consequences of using hard water / problems caused by hard water in wet textile processing 20 2.7.6. Sources of hardness…………………………………… 21 2.7.7. Effect of hard water…………………………………….. 21 2.7.8. Boiler types and classification………………………...... 22 2.7.8.1. Boilers……………………………………….. 22 2.7.8.2. Steel boiler ………………………………… 23 2.7.8.2.1. Fire- tube Boilers……………….. 23 2.7.8.2.2. Water tube boilers…………….. 24 2.8. Formation of rust in boilers ….…………………………………. 26 2.8.1. Chemical rust…………………………………………. 26 2.8.2. Electrochemical rust………………………………….. 26 2.8.3. Bacterial rust…………………………………………. 26 2.9. Specification of boiler feed water………………………………. 26 2.9.1. Conditioning…………………………………………. 26 2.9.2. Boiler corrosion, deaerators and scavenger………….. 26 2.9.3. Scales, sludge, deposits, sediment and fouling deposits 28 2.9.4. Foaming…………………………………………….. 28 2.9.5. Boiler blows down……………………………………. 28 2.9.6. Condensate returns systems………………………….. 29 2.10 Boiler water treatment…………………………………………... 30 2.10.1. Phosphate treatment………………………………….. 31 2.10.2. Soda ash and caustic treatment………………………. 31 2.10.3. Chelating agents……………………………………… 31 2.10.4. Zeolite or Base – Exchange Process…………………. 32 2.10.5. Reverse Osmosis (RO)……………………………….. 33 2.10.5.1 Advantages of Reverse Osmosis…………... 33 2.10.6. Water treatment products…………………………….. 34 2.10.6.1 Antifoams and defoamers………………….. 34 2.10.6.2 Biocides & Disinfectants………………… 34 2.10.6.3 Boiler water treatment chemicals…………. 35 2.10.6.3.1 Scale and corrosion inhibitors… 35 2.10.6.3.2 Sludge conditioners…………… 35 2.11 Determination of water hardness………………………………... 35 2.11.1. Measurement of degree of hardness (dGH)..….……… 35 2.11.2 Significance of calcium – magnesium determination.. 36 2.12 Heat energy…………………………….……………………….. 37 2.13 Location of water samples ……………………………………… 38 2.13.1. Kenana Sugar Company (K.S.C)…………………….. 39 2.13.2. Khartoum Refinery Company (K.R.C)……………….. 39 CHAPTER THREE……………………………………………………… 41 MATERIALS AND METHODS…...………………………….... 41 3.1. Materials………………………………………………………… 41 3.1.1. Water samples………………………………. 41 3.1.2. Preparation of standard solutions……………………... 42 3.2. Methods…………………………………………………………. 43

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3.2.1. Chemical analysis…………………………………….. 43 3.2.1.1. Total Dissolved Solids (TDS)……………... 43 3.2.1.2. pH value…………………………………… 43 3.2.1.3. Electric conductivity (EC) ………………… 43 3.3. Determination of hardness………………………………………. 43 3.3.1. Permanent hardness…….…………………………….. 43 3.3.2. Temporary hardness…………………………………... 43 3.3.3. Total hardness………………………………………… 44 3.3.4. Carbonate and bicarbonate……………………………. 44 3.3.5. Calcium (Ca+2)……………………………………. 45 3.3.6. Chloride (CL ):……………………………………….. 45 -2 3.3.7. Sulphate (SO4 ): …………………………………….. 45 CHAPTER FOUR…………………………………………………………... 47 RESULTS AND DISCUSSION …………………….……….……… 47 4.1. Results…………………………………………………………… 47 4.1.1. Results of total hardness ……………………………... 47 4.1.2. Results of pH values …………………………………. 49 4.1.3. Results of total dissolved solids………………………. 50 4.1.4. Results of electric conductivities……………………... 52 4.1.5. Results of some ions in the four water samples………. 4.1.5.1. Analytical results of different ions in (ml 53 titrant) ……………………………………... 4.1.5.2. Results of different ions in ppm of the four 55 water samples ……………………………... CHAPTER FIVE………………………………………………………..…. 57 CONCLUSION AND RECOMMENDATIONS………………….… 57 5.1. Conclusion….……………………………………………..……. 57 5.2. Recommendations…………...……………………………..…… 58 REFERENCES……………………………………………………..……… 59 Appendix 61

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LIST OF TABLES Table Page 2.1. Costing and Production department, Blue Nile Textile (June 1988) 14 2.2. Chemical requirements of feed water and boiler water for low and medium pressure boilers…………… ………………………………. 18 2.3. Classification of water hardness ……………………………………. 22 2.4. Heat unit of dry and moist fuel……………………………………… 38 2.5. Samples and locations……………………………………………….. 38 4.1. Results of total hardness for the four boilers ……………………….. 47 4.2. Total hardness CaCa3 ppm for the four boilers …………..………… 48 4.3. Results of pH values for the four companies ……………………….. 49 4.4. Results of total dissolved solids for four companies ………………. 50 4.5 Comparison between units used to measure TDS and others 52 4.6. Results of electric conductivity of four companies ………………… 52 4.7. Average volume of titrant used for titrating some ions in the boiler feed water of Gematex factory……………………………………… 53 4.8. Average volume of titrant used for titrating of some ions in the boiler feed water of B.N text Factory……………………………… 54 4.9. Average volume of titrant used for titrating of some ions in the boiler feed water of K.S.C company………………………………… 54

4.10. Average volume of titrant used for titrating of some ions in the boiler feed water of K.R.C company …………………………… 55 4.11. Result of some ions in ppm in the boiler feed water of the four companies …………………………………………………………... 55 4.12 Summary information about the four boilers…………………………. 56

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LIST OF FIGURES Figure Page 2.1. Water molecule and representation of four SP3 orbital …………….. 4 2.2. Fire-tube boiler……………………………………………………… 24 2.3. Work of steam engines work ……………...... 24 2.4. Water tube boiler …………………………………………………… 25 2.5. Oxygen Corrosion (Boiler)……………………………………… 27 2.6. Calcium Carbonate Scale……………………………………………. 28 2.7. Ion exchange process……………………………………………… 32 2.8. Khartoum Refinery Company……………………………………… 40 2.9 Kenana Sugar Company…………………………………………… 40

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LIST OF ABBREVIATIONS

BFW: Boiler feed water WTE: Wet – textile engineering WTPs: Wet – textile processing WTES: Wet – textile effluents N.P: Nonyl phenol N.P.E: Nonyl phenol exothylate R.O: Reverse osmosis E.C.: Electrical conductivity TDS: Total dissolved solids BBD: Boiler blow down dGH: Degree general hardness ppm: Part per million Moh/cm: Micro-ohms per centimeter Conc: Concentration B.N.Tex: Blue Nile Textile K.S.C. Kenana Sugar Company K.R.C. Khartoum Refinery Company Gematex: Gezira Managil Textile

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CHAPTER ONE INTRODUCTION 1.1. General introduction: The use of boilers that work under pressure in industrial organizations is increasing. Some boilers are used for the generation of steam in power station and others are used for heating. Boilers are used for the generation of steam either to be used in electric power stations or for the generation of steam for heating purposes. According to (T.D.Easton and A.Mconky, 1958) the purpose of any power plant is the power output which should be obtained as economically as possible consistent with capital cost and running conditions. It is necessary to assess the overall performance of a plant for comparison purposes and the important criterion is the overall thermal efficiency. In a plant it may be needed to assess a boiler or steam generator only in which case the boiler efficiency may be defined by the heat transmitted to the working fluid compared to the fluid energy supplied. Efficiency specifically applied to a steam boiler. It’s the ratio of heat absorbed by the boiler in the generation of steam to the total amount of heat available in the medium utilized in securing such generation.

In any case if the boiler is to use more fuel than entitled for due to reasons associated with the constituent of the water feed boiler, i.e. being hard and may develop scales on pipes and other parts of the boiler then this phenomenon will resemble a serious limitation to the implementation of the process. The water required for boiler feed purposes i.e. for steam generation, should be of high quality and require a lot of treatment before use.

1 1.2 Statement of the problem: The nature of the problem is that water constitutes ions like calcium and magnesium dissolved in it – called hard water – such water when boils to generate steam it deposits these ions on the pipes and other parts of the boiler as calcium carbonate (scales). Such phenomenon reduces the flow rate in water tube boiler and eventually blocks boiler’s tubes. The consequences of using water in boilers without treatment to remove the constituents responsible for the hardness .will lead to formation of scales and corrosion. Both are negative signs for inefficient boilers. Boilers have to be treated carefully. They and their sisters, the electric power generating units are costly equipments. They should take the maximum care. Their role in wet – textile processing is vital. An old–new–bad – habit in the sudanese industry and particularly in the private sector is the bye pass habit . For any reason due to lack of spare parts, the engineering staff responsible for the maintenance and repair of the mechanical and electrical parts of the water treatment units or its auxiliaries usually tend to jump over processes cancelling a major step in the production line. because of missing spare parts. In big textile mills, it was noticed that the whole or parts of the water treatment system was dismantled and its units were left haphazardly on the ground. It is very clear here how little things make big difference and how the importance of water treatment and conditioning of the boiler feed water is nowhere better exemplified than by the final condition of the boilers of these companies. The costly boilers were sold as iron scrap. The water supply for the boiler came directly from the well with its total hardness exceeding 350 ppm. Without the right boiler feed water treatment a steam raising plant will suffer from scale formation and corrosion. At best, this lead to poor quality steam, reduced efficiency, shorter plants life and an operation which is unreliable. At worst it can lead to catastrophic failure and the loss of life. One way to overcome this problem is to apply a genuine, stringent legal, testing, training and certification system of supervision to minimize or prevent such occurrence.

2 1.3 Objectives of the research: 1.3.1 General objective: To highlight the importance of proper water treatment for feed water before entering the boiler .

1.3.2 Specific objectives: 1. To analyze and determine the chemical constituents of the boiler feed water. of various of boilers with different purposes. 2. To evaluate and compare the results of the analysis of the constituents, first with each boiler location to another and then with respect to standard specification. 3. To correlate between the values of these constituents in the water samples and the problems that may happen to the boilers. 4. To verify the effect of water hardness on performance of boilers.

3 CHAPTER TWO LITERATURE REVIEW 2.1 Structure of water:

Chemically water comprises both elements oxygen and hydrogen (H2O). The two hydrogen atoms are attached at an angle of 105. Oxygen has only two unpaired electron atoms which occupies two corners of a tetrahedron. The other two corners of the tetrahedron are occupied by unshared pairs of electrons. C.H.Cho etal,.(1996)

Fig (2-1): Water molecule and representation of four sp3

The use of sp3 hybrid orbitals in explaining the bonding in molecules which obey the octet rule is represented by four sp3 hybrids. Almost all hydrogen atoms in water have an atomic weight of 1. The American Chemist Harold Clayton discovered in 1932 the presence of small amount (1 in 6 000) of so-called heavy water or deuterium oxide (D2O) in naturally occurring water. Deuterium is the hydrogen isotope with an atomic weight of 2. In 1951 chemist Aristed Groose discovered that naturally occurring water contains also minute traces of tritium (T2O); tritium is the hydrogen isotope with atomic weight of 3, King,R,Bruce (2000) 2.2 Physical and chemical properties of water: Water is considered as the most abundant matter on the earth, in its liquid 3 condition. It covers /4 of the earth surface. Pure water is a transparent liquid, but since it passes through various conditions its colour is changed according to the nature through which it passes. At atmospheric pressure (760 mm of mercury) the freezing point of water is 0C and its boiling point is 100C. Water attains its maximum density at a temperature of 4C and expands upon freezing. Like most other liquids water can exist in a super cooled state 4 that is it may remain liquid although its temperature is below its freezing point. Water can easily be cooled to about (- 25C) without freezing. In an industrial organization water is used as a source of steam which is used for energy storage that is introduced and extracted by heat transfer usually through pipes. Steam is a capacious reservoir for thermal energy, because of water high heat of evaporation (or evaporization). Steam is the technical term for water- vapour, the gaseous phase of water which is formed when water boils. If heated further it becomes superheated steam. The enthalpy of evaporation is the energy required to turn the water into gaseous form when water boils. It increases in volume by 1600 times at standard temperature and pressure. This change in volume can be converted into mechanical work. The enthalpy of evaporization (evaporation) also known as the heat of evaporation is the energy required to transfer a given quantity of a substance into a gas at a given pressure (often atmospheric pressure). It is often measured at the normal boiling point of a substance. The enthalpy of evaporization can be viewed as the energy required to overcome the intermolecular interactions in the liquid. Helium (He) gas has a particularly low enthalpy of evaporization 0.0845 kj/mole as the Vander Waals forces between the helium atoms are particularly weak. On the other hand in liquid water the molecules are held together by relatively strong hydrogen bonds and the enthalpy of evaporization for water is 40.65 k j/mole and is more than five times the energy required to heat the same quantity of water from 0C to 100C, Howard etal.,(1997). 2.3 Occurrence of water: Water is the only substance that occurs at ordinary temperatures in all three states of matter, that is a solid a liquid and a gas. As a solid or ice it is found as glaciers and ice caps on water surfaces in winter as snow, hail and frost. It occurs in the liquid state as rain clouds formed of water droplets and on vegetation as dew . In 3 addition it covers /4 of the earth surface in the form of swamps , lakes, rivers and oceans. As a gas or water vapour it occurs as fog , steam and clouds. Atmospheric vapour is measured in term of relatively humidity which is the ratio of the quantity of vapour actually present to the greatest amount possible at a given temperature. Water occurs as moisture in the upper portion of the soil surface in which it is held by capillary action to the particles of the soil . In this state it is called bound water. Under the influence of gravity water accumulates in rock interstices beneath the surface of

5 the earth, as a fast ground water reservoir supplying wells and springs and sustaining the flow of some streams during periods of drought. 2.4 Natural water cycle: Hydrology is the science concerned with the distribution of water on the earth, its physical and chemical reactions with other naturally occurring substances and its relation to life on earth .The continuous movement of water between the earth and the atmosphere is known as the hydrological cycle. Under several influences of which heat is predominant, water is evaporated from both water and land surfaces and is transpired from living cells. This vapour circulates through the atmosphere and is precipitated in the form of rain or snow. On striking the surface of the earth, the water flows two paths. In amount determined by the intensity of the rain and the porosity permeability thickness and the previous moisture content of the soil, one part of the water termed surface runoff, flows directly into rills and stream and hence into ocean or land locked bodies of water – the remainder filterates into soil. A part of the in- filterated water becomes soil moisture which may be evaporated directly or may move upwards through the roots of vegetation to be transpired from leaves. The portion of the water that overcomes the forces of cohesion and adhesion in the soil profile percolates downwards accumulating in the so-called zone of saturation to form the ground water reservoir, the surface of which is known as water table. Under natural conditions the water table rises intermittently in response to replenishment or recharge and then declines as a result of continuous drainage into natural outlets such as spring, C.J.Vorosmarty,(2010) 2.4.1 Evaporation – transpiration, condensation: Evaporation is the process by which water in the ocean and on land changes to water vapor and enter the atmosphere as a gas. Evaporation from plants is called transpiration. The evaporation rate increases with temperature, sunlight intensity, wind speed and ground moisture and it decreases as the humidity of air increases. Water vapor cools as it rises, condensing into droplets of water to form clouds. Precipitation falls from the clouds and the water returns to earth continuing the hydraulic cycle. Almost all the water on earth has passed through the water cycle; countless times very little water has been created or lost over the past billion years, Silbrg,Martin A.(2006).

6 2.5 Composition of water: Because of its capacity to dissolve numerous substances in large amount, pure water rarely occurs in nature. During condensation and precipitation rain and snow absorb from the atmosphere varying amount of carbon dioxide or other gases as well as traces of organic and inorganic materials .In addition precipitation carries radioactive fallout to the earth surface in its movement and through the earths crust. Water reacts with minerals in the soil and rocks. The principal dissolved constituents

  of surface and ground water are the sulphates ( SO4 ) chlorides (Cl ) and

1 bicarbonates ( HCO3 ) of sodium and oxides of calcium and magnesium. Surface water may also contain domestic sewage and industrial wastes. Ground from shallow wells may contain large quantities of nitrogen compounds and chlorides derived from human and animal wastes. Water from deep wells generally contains only minerals in solution. Almost all supplies of natural drinking water contain fluorides in varying amount the proper proportion of fluorides in drinking water has been found to reduce tooth decay. Sea water contains in addition to concentrated amount of sodium chloride (NaCl) salts, many other soluble compounds as the impure water of rivers and stream are constantly feeding the oceans. At the same time pure water is continuously lost by the process of evaporation and as a result the proportion of the impurities that give the oceans their saline characters in increased Pedro Fierro and Nyer, (2007) 2.6 Wet textiles engineering (WTE): Wet processing engineering is one of the major streams in textile engineering refers to textile chemical engineering. There are many activities included under this name. The medium in which these activities are carried out is an aqueous medium and water plays a significant role in these processes. The water must possess certain properties to be suitable in this respect and after each process huge amount of water is discharged as water effluent to surrounding environment. The boiler feed water constituents unless carefully treated monitored and conditioned they well impose serious problems concerning the performance of the steam boiler and the cost of production as well, (Dr.S.P.Mishra,june(2010). 2.6.1 Wet textiles processing (WTP): Wet textile processing in industry is the production processes that require significant quantities of water and heat. Heat in the form of steam is widely used in these processes. It can be direct heating where life steam heat a bath of water to 7 maximum possible degree, or by heat transfer through pipes. Boilers are the devices used for production of steam at different levels of pressure. Wet textile processing is the process that use any type of treatment. It is usually done on the manufactured assembly of interlacing , filament and /or having substantial surface (planar) area in relation to its sickness and adequate mechanical strength to give a cohesive structure. In other words wet process is done on manufactured fabric. The processes are carried out in aqueous stage and thus is called wet process. It usually covers pretreatment, , printing and finishing. All these processes required aqueous medium which is created by water. A massive amount of water is required in these processes. It is estimated that an average, almost 100 liters of water is used to process 1 kg of textile goods. Not all water can be used in textile process, it must have certain properties, quality, and attributes for being used in textile processes. This is why water is a pure concern in wet process engineering,(Dr.S.P,Mishra,June(2010) Most water used in the is from deep well water which is found 800 ft below the surface level. The main problem here is water hardness caused by the presence of calcium and magnesium. Iron, aluminum and copper salts may also contribute to the hardness but their role is much less. Using hard water in wet processes can cause problems such as the formation of scale in boilers, reaction with soap and detergent, reaction with and problems due to iron. Water hardness can be removed by boiling process, liming process, soda lime process, base exchange or synthetic ion process. Rain water may be used in wet processes as it is less likely to cause the problems associated with water hardness. Wet textile processing can be divided into three main stages which are pretreatment, coloration (dyeing and printing) and final finishing. 2.6.1.1. Pretreatment processes : They include singeing, , scouring, bleaching and mercerizing. Singeing is carried out to remove the loose hairy fibers, protruding from the surface of the cloth, thereby giving it a smooth, even and clean looking face. It is essential process when the goods will be subjected to mercerizing, dyeing and printing to obtain best results. These results will increase wettability dyeing characteristics, improve reflection, no frosty appearance, better clarity in printing. It improves visibility of the fabric structure, less pilling. Singeing is performed only in the woven fabric.

8 Desizing is the process of removing material from the fabrics. It is removed by making it water soluble and washing it by warm water. Desizing can be done by either hydrolytic method (rot steep, acid steep or enzymatic steep) or the oxidative method (chlorine, ). The cloth may be steeped in dilute acid and then rinsed or enzymes may be used to break down the sizing material that cover the warp . Scouring is a chemical washing carried out on fabric to remove natural wax and non-fibrous impurities (e.g. remains of seed fragments) from the fibers and any added soiling or dirt. Scouring is usually carried out in iron vessels called kiers. The fabric is boiled in an alkali which forms a soap with free fatty acids (saponification). A kier is usually enclosed so that the solution of the sodium hydroxide can be boiled under pressure, excluding oxygen which would degrade the cellulose in the fabric. Preparation and scouring are prerequisite to most of the other finishing processes Bleaching improves whiteness by removing natural coloration and remained traces of impurities from the cotton. It can be carried out using an oxidizing agent such as dilute hydrogen peroxide or dilute . If the fabric is to be dyed a deep shade then lower levels of bleaching are acceptable. However for white bed sheets and medical applications then the highest levels of whiteness and absorbency are essential. Mercerizing is a treatment for cotton fabric and threads that gives fabrics or yarn lustrous appearance and strengthens them. The fabric is treated with sodium hydroxide solution to cause swelling of the fibers. It takes place under tension and the alkali must be removed before the tension is released or shrinkage will take place. The result is improved luster, strength and affinity. 2.6.1.2.Coloration of textiles : Dyeing is the addition of colors to textile products like fibers, yarns and fabrics. It is normally done in a special solution containing dyes and particular chemicals. The dye molecules may be bonded to the molecules. Temperature and time controlling are two key factors in dyeing. There are two main classes of dyes for natural and man-made fibers. Dyeing can be carried out to fibers, yarn and fabric. Fabric dyeing is also known as piece dyeing i.e. after the fabric is being constructed. It is economical and most common method of dyeing solid colored fabrics. There are many types of dyestuff including acid, basic, direct, , vat, reactive, azoic, sulpher and disperse, each of which is used on a particular kind of material with 9 special kind of technique. Dyeing methods vary as they include two main types, exhaust and continuous. In exhaust dyeing a jigger or a beam dyeing machine is used. Here the fabric is threaded to two rollers and continuously allowed to pass through a dye liquor from one end to another till the liquor is exhausted. In continuous dyeing the fabric in open stretched form is passed through an impregnating dye bath and then allowed to pass through an squeezing rollers to obtain the required amount of dye pick-up. The fabric is then passed through drying chambers. Dr.S.P.Mishra, June(2010) is a process of applying colors to fabric in definite patterns or design. In properly printed fabric the color is bonded to the fibers so as to resist washing and friction. Textile printing is related to dyeing but while in dyeing the whole fabric is uniformly covered with one color, in printing one or more colors are applied to it in certain parts only and in sharply defined patterns. Beside that the method of printing so described is simply adopted a multicolor patterns on slightly tinted fabric but certainly not on deep colored fabric. For then the ground would interfere with the colored pattern printed upon it. Many of the most attractive fabric are those which have colored pattern on a ground color. In printing, wooden blocks, stencils, engraved plates, rollers or silkscreen can be used to place colors on the fabric. Colorants used in printing contain dyes thickened to prevent the color from spreading by capillary attraction beyond the limits of the pattern or design. 2.6.1.3 Textile finishing : It is the term used for series of processes to render textile goods fit for their purposes or end-use and/or improve serviceability of the fabric. Finishing is carried out to improve the quality and appearance of a fabric. Fabric may receive considerable added value by applying one or more finishing process. There are innumerable steps leading to finished products, each having a number of complex variables and every lot is like a new, and much depends on the well-trained manpower rather than modern machine and technology. However development is taking place at a rapid pace to satisfy the user with quality product and competitive price. This in turn will impart cost competitiveness. More functional finishes are being developed, however the trend is to use more mechanical finishes than chemical finishes. The key success in textile wet processing technology will be an indication of highly trained manpower at lucrative wages in structural manner. The popular finishing processes are : 10 Raising, calendaring, crease-resistance, filling, softening, water repellency, moth-proofing, mildew-proofing, flame retardant, antistatic and soil resistance. is intended to upgrade the fabric handle and to impart a smooth, silky touch to the fabric. Raising is the lifting of a layer of fibers of the fabric. It results in a lofty handle. Crease-resistance a process which makes the crease formation and shrinkage during washing and folding much more difficult. In most finishing processes of cotton the following steps are followed. 1. Padding the material with a solution containing a condensation polymer, precursor and a suitable polymerization catalyst. 2. Drying and curing in a stenter frame to form cross links between the adjacent polymer chains. Softening and smoothing agents are often applied not only to improve the handle, but also to compensate tear strength and abrasion resistance. Every resin finish contains surfactants as emulsifier, wetting agents and stabilizers. These surface- active substances are necessary to ensure that the fabric is wet rapidly and thoroughly during padding and the components are stable in the liquor, Dr.S.P.Mirsha,(2010). 2.6.2 The role of water in wet – textile processing (WTPs): Water resembles everything to wet textile processing. It plays a major role in the wet pressing. Actually desizing of fabrics is carried out with plenty of water. The mechanism of desizing is solely depending upon the characters of water. It allows the desizing material (usually enzymes) to penetrate the fabric molecules and destroy the sizing material. Scouring of cotton grey fabric takes place with caustic soda dissolved in plenty of water. In the bleaching process the same technique is adopted using hydrogen peroxide. Water is a universal solvent that dissolves many substances in it. Colors and dyes dissolved in water are used to dye fabric materials. The water carrying the dye molecules has the ability to penetrate deeply into the fabric distributing the colour evenly throughout the fabric. In printing the paste carrying, colour is also dissolved in plenty of water. The colour paste can not be applied alone to the fabric unless it is dissolved in water. Water in its different forms is widely used in wet – textile processing. Boiled water is used in the scouring process to remove all impurities attached to the cotton fibres. Again boiled water is needed to wash off these impurities after being released from the fabric. Unfixed dyes after fixation of the colours also need boil washing Alnagaawi, (1980).

11 Hot water says at (60C) or even cold water may be enough for the fixation of certain classes of dyestuffs. Cold water (15C) is required to undergo mercerization of cotton fabric to achieve a number of quality factors to the fabric. Steam (at 100C) or even superheated steam (at 170C) maybe used in the fixation of dye stuff. Water in the form of steam may be applied directly to heat a water bath for washing and cleaning purposes or indirectly by passing steam through pipes to raise the temperature to certain degree without changing the liquor to good ratio (L.G.R). Water hardness due to the presence of calcium and magnesium ions dissolved in the water may give rise to problem during wet – processing. According to Dr. A. Alnagaawi, (1980) (In Arabic). They react with sodium soap dissolved in water and turn it into lime soap. The latter forms with fatty acid – present in dirt the salt of calcium and magnesium which are insoluble in water. The lime soap or the soap of calcium and magnesium is viscous substances that easily irregularly precipitate on fabric or yarn and also attracts soil particles .It causes uneven dyeing because it resists the entrance of dye molecules and these results in poor rubbing fastness, Alnagaawi, (1980). 2.6.3. The properties of water required by (WTPs): Water has to possess certain qualities to be suitable for any type of processing activity. Dyeing in particular requires the water to be free from mineral particles. If the water is hard the situation becomes worse because Ca and Mg cations may react with the dye molecules rendering them less active. Depending on the type of dyestuff used and the process adopted, the pH medium of water varies from acidic to alkaline. In chlorine hard water contains iron particles which can combine with chlorine bleach to produce iron oxide or rust which stains clothes. In general water used in WTPs should be colorless, odorless, hardness less than 5, pH greater than 7, E.C and TDS values should be minimum. 2.6.4. The effect of effluent (WTPs) on environment: WTP units discharge their effluent into certain municipal waste water treatment systems. If there is no such treatment system connected to the WTP unit then the environment receiving such effluent will be seriously affected. Although some WTPs discharge their effluent into some kind of treatment system, others discharge their effluent haphazardly without treatment. Textile mill effluents (TMEs) are waste water discharge from textile mills produced during wet processing such as scouring, carbonizing etc... They are complex

12 mixtures of chemical waste whose composition varies overtime and from one mill to another. Untreated TMEs may include high concentration of nonyl phenol (NP) and its ethoxylates (NPEs), suspended solids, metals and other organic matters. Untreated TMEs can also exhibit extreme pH variation and elevated temperature, US. Environmental Protection Agency(EPA),Aug.(2010) . 2.6.5. The effect of the constituents of the boiler feed water on production cost Steam is used in a variety of application in industry namely, process heating and power generation. Process heating accounts for an average of more than 60% of thermal energy use. Process heating also accounts for significant portion of controllable operating cost. It is one of the few areas of opportunities where management can reduce operating cost and improve profit. Boiler feed water containing mineral particles may be responsible for serious limitation on the performance of the steam boilers due to corrosion and scales formation. Table (2.1.): Costing &Production department, Blue Nile Textile Week Quantity of furnace Production achieved Profit realized (% ) consumed (ton) (mt ) 1 35 200,000 15.00 2 60 350,000 9.32 3 50 190,000 9.90 4 50 198,000 10.41 Source: Blue Nile Textile, wet processing (June, 1988).

A work study carried out by production department, Blue Nile Textiles Factory (July- Dec 2006) showed clearly the direct correlation between boiler performance and production targets. Production targets necessarily affect profit and loss account. In one and the same fiscal year the analysis of production cost can be summarized in the following equation (2.1): 1 2 3 4 5 6 Fabric Dyes & Power Administ. Profit Sales Cost + chemical + Cost + Cost + realized = Value cost

30% 20% 20% 15% 15% 100% Source: Blue Nile Textile Factory (1988)

13 If the above mentioned percentage are maintained for each item and knowing that item (1) – (2) – (4) – (6) are fixed cost items and item (3) – (5) are variable item cost. The items (3) and (5) are interdependent and if any one increases the other will decrease. Item (3) - power cost- comprises electric power and furnace oil consumption. Increase in consumption of furnace oil due to problems associated with the boiler performance will definitely decrease the profit. 2.6.6. Researches and workshops: 2.6.6.1. Workshop I: One of the important research related to the topic is the training program (in the form of workshop) conducted by the research and industrial consultation center, Khartoum, Sudan during the period 31/05/2003 – 06/06/2003 concerning boiler feed water and steam boiler for a number of companies using steam boiler in their work. The outcomes of this workshop are the following requirements and should be considered carefully during running the boiler: 1- The level of the water in the boiler must be revised throughout running the boiler to ensure no decrease or increase in the allowed level of water. 2- To ensure working efficiency of the safety valves and to revise the pressure on the steam pressure gauges. 3- The valves distributing the steam should be opened gradually, one after the other so that heating of the steam pipes can take place slowly and cannot be subject to high heat suddenly. 4- To make sure not to increase or decrease the steam pressure of the boiler within short periods and big rates, otherwise the parts of the boiler may be rendered collapse as a result of high temperature. 5- The ideal feeding of the boiler takes place by delivering hot water to the boiler, a quantity parallel to that water which has been boiled and by doing so we can guarantee the stable level of water inside the boiler. 6- In accordance with the probability that the boiler feed water used contains different chemical material that may percolate to the bottom of the boiler in the form of solid materials and this can affect the efficiency of the boiler in many ways. It may lead to the combustion of the bottom of the boiler because of the direct flame or may be responsible for the corrosion of the metallic boiler parts.

14 It is therefore highly recommended to analyze the water before use. 7- In high pressure boiler, feed water should be analyzed every certain number of hours during work. This will allow the knowledge of the quality and type of the deposited material and to put forward a suitable treatment process. 8- If any precipitate is observed in the glass-tube gauge of the water level, this may be an indication of big quantity of precipitate in the boiler. 9- If oil droplets appear on the surface of the water inside the glass-tube gauge, at this moment one needs immediately to stop the boiler clean it and remove the source of oil. 10- If any leakage of water or steam is discovered at any part of the boiler this may be an indication of weakness or damage of that area. Therefore one has to stop the boiler immediately. Booklet issued by the research and industrial consultation center, Khartoum Sudan (2003).

2.6.6.2. Workshop II: A workshop under the name; Boiler operation, maintenance and safety will be held in a seminar form in Dublin, Scotland on 17 & 18 Nov. 2015. The seminar is designed to give a broad introduction to boilers, including everyday operation and important safety process. Understanding of basic boiler operation and safety is the goal of the seminar. In addition the participants will learn about combustion and heat transfer fundamentals, the different types of boilers and basic burner control. How and when to schedule preventive maintenance, how to avoid common boilers accidents and how to operate boiler safely and efficiently. Also the seminar will cover areas concerned with boiler feed water, its constituent and the essential need for a proper water unit to remove all foreign elements from the water. The seminar will highlight the importance of the use of the ancillaries supplemented with the boiler like deaerator, scavenger, alkalizer and economizer. The methods of treatment will be discussed thoroughly, beside the use of modern technology so that the water entering the boiler should be perfectly treated and conditioned in order not to harm the boiler. Maintenance Resource Division, e-mail info@esstle ae.

15 2.6.7. New development in the chemical detection of the boiler feed water: The problems imposed by the constituents of the boiler feed water on the efficiency and performance of the boiler feed water encouraged many industrialist to implement an effective monitoring and control system for the detection of chemical in the boiler feed water. This system involves an in-line process analytics of high sensitivity sensors or microprocessor gauges fixed at different parts of the water treatment units to detect with accuracy, flexibility and at low cost of operation of the water chemistry measurements. They include the following detectors: - pH sensor or microprocessor to maintain measurement continuity under low range of conductivity. - Dissolved oxygen sensor or microprocessor to monitor the level of oxygen gas in the water in ppb. - Electric conductivity microprocessor with exceptionally wide range measurement and accuracy. - Total hardness detecting microprocessor showing the values of the total

hardness of the water under question in ppm CaCO3, total hardness. Obviously many modifications and variation of the chemical detectors can be practiced to obtain quickly reliable and accurate chemical check results. In case of any discrepancy from the standard specifications required by the boiler feed water the whole system will stop and resume work only after the discrepancy is corrected, (Babcock and Wilcox, 2007). 2.6.8 Characteristics of boiler feed water: Water absorbs more heat for a given temperature rise than any other common inorganic substance. It expands 1600 times as it evaporates to steam at atmospheric pressure. The steam is capable of carrying large quantities of heat. These unique properties of water make it an ideal raw material for heating and power generation processes. All natural waters contain varying amounts of dissolved and suspended matter and dissolved gases. The amount of mineral dissolved in water varies from 30 g/L in sea water to anything from 0.005 to 1500 mg/L in fresh water supplies. Since water impurities cause boiler problems, careful considerations must be given to the quality of the water used for generating steam, (Babcock and Wilcox, 2007). The composition of boiler feed water must be such that the impurities in it can

16 be concentrated a reasonable number of times inside the boiler without exceeding the tolerance limits of the particular boiler design. If the feed water does not meet these requirements, it must be pretreated to remove the impurities. Impurities need not to be removed completely in all cases, however, since chemical treatments inside the boiler can effectively and economically counteract them. Feed water purity is the matter of quality and nature of impurities. Some impurities such as hardness, iron and silica are of more concern than sodium salts. The purity requirement for any feed water depends on how much feed water is used as well as what the particular boiler design, pressure, heat transfer, etc. can tolerate. Feed water purity requirements therefore can vary widely. A low pressure fire tube boiler can usually tolerate high feed water hardness with proper treatment while, virtually all impurities must be removed from water used in some model high pressure boilers. Only relatively wide ranges can be given as to maximum levels of alkalis, salts, silica, phosphates, etc. in relation to working pressure. The actual maximum levels must be obtained from the boiler manufacturer who will base them on the characteristics of the boiler in question, (Babcock and Wilcox, 2007).

17 Table (2.2): Chemical requirements of feed water and boiler water for low and medium pressure boilers Requirements for boiler pressure Characteristics Up to 20 kg/cm2 21 to 39 kg/cm2 40 to 59 kg/cm2

Feed water:

a. Total hardness as CaCO3 mg/L 10 1 0.5 (Max.) b. pH value 8.5 – 9.5 8.5 – 9.5 8.5 – 9.5

c. Dissolved Oxygen 0.1 0.02 0.01

d. Silica as [SiO2] 0 5 0.5 mg/L (Max.) Boiler water:

a. Total hardness (of filtrated sample) as Not detected CaCO3 mg/L b. Total alkalinity as CaCO3 mg/L 700 500 300 (Max.) c. Caustic alkalinity CaCO3 mg/L 350 200 60 (Max.) d. pH values 11.0 – 12.0 11 – 12 10.5 – 11.0

e. Residual Na2SO3 30 – 50 20 – 30 0 mg/L

f. Ratio Na2S04 / caustic alkalinity Above 2.5 (as NaOH) Source: Bureau of Indian Standard. Boiler Section Committee CDC, 57 (1983)

18 2.7 Properties of ground water: 2.7.1 Electrical conductivity (E.C): It is the measure of the ability of water to conduct electric current that passes through it. E.C is directly proportional to the amount of dissolved solids in water, and it is an excellent indicator of total dissolved substances (TDS) in water. Electric conductivity is expressed in micro mesh per centimeter (moh/cm), Standard method ASTM E 11111033. Twort et al., (2009). 2.7.2 pH: It is the negative logarithm of the hydrogen ion concentration pH values is measured by pH meter, to determine the acidity or the alkalinity or the neutrality of the water. Reagents: Standard buffer solution of pH = 4, 7, 9. Buffer tablets of pH = 4, 7, 9 Each tablet was dissolved in 100 ml distilled water to form the buffer specified. Procedure: The pH meter was calibrated by the buffer solutions of pH = 4, 7, 9 at 25C. pH of the samples were recorded, (Twort et al., (2009).

2.7.3 Total alkalinity: The alkalinity of water is the capacity of the water to accept protons. It is usually imported by the bicarbonates, carbonates and hydroxide components of a natural or treated water supply. It roughly refers to the amount of bases in a solution that can be converted to uncharged species by strong acid. It is determined by titration with standard solution of strong mineral acid, to the successive bicarbonate and carbonic acid points indicated electrometrically or by means of colour phenolphthalein, Twort et al.,( 2009).

19 2.7.4 Total dissolved solids (TDS): Solids refer to matter suspended or dissolved in water or dissolved in waste water. Solids may affect or effluent quality adversely in a number of ways. Water with high dissolved solids is generally inferior. Highly mineralized water is unsuitable for many industrial applications and also induces an unfavorable physiological reaction in transient consumer, Twort et al., (2009). Total dissolved solids (TDS) is a term applied to the material residue left in the vessel after evaporation of a sample and its subsequent drying in an oven at a defined temperature. Total solids include total suspended solids. The portion of total solids retained by fitter and the total dissolved solids, the portion that passes through the filter. Fixed solids is a term applied to the residue of total suspended or dissolved solids after heating to dryness for specific time and specific temperature the weight loss on ignition is called volatile solids Twort et al., (2009). 2.7.5 Hard water: Hard water is water that has high mineral contents (in contrast to soft water). Hard water has content of Ca++ and Mg++ (ions). Hard water is generally not harmful to one's health but can pose serious problems in industrial setting. Hard water is monitored to avoid costly breakdown in boilers. The hardness of water is often indicated by the not – formation of lather with soap agitated with the sample of water.Standard test method D1126-12 for water hardness, Twort et al.,( 2009). 2.7.5.1 Consequences and problems caused by using hard water in wet textile processing:  Precipitation of Soaps.  Re-deposition of dirt and insoluble soaps on fabric being washed. This can cause yellowing and lead to un-levelled dyeing and poor handling.  Precipitation of some dyes as Ca and Mg salts that react with them.  Seal formation on equipment and in boilers.  Reduction in activity of enzyme used for desizing.  Decrease the solubility of sizing agents.  Coagulation of some types of printing paste.  Incompatibility with chemicals in finishing.  Decomposition of bleaching bath.  In mercerization form insoluble metal oxide and reduces absorbency and luster Colin, (2002). 20 2.7.6 Sources of hardness: Temporary hardness is a type of water hardness caused by the presence of dissolved minerals of calcium and magnesium carbonate. When dissolved these minerals yield calcium and magnesium cations (Ca++, Mg++) and carbonate and

  bicarbonate anions ( CO3 , HCO3 ). The presence of metal cations makes the

 hardness. However unlike the permanent hardness caused by the sulphate ( SO4 ) and chlorides ( Cl  ) compound, the temporary hardness can be reduced either by boiling the water or by the addition of lime (Ca (OH)2) through the process of lime softening. Boiling promotes the formation of carbonate from the bicarbonates out of solution.

Boil Ca (HCO)3)2 Ca CO3 + CO2 + H2O (aqueous) (solid) (gas) liquid) Colin, (2002) 2.7.7 Effect of hard water: Boilers are essentially devices for transferring liquid water to steam by heating the water. Boiler incorporate a fire – box or a furnace in order to burn the fuel and generate heat. The heat initially transferred to water to make steam. A fire – tube boiler consists of a tank of water perforated with pipes. The hot gases from burnt furnace oil run through the pipes to heat the water in the tank. Any remaining heat in the combustion gases can either be evacuated or made to pass through an economizer the role of which is to warm the feed water before it enters the boiler. In a real boiler the goal is to extract every bit of heat from the burning fuel to improve efficiency. Boiler in industrial application resembles a major role in production. It supplies various units with direct or indirect steam for heating. The supply of steam should be continuous, adequate and economical. The consumption of fuel for boiling the water should be within economical range to maintain and realize profit in production. When the water evaporates the dissolved solids are left behind and frequently form scales and deposits. Deposition on heat transfer surfaces can cause the metal to overheat leading to premature failure. The deposit is a solid coating material of lime substance normally seen on surfaces of boilers and their pipes. It is a result of precipitation of calcium and magnesium salts found in the hard water. Sometimes other salts of iron (Fe++) and cobalt (CO++) are found beside calcium and magnesium but in general the hardness of water is known to be due to calcium and magnesium. In

21 addition to this hardness there are calcium sulphate and magnesium sulphate (Ca

SO4), (Mg SO4), Colin,(2002). The more the resistance to transfer heat from the hot pipes of the boiler to the surrounding water the less the transfer of heat thus the quantity of heat lost will be more and the boiler has to be supplied with more fuel and consequently this will increase the cost of running the boiler. Thus heated hard water which forms scales of calcium and magnesium minerals (lime scales deposit) can contribute to the inefficient operation or failure of water–using appliances. Pipes may become clogged with scales that reduce water flow and ultimately requires pipes replacement. Lime scale has been known to increase energy bill by 25%, Colin, (2002). Table (2.3): Classification of water hardness

Units Classification mg / L or ppm Grain / Gallon Soft 0 – 17.0 0 – 1 Slightly hard 17.1 – 60 1 – 3.5 Moderately hard 61 – 120 3.5 – 7.0 Hard 120 – 180 7.0 – 10.5 Very hard 180 – over 10.5 and more Source: Water hardness, (1980) Lisle, Illinois: The water quality research council

2.7.8 Boiler types and classification: 2.7.8.1 Boilers A gas/oil central heating boiler (heat generator) is like the engine of a car, provides the heat that the facility needs, to warm itself up. The size of the boiler is matched to the size of the facility. If the boiler is over sized, the fuel bill will be excessive and if the boiler is under sized, it may not generate enough heat. The ideal size for an industrial boiler is one that just copes adequately with the requirement of the facility. The boiler consists of two parts: 1. Boilers / burner combustion (the parts producing the heat). 2. Piping with pumps and values (the parts distributing the heat). Boilers are classified as high pressure or low pressure and steam boiler or hot water boiler. Boilers that operate higher than 15 psi are called high pressure boilers. A hot water boiler strictly speaking is not a boiler. It is a fuel fired hot water heater.

22 Because of its similarities in many ways to a steam boiler the term hot water boiler is used. Heating boilers are also classified as to the method of manufacture, i.e. Casting (cast iron boilers) or fabrication (steel boilers), those that usually use iron , bronze or brass in their construction and those that are fabricated use steel ,copper or brass with steel being the most common material.

2.7.8.2 Steel boiler Steel boilers are generally divided into two type; Fire tube and water tube.

2.7.8.2.1 Fire- tube Boilers In the fire tube boilers combustion gases pass through the inside of the tubes with water surrounding the outside of the tubes. The advantages of a fire- tube boiler are its simple construction and less rigid water treatment requirements. The disadvantages are the excessive weight per pound of steam generated, excessive time required to raise steam pressure, because of the relatively large volume of water, and inability to respond quickly to load changes, again due to the large amount of water volume. The most common fire- tube boilers used in heating applications are often referred to as {scotch} or {scotch marine} boilers as this boiler type was commonly used for marine service because of its compact size. The name fire tube is very descriptive. The fire or hot flue gases from the burner is channeled through tubes that are surrounded by the fluid to be heated. The body of the boiler is the pressure vessel and contains the fluid. In most cases this fluid is water that will be circulated for heating purposes or converted to steam for process use. Every set of tubes that the flue gas travels through before it makes a return is considered as ‘a pass’. So a three-pass boiler will have three sets of tubes with the stack outlet located on the rear of the boiler. A four – pass boiler will have four sets and the stack outlet at the front. Fire tube boilers are relatively inexpensive, easy to clean and compact in size. They are available in sizes from 6x105 to 5x107 Btu/hr. The tubes can easily be replaced and they are well suited for space heating and industrial process application. However, their disadvantages include unsuitability for high pressure applications more than 250 psig and their limitation for high capacity generation.

23

Fig. (2.2): Fire-tube boiler Source;-http://en.wikipedia.org/wiki/fire tube boiler

Fig. (2.3): Work of steam engines (fire -tube boiler) Source:-http://en.wikipedia.org/wiki 2.7.8.2.2 Water tube boilers: In a water tube boiler the water is inside the tubes and combustion gases pass around the outside of the tubes. The advantages of a water tube boiler are a lower unit weight per pound of steam generated, less time required to raise steam pressure, a greater flexibility for responding to load changes and greater ability to operate at high rates of steam generation. A water tube design is the exact opposite of a fire tube. 24 Here the water flows through the tubes which are incased in a furnace in which the burner fires. These tubes are connected to a steam drums and mud drum. The water is heated and steam is produced in the upper drum. Large steam users are better suited for the water – tube design. The industrial water- tube boiler typically produces steam or hot water primarily for industrial process application. Water –tube boilers are available in sizes far greater than a fire – tube design, up to several million pounds per- hour of steam. They are able to handle pressure up to 5000 psig. They recover faster than their fire – tube cousin and they have the ability to reach very high temperatures. However, their disadvantages include their high initial capital cost. Their cleaning is more difficult due to the design. There is no commonalty between the tubes, (G.F and Gillman, 2005).

Fig. (2.4): Schematic diagram of a marine-type water tube boiler

Source: https://en.wikipedia.org/wiki

25 2.8 Formation of rust in boilers: Rust is the degradation of metals by various actions. In rust certain parts of the boiler specially the surface containing the water will be turned into a brittle material. Rust is developed from the reaction of iron (Fe) that forms parts of the boiler. 2.8.1 Chemical rust:

2 Fe + O2 2 Fe O

2.8.2 Electrochemical rust:

+ H2O H + OH ++ - Fe + 2 (OH ) Fe (OH)2 2.8.3 Bacterial rust: It is the reaction between iron (Fe) and the gases liberated from the effect of bacteria on organic matter found in the water.

Fe + CO2 + H2O Fe (HCO3)2 2.9 Specifications of boiler feed water: It is the water used to supply (feed) the boiler to generate steam, or hot water. In a thermal power station, the feed water is usually stored, pre heated and conditioned in a feed water tank and forwarded into the boiler by a boiler feed water pump. 2.9.1 Boiler feed water conditioning: The feed water has to be specially conditioned to avoid problems in the boiler and downstream components. The water required for boiler feed purposes i.e for steam generation should be of very high quality and thus requires a lot of treatment. Untreated water containing impurities may lead to problems. 2.9.2 Boiler corrosion, deaerators and scavenger:

Corrosive components especially oxygen (O2) and carbon dioxide (CO2) gases have to be removed using deaerators. A deaerator is a device that is widely used for the removal of oxygen and other dissolved gases from the feed water to steam generating boiler. In particular dissolved oxygen in boiler feed water will cause serious corrosion, damage steam system by attacking the walls of metal piping and other metallic equipments and forming oxides. In dry oxygen iron (Fe) readily forms

iron (II) oxide, but the formation of hydrated ferric oxide (Fe III) i.e Fe2O3 (OH)x that mainly comprises rust, typically require oxygen and water. Water also combines with

26 any dissolved CO2 to form carbonic acid that causes further corrosion. Most deaerators are designed to remove the levels of 7 ppm by weight (0.005 cm3/L) or less. There are two basic types of deaerators, the tray type, a vertical domed deaeration section mounted above storage vessel. Boiler feed water enter the vertical deaeration section above the perforated trays and flows downwards through the perforation. Low pressure deaeration steam enters below the perforated trays flows upwards through the perforation. These must be a good contact and mixing between the steam and the boiler feed water. The steam strips the dissolved gas from the boiler feed water and exits via the vent at the top of the domed section. A vent condenser may be included to trap and recover any water entrained in the vented gas. The deaerated water flows from where it is pumped to the steam generating boiler section. Low pressure – steam heating which enters the horizontal storage vessel through a sparger pipe in the bottom of the vessel is typically provided to minimize heat loss. The deaerators in the steam generating systems use low pressure steam. Thomas C. et. al., (1997). Remnants of gases can be removed chemically or by the use of an oxygen scavenger. Oxygen scavengers are often added to the deaerated boiler feed water to remove any last traces of oxygen that were not removed by the deaerator. The most commonly used oxygen scavenger is sodium sulphite (Na2 SO3). It is very effective and rapidly reacts with any traces of oxygen to form the sodium sulphate (Na2 SO4) which is non – scaling. Other widely used scavengers are hydrazine (N2 H4) nitrites acetic acid (NTA) and ethylene diammine tetra acetic acid (EDTA).

Fig. (2.5): Oxygen Corrosion (Boiler) Source:- www chemical.com/oxygen- corrosion

27 2.9.3 Scales, sludge, deposits, sediment and fouling deposits: These phenomenon reduce the heat transfer in the boiler reduce the flow rate and eventually block boilers tubes. Any non – volatile salts and minerals that would remain in soluted form when the feed water is evaporated have to be removed because these would be concentrated in the liquid phase and require excessive "blow down" draining and to avoid the solid crystals "fallout". Even worse are the minerals that form scales.

Fig. (2.6) Calcium Carbonate Scale Source:-http://Wikipedia.org/wiki/lime scale 2.9.4 Foaming: Foaming results in water being carried from the boiler with the steam. It is influenced by several factors including. 1. Water level in the boiler. 2. Dissolved solid contents. 3. Suspended solids in the water. Foaming can be prevented or reduced by boiler blow down, a complete change of boiler water or by the addition of antifoamers. Use of antifoamers as routine part of internal treatment is a good practice. However the use of excessive amount can actually cause foaming and should be avoided. 2.9.5 Boiler blows down: When steam is generated, essentially pure water vapour is discharged from the boiler leaving all dissolved and suspended solids behind in the boiler; therefore the solid concentration in the liquid water in the boiler continuously increases as the water evaporates. In order to maintain the dissolved solid contents below the allowable level (maximum), some of the concentrated water must be removed from

28 the boiler and replaced with water containing a lower amount of dissolved solids, the water removed from the boiler in such case is called blow down. Any increase in the salinity of the boiler water as a result of excessive heating is monitored by conductivity measurement. When the maximum value is reached, blow down occurs. The blow down valve is opened and the boiler water is removed from the boiler. Low –salt feed water compensates for the loss in the boiler and reduces the boiler water conductivity. Part of the boiler water flow is guided across a cooler before reaching the conductivity probe in order to avoid overload of the probe to reduce sample water loss. Samples can be taken periodically making use of a motorized valve system. Thomas et al., (1997) Condensate recovery systems help reduce three tangible costs of producing steam . *Fuel-energy cost *Boiler water make-up *Boiler water chemical treatment. www.gewater.com/handbook/boiler 2.9.6 Condensate returns systems: Once steam leaves the boiler and is used for its intended purpose, steam will condensate and form hot water. The condensed water is called condensate and all or portion of it is usually returned to the boiler as feed water. The make – up water added to replace any losses of feed water which has to be demineralized and deionized water. Furthermore feed water has to be alkalized to a pH = 9 or more, to reduce oxidation and to support the formation of a stable layer (magnetite) on the water – side surface of the boiler, protecting the material underneath from further corrosion. This is usually done by dosing alkali agents into the feed water like (NaOH) caustic soda or volatile ammonia, Patton, (1987). Boilers are generally used to provide a source of steam or hot water to facility heating and process need. In steam and condensate boiler system, heat is added to water in a boiler causing the water to boil and form steam. The steam is piped to points requiring heat and as the heat is transferred from the steam to the building area or process requiring heat, the steam condensates to from condensate. In some very low pressure saturated steam heating applications , the steam distribution piping may be sized to slope back to the boiler so that the steam distribution piping also act as the condensate return piping (single- pipe system). In other low pressure application there may be steam supply piping and condensate return piping (two – pipe system)

29 although the condensate system is open to the steam system. In a typical packaged steam boiler operation, the boiler system may generate steam at about 150 psig for distribution throughout the facility and may be lowered to the operating pressure of equipment supplied through the point of use pressure reducing station. As heat is transferred from the steam, condensate is formed which collects in discharge legs until enough condensate is present to operate a trap that isolates the steam distribution system from the condensate system. In common facility heating application, the condensate system is arranged to drain the condensate to a certain condensate receiver or into local small receivers that pump the condensate back to the central condensate receiver. Thomas et al., (1997) 2.10 Boiler water treatment: Inter chemical treatment is usually necessary to provide insurance against scale and corrosion even if the water has been externally treated. When the boilers are operated at moderate pressure and the raw feed water is of good quality (low hardness, silica and turbidity), internal treatment alone will often be adequate. The boiler feed water treatment is normally done with the following chemicals  Hardness stabilizers  Deflocculating agents  Corrosion inhibitors  Oxygen binding agents e.g. hydrazine  pH value regulation (caustic soda , ammonia)  Defoaming agent Many of the problems of the boiler feed water quality and the subsequent steam side scales and corrosion damage were caused by inadequate water treatment. As from the objective of the research a comparative study between boiler feed water of different locations in the country was established .The data obtained included chemical study of the boiler feed water and the effect of the chemical constituent on the boiler condition and performance. A plant by plant study was conducted to specifically identify the problems associated with the boiler feed water and then after to specify the necessary upgrades. While the upgrading it requires capital expenditure, significant economic benefits may be derived from improved plant availability and reduction of maintenance cost. The useful lifetime of the plant boiler will be extended, Patton, (1986).

30 2.10.1 Phosphate treatment:

When soluble sodium phosphate (Na3 PO4) is added it reacts with calcium to form an insoluble precipitate of calcium phosphate (Ca3 (PO4)2), magnesium and silica they are precipitated as magnesium hydroxide (Mg (OH)2) and magnesium silicate (Mg SiO3) or calcium silicate (Ca SiO3). The alkalinity of the make – up is usually adequate to produce the necessary hydroxide (OH-) for the magnesium precipitation, although in some cases caustic soda must be added. The pH should be maintained above (9.5) both for magnesium precipitation and to ensure the formation -3 of less adherent precipitates, A reserve excess of (PO4 ) should be maintained. Sludge dispersant may be maintained in conjunction with phosphate to prevent adherence of the precipitated particles and to maintain the resultant sludge as non – adherent slurry, Patton, (1986). Sludge dispersants coat the finely divided particles as they are formed so they will not form large crystalline precipitates. Smaller particles will remain dispersed at the velocities encountered in most boilers enabling efficient removal during blow down.

2.10.2 Soda ash and caustic treatment:

In this process sodium carbonate (Na2 CO3), sodium hydroxide (Na OH) or both are added to the boiler to supplement the alkalinity supplied by the make – up water which is not softened. The sodium carbonate addition results in the +2 precipitation- of calcium ions (Ca ) as calcium carbonate (Ca CO3). The addition of caustic soda elevates the pH causing the precipitation of magnesium and silica as magnesium hydroxide Mg (OH)2 and magnesium silicate, Patton,( 1986).

2.10.3 Chelating agents: Chelating agents are natural, such as EDTA which form soluble complex ions with calcium and magnesium. Thus precipitation is prevented and the calcium and magnesium ions are effectively maintained in solution. The cost of chelating agents limit their use to very low hardness feed water, (usually below 5 ppm) (Applied Water Technology) Patton, (1986).

31 2.10.4 Zeolite or base – exchange process: Zeolites are hydrated silicates of sodium and aluminum with the general formula as below:

[(Na2O)x . (Al2O3)y . (SiO2)z . (H2O)n] These compounds occur in nature. They can also be fabricated and in the latter case they are known as base – exchangers or ion – exchangers. A zeolite or base – exchanger or ion – exchanger reacts with the calcium and magnesium ions in hard water in the following way.

Na2O.AL2O3.SiO2.H2O+Ca(HCO3)2CaO.AL2O3.SiO2.H2O+ 2 NaHCO3

Na2O.AL2O3.SiO2.H2O+CaSO4  CaO.AL2O3.SiO2.H2O+ 2 NaHCO3

Na2O.AL2O3.SiO2.H2O+Mg(HCO3)2MgO.AL2O3.SiO2.H2O+2NaHCO3

Na2O.AL2O3.SiO2.H2O+MgSO4  MgO.AL2O3.SiO2.H2O+2NaHCO3 By this method hardness is totally removed after it has been percolated through the zeolite. Hardness of 0.2 ppm or less may remain after water emerges. After all the sodium has been exhausted, it has to be regenerated by treatment with concentrated, sodium chloride solution (20%).The calcium chloride (CaCl2) formed and the residual sodium chloride are washed a way and the generated zeolite is used once again indefinitely. However it is when the source of water is very hard, it is more economical to use the soda – lime process followed by the zeolite process, Dsouza, (1998).

Fig. (2.7): Ion exchange process Source : Dsouza (1998)

32 2.10.5 Reverse osmosis (RO): Reverse osmosis (RO) is the reversal of the natural osmosis process which is the movement of solvent into a region of high concentration. Osmotic pressure (osmo- regulation) is a measure of the tendency of water to move into one solution from another by osmosis. Reverse osmosis is a membrane technique, technical filtration method that removes many types of large molecules and ions from solution, by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is returned on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side. To be selective the membrane should not allow large molecules or ions to pass through the pores or (holes) but should allow small component of the solution such as the solvent i.e. (H2O) to pass freely. The process is used to desalinate aqueous solution using a suitable high performance membrane technique. It is possible today to remove more than 99% of the salts from an aqueous solution, Mecktta, (1972).

2.10.5.1 Advantages of reverse osmosis From the procedures of membrane filtration reverse osmosis is the one with highest separation limit. The raw water to be desalinated is lead into a chamber that is closely sealed by means of a semipermeable membrane in contrast to osmotic pressure gradient; an artificial pressure is created in the chamber. As the membrane is only permeable to pure water but not for ions and other particles dissolved in the water, parts of the raw water (concentrated solution) will become pure, desalinated water (primates) and the other parts become even higher concentrated solution (concentrate). Using water treated through reverse osmosis softening appliance sets the ideal conditions for dyes reaction. Water can be chemically or mechanically softened. The chemical means bind up dissolved minerals so that they cannot interfere with dye reaction but the mechanically softened process i.e. reverse osmosis removes the dissolved minerals completely and this is the best way the reverse osmosis is doing. The microscopic charged particles causing hardness can no longer take space in the water, hindering some dye molecules to be dissolved in water. The chemically softened water has less space available to dissolve urea and dye than an equivalent volume of RO softened water.

33 Other advantages of reverse osmosis is that it’s easy and safe handling with modern microprocessor control with integrated conductivity measuring and clear display of operation states. It is an efficient operation with pure water yield of up to 80% and separation of more than 99% of dissolved ions. Also low energy inputs thanks to use low energy reserve osmosis membrane and long lifetime membrane, Mecktta,( 1972).

2.10.6 Water treatment products: Many companies offer an extensive range of advanced scientifically formulated treatment products manufactured to the highest international quality and environmental standards for guaranteed performance. It can meet the demands of most commercial, municipal and industrial process environments where they help to improve productivity optimize performance and reduce equipment life cycle cost. They include high performance water treatment chemicals for steam boiler, waste water effluent treatment chemicals, high performance industrial chemicals, reverse osmosis membrane products, ecofriendly biological formulation and advance polymer, Water Treatment Products Ltd. Unit 1,G.Thomus Industrial state, United Kingdom.

2.10.6.1 Antifoams and defoamers: Antifoam is a mixture of hydrocarbon, emulsifier and special active ingredients. Defomers divinol destroys the foam and this contributes to reduce contamination in the drainage system expensive cleaning cost. Un-wanted foaming can be problematic in many commercial manufacturing and industrial process applications, consequently it requires careful control measures to minimize or eliminate its impact.

2.10.6.2 Biocides and Disinfectants: The control of microbiological activity is an important, often safety` critical activity in many commercial, manufacturing and industrial process applications. It is used in a wide range of commercial cleaning, environmental hygiene, and industrial and process water treatment activities. They include both oxidizing and non-oxidizing biocides for complete water system control. Oxidizing biocides include calcium hypochlorite, sodium hypochlorite, stabilized bromine, bromine and chlorine tablets, hydrogen peroxide and full range of chlorine dioxide tablets. Non-oxidizing biocides include a range of broad spectrum biocides and micro biocides and more.

34 2.10.6.3 Boiler water treatment chemicals: Industrial boilers and steam raising plants are used extensively in many commercial, manufacturing and industrial processes. Managing the problems associated with the use of water including scale formation , metallic corrosion , boiler water carryover and sludge deposition, scientifically formulated chemicals are produced to improve the operation and maintenance of industrial boiler system and steam generation. These chemicals include scale and corrosion inhibitors, oxygen scavenger alkalinity builders, sludge conditioners, condensate line treatment and more. The control of boilers water pH and alkalinity levels are important issue affecting the operation and maintenance of industrial boiler systems. Some companies offer a multi- functional boiler water treatment chemicals to be used in a single " one shot " chemical product. Oxygen related metallic corrosion is a significant issue in the operation and maintenance of steam boiler. If left un-treated, boiler water derived oxygen will corrode metallic boiler components leading to increased maintenance cost and reduced boiler efficiency, Water Treatment Products ltd,Unit1 G.Thomus industrial state, United Kingdom.

2.10.6.3.1 Scale and corrosion inhibitors: Scale is caused by the accumulation of hardness. Salt in the boiler water which, if not removed can cause localized overheating reduce heat transfer efficiency and in severe situations tube failure

2.10.6.3.2 Sludge conditioners: Boiler water sludge is caused by small quantities of hardness, salts and traces of suspended matter present in operational steam boiler and feed waters .When the sludge settles and eventually bakes onto the boiler heat transfer surfaces, forming a hard crystalline scale which degrades heat transfer efficiency and the overall boiler efficiency, Water Treatment Products ltd,Unit1 G.Thomus industrial state, United Kingdom.

35 2.11 Determination of water hardness: 2.11.1 Measurement of degree of general hardness (dGH): It is the amount of water hardness specially general hardness. General hardness is a measure of concentration of metal divalent ions such as calcium (Ca++) and magnesium (Mg++) per volume of water. Specially 1 (one) dGH is defined as 10 milligram of calcium oxide (CaO)/liter of water, which is equivalent to 0.17832 in mole/liter of elemental calcium and / or magnesium ions. Since calcium oxide (CaO) has molar mass of 56.0778 gm/mole. 1 dGH defined by 10 mg of CaO/liter of water, equivalent to.

One ppm defined as one (1) mg of CaCO3 / liter water. Test strips measure hardness in (ppm) defined as one part / million one milligram of CaCO3 / liter in water. 1 dGH corresponds to 17.848 ppm since CaCO3 has a molar mass of (100.0875) gm/mole.

One dGH = 17.850 ppm Ca CO3. One dGH = 7.143 ppm Ca+2 -2 One dGH = 10.707 ppm CO3 – For bicarbonate HCO3

CaCO3 forms two Ca (HCO3)2 in water at pH less than 10.25. +2 Therefore 10.707 mg/l of CO3 forms - 61 x 2 x 10.707 = 22.8 mg/ L HCO3 (http://en.m wikipedia.org/wiki/DGH). 60

2.11.2 Significance of calcium – magnesium determination: Hard water typically contains high concentration of calcium and magnesium, other cations interfere with the use of water for many applications (i.e. diminish the effectiveness of soap and some detergent for cleansing operations, they diminish the drinking quality of the water and they contribute to the accumulation of insoluble salts deposits in storage vessels. The determinations of levels of these ions in untreated (natural) water are very common procedures in commercial laboratories. For some purposes it is only necessary to know the total hardness. This is related to the total amount of magnesium and calcium in the water and is usually expressed in terms of ppm CaCo3, that is the total mole/liter or calcium and magnesium concentration is converted into the equivalent weight of CaCO3 in ppm unit. Sometimes, however, it is

36 desired to know the relative amount of each calcium and magnesium as one may be having more serious inference in the planned application for the hard water. By convention the total hardness of water is quoted in terms of parts per million of calcium carbonate ignoring the concentration of magnesium salts. In this method a sample of tap water will be analyzed. Calcium and magnesium ions form (1: 1) complexes with EDTA according to the following equations. +2 Ca + H2 EDTA Ca EDTA + 2H +2 Mg + H2 EDTA Mg EDTA + 2H The indicators used are the Erichrome black T, when changes from Red to Blue in the presence of Excess EDTA.

-2 -1 + Mg In + H2 EDTA Mg EDTA + H In + H (Red) (Blue)

The separate calcium and magnesium concentration can be found by a separate titration of higher pH by adding (NaOH) the magnesium precipitate as

(Mg(OH)2) and the calcium can be determined separately. Simple subtraction from the total concentration of magnesium and calcium the magnesium concentration can be found, (www.sjsu,edu/faculty).

2.12 Heat energy: The quantitative measure of heat is the BTU ordinarily written Btu. This is the quantity of heat required to raise the temperature of one pound of pure water one degree at 62 F degrees Fahrenheit that is from 62 to 63 F. In the metric system this unit is calorie, it is the necessary heat to raise the temperature of one kilogram of pure water from 15 to 16 degree centigrade 1 calorie =3.968 btu Heating values of fuel can be determined chemically by reducing the fuel to its elementary constituents of C, H, O, N, S, ash and moisture to secure a reasonable degree of accuracy. Heat unit in Btu per pound of dry fuel = 14600 C + 62000 (H – O/8) + 4000 S

37 Table (2.4): Heat unit of dry and moist fuel Constituents Moist Fuel Dry Fuel C 83.95 84.45 H 4.23 4.25 O 3.02 3.04 N 1.27 1.28 S 0.91 0.91 Ash 6.03 6.07 Moisture 0.59 0.59 Total 100 100 Source: Gutenberg E Book of Steam, its generation and use (2012). Substituting in the above formula: Heat units in b.t.u per pound of dry fuel = 14600*0.8445*62000 (0.0425- 0.0304/8) + 4000* 0.091= 14765 b.t.u 2.13 Locations of water samples: Samples were collected from four locations in the country. These are either factories or companies adopting the use of boilers for steam generation.

Table (2.5): Samples and locations Sample Location Abbreviation Blue Nile Textile Factory Wad Madani, South of (a) B.N.T Wad Madani, Maringan area. Gezira Managil TextileFactory, Wad Madani, east (b) Gematex of Wad Madani, Malakia area. Kenana Sugar Company, Kosti, by the river White (c) K.S.C Nile, Rabac Town. Khartoum Refinery Company, Khartoum North (d) K.R.C near Algaili Village.

38 2.13.1 Kenana Sugar Company: The company was established in the year 1975. it is located in Kenana town, on the south eastern side, about 21 kilometer from Rabak town, in the White Nile State. It is a Sugar Cane Factory producing more than 300000 tons of sugar annually. In the plant they have water – tube boiler of 75 ton/hr capacity. The steam produced is entitled for the production of electric power and heat processes. During the agricultural production season they use the bye-product of the industry, bagas, as a source of fuel energy. The water source for the boiler is from the river White Nile. Although the boiler was established on 1978, and it was working through all this time, yet till how it is running at normal capacity. The pay very high attention to the requirement of the facility as far as the feeding of the boiler with the proper treated water, the water treatment and its ancillary units are the all working and under full control and supervision. Maintenance, cleanliness, boiler blow down processes are carried out regularly without delay. The condition of the boilers can be considered good as its start was on 1978. Source: Kenana Sugar Company

2.13.2 Khartoum Refinery Company (KRC): The company was established in the year (1996), it is located near Algaili village, north of Khartoum by the river Nile. It is a petroleum oil refinery company the capacity of the refinery is 100000 barrels of oil per day. Because of the high capacity, many of the units operate continuously at steady rate for months to years. The high capacity also makes process optimization and advanced process control very desirable. Steam boilers are used widely in the refinery. The employ water tube boiler device as the steam pressure needed is high. The boiler capacity is 75 ton/hr. It was installed in the year 1999. It was manufactured by the Chinese company (Harbin). The special attention paid to the supervision and performance of the boiler and its ancillary units avoid the company many problems. Their water treatment unit is ideal. There is a quality control unit checking boiler feed water every working shift two times. The quality control department which monitors and controls the chemical analysis of the boiler feed water is an independent unit and they report directly to the general manages. Any discrepancy observed by the quality control concerning chemical levels in the boiler feed water will be corresponded to the mechanical

39 electrical unit who should in return respond quickly and make the necessary arrangement to shift back to normal standard specification of the boiler feed water. Source: Khartoum Refinery Company

K.R.C Fig (2.8) : Khartoum Refinery Company

K.S.C Fig (2.9):Kenana Sugar Company Source : google

40 CHAPTER THREE MATERIALS AND METHODS

This study was conducted at the Faculty of Textile and the Faculty of Engineering and Technology, University of Gezira, Wad Medani, Sudan during the period January 2012 - March 2015.

3.1 Materials: 3.1.1 Water samples: The water samples were collected from each location for chemical analysis. The locations were textile factories or sugar or Petroleum Company. a. Blue Nile Textile Company, Wad Medani City. b. Gematex Textile Company, East Wad Medani. c. Kenana Sugar Company. d. Khartoum Refinery Company, Khartoum North.

Three samples of two litres in each case were collected to ensure full representation of the samples to the whole bulk of the water. The samples were collected after intervals i.e at the beginning of every working shift. The first samples were taken from the tank fed from the water source, river or well i.e before treatment (BT). The second samples were collected after the water being treated i.e after treatment (A.T). The instruments used in the titration and determination of the constituents of the boiler feed water samples were: Burette, pipette, volumetric flask 250 ml, flasks, beakers, weighing balance, steam bath. The pH, EC, TDS values were determined by microprocessors. Every sample was tested three times for every chemical check. The average value of the three test results was then calculated. Blue Nile Textile Factory and Gemtex textile , the tests of the samples after treatment , of the boiler feed water were not carried simply because they were not treating the water in recent years . The boiler was fed directly from the water source.

41 3.1.2 Preparation of standard solutions: 1. Standard buffer solutions of (pH=4) and (pH=9) were prepared by using buffer tablets of (pH=4) and (pH=9) and then dissolved and diluted to 100 ml with distilled water. 2. Ammonia buffer solution (pH=10) was prepared by dissolving and

diluting 16.9 gram ammonia chloride (NH4Cl) and 143 ml of concentrated ammonium hydroxide into 250 ml distilled water. 3.Standard EDTA titrant (0.01M) was prepared by dissolving 3.732 gram

sodium EDTA salt Na2C10O8N2.2H2O in distilled water and then diluted to one liter. 4. Erichrome black T indicator solution was prepared by dissolving 0.5 gram erichrome black T with 4.5gram hydroxylamine hydrochloride in 100 ml ethyl alcohol (95%). 5.Hydrochloric acid (0.01M) was prepared by dissolving calculated amount of concentrated HCl in liter of distilled water. 6.Hydrochloric acid 1:1 solutions were prepared by dissolving 50 ml of concentrated acid in distilled water and then dilute to one liter. 7.Sulphuric acid (0.02M) solutions were prepared by dissolving 1.9ml of

concentrated H2SO4 in distilled water and then dilute to one liter. 8.Methyl orange indicator was prepared by dissolving 0.05 gram methyl orange powder in distilled water and then complete to one liter 9.Phenolphthalein indicator solution was prepared by dissolving 0.05 gram phenolphthalein in 50 ml (95%) ethanol and then diluted to 100 ml with distilled water. 10.Sodium hydroxide solution NaOH (2.0M) was prepared by dissolving 8 gram solid NaOH in distilled water and then complete to one liter.

11.Calcium carbonate CaCO3 (0.02M) stock solution was prepared by

dissolving 2.4 gram CaCO3 TO 50 ml distilled water and then dissolved by adding drop wise 10 ml HCl and then diluted to one liter with distilled water. 42 12.Barium chloride (BaCl2) solution 10% was prepared by dissolving 10

gram (BaCl2H2 O) in 100 ml distilled water. 13.Potassium chromate indicator was prepared by dissolving 5 gram

K2CrO4 and few drops of silver nitrate AgNO3 (1.0M) in distilled water till a red precipitate was formed. Then it was filtered and the filtrate was diluted to 100 ml with distilled water.

14.Silver nitrate (AgNO3) titrant (0.01M) was prepared by dissolving 1.7 gram silver nitrate in distilled water and then diluted to one liter. The

solution was then stored in a dark bottle. 3.2 Methods: 3.2.1 Total Dissolved Solids (TDS): Total Dissolved Solids (TDS) was measured by TDS meter, a measuring set was used with specific TDS meter cell and it was calibrated with distilled water at 25C. The (TDS) of the samples were then determined in ppm. Hach,( 2001). 3.2.2 pH value: pH value was measured by pH meter. The pH meter was calibrated by using the standard buffer solutions at 29C and pH adjusted to (pH = 7) pH value of the samples were recorded. Aranold et al.,( 1992). 3.2.3 Electric conductivity (EC): Electric conductivity (EC) was reassured by electric conductivity meter. A measuring set was used with specific conductance cell and it was calibrated with (0.01M) KCl the conductivities of the samples were then determined in (mhos/cm) Aranold et al., (1992). 3.3 Determination of hardness: 3.3.1 Permanent hardness: Permanent hardness estimated by evaporating 100 ml of water to dryness on a water bath, with a known volume of 0.1 M sodium carbonate solution. The residue was extracted with freshly boiled hot distilled water and filtered. The insoluble calcium carbonate on the filter paper was thoroughly washed. The filterate (containing the permanent hardness) was cooled and titrated with 0.1 M sodium carbonate solution in the presence of methyl orange indicator.

43 1 (ml) of 0.1 M (Na2CO3)  0.005 (gm permanent hardness expressed as

CaCO3).

3.3.2 Temporary hardness: Temporary hardness was determined by titrating 100 ml of water sample with 0.1 M HCL using methyl orange as the indicator

1 (ml) of 0.1 M HCl  0.005 gm of CaCO3

2 HCl + CaCO3 CaCl2 + H2O + CO2

1 ml of 0.1 M HCl  0.005 gm of CaCO3 Or:

 0.005 gm CaCO3 http://books.goole.com/books? 3.3.3 Total hardness: 1 ml of ammonia buffer solution and (3-5 ml) of erichrome black T indicator solution were added to 25 ml of water sample in a volumetric conical flask (250 ml). The solution was then titrated with standard EDTA (0.01 M) till the colour change from wine red to blue. Calculation:

A = ml of EDTA required for titration

B = mg of Ca CO3 equivalent to 1 ml EDTA titrant EDTA titrimetric method was used as described in Vogel, et al, (1978) 3.3.4 Carbonates and bicarbonates: To 50 ml of water sample few drops of phenolphthalene indicator solution or

methyl orange indicator were added and the sample was titrated with (0.1 M) HCl until the color changes from red to blue, Aranold et. al., (1992).

44 Calculation:

A = ml of HCl required for titration -2 B = mg of CO3 equivalent to 1 ml HCl titrant HCl titrimetric method 59.3.2 was used as described in vogel et al .(1978)

A = ml of HCl required for titration -1 B = mg of HCO3 equivalent to 1 ml HCl titrant HCl titrimetric method 59.3.2 was used as described in vogel et al .(1978) 3.3.5 Calcium ions (Ca+2): 2 ml of NaOH (0.02M) solution and (3–5 ml) of murexide indicator solution was added to 50 ml volume of water sample in a conical flask (250 ml) the solution was then titrated with standard EDTA (0.01 M) solution till the colour changed from purple to wire red. Calculation:

Where: A = ml of EDTA required for titration M = Molarity of EDTA A.W = Atomic weight of Ca+2 V = Volume of sample This method was described by Aranold et al., (1992).

3.3.6 Chloride ions (CL ):

To 100 ml of water sample few drops of K2CrO4 indicator were added and the solution was titrated against 0.01M AgNO3 till the color changed from yellow to light red. Calculation:

A = (ml) AgNO3 titrant required for titration

45

B = mg of Cl equivalent to 1 ml AgNO3 titrant -2 3.3.7 Sulphate ions (SO4 ):

To 50 ml of water sample, dilute HCl (50%) was added to adjust pH 4-5. The solution was heated for few minutes in a water bath. 10 ml of 10% BaCl2 solution were added . The solution was left overnight for precipitation and then filtered through filter paper. The weight of the residue was determined. Calculation:

46 CHAPTER FOUR RESULTS AND DISCUSSION 4.1 Results: Results of the constituent of the boiler feed water were determined volumetrically and or gravimetrically for each company or factory. They were first tabulated in ml titrant according to the method used and then calculated in ppm for every ion detected.

4.1.1. Results of total hardness: It’s the most important test in the experimental work. The total hardness was determined for every company and the average value of the titrant was calculated after carrying three tests for each company. Table (4.1) shows the results.

Table (4.1): Volume of titrant needed to determine total hardness for the four companies (ml) titrant 0.01 M EDTA Location Before Treatment After Treatment I II III Average I II III Average B.N textile 10.50 10.60 10.55 10.56 N.A. N.A.

Gematex 18.20 18.40 18.20 18.20 N.A. N.A. textile K.S.C 12.20 12.00 12.20 12.20 4.45 5.55 5.00 5.00 K.R.C 8.90 9.10 9.00 9.00 1.90 2.10 1.90 2.00

It's clear from table (4.1) above that although all companies reveal considerable amount of titrant used in the analysis before treatment, yet Gematex factory shows the highest value whilst K.R.C shows the least value. This is specially noticed after the water treatment process which carried explosively in the case of K.S.C and K.R.C. Table (4.1) reveals the average values of the titrant used. It can be used to determine the total hardness in ppm of the four companies.

47 Table (4.2): Total hardness as CaCO3 (ppm) for the four water samples Average (ppm) Standard specified Location value Before treatment After treatment B.N.T 213 N.A. Gematex 364 N.A. < 10 ppm K.S.C 244 100 K.R.C 180 40

The total hardness is an expression of the quantity of calcium carbonate that may deposit while boiling and form scales on pipes and other parts of the boiler. This will definitely reflect its effect on the performance and efficiency of the boiler. Table (4.2) shows that Gematex company's value of total hardness is higher than B.N. Text. Company by 41.48%, and higher than K.S.C. by 72.53% and higher than K.R.C. by 89.01%. Nevertheless all the values of the four companies deviated from the standard specified value which less than 10 ppm. (w.w.w.com/Boiler water treatment). The values of the total hardness shown in table (4.2) reflects the condition of the boiler devices in the four companies. While both boilers of K.S.C and K.R.C. are still in working condition, the boilers of B.N. Text. and Gematex factories were all scrapped.

Note : Blue column before treatment, red after treatment if any.

Figure (4.1): Total hardness calculated as (ppm) CaCO3 for the four water samples

48 4.1.2 Results of pH values: pH values were determined for every company using digital microprocessor Table (4.3)below shows the values of pH before and after the treatment of the boiler feed water of the four companies Table (4.3): pH values for the four companies pH Standard pH Location Before treatment After treatment B.N.T 8.4 N.A. Gematex 7.9 N.A. 8.5 – 9.5 K.S.C 6.7 7.5 K.R.C 7.9 8.7

As table (4.3) shows, the standard specified pH value for boiler feed water is (8.5-9.5) as stated by Bureau of Indian Standard . K.R.C. is the most suitable among the four companies being (8.7).i.e. within the standard range. Other companies need adjustment to become suitable. K.S.C deviates from the standard by 11.8 % . Gematex company deviates from the standard by 7.1 % .Blue Nile Textile deviates by 1.2 %. Acidic medium in boiler feed water is corrosive and may cause damage to the parts of the boiler and holes in pipes. This phenomenon was noticed in both Gematex and B.N. Text factories.

Figure (4.2): pH values for the four companies.

49 4.1.3 Results of Total dissolved solids: The total dissolved solids were determined using a micro processing digital device as shown in table (4.4). Table (4.4): Results of the total dissolve solids for the four companies TDS Mg/L STD Location Before treatment After treatment B.N.T 195 N.A. Gematex 450 N.A. 4000 K.S.C 320 60 K.R.C 115 40 N.A : Not Available Table (4.4) reveals that the total dissolved solids in the boiler feed water of Gematex textile factory was (56.67%) higher than that of B.N. Textile factory and it was (86.67%) higher than K.S.C. It is obvious that the water treatment and conditioning processes carried out in K.R.C and K.S.C companies are the reasons for the big decrease of the total dissolved solids values, from 320 to 60 Mg/I (81.25%). K.R.C. shows (100%) removal in this sample. The specified standard value of total dissolved solids for boiler feed water as stated by (Degremont, 1991) is 4000 Mg/I. In other reference ,(source:www2 spraxsarco com/re: ) gives the maximum permissible levels of boiler water TDS is in the range of 1500 -10000 ppm depending on the type of boiler. Higher levels of TDS in boiler feed water may give rise to foaming.

500 450 400 350 300 250

200 TDS Mg/L TDS 150 100 50 0 B.N.T Gematex K.S.C K.R.C Location

Figure (4.3): Results of the total dissolved solids for the four companies

50 The actual dissolved solids concentration at which foaming may start will vary from boiler to boiler. Conventional shell boilers are normally operated with the TDS value in the range of 2000 ppm for larger boilers provided that the - Boiler operate near its design pressure - Other boiler water condition are correctly controlled - Below are broad guidelines on the maximum permissible levels of boiler water TDS in certain type of boilers Degree Bauma and degree Twaddle are alternative hydrometer scales. Table(4.5) in the Appendix revealed other units used to measure the water constituents 4.1.4 Results of electrical conductivity (E.C): The values of the E.C. for the four companies were determined using micro processor digital device Table (4.6) below shows the results. Table (4.6): Results of E.C. of the four companies

E.C Microhm/cm Location Before treatment After treatment B.N.T 347 N.A. Gematex 863 N.A. K.S.C 425 113 K.R.C 245 80

As in table (4.6) it is clear that the E.C. values of Gematex boiler feed water were higher than that of the Blue Nile Textiles factory by (60 %) and higher than K.S.C company by (87 %). K.R.C through their proper behavior of water treatment and conditioning of boiler feed water succeeded to bring E.C values to 80. TDS may be expressed in a number of different units. Table (4.5) gives the approximate conversions from TDS to other units. Degree Bauma and degree Twaddle are alternative hydrometer scales. It is also noticed from table (4.5) that the E.C values of the four companies are far below the typical maximum value of E.C for various boiler types. The highest E.C value was recorded by Gematex company being 863 microhm/cm which is nearly double as much as that of TDS being 450 ppm.

51

Figure (4.4): Results of E.C. of the four companies.

4.1.5. Results of some cations and anions in the boiler feed water of the four companies: 4.1.5.1. Analytical results of different ions in ml titrant:

+2 -  2 2 The Ca , Cl , HCO3 , CO3 and SO4 ions were determined titrimitrically and gravimetrically for the four companies. Table (4.7) show these results.

Table (4.7): Average volume of titrant needed for titrating some ions in the boiler feed water for Gematex factory. Gematex (ml) titrant Analyte Titrant I II III Average 2 Ca 0.01 M 37.5 37.0 37.0 37.0 EDTA  Cl 0.01 M 8.9 8.5 8.5 4.5 Ag NO3 / 0.01 M 36.00 37.20 39.10 36.43 HCl Ba Cl2 10.10 9.85 10.06 10.08 (10%)

The boiler feed water of Gematex shows the highest value of Ca+2ions dissolved in the water compared with that of the other companies shown later. and

52  HCO3 ions were determined simultaneously in one water sample as it became clearly

2 difficult to determine the CO3 ion alone. Table (4.8): Average volume of titrant needed for titrating some ions in the boiler feed water of Blue Nile Textile Factory. B.N. Textile (ml) titrant Analyte Titrant I II III Average 2 Ca 0.01 M 21.10 21.2 21.2 21.2 EDTA  Cl 0.01 M 1.25 1.30 1.20 1.25 Ag NO3 / 0.01 M 10.60 10.41 10.50 10.50 HCl 2 Ba Cl2 0 0 0 0 SO4 (10%)

As shown in table (4.7) the amount of titrant needed to detect the Ca+2 ion in the boiler feed water of the Blue Nile textile factory is lower than that of Gematex. Also no ion was detected in the water. Table (4.9): Average volume of titrant needed for titrating some ions in the boiler feed water of K.S.C company. K.S.C (ml) titrant Analyte Titrant I II III Average 0.01 M 10.50 10.70 10.50 10.50 EDTA 0.01 M 8.7 8.6 8.6 8.6 Ag NO3 / 0.01 M 9.80 9.85 9.83 9.84 HCl Ba Cl2 7.2 7.1 7.3 7.2 (10%)

Table (4.8) reveals that the chloride ion level in the boiler feed water of K.S.C was the highest among the four companies. Other ions detected showed varying values. and ions were determined in one bath and the average result shown is for both ions.

53 Table (4.10): Average volume of titrant needed for titrating some ions in the boiler feed water for K.R.C K.R.C (ml) titrant Analyte Titrant I II III Average 2 Ca 0.01 M 3.7 3.8 3.8 3.8 EDTA  Cl 0.01 M 4.9 5.1 4.9 4.95 Ag NO3  2 0.01 M 4.2 4.0 4.2 4.1 HCO3 / CO3 HCl 2 Ba Cl2 4.85 4.90 4.86 4.85 SO4 (10%)

In table (4.10) all ions detected show varying amounts. Average result were calculated from two nearest readings. and were determined together in one bath and the average result was shown for both ions.

4.1.5.2. Results of different ions of the four water samples: The average values of ml titrant were used to calculate the amount of these ions in ppm. Table (4.11) underneath shows these results. Table (4.11): Results of some ions in (ppm) of the four companies. Analyte B.N Textile Gematex K.S.C K.R.C STD

84.40 146.00 40.60 15.20 ≥ 6.0 ــــ 35.0 61.06 60.35 8.7 46 222 60 24.4 ≥ 4.0

ــــ 40.0 60.0 83.0 0.00

Table (4.11) shows that the values of calcium, carbonate and bicarbonate ions in the water sample of Gematex are the highest among the four companies. The total hardness of the water sample of Gematex is also the highest. Both results may be considered as the reason behind boiler deterioration and deficiency in a comparatively short period. B.N. Textile values of these ions are also high and may be the same reason for the damage of their boilers. K.S.C and K.R.C companies show low levels of these ions but even though their values are higher than the standard specified by +2 -2 -. Bureau of Indian Standards. (6 ppm for Ca as CaCO3. 4 ppm CO3 /HCO3 ).

54 Calcium ion level in Gematex water sample is the highest among all samples. It is higher than KRC by (90%) and than KSC by (73%) and than BN textiles by (42%). The situation of the four boilers in the four companies highlighted the importance for more proper and perfect treatment and conditioning of the boiler feed water. The scales, corrosion, damage of boilers parts and low efficiency of the boiler may all be attributed to the presence of foreign elements like calcium ions found in the water. Sulphate ions level in table (4.10) reveals that it is the highest in case of Gematex being 83 ppm while in B.N. Textile it is nil .These ions and the chloride ions are non-scaling. Their role in scaling and corrosion is insignificant as both ions are less-adherent slurry during boiling, and can be removed while the boiler blow down.

250 2 Ca  Cl 200  2 HCO3 /CO3 2 SO4 150

100

Concentration ppm Concentration

50

0 B.N Text Gematex K.S.C K.R.C

Companies and Factories

Figure (4.5): Results of calcium, chloride, carbonate/bicarbonate and sulphate ions in (ppm) in the four companies.

55 Table (4.12): Summary of information collected about the four boilers

Location Water Source Boiler Manufacturer Total Year Present Purpose Ancillary sample of types capacity of condition Water Deaerator Scavenger Alkalizer Steam water ton/hr start treatment condensate Blue (a) Well Fire- Multi- pack 10 1978/ 3 boiler Heat x x x x x Nile tube (England) 1980 scrapped Textile one Factory boiler severely damaged Gematex (b) Well Fire- (!) 10 1978 2 boiler Heat x x x x x textile tube scrapped Factory K.S.C (c) River Water Takume 30 1978 Good Power      tube (Japan) Generation and Heat K.R.C (d) River Water Harbin 75 1999 Very Power      tube (China) good generation and Heat

Source: Gematex, Blue Nile Textiles, K.S.C. and K.R.C Companies. Key: x : Not available process.  : Available

56 CHPTER FIVE CONCLUSION AND RECOMMENDATIONS 5.1conclusion: 1. All water samples of the boiler feed water for the four companies constitute various anions and cations with varying degrees. 2. Gematex company shows higher values of total hardness, calcium ions, carbonates and bicarbonates ions in their water sample. The main reason for that is their non- treatment and conditioning of the boiler water. This may be the reason behind the quick deterioration of their boilers. B.N Text. Also shows relatively high values in these ions which accumulate inside the boilers forming scales and rendering the boilers inefficient in short period. K.S.C. and K.R.C. show low levels of the mentioned ions because they are treating and conditioning their boiler feed water. That is why their boilers are in good running condition. High value of total hardness, in the boiler water i.e. above standard level and pH values that deviates from standard may cause problems concerning boiler performance 3. It appears from the discussions that the water treatment process which is responsible for the removal of foreign elements from the boiler feed water is of absolute necessity if the boilers are to run without problems. pH specified standard values should also be maintained to avoid corrosion. 4. Factories or companies which pay attention to the treatment of their boiler feed water by minimizing the levels of foreign elements, maintaining pH, they secure these boilers from serious limitations. 5. It is clear from the results of the concentration of the anions and cations of the four water samples that they all deviate from the standard specified values by different degrees. But in most cases the deviations in Gematex and Blue Nile textile factories are higher than that of K.S.C. and K.R.C. companies specifically in the constituents which affect the scaling and corrosion.

57 5.2. Recommendations: 1. A reliable water treatment unit is highly recommended for every mill adopting boilers for steam generation. Once the source of raw water is located, a treatment method is established to remove any foreign elements dissolved in the boiler feed water and that a testing unit should be inaugurated to monitor the boiler feed water. 2. Reverse Osmosis system is to be added to the line of treatment as it removes physically all anions and cations from the water. This is particularly recommended in wet textile processing while carrying certain dyeing printing technique. 3. Micro processing indicators that can digitally display chemical measurements of some properties of the treated water in – line with the treatment process is also recommended. This will show instantly the levels of foreign constituents in the boiler feed water. 4. Application of a genuine, stringent, legal, testing, training, certification system to be imposed by the ministry of industry and to inspect periodically the condition of the boilers of the various companies and factories in the country. 5. All companies need proper revision concerning their water treatment units. They must bring the chemical constituents of their boiler feed water to the levels specified by their boiler manufacturer. 6. A comprehensive study is recommended to cover the effect of boiler feed water on the performance, efficiency, consumption of furnace fuel of industrial boiler. Also to compare that with production, expenses of repairing and use of chemicals in washing

58 REFERENCES

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60 Appendix

Typical max. TDS for various boiler types Boiler type Max. TDS ppm Lancashire 10000 Two-pass economic 4000 Three- pass economic 3000- 3500 Low pressure water-tube 2000-3000 Med. : ; : 1500 High ; : : 1500 TDS may be expressed in a number of different units. Table (4.5) gives some approximate conversions from TDS to other units.

Table (4.5 ): Comparison of units used to measure TDS and others Total dissolved Conductivity Relative Degree Degree Solids TDS s/cm density at Bauma Twaddle (ppm) Neutral Unneutral 15.5 c Be Tw 0 0 0 1.000 0.000 0.000 200 266 400 1.00036 0.026 0.036 400 571 800 1.00036 0.052 0.073 800 1140. 1600 1.00073 0.105 0.145 1000 1429 2000 1.00091 0.131 0.182 1200 1714 2400 1.00109 0.157 0.218

Source: www2. Spraxsarco com /re:

61