Boiler Feed Water Treatment
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Boiler Feed Water Treatment: A case Study Of Dr. Mohamod Shareef Thermal Power Station, Khartoum State, Sudan Motawakel Sayed Osman Mohammed Ahmed B.Sc. (Honours) in Textile Engineering Technology University of Gezira (2006) A Dissertation Submitted to the University of Gezira in Partial Fulfillment of the Requirements for the Award of the Degree of Master of Science In Chemical Engineering Department of Applied Chemistry and Chemical Technology Faculty of Engineering and Technology University of Gezira January,2014 I Boiler Feed Water Treatment: A case Study Of Dr. Mohamod Shareef Thermal Power Station, Khartoum State, Sudan Motawakel Sayed Osman Mohammed Ahmed Supervision Committee: Name Position Signature Dr. Bshir Mohammed Elhassen Main Supervisor …………………. Dr. Mohammed Osman Babiker Co-supervisor ………………….. Date : January , 2014 II Boiler Feed Water Treatment: A case Study Of Dr. Mohamod Shareef Thermal Power Station, Khartoum State, Sudan Motawakel Sayed Osman Mohammed Ahmed Examination Committee: Name Position Signature Dr. Bshir Mohammed Elhassen Chair Person ……………… Dr.Bahaaeldeen Siddig Mohammed External Examiner ………………… Dr. Mustafa Ohag Mohammed Internal Examiner ………………… Date of Examination : 6. January.2014 III Dedication This research is affectionately dedicated to the souls of my parents , To my family With gratitude and love To whom ever love knowledge I Acknowledgment I would like to thank Dr. Basher Mohammed Elhassan the main Supervisor for his guidance and help. my thank also extended to Dr. Mohammed Osman Babiker my Co-supervisor for his great help. my thanks also extended to Chemical Engineers in Dr. Mohamod Sharef Thermal Power Station. II Boiler Feed Water Treatment: A case Study Of Dr. Mohamod Sharef Thermal Power Station, Khartoum State, Sudan Motawakel Sayed Osman Mohammed Ahmed Abstract A boiler is an enclosed vessel that provides a means for combustion heat to be transferred to water until it becomes heated water or steam. The hot water or steam under pressure is then usable for transferring the heat to a process. The purpose of this research is to present the detailed findings about boiler feed water treatments, theories and application in power plants field with practical application on pre- treatment plants and anions exchanger unit . The realization of these objectives implies: online data analysis techniques for analytical and experimental work to be applied to raw water and treated water in laboratory, to analyze the water composition and properties through: determination of raw water parameters in reference to specifications. moreover, the work involves analyzing and comparing the water parameters over seasons of the year. The study area is Dr. Mohamod Sharef thermal power station. The samples were taken from the clarifier tank, demin tank, anion exchanger, boiler drum water , condensate water ,dearator water, feed water ,saturated steam and superheated steam and the turbidity ,conductivity and silicate were measured in March and compared with the same samples taken in January and August. In the clarifier tank the samples taken in March had a turbidity =1.88 NTU and the target value <20 NTU that means the obtained value is acceptable and compared with the turbidity reading of samples taken in January (1.72 NTU) and August (4.2 NTU), this means that in August (Autumn) the turbidity was high ,as to the pH the target is 6.5 – 8,its determined value was slightly beyond the standard, this could be due to some colloids that escaped settling in the clarifier. As to the conductivity the seasonal variation as in all readings were below the recommended value (<250µs /cm).The readings (beyond the measured values) showed some deviation from the standard. This means that water had high concentration of solids and impurities after the river station .Most of the values for the samples were within the target range of the turbidity, pH, conductivity and silicate, that means that the chemical dosing is specific and suitable, so it is recommended that the water feed into the boiler must be treated to generate high quality steam. III معالجة المياه الداخلة للمرجل: منطقة الدراسة في محطة الدكتور محمود شريف للتوليد الحراري، وﻻية الخرطوم، السودان متوكل سيد عثمان محمد احمد ملخص الدراسة المرجل عبارة عن وعاء مغلق يستخدم حرارة اﻻحتراق لتحويل الماء إلي ماء ساخن أو بخار،الماء الساخن والبخار تحت ضغط يستخدم لنقل الحرارة لعملية ما. الغرض من هذا البحث هو تقديم بالتفصيل متطلبات معالجة المياه الداخلة إلي المراجل نظريا وعمليا في حقول توليد الطاقة مع التطبيق العملي للمعالجة اﻷولية لمحطات المياه ووحدة المبادل اﻷيوني. ويتم تحقيق هذه اﻷهداف بتحليل ودراسة هذه المياه الخام والمياه التي تمت معالجتها ومقارنتها بالمواصفات والمقاييس المطلوبة وكذلك مقارنتها ببقية فصول السنة. تمت الدراسة بمحطة الشهيد الدكتور محمود شريف الحرارية , أخذت العينات من حوض التنقية ومستودع تخزين المياه القادمة من محطة النهر بعد المعالجة اﻷولية ومن المبادل اﻷيوني ومياه اسطوانات المرجل ومنطقة البخار المكثف وماء السخان الطارد للهواء ومياه تغزيه المراجل ومنطقة البخار المشبع والمحمص تم قياس العكورة والموصلية الكهربية واﻷس الهيدروجيني في شهر مارس وقورنت بعينات أخذت في شهري يناير وأغسطس. في حوض التنقية وجدت العكورة )NTU 1.88( والقيمة المطلوبة )NTU 20>( وهي قيمة مقبولة وعند مقارنتها بالقراءة التي أخذت في شهري يناير أغسطس علي التوالي وجدت )NTU 1.72( و)NTU 4.2( حيث سجلت اعلي قراءة للعكورة في شهر أغسطس )الخريف( ،أما بالنسبة لﻷس الهيدروجيني فهو مطلوب من )8 - 6.5 ( وكل القيم المقاسة واقعة في نفس المدي بالرغم من وجود بعض الكائنات الحية الموجودة في حوض التنقية. كذلك الموصلية الكهربية كانت قراءتها في كل فصول السنة في المدي المطلوب )250µs /cm>( ,هنالك قراءات أظهرت بعض اﻻنحرافات عن القيمة المطلوبة وهذا يعني أن الماء به مواد صلبة وشوائب بعد محطة النهر. معظم نتائج العينات تقع في المدي المطلوب من العكورة واﻷس الهيدروجيني والموصلية الكهربية و السيليكا, وهذا يعني أن الجرعات الكيميائية مناسبة ومحددة ،لذلك أوصي بمعالجة المياه الداخلة للمراجل ﻹنتاج بخار زو جودة عالية. IV TABLE OF CONTENTS Item page Dedication…………………………………………………………….. i. Acknowledgment………………………………………………............ ii. Abstract (English)…………………………………………………….. iii. i Abstract (Arabic)……………………………………………………… iv. Table of Contents……………………………………………………… v. List of Figures…………………………………………………………. i List of Tables…………………………………………………………... Chapter one Introduction Introduction…………………………………………………… 1 Research Objectives…………………………………………….. 9 Chapter Two Literature Review 2.1-Water treatment 2.1.1-Impurities in water………………………………………… 01 2.1.2-Pre-treatment……………………………………………… 14 2.1.3-Demineralization………………………………………….. 22 2.1.4-Additional treatment options ……………………………. 27 2.1.5-Other water purification techniques………………………. 28 2.2- Boiler water treatment: 2.2.1-Boiler feed water…………………………………………. 32 V 2.2.2-Boiler operation………………………………………….. 35 2.2.3-Fly ash collection………………………………………… 41 2.2.4-Boiler make up water treatment plant and storage………. 40 2.2.5- Fuel preparation system………………………………… 42 2.3- Rankine cycle ……………………………………………… 45 2.4- Cooling tower……………………………………………… 47 2.5-Problems in the boiler……………………………………… 49 2.5.1-Corrosion…………………………………………………. 49 2.5.2-Deposits…………………………………………………. 50 2.5.3-Solubilizing programmed……………………………….. 50 2.6- Chemical treatment……………………………………… . 52 Chapter Three Materials and Method: 3.1-Area of study …………………………………………… 55 3.2- Chemical treatment (dosing) 3.2.1 River station……………………………………………. 56 3.2.2 Demineralization unit………………………………….. 57 3. 2. 3. Feed water dosing…………………………………… 58 3.2.4-Boiler Internal Treatment Chemicals dosing…………. 61 3.2.5-Cooling tower dosing………………………………… 61 VI 3.3- Laboratory 3.3.1- Turbidity Test……………………………………… 62 3.3.2- Conductivity Test……………………………………. 63 3.3.3-pH Test……………………………………………….. 65 3.3.4 Silica Test…………………………………………….. 68 Chapter Four Results and Discussion 4.1- Result…………………………………………….. .. ..... 71 4.2 – Discussion………………………………………….. …. 73 Chapter Five Conclusions and Recommendation 5.1-Conclusions………………………………………....... ......... 79 5.2-Recommendation……………………………………………. 79 REFERENCES VII List of figures: figure Item page Figure 1 Demineralization unit 23 Figure 2 The chemical dosing of water treatment in power 33 plant. Figure 3 Diagram of boiler feed water deaerator. 34 Figure 4 Diagram of a typical water-cooled surface condenser. 36 Figure 5 The boiler plant overview 43 Figure 6 Rankine cycle. 45 Figure 7 Curve of the four processes in the Rankine cycle. 46 Figure 8 Cooling towers. 48 Figure 9 The drive off oxygen and other dissolved gases. 51 Figure 10 Pre-treatment of water in the river station. 56 Figure 11 Mechanism of demineralization water. 57 Figure 12 Impurities of water in river station. 58 Figure 13 Relationship among concentration, pH, and 59 conductivity for dilute aqueous ammonia solutions. Figure 14 The samples taken. 60 Figure 15 Turbidity meter. 62 Figure 16 Conductivity meter. 64 Figure 17 pH meter. 67 Figure 18 Si –meter (photometer). 69 Figure 19 The seasonal variation of the turbidity in the clarifier 74 tank. VIII List of tables: Tables Item page Table 1 The impurities in water. 14 Table 2 List of problems caused by impurities in water. 54 Table 3 Chemical dosing in the river station. 56 Table 4 Chemical dosing in the demineralization station. 57 Table 5 Feed water dosing. 58 Table 6 Cooling towers dosing. 61 Table 7 The reading parameter of clarifier water tank. 71 Table 8 The reading parameter of demineralization unit. 71 Table 9 The reading parameter of boiler drum water. 71 Table10 The reading parameter of condensate water 70 Table 11 The reading parameter of dearator water. 70 Table 12 The reading parameter of feed water. 17 Table 13 The reading