Technological Parameters of Biomass Briquetting of Macrophytes in Nansi Lake

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Energy Procedia 5 (2011) 2449–2454

IACEED2010 Technological Parameters of Biomass Briquetting of Macrophytes in Nansi Lake

Li Fengmina, Zhang Mingquana*

aCollege of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China

Abstract

In order to provide a new technique for macrophytes use, this study evaluated the effect of binder content and biomass content on properties of biomass briquetting. Take loess as the binder, when the addition was 30%, mechanical properties of briquetting were the best and drop strength of giant reed briquetting and reed briquetting was 96% and 97% respectively and water impermeability was 6% and 28% respectively. Also, when the binder was lime, the results were almost the same. Take giant reed as biomass, when the addition was 45%, mechanical properties of briquetting were the best and drop strength of biomass briquetting with loess and lime was 90% and 55% respectively, and water impermeability was 32% and 18% respectively. When the biomass is reed, the results are almost the same. Calorific value of biomass briquetting was between 10.7 MJ / kg and 20.3MJ/kg and ash content was between 17.2% and 50.9%. When binder content was 30% and biomass content was 45%, calorific value was 11.5 ~ 14.5 MJ / kg and ash content was between 30.5% and 40.1%. This study could provide a support for wetland restoration of the ecosystem, water quality, and the improving of the economic benefits. © 2011 Published by Elsevier Ltd. Open access under CC BY-NC-ND license. Selection and peer-review under responsibility of RIUDS

Keywords: Nansi Lake; macrophytes; biomass; solid fuel

1. Introducti on

Wetland is the ecosystem that has many unique features, and it not only provide large amounts of food, material and water, but also play an important role in maintaining ecological balance and preserving biodiversity. In recent years wetlands were destroyed by anthropogenic factor such as wetlands reclamation and aiming at this situation our country proposed policy of returning farmlands to wetlands.

* Corresponding aut hor. Tel.: +8615265222598 E-mail address: [email protected].

Macrophytes perform significantly in water purification and bioremediation. Due to lack of effective use technology, macrophytes cannot be promptly harvested and many of them decay and pollute wetland water. Therefore, to seek a recycling and commercial utilization of macrophytes becomes the current urgent need of technique of wetland bioremediation. Biomass energy represents approximately 14% of world total energy consumption, a little higher than coal (12%) and similar to those of electricity (14%) and gas (15%) [1]. Proportion of biomass energy in different countries has big distinction ranging from 2% to 90%. With the aggravation of energy crisis, biomass energy has received more attention as a renewable energy which is also CO2 neutral [2]. As to biomass energy, domestic and foreign scientists have done some research focusing on three aspects that include the environmental impact, biomass resources and biomass conversion technology [3]. So far, the development and utilization of biomass as fuel mainly concentrate on three points: (1) Biomass can derive liquid fuels such as biodiesel from rapeseed, sunflower, soybean, palms and seaweed [4, 5]. Also ethanol [6], methanol [7] and furan [8] can be achieved from lignocellulosic biomass. (2) Biomass can derive combustible gas. Mixed biomass waste has methane potential [9] and by an augmented two- or three-stage anaerobic fermentation process can cornstalks produce hydrogen [10]. (3) Biomass can derive briquetting [11]. Rice husk, wood residues and coffee husk are identified as promising agro-residues for briquetting in the short term [12]. Extensive applications of the former two methods are restricted by high cost and complex technology. But the third method attracts more concern as it can provide a way to solve environmental p roble ms as well as posses the ability to produce alternative fuel. The techniques of biomass compression consist of hot pressure molding, wet pressure molding and carbonization molding. Although after decades of theoretical research and engineering practice, problems with heavy wear and big power consumption are still not resolved. Serving as a near-term, low-risk, low-cost, sustainable, renewable energy, biomass and coal can be molded into briquetting under normal te mperature and lower pressure. Also, biomass-coal co-combustion promises reduction in effective CO2 emissions, reduction in SOx and often NOx emissions, and several societal benefits [13]. As a result, briquetting made of coal and biomass is an effective technique for biomass use. This article is to study the best proportion of binder, combustion agents and the addition of coal in order to obtain the ideal biomass briquetting which help resolve the problems with heavy wear and big power consumption.

2. Experiment

2.1 Materials

Giant reed (Arundo donax L.) and reed (Phragmites australis) were achieved from Nansi Lake, Shandong province, China. After air-dried for 2 days and subsequently over-dried overnight 70-80 ć , the materials were ground and then passed through a 2 mm sieve. The addition of coal and binder were also crushed and then passed through a 2 mm sieve.

2.2 Methods

The formulation of the test material consisted of three parts: biomass powder, coal and binder. To fix the amount of reed and giant reed at 45%, the amount of loess and lime ranged from 0% to 40% with an interval of 10%. The same amount of burning-rate accelerator which was neglected for its small proportion was added in each treatment to improve the briquetting combustion properties. Biomass, coal and binder were mixed and put in a forming machine to shape the final briquetting. To fix the amount of loess and lime at 30%, the amount of reed and giant reed ranged from 25% to 55% with an interval of 10%. Other treatments were the same as above. Li Fengmin and Zhang Mingquan / Energy Procedia 5 (2011) 2449–2454 2451

2.3 Analytical methods

Put ten weighed briquettings in a box whose bottom can be opened. Then elevate the box up to 2m, open the bottom and let the briquettings fall freely to 12mm thick steel plate three times. Finally the briquettings are passed through a 13mm sieve and the proportion of briquettings >13mm is taken as the drop strength. Place the briquettings in 27ć water for 30s. The ratio of amount of absorbed water to original weight reflects water impermeability of biomass briquetting. Weigh 2̚3g of ground samples and put them in an ceramic crucible which is iglossed to constant weight. Then put the ceramic crucible in muffle furnace where the samples are heated at 600ć for six hours. At last the ceramic crucible is cooled down in a dryer. The ratio of amount of samples to original weight reflects ash content. The calorific value of biomass briquetting is meas ured by oxygen bomb calorimeter JR-3500.

3. Results and discussion

3.1 Effect of binder content on properties of biomass briquetting

The amount of binder affects property of biomass briquetting. Fig. 1(a) reflects the effect of binder content on the drop strength of biomass briquetting. We can clearly see that with increasing amount of binder, the drop strength of biomass briquetting increases firstly and then decreases and reaches its maximun when the amount of binder is 30% where the drop strength of giant reed briquetting and reed briquetting is 96% and 97% respectively when loess serves as the binder and is 89% and 65% respectively when lime serves as the binder. The drop strength of giant reed briquetting is larger than reed briquetting when the binder is all the same. Maybe it results from the fact that giant reed powder has larger treacliness and density than reed powder. For the same biomass, the drop strength of briquetting with lime is larger than briquetting with loess when binder content is low, but the results are contrary when the binder content is high. The amount of binder affects properties of biomass briquetting. Fig. 1(b) reflects the effect of binder content on water impermeability of biomass briquetting. As can be seen from the figure, with increasing amount of binder, water impermeability of biomass briquetting decreases firstly and then increases and reaches its minimun when the amount of binder is 30% where water impermeability of giant reed briquetting and reed briquetting is 6% and 28% respectively when loess serves as the binder and is 5% and 20% respectively when lime serves as the binder. Water impermeability of giant reed briquetting is smaller than reed briquetting when the binder is all the same. It results from the fact that reed powder has stronger water absorbing power. When the binder content ranges from 10% to 30%, water impermeability of giant reed briquetting with loess and giant reed briquetting with lime almost has no difference. But when the binder content is 1% and 40%, water impermeability of giant reed briquetting with lime is obviously larger than giant reed briquetting with loess. As regards to reed briquetting, the briquetting with loess is larger than the briquetting with lime. The amount of binder affects combustion properties of biomass briquetting. Fig. 1(c) reflects the effect of binder content on calorific value of biomass briquetting. As can be seen from the figure, calorific value of biomass briquetting decreases with increasing amount of binder because availability of combustive components of briquetting decreases with increasing amount of binder. The calorific value of giant reed briquetting with loess is larger than reed briquetting with loess and the results are contrary when the binder is lime. The calorific value of giant reed briquetting and reed briquetting is between 10.3MJ/kg and19.8MJ/kg. When the binder content reaches 30%, that is to say, mechanical properties of briquetting 2452 Li Fengmin and Zhang Mingquan / Energy Procedia 5 (2011) 2449–2454

are the best, the calorific value of giant reed briquetting with loess and reed briquetting with loess is 14.2MJ/kg and 13.4MJ/kg respectively and the calorific value of giant reed briquetting with lime and reed briquetting with lime is 13.7MJ/kg and 14.5MJ/kg respectively. The amount of binder affects ash content of biomass briquetting. Fig. 1(d) reflects the effect of binder content on ash ontet of biomass briquetting. As can be seen from the figure, ash content of biomass briquetting increases with increasing amount of binder because availability of combustive components of briquetting decreases with increasing amount of binder. When the binder is loess, the ash content of giant reed briquetting is larger than reed briquetting and when the binder is lime, the ash content of giant reed briquetting is smaller than reed briquetting in low binder content while the results are contrary in high binder content. When the biomass is giant reed, the ash content of briquetting with loess is larger than briquetting with lime. But the results are opposite when the biomass is reed. a 120 b 100 哴൏㣖ㄩ哴൏㣖㣷 100 ⸣⚠㣖ㄩ ⸣⚠㣖㣷 80 80 60 60

40 40 Drop strength/% strength/% Drop

20 20 哴൏㣖ㄩ哴൏㣖㣷 Water impermeability/% ⸣⚠㣖ㄩ ⸣⚠㣖㣷 0 0

0 10 20 30 40 50 0 10 20 30 40 50

Binder content/% Binder content/% c c d 60 d 25 哴൏㣖ㄩ哴൏㣖㣷 ⸣⚠㣖ㄩ ⸣⚠㣖㣷 50 20

kJ/kg 3 40 15 30 Ash content/% content/% Ash 10 20 哴൏㣖ㄩ哴൏㣖㣷 Calorific value/10 Calorific ⸣⚠㣖ㄩ ⸣⚠㣖㣷 5 10 0 10 20 30 40 50 0 10 20 30 40 50

Binder content/% Binder content/%

Fig. 1. Effect of binder content on propert ies of biomass briquett ing.Ʒ anG ᇞ represent giant reed briquett ing wit h loess and lime respectively.Ƶ and ƶ represent reed briquetting with loess and lime respectively.

3.2 Effect of biomass content on properties of biomass briquetting

The amount of biomass affects properties of biomass briquetting. Fig. 2(a) reflects the effect of biomass content on the drop strength of biomass briquetting. We can clearly see that with increasing amount of biomass, the drop strength of biomass briquetting increases firstly and then decreases and reaches its maximun when the amount of biomass is 45% where the drop strength of briquetting with loess and briquetting with lime is 90% and 55% respectively when giant serves as the biomass and is both Li Fengmin and Zhang Mingquan / Energy Procedia 5 (2011) 2449–2454 2453

74% when reed serves as the biomass. The drop strength of briquetting with loess is larger than briquetting with lime because loess has larger treacliness than lime. For the same binder, the drop strength of giant reed briquetting is larger than reed briquetting in low biomass content, but the results are contrary when the biomass content is high. The amount of biomass affects properties of biomass briquetting. Fig. 2(b) reflects the effect of biomass content on water impermeability of biomass briquetting. As can be seen from the figure, with increasing amount of biomass, water impermeability of biomass briquetting increases gradually. The other three briquttings do not increase greatly except for giant briquetting with loess. When biomass content is ̰ 45%, water impermeability of briquetting is 12%̚47%. Loess served as the binder, when biomass content ̰ 45%, water impermeability of giant reed briquetting is larger than reed briquetting and the results are oppsite when biomass content >45%. As regards to reed briquetting, briquetting with loess is lager than briquetting with lime. For giant reed briquetting, when biomass content is <35%, briquetting with lime is larger than briquetting with loess and the results are contrary when biomass content is >35%. The amount of biomass affects combustion properties of biomass briquetting. Fig. 2(c) reflects the effect of biomass content on calorific value of biomass briquetting. As can be seen from the figure, calorific value of biomass briquetting decreases with increasing amount of biomass because calorific value of b io mass is sma lle r than coal. The ca lorific value of reed briquetting with lime is s maller than the other three briquettings which have no obvious difference. In this study, calorific value of four briquettings is between 11.7MJ/kg and 14.9MJ/kg. When the biomass content reaches 45%, that is to say, the mechanical properties of briquetting are the best, the calorific value of giant reed briquetting with loess and reed briquetting with loess is 13.2MJ/kg and 12.8MJ/kg respectively and the calorific value of giant reed briquetting with lime and reed briquetting with lime is 12.2MJ/kg and 11.5MJ/kg respectively. The amount of biomass affects ash content of biomass briquetting. Fig. 2(d) reflects the effect of biomass content on ash content of biomass briquetting. As can be seen from the figure, ash content of biomass briquetting decreases with increasing amount of biomass because the ash content of biomass is smaller than that of coal. When the binder is loess, ash content of giant reed briquetting and reed briquetting has no obvious difference. When lime serves as the binder, ash content of giant reed briquetting is larger than reed briquetting in low biomass content. As mechanical properties of briquetting are the best, loess served as the binder, ash content of giant reed briquetting and reed briquetting is 13.2% and 12.8% respectively and lime served as the binder, ash content of giant reed briquetting and reed briquetting is 12.2% and 11.5% respectively.

a 100 b 140 㣖ㄩ哴൏ 㣖ㄩ⸣⚠ 120 㣖㣷哴൏ 㣖㣷⸣⚠ 80 100

80 60 60

Drop strength/% strength/% Drop 40 40 㣖ㄩ哴൏ 㣖ㄩ⸣⚠ Water impermeability 20 㣖㣷哴൏ 㣖㣷⸣⚠ 20 0 25 35 45 55 25 35 45 55

Biomass cont ent/% Biomass content/%

2454 Li Fengmin and Zhang Mingquan / Energy Procedia 5 (2011) 2449–2454

c 17 d 50

kJ/kg kJ/kg 15

3 45

kJ/kg

3 40 11

content/% Ash 35 Calorific value/10 Calorific value/10 9 㣖ㄩ哴൏ 㣖ㄩ⸣⚠ 㣖ㄩ哴൏ 㣖ㄩ⸣⚠ 㣖㣷哴൏ 㣖㣷⸣⚠ 㣖㣷哴൏ 㣖㣷⸣⚠ 7 30 25 35 45 55 25 35 45 55

Biomass cont ent/% Biomass content/%

Fig. 2. Effect of biomass content on propert ies of biomass briquett ing.Ʒ and Ƶ represent giant reed briquetting with loess and lime respectively. ᇞ and ƶ represent reed briquet t ing wit h loess and lime respectively.

4. Conclusion

In the molding process, binder has observably impact on biomass briquette forming effect, mechanical properties and combustion properties and when giant reed and reed serve as the biomass, the best addition of the binder is 30%. Biomass content is another important factor. When loess and lime serve as the binder, the best addition of the biomass is 45%.

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