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Study of ratio of energy consumption and gained energy during briquetting process for glycerin-biomass briquette fuel
Fuel 115 (2014) 186–189
Contents lists available at SciVerse ScienceDirect
Fuel journal homepage: www.elsevier.com/locate/fuel
Study of ratio of energy consumption and gained energy during briquetting process for glycerin-biomass briquette fuel Chatcharin Sakkampang a, Tanakorn Wongwuttanasatian a,b,⇑ a b
Department of Mechanical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002, Thailand Centers for Alternative Energy Research and Development (AERD), Khon Kaen University, Khon Kaen 40002, Thailand
h i g h l i g h t s Glycerin-biomass briquette fuels were studied. Energy used during processes was compared to HV of the briquette. Actual HV and correlated HV were compared and found to be within 5%. Relationship of total HV was a function of mass fraction of its compositions.
a r t i c l e
i n f o
Article history: Received 12 November 2012 Received in revised form 5 July 2013 Accepted 5 July 2013 Available online 19 July 2013 Keywords: Glycerin Biomass Heating value Briquette fuel
a b s t r a c t This paper investigated the feasibility of using the mixture of glycerin and biomass as an alternative fuel by measuring the energy used in the densification process and the energy gained from the briquette fuels. The correlation of the heating values between the calculated values and the actual values was also determined. Rice husk, sawdust, sugarcane bagasse, and sugarcane leaf were used as biomass. Different amounts of glycerin were mixed with the biomass during the densification process. The ratios of the energy used compared with the energy gained were approximately 1–3% for domestic-scale solar drying condition and 12–18% for industrial-scale machine drying condition. Heating values of the briquettes increased with the increasing amount of glycerin. Using the mixture of glycerin and biomass in the densification process was considered feasible to be further developed as an alternative fuel. Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction In Thailand, an abundance of waste, e.g., palm, jatropha, coconut oil, and used vegetable oil, can be converted to biodiesel. As a result, the Thai government has encouraged and supported biodiesel production in order to reduce crude oil import. The Ministry of Energy also established a policy to increase energy selfdependence by introducing B5 (95% diesel and 5% biodiesel) to the community and the industry [1]. This policy has resulted in the increase in biodiesel production and producers both at the community scale and the industrial scale. During the biodiesel production, glycerin is created as a by-product (1 ton of biodiesel yields 0.11 ton of crude glycerin) [2]. Purified glycerin is commonly used in the cosmetic and food industries but the cost of purifying crude glycerin is relatively high [3–5]. Crude glycerin has high viscosity and flash point, so it cannot be directly used as a fuel, unless ⇑ Corresponding author at: Department of Mechanical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002, Thailand. Tel.: +66 43202845 (office), +66 803173170 (mobile); fax: +66 43202849. E-mail addresses: [email protected] (C. Sakkampang), [email protected] (T. Wongwuttanasatian). 0016-2361/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.fuel.2013.07.023
it is mixed with other fuels [6,7]. In addition, it is contaminated with salt, alcohol, heavy metals, and water, and normally discarded as waste. Currently, there are many large-scale biodiesel manufacturers and the amount of crude glycerin is greater than the demand of the industry, causing the price of crude glycerin to plummet [3]. Moreover, the number of community-scale biodiesel producers has also risen, creating additional amounts of crude glycerin. The amount of glycerin waste has been rising and creating storage and disposal problems. Nevertheless, the staggering abundance of glycerin and its low price are considered economically attractive to be studied for alternative fuel. Oezkan et al. observed the performance of biodiesel with glycerin in an engine test and found out that biodiesel with glycerin could be used as fuel with some modifications [8]. Chaiyaomporn and Chavalparit used palm fiber and palm shell mixed with glycerin as a raw material to find the optimum ratio of pelletized fuel, by which they investigated the physical properties of the pellet by varying the ratio of mixture and particle size of raw material. The result showed that the optimum ratio of pelletized fuel (palm fiber:water:waste glycerin) 50:10:40, yielding 982.2 kg/m3 and 22.5 MJ/kg for the specific gravity and the heating value, respectively [9]. Brady and Tam evaluated the energy of fuel
C. Sakkampang, T. Wongwuttanasatian / Fuel 115 (2014) 186–189
pellets containing sawdust and glycerin in a ratio of 1.0–1.3 and found out that the obtained energy content could be adopted as an alternative fuel [10]. Raslavicˇius evaluated the proportions, durability, characterization of combusion regimes, and emission characteristics of fuel briquettes (glycerol with woody cutting waste) and found out that crude glycerol was suitable as a partial substitute for woody cutting waste in the briquette production. In addition, the fuel briquettes did not show negative impact on the environment because their combusion exposed low CO, SO2, and NOx emission levels [11]. To create fuel briquettes by mixing glycerin with biomass, suitable biomass materials must be selected. Farm wastes such as rice husk, sawdust, sugarcane bagasse, sugarcane leaf, coconut shells, and palm fiber can be considered because they are abundant in Thailand. The only drawback for most of the farm wastes is their bulk volume, which demands large storage and high transportation cost. In general, the steps to convert biomass into energy are shown in Fig. 1a. Biomass are collected and transported, and then converted into energy by the burning process. However, in order to achieve higher energy per volume, a densification process (compacting biomass into fuel briquettes with pressure) is usually added as shown in Fig. 1b [12]. The densification process involves drying, shredding, and pressing, which needs costly equipments and a few energy sources. Since the densification process is an addition to the general biomass energy conversion steps, it is crucial to investigate the ratio of energy consumption and gained energy of the densification process. Based on the aforementioned works, it is also important to determine the feasibility of using the mixture of glycerol and biomass as an alternative fuel. Thus, this research only studied the ratio of energy consumption including drying, shred, and compacted process accounting for the gained energy from the glycerin-biomass briquettes. Different glycerin-biomass ratios were also investigated in order to obtain the optimal ratio for the densification process. In addition, the correlation between the calculated heating values and the measured heating values was examined. Note that the calculation of the energy used in the transportation and collection processes depends on many factors such as distance between the experimental site and the collection site, type of vehi-
187
cle used for biomass collection, labor cost, etc. [13]. As a result, the energy calculation needs to be dealt with extensively and should be a separate study of its own. However, in this study, the transportation and collection processes could be assumed as a fixed parameter normally occurred in the biomass energy conversion. 2. Experimental methods 2.1. Materials Four types of biomass normally found from farm wastes were considered in this study: (1) rice husk, (2) sawdust, (3) sugarcane bagasse, and (4) sugarcane leaf. These raw materials were dried and shredded to have approximately 0.2–2.0 mm in length. During the densification process, certain amounts of glycerin were mixed with these raw materials to increase the heating value of briquettes. Note that the type of densification process carried out here was a cold process using molasses as the bonding agent. Seven different ratios (biomass:molass:glycerin) used in the densification process were: (1) 90:10:0, (2) 85:10:10, (3) 80:10:10, (4) 75:10:15, (5) 70:10:20, (6) 65:10:25, and (7) 60:10:30. Note that briquettes could not be easily deformed if the amount of glycerin was higher than 35% [14]. 2.2. Machines The shredding machine used in this study was dual-function with a roller crusher (2 hp motor) and a hammer mill (3 hp motor) having a production capacity of 19.87 kg/h. The densification machine used was a pressure-adjustable piston press (4 hp motor) having a production rate of 30–42 kg/h. The pressure used to compact the materials was 10 MPa [14]. 2.3. Testing procedure In order to observe the energy used in the densification process and the energy gained from briquette fuels, two conditions were studied: (1) domestic-scale solar drying, and (2) industry-scale
Fig. 1. Conversion of biomass to energy diagram.
188
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heating values increased with increasing in amount of glycerin because glycerin has a higher heating value than those of the biomass.
Table 1 Required steps used in the densification process of each biomass. Type Rice husk Sawdust Sugarcane bagasse Sugarcane leaf
Drying p p p p
Shredding – – p p
Briquetting p p p p
p ‘‘ ’’ Represents ‘‘required’’ and ‘‘–’’ represents ‘‘not required’’.
Table 2 Heating values of glycerin and biomass. Material
Heating value (MJ/kg)
Glycerin Rice husk Sawdust Sugarcane bagasse Sugarcane leaf
24.59 13.40 17.31 16.19 18.36
machine drying. For the domestic-scale solar drying condition, the energy used in the drying process was not considered because the biomass were dried by solar energy (E1 = 0). For the industry-scale machine drying condition, the biomass were dried by a drying machine (E1 – 0). For both conditions, the biomass were shredded (E2) and compacted (E3) shown in Fig. 1b. Note that rice husk and sawdust did not require shredding as shown in Table 1. During the briquetting process, certain amounts of glycerin were added to obtain the desired set ratios. In the shredding and briquetting steps, energy values were recorded by using a power analyzer. After the briquetting process, fuel briquettes were obtained and their heating values (HV) were measured based on ASTM D240 standard. These values were then compared with the total consumed energy from the drying, shredding, and briquetting processes.
3.2. Ratios of the energy consumption and the gained energy of the densification process Tables 4 and 5 show the energy consumption values of the shredding process and the briquetting process, respectively. In the briquetting process, the required energy values ranged from 0.04 to 0.11 MJ/kg, indicating that the increased amount of glycerin did not significantly affect the energy consumption. The comparison between the energy used in the densification process and the energy gained from different briquette fuels is displayed in Table 6. For the industrial-scale machine drying condition, the drying energy required was approximately 2.25 MJ/kg of biomass. This energy was calculated based on the work of Fagernäs et al. by selecting the moisture content reduction from 60% to 15% of a kilogram of water [15]. The results showed that the energy used in the densification process ranged from 12.13% to 17.64% of the energy gained from the briquette fuels. It could be observed that the drying process consumed the major portions of the energy used. For the domestic-scale solar drying condition, the ratio of energy consumed in the densification process to the energy gained from the obtained briquette fuels ranged from 0.26% to 2.62%. Note that the energy used in the drying process was not required in this condition. Thus, the ratios of the energy used in the densification process to the energy gained from the briquette fuels could also be obtained from Table 6 by removing the energy used in the drying process. 3.3. Relationship between the heating values and the glycerin-biomass ratios The relationship between the heating values and the mass fractions of glycerin could be written in the following form:
3. Experimental results
HVtot ¼ m1 HV1 þ m2 ð24:59Þ þ 0:1ð8Þ
3.1. Heating values
where HVtot is the total heating value of a briquette fuel (MJ/kg), m1 the mass fraction of biomass, HV1 the heating value of biomass, m2 the mass fraction of glycerin, and 0.1 (or 10%) is the mass fraction of molass. The heating values of glycerin and molass were 24.59 MJ/kg and 8 MJ/kg, respectively. Based on Eq. (1), the calculated heating values of the fuel briquettes having different glycerin-biomass ratios were obtained.
By using a standard bomb calorimeter, the heating values of glycerin, biomass, and obtained fuel briquettes were measured. The heating values of glycerin and biomass are shown in Table 2. The heating values of the obtained briquettes with different glycerinbiomass ratios are shown in Table 3. It can be observed that the
ð1Þ
Table 3 Heating values of briquette fuels. Ratio of briquettes (biomass:molass:glycerin)
90:10:0 85:10:5 80:10:10 75:10:15 70:10:20 65:10:25 60:10:30
Heating value (MJ/kg) Rice husk
Sawdust
Sugarcane bagasse
Sugarcane leaf
13.26 14.06 14.18 14.73 14.84 15.50 15.94
16.78 16.99 17.51 17.52 17.48 18.83 18.96
15.77 16.09 16.33 16.45 17.42 17.87 18.19
17.72 18.13 18.45 18.70 18.69 19.28 19.59
Table 4 Energy consumed in the shredding process.
a
Materials
Capacity (kg/h)
Electric power (kW)
Energy used (kW h/kg)
Energy used (MJ/kg)
Rice huska Sawdusta Sugarcane bagasse Sugarcane leaf
– – 19.87 32.01
– – 2.27 2.32
0 0 0.11 0.07
0 0 0.41 0.26
Shredding was not required.
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C. Sakkampang, T. Wongwuttanasatian / Fuel 115 (2014) 186–189 Table 5 Energy consumed in the briquetting process. Ratio of briquettes (biomass:molass:glycerin)
90:10:0 85:10:5 80:10:10 75:10:15 70:10:20 65:10:25 60:10:30
Energy used (MJ/kg) Rice husk
Sawdust
Sugarcane bagasse
Sugarcane leaf
0.0977 0.1014 0.1002 0.0926 0.0980 0.0940 0.0948
0.0461 0.0476 0.0485 0.0476 0.0510 0.0489 0.0493
0.0433 0.0475 0.0493 0.0484 0.0562 0.0536 0.0546
0.0542 0.0492 0.0519 0.0512 0.0548 0.0547 0.0510
Table 6 Total energy consumption in the densification process of the industrial-scale drying machine condition. Material
Energy used in drying process (MJ/kg)
Energy used in shedding process (MJ/kg)
Energy used in briquetting process (MJ/kg)
Total energy used (MJ/kg)
Heating value (MJ/kg)
Energy used compare to gained energy (%)
Rice husk Sawdust Sugarcane bagasse Sugarcane leaf
2.25 2.25 2.25
– – 0.26
0.09–0.10 0.04–0.05 0.04–0.06
2.34–2.35 2.29–2.30 2.55–2.57
13.26–15.94 16.78–18.96 15.77–18.19
14.74–17.64 12.13–13.64 14.12–16.17
2.25
0.41
0.05–0.06
2.71–2.72
17.72–19.59
13.88–15.29
mass. The obtained results indicated that the mixture of glycerin and biomass was considered feasible to be further developed as an alternative fuel. Acknowledgements This research project was financially supported by the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission, through the Biofuel Cluster of Khon Kaen University. I would like to gratefully thank to Center for Alternative Energy Research and Development, Khon Kaen University, Thailand. References
Fig. 2. The comparisons of correlated HV and the actual HV in difference ratios of glycerin and biomass.
These values were then compared with the measured heating values (Table 3) and illustrated in Fig. 2. It could be observed that the measured heating values were within ±5% errors and correlated well with the calculated heating values. It could be seen that increasing amounts of glycerin led to the increase of the heating values and the optimum glycerin-biomass ratio found in this study was 30%. This value was also in a suitable range of the compressive strength of briquette fuel found in the previous study [14]. The obtained results indicated that the mixture of glycerin and biomass was considered feasible to be further developed as an alternative fuel. 4. Conclusions This research investigated the ratios of the energy consumption during densification process and the gained energy of the briquette fuels having different ratios of glycerin and biomass. The results showed that the energy consumptions were 1–3% of the energy gained for the domestic-scale solar drying condition, and 12–18% of the energy gained for the industrial-scale condition. In addition, the optimum ratio of glycerin mixed with biomass was 30% by
[1] Phalakornkule C, Petiruksakul A, Puthavithi W. Biodiesel production in a small community: case study in Thailand. Resour Conserv Recycl 2009;53:129–35. [2] Behr A, Eilting J, Irawadi K, Leschinski J, Lindner F. Improved utilisation of renewable resources: new important derivatives of glycerol. Green Chem 2008;10:13–30. [3] Hedtke D. Glycerine processing. In Bailey’s industrial oil & fat products, vol. 5, New York: John Wiley & Sons; 1996, p. 275–08. [4] O’Driscoll C. Seeking a new role for glycerol. Biofuels Bioprod Bioref 2007;1:6–7. [5] Bournay L, Casanave D, Delfort B, Hillion G, Chodorge J. New heterogeneous process for biodiesel production: a way to improve the quality and the value of the crude glycerin produced by biodiesel plants. Catal Today 2005;106:190–2. [6] Queirós P, Costa M, Carvalho R. Co-combustion of crude glycerin with natural gas and hydrogen. Proc Combust Inst 2012;34:2759–67. [7] Bohon MD, Metzger BA, Linak WP, King CJ, Roberts WL. Glycerol combustion and emissions. Proc Combust Inst 2011;33:2717–24. [8] Oezkan M, Ergenc AT, Deniz O. Experimental performance analysis of biodiesel, traditional diesel and biodiesel with glycerine. Turkish J Eng Env Sci 2005;29:89–94. [9] Chaiyaomporn K, Chavalparit O. Fuel pellets production from biodiesel waste. Environ Asia 2010;3:103–10. [10] Brady S, Tam K. Zero waste biodiesel: using glycerin and biomass to create renewable energy. UCR Undergrad Res J 2008;2:5–11. [11] Raslavicˇius L. Characterization of the woody cutting waste briquettes containing absorbed glycerol. Biomass Bioenergy 2012;45:144–51. [12] Wilaipon P. Physical characteristics of maize cob briquette under moderate die pressure. Am J Appl Sci 2007;4:995–8. [13] Rentizelas AA, Tolis AJ, Tatsiopoulos IP. Logistics issues of biomass: the storage problem and the multi-biomass supply chain. Renew Sust Energy Rev 2009;13:887–94. [14] Sakkampang C, Wongwuttanasatian T. Design of briquettizing machine for biomass briquette fuel. Adv Sci Lett 2012;13:565–9. [15] Fagernäs L, Brammer J, Wilén C, Lauer M, Verhoeff F. Drying of biomass for second generation synfuel production. Biomass Bioenergy 2010;34:1267–77.
Contents lists available at SciVerse ScienceDirect
Fuel journal homepage: www.elsevier.com/locate/fuel
Study of ratio of energy consumption and gained energy during briquetting process for glycerin-biomass briquette fuel Chatcharin Sakkampang a, Tanakorn Wongwuttanasatian a,b,⇑ a b
Department of Mechanical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002, Thailand Centers for Alternative Energy Research and Development (AERD), Khon Kaen University, Khon Kaen 40002, Thailand
h i g h l i g h t s Glycerin-biomass briquette fuels were studied. Energy used during processes was compared to HV of the briquette. Actual HV and correlated HV were compared and found to be within 5%. Relationship of total HV was a function of mass fraction of its compositions.
a r t i c l e
i n f o
Article history: Received 12 November 2012 Received in revised form 5 July 2013 Accepted 5 July 2013 Available online 19 July 2013 Keywords: Glycerin Biomass Heating value Briquette fuel
a b s t r a c t This paper investigated the feasibility of using the mixture of glycerin and biomass as an alternative fuel by measuring the energy used in the densification process and the energy gained from the briquette fuels. The correlation of the heating values between the calculated values and the actual values was also determined. Rice husk, sawdust, sugarcane bagasse, and sugarcane leaf were used as biomass. Different amounts of glycerin were mixed with the biomass during the densification process. The ratios of the energy used compared with the energy gained were approximately 1–3% for domestic-scale solar drying condition and 12–18% for industrial-scale machine drying condition. Heating values of the briquettes increased with the increasing amount of glycerin. Using the mixture of glycerin and biomass in the densification process was considered feasible to be further developed as an alternative fuel. Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction In Thailand, an abundance of waste, e.g., palm, jatropha, coconut oil, and used vegetable oil, can be converted to biodiesel. As a result, the Thai government has encouraged and supported biodiesel production in order to reduce crude oil import. The Ministry of Energy also established a policy to increase energy selfdependence by introducing B5 (95% diesel and 5% biodiesel) to the community and the industry [1]. This policy has resulted in the increase in biodiesel production and producers both at the community scale and the industrial scale. During the biodiesel production, glycerin is created as a by-product (1 ton of biodiesel yields 0.11 ton of crude glycerin) [2]. Purified glycerin is commonly used in the cosmetic and food industries but the cost of purifying crude glycerin is relatively high [3–5]. Crude glycerin has high viscosity and flash point, so it cannot be directly used as a fuel, unless ⇑ Corresponding author at: Department of Mechanical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002, Thailand. Tel.: +66 43202845 (office), +66 803173170 (mobile); fax: +66 43202849. E-mail addresses: [email protected] (C. Sakkampang), [email protected] (T. Wongwuttanasatian). 0016-2361/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.fuel.2013.07.023
it is mixed with other fuels [6,7]. In addition, it is contaminated with salt, alcohol, heavy metals, and water, and normally discarded as waste. Currently, there are many large-scale biodiesel manufacturers and the amount of crude glycerin is greater than the demand of the industry, causing the price of crude glycerin to plummet [3]. Moreover, the number of community-scale biodiesel producers has also risen, creating additional amounts of crude glycerin. The amount of glycerin waste has been rising and creating storage and disposal problems. Nevertheless, the staggering abundance of glycerin and its low price are considered economically attractive to be studied for alternative fuel. Oezkan et al. observed the performance of biodiesel with glycerin in an engine test and found out that biodiesel with glycerin could be used as fuel with some modifications [8]. Chaiyaomporn and Chavalparit used palm fiber and palm shell mixed with glycerin as a raw material to find the optimum ratio of pelletized fuel, by which they investigated the physical properties of the pellet by varying the ratio of mixture and particle size of raw material. The result showed that the optimum ratio of pelletized fuel (palm fiber:water:waste glycerin) 50:10:40, yielding 982.2 kg/m3 and 22.5 MJ/kg for the specific gravity and the heating value, respectively [9]. Brady and Tam evaluated the energy of fuel
C. Sakkampang, T. Wongwuttanasatian / Fuel 115 (2014) 186–189
pellets containing sawdust and glycerin in a ratio of 1.0–1.3 and found out that the obtained energy content could be adopted as an alternative fuel [10]. Raslavicˇius evaluated the proportions, durability, characterization of combusion regimes, and emission characteristics of fuel briquettes (glycerol with woody cutting waste) and found out that crude glycerol was suitable as a partial substitute for woody cutting waste in the briquette production. In addition, the fuel briquettes did not show negative impact on the environment because their combusion exposed low CO, SO2, and NOx emission levels [11]. To create fuel briquettes by mixing glycerin with biomass, suitable biomass materials must be selected. Farm wastes such as rice husk, sawdust, sugarcane bagasse, sugarcane leaf, coconut shells, and palm fiber can be considered because they are abundant in Thailand. The only drawback for most of the farm wastes is their bulk volume, which demands large storage and high transportation cost. In general, the steps to convert biomass into energy are shown in Fig. 1a. Biomass are collected and transported, and then converted into energy by the burning process. However, in order to achieve higher energy per volume, a densification process (compacting biomass into fuel briquettes with pressure) is usually added as shown in Fig. 1b [12]. The densification process involves drying, shredding, and pressing, which needs costly equipments and a few energy sources. Since the densification process is an addition to the general biomass energy conversion steps, it is crucial to investigate the ratio of energy consumption and gained energy of the densification process. Based on the aforementioned works, it is also important to determine the feasibility of using the mixture of glycerol and biomass as an alternative fuel. Thus, this research only studied the ratio of energy consumption including drying, shred, and compacted process accounting for the gained energy from the glycerin-biomass briquettes. Different glycerin-biomass ratios were also investigated in order to obtain the optimal ratio for the densification process. In addition, the correlation between the calculated heating values and the measured heating values was examined. Note that the calculation of the energy used in the transportation and collection processes depends on many factors such as distance between the experimental site and the collection site, type of vehi-
187
cle used for biomass collection, labor cost, etc. [13]. As a result, the energy calculation needs to be dealt with extensively and should be a separate study of its own. However, in this study, the transportation and collection processes could be assumed as a fixed parameter normally occurred in the biomass energy conversion. 2. Experimental methods 2.1. Materials Four types of biomass normally found from farm wastes were considered in this study: (1) rice husk, (2) sawdust, (3) sugarcane bagasse, and (4) sugarcane leaf. These raw materials were dried and shredded to have approximately 0.2–2.0 mm in length. During the densification process, certain amounts of glycerin were mixed with these raw materials to increase the heating value of briquettes. Note that the type of densification process carried out here was a cold process using molasses as the bonding agent. Seven different ratios (biomass:molass:glycerin) used in the densification process were: (1) 90:10:0, (2) 85:10:10, (3) 80:10:10, (4) 75:10:15, (5) 70:10:20, (6) 65:10:25, and (7) 60:10:30. Note that briquettes could not be easily deformed if the amount of glycerin was higher than 35% [14]. 2.2. Machines The shredding machine used in this study was dual-function with a roller crusher (2 hp motor) and a hammer mill (3 hp motor) having a production capacity of 19.87 kg/h. The densification machine used was a pressure-adjustable piston press (4 hp motor) having a production rate of 30–42 kg/h. The pressure used to compact the materials was 10 MPa [14]. 2.3. Testing procedure In order to observe the energy used in the densification process and the energy gained from briquette fuels, two conditions were studied: (1) domestic-scale solar drying, and (2) industry-scale
Fig. 1. Conversion of biomass to energy diagram.
188
C. Sakkampang, T. Wongwuttanasatian / Fuel 115 (2014) 186–189
heating values increased with increasing in amount of glycerin because glycerin has a higher heating value than those of the biomass.
Table 1 Required steps used in the densification process of each biomass. Type Rice husk Sawdust Sugarcane bagasse Sugarcane leaf
Drying p p p p
Shredding – – p p
Briquetting p p p p
p ‘‘ ’’ Represents ‘‘required’’ and ‘‘–’’ represents ‘‘not required’’.
Table 2 Heating values of glycerin and biomass. Material
Heating value (MJ/kg)
Glycerin Rice husk Sawdust Sugarcane bagasse Sugarcane leaf
24.59 13.40 17.31 16.19 18.36
machine drying. For the domestic-scale solar drying condition, the energy used in the drying process was not considered because the biomass were dried by solar energy (E1 = 0). For the industry-scale machine drying condition, the biomass were dried by a drying machine (E1 – 0). For both conditions, the biomass were shredded (E2) and compacted (E3) shown in Fig. 1b. Note that rice husk and sawdust did not require shredding as shown in Table 1. During the briquetting process, certain amounts of glycerin were added to obtain the desired set ratios. In the shredding and briquetting steps, energy values were recorded by using a power analyzer. After the briquetting process, fuel briquettes were obtained and their heating values (HV) were measured based on ASTM D240 standard. These values were then compared with the total consumed energy from the drying, shredding, and briquetting processes.
3.2. Ratios of the energy consumption and the gained energy of the densification process Tables 4 and 5 show the energy consumption values of the shredding process and the briquetting process, respectively. In the briquetting process, the required energy values ranged from 0.04 to 0.11 MJ/kg, indicating that the increased amount of glycerin did not significantly affect the energy consumption. The comparison between the energy used in the densification process and the energy gained from different briquette fuels is displayed in Table 6. For the industrial-scale machine drying condition, the drying energy required was approximately 2.25 MJ/kg of biomass. This energy was calculated based on the work of Fagernäs et al. by selecting the moisture content reduction from 60% to 15% of a kilogram of water [15]. The results showed that the energy used in the densification process ranged from 12.13% to 17.64% of the energy gained from the briquette fuels. It could be observed that the drying process consumed the major portions of the energy used. For the domestic-scale solar drying condition, the ratio of energy consumed in the densification process to the energy gained from the obtained briquette fuels ranged from 0.26% to 2.62%. Note that the energy used in the drying process was not required in this condition. Thus, the ratios of the energy used in the densification process to the energy gained from the briquette fuels could also be obtained from Table 6 by removing the energy used in the drying process. 3.3. Relationship between the heating values and the glycerin-biomass ratios The relationship between the heating values and the mass fractions of glycerin could be written in the following form:
3. Experimental results
HVtot ¼ m1 HV1 þ m2 ð24:59Þ þ 0:1ð8Þ
3.1. Heating values
where HVtot is the total heating value of a briquette fuel (MJ/kg), m1 the mass fraction of biomass, HV1 the heating value of biomass, m2 the mass fraction of glycerin, and 0.1 (or 10%) is the mass fraction of molass. The heating values of glycerin and molass were 24.59 MJ/kg and 8 MJ/kg, respectively. Based on Eq. (1), the calculated heating values of the fuel briquettes having different glycerin-biomass ratios were obtained.
By using a standard bomb calorimeter, the heating values of glycerin, biomass, and obtained fuel briquettes were measured. The heating values of glycerin and biomass are shown in Table 2. The heating values of the obtained briquettes with different glycerinbiomass ratios are shown in Table 3. It can be observed that the
ð1Þ
Table 3 Heating values of briquette fuels. Ratio of briquettes (biomass:molass:glycerin)
90:10:0 85:10:5 80:10:10 75:10:15 70:10:20 65:10:25 60:10:30
Heating value (MJ/kg) Rice husk
Sawdust
Sugarcane bagasse
Sugarcane leaf
13.26 14.06 14.18 14.73 14.84 15.50 15.94
16.78 16.99 17.51 17.52 17.48 18.83 18.96
15.77 16.09 16.33 16.45 17.42 17.87 18.19
17.72 18.13 18.45 18.70 18.69 19.28 19.59
Table 4 Energy consumed in the shredding process.
a
Materials
Capacity (kg/h)
Electric power (kW)
Energy used (kW h/kg)
Energy used (MJ/kg)
Rice huska Sawdusta Sugarcane bagasse Sugarcane leaf
– – 19.87 32.01
– – 2.27 2.32
0 0 0.11 0.07
0 0 0.41 0.26
Shredding was not required.
189
C. Sakkampang, T. Wongwuttanasatian / Fuel 115 (2014) 186–189 Table 5 Energy consumed in the briquetting process. Ratio of briquettes (biomass:molass:glycerin)
90:10:0 85:10:5 80:10:10 75:10:15 70:10:20 65:10:25 60:10:30
Energy used (MJ/kg) Rice husk
Sawdust
Sugarcane bagasse
Sugarcane leaf
0.0977 0.1014 0.1002 0.0926 0.0980 0.0940 0.0948
0.0461 0.0476 0.0485 0.0476 0.0510 0.0489 0.0493
0.0433 0.0475 0.0493 0.0484 0.0562 0.0536 0.0546
0.0542 0.0492 0.0519 0.0512 0.0548 0.0547 0.0510
Table 6 Total energy consumption in the densification process of the industrial-scale drying machine condition. Material
Energy used in drying process (MJ/kg)
Energy used in shedding process (MJ/kg)
Energy used in briquetting process (MJ/kg)
Total energy used (MJ/kg)
Heating value (MJ/kg)
Energy used compare to gained energy (%)
Rice husk Sawdust Sugarcane bagasse Sugarcane leaf
2.25 2.25 2.25
– – 0.26
0.09–0.10 0.04–0.05 0.04–0.06
2.34–2.35 2.29–2.30 2.55–2.57
13.26–15.94 16.78–18.96 15.77–18.19
14.74–17.64 12.13–13.64 14.12–16.17
2.25
0.41
0.05–0.06
2.71–2.72
17.72–19.59
13.88–15.29
mass. The obtained results indicated that the mixture of glycerin and biomass was considered feasible to be further developed as an alternative fuel. Acknowledgements This research project was financially supported by the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission, through the Biofuel Cluster of Khon Kaen University. I would like to gratefully thank to Center for Alternative Energy Research and Development, Khon Kaen University, Thailand. References
Fig. 2. The comparisons of correlated HV and the actual HV in difference ratios of glycerin and biomass.
These values were then compared with the measured heating values (Table 3) and illustrated in Fig. 2. It could be observed that the measured heating values were within ±5% errors and correlated well with the calculated heating values. It could be seen that increasing amounts of glycerin led to the increase of the heating values and the optimum glycerin-biomass ratio found in this study was 30%. This value was also in a suitable range of the compressive strength of briquette fuel found in the previous study [14]. The obtained results indicated that the mixture of glycerin and biomass was considered feasible to be further developed as an alternative fuel. 4. Conclusions This research investigated the ratios of the energy consumption during densification process and the gained energy of the briquette fuels having different ratios of glycerin and biomass. The results showed that the energy consumptions were 1–3% of the energy gained for the domestic-scale solar drying condition, and 12–18% of the energy gained for the industrial-scale condition. In addition, the optimum ratio of glycerin mixed with biomass was 30% by
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