Biomass Conv. Bioref. (2011) 1:99–103 DOI 10.1007/s13399-011-0011-5

ORIGINAL ARTICLE

Development of domestic biogas stove A. K. Kurchania & N. L. Panwar & Savita D. Pagar

Received: 30 March 2011 / Revised: 26 April 2011 / Accepted: 28 April 2011 / Published online: 10 May 2011 # Springer-Verlag 2011

Abstract The matured biogas production technology has led to the development of a number of biogas appliances for lighting, power generation, and cooking. The most promising among them is the biogas stove to meet the energy requirement for cooking application at domestic level. In this paper attempt has been made to design and develop a domestic biogas stove for meeting domestic cooking energy need. The performance of the stove was evaluated by using 2 m3 floating-type biogas plant. The thermal efficiency of developed stove was approximately 60.01%. Emission of carbon dioxide during combustion was measured and approximately 150–180 ppm. Keywords Biogas . Burner . Cooking . Domestic stove . Thermal efficiency

Nomenclature Ao Ap At Cdo Cdp CF d Po F Q

Injector orifice area (in square millimeter) Burner port area (in square millimeter) Throat area (in square millimeter) Discharge coefficient (the ratio of actual to theoretical discharge rate) Discharge coefficient of burner ports Friction-loss coefficient Relative density of gas Static gas pressure (in millibar) Flame-port diameter Gas flow rate (in cubic meter per hour)

A. K. Kurchania : N. L. Panwar (*) : S. D. Pagar Department of Renewable Energy Sources, College of Technology and Engineering, Maharana Pratap University of Agriculture and Technology, Udaipur 313 001, India e-mail: [email protected]

r s W

Ratio of entrained to jet fluid, i.e., primary air/gas ratio Specific gravity of gas Wobbe number

1 Introduction Energy is one of the basic inputs for all economic activities. Per capita energy consumption is one of the major determinants as well as indicator of economic development [1, 2]. Consumption of fossil fuel leads to global warming and is responsible for climatic change. Therefore, there is a need to develop and utilize renewable energy resources for a sustainable global energy strategy [3, 4]. In 2006, about 18% of global final energy consumption came from renewable sources, with 13% coming from traditional biomass [5]. Anaerobic digestion of biomass material directly converts it to a gas, termed as biogas, a mixture of mainly methane and carbon dioxide with small quantities of other gases such as hydrogen sulfide [6–8]. It is a colourless, blue burning gas that can be used for cooking, heating, and lighting [9]. Biogas is a clean, efficient, and renewable source of energy which has been popularized as a substitute for other fuels for the purpose of energy saving in rural areas [10]. It helps to reduce the rate of deforestation and environmental deterioration by providing biogas as a substitute for firewood and dung cakes to meet the energy demand of the rural population [11]. It also improves hygiene and health of the rural population, especially women, by elimination of smoke produced during cooking on firewood, by reduction in the hardships of collection of firewood, and by stimulation of better management of

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dung and night soil and to increase agricultural production by promoting optimal utilization of digested dung as organic fertilizer [12]. There are a number of biogas stoves which are converted from LPG stoves which are available in the market for domestic cooking applications. Primary air control is provided at the bottom of the stove and it becomes difficult to control and yields less efficiency. Keeping this in view, a biogas stove for domestic application to meet out cooking energy need was developed and tested to evaluate its performances.

2.1.1 Air requirement for complete combustion To release the potential heat contained in a fuel, it is necessary to burn it with a sufficient quantity of air. Insufficient air would lead to loss of potential heat by incomplete combustion, while an excess may give rise to an unduly large loss of sensible heat. It is important therefore to know the theoretical or stoichiometric air requirement or air–biogas ratio which is required for complete combustion of a fuel. The combustion reaction is as follows: CH4 þ 2O2 ! CO2 þ 2H2 O:

2 Material and method

From Avogadro's law, which states that equal volumes of gases under the same conditions of temperature and pressure contain the same number of molecules, it follows that

2.1 Design of domestic biogas stove To utilize the biogas for domestic cooking proposes, a stove was designed, developed, and fabricated at the Department of Renewable Energy Sources, Udaipur, India (27°42′ N, 75°33′ E). Various design parameters were taken into account for efficient design such as air requirement for complete combustion, injector orifice, primary aeration, flame port, and mixture tube and throat. The calculation of each required component done as procedure suggested by Fulford [13] is discussed in this section. The parameters of designed domestic biogas stove are presented in Table 1.

1 molecule CH4 þ 2 molecules O2 ! 1 molecule CO2 þ 2 molecules H2 O: Then, assuming ideal-gas behaviour 1 volume CH4 þ 2 volumes O2 ! 1 volume CO2 þ 2 volumes H2 O: Since air contains 20.95% oxygen (volume basis), the air requirement is given by oxygen requirement×100/20.95, i.e., each volume of oxygen is accompanied by 3.78 volumes of nitrogen to make up 4.78 volumes of air. Hence,

CH4 þ 2O2 þ 7:56 N2 ! CO2 þ 2 H2 O þ 7:56 N2 Or CH4 þ 9:56 air ! CO2 þ 2 H2 O þ 7:56 N2 CH4 þ 2O2 ! CO2 þ2 H2 O ! Stoichiometric O2 per unit volume of gas is 2 !Stoichiometric air per unit volume of gas is 9:56

rffiffiffiffiffiffi Po Q ¼ 12:55 Ao Cdo W s

2.1.2 Injector orifice The integrated form of the Bernoulli equation governs the discharge of gas through the injector orifice. The injector orifice area was calculated from Eq. (1). Table 1 Parameters of designed stove and burner S. no.

Component

Specification

1. 2. 3. 4. 6. 7. 8. 9. 10.

Length of the gas and air mixing tube Inner diameter of tube No. of air holes for primary aeration Diameter of air holes for primary aeration Number of ports Diameter of each port Distance between pan and burner Crown diameter Diameter of injector opening

850 mm 14 mm 4 4 mm 49 2.0 mm 35 mm 80 mm 2.0 mm

ð1Þ

2.1.3 Primary aeration The percentage of primary air required and the means by which this aeration is achieved exert an overriding influence on the design of atmospheric burners. For a circular type burner, throat area was estimated by Eq. (2). sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi At r¼ d 1 ð2Þ Ao Burners designed for biogas normally operates at 40–60% primary aeration (r = 2.0–2.5). 2.1.4 Flame port Small flame ports are normally employed as they minimize the tendency to light back. On the other hand, large

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Fig. 1 Line diagram of domestic biogas stove

numbers of small drilled ports are expensive to produce and may be prone to blockage. It was quoted a suitable compromise size of 2.5–3.1 mm for the optimum performance (Prigg). Easy crosslighting from port to port is necessary to prevent delayed ignition, and it has been shown that the crosslighting distance is approximately proportional to the flame-port diameter. The flame-port diameter was calculated by Eq. (3). sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi Ap F ð2 þ CF Þ ð3Þ ¼ ðr þ 1Þðr þ d Þ dCdp Ao 2.1.5 Mixture tube and throat It is generally desirable to use the minimum diameter, consistent with obtaining the desired primary aeration and port loading for designing the mixture tube and throat. The throat area was estimated from Eq. (4). pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi At ¼ Cdp ð2 þ CF Þ Ap

ð4Þ

performance could be obtained. Its burner head was replaced with the one having holes with more inclination (60o). At higher inclination the combustion products are at a high temperature, they rise vertically away from the flame. The distance between bottom of the pan and top of the burner was kept about 35 mm for proper combustion. The gas inlet channel was kept smooth to reduce resistance of gas and air. The size of air duct and spacing of air holes were such that complete combustion took place. The area of flame ports was kept properly with respect to the area of jet orifice. In traditional stoves, primary air control is provided at the bottom of the stove and it becomes difficult to adjust. Primary aeration control was provided outside of the developed stove to adjust the air conveniently for proper combustion. 2.3 Measurement techniques Biogas samples were collected by water displacement method and were analyzed by using gas chromatography

2.2 Stove description A domestic biogas stove was developed to provide a means of utilizing the biogas to cook for a minimum of six people, for a period of not less than 1 h each day. The burner allowed the sufficient biogas to cook the required amount of food, at a rate that did not exceed the required quantity of biogas. The burner was simple in design; it allowed easy installation and maintenance with little technical knowhow. Schematic diagram of stove is shown in Fig. 1. The body of existing biogas stove was used as illustrated in Fig. 2. Other modifications were provided so that better

Fig. 2 View of domestic biogas stove

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(Netal Chromatographs, Baroda, Gujarat, India) to find out the biogas constituent The chromatograph consisted of two columns Molecular sieve and Porapack N as stationary media and Argonas carrier gas. Chromatograph used thermal conductivity detectors. ‘INSURF’ Junkar's gas calorimeter (Instrumentation and Refrigeration of India, Chennai, India) was also used to determine the calorific value of biogas by combustion. In this procedure, a known volume of gas is used to steady heat a volume of flowing water; the rise in water temperature is measured. A dry-type gas flow meter (Model SI-2.5) was used to measure the volume flow rate of biogas flowing from the biogas plant. Its range was from 0.016 to 2.5 m3 h−1. Emission of CO was recorded by a gas analyzer (AFRISO EURO INDEX, Multilyzer Industries). A regulating valve was connected before the flow meter to control the flow rate of the gas.

3 Results and discussion 3.1 Experimental setup The developed domestic type biogas stove for thermal application was tested at Biogas Appliances Testing Laboratory situated at Department of Renewable Energy Sources, Udaipur, India (27°42′ N, 75°33′ E). The floating dome type biogas plant having 2 m3 capacity was used to supply biogas for testing purpose. The developed stove was tested as per the Bureau of Indian Standards (BIS; IS 8749: 2002). The BIS test procedure takes into account only the sensible heat stored in the water mass and pan in determining the useful heat.

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efficiency was 6% higher than that of reported by Chandra et al. [17]. Emission of carbon dioxide during combustion was measured and it was in range of 150–180 ppm.

4 Source of availability More details on the technology including training and dissemination of technology at village level can be provided by Department of Renewable Energy Sources, College of Technology and Engineering, MPUAT, Udaipur (Rajasthan) India.

5 Conclusion The growing demand for petroleum fuels and their limited availability in the world have necessitated the search for the replacement of these fuels. Biogas is a relatively clean gaseous fuel produced mainly from cattle dung and other biomass waste in anaerobic digestion. It is nontoxic, nonpoisonous gas. It can be used for direct combustion in cooking, lighting applications, or to power combustion engine for motive power or electricity generation; but due to above-mentioned properties, its use as a cooking fuel is more advantageous. An improved domestic biogas stove was developed having the biogas consumption rating of 375 l/h. Its thermal efficiency was found about 60.10%. There is huge potential for more efficient biogas technology in rural areas where generally cooking is done on inefficient stoves. It can increase the efficiency of household activities as well as help to empower man and children. In addition, by reducing greenhouse gas emission, the technology also helps to mitigate climate change [18].

3.2 Stove performance The stove was operated as per Bureau of Indian Standards norms, and it was observed that the flame travel was found complete when the vessel was placed on the burner. The flame was stable and at that time, wind velocity was about 5 m s−1. No undue or excessive noise was reported during the operation. When igniting one flame hole of a burner under the rated pressure, the time of flame transmission over all the holes took 2.5 s. The stove under test was connected to biogas supply pipe and the manometer indicated 100 mm of water column, when connected to atmosphere. The biogas consumption during the experiment was 375 l h−1, and the thermal efficiency was about 60.01%. Similar efficiency was reported by Mahin [14], and in China, in the Model-Beijing-4 of biogas stove, the thermal efficiency was about 59–62%, depending on the gas pressure [15]. The Indian study found it to vary between 40% and 65% [16]. The calculated thermal

References 1. Pagar Savita D (2008) Design, development and performance evaluation of biogas stoves. Unpublished M.E.(Ag) thesis, submitted to Maharana Pratap University of Agriculture and Technology, Udaipur 2. Rathore NS, Panwar NL, Kurchania AK (2008) Renewable energy: theory and practice. Himanshu Publication, Udaipur 3. Chang JYC, Leung D, Wu CZ, Yuan ZH (2003) A review of the energy production, consumption, and prospect of renewable energy in China. Renew Sustain Energ Rev 7:453–468 4. Panwar NL, Shrirame HY, Bamniya BR (2010) CO2 mitigation potential from biodiesel of castor seed oil in Indian context. Clean Techn Environ Policy 12:579–582 5. (2007) Global status report http://www.ren21.net/pdf/ RE2007_Global_Status_Report.pdf. Accessed 20 March 2009 6. E.U. (1999) Biomass conversion technology, EUR 18029 EN ISBN 92-828-5368-3 7. McKendry P (2002) Energy production from biomass (part 2): conversion technology. Bioresour Technol 83:47–54

Biomass Conv. Bioref. (2011) 1:99–103 8. Hiremath RB, Kumar B, Balachandra P, Ravindranath NH, Raghunandan BN (2009) Decentralized renewable energy: scope, relevance and applications in the Indian context. Energy for Sustainable Development 13:4–10 9. Itodo IN, Agyo GE, Yusuf P (2007) Performance evaluation of a biogas stove for cooking in Nigeria. J Energy South Afr 18(3):14– 18 10. Yua L, Yaoqiua K, Ningshenga H, Zhifenga W, Lianzhon X (2008) Popularizing household-scale biogas digesters for rural sustainable energy development and greenhouse gas mitigation. Renew Energ 33:2027–2035 11. Bhattacharya SC, Abdul Salam P, Sharma M (2005) Emissions from biomass energy use in some selected Asian countries. Energy 25 (2):169–188 12. Castro JFMD (1995) Biogas for household use: the case of Nepal. Energy for Sustainable Development 6:37–40

103 13. Fulford D (1996) Biogas stove design. A short course. “Renewable Energy and the Environment” at the University of Reading, UK for an Advanced Biomass Module. www.kingdombio.com/ BiogasBurner1.pdf. Accessed 12 Jan 2008 14. Mahin DB (1992) Biogas in developing countries. Bioenergy system report to USAID, Washington 15. Chan U Sam (1982) State of the art review on the integrated use of anaerobic processes in China. Internal report prepared for IRCWD 16. Dutt GS, Ravindranath NH (1993) Bioenergy: direct applications in cooking. In: Johansson TB (ed) Renewable energy: sources for fuels and electricity. Island Press, Washington 17. Chandra A, Tiwari GN, Srivastava VK, Yadav YP (1991) Performance evaluation of biogas burners. Energy Convers Manag 32:353–358 18. Katuwal H, Bohara AK (2009) Biogas: a promising renewable technology and its impact on rural households in Nepal. Renew Sustain Energ Rev 13(9):2668–2674