Evaluation of main parameters and efficiency of partial biomass gasification in fixed bed gasifier with inverse blowing
Recent years the attention of many researchers is aimed at the development of new technology for solid fuels gasification, including biomass, which is known as partial gasification, pyrolysis, carbonization, oxidative pyrolysis, autothermal oxidative pyrolysis, partial gasification with inverse blow...
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| Дата: | 2016 |
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| Автори: | , , , |
| Формат: | Стаття |
| Мова: | Ukrainian |
| Опубліковано: |
Institute of Renewable Energy National Academy of Sciences of Ukraine
2016
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| Теми: | |
| Онлайн доступ: | https://ve.org.ua/index.php/journal/article/view/126 |
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| Назва журналу: | Vidnovluvana energetika |
Репозитарії
Vidnovluvana energetika| Резюме: | Recent years the attention of many researchers is aimed at the development of new technology for solid fuels gasification, including biomass, which is known as partial gasification, pyrolysis, carbonization, oxidative pyrolysis, autothermal oxidative pyrolysis, partial gasification with inverse blowing and counter moving thermal wave. Technology products are coke residue (biochar) and flammable low-tar gas, whereas at classical completegasification the combustible gas is the only target product.Published data obtained at different regime conditions differ by the yield of gas and biochar, a composition of the gas, which complicate comparison the technology efficiency for fuels processing at different modes of operation. Objectively, this is because direct measurement of some variables (consumption of hot gas, resin content in gas, ultimate fuel, and products composition) are technically complex and expensive. Therefore, on the basis of the limited list of measured values, it is necessary to determine the main parameters of partial fuel gasification and estimate its efficiency. The appropriate procedure is not published yet.It is described method of main parameters calculation for partial gasification of biomass which is based on experimentally measured values of some variables and modified known method for complete gasification. It is based on material balances and thermal balance taking into account exothermic heat of biomass pyrolysis reaction.Initial data are the ultimate fuel composition, yields of biochar, resin, and condensate, the chemical composition of the generator gas. The chemical composition of gas was determined by means of gas chromatograph Agilent 6890 N. The main flammable components of gas at biomass partial gasification are hydrogen, carbon oxide, methane. In addition to methane hydrocarbons available in gas: ethane, ethylene, acetylene, propane, propylene and butane, and their total content by volume more than 30% of methane, and their contribution to the gas heat value is over 60% of methane input. Their presence increases the gas heating value up to 7.5 MJ / Nm3.Making a carbon balance equation the yield of dry gas per 1 kg of fuel can be calculated. Making hydrogen balance the moisture in a gas can be calculated, and from nitrogen balance volume of blowing air can be found. The correctness of all calculations can be checked making the mass balance of substances spent and received at partial fuel gasification.Thermal balance per 1 kg of fuel is made to check equality of the incoming energy with chemical energy of fuel and heat of fuel, air, and exothermal heat of biomass thermal decay to outcoming chemical energy and heat with biochar, resins, gas and moisture, which it contains, as well as heat loss into environment.Based on results of the heat balance the energy efficiency of partial gasification can be calculated as the ratio of the amount of potential (chemical) energy of gas and biochar, which were obtained from 1 kg of fuel to the lower heat value of the fuel.
Results of the main parameters and efficiency calculations for two processes of partial gasification of wood pellets and birch cubes are presented. The yield of biochar from pellets comprises 21%wt, and that from birch cubes is only 12.2%wt. With birch cubes more gas generated, and this gas has higher low heat value. This may indicate that for biochar production the process implemented at partial gasification of pellets is morefavorable, and for gas production – the process of partial gasification birch cubes. Despite this, for the examined processes the efficiency value is almost equal and makes about 90%. |
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