What is the principle of biomass gasification?
As an alternative to fossil fuels, the key to biomass energy is to convert low-grade biomass with low energy density into high-grade energy. How to effectively convert biomass into clean and efficient high-grade energy is the main research topic in this field. Currently, biomass energy conversion technologies mainly include biomass gasification, liquefaction, solidification and direct combustion technologies. Biomass gasification technology is one of the important means.
Biomass gasification principle:
1.Biomass gasification refers to the process of obtaining product gas from biomass raw materials (fuel wood, sawdust, wheat straw, rice straw, etc.) by pressing and molding or by simple crushing and processing, and then sending it to the gasifier for gasification and cracking under less oxygen conditions to obtain a gas body and purification treatment.
2.Under certain thermodynamic conditions, the pyrolysis, oxidation, reduction and reforming of biomass polymers are carried out by the action of partial air (or oxygen) and water vapor, and the pyrolysis is accompanied by further thermal cracking or catalytic cracking of tar into small molecule hydrocarbons to obtain gases containing CO, H2 and CH4.
3.Since biomass consists of cellulose, hemicellulose, lignin, inert ash, etc., with high oxygen content and volatile fraction and strong activation of coke, it is more active and suitable for gasification compared with coal.
4.Biomass gasification mainly includes gasification reaction, catalytic conversion of syngas and gas separation and purification processes. The focus of gasification conversion is on the adjustment and control of gas components and yields. The gasification process requires a gasification medium (often air), and the gas calorific value is low, generally 4-6 MJ/m3; the pyrolysis process usually does not require a gasification agent, and the products are liquid, gas and carbon, and the gas calorific value is high, generally 10-15 MJ/m3. The gasification process is accompanied by the pyrolysis process, which is the first step of gasification.
5.The purpose of biomass gasification is to obtain clean product gas, so a catalyst is used to inhibit or eliminate the tar produced in the pyrolysis reaction.