Kinetics Study And Entropy Generation Analysis On Biomass Pyrolysis And Gasification

This paper using thermal gravimetric analyzer for maize straw and pine sawdust carried out pyrolysis experiment and semi-coke CO₂ gasification experiment respectively,on the basis of common dynamics research combining the theory of absolute reaction rate and the non-equilibrium thermodynamic theory, the reaction mechanism of biomass pyrolysis gasification conducted in-depth research, the main conclusions as follows:?1?By using thermal gravimetric analysis of maize straw and pine sawdust for different particle sizes and different heating rate of pyrolysis experiment,the results show that:TG and DTG curves with the heating rate increases were moved to the high temperature zone;particle size the larger,the temperature gradient between the biomass samples the greater,the heat transfer limit,the more obvious.?2?On the basis of pyrolysis experiment, using the theory of absolute reaction rate, through the Coats-Redfern integral method of the main reaction zone reaction mechanism were studied, to calculate the activation enthalpy, and entropy of activation and the characteristic spot on the surface free energy of activation, and calculate its reaction rate constant, the results show that the activation entropy increases with the increase of heating rate, chemical reaction increasingly fierce; at the same time 1DG increased, achieve the same weightlessness rate is the required higher temperature, the reaction level increased.particle size is smaller,the less residual carbocoal quality.?3?Using n order reaction rate model to calculate the biomass semi-coke CO₂ gasification reaction activation energy E and refers to the former factor A and reaction series.Using the cloth doll partial pressure principle to calculate the relationship between CO generation and temperature.The results that the stability of CO increases with the increase of reaction temperature,when reaction temperature is as high as 1223 K,the generation amount of CO up to 98%.?4?under the condition of the thermal analysis experiment,by utilizing the principle of the non-equilibrium thermodynamic,according to local equilibrium assumption of semi-coke gasification process to establish CO₂ entropy production rate equation,while using Onsager reciprocal relationship to calculate the relationship between the reaction rate and phenomenological coefficient, and analysis three irreversible factors of the cause of entropy production rate, the results show that:heat transfer entropy production rate of entropy production rate > chemical reaction of entropy production rate > mass transfer of entropy production rate.