稻壳与水蒸气分段热解气化流程模拟

Process Simulation for Rice Husk Staging Pyrolysis and Gasification With Steam

生物质分段热解气化工艺通过提升反应温度提高碳转化率、降低焦油含量。该工艺过程中利用部分生物质热解气化产气在气化炉外部的燃烧器进行燃烧产生高温烟气,为热解、气化过程提供热量。该文选取稻壳为原料,利用Aspen Plus软件,模拟稻壳与水蒸气分段热解气化工艺过程,该过程考虑了热量回收与利用以及产气的部分循环利用,通过流程模拟,分析了气化温度、水蒸气通入量对产气各组分的产量、碳转化率、产气低位热值的影响。结果表明：利用总产气量的15.4%~20.5%用于燃烧可实现分段热解气化工艺的热量自给。随着气化温度的升高,产气中H2和CO含量增加,碳转化率升高,产气低位热值在气化温度为700℃时最低,随后逐渐升高；水蒸气的通入量增加会提高H2和CO2的产量,使碳转化率升高,产气低位热值降低；在气化温度为800~1000℃内,w（H2O）/w（B） 〉0.15（水蒸气与生物质质量比）时,CO的产量随水蒸气的通入量增加而减少,碳转化率接近100%。

Biomass staging pyrolysis and gasification process can increase carbon conversion rate and reduce tar content by rising up temperature. This process uses part of the product gas for combustion in an external burner to generate high temperature anaerobic flue gas and provide heat for pyrolysis and gasification. This paper selected rice husk as the gasification material, and used Aspen Plus software to simulate the process of rice husk staging pyrolysis and gasification with steam. Heat recovery and utilization, and the recycling of part of the product gas were considered in the simulation model. The influence of the gasification temperature and the steam-to-biomass ratio on product gas component yield,the carbon conversion rate and low heat value of product gas were analyzed by simulation. Results show that： Heat self-sufficient of the staging pyrolysis and gasification process can be achieved by using 15.4%-20.5% of the total product gas for combustion. The amount of H2 and CO in product gas and the carbon conversion rate increase with gasification temperature. Low heat value of the product gas reaches the minimum when the gasification temperature is 700℃, followed by gradually increase. Increasing the amount of steam intake will increase the amount of H2 and CO2 as well as the carbon conversion rate, but reduce the low heat value of the product gas. When gasification temperature ranges from 800℃ to 1000℃, and w（H2O）/w（B）〉0.15（mass ratio of steam and biomass）, the amount of CO decreases as the steam intake increases, meanwhile the carbon conversion rate is close to 100%.