麦秸半焦低温催化气化实验研究

Catalytic Gasification of Wheat Straw Char at Low Temperature

以麦秸半焦为研究对象,比较麦秸半焦和酸洗麦秸半焦700℃下水蒸气气化实验,研究了麦秸灰分中碱金属含量、催化剂种类(K基、Ca基和Fe基)对气化过程的影响。实验结果表明,麦秸灰分中较高含量的碱金属K能够有效促进半焦气化的进行,使得在非催化条件下半焦的碳转化率达到63.4%,相比酸洗麦秸半焦提高了2.6倍。低温下碱金属K基催化剂对半焦气化的促进作用显著,在700℃和K/Al催化剂条件下H2产率和碳转化率分别达到118.60 mol/kg和98.5%,相较于Ca/Al、Fe/Al催化剂而言,H2产率分别提高了10.7%和20.5%,碳转化率提高了12.4%和31.0%;而Ca/Al及Fe/Al催化剂有利于水气变换反应的进行,可提高气化产物中H2体积分数,降低CO体积分数。综合考虑碳转化率、气体产率及气体组分含量等因素,在催化效果较好的K基催化剂中添加适量的Ca基催化剂有利于调节产气成分,从而进一步提纯获得富氢气体。

The steam gasification of wheat straw char（ WSC） and pickling wheat straw char（ PWSC） at 700 ℃ were carried out.The effects of alkali metal content in wheat straw（ WS） ash and catalyst species（ K-based,Ca-based and Fe-based） on the gasification process were investigated. The results show that high content of alkali metal potassium in wheat straw ash can effectively promote the gasification of char. This results in a carbon conversion efficiency of 63. 4 % without catalyst. This conversion rate is 2. 6 times higher than that of the pickling wheat straw char（ PWSC）. At low temperature,the K-based catalyst exhibits a positive effect on the gasification of char. The H2 yield is 118. 60 mol / kg with carbon conversion efficiency 98. 5 %under the condition of K / Al catalyst at 700 ℃. The H2 yield and carbon conversion efficiency increased by 10. 7 % and 12. 4 %comparaed with that with Ca / Al catalyst,respectively. The H2 yield and carbon conversion efficiency increased by 20. 5 % and31. 0 % compared with Fe / Al catalyst. Ca / Al and Fe / Al catalysts can promote the water gas shift reaction,which trends to elevate the H2 volume fraction,and reduce the CO volume fraction in the gasification products. By considering the carbon conversion,gas yield and gas composition volume fraction,the combination of certain Ca-based catalyst and K-based catalyst can regulate the gas composition. This generates a hydrogen rich gas with further purification.