Study On Co-gasification Of Soybean Straw And Yongcheng Coal

Gasification technology is an effective way to realize clean and efficient utilization of coal and biomass.However,the traditional single gasification method has many shortcomings.Co-gasification technology can better realize complementary advantages,and has great development potential in comprehensive utilization of energy resources,carbon and pollution reduction.In this paper,soybean straw and Yongcheng coal are used as experimental raw materials to carry out pyrolysis tests of soybean straw and Yongcheng coal.The non-isothermal CO₂ gasification and isothermal gasification of soybean straw coke and Yongcheng coal coke are studied,and the soybean straw ash and K₂CO₃\Na₂CO₃\Ca O are loaded into Yongcheng coal coke for co-gasification test.On the basis of the above research,The kinetics analysis of the co-gasification of soybean straw and Yongcheng coal was carried out.The research results are as follows:（1）Pyrolysis tests of soybean straw and Yongcheng coal were conducted by thermogravimetric analyzer at different heating rates and mixing ratios,and their synergies were analyzed.The results show that soybean straw and Yongcheng coal exhibit the same weight loss characteristics at different heating rates.At higher heating rates,the weight loss rate of pyrolysis decreases and the initial volatiles precipitation temperature increases.When the mixing ratio of soybean straw is 30%,50%and 70%,respectively,the corresponding initial volatiles precipitation temperature TS is 273℃,280℃and 296℃,indicating that T_Swill increase with the increase of biomass mixing ratio.By comparing the theoretical calculated value of the coke sample generated by the independent pyrolysis of soybean straw and Yongcheng coal with the experimental value of the coke sample obtained by the co-pyrolysis of soybean straw and Yongcheng coal,it is found that the synergistic effect of soybean straw and Yongcheng coal is not obvious during the co-pyrolysis process.（2）Under N₂ atmosphere,soybean straw and Yongcheng coal are prepared in accordance with 1:0,3:7,5:5,7:3,0:1,respectively.1.Mixing ratio and pyrolysis coke production temperatures at 600℃,750℃and 900℃,coke samples were prepared by two methods:coke production after mixing and coke production after mixing.Furthermore,non-isothermal CO₂ gasification and isothermal gasification experiments were conducted based on thermogravimetric analyzer.The results of kinetic analysis show that the mixing ratio has a significant effect on co-gasification in non-isothermal process.With the increase of soybean straw mixing ratio,the initial temperature of gasification decreases and the reactivity of gasification increases.The N-order reaction model was used to analyze the kinetics of non-isothermal co-gasification.The activation energy Ea decreased with the increase of soybean straw coke content,indicating that the addition of soybean straw coke can promote the gasification reaction.Under isothermal gasification,the gasification reactivity of soybean straw and Yongcheng coal mixed before coking is better than that of coke-mixed before coking.With the increase of coke temperature,the carbon conversion rate of co-gasification decreases during the same gasification time.（3）The gasification experiment of loaded soybean straw ash in Yongcheng coal coke was carried out by thermogravimetric analyzer,and the influence of gasification temperature and added soybean straw ash on the gasification reactivity of Yongcheng coal coke was investigated.Three gasification kinetics models were used for analysis.The results showed that:When the coal coke is loaded with 15%ash,it can be fully gasification at 900℃,while the coal coke without ash load needs a higher gasification temperature to achieve the same gasification effect,indicating that the loaded biomass ash can effectively reduce the gasification temperature while ensuring the gas rate.The shrinkage core model showed a good fit in describing the kinetics of gasification reaction.The activation energies Ea all decreased with the increase of biomass ash content,indicating that the gasification reactivity increased with the increase of biomass ash content.K₂CO₃ and Na₂CO₃ have high catalytic activity on coal coke,and the optimum value of K₂CO₃ and Na₂CO₃ exists in the loading range of 5%-7%（ionic loading,mass fraction）.The catalytic effect of two-component K₂CO₃/Na₂CO₃ on coal coke is better than that of K₂CO₃/Ca O and Na₂CO₃/Ca O.The catalytic effect of K₂CO₃/Na₂CO₃ on coal coke is better than that of single component.There are 39 figures,19 tables and 90 references in this paper.