Study On Co-combustion Performance Of Rape Straw And Lignite

In recent years,many countries use biomass and coal co-combustion power generation to alleviate the shortage of fossil energy and environmental pollution,co-combustion technology has been concerned by the community.The co-combustion of biomass and coal is closely related to its inherent minerals and structure.Deepening the understanding of co-combustion of biomass and coal has important guiding significance for the improvement of co-combustion technology of lignite and biomass.In this paper,rape straw from Lianyungang,Jiangsu Province and Shengli lignite from Xilinguole,Inner Mongolia Autonomous Region were selected as research objects.Firstly,the combustion properties of the two materials were compared by thermogravimetric analysis,and their structures were characterized by industrial analysis,SEM-EDS,XRD,FT-IR and XPS;Then,the effects of blending ratio and blending method on the co-combustion performance and its synergistic effect were investigated,and the kinetic parameters were analyzed.At the same time,the effects of minerals on the co-combustion performance were investigated;Finally,the synergistic effect of the mixture of rape straw and lignite with different structure was analyzed.The results show that the blending ratio and blending method have a certain influence on the co-combustion performance of rape straw and lignite.The results show that the combustion weight loss temperature range of different proportion of rape straw and lignite is mainly in 200-600℃,and the combustion performance is better with the increase of rape straw proportion.In the low temperature region（200-350℃）,the synergistic effect of different proportion of rape straw and lignite is weak;In the high temperature region（350-500℃）,when the ratio of rape straw and lignite is 3:7,the synergistic effect of the mixture is the best.Compared with dry mixing method,wet mixing method can separate lignite and rape straw from their inherent minerals,resulting in better combustion performance.Kinetic analysis showed that the combustion activation energy of the mixture was lower than the theoretical activation energy of the two substances,which further indicated that there was a synergistic effect between rape straw and lignite in the co-combustion process.The minerals in rape straw and lignite have great influence on the co-combustion performance of the blends.The minerals in lignite have no synergistic effect on the combustion of volatile matter,but have obvious promotion and synergistic effect on the combustion of fixed carbon.The minerals in rape straw have a negative synergistic effect on the combustion of volatile matter in the mixture,and a significant promoting and synergistic effect on the combustion of fixed carbon in the mixture.After adding K⁺and Ca²⁺to the rape straw by impregnation method,it was found that K⁺could promote the combustion of rape straw volatile,and Ca²⁺could promote the combustion of rape straw fixed carbon better than K⁺,but Ca²⁺could inhibit the combustion of rape straw and coal,However,the synergistic effect of potassium ion on the co-combustion of rape straw and lignite mixture was greater.The structure of rape straw has great influence on the co-combustion performance and synergistic effect of straw and lignite.After pyrolysis at different temperatures,the structure of rape straw decomposed.FT-IR characterization showed that the aliphatic groups and oxygen-containing functional groups of pyrolysis rape straw were reduced,cellulose,hemicellulose and some lignin were decomposed,and the combustion performance became poor.By comparing the co-combustion performance of the mixture of rape straw and lignite and the mixture of rape straw and lignite after pyrolysis at different temperatures（300℃,400℃ and 500℃）,it can be seen that the mixture of untreated rape straw and lignite and the mixture of straw and coal after pyrolysis below 400℃ have good synergistic effect,and there is no obvious difference in the synergistic effect.The combustion synergistic effect of rape straw and lignite mixture decreased after 500℃ pyrolysis.