Research On Nitrogen Release During Co-pyrolysis Of Zhundong Coal And Corn Straw

Co-combustion is a crucial mean to improve the quality of waste biomass and low-rank coal,because it can not only integrate and utilize abundant biomass resources in China to alleviate the environmental pressures,but reduce the pollution and safety problems from unreasonable combustion of low-rank coal.The release of nitrogen in the process of rapid pyrolysis has a great influence on the final emission of nitrogen-containing pollutants.To ensure the clean and efficient further utilization of blended fuel,it is necessary to control the emission of pollutant related to N.However,the relative investigations are not comprehensive,and mainly concentrated on pyrolysis in an inert atmosphere.Therefore,to fully recognize the nitrogen emission mechanism,the emission of nitrogen-containing gases during pyrolysis of Zhundong coal,corn straw and a mixture of them in N2 atmosphere and oxidizing atmosphere were investigated in this study.At first,the horizontal tube furnace was used to analyze the rapid pyrolysis characteristics of Zhundong coal,straw,and their equal proportion mixtures in the nitrogen atmosphere with a pyrolysis temperature range of 300-900?.The results showed that when the pyrolysis temperature was 300? and 600?,the co-pyrolysis of coal and raw straw has mutual inhibition effect,which lead to a yield decrease of pyrolysis gas and tar,but promotion effects were found at other temperatures.The co-pyrolysis of coal and straw presented weak inhibition effects on the release of nitrogenous gases at all temperature except 500?.After that,the oxygen,carbon dioxide and nitrogen were used to prepare the oxidizing atmosphere,where the rapid pyrolysis experiments of Zhundong coal,straw and their equal proportion mixtures were carried out in.Results showed that the co-pyrolysis of coal and straw generally exhibited mutual inhibition effects in an oxidizing atmosphere.When the pyrolysis temperature was 400?,the co-pyrolysis of the oxidizing atmosphere with 5%O2 concentration showed promotion effects and reduced the yield of pyrolysis char.In general,the co-pyrolysis of coal and straw inhibited the release of nitrogen-containing gas.Among them,the inhibition effects on HCN were weak,but the co-pyrolysis promoted the precipitation of HCN at 400?.Furthermore,the characteristics of pyrolysis at a mixture of 1:1 of Zhundong coal and straw in nitrogen atmosphere and oxidizing atmosphere were compared.It was found that when the pyrolysis temperature was lower than 700?,the changes of atmosphere have no obvious effects on the co-pyrolysis.When the temperature was higher than 700?,the oxidizing atmosphere obviously promoted the co-pyrolysis process and reduced the yield of pyrolysis char.When the pyrolysis temperature was lower than 600?,the oxidizing atmosphere promoted the release of NH3,while reduced the production of HCN.The oxidizing atmosphere had strong inhibition effects on the release of NH3 and HCN when the pyrolysis temperature was above 600?,compared with the nitrogen atmosphere.