Migration Of Inorganic Cl In Simulated Components Of Combustible Solid Waste During Torrefaction

With the development of economy and the improvement of social living standards,the number of combustible solid wastes is increasing and the components are more complicated,which seriously hinders the clean and efficient disposal of combustible solid waste.Among them,the chlorine-containing substances in the combustible solid wastes are susceptible to secondary pollution during the heat treatment process,endangering human health.Therefore,it has become extremely important to seek ways to reduce the chlorine?Cl?content of combustible solid wastes to meet cleaning requirements.Because torrefaction has the function of improving the quality of biomass fuel and reducing the content of harmful elements,torrefaction is used as a means of pre-conditioning of combustible solid wastes,in order to reduce the Cl content and improve the fuel characteristics of torrefied products.It is an effective way to achieve clean and efficient disposal of combustible solid wastes.This article uses the simulated components of combustible solid waste as raw materials?NaCl-loaded Cellulose and Lignin?.Based on the existing Cl content determination method,a method for accurately measuring the Cl content of combustible solid waste is proposed.Torrefaction experiments were carried out on a combustible solid waste simulation component at four temperatures?250,300,350 and 400°C?using a tube furnace and TG-FTIR/MS,and explore the existence and migration of inorganic Cl in the simulated components of combustible solid waste.The main research contents and results are as follows:?1?The advantages and disadvantages of five methods for measuring Cl content were analyzed,and a method for measuring the Cl content of combustible solid waste was proposed.The results show that the oxygen bomb combustion method,eschka method,water extraction method and XRF method can not accurately measure the different types of Cl content of combustible solid wastes.The water extraction method combined with the oxygen bomb combustion method and the Eschka method can measure the inorganic Cl and organic Cl content in combustible solid wastes.However,the water extraction combined with the Eschka method is the most suitable and accurate detection of total Cl content of combustible solid wastes.?2?The existence form and migration of inorganic Cl in NaCl-loaded Cellulose during torrefaction were studied.The results show that the inorganic Cl in NaCl-loaded Cellulose is converted into organic chlorine during torrefaction and is present in the solid products,and the released Cl is mainly precipitated in the form of HCl/CH₃Cl and tar-Cl.After the addition of SiO₂,the formation of organic Cl was not found,the amount of HCl was nearly doubled,and the amount of CH₃Cl was the highest at 350°C.This may be because SiO₂ may inhibit the formation of carbon active sites in char,thus hindering the inorganic Cl to organic Cl conversion promotes the formation of HCl and CH₃Cl.?3?The existence form and migration of inorganic Cl in NaCl-loaded Lingin during torrefaction were studied.The results show that no organic Cl is formed in torrefied solid product regardless of whether SiO₂ is added to the NaCl-loaded lignin,and the reduced inorganic Cl is mainly released in the form of HCl/CH₃Cl.and no organic Cl is present in the torrefied solid products.However,SiO₂ change the structure distribution of solid products and inhibit the formation of carbon active sites,promoting the formation of relatively more functional groups such as methoxy groups,thereby increasing the formation of HCl and CH₃Cl at 350°C and 400°C,and increasing HCl.The amount is nearly doubled,but the total amount of CH₃Cl increase is small.