The Study Of Pyrolysis Technology And Equipment For Low Rank Coal

Coal is the main energy of our country.The reserves of low-rank coal are huge and the volatile content is high.However,because of the large amount of water,low calorific value,poor thermal stability and poor strength,coal.is rarely used in an efficient and economical way;In addition,with the mechanization of coal mining improved,the lump coal yield decreased while the pulverized coal resources can not be effectively used.In order to realize the high-efficiency and clean utilization of low rank coal,coal-chemical and co-production technology whose source is pyrolysis is one of the main directions.Aiming at the shortcomings of low-rank coal distillation technology,our research group proposed a new low-rank coal low-temperature carbonization technology and equipment.The new low-rank coal low-temperature carbonization technology has many innovative advantages:The new technology makes retort and heating furnace together,and system energy loss and equipment investment are reduced;The retort heating system,composed by regenerative combustion and flue gas exchange technology and heat pipe bundle,while making the most of waste heat at the same time can guarantee the carbonization temperature uniformity of the furnace;The cold circulation gas are added at the bottom of retort and the carbocoal sensible heat are recycled.Circulating gas as a heat carrier,will not reduce the calorific value of the pyrolysis gas,while reducing the difficulty of subsequent processing.This article has carried on the comprehensive analysis discussion to the realization of the new craft process and the device structure design.Selecting Baori lignite as the analysis object and designing Carbonization furnace's daily processing coal is 300 tons.Through the access to information selected retort temperature of 550?,the design of the coke temperature is 150? and distillation gas outlet temperature is 200?.By thermal equilibrium analysis and calculation of the Carbonization furnace,the thermal efficiency of the new retort the gas fuel consumption and the amount of cold cycle gas was drawn.By means of programming,the air excess coefficient and flue gas exchange quantity in regenerative combustion process were optimized.Then the key structure of Carbonization furnace and thermal parameters were selected and calculated.Through the analysis of the heat transfer process in the retort,the mathematical models of the heat transfer process of coal drying,retorting and semi-coke cooling are established respectively.The convection heat transfer process between gas and material in the furnace,gas and heat exchange tube bundle were analyzed theoretically and it established a foundation for solving mathematical models.By combining the mathematical models of each process of coal carbonization in the furnace,a matrix equation is formed and iteratively calculated bycomputer programming to obtain the temperature distribution of the material layer and the gas.Then,according to the temperature distribution of the material layer and the gas,the height of the retort and the layout of the heat-exchange bundle were changed,and the iterative calculation was carried out again to make the outlet temperature of the final retort meet the design requirements and draw the furnace height and heat exchanger bundle arrangement After that,the influences of different tube wall temperature and gas flow of different cold cycles on the retorting process were analyzed,and the furnace height and the arrangement of the heat-exchange bundles corresponding to the porosity of different layers were analyzed.Aiming at the problem that the pulverized coal resources cannot be effectively utilized,the same dry distillation chamber structure was proposed for the pulverized coal pyrolysis,and the pyrolysis of pulverized coal in the dry distillation chamber was simulated by the FLUENT.