The Experimental Study Of Lignite Microwave Pyrolysis And Carbocoal Characteristics

With the rapid development of our country's economy and the increase of energy demand,the supply of high rank coal such as anthracite and bituminous coal is becoming tighter,energy shortage problem is increasingly prominent.,our country began to pay attention to the exploitation and utilization of lignite and other low rank coals.Its high moisture content and low calorific value,not only high transport costs,but also direct combustion thermal efficiency is low,so modified lignite mention quality is key to efficient and clean use of lignite.Comparing to traditional heating pyrolysis model,microwave heating shows several characteristics such as high efficiency,selectivity,easy control,energy saving and no pollution.In this paper,the microwave heating technology applied to lignite pyrolysis mass.This paper first through the aids of traditional coal quality test and modern analysis instruments to characterize and evaluate the lignite quality which included element,petrographic composition,mineral morphology and functionl groups.Then through the control of single factor experiment method to investigate the influence of pyrolysis product and distribution which included pyrolysis temperature,pyrolysis residence time,particle size of raw material and microwave power.Last research the composition and microstructure characteristics of solid product by industrial analyzer,elemental analyser,scanning electron microscope and polycrystalline X-ray diffraction analyzer,meanwhile analyze the gasification and combustion characteristics of semicoke by synchronizing thermal analyzer,to obtain gasification activity index,the index of combustion characteristics and combustion reaction kinetics parameters.Studied the influence of semicoke features produced in different pyrolysis temperature and pyrolysis residenc.e time.The results show that pyrolysis mass is one of the most effective utilization way for lignite because its high volatile and oxygen functional groups,low fixed carbon content and low ash and sulfur.In the range of experimental conditions,the pyrolysis temperature and pyrolysis residence time are the most influential factors among pyrolysis process parameters,and then the effects of microwave power,the influence of particle size of coal samples is little.Microwave pyrolysis reduces the lignite coal volatile content,improves the lignite coal rank.And with the increase of pyrolysis temperature and pyrolysis residence time,degree of the lignite pyrolysis,the more obvious this trend.The structure of semicoke tends to be in order,crystallization degree increase,tends to be the graphite structure.At the same time the ignition temperature and activation energy of semicoke increased,combustion characteristic index and reactivity reduced,which means the thermal stability of semieoke was improved,tends to be the characteristics of high rank coal.