Techological advances in drying for quality improvement of high-moisture,low-quality coal
Coal is the ballast and stabilizer for ensuring China's energy security.With the depletion of high-quality coal resources,the uti-lization of low-quality coal has gradually taken the lead.Low-rank coal reserves are large and have high moisture content,which reduces its subsequent utilization efficiency.Coal drying can effectively reduce coal moisture,improve coal quality,and promote the clean and effi-cient utilization of high water content low quality coal.The moisture in coal was summarized and classified according to the location and nature of the storage.The classification of the pore structure and oxygen-containing functional groups in coal and the influence of the dr-ying process on the physicochemical structure of coal were reviewed,and the influence of the physicochemical structure of coal on the re-moval and reabsorption of moisture was then analyzed.The results show that the moisture in small pores and the moisture bonded in the form of hydrogen bonding are more difficult to remove,and the reduction of pore volume and oxygen-containing functional groups after dr-ying can effectively inhibit the moisture reabsorption,and the ignition point of coal is affected by the type of coal and the moisture content,and the upper limit of the drying temperature should be reasonably controlled to prevent overheating and combustion of the coal during dr-ying.The current application status of evaporation drying and dehydration technology was summarized,including drum drying,low-tem-perature steam drying,fluidized bed drying,vibration mixed-flow drying,microwave drying and other drying methods,and different dr-ying methods were compared and evaluated,and the research direction of future drying technology was explored.The structure of the hot flue gas drying equipment is simple,the processing capacity is large,but the drying process needs to strictly control the oxygen content,and the safety is relatively low.Microwave drying has the advantages of selective heating and fast drying rate,but it may have thermal run-away in the late stage of drying,and it is mainly in the laboratory/pilot research stage at present.The drying technology using steam as the heat medium has high safety and no waste water and exhaust gas discharge,with low energy consumption and high safety features,and can be further researched on steam transient drying technology,to solve the safety and high efficiency dewatering and quality improvement of coal with wide grain size.
moisturelow-quality coaldrying and upgradingpore structureoxygen-containing functional groups
万方数据
维普
