Study On Process Optimization And Energy Saving Of Methanol From Coke Oven Gas

According to the first-stage and the second-stage methanol production systems and the current situation of the ammonia production system technology of Hebei Xuyang Coking Co.,Ltd,aiming at process optimization,energy saving and efficiency improvement,the integrated cascade utilization of energy and the optimal hydrogen-carbon ratio of methanol synthesis were analyzed and researched.The purposes of energy conservation and emission reduction with the production equipments,environment improvement,increasing yield and efficiency were achieved.Based on energy conservation and yield increase,a technical change with the desorbed gas management for the third-stage ammonia synthesis device was made.Compared with its original process,serving as the fuel gas for the coke oven and the boiler consumption and releasing subsequently,it was improved and using as the fuel gas of the preheating furnaces for the coke oven gas of the first-stage and second-stage methanol synthesis devices.In addition,the technical process of the synthetic purge gas(about 5000Nm3/h)which conducted in the first-and second-stage methanol synthesis devices was also improved from using as the fuel gas of coke oven gas preheating furnaces to the feed gas for the third-stage synthetic ammonia.These two technology improvements lead to a higher hydrogen utilizable ratio,more ammonia output(the increase is about 13,800 tons/year)as well as a higher corporate benefit(the growth is about 27,6000,000 RMB per year).With related processes utilization,most of the conversion drum and the synthetic drum of the first-and second-stage methanol production and the steam generated from the medium-pressure boiler went into the low-pressure steam piping network after the depressurization treatment,causing a huge energy waste.In this study,the medium pressure steam in the five channels mentioned above was concentrated for electricity generation and thus using as a production electricity source.This technical improvement could lead to an enterprise benefit growth of about 6,624,000 RMB per year.Through the technique adjustment,the optimal hydrogen-carbon ratio of the methanol synthesis(2.10?2.13)was obtained.Additionally,the problem of power consumption increase,which caused by the content and density increase of the carbon monoxide and carbon dioxide in the circulation gas fed for the synthetic centrifugal compressor after the carbon supplement in the conversion process,was solved in this study and the purposes of energy conservation and cost reducing were achieved as well.