Effect of caprolactam waste liquid on coal water slurry gasification process
The mixed coal,caprolactam waste liquid,fresh water and additive sodium lignosulfonate were added to the coal mill in a certain proportion to obtain coal water slurry,which was then subjected to gasification reaction after pumping into a gasifier for coal water slurry water cooled wall gasification process.The properties of coal water slurry produced from waste liquid were in-vestigated,as was the impact of the waste liquid on the coal water slurry gasification process and gasification waste water.And the economic and environmental protection of coal water slurry production from waste liquid was also analyzed.The results showed that compared with fresh water to coal water slurry,the concentration of coal water slurry from completely waste liquid increased from 60.4%to 61.3%,the viscosity decreased from 750 mPa·s to 652 mPa·s,and the ash melting point decreased from 1 380℃to 1 270℃,still meeting the quality requirements for coal slurry entering the furnace;the synthesis gas volume of the complete waste liquid to coal water slurry gasification reaction increased from 265 570 Nm3/h to 280 212 Nm3/h,the effective gas volume fraction increased from 76.9%to 77.4%,and the hydrogen sulfide volume fraction increased from 0.14%to 0.19%,and there was no significant change in the gasification process parameters;the chemical oxygen demand(COD)and ammonia ni-trogen content of the wastewater discharged from the slag water treatment unit for the complete waste liquid to coal slurry gasifica-tion reaction increased,with COD rising from 324.2 mg/L to 515.5 mg/L and ammonia nitrogen content rising from 144.23 mg/L to 179.9 mg/L;and the use of caprolactam waste liquid to completely replace fresh water in the production of coal water slurry could save a large amount of fresh water,reduce the consumption of limestone,raw coal,etc.,the COD removal rate of caprolactam waste liquid in the system was 99.35%,and the content of benzene in the atmosphere near the coal mill was far less than the control index of 3 mg/kg.
caprolactam waste liquidcoal water slurryviscosityconcentrationgasification process
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