Simulation And Optimization Of Coal-based Chemical Power Polygeneration

Chemical-power polygeneration can couple different functions systems while producting different products and avoiding the shortcomings of each subsystem effectively.It found that the coal-based methanol production process has some disadvantages,such as large power consumption and serious heat waste according to analysis,while the subcritical thermal power station has low thermal efficiency in the low load condition.At the same time,plasma coal gasification has the feature of large electricity consumption.In this case,different systems were simulated by Aspen Plus,then it found that internal loss in the plasma reactor was large,accounting for about 70%of the total loss according to the exergy analysis,and the loss in the plasma generator was 10%.The unreacted gas in the synthesis subsystem accounts for a large proportion,about 50%of the total output.This is the essential reason for the high conversion rate of the chemical system,however,the high conversion rate also causes large power consumption and heat waste,the former accounts for about13%of the total input,the latter is 19521MJ/h,accounting for 7%of the total output,the distillation system has the lowest exergy loss and the exergy efficiency is 92%.Before coupling the system,firstly,optimizing and debugging some key parameters of the chemical system.During the optimization of the parameters of the chemical system,it finds that in the same conditions,enhancing oxidizing property is positive to plasma coal gasification,which increases the carbon conversion.Increasing the amount of CO₂supplied increases the selectivity of CO,and increasing of gasification temperature is beneficial to the generation of CO.In the process of methanol synthesis,the influence of the pressure of synthetic tower 1 is large for methanol production,and the pressure of tower 1can be appropriately reduced and the pressure of tower 2 can be increased.The effect is obvious that the distillation column pressure to the product temperature,and it has little effect on the amount of product.The increasing of the number of feed stage has a effect on the temperature of the product.Then,proposing the polygeneration construction scheme based on exergy analysis,it include these points.The unreacted gas is connected to the primary air outlet of the boiler as boiler fuel;and the steam produced by the synthesis system is supplied to the plasma generator;the steam produced by the primary heat exchange process of the synthesis system is passed into the regenerative system to reduce pumping in low-pressure cylinders;hot water after heat exchanging to the distillation system.Finally,combining the parameter optimization results with the construction plan to couple systems.After the implementation of polygeneration,power stations can save 3.19t/h of coal,the extraction steam of low-pressure cylinders can be reduced 15.624t/h,and the low-pressure cylinders can product extra work1.254MW.The exergy of the synthesis system exhaust goes down to 0,the efficiency of the plasma generator was increased by 1.69%,and the loss was reduced by 1793.6886MJ/h.Distillation system saves hot water 15.64t/h.