Process Simulation And Optimization Of Methanol Distillation Unit

The methanol is a widely-adopted chemical product and a basic chemical raw material. However, by the existing synthesis process, there are lots of impurities in the crude methanol, which needs to be refined. Distillation is the main method of methanol purification. Therefore, the research on the process of methanol distillation is of great significance.Process simulation and optimization of 600 kt methanol annually distillation unit are carried out by using Aspen Plus simulation software in this Paper. The activity coefficient model of NRTL is selected in the pre-distillation column, the atmospheric column and the methanol recovery column. The combing model of NRTL-RK is selected in the pressurized column. On this basis, separation equipment model and simulation process of methanol distillation unit are established and the simulation results agree well with the actual value, conforming the reliability of the model.Based on the right simulation process of methanol distillation unit, the effect of process Parameters such as theoretical plates, reflux ratio, recovery ratio and feed stage on the unit is investigated by sensitivity analysis tool and the optimized process Parameters are obtained. Under the optimized process Parameters, the mass fraction and the recovery ratio of methanol can reach 99.9% and 99.3%, the heat duty of methanol distillation unit is reduced 11.1%.With existing problems in existing equipment are analyzed by sensitivity analysis tool,2 modified solutions are raised:(1) Recover waste heat to warm the feed into the column, (2) Add incondensable gas water washing device to recover methanol. Under the premise of meeting the separation requirements, new process saves 4.5% heat duty for pre-distillation column, increases recovery ratio by 0.2%.