The Study On Process Simulation And Reform Of The Rectisol Equipment Of A Plant

Methanol,which can be used for producing chemical products such as olefins and acetic acid,is a basic product of C1 chemistry.There should be a gas purification devise in coal to methanol process to absorb acid gas impurities in coal gas to prevent catalyst from being poisoned in subsequent synthesis reactions.Rectisol is a physical absorption method that uses methanol as an absorbent to absorb acid gases under low temperature and high pressure conditions.Rectisol is widely used in coal-to-methanol process.Aspen Plus is a simulation software which is used in the field of chemical engineering.It has a complete physical property database and powerful simulation and analysis functions.The task that the production of a Rectisol system in a methanol synthesis plant needs to be expanded by 40% is studied in this paper.The process is simulated by using Aspen Plus chemical process simulation software.The physical property method of PSRK is selected according to the properties of the process.Then,whole process is simulated and the results of the simulation are consistent with the original process,proving the correctness of the selected physical methods.In order to make the products after expansion meet the production standards,the process is analyzed and the transformation scheme is proposed as follows: A nitrogen stripping tower is added to strip the dissolved acid gas which is contained in the main wash methanol returning to the shift gas absorber.In the meantime,the temperature of main wash methanol is reduced and the absorption capacity of main wash methanol is increased.A dual-stream heat exchanger is added to recover the cold of the gas from the newly added nitrogen stripper.A utility heat exchanger is added to reduce the temperature of the methanol absorbent in the crude decarbonization section and increase the absorptive capacity of the methanol absorbent.After the transformation above,the product streams comply with factory standards and the goal of expanding production by 40% is achieved.The above reconstruction scheme is feasible and provides a reference for the application of the plant.