Abstract: There are two feed gas streams in the rectisol stage in a certain plant that plans to expand production.To achieve expansion in the rectisol stage,the actual working condition of this original rectisol process is simulated by using Aspen Plus on the basis of PSRK property method.Because the simulation values match well with the actual operation data,PSRK is determined as the optimal property method for rectisol simulation.Hence,a revamping scheme is proposed as follows:two additional heat exchangers are used to precool feed gas,a new nitrogen stripping tower is also added to strip the dissolved acid gas contained in the methanol in the absorbing tower and a new pump is added to transport stripped methanol into the absorbing tower.Therefore,both the temperature of methanol and the content of CO2 in the methanol are reduced,which leads to an obviously increasing absorption capacity of methanol.Meanwhile,the optimal parameters are determined by sensitivity analysis as follows:feed flow of N2 is 300 kmol·h-1,number of theoretical plates is 7 and split ratio is 0.020.After these innovations,various product streams conform to process requirements and the 20% expansion target is achieved.Finally,the operation flexibility analysis on revamped process shows that the maximum capacity can be expanded by 26%,providing a margin for actual expansion.
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