Absorption Separating Process For Olefin Production By Oxidative Coupling Of Methane

Ethylene plays an important role in petroleum and chemical industry. About 75% products of petroleum and chemical industry are produced from ethylene. Oxidative Coupling of Methane (OCM) is the only way for manufacturing olefin from methane. It has a temping foreground in technology and economy. This paper proposes a novel separation process for ethylene production by OCM.Firstly, this paper designs an original separation process for ethylene production from OCM synthesis gas. Toluene is the absorbent for the original separation process. The results of the original separation process simulated by Aspen Plus software shows that reclaim ration of ethylene from synthesis gas is up to 99.93%, mass fraction of ethylene increased from 8.3% to 63.1%.Secondly, sensitivity analysis tool is used to related technical parameters of the original separation process. The effects of these parameters to reclaim ration of ethylene and energy consumption are studied in detail.Applied the Energy-flow Framework Diagram (EFD) to the original process, and bring forward a new process by some ameliorative measures. Add mid-chiller and mid-heater in new process to increase energy integration of system. At the same time, adjust unfit temperature change of some heaters. Comparing new process with original process, the consumption of chill energy and cooling water decreases by 19.9% and 73.3%, and stream export 5.6kW. The exergy loss reduces 44.7%.Thirdly, present a quasi-quantificational technologic value system. UNIFAC model as basic computing method is applied in the technologic value system. Under the condition of arranged reclaim ration of ethylene, exergy consumptions of utility facilities, absorbent quantity and absorbent cycle loss ration are used as appraising target.Toluene, cyclohexane and propane are chosen respectively as absorbent in the technology appraising system. Simulated results shows that all three absent arrive arranged reclaim ration of ethylene (95%). According to exergy consumptions of utility facilities, the sequence is propane > cyclohexane > toluene. In accordance with absorbent quantity and absorbent cycle loss ration, the sequence is toluene < cyclohexane < propane. While exergy consumptions of utility facilities when uses cyclohexane as absent is close to propane, and absorbent quantity and absorbent cycle loss ration is far lesser than propane. Therefore cyclohexane is an appropriate absorbent for separation process.