The dividing-wall has attracted more and more interesting across the word due to its excellent performance in energy saving. It is usually used for ternary separations, which is an actual application of the Petlyuk configuration, consisting of a vice fractionator and a main distillation column divided by a vertical wall into two sections. The feed stream flows into pre-fractionator and three product streams are removed from main column. The lightest part of the feed stream is on the top of main column while the heaviest part is sent out from bottom of main fractionator, the left one is side stream. The top liquid is split between the pre-fractionator and main sides of the dividing-wall column, while at the bottom the vapor flow is split according to the pressure drop on both sides of the wall. In our study, the concept the light part, the heavy part and the middle part of the feed stream is broad. In the application of dividing-wall in separation process of coal-based light olefins, the light part is consist of hydrogen, methane, ethane and ethylene, the middle part is consist of propylene and propylene, while the heavy part is consisted of other components. A simulation dividing-wall column process is accomplished in the software Aspen Hysys, and the application of logic operation unit leads it easier to make sensitivity analysis because of the reduction of freedom degree. The sensitivity analysis includes the relationship between mole flowrate of middle stream and production quality, effect of vapor and liquid recycle to pre-fractionator on the components mole fraction of middle stream, the effect of middle stream mole flowrate on energy consumption, and the impact of feed stream temperature and reflex ratio. At last, a set of optimized operation parameters is obtained.

New application of dividing-wall columns for the separation of coal based light olefins

251st National Meeting (2016)

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