Recycling of Tail Gas in Fischer-Tropsch Bubble Column Slurry Reactor and its Impact on the Coal-to-Liquid Process

摘要

Coal-to-Liquid (CTL) process could be a strategic alternative to produce clean and environmentally friendly liquid hydrocarbons through Fischer-Tropsch (F-T) synthesis in countries with scanty oil resources and abundant coal reserves. In order to maximize the syngas conversion, it is a common practice to recycle the tail gas coming from the F-T reactor. In this study, a simulator based on a comprehensive computer model for F-T Slurry Bubble Column Reactor (SBCR) developed in our laboratory was used to predict the effects of tail gas recycling on the performance of a conceptual commercial-scale SBCR for syngas conversion into high-value liquid hydrocarbons. The simulator was integrated with ASPEN Plus to perform a complete simulation of an F-T SBCR with tail gas recycling as part of a CTL plant. The simulation results revealed that a significant increase in hydrocarbon products yields can be achieved by recycling the F-T SBCR tail gas. This increase was accompanied by a more modest increase in the amount of water produced. In addition, less liquid products were lost and the selectivities of the heavier hydrocarbons, such as waxes, appeared to increase. Also, all these effects were amplified by recycling larger amounts of the reactor tail gas.