Abstract:

The molar ratio of H₂/CO required is around 2.1 for the methanol synthesis of the coal-to-methanol (CTM) process.However,the H₂ to CO ratio of the crude syngas is only about 0.7.It is necessary to convert part of CO and H₂O into H₂ and CO₂ by water gas shift reaction.While mixing of the shifted syngas and the unshifted syngas results in reduction of CO₂ concentration,this leads to the high energy consumption for CO₂ capture.A coal based methanol and power cogeneration process with low energy consumption for CO₂ capture is proposed.The CO of the crude syngas is partly converted into CO₂ and H₂,and the shifted syngas does not mix with the unshifted syngas.The CO₂ concentration in the shifted syngas is thus relatively high compared to conventional CTM process.The energy consumption for CO₂ capture is reduced as a result.The H₂ rich syngas after CO₂ capture is partly mixed with the unshifted syngas to adjust the composition of methanol feed gas.System analyses are made based on process modeling and simulation.The energy saving ratio of the proposed process reaches 16.5%,and energy consumption for CO₂ capture is reduced by 30.3%.

Key words: polygeneration, CO₂ capture, methanol, energy consumption

摘要：

传统的煤制甲醇过程所需合成气的氢碳比为2.1左右，而煤气化粗合成气氢碳比仅为0.7左右，因此需要将部分合成气进行变换来调节氢碳比。然而，变换气与未变换气混合后使得CO₂浓度降低，从而导致CO₂捕集能耗增加。提出了一种低能耗捕集CO₂煤基甲醇和电力联产过程。新联产过程中部分粗合成气首先经过变换，将CO转变为H₂和CO₂，CO₂浓度提高，在此时进行CO₂捕集可实现捕集能耗的降低。经CO₂捕集后，得到富H₂气体，富H₂气体分流后与另一部分煤气化粗合成气混合调节甲醇合成的氢碳比。对新的过程进行了建模、模拟与分析。结果表明相比传统的带CO₂捕集的煤制甲醇和IGCC发电过程，新的联产过程的能量节约率可达到16.5%，CO₂捕集能耗下降30.3%。

关键词: 联产, CO₂捕集, 甲醇, 能耗