A Novel Coal-based Synthesis Gas-to-olefins Process Combined With Dry Reforming Of Methane And Steam Methane Reforming

Olefins are significant platform chemicals and the raw material for the synthesis of rubber, plastics and fiber. The soaring olefins demand driven by developing economy and the thinning oil reserves emphasize the importance of research on non-oil feedstocks for olefins production.What has been proposed in this thesis is a novel coal-based synthesis gas-to-olefins process combined with DRM(dry reforming of methane) and SMR(steam methane reforming), which is mainly implemented by high temperature F-T(Fischer-Tropsch) synthesis. Crude syngas from coal gasification is sent to F-T reactor to produce olefins and oil after purification process. DRM is introduced to consume CO2 and produce syngas, which is recycled back to the reactor and SMR is introduced to adjust H/C ratio appropriate for F-T synthesis.The proposed CSTO(coal-to-olefins via syngas) process has been further modeled and simulated with Aspen Plus software and the simulation results are compared with industrial data. The factors which affect the material consumption, energy consumption and pollutants emission have been investigated and analyzed and solutions are also presented. The capital investment and product cost have been studied. Comparisons between the CSTO process and the already existing OTO(oil-to-olefins), CTO(coal-to-olefins via methanol) processes in terms of energy consumption, material consumption, resource utilization efficiency, energy efficiency, pollutants emission, capital investment and product cost have also been conducted. It is concluded that:(1)The proposed CSTO process is capable of producing olefins with feedstock of coal consistently.(2)The proposed process has a total energy efficiency of 48.5%, 10.3% higher than that of CTO when the H2 conversion is 60%, the olefins selectivity is 27% and the ratio of CO2 input to DRM unit to CO2 emitted is 1.(3)The carbon efficiency of CSTO process can reach 60% when the input ratio of CH4 to coal is 0.26 and the input ratio of CH4 to DRM unit to SMR unit is 2.8.(4)The water consumption, electricity consumption and steam consumption of the CSTO process is 1.6, 1.54 and 1.26 times higher than that of the CTO process. But the energy efficiency of CSTO is 48.5%, 10.3% higher than that of CTO because CSTO requires much less coal input.(5)The total capital investment and production cost per ton of olefins of CSTO is 0.56 and 1.09 times to CTO. But the production cost per ton of olefins of CSTO will be less than CTO when carbon tax surpass 130 CNY per ton of CO2.