生物质制甲醇系统CO2捕集过程的设计模拟及技术经济性分析

Simulation and techno-economic analysis of CO2 capture during biomass-to-methanol

通过ASPEN PLUS过程系统建模模拟,设计了生物质制甲醇系统中CO2的捕集工艺流程,并分析了其技术经济性能,研究了不同CO2捕集率的成本及其对生物质制甲醇能耗、水耗的影响。结果表明,捕集率为85%时生物质制甲醇系统CO2捕集封存较佳,单位捕集量的成本最低,有效能耗为453 MJ/t、水耗为193 kg/t、成本为135元/t,远低于直接从大气中捕集CO2。虽然这将使生物质制甲醇的生产成本增加154元/t,但当CO2减排补贴价格为40~50元/t时,则可抵消该部分成本增量。

China ranks first in methanol production around the world, occupying approximately 50% of the global production. But the dominant coal-to-methanol technology in China suffers from serious CO2 emission, which aggravates the global climate change. On the other hand, the development of biomass-to-methanol technology provides a method to reduce the CO2 emission of methanol production from sources, as the biomass feedstock is carbon neutral. And the application of CO2 capture and storage technology to biomass-tomethanol can further propose a low-cost way to capture, utilize and partially sequestrate CO2 from the atmosphere indirectly. In this work, the CO2 capture process in biomass-to-methanol production was conceptually designed and simulated by using ASPEN PLUS software. A Rectisol process integrated with a CO2 capture unit was provided. A techno-economic analysis was carried out to reveal the cost of different CO2 capture ratio and the effect on the biomass-to-methanol production. The results showed that moderately increased CO2 capture ratio could reduce the average cost per unit of CO2 capture, but excessive CO2 capture could also lead to a sharp increase in consumption and cost. 85% of CO2 capture was the most cost-effective choice for biomass-to-methanol. It indicated energy consumption of 453 MJ/t CO2, water consumption of 193 kg/t CO2, and cost of 135 CNY/t CO2, which were much lower than that of directly collecting CO2 from the atmosphere. The total production cost of methanol would also increase by 154 CNY/t, because of the CO2 capture and storage, and had a greater effect on the economic benefits of the biomass-to-methanol system. Therefore, policy-related subsidies were urgently needed. The cost of CO2 capture and storage in biomass-to-methanol could be offset when the subsidy of carbon abatement was around 40~50 CNY/t CO2. And once the subsidy was higher than 100 CNY/t CO2, the total production cost of biomass-to-methanol could be reduced to the same level as conventional coal-to-methanol.