To promote agricultural waste utilization and low-carbon methanol production,a green hydrogen-assisted biomass-to-methanol (GH-BTM) process was proposed.A whole-process model integrating biomass gasification,green hydrogen supplementation,methanol synthesis and distillation,and organic Rankine cycle waste heat recovery was developed using Aspen Plus.The effects of steam-to-biomass ratio,gasification temperature,methanol synthesis temperature,and green hydrogen supplementation on system performance were investigated,and the proposed process was compared with coal-to-methanol (CTM) and green hydrogen-assisted coal-to-methanol (GH-CTM) processes.The results show that green hydrogen supplementation improves syngas composition and enhances methanol synthesis performance.The hydrogen efficiency,energy efficiency,and exergy efficiency of GH-BTM are 88.80%,81.79%,and 72.85%,respectively.The life-cycle greenhouse gas emission is 0.31 kg CO2/kg CH3OH,the methanol production cost is 231.50 USD/t,and the internal rate of return is 23.77%,indicating favorable low-carbon performance and economic feasibility,and providing a reference for agricultural waste utilization and green methanol production.
利用可再生电力电解水制得的绿氢与生物质气化过程耦合,可调节合成气氢碳比和化学计量数,改善甲醇合成原料气组成,从而提高甲醇合成性能并降低化石能源依赖[9-10]。特别是以农业废弃物为碳源协同绿氢制备绿色甲醇,不仅有助于缓解生物质露天焚烧造成的环境问题,也可实现可再生碳资源的高值化利用[11]。因此,本文中提出绿氢协同生物质制甲醇(green hydrogen-biomass to methanol,GH-BTM)工艺,耦合生物质气化、绿氢补充、甲醇合成精馏及有机朗肯循环余热回收过程,利用Aspen Plus建立工艺模型,考察气化温度、蒸气/生物质比、甲醇合成温度和氢气添加量对系统性能的影响,并从能量效率、㶲效率、生命周期碳排放和经济性等方面与煤制甲醇(CTM)和绿氢辅助煤制甲醇(GH-CTM)工艺进行对比,为绿色甲醇制备和农业废弃物资源化利用提供参考。
甲醇合成过程采用Lurgi Mega Methanol工艺思路进行模拟,包括合成与精制2个部分[4,15]。合成气与补充绿氢混合后,经压缩、换热进入甲醇合成反应器。本文中选用RPlug模块模拟甲醇合成过程,并采用LHHW动力学模型描述Cu/ZnO/Al2O3催化剂表面的反应行为[16-18]。甲醇合成主要涉及CO2加氢、逆水煤气变换和CO加氢反应:
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