基于物质流-能量流分析的农林废弃物制备低碳烯烃系统综合评价

Light olefins such as ethylene and propylene are the important chemicals, which mainly obtained from catalytic cracking of naphtha. To decrease the dependence of crude oil, advanced technologies for bio-light olefin production have been developed in industry and academia, derived from biomass. However there is still lack of effective and comprehensive method for evaluating bio-light olefin production technologies. Taking a typical bio-light olefin production plant, using agricultural and forestry residues, as an example, an integrated evaluation approach will be establish in terms of the material and energy flows analysis in this application. Three types of technique routes will be studied, including gasification-direct olefin synthesis from syngas, gasification-methanol to olefin and pyrolysis-bio-oil catalytic cracking. The common conversion properties and individual advantage of different production route will be discussed and the interaction of feedstock, conversion efficiency and byproduct utilization will be investigated. The life cycle assessment, fuzzy recognition approach and grey relational model will be integrated to assess the efficiencies of carbon emission, resource and energy consumption of different bio-light olefin production routes. The effect of the main operation parameters on the change of material and energy flows and the above-mentioned efficiencies of the three production route will also be discussed. .A comprehensive evaluation with the consideration of index system of environmental impact, operation performance and energy recovery for bio-light olefin production form agricultural and forestry residues will be established. Combining with the factors of market and policy using scenario analysis, an all-around assessment model for industrial utilization of agricultural and forestry residues for bio-light olefin production will be achieved. Therefore, this study will be a beneficial reference for the evaluation of the conversion technology from low value-added agricultural and forestry wastes to useful chemicals.

乙烯、丙烯等低碳烯烃是重要能源化工原料，目前主要来源于石脑油蒸汽裂解，在降低依赖石油的背景下，本项目针对农林废弃物制备低碳烯烃路线多样化和系统综合评价缺乏的现状，以农林废弃物气化-合成气直接合成、气化-经甲醇间接合成、快速裂解-经生物油催化裂化制备生物低碳烯烃三种路线为对象，探讨各路线的物质和能量流向，分析不同制备系统的共性行为模式和独特优势，解析原料成分、转化系统工艺及效率、副产品利用等要素的交互作用影响。利用生命周期分析、模糊识别和灰色关联分析的系统工程分析方法，以碳减排效率、资源和能源效率为基础，考察不同生物低碳烯烃制备系统中运行参数对系统过程的影响，构建包括运行效果、环境影响、能量回收的农林废弃物制备低碳烯烃过程评价机制。结合市场和政策要素的情景分析，综合评价以低碳烯烃产品为导向的农林废弃物利用系统，为农林废弃物高值产业化利用提供理论和技术支撑。

本项目针对农林废弃物制备低碳烯烃路线多样化和系统综合评价缺乏的现状，以气化-经甲醇间接合成、气化-合成气费托直接合成、快速裂解-经生物油催化裂化三种制备低碳烯烃路线为对象，探讨各路线的物质和能量流向，利用热力学和生命周期等系统工程学方法，对比分析不同转化系统的效率、副产品利用和碳排放性能，开展农林废弃物制备低碳烯烃过程的综合评价。.对联合CO2捕集的生物质化学链气化系统进行了模拟和分析，探索燃料反应器温度、载氧体量，水蒸气量和CO2捕集剂CaO对产气系统的影响规律，为高氢碳比合成气制取工艺提供参考。.对上述三种热转化工艺制取低碳烯烃开展了流程设计，构建了相应的转化和公用工程系统模型，进行了转化单元和全流程模拟，实现了制取系统的蒸汽和电力自给。采用物质流和能量流平衡方法，考察了不同制取系统中原料碳转化和能量转化规律，在此基础上开展了操作单元、制取子系统和系统等不同层次的能量效率和㶲效率分析、优化和比较，探索了工艺㶲损失关键单元和改进措施。结合生物低碳烯烃生命周期过程，收集了不同阶段的污染物和资源能源消耗清单，对其环境影响和经济性进行了评价。结果发现，原料经气化、甲醇合成、甲醇制烯烃路线的能量和㶲效率及环境影响等性能较好，气化器、热解器、燃烧器等发生化学㶲变化的单元为系统能量和㶲损的主要环节，此外优化系统换热和能量回收，有利于加强系统内热效率，降低㶲损。使用含碳量高原料，提高烯烃收率也使得工艺系统综合性能提升。.本研究以农林废弃物热化学转化制备低碳烯烃工艺评价为目标，以物质流-能量流分析为基础，完善了热力学、生命周期等系统工程学在农林废弃物利用系统评价中的理论方法和优化生物低碳烯烃制取过程的调控手段，可为生物低碳烯烃工艺的推广和实施提供切实的理论支撑。项目执行期间共发表和接收研究论文10篇，其中SCI论文3篇，EI论文3篇，国际会议论文1篇。