采用环境与火用生命周期评价方法对褐煤直接燃烧发电系统和褐煤热解燃烧分级转化多联产系统的环境影响与能量转化进行了分析。结果表明,环境影响方面,每燃用1 t褐煤,多联产系统产生的环境影响与直接燃烧相比在温室效应、酸化、富营养化和光化学臭氧形成潜力方面分别降低61. 7%,62. 9%,38. 5%和20. 0%。原因主要是多联产系统由于热解气净化后使用燃气蒸汽联合循环发电技术,能量转化效率高,产生的直接排放少;同时除发电外,多联产系统联产了高附加值产品甲醇、燃料油、硫等,抵消了生产过程的环境排放。能量转化方面,直接燃烧与多联产系统的积累火用消耗效率分别为94. 4%和111. 9%,多联产系统的能量转化优于直接燃烧系统。多联产系统输出产物的积累火用总值高于投入原料与能量的积累火用消耗总值(效率高于100%),原因是多联产系统在常规生产电力的基础上联产了高附加值的产物。

Both environmental and exergetic life cycle assessment (LCA) of lignite circulating fluidized bed combus- tion (CFBC) system and lignite pyrolysis-based polygeneration system are compared in this study. The environmental LCA is used to quantify environmental burdens;while the exergetic LCA is applied to measure thermodynamic perform- ance. Results from the environmental LCA reveals that the impact categories of global warming potential,acidification potential,nutrient enrichment potential,and photochemical ozone formation potential caused by the polygeneration sys- tem are 61. 7% ,62. 9% ,38. 5% and 20. 0% lower than that caused by the CFBC system. The reasons are mainly at- tributed to the higher electricity generation efficiency,lower direct emission of the polygeneration system. Besides,the co-production of high added value products like methanol,fuel oil,and sulphur also offsets the potential impacts to pro- duce these materials. Regarding to the exergetic LCA results,the cumulative exergy consumption (CExC) efficiency of the CFBC system and the polygeneration system are 94. 4% and 111. 9% ,respectively. The CExC efficiency is even higher than 100% for the polygeneration system,which means more CExC are generated from the products compared to the total CExC consumed from the input energy and materials. This is mainly attributed to the cogeneration of electricity and high added value products,such as methanol (70. 37 kg / ton lignite),fuel oil (12. 3 kg / ton lignite),and sul- phur (6. 72 kg / ton lignite) from the polygeneration system.