化学链技术及其在化石能源转化与二氧化碳捕集领域的应用

化学链是指将某一特定的化学反应通过化学介质的作用分多步反应完成的过程．这一概念早在20世纪初就曾被用于以水蒸气与铁反应制备氢气，并于20世纪中期被提出用于二氧化碳的商业化生产．然而，时至今日，尚无商业化的化学链工艺用于化石燃料的转化．在近年来全球气候变暖及能源危机的急迫形势下，化学链循环过程由于其具有可以将碳基燃料直接转化为可供封存的二氧化碳的独特能力而格外受到关注，人们因而加大了对化学链工艺的研究开发力度．现代化学链工艺逐步克服了早期工艺的缺点，并不断尝试开发以煤或者其他固体燃料作为直接进料的新工艺．现有的各种小试及中试装置操作结果及系统模拟分析表明，化学链循环工艺可以有效地降低二氧化碳分离能耗并提高化石能源转化效率，极具商业化潜力．本文主要介绍目前世界范围内现行的使用化石燃料作为原料的化学链循环工艺，重点总结对比了化学链燃烧和化学链气化两个过程的发展现状，并对化学链循环工艺工业化进程中的机遇和挑战进行了简要的讨论．

Chemical looping technology and its applications in fossil fuel conversion and CO2 capture

Chemical looping is a reaction scheme to decompose one reaction into multiple subreactions via chemical intermediates. The concept of chemical looping has been applied to the generation of hydrogen through the steam iron reaction, as well as the production of carbon dioxide since the 20th Century. However, there are currently no chemical looping processes in commercial operation. Under the circumstances of growing global warming and energy crisis, chemical looping processes have attracted extensive interests for the unique ability to convert carbonaceous fuel to energy or chemicals with affordable CO2 control. Recent developments in chemical looping technology have overcome some of the earlier shortcomings. New research on direct conversion of solid feedstock, such as coal has also been conducted. Through the current sub-pilot/pilot scale tests and process analysis, it has been demonstrated that chemical looping process can effectively reduce the energy cost for CO2 separation with enhanced energy efficiency. This paper presents the status of existing research activities on chemical looping development for fossil fuel conversion, with emphasis on large scale demonstration of chemical looping combustion （CLC） and chemical looping gasification （CLG）. The opportunities as well as the challenges on the way to commercialize chemical looping processes have also been briefly discussed.