耦合纯氧气化的燃煤化学链燃烧分离CO2的基础研究

本项目研发一种耦合纯氧气化的燃煤化学链燃烧分离CO2新方法。该方法拟将燃料反应器由传统的单一反应器改进为由底部鼓泡床气化炉和上部提升管组成的两级反应器，其中气化炉内通入少量纯氧，和水蒸气一起充当气化剂，通过纯氧气化的放热实现燃料反应器热量自给，使其反应温度不再受空气反应器温度的制约，从而可以提高燃料反应器及整个系统的反应效率；同时，拟在系统后部增设燃烬室，通过在其中加入极少量纯氧，可以有效降低系统出口可燃气体浓度，从而提高能量转换效率并降低排放污染。另外，对于载氧体而言，此新方法通过燃料反应器的分级运行和燃烬室补燃，有效降低了载氧体的损耗以及对载氧体反应活性的要求，使得载氧体选材的重心可以放在廉价及化学稳定性上。本项目旨在通过理论、实验和数值模拟相结合的方式，探索该方法下燃煤化学链燃烧的流动特性、传热传质规律以及反应机理，验证此方法的可行性，为以后燃煤化学链燃烧相关技术的开发提供理论依据。

A new method of coal-fired chemical-looping combustion for CO2 separation, which couples the reaction of pure oxygen gasification, will be developed in this project. The fuel reactor type will be improved from a traditional single reactor to a two-stage reactor consisting of a bubbling fluidized bed gasifier at the bottom and a riser at the upper section. During the operation process, a small amount of pure oxygen will be injected into the gasifier together with the typical gasification agent (i.e. steam). The exothermic reaction of gasification between coal and pure oxygen can realize the self-support of heat for the whole fuel reactor. Thus, the reaction temperature in the fuel reactor will not be restricted by the temperature of the air reactor, which should be great beneficial for the reaction efficiency of the fuel reactor and even the whole system. In addition, a reburning chamber will be set at the outlet of the system, in which another small amount of pure oxygen will be injected to reburn the unreacted combustible gases from the fuel reactor. As a result, the energy conversion efficiency will be improved and the emission pollution of combustible gases will be effectively reduced. On the other hand, with the help of the graded operation of fuel reactor and the reburning of combustible gases in the reburning chamber, the operation loss and the reactivity requirement of oxygen carrier in the novel system will be effectively reduced. Hence, the selection of oxygen carrier material can focus on the aspects of the cheapness and the long-time chemical stability. With the methods of theory, experiments and numerical simulation, this project aims to investigate the flow characteristics, heat and mass transfer law and reaction mechanism of the novel system, and further verify the feasibility of this new method, which can provide a theoretical reference for the future development of coal-fired chemical-looping combustion technology.