基于3kW塔式串行流化床差异燃料的化学链燃烧解析

化学链燃烧反应器具有广泛的燃料适应性，可同时兼顾气、液、固多类型燃料的运行。本文依托耦合内构件的3kW塔式串行流化床反应器，分别开展异丙醇、污泥以及煤炭的化学链燃烧实验，探究燃料物化属性对化学链燃烧过程与反应器运行的影响，揭示面向目标燃料的反应器针对性设计、载氧体性能选择与流化操作策略，助力形成指向性强、碳捕集效率高与操作灵活的化学链燃烧技术。面对碳化程度低、有机质含量高的固体燃料，焦炭气化速率已非强化重点，如污泥在3kW塔式反应器910℃与150s停留时间内，可实现大于99%的CO₂捕集效率，化学链燃烧反应器应侧重改善可燃气体转化与旋风分离器对轻质焦炭颗粒的捕捉。当采用异丙醇等高CH₄含量的燃料时，Fe基矿石载氧体的反应性能不足，3kW反应器的额外耗氧率高达10%～19%，其中未燃尽CH₄对额外耗氧率的贡献占比超80%。化学链燃烧反应器需依据热解反应气的物化特性，选择或掺混功能性载氧体，以针对性改善气固转化。在煤等高碳化燃料的化学链燃烧过程中，焦炭气化是反应的限制性步骤，简化循环结构的3kW塔式反应器停留时间不足，仅可...

Investigation of multi-fuel chemical looping combustion in a 3kW interconnected fluidized bed reactors

Chemical looping combustion (CLC), with wide fuel adaptability, can be operated with multiple fuels, including gas, liquid, and solid fuels. The CLC processes of isopropanol, sewage sludge, and coal were investigated in a 3kW tower interconnected fluidized bed reactors, in which several internal gas distributors were arranged along the fuel reactor to establish a multi-staged chambers structure. The experiments were intended to indicate the rules of reactor optimization design, oxygen carrier selection, and operational fluidization strategy as treating with differential fuels, which was also expected to promote the CLC development with the formation of strong pertinence, high carbon capture efficiency, and flexible fluidization. For the fuel with low carbonization and high organic matter content, the CLC process intensification should emphasize the improvement of gas-solid reaction and cyclone collection efficiency. The char gasification was no longer the critical factor on account that above 99% CO₂ capture efficiency was acquired in the 3kW reactor as adopting sewage sludge as fuel. The Fe-based oxygen carrier showed a limited reactivity with loading isopropanol, which would release abundant CH₄ in the pyrolysis process. The oxygen demand for isopropanol CLC was high as 10%—19%, in the unconverted CH₄ accounted for 80%. The CLC reactors should select or blend functional oxygen carriers according to the physicochemical characteristics of pyrolysis gases. The char gasification was the limited step in the coal CLC process, resulting in only 60% CO₂ capture efficiency obtained in the 3kW reactors, which had a simplified circulation structure resulting in a limited particle residence time. Coupling carbon stripper and adding an additional circulation loop of char particles were the critical factors to realizing high-efficiency chemical chain combustion. In addition, it was urgent to pay attention to the continuity and stability of solid fuel feeding. The intermittent feeding mode of the screw feeder could cause periodic and significant fluctuation of fuel reactor and feed leg pressure and destroy the stability and safety of cyclic operation.