CaSO_4氧载体与CO反应中Boudouard反应的热力学分析及其抑制研究

Thermodynamic analysis and suppress research on the Boudouard reaction in the reaction of CaSO_4 oxygen carrier with CO

在反应温度500～1200℃、CO浓度0.5%～99.0%、CO2浓度0～70%和SO2浓度0～10%条件下，利用化学平衡常数，对化学链燃烧 CaSO4与CO反应过程中Boudouard反应的可行性展开热力学研究，获得了抑制Boudouard反应及积碳生成的方法。由于CaSO4竞争还原反应和Boudouard反应平衡常数的表达形式不同，通过比较各个反应的CO平衡转化率以判断各个反应进行程度的高低。在化学链燃烧燃料反应器适宜温度范围（850～1050℃），CO 浓度越高，Boudouard 反应越容易进行，SO2浓度对 Boudouard 反应进行的程度没有影响。而提高反应温度和反应气中CO2浓度，则有利于抑制Boudouard反应的进行。当气体反应物中CO2浓度超过3.7%，即使CO浓度达到95.0%，Boudouard反应不能进行。

For the application of CaSO4 oxygen carrier in chemical looping combustion （CLC）,the thermodynamic of Boudouard reaction during the process of CaSO4 reduction with CO were investigated at 500-1200℃,at different CO concentrations （0.5%-99.0%）,CO2 concentrations （0-70%） and SO2 concentrations （0-10%）. And the control method of the Boudouard reaction for less carbon deposition on oxygen carrier was discussed. The expression forms of the equilibrium constants of CaSO4 reductions and Boudouard reaction differed,and therefore,direct comparisons on the extents of the chemical reactions cannot be done. The extents of the chemical reactions of the competitive reductions of CaSO4 and the side reaction of the Boudouard reaction were analyzed based on the CO equilibrium conversions. For the suitable temperature of fuel reactor in CLC （850-1050℃）,higher CO concentrations favor the Boudouard reaction,while the SO2 concentrations had no effects on the extent of the Boudouard reaction. The Boudouard reaction was suppressed at higher reaction temperatures and higher CO2 concentrations. Furthermore,when the CO concentration was at 95%and the CO2 concentration in the gas reactant was above 3.7%,the Boudouard reaction was not able to be initiated.