流化床-气流床耦合反应器中煤气化特性

Coal gasification performance in fluidized bed-entrained flow integrated reactor

利用化工动力学软件CHEMKIN建立了流化床-气流床耦合反应器等效网络模型,在300mm反应器中的煤气化实验结果基础上,充分考虑耦合反应器不同区域物料间两相流动、传质传热,对耦合反应器各部分流体力学特征以及耦合反应器中不同区域的化学反应进行了分析。利用模型对飞灰的碳转化率、耦合反应器的碳转化率、耦合反应器内温分布及物料停留时间进行计算,结果表明,流化床耦合气流床反应器后,气流床可将出口飞灰碳转化64.1%,实现了耦合反应器对飞灰的再气化;耦合反应器煤气化系统的碳转化率由单独流化床的84.9%提高到92.2%。

The carbon conversion from the fluidized bed coal gasification is about 85%. The fluidized bedentrained flow integrated coal gasifier was built with the aim to reuse the carbon in fly ash. A reactor network model was established by using the software CHEMKIN to study the reactions occurring in the integrated gasifier, and to investigate carbon re-gasification in fly ash. Based on experimental results on a 300 mm （i. d. ） integrated gasifier, the raw materials inter-phase flow, mass and heat transfer in different zones and the hydrodynamic characteristics of the integrated coal gasifier were analyzed. This model is to simplify the unstable continuity process in the integrated gasifier into a combination of ideal reactors, attempting to avoid the non-convergence of the study on complex flow field with many reactions with the CFD model. This model could be significant in the accurate analysis of new reactor concepts with sufficient knowledge of the hydrodynamic characteristics of reactors. Through the model, the carbon conversion rate of fly ash in the integrated coal gasifier, temperature profile and residence time of materials were recorded and calculated respectively. It was concluded that carbon conversion rate of fly ash reached 64.1 % in the entrained flow, and that the carbon in fly ash with low reactivity was re-gasified. Accordingly, the carbon conversion in the whole gasification system increased from 84.9% in the fluidized bed reactor to 92.2 % in the integrated coal gasifier.