化工过程损率模块化模型研究

Modular based exergy loss analysis for chemical processes

针对化工过程系统物质变化和能量利用效率的建模和优化问题,提出损率模块化分析方法。根据过程特性,建立化工过程的宏结构,将过程系统分解为物料处理、化学反应、分离回收、废物处理、产品处理、能量处理和能量回收7个模块,并建立了各模块的平衡数学模型。以损率为目标,建立简化的系统分析模型。以天然气蒸汽转化制合成气过程为例,建立了其平衡数学模型,并以水碳比为变量建立损率线性模型,分析水碳比对系统损的影响。结果表明,在保持压力和温度不变的情况下,损率随着水碳比的增加而增加。模块化模型和研究结果具有较好的理论和实践应用价值。

Process efficiency modeling and optimizatioin of material conversion and energy utilization is an important topic for chemicalprocess design. The modular based exergy loss analysis method is proposed based on the thermodynamic efficiency in this work. According to process characteristics, macro-structure model for chemical process is presented systematically, which includes seven general modules. They are material processing, reactor, separator and recovery, waste treatment, product processing, energy processing, and energy recovery. The corresponding mathematic models for exergy balance are proposed. The simplified mathematic model of exergy loss is established based on exergy balances. The syngas production process by natural gas refomer is presented as a case study to illustrate the proposed method. The detailed models for exergy balances of the case study are presented. The effect of the water-carbon ratio on the exergy loss is discussed; the coresponding exergy loss model is proposed. The result shows that the water-carbon ratio is proportional to the exergy loss with the pressure and temperature being constant. The process sustainability could be improved by reducing water-carbon ratio. The proposed modular model and results have certain theoretical and practical application for the improvement of chemical process efficiency.