加氢裂化装置高压换热流程火用损分析与改进

 以国内某加氢裂化装置为研究对象，在运用流程模拟软件PRO/II对加氢高压换热流程进行模拟计算的基础上，对其进行火用分析，借助能级-热量（ε-Q）图，找出换热过程瓶颈。分析结果表明，原有的换热流程循环氢与原料油的热量分配比例不合理，循环氢载热量达31.49 MW，占反应物总需热的61.3%，导致循环氢加热炉的出口温度高达442 ℃，与仅306℃的原料油混合造成混合火用损达1.304 MW。优化方案中通过调整高压换热网络物流换热次序，循环氢与原料油换热量分配的比例分别由原来的53.2%和46.8%调整至40.0%和60.0%，优化后的流程提高能量回收率，减少了加热炉负荷，传热火用损减少了0.061 MW，混合火用损则减少了1.229 MW。

EXERGY ANALYSIS AND OPTIMIZATION FOR THE HIGH-PRESSURE HEAT EXCHANGE NETWORK OF A HYDROCRACKING UNIT

Based on a domestic hydrocracking unit, the high-pressure heat exchange network is simulated by using the simulation software of PRO/II, an exergy analysis is then presented by means of energy-grade-heat load (ε-Q) diagram and the bottlenecks in the heat exchange process are found. The analysis results show that the proportion of heat duty between recycle hydrogen and feed oil is unreasonable, thus the temperature of the recycle hydrogen at the furnace outlet is as high as 442℃, when it meets the 306℃ feed oil, an exergy loss of mixing comes to 1.304 MW. By readjusting the heat exchange sequence, the proportion of heat exchange capacity between recycle hydrogen and feed oil is optimized from the original 53.2% and 46.8% to 40.0% and 60.0%, respectively. After optimization, the energy recovery rate is increased, the load of furnace is reduced and reductions of exergy loss are obtained, which is 0.061 MW and 1.229 MW for heat exchanging and mixing, respectively.