压力分布对脱蜡装置酮苯多效蒸发最小供热负荷的影响

应用流程模拟与夹点技术对酮苯脱蜡工艺中脱蜡油回收系统的三效蒸发回收溶剂的操作压力的组合方案进行对比，结果显示，三效蒸发中3个蒸发塔的低-中-高压力方案和低-高-中压力方案能量回收的最佳条件明显不同。采用低-中-高压力方案时，应有较高的三效塔压力，二效塔压力可在较宽的范围内变化，同时总溶剂蒸出率应较高，而一效塔与二效塔的蒸出率应较低；采用低-高-中压力方案时，应有较高的二效塔应力，但三效塔压力应较低，总蒸发率不应太高，蒸发塔蒸出率分布也应比较均衡。若仅从能量回收率考虑，低-中-高压力方案有一定的优势，但由于低-高-中压力方案蒸发塔的操作温度较低，可采用温位较低的加热介质，加热成本较低。

EFFECT OF PRESSURE DISTRIBUTION ON MINIMUM HEAT SUPPLY OF MULTI-EFFECT EVAPORATION SYSTEM OF MEK-TOLUENE DEWAXING UNIT

A series of case study were made to evaluate the effect of the pressure distribution among each evaporators of MEK toluene dewaxing unit on the minimum heat supply, which computed by pinch point technology. Two schemes, low medium high pressure distribution and low high medium pressure distribution, were compared. Operating at their own optimal conditions, the former had high total solvent evaporation rate and much lower solvent evaporation rates in the 1st and 2nd evaporators; and the latter had relatively lower total solvent evaporation rate and more even evaporation rate of each evaporator. From the energy recovery point of view, the former had certain superiority, however, the latter had lower heating cost for its lower operating temperature, which heat demand could be supplied by lower temperature medium.