常减压装置在停开减压单元工况下的换热网络优化案例分析

Case study on optimization of heat exchanger network for shutdown condition of atmospheric-vacuum distillation unit

对原油常减压装置在停开减压单元工况下的换热网络进行了研究并提出了优化改造方案。应用Aspen Plus软件对某石化企业5.0 Mt/a常减压蒸馏单元进行建模,使用Aspen Energy Analyzer软件对停开减压单元状态下的换热网络进行建模,通过使用夹点技术对现行换热网络进行夹点分析和用能诊断,发现现行换热网络存在较大节能潜力。在遵循夹点原则和确保合适传热温差的基础上,确定了现行换热网络的夹点位置和能量目标,消除了违背夹点规则的换热,并对换热流程进行改造,得到优化可行的换热网络。通过对改造后的换热网络进行了经济分析并提出了换热器改造方案。优化后的换热网络使原油预热终温提高了14.2℃,年节省公用工程总量12.8MW;改造总投资为167.05万元,投资回收期约3个月,年经济效益增加646.37万元。

The heat exchanger network for crude atmospheric-vacuum distillation unit at shutdown condition of vacuum distillation unit is studied and an optimal revamping scheme is proposed.An Aspen Plus model of an atmospheric-vacuum distillation unit with a capacity of 5.0 million tons a year is developed,and the heat exchanger network under the shutdown situation of vacuum distillation column is simulated by Aspen Energy Analyzer.The pinch point analysis and energy utilization study of the heat exchanger network with the pinch point technology has found that the existing heat exchanger network has a great energy saving potential.On the basis of pinch point principles and assurance of appropriate temperature difference for heat transfer,the existing pinch point location of heat exchanger network and energy objective are determined,the heat exchange that violate the pinch-point rule are eliminated,the heat exchange process is improved and a new optimized heat exchanger network is obtained.On the basis of economic analysis of revamped heat exchanger network,an optimized heat exchanger network is recommended.After the operation of optimized heat exchanger network,the end temperature of crude oil after preheating is raised by 14.2 ℃,and annual utility saving is 12.8 MW;The total revamping investment is 1.6705 million Yuan（RMB） and the payback period is 3 months.The annual economic benefit is increased by 6.4637 million RMB a year.