The Process Simulation And Heat Exchanger Network Optimization Of Atmosphere-Vacuum Distillation Process

Population overflow and energy crisis are two topics of today's world, and energy conservation is of the tendency. Chemical enterprises of petroleum are consumers of enormous energy, among which, with 20-30 percent of the total energy consumption, atmosphere-vacuum plant is of the utmost consumer. So, optimizing the heat exchanger network and maximizing the energy-saved are of great importance .Surrounding this subject, according to the background of a certain atmosphere-vacuum plant, such work has been done:1. Using pinch technology to diagnose the energy-used conditions of the whole system, the results showed that the pinch temperature is low, temperature difference is big and heat flow through the pinch. According to pinch technology, cold utility loads above pinch and hot utility loads below pinch will make double waste of the utility loads. At the same time, the temperature difference of the locale is bigger than of the original design, the waste of virtual energy is huge and the usage of energy is irrational. Therefore it is necessary to improve the matches of the streams neighboring the pinch and diminish the heat quantity flowing through the pinch in order to reduce the hot utility consumption of the system.2. The petroleum system is very complicated, which includes thousands of compounds, and its exact components are difficult to define. So the simulation software of ASPEN PLUS was applied to simulate the whole atmosphere-vacuum distillation process in order to make certain the petroleum components N streams flow rate etc. of the tow conditions of the locale , which established the foundation of the optimization of the locale heat exchanger network. Simultaneously, the basic data of the four conditions of 350 X 104 ton per year were simulated to settle the base of capacity-augment retrofit.3.Aiming at the problems found in energy diagnosis process, the HEXTRAN software of Simsci corporation was used to simulate and optimize the heat exchanger network of the locale, which obtained two optimal schemes; considering the need of retrofit, optimal heat exchanger networks of four conditions of 350 X 104 ton per year were produced.4.After diagnosing the energy-used of the heat exchanger networks of optimization, hot-cold curves and grand curves were obtained. The results indicates that pinch temperature is improved, utility quantity is much reduced, and final temperature of the preheated crude oil is increased, which proves the optimal heat exchanger networks are the most optimal ones tosome extent.