Operation And Running Cycle Optimization Of Atmospheric And Vacuum Distillation Based On Flowsheet Simulation

Crude oil is one of the most important energy, the demand of which will keep on growing for a long time, and its supply becomes degenerated in the future. In the face of high oil price, high acid crude oil is considered to be"opportunity oil"due to its lower price, and gets more attention from refineries to improve economic benefit. Atmospheric and vacuum distillation unit is the leading device of the refinery, which not only produces petroleum products but also provides raw materials for secondary processing device. The design and operation of distillation unit have directly effects on the product quality, product rate and economic benefit of refineries, so the simulation and optimization of this process is of great importance.Based on the property data of crude oil and process operation parameters from the distillation unit of Qingdao refinery, we used Aspen Plus to establish the atmospheric and vacuum distillation unit model and compared simulated values with actual ones in terms of the main process parameters, material balance, product quality, etc. to get the better optimization model. On this basis, we conducted the optimization of operation and running cycle.We found that there were certain overlap degrees between aviation kerosene and light diesel oil after surveying ASTM D86 curves of the main products of distillation unit, and the production of aviation kerosene and the separation accuracy could be increased. By analyzing the relationship between main process parameters and separation accuracy, we decided the stripping steam mass flow of the second sidestream, the pumparound mass flow of the second intermediate reflux and the top draw of atmospheric tower as the operating variables. Under the constraints of atmospheric products'guideposts, we got the optimized operating conditions by offline optimization, which improved the production of aviation kerosene and the yield of light products (including naphtha, aviation kerosene and diesel). The production of aviation kerosene increased 27% and the yield of light products increased 1.33%.Corrosion is one of the most important factors that influence the operation cycle because atmospheric and vacuum distillation unit is the most severe corrosion area in high-sulfur and high-acid oil processing. This paper investigated the main factors of high temperature corrosion of crude oil distillation unit and took temperature, sulfur content, acid value and the material of equipment as the analysis object to study their relationship with corrosion rate. We analyzed the corrosion of the high temperature zones of atmospheric and vacuum distillation unit by the method of combining process simulation technology and corrosion experiment and provided some proposals for corrosion protection.Finally, on the basis of the previous model of atmospheric and vacuum distillation unit and corrosion analysis method we carried out blending simulation analysis of Saudi heavy oil and Sudanese crude oil in the following mass ratio of 1:1, 1:3 and 1:5 respectively. We analyzed the simulated results in the aspect of material balance, product properties, gas-liquid load and corrosion distribution, and concluded that the option 3 was the feasible program. These analyses can provide the refinery with technical guidance and data support for blending process.