Application Of Honeywell DCS Control System In Low Density Polyethylene Slurry Catalyst Device

After 3 times technical transformation including introducing supercondensation technology, the production capacity of low density polyethylene in Jilin Petrochemical Plant has been raised from 10 thousand tons per year to 27.4 thousand tons per year now. The catalyst residence time is also shortened after the production load increased greatly, resulting in higher catalyst ash content of polyethylene products, which leads to decrease in mechanical property, optical property and surface appearance. In recent years, most of the domestic similar catalyst powder devices have carried out the transformation of slurry catalyst, such that new device directly using catalyst slurry feeding technique.The paper originated from Jilin Petrochemical Plant technical transformation project. The main purpose was by adopting Honeywell DCS system to realize interlocking and logic control and stabilize the performance of the device, thus reducing material and energy consumption and achieving the improvement of the quality of products.Slurry catalyst device control scheme was based on Honeywell DCS distributed control system to realize configuration of controller, I/O card, safety grid, power supply arrangement, relay, FTA and cabinet design. The controller used the HPM23/24 number controller of the original Honeywell DCS system of the low density polyethylene plant, without any new controller, but designed the new card and the cabinet. Hardware design included logic and configuration design, complex circuit and configuration design, process parameters calculation configuration, and adjustment of control loop PID setting and so on.The implementation of this project has achieved remarkable results, depending on adjusting the parameters of each loop to control the parameter value of the product so that the product index is controlled accurately, and the device runs stably. Slurry catalyst has high activity, so that effectively reduce the cost of the catalyst, and improve the quality of products. After a year of design and construction, the equipment has run stably, which indicators are close to or equivalent to those of the domestic similar equipment, and has achieved good economic benefits.