Automation System Design Of Quality Upgrading In Diesel Hydrotreating Unit

Nowadays,the world is becoming stricter on environmental protection and petroleum product quality standards.Sulphur content has become one of the important indicators to measure the quality of oil,and is also the key to promoting the quality upgrade of gasoline and diesel.The national ? standard is planned to be implemented in 2020,and now some domestic refineries have successfully produced automotive diesel that meets the national ? standard.The upgrading of diesel hydrogenation quality studied in this paper is based on a domestic 3.5 million ton / year diesel hydrogenation refining device,which is dedicated to producing diesel products that meet the national ? standard;at the same time,reducing the diesel-gasoline ratio,increasing the production of ethylene and reforming raw materials.This article takes this modified device as an example to introduce the design of the automatic control system of a large diesel hydrorefining device.First,this article describes the overall process technology after the modification of the diesel hydrorefining device.It introduces the process from the three parts of reaction,distillation,and public part,and it compares the process options before and after the device modification to provide basic inputs for the design of automatic control system.Secondly,the main improved control scheme and safety interlock scheme of diesel hydrorefining device are discussed.The improved control scheme mainly includes liquid level and pressure control of the raw oil buffer tank after filtration;high-pressure reaction feed oil pump in / out flow control;high-pressure heat exchange system control;reaction system temperature and pressure control;content.In terms of safety interlock control,examples are given to introduce the emergency pressure relief interlock of the device accident;the low and low level interlock of the hot high-pressure separator;the high and high level interlock of the circulating hydrogen inlet separator tank;the interlock of the reaction feed heating furnace;,The high-pressure pump itself safety interlock protection,etc.Next,from the perspective of the enlargement of the device,the improvement of the instrument selection of the high temperature / high pressure reaction part of the diesel hydrorefining device was studied.The improvement plan mainly includes reactor temperature monitoring;hot high-pressure separator liquid level monitoring and control;reaction feed pump outlet flow monitoring;high-pressure emergency interlock on-off valve selection improvement.Finally,the design and commissioning of DCS,the decentralized control system for diesel hydrogenation quality upgrading and reforming devices,are introduced in detail.The original device's automatic control system was Yokogawa's CS3000 system.After many years of production and operation,there were shortcomings such as inaccurate control parameters,high failure rate,and low use efficiency.According to the design principles of the DCS system and the number of transformed I / O points,the upgraded CENTUM VP integrated production control system is selected.Starting from the structure and function of the DCS system,the overall design of the system is discussed,and the system hardware configuration and design are carried out from the aspects of on-site detection and transmission unit,final execution unit,logic control operation unit,and process interface unit.The system engineer configures,generates,downloads,debugs,and puts into operation the DCS system on the basis of automatic control scheme design.