The Study On Control Strategy Of Crude Unit Overhead System With Technological Anti-corrosion And Precise Injection

Atmospheric and vacuum distillation unit is the main refining equipment in the crude oil processing industry and it provides raw materials for the subsequent device.It plays a vital role in the oil refining processing industry.In recent years,the poor quality of crude oil result in the strong corrosion in low temperature overhead system of crude distillation unit.Heat exchanger leakage failure usually happens.However,the anti-corrosion means lack precision for the low temperature corrosion process and does not play a good role in corrosion controling.Therefore,how to control the process of anti-corrosion measures precisely and effectively to meet the goal of petrochemical enterprises to run long cycle.It is a urgent problem to be solved.The research object is 1# Atmospheric and vacuum distillation tower overhead system of the petrochemical in this paper.According to the control strategy of anti-corrosion and precise injection of atmospheric and vacuum distillation unit overhead system,this work focuses on the following aspects:1)This paper choose the design condition parameters,uses the idea of thermodynamic equilibrium and ion balance,sets up the process simulation model and heat transfer model of the overhead system by ASPEN and HTRI,obtains the dew point temperature and heat exchanger temperature distribution,determines the occurrence of the dew point in the second pipe from the inlet about 4.2 m distance.Through the analysis of the influence factors about dew point temperature,the water injection rate of the dew point corrosion area is controlled in the higher material grade;2)This paper selects the electrolyte model,according to the components and corrosive gas content in the overhead system,calculates the dew point area solution pH value,and analyzes the effect of ammonia injection and water injection on pH value,it is clear that the inorganic ammonia can not effectively improve the pH value of dew point region.The influence of the amount of ammonia injection and water injection on the pH value of the separation tank was analyzed under different condition,finally get the injection amount for controlling the pH value in the separation tank;3)The crystallization trend of ammonium chloride in the overhead system was analyzed by the crystallization curve of ammonium chloride salt to obtain the crystallization temperature,constructs the calculation model of crystallization temperature.At the same time,discuss the effect of water injection to crystallization temperature under different operating conditions,we can get the law of its deposition.4)Preliminary propose the precision filling system program,utilize ASPEN,HTRI and automatic control system to systematically integrate Lims system data with DCS data to calculate the dew point temperature,position,ammonium salt crystallization temperature and position.Through the automatic control system,adjusting the amount of ammonia injection,water injection to control the corrosion.