The Flow Corrosion Failure Analysis And Engineering Optimization Of Atmospheric Pressure Distillation Tower Overhead System

Atmospheric and vacuum distillation is the first process in the refining industry, shoulderingarduous tasks of providing raw materials for downstream devices such as hydrocracking、catalytic reforming and hydrocracking delicate for the long term. Since the first atmospheric andvacuum distillation device has established, it had been hindering by the flow corrosion failure ofatmospheric pressuredistillation tower overhead system from its long-cycle operation.In recentyears,along of the poor quality of crude oil getting more and more serious,the flow corrosionfailure of heat exchangeand air cooler of atmospheric pressure distillation tower overhead systembecoming so serious that be difficult to control.Therefore,it is the effective ways to explortheflow corrosion mechanismof atmospheric pressure distillation tower overhead system thatunder complex environment and put forward corresponding optimization technology based onthe prevention andfailure prediction analysis to improve running reliability of atmosphericpressuredistillation tower overhead system.Based on the atmospheric pressure distillation tower overhead system of ZH atmospheric andvacuum distillation devices as research object, this paper clears about the flow corrosion failuremechanism of atmospheric pressure distillation tower overhead system and realizes flowcorrosion prediction and engineering optimization by useing correlation analysis technology,ASPEN simulation calculation and combined of fluid dynamics calculation as the researchmethod.The mainly completed research content and related conclusions of this paper asfollows:1） The paper analyzes corrosion hazard sources of atmospheric pressure distillationtower overhead system are, clears about that HCl, NH3and H2S are the fundamental corrosionhazard sources which caused the corrosion failure of atmospheric pressure distillation toweroverhead system atmospheric pressure distillation tower overhead system,determines that theflow corrosion mechanism of atmospheric and vacuum process often system mainly includesdew point corrosion, ammonium salt crystallization corrosion under the deposit scale and multiphase flow erosion through the process of flow, heat transfer, phase change correlationanalysis.2） This paper chooses the typical operating conditions and process operatingparameters,sets up a process simulation theory model, obtaines the physical parameters andbalance of oil, gas, water with the temperature distribution law using ASPEN simulation;3）calculates dew point temperature and crystallization temperatur of ammonium salt (NH4Cl,NH4HS),determines that the main failure forms of heat exchanger of atmospheric pressuredistillation tower overhead system.are dew point corrosion of HCl and NH4Cl deposition;4)receives the temperature distribution of tube and shell side fluid and pipe wall by using HTRIheat transfer calculation, predicts failure area location to determine the heat exchanger tubebundle after import1.5m distance monitor combining with the dew point temperature andammonium salt crystallization temperature prediction.5) puts forward process optimizationinclude the proposed pipeline balance piping, water injection location adjustment and the topinjection of ammonia and so on according to the failure mechanism and failure location of heatexchanger,establishes a flow corrosion failure control system and the regulatory scheme ofatmospheric pressure distillation tower overhead system.The innovation points of this paper as follows: Directing at the specific process of ZHatmospheric pressure distillation tower overhead system,the paper uses the method of reversehindcasting in process modeling and get the oil, gas and water balance with the temperaturedistribution law by useing ASPEN simulation. The paper acquires the temperature distribution oftube wall by using HTRI modeling calculation.and predicts the failure district of the tube bundlebased on the predictions of dew point corrosion and ammonium salt crystal deposition and putsforward. corresponding prevention and control measures.