Analysis And Treatment Of Ammonium Salt Scaling In Reaction System Of Diesel Hydrogenation Unit

As the environmental protection requirements of the petroleum and petrochemical industry become more and more stringent,upgrading the quality of gasoline and diesel oil is imminent.As the main technology for gasoline and diesel production,hydrogenation unit has rapidly developed into an indispensable production unit in the refinery process.However,since the feedstock oil of each hydrogenation unit usually contains sulfur,nitrogen and chlorine,the subsequent process produces H2S,NH3,HCl and other corrosive media.This kind of corrosive medium is easy to form ammonium salt crystals in the high-pressure heat exchanger and the high-low separation air cooler,which can block the tube bundle and cause corrosion under the scale,thereby causing safety accidents of hydrogenation equipment leakage.Therefore,analyzing and studying the salt-forming corrosion location,mechanism and hazards of the hydrogenation unit,and formulating corresponding anti-corrosion measures have become an important topic in the corrosion research of the oil refining industry.This article takes a diesel hydrogenation unit of a refinery and chemical enterprise as the research object,and analyzes the causes and treatment measures of its ammonium salt scaling.By collecting the operating data of the diesel hydrogenation unit,comprehensively analyzing its production process,raw material properties,reaction system operating temperature and pressure,as well as the structure and material of the pipeline and equipment,etc.,the corrosion flow chart of the reaction system of the hydrogenation unit was designed.Using the chemical mechanism of ammonium salt corrosion in the reaction system for reference,the ammonium salt scaling status of the analysis device was studied from two aspects of process water injection and equipment operating condition control.It is determined that the raw material chlorine content,the reaction water injection rate and the temperature control of the inlet and outlet of the heat exchanger are the key factors affecting the scaling of ammonium salt.Based on the production and operation parameters of the diesel hydrogenation unit and the analysis of laboratory data,the ammonium chloride salt temperature is calculated to be 202?through the calculation of the ammonium salt crystallization temperature.It is predicted that the hydrogen-mixed raw material and the reaction product heat exchanger E101B tube bundle will produce ammonium chloride Crystal deposits and verify the reliability and accuracy of the prediction based on the operating conditions of the field equipment.Then it analyzes the impact of ammonium salt scaling on the operation of the device.First,it brings corrosion hazards to the equipment.The heat exchanger tube bundle produces ammonium salt corrosion,which has the risk of corrosion and leakage;secondly,it brings risks to the process operation.The fouling and clogging causes a decrease in heat exchange efficiency and an increase in pressure difference,which indirectly causes overload operation of the heating furnace and increases the operation risk of the circulating hydrogen compressor.Through process water injection analysis and calculation,the minimum water injection volume of the device is obtained,and it is recommended to optimize the water injection quality.Then,according to the actual situation of the device,the frequency conversion pulse electromagnetic scale inhibition equipment was selected for online application.It was concluded that the electromagnetic scale inhibition technology played a certain role in preventing the ammonium salt crystallization of the hydrogenation unit,and it was calculated that the ammonium salt scaling rate was reduced by 10%.Finally,through the implementation of the shutdown water washing program,the E101B ammonium salt scaling problem was completely solved,an accident of equipment corrosion and leakage caused by ammonium salt scaling was avoided,and the safe and stable operation of the device was ensured.