Ammonium Salt Crystal Deposition Characteristics And Corrosion Behavior In Hydrogenation Air-cooling System

Since entering the new century,with the growth of the world economy,the crisis of the energy intensified,the continuous depletion of oil resources,oil demand has risen year after year,the oil refining industry in chlorine,high nitrogen,high sulfur and other poor crude oil processing ratio continues to increase.Refining equipment due to flow corrosion caused by the failure of the accident occurred frequently,the people's lives and property safety and long-term stable operation of enterprises to bring a severe test.Which is caused by the crystallization of ammonium chloride corrosion failure,the failure mechanism is complex,influential factors changeable,difficult to effectively predict and control,has become a key factor in the sustainable development of refining equipment.Aimed at the hydrogenation air-cooling system,through the study of the hydrogenation process,the easy crystalline components source and crystallization characteristics of the ammonium chloride were analyzed.The multi-phase equilibrium system of the petrochemical process was constructed by Aspen plus software to realize the accurate simulation of the cooling and separation process of the reaction effluent And the equilibrium model of ammonium chloride was established,and the calculation model of crystallization temperature of ammonium chloride was established to clarify the main factors affecting the crystallization of ammonium chloride.According to the Eulerian-Lagrang method was used to establish the flow sedimentation model of ammonium chloride particles.The distribution law of multiphase flow in the air cooler tube bundle and the deposition rule of ammonium chloride particles were obtained by Fluent software simulation to form quantitative prediction method of ammonium chloride deposition.The corrosion rate caused by ammonium crystallization was studied.Based on the constant temperature and humidity test device,the corrosion environment under different temperature and humidity conditions was simulated.The corrosion rate of 10 # carbon steel,316 L steel and 15 CrMo steel in different temperature and humidity environment was studied by weightlessness method.The mechanism of moisture absorption and desorption of ammonium chloride was studied.The protective film of the corrosion products of the material was studied by means of SEM,EDS and clarified that the mechanism of ammonia chloride corrosion in hydrogenation air-cooling system.The innovation of the paper is as follow: the source of the easy crystalline components and the crystallization process of ammonium chloride was analysed by studying the process of hydrogenation and the reaction mechanism.The deposition characteristics of ammonium chloride particles with different particle size were calculated by Fluent software to construct a quantitative prediction method for the flow deposition of ammonium chloride.The relative critical humidity and corrosion mechanism of ammonium chloride at different temperatures were analyzed by under-deposit corrosion experiments and the moisture absorption characteristics of ammonium chloride were studied.The research results can provide the theoretical basis for the risk assessment and control optimization of ammonium chloride crystallization in the hydrogenation air-cooling system.