Research On Purification Mechanism And Technology Of Oil Tank Cleaning Waste Liquid

The underground oil tank of gas station is used as the storage container of product oil to ensure the quality of oil products.Oil tanks need to be cleaned regularly according to national regulations.In order to prevent the tank waste liquid from polluting the environment,it is necessary to separate and recycle the waste liquid through the purification system to reduce the waste of resources.However,at present,the waste liquid purification system of finished oil tank is mainly imported from abroad,and the cost is high,so it is mostly used in large oil fields.The common treatment methods are low efficiency and serious waste of resources in China.Therefore,a set of purification process is designed for the cleaning waste liquid of finished oil tank in small and medium-sized gas stations,which can improve the efficiency and save resources.Firstly,according to the physical parameters and characteristics of domestic gas station tank cleaning waste liquid,the treatment scale and technical indicators of small and mediumsized gas stations,the process flow of purified tank cleaning waste liquid is designed,which is mainly composed of four modules.In addition to the common separation of oil,water and sand,sulfide removal is also considered in this purification system.Based on the principle of coagulation sedimentation and inclined plate sedimentation tank,the pretreatment device of sulfide is studied and designed.Then the basket filter is selected as the equipment of the coarse filter module.The main function of the purification system is to effectively separate oil,water and sand from waste liquid.Therefore,the three-phase cyclone and disc centrifuge are used in series as the key technology of the primary and secondary separation modules of the purification system.For the oil water sand hydrocyclone,based on the design basis,the structural design and improvement are completed.And the range of parameters is determined.The 3D modeling is carried out by Solidworks.Then,the finite element model is established and simulated by FLUENT to analyze the characteristics of fluid trajectory,pressure and velocity.The influence of main structural parameters of hydrocyclone on separation performance is analyzed.In order to make the separation efficiency of the first stage separation module the orthogonal test is designed.The range analysis method is used to analyze the test results and optimize the structural parameters,so as to lay a good foundation for the next stage separation.The design of structure and size is also realized by the technical index and basic parameters of the secondary separation module.In addition,it is necessary to check the preset parameter processing capacity.The finite element model is established to analyze the flow field characteristics to verify the rationality of the flow field model in the drum.Fluent numerical analysis method is used to analyze the influence of different parameters on the separation performance of the disc centrifuge.Considering that the change of disc clearance and cone angle does not meet the principle of single variable,a comprehensive test of rotating speed and inlet speed is designed.The parameters are optimized to make the final separation efficiency meet the design requirements.