Design Of Ultrasonic Auto Back Washing Filter And Study Of Filtration Mechanism

The production of petroleum industry is especially important with today's energy crisis. Massive waste water is produced in the exploitation and processing of the petroleum, and this kind of water is rich in organic pollutants, which are really hard to degrade. If the waste water is discharged into nature before treatment, it will bring enormous destruction to our environment. Therefore, it is needed to filter solid particles and oil off from waste water, after the treatment the waste water can meet the discharge standard and can be reused in petroleum industry. Particle size of impurity and suspended matter is very small, and normal filtering method can not work effectively. Old type filters have many shortages such as incompleteness of pollution discharge, blocking of filter material by impurity, low cleaning efficiency of filter core and so on. Replacing filter core frequently not only influents the filtration efficiency but also leads to waste of material and increasing of cost. A efficient filter which has high filtration precision and good cleaning result is urgently needed. Aiming at this engineering requirement, a new ultrasonic auto back washing filter which posses reasonable structure and high filtration precision is designed in this paper.Main work of this paper includes proper design of the filter, control system design, analysis of filtration mechanism, dynamic analysis of flow field and structural optimization of the filter. In the process of proper design, by using of ultrasonic back washing technology, solid particles on the filtration material is knocked off and is discharged by the slag discharge system, which ensures that every filter elements is cleaned thoroughly and has performance as initial. Electric control system uses the control of PLC. Differential pressure controller is applied to monitor the pressure difference between clear water and dirty water. When the pressure difference reaches to the set value, differential pressure controller output signal and the back washing system is started and stopped by PLC or operating the control cabinet. Therefore, auto back washing function is realized. The filtration mechanism of ultrasonic auto back washing is analyzed based on the darcy equation. Then the dynamic characteristics of the filter is simulated and analyzed by using of hydromechanical software FLUENT, according to the result, improvement measures is put forward from two aspects of boundary condition and structure, and the filtration efficiency and stability are improved significantly.