Study On Improving The Cycle Of Concentration Of Circulating Cooling Water Based On Mesh Filtration Combined With Pulsed Spark Discharge In Water

In view of the defects of existing circulating cooling water system in water treatment technology like the environmental pollution induced by chemical treatment and the lack of direct action mechanism in these physical treatment methods adopting magnetic field and high voltage electrostatic field,a new type of self-cleaning filter system,which combined electrohydraulic discharges and mesh filtration,has been developed to improve the concentration ratio of circulating cooling water.Metal mesh filter with 10?m aperture is used to filter the hardness particles in the new method,and the filter can be cleaned by the pulsed spark discharge shock wave in water.In the present thesis,experimental investigations on the feasibility and applicability of this method were conducted using the artificially hardened water and practical circulating cooling water,and the influence of structural parameters and operational parameters on the experimental results were also studied.The main conclusions are as follows:1)The method can effectively deal with the circulating cooling water with high concentration ratio.It can greatly enhance concentration rate and reduce fresh water abstractions,besides,less energy consumption will be needed and the operating cost is extremely low.Meanwhile,it can significantly save water and bring huge benefits in economy,environment and ecology.Therefore,it deserves further research.2)Compared with the negative streamer spark discharge,the experimental effect produced by the positive streamer spark discharge is more obvious,and the shock wave coverage area is larger.So the positive streamer spark discharge is utilized in this new method.3)In the current experimental conditions,it is better when the needle electrode tip projects insulation casing 1 mm and needle-plate electrode distance reaches 9 mm.4)The total flow and tangential flow are two important factors affecting the pressure drop across the metal mesh,which also determine the amount of circulating cooling water that can be processed per unit of time.5)Only set a certain frequency to spark discharge can realize the online cleaning of filter.When a high discharge frequency being set,it is possible to reduce the pressure to a greater extent in a shorter period of time,but high requirements of equipment have to be met,and the operating cost will raise as the energy consumption increases.Thus,the frequency of the discharge in dealing with the circulating cooling water should beselected accord to the actual situation.When same energy applied,small capacitance and high voltage is more advantageous to improve the effective utilization rate of energy in spark discharge.6)In the current experimental conditions,the test system can effectively treat the simulated cooling water with concentration of 600mg/L and below,but fail to deal with sodium carbonate solution with concentration of 800mg/L,and the decisive factor for effective process is the solution conductivity.So this method can handle the simulated cooling water with the maximum concentration between 600 ~ 800 mg/L,and effectively increase the cycle of concentration of circulating cooling water to 12.