Slurry Pump Cavitation Mechanism And Prevention Measures In FGD System

Slurry pump is the key equipment of flue gas desulphurization system in thermal power plant. During the operation, slurry pump suffers cavitation, chemical corrosion and mechanical abrasion. The instantaneous high pressure caused by cavitation is the main reason of structural damage of slurry pump. In this paper, non-spherical bubble collapsing process near a rigid boundary is simulated in order to investigate the problem of slurry pump cavitation and seek prevention measures. Because of the complexity of the slurry composition, water is chosen as a substitute of slurry. Optimized bubble collapsing model by consideration of real viscosity of vapor changing with temperature and pressure. The variation of parameters of bubble collapsing process under different liquid flied pressure are obtained and analysised. Vapor-air bubble collapsing process is also simulated and analysised.Simulation results suggest: non-spherical bubble collapsing dynamic processes of the vapor bubble with real viscosity and the vapor bubble with constent viscosity are similar when liquid field pressure changes from 0.1 to 0.6MPa, but the vapor bubbles with real viscosity has better shape of symmetry under different liquid field pressure; micro jet velocity of vapor bubble with real viscosity is lower than the vapor bubble with constent viscosity under different liquid field pressure, while the results of the maximum pressure of two kinds of bubbles are reversed; the effect of shock wave of micro jet against the rigid boudary is less than the maximum pressure of vapor collapsing; the relationship between micro jet and air content of vapor-air bubble is not obvious; the tendency of the maximum pressure of vapor-air bubble collapsing changes along with air content is similar to para-curve and the peak value is about 2100 MPa when air content is 0.5.Based on the simulation results, three methods to control slurry pump cavitation problem are put forward: to control the flux of air flow, increase the air dissolving capacity of slurry and optimize liquid field pressure. The the flux of air should be control based on the maximum flow rate and the load condition of the slurry pump. The increasing of air dissolving capacity of slurry can reduce the amount of air in liquid field and air content in bubble, so as to improve the anti-cavitation ability of slurry.