Study On Hydraulic Design And Pressure Fluctuation Characteristics Of Methanol Pump

Methanol pump is a kind of horizontal open multistage pump used for transporting methanol in industry.It is widely used in petrochemical and coal chemical industry because of its high flow rate and high lift.In a methanol pump,pressure pulsation in the special first double suction double volute is the key cause of pump vibration,and there is little research about it.In this paper,the pressure pulsation in double outlet volute is explored by cutting the first double suction impeller to optimize the pump operating environment.In this paper,a four-stage volute-type methanol pump is used as the research model.The author combined theoretical analysis,numerical calculation and experimental verification to compare and analyze the internal characteristics of the pump under different flow conditions,and the external characteristics of the numerical simulation are compared with the experimental results as well.Modal analysis of rotor shaft and impeller rotor components verifies the safety and reliability of pump rotor parts.The pressure pulsation characteristics of the first double suction impeller under different cutting conditions are studied,and the following conclusions are drawn:(1)The hydraulic design of the pump is reasonable and the numerical simulation results are in good agreement with the experimental results;(2)In prestressed modal analysis of pump rotor,the influence of centrifugal force on the natural frequency of the pump rotor is greater than that of the water pressure.The natural frequency of the rotor prestressed mode deviates from the vibration frequency of dangerous areas of the pump.The rotor is well designed and the pump operation is safe;(3)The pressure pulsation in the volute is in accordance with the rotation rule of the impeller after cutting the first impeller.When the cutting amount is 0.98,the pressure pulsation of the first double volute tongue is the best through different cutting amount.The pressure pulsation at the exit point of the volute decreases with the increase of the cutting amount,and the cutting amount of the impeller should not be too large;Under different cutting modes,the pressure pulsation of V-cutting is the best at volute tongue,and the pressure pulsation of oblique cutting is larger in the volute,and the effect is small at the exit point.