Reasonable selection and normal operation and maintenance of energy-saving self suction centrifugal pumps

≪ One> Reasonable selection of energy-saving self suction centrifugal pumps The determination of reasonable selection parameters (Q, H) is a prerequisite for pump operation, but most self suction centrifugal pump parameters are not accurate. Reasonable selection of pumps can save energy consumption and reduce waste. Based on specific circumstances and design experience, make corresponding choices for the margin of each item

1. Determination of Q (flow rate)

For pumps operating continuously and stably, when the flow rate can be accurately calculated, no margin or less margin can be left;

; If there is more room for long-term consideration, the results of comprehensive weighing indicate that it is often better to replace the pump with a new one

2. Determination of H (Head)

The reasonable determination of this parameter is more difficult. From the perspective of energy conservation, the following points should be noted:

(1) The pipeline resistance should be determined by calculation, and cannot be underestimated.

H=H static+H resistance, where H static is easily calculated and generally determined accurately, and H resistance is often overestimated due to the complexity of calculation. When selecting a suitable pump model in practice.

. For example, if the head H is estimated to be about 3 meters higher, the selected pump will incur an additional annual electricity bill of nearly a thousand yuan

(2) The problem of margin

There is no need to leave margin when accurately calculating the H value.

. Q. The situation of leaving margin for both H parameters should be avoided, because regardless of which parameter has margin, it will bring margin to the other parameter

3. Selection of Pump Performance

For pumps with stable process flow, the performance is selected based on the operating point. When the process flow adjustment range is large, special attention should be paid to whether the Q-H curve and the Q-H curve are relatively flat within the adjustment range, so that the pump can operate in areas with higher efficiency.

4. Parallel Operation

For situations with large flow regulation and excessive flow, using multiple pumps in parallel can achieve pump operation, and coordinating the use of backup pumps is economically reasonable.

< II Normal operation and maintenance issues of the mechanical seal of the self suction centrifugal pump

1. Preparation and precautions before startup

(1) Check whether the mechanical seal of the self suction centrifugal pump, as well as the installation of auxiliary devices and pipelines, meet technical requirements

(2) Before starting the mechanical seal, perform a static pressure test to check if there is any leakage. If there is a lot of leakage, the cause should be investigated and the solution should be found. If it is still ineffective, it should be disassembled, inspected, and reinstalled. The general static pressure test pressure is 2-3 kilograms per square centimeter

(3) Rotate the pump towards the turning gear and check if it is light and even. If the turning gear is struggling or not moving, check if the assembly dimensions are incorrect and if the installation is reasonable

2. Installation and Shutdown

(1) Before starting, the sealing chamber should be kept full of liquid. When transporting solidified media, steam should be used to heat the sealing chamber to melt the media. Before starting, the car should be turned to prevent sudden starting and causing soft ring fragmentation.

(2) For mechanical seals using the external sealing oil system of the pump, the sealing oil system should be started and stopped first, and then the sealing oil system should be stopped

(3) After shutdown, the cooling water for the sealing oil chamber and end face seal cannot be stopped immediately. The cooling water can only be stopped when the oil temperature at the end face seal drops below 80 degrees to avoid damaging the sealing parts

3. Operation

(1) If there is a slight leakage after the pump is started, it should be observed for a period of time. If the leakage does not decrease after continuous operation for 4 hours, the pump should be stopped for inspection.

(2) The operating pressure of the pump should be stable, and the pressure fluctuation should not exceed 1 kilogram/square centimeter

(3) During the operation of the pump, suction should be avoided to prevent dry friction and seal damage on the sealing surface