Possible faults and treatment of the hottest indus

2022-09-22
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Possible faults and treatment of industrial pump operation

I. operation of industrial pump

1. Inspection before operation

accidents of industrial pump occur most in the early stage of production and operation of the device, and the installation quality directly affects the operation condition of the pump. Therefore, inspection should be carried out with special care during the test run

most accidents in pump installation are due to improper configuration of suction pipe, except that the driver is not aligned with the pump. The suction pipeline shall be straight and shortened, and the long pipeline must be enlarged to reduce the friction resistance of the pipeline. And avoid the occurrence of high local airbags that are easy to cause accidents. Therefore, the eccentric reducer with straight upper part should be used; Filter holes (about 40 mesh) shall be set on the pipeline before the pipeline is connected with the pump, and its net area shall be times of the flow section of the suction pipe. Install a pressure gauge before and after the filter to monitor the blockage of the filter during operation; All supports of the pipeline should give full play to their respective roles. The pipeline should be pressure tested, and the water test pressure should be 1.5 times the operating pressure, without leakage

check whether the pump foundation is firm, whether the bolts and nuts are loose, and whether they can withstand the deflection and impact generated during operation. Check whether the pump components and accessories are complete, and whether the installation and adjustment meet the requirements

II. Operation preparation

1. Turning

2. Check the suction conditions

3. Adjust the packing or mechanical seal device. Supply water and liquid to the cooling and sealing liquid systems in the cooling water jacket and sealing device respectively, and confirm that the flow channel is unblocked

4. Add lubricating oil and grease. Add selected qualified lubricating grease to the oil tank and lubricating parts to achieve appropriate oil level height and grease amount

5. Pump filling

6. It is necessary to preheat or precool the high-temperature pump and low-temperature pump

III. operation

1. The general starting methods of starting the

pump are as follows:

(1) open the suction valve, close the drain valve, open the vent valve for pump filling, and close the vent valve after seeing the liquid

(2) open the bearing cooling water valve and pressure gauge valve

(3) if the stuffing box is equipped with a water jacket, open the water supply valve in its cooling pipe

(4) if there is a sealing device, open the sealing valve

(5) the preheating valve should be opened before the high-temperature pump reaches the operating temperature. When the preheating is completed, the preheating valve should be closed

(6) if there is a device to prevent overheating, open the valve of the self circulation system

(7) start the motor

(8) after reaching the rated revolution and the reading of the outlet pressure gauge indicates the rated value, gradually open the drain valve and adjust the flow with the drain valve to be moderate

(9) check the leakage at the stuffing box. In order to ensure that the packing can be fully lubricated, the gland and liquid sealing valve can be adjusted to maintain an appropriate amount of leakage

(10) after the pump flow increases, close the self circulation valve if overheating is no longer possible

2. Shutdown

the shutdown method of pump should also be determined according to its form and purpose. Generally, the shutdown sequence of centrifugal pump driven by motor is as follows

(1) open the valve of self circulation system

(2) close the drain valve

(3) stop the motor

(4) if the operating temperature of the pump is maintained, open the preheating valve

(5) close the cooling water feed valve of the bearing and stuffing box. In winter, the cooling water system can be purged for antifreeze

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(6) if liquid sealing is not required during shutdown, close the liquid valve

(7) if necessary, close the suction valve, open the air valve (or vent hole) and drain valve, and drain all the liquid in the pump

axial flow pumps, etc. should reverse the above two items (2) and (3), most of which are to stop the motor first and then close the drain valve

II. Pump switching

I. the switching sequence of the in-service pump and the standby pump is:

1. Start the standby pump to add it to the running pump pipeline and maintain the parallel operation state in a short time

2. The pump in use can be stopped after it is checked and confirmed that there is no abnormality when the standby pump reaches the specified number of revolutions

it must be noted here that during short-term parallel operation, the standby pump is in a closed operation state. At this time, if the pump is stopped soon, it is prone to water hammer. Moreover, if the check valve on the discharge side does not work properly, the liquid will flow back to the disabled pump, causing the pressure of the discharge pipeline to drop and the flow to decrease. Therefore, in order to prevent the above phenomena, it is necessary to slowly close the discharge valve of the in-service pump, and then stop the in-service pump after the sample mill loss and heavy standby pump have been stable at the normal operation point

II. Problems that may occur during small flow operation

1. The temperature rise of the pump

the difference between the shaft power consumed by the pump and the hydraulic power generated by the zigzag pump is the loss of power. Except for a small amount of mechanical friction loss, other losses are converted into heat energy and transmitted to the liquid delivered in the pump, causing the temperature rise of the pump

2. Radial thrust problem

when the single volute pump operates at the highest efficiency point, the pressure acting around the impeller is almost equal, but it is not equal under other flows

3. Surge

when running with small flow, there will be regular periodic changes in flow and discharge pressure, which is called surge. However, since the liquid delivered by the pump is non compressible, the possibility of surge is small. However, when the pump has a hump performance curve and the discharge pipeline regulating valve is far from the pump outlet, surge may occur when the detection data and functional requirements are not many and the digital display can meet. When surge occurs, there is vibration and sound, which will have a negative impact on the pump. Sometimes, when the recirculation problem is found in the suction part of the centrifugal pump, a similar surge phenomenon will appear, but this is not surge. This similar surge phenomenon mostly occurs in pumps with large flow or large diameter impeller with low suction vacuum height. (end)

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