01 Preparation before starting
In order to ensure the safe operation of the pump, the unit should be fully and carefully inspected before starting the pump. Especially for newly installed pumps and pumps after overhaul, more attention should be paid to the inspection work so that problems can be dealt with in time. The main inspection contents are as follows:
1. Check whether the rotor of the unit is flexible and light, and whether there is metal friction in the pump. If so, the reason should be checked. This inspection is often carried out by cranking, that is, turning the coupling of the unit by hand.
2. Check whether the lubricating oil in the bearing is normal and the oil quality is clean.
3. Check whether the gate valve on the outlet pipe is flexible for opening and closing.
4. Check whether the anchor bolts and other connecting bolts of the water pump motor are loose or fall off, if any, they should be tightened or replaced.
5. Remove the debris on the water inlet of the pump to prevent the debris from being sucked into the impeller after starting up.
6. Check whether the direction of the motor and the pump are consistent and whether the power supply and distribution equipment is fixed; it is an indispensable task for the newly installed water pump or the pump after the overhaul to check the motor steering.
7. Check whether the control system is normal, whether the display of each instrument is accurate, and if there is remote control, check whether the remote monitoring is accurate and effective.
02 Diversion and start
1. Diversion
According to the working principle of the aforementioned centrifugal pump, the centrifugal pump must be diverted before starting. In general, small centrifugal pumps mostly use the method of irrigation and exhaust. At this time, the bottom of the suction pipe should be equipped with a bottom valve. The method of water introduction is tap water irrigation, overhead tank irrigation, and water pump irrigation. Most of the large and medium-sized centrifugal pumps use the water ring vacuum pump to pump water. When pumping, when there is water in the exhaust pipe, it means that the suction pipe and the pump are full of water, you can start the pump to start working.
For the self-priming pump installed below the water level of the suction tank, open the inlet valve, and the water will automatically fill the suction pipe and the pump.
2. Start
The centrifugal water pump is generally started with a closed gate. When starting, the operator and the crew should not be too close. After the pump speed stabilizes, the valves on the vacuum gauge and the pressure gauge should be opened immediately. At this time, the reading on the pressure gauge should rise to the pump The idling head at zero flow indicates that the pump has been pressurized. Then gradually open the gate valve on the pressurized water pipe. At this time, the vacuum gauge reading gradually increases, the pressure gauge reading gradually decreases, and the ammeter reading on the switchboard should gradually increase. The starting work is completed when the gate valve is fully opened.
When the pump is closed, the running time should generally not exceed 2~3min; if the time is too long, the water flow in the pump will be heated due to continuous circulation in the pump, causing damage to some parts of the pump.
If after the motor is closed, it is found that there is only a "buzzing" sound without turning, the power should be cut off immediately to check the cause.
If the pump runs without water, stop the pump immediately and check the cause.
03 Centrifugal pump operation management
1. After each pump unit is put into operation, the relevant record items on the daily operation report should be filled in time. For computer management, the daily operating data of each pump should be entered into the computer's storage system.
2. Pay attention to whether the unit has abnormal noise and vibration. When the pump is running normally, the unit should be calm and the sound should be normal and uninterrupted. Abnormal sound and vibration are often the precursors to the failure of the pump. In this case, the machine should be shut down for inspection immediately.
3. Pay attention to the inspection of the bearing temperature and oil quantity of the unit. The temperature of the bearing is generally not allowed to exceed the ambient temperature of 30 ℃ ~ 40 ℃, the highest does not exceed 75 ℃. When there is no thermometer, it can also be touched by hand. Judging from experience, if you feel very hot, you should stop and check.
4. The new unit uses grease ball bearings. The first oil change time is after the unit runs 80h~100h, and the oil is changed every 2400h in the future (using molybdenum disulfide lubricant, the time can be doubled). For bearings that are lubricated with mechanical oil, change the oil every 240h, and pay attention to the oil level between the two scales of the oil scale at any time, and refill at any time when there is insufficient.
5. The normal drip level of the stuffing box is generally as long as it can be controlled to drop down and not form a continuous line, that is, 20 to 150 drops per minute. The amount of dripping can be controlled by loose and tight packing gland. Note that it cannot be pressed unilaterally to prevent abrasion of the sleeve and gland.
6. Regularly check the couplings and the bolts on the feet of the unit. If any deviation or looseness is found, it should be corrected in time.
7. Pay attention to the change of instrument pointer. Under normal operating conditions, the position of the meter pointer should be basically stable at a certain position. If the indicator pointer changes drastically and jumps, the cause should be found immediately. For example, if the vacuum gauge reading rises, it may be that the suction pipe mouth is blocked or the water level of the water source drops; if the pressure gauge reading rises, it may be that the pressure water pipe mouth is blocked; if the pressure gauge reading decreases, it may be that the suction pipe leaks air and inhales air, or The speed should be reduced, the impeller is blocked, etc. For the motor, it should be noted whether the reading on the ammeter exceeds the rated current of the motor. If the current is too large or too small, it should be stopped in time to check.
8. If the large pump set uses water-cooled bearings or circulating oil-cooled motors, the water circuit and oil circuit should be kept clear. If the circulating cooling system fails, the pump should be stopped immediately for maintenance.
9. If the water level of the injection well is lower than the minimum design water level, one or two units should be properly shut down to avoid cavitation and damage to the impeller. Generally speaking, urban sewage generally has less water from midnight to 8 in the morning, so special attention should be paid.
10. For the pump unit without heat insulation measures, when the pump is not running in winter, the water should be drained from the threaded pipe plug at the bottom of the pump to prevent the pump from freezing and cracking. If the pump is not used for a long time, the water should be drained.
04 Centrifugal pump parking
Before the centrifugal pump is stopped, the vacuum gauge and pressure gauge valves should be closed for the centrifugal pump, and then the gate valve on the pressure pipe should be closed slowly to close the gate.
After stopping, the water and sludge on the surface of the pump and motor should be wiped clean. After the pump is not used for a long time or stopped in winter, the water in the pump casing should be drained immediately. Some problems that cannot be handled during operation should be dealt with in time after stopping.
For pumps with higher heads, attention should be paid to the possible damage caused by the water hammer when the pump is stopped. Generally speaking, the design of the water pump system has taken into account the impact of the water hammer when stopping the pump. It is important for the operator to ensure that the water hammer elimination system is intact and effective at all times, so that when the pump is stopped or suddenly due to failure When the pump is stopped, the effect of water hammer is effectively minimized.
Installation and use of centrifugal submersible pump
1. Before starting, carefully check whether the electric pump is deformed or damaged during the transportation, storage, installation, and whether the fasteners are loose or falling off.
2. Check whether there is oil in the oil chamber and whether the oil is clean.
3. Before starting, check whether the impeller rotates flexibly.
4. Check whether the power supply device is reliable, and whether the voltage and frequency comply with the regulations. If the motor reverses, you should immediately switch any two wiring positions to make it rotate forward.
5. Check whether the power supply device is safe, reliable and normal. The power supply voltage and frequency should meet the regulations.
6. Check whether the cable is damaged, broken, and whether the seal at the junction box is intact. If any irregularities are found, they should be properly handled.
7. It is strictly forbidden to use the pump cable as a suspension wire to avoid danger.
8. Before the new pump is used and the long-term pump is put into use, the insulation of the casing should be measured by a megohmmeter, and it should be no less than 2MΩ, otherwise the motor winding should be dried.
9. If the pump works in a sludge well, because there may be methane and other flammable gases in the well, the control cabinet should be far away from the wellhead, and the pump body should be fully immersed in water or mud to prevent explosion.
10. After the mobile submersible pump is raised from sewage or sludge, clean the inside and outside of the pump with clean water. It is best to run in clean water for one or two minutes.
11. The mobile installed pump should be taken out of the water after use. Long-term immersion in water will reduce the service life, especially in winter, icing will cause great damage to the pump and even make the pump scrap.
12. Regardless of the fixed installation pump or the mobile installation pump, they should be handled lightly.
13 The test operation time of the submersible pump in a water-free environment should not exceed 2~3min.
14. Before moving the submersible pump, the power supply must be cut off.
15. When the submersible pump is started, due to the reaction force of rotation, the whole pump body will have a sudden twist. The torque of large and medium-sized pumps can not be ignored, and sometimes the connecting hose will be twisted away from the joint. Therefore, pay attention to the firmness of the joint during installation. When twisting, be careful not to hit the hard structure.
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