Water ring vacuum pump is a common vacuum pumping equipment in vacuum system of power plant. It plays an important role in establishing vacuum before unit start and maintaining vacuum after unit start
The working performance of vacuum pump directly affects the vacuum of the unit and the economy of the power plant. Let’s talk about the starting and stopping steps, normal operation of vacuum pump and the problems that should be paid attention to.
The start and stop steps of water ring vacuum pump are as follows:
1、 Before start-up, check that the system connection is in good condition, the work order is completed, the irrelevant personnel are evacuated from the production site, the status of the relevant valves of the system is correct, and the on-site measuring meters have been put into normal operation.
2、 Check that the control pressure of the pneumatic inlet valve is normal, the compressed air pressure is kept at 0.4-0.5mpa, the power supply of the inlet pneumatic valve has been supplied, and the switch test is normal.
3、 Check that the valve of the vacuum pump water supply system has been opened, the condensate pump is in normal operation or the pressure of the demineralized water system is normal.
4、 Check that the inlet and return water valves of the cooler are open, the water supply pressure is normal, the steam water separator and the valve status of the make-up water pipeline are correct, the drain valve at the bottom of the steam water separator is closed, and the drain valve of the pump body is closed.
5、 Open the by-pass valve of the water make-up valve of the steam water separator to make up the water level of the steam water separator to 140-180mm, then put the solenoid valve into operation, open the front and rear manual valves of the solenoid valve, and put the automatic regulation into operation
6、 The insulation of the tester is qualified, and then the power supply is put on. Check that the grounding wire of the motor is in good condition, and confirm that the starting conditions are met
7、 Confirm that the vacuum breaking valve of the exhaust device has been closed and the water seal device of the shaft seal heater has been put into operation. And water injection sealing is carried out for the vacuum breaking door.
8、 Start the vacuum pump to operate, the current is not greater than the rated current, check that the vacuum pump operates normally, the water level of the air-water separator is normal, the vibration of the motor and the pump bearing is normal, the temperature change is normal, the temperature rise of the bearing is not more than 40 ℃, the bearing temperature of the vacuum pump is not more than 75 ℃, and the bearing temperature of the motor is not more than 85 ℃.
9、 When the pressure difference at the inlet of vacuum pump reaches 0.3kpa, the connection of inlet pneumatic valve is normal. Otherwise, it should be opened manually.
10、 Check that the vacuum of the unit starts to rise, the vacuum pump operates normally, the body has no abnormal sound, the water leakage of the packing seal is suitable, the water level of the steam water separator is normal and stable, and the inlet and return water temperature of the cooler is normal.
11、 If the vacuum pump needs to stop using, the pneumatic valve at the inlet shall be closed first, and then the vacuum pump shall be stopped after the start-up inlet valve is closed. If the start-up inlet valve cannot be closed normally, the manual inlet valve shall be closed and then the vacuum pump shall be stopped. At the same time, when the pump is stopped, the interlock of standby motor shall be released, otherwise the pump will be interlocked and self started.
The following points can be summarized for the precautions during the start stop and normal operation of vacuum pump
1. Before the start-up, the conditions shall be fully checked to ensure that the water level of steam water separator is normal before the start-up, neither high water level start-up nor water free start-up is allowed.
2. Before starting, the manual inlet valve shall be opened, which can be started. After starting, the valve shall be automatically connected under the effect of pressure difference. The pneumatic valve shall be opened first and then started, otherwise the vacuum of the unit will drop.
3. During normal operation, the water level of the steam water separator shall be kept within a certain range. If the water level is too high, the water shall be drained through the bottom drain valve. If the water level is too high, the water shall be automatically discharged through the make-up solenoid valve. During operation, the monitoring water supply temperature is normal. If the temperature is too high, the water shall be changed in time to reduce the temperature, prevent the cooling effect from being affected and reduce the vacuum pumping capacity of the pump
4. When stopping, close the pneumatic valve at the inlet first, and then stop the operation of the vacuum pump after the pneumatic valve at the inlet is closed normally. If the pneumatic valve at the inlet cannot be closed normally, keep the vacuum pump running, close the manual inlet valve locally, and then stop the vacuum pump, and then contact the maintenance personnel to find out the cause and deal with it normally.
5. When the unit establishes vacuum, three vacuum pumps shall be started to quickly establish vacuum. When the unit operates normally, one vacuum pump shall be kept in operation and two for standby.