The unit is a C330 / N350-17.75 / 0.981 / 540/540 type steam turbine produced by Nanjing Steam Turbine Co., Ltd., which is manufactured by Shanghai Electric Power Repair and Manufacturing Plant 2 * 50% model: FK6F32M steam feed water pump configuration, using model G4.2- 0.9 / 350-4 330MW 50% BFPT steam turbine drive, the feed water pump lubricating oil system is centrally supplied by the small steam turbine oil supply device. Since the units have been commissioned and put into operation, the temperature of the lubricating oil of the steam pump bearing is high, up to 51 ℃. After consulting the pump manufacturer's instructions, the temperature of the bearing lubricating oil is between 43-48 ° C, and the temperature of the lubricating oil in the accident state is 43-60 ° C. For this abnormal parameter, analyze and find the cause.
The reason for the high temperature of the lubricating oil of the steam pump bearing: after comparing the temperature table of the lubricating oil of the steam pump bearing of the local units is basically the same as that in the microcomputer, the infrared thermometer is used to measure the temperature of the oil inlet pipeline of the steam pump bearing. It is basically the same as the oil inlet temperature of the steam pump bearing lubricating oil in the microcomputer, which can exclude the high temperature caused by the indication of the thermal meter.
Check the oil temperature regulating valve of each unit's steam pump lubricating oil cooler. Now the oil temperature regulating valve of each unit's steam pump bearing lubricating oil cooler is in the fully open position, open the bypass valve of the small machine oil cooler regulating valve, There is no obvious change in the lubricating oil temperature of the steam pump. There is no jamming problem by checking the regulating valve after the # 2 machine is shut down. Therefore, the situation that the lubricating oil temperature is too high due to insufficient cooling water is excluded. After the shutdown of # 2 machine, switch the 2-2 small machine oil cooler to standby operation, clean the operation oil cooler, and check the heat exchange fins of the plate heat exchanger to find that there is no obvious blockage. A dirty oil blocker causes the oil temperature of the oil cooler to rise.
An inspection of the small engine oil tank system revealed that the outlet of the small engine lubricating oil cooler entered the oil tank after passing through the oil filter, and then from the outlet mother pipe to the 12.6 meter steam pump bearing, so it is not excluded that the lubricating oil enters the oil tank after being cooled by the oil cooler After heating the lubricating oil temperature, it is necessary to take the opportunity of outage to carry out transformation and observe the effect.
Check the cooling situation of the small machine lubricating oil cooler, compare the local oil temperature meter inlet and outlet of the small machine cold oil cooler with the microcomputer, so exclude the inaccurate indication of the local meter, Check the cooling system of the engine, the lubricating oil of the small machine enters the oil cooler all the way through the outlet of the main oil pump, and the other way directly connects to the oil cooler outlet through the temperature control valve and enters the oil filter. If the temperature control valve is not adjusted sensitively, it will cause cold oil For the case of the short circuit of the device, take the # 2 machine 2-2 small machine oil cooler as an example to check the cooling situation of the local small machine oil cooler. 2-2 The temperature of the inlet pipeline of the oil cooler of the small machine is 54.7 ℃, and the outlet pipeline of the oil cooler is 40.5 ℃, but the inlet pipeline of the oil filter is 49.9 ℃. It is judged that the oil cooler does not play a cooling role. The temperature control valve at the outlet of the oil heater is short-circuited, and only a small part enters the oil cooler. Therefore, it is judged that the temperature control valve of the oil cooler of the small machine has an insensitive adjustment problem, which causes the temperature of the oil to increase.
After consulting the temperature control valve manual, the temperature control valve is installed on the lubricating oil pipeline after the outlet of the oil cooler to maintain the stability of the lubricating oil outlet temperature, maintained at about 43 ℃, the temperature control valve temperature range is 43 ± 2 ℃, so The insensitive adjustment of the temperature control valve makes most of the lubricating oil directly enter the oil filter through the temperature control valve is the direct cause of the high temperature of the lubricating oil of the steam pump. It is necessary to take the opportunity of outage to check the temperature control valve to ensure that the lubricating oil temperature of the steam pump is within the normal range.