JP3061962B2 - Steam turbine lubricating oil system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine lubricating oil system for supplying lubricating oil to a steam turbine.

[0002]

2. Description of the Related Art For example, there is a lubricating oil system for a steam turbine bearing as shown in FIG. The steam turbine bearing lubricating oil system is roughly classified into three systems: a lubricating oil supply system, a lubricating oil cleaning system, and a lubricating oil supply system. The lubricating oil supply system is a portion including the oil tank 2, the oil pumps 3, 4, the turbine bearing 5, the lubricating oil supply pipe 6, and the return oil pipe 7. The lubricating oil cleaning system is a portion configured by the oil purifier 21 and the oil filter pump 22. The lubricating oil supply system is a portion configured by an oil storage tank 31, an oil transfer pump 32, and an oil pipe connecting these devices. A general lubricating oil flow when the steam turbine is in a load operation state is generated by using the steam turbine rotor as a drive shaft. That is, the control oil from the main oil pump 8 drives the oil turbine 9 provided in the oil tank 2, and then becomes lubricating oil for the bearing and flows into each turbine bearing 5 via the lubricating oil supply pipe 6. The lubricating oil from the turbine bearing 5 is returned to the oil tank 2 through the return oil pipe 7. On the other hand, the stored oil in the oil tank 2 is sucked up by the booster oil pump 3 driven by the oil turbine 9 and becomes the suction oil of the main oil pump 8.

[0003] A lubricating oil cleaning system is provided to prevent deterioration of the lubricating oil and ensure cleanliness. During normal operation, a certain amount of stored oil from the main oil tank 2 flows into the oil purifier 21 and is cleaned, and then returned to the oil tank 2 by the oil filter pump 22 again.

The lubricating oil replenishment system is a system for temporarily storing lubricating oil at the time of regular inspection or the like. For example, when recovering oil from a lubricating oil system or an oil purifier system, the oil filter pump 22 discharges oil. The line valves 23 a and 23 b or the oil tank drain valve 24 are opened and closed to inject oil into the oil storage tank 31. When the oil is filled from the oil storage tank 31 to the oil tank 2 or the oil purifier 21, the oil transfer pump 3
2 is operated to open and close the valves 25, 26, 27 of the system.

The electric bearing oil pump 4 provided in the oil tank 2 is used when the main oil pump 8 does not perform its function sufficiently at a low rotation speed in the process of starting and stopping the turbine. When the bearing oil pressure of the system drops abnormally, the pressure is automatically started using the pressure switch 40 or the like, thereby ensuring the bearing oil pressure, that is, preventing the bearing from burning out of the turbine.

[0006]

However, when the oil level of the oil tank 2 is abnormally lowered due to some accident, it is assumed that lubricating oil cannot be supplied to the steam turbine bearing. From the viewpoint of preventing fire due to oil leakage, the lubricating oil supply pipe 6
There are many double pipe systems that let the inside pass through. However, all the lubricating oil supply pipes 6 may not be able to adopt the double pipe method due to structural restrictions and the like. Is discharged. Since the decrease in the oil level of the oil tank 2 is notified by the oil level monitor 41 in the oil tank 2, the operator of the power plant can take appropriate measures if the cause of the oil leak is clear and the leak rate is low. However, if the cause is unknown or the leakage ratio is high and the oil level in the oil tank 2 is significantly reduced, the turbine is forcibly tripped to prevent the steam turbine bearing from burning. In this case, since the turbine rotating at the rated speed has a large moment of inertia, a large-capacity turbine such as a nuclear power turbine may require about two hours to stop. In such a case, the oil level drops below the oil suction portion of the oil pump 4 during that time, and eventually the lubricating oil is not supplied.

FIG. 4 shows the relationship between the decrease in the oil level of the oil tank 2 and the rotation speed of the steam turbine at the time of an accident.

At time t _1, it is assumed that the lubricating oil starts to be discharged out of the system due to breakage of the oil pipe or the oil tank 2 or the like, and the oil tank oil level a starts to decrease. At time t ₂ , the oil level continues to decrease and H ₁ decreases from the initial oil level, so that the oil level monitoring switch 41 operates. At this time, the operator forcibly trips the turbine to protect the turbine based on the situation judgment, lowers the turbine speed b, activates the electric bearing oil pump 4, and works to secure lubricating oil. However oil level drop in the oil tank 2 is continued, at time t ₃ would drop to a point lower than the initial oil level H2 (limit oil level capable bearing oil pump 4 sucks the oil). At this time, the turbine rotation speed is in the low rotation speed range, but has not been stopped, and the supply of the lubricating oil causes burnout of the bearing.

Therefore, in the prior art, when the oil level of the oil tank is abnormally reduced due to leakage of the steam turbine lubricating oil out of the system, it is necessary to secure the lubricating oil until the steam turbine is safely stopped. It was not enough and had some problems in turbine protection.

The present invention provides a steam turbine lubricating oil system capable of preventing burnout of a steam turbine bearing by mitigating the oil level drop and securing the function of a bearing oil pump when the oil tank oil level is abnormally reduced. The purpose is to gain.

[0011]

SUMMARY OF THE INVENTION An oil tank storing lubricating oil to be supplied to a bearing of a steam turbine, an oil level monitor for continuously detecting the oil level of the oil tank, and an oil transfer pump to the oil tank An oil storage tank for replenishing the lubricating oil with
In a steam turbine lubricating oil system including an oil purifier for purifying lubricating oil in an oil tank and an oil filter pump for supplying the lubricating oil purified by the oil purifier to the oil tank and the oil storage tank, Based on the oil pipe connecting the oil transfer pump and the oil tank via the electric valve and the oil level information from the oil level monitor, if the oil level is below a predetermined position or the rate of decrease of the oil level Is greater than or equal to a predetermined value,
It is determined that the oil level is abnormal, and the electric valve is opened and the oil transfer pump of the oil storage tank is started,
An oil pump starting device for supplying the lubricating oil stored in the oil storage tank to the oil tank.

Further, each of the sedimentation chamber, the filtration chamber and the oil storage chamber of the purifier is connected to the suction port side of the oil filter pump by a pipe via an electric valve, and an oil pump activation device is provided.
It is determined that the oil level is abnormal if the oil level is below a predetermined position or the rate of decrease of the oil level is above a predetermined value according to the oil level information from the oil level monitor. Then, all the electric valves in the oil purifier chambers are opened, and the oil filter pump is started to supply the lubricating oil to the oil tank.

[0013]

According to this, when the oil surface position of the oil tank is below a predetermined position, or when the change rate of the oil surface position is above a predetermined value, the oil storage pump is started and the electric valve is controlled to supply lubricating oil to the oil tank. The supply improves the reliability of the lubricating oil system of the steam turbine.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a system diagram showing one embodiment of the present invention. Compared to the conventional example shown in FIG. 3, an oil level monitoring device 42 for monitoring the oil level of the oil tank and an oil pump starting device 43 for determining whether the oil level is abnormally lowered or whether the oil transfer pump 32 should be started. An oil pipe 10 for directly connecting an oil transfer pump 32 discharge line to an oil tank, an electric valve 11 provided on the line, and electric drain valves 28a, 28b, 28c provided in each chamber inside the oil purifier. An oil pipe 29 for connection to an oil filter pump is added.

The oil tank oil level monitor 42 is a device for continuously monitoring the oil level, and outputs the information to the oil pump starting device 43 sequentially. Oil pump starter 43
In, for example, when the oil level drops abnormally, when the oil level drop rate is large and lubricating oil is expected to run out, or when the operator predicts danger and forcibly operates the oil pump start push button 44, The oil transfer pump 32 is automatically started and the electric valve 11 is automatically opened. Therefore, the oil in the oil storage tank 31 is sucked up by the oil transfer pump 32 and injected into the oil tank 2 via the oil pipe 10 and the electric valve 11.

On the other hand, the oil pump start signal from the oil pump starter 43 causes the start signal to be input to the oil filter pump 22 of the oil purifier, and the sedimentation chamber, the filtration chamber, and the like in the oil purifier.
The electric valves 28a, 28b and 28c connected to the oil storage chambers are forcibly opened. Normally, during operation, the oil purifier 21
Only the oil in the oil storage chamber inside becomes the suction oil of the oil filter pump 22, but when the electric valve which can be a drain valve is opened, all the oil in the oil purifier 21 becomes oil filter pump 2
2 can be injected into the oil tank 2.

FIG. 2 shows the oil level drop at the time of an accident when the lubricating oil system according to the present invention is employed. Since the oil pipe or outflow of the lubricating oil to the cracked out of the system to the oil tank has been started at time t _1, and an oil tank oil level a began to decrease. In time t _2, the order operator is forced to stop the turbine for steam turbine protection, turbine speed b begins to drop. In the system according to the present invention, a forced start signal to the oil transfer pump 32 and the oil filter pump 22 is issued from the oil pump starting device 43 at time t ₃ ′, and the electric valves 11 and 28 are driven.
Since a, 28b, and 28c are forcibly opened and the lubricating oil is supplied to the oil tank 2, the change rate of the oil surface of the oil tank 2 becomes slow. For this reason, in the prior art, the oil level of the oil tank dropped to the bearing oil pump suction port at time t ₃ (H ₂ ), but in the present invention, it becomes H ₂ ′, which is lower than that. Also at time t ₄ when the turbine is stopped, oil level is H
₃ (H ₃ <H ₂ ) is ensured, and the bearing oil pump 4 can sufficiently perform its function.

The rate of descent of the oil level a of the oil tank 2 is determined by the difference between the amount of oil leakage and the sum of the capacities of the oil transfer pump 32 and the oil filter pump 22. Needless to say, the capacity of the oil transfer pump or the oil filter pump needs to be sufficiently studied and determined.

[0019]

As described above, according to the present invention, when the oil level of the oil tank is lowered due to the leakage of the lubricating oil out of the system, the oil transfer pump or the oil filter pump is forcibly operated.
The oil in the oil storage tank or the oil in the oil purifier can be injected into the oil tank. In addition, it is possible to alleviate a decrease in the oil level of the oil tank, thereby preventing an unexpected accident of the turbine bearing.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing characteristics of the present invention.

FIG. 3 is a system diagram showing a conventional example.

FIG. 4 is an explanatory diagram showing a conventional characteristic.

[Explanation of symbols]

 2 Oil tank 3 Booster oil pump 4 Electric bearing oil pump 5 Turbine bearing 6 Lubricating oil supply pipe 7 Return oil pipe 8 Main oil pump 9 Oil turbine 10 Oil piping 11 Electric valve 21 Oil purifier 22 Oil filter pump 23 Oil filter pump discharge line Valve 24 Oil tank drain valve 25 Valve 31 Oil storage tank 32 Oil transfer pump 40 Pressure switch 41 Oil level monitoring switch 42 Oil level monitoring device 43 Oil pump starting device 44 Start push button

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01D 25/18-25/20 F16N 7/36 F16N 29/00 F01M 11/06

Claims (2)

(57) [Claims] 1. An oil tank storing lubricating oil to be supplied to a bearing of a steam turbine, an oil level monitor for continuously detecting an oil level of the oil tank, and a lubricating oil supplied to the oil tank by an oil transfer pump. An oil storage tank for replenishing oil, an oil purifier for purifying lubricating oil in the oil tank, and an oil filter pump for supplying lubricating oil purified by the oil purifier to the oil tank and the oil storage tank. In a steam turbine lubricating oil system provided with: an oil pipe connecting an oil transfer pump of the oil storage tank and the oil tank via an electric valve; and oil level position information from the oil level monitor. When the position is equal to or less than a predetermined position or when the rate of decrease of the oil level is equal to or higher than a predetermined value, it is determined that the oil level is abnormal, and the electric valve is opened and the oil level is adjusted. The oil transfer pump of the storage tank Start to, a steam turbine lubricating oil system, characterized in that the lubricating oil which is stored in the oil storage tank and a supply oil pump start device to the oil tank. 2. The settling chamber, the filtration chamber, and the oil storage chamber of the oil purifier are connected to the suction port side of the oil filter pump by pipes via electric valves, respectively, and the oil pump activation device is connected to the oil pump. If the oil level position is less than or equal to a predetermined position based on the oil level position information from the oil level monitor, or if the rate of decrease in the oil level is equal to or higher than a predetermined value, the oil level position is abnormal. And operating the oil filter pump in order to supply lubricating oil to the oil tank while opening all of the electric valves in the respective oil purifier chambers. 2. The steam turbine lubricating oil system according to 1.