JP2624275B2 - Operating method and operating device for oil pump for steam turbine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for operating a pump for a control oil system of a steam turbine and a pump for a bearing lubricating oil system. The present invention relates to an oil pump operation method and an operation device suitable for operation using the same one pump at different times.

[Conventional technology]

FIG. 3 is a system diagram showing a conventional example of this type of oil pump operating device.

A main oil pump 2 is installed in an oil tank 1 and is directly connected to an AC motor 3.

In oil supply facilities that do not have a turbine shaft driven main oil pump but have an AC motor driven main oil pump, in addition to one AC electric driven main oil pump that operates during normal operation, Although it has a replacement electric drive pump of capacity, it is omitted in this figure. When the turbine driven by the boiler feed pump is started and during rated operation, the AC motor 3 is operated by the normal AC power supply 4 and the oil in the oil tank 1 is pumped by the main oil pump 2 connected to the AC motor 3. Discharge oil from the main oil pump 2 is supplied to a control oil system 5 for a turbine valve,
It is sent to the turbine bearing lubricating oil system 7 that has passed through the pressure reducing valve 6. Here, the oil pressure of the control oil system 5 is about 14 kg / cm ² , and the oil pressure of the lubrication oil system 7 is about 4 kg / cm ² .

When the main turbine and the generator (not shown) trip, the normal AC power supply 4 is lost, and the AC electric drive main oil pump 3 stops. At this time, the turbine driven by the boiler feed pump is also tripped, but in order to prevent seizure between the turbine rotor and the bearing, a DC motor 9 by the emergency DC power supply 8 and an emergency oil pump 10 connected to the DC motor 9 are used. Operates immediately and supplies oil to the bearing lubricating oil system 7. However, since the emergency DC power supply 8 is a storage battery, it cannot be used for a long time. Therefore, the emergency Dadel engine 11 is started, the generated power of the emergency AC generator 12 is started, and the AC motor 3 and the main oil pump 2 are operated again by this AC power supply, and during long-time turbine turning, It is also possible to continue supplying bearing lubrication oil. In this case, the boiler feed pump driven turbine (not shown) is tripping, but the rated oil pressure is supplied to the control oil system 5 and the bearing lubrication oil system 7.

Incidentally, a device related to this type of device is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-202310.

[Problems to be solved by the invention]

As described above, the main oil pump 2 supplies (i) the pressure oil to the control oil system 5 having a pressure of 14 kg / cm ² , and partially reduces the pressure to supply the pressure oil to the lubrication oil system 7 having a pressure of 4 kg / cm ^2. Supply state (during normal operation) and (ii) State where it is sufficient to supply only lubricating oil with a pressure of 4 kg / cm ² (for example, during turning or tripping)
There is.

Thus, when it is necessary to operate the emergency Dadel engine 11 and the emergency AC generator 12 and turn the AC motor 3 to operate the main oil pump 2, the above-mentioned (ii) 4k
g / cm ² lubricating oil supply is sufficient.

Nevertheless, the AC motor 3 for driving the main oil pump is also used in the state (i) (a state in which both 14 kg / cm ² of control oil and 4 kg / cm ² of lubricating oil are required). Therefore, the AC motor 3 and the main oil pump 2 are provided with large capacities to withstand the condition (i) (supply the control oil of 14 kg / cm ² ).

In connection with these matters, the emergency AC generator 12 for supplying emergency power to the large-capacity AC motor 3 and the emergency Dadel engine 11 as its power source must be provided with a large capacity. No.

 For this reason, the equipment cost becomes excessive.

The present invention has been made in view of the above circumstances, and supplies unnecessary and sufficient hydraulic and oil amounts according to the respective states of the above-described start-up, rated operation, and turning of the turbine.
It is an object of the present invention to provide an emergency AC motor, an operation method capable of reducing the capacity of an engine for driving the AC motor, and an operation device suitable for carrying out the operation method.

[Means for solving the problem]

The above object is achieved by switching the discharge pressure and the oil amount of the oil pump to the respective optimum necessary amounts at the time of starting the turbine, at the time of rated operation, and at the time of turning. Specifically, switching between the oil discharge pressure and the oil amount of the oil pump is achieved by switching the number of poles of an AC motor that drives the pump.

[Action]

FIG. 5 shows the relationship between the discharge amount and discharge pressure of the AC motor drive oil pump and the number of poles of the motor.

When the rotation speed N ₁ changes to N ₂ as a characteristic of the pump, N ₁
Between the discharge amount Q ₂ o'clock discharge amount Q _1, N ₂ when _{N 1 / N 2 = Q 1} / Q 2
Holds.

Also, when the rotation speed N ₁ is changed to N ₂ , the discharge pressure at N ₁
Relationship of _{(N 1 / N 2) 2} = P 1 / P 2 between the discharge pressure P ₂ o'clock P ₁ and N ₂ is satisfied.

That is, when the rotation speed of the pump is reduced to half, the discharge amount of the pump is reduced to one half in proportion to the rotation speed, and the discharge pressure of the pump is reduced to one fourth in proportion to the square of the rotation speed. Therefore, changing the discharge pressure and the discharge amount of the pump can be achieved by switching the pump circuit. Here, the rotation speed N of the pump
And the number of poles n of the AC motor driving the pump Holds. That is, reducing the number of revolutions of the pump to half is achieved by doubling the number of poles of the AC motor.

Further, as in the above example, the number of poles of the motor is reduced to 1/2, the rotation speed and the discharge amount of the pump are reduced to 1/2, and the discharge pressure is reduced to 1/4, so that the power consumption of the motor is reduced. In this case, taking into account mechanical losses and changes in pump efficiency characteristics,
/ 2 power savings.

In addition, the capacity of the emergency AC power supply is significantly reduced since it does not require the capacity to purchase a control oil system.

〔Example〕

FIG. 1 shows an embodiment of the operating device of the present invention configured to carry out the operating method of the present invention.

This embodiment is an example in which the present invention is applied to the above-mentioned conventional example and is improved. In FIG. 1 showing this example, the same reference numerals as those in the conventional example (FIG. 3) are used. The components are the same as or similar to those in the conventional example.

 Next, differences from the above-described conventional example will be described.

The AC motor 3 for driving the main oil pump 2 of the present embodiment includes a pole number switching device 13, and has a structure in which the number of poles can be switched between 2 poles and 4 poles.

In the rated state, the pole motor is driven by two poles. When the pole motor is switched to four poles, the rotation speed of the AC motor 3 and the main oil pump 2 directly connected to the AC motor 3 becomes 1/2 of the rated speed. The discharge pressure of No. 2 is 1/4 of the rated value.

Assuming that the rated discharge pressure is 14 kg / cm ² , the discharge pressure becomes 14 × 1/4 = 3.5 kg / cm ² by switching the number of poles (4 poles), and the power consumption of the AC motor 3 is also reduced to 1/3. It becomes ~ 1/2.

In carrying out the present invention, the main oil pump 2 may be provided with an oil pump (not shown) of the same specification as a spare.

At the time of startup and rated operation of the boiler feed pump drive turbine, the AC motor 3 is operated with two poles by the normal AC power supply 4 to remove the oil in the oil tank 1 from the main oil pump 2 connected to the AC motor 3. The oil is sent to the control oil system 5 and the bearing lubrication oil system 7 of the turbine. Here, the control oil system has a pump discharge pressure of 14 kg / cm ² , and the bearing lubrication oil system 7 has a
The pressure is reduced to 4 kg / cm ² and supplied.

When the main turbine and the generator (not shown) trip, the normal AC power supply 4 is lost and the AC electric drive pump 3
Stops.

However, in order to prevent seizure of the turbine rotor and the bearing, the DC motor 9 by the emergency DC power supply 8 and the flow motor 9
The emergency oil pump 10 connected to the oil pump operates immediately to supply oil to the bearing lubricating oil system 7. However, since the emergency DC power supply 8 is a storage battery, it cannot be used for a long time.

Therefore, the emergency Dadel engine 11 and the emergency AC generator 12 are started, the emergency AC power supply 12 is started, and the AC motor 3 and the main oil pump 2 are operated again by the AC power supply, and the turbine turning for a long time is performed. Also supplies bearing lubrication oil. At this time, the number of poles of the AC motor 3 is switched from 2 poles to 4 poles by the switching device 13, so that the rotation speed and the discharge amount of the main oil pump 2 are 1/2 of the rated time, and the discharge pressure is 1 /
It becomes 4 and a 3.5 kg / cm ² oil pressure is supplied to the bearing lubricating oil system 7. By this switching, the power consumption of the AC motor 3 is reduced to about 1 /
Decrease by 3 to 1/2.

Since the power consumption of the AC motor (during two poles) that drives the main oil pump occupies about 20% of the entire emergency AC power supply, according to the present embodiment, the Dadel engine 11 and the emergency AC The capacity of the generator 12 can be reduced by 10 to 15%, which has effects on the system configuration and economy.

 FIG. 2 shows the above series of operation patterns.

FIG. 6 shows an embodiment in which the switching of the number of motor poles of the AC motor drive pump according to the present invention is applied to the oil system of the main turbine. When the main turbine is started, the control oil 5 and the bearing lubricating oil 7 are supplied by the auxiliary oil pump 15 driven by the AC motor 14, and the main oil pump 2 is directly connected to the turbine rotor shaft as the turbine 20 speeds up. And suction pump
18, pressure oil is supplied to the control oil system 5 and the bearing lubrication oil system 7 through the booster oil pump 19. When a steam turbine (not shown) trips and the normal AC power supply 4 is lost, an emergency oil pump 10 driven by a DC motor 9 by an emergency DC power supply 8 supplies oil to a bearing lubrication system.

According to the prior art, the turning oil pump is then operated by operating the emergency Dadel engine 11 and the emergency alternator 12.
In this embodiment, the number of poles of the AC motor 14 for driving the auxiliary oil pump 15 is changed by the switching device 13 from 2 poles to 4 poles. By switching to, the auxiliary oil pump 15 can be used only for supplying the bearing lubricating oil during turning, and an oil system in which the turning oil pump 17 and the AC motor 16 are omitted can be configured.

FIG. 7 shows an operation pattern of the embodiment according to the prior art, and FIG.
FIG. 3 shows an operation pattern of the embodiment of the present invention.

〔The invention's effect〕

According to the apparatus and method of the present invention, oil is supplied in accordance with the operating condition of the turbine, and the turbine generator is tripped to drive a pump for lubricating the bearing during turning when the AC power is normally lost. The power consumption of the AC motor can be reduced to 1/3 to 1/2, and the total capacity of emergency power generation equipment is 10%.
It can be reduced by ~ 15%, and has an excellent practical effect of enabling the system to be lightweight and low cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a system diagram of a turbine control oil and bearing lubricating oil around a tank according to one embodiment of the present invention, and FIG. 2 is a main oil pump and emergency oil according to one embodiment of the present invention. FIG. 3 is a diagram showing an operation pattern of a pump, FIG.
FIG. 4 is a table showing operation patterns of a main oil pump and an emergency oil pump in the prior art, FIG. 5 is a characteristic diagram of an AC motor driven oil pump, and FIG. FIG. 7 is a table showing an oil pump operation pattern in the prior art, and FIG.
It is a chart showing an oil pump operation pattern in an example. 1 ... oil tank, 2 ... main oil pump, 3 ... AC motor, 4 ... general AC power supply, 5 ... control oil system, 7 ... bearing lubrication oil system, 8 ... DC power supply, 9 ... DC motor, 10 ……
Emergency oil pump, 12 Emergency AC power supply, 13 AC current machine pole number switching device, 14 AC motor, 15 Auxiliary oil pump, 16 AC motor, 17 turning oil pump
18… Suction pump, 19… Booster oil pump, 20… Turbine.

Claims (2)

(57) [Claims] (A) a main oil pump for supplying oil to a control oil system and a bearing lubrication oil system of a steam turbine by pressure; (b) an AC motor driving the main oil pump; and (c) the AC motor. (D) an emergency AC generator for supplying power to the AC motor and an emergency engine for driving the AC generator; and (e) a backup for the main oil pump. (I) a control oil system and a lubricating oil, the method comprising: operating an oil system device of a steam turbine provided with the emergency oil pump, a DC motor for driving the emergency oil pump, and an emergency DC power supply. The state in which oil must be pumped to both the system and
(Ii) In a method of switching the operation to a state in which it is not necessary to supply oil to the control oil system by pressure and it is sufficient to supply oil only to the lubricating oil system, (f) the AC motor for driving the main oil pump includes: (G) In the state (i), the number of poles is reduced to increase the rotation speed of the AC motor for driving the main oil pump, and in the state (ii), the number of poles is increased. An operation method of an oil pump for a steam turbine, wherein the rotation speed of the electric motor is decreased. 2. A main oil pump for supplying oil to a control oil system and a bearing lubricating oil system of a steam turbine by pressurizing the oil; (b) an AC motor driving the main oil pump; and (c) the AC motor. (D) an emergency AC generator for supplying power to the AC motor and an emergency engine for driving the AC generator; and (e) a backup for the main oil pump. An emergency oil pump, a DC motor for driving the emergency oil pump, and an emergency DC power supply, for driving an oil system device of a steam turbine, wherein: (f) the AC motor for driving the main oil pump (G) When the number of poles of the main oil pump driving AC motor is reduced by the above-described pole number switching apparatus, the rotation speed of the main oil pump increases, and when the number of poles is increased, Main oil po Wherein the rotational speed of the flops is configured to decrease the operating device of the steam turbine oil pump.