JPH03291492A - Vacuum adjuster for condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a condenser system for condensing turbine exhaust of a thermal power plant or a nuclear power plant, and particularly relates to a condenser vacuum adjustment device. Regarding.

(Prior Art) Condensers in thermal power plants and nuclear power plants generally use seawater or river water as cooling water, and this cooling water is supplied to the condenser by a cooling water pump. When the cooling water supplied by the cooling water pump passes through the many thin tubes provided in the condenser, it cools the turbine exhaust steam flowing into the condenser body. As the turbine exhaust steam is cooled, it condenses and its volume decreases all at once, so the inside of the condenser is maintained in a vacuum. Therefore, by maintaining the condenser in a vacuum, it is possible to increase the heat drop of steam energy and maintain high cycle efficiency.

However, when a power plant is operated for a long time, air leaks into the condenser and non-condensable gas in the steam accumulates in the condenser, reducing the vacuum level of the condenser, so this cannot be prevented. A vacuum pump is installed for this purpose. This vacuum pump is operated continuously during condenser operation.

By the way, when seawater or river water is used as cooling water, low-temperature cooling water is supplied to the condenser in winter. Due to the characteristics of the condenser, the lower the cooling water temperature, the higher the vacuum can be obtained. Furthermore, the condenser has the characteristic that when the temperature of the cooling water is constant, the smaller the amount of incoming steam, the higher the vacuum can be obtained.

Therefore, although high vacuum is desirable from the viewpoint of maximizing the use of steam energy and increasing cycle thermal efficiency, on the other hand, it poses the following problems in actual operation.

One is an increase in steam wetness. In other words, if the humidity of the turbine exhaust increases, the blades near the final stage of the turbine will not only be damaged by two lotions, but also cause corrosion, which will ultimately lead to serious problems such as reduced efficiency and flying blades. There is a problem that this may lead to an accident.

The second is a change in the alignment of the turbine shaft due to the deformation of the turbine exhaust chamber. In other words, a high vacuum means that the external pressure becomes relatively large, and this also changes the pressure acting on the turbine exhaust chamber. This results in deformation of the turbine exhaust chamber and changes in the alignment of the turbine shaft.

The details of turbine shaft alignment will be omitted, but it is closely related to stable operation of the turbine. If this alignment changes, the vibration characteristics of the turbine change, which may lead to increased vibration and problems such as stoppage.

In order to prevent the above-mentioned problems, certain limits are placed on high-vacuum operation, and various measures have been taken to prevent the vacuum from becoming any higher. For example, a method is known in which the capacity of a vacuum pump is adjusted by injecting air into the suction side of the vacuum pump to give an apparent extra load to the vacuum pump.

An overview of such a conventional condenser vacuum adjustment method will be explained with reference to the system diagram shown in FIG.

Seawater or river water is supplied to the condenser 1 as cooling water by a cooling water pump 2 via a cooling water supply pipe 3 . This cooling water exchanges heat with turbine exhaust steam in the condenser 1, and the cooling water that has finished its work is discharged to the outside of the system via the cooling water discharge pipe 4.

After the turbine exhaust condenses in the condenser 1, the condensate pump (
(not shown) is again sent to the condensate system (not shown). However, non-condensable gas that cannot be completely condensed and air that leaks into the condenser are removed by the vacuum pump 5 through the vacuum pump inlet pipe 6.
It is discharged to the outside of the system via the vacuum pump outlet pipe 7, and the condenser 1
A degree of vacuum is maintained.

In order to eliminate the above-mentioned problems when the vacuum becomes high during winter or the like, a line consisting of an air injection pipe 8 and an air injection valve 9 is provided. Air is injected into the vacuum pump 5 through this line, and the amount extracted from the condenser 1 through the air extraction pipe 6 is reduced by that amount, so that high vacuum is not achieved.

In some cases, the air injection pipe 8 and the air injection valve 9 are directly connected to the condenser 1.

(Problems to be Solved by the Invention) However, the above-described conventional method has the following problems. That is, when the air injection valve 9 is opened to inject air into the suction side of the vacuum pump 5 to prevent high vacuum, dissolved oxygen in the condensate increases.

Many iron-based materials are used in condensate systems. Since these iron-based materials are easily oxidized (corroded), dissolved oxygen in condensate is strictly controlled to prevent this. However, if air is injected to prevent a high vacuum, dissolved oxygen will become highly concentrated and cause corrosion. If air is not injected, a high vacuum will result, causing the problems described above.

Incidentally, in recent years, especially in thermal power plants, in order to follow fluctuations in electric power demand, even large-capacity thermal power plants have frequently been operated with nighttime shutdown or minimum load operation at night. These operations are, so to speak, operations with less turbine exhaust steam, and are increasingly operated under high vacuum conditions. Therefore, avoidance of this high vacuum operation and measures to reduce dissolved oxygen are issues that need to be solved as soon as possible.

The present invention was made in view of this situation, and its purpose is to prevent the condenser from operating at an excessively high vacuum, and to improve the condenser vacuum without increasing dissolved oxygen in the condenser. The object of the present invention is to provide a regulating device.

[Configuration of the Invention (Means for Solving the Problems) In order to achieve the above object, the present invention provides a condenser for condensing exhaust steam of a turbine, and a cooling water supply for supplying cooling water to the condenser. A condenser vacuum adjustment device comprising a pump and a vacuum pump that maintains the pressure in the condenser at a specified vacuum by sucking in non-condensable gas in the condenser and discharging it to the outside of the system, wherein the vacuum pump It is composed of a vacuum pump bypass pipe that communicates the inlet pipe and the outlet pipe, a flow rate adjustment valve provided in the middle of the vacuum pump bypass pipe, and a U-shaped seal and a nitrogen gas filling device connected to the vacuum pump outlet pipe. It is characterized by this.

(Function) According to the present invention, the vacuum pump sucks in and discharges the circulating non-condensable gas and the non-condensable gas from the condenser, so the sucked non-condensable gas from the condenser decreases, and the non-condensable gas from the condenser decreases. The degree of vacuum is maintained at a certain value, high vacuum operation is avoided, and since there is no air injection, dissolved oxygen in the condenser does not increase.

(Example) Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a system diagram of an embodiment of the present invention. Note that the same parts as those in FIG. 2 already explained will be described with the same reference numerals.

In FIG. 1, cooling water of seawater or river water is supplied to a condenser 1 via a cooling water supply pipe 3 by a cooling water pump 2. The cooling water that has exchanged heat with the turbine exhaust steam in the condenser 1 is discharged to the outside of the system through the cooling water discharge pipe 4. On the other hand, after the turbine exhaust gas is condensed in the condenser 1, it is again sent to the condensate system (not shown) by a condensate pump (not shown). However, non-condensable gas that cannot be completely condensed and air that leaks into the condenser are discharged from the system by the vacuum pump 5 through the vacuum pump inlet pipe 6 and the vacuum pump outlet pipe 7. degree is held at a predetermined value. Further, a vacuum pump bypass pipe 10 is provided to bypass the vacuum pump 5 provided at the connection point between the vacuum pump inlet pipe 6 and the vacuum pump outlet pipe 7, and a vacuum pump bypass valve 11 is provided in the middle of the bypass pipe 10. Further, a nitrogen gas filling tube 13 for filling nitrogen gas from a nitrogen gas filling device 12 is provided on the vacuum pump 5 side of the vacuum pump outlet tube 7, and a U-shaped seal portion 16 is formed on the exit side of the vacuum pump outlet tube 7. At the same time, a nitrogen gas discharge pipe 14 and a discharge valve 15 are provided.

Next, the operation of this embodiment will be explained.

Normally, after the turbine exhaust gas is condensed in the condenser 1, it is sent again to the condensation system (not shown) by a condensate pump (not shown). The air leaking into the vacuum pump inlet pipe 6. It is discharged to the outside of the system via the vacuum pump outlet pipe 7, and the degree of vacuum in the condenser 1 is maintained at a predetermined value. However, when the condenser 1 is operated in a high vacuum of a predetermined value or higher, the vacuum pump outlet pipe 7 is filled with nitrogen gas from the nitrogen gas filling device 12 via the nitrogen gas filling pipe 13. Thereafter, a vacuum pump bypass pipe 11 is provided in the middle of a vacuum pump bypass pipe 10 that connects the vacuum pump inlet pipe 6 and the outlet pipe 7.
Let's open. Then, the non-condensable gas extracted from the condenser 1 reaches the vacuum pump outlet pipe 7 by the vacuum pump 5, but since the U-shaped seal part 16 is filled with nitrogen gas,
The waste is not discharged outside the system and is returned to the bypass pipe 10. It will be sucked into the vacuum pump inlet pipe 6 through the bypass valve 11.

By repeating the above-described operations, the amount of non-condensable gas extracted from the condenser 1 is reduced, so that excessively high vacuum operation of the condenser 1 is prevented. In addition, the vacuum pump outlet pipe 7 is cut off from the outside by nitrogen gas at the U-shaped seal portion 16, and only non-condensable gas passes through the vacuum pump 5, so that the vacuum pump does not draw in the vacuum pump.

Air inflow from the discharge system can be completely suppressed. Therefore, since the dissolved oxygen concentration in the condensate does not increase, prevention of high vacuum operation and prevention of increase in dissolved oxygen concentration are achieved at the same time.

The degree of vacuum can be adjusted as desired by adjusting the degree of opening of the bypass valve 11. Furthermore, by providing the nitrogen gas exhaust pipe 14 and the exhaust valve 15 in the U-shaped seal portion 16, nitrogen gas can be filled in and discharged as desired, so vacuum adjustment can be performed as appropriate depending on the operating status of the plant. can.

In the above embodiment, the nitrogen gas filling tube is connected to the vacuum pump outlet tube, but it may be a vacuum pump bypass tube or a vacuum pump suction tube. Furthermore, it may also be the condenser itself. In either case, it goes without saying that the same effect can be obtained by finally filling the U-seal portion of the vacuum pump outlet pipe with nitrogen gas and sealing it at the U-seal portion.

Further, although the above embodiments have been described using nitrogen gas as an example of sealing, it goes without saying that similar effects can be obtained by using other inert gases.

[Effects of the Invention] As explained above, according to the present invention, the vacuum pump sucks in and discharges the circulating non-condensable gas and the non-condensable gas from the condenser. The degree of vacuum in the condenser is maintained at a certain value, avoiding high vacuum operation, and since there is no air injection, dissolved oxygen in the condenser does not increase.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention, and FIG. 2 is a system diagram of a conventional condenser vacuum adjustment device. 1... Condenser 3... Cooling water supply pipe 5... Vacuum pump 7... Vacuum pump outlet pipe 11... Bypass valve 13... Nitrogen gas filled pipe 15... Nitrogen gas discharge Valve 2...Cooling water pump 4...Cooling water discharge pipe 6...Vacuum pump inlet pipe I0...Bypass pipe I2...Nitrogen gas filling device 14...Nitrogen gas discharge pipe 16... U-shaped seal part

Claims (1)

[Claims] A condenser that condenses the exhaust steam of the turbine; a cooling water pump that supplies cooling water to the condenser; A condenser vacuum adjustment device comprising a vacuum pump that maintains the pressure at a specified vacuum, a vacuum pump bypass pipe that communicates the inlet pipe and the outlet pipe of the vacuum pump, and a flow rate adjustment device provided in the middle of the vacuum pump bypass pipe. A condenser vacuum adjustment device comprising a valve, a U-shaped seal connected to the vacuum pump outlet pipe, and a nitrogen gas filling device.