JPH0726790B2 - Gas extractor for condenser for grand seal steam - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a gas extraction device for a condenser for gland seal steam that condenses gland seal steam flowing out from a gland portion of a steam turbine to obtain condensed water.

[Technical Background of the Invention and Problems Thereof] Generally, in a steam turbine, a seal steam is sent from the outside to a gland portion, that is, a portion where a turbine rotor penetrates a casing, and a cycle steam flow leaking from the gland portion to the outside of the casing is prevented. I'm trying to cut it. The system that supplies this seal steam is independent of the main steam system that is connected to the boiler or reactor as a turbine gland seal system. We are working to obtain clean steam and completely eliminate cycle steam leaks in the gland. In this way, the supply of sealing steam is indispensable to prevent leakage of cycle steam,
On the other hand, in order for the supply of the seal steam to be smoothly performed, the discharge of the seal steam including the surplus must also be smooth. In this process, the seal steam sent to the gland part is guided to the gland seal steam condenser to exchange heat with cooling water (usually condensed water of cycle steam) to obtain condensate. The route to the steam condenser is sufficiently lower than atmospheric pressure during the operation of the steam turbine.
In other words, it is placed in a negative pressure state.

The negative pressure state of this turbine gland seal system is maintained by the configuration shown in FIG. That is, the turbine 1
The gland part 2 (in the figure, one turbine is shown, but a plurality of turbines are actually provided) has a gland seal steam condenser for keeping the vacuum by extracting the air inside the vessel with an exhaust fan 3. 4 and the gland seal steam pipe 5 are connected, and the path from the gland part 2 to the gland seal steam condenser 4 is kept at the same pressure. Incidentally, reference numeral 6 in the drawing
Is a stack that carries the air extracted by the exhaust fan 3 and discharges it into the atmosphere, and reference numeral 7 is a stop valve.

Normally, the internal pressure of the condenser 4 for gland seal steam is sufficiently low if the operation of the exhaust fan 3 is normal, but there is no problem,
If the blower 3 is stopped due to some accident, the non-condensable gas released from the seal steam introduced into the vessel cannot be discharged and the pressure inside the vessel rises. Due to the increase in the internal pressure, the smooth flow of the sealing steam is stopped, and it becomes difficult to supply and discharge the sealing steam to the gland portion 2 of the turbine 1. Therefore, the flow of the cycle steam leaking to the gland portion 2 cannot be stopped, and there is a concern that the efficiency of the turbine may be reduced or the steam containing radioactive pollutants may leak in the case of a nuclear turbine.

[Object of the Invention] The object of the present invention is to keep the path from the gland portion of the turbine to the condenser for gland seal steam in a negative pressure state even when the exhaust fan is stopped, whereby smooth flow of steam is not hindered,
It is an object of the present invention to provide a gas extractor for a condenser for a gland seal steam that does not cause a decrease in turbine efficiency or a steam leakage problem.

[Summary of the Invention] The present invention is provided between a gland seal steam condenser and a turbine condenser so that the pressure inside the gland seal steam condenser can maintain a constant level even when the exhaust fan is stopped. It is characterized by having a communication means.

Embodiments of the Invention Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the configurations shown in these figures, the same components as those shown in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 1, this embodiment (first embodiment) branches a communication pipe 9 that branches off from a route side of a condenser 4 for gland seal steam to a blower 3 and reaches a condenser 8 for a turbine. It is provided through.

In the configuration thus configured, the stop valve 7 is fully closed in accordance with the stop of the exhaust fan 3, and the communication valve 10 is fully opened so that the gland seal steam condenser 4 becomes the turbine condenser. 8 and the connecting pipe 9 are connected, and the internal pressure of the condenser 4 for gland seal steam finally settles to a value in equilibrium with the internal pressure of the condenser 8 for turbine. Normally, the turbine condenser 8 is maintained at a value close to an absolute vacuum of about 722 mm Hg during operation of the turbine 1, so when balanced with this, the pressure in the gland seal steam condenser 4 is equal to the above value. Then, the path from the gland portion 2 to the gland seal steam condenser 4 becomes a stable negative pressure state. Therefore, the flow of the seal steam is not obstructed at all, and the flow of the cycle steam flowing into the gland portion 2 can be cut off.

Next, FIG. 2 shows a second embodiment of the present invention.

That is, in the present embodiment, the expansion device 11 is provided in the path of the communication pipe 9 together with the communication valve 10. Normally, when the exhaust fan 3 is used, the pressure inside the condenser 4 for gland seal steam is several hundred.
It can be lowered to mmAg, but when it is equilibrated with the turbine condenser 8 close to absolute vacuum, it becomes too low,
There is a risk of inconvenience such as excessive flow of sealing vapor in the gland part 2, and this is brought closer to the design point.
The expansion device 11 is intended to adjust the internal pressure of the condenser 4 for the gland seal steam.

Also in the present embodiment, the path from the gland portion 2 to the gland seal steam condenser 4 is in a stable negative pressure state, and the flow of the seal steam is not impaired at all.

Further, FIG. 3 shows a third embodiment of the present invention.

The communication valve 10 of each of the above-described embodiments operates while maintaining the valve positions of two positions of fully open and fully closed, and the configuration of this embodiment automatically performs this operation. That is, here, the communication valve 12 detects an increase in the internal pressure of the condenser 4 for gland seal steam by the pressure detector 13, compares the detected value with a set value, and when the detected value is equal to or more than the set value, It is controlled by the controller 14 which outputs a signal for fully opening the valve position of the. Therefore, as in each of the above-described embodiments, the path from the gland portion 2 to the condenser 4 for the gland seal steam becomes a negative pressure state due to the full opening of the communication valve 12, the flow of the seal steam is always secured, and the leaking cycle steam It is possible to interrupt the flow at the ground section 2.

Furthermore, FIG. 4 shows a fourth embodiment of the present invention.

In this embodiment, instead of the communication pipe 9 and the communication valve 10 or the communication valve 12 of each of the above-mentioned embodiments, a gland seal steam pipe is branched to connect the emergency steam pipe 15 to the condenser 8 to the emergency communication valve 16 and the throttle. It is provided via the device 11. As a result, the pressure adjustment of the turbine gland seal system with respect to the abnormal stop of the exhaust fan 3 can be performed more quickly. In this case, since the flow of the seal steam is guided from the gland portion 2 to the turbine condenser 8, it is condensed together with the cycle steam in the turbine condenser 8.

[Effects of the Invention] As described above, according to the present invention, the internal pressure of the condenser for the gland seal steam is balanced with the internal pressure of the condenser for the turbine even when the exhaust fan is stopped. The path to the seal steam condenser is kept under negative pressure,
As a result, the smooth flow of the seal steam is not hindered at all, and the excellent effect that the turbine efficiency is not reduced and the steam leakage problem does not occur.

[Brief description of drawings]

FIG. 1, FIG. 2, FIG. 3 and FIG. 4 show the respective embodiments according to the present invention, showing the first embodiment, the second embodiment, the third embodiment and the fourth embodiment, respectively. FIG. 5 is a configuration diagram showing a conventional turbine gland seal system. 1 …… Turbine 2 …… Gland part 3 …… Exhaust fan 4 …… Grand seal steam condenser 5 …… Grand seal steam pipe 8 …… Turbine condenser 9 …… Communication pipe 10.12 …… Communication valve 11 ...... Throttle device 13 ...... Pressure detector 14 ...... Regulator 15 ...... Emergency steam pipe 16 ...... Emergency communication valve

Claims (4)

[Claims] Claim: What is claimed is: 1. A seal steam that flows out from a gland portion of a turbine is guided by an exhaust fan to a condenser for gland seal steam whose inside pressure is kept negative to condense it. A gland characterized by having a connecting means between the gland seal steam condenser and the turbine condenser so that the pressure inside the condenser can be maintained at a constant level even when the exhaust condenser is stopped. Condenser gas extractor for seal steam. 2. The connecting means is constituted by a connecting pipe which is branched from the side of the gland seal steam condenser leading to the exhaust fan and has a connecting valve leading to the turbine condenser. A gas extraction device for a condenser for a gland seal steam according to claim 1. 3. A gas extraction device for a gland seal steam condenser according to claim 2, wherein a throttle device is provided in the path of the connecting pipe. 4. The control signal of the communication valve compares a preset pressure with the detected internal pressure of the condenser for gland seal steam, and fully opens the valve position when the detected value exceeds the set value. The gas extraction device for a gland seal steam condenser according to claim 2, wherein the gas extraction device is provided by a device that outputs a signal.