JPS5879606A - Shaft seal device of geothermal heat steam turbine - Google Patents

Abstract

PURPOSE:To prevent deterioration of material and prevent generation of erosion and corrosion in a turbine shaft part, by utilizing a fact, that mixing of air into turbine condensed water is permitted in a geothermal steam turbine for the control of water quality, and performing a shaft seal of the geothermal steam turbine with the outside air. CONSTITUTION:During operation of a turbine, if a blower 17 is operated, the outside air is sucked, as shown by arrow heads (a), into annular gaps between shaft seal packings 4b and turbine shaft 3. The outside air, flowing in through the shaft seal packings 4b, is partially seized by packets 15, and the rest of air circulatively flows in annular gaps between shaft seal packings 4a and the turbine shaft 3, to flow in turbine exhaust parts 14 and block an outflow of turbine waste steam to shaft seal parts. The air seized in the pockets 15 is released to the atmosphere by the blower 17 via an exhaust pipe 16. While the air, flowing into the turbine exhaust parts 14, is discharged to the atmosphere via an air gas extracting pipe 11 of a condenser 12.

Description

DETAILED DESCRIPTION OF THE INVENTION l) Technical Field of the Invention The present invention relates to a shaft sealing device in a geothermal steam turbine.

j) Prior art In general, the shaft sealing device for geothermal steam turbines is
A steam pressure shaft sealing system, such as that used in conventional thermal or nuclear power turbines, is used.

That is, FIG. 1 is a schematic explanatory diagram of a conventional shaft sealing device for a geothermal steam turbine, in which a turbine shaft 3 penetrating through the end wall is provided at a portion of both ends of a cage containing a turbine row I/. On the outer periphery, several granoid shaft seals, 4c'b, $0, are provided. Further, a seal steam supply pocket 1 is formed on the outer periphery of the turbine rotor/near shaft seal gaskets $a and 4cb, which communicate with both wheel seal gaskets #a and MEbFIJffK, and to which a seal steam supply pipe j is connected. ．． In addition, the outer edge of the shaft is sealed with a seal-b, and on the outer periphery of the 3, there is a ring-shaped seal with 1 ring, 4 co.
A vapor collection pocket 7 is formed with a delayed seal. The sealed vapor collection pocket 7 is connected to the exhaust pipe r.
to the ground steam condenser via 'II! It is continued. In addition, the code 10 is a pet blower, /l water mouth /J
K is an air gas extraction pipe, /J is a condensate pump.

However, the sealed steam supply pipe! When the seal steam is supplied to the seal steam supply port 4 through the seal steam supply port 4, a part of the seal steam passes through the gap between the shaft seal packing 1 and the turbine shaft J, and flows out to the outside of the turbine exhaust. is prevented.

On the other hand, the remainder of the sealing steam passes through the gap between the shaft sealing member ypb and the turbine shaft J, and passes through the shaft sealing member 7f.

It mixes with external air flowing in from the casing, flows into the sealed vapor collection pocket 7, and prevents external air from flowing into the casing. Further, the mixed gas in the pocket 7 flows into the gland steam condenser via the exhaust pipe 1, where the sealing steam is discharged as condensate.

3) Problems with the conventional technology However, when a steam shaft sealing device is used in a geothermal steam turbine as described above, the degree of superheat of the geothermal steam used for shaft sealing is low, so cooling by the turbine shaft etc. is not sufficient. Steam condensation is likely to occur, and the water particles generated by the condensation cause corrosion to the ground labyrinth packing and the turbine shaft surface.

In addition, in a state where steam condensation occurs, metal and non-metallic gases are also condensed, so cracks due to stress corrosion cracks are likely to occur in the turbine shaft. Because of this, there are two disadvantages for some towns, such as a decline in financial strength and corrosion. In order to prevent these phenomena, methods such as shrink-fitting a sleeve made of corrosion-resistant material to the rotor shaft seal are currently being carried out, but this method is also cumbersome to process. There are other problems, such as making it more expensive.

Purpose of the Invention In view of the above, the present invention takes advantage of the fact that in a geothermal steam turbine cycle, the feed water heater and deaerator are distorted, so that air is mixed into the turbine cover water, which is permissible from the viewpoint of water quality management. In addition, by sealing the shaft with external air, it is possible to prevent deterioration of the turbine shaft portion, erosion, corrosion, and the like.

Another object of the present invention is to provide a shaft sealing device for a geothermal steam turbine that reduces the additional power of the air gas extraction system.

According to the present invention, external air is suctioned and passed through the shaft sealing portion as a shaft sealing fluid, and the outside air of the shaft sealing portion is
The feature is that at least one pocket is provided to capture a part of the air passing through the shaft seal, and an exhaust pipe having one end connected to an exhaust system RK is connected to the pocket, so that the external air sucked into the shaft seal is A part of the exhaust gas is discharged by the exhaust system, and the rest flows into the turbine exhaust section, and the shaft is sealed using the queen air.

4) Embodiment of the Invention FIG. 1 is a block diagram schematically showing a shaft seal device of the present invention, in which a plurality of shaft seal packings are provided on the outer periphery of the turbine shaft J.
1.4"fi is installed, and both shaft sealing/dia 1.
In the outer Pl@trap of Reference 1, a pocket lj is formed between the two shaft sealing paraki y. The pocket /311C is connected to the exhaust pipe /4, and a pro-alf is provided in the middle of the exhaust pipe /4.

When the blower 17 is operated during operation of the turbine, external air is sucked into the annular gap between the shaft seal packing #b and the turbine shaft 30 as shown by the arrow IK. Therefore, a part of the air flowing through the shaft seal packing y41b is trapped in the pocket/jtK, and the remaining air flows through the annular gap between the shaft seal packing 4Ia and the turbine shaft J to the turbine.
It flows to the bottle shaft part/41 and prevents the turbine exhaust steam from flowing to the upper r-shaft seal part. Therefore, the air captured by the air blower/3 is discharged into the atmosphere via the exhaust pipe 11 by the blower/74C. On the other hand, the air that has flowed into the turbine exhaust section /41L is discharged into the atmosphere through the air gas extraction pipe l/ of the condenser l.

By the way, some of the external inflow air is discharged through the condenser at a pressure higher than the pressure inside the condenser, so rather than leading the entire amount of external air to the bale water inlet and then releasing it to the atmosphere, it is better to It is possible to reduce the sum of the power required to discharge the air from the condenser and the power required to discharge the air flowing into the condenser. In addition, by increasing the number of pockets in the shaft seal section that discharges air and discharging the air to the corresponding negative pressure section, the amount of air flowing into the turbine exhaust section is reduced, and the amount of air flowing into the turbine exhaust section is reduced. Relative to the amount of air, the total power required for these discharges to the atmosphere can be further reduced.

That is, FIG. 3 shows another embodiment of the present invention, in which shaft seal packings 1) and 6 are provided on the outer periphery of the turbine shaft J, and shaft seals ≠ 1 and lb Pockets: y)/ja+/31) are formed on the outer periphery of the shaft seal and the outer periphery of the shaft seal G and G, respectively. On the other hand, the condensate a/2Ki1111 air gas extraction pipe// is sequentially provided with multiple stages of suction pops /l&, /Ib, /10.

Pocket near turbine rotor l/3b is exhaust pipe 74t
The pocket 151 on the atmospheric side is connected to the middle of the suction pump /Its and /Ib through the exhaust pipe /4.
It is connected to the middle of suction pot itb and /la via 8L.

Therefore, the trapped air flowing into the bokeh)/ja is sucked by the suction pop/IQ on the high pressure side, and the air is trapped in the bokeh:y
)/jb is pumped through a medium pressure suction pump 1lbK.
Therefore, they are sucked in and discharged into the atmosphere.

Therefore, in this case, by sucking the air in each pocket into the corresponding negative pressure part, it is possible to use the umbrella and the air gas extraction system pump of the condenser.
Equipment can be made more compact.

Furthermore, as shown in Figure 1, when the air gas extraction system of the water outlet is equipped with multiple stages of ejectors /9a and /913, the exhaust pipe 14 connected to It can also be connected to the intermediate part between the ejector/9b of the first stage and the ejector/9b of the first stage. In addition, wh, sob in figure 1
is turf.

7) Effects of the Invention As mentioned above, the present invention uses air from outside for the shaft seal of a geothermal steam turbine instead of using sealing steam as in the past, so that it eliminates the problem that conventionally occurs in the shaft seal. It is possible to completely prevent a decline in financial strength, corrosion, and the occurrence of erosion.

The shaft seal can be maintained in the same state as the initial state for a long period of time, and performance deterioration can be prevented. In addition, unlike conventional methods, there is no need to extract part of the working air from the main steam or intermediate stage of the turbine as sea steam, so there is no reduction in working steam, resulting in an increase in power, which is required for the air exhaust system. By providing sufficient power, it is possible to improve the properties of the koji tea. Furthermore, if a pump, ejector, etc. of the 9 gas extraction system of Mizuguchi is used as the exhaust port, it is possible to make the equipment more compact.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional geothermal steam turbine shaft sealing device, and FIGS. 2 to 2 are schematic configuration diagrams showing embodiments of the geothermal steam turbine shaft sealing amount of the present invention. 3...Turbine shaft, #a, 4tb, IIQ・
・・Shaft seal, /j, 15a, /jb-・
Pocket, 7A, /4a+/6m)...exhaust pipe, /7
...Blower.

Claims (1)

[Scope of Claims] 1. At least one air filter that absorbs and circulates external air as a shaft seal fluid through the shaft seal, and captures a portion of the air passing through the shaft seal in an external station of the shaft seal. A geothermal steam turbine/shaft-sealed snow that is characterized by having a pocket and connecting one end of the pocket to an exhaust pipe connected to an exhaust system. 7. The geothermal steam turbine/shaft sealing device according to claim 7, characterized in that the exhaust at is a proa. The geothermal steam according to claim 7, characterized in that the exhaust pipe connected to J, Pocket) K is connected to an intermediate stage of a plurality of suction pumps provided in the EI water inlet air gas extraction system! -Bi 7-axis enclosure. Sail Pocket) [Connect the exhaust pipe, *Mizuguchi's air gas extraction system Ezeku 5ca41! The geothermal steam turbine/shaft seal device according to claim 1, characterized in that: t.