JPH04132802A - Shaft sealing method of double-flow evacuating geothermal steam turbine and device thereof - Google Patents

Abstract

PURPOSE:To reduce the construction cost as well as to save time and labor for operation and maintenance by supplying the shaft sealing steam of specified pressure a little lower than atmospheric pressure to the middle of a gland part being installed in a part where a turbine rotor pierces through a casing. CONSTITUTION:A pressure control valve 20 is controlled by an output signal out of a controller 22 from a deviation between detection pressure in a shaft sealing steam pipe 18 detected by a steam pressure detector 21 and the desired value and thereby a pressure of shaft sealing steam in the shaft sealing steam pipe 18 is set down to the specified pressure. The shaft sealing steam of this specified pressure is fed to each mid part of both gland parts 4, 4a, flowing into two evacuation parts 12, 12a by way of these gland parts 4, 4a, and then it flows into a condenser 11. On the other hand, from the atmospheric side of the gland parts 4, 4a, the shaft sealing steam to be supplied is of negative pressure, so that air is inhaled and it is flows into the evacuation parts 12, 12a together with the said shaft sealing steam, thus it flows in the condenser 11. Doing like this, cost is reduced and, what is more, time and labor for operation and maintenance is savable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a two-stream exhaust geothermal steam turbine in which geothermal steam is supplied to the turbine and its exhaust gas is led to a direct contact condenser, in which the rotor penetrates the casing. The present invention relates to a shaft sealing method and apparatus for a gland section provided in a part where the ground section is installed.

[Conventional technology]

In a steam turbine equipped with a condenser, the exhaust gas that has undergone expansion work in the blade stages is led to the condenser and becomes condensate, and the exhaust section becomes a vacuum, so the rotor penetrates the casing. A shaft sealing device supplies shaft sealing steam to the provided gland to prevent air from being sucked in. As a steam turbine equipped with such a shaft sealing device, there is known a two-stream exhaust geothermal steam turbine equipped with a direct contact condenser shown in FIG. 2 and driven by geothermal steam.

In FIG. 2, the rotor 1 includes moving blades (not shown), and the internal casing 2 surrounds the rotor 1 with stationary blades (not shown) forming blade stages on two sides of the moving blades of the rotor 1.

The outer casing 3 surrounds the inner casing 2 and the rotor 1
Gland portions 4, 4a made of labyrinth packings are provided on both sides of the casing 3 where the casing 3 is penetrated.

The rotor 1 is supported by parallel bearings 5, 5a.

The generator 7 is connected to the rotor 1 via a camp ring.

A steam supply pipe 10 is provided connected to the steam port 9 in the center of the internal casing 2, and the steam that flows into the internal casing 2 from the steam port 9 via the steam supply pipe 10 is divided into two directions and flows through the blade stages. .

A direct contact type condenser 11 is connected to the outer casing 3 and expands the blade stages in two directions to perform exhaust part 12.
The steam exhausted from 12a is brought into contact with cooling water supplied from the outside to be cooled and condensed to form condensate. Note that the air extractor 13 extracts non-condensable gas contained in geothermal steam and cooling water to maintain a vacuum in the condenser. The condensate pump 14 sends mixed water of condensate and cooling water that remains in the lower part of the condenser 11 to the outside through a condensate supply pipe 15 .

The shaft-sealed steam pipework 8 is connected to the central part of the gland portion 4.4a, and a shaft-sealed steam supply pipe 19 is provided which is connected to this shaft-sealed steam pipe 18 and supplies shaft-sealed air. Shaft seal air supply pipe H
A pressure control valve 20 is installed in the shaft-sealed steam pipe 1.
8 is provided with a steam pressure detector 21 for detecting the internal steam pressure.

The pressure detected by the steam pressure detector 21 is input to the pressure regulator 22, and the pressure control valve 20 is controlled based on the deviation between the target value of a predetermined pressure slightly higher than atmospheric pressure and the pressure detected by the steam pressure detector 21.

Gland portions 4, 4a between the atmosphere side of the gland portions 4, 4a and the connection point to the ground portions 4, 4a of the shaft-sealed steam pipe on the 1st day.
A ground steam pipe 24 is connected to the ground steam pipe 24 .

The grand steam pipe 24 is connected to a grand steam condenser 25, and the steam that has flowed into the grand steam condenser 25 through the grand steam pipe 24 is condensed, and the exhaust air 112 is
6, the non-condensable gas in the gland steam condenser 25 is discharged to make the interior of the gland steam condenser a negative pressure slightly lower than atmospheric pressure.

With this configuration, when geothermal steam flows into the inner casing 2 from the steam supply pipe 10 through the steam supply pipe 10, the geothermal steam flows in two directions, performs expansion work in the blade stages, and rotates the rotor 1. The generator 7 generates electric power to overcome this power. At this time, the geothermal steam that has worked in the blade stage is led from the exhaust section 12.12a to the direct contact type condenser 11, contacts cooling water supplied from the outside, cools and condenses, and becomes condensate. By driving the air extractor 13, non-condensable gas is extracted and maintained in a vacuum.

Therefore, since the exhaust section 12.12a becomes a vacuum, the shaft-sealed steam is supplied to the shaft-sealed steam pipe 18 via the shaft-sealed steam supply pipe 19 to prevent air from being sucked into the glands 4, 4a. 4, 4a to a predetermined pressure slightly higher than atmospheric pressure, for example, about +0.07 kg/-, the predetermined pressure is controlled by inputting the pressure detected by the steam pressure detector 21 to the pressure regulator 22, The pressure control valve 20 is controlled by an output signal output from the pressure regulator 22 based on the deviation between the detected pressure and the target value of the predetermined pressure.

In addition, the shaft-sealed steam supplied to the gland parts 4 and 4a from the shaft-sealed steam pipe 1st flows through the gland and 4a towards the exhaust part 12. flows. The steam flowing toward the bearing stand 6.6a side is connected to the gland section 4.
．． If the lubricating oil is discharged from 4a and flows into the bearings 5, 5a, the lubricating oil will deteriorate, so in order to prevent this, the steam flowing through the glands 4, 4a toward the bearing stands 6, 6a is diverted from the steam inside the gland steam pipe 24. By setting the steam pressure to a pressure slightly lower than atmospheric pressure, for example, about -0,003 kg/j, air is drawn from the atmospheric side of the gland sections 4, 4a and guided to the gland steam condenser 25. As a result, steam from the gland portions 4, 4a does not flow into the bearings 5, 5a, so deterioration of the lubricating oil is prevented.

[Problem to be solved by the invention]

As mentioned above, the shaft sealing steam is supplied and the shaft sealing steam flowing through the gland toward the bearing side is guided to the gland steam condenser which is maintained at a pressure slightly lower than atmospheric pressure, and the shaft sealing steam flows toward the bearing. The method of preventing the water from flowing in requires equipment such as a gland steam pipe, a gland steam condenser, and an exhaust fan, which has the disadvantage of increasing costs and requiring time and effort for operation and maintenance.

The purpose of the present invention is to provide a two-stream exhaust geothermal system with a direct contact condenser that is low in cost and requires less operation and maintenance.
An object of the present invention is to provide a shaft sealing method and apparatus for an air turbine.

[Means to solve the problem]

In order to solve the above problems, according to the present invention, geothermal steam flowing in from the steam inlet of the casing surrounding the turbine rotor is divided into two directions, performs expansion work in the blade stages, and is then discharged from the exhaust ports on both sides as cooling water. The shaft of a two-flow exhaust geothermal steam turbine is sealed by supplying steam to the glands provided on both sides where the turbine rotor of the steam turbine passes through the casing. In the sealing method, shaft sealing steam at a predetermined pressure slightly lower than atmospheric pressure is supplied to the central part of the gland section.

In addition, as a shaft sealing device for shaft sealing the gland section of the above-mentioned two-stream exhaust geothermal fume turbine, there is also a shaft sealing steam pipe that supplies shaft sealing steam to the middle part of the gland section, and a shaft sealing steam pipe that is connected to this steam pipe and supplies shaft sealing steam to the outside. a shaft-sealed steam supply pipe, a pressure control valve provided in the steam supply pipe, and a control means for controlling the pressure control valve so that the steam pressure in the shaft-sealed steam pipe becomes a predetermined pressure slightly lower than atmospheric pressure. It shall consist of:

[Effect]

The shaft-sealed steam is controlled to a predetermined pressure slightly lower than atmospheric pressure by a pressure control valve installed in the shaft-sealed steam supply pipe in the middle of the gland section on both sides where the turbine rotor penetrates the casing. By supplying
The shaft-sealing steam flows from the middle of the gland to the exhaust section, sucks air from the atmosphere side of the gland, passes through the gland, and flows to the exhaust section. As a result, the shaft seals the gland, and steam flows to the atmosphere side of the gland. Since no steam is discharged, the lubricating oil does not deteriorate due to steam entering the bearing.

By the way, geothermal steam contains a large amount of non-condensable gas, and on the other hand, the cooling water that is supplied to the condenser, which is converted into condensation by contact with the cooling water, is also degassed within the condenser, so these non-condensable gases are The total amount of condensed gas is large, for example, 2 to 3 tons/11 in a 50 MW class turbine facility. In this case, as mentioned above, the pressure of the shaft sealing steam supplied to the gland section is set to a pressure slightly lower than atmospheric pressure, for example, about -0,001 kg/
When set to -, the amount of air sucked in from the atmosphere side of the ground section is about 0.1 ton/h. Therefore, even if this amount of air is added to the 2 to 3 tons/h of non-condensable gas, there is almost no need to increase the capacity of the air extractor.

Furthermore, since the shaft sealing steam does not flow from the gland toward the bearing, equipment such as a gland steam condenser, gland steam piping, and exhaust fan are not required.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a system configuration diagram of a two-stream exhaust geothermal steam turbine equipped with a shaft sealing device according to an embodiment of the present invention. In FIG. 1, parts that are the same as those in the conventional example shown in FIG. 2 are given the same reference numerals, and their explanations will be omitted. In FIG. 1, the gland steam pipe 24 in FIG. 2 of the conventional example. Grand steam condenser 25
．． The structure is the same as the conventional example except that the exhaust fan 26 and the like are removed and the shaft-sealed steam pipe is connected to the middle part of the ground portions 4 and 4a.

In FIG. 1, the pressure of the shaft-sealed steam in the shaft-sealed steam pipe 18 is set to a predetermined pressure slightly lower than atmospheric pressure, for example, about -0,001 kg.
/ aj. That is, the pressure control valve 2o is controlled by the output signal from the regulator 22 based on the deviation between the detected pressure in the shaft-sealed steam pipe 18 detected by the steam pressure detector 21 and the target value of the predetermined pressure. The pressure of the shaft-sealing steam is set to the specified pressure. This shaft sealing steam at a predetermined pressure is supplied to the central part of the gland parts 4, 4a, and the gland part 4
, 4a, flows into the vacuum exhaust section 12.degree. 12a, and flows into the condenser 11. On the other hand, from the atmosphere side of the gland portions 4, 4a, air is sucked into the shaft sealing steam supplied from the atmosphere side due to the negative pressure, and it flows into the exhaust portion 12.12a together with the shaft sealing steam through the gland portion 4.4a, and is recovered. It flows into the water container 11.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to supply shaft sealing steam at a predetermined pressure slightly lower than atmospheric pressure to the central part of the gland section provided in the part where the turbine rotor penetrates the casing, and to do this. The equipment includes a shaft-sealed steam pipe connected to the central part of the gland section, a pressure control valve that controls the pressure of the shaft-sealed steam in this shaft-sealed steam pipe to a predetermined pressure slightly lower than atmospheric pressure, and a control means for controlling this. As a result, while air is sucked into the gland from the atmosphere side of the gland, the shaft sealing steam flows through the gland to the exhaust section and seals the shaft.
There is no need for an exhaust fan, gland steam condensate piping, etc., which has the effect of reducing construction costs and saving time and effort in operation and maintenance.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of a two-stream exhaust geothermal steam turbine equipped with a shaft sealing device according to an embodiment of the present invention, and FIG. 2 is a system configuration diagram of a two-stream exhaust geothermal steam turbine equipped with a conventional shaft sealing device. 1: Rotor, 2: Internal casing, 3: External casing, 4, 4a Nigerland section, 11: Condenser, 18 twin-shaft sealed steam pipe, 20: Pressure control valve, 21: Steam pressure detector, 22
: Regulator.

Claims (1)

[Claims] 1) Geothermal steam that flows in from the steam inlet of the casing surrounding the turbine rotor is divided into two directions and expands in the blade stages, and then condenses from the exhaust ports on both sides by contact with cooling water. In a shaft sealing method for a two-flow exhaust geothermal steam turbine, the shaft sealing method for a two-flow exhaust geothermal steam turbine supplies shaft sealing steam to the gland sections provided on both sides where the turbine rotor of a steam turbine guided to a condenser passes through the casing. A shaft sealing method for a two-stream exhaust geothermal steam turbine, characterized by supplying shaft sealing steam at a predetermined pressure slightly lower than atmospheric pressure to the central part of the turbine. 2) Geothermal steam that flows in from the steam inlet of the casing surrounding the turbine rotor is split into two directions, expanded in the blade stages, and then led from the exhaust ports on both sides to the condenser where it is condensed by contact with cooling water. In a shaft sealing device for a two-flow exhaust geothermal steam turbine, the shaft sealing device supplies shaft sealing steam to the gland sections provided on both sides of the steam turbine where the turbine rotor passes through the casing, thereby sealing the shaft. A shaft-sealed steam pipe to be supplied, a shaft-sealed steam supply pipe connected to this steam pipe and which supplies shaft-sealed steam from the outside, a pressure control valve provided in this steam supply pipe, and a steam pressure inside the shaft-sealed steam pipe. 1. A shaft sealing device for a two-stream exhaust geothermal steam turbine, comprising: a control means for controlling a pressure control valve to maintain a predetermined pressure slightly lower than atmospheric pressure.