JPH01305106A - Turbine gland steam supply device - Google Patents

Abstract

PURPOSE:To make it possible to maintain the temperature of a low pressure gland section optimum by mixing the gland steam whose pressure is regulated by a steam pressure regulator with the steam extracted from a turbine, cooling the mixture, and introducing it to the low temperature gland section. CONSTITUTION:The steam leaked from a turbine 2 to a high pressure gland section 6 is sent to a steam pressure regulator 8 through a conduit tube 7. To the regulator 8 a part of the main steam in a main steam supply tube 1 is also introduced as auxiliary steam through a conduit tube 11. The steam whose pressure has been regulated is introduced to a low pressure gland section 10 through a conduit tube 9 as gland steam, and on the other hand, export steam is discharged to a steam condenser 3 through a pipe 12. In this case, a steam extracting tube 32 is extended from the turbine 2, and the other end is connected to the conduit tube 9 provided downstream the steam pressure regulator 8 through a flow control valve 33. The temperature of gland seal steam is maintained optimum by controlling the opening of the flow control valve 33 according to the output of a temperature detecting section 34.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a turbine gland steam supply device, and more particularly, to a turbine gland steam supply device that can effectively reduce the temperature of the gland steam of a steam turbine. This invention relates to a steam supply device.

(Prior art) Generally, in a steam turbine, in order to maintain the internal pressure of the casing at a pressure different from atmospheric pressure, a shaft seal device is used to prevent steam from flowing out or air from entering into the part where the rotor penetrates the casing. is provided.

Figure 3 is a conventional grand steam system diagram, showing the boiler (
(not shown) is supplied to a turbine 2 via a main steam supply pipe 1, where it performs work. The steam that has done work in the turbine 2 is condensed in a condenser 3, and the condensed water is sent to a grand steam condenser 4. condensate pump 5
The water is then returned to the boiler via a water supply pump (not shown), etc.

By the way, in the high-pressure gland section 6 of the turbine 2, a part of the main steam tends to leak from inside the turbine, and the leaked steam leaked from the inside of the turbine to the high-pressure gland section 6 passes through the conduit 7 to the steam pressure regulator. 8, where the pressure is regulated and then supplied to the low pressure gland section 10 via a conduit 9 as low pressure gland seal steam. Further, a conduit 11 branched from the main steam supply pipe 1 is connected to the steam pressure regulator 8, and in order to compensate for the lack of low pressure gland seal steam led out from the high pressure gland section 6,
A part of the main steam is introduced into the steam pressure regulator 8 as make-up steam, and surplus steam is discarded through the pipe 12 to the condenser 3 or the like.

FIG. 4 is a cross-sectional view showing a schematic configuration of the high-pressure gland section 6, and the high-pressure gland section 6 includes the rotor 1 of the turbine 2.
A shaft sealing device 15 is provided at a portion where the shaft seal 3 penetrates the casing 14. That is, a packing casing 1 is provided on the outer circumference of the rotor 13 so as to surround the rotor 13.
6, and three ring-shaped packings 17a are provided on the inner peripheral part of the packing casing 16, facing the outer peripheral surface of the rotor 13.

! 7b and 17e are mounted spaced apart from each other in the axial direction of the rotor, and annular gland steam chambers 18a and 18b are formed in the packing casing 16, which are divided by mutually adjacent packings. and.

A ground steam chamber 18a on the turbine room side is connected to the steam pressure regulator 8 via the conduit 7, and an outer ground steam chamber 18b is connected to the grand steam condenser 4 via a conduit 19 shown in FIG. has been done. However,
A part of the leaked steam 20 leaking from inside the turbine to the gland steam chamber 18a through the packing 17a flows out through the conduit 7 to the steam pressure regulator 8;
The remaining leaked steam 21 that was not led to the packing 17
The air is introduced into the grand steam chamber 18b through the section b, and is led out to the grand steam condenser 4 together with the air 22 that has flowed in from outside the turbine. In this way, steam inside the turbine is prevented from leaking into the atmosphere, and air from the atmosphere is prevented from flowing into the turbine.

On the other hand, as shown in FIG. 5, the low-pressure gland section also includes a shaft sealing device 45 in the same manner as the high-pressure gland section. Three gaskets 24a, 24b, and 24c are mounted on the inner circumferential surface of the gasket casing 23 facing the rotor 13, spaced apart from each other in the axial direction of the rotor 13, and the inside of the gasket casing 23 is separated by adjacent gaskets. Divided annular gland steam chambers 25a, 25b are formed.

A grand steam chamber 25a located on the turbine chamber side
The steam pressure regulator 8 is connected to the steam pressure regulator 8 via a conduit 9, and the other ground steam chamber 25b is connected to the grand steam condenser 4 via a conduit 26 shown in FIG.

Sealing steam whose pressure has been regulated by the steam pressure regulator 8 is introduced into the grand steam chamber 25a, and a portion of the sealing steam passes through the packing 24a to the condenser 3.
The remaining sealing vapor flows into the gland steam chamber 25b through the packing 24b, and is led out to the gland steam condenser 4 together with the air introduced into the gland steam chamber 25b through the packing 24c. In this way, atmospheric air is prevented from flowing into the turbine along the rotor even in the low-pressure gland section.

(Problems to be Solved by the Invention) By the way, - A small to medium-sized steam turbine used for boat fishing has a main steam pressure of 1100 at, a main steam temperature of 500°C, and a condenser vacuum degree of 7.
Since the temperature is set at about 00 mHg, the temperature of the steam leaking from the high-pressure gland section 6 is about 400°C.

The pressure will be about 2.0 ata. This steam is conducted via conduit 7 to steam pressure regulator 8 as described above where 1.
5 ata and is supplied to the low pressure gland section 10 via the conduit 9. However, between the high pressure gland section 6 and the low pressure gland section 10, the sealing steam only undergoes an enthalpy change. The seal steam temperature at 10 will be approximately 400°C. Therefore, the ambient temperature of the grand steam chamber 25a is approximately 400°C.

On the other hand, when the condenser vacuum degree is set to about 700 maHg, the ambient temperature of the final stage wheel 27 is about 100°C, so the rotor 13 has a high temperature region and a low temperature region adjacent to each other near the low pressure gland. I will do it. Therefore, this distribution causes problems such as thermal stress and unfavorable conditions in the rotor 13 such as differential expansion.Moreover, heat recovery of the steam flowing through the conduit 7 is not performed, resulting in loss in terms of thermal cycles. There are problems such as.

In particular, when the turbine plant is under partial load, the leakage steam from the high-pressure gland is insufficient for low-pressure gland seal steam, so main steam is used as make-up steam via conduit 11 as described above. As a result, the ambient temperature in the low-pressure gland section was approximately 450°C,
Further problems arise in terms of the rotor 13 and its thermal cycle.

Conventionally, in large turbines, a method has been adopted in which the conduit downstream of the steam pressure regulator is routed into the condenser, and the low-pressure gland seal steam is cooled by the turbine exhaust steam to obtain a steam temperature of approximately 150°C. However, although this method has favorable effects in terms of the rotor's financial strength, thermal stress, and differential elongation, it takes up the effective cooling area of the conduit in the condenser. There were many requests for transportation.

Turbines with small condensers, such as small and medium-sized turbines, have problems in terms of space, and also have disadvantages such as restricting the flow path of turbine exhaust steam and increasing exhaust loss.

It has also been proposed to install a water injection device near the outside of the gland steam conduit and adjust the gland steam temperature using water injected by a water injection valve, but this also means that condensers such as small and medium-sized turbines are small. This poses a problem in terms of space for turbines.

Furthermore, a feed water heater is installed on the downstream side of the condensate pump.
It has also been proposed to adjust the high-temperature gland steam by exchanging heat between the gland steam from the steam pressure regulator and the feed water to the boiler, but this poses the problem of requiring the equipment cost of installing a feed water heater.

In view of these points, the present invention has been proposed to solve the following problems in terms of the structure of the steam turbine:
The object of the present invention is to obtain a turbine gland steam supply device that can supply gland steam at an optimal temperature during operation.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a steam pressure regulator that adjusts the steam pressure by mixing steam flowing out from a high-pressure gland part of a steam turbine with steam supplied from a boiler, and a steam pressure regulator that adjusts the steam pressure This turbine gland steam supply device includes a conduit that sends steam sent from a regulator to a low-pressure gland section of a steam turbine, and an extraction pipe that sends steam extracted from the steam turbine to the middle of the conduit.

(Operation) The steam that has passed through the steam pressure regulator is mixed with the steam extracted from the turbine, and the temperature of the sealing steam can be controlled to be optimal from the viewpoints of the financial strength, thermal stress, differential expansion, etc. of the rotor.

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

FIG. 1 shows an embodiment of the turbine gland steam supply system of the present invention, in which leak steam in the high-pressure gland section 6 of the turbine 2 is introduced into a steam pressure regulator 8 via a conduit 7. On the other hand, a portion of the main steam is also supplied to the steam pressure regulator 8 through a conduit 11 as makeup steam for the sealing steam.

Incidentally, an extraction pipe 32 is provided from the turbine 2 via a flow rate control valve 33, and is connected to a conduit 9 downstream of the steam pressure regulator 8.

The steam passing through the upstream extraction tube 32 and the ground steam are mixed. Here, the extraction location of the turbine 2 is selected so that the steam passing through the extraction pipe 32 has a lower temperature and a higher pressure than the steam passing through the steam pressure regulator 8. Since the steam temperature passing through the conduit 9 is lower, the temperature of the steam passing through the conduit 9 is lower after connecting with the extraction pipe 32. Also, since the steam pressure passing through the extraction pipe 32 is higher, the steam passing through the conduit 9 has a lower temperature. However, the steam flows back into the extraction pipe 32 and does not flow into the turbine 2.

Next, the steam passing through the conduit 9 after being connected to the extraction pipe 32 passes through the temperature detection section 34, where the temperature is detected and the signal 35 thereof is fed back to the flow control valve 33. The opening degree of the flow control valve 33 is controlled by the signal 35, and the temperature of the gland steam after mixing with the extraction pipe 32 is controlled to the optimum temperature as sealing steam, and then the gland steam is supplied to the low pressure gland section 10 of the turbine.

Note that other points are the same as the conventional one shown in FIG.

Therefore, the steam leaking into the high pressure gland section 6 is transferred to the conduit 7.
The steam is then introduced into the steam pressure regulator 8, where it is adjusted to a predetermined pressure together with the main steam led through the conduit 11.

Steam from the steam pressure regulator 8 is mixed with extracted steam from the turbine 2 through an extraction pipe 32 and a flow control valve 33. At this time, the temperature is reduced to a predetermined temperature by controlling the opening degree of the flow rate regulating valve 33 based on signal feedback issued from the temperature detection section 34. The obtained mixed vapor is fed to the low pressure gland section 10.

Here, the ground steam flow rate in the conduit 9 before mixing the steam from the extraction pipe 32 is 61, and its enthalpy is h□
The flow rate of extracted steam in the extraction pipe 32 is G2, its enthalpy is
Assuming that the flow rate of sealing steam sent to O is G1 and the enthalpy is G, the flow rate balance and energy balance are as shown in the following equation.

G, +G, =G3...
■G1・hyu+G2・h2=G,・h, ・・・・
... From formulas ■■ and ■, for example, main steam pressure 1100at, main steam temperature 500℃
For 50 MV class turbines, each numerical value is generally about the following.

G, = 2000 (kg/hr) h1 = 800 (kcaQ/kg) h, = 650 (kcal!/kg) hz = 710
(k can/kg) If these values are substituted into the formula 0, we get G2=3000 ()cg/hr), and the seal steam pressure sent to the low pressure gland is about 1.1 (kg/c11a) Therefore, the enthalpy h3 = 710 (k caQ / kg) becomes about 250°C, and at this temperature, the low pressure gland section IO has a good supply temperature for the financial strength, thermal stress, expansion difference, etc. of the rotor 13. Become.

Also, the flow rate passing through the flow rate control valve 33 is 3000 (kg/kg/kg).
hr), the capacity of the flow control valve is not large, and the equipment cost is not large.

Since the above example is intended for a turbine in which the condenser vacuum degree is set to about 700ml/g, the gland steam to the low pressure gland section is set to be about 250℃, but the condensate Turbines with low vessel vacuum and high ambient temperature of the final stage wheel, or turbines that require a high ground steam temperature to the low-pressure gland for other reasons, or low-pressure glands that require a high temperature setting due to the load of the turbine plant. If the target is a turbine that requires temperature control, the structure shown in FIG. 2 may be used.

That is, a plurality of extraction points from the turbine 2 are provided, flow control valves 33a and 33b are arranged in the extraction pipes 32a and 32b, and these extraction pipes 32a and 32b are connected to a conduit 9 downstream of the steam pressure regulator 8. The rest is the same as the first embodiment shown in FIG.

〔Effect of the invention〕

As explained above, in one aspect of the present invention, ground steam whose pressure has been adjusted by a steam pressure regulator is mixed with extracted steam from inside the turbine to lower the temperature.

Since it is led to the low-pressure gland, the low-pressure gland can be set at an optimum temperature, which provides structural and operational advantages in terms of rotor material strength, thermal stress, differential elongation, etc. Moreover, if the extraction steam pipes from inside the turbine are extracted from a plurality of locations, it becomes easier to control the optimum temperature of the low-pressure gland section.

[Brief Description of the Drawings] Fig. 1 is a system diagram showing one embodiment of the grand steam system of the turbine gland steam supply device of the present invention, Fig. 2 is a system diagram showing another embodiment of the present invention, and Fig. The figure is a conventional gland steam system diagram, and FIGS. 4 and 5 are partial cross-sectional views of a high-pressure gland section and a low-pressure gland section. 1... Main steam supply pipe 2... Turbine 3...
Condenser 4...Gland steam condenser 5...Condensate pump 6...High pressure gland section 7
．． 9, 11, 19.26... Conduit 8... Steam pressure regulator 10... Low pressure gland part 12... Piping 13... Rotor 14... Casing 1
5.45... Shaft seal device 16.23... Packing casing 17a, 17b, 17c, 24a, 24b, 24cm Packing 18a, 18b, 25a, 25b - Grand steam chamber 20.21... Leak steam 22.・Air 27
...Final stage wheel 32...Extraction pipe 33...
Flow control valve 34...Temperature detection unit 35...Signal agent Patent attorney Nori Ken Yudo Chika Kendai Daishimaru 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) A steam pressure regulator that adjusts the steam pressure by mixing steam flowing out from the high-pressure gland section of the steam turbine with steam supplied from the boiler, and a steam pressure regulator that adjusts the steam pressure by mixing the steam flowing out from the high-pressure gland section of the steam turbine with the steam supplied from the boiler, and the steam pressure regulator that adjusts the steam pressure by mixing the steam flowing out from the high-pressure gland part of the steam turbine with the steam supplied from the boiler. A turbine gland steam supply device comprising: a conduit for sending steam to a gland; and an extraction pipe for sending steam extracted from a steam turbine to the middle of the conduit. (2) A temperature detection section is disposed downstream of the confluence of the conduit with the extraction pipe, and a flow rate control valve is disposed in the middle of the extraction pipe, so that the output of the temperature detection section is 2. The turbine gland steam supply system according to claim 1, further comprising means for controlling the flow control valve so that the flow rate is within a predetermined width.