JPH0932512A - Steam supply device of steam turbine gland seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce surplus steam generated at high load operation time, and enhance heat efficiency by setting a leakage steam quantity from a turbine gland seal lower than a necessary gland sealing steam quantity, and supplying auxiliary steam to an auxiliary steam header over the whole operation areas from a gland steam pressure control valve. SOLUTION: The sum of a supply quantity of leakage steam from turbine gland sealing parts 74, 76, 78 and 80 and a supply quantity of auxiliary steam of an auxiliary steam header 72 is controlled so as to become a necessary steam quantity of the turbine glad sealing parts 74, 76, 78 and 80. A leakage steam quantity from the turbine gland sealing parts 74, 76, 78 and 80 is set lower than a necessary gland sealing steam quantity, and auxiliary steam is supplied to the auxiliary steam header 72 over the whole operation areas from a gland steam pressure control valve 70. Therefore, a surplus steam quantity generated at high load operation time is eliminated, and heat efficiency of the whole can be improved according to reduction in steam abandoned to a condenser.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined power generation comprising an exhaust heat recovery boiler for generating steam using exhaust gas from a gas turbine as a heat source, and a steam turbine driven by the steam generated by the exhaust heat recovery boiler. The present invention relates to a steam turbine gland seal steam supply device applied to a plant.

[0002]

2. Description of the Related Art Conventionally, a reheat triple pressure type combined cycle power plant is known in which three kinds of steam pressure systems (high pressure, medium pressure and low pressure) are provided to improve thermal efficiency and a reheat cycle is adopted. , Hitachi Review, 1992, Vol. 74, pages 9-14.

FIG. 2 is a diagram showing the structure of a conventional apparatus. The high-pressure drum 14 of the exhaust heat recovery boiler plant 12, which uses exhaust gas such as a gas turbine as a heat source, is a saturated steam 1 during normal operation.
6 is generated. The saturated steam 16 is superheated by the high-pressure superheater 18, and as the superheated steam 20, the high-pressure main steam control valve 22.
And is supplied to the high-pressure steam turbine 24.

The steam that has driven the high-pressure steam turbine 24 is
It is discharged through the low temperature reheat steam pipe 26. Saturated steam 30 generated in the medium-pressure drum 28 of the exhaust heat recovery boiler plant 12
Is superheated in the medium pressure superheater 34 to become superheated steam 36,
It merges with the cold reheat steam pipe 26 via the valve 38. The combined steam is reheated by the reheater 40, and the superheated steam 4
2 and is supplied to the intermediate pressure steam turbine 46 via the reheat steam control valve 44.

Further, the saturated steam 52 generated in the low pressure drum 50 of the exhaust heat recovery boiler plant 12 is superheated in the low pressure superheater 54 to become superheated steam 56, and then the low pressure main steam control valve 58 and the low pressure main steam pipe. It is supplied to the low-pressure steam turbine 62 via 60. A turbine unit composed of high-pressure, medium-pressure, and low-pressure steam turbines 24, 46, 62 connected to the same shaft and a generator 64 driven by them converts steam energy into electric energy. Although not shown, a plurality of similar turbine units (a plurality of shafts) are provided side by side.

A part of the extracted steam 65 extracted from the low-temperature reheat steam pipe 26 passes through the auxiliary steam supply pressure control valve 66 and the desuperheater 68, and is decompressed / reduced to the required steam condition of the steam turbine gland seal. After being heated, it is supplied to the intermediate portion of the steam turbine gland packing parts 74, 76, 78, 80 of the turbines 24, 46, 62 via the steam turbine gland steam pressure control valve 70 and the auxiliary steam header 72, as will be described later. To seal the inside of the turbine and the outside air.

For example, the auxiliary steam supply pressure control valve 66 is controlled to keep the output side pressure at 7 atg, and the gland steam pressure control valve 70 controls the steam pressure of the auxiliary steam header 72 to 1 atg.
Controlled to keep on. As is well known, the turbine gland seal is a device for suppressing the outflow of steam from the turbine gland packing during start-up, stop, and operation, and for preventing air from entering the turbine.

At the time of stopping and starting, the load on the turbine is small, and the leaked steam from the high-pressure turbine 24 is also small. Therefore, as shown in FIG. 3, all the steam necessary for the gland seal is supplied from the auxiliary steam header 72, and part of the steam supplied to the middle part of the gland packing reaches the outermost packing part, which is not shown. It is discharged to the condenser 85 together with the air sucked from the outside. This prevents the ground leak steam from leaking to the outside and fulfills the sealing function.

On the other hand, when the load increases, the amount of leaked steam 81 from the high pressure turbine gland packing increases, and a part of the leaked steam 81 passes through the high pressure turbine gland seal portion and the auxiliary steam header 72.
The surplus steam flows into the low pressure turbine 62 through the steam pipe 82 and flows into the auxiliary steam header 72 through the high pressure turbine ground leak steam supply line 83.

The gland steam pressure control valve 70 is controlled so as to decrease the amount of steam supplied from the auxiliary steam side as the amount of leaked steam from the turbine gland packing increases, and keeps the pressure inside the auxiliary steam header 72 constant. . In a condensing turbine, the exhaust pressure is close to vacuum, so in order to prevent outside air from flowing into the turbine from the gland packing part, the pressure in the middle part of the gland packing part is slightly higher than atmospheric pressure. The seal steam of is enclosed. For this reason, one steam header 72 connected to all packing lands is provided, and steam is supplied from the outside when the turbine is under low load operation, and the steam flowing out from the gland packing is under high load. Collected in the steam header 72.

The seal steam pressure of the gland packing in each operating state is controlled by controlling the gland steam supply valve 70 and the gland steam exhaust valve 84 to thereby control the steam header 7
The pressure in ² is maintained at a target value set in all operating conditions, for example, 1 atg (kg / cm ² -g).

However, since the amount of steam flowing out from the packing land of the high-pressure turbine 24 is small at the time of starting the turbine, the gland seal steam is supplied from the gland steam supply system via the gland steam pressure control valve 70. When the turbine load reaches a certain ratio, the steam flowing out from the gland packing of the high-pressure turbine causes excess seal steam in the steam header 72, and the surplus steam is discharged from the steam header 72 via the gland steam exhaust valve 84 to the condenser. It is discharged to 85 and the pressure in the steam header 72 is kept constant. The turbine unit configured as above is the auxiliary steam mother pipe 86.
A plurality of units (the number of axes) are connected via a valve 87 connected to. In the figure, 6 turbine units can be connected.

FIG. 6 is a block diagram showing the control method of each valve in the conventional apparatus. The auxiliary steam supply pressure control valve 66 is
Detects the pressure of the auxiliary steam mother pipe 86 arranged on the output side,
Normally, when the pressure is lower than a predetermined value, for example, 7 atg, the small valve 662 of the auxiliary steam pressure control valve 66 is opened to supply the auxiliary steam to the turbine gland packing part. Also, when it is necessary to supply a large amount of auxiliary steam, such as when starting a steam turbine unit of another operating axis that is connected via the auxiliary steam mother pipe 86 and the valve 87, the auxiliary steam supply pressure The large valve 664 of the control valve 66 is opened and supplied.

On the other hand, in order to keep the pressure of the gland seal steam header 72 at a constant pressure, for example, 1 atg (or within a certain pressure range), the pressure of the gland seal steam header 72 is detected, and when it is lower than a predetermined value, for example, 1 atg, the gland steam The pressure control valve 70 is opened and the gland steam exhaust valve 84 is closed. On the other hand, when the pressure is higher than the predetermined pressure, the gland steam exhaust valve 84 is opened and the gland steam pressure control valve 70 is closed.

In such an apparatus, the steam pressure on the downstream side of the auxiliary steam supply pressure adjusting valve 66 changes depending on the opening degree of the gland steam pressure adjusting valve 70. For example, when the flow rate of the gland steam pressure control valve 70 is reduced, the upstream pressure of the valve, that is, the pressure of the auxiliary steam mother pipe 86 increases. On the other hand, since both pressure adjusting valves 66 and 70 are controlled so that the pressure on the output side becomes constant, the opening degree of the auxiliary steam supply pressure adjusting valve 66 is eventually increased until the flow rate of the gland steam pressure adjusting valve 70 is balanced. Squeezed.

For example, assuming that the minimum flow rate of the control valve 70 is 0.4 t / h, the minimum flow rate of the control valve 66 must be reduced to 0.4 t / h when activating a single-shaft turbine unit. On the other hand, assuming that the maximum flow rate of the control valve 70 of the 1-axis turbine unit is 40 t / h, the flow rate to be controlled by the control valve 66 is 40X6 = 240 when the 6-axis turbine unit is started at the same time.
Reach t / h. Therefore, the control flow rate range of the regulating valve 66 reaches 600 (= 240 / o.4) when the minimum flow rate is 1, and it is difficult to control with a single valve. Therefore, conventionally, two control valves 662, 66 are used as the auxiliary steam supply pressure control valve 66.
4 was used.

[0017]

In the conventional configuration shown in FIG. 6, the excess or deficiency of steam occurs with respect to the required steam header pressure due to load fluctuations (from startup to rated load). Especially during high-load operation, excess steam is always collected in the condenser 8
It will be discharged to No. 5, which will be a factor of lowering the thermal efficiency.
Therefore, an object of the present invention is to reduce surplus steam generated during high load operation and improve thermal efficiency.

Further, in the conventional apparatus, since the auxiliary steam supply pressure adjusting valve 66 has a wide control range as described above, it is necessary to use two adjusting valves. Therefore,
A second object of the present invention is to narrow the control range of the control valve.

[0019]

As shown in FIG. 4, if the amount of leaked steam from the turbine gland is small and the amount of supply from the auxiliary steam side can be increased with respect to the required pressure of the gland seal steam header 72, a high load can be achieved. It is possible to operate without generating surplus steam even during operation.

Therefore, the present invention eliminates the system connecting the high-pressure turbine gland part to the gland seal steam header 72, and creates a situation in which the gland seal steam header 72 always lacks the seal steam, resulting in a result. The amount of steam supplied from the auxiliary steam side is increasing. The amount of leak steam supplied from the turbine ground leak and the sum of the amount supplied from the auxiliary steam side are controlled to be the required steam amount of the gland seal, and the amount of leak steam from the turbine ground leak is set to the required ground. The amount of sealing steam is set lower than the amount of sealing steam, and auxiliary steam is supplied from the auxiliary steam supply device to the auxiliary steam header over the entire operating region.

That is, the object of the present invention is achieved by changing the distribution of the supply amount from the auxiliary steam side and the supply amount from the ground leak with respect to the required pressure of the gland seal steam header 72. Further, the excess ground leak steam during the high load operation merges with the low pressure main steam pipe 60 and works in the low pressure turbine 62, which contributes to the improvement of thermal efficiency.

[0022]

In the present invention, the line for supplying the leak steam from the high-pressure turbine gland to the seal steam header is deleted so that the auxiliary steam can always be supplied to create a situation in which the seal steam is always insufficient. As a result, the supply amount from the auxiliary steam side is increased. Therefore, steam of a predetermined value or more is always supplied from the auxiliary steam header.

Further, in the present invention, since it is possible to increase the minimum control flow rate of the gland steam pressure control valve 70, the flow control range of the auxiliary steam supply pressure control valve 66 can be reduced, and therefore the control valve can be reduced. It becomes possible to be one.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to an embodiment shown in the drawings. In FIG. 1, the high-pressure drum 14 of the exhaust heat recovery boiler plant 12, which uses exhaust gas such as the gas turbine 1 as a heat source, generates saturated steam 16 during normal operation. The saturated steam 16 is superheated by the high pressure superheater 18, and is supplied to the high pressure steam turbine 24 as the superheated steam 20 via the high pressure main steam control valve 22.

The steam that has driven the high-pressure steam turbine 24 is
It is discharged through the low temperature reheat steam pipe 26. Saturated steam 30 generated in the medium-pressure drum 28 of the exhaust heat recovery boiler plant 12
Is superheated in the medium pressure superheater 34 to become superheated steam 36,
It merges with the cold reheat steam pipe 26 via the valve 38. The combined steam is reheated by the reheater 40, and the superheated steam 4
2 and is supplied to the intermediate pressure steam turbine 46 via the reheat steam control valve 44.

The saturated steam 52 generated in the low-pressure drum 50 of the exhaust heat recovery boiler plant 12 is superheated in the low-pressure superheater 54 to become superheated steam 56, and then the low-pressure main steam control valve 58 and the low-pressure main steam pipe. It is supplied to the low-pressure steam turbine 62 via 60. A turbine unit composed of high-pressure, medium-pressure and low-pressure steam turbines 24, 46, 62 connected to the same shaft and a generator 64 driven by them converts steam energy into electric energy. Although not shown, a plurality of similar turbine units (number of shafts) are provided side by side.

Steam 6 extracted from the low-temperature reheat steam pipe 26
A part of 5 is an auxiliary steam supply pressure control valve 66 and a desuperheater 68.
After the pressure is reduced and reduced to the required steam condition of the steam turbine gland seal via the steam turbine gland seal, the steam turbine gland 74 of each turbine 24, 46, 62 is passed through the steam turbine gland steam pressure control valve 70 and the auxiliary steam header 72. , 7
It is supplied to the middle of 6, 78, 80 and seals the inside of the turbine and the outside air. For example, the pressures on the output side of the pressure reducing valve 66 and the pressure control valve 70 are set to 7 atg and 1 atg, respectively.

At the time of stopping and starting, the load on the turbine is small, and the leaked steam from the high-pressure turbine 24 is also small. Therefore, as shown in FIG. 4, all the steam necessary for the gland seal is supplied from the auxiliary steam header 72, and the steam supplied to the gland performs a flow sealing function in a direction in which it partially flows into the atmosphere. On the other hand, when the load increases, the amount of steam leaked from the high-pressure turbine gland increases, and part of the steam flows into the auxiliary steam header 72 through the high-pressure turbine gland seal portion. Through low pressure turbine 62. In order to keep the pressure in the auxiliary steam header 72 constant, the gland steam pressure control valve 70
Controls the amount of steam supplied from the auxiliary steam side as the amount of leaked steam from the turbine ground increases.

In the present invention, the steam leaked from the gland portion of the high-pressure turbine 24 is not returned to the gland seal steam header 72 unlike the conventional apparatus, is joined with the low-pressure main steam pipe 60, and is supplied to the low-pressure turbine 62. . This allows the low-pressure turbine 62 to recover the energy of the steam that has been surplus during the high-load operation and has been discharged, and improve the thermal efficiency. The pressure of the leaked steam 81 from the high-pressure turbine is about 3 atg, which is sufficient to drive the low-pressure turbine.

As shown in FIG. 3, in the conventional device,
Leakage steam from the high-pressure turbine 24 is supplied to the auxiliary steam header 7
Since it has been returned to 2, the leak steam from the turbine ground rapidly increases and the supply amount from the auxiliary steam side decreases as the operating load of the high-pressure turbine 24 increases. Then, at about ½ load, all the necessary gland seal steam amount is covered by the leak steam from the high-pressure turbine gland, and the supply from the auxiliary steam side becomes zero.

In this state, a larger amount of steam than that required for the gland seal leaks from the turbine gland, flows into the header 72, and supplies an amount of steam that maintains the pressure in the header at a predetermined pressure or higher. Therefore, since the auxiliary steam supply pressure control valve 24 needs the flow rate control capability up to near zero, its control range is wide, and the large and small two valves 662, 6 are provided.
The control by 64 was required. That is, when supplying auxiliary steam to a turbine unit of multiple shafts, two valves 6
62 and 664 are used to control a large flow rate, and when the load is reduced and one turbine unit is used, a small capacity valve 66 is used.
Only 4 is used.

However, in the embodiment according to the present invention, as shown in FIG. 4, the leaked steam from the high pressure turbine 24 is joined to the low pressure main steam pipe 60 without being returned to the seal steam header 27 and supplied to the low pressure turbine 62. To do. Therefore, even if the load increases, the leaked steam from the high-pressure turbine gland is quickly extracted and supplied to the low-pressure turbine 62, so that the amount of gland seal steam is reduced as compared with that in FIG. 3.

That is, the amount of steam leaked from the high-pressure turbine gland is the same as the conventional one, but the amount of steam supplied to the gland seal may exceed the required steam amount of the gland seal by supplying the leak steam to the low-pressure turbine. Set to not. By reducing the amount of leaked steam supplied from the high-pressure turbine gland to the gland seal, the amount of supply from the auxiliary steam side increases and balances with the required amount of gland seal steam, and no surplus steam is generated.

Further, according to the present invention, since the amount of steam required for the gland seal is always larger than the amount of leak from the high pressure turbine gland, auxiliary steam of a predetermined amount or more for compensating for insufficient steam is always required. And Therefore, the minimum flow rate of the auxiliary steam supply pressure control valve 66 does not need to be zero, and can be set to a large value. Maximum flow rate, for example
At 240 t / h, if the minimum flow rate is increased from 0.4 t / h in the conventional device to 3 t / h, the flow rate ratio can be about 80. As a result, the control range is relaxed, so that the small valve 664 used conventionally can be dispensed with and the large valve 662 can be used, so that the facility cost can be reduced. In this case, when the steam becomes excessive, the steam pressure in the auxiliary steam header 72 rises, so that the gland steam exhaust valve 84 is opened and supplied to the low-pressure turbine 62.

Next, a method of controlling each valve in the embodiment of the present invention will be described with reference to FIGS. FIG. 5 shows the relationship between the valve openings of the gland steam pressure control valve 70 and the gland steam exhaust valve 84. As described above, since the pressure of the gland seal steam header 72 is controlled to be maintained at a constant pressure slightly higher than the atmospheric pressure, for example, 1 atg, in the region where the pressure of the gland seal steam header 72 is lower than the target pressure. , Grand steam pressure control valve 70
Are controlled to open, and the gland steam exhaust valve 84 is controlled to close.

On the contrary, in a region where the pressure of the gland seal steam header 72 is higher than the target pressure, the gland steam pressure control valve 84 is closed and the gland steam exhaust valve 70 is controlled to open. Accordingly, when the pressure of the gland seal steam header 72 is within the set pressure range, both the gland steam pressure control valve 70 and the gland steam exhaust valve 84 are closed, and the pressure of the gland seal steam header 72 is a constant value,
Alternatively, it is kept within a predetermined range.

When the opening of the gland seal steam pressure control valve 70 is narrowed, the pressure on the upstream side of the valve increases. Therefore, the control valve 6
Reference numeral 64 narrows the opening to suppress the pressure rise. As a result, the flow rates of the control valve 664 and the control valve 70 are throttled to the same flow rate to balance the two.

Next, a specific control method will be described with reference to FIG. Similar to the control method in the prior art described above, the auxiliary steam mother pipe 86 and the gland seal auxiliary steam header 72 are provided.
Pressures 90 and 92 are detected, pressure regulators 94 and 96 calculate deviations from the set pressure, and signal converters 98, 100 and 102 operate auxiliary steam pressure control valve 66 and gland steam pressure control valve. 70, the opening / closing control of the gland steam exhaust valve 84 is performed. According to the present invention, the auxiliary steam pressure adjusting valve 66 is a single valve 664 and the control range is wide, so that the number of constituent axes of the plant is When the number increases, there is a possibility that the restriction of the minimum flow rate may be limited due to the performance of the control valve 664.

In such a case, the gland steam pressure control valve 70 (or the gland steam exhaust valve 84) is provided so that the steam corresponding to the minimum opening degree of the auxiliary steam supply pressure control valve 664 can be taken into the gland seal steam header 72. A lower limit limiter 104 for opening the valve is added to limit the lower limit of the opening.

This device 104 uses the result of the calculation performed by the pressure regulator 96 to adjust the gland steam pressure regulating valve 7
When narrowing down 0, the opening degree of the auxiliary steam supply pressure control valve 664 on the upstream side is restricted so that it cannot be throttled below the narrowing limit flow rate (minimum flow rate). The seal steam header 72 takes in the steam corresponding to the minimum opening degree of the auxiliary steam pressure supply control valve 664, and discharges it from the gland steam exhaust valve 84 for stable operation. Further, the same effect can be obtained even if the device 104 is similarly attached to the gland steam exhaust valve 84.

Further, the steam discharged from the gland steam exhaust valve 84 is guided to the low-pressure turbine 62, is recovered as the power of the turbine, and the turbine is made to work, so that the surplus steam can be used without waste. In addition, in a plant in which a feed water heater is installed, it is possible to guide the discharged steam to the feed water heater and use it as steam for heating the feed water.

[0042]

According to the present invention, the seal steam supply line from the high pressure turbine gland to the seal steam header is deleted, and the leaked steam from the gland seal is sent to the low pressure turbine in the lower stage to recover energy. As a result, the amount of ground leak steam flowing into the auxiliary steam header is reduced, so that the amount of supply from the auxiliary steam side is correspondingly increased to supply the amount of steam necessary for the gland seal over the entire operating region. Therefore, the amount of surplus steam generated during high-load operation is reduced, and the thermal efficiency of the entire plant is improved with the reduction of steam discarded to the condenser.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the device of the present invention.

FIG. 2 is a system diagram showing a configuration of a conventional device.

FIG. 3 is a diagram showing a relationship between an operating load of a steam turbine of a conventional device, a required steam amount of a gland seal, and a leak steam amount from a turbine gland.

FIG. 4 is a diagram showing the relationship between the operating load of the steam turbine of the device of the present invention, the required steam amount of the gland seal, and the leak steam amount from the turbine gland.

FIG. 5 is a diagram showing a relationship between a gland seal steam header pressure and a valve opening degree of a pressure control valve.

FIG. 6 is a diagram showing a pressure control method by a conventional device.

FIG. 7 is a diagram showing a pressure control method by the device of the present invention.

[Explanation of symbols]

10 ... Gas turbine, 12 ... Exhaust heat recovery boiler, 14 ... High pressure drum, 16 ... Saturated steam, 18 ... High pressure superheater, 20 ...
Superheated steam, 22 ... High-pressure main steam control valve, 24 ... High-pressure steam turbine, 26 ... Low-temperature reheat steam pipe, 28 ... Medium-pressure drum, 3
4 ... Medium pressure superheater, 36 ... Superheated steam, 40 ... Reheater, 42
... superheated steam, 44 ... reheated steam control valve, 46 ... medium pressure steam turbine, 50 ... low pressure drum, 52 ... saturated steam, 54 ... low pressure superheater, 56 ... superheated steam, 58 ... low pressure main steam control valve,
62 ... Low-pressure steam turbine, 64 ... Generator, 65 ... Extracted steam, 66 ... Auxiliary steam supply pressure control valve, 68 ... Desuperheater, 7
0 ... Grand steam pressure control valve, 72 ... Grand seal steam header, 74 ... Turbine gland seal part, 81 ... High pressure turbine gland leak steam, 83 ... High pressure turbine gland leak steam supply line, 84 ... Gland steam exhaust valve, 85 ... Return Water vessel, 86 ... Auxiliary steam mother tube, 90 ... Pressure detector, 92 ... Pressure detector, 94 ... Pressure regulator, 96 ... Pressure regulator, 98 ... Signal converter, 100 ... Signal converter, 1
02 ... Signal converter, 104 ... Lower limiter of valve opening.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Hiroshi Hattori, 3-2-1, Sachimachi, Hitachi, Ibaraki Prefecture, Hitachi Engineering Co., Ltd.

Claims (5)

[Claims] 1. A plurality of turbine units including an exhaust heat recovery boiler that generates steam using exhaust gas as a heat source, and a plurality of steam turbines that are connected to the same shaft and that are driven by the steam generated in the exhaust heat recovery boiler. And an auxiliary steam header that constantly supplies a gland seal of a predetermined pressure to the gland seal of each turbine of the turbine unit over the entire operating region, and the auxiliary steam header when the pressure of the auxiliary steam header exceeds a predetermined value. Gland steam exhaust valve for discharging the steam of the turbine unit, an energy recovery device for recovering energy by supplying leaked steam from the gland seal of the high-pressure side turbine of the turbine unit to the low-pressure turbine on the lower stage side, and the pressure of the auxiliary steam header Is below a specified value, auxiliary steam is supplied from the outside to maintain its pressure at a specified value. A pressure control valve is provided, and the supply amount of leakage steam from the turbine gland seal is controlled so that the sum of the supply amount of the auxiliary steam becomes the required vapor amount of the gland seal, and the leakage from the turbine gland seal A steam turbine gland seal steam characterized in that the steam amount is set lower than the required gland seal steam amount, and the auxiliary steam is supplied from the gland steam pressure control valve to the auxiliary steam header over the entire operating region. Supply device. 2. The steam supply device for a steam turbine gland seal according to claim 1, wherein the exhaust gas is supplied from a gas turbine. 3. The auxiliary steam supply pressure control valve for supplying steam of a predetermined pressure is provided on the upstream side of the gland steam pressure control valve, and at least the gland steam pressure control valve and the gland steam exhaust valve are provided. On the other hand, a steam supply device for a steam turbine gland seal, which is provided with a minimum opening limit and whose opening can be changed according to the number of operating units (number of operating axes) of the turbine unit. 4. The steam turbine gland seal according to claim 1, further comprising an energy recovery device for recovering excess steam discharged from the gland steam exhaust valve to a steam turbine side and recovering and using the excess steam in a plant. Steam supply device. 5. A plurality of turbine units including an exhaust heat recovery boiler that generates steam using exhaust gas as a heat source, and a plurality of steam turbines that are connected to the same shaft and that are driven by the steam generated in the exhaust heat recovery boiler. And an auxiliary steam header that constantly supplies a gland seal of a predetermined pressure to the gland seal of each turbine of the turbine unit over the entire operating region, and the auxiliary steam header when the pressure of the auxiliary steam header exceeds a predetermined value. Energy for exhausting the steam of the above and supplying leaked steam from the gland steam exhaust valve that supplies the steam to the low pressure side turbine and the gland seal of the high pressure side turbine of the turbine unit to the low pressure turbine on the lower stage side When the pressure of the recovery device and each of the auxiliary steam headers is below a predetermined value, the auxiliary steam is supplied with the auxiliary steam headers. A steam supply device for a steam turbine gland seal, comprising: a gland steam pressure control valve that supplies the pressure to a gland steam pressure control valve.