JP2001207808A - Steam cooled quick start system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam cooled quick start system raising exhaust gas temperature and speeding up steam generation in a waste heat recovery boiler of a combined cycle plant for enabling a quick start of the plant. SOLUTION: By an operation of a stabilizing burner provided in an inlet part of the waste heat recovery boiler, a load of a gas turbine can be increased without ventilating self-generated steam as gas turbine cooling steam because high temperature exhaust of the gas turbine does not the only heating source for the waste heat recovery boiler. By fully opening a gas inlet valve of a compressor, an exhaust gas amount is sufficiently secured for adequately operating the stabilizing burner. As a result, generation of the self-generated steam is speeded up for enabling the quick start of the plant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam cooling rapid start system in a waste heat recovery boiler of a combined cycle plant, in which the temperature of exhaust gas is increased to speed up the generation of steam and to quickly start the plant. .

[0002]

2. Description of the Related Art A conventional device will be described with reference to FIG. FIG. 4 is a schematic system diagram of a combined cycle plant.

Air flowing into an axial compressor (compressor) 21 is compressed and enters a combustor 22, in which fuel supplied separately is burned to generate high-temperature gas, which is expanded in a gas turbine 23. To generate rotational energy.

Since the gas turbine 23 has a structure mechanically axially coupled to the generator 24 together with the axial compressor 21, the generator 24 is driven by rotation of the gas turbine 23 to obtain electric power.

[0005] In this way, the gas turbine 23 which drives the generator 24 and performs one job of securing electric energy is provided.
Is then guided to an exhaust heat recovery boiler (HRSG) 25 to generate steam, and then discharged from a chimney 26 to the atmosphere.

On the other hand, steam generated in the exhaust heat recovery boiler 25 is supplied to a high-pressure turbine according to its pressure and temperature level.
Among the medium and low pressure turbines, the steam is supplied to the corresponding steam turbines 27, 28 and 29,
Driving a generator 30, which is mechanically coupled to 8, 29, provides more power.

[0007] In the above-described series of cycles, a gas turbine portion corresponding to an upstream side, which is included in a so-called topping cycle, is exposed to high-temperature gas.
Conventionally, cooling of the two-stage stationary blades, moving blades, and other parts to be cooled at a high temperature of the gas turbine is usually performed by compressed air obtained by cooling a part of the discharge air of the axial flow compressor 21 for many years. However, in recent years, a steam cooling cycle has been adopted in order to further improve the thermal efficiency of the entire plant.

[0008]

However, in the above-described steam cooling cycle, the higher the temperature of the exhaust gas from the gas turbine, the faster the generation of self-canister steam (HRSG generated steam), so that the cooling steam can be secured earlier. In a steam cooling system in which steam is supplied to cool the blades of a gas turbine exposed to high-temperature gas and other high-temperature cooled parts, a high load is applied to the gas turbine unless a certain amount of steam is passed through the high-temperature cooled part. Therefore, the plant must be started gradually, and the start-up time must be long.

For this reason, FIG.
As shown in FIG. 1, an auxiliary boiler (Aux.
B), steam is generated by the auxiliary boiler, and the steam is used as cooling steam for the high-temperature cooled portion of the gas turbine at the time of plant startup. However, installing one auxiliary boiler in parallel with the plant construction cost , Running costs, etc., are greatly increased.

SUMMARY OF THE INVENTION The present invention has been made under such a background, and has been made to reduce the number of facilities in a combined cycle plant having a steam cooling cycle and to shorten the cycle startup time. It is an object to provide things.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and in a steam cooling cycle of a combined cycle plant, an auxiliary fuel is supplied to an inlet portion of an exhaust heat recovery boiler supplied with gas turbine exhaust gas. An object of the present invention is to provide a steam-cooled rapid start system that is provided with a burner and configured to start by fully opening an inlet valve of a gas turbine compressor at a low load at the time of start.

That is, according to the present invention, by employing the auxiliary burner at the inlet of the exhaust heat recovery boiler, the heating source of the exhaust heat recovery boiler does not need to depend only on the high temperature exhaust gas of the gas turbine. As a result, the load on the gas turbine was increased without venting the self-canister steam as the gas turbine cooling steam.Moreover, by fully opening the gas inlet valve of the compressor, the amount of exhaust gas was secured and the auxiliary combustion burner functioned properly. It accelerates the generation of self-canistered steam and enables rapid start-up of the plant.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a schematic system of a combined cycle plant according to the present embodiment.

Reference numeral 1 denotes an exhaust heat recovery boiler (HRSG), which, although not shown in detail, includes units such as an economizer, an evaporator, a superheater, and a reheater in order.

Reference numeral 2 denotes an exhaust gas duct, which is a path for supplying exhaust gas to the exhaust heat recovery boiler 1, which has been expanded by a gas turbine located upstream thereof and has completed one work, but still has sufficient thermal energy.

Reference numeral 3 denotes an auxiliary burner, which is disposed at the exhaust gas inlet of the exhaust heat recovery boiler 1 corresponding to the end of the exhaust gas duct 2, and the fuel of the auxiliary burner 3 branches off from the fuel system of the gas turbine combustor. It is supplied by a fuel pipe 4.

Reference numerals 5, 6, and 7 denote steam turbines, respectively, which are high-pressure steam turbines, medium-pressure steam turbines, and high-pressure steam, medium-pressure steam, or low-pressure steam supplied from the exhaust heat recovery boiler 1.
It is a low-pressure steam turbine, which generates electric power by driving a generator 8 which is mechanically coupled to the shaft, and the final exhaust gas is condensed by a condenser 10, passed through a condenser line 11, and discharged into a waste heat recovery boiler 1.
Returned as water supply.

Reference numeral 9 denotes a steam pipe, which is a passage for branching high-pressure exhaust gas from a steam turbine (corresponding to a high-pressure turbine) 5 and supplying it to a high-temperature portion to be cooled such as a blade or a transition piece of a gas turbine as cooling steam. After the cooling steam supplied from the steam pipe 9 is heated through a predetermined cooling process and, if necessary, is reheat-adjusted via the exhaust heat recovery boiler 1, the cooling steam is supplied to the steam turbine (medium). (Corresponding to a pressure turbine) 6.

Although schematically shown, the steam-cooled gas turbine is mechanically connected to a compressor and a generator by a rotating shaft, and a gas inlet valve (not shown) provided in the compressor. By controlling the opening of (IGV), the amount of gas supplied to the gas turbine via the combustor can be adjusted.

In the present embodiment configured as described above, at the exhaust gas inlet of the exhaust heat recovery boiler 1 in which the exhaust gas duct 2 communicates with the exhaust heat recovery boiler 1, an auxiliary burner 3 provided here is provided. By advancing the combustion, the combustion gas from the auxiliary burner 3 and the exhaust gas from the gas turbine are mixed, so that the temperature becomes higher and the generation of self-canister steam can be promoted.

Further, in the auxiliary combustion burner 3, the fuel supplied from the fuel system through the fuel pipe 4 burns together with the combustion component supplied as the gas turbine exhaust gas. , And progress stably.

Accordingly, if the generation of the self-canister steam by the waste heat recovery boiler 1 proceeds appropriately, this steam is sent to the steam turbines 5, 6, 7 according to the respective pressure and temperature levels as described above. When the generator 8 is driven, a part of the generated steam is sent through the steam pipe 9 to a high-temperature portion such as a gas turbine blade or a transition piece, where it is subjected to cooling.

For comparison, FIG. 3 shows a conventional auxiliary boiler adopting an auxiliary boiler, and FIG. 2 shows an embodiment of the present invention. In the case of using a conventional auxiliary boiler, a combined cycle boiler is used. In order to increase efficiency, the gas inlet valve (IGV) schedule raises the load by fully closing at low load, so that the exhaust gas temperature follows a gradual rise mode and secures the predetermined exhaust gas temperature to generate self-canister steam. It takes a certain amount of time to reach.

On the other hand, in this embodiment, as shown in FIG. 2, the operation is performed with the gas inlet valve (IGV) fully opened at the time of low load, so that the amount of exhaust gas supplied through the gas turbine is sufficient. Yes, the combustion of the auxiliary burner proceeds appropriately and suitably, and the exhaust gas temperature becomes a high temperature range immediately after the start, the function of the exhaust heat recovery boiler 1 is sufficiently exhibited, the self-canister steam generation is accelerated, and the gas turbine is rapidly started. Becomes possible.

That is, according to the present embodiment, a sufficient amount of exhaust gas obtained by fully opening the gas inlet valve (IGV) is supplied to the auxiliary combustion burner, so that the self-canister steam starts a steam cooling cycle. As a result, it is possible to perform the raising quickly, and as a result, it is not necessary to increase the equipment such as the auxiliary boiler, and the economic effect can be greatly improved through the production and operation.

Although the present invention has been described with reference to the illustrated embodiment, the present invention is not limited to such an embodiment.
It goes without saying that various changes may be made to the specific structure within the scope of the present invention.

[0027]

As described above, according to the present invention, in the steam cooling cycle of the combined cycle plant, the auxiliary heat burner is provided at the inlet of the exhaust heat recovery boiler to which the gas turbine exhaust gas is supplied, so as to reduce the start-up time. Since the steam cooling quick start system was configured so that the gas turbine compressor inlet valve was fully opened and started at the time of load,
The operation of the auxiliary burner provided at the inlet of the exhaust heat recovery boiler eliminates the need to rely solely on the high-temperature exhaust gas from the gas turbine as a heat source for the exhaust heat recovery boiler. The load on the gas turbine is increased, and the gas inlet valve of the compressor is fully opened to secure a sufficient amount of exhaust gas to make the auxiliary burner function properly, thereby saving equipment without using an auxiliary boiler. Thus, a steam-cooled rapid start system capable of achieving cost reduction and quick start can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram of a combined cycle plant according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between exhaust gas temperature and opening / closing of a gas inlet valve (IGV) at a low load at the time of starting a cycle in the embodiment.

FIG. 3 is an explanatory diagram showing the relationship between the exhaust gas temperature and the opening and closing of a gas inlet valve (IGV) at a low load at the time of starting a cycle in a conventional one.

FIG. 4 is a schematic system diagram of a conventional combined cycle plant.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 waste heat recovery boiler 2 exhaust gas duct 3 auxiliary burner 4 fuel pipe 5 steam turbine 6 steam turbine 7 steam turbine 8 generator 9 steam pipe 10 condenser 11 condenser line 21 axial compressor 22 combustor 23 gas turbine 24 power generation Machine 25 waste heat recovery boiler 26 chimney 27 steam turbine 28 steam turbine 29 steam turbine 30 generator

Claims (1)

[Claims] In a steam cooling cycle of a combined cycle plant, an auxiliary burner is provided at an inlet of an exhaust heat recovery boiler supplied with gas turbine exhaust, and an inlet valve of a gas turbine compressor is fully opened at a low load at start-up. A steam-cooled quick-start system, characterized in that the steam-cooled quick-start system is configured to be started.