JP2653610B2 - Combined cycle power plant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined cycle power plant, and more particularly to an improved combined cycle power plant that reduces NOx contained in exhaust gas from a gas turbine.

[0002]

2. Description of the Related Art Conventionally used combined cycle power plants include a single shaft type in which a plurality of different types of motors are combined on a single shaft and arranged on a plurality of rows, and a gas turbine shaft. There is a so-called multi-shaft type in which a steam turbine shaft is separately separated and a plurality of gas turbine shafts and steam turbine shafts are arranged. Considering the size of the arrangement, the former is relatively common. The combined cycle power plant according to the present invention belongs to the former, and its configuration and arrangement are shown in FIG. That is, A
Denotes a combined cycle power plant in a first shaft train, and B denotes a combined cycle power plant in a second shaft train.

[0003] The first shaft row A is connected by one common shaft,
The air compressor 1A and the gas turbine 2 are arranged in this order from the right of the drawing.
A, a so-called power train in which the steam turbine 3A and the generator 4A are arranged in a skewered manner. The second shaft train B is also a power train in which the air compressor 1B, the gas turbine 2B, the steam turbine 3B, and the generator 4B are arranged in the same manner as described above.

[0004] In the above arrangement, the air compressors 1A, 1B that have sucked the atmosphere are turned into high-pressure air and the combustor 5A, 1A.
5B, and generates combustion gas together with the added fuel, and sends the combustion gas as a working fluid to the gas turbines 1A and 1B. The gas turbines 1A and 1B
The expansion work is performed to obtain a rotational torque, and the steam turbines 3A, 3
B is transmitting rotational power.

The exhaust gas leaving the gas turbines 1A and 1B is:
The steam is sent to separately disposed waste heat recovery boilers 6A and 6B, where steam is generated by the first heat exchangers 7A and 7B and the second heat exchangers 8A and 8B. NOx is to be removed.

[0006] The steam emitted from the first heat exchangers 7A and 7B is
The steam is sent to the steam turbines 3A and 3B, where the expansion work is replaced with rotational torque, and electric power is obtained by turning the generators 4A and 4B. The steam that has completed the expansion work is condensed in the condensers 10A and 10B, and after condensing, passes through the pumps 11A and 11B as second feed water.
It is sent to the heat exchangers 8A and 8B under pressure, and is subjected to steam generation again, so-called closed loop circulation.

As described above, this type of plant recovers exhaust heat by axially connecting the gas turbines 1A and 1B and the steam turbines 3A and 3B to increase the output of the entire prime mover, while at the same time increasing NOx as a source of air pollution. Are taking measures to curb this.

[0008]

Meanwhile, the denitration devices 9A and 9B provided in the exhaust heat recovery boilers 9A and 9B are provided with an ammonia injection device, and add ammonia to exhaust gas from the gas turbines 1A and 1B to pass through a catalyst. Chemical reaction is performed to suppress NOx.

However, during the rated operation of the gas turbines 1A and 1B, the exhaust gas temperature is as high as 500 to 600 ° C., and sufficiently reacts with ammonia through the catalyst, but as in the start-up operation of the gas turbines 1A and 1B, Exhaust gas temperature is 2
If the temperature is lower than 50 ° C., a large amount of unreacted ammonia is generated, and NO
There is a problem that it hardly contributes to x suppression.

[0010] In view of the above, an object of the present invention is to publish a combined cycle power plant in which various studies have been made so that NOx can be suppressed even during the start-up operation of a gas turbine.

[0011]

According to the present invention, an air compressor, a gas turbine, a steam turbine, and a power generator are arranged in a skewed shape on a common shaft, and the exhaust gas discharged from the gas turbine is separately sent to an exhaust heat recovery boiler. In a combined cycle power plant in which the generated steam is supplied to a steam turbine to generate electricity, in a combined cycle power plant in which a plurality of rows are arranged, an air compressor of one shaft series motor is used for a heat recovery steam generator of another shaft series motor. A conductive path for sending out high-temperature and high-pressure air is provided.

[0012]

According to the above construction, when one motor of the shaft series is in rated operation and the other motor of the shaft series is in the start-up operation, high-temperature, high-pressure air is generated from the air compressor of the motor of one shaft series. It is sent to the exhaust heat recovery boiler of another prime mover via the conduction path. For this reason, the temperature of the exhaust gas flowing through the exhaust heat recovery boiler of another shaft-sequence prime mover increases until a chemical reaction with ammonia through the catalyst becomes possible. Therefore,
Even during the start-up operation, it can contribute to the suppression of NOx contained in the exhaust gas.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A combined cycle power plant according to the present invention and an example will be described below with reference to the drawings. The same components as those in FIG. 4 are denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 1, a first shaft train A having a motor group coupled to one common shaft and a second shaft train B having a motor group coupled to another common shaft are parallel to each other. The shaft rows A and B are operated separately and independently.

In the above-described configuration, the air compressor 2A of the first shaft train A and the exhaust heat recovery boiler 6B of the second shaft train B are connected to each other by a conduction path 12A with a control valve 13 interposed therebetween. . In addition,
The exhaust heat recovery boiler 6A of the first shaft train A is also connected to a heat path 14 from an air compressor of another shaft train (not shown).

According to such a configuration, for example, when the first shaft train A is in the rated operation and the second shaft train B is in the start-up operation, the air flowing out of the air compressor 2A has a high temperature and a high pressure. Therefore, if the exhaust gas flowing through the exhaust heat recovery boiler 6B is sent to the exhaust heat recovery boiler 6B of the second shaft train B via the conduction path 12A as it is, the exhaust gas flowing through the exhaust heat recovery boiler 6B is heated, so that the denitration device 9B can cause a chemical reaction with the catalyst. become. When the first shaft train A is in the start-up operation, high-temperature and high-pressure air from an air compressor of another shaft train (not shown) passes through the conduit 14 and the exhaust heat recovery boiler 6
A, so that the temperature of the exhaust gas flowing through the exhaust heat recovery boiler 6A can be increased to contribute to NOx suppression.

FIG. 3 shows a second embodiment of the combined cycle power plant according to the present invention. In this embodiment, a conduction path 12B is provided for connecting the bleeding stage of the air compressor 2A of the first shaft train A and the exhaust heat recovery boiler 6B of the second shaft train B. Other components are the same as in the first embodiment. This embodiment considers that if the air pressure at the outlet of the air compressor 2A of the first embodiment is too high, the structure of the exhaust heat recovery boiler 6B of the second shaft train B is deformed.

FIG. 2 is a graph showing the temperature rise characteristics of the exhaust gas flowing through the exhaust heat recovery boiler and the NOx emission based on the above embodiment. In this figure, the shaded area indicates the temperature range in which the exhaust gas undergoes a chemical reaction in the denitration apparatus, the broken line indicates the conventional characteristic, and the solid line indicates the characteristic of the present invention.

As can be understood from FIG. 1, the temperature of the conventional exhaust gas G1 indicated by the broken line does not reach the chemical reaction region with the denitration apparatus until about 120 minutes or more have elapsed since the start of startup. Exhaust gas G shown by solid line
2 is pulled up as shown, and it can be greatly shortened to about 80 minutes until it enters the chemical reaction zone. Further, the NOx emission amount of the exhaust gas has conventionally been a characteristic N1 indicated by a broken line,
According to the present invention, a characteristic N2 indicated by a solid line is obtained, which is greatly reduced.

It will be readily understood that NOx can be significantly reduced by adding a heat source from another plant during the start-up operation of the combined cycle power plant.

[0021]

As described above, in the combined cycle power plant according to the present invention, since the air compressor of the first shaft train and the exhaust heat recovery boiler of the second shaft train are connected by the conduction path, the air The temperature of the exhaust gas can be easily increased with the help of the high-temperature and high-pressure air of the compressor, whereby NOx can be significantly suppressed even during the start-up operation.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment of a combined cycle power plant according to the present invention.

FIG. 2 Temperature characteristics of exhaust gas flowing through an exhaust heat recovery boiler and NO
The graph which simultaneously shows x discharge characteristic.

FIG. 3 is a schematic diagram showing a second embodiment of the combined cycle power plant according to the present invention.

FIG. 4 is a schematic diagram of a combined cycle power plant showing a conventional example.

[Explanation of symbols]

 A first shaft train B second shaft train 1A, 1B Gas turbine 2A, 2B Air compressor 3A, 3B Steam turbine 4A, 4B Generator 6A, 6B Exhaust heat recovery boiler 9A, 9B Denitration equipment 12A, 12B, 14 Conduction path

Claims (1)

(57) [Claims] An air compressor, a gas turbine, a steam turbine, and a power generator are arranged in a skewed shape on a common shaft, and the exhaust gas emitted from the gas turbine is sent to a separately disposed exhaust heat recovery boiler. In a combined cycle power plant in which a single-shaft prime mover that generates and supplies power to a plurality of rows is connected, a conduction path that sends high-temperature and high-pressure air from the air compressor of this shaft prime mover to a waste heat recovery boiler of another shaft prime mover is provided. A combined cycle power plant characterized by being provided.