JPH06146927A - Compound power generating plant - Google Patents

Abstract

PURPOSE:To embody a compound power generating plant of low cost and long life and provided with a high temperature and high pressure gas discharging system, in which generation of noise is suppressed. CONSTITUTION:A gas turbine bypass pipe passage 12 is branched from a fuel gas pipe passage for supplying high temperature end high pressure gas from a pressurized stream bed-provided boiler 1 to a gas turbine 5, and a temperature reducing device 13, a gas turbine bypass valve 15, and a pressure reducing device 16 are arranged on the bypass pipe passage 12. The gas turbine bypass pipe passage 12 is communicated with a gas turbine outlet flue. A high temperature dust removal device 17 is interposed in a combustion gas pipe. At the time of stopping a plant, after stopping the gas turbine 5, gas inside the pressurized stream bed provided boiler 1 is cleaned by means of a cyclone 3 and the high temperature dust removal device 17 by opening the bypass valve 15 of the gas turbine bypass pipe passage 12, and then the gas enters the bypass pipe passage 12. Furthermore, the temperature and pressure of the gas are reduced by the temperature reducing device 13 and a pressure reducing device 16 to nearly the level of the atmospheric pressure, and the gas is discharged in the flue.

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 having a gas turbine that uses a high temperature and high pressure gas produced by a pressurized fluidized bed boiler as a fuel.

[0002]

2. Description of the Related Art A conventional example of a combined cycle power plant having a pressurized fluidized bed boiler and a gas turbine produced by the boiler and using high temperature and high pressure gas as a fuel will be described with reference to FIG. Figure 2
In FIG. 1, 1 is a pressurized fluidized bed boiler, and the high temperature / high pressure gas produced in a pressurized container 2 constituting the boiler is guided to a gas turbine 5 through a cyclone 3 and a gas turbine fuel gas inlet stop valve 9.

In the gas turbine 5, the high temperature and high pressure gas is combusted by the air 4 passing through the compressor, and the combustion gas is discharged through the denitration device 6, the exhaust heat recovery heat exchanger 7 and the chimney 8. Reference numeral 10 denotes a gas turbine bypass valve, which is installed upstream of the gas turbine inlet fuel stop valve 9 and has a high-temperature / high-pressure gas release system. Has a function of performing an operation of releasing the air into the atmosphere 11.

[0004]

As described above, the conventional apparatus in which only the atmosphere release valve is installed as the high temperature / high pressure gas release system in the combined power plant has the following problems.

(1) When the temperature of the gas to be handled is high such that it exceeds 600 ° C., the valve material of the atmosphere release valve must be Hastelloy, Inconel, or the like, which makes the valve expensive. When using carbon steel, the valve body,
Since it is necessary to cool the valve seat, the valve box, etc., the system becomes complicated and the valve body life consumption increases, so it is necessary to replace the valve in a short period of time.

(2) If the gas temperature is high, the valve size must be increased and the number of installed valves also increases.

(3) When the gas temperature is high, the noise generated in the valve is large and a large-scale noise countermeasure is required.

(4) Since this high temperature and high pressure gas discharge line is frequently used, it is a factor that significantly reduces the reliability of the plant.

(5) The gas discharged from the boiler contains high-concentration dust and is roughly dust-removed by a cyclone. However, there is a concentration of about 40 to 50 ppm at the inlet of the atmospheric release valve, which may cause erosion of the valve. It An object of the present invention is to provide a combined cycle power generation plant having a high temperature / high pressure gas discharge configuration that solves these problems.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in a combined cycle power plant having a pressurized fluidized bed boiler and a gas turbine that uses the high temperature and high pressure gas produced by the boiler as a fuel. From the fuel gas supply pipeline that connects the fuel gas inlet stop valve of the gas turbine to the high temperature dedusting device, and is branched from the fuel gas supply pipeline that exits the high temperature dedusting device. A configuration is provided in which a gas turbine bypass pipe that reaches the atmosphere is provided with a turbine bypass valve and a pressure reducing device interposed. Atmospheric emissions can be via the gas turbine exit flue or directly.

[0011]

The combined cycle power plant according to the present invention is provided with the above-mentioned gas turbine bypass line, and when the gas turbine trips, the gas turbine inlet stop valve is fully closed, and then a gas flow is created in the fluidized bed to form a gas flow in the bed. The bypass valve installed in the gas turbine bypass line for fluidization is opened. This causes the hot gas in the fluidized bed to flow into the gas turbine bypass line.

In this case, since the high temperature gas is cooled by the temperature reducing device installed upstream of the gas turbine bypass pipe, the gas temperature at the gas turbine bypass valve inlet can be lowered. This makes it possible to use inexpensive carbon steel as the material of the bypass valve body.

As described above, since the specific volume of the processing gas is reduced by lowering the temperature of the bypassed gas, the bypass valve can be made smaller and the number of units can be reduced as compared with the prior art. Further, since the pressure reducing device is provided on the downstream side of the bypass valve, the differential pressure in the bypass valve can be reduced, and the wear of the valve body and the valve seat portion due to the dust contained in the gas can be prevented.

Further, in the pressure reducing device disposed downstream of the bypass valve, multistage depressurization is performed so that a supercritical flow does not occur, and if the gas temperature is lowered, the noise level can be lowered by a synergistic effect due to the reduction of gas energy. .

Further, since the gas flowing into the gas turbine bypass line is reduced to a low level of about 10 ppm by the high temperature dedusting device installed at the outlet of the pressurized fluidized bed boiler, the gas turbine is reduced. Bypass valve erosion is less than before.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a combined power plant according to the present invention.
A specific description will be given based on the embodiment shown in FIG. Note that FIG.
2, the same parts as those of the conventional device shown in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted. In the device shown in FIG. 1, the temperature reducing device 13 is provided at the most upstream part of the gas turbine bypass pipeline 12 branched from the upstream part of the gas turbine fuel gas inlet stop valve 9, and the gas turbine bypass valve 15 is provided downstream of the temperature reducing device 13. Is a system in which a pressure reducing device 16 is installed on the downstream side of the gas turbine bypass valve 15.

A high temperature dedusting device 17 is disposed downstream of the cyclone 3 in the gas pipeline extending from the pressurized fluidized bed boiler 1 to the gas turbine. When the plant is normally shut down or in an emergency stop such as an accident, the gas turbine 5
At this point in time after the stop, the gas turbine fuel gas inlet stop valve 9 is fully closed, but in order to keep the coal bed in the pressure vessel 2 of the pressurized fluidized bed boiler 1 fluidized, The accumulated gas is discharged to the outside and the pressure is reduced.

The gas in the pressure vessel 2 is cleaned by the cyclone 3 and the high temperature dedusting device 17 by opening the gas turbine bypass valve 15, and then flows into the gas turbine bypass line 12. Gas turbine bypass line 1
The gas flowing into 2 is cooled by the cooling device 13 by the cooling water 14 until the temperature reaches 600 ° C. or lower.

Whether the cooling device 14 uses the direct contact method between the cooling water 14 and the gas or the indirect contact method between the cooling water 14 and the gas, the cooling water 14 is controlled by the cooling device 14 of the cooling device 14. The design temperature on the downstream side of the temperature reducing device 13 can be lowered by constantly circulating the temperature inside.

The gas exiting the noise reduction device 13 flows into the gas turbine bypass valve 15, is further decompressed by the multi-stage decompression device 16 to near atmospheric pressure, and is discharged to the flue. The temperature of the gas exiting the temperature reducer 13 is below 600 ° C, so
The illustrated device has the following advantages over the prior art.

(1) Since the specific volume of the processing gas is reduced to 70% or less of the conventional one, it is possible to reduce the size of the pipe diameter on the downstream side of the temperature reducing device 13 and reduce the capacity of the gas turbine bypass valve 15.

(2) By setting the temperature of the processing gas to 600 ° C. or lower, the material of the gas turbine bypass valve 15 can be made inexpensive such as carbon steel. Also, the valve body, valve seat,
A simple structure can be achieved without the need to cool the valve box or the like.

(3) Since the specific volume of the treated gas is as small as 70% or less of the conventional one, the noise generated in the gas turbine bypass valve 15 and the pressure reducing device 16 can be reduced by 10 dB or more.

(4) A decompression device 16 is installed on the downstream side of the gas turbine bypass valve 15, and the gas turbine bypass valve 1
By not giving a large differential pressure to 5, it is possible to reduce the wear of the valve body and the valve seat portion of the gas turbine bypass valve 15. By the above (1) to (4), it is possible to improve the reliability of plant operation and reduce noise.

(5) Further, the gas turbine bypass line 1
Since the gas flowing into 2 is sufficiently cleaned by the cyclone 3 and the high temperature dedusting device 17, the erosion of the gas turbine bypass valve 15 can be prevented.

Although the present invention has been specifically described based on the illustrated embodiment, the present invention is not limited to this embodiment.
It goes without saying that various modifications may be made within the scope of the present invention. For example, in the device shown in FIG. 1, the gas exiting the gas turbine bypass line 12 is configured to be discharged to the atmosphere via the gas turbine outlet flue, which does not pass through the gas turbine flue. Alternatively, the gas may be directly emitted into the atmosphere.

[0027]

As described above, in the combined cycle power plant according to the present invention, the high temperature dedusting device is arranged in the fuel gas supply pipe line connecting the fuel gas inlet stop valve of the gas turbine from the pressurized fluidized bed boiler, Since the fuel gas supply line that has exited the high-temperature dedusting device is branched, and a temperature reducing device, a gas turbine bypass valve, and a pressure reducing device are interposed, a gas turbine bypass line that reaches the atmosphere is provided. As described below, many effects can be obtained, and reliability of plant operation can be improved and noise can be reduced.

(1) Since the gas flowing into the gas turbine bypass valve is cooled through the temperature reducing device, the specific volume of the treated gas is reduced to, for example, 70% or less of the conventional volume, and the pipe on the downstream side of the temperature reducing device is reduced. It is possible to reduce the size of the bore and reduce the capacity of the gas turbine bypass valve.

(2) For the same reason as above, the material of the gas turbine bypass valve can be made inexpensive such as carbon steel. Further, it is not necessary to cool the valve body, the valve seat, the valve box, etc., and the structure can be simple.

(3) Similarly, since the specific volume of the treated gas becomes small, for example, 70% or less of that in the conventional case, noise generated in the bypass valve provided in the gas turbine bypass line or the pressure reducing device should be reduced by 10 dB or more. Can be done.

(4) Since the pressure reducing device is installed on the downstream side of the gas turbine bypass valve, wear of the valve body and the valve seat portion of the gas turbine bypass valve is prevented by preventing the gas turbine bypass valve from having a large differential pressure. Can be reduced.

(5) Since the gas flowing into the gas turbine bypass pipe has been sufficiently cleaned by the cyclone and the high temperature dedusting device, erosion of the gas turbine bypass valve can be prevented.

[Brief description of drawings]

FIG. 1 is an equipment layout diagram showing a configuration of a combined cycle power plant according to an embodiment of the present invention.

FIG. 2 is an equipment layout diagram showing a configuration of a conventional combined cycle power plant.

[Explanation of symbols]

 1 pressurized fluidized bed boiler 2 pressure vessel 3 cyclone 4 air 5 gas turbine 6 denitration device 7 exhaust heat recovery heat exchanger 8 chimney 9 gas turbine fuel gas inlet stop valve 12 gas turbine bypass line 13 temperature reducer 14 cooling water 15 Gas turbine bypass valve 16 Pressure reducing device 17 High temperature dedusting device

Claims (1)

[Claims] 1. In a combined power plant having a pressurized fluidized bed boiler and a gas turbine using the high temperature and high pressure gas produced by the boiler as a fuel, a fuel gas connecting a fuel gas inlet stop valve of the gas turbine to the boiler. Gas that reaches the atmosphere by arranging a high-temperature dedusting device in the supply pipeline and branching from the fuel gas supply pipeline that exits the high-temperature dedusting equipment and interposing a temperature reducing device, a gas turbine bypass valve and a pressure reducing device A combined power generation plant characterized by having a turbine bypass pipe line.