JPH057941U - External combustion gas turbine - Google Patents

Abstract

(57) [Abstract] [Purpose] In a gas turbine having an independent large-capacity external combustor (2), the piping downstream of the gas relief valve (V3) that operates when the rotating system trips is simplified, and an exhaust gas boiler ( 5) To alleviate the thermal shock of 5) and to prevent the rise of pressure on the discharge side of the air compressor (1), which in turn prevents surging. [Composition] A desuperheater (7) is provided downstream of the gas relief valve (V3), and at the time of trip, the discharge air of the air compressor (1) is bypassed with a cutoff valve (V6) and a bypass line (9).
It is led to the desuperheater (7) and used as a dehumidifying fluid.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a gas turbine having an external combustor, and more particularly to a trip safety device system.

[0002]

[Prior Art]

 5 and 6 are system diagrams showing an example of a safety device for a conventional external combustion type gas turbine during a trip of a rotary system. FIG. 5 shows a state of valve operation during normal operation and FIG. 6 shows a situation of valve operation during trip.

First, in FIG. 5, the discharge air of the air compressor 1 burns low-calorie fuel in the external combustor 2 to become high-temperature high-pressure gas, which expands in the turbine 3 to drive the load 4. The exhaust gas from the turbine 3 is recovered in the heat exchanger 5 such as an exhaust gas boiler, and then released from the chimney 6 to the atmosphere.

When a fuel having a low heating value is used, the combustion load factor (called heat release) of the gas turbine combustor is extremely low. For this reason, the inner cylinder volume of the combustor becomes extremely large compared to the case of using natural gas or light oil as fuel, and reaches 10 times or more. Therefore, an annular can-shaped or annular combustor integrally formed with the gas turbine main body cannot be used, and an independent large-capacity single-tube combustor 2 is used. A gas turbine using such a combustor is called an external combustion gas turbine.

When the rotary system of this type of gas turbine trips, a large amount of gas in the external combustor 2 and the pipes flows into the turbine 3 simply by closing the fuel cutoff valve V1 as in a normal gas turbine. , Gas turbines cannot be stopped rapidly. This phenomenon is especially noticeable when the combustor is installed away from the turbine to bring it closer to the fuel supply. Therefore, as shown in FIG. 6, the trip signal closes the gas shutoff valve V2 to open the gas relief valve V3 to prevent the combustion gas from flowing into the turbine 3, and the high pressure air shutoff valve V4 to close the combustion. The air supply to the compressor is stopped and the bypass valve V5 is opened to prevent surging of the compressor.

[0006]

[Problems to be solved by the device]

 The conventional trip safety device has the following problems to be solved. That is, the downstream piping of the gas relief valve V3 needs to be heat resistant, and the heat exchanger 5 may be damaged by thermal shock. Also, if there is a gap between the open / close synchronization of each shutoff valve and the open / close speed, the pressure on the discharge side of the air compressor rises and the compressor may rush into surging.

[0007]

[Means for Solving the Problems]

 In order to solve the above-described conventional problems, the present invention provides a decompressor downstream of a gas relief valve of a piping system that bypasses a turbine by branching from an outlet side piping of an external combustor, and an air compressor. The present invention proposes an external combustion gas turbine, which is characterized in that it is branched from the discharge side pipe and communicates with the above-mentioned desuperheater, and a bypass pipe line having a cutoff valve is provided.

[0008]

[Action]

 According to the present invention, the high-temperature gas that has passed through the gas relief valve at the time of trip of the gas turbine is cooled by the desuperheater and then flows into the heat exchanger through the non-heat resistant downstream pipe. Further, most of the air on the discharge side of the air compressor is directly supplied to the desuperheater without passing through the turbine, so the pressure of the air discharged from the compressor does not rise. Further, since the air discharged from the compressor is used as the dehumidifying fluid, no special dehumidifying fluid facility is required or the capacity is small.

[0009]

【Example】

 1 and 2 are system diagrams showing an embodiment of the present invention. FIG. 1 shows a valve operation state during operation and FIG. 2 shows a valve operation state during trip.

In the present embodiment, the temperature reducer 7 is installed near the downstream side of the gas relief valve V3. A bypass pipe 9 that bypasses the turbine 3 and communicates with the desuperheater 7 is provided in the discharge side pipe of the air compressor 1. The bypass pipe 9 has a compressed air bypass valve (cutoff valve). V6 is provided. That is, the discharge air of the air compressor 1 is used as the temperature reducing fluid of the temperature reducer 7. Then, if the discharged air alone is not sufficient as the temperature reducing fluid, water is further used. In that case, fresh water from the water storage tank 8 is sprayed. The water tank cutoff valve V7 operates in synchronization with the trip signal.

The high-pressure air cutoff valve V4 is opened during gas turbine operation and closed during trip, while the compressed air bypass valve V6 is closed during operation and opened during trip. That is, these two valves V4 and V6 must be synchronized with each other to perform the reverse operation. However, if both valves are opened and closed independently, they will not operate completely synchronously due to signal delay, hysteresis, and valve characteristic, etc. As a result, there may be a case where the air discharged from the air compressor is insufficient. When the one-way gas turbine is started, the opening of both valves must be controlled independently in order to make the start-up smooth. Therefore, in the present embodiment, the high pressure air cutoff valve V4 and the compressed air bypass valve V6 are mechanically connected via a clutch, and both valves are provided with independent valve drive machines.

FIGS. 3 and 4 are cross-sectional views showing the interlocking mechanism of both valves V4 and V6, FIG. 3 showing a state where the clutch is engaged, and FIG. 4 showing a state where the clutch is disengaged. In these drawings, the valve shaft of the high pressure air cutoff valve V4 and the valve shaft of the compressed air bypass valve V6 are connected by a clutch 11, and valve drive motors 12A and 12B are attached to the ends of the valve shafts, respectively. . In the illustrated example, a conical clutch is used as the clutch 11. At the time of clutch engagement shown in FIG. 3, both valves V4 and V6 are driven by one valve drive machine (valve drive motor 12A in the case of the conical clutch of the illustrated example).

At the time of starting the gas turbine, if the clutch 11 is disengaged as shown in FIG. 4, the high-pressure air cutoff valve V4 and the compressed air bypass valve V6 are opened by independent valve drivers 12A and 12B. Controlled, a portion of the air compressor discharge air is sent to the combustor. After the start-up is completed, if the clutch 11 is put in as shown in FIG. 3, the high pressure air cutoff valve V4 and the compressed air bypass valve V6 are mechanically connected, and both valves operate in perfect synchronization. Therefore, when the gas turbine trips, the high-pressure air discharged from the air compressor is sent to the desuperheater without entering the combustor.

In this embodiment, the desuperheater 7 is provided immediately after the gas relief valve V3, and the discharge air of the air compressor 1 is used as the dehumidifying fluid. The heat exchanger 5 is not damaged and the air compressor 1 is not surging. Therefore, the cost can be reduced and the reliability of the plant can be improved. Further, since the high-pressure air cutoff valve V4 and the compressed air bypass valve V6 are connected via the clutch 11, and both valves are provided with independent valve drive mechanisms, the high-pressure air cutoff valve and the compressed air bypass valve are installed during the turbine trip. Synchronous operation with the bypass valve prevents compressor surges and insufficient cooling air flow to the desuperheater. At startup, both valves are controlled independently and the gas turbine can be started smoothly.

[0015]

[Effect of the device]

 According to the present invention, it is not necessary to use expensive heat-resistant specifications for the downstream piping of the gas relief valve, and neither damage of the heat exchanger nor surging of the air compressor occurs. Therefore, the cost can be reduced and the reliability of the plant can be improved.

[Brief description of drawings]

FIG. 1 is a system diagram showing a valve operation state during gas turbine operation in an embodiment of the present invention.

FIG. 2 is a system diagram showing a valve operation state at the time of trip of a gas turbine in the above embodiment.

FIG. 3 is a view showing a state in which a clutch is engaged in the interlocking mechanism of the high pressure air cutoff valve and the compressed air bypass valve in FIGS. 1 and 2.

FIG. 4 is a diagram showing a state where a clutch is disengaged in the interlocking mechanism.

FIG. 5 is a diagram showing a valve operation state during turbine operation in an example of a conventional rotary trip type safety device for an external combustion type gas turbine.

FIG. 6 is a diagram showing a valve operation state at the time of turbine trip in the above-mentioned conventional security device.

[Explanation of symbols]

 1 Air Compressor 2 External Combustor 3 Turbine 4,5 Heat Exchanger (Exhaust Gas Boiler) 6 Chimney 7 Desuperheater 8 Water Tank 9 Bypass Pipe 11 Clutch 12A, 12B Valve Drive Motor V1 Fuel Cutoff Valve V2 Gas Cutoff Valve V3 Gas Relief valve V4 High pressure air cutoff valve V5 Bypass valve V6 Compressed air bypass valve (cutoff valve)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Kenichi Arase 2-1-1, Niihama, Arai-cho, Takasago-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Takasago Plant

Claims (1)

[Claims for utility model registration] [Claim 1] A desuperheater is provided downstream of the gas relief valve in a piping system that branches from the outlet side piping of the external combustor and bypasses the turbine, and the discharge side piping of the air compressor. An external combustion gas turbine, characterized in that a bypass pipe line that branches off from and communicates with the desuperheater and that has a cutoff valve is provided.