JPS61135940A - Exhaust gas damper - Google Patents

Abstract

PURPOSE:To prevent a reversal flow and an abnormal pressure increase when exhaust gas ducts are merged by providing a damper to the exhaust gas ducts that lead the burnt gas discharged from a gas turbine system to a smoke stack. CONSTITUTION:A compound cycle plant has a gas turbine system 10, a waste heat recovering boiler 20, a steam turbine system 40 and denitrification system 31. In such an arrangement, an exhaust gas damper 27 is disposed in an exhaust gas duct 25 from the waste heat recovering boiler 20 to a smoke stack 24. As an abnormal pressure increase in the exhaust gas duct can take place by the compressed air due to the racing gas turbine if a damper at the waste heat recovering boiler outlet is rapidly closed while the gas turbine is being tripped, the abnormal pressure increase is prevented by the rate of speed of the damper closure at the waste heat recovering boiler outlet and the action of the afore-said exhaust gas damper 27. Further, the burnt gas from the working gas turbine is prevented from reversing itself into the stopped gas turbine system.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an exhaust gas damper in an exhaust gas duct that guides combustion gas discharged from a gas turbine device from an exhaust heat recovery boiler to a chimney, and particularly relates to an exhaust gas damper for preventing backflow and for preventing abnormal pressure rise. This invention relates to an exhaust gas damper in an exhaust gas duct that can prevent

[Background of the invention]

Figures 5 and 6 show a conventional gas turbine device 10 and an exhaust heat recovery boiler 2 that generates steam using its combustion gas as a heat source.
This shows a combined cycle plant including a steam turbine 40 and a steam turbine device 40 that uses the generated steam as driving steam.

Here, the exhaust gas ducts 25 are merged at the chimney 24 and guided to the chimney. In addition, since two exhaust gas ducts are merged into one duct, when one unit is operating and the other is stopped, the exhaust gas from the operating unit passes through the stopped exhaust gas duct 25. υ, there is a problem of backflow to the exhaust heat recovery boiler 20 and the gas turbine device 10.

[Purpose of the invention]

An object of the present invention is to provide an exhaust gas damper that can prevent backflow of combustion gas during operation and abnormal pressure rise due to compressed air due to idle rotation when the gas turbine is stopped, when the exhaust gas ducts of two gas turbines are merged into one. It's about doing.

[Summary of the invention]

A feature of the present invention is that the exhaust gas damper in the exhaust gas duct that guides the combustion gas discharged from the gas turbine device from the exhaust heat recovery boiler to the chimney prevents the combustion gas during operation from flowing back into the stopped gas turbine device. However, it has a structure that can prevent abnormal pressure rise due to compressed air due to gas turbine idling during a gas turbine trip.

[Embodiments of the invention]

An embodiment of a combined cycle plant equipped with an exhaust gas damper in an exhaust gas duct to which the present invention is applied will be described.

In FIG. 1, the combined cycle plant includes a gas turbine device 10 and an exhaust heat recovery boiler 20 that generates steam using combustion gas discharged from the gas turbine device as a heat source.
, a steam turbine device 40 that uses steam generated in the exhaust heat recovery boiler as driving steam, and a denitrification device 31 that removes NOx components from combustion gas discharged from the gas turbine device. The gas turbine device 10 includes a compressor 11 that pressurizes the introduced air 4, a combustor 14 that burns the pressurized air together with fuel supplied from the fuel system 5, and a turbine 12 that is driven by the combustion gas generated by combustion. and,
It is equipped with a generator 13 that takes the load. Further, the exhaust heat recovery boiler 20 has a superheater 21, an evaporator 22, a economizer 23, and a chimney 24 along the upstream to downstream of the combustion gas flow led from the gas turbine device, and the steam generated in the superheater 21 is guided to the steam turbine device 40 through the steam piping 2;
From the station 40, the water is led to the energy saver 23 through the water supply pipe 1. Further, a denitration device 30 is installed between the evaporator 22 and the superheater 21 of the exhaust heat recovery boiler device 20. In this embodiment, as shown in FIG. 2, by installing an exhaust gas damper 27 built into the exhaust gas duct 25 from the exhaust heat recovery boiler device 20 to the chimney 24, the exhaust heat recovery boiler outlet damper is quickly closed when the gas turbine trips. Then, the pressure in the exhaust gas duct will rise abnormally due to the compressed air generated by the idle rotation of the gas turbine, so this abnormal pressure rise can be prevented by adjusting the closing speed of the exhaust heat recovery boiler outlet damper and using the exhaust gas damper (swing type damper) of the present invention. In addition, by installing the exhaust gas damper 27, when one unit is in operation and one unit is stopped, it is possible to prevent the combustion gas in operation from flowing back to the gas turbine device (exhaust heat recovery boiler) that is stopped. .

Next, embodiments of the present invention will be described using FIGS. 1, 2, 3, and 4. FIG. 1 shows a combined cycle plant equipped with measures to prevent abnormal pressure rise and backflow in the exhaust gas duct.

FIG. 2 shows a route of an exhaust gas duct that guides combustion gas discharged from the gas turbine device 10 to a chimney. in this case,
By installing the exhaust heat recovery boiler outlet damper 26 and the exhaust gas damper 27 when the gas turbine trips, it is possible to prevent an abnormal pressure increase in the exhaust gas duct and to prevent backflow from multiple units in operation.

FIG. 3 shows an installation diagram in which an exhaust heat recovery boiler outlet damper 26 and an exhaust gas damper 27 capable of preventing abnormal pressure rise and backflow are installed in the exhaust gas duct.

Figure 4 shows a detailed diagram of the exhaust gas damper. Since the exhaust gas duct 25 has a large cross-sectional area, the damper 27 used therein is designed to have the same function as a simple check valve in order to easily prevent abnormal pressure rise and to easily prevent backflow.

In addition, because the cross-sectional area is large, the structure of the damper is easy, and in order to prevent abnormal pressure rise and backflow, the partitions in the duct are finely divided, and the damper is installed in multiple stages to reduce the amount of gas relative to the damper. The damper can be opened and closed easily with less contact, and abnormal pressure rise and backflow can be prevented. That is, in FIG. 4, the damper main body 27a is attached to the rotating shaft 28 together with the support 36, and the end of the damper main body 27a is fixed by the presence of the stopper 35.
It is designed to only open in one direction. And 3
0 is a sealing material, 29 is a partition, 3 is a gas flow, and 9 is a counterflow gas flow.

In addition, the following modifications can be considered in the present invention including the above.

(1) When the exhaust gas ducts connected to multiple gas turbine devices are combined and the exhaust gas ducts have a - structure, two units are in operation and one unit is stopped, or one unit is in operation and two units are stopped. The structure prevents exhaust gas from flowing back into the duct when the system is not running.

(2) When the gas turbine trips, the damper at the exhaust heat recovery boiler outlet is closed to prevent backflow from the operating gas turbine, but in the closed state, the gas turbine may suddenly stop rotating. Since this is not possible, the structure allows air to be taken in during idling and exhausted when continuing to exhaust to the chimney side.

(3) When the exhaust gas ducts connected to multiple gas turbine devices are combined and the exhaust gas duct has a structure of -, two units are operating and one unit is stopped, or one unit is operating and two units are stopped, A structure that allows the exhaust gas damper to be opened when starting a stopped gas turbine without causing the exhaust gas during operation to flow back.

(4) By merging the exhaust gas ducts connected to multiple gas turbine devices, it is possible to prevent abnormal pressure rise and reverse flow in the exhaust gas ducts with a structure of 1-2. A structure that allows the gas turbine to start up without backflow of exhaust gas.

〔Effect of the invention〕

According to the present invention, the exhaust gas ducts from the gas turbine can be merged by installing a backflow prevention and abnormal pressure rise prevention damper in the exhaust gas duct that guides the combustion gas discharged from the gas turbine device to the chimney.

[Brief explanation of the drawing]

Figures 1, 2, 3, and 4 show examples of backflow prevention and abnormal pressure rise prevention lines in exhaust gas ducts to which the present invention is applied, and Figure 1 shows a composite line equipped with backflow and abnormal pressure rise prevention lines. System diagram of the cycle plant; Figures 2, 3, and 4 are explanatory diagrams of the abnormal pressure rise prevention line and backflow prevention damper; Figure 5 is the system of a conventional combined cycle plant that combines a gas turbine and a steam turbine. Figure 6 is a layout diagram of the combined cycle plant. DESCRIPTION OF SYMBOLS 10... Gas turbine apparatus, 20... Exhaust heat recovery boiler, 25... Exhaust gas duct, 26... Damper, 2
7, 278... Abnormal pressure rise prevention and backflow prevention damper.

Claims (1)

[Claims] 1. In an exhaust gas duct that guides combustion gas discharged from a gas turbine device from an exhaust heat recovery boiler to a chimney, compressed air is sent through idle rotation when the gas turbine device trips, and the exhaust heat recovery An exhaust gas damper comprising a structure that prevents the exhaust gas duct and the exhaust heat recovery boiler from becoming abnormally high in pressure when the damper attached to the outlet of the boiler is closed.