JPS6214922A - Complex plant denitrification equipment - Google Patents

Abstract

PURPOSE:To denitrate even outlet flue gas at the time of the starting of a gas turbine, by providing a bypass line between the upstream side of the exhaust gas line provided to the outlet of a gas turbine and the upstream side of a denitration apparatus. CONSTITUTION:The opening degree of the damper 9 of a bypass line 10 is preliminarily made large at the time of the starting of a gas turbine 1 and the residual gas after outlet flue gas was sent to a high pressure boiler 4 is sent to a denitration apparatus 6 by the bypass line 10 and ammonia is injected to said line from an ammonia injection line 5 to perform denitration in the denitration apparatus 6. The opening degree of the damper 9 is gradually reduced and, when the temp. of the outlet flue gas of the high pressure boiler 4 rises to 300-400 deg.C, the damper 9 is closed. Because high temp. exhaust gas is introduced into the denitration apparatus 6, the damper 11 of an exhaust line 12 is closed when high temp. low NoX exhaust gas is exhausted from the denitration apparatus 6 and the amount of high temp. low NoX flue gas introduced into a low pressure boiler 7 is limited to discharge said flue gas from a chimney 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a denitrification device for a composite plant that combines a gas turbine and a waste heat boiler.

[Prior Art] In a composite plant that combines a gas turbine driven by combustion gas and a waste heat boiler that recovers heat from the exhaust gas of the gas turbine, the exhaust gas of the gas turbine a is transferred to the high pressure boiler b as shown in Fig. 2. Heat is recovered by low pressure boiler C, and nitrogen oxides (NOx >
In order to reduce this, a denitrification device d is installed between the high pressure boiler b and the low pressure boiler C, and an ammonia injection line e is provided immediately before the denitrification device d. In the figure, f indicates a reheating device and 9 indicates a chimney.

As a result, the heat in the exhaust gas discharged from the gas turbine a during normal operation is effectively recovered, NOx is also reduced, and pollution is eliminated.

[Problems to be Solved by the Invention] However, when the gas turbine a is started, the exhaust gas temperature at the outlet of the gas turbine a reaches the rated gas temperature (400 to 500
'C), but because the boiler tube is thick on the high pressure boiler b side, there is a limit to the rate of increase in canned water temperature, so it takes several tens of minutes to reach the rated load.

Therefore, during startup, the exhaust gas from the gas turbine a must be partially exhausted into the chimney 9 by the bypass damper h until the high pressure boiler b reaches its rated load. It had not been done. This also applies when an accident occurs in the boiler system.

If the exhaust gas discharged through the bypass line is to be denitrified during startup, an ammonia injection line e' and a denitrification device d' should be separately installed between the bypass damper h and the chimney 9', as shown in Fig. 3. Alternatively, as shown in FIG. 4, it has been considered to separately provide an ammonia injection line e'' and a denitrification device d'' between the gas turbine a and the bypass damper h.

However, these methods require two sets of denitrification equipment, resulting in high equipment costs.

Means for Solving Problem F] In order to solve the above-mentioned conventional problems, the present invention provides an ammonia solution which is sequentially arranged in the boiler upstream side of the gas turbine outlet exhaust gas line and the boiler downstream side exhaust gas line. A composite plant denitrification device was constructed by connecting the injection line and the cough ammonia injection line connection inlet side of the denitrification device by a bypass line having a damper.

[Function] By switching the damper on the bypass line, when the turbine is started, the bypass line is opened and a part of the gas turbine outlet exhaust gas is guided to the denitrification device, and during steady operation, the bypass line is closed and all the outlet exhaust gas is sent to the boiler. Denitrification can be carried out by denitrification neck after the denitrification is conducted.

Therefore, the common denitrification device can denitrify the exhaust gas during startup and normal operation of the gas turbine.

[Example] Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 shows an embodiment of the present invention, in which a reheating device 3, a high pressure boiler 4, an ammonia injection line 5, a denitration device 6, a low pressure boiler 7 and a chimney 8 are connected to the outlet exhaust gas line 2 of a gas turbine 1 in order downstream. The upstream side of the reheating device 3 of the outlet exhaust gas line 2 and the upstream side of the connection part of the ammonia injection line 5 are connected by a bypass line 10 having a damper 9, and by switching the damper 9, the This allows the exhaust gas to be directly introduced into the denitrification device 6.

Further, the upstream side of the low pressure boiler 7 of the outlet exhaust gas line 2 and the chimney 8 are connected by an exhaust line 12 having a damper 11.

Here, the catalyst used in the denitrification device 6 has a temperature of 300 to 500'C because the exhaust gas temperature at the high pressure boiler 4 outlet is 300 to 400°C and the exhaust gas temperature at the gas turbine 1 outlet is 400 to 500'C. It is preferable to use a substance that can promote the denitrification reaction within a certain range. Or 300~400'C
You may use the denitrification catalyst for 400 to 500℃ by switching between the denitrification catalyst for
0 may be provided with a cooling device to lower the exhaust gas temperature to 300 to 400°C.

In such a configuration, when the gas turbine 1 is started, the opening degree of the damper 9 of the bypass line 10 is made large, and the outlet exhaust gas is sent to the high pressure boiler 4, and the remainder is sent to the denitrification device 6 via the bypass line 10, and the ammonia Injection line 5
Ammonia is injected and denitrified in the denitrification device 6.

The opening degree of the damper 9 is gradually reduced, and when the temperature of the exhaust gas at the outlet of the high pressure boiler 4 rises to 300 to 400°C, the damper 9 is closed.

During this time, high-temperature exhaust gas is introduced into the denitrification device 6, so when high-temperature, low-NOx exhaust gas is discharged from the denitrification device 6, the damper 11 of the exhaust line 12 is opened and the gas is introduced into the low-pressure boiler 2. Limiting the amount of high temperature and low NOx exhaust gas,
It will be discharged from the chimney 8. Furthermore, if the temperature decreases to some extent by passing through the denitrification device 6, there is no problem in introducing the denitrified exhaust gas into the low pressure boiler 7.

It should be noted that the denitrification device for a composite plant of the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[Effects of the Invention] As explained above, according to the denitrification device for a composite plant of the present invention, a bypass line is provided between the boiler upstream side of the gas turbine outlet exhaust gas line and the denitrification device upstream side, so that a new denitrification device is provided. It is possible to denitrify the exhaust gas at the outlet when the gas turbine is started without adding any equipment, and it is very useful as a pollution prevention measure, and exhibits various excellent effects such as low equipment costs.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one embodiment of the device of the present invention, FIG. 2 is a diagram showing an example of a conventional device, FIG. 3 is a diagram showing an improved example of the conventional device shown in FIG. FIG. 4 is a diagram showing another improved example of the conventional device shown in FIG. 2. 1 is a gas turbine, 2 is an outlet exhaust gas line, 4 is a high-pressure boiler, 5 is an ammonia injection line, 6 is a denitrification device, 8 is a chimney, 9 and 11 are dampers, 10 is a bypass line, 12
indicates the discharge line. -Hezo Gorge (Y) -,? Gorge
Mound

Claims (1)

[Claims] 1) The boiler upstream side of the gas turbine outlet exhaust gas line,
A denitrification device for a complex plant, characterized in that an ammonia injection line sequentially arranged in the exhaust gas line on the downstream side of the boiler and an inlet side of the ammonia injection line connection part of the denitrification device are connected by a bypass line having a damper.