JPH044021A - High-temperature exhaust gas denitrification device - Google Patents

Abstract

PURPOSE:To improve denitrification efficiency by providing a mixer which introduces the atm. air therein and mixes the air with exhaust gases in a high- temp. exhaust gas system before a denitrification reactor. CONSTITUTION:This high-temp. exhaust gas denitrification device has the denitrification reactor 3 which converts the NOx in the exhaust gases to harmless N2 by bringing the NOx into reaction with ammonia in the presence of a catalyst in the high-temp. exhaust combustion gas system discharged from a gas turbine 1, etc. The mixer 2 which sucks the atm. air or introduces the atm. air under pressurization therein and mixes the air with the exhaust gases is provided in the high-temp. exhaust gas system before the denitrification reactor 3. A means for controlling the cooling to lower the temp. of the exhaust gases to the temp. range where the denitrification reaction efficiency of the catalyst to be used is high is provided. Since the high-temp. exhaust gases can be freely controlled and cooled down to the temp. range of the highest denitrification reaction efficiency, the NOx in the exhaust gas is denitrified with the high efficiency at the smaller amt. of the catalyst to be used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a denitrification device for high-temperature combustion gas discharged from a gas turbine or the like, and in particular, the present invention relates to a denitrification device for high-temperature combustion gas discharged from a gas turbine, etc. The present invention relates to a denitrification device that improves denitrification efficiency by controlling cooling to a temperature suitable for denitrification reactions.

[Conventional technology]

With the recent growth in nuclear power generation, there is a tendency for thermal power generation to shift from base load use to load adjustment use. especially,
Power generation using a gas turbine is easy and quick to start and stop, so there are cases where the gas turbine is used alone for seasonal thermal power, etc., and the exhaust gas temperature is 600-700℃.
The temperature will be as high as 00℃.

However, environmental regulations are becoming stricter year by year, and it is natural that nitrogen oxides (NOx) must also be kept within regulatory limits.

FIG. 7 shows an example of a conventional high-temperature exhaust gas denitrification system. That is, this is a system in which the denitrification reactor 3 is placed directly at the exhaust gas outlet of the gas turbine to perform denitrification treatment on the exhaust gas.

Generally, the performance of the denitrification catalyst is as shown in Figure 6(a).
It is best to use the catalyst at around 350°C; catalysts that can withstand high temperatures tend to have lower denitrification performance. Therefore,
When directly denitrifying high-temperature exhaust gas, Fig. 6(b)
As shown in Figure 2, as the denitrification temperature increases, a large amount of catalyst becomes necessary.

For this reason, as a denitrification method for high-temperature exhaust gas, a method is proposed in which water and ammonia are injected to suppress the high-temperature region of the exhaust gas and to improve the durability and denitrification performance of the denitrification catalyst (Japanese Patent Application Laid-Open No. 1999-11991).
No. 330) or a device that sprays cooling water into high-temperature exhaust gas to control the exhaust gas temperature to the optimum temperature (Utility Model Publication No. 1
-80617) and the like have been proposed.

[Problem to be solved by the invention]

As mentioned above, conventional denitrification systems for high-temperature exhaust gas have often been able to perform denitrification by filling a large amount of catalyst, ignoring economic efficiency, or in some cases, have been unable to perform denitrification treatment at all.

In addition, methods to lower the temperature of high-temperature exhaust gas by injecting water and ammonia into the high-temperature exhaust gas system or spraying cooling water are methods that evenly mix cooling water into the exhaust gas to maintain the appropriate temperature of the exhaust gas. Moreover, it was difficult to lower the wastewater uniformly, and there were also problems in treating the wastewater produced.

An object of the present invention is to solve the above-mentioned problems in the prior art, and to achieve the highest denitrification performance in a catalyst using the temperature of the exhaust gas by introducing cooling air or steam into the high-temperature exhaust gas. Cool the area evenly,
It is an object of the present invention to provide a denitrification device for high-temperature exhaust gas that can reduce the amount of catalyst charged, can denitrify high-temperature exhaust gas that has conventionally been impossible to denitrate, and has high denitrification efficiency.

[Means to solve the problem]

In order to achieve the above object of the present invention, a mixer is provided at the outlet of high-temperature combustion exhaust gas discharged from a gas turbine or the like to sufficiently mix the high-temperature exhaust gas with room temperature cooling air, etc., and the temperature of the exhaust gas is The denitrification process is performed by uniformly lowering the temperature of the exhaust gas to a predetermined temperature range, and by lowering the temperature of the exhaust gas introduced into the denitrification reactor provided downstream to the optimal denitrification temperature in advance.

The present invention provides a denitrification reactor for high-temperature combustion exhaust gas systems discharged from gas turbines, etc., which reacts NOx (nitrogen oxides) in the exhaust gas with ammonia under a catalyst to convert it into harmless N2 (nitrogen). In a high-temperature exhaust gas denitrification device equipped with a high-temperature exhaust gas denitrification system, a mixer is installed in the high-temperature exhaust gas system upstream of the denitrification reactor to suck or pressurize atmospheric air and mix it with the exhaust gas. This is a high-temperature exhaust gas denitrification device equipped with means for controlling cooling to a highly efficient temperature range.

The cooling control means for high-temperature exhaust gas in the present invention includes means for providing a venturi mechanism in the high-temperature exhaust gas system and controlling the temperature of the exhaust gas by directly sucking and mixing the atmosphere with the venturi mechanism, or by sucking and pressurizing the atmosphere using a fan or compressor. Introduced into the high-temperature exhaust gas system and mixed with exhaust gas,
By using a combination of means for cooling and controlling the exhaust gas temperature, or means for directly sucking and mixing atmospheric air by providing a venturi mechanism in the high-temperature exhaust gas system, and means for increasing the pressure of atmospheric air using a fan or compressor and introducing it and mixing it with the exhaust gas, The exhaust gas temperature can be controlled by cooling. Furthermore, the high-temperature exhaust gas cooling control means of the present invention can also cool and control the exhaust gas temperature by introducing and mixing water vapor into the high-temperature exhaust gas system.

And, in the high temperature exhaust gas cooling control means of the present invention,
In the cooling fluid supply system of the cooling control means.

It is equipped with a fluid flow control damper and a flow control valve for controlling the exhaust gas temperature, and has means for cooling and controlling the exhaust gas temperature, and also has ammonia for denitrification reaction in the cooling fluid supply system of the cooling control means. It is also possible to provide a means for injecting and mixing ammonia into the cooling fluid to control the exhaust gas temperature by cooling.

[For production]

The temperature of the exhaust gas inlet to the denitrification reactor is uniformly lowered and the denitrification process is performed by controlling it to the temperature range where the catalyst used has the highest denitrification ability, achieving highly efficient denitrification reactions with a small amount of catalyst charged. It becomes possible to do so.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in more detail with reference to one drawing. FIG. 1 shows an example of the denitrification system in the denitrification apparatus of the present invention.

As shown in the figure, a mixer 2 is installed at the outlet of the gas turbine 1 to mix atmospheric air at room temperature, and after the temperature of the treated gas is lowered to the optimum temperature for the denitrification reaction, it is introduced into the denitrification reactor 3. This method removes NOx from exhaust gas.

For example, when treating exhaust gas flowing into the denitrification reaction 13 at 650'C, as shown in Figure 6(b), conventionally
Approximately 10 times the amount of denitration catalyst was required compared to the amount of catalyst used in the 50°C treatment, but by lowering the exhaust gas temperature to 500°C, the amount of catalyst stabilized at approximately twice the amount as shown in Figure 6 (d). denitrification is possible.

FIGS. 2 to 5 are specific examples showing a process flow when a cooling fluid such as atmospheric air is mixed in the high-temperature exhaust gas denitrification apparatus of the present invention and the denitrification reaction temperature is controlled to the optimum temperature.
An example of the cooling fluid mixing means, the exhaust gas temperature control method, and the injection position of NH and (ammonia) for denitrification is shown.

FIG. 2 shows a method in which a venturi 4 is used to directly suck and mix atmospheric air to control cooling.

Figure 3 shows air being sucked and pressurized by a fan 5, and a mixer 2
The following shows a method for controlling cooling by feeding

FIG. 4 shows a control system in which atmospheric air is sucked and pressurized using compressed air 6 and venturi 7, and is then sent to mixer 2 for cooling.

FIG. 5 shows a method of supplying water vapor 8 to the mixer 2 and controlling the temperature of the high-temperature exhaust gas by cooling it.

〔Effect of the invention〕

As explained in detail above, according to the high-temperature exhaust gas denitrification device of the present invention, it is possible to freely control the cooling of the high-temperature exhaust gas to the temperature range that provides the best denitrification reaction efficiency, so it is possible to use a small amount of catalyst. NOx in exhaust gas can be denitrated with high efficiency.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a system flow of a high-temperature exhaust gas denitrification device exemplified in an embodiment of the present invention, FIGS. 2 to 5 are system diagrams showing specific embodiments in an embodiment of the present invention, and FIG. (,) is the exhaust gas temperature of the denitrification catalyst and the catalyst performance (
Figure 6(b) is a graph showing the relationship between
A graph showing the amount of catalyst filling (ratio) for each exhaust gas temperature when using the catalyst shown in a), Figure 6(c) shows the increase in the amount of catalyst filling relative to the amount of air mixed to lower the exhaust gas temperature. Figure 6(d) is a graph showing the total catalyst filling amount (ratio) calculated from Figures 6(b) and 6(c). Figure 7 is a graph showing the ratio in a conventional high-temperature exhaust gas denitrification device. It is a figure showing a denitrification system flow. 1... Gas turbine 2... Mixer 3... Denitration reactor 4... Venturi 5... Fan
6...Compressed air 7...Venturi 8.
...Steam 9...Damper 10...Silencer 11...Control valve

Claims (1)

[Claims] 1. In the high-temperature combustion exhaust gas system discharged from a gas turbine, etc., NO_x (nitrogen oxides) in the exhaust gas is converted to harmless N_2 (nitrogen) by reacting with ammonia under a catalyst. In a high-temperature exhaust gas denitrification equipment equipped with a denitrification reactor,
A mixer is installed in the high-temperature exhaust gas system upstream of the denitrification reactor to suck or pressurize atmospheric air and mix it with the exhaust gas, and the temperature of the exhaust gas is controlled to be within a temperature range where the denitrification reaction efficiency of the catalyst used is high. A high-temperature exhaust gas denitrification device characterized by being provided with a means. 2. The high-temperature exhaust gas cooling control means according to claim 1,
A high-temperature exhaust gas denitrification device, characterized in that a venturi mechanism is provided in a high-temperature exhaust gas system, and the venturi mechanism directly sucks and mixes atmospheric air to cool and control the exhaust gas temperature. 3. The high-temperature exhaust gas cooling control means according to claim 1,
A high-temperature exhaust gas denitrification device characterized by being a means for cooling and controlling the exhaust gas temperature by suctioning and pressurizing atmospheric air using a fan or compressor, introducing it into a high-temperature exhaust gas system, and mixing it with the exhaust gas. 4. The high-temperature exhaust gas cooling control means according to claim 1,
By providing a venturi mechanism in the high-temperature exhaust gas system to directly suck and mix the atmosphere, and by using a fan or compressor to increase the pressure of the atmosphere and introduce it and mix it with the exhaust gas,
A high-temperature exhaust gas denitrification device characterized by cooling and controlling exhaust gas temperature. 5. The high-temperature exhaust gas cooling control means according to claim 1,
A high-temperature exhaust gas denitrification device characterized by being a means for introducing and mixing water vapor into a high-temperature exhaust gas system to cool and control the exhaust gas temperature. 6. In the exhaust gas temperature cooling control means according to claim 1, 2, 3, 4 or 5, the exhaust gas temperature is controlled in the cooling fluid supply system of the cooling control means. 1. A high-temperature exhaust gas denitrification device, comprising a fluid flow rate control damper and a flow rate control valve for control, and means for cooling and controlling exhaust gas temperature. 7. In the exhaust gas temperature cooling control means according to any one of claims 1 to 6, means for injecting and mixing ammonia for denitrification reaction into the cooling fluid supply system of the cooling control means. 1. A high-temperature exhaust gas denitrification device comprising: a means for cooling and controlling exhaust gas temperature by mixing ammonia into the cooling fluid.