JP2001149747A - Gaseous ammonia injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gaseous ammonia injection device capable of uniformizing the flow rate of the gaseous ammonia blown-off from plural nozzles belonging to the same group. SOLUTION: In the gaseous ammonia injection device 10, an injection pipe 52 is constituted of a stepwisely shrinking pipe. The injection pipe 52 is formed so that diameter of the injection pipe is becomes small toward the downstream side in the gaseous ammonia flow supplied to the injection pipe 52. In such a way, the flow rate of the gaseous ammonia blown-off from each of nozzles 34A-34D is uniformized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ammonia gas injection device, and more particularly to an ammonia gas injection device for injecting ammonia gas into combustion exhaust gas obtained by burning a sulfur-containing fuel.

[0002]

2. Description of the Related Art Conventionally, in a facility for treating a fuel exhaust gas containing sulfur, a method of removing SO ₂ by a wet desulfurizer is generally used. On the other hand, SO ₃ is mixed with steam to form a sulfuric acid mist, so it is not only difficult to remove it with a desulfurizer,
There is a problem that an acid such as sulfuric acid mist generated corrodes the electrostatic precipitator.

Therefore, in a fuel exhaust gas treatment apparatus containing sulfur, NH 4 is introduced before the exhaust gas is guided to a desulfurizer and an electric dust collector.
Neutralization is performed by injecting an alkaline gas such as ₃ into exhaust gas. At that time, NH ₃ and SO
The reaction of ₃ produces a solid of ammonium sulfate. This solid is collected by an electric dust collector, and the exhaust gas after passing through the electric dust collector is discharged to the atmosphere via a wet desulfurization device or the like.

It is desirable to inject the NH ₃ in accordance with the SO ₃ concentration. However, since there is no device for continuously monitoring SO ₃ , the leak NH ₃ after the dust collector is measured and the NH ₃ is injected. NH ₃ is controlling NH ₃ injection rate to be constant values.

[0005]

However, in the above-mentioned conventional method, the amount of NH ₃ injected corresponding to fluctuations in the load of the boiler, in particular, changes in the concentration of SO ₃ when the boiler is started and stopped, and uneven concentration due to drift in the flue. Is difficult to control.

[0006] It has been found that the difference in the concentration distribution of the SO ₃ concentration in the exhaust gas duct is about 30% or more, and the conventional method has the problem that NH ₃ is locally excessive or deficient in the exhaust gas duct. Occurs. When NH ₃ is insufficient, the reaction is not completely performed, and acidic ammonium sulfate or the like is generated.
The dust adhering to the dust collecting electrode and discharge electrode of the subsequent dust collecting device is solidified and deposited due to moisture absorption and the temperature, and the dust collecting rate is reduced. Conversely, if the amount of NH ₃ is excessive,
There is a problem that the amount of leak NH ₃ increases.

To cope with the SO ₃ concentration distribution in the exhaust gas duct, a large number of nozzles are arranged on a section orthogonal to the axis of the duct, and the nozzles are divided into a plurality of groups to control the NH ₃ injection amount. There is a way to do that. In this method, a plurality of nozzles belonging to the same group are attached to one injection pipe, and the amount of NH ₃ supplied to each injection pipe is adjusted to control the NH ₃ injection amount for each group. Then, in the downstream region corresponding to each group, NH ₃
The concentration was measured, and the NH of each group was determined based on the measured value.
₃ By controlling the injection amount, S in the exhaust gas duct
Ammonia gas according to the O ₃ concentration distribution is injected.

[0008] However, the conventional method has a problem that the amount of NH ₃ blown out from a plurality of nozzles belonging to the same group varies, so that a local excess or deficiency of NH ₃ occurs.

The present invention has been made in view of the above circumstances, and has as its object to provide an ammonia gas injection device capable of equalizing the amount of ammonia gas blown from a plurality of nozzles belonging to the same group. I do.

[0010]

According to a first aspect of the present invention, a plurality of nozzles are attached to an injection pipe at intervals in an axial direction of the injection pipe, and the plurality of nozzles are connected to each other. In an ammonia gas injection device arranged on a cross section orthogonal to the axis of the duct through which the exhaust gas flows, and injecting ammonia gas into the exhaust gas from the plurality of nozzles via the injection pipe, inside the plurality of nozzles ,
Throttling means for reducing the flow rate of ammonia gas flowing inside each nozzle is provided, and the amount of air blown out from each nozzle by the throttle means is made uniform.

According to the first aspect of the present invention, since the throttling means (for example, the orifice plate) is provided in each nozzle, the amount of the ammonia gas blown out from each nozzle can be made uniform, and the localization of the ammonia gas can be achieved. Can be prevented.

According to a second aspect of the present invention, in order to achieve the above object, a plurality of nozzles are attached to an injection pipe at intervals in an axial direction of the injection pipe, and the plurality of nozzles are connected to a duct through which exhaust gas flows. In an ammonia gas injection device which is arranged on a cross section orthogonal to an axis and injects ammonia gas into the exhaust gas from the plurality of nozzles via the injection pipe, a flow path area of the injection pipe is in a flow direction of the ammonia gas. Is formed smaller on the downstream side than on the upstream side.

According to the second aspect of the present invention, the flow path area of the injection pipe is formed smaller on the downstream side in the flow direction of the ammonia gas than on the upstream side. The supply amount is made uniform. Therefore, the amount of ammonia gas blown out from each nozzle is made uniform, and local excess or deficiency of ammonia gas can be prevented. Further, according to the present invention, the amount of air blown out from each nozzle can be made uniform without increasing the internal resistance of each nozzle, so that the power for supplying ammonia gas to the injection pipe can be reduced. Can be.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the ammonia gas injection device according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a flow chart of a combustion gas processing facility to which an ammonia gas injection device 10 of the present embodiment is applied.

As shown in FIG.
The boiler 12, the denitration device 14, the air heater 16, the ammonia gas injection device 10, the NH ₃ detection device 18, the electric dust collecting device 20, the gas gas heat exchanger 22, the desulfurizing device 24, the wet electric dust collecting device 26, and the chimney 28 are included. It is configured to communicate with a duct.

The boiler 12 burns the fuel containing sulfur and burns the fuel containing about 400 ppm of dust, nitrogen oxides and sulfur oxides.
Exhaust gas of ℃ is discharged to the latter stage. A denitration device 14 and an air heater 16 are provided downstream of the boiler 12, and the exhaust gas is cooled by the denitration device 14 to 170 ° C. while removing nitrogen oxides. The air heater 16 cools the exhaust gas by the combustion air supplied to the boiler 12, whereby the boiler 12 is supplied with the heated combustion air.

The ammonia gas injection device 10 is disposed in a duct 30 that connects the denitration device 14 and the electrostatic precipitator 20, and injects a mixed gas of ammonia gas and air into exhaust gas passing through the duct 30. . Thereby, SO ₃ contained in the exhaust gas is neutralized, and a solid of ammonium sulfate is generated. This solid is removed together with the dust in the exhaust gas by the electrostatic precipitator 20 utilizing static electricity.

In the subsequent stage of the electric precipitator 20, a desulfurizer 24 and a wet electric precipitator 2 are connected via a gas-gas heat exchanger 22.
In the exhaust gas, SO ₂ in the exhaust gas is removed by a desulfurization device 24, and sulfuric acid mist in the exhaust gas is removed by a wet electric dust collector 26. A chimney 28 is connected to the wet type electrostatic precipitator 26 via the gas / gas heat exchanger 22, and the exhaust gas discharged from the wet type electric precipitator 26 is heated through the gas / gas heat exchanger 22. After that, it is discharged from the chimney 28 to the outside of the facility.

Next, the ammonia gas injection device 10 according to the present invention will be described.

FIG. 2 shows the ammonia gas injection device 10 and N
FIG. ₃ is a perspective view illustrating a structure of an H ₃ detection device 18. As shown in FIG.
Are provided on a cross section of the duct 30 in the axial direction, and a number of nozzles (only some of which are shown) are provided. The plurality of nozzles 34, 34.
Is divided by a certain area on its axial cross section,
.. Are grouped so that the same number of nozzles 34, 34,. The following is an example in which the inside of the duct 30 having a height of 4 m and a width of 7 m is divided into 1 m ² having a height of 1 m and a width of 1 m, and four nozzles 34 are vertically arranged in one section. explain.

As shown in FIG. 2, the ammonia gas injection device 10 has seven mother tubes 32 (only one is shown) installed at intervals of 1 m in the horizontal direction on the axial section of the duct 30. I have. The mother pipe 32 is vertically arranged at the center of each section. As shown in FIGS. 3 and 4, 16 nozzles 34, 34,... Are arranged at equal intervals of 0.25 m on the downstream side with respect to the flow of the exhaust gas.

Inside the mother pipe 32, four injection pipes 36,
Are inserted at regular intervals along the axial direction of the duct 30 and in the vertical direction. The injection pipe 36 is formed with a constant inner diameter and has four nozzles 3 each.
4, 34 ... are communicated. Therefore, each injection tube 3
By controlling the flow rate of the ammonia gas supplied to the nozzle 6, the amount of blown air from the four nozzles 34 is controlled simultaneously. Thus, the amount of blown air from the nozzles 34, 34,... Is controlled in groups of four. Here, the four nozzles 34, 34,... Belonging to the same group are referred to as 34A, 34B, 34C, 34D in order from the upper side.

As shown in FIG. 2, the injection pipe 36 is provided with a flow control means 38 such as a flow meter and a flow control valve. The flow control means 38 includes an ammonia gas supply pump (not shown). Connected. Each flow control means 38
Is connected to the control device 40 as shown in FIG. 1, and the ammonia gas supply amount is controlled by a command signal from the control device 40. Therefore, the control device 40 controls the supply amount of ammonia gas for each injection pipe 36, and controls the amount of ammonia gas blown out from the nozzles 34, 34 for each group. Thereby, the duct 30
In the axial section, the injection amount of ammonia gas is controlled every 1 m ² .

As shown in FIG. 5A, the inside of the nozzle 34 has a double structure comprising an inner tube 44 and an outer tube 46 having a coaxial 43, and ammonia gas flows through the inner tube 44. The air flows inside the outer tube 46 (that is, outside the inner tube 44). As a result, air is blown around the ammonia gas blown out from the inner pipe 44, so that the ammonia gas immediately after blown is prevented from directly contacting the exhaust gas. Thus, it is possible to prevent ammonium sulfate from being generated in the vicinity of the injection port of the nozzle 34.

The inner tube 44 and the outer tube 46 have tapered ends at the injection port side. Thereby, the flow of the ammonia gas and the air is rectified at the ends of the inner pipe 44 and the outer pipe 46. That is, as shown in FIG. 5B, the ammonia gas and the air do not generate a vortex downstream of the end faces of the inner pipe 44 and the outer pipe 46. The inner pipe 4
The outer tube 4 and the outer tube 46 may have a sharp end at the injection port side, and may have an inclined surface formed on the inner peripheral surface side.

As shown in FIG. 6, an orifice plate 48 having a hole with an orifice diameter d is mounted inside the inner tube 44. The relationship between the orifice diameter d and the nozzle diameter D will be described later in detail.

FIG. 8 is a plan view of the ammonia gas injection device 10 shown in FIG.

As shown in the figure, the mother pipe 32 is formed in a substantially elliptical shape, and has a downstream end formed at an acute angle with respect to the flow direction of the exhaust gas.
4 are arranged. Thereby, the flow of the exhaust gas in the vicinity of the nozzle 34 is rectified, and the generation of a vortex in the vicinity of the nozzle 34 is suppressed. Therefore, the ammonia gas blown out from the nozzle 34 is not entrained in the swirl of the exhaust gas, and it is possible to prevent dust from adhering to the ejection port of the nozzle 34 and causing enlargement.

On the other hand, the NH ₃ detector 18 shown in FIG.
Are provided at the downstream side of the duct 30, that is, at the entrance of the electric precipitator 20 (see FIG. 1).
2 ... This measurement sensor 42 is
At a distance of 1 second or more after the residence time on the downstream side, and is disposed at the center of a section of the duct 30 divided on the axial cross section at intervals of 1 m ² . That is, each measurement sensor 42 is installed facing the center of the nozzles 34A to 34D.

The measuring sensor 4 of the NH ₃ detecting device 18
Are connected to the control device 40 as shown in FIG. The control device 40 performs arithmetic processing on the measurement values of the respective measurement sensors 42 and sends the result to the flow control means 38 as a command signal. Thereby, the flow rate of ammonia gas supplied to each injection pipe 36 is controlled, and an appropriate amount of ammonia gas is blown out from the nozzles 34A to 34D facing each measurement sensor 42.

Next, the operation of the ammonia gas injection device 10 configured as described above will be described.

Four nozzles 34A belonging to the same group
To 34D are one injection pipe 36 formed with a constant inner diameter.
, The ammonia gas supplied to the injection pipe 36 is distributed to the four nozzles 34A to 34D and injected. Therefore, when the orifice plate 48 is not installed inside the nozzle 34, the amount of the blown-out airflow of the ammonia gas is smaller as the nozzle 34 is arranged on the upstream side (ie, the upper side), and is arranged on the downstream side (ie, the lower side). The blown air amount of the ammonia gas increases as the nozzle 34 is set.

FIG. 11 is a diagram showing the blowing speed of the ammonia gas for each nozzle. As shown by the dotted line in FIG. 11, the conventional ammonia gas injection device has a large blowing speed of the nozzle 34A, The blowing wind speed of 34D is small.
As described above, when there is a variation in the blowing air speed blown out from the nozzles 34A to 34D of the same group, the amount of ammonia gas locally becomes excessive or deficient.

On the other hand, as shown in FIG. 6, the ammonia gas injection device 10 of the present embodiment
The orifice plate 48 is mounted inside the .about.34D. Therefore, the blowing wind speed from each of the nozzles 34A to 34D is made uniform according to the orifice diameter d of the orifice plate 48.

FIG. 7 shows the effect of the orifice diameter d on the blowing wind speed.
And Vn / Vave with respect to d / D. Here, Vn represents each of the nozzles 34A to 34D.
The velocity of the ammonia gas blown from the
ave is the average blowing wind speed of the nozzles 34A to 34D.

As shown in the figure, as the orifice diameter d becomes smaller than the nozzle diameter D, the difference in the blowing air speed between the nozzles 34A and 34D becomes smaller. Since the difference between the nozzles 34A and 34D is the largest among the nozzles 34A to 34D, when the difference between the nozzles 34A and 34D is small, the blowing air speeds of all the nozzles 34A to 34D are made uniform. That is, the smaller the orifice diameter d, the more uniform the blown air velocity of all the nozzles 34A to 34D. Therefore, the nozzles 34A to 34A
In order to make the blowing air speed of D uniform, it is preferable to reduce the orifice diameter d. In particular, when d / D is set to 0.5 or less, the variation of the blowing air speed of the nozzles 34A to 34D becomes ± 0.5%. Within.

As described above, according to the ammonia gas injection device 10 of the present embodiment, since the orifice plate 48 is provided inside the nozzle 34, the blowing speed from the nozzles 34A to 34D can be made uniform. As a result, since the ammonia gas having substantially the same air volume is injected from each of the nozzles 34A to 34D, local excess or deficiency of the ammonia gas can be suppressed, and adverse effects on the subsequent processing apparatus due to excess or deficiency of the ammonia gas can be suppressed. can do.

Further, in the ammonia gas injection device 10, the inner pipe 44 and the outer pipe 46 of the nozzle 34 are tapered at the injection port end, so that a vortex is generated immediately after the ammonia gas and the air are blown out. Never do. further,
Since the mother pipe 32 is formed in a substantially elliptical shape and its downstream end is formed at an acute angle, the exhaust gas does not generate a vortex near the nozzle 34. Therefore, since ammonia gas, air and exhaust gas do not generate a vortex,
The eddy current can prevent the ammonium sulfate solid from adhering to the end of the nozzle 34 and increasing its size.

The shape of the mother tube 32 is not limited to the above-described embodiment. For example, as shown in FIG.
The downstream end of the mother pipe 32 may be formed in a V-shape. In this case, the ammonia gas is easily diffused, and the generation of the vortex near the nozzle 34 is prevented.

Next, an ammonia gas injection device according to a second embodiment will be described.

As shown in FIG. 10, in the ammonia gas injection device of the second embodiment, the injection tube 52 is a step-shrink tube having a small diameter from the upper part to the lower part. That is, assuming that the diameter of the injection pipe 52 at the position of the nozzle 34A is a,
The diameter at the position of the nozzle 34B is 0.87a, the nozzle 3
The diameter at the position of 4C is 0.61a, and the diameter at the position of the nozzle 34D is 0.53a. Further, the nozzles 34A to 34D are formed with a constant diameter of 0.53a, and no control resistance such as an orifice plate is provided inside. The description of members that are the same as or similar to those of the first embodiment will be omitted.

In the ammonia gas injection device configured as described above, since the injection pipe 52 is formed of a step-contraction pipe and the flow area of the ammonia gas is gradually reduced, the ammonia gas is supplied to all the nozzles 34A to 34D. Is easy to flow.
For example, since the diameter of the injection pipe 52 at the position of the nozzle 34A is reduced to 0.78a at the position of the nozzle 34B, the ammonia gas flowing from the position of the nozzle 34A to the position of the nozzle 34B is Becomes a resistance and flows sufficiently to the nozzle 34A. Similarly, the ammonia gas sufficiently flows into the nozzles 34B and 34C, and the ammonia gas does not concentrate and flow only in the nozzle 34D. That is, it is possible to make the blowing wind speed of each of the nozzles 34A to 34D uniform, and to prevent the ammonia concentration from becoming locally non-uniform.

FIG. 11 shows the state of each of the nozzles 34A to 34D.
It shows the distribution of the blowing wind speed. Solid line shown in the figure
Means that the flow rate supplied to the injection pipe 52 is 100, 200, 30
0m ^Three/ H, Vn / Vave is calculated by
Are shown for each of the files 34A to 34D. Also shown in the figure
The dotted line indicates that the injection tube was formed with a constant inner diameter (ie,
Vn / Vave of the conventional device).

As shown in the figure, when a step contraction tube is used as the injection tube 52, each nozzle 34
It can be seen that the blowing wind speed from A to 34D is greatly uniformed. In particular, as compared with the case where the injection pipe is formed with a constant inner diameter, the blowing wind speed of the nozzles 34A and 34D is greatly improved, and the blowing wind speeds of all the nozzles 34A to 34D fall within a range of ± 5%.

As described above, according to the ammonia gas injection device of the second embodiment, since the step-contraction tube is used as the injection tube 52, the blowing speed of the gas blown from each of the nozzles 34A to 34D can be made uniform. it can. Thereby, it is possible to prevent the amount of ammonia gas from being locally excessive or deficient in each section.

The ammonia gas injection device according to the second embodiment does not increase the internal resistance of the nozzles 34A to 34D, so that the pressure loss at the nozzles 34A to 34D is small.

FIG. 12 shows a case where the injection pipe 52 is a step-shrink pipe and an orifice plate 48 inside the nozzles 34A to 34D.
FIG. 6 is a diagram comparing a differential pressure with a case where a pressure difference is provided. Here, the differential pressure is a differential pressure in the injection pipe 36 immediately before the nozzle 34D, and the orifice plate 48 used has a d / D = 0.5. The blowout flow rate of ammonia gas at the time of the measurement is 80 to 300 m ³ / h.

As shown in the figure, when the injection pipe 52 is a step-contraction pipe, the pressure difference becomes significantly smaller than when the orifice plate 48 is used inside the nozzles 34A to 34D. 7 m / s, the differential pressure is 1/1
It becomes 0. Therefore, when the injection pipe 52 is a step contraction pipe, the burden on the ammonia gas supply device that supplies the injection pipe 52 can be reduced.

As described above, the ammonia injection apparatus according to the second embodiment can equalize the blowing air speed of each of the nozzles 34A to 34D without installing a control resistor inside the nozzles 34A to 34D. The load on a supply device (not shown) such as a pump for supplying ammonia gas to each injection pipe 52 can be reduced.

The injection tube 52 may be a step-shrink tube, and an orifice plate 48 having a relatively large orifice diameter d may be provided inside the nozzles 34A to 34D. Thereby, the amount of air blown out from the nozzles 34A to 34D can be made more uniform without greatly increasing the load on the supply device.

In the above embodiment, the NH ₃ detecting device 18 is provided, and each of the injection pipes 3 of the ammonia gas injection device 10 is made to correspond to the NH ₃ concentration detected by the detecting device 18.
6. The ammonia gas discharge amount is controlled by the method 6. If the ammonia gas appropriate injection amount in each section in the duct is obtained in advance by experiments and the like, and the ammonia gas injection amount of each injection pipe 36 is set accordingly, No NH ₃ detector 18 is required.

[0053]

As described above, according to the ammonia gas injection apparatus according to the present invention, since the throttle means is provided in each nozzle, the amount of ammonia gas blown out from the nozzles of the same group can be made uniform. Thus, local excess or deficiency of ammonia gas can be prevented.

Further, according to the present invention, the flow area of the injection pipe is formed smaller on the downstream side in the flow direction of the ammonia gas than on the upstream side, so that the flow rate of the ammonia gas supplied from the injection pipe to each nozzle is made uniform. It is possible to prevent a local excess or deficiency of the ammonia gas.

[Brief description of the drawings]

FIG. 1 is a flow chart of a combustion gas processing facility to which an ammonia gas injection device according to the present invention is applied.

FIG. 2 is a perspective view showing the structure of an ammonia gas injection device according to the present invention.

FIG. 3 is a longitudinal sectional view of the ammonia gas injection device shown in FIG. 2;

FIG. 4 is a side view of the ammonia gas injection device shown in FIG. 2;

FIG. 5 is a half sectional view showing the internal structure of the nozzle.

FIG. 6 is a sectional view showing the internal structure of the inner tube of the nozzle.

FIG. 7 is a diagram showing the effect of orifice diameter on wind speed.

8 is a plan view of the ammonia gas injection device shown in FIG.

FIG. 9 is a plan view of an ammonia gas injection device showing a mother pipe having a shape different from that of FIG. 8;

FIG. 10 shows a second embodiment of the ammonia gas injection device according to the present invention.
Side view showing an injection tube which is a characteristic part of the embodiment of the present invention.

FIG. 11 is a diagram showing a wind speed distribution in each nozzle.

FIG. 12 is an explanatory view showing the operation of the ammonia gas injection device of FIG.

[Explanation of symbols]

10 ... Ammonia gas injection device, 12 ... Boiler, 14 ...
Denitration equipment, 16 air heater, 18 NH ₃ detector,
Reference numeral 20: electric dust collector, 22: gas-gas heat exchanger, 24 ...
Desulfurizer 26, wet electric precipitator 28, chimney 30,
... duct, 32 ... mother pipe, 34 ... nozzle, 36 ... injection pipe,
38 flow rate control means, 40 control device, 42 measurement sensor, 44 inner tube, 46 outer tube, 48 orifice plate

Continuation of the front page (72) Inventor Sadao Sakakibara 537 Uehongo, Matsudo-shi, Chiba F-term in Hitachi Plant Construction Machinery Engineering Co., Ltd. 4D002 AA02 AC01 BA03 BA13 BA14 BA16 CA01 CA11 CA13 DA07 EA02 FA06 GA02 GA03 GB01 GB03 GB06

Claims (4)

[Claims] A plurality of nozzles are attached to an injection pipe at intervals in an axial direction of the injection pipe, and the plurality of nozzles are arranged on a cross section orthogonal to an axis of a duct through which exhaust gas flows. In the ammonia gas injection device for injecting ammonia gas into the exhaust gas from the plurality of nozzles through, a throttle means for reducing the flow rate of ammonia gas flowing inside each nozzle is provided inside the plurality of nozzles, An ammonia gas injection apparatus characterized in that the amount of ammonia gas blown out from each nozzle is made uniform by the throttle means. 2. A plurality of nozzles are attached to an injection pipe at intervals in an axial direction of the injection pipe, and the plurality of nozzles are arranged on a cross section orthogonal to an axis of a duct through which exhaust gas flows. In the ammonia gas injection device for injecting ammonia gas into the exhaust gas from the plurality of nozzles via, the flow path area of the injection pipe, the downstream side in the flow direction of the ammonia gas is formed smaller than the upstream side Characteristic ammonia gas injection device. 3. A section perpendicular to the axis of the duct is divided into a plurality of sections, and the injection pipe is formed by grouping nozzles included in the section, and a supply amount of ammonia gas supplied to the injection pipe is set for each injection pipe. 2. The method according to claim 1, wherein
Or the ammonia gas injection device according to 2. 4. The ammonia gas injection device according to claim 1, wherein an end of the nozzle on the side of the injection port is pointed.