JPH0924246A - Ammonia injection device in denitration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make distribution of ammonia uniform in the-section of an exhaust gas flow path and to increase the denitration efficiency by changing the directions and angles of both ammonia injection main pipe and spout port of an ammonia injection nozzle along the shape of the exhaust gas flow path in an exhaust gas duct. SOLUTION: The axial lines 5a of many ammonia injection main pipes 5 are placed in the vertical direction in the expansion part of the downstream part of an inlet duct 3. The main pipes 5 are sequentially provided in the uniform intervals in the section of an exhaust gas flow path. Two ammonia injection nozzles 6 are directed toward the downstream side of an exhaust gas flow and fitted to the ammonia injection main pipes 5, so that an angle θ at which an axial line Z1 parallel to the centerline Z of a boiler intersects a fitting centerline Y is changed in accordance with an expansion degree in the inlet duct 3. Further, both ammonia injection nozzles 6 are fitted at a constant setting angle β. In such a way, even if the shape of the flow path in the duct is changed, the direction and the setting angle of the ammonia injection main pipes and the injection nozzles are changed. Ammonia used as a reducing agent for denitration is uniformly distributed in the section of the exhaust gas flow path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ammonia injection device in a denitration device that uses ammonia as a reducing agent.

[0002]

In a denitration apparatus using ammonia as a reducing agent, it is necessary to inject ammonia so that it is evenly distributed in the exhaust gas in order to obtain a highly efficient denitration action.

In order to obtain such a uniform distribution of ammonia in the exhaust gas passage, a mixer for mixing ammonia and exhaust gas is provided in the duct upstream of the denitration catalytic reactor (hereinafter abbreviated as a reactor). Immediately upstream of the mixer, an ammonia injection nozzle and an ammonia injection mother tube to which the ammonia injection nozzle is attached are provided.

When the above-mentioned ammonia injection nozzle, mother tube, and mixer are installed, the installation space for these is usually limited in a power plant where a denitration catalyst device is installed. Therefore, as shown in FIG. A step is formed in the vertical direction between the downstream end and the reactor 2, and the ammonia injection mother tube 4 and the injection nozzle are provided along the step.

That is, in FIG. 7, the downstream end of the flue 1 and the reactor 2 are attached with a step in the vertical direction. Further, 3 is an inlet duct, 4 is an ammonia injection mother tube to which a large number of ammonia injection nozzles (not shown) are attached, and 9 is a mixer for mixing the ammonia injected from the injection nozzle and the exhaust gas.

The ammonia injection nozzles are respectively attached at right angles to the axis of the ammonia injection mother pipes 4 arranged in the height direction of the reactor 2, and the openings are located on the downstream side of the exhaust gas flow (reactor 2 side). ).

Therefore, in the above-mentioned conventional apparatus, when there is a vertical step between the end portion of the flue 1 and the reactor 2 as shown in FIG. Distribution of ammonia is small on the upper side of the reactor 2,
There is a problem in that the distribution of ammonia becomes non-uniform at the inlet of the reactor 2 and the denitrification efficiency decreases, as the amount increases in the central portion and the portion near the lower portion.

An object of the present invention is to provide a denitration device having an ammonia injection nozzle upstream of a denitration catalytic reactor in an exhaust gas passage, in which the distribution of ammonia introduced into the reactor is made uniform in the cross section of the exhaust gas passage to remove denitration. It is an object of the present invention to provide a denitration device having improved efficiency.

[0009]

According to the present invention, the direction and angle of an ammonia injection mother pipe for ejecting ammonia toward the inlet of a denitration catalytic reactor and an ammonia injection nozzle attached to the mother mother pipe are defined as follows. The gist is that it is changed along the exhaust gas flow path shape of the duct so that the ammonia ejected from the ammonia injection nozzle can be evenly distributed in the exhaust gas. A large number of ammonia injection mother tubes are installed in the exhaust gas flow upstream of the denitration catalyst reactor in a direction substantially perpendicular to the exhaust gas flow, and ammonia is injected from the ammonia injection nozzle attached to the same injection mother tube to remove the denitration catalyst. In an exhaust gas denitration apparatus that performs catalytic reduction by means of an exhaust gas, the ammonia injection mother pipe and the ammonia injection nozzle are Orientation and angle of the jetting ports of the nozzles along the flow path shape of the duct between the 応器 is that is disposed contain altered.

As a result, the plurality of ammonia injection mother tubes and the plurality of nozzles have different directions of the mother tubes and nozzles even if the shape of the duct flow passage is changed so as to be expanded downstream. Since the mounting angle is changed according to the shape of the flow path and the equipment is equipped, the ammonia ejected from the injection nozzle toward the reactor side is uniformly distributed in the exhaust gas flow path cross section at the reactor inlet. .

Therefore, ammonia is uniformly distributed in the exhaust gas and introduced into the denitration catalytic reactor, and the denitration efficiency is improved.

Preferably, two ammonia injection nozzles are attached to one ammonia injection mother pipe, and the attachment angle at the center of the ejection port is changed according to the flow path shape of the duct. Configure.

As a result, the mounting state of the ammonia injection nozzle on the mother pipe can be changed according to the shape of the flow path of the exhaust gas, and further fine adjustment for obtaining a uniform distribution of ammonia becomes possible.

Another feature of the present invention is to install a plurality of rectifying members for guiding the exhaust gas flow upstream of the ammonia injection mother pipe in the duct in a direction substantially perpendicular to the exhaust gas passage. It is a form.

According to this structure, the exhaust gas on the upstream side of the ammonia injection mother pipe and the injection nozzle is rectified by the rectifying member so as to flow uniformly over the entire cross section of the flow passage, and is guided to the mother pipe and the nozzle. As a result, in addition to the above, the exhaust gas and the ammonia are mixed more uniformly.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. 1 and 2 are configuration diagrams of an ammonia injection device of a denitration device installed in a boiler exhaust gas passage according to a first embodiment of the present invention.

FIGS. 1 and 2 show a denitration device in which a reactor 2 is horizontally extended and displaced with respect to a terminal portion of a flue 1 through which exhaust gas from a boiler (not shown) flows, In the figure, 3 is an inlet duct connecting between the flue 1 and a denitration catalytic reactor (hereinafter abbreviated as a reactor) 2, and the inlet duct 3 is the same as the flue 1 and the reactor 2 described above. With this arrangement, one side is expanded toward the reactor 2 in the horizontal direction.

Reference numeral 5 denotes an ammonia injection mother pipe, which has an axial line 5a arranged vertically in the expanded portion at the downstream portion of the inlet duct 3 and is arranged in a large number in a row in the exhaust gas flow passage cross section.

As shown in FIG. 2, two ammonia injection nozzles 6 are attached to each of the ammonia injection mother pipes 5 toward the downstream side of the exhaust gas flow. The ammonia injection mother pipes 5 are arranged so that the ammonia injected from the ammonia injection nozzles 6 and 6 can be uniformly distributed in the mixing portion 9 at the inlet of the reactor 2 so that the ammonia injected therefrom can be uniformly distributed. 6. The angle θ formed by the mounting center line Y and the axis Z ₁ parallel to the boiler center line Z is changed according to the degree of expansion of the inlet duct 3 in the horizontal direction.

The two ammonia injection nozzles 6 and 6 attached to each ammonia injection mother pipe 5 are attached with a constant attachment angle β.

An example of the arrangement of the ammonia injection mother pipe 5 and the ammonia injection nozzles 6 and 6 in the ammonia injection device of the denitration apparatus shown in FIGS. = 30 °, and θ = 10 at a portion where the exhaust gas flow passage in the inlet duct 3 is substantially parallel to the boiler center Z (a portion near the boiler center Z in FIG. 1).
, Θ = 45 ° in the most widened part (near the N part in FIG. 1), and the middle part is changed in the range of θ = 10 ° to 45 ° (center is about θ = 30 °). .

Reference numeral 4 denotes a straightening plate provided in the inlet duct 3 along the cross section of the flow path of the exhaust gas flow. The straightening plate 4 is appropriately bent according to the shape of the flow path of the inlet duct 3 to produce smoke. The exhaust gas flow passage between the end of the passage 1 and the ammonia injection mother pipe 5 is smoothly expanded.

In FIG. 2, reference numeral 51 is a bracket for supporting the ammonia injection mother pipe 5, and 52 is a protector plate for preventing ash erosion.

During the operation of the denitration apparatus equipped with the ammonia injecting device constructed as described above, the exhaust gas from the boiler is introduced from the flue 1 into the inlet duct 3, where it is guided by the straightening vanes 4 and horizontally. Uniformly spreads and flows toward the ammonia injection mother pipe 5 side.

Then, in the exhaust gas, ammonia is injected from the ammonia injection nozzles 6 and 6 attached to each of the ammonia injection mother pipes 5 which are arranged in multiple rows at different angles and directions as described above along the exhaust gas passage section. Squirt out.

At this time, the directions and angles of the ammonia injection mother pipe 5 and the ammonia injection nozzles 6 and 6 are changed according to the extent of expansion of the exhaust gas flow passage in the inlet duct 3, so that each injection nozzle 6 , 6 are evenly distributed at the inlet (mixing part 9) of the reactor 2, mixed with the exhaust gas, and uniformly introduced into the reactor 2.

A second embodiment of the present invention is shown in FIGS. In this embodiment, the reactor 2 is arranged to extend vertically with respect to the end of the flue 1 and is displaced upward, and the inlet duct 3 is substantially horizontal from the end of the flue 1 to the bottom. In addition, the shape is such that it expands toward the reactor 2 side toward the upper side.

The ammonia injection mother pipes 5 are arranged with their axis 5a in the horizontal direction and are arranged in a large number at even intervals in the cross section of the flow path of the exhaust gas. In each mother pipe 5, as shown in FIG. In addition, the two ammonia injection nozzles 6 and 6 are attached at a fixed attachment angle α with their ejection ports facing the downstream reactor 2 side.

In the case of this embodiment, the above-mentioned ammonia injection mother pipe 5 does not cause non-uniform distribution of the ammonia ejected from the ammonia injection nozzle 6, especially in the vertical direction, so that the injection nozzle 6 with respect to the horizontal line W will not be generated. ，
The angle θ formed by the mounting center line Y of 6 is changed according to the degree of expansion of the inlet duct 3 in the vertical direction.

That is, θ is set small in the lower portion where the exhaust gas flow in the inlet duct 3 is substantially horizontal and set large in the upper portion expanded toward the reactor 2 side. As a preferable example of the form, θ = 5 ° in the lower part where the exhaust gas flow is substantially horizontal, θ = 20 ° in the most expanded upper part, and θ = 5 ° to 20 ° in the middle part. Is changing.

The mother pipe 5 of the ammonia injection nozzles 6 and 6
The attachment angle α to the exhaust gas flow is set to be large in the lower part and the middle part where the exhaust gas flow is substantially horizontal (for example, α = 45 °) and small in the upper part where the exhaust gas flow is expanded (for example, α = 30 °). The vertical inclination angle θ of the mother tube 5 is harmonized to prevent the formation of a non-uniform distribution of the ammonia ejected from the injection nozzles 6 and 6, particularly in the vertical direction, thereby forming a uniform distribution as a whole.

5 and 6 show a third embodiment of the present invention. In this embodiment, a mixer 9 for mixing ammonia and exhaust gas is installed on the downstream side of the ammonia injection mother pipe 5 and the ammonia injection nozzle 6, that is, at the inlet of the reactor 2. , 2 of the embodiment.

That is, in this embodiment, FIGS.
In the same manner as the embodiment shown in FIG. 2, the reactor 2 is arranged so as not to spread in the waterside direction and displaced from the terminal end of the flue 1,
A large number of the ammonia injection mother tubes 5 are arranged in the vertical direction along the exhaust gas passage section at a uniform interval in the vertical direction.

In this embodiment, the inclination angle θ of the ammonia injection mother pipe 5 and the mounting angle β of the two ammonia injection nozzles 6 and 6 are also changed according to the shape of the flow path of the inlet duct 3. At a portion where the inclination angle θ of the injection mother pipe 5 is parallel to the boiler center line Z of the exhaust gas flow, θ =
It is preferable that 0 °, θ = 30 ° in the expanded portion of the inlet duct, and θ = 20 ° in the intermediate portion.

Further, the mounting angle β of the ammonia injection nozzles 6, 6 is β = at the portion near the center line of the boiler and the intermediate portion of the flow path.
30 °, β = 45 ° at the site where the inlet duct 3 is expanded
It is preferable to smoothly change the degree and the middle thereof in the range of β = 30 ° to 45 °.

[0036]

The present invention is configured as described above.
According to the invention of claims 1 and 2, since the direction and the angle of the ammonia injection mother pipe and the ammonia injection nozzle are changed along the flow path shape of the exhaust gas duct on the upstream side of the reactor, the ammonia injection device is provided. Even if the shape of the equipped exhaust gas duct expands or contracts, ammonia will be ejected according to this flow path change, and ammonia will be supplied to the reactor in a state where it is evenly distributed in the exhaust gas, and the denitration of the reaction will occur. Efficiency is improved.

Further, since the ammonia is uniformly distributed, no special flow path length is required, so that the total length of the denitration system is shortened.

According to the third aspect of the invention, the distribution of the exhaust gas flow flowing into the ammonia injection mother pipe 5 and the nozzle 6 is made uniform by the rectifying member, so that the ammonia and the exhaust gas are evenly mixed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an ammonia injection device of a boiler exhaust gas denitration device according to a first embodiment of the present invention.

FIG. 2 is an enlarged structural diagram of an ammonia injection mother tube and an injection nozzle in FIG.

FIG. 3 is an illustration corresponding to FIG. 1 according to a second embodiment of the present invention.

FIG. 4 is an illustration corresponding to FIG. 2 according to a second embodiment of the present invention.

FIG. 5 is a view corresponding to FIG. 1 according to a third embodiment of the present invention.

FIG. 6 is an illustration corresponding to FIG. 2 according to the third embodiment of the present invention.

FIG. 7 is a corresponding view of FIG. 1 showing a conventional denitration device.

[Explanation of symbols]

 1 Flue 2 DeNOx catalyst reactor 3 Inlet duct 4 Rectifier plate 5 Ammonia injection mother tube 6 Ammonia injection nozzle 9 Mixer

Claims (3)

[Claims] 1. A large number of ammonia injection mother tubes are installed in the exhaust gas flow upstream of the denitration catalytic reactor through which the exhaust gas containing nitrogen oxides flows, and are attached to the same. In an exhaust gas denitration apparatus that injects ammonia from an ammonia injection nozzle to perform catalytic reduction with a denitration catalyst, the ammonia injection mother pipe and the ammonia injection nozzle are duct flow paths between the injection nozzle and the denitration catalyst reactor. An ammonia injection device for a denitration device, characterized in that the direction and the angle of the ejection port of each nozzle are changed according to the shape. 2. The two ammonia injection nozzles are attached to one ammonia injection mother pipe, and the attachment angle at the center of the ejection port is changed according to the flow path shape of the duct. Ammonia injection device of the denitration device described. 3. The denitration device according to claim 1, wherein a plurality of rectifying members for guiding the exhaust gas flow are arranged in parallel in a direction substantially perpendicular to the exhaust gas flow path on the upstream side of the ammonia injection mother pipe in the duct. Ammonia injector.