JP5835962B2 - Exhaust gas duct and denitration apparatus provided with the same - Google Patents

Description

  The present invention relates to an exhaust gas duct suitable for use in a denitration apparatus that decomposes and removes nitrogen oxides contained in exhaust gas by mixing ammonia, and a denitration apparatus including the exhaust gas duct.

The exhaust gas discharged from automobiles, boilers, and the like contains nitrogen oxides that cause environmental loads such as photochemical smog and acid rain. Therefore, a denitration device is used as means for removing nitrogen oxides in order to prevent nitrogen oxides from being released into the atmosphere.
As a denitration method used in a denitration apparatus, there is an SCR method (dry ammonia selective catalytic reduction method) in which nitrogen oxides in exhaust gas are reacted with ammonia and decomposed into water and nitrogen by a catalyst. Specifically, ammonia water is vaporized by a vaporizer in a duct through which exhaust gas passes, and is injected into the duct, and nitrogen oxide and ammonia in the exhaust gas are mixed by the mixer.

  However, since the cost increases by using a vaporizer or a mixer, a method of mixing ammonia and nitrogen oxide without using a vaporizer or a mixer is used. For example, as a method that does not use a mixer, the ammonia vaporized by the vaporizer is injected into the duct two-dimensionally within the duct cross section so that the injection position is in a grid shape, so that ammonia is uniformly distributed in the exhaust gas. There is a way to diffuse. Further, as a method that does not use a vaporizer, there is a means in which ammonia water is sprayed into exhaust gas, evaporated at the temperature of the exhaust gas, and nitrogen oxide and ammonia in the exhaust gas are mixed by a mixer. However, the duct must be longer than the diffusion distance of ammonia and long enough to secure a distance for evaporation.

  As an example of the mixer, the mixer shown in Patent Document 1 is shown in FIG. In this mixer, a plurality of plates 101 are arranged so as to be adjacent to openings having the same shape as the plate 101, and a layer 103 in which pyramids formed by two plates 101 and two openings having the same shape are arranged side by side. To form. The plurality of layers 103 are arranged side by side at intervals so that the cross-sectional direction of the duct coincides with the surface direction of the layer 103 and the plates 101 of the other layers 103 overlap the openings between the adjacent plates 101. The flow of the exhaust gas sprayed with ammonia and passing through the duct flows along the plate 101 while colliding with the plate 101 and disturbing the flow, and passes through the duct. When the flow is disturbed, nitrogen oxides and ammonia contained in the exhaust gas are mixed.

U.S. Pat. No. 4,830,792

  However, since the mixer shown in Patent Document 1 has a complicated shape, the manufacturing cost is high. Further, a space for arranging a plurality of layers side by side with an interval is required, and the installation place is limited.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the exhaust gas duct which can mix ammonia in waste gas with simple structure, and the denitration apparatus provided with the same. .

In order to solve the above problems, the exhaust gas duct of the present invention and the denitration apparatus equipped with the same employ the following means.
That is, the exhaust gas duct according to the first aspect of the present invention is an exhaust gas duct that distributes exhaust gas and mixes a reducing agent with the exhaust gas, the first passage extending along the first central axis, and the second central axis. A second passage extending along the first passage, and a turning portion for turning the flow direction of the exhaust gas flowing in from the first passage toward the second passage, wherein the first passage and the second passage are When the exhaust duct is viewed in plan, the first central axis and the second central axis do not intersect, and when the exhaust duct is viewed from the side, the first central axis and the second central axis intersect. and has the turning portion is configured to connect to a passage of the L-shape when the said second passage and said first passage and a side view of the said exhaust gas duct, flows into the inlet of the second passage The exhaust gas flowing from the outlet of the first passage along the first central axis is turned toward the inlet of the second passage so that the exhaust gas has a swirling component around the second central axis. The crossing surface is located downstream of the reducing agent charging position.

The exhaust gas into which the reducing agent is introduced from the reducing agent inlet in the first passage proceeds in the first passage in the axial direction of the first passage. Since the second passage is connected downstream of the first passage, the exhaust gas enters the second passage from the first passage. The flow that has traveled in the second passage in the axial direction of the first passage is in contact with the intersecting surface that forms a side wall surface that intersects at an angle with respect to the axial direction of the first passage. Is turned along the direction of the crossing plane. Furthermore, the flow whose direction has been diverted further diverts the flow along the wall surface forming the passage. In this way, the flow direction gradually turns along the wall surface of the second passage, whereby a vortex is generated in the flow. The swirled flow in the second passage is pushed by the exhaust gas flowing into the second passage from the first passage and advances in the second passage in the axial direction while turning.
Thereby, ammonia is effectively mixed with the exhaust gas that has turned into a swirling flow.

The turning section connects the first passage and the second passage so as to form an L -shaped passage when the exhaust duct is viewed from the side, and the exhaust gas flowing into the inlet of the second passage Crossing the surface to turn the flow direction of the exhaust gas flowing out from the outlet of the first passage along the first central axis toward the inlet of the second passage so that the gas has a swirling component around the second central axis The crossing surface is located downstream of the reducing agent charging position.

  Thereby, a swirl | vortex flow can be generated in the flow in a 2nd channel | path via the turning part which is a cylindrical simple structure between a 1st channel | path and a 2nd channel | path. Therefore, ammonia can be mixed with the exhaust gas with a simple configuration and easy installation work.

It is preferable shape of the cross section perpendicular to the front Symbol the second central axis of the second passage is a parallelogram.

The second passage is formed such that a cross section perpendicular to the axial direction thereof is a parallelogram. That is, since the surface direction of the surface forming the second passage is orthogonal to the axial direction of the first passage, the surface forming the second passage is an intersecting surface.
Thereby, a swirl | vortex flow can be generated in a 2nd channel | path, without providing separate members other than a 1st channel | path and a 2nd channel | path. Therefore, ammonia can be mixed with the exhaust gas at a low cost.

It is preferable shape of the cross section of Cartesian before Symbol the second central axis of the second passage is square.

When the flow direction is turned in the second passage, the flow is continuously turned at the same angle because the second passage has a square cross section. Therefore, since the flow is not attenuated, the vortex is easily swirled.
Thereby, ammonia can be mixed with exhaust gas more efficiently.

The exhaust gas duct according to the second aspect of the present invention is an exhaust gas duct for circulating exhaust gas and mixing the exhaust gas with a reducing agent, the first passage extending along the first central axis, and the second central axis. And the first passage and the second passage are arranged so that the first central axis and the second central axis intersect when the exhaust gas duct is viewed from the side. The first passage and the second passage are connected to form an L -shaped passage when the exhaust gas duct is viewed from the side, and the inlet of the second passage is connected to the second passage. A partition plate is provided for turning the flow direction of the exhaust gas flowing out from the outlet of the first passage along the first central axis so that the exhaust gas flowing in has a swirling component around the second central axis. , The partition plate , And which it is located downstream of the reducing agent loading position.

When the first passage is connected downstream of the passage having a rectangular cross-sectional shape perpendicular to the axial direction of the second passage, a partition plate is provided in the connected passage. A partition plate makes a surface direction parallel to the axial direction of the channel | path connected, and makes a cross section oppose the direction into which a flow flows. Since the shape of the cross section perpendicular to the axial direction of the second passage can be formed into any shape by providing the partition plate at any position, the second passage having a square cross section and a square cross section. Can be formed. Thereby, it is possible to efficiently generate a swirl flow in various shapes of passages, and to mix ammonia with exhaust gas efficiently.
Further, even when the first passage is connected to the downstream thereof with a pipe having an axial direction intersecting the axial direction of the first passage, the partition plate is disposed on the surface thereof in the axial direction of the first passage. By being provided so as to intersect with each other, the partition plate becomes an intersecting surface, and a swirling flow can be generated in the pipe connected to the first passage.
Therefore, even if a pipe having a central axis that intersects the central axis direction of the first passage is already provided downstream of the first passage, ammonia can be mixed into the exhaust gas with a simple configuration.

It is preferable that the partition plate intersects with the first central axis of the first passage with an angle between 30 degrees and 45 degrees.

By providing the partition plate so as to intersect with the axis of the first passage at an angle of 30 to 45 degrees, the flow flowing from the first passage to the second passage is 30 to 45 degrees. The angle of flow is diverted by an angle between.
Thereby, since a swirl flow is not distorted by pressure loss, ammonia can be further mixed with exhaust gas.

  It is preferable that both sides of the partition plate perpendicular to the axial direction of the second passage are located in an in-plane direction of the surface of the first passage perpendicular to the axial direction of the second passage.

The partition plate is located only in the second passage communicating with the first passage in the axial direction of the first passage. That is, the flow that has passed through the first passage and turned into a swirl flow in the second passage becomes wider when it passes through the partition plate. Since a swirl flow having the flow direction as a swirl surface is generated in the enlarged portion of the flow path, swirl in the flow direction is added to the swirl flow generated by the intersecting surface.
Thereby, ammonia can be mixed with exhaust gas more efficiently.

  It is preferable that a denitration apparatus has the exhaust gas duct.

  A swirling flow is generated at the intersecting surface in the exhaust gas duct, and ammonia is mixed with the exhaust gas to contact the catalyst. Thereby, ammonia can be mixed with the exhaust gas for denitration with a simple configuration, so that the cost for denitration can be reduced.

  Thereby, ammonia can be mixed in the exhaust gas with a simple configuration.

It is a perspective view of the exhaust gas duct shown in a 1st embodiment of the present invention, and a denitration device provided with the same. It is a top view of the exhaust gas duct provided in the denitration apparatus shown in FIG. It is a sectional side view of the exhaust gas duct shown in FIG. It is a top view of the exhaust gas duct of the denitration apparatus shown in 2nd Embodiment of this invention. It is a sectional side view of the exhaust gas duct shown in FIG. It is a top view of the exhaust gas duct of the denitration apparatus shown in 3rd Embodiment of this invention. It is a sectional side view of the exhaust gas duct shown in FIG. It is a perspective view of the mixer provided in the conventional denitration apparatus.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
FIG. 1 is a perspective view showing a first passage 3 and a second passage 5 constituting an exhaust gas duct 13 provided in the denitration apparatus 1.
FIG. 2 is a plan view showing the first passage 3 and the second passage 5 in FIG. 1 and the flow X of the exhaust gas flowing therethrough.
FIG. 3 is a side cross-sectional view showing the first passage 3 and the second passage 5 in FIG. 2 and the flow X of the exhaust gas flowing therethrough.

  The exhaust gas duct 13 includes a first passage 3 and a second passage 5. The second passage 5 includes a turning portion 9 on the upstream side, and the first passage 3 and the main body of the second passage 5 are connected via the turning portion 9.

  The first passage 3 is a cylindrical passage through which the exhaust gas flow X passes. The first passage 3 may have a cross-sectional shape that is perpendicular to the axial direction of the first passage 3 and may be a circle, a rectangle, or a polygon. The first passage 3 has a turning portion 9 connected downstream thereof.

  The turning portion 9 is a cylindrical body having a passage inside, and the passage communicates with the first passage 3. The turning portion 9 is connected to the main body of the second passage 5 at the end opposite to the end to which the first passage 3 is connected.

  The axial direction of the second passage 5 body intersects the axial direction of the first passage 3. The angle at which the axial direction of the first passage 3 and the axial direction of the second passage 5 body intersect is arbitrary as long as the axial direction of the first passage 3 and the axial direction of the second passage 5 are not parallel. Further, the second passage 5 is provided to extend only in one direction from a region where the first passage 3 and the second passage 5 intersect so as to form a substantially L-shaped passage as in the present embodiment. Alternatively, the first passage 3 and the second passage 5 may extend in both directions so as to form a substantially T-shaped passage.

  The turning portion 9 has a connecting portion 9 a that connects the intersecting surface 11 and the first passage 3. The turning portion 9 has an intersecting surface 11 that is one side wall surface and an opposing surface 9b that is opposite to the intersecting surface 11 and that is the other side wall surface. In the axial direction of the first passage 3, the length of the intersecting surface 11 is longer than the length of the facing surface 9b. Each of the intersecting surface 11 and the opposing surface 9b may be formed by a plurality of planes having different surface directions, or may be a continuously curved surface. The cross-sectional shape of the turning portion 9 may be a quadrangle, a polygon, or a circle. In the turning portion 9, the side wall surface including the intersecting surface 11 is bent toward the opposite surface 9 b upstream from the intersecting surface 11, and the angle of the center of bending is preferably 30 degrees or more and less than 45 degrees. Since the first passage 3 and the second passage 5 main body are connected via the turning portion 9 in which the lengths of the intersecting surface 11 and the facing surface 9b are different, the second passage is on the extension of the central axis of the first passage 3. The central axes of 5 do not intersect.

  A reducing agent charging position (not shown) is provided on the upstream side of the intersecting surface 11, that is, on the first passage 3 side. An economizer 17 for heating the boiler feed water is generally provided upstream of the first passage 3 by utilizing the residual heat of the flue gas from the boiler. A catalyst 19 that reacts nitrogen oxides in the exhaust gas with ammonia is provided downstream of the second passage 5.

Next, the flow X passing through the first passage 3 and the second passage 5 will be described.
The exhaust gas flow X flowing into the denitration apparatus 1 passes through the economizer 17 and flows into the first passage 3. The flow X is supplied with a reducing agent, that is, ammonia, into the flow path at the reducing agent charging position, and passes through the first passage 3 and the turning section 9 together with the ammonia. At this time, ammonia may be a liquid or a gas.
In the turning portion 9, an intersecting surface 11 that intersects with a predetermined angle with respect to the axial direction of the first passage 3 is located. Therefore, the flow X that has flowed along the axial direction of the first passage 3 is in contact with the intersecting surface 11 in the turning portion 9, and the direction of the flow is turned in the surface direction of the intersecting surface 11. At this time, the flow direction of the flow X is disturbed, and a swirling flow is generated. Every time the flow X comes into contact with a corner in the second passage 5, the direction of the flow X is turned. It flows in the axial direction of the two passages 5.
Thereby, ammonia flows into the exhaust gas by swirling the flow, so that when the flow comes into contact with the catalyst 19 through the second passage 5, the reaction can be reliably caused in the mixed state.

  Further, by making the cross-sectional shape orthogonal to the axial direction of the second passage 5 a square, the flow redirected in the direction of the flow X by the intersecting surface 11 is always redirected at the same angle. Further, the distance from the turning of the direction of the flow X to the next turning is also equal. Accordingly, since the flow X swirls in a circular shape, the flow X is hardly attenuated, and ammonia can be mixed into the exhaust gas more efficiently. In addition, the shape of the cross section of the 2nd channel | path 5 may be a regular polygon other than a square, and a perfect circle.

The intersecting surface 11 may intersect with the axis of the first passage 3 at an angle between 30 degrees and 45 degrees.
The larger the angle at which the intersecting surface 11 and the axis of the first passage 3 intersect, the stronger the swirl of the swirling flow and the higher the mixing efficiency. By turning the direction of the flow X at an angle between 30 degrees and 45 degrees, the swirling flow is not distorted due to the pressure loss, and ammonia can be efficiently mixed with the exhaust gas. In particular, when the denitration apparatus is small, the cross section of the second passage 5 is often square, which is suitable for implementing the invention described in this embodiment. However, it is of course possible to apply this embodiment even when the denitration apparatus is large.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 4 is a plan view showing the first passage 3 and the second passage 5 constituting the exhaust gas duct 13 provided in the denitration apparatus 1 shown in the present embodiment, and the flow X flowing therethrough.
FIG. 5 is a side sectional view showing the first passage 3 and the second passage 5 in FIG. 4 and the flow X flowing therethrough.

The first passage 3 and the second passage 5 constituting the exhaust gas duct 13 provided in the denitration apparatus 1 shown in FIGS. 4 and 5 are connected to the first passage 3 and the second passage 5, and the axis of the first passage 3. This is common to the first embodiment in that the intersecting surface 11 having a surface direction intersecting the direction is located. Accordingly, the same reference numerals are assigned to these configurations, and the description thereof is omitted.
Compared with the first embodiment, this embodiment has a parallelogram-shaped cross section perpendicular to the axial direction of the second passage 5, and the second passage 5 is formed in a passage divided by the partition plate 7. The partition plate 7 is different in that the side perpendicular to the axial direction of the second passage 5 is located in the in-plane direction of the side wall surface of the first passage 3 perpendicular to the axial direction of the second passage 5.
The first passage 3 is connected to the second passage 5 having a parallelogram in cross section so that one of the side wall surfaces forming the second passage 5 has a predetermined angle with respect to the axial direction of the first passage 3. The crossing surface 11 is located with the surface direction crossing at.
Thereby, the intersecting surface 11 can be provided in the second passage 5 by only the first passage 3 and the second passage 5, and a swirling flow can be generated in the flow passing through the second passage 5. Therefore, ammonia can be mixed with the exhaust gas with a simple configuration.

  Further, the second passage 5 is formed by the partition plate 7 so that the length of each side in the cross section of the second passage 5 is equal. In particular, when the denitration device 1 is large in size, the length of each side in the cross section of the second passage 5 is different, for example, a rectangle or the like, so that the second passage 5 has a shape close to a perfect circle. Since the flow X can swirl, even when the first passage 3 is connected to passages having different side lengths forming a cross section, ammonia can be efficiently mixed with the exhaust gas.

  The partition plate 7 is provided in a region where the first passage 3 and the second passage 5 intersect. That is, in the axial direction in the 2nd channel | path 5, the partition plate 7 exists over the range of the height h shown in FIG.

A swirl flow is generated in the second passage 5, and the flow X traveling in the second passage 5 while swirling is along the partition plate 7 in a portion communicating with the first passage 3 in the axial direction of the first passage 3. Go ahead. When the downstream end of the partition plate 7 is passed, the partition plate 7 disappears on the side surface of the channel, and the channel is expanded. At that time, the flow path suddenly widens, and a swirl flow that swirls horizontally in the direction of the flow X, that is, the axial direction of the second passage 5 is generated at the end of the flow path. By this swirl flow, a swirl component in the axial direction of the second passage 5 is added to the swirl flow generated by the intersecting surface 11.
Therefore, ammonia can be mixed with exhaust gas more efficiently.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS.
FIG. 6 is a plan view showing the first passage 3 and the second passage 5 constituting the exhaust gas duct 13 provided in the denitration apparatus shown in the present embodiment, and the flow X flowing therethrough.
FIG. 7 is a side sectional view showing the first passage 3 and the second passage 5 in FIG. 6 and the flow X flowing therethrough.

The first passage 3 and the second passage 5 constituting the exhaust gas duct 13 provided in the denitration apparatus 1 shown in FIGS. 6 and 7 are connected to the first passage 3 and the second passage 5, and the axial direction of the first passage Is formed in a passage divided by the partition plate 7, and the partition plate 7 has a side perpendicular to the axial direction of the second passage 5, The second embodiment is common to the second embodiment in that it is located in the in-plane direction of the surface of the first passage 3 orthogonal to the axial direction of the second passage 5. Accordingly, the same reference numerals are assigned to these configurations, and the description thereof is omitted.
This embodiment is different from the second embodiment in that the second passage 5 has a rectangular cross section, and the passage cross-sectional shape is formed by partition plates located on both sides.
Both the first passage 3 and the second passage 5 have a rectangular passage cross section. And the partition plate 7 is provided in the area | region where the 1st channel | path 3 and the 2nd channel | path 5 cross | intersect. The partition plates 7 are provided on both sides in the passage, and one surface direction thereof is an intersecting surface 11 that intersects the axial direction of the first passage 3.
As a result, the flow X flowing into the second passage 5 through the first passage 3 comes into contact with the partition plate 7, that is, the intersecting surface 11, and the flow direction is changed to the direction of the intersecting surface 11. It becomes a swirl flow by being disturbed.
Therefore, ammonia can be efficiently mixed with the exhaust gas by providing the partition plate 7 in a general duct having a rectangular cross section.

  In each of the above embodiments, the reducing agent is ammonia, and the fluid flowing through the first passage and the second passage is exhaust gas. However, if there are two types of fluids that need to be mixed, a fluid other than exhaust gas and ammonia may be used. There may be.

  By providing the exhaust gas duct 13 shown in each of the above embodiments in the denitration apparatus 1, denitration can be performed with a simple configuration, so that the equipment cost and operation cost of the denitration apparatus 1 can be reduced.

DESCRIPTION OF SYMBOLS 1 Denitration apparatus 3 1st channel | path 5 2nd channel | path 7 Partition plate 9 Turning part 9a Connection part 9b Opposing part 11 Crossing surface 13 Exhaust gas duct 101 Plate 103 Mixer

Claims (6)

An exhaust gas duct for circulating exhaust gas and mixing a reducing agent with the exhaust gas,
A first passage extending along a first central axis;
A second passage extending along a second central axis;
A turning portion for turning the flow direction of the exhaust gas flowing in from the first passage toward the second passage;
The first passage and the second passage include the first central axis when the exhaust gas duct is viewed in plan and the first central axis does not intersect the second central axis and when the exhaust gas duct is viewed from the side. Arranged so that the second central axis intersects,
The turning section connects the first passage and the second passage so as to form an L -shaped passage when the exhaust duct is viewed from the side, and the exhaust gas flowing into the inlet of the second passage Crossing the surface to turn the flow direction of the exhaust gas flowing out from the outlet of the first passage along the first central axis toward the inlet of the second passage so that the gas has a swirling component around the second central axis Have
The exhaust gas duct is characterized in that the intersecting surface is located downstream of the reducing agent charging position. An exhaust gas duct for circulating exhaust gas and mixing a reducing agent with the exhaust gas,
A first passage extending along a first central axis;
A second passage extending along the second central axis,
The first passage and the second passage are arranged so that the first central axis and the second central axis intersect when the exhaust gas duct is viewed from the side.
The first passage and the second passage are connected to form an L -shaped passage when the exhaust gas duct is viewed from the side,
At the inlet of the second passage, the exhaust gas flowing into the second passage flows out from the outlet of the first passage along the first central axis so as to have a swirling component around the second central axis. A partition plate that turns the flow direction of the exhaust gas is provided,
The exhaust gas duct, wherein the partition plate is provided downstream of the reducing agent charging position.   The exhaust gas duct according to claim 1 or 2, wherein a shape of a cross section perpendicular to the second central axis of the second passage is a parallelogram.   The exhaust gas duct according to claim 1 or 2, wherein a shape of a cross section perpendicular to the second central axis of the second passage is a square.   The exhaust gas duct according to claim 2, wherein the partition plate intersects with the first central axis of the first passage at an angle of 30 to 45 degrees.   A denitration apparatus having the exhaust gas duct according to any one of claims 1 to 5.

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