TWI820288B - Nox removal equipment - Google Patents

Abstract

A NOx removal equipment comprising an inlet duct having a flow channel for flowing an exhaust gas from a boiler in a horizontaldirection, a joint duct having a flow channel for changing a flow of the exhaust gas from the horizontal direction to a vertical direction, and a reactor duct having a flow channel for flowing the exhaust gas in the vertical direction, wherein a screen plat, a NOx reductant supply line structure, and a fixed bed comprising a denitration catalyst are inside of the reactor duct in this order along the course of the exhaust gas, and the NOx reductant supply line structure comprises a heat exchange line, a transportation line and a nozzle, wherein the heat exchange line is for warming a NOx reductant with heat held by the exhaust gas, the transportation line is for delivering the warmed NOx reductant in the heat exchange line to the nozzle, and the nozzle is for injecting the NOx reductant delivered through the transportation line into the reactor duct.

Description

Denitrification device

The present invention relates to a denitration device.

Various devices for removing nitrogen oxides contained in combustion exhaust gases have been proposed.

For example, Patent Document 1 discloses a denitration device in which a reducing agent injection device is disposed upstream of a denitration reactor having a built-in catalytic layer, so that the reducing agent injected by the reducing agent injection device is mixed with the exhaust gas. The nitrogen oxide reaction is characterized by: a rectifying grid that separates the gas flow direction is arranged between the reducing agent injection device and the catalyst layer, and the exhaust gas and the reducing agent are arranged in at least one area of the rectifying grid. Agent gas mixing promoter.

Patent Document 2 discloses a smoke exhaust denitration device, which uses a heat exchanger to heat up the exhaust gas and reduces it with a reducing agent, and removes nitrogen oxides in the exhaust gas through a denitration catalyst; it is characterized by: A rectifying plate is arranged upstream of the heat exchanger, and the heat exchanger is connected with the aforementioned denitration catalyst. Arranged in an opposite manner, the reducing agent is injected through the reducing agent injection pipe inserted between the heat exchanger and the denitration catalyst.

Patent Document 3 discloses an ammonia gas injection device, which is located in an exhaust flow path and includes a plurality of main pipes arranged perpendicularly to the exhaust flow, a plurality of protruding pipes protruding from the sides of the main pipes, and a plurality of protruding pipes protruding from the sides of the main pipes. The end of the protruding pipe is provided to open in the downstream direction of the exhaust flow. The distance between the center line of each nozzle and the side of the main pipe is larger than the outer diameter of the main pipe. Projected on a cross section orthogonal to the exhaust flow The position of each nozzle is arranged so as to be located at each vertex of a plurality of adjacent equilateral triangles, and an exhaust rectifying device is provided on the upstream side of the exhaust flow than the nozzle.

Patent Document 4 discloses a denitrification agent injection device that injects a denitrification agent into the exhaust gas flow to remove nitrogen oxides; it is characterized by disposing the denitrification agent in the exhaust gas flow on the downstream side of the denitrification agent injection pipe. supply pipe, and connect the denitrification agent injection pipe and the denitrification agent supply pipe, thereby utilizing the denitrification agent supply pipe and the member for heating the denitrification agent and for promoting the injection and denitration mixing.

Patent Document 5 discloses an ammonia injection piping in which an ammonia injection nozzle is arranged in the exhaust gas and ammonia is sprayed, thereby reducing nitrogen oxides in the exhaust gas. The characteristic is that the piping on the upstream side of the ammonia injection nozzle is used as a borrowing pipe. The ammonia heating unit heats ammonia with the heat retained in the exhaust gas.

[Prior technical literature]

[Patent Document 1] Japanese Patent Application Publication No. 10-165769

[Patent Document 2] Japanese Patent Application Publication No. 10-57770

[Patent Document 3] Japanese Patent Application Laid-Open No. 8-89754

[Patent Document 4] Japanese Patent Application Publication No. Sho 60-12120

[Patent Document 5] Japanese Patent Application Publication No. Sho 56-10322

The subject of the present invention is to provide a novel denitration device.

The present invention includes the following aspects.

[1] A denitrification device having: a reactor duct having a flow path for flowing exhaust gas from a boiler; and in the reactor duct, along the flow of the exhaust gas, a sieve plate and a denitrification agent are sequentially provided The supply line system includes a fixed bed of denitrification catalyst, and the denitrification agent supply line system has: a heat exchange line for heating the denitrification agent with the heat retained in the exhaust gas; and a conveyor line for The denitrification agent heated by the heat exchange line is supplied to the nozzle; and the nozzle is used to inject the denitrification agent supplied through the transfer line into the reactor conduit.

[2] A denitration device having: an inlet duct having a flow path for flowing exhaust gas from a boiler in a lateral direction; and a joint duct having a flow path for changing the flow of exhaust gas from a lateral direction to a longitudinal direction. ; and the reactor duct has a flow path for the exhaust gas to flow in the longitudinal direction; in the reactor duct, along the flow of the exhaust gas, there are sieve plates, The denitrification agent supply line system includes a fixed bed of denitrification catalyst, and the denitrification agent supply line system has: a heat exchange line for heating the denitrification agent with the heat retained in the exhaust gas; and a conveyor line , is used to supply the denitrification agent heated by the heat exchange line to the nozzle; and the nozzle is used to inject the denitrification agent supplied via the transfer line into the reactor conduit.

[3] The denitrification device according to [1] or [2], further comprising a structure that supports the screen plate, and the denitrification agent supply line system is supported by the structure that supports the screen plate.

[4] The denitrification device according to [1] or [2], further comprising a structure that supports the sieve plate and a structure that supports a denitrification agent supply line system, and the denitrification agent supply line system is supported by the denitrification agent. The agent supply line system is supported by the structure.

[5] The denitration device according to any one of [1] to [4], wherein the denitration agent supply line system further has a baffle.

[6] The denitration device according to any one of [1] to [5], wherein at least part of the heat exchange line has a heat sink.

The denitrification device of the present invention can uniformly mix the exhaust gas and the denitrification agent, and the flow of the exhaust gas introduced into the fixed bed is less likely to be uneven, so the denitrification efficiency is extremely high. The denitrification device of the present invention is not prone to clogging of the fixed bed and uneven wear of the fixed bed, can also suppress machine failure caused by the generation of ammonium sulfate, and can be used stably for a long time.

The denitrification device of the present invention is located between the sieve plate and the fixed catalyst bed and preferably injects the denitrification agent into a position where the gas flow is not uneven. Therefore, the denitrification agent is uniformly supplied to the fixed catalyst bed and is not uneven. The amount of denitrification agent that passes through after reacting with the catalyst is small. Therefore, there is no need to inject an excess amount of denitrification agent that far exceeds the stoichiometric ratio of the denitrification agent in the denitrification reaction, and operating costs can be reduced.

1:Inlet duct

2: Connector tube

3: Sieve plate

4: Catalyst fixed bed

5:Exit duct

6:Reactor conduit

7: Denitrification agent (NH ₃ ) supply line system

8:Heat exchange line

9:Conveyor line

10:Nozzle

11:Herringbone baffle

12: Wing baffle

13:Heat sink

G: exhaust

[Fig. 1] is a diagram showing the first embodiment of the denitration device of the present invention.

[Fig. 2] is a diagram showing a second embodiment of the denitration device of the present invention.

[Fig. 3] A perspective view showing an example of a denitrification agent supply line system (with heat sink attached).

[Fig. 4] is a cross-sectional view showing an example of a denitrification agent supply line system (with a herringbone baffle).

[Fig. 5] is a cross-sectional view showing an example of a denitrification agent supply line system (with wing-shaped baffle).

[Fig. 6] is a diagram showing a third embodiment of the denitration device of the present invention.

[Fig. 7] A perspective view showing an example of a denitrification agent supply line system (without fins).

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In addition, the scope of the present invention is not limited to the following embodiments.

FIG. 1 is a diagram showing a first embodiment of the denitration device of the present invention. The denitration device of the first embodiment includes a reactor duct 6 and a flow path for flowing exhaust gas from the boiler. In the reactor duct, along the flow of exhaust gas, there are in sequence: a sieve plate 3, which is composed of a plurality of grilles; a denitrification agent supply line system 7; and a fixed bed 4, which is used for denitrification removal. Catalyst for nitrogen oxides contained in exhaust gas. Grilles are generally composed of flat plates. Furthermore, the denitrification agent supply line system 7 has: a heat exchange line 8 for heating the denitrification agent with the heat retained in the exhaust gas; and a conveyor line 9 for denitrification heated by the heat exchange line. The nitrifying agent is supplied to the nozzle; and the nozzle 10 injects the denitrifying agent supplied through the conveying line into the reactor conduit.

FIG. 2 is a diagram showing a second embodiment of the denitration device of the present invention. The denitration device of the second embodiment has an inlet duct 1, a joint duct 2, a reactor duct 6, and an outlet duct 5. The exhaust gas G from the boiler flows through the inlet duct 1, the joint duct 2, the reactor duct 6, and the outlet duct 5 in this order.

In the denitration device of the second embodiment, the inlet duct 1 has a flow path for allowing the exhaust gas from the boiler to flow in the lateral direction. In FIG. 2 , the upper surface and the lower surface of the flow path of the inlet duct 1 are drawn with straight lines. The cross-sectional shape of the flow path of the inlet duct when viewed from the gas flow direction can be rectangular, trapezoidal, circular, elliptical, etc. Among them, the rectangular shape is preferred in terms of ease of processing.

In the denitration device of the second embodiment, the joint duct 2 has a flow path for changing the flow of exhaust gas from the horizontal direction to the vertical direction. Although the joint duct shown in Figure 2 changes the flow downward, it may also change the flow upward as shown in Figure 6 . The direction of the joint duct can be appropriately selected taking into account the installation space and layout of the denitration device. In FIG. 2 , the upper side surface and the lower side surface of the flow path of the joint conduit 2 are drawn with straight lines. The surface that separates the upper side and the surface that separates the lower side of the flow path of the joint duct 2 may be arc-shaped when viewed from the same viewpoint as in FIG. 2 . Furthermore, the lower surface of the flow path that separates the inlet conduit 1 and the surface that separates the flow path of the reaction conduit 6 on the side closer to the inlet conduit 1 are directly joined, and the lower surface of the flow path that separates the joint conduit 2 is omitted. Yes. The cross-sectional shape of the flow path of the joint conduit 2 viewed from the gas flow direction can be rectangular, trapezoidal, circular, elliptical, etc. Among them, the rectangular shape is preferred in terms of ease of processing.

In the denitration device of the second embodiment, the reactor duct 6 has a flow path for flowing the exhaust gas in the longitudinal direction. In FIG. 2 , the separation surface of the flow path of the reactor conduit 6 close to the inlet conduit side and the separation surface away from the inlet conduit side are drawn with straight lines. The cross-sectional shape of the flow path of the reactor conduit when viewed from the gas flow direction can be rectangular, trapezoidal, circular, elliptical, etc. Among them, the rectangular shape is preferred in terms of ease of processing. The size of the flow path cross section of the reactor conduit is preferably almost the same from the inlet of the reactor conduit through the outlet of the fixed catalyst bed to the outlet of the reactor conduit. The outlet of the reactor conduit is generally connected to the inlet of the outlet conduit 5 .

In the reactor conduit, there is a sieve plate 3 and denitrification agent supply. Line system 7 and catalyst fixed bed 4. Sieve plate 3 is located at the inlet side of the reactor conduit. A structure to support the sieve plate is provided on the inlet side of the reactor conduit, such as a beam spanning the inside of the reactor conduit (not shown). The screen plate is supported in the reactor conduit by the screen plate supporting structure. The catalyst fixed bed 4 is located at the outlet side of the reactor conduit. A structure to support the fixed bed of catalyst is provided on the outlet side of the reactor conduit, such as a beam across the inside of the reactor conduit (not shown). The catalyst fixed bed is supported in the reactor conduit by the catalyst fixed bed support structure. The denitrification agent supply line system 7 is located between the sieve plate and the catalyst fixed bed. The denitrification agent supply line system is preferably located closer to the screen plate than the catalyst fixed bed. The denitrification agent supply line system may be supported by the aforementioned sieve plate support structure or catalyst fixed bed support structure. A structure supporting the denitrification agent supply line system may be provided between the sieve plate and the catalyst fixed bed. For example, a beam or the like may be provided across the reactor duct, and the denitrification agent supply line system may be supported in the reactor duct by a denitrification agent supply line system support structure.

The method of supporting is not particularly limited. For example, it may be placed on a support structure provided below, suspended from a support structure provided above, or straddled on a support structure provided on the side.

The sieve plate is preferably composed of a plurality of grilles. Multiple grilles are generally arranged with their main surfaces parallel. In order to fix a plurality of grids in such an arrangement, wires or plates (horizontal members) in a direction orthogonal to the main surface of each grid may be joined to each grid to form a grid. Furthermore, outer frame members (terminal members) may be provided at both ends of a plurality of grilles.

The sieve plate is attached to the inlet side of the flow path of the reactor conduit 6 and covers the entire cross-section of the flow path. The main surface of the grid is substantially orthogonal to the gas flow direction of the inlet conduit 1 and substantially parallel to the reactor conduit 6 It is better to set the screen plate according to the direction of gas flow.

In terms of the arrangement of the sieve plate, it is located at the inlet of the flow path of the reactor conduit 6, and the beams are arranged on the inner walls of the two opposing flow paths in a direction such as parallel, right angles or grid shape to the gas flow direction of the inlet conduit 1. It can also be spanned and a screen plate unit can be installed on the beam or between the beams. The plurality of sieve plate units constitute a sieve plate. The sieve plate unit is one in which the grille and the horizontal members or terminal members are connected in a ladder or lattice shape, and may also be in a grid shape.

The denitrification agent supply line system has: a heat exchange line 8, which is used to heat the denitrification agent with the heat retained in the exhaust gas; a conveying line 9, which is used to supply the denitrification agent heated by the heat exchange line to the nozzle; and the nozzle 10, which injects the denitrification agent supplied via the delivery line into the reactor conduit.

The heat exchange line 8 is a pipeline in which the heat transfer tubes are arranged orthogonally to the gas flow of the reactor duct. The heat exchange line can be a section of heat transfer tubes arranged horizontally in a intestine shape, string shape or comb shape. The heat exchange line 8 may be composed of heat transfer tubes arranged in parallel rows or in a staggered pattern in multiple vertical layers. As the heat transfer tube, a straight or curved tube with high thermal conductivity is used. The cross-sectional shape of the heat transfer tube may be circular, polygonal, etc. The inner wall of the heat transfer tube may be smooth, or may be grooved to improve thermal conductivity. It is better to use heat transfer tubes with spiral grooves on the inner wall. The heat transfer tube may also have heat sinks 13 attached to the outer wall. Examples of the heat sink include flat plate heat sinks, corrugated heat sinks, slit heat sinks, spiral heat sinks, ventilated heat sinks, and the like. heat sink, tied to It is preferred that the main surface be arranged parallel or at right angles to the main surface of the grid and substantially parallel to the gas flow direction of the reactor conduit 6 . The inlet end of the heat exchange line is connected to the pipe from the denitrification tank outside the reactor conduit, and the outlet end of the heat exchange line is connected to the inlet end of the transfer line. As a denitrification agent, it is preferable to use one in which ammonia gas is diluted with air. In the reactor conduit, it is better to heat the ammonia gas in the heat exchange line to a temperature that does not produce ammonium sulfate.

The transfer line 9 is a pipe arranged so that the supply pipe is orthogonal to the gas flow of the reactor duct. As the supply pipe, a straight or curved pipe is used. The cross-sectional shape of the supply pipe may be circular, polygonal, etc. The inner wall of the supply pipe is preferably smooth from the viewpoint of reducing pressure loss. For the conveyor line, it is better to arrange a section of the supply pipe horizontally in the shape of a intestine, a string, or a comb. The transfer line can be installed in the reactor duct at the same height as the heat exchange line, at a lower height than the heat exchange line, or at a higher height than the heat exchange line. However, it can be set at A higher height level than the heat exchange line is preferred. The conveyor line is preferably arranged so that the length direction of the supply pipe is parallel or perpendicular to the main surface of the grid.

The shape of the nozzle 10 is not particularly limited as long as it can supply the denitrification agent into the reactor duct. At least one nozzle can be installed in the middle or at the end of the supply pipe. The nozzle is preferably installed so that the denitrification agent is supplied in the same direction as the gas flow direction of the reactor duct. Furthermore, if the nozzle is installed so that the conveyance line or the heat exchange line is arranged downstream of the nozzle, the flow will be disturbed by the conveyance line or the heat exchange line, causing the It is better to mix the supplied denitrification agent with the exhaust gas evenly. The number of nozzles provided is not particularly limited as long as the denitrification agent can be uniformly supplied into the reactor duct. The nozzle system can be arranged in staggered or side-by-side arrangements. The staggered arrangement, angle, etc. can be set appropriately.

FIG. 3 is a conceptual diagram when the denitrification agent supply line system 7 shown in FIG. 2 is viewed from obliquely below. In the heat exchange line shown in FIG. 3 , the heat sink 13 is provided on a part outside the heat exchange line 8 , and the heat exchange line 8 is piped in a intestine shape. When the heat transfer coefficient of the heat exchange line is sufficiently large, it is not necessary to install the heat sink as shown in Figure 7. The conveyor line shown in FIG. 3 has the conveyor line 9 arranged in a string shape, and a plurality of nozzles 10 are provided in the middle and at the end of the conveyor line 9 .

The denitrification agent supply line system can further have a baffle. The shape of the baffle is not particularly limited. For example, the baffle extends in a herringbone shape along the ridge line of the supply pipe where the nozzle is installed (herringbone baffle 11, see FIG. 4). Wing-shaped expansion on the side (wing-shaped baffle 12, see Figure 5) can also be used.

The denitrification device of the present invention can make nitrogen oxides and denitrification agents evenly contact the catalyst fixed bed, so the reaction rate in the catalyst fixed bed can be improved. In addition, since the dust contained in the combustion exhaust gas will evenly contact the catalyst fixed bed, it is possible to prevent local wear of the catalyst fixed bed or local accumulation of dust on the catalyst fixed bed, thereby suppressing the degradation of the catalyst. Localized deterioration. The denitrification device of the present invention can suppress the reaction between the sulfur content that may be contained in the combustion exhaust gas and ammonia as one of the denitrification agents, thereby reducing the generation of ammonium sulfate.

3: Sieve plate

4: Catalyst fixed bed

6:Reactor conduit

7: Denitrification agent (NH ₃ ) supply line system

G: exhaust

Claims (6)

A denitrification device having: a reactor duct having a flow path for flowing exhaust gas from a boiler; and in the reactor duct, along the flow of the exhaust gas, a screen plate and a denitrification agent supply line system are sequentially provided , a fixed bed containing a denitrification catalyst, and the denitrification agent supply line system has: a heat exchange line, which is used to heat the denitrification agent with the heat retained in the exhaust gas; a conveying line, which is used to heat the denitrification agent. The denitrification agent heated by the heat exchange line is supplied to the nozzle; and the nozzle is used to inject the denitrification agent supplied through the conveying line into the reactor conduit between the screen plate and the fixed bed containing the denitrification catalyst, The denitrification agent supply line system is configured such that in the flow of exhaust gas, the nozzle is arranged immediately downstream of the screen plate and upstream of the heat exchange line. A denitrification device having: an inlet duct having a flow path for flowing exhaust gas from a boiler in a lateral direction; a joint duct having a flow path for changing the flow of exhaust gas from a lateral direction to a longitudinal direction; and a reaction The reactor duct has a flow path that allows the exhaust gas to flow in the longitudinal direction; in the reactor duct, along the flow of the exhaust gas, there are in sequence a sieve plate, a denitrification agent supply line system, and a fixed bed containing a denitrification catalyst. , and the denitrification agent supply line system has: a heat exchange line, which is used to heat the denitrification agent with the heat retained in the exhaust gas; a conveying line, which is used to heat the denitrification agent with the heat exchange line Supply to the nozzle; and the nozzle is used to inject the denitrification agent supplied through the conveyor line into the screen plate and the fixed bed containing the denitrification catalyst. In the reactor duct between the two reactors, the denitrification agent supply line system is set up such that in the flow of exhaust gas, the nozzle is arranged immediately downstream of the screen plate and upstream of the heat exchange line. The denitrification device according to claim 1 or 2, further comprising a structure that supports the screen plate, and the denitrification agent supply line system is supported by the structure that supports the screen plate. The denitrification device according to claim 1 or 2, further comprising a structure that supports the sieve plate and a structure that supports the denitrification agent supply line system. The denitrification agent supply line system is supported by the denitrification agent supply line system. supported by structures. The denitrification device as claimed in claim 1 or 2, wherein the denitrification agent supply line system further has a baffle. The denitrification device according to claim 1 or 2, wherein at least part of the heat exchange line has a heat sink.

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