JP6836168B2 - Denitration device - Google Patents

Description

The present invention relates to a denitration device used in a coal-fired power generation facility or the like.

In coal-fired power generation facilities, nitrogen oxides are generated as coal burns. Due to regulations such as the Air Pollution Control Act, it is necessary to keep such nitrogen oxide emissions below a certain level. For this reason, a denitration device for reducing and decomposing nitrogen oxides is installed.
The denitration device is filled with a denitration catalyst, and by coexisting with ammonia (gas), a reduction reaction is exhibited at a high temperature.

As the denitration catalyst continues to be used, the through holes of the denitration catalyst may be blocked by coal ash contained in the flowing air. One of the factors is the phenomenon that coal ash is deposited on the reinforcing beams installed between the layers of the denitration catalyst, and when a certain amount of coal ash is deposited, it drops to the denitration catalyst at once.

When the coal ash falls at once, the coal ash becomes a lump and closes the through hole. When the through hole is closed, the differential pressure between the inlet and outlet of the denitration device increases, and finally, the coal-fired power generation facility needs to be shut down and cleaned. Further, when a part of the through hole is closed, the contact area between the exhaust gas and the denitration catalyst is reduced, the performance of the denitration device is deteriorated, and the deterioration of the denitration catalyst is promoted. Further, since the exhaust gas flows into the through holes that are not closed, the flow velocity increases and the denitration catalyst is partially worn.

Therefore, it is necessary to remove these coal ash, and such coal ash removal is a method of removing the accumulated coal ash by directly blowing air (or steam) to the denitration catalyst during the operation of the coal-fired power generation facility. There is. However, these can cause wear and tear of the catalyst. In addition, there are also a cleaning method in which the coal-fired power generation facility is stopped and the coal ash is sucked by a prober, a cleaning method in which the coal ash is removed by air, and the like (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2001-223404

However, these methods require a large amount of cost because the coal-fired power generation equipment needs to be stopped for several days to perform the work.
An object of the present invention is to provide a denitration device capable of easily preventing blockage of through holes provided in a denitration catalyst.

The denitration device of the present invention is a denitration device that denitrifies a gas containing nitrogen oxides, and is provided with a plurality of through holes extending in the longitudinal direction to denitrate the gas containing nitrogen oxides passing through the through holes. It includes a denitration catalyst layer having a denitration catalyst, a reinforcing beam member arranged on the upstream side of the gas in the denitration catalyst layer, and a blockage prevention structure for preventing blockage of the through hole.

The blockage prevention structure is a deposit removing structure for removing deposits deposited on the beam member, and has an air blowing portion that extends upstream of the gas with respect to the beam member and faces the beam member side. A provided tubular member and an air supply unit that supplies air to the tubular member may be provided.

The blockage prevention structure is a deposit removing structure for removing deposits deposited on the beam member, and an air blowing portion that extends downstream of the gas with respect to the beam member and faces the beam member side. A tubular member provided and an air supply unit for supplying air to the tubular member may be provided, and the beam member may be provided with a plurality of through holes.

The blockage prevention structure is a deposit removing structure for removing deposits deposited on the beam member, and may include a driving unit that vibrates the beam member.

The blockage prevention structure is a deposit removing structure for removing deposits deposited on the beam member, and may include a driving unit for rotating the beam member.

The blockage prevention structure may be a driving unit that vibrates the denitration catalyst layer.

The blockage prevention structure may be movable along the denitration catalyst layer and may include an ultrasonic system including an ultrasonic sensor and an ultrasonic generator, and a movable arm to which the ultrasonic system is attached. ..

According to the present invention, it is possible to provide a denitration device capable of easily preventing blockage of a through hole provided in a denitration catalyst.

It is a block diagram of the coal-fired power generation facility 100 in which the denitration device of the embodiment is used. It is a block diagram of the denitration device 160. It is a figure explaining the blockage prevention structure 10 of the 1st Embodiment of this invention. It is a figure explaining the blockage prevention structure 20 of the 2nd Embodiment of this invention, (a) is a conceptual diagram, (b) is a sectional view of a portion including an air blowing hole. It is a figure explaining the blockage prevention structure 30 of the 3rd Embodiment of this invention. It is a figure explaining the blockage prevention structure 40 of the 4th Embodiment of this invention. It is a figure explaining the blockage prevention structure 50 of the 5th Embodiment of this invention. It is a figure explaining the blockage prevention structure 70 of the 6th Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a coal-fired power generation facility 100 in which the denitration device 160 of the embodiment is used.

As shown in FIG. 1, the coal-fired power generation facility 100 includes a coal bunker 120, a coal feeder 125, a pulverized coal machine 130, a combustion boiler 140, and an exhaust passage 150 provided on the downstream side of the combustion boiler 140. , Denitration device 160, air preheater 170, electrostatic dust collector 190, gas heater (for heat recovery) 180, induction blower 210, desulfurization device 220, gas heater (for reheating) 230, desulfurization provided in the exhaust passage 150. A blower 240 and a chimney 250 are provided.

The coal bunker 120 stores coal supplied by a coal transport facility from a coal silo (not shown). The coal feeder 125 supplies the coal supplied from the coal bunker 120 to the pulverized coal mill 130 at a predetermined supply speed.
The pulverized coal machine 130 crushes the coal supplied from the coal feeder 125 to produce pulverized coal. In the pulverized coal machine 130, coal is pulverized to an average particle size of 60 μm to 80 μm. The particle size distribution of the pulverized coal is 10 to 15% for 150 μm or more, 30 to 40% for 75 μm to 150 μm, and 45 to 60% for less than 75 μm.
As the pulverized coal mill 130, a roller mill, a tube mill, a ball mill, a beater mill, an impeller mill and the like are used.

The combustion boiler 140 burns the pulverized coal supplied from the pulverized coal machine 130 together with the forcedly supplied air. Combustion of pulverized coal produces coal ash such as clinker ash and fly ash, and also generates exhaust gas.
The cleaner ash refers to the lumpy coal ash that has fallen to the bottom of the combustion boiler 140 among the coal ash generated when the pulverized coal is burned. Further, fly ash is a coal ash generated when pulverized coal is burned, and has a particle size (particle size of about 200 μm or less) that is blown up together with combustion gas (exhaust gas) and flows to the exhaust passage 150 side. Spherical coal ash.

The exhaust passage 150 is arranged on the downstream side of the combustion boiler 140, and circulates the exhaust gas generated in the combustion boiler 140 and the generated coal ash. As described above, the exhaust passage 150 includes a denitration device 160, an air preheater 170, a gas heater (for heat recovery) 180, an electrostatic precipitator 190, an induction ventilator 210, a desulfurization device 220, and a gas heater (for reheating). ) 230, a desulfurization ventilator 240, and a chimney 250 are arranged.

The denitration device 160 removes nitrogen oxides in the exhaust gas, which will be described later. In the present embodiment, the denitration device 160 injects ammonia gas as a reducing agent into the exhaust gas at a relatively high temperature (300 ° C. to 400 ° C.), and by acting with the denitration catalyst, the nitrogen oxides in the exhaust gas are converted into harmless nitrogen. Nitrogen oxides in the exhaust gas are removed by the so-called dry ammonia catalytic reduction method, which decomposes into water vapor.

The air preheater 170 is arranged on the downstream side of the denitration device 160 in the exhaust passage 150. The air preheater 170 exchanges heat between the exhaust gas that has passed through the denitration device 160 and the combustion air sent from the push-in type ventilator 75, cools the exhaust gas, and heats the combustion air.

The gas heater 180 is arranged on the downstream side of the air preheater 170 in the exhaust passage 150. Exhaust gas recovered from heat by the air preheater 170 is supplied to the gas heater 180. The gas heater 180 further recovers heat from the exhaust gas.

The electrostatic precipitator 190 is arranged on the downstream side of the gas heater 180 in the exhaust passage 150. Exhaust gas recovered from heat by the gas heater 180 is supplied to the electrostatic precipitator 190. The electrostatic precipitator 190 is a device that collects coal ash (fly ash) in exhaust gas by applying a voltage to the electrodes. The fly ash collected by the electrostatic precipitator 190 is collected by the fly ash recovery device 126.

The attraction ventilator 210 is arranged on the downstream side of the electrostatic precipitator 190 in the exhaust passage 150. The attraction ventilator 210 takes in the exhaust gas from which the fly ash has been removed in the electrostatic precipitator 190 from the primary side and sends it out to the secondary side.

The desulfurization device 220 is arranged on the downstream side of the induction ventilator 210 in the exhaust passage 150. The exhaust gas sent from the induction ventilator 210 is supplied to the desulfurization apparatus 220. The desulfurization apparatus 220 sprays a mixed solution of limestone and water on the exhaust gas to absorb the sulfur oxides contained in the exhaust gas into the mixed solution to generate a desulfurized gypsum slurry, and dehydrates the desulfurized gypsum slurry. This produces desulfurized gypsum. The desulfurization gypsum produced in the desulfurization device 220 is recovered by the desulfurization gypsum recovery device 222 connected to this device.

The gas heater 230 is arranged on the downstream side of the desulfurization apparatus 220 in the exhaust passage 150. The gas heater 230 is supplied with exhaust gas from which sulfur oxides have been removed in the desulfurization apparatus 220. The gas heater 230 heats the exhaust gas. The gas heater 180 and the gas heater 230 are between the exhaust gas flowing between the air preheater 170 and the electrostatic precipitator 190 and the exhaust gas flowing between the desulfurization device 220 and the desulfurization ventilator 240 in the exhaust passage 150. It may be configured as a gas heater that exchanges heat with.

The desulfurization ventilator 240 is arranged on the downstream side of the gas heater 230 in the exhaust passage 150. The desulfurization ventilator 240 takes in the exhaust gas heated by the gas heater 230 from the primary side and sends it out to the secondary side.
The chimney 250 is arranged on the downstream side of the desulfurization ventilator 240 in the exhaust passage 150. Exhaust gas heated by the gas heater 230 is introduced into the chimney 250. The chimney 250 emits exhaust gas.

FIG. 2 shows a configuration diagram of the denitration device 160.
As shown in FIG. 2, the denitration device 160 includes a housing 61 and a plurality of stages of denitration catalyst layers 62 arranged inside the housing 61.

The housing 61 serves as a place for a denitration reaction in the denitration device 160, and is provided with an inlet side opening 63 and an outlet side opening 64 for exhaust gas. The exhaust gas flows from the inlet side opening 63 to the outlet side opening 64 as shown by the arrow A in the figure. As shown in the figure, the denitration catalyst layer 62 includes a plurality of honeycomb-type denitration catalysts 622 as an example.

The denitration catalyst 622 has a long shape (rectangular parallelepiped shape) in which a plurality of through holes 624 extending in the longitudinal direction are formed. The plurality of denitration catalysts 622 are arranged so that the extending direction of the through hole 624 is along the flow path A of the exhaust gas. In the present embodiment, the plurality of denitration catalysts 622 are arranged inside the housing 61 in a state of being housed in the casing 621.

A gap 65 is provided between the denitration catalyst layers 62, and a beam member 66 for reinforcing the denitration device 160 is provided in the gap 65. The beam member 66 is not limited to the structure shown in FIG. 2, and the shape shown in FIG. 2 is an example.
The denitration device 160 is arranged on the downstream side of the combustion boiler 140, and circulates the exhaust gas generated by the combustion boiler 140 and the generated coal ash. Therefore, during the operation of the coal-fired power generation facility 100, coal ash (sediment) is deposited on the beam member 66 of the denitration catalyst 622.
If this accumulated coal ash is not properly removed, it may agglomerate and fall into the through hole 624 of the denitration catalyst 622, blocking the through hole 624. When the through hole 624 is closed, the denitration function of the denitration catalyst 622 deteriorates. Therefore, in the present embodiment, a blockage prevention structure for preventing blockage of the through hole 624 is provided.

(First Embodiment)
FIG. 3 is a diagram for explaining the blockage prevention structure (deposit removal structure) 10 of the first embodiment of the present invention. As shown in the figure, the side wall portion 67 of the housing 61 is provided with an insertion hole 68. A tubular member 11 is slidably penetrated through the insertion hole 68.
The internal portion of the housing 61 of the tubular member 11 extends along the beam member 66 at the upper part of the beam member 66 (upstream side of the exhaust gas flow). At the tip of the tubular member 11, an air blowing portion 12 projecting toward the beam member 66 side (downstream side) is provided.
Further, in the outer portion of the housing 61 of the cylinder member 11, an air cylinder that expands and contracts the cylinder member 11 in the length direction B (direction orthogonal to the inflow direction of exhaust gas) of the beam member 66 indicated by the arrow in the drawing. And the like, and a ventilation mechanism 14 such as an air pump that blows air to the cylinder member 11 are attached.

During the operation of the coal-fired power generation facility 100, coal ash is deposited on the upstream side of the beam member 66. Therefore, the cylinder member 11 is driven before the accumulated amount of coal ash increases. That is, air is blown out from the air blowing portion 12 provided at the tip of the tubular member 11. Then, the air is blown out to the upstream side of the beam member 66 where the coal ash is deposited, so that the coal ash deposited on the beam member 66 is blown off and falls into the through hole 624 of the denitration catalyst 622.

Then, when the tubular member 11 is expanded and contracted in the direction B by the expansion / contraction mechanism 13, the air blowing portion 12 moves along the beam member 66. Therefore, the accumulated coal ash is sequentially blown off in the direction B in the beam member 66.
The expansion and contraction of the tubular member 11 by the expansion and contraction mechanism 13 may be performed at a constant speed along the direction B so that air is uniformly injected to the entire beam member 66, and coal is used in the beam member 66. The spray may be focused on the places where ash is likely to accumulate. The place where coal ash is likely to be deposited is a place corresponding to the shape of the beam member 66, for example, a place having a large area in the direction perpendicular to the flow of exhaust gas.

According to this embodiment, the expansion / contraction mechanism 13 and the ventilation mechanism 14 can be appropriately operated to drop the coal ash without stopping the coal-fired power generation facility 100. Therefore, since the work can be performed more frequently than the work of stopping the coal-fired power generation facility 100, the coal ash can be dropped before the accumulated amount of coal ash becomes too large.
When the accumulated amount of coal ash is small, the dropped coal ash can pass through the through hole 624 of the denitration catalyst 622, and the through hole 624 is not blocked. Therefore, the through hole 624 of the denitration catalyst 622 is not blocked and the denitration function of the denitration catalyst 622 is not deteriorated.

Further, when a part of the through hole 624 is closed, the exhaust gas flows into the through hole 624 which is not closed, so that the flow velocity may increase and the denitration catalyst 622 may be worn, but the through hole 624 is not closed. There is no such thing.

Then, since it is possible to prevent the through hole 624 from being blocked without directly blowing air (or steam) onto the denitration catalyst 622, the denitration catalyst 622 is not worn or damaged.

Further, since the denitration device 160 of the present embodiment can remove coal ash during the operation of the coal-fired power generation facility 100, the possibility of unplanned facility stoppage and coal ash cleaning work is reduced, leading to cost reduction. ..

The blockage prevention structure 10 may be continuously operated during the operation of the coal-fired power generation facility 100, or may be operated at regular intervals.

(Second Embodiment)
4A and 4B are views for explaining the blockage prevention structure (deposit removal structure) 20 of the second embodiment of the present invention, in which FIG. 4A is a conceptual diagram and FIG. 4B is along the line CC of FIG. , Is a cross-sectional view of a portion including an air blowing hole 266A. In the figure, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.
In the present embodiment, the internal portion of the housing 61 of the tubular member 21 extends along the beam member 266 on the downstream side of the beam member 266. At the tip of the tubular member 21, an air blowing portion 22 protruding toward the beam member 266 side (upstream side) is provided.
The beam member 266 of the present embodiment is provided with a plurality of air blowing holes 266A. As shown in FIG. 4B, the air blowing hole 266A is cut diagonally so that the air flowing from the inside of the beam member 266 to the outside through the air blowing hole 266A goes downward, and is cut along the edge of the beam member. The air is flowing.

Also in this embodiment, during the operation of the coal-fired power generation facility 100, coal ash is deposited on the upstream side of the beam member 266. Therefore, the cylinder member 21 is driven before the accumulated amount of coal ash increases. That is, air is blown out from the air blowing portion 22 provided at the tip of the tubular member 21. Then, the air flows from the inside of the beam member 266 to the outside through the air blowing hole 266A, and the air that has flowed out is turned in the direction A by the flow of the exhaust gas.
At this time, the coal ash deposited on the beam member 266 is also dropped in the downstream direction along the air flow direction A and falls into the through hole 624 of the denitration catalyst 622. Therefore, this embodiment also has the same effect as that of the first embodiment.

(Third Embodiment)
FIG. 5 is a diagram illustrating a blockage prevention structure (deposition removal structure) 30 according to a third embodiment of the present invention.
In the present embodiment, the beam member 366 is connected to the drive unit 31 and can vibrate in the direction A and the directions A and B by the drive unit 31.

Also in this embodiment, coal ash is deposited on the upstream side of the beam member 366 during the operation of the coal-fired power generation facility 100. Therefore, the drive unit 31 is started before the accumulated amount of coal ash increases. Then, the beam member 366 starts to vibrate in the direction A and the direction B. Due to this vibration, the coal ash accumulated on the upstream side of the beam member 366 is shaken off and falls into the through hole 624 of the denitration catalyst 622. Therefore, this embodiment also has the same effect as that of the first embodiment.

(Fourth Embodiment)
FIG. 6 is a diagram illustrating a blockage prevention structure (deposition removal structure) 40 according to a fourth embodiment of the present invention.
In the present embodiment, the beam member 466 has, for example, a cylindrical shape, and, for example, a cylindrical outer cylinder 466B is arranged on the outer periphery of the beam member 466. The outer cylinder 466B is connected to the drive unit 41 and can be rotated by the drive unit 41.

Also in this embodiment, coal ash is deposited on the upstream side of the outer cylinder 466B during the operation of the coal-fired power generation facility 100. Therefore, the drive unit 41 is started before the accumulated amount of coal ash increases. Then, the outer cylinder 466B rotates. By this rotation, the coal ash deposited on the outer cylinder 466B is shaken off and falls into the through hole 624 of the denitration catalyst 622. Therefore, this embodiment also has the same effect as that of the first embodiment.

(Fifth Embodiment)
FIG. 7 is a diagram illustrating a blockage prevention structure (deposition removal structure) 50 according to a fifth embodiment of the present invention.
In the present embodiment, the blockage prevention structure 50 is provided on the denitration catalyst layer 62. The blockage prevention structure 50 is a drive unit 51 capable of vibrating the denitration catalyst layer 62 in directions A and B.

In the present embodiment, during the operation of the coal-fired power generation facility 100, coal ash is deposited on the upstream side of the beam member. Therefore, the drive unit 51 is started before the accumulated amount of coal ash increases. Then, the denitration catalyst layer 62 starts to vibrate in the direction A and the direction B. Due to this vibration, the coal ash deposited on the upstream side of the beam member of the denitration catalyst is shaken off and falls into the through hole of the denitration catalyst. Therefore, this embodiment also has the same effect as that of the first embodiment.

(Sixth Embodiment)
FIG. 8 is a diagram illustrating a blockage prevention structure 70 according to a sixth embodiment of the present invention.
As shown in the figure, the side wall portion 67 of the housing 61 is provided with an insertion hole 68. A movable arm 71 is slidably penetrated through the insertion hole 68. The inner portion of the housing 61 of the movable arm 71 extends above the denitration catalyst layer 62 along the denitration catalyst layer 62. An ultrasonic system 72 projecting toward the denitration catalyst layer 62 side (downstream side) is attached to the tip of the movable arm 71.
The ultrasonic system 72 includes an ultrasonic sensor and an ultrasonic generator. Further, in the movable arm 71, a moving portion 73 for moving the movable arm 71 in the direction B and a driving portion 74 for driving the ultrasonic system 72 are attached to the outer portion of the housing 61.

During the operation of the coal-fired power generation facility 100, coal ash may be deposited on the beam member, and after a certain amount of coal ash is deposited, it may drop onto the denitration catalyst 622 at once. Then, the through hole of the denitration catalyst of the denitration catalyst layer 62 may be blocked.
Therefore, in the present embodiment, the ultrasonic system 72 is driven by the moving unit 73 and the driving unit 74. The ultrasonic system 72 provided at the tip of the movable arm 71 moves in the direction B along the denitration catalyst layer 62, and searches for the blocked portion of the through hole in the denitration catalyst layer 62 by the ultrasonic sensor. Then, when the blocked portion is found, ultrasonic waves are generated from the ultrasonic generator to decompose the coal ash lump that is blocking the through hole and eliminate the blockage of the through hole.
In this embodiment as well, since coal ash can be removed during the operation of the coal-fired power generation facility 100, the possibility of unplanned system stoppage and coal ash cleaning work is reduced, leading to cost reduction.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and for example, a plurality of blockage prevention structures of the above embodiments may be combined and provided in the catalyst device.

10, 20, 30, 40, 50, 70 Blockage prevention structure (deposition removal structure)
11,21 Cylinder member 12,22 Blow-out part 13 Telescopic mechanism 14 Blower part 31,41,51 Drive part 61 Casing 62 Denitration catalyst layer 63 Inlet side opening 64 Outlet side opening 65 Gap 66,266,366,466 Beam Member 67 Side wall part 68 Insertion hole 71 Movable arm 72 Ultrasonic system 73 Moving part 74 Drive part 100 Coal-fired power generation equipment 160 Denitration device 266A Outlet hole 466B Outer cylinder 621 Casing 622 Denitration catalyst 624 Through hole

Claims (3)

It is a denitration device that denitrifies gas containing nitrogen oxides.
A denitration catalyst layer having a plurality of through holes extending in the longitudinal direction and having a denitration catalyst for denitration of a gas containing nitrogen oxides passing through the through holes.
Reinforcing beam members arranged on the upstream side of the gas in the denitration catalyst layer,
An obstruction prevention structure that prevents obstruction of the through hole and
With
The blockage prevention structure is a deposit removing structure for removing deposits deposited on the beam member.
A tubular member that extends downstream of the gas with respect to the beam member and is provided with an air blowing portion that faces the beam member side.
An air supply unit that supplies air to the tubular member is provided.
The beam member is provided with a plurality of through holes.
Denitration device. It is a denitration device that denitrifies gas containing nitrogen oxides.
A denitration catalyst layer having a plurality of through holes extending in the longitudinal direction and having a denitration catalyst for denitration of a gas containing nitrogen oxides passing through the through holes.
Reinforcing beam members arranged on the upstream side of the gas in the denitration catalyst layer,
An obstruction prevention structure that prevents obstruction of the through hole and
With
The blockage prevention structure is a deposit removing structure for removing deposits deposited on the beam member.
A drive unit for rotating the beam member is provided.
Denitration device. It is a denitration device that denitrifies gas containing nitrogen oxides.
A denitration catalyst layer having a plurality of through holes extending in the longitudinal direction and having a denitration catalyst for denitration of a gas containing nitrogen oxides passing through the through holes.
Reinforcing beam members arranged on the upstream side of the gas in the denitration catalyst layer,
An obstruction prevention structure that prevents obstruction of the through hole and
With
The blockage prevention structure is
An ultrasonic system that is movable along the denitration catalyst layer and includes an ultrasonic sensor and an ultrasonic generator.
A movable arm to which the ultrasonic system is attached.
Denitration device.

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