JP2010264401A - Flue gas denitration apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flue gas denitration apparatus capable of effectively collecting massive ash contained in a flue gas and automatically and completely discharging the collected massive ash while reducing maintenance cost. <P>SOLUTION: The flue gas denitration apparatus is for removing nitrogen oxide contained in the flue gas produced in a coal-burning boiler B and is provided with: a denitration catalyst 12; a guide vane 13 arranged to be inclined against the flow of the flue gas in the upstream side of the denitration catalyst 12 and changing the advancing direction of the massive ash; a collecting part 14 positioned between the guide vane 13 and the denitration catalyst 12 to collect only the massive ash the advancing direction of which is changed by the guide vane 13 while passing the flue gas; a transporting pipe line 22 connecting the collecting part 14 to an external container 21 to which the massive ash collected in the collecting part 14 is transported; and a transporting mechanism 20 possessing a communicating pipe 23 having one end connected to the container 21 and the other end opened in the downstream side of the denitration catalyst 12. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a flue gas denitration apparatus used to remove nitrogen oxides (NO _x ) contained in exhaust gas discharged when fossil fuel such as coal is burned in a boiler.

The flue gas denitration apparatus as described above is disposed following, for example, a vertical flue from a coal-fired boiler (fossil fuel combustor), and the coal flue gas discharged from the coal-fired boiler passes through the vertical flue. Then, in the process of passing through the honeycomb-shaped denitration catalyst layer of the flue gas denitration device from above to below, denitration of NH ₃ injected at the denitration device inlet and nitrogen oxides (NO _x ) contained in the exhaust gas As the reaction proceeds, nitrogen oxides are removed.

Here, the exhaust gas contains fixed substances such as dust (fly ash) and massive ash, and particularly massive ash (popcorn ash) having a large particle size is likely to be clogged with a denitration catalyst, When such massive ash is deposited on the denitration catalyst, clogging of the denitration catalyst prevents the flow of exhaust gas, which hinders the operation of the boiler plant.
Conventionally, as a flue gas denitration apparatus that removes large massive ash that causes clogging of such a denitration catalyst, for example, as disclosed in Patent Document 1, the vertical flue has its There is a screen in which a mesh-like screen (wire mesh) is disposed so as to cross the flow path, and a hopper is disposed in the lower part of the vertical flue. In this flue gas denitration device, a screen in which exhaust gas crosses the flow path When passing through the ash, only large massive ash riding on the flow of exhaust gas is collected, and thereby massive ash falling in the vertical flue is collected by a hopper.

Japanese Patent Laid-Open No. 02-95415

However, in the above-described flue gas denitration device, large lump of ash that has been carried on exhaust gas with a large flow velocity is collected by the screen. There is a problem that it takes time to replace the screen, and it has been a conventional problem to solve this problem.
The present invention has been made paying attention to the above-described conventional problems, and can effectively collect large massive ash contained in exhaust gas after reducing maintenance management costs. An object of the present invention is to provide a flue gas denitration apparatus capable of automatically discharging collected massive ash.

  The invention according to claim 1 of the present invention is a flue gas denitration device for removing nitrogen oxides contained in exhaust gas discharged from a combustor when fossil fuel such as coal is burned in a combustor such as a boiler. A denitration catalyst and a screen-like (wire mesh) that is arranged in an inclined state with respect to the flow of the exhaust gas at the upstream side of the denitration catalyst and changes the traveling direction of massive ash carried on the exhaust gas. A guide vane, a trapping unit that is located between the guide vane and the denitration catalyst, captures only the massive ash whose flowing direction is changed by the guide vane while flowing the exhaust gas, an upstream side of the denitration catalyst, and This flue gas denitration is characterized by having a transfer mechanism for transferring the massive ash captured by the trapping portion to the outside of the exhaust gas system using a pressure difference generated between the downstream sides. And a means for solving the conventional problems described above the configuration of the location.

Further, in the flue gas denitration apparatus according to claim 2 of the present invention, the transfer mechanism includes a transfer pipe connecting the container disposed outside the exhaust gas system and the trapping portion, one end connected to the container and the other. The end is provided with a communication pipe that opens on the downstream side of the denitration catalyst.
At this time, as in the flue gas denitration apparatus according to claim 3 of the present invention, the container is provided with a discharge port for discharging the massive ash transferred from the capturing part to the outside of the container. it can.

  Further, in the flue gas denitration apparatus according to claim 4 of the present invention, the transfer mechanism includes an ash collection unit (hopper) attached to an outlet of an air preheater disposed on the downstream side of the combustor or the denitration catalyst. ), A transfer pipe that connects the ash treatment unit that transfers the dust collected in the above and the capture unit, and a communication pipe that has one end connected to the container and the other end opened downstream of the denitration catalyst. It has a configuration.

In the flue gas denitration apparatus according to the present invention, a catalyst having a honeycomb shape is used as the denitration catalyst, and the contact area with the exhaust gas that passes through the catalyst element with a diameter of about 5 mm while reducing the ventilation resistance is large. The one formed so as to be adopted.
Such a denitration catalyst is installed in a plurality of stages so as to cross the exhaust gas flow path, and a pressure loss caused by the exhaust gas passing through the denitration catalyst occurs between the upstream side and the downstream side of the denitration catalyst. This is a pressure difference. When three stages of denitration catalysts are installed, a pressure difference of about 100 mmAq occurs.

  Moreover, in the flue gas denitration apparatus according to the present invention, it is desirable to use a member that can flow an exhaust gas such as punching metal with almost no stagnation in addition to the metal mesh in the guide vane and the capturing part. At this time, it goes without saying that the size of one mesh or one hole of the metal mesh or punching metal is set smaller than the opening diameter of one block ash or catalyst element to be captured.

In the flue gas denitration apparatus according to the present invention, the exhaust gas generated when fossil fuel such as coal is burned in a combustor such as a boiler is injected at the inlet of the flue gas denitration apparatus in the process of passing through the denitration catalyst. _The nitrogen oxide is removed by advancing a denitration reaction between NO ₃ and nitrogen oxide (NO _x ) contained in the exhaust gas.
During this time, the direction in which the massive ash carried on the exhaust gas travels is changed by the guide vane located on the upstream side of the denitration catalyst, and the massive ash whose traveling direction has been changed is captured by the capture unit, and the capture unit The massive ash caught in the above is transferred out of the exhaust gas system by the transfer mechanism.

At this time, the guide vane that changes the traveling direction of the massive ash carried on the exhaust gas is arranged in an inclined state with respect to the flow of the exhaust gas on the upstream side of the denitration catalyst. The degree of wear due to contact is reduced, and the maintenance management cost can be reduced by the amount that guide vanes are replaced and repaired less frequently.
In addition, the transport mechanism automatically transfers the massive ash captured by the capture unit out of the exhaust gas system due to the pressure difference generated between the upstream side and the downstream side of the denitration catalyst. As a result, there is no accumulation of massive ash, and as a result, there is no need for manual cleaning when the boiler unit is stopped, and there are no problems such as massive ash that has accumulated on the catching part leaking and causing clogging of the denitration catalyst. It becomes.

Since the flue gas denitration apparatus according to claim 1 of the present invention has the above-described configuration, it is possible to reduce the maintenance management cost as well as to efficiently and reliably ensure large massive ash contained in the exhaust gas. It has a very good effect that it can be removed.
In addition, since the flue gas denitration apparatus according to claim 2 of the present invention has the above-described configuration, it can efficiently and reliably remove large massive ash contained in the exhaust gas without causing a complicated structure. This is a very good effect that is possible.

  Furthermore, since the flue gas denitration apparatus according to claims 3 and 4 of the present invention is configured as described above, a very excellent effect is obtained that the collected massive ash can be easily processed.

It is schematic structure explanatory drawing which shows the waste gas process containing the flue gas denitration apparatus by one Example of this invention. It is external appearance expansion explanatory drawing of the flue gas denitration apparatus in FIG. It is external appearance explanatory drawing which looked at the flue gas denitration apparatus in FIG. 1 from the boiler side. FIG. 2 is a partial cross-sectional explanatory view from the side of the flue gas denitration device in FIG. 1.

Embodiments of the present invention will be described below with reference to the drawings.
1 to 4 show a flue gas denitration apparatus according to an embodiment of the present invention.
As shown in FIG. 1, the flue gas denitration device 10 is connected to a coal-saving unit Ba of a coal-fired boiler (combustor) B via a vertical flue 1, and an exhaust gas is connected to the vertical flue 1. ammonia injection nozzle (not shown) by reducing nO _X by injecting ammonia into a nitrogen and water are placed in. On the other hand, on the downstream side of the flue gas treatment flue 2 from the flue gas denitration device 10 to the chimney P, an air heater 3, a dust collector 4, an induction fan 5, a heat exchanger 6, a desulfurization unit 7, and a pushing fan 8 are provided. The air heater 3 heats the external air introduced by the pushing fan 9 with the heat of the exhaust gas discharged from the flue gas denitration device 10 and sends it to the coal-fired boiler B, and the heat exchanger 6 attracts the air. Heat exchange between the exhaust gas after passing through the dust collector 4 guided by the fan 5 and the exhaust gas after passing through the desulfurization unit 7 introduced by the pushing fan 8 is performed.

As shown in FIG. 2, the flue gas denitration device 10 is disposed along the vertical flue 1, and the exhaust gas introduced from the upper end connection flue 1 a of the vertical flue 1 passes through the inside of the duct 11. It flows from top to bottom.
As shown in FIG. 3, the flue gas denitration device 10 is in contact with a denitration catalyst 12 having a honeycomb shape in which the diameter of one opening of a catalyst element is about 5 mm, that is, contact with exhaust gas passing through while reducing ventilation resistance. The denitration catalyst 12 is formed so as to have a large area, and such a denitration catalyst 12 has a plurality of stages (three stages in this embodiment) inside the duct 11 so as to cross the flow path of the exhaust gas. )is set up.

  In this case, as shown in FIG. 4, a guide vane 13 made of a wire mesh is disposed on the upstream side of the denitration catalyst 12 in an inclined state with respect to the horizontal flow of the exhaust gas in the upper end connection flue 1a. ing. The guide vane 13 flows the exhaust gas along the arrow G toward the denitration catalyst 12 side without any delay, while the direction of the massive ash that travels on the exhaust gas and travels horizontally along the upper end connection flue 1a is indicated by the white arrow K. It is designed to change downward.

Further, between the guide vane 13 and the uppermost denitration catalyst 12, a capturing unit 14 that captures only massive ash whose traveling direction is changed downward in the guide vane 13 is disposed.
The capturing unit 14 includes a plurality of inverted triangular pyramid boxes 14b each including a wall surface 11a of the duct 11 located on the boiler B side and two metal mesh inclined plates 14a attached obliquely to the wall surface 11a. These inverted triangular pyramid boxes 14b are arranged adjacent to each other in the width direction of the wall surface 11a of the duct 11.

Further, the flue gas denitration apparatus 10 includes a transfer mechanism 20 that transfers the massive ash captured by the capturing unit 14 to the outside of the exhaust gas system.
In this embodiment, the transfer mechanism 20 includes a plurality of transfer pipes 22 connecting the two containers 21 arranged outside the duct 11 outside the exhaust gas system and the inverted triangular pyramid boxes 14b of the capturing unit 14. In addition, the transfer mechanism 20 includes a communication pipe 23 having one end connected to the upper common space of the two containers 21 and the other end opened downstream of the denitration catalyst 12 at the lowest stage. Using the pressure loss caused by the exhaust gas passing through the three-stage denitration catalyst 12, that is, the pressure difference generated between the upstream side and the downstream side of the three-stage denitration catalyst 12, the massive ash captured by the capture unit 14 is removed. The two containers 21 are automatically transferred.

At this time, the two containers 21 are respectively provided with discharge ports 21a, and by connecting a suction device to these discharge ports 21a, the block ash transferred from the capturing unit 14 by the transfer mechanism 20 is externally provided. To be discharged.
In the flue gas denitration apparatus 1, NH ₃ injected at the inlet of the flue gas denitration apparatus 1 in the process in which exhaust gas generated when coal is burned in the coal-fired boiler B sequentially passes through the three-stage denitration catalyst 12. The nitrogen oxides are removed by advancing a denitration reaction between nitrogen oxides (NO _x ) contained in the exhaust gas.

  Here, when the exhaust gas flows through the guide vane 13 located on the upstream side of the denitration catalyst 12, the exhaust gas itself flows along the arrow G to the denitration catalyst 12 side without any delay, while the upper end connection flue 1a is The advancing direction of the massive ash carried on the exhaust gas is changed downward as indicated by the white arrow K, and the agglomerated ash whose direction is changed in this way is a plurality of inverted triangular pyramid boxes of the capturing unit 14. The block ash captured by each inverted triangular pyramid box 14b of the capturing unit 14 is transferred to the container 21 located outside the exhaust gas system by the plurality of transfer pipes 22 of the transfer mechanism 20.

And when the block ash accumulates in the two containers 21, a suction device is connected to each discharge port 21a of the container 21, and the block ash transferred by the transfer mechanism 20 from the capturing part 14 is discharged to the outside. .
In this embodiment, the guide vane 13 that changes the advancing direction of the massive ash carried on the exhaust gas downward is arranged in an inclined state with respect to the flow of the exhaust gas on the upstream side of the denitration catalyst 12, so that the guide vane The degree of wear due to the contact with the massive ash generated in 13 is reduced, and the maintenance management cost is reduced by the amount that the frequency of replacement and repair of the guide vane 13 is reduced.

  Further, the transfer mechanism 20 automatically transfers the massive ash captured by the capturing unit 14 to the container 21 outside the exhaust gas system due to the pressure difference generated between the upstream side and the downstream side of the three-stage denitration catalyst 12. Therefore, the block ash is not deposited on the trapping part 14, and it is not necessary to perform cleaning by human power, which has been necessary in the prior art. In addition, the block ash deposited on the trapping part 14 leaks down and denitration catalyst. It is possible to avoid the occurrence of problems such as twelve clogging.

That is, the large massive ash contained in the exhaust gas can be removed efficiently and reliably.
Further, in the above-described flue gas denitration apparatus 10, the suction device is connected to each discharge port 21a of the container 21 so that the massive ash accumulated in the two containers 21 is discharged to the outside. Processing of the lump ash thus obtained can be easily performed.
In the above-described embodiment, the inclined plate 14a of the inverted triangular pyramid box 14b in the guide vane 13 and the capturing part 14 is made of a metal mesh, but is not limited to this. For example, punching instead of the metal mesh is performed. Metal may be adopted.

  Further, in the above-described embodiment, the transfer pipe 22 of the transfer mechanism 20 is configured to connect the container 21 and the capturing unit 14. However, the present invention is not limited to this. For example, the transfer pipe of the transfer mechanism 20 22 shows the dust collected by the ash collection part (hopper) attached to the outlets of the heat exchangers (air preheaters) 3 and 6 disposed downstream of the coal burning boiler B and the denitration catalyst 12. You may comprise so that the ash processing part to transfer and the capture | acquisition part 14 may be tied.

DESCRIPTION OF SYMBOLS 10 Flue gas denitration apparatus 12 Denitration catalyst 13 Guide vane 14 Capture part 20 Transfer mechanism 21 Container 21a Discharge port 22 Transfer piping (transfer mechanism)
23 Communication pipe (transfer mechanism)
B Coal fired boiler (combustor)

Claims (4)

A flue gas denitration device for removing nitrogen oxides contained in exhaust gas discharged from a combustor when fossil fuel such as coal is burned in a combustor such as a boiler,
A denitration catalyst,
A guide vane that is disposed on the upstream side of the denitration catalyst in an inclined state with respect to the flow of the exhaust gas, and changes a traveling direction of the bulk ash carried on the exhaust gas;
A trap that is located between the guide vane and the denitration catalyst and captures only the massive ash whose direction of travel is changed by the guide vane while flowing the exhaust gas,
A flue gas characterized by comprising a transport mechanism for transporting the massive ash captured by the trapping unit out of the exhaust gas system using a pressure difference generated between the upstream side and the downstream side of the denitration catalyst. Denitration equipment.   The transfer mechanism includes a transfer pipe that connects a container disposed outside the exhaust gas system and the capture unit, and a communication pipe having one end connected to the container and the other end opened downstream of the denitration catalyst. The flue gas denitration device according to claim 1.   The flue gas denitration device according to claim 2, wherein the container is provided with a discharge port for discharging the massive ash transferred from the capturing unit to the outside of the container.   The transfer mechanism includes a transfer pipe connecting an ash treatment unit attached to an outlet of an air preheater disposed on the downstream side of the combustor and the denitration catalyst and the capture unit, one end connected to the container, and The flue gas denitration device according to claim 1, further comprising a communication pipe having the other end opened downstream of the denitration catalyst.

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