WO2020204122A1

WO2020204122A1 - Boiler

Info

Publication number: WO2020204122A1
Application number: PCT/JP2020/015142
Authority: WO
Inventors: 三紀下郡; 康一郎森; 村上　和生; 康横山; 貴士出井; 山口　良祐
Original assignee: 三菱日立パワーシステムズ株式会社
Priority date: 2019-04-05
Filing date: 2020-04-02
Publication date: 2020-10-08

Abstract

This boiler (1) is characterized by comprising: a furnace (2); a sub lateral wall part (12) provided on the gas-flow-direction downstream side of an upper part of the furnace (2); a can rear part (11) disposed in rear of the sub lateral wall part (12); and a soot removing device (21) that has a nozzle (22) configured to be accessible to the inside of the sub lateral wall part (12) from the bottom surface (13) of the sub lateral wall part (12) and that removes soot on the bottom surface (13) of the sub lateral wall part (12) by spraying a soot removing medium from the nozzle (22). The present invention can suppress deposition of ash in the bottom surface of the sub lateral wall part compared to conventional configurations even when low-quality coal is used.

Description

boiler

The present invention relates to a boiler equipped with a fireplace, and more particularly to a boiler equipped with a soot blower device for removing ash adhering to a heat transfer tube.

The techniques described in Patent Documents 1 to 4 below are known with respect to a soot blower for removing ash adhering to a heat transfer tube in a boiler that burns solid fuel particles such as pulverized coal obtained by crushing coal.

In Patent Document 1 (Japanese Unexamined Patent Publication No. 2002-286201), an air hole (9) is provided in the membrane bar (8) of the heat transfer tube (1) located above the bottom wall (6) of the sub-side wall portion (30). Is provided, and the ash accumulated on the bottom of the sub-side wall portion (30) is floated by air (soot removing medium) or gas (soot removing medium) from the air hole (9) and discharged to the outside of the furnace. Are listed.

In Patent Document 2 (Japanese Patent Publication No. 64-38405), steam (soot removing medium) is introduced from the nozzle (5) of the soot blower (3) toward the protective plate (4) of the furnace wall tube (1) of the fireplace. The technique of spouting and cleaning is described.

According to Patent Document 3 (Japanese Unexamined Patent Publication No. 58-127014), the nozzle (4a) moves forward and backward along the axial direction of the outer tube (4) in the soot blower for removing soot adhering to the heat transfer surface of the boiler. The configuration is described.

In Patent Document 4 (Patent No. 2774107), a plurality of short pull-out type soot blowers (1) are arranged on the left and right side walls of the can at a position (A) slightly above the burner (2) to remove soot. The configuration to be used is described.

JP-A-2002-286201 ("0011"-"0012", FIGS. 1, 2) Jikkai Sho 64-38405 (Page 10, Line 10, Page 11, Line 12, Fig. 1) Japanese Unexamined Patent Publication No. 58-127014 (Page 2, upper left column, line 2 to lower left column, line 12, FIG. 1) Japanese Patent No. 2774107 (Page 1, right column, line 6 to page 2, left column, line 20, FIG. 2)

FIG. 3 is an explanatory diagram of a conventional boiler, FIG. 3 (A) is an explanatory diagram of the ash accumulation state when using conventional high-grade coal, and FIG. 3 (B) is an explanatory diagram of ash accumulation state when using poor coal. It is explanatory drawing.
In FIG. 3A, in the conventional boiler 01, a plurality of heat transfer tubes 03 are installed in a state of being suspended above the fireplace 02, and the heat transfer tubes 05 are also installed at the rear portion 04 of the can behind the fireplace 02. Has been done. The upper part of the fireplace 02 and the rear part 04 of the can are connected by a sub-side wall portion 06.
Here, coal usually contains 10% to 20% of ash, and there is a problem that the combustion ash generated by combustion is deposited on the bottom wall portion 06a of the auxiliary side wall portion 06 that connects from the fireplace 02 to the can rear portion 04. Occurs. The following two mechanisms are considered for the mechanism of ash deposition.
(1) The ash scattered from the fireplace 02 side is captured and deposited in the gas flow retention region (the region where the flow velocity is slow near the sub-side wall bottom wall portion 06a).
(2) The ash (lumpy ash) adhering to the hanging portion (heat transfer tube 03) falls off, is carried by the gas flow, and is deposited on the bottom wall portion 06a of the sub-side wall. Although not shown, the heat transfer tube 03 may be installed on the upper part of the sub-side wall bottom wall portion 06a, and in that case, the ash fallen from the upper part of the sub-side wall bottom wall portion 06a is also deposited.

In the prior art, in order to suppress the accumulation of ash on the sub-side wall portion 06, (i) the horizontal portion of the sub-side wall bottom wall portion 06a is reduced and inclined, and (ii) the

heat transfer tubes

03 and 05 are supported. Measures are taken such as providing a soot blower 07 of the same long insertion / removal type (type that is inserted / removed in the front-rear direction, see Patent Documents 1 and 2) in the vicinity of the bottom wall portion 06a of the sub-side wall.
With conventional coal (equivalent to bituminous coal), the ash deposited on the bottom wall of the sub-side wall 06a is granular and does not grow above the angle of repose (ash above the angle of repose collapses). Further, since the planned value of the gas temperature of the auxiliary side wall portion 06 is planned to be lower than the melting point of the ash, the progress of sintering is slow, and the accumulation of ash can be suppressed by blowing the soot blower 07 at a predetermined frequency. Is.

However, inferior charcoal ash, which will be expanded in the future, has high adhesiveness due to its high alkalinity and low melting point. Conventionally, even if ash is deposited, it does not sinter, so it slides off, or even if it accumulates to some extent, it can be easily decalcified with the soot blower 07 (FIG. 3 (A)). On the other hand, in the case of inferior charcoal, the ash that should have slipped off due to the incline adheres to the inclined portion 08 on the nose during dedicated combustion (only inferior charcoal is used) and co-firing, and the ash accumulation proceeds from this However, it has been found that it grows into a large lumpy ash like honeycomb toffee (Fig. 3 (B)).
In particular, since the lower end 08a side of the nose upper inclined portion 08 greatly deviates from the effective range 07a of the soot blower 07, there is a problem that the conventional soot blower 07 cannot cope with it. Further, in the case of inferior charcoal, since the ash is easily melted, once it adheres, the ash adhesion accelerates, and there is a problem that the flow path is blocked and the fireplace is shut down.

The technical subject of the present invention is to suppress the accumulation of ash on the bottom surface of the sub-side wall portion as compared with the conventional configuration even when low-grade coal is used.

The above object of the present invention can be achieved by adopting the following configuration.
The invention according to claim 1 is a furnace, a sub-side wall provided on the downstream side in the gas flow direction above the fireplace, a can rear portion arranged behind the sub-side wall portion, and a can rear portion. It has a nozzle configured so that it can be taken in and out from the bottom of the upstream side toward the inside of the gas flow, and is equipped with a soot removal device that ejects a soot removal medium from the nozzle to remove soot from the bottom. It is a boiler characterized by.

The invention according to claim 2 is the boiler according to claim 1, further comprising the nozzle for injecting a soot removing medium along the bottom portion.

The invention according to claim 3 is characterized in that the soot removing device having the nozzles arranged at intervals along the left-right direction intersecting the gas flow direction is provided. The boiler according to 2.

The invention according to claim 4 is the boiler according to claim 3, wherein the nozzles adjacent to each other in the left-right direction are arranged at positions shifted from each other in the front-rear direction.

According to the first aspect of the present invention, the nozzle that can be taken in and out from the bottom surface of the sub-side wall portion can blow soot and ash from the bottom wall of the sub-side wall portion, and enters and retreats from the left and right sides of the conventional sub-side wall portion. Compared to the configuration using a nozzle, a wide range of soot can be removed with a short nozzle. Therefore, even when low-grade coal is used, it is possible to suppress the accumulation of ash on the bottom surface of the sub-side wall portion as compared with the conventional configuration.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, since the soot-removing medium is ejected along the bottom surface of the sub-side wall portion, the soot-removing medium is ejected perpendicularly to the bottom surface. Compared with the case where the bottom surface is worn over time, wear is suppressed and the flow of combustion gas is also reduced.

According to the invention of claim 3, in addition to the effect of the invention of

claim

1 or 2, the soot-removing medium ejected from a plurality of nozzles covers a wide range of the bottom wall of the sub-side wall portion. be able to.

According to the invention of claim 4, in addition to the effect of the invention of claim 3, the bottom wall of the sub-side wall portion is wider with a smaller number of nozzles as compared with the case where the nozzles are arranged in a row. The area can be cleaned.

1A and 1B are schematic explanatory views of a boiler according to an embodiment of the present invention, FIG. 1A is an overall view, and FIG. 1B is a plan view. 2A and 2B are explanatory views of the soot removing device of the first embodiment, FIG. 2A is an explanatory view of a state of being moved to a protruding position, and FIG. 2B is an explanatory view of a state of being moved to a buried position. FIG. 3 is an explanatory diagram of a conventional boiler, FIG. 3 (A) is an explanatory diagram of the ash accumulation state when using conventional high-grade coal, and FIG. 3 (B) is an explanatory diagram of ash accumulation state when using poor coal. It is explanatory drawing.

The embodiments of the present invention are shown below.

1A and 1B are schematic explanatory views of a boiler according to an embodiment of the present invention, FIG. 1A is an overall view, and FIG. 1B is a plan view.
In addition, in the present specification and claims, a boiler fireplace may be referred to as a "can".
In FIG. 1, in the coal-fired boiler 1 of the first embodiment of the present invention, the fireplace 2 has a water pipe portion in which a burner or the like (not shown) is installed. The fireplace 2 has a can front wall 2a, a can rear wall 2b, and side walls 2c and 2d. A suspended heat transfer section (heat transfer tube group, heat exchanger) 4 is arranged on the ceiling above the furnace 2 along the flow direction of the combustion gas burned by the burner, and on the rear wall 2b side of the can. , Banks (heat transfer tubes, heat exchangers) 7 are arranged.
Further, the upper part of the fireplace 2 and the rear portion 11 of the can are connected by a sub-side wall portion 12. The bottom wall 13 of the secondary side wall portion 12 is connected to the inclined surface 14 toward the nose tip portion 14a on the front side of the can. A soot blower 16 for removing soot adhering to the heat transfer tube is installed around the suspended heat transfer section 4 and the bank 7.

2A and 2B are explanatory views of the soot removing device of the first embodiment, FIG. 2A is an explanatory view of a state of being moved to a protruding position, and FIG. 2B is an explanatory view of a state of being moved to a buried position.
In FIGS. 1 and 2, a wall blower 21 as an example of the soot removing device is arranged on the bottom wall 13 of the sub-side wall portion 12 and the inclined surface 14 on the can front side of the bottom wall 13. In FIG. 1B, the wall blowers 21 of the first embodiment are arranged at intervals along the left-right direction of the boiler 1. In particular, in the first embodiment, the wall blowers 21 adjacent to each other in the left-right direction are arranged at positions deviated from the front-rear direction, which is the gas flow direction in the sub-side wall portion 12. Therefore, the wall blowers 21 are arranged in a so-called staggered arrangement in the plan view.

In FIG. 2, the wall blower 21 of the first embodiment has a tubular nozzle 22. At the tip of the nozzle 22, an ejection port 23 for ejecting steam as an example of a soot removing medium is formed. The soot removing medium is not limited to the above, and any gas such as air or an inert gas can be used.
The wall blower 21 of the first embodiment blows the steam at an angle slightly toward the inclined surface 14 side rather than parallel to the inclined surface 14 so that the steam flows in the direction along the inclined surface 14. That is, in the first embodiment, the wall blower 21 ejects gas in a direction substantially parallel to the inclined surface 14. When gas is ejected in a direction substantially perpendicular to the inclined surface 14 as in the soot blowers of

Patent Documents

1 and 2, the inclined surface 14 may be worn by spraying steam over time, and the steam may be worn on the inclined surface 14. It will bounce and move across the flow of combustion gas, which may disturb the flow of combustion gas flowing from the furnace 2. On the other hand, as in the first embodiment, by ejecting steam substantially parallel to the inclined surface 14, the wear of the inclined surface 14 over time is reduced, and the steam flow is in the vicinity of the inclined surface 14. It will be unevenly distributed in the area, and it will not easily disturb the flow of combustion gas. Further, when steam is ejected substantially perpendicular to the inclined surface 14, the range where the steam reaches, that is, the range where the soot can be removed becomes narrow, or the steam is blown to the suspended heat transfer portion 4 and the heat transfer tube is worn. However, by ejecting steam substantially in parallel, it is possible to widen the range in which the steam reaches and the range in which soot can be removed, and it is possible to prevent unnecessary wear of the suspended heat transfer unit 4.

Further, the wall blower 21 of the first embodiment has a protruding position protruding inward of the boiler 1 as shown in FIG. 2A and an inclined surface as shown in FIG. 2B with respect to the inclined surface 14. The spout 23 is housed inside the 14 and is movable from the buried position in the buried state. The configuration for moving the wall blower 21 between the protruding position shown in FIG. 2 (A) and the buried position shown in FIG. 2 (B) is, for example, a mechanism for advancing and retreating a short-pull type soot blower. (See, for example, Patent Documents 3 and 4) can be diverted.

The wall blower 21 of the first embodiment moves from the buried position to the protruding position at a preset time in a trial run or the like, ejects steam from the ejection port 23 for a predetermined time, and blows off the soot accumulated on the inclined surface 14. And clean. Then, when the cleaning is completed, the position returns to the buried position. Therefore, the wall blower 21 protrudes inside the sub-side wall portion 12 only during the cleaning period, and the wall blower 21 is housed during the non-cleaning period, so that the flow of combustion gas is disturbed by the wall blower 21. This is reduced, and soot and ash are prevented from adhering and accumulating on the wall blower 21 and blocking the spout 23.

In FIG. 1B, it is possible, but not limited to, a configuration in which all the wall blowers 21 are operated when the sub-side wall portion 12 is cleaned. For example, one row of nozzles 22 (a) on the front side of the can, one row of nozzles 22 (c) on the rear side of the can, and one row of nozzles 22 (b) in between are alternately operated. It is also possible to operate the nozzles 22 on the left side toward the nozzles 22 on the right side one by one (two or three are possible) in order.
It is also possible to constantly operate the wall blower 21 (continue to eject steam), and in this case, the wall blower 21 is held at the protruding position while the boiler 1 is in operation.

Therefore, the operation of the wall blower 21 of the first embodiment cleans the soot and ash accumulated on the bottom wall 13 and the inclined surface 14 of the sub-side wall portion 12. In particular, the wall blower 21 of the first embodiment has a wider surface because it has a configuration of entering and exiting the inclined surface 14 unlike the conventional configuration of entering and retreating to the left and right side walls as in the conventional case. It is possible to clean. Therefore, even when low-grade coal is used, it is possible to suppress the accumulation of ash on the bottom wall 13 and the inclined surface 14 of the sub-side wall portion 12 as compared with the conventional configuration. Therefore, low-grade coal that could not be used in the past can be used in the boiler 1, and the risk of flow path blockage and fireplace shutdown is reduced.
In particular, in the first embodiment, the wall blower 21 is installed on the bottom wall 13 and the inclined surface 14, and the wall blower 21 is installed on the existing boiler only by replacing the bottom wall 13 and the inclined surface 14 of the existing boiler. And steam piping can be installed. Therefore, compared to updating the entire boiler 1, the wall blower 21 can be installed at low cost and easily, and low-grade coal can be used.

Further, in the first embodiment, the wall blowers 21 are staggered. Therefore, it is possible to efficiently clean a large area with a small number of sheets as compared with the case where they are simply arranged in a row.
Here, when the wall blower 21 is arranged on the rear side of the can, that is, on the upper side of the inclined surface 14, when the blown soot or the like slides down along the inclined surface 14, the steam of the wall blower 21 is difficult to reach. The soot adhering to the lower end side (front side of the can) of the surface 14 is also easily slipped off in the form of being caught in the blown soot or the like, and soot is less likely to accumulate on the inclined surface 14.

Further, in the first embodiment, since the wall blower 21 moves in and out of the inclined surface 14, the length of the nozzle 22 can be shortened as compared with the conventional configuration shown in FIG. .. Therefore, the cost of parts and the amount of steam can be reduced as compared with the conventional case. Further, in the configuration using a long nozzle as described in

Patent Documents

1 and 2, there is a problem that the nozzle protrudes greatly to the left and right of the can when the nozzle is stored, which requires a large space. However, in the first embodiment, there is a problem. , Such problems are avoided. Further, the long nozzle requires a long linear space for the long nozzle to pass through, and it is difficult to install an arbitrary number of the long nozzles in an arbitrary place due to the positional relationship with the suspended heat transfer unit 4. However, this can be solved by the wall blower 21 of the first embodiment. Further, the long nozzle has a high risk of bending, but the short wall blower 21 reduces this risk.

When steam is used as the soot removing medium, water (drain water) in which the steam in the nozzle 22 is liquefied remains after the steam injection is completed. Therefore, at the next steam ejection, the drain water will be discharged before the steam ejection. As in the prior art, the longer the nozzle length, the more drain water there is, and there is a problem that consideration must be given to the drain water treatment that may flow down the inclined surface 14 and flow into the fireplace 2. On the other hand, in the wall blower 21 of the first embodiment, since the nozzle 22 is short, less drain water is required, and troubles due to drain water can be reduced.

(Change example)
Although the examples of the present invention have been described in detail above, the present invention is not limited to the above examples, and various modifications can be made within the scope of the gist of the present invention described in the claims. It is possible. Examples of modifications (H01) to (H03) of the present invention are illustrated below.
(H01) In the above-described embodiment, the number and arrangement of the wall blowers 21 are not limited to the staggered arrangement illustrated in the examples. The boiler 1 may be arranged in a straight line along the left-right direction, may be arranged in two or less rows, may be arranged in four or more rows, or may be arranged in a grid pattern.

(H02) In the above embodiment, the inclined surface 14 is preferably formed to have an inclined shape, but it may be a flat surface along a horizontal surface, or a convex or concave curved surface.
(H03) In the above embodiment, the wall blower 21 is preferably installed on the upper side of the inclined surface 14, but can also be installed on the central portion or the lower side.

1 ... Boiler,
2 ... Fireplace,
11 ... the back of the can,
12 ... Sub-side wall,
13 ... The bottom surface of the secondary side wall
21 ... Soot removal device,
22 ... Nozzle.

Claims

With a fireplace
An auxiliary side wall provided on the downstream side in the gas flow direction above the fireplace, and
The rear part of the can arranged behind the sub-side wall portion and
A soot removing device having a nozzle configured to allow gas flow in and out from the bottom on the upstream side of the rear of the can, and ejecting a soot removing medium from the nozzle to remove soot from the bottom. ,
Boiler characterized by being equipped with.
The nozzle, which ejects a soot-removing medium along the bottom,
The boiler according to claim 1, wherein the boiler is provided with.
The soot removing device having a plurality of nozzles arranged at intervals along the left-right direction intersecting the gas flow direction.
The boiler according to claim 1 or 2, wherein the boiler is provided with.
The nozzles adjacent to each other in the left-right direction are arranged at positions shifted from each other in the front-rear direction.
The boiler according to claim 3, wherein the boiler is characterized by the above.