JPH08110007A - Apparatus for preventing abrasion of loop pipes in heat recovery section - Google Patents

Abstract

PURPOSE: To permit an amount of combustion gas, which is sufficient to prevent excessive abrasion of bent ends of loop pipes and to perform adequate heat exchange, to flow through gaps between the bent ends and a heat exchanger tube wall in a heat recovery section and to prevent deposition of coal ash on an erosion baffle. CONSTITUTION: An erosion baffle 19 is mounted via support members 17 to a heat exchanger tube wall 7, which define a reheater side flow passage 5a and a superheater side flow passage 5b, in a position above bent ends 9 of loop pipes 10 of a reheater 11 and a superheater 12 to have a required width substantially in a horizontal direction to extend into the flow passage 5a, 5b. Coal ash passing holes 20 having a diameter of about 5 to 20mm are formed uniformly over the entire surface of the erosion baffle 19 to have a hole area rate of about 40 to 70%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loop tube wear prevention device for a rear heat transfer section.

[0002]

2. Description of the Related Art FIG. 9 shows an example of a commonly used coal-fired boiler. The coal-fired boiler has a structure in which the entire upper circumference of a boiler body 1 is surrounded by a ceiling enclosure 2.

The boiler body 1 includes a furnace 3, an auxiliary side wall 4 provided at a rear side of an upper end portion of the furnace 3, a downward side provided at a rear side of the auxiliary side wall 4, and an interior wall 6 by an intermediate wall 6. The rear heat transfer section 5 is divided into a front reheater-side flow path 5a and a rear superheater-side flow path 5b. The furnace 3, the side wall 4, the rear heat transfer section 5, and the middle portion. The wall 6 is, as shown in FIG.
It is formed by a panel-shaped heat transfer tube wall 7 in which the heat transfer tubes 7a are connected to each other by fins 7b.

In addition, above the furnace 3 of the boiler body 1 and inside the sub-side wall 4, a suspension type superheater 8 comprising a plurality of heat transfer tubes 8a
In the reheater side flow path 5a of the rear heat transfer section 5, a bent end portion that extends horizontally and is bent 180 ° near the heat transfer tube wall as shown in FIG. 9 is formed, and a reheater 11 including a zigzag loop tube 10 extending in the horizontal direction and having a bent end portion 9 is formed again is provided. Further, the superheater-side flow path 5b has a similar structure. A horizontal superheater 12 is provided.

In the above-mentioned boiler, the combustion gas A generated in the furnace 3 by combustion flows into the rear heat transfer section 5 through the sub side wall 4, and then the reheater 11 and the superheater 12
Between the loop pipes 10 (the space indicated by 13 in FIGS. 5 and 6) and between the reheater 11 and the superheater 12 and the heat transfer pipe wall 7 forming the rear heat transfer part 5 ( 6 and 7
Inside, the part indicated by 14) while passing through the reheater side flow path 5
Flowing downward in a and the superheater-side flow path 5b, and discharged from an exhaust gas duct (not shown).

At this time, the water flowing through the heat transfer tube wall 7 of the boiler body 1 and the heat transfer tubes 7a, 8a of the superheater 8 and the loop tubes 10 of the reheater 11 and the superheater 12 due to the heat of the combustion gas A. And heating steam.

However, when the combustion gas A flows downward in the reheater-side flow passage 5a and the superheater-side flow passage 5b, the combustion gas A flows in the loop pipe of the portion B shown in FIGS. There was a problem that the loop tube 10 was severely worn by the coal ash contained in the combustion gas A when hitting the upper surface of the horizontal portion of 10.

In order to solve the above-mentioned problem, a protector 15 is attached to cover the upper surface of the horizontal portion of the loop tube 10 to prevent abrasion, but the bent end portion of the loop tube 10 is prevented. In No. 9, the protector is not attached because the structure is complicated and it is difficult to manufacture and attach the protector. Therefore, the bent end 9 is severely worn, and the repaired portion is replaced with a new one. There was a problem that was often needed.

Therefore, conventionally, as shown in FIGS. 3 and 4, the bent end portion 9 of the loop pipe 10 of the reheater 11 and the superheater 12 in the heat transfer pipe wall 7 forming the rear heat transfer portion 5. An erosion baffle 16 which has a required width and extends inwardly in the substantially horizontal direction is attached via a support member 17 to a position immediately above the end of the loop pipe 10 to prevent the bent end 9 of the loop pipe 10 from being worn. Was there.

[0010]

However, when the conventional erosion baffle 16 is attached, the gap 14 (shown in FIGS. 4, 6 and 7) where the combustion gas A easily flows is closed, Bent end 9 of loop tube 10
There is a problem that the contact of the combustion gas A with the exhaust gas is extremely reduced, and the heat exchange efficiency of the reheater 11 and the superheater 12 is reduced accordingly, and the erosion baffle 16 causes a flow path in the rear heat transfer section 5. There is a problem in that the pressure loss increases due to the narrowing of the air conditioner, and the power of a fan (not shown) for flowing the combustion gas A increases. Further, the coal ash contained in the combustion gas A is deposited on the erosion baffle 16, and the heat transfer surface of the heat transfer tube wall 7 is reduced by this amount, the heat exchange efficiency is reduced, and the boiler is also reduced. Since it is necessary to remove the accumulated coal ash at the time of inspection, the inspection work is prolonged, and further, since the boiler operation is stopped during the inspection, there is a problem that the operation efficiency of the boiler also decreases. It was

In view of the above situation, the present invention does not extremely wear the bent end portion in the gap between the bent end portion of the loop tube and the heat transfer tube wall of the rear heat transfer section, and is sufficient. The purpose is to flow an amount of combustion gas capable of heat exchange and to prevent the deposition of coal ash on the erosion baffle.

[0012]

SUMMARY OF THE INVENTION The present invention comprises a rear heat transfer section which is connected to the rear side of a furnace via a side wall and in which a reheater and a superheater consisting of a plurality of loop tubes are arranged. A loop tube wear prevention device for a rear heat transfer section of a coal-fired boiler, wherein the loop tube of the reheater and the superheater in the heat transfer tube wall that constitutes the rear heat transfer section is located above the bent end of the loop tube. ,
An erosion baffle having a required width in a substantially horizontal direction and projecting into a flow path is attached, and a coal ash circulation hole is formed on the entire surface of the erosion baffle.

Further, in the present invention, the diameter of the coal ash flow hole formed in the erosion baffle is about 5 mm to 20 mm.
And the open area ratio of about 40% to 70% is optimal.

[0014]

In the present invention, a part of the combustion gas flowing downward in the rear heat transfer section hits the erosion baffle and its flow velocity is weakened, and passes through the coal ash flow hole of the erosion baffle to form the rear heat transfer section. It flows through the gap between the heat transfer tube wall and the bent end of the loop tube.

Therefore, a gentle and sufficient flow rate of the combustion gas flows in the above-mentioned gap, so that the bent end portion is prevented from being worn by the coal ash contained in the combustion gas, and the overall combustion gas is prevented. The flow of the combustion gas is improved, the pressure loss is reduced, and the heat exchange efficiency is improved by the contact of the combustion gas with the bent end portion of the loop tube.

Further, since the coal ash falls from the coal ash flow hole, the coal ash does not deposit on the erosion baffle.

Further, in the present invention, the diameter of the coal ash circulation holes is about 5 mm to 20 mm, and the open area ratio is about 40% to 70%.
%, The flow velocity and flow rate of the combustion gas flowing in the gap between the heat transfer tube wall forming the rear heat transfer section and the bent end of the loop tube are optimized, and the bent end is worn by the coal ash. Is more reliably prevented, heat exchange is performed more efficiently, and the deposition of coal ash on the erosion baffle is more reliably prevented.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 and FIG. 2 show an embodiment of a loop pipe wear prevention device for the rear heat transfer portion of the present invention, and FIGS.
The same parts as those shown in FIG. 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIGS. 1 and 2, the reheater 11 and the superheater 12 in the heat transfer tube wall 7 constituting the rear heat transfer section 5 are shown.
At a position above the bent end portion 9 of the loop tube 10 (position apart from the upper surface of the loop tube 10 by about 20 cm), the reheater side flow path 5a having a required width (about 30 cm) in the substantially horizontal direction. And the erosion baffle 1 that overhangs the superheater-side flow path 5b
9 is attached via a support member 17, and coal ash circulation holes 20 are uniformly formed over the entire surface of the erosion baffle 19. Also, in the case shown, the erosion baffle 1
No. 9 is divided into required length dimensions so that stress due to thermal deformation is not generated.

Further, the coal ash flow holes 20 formed in the erosion baffle 19 have a diameter of about 5 mm to 20 mm and an opening ratio of about 40% to 70%.

Although only a part of the erosion baffle 19 is shown in this embodiment, the loop tube 10
The erosion baffle 19 is also attached to the other portions of the upper side of the bent end 9 as in the present embodiment.

In the present embodiment, a part of the combustion gas A flowing downward in the rear heat transfer section 5 hits the erosion baffle 19 and its flow velocity is weakened, and passes through the coal ash flow hole 20 of the erosion baffle 19. It flows through the gap 14 between the heat transfer tube wall 7 forming the rear heat transfer section 5 and the bent end 9 of the loop tube 10.

Therefore, the gradual and sufficient flow rate of the combustion gas A passes through the gap 14, and the combustion gas A also comes into contact with the bent end portion 9 of the loop tube 10.

Further, since the coal ash contained in the combustion gas A comes to fall from the coal ash distribution hole 20, the coal ash does not deposit on the erosion baffle 19.

Further, in the present invention, the coal ash distribution hole 2
The diameter of 0 is about 5 mm to 20 mm, and the open area ratio is about 40%
When it is 70%, the flow velocity and flow rate of the combustion gas A flowing in the gap 14 between the heat transfer tube wall 7 forming the rear heat transfer section 5 and the bent end portion 9 of the loop tube 10 are optimized, and the coal ash distribution The coal ash can be more reliably dropped from the hole 20. Moreover, as a result of the experiment, the diameter of the coal ash circulation hole 20 is 1
The best result was obtained when the opening ratio was 6 mm and the opening ratio was 50%.

Therefore, abrasion of the bent end portion 9 due to the coal ash contained in the combustion gas A is reliably prevented, heat exchange efficiency is improved, pressure loss is reduced, and the erosion baffle 19 on the boiler inspection is performed. Since it is no longer necessary to remove the coal ash, the inspection work is shortened and the boiler operation efficiency is improved.

The mounting position of the erosion baffle 19 described in the embodiments of the present invention and the width interval in the horizontal direction can be appropriately changed, and other various changes can be made without departing from the scope of the present invention. Of course.

[0029]

According to the present invention, by disposing the erosion baffle having the coal ash circulation holes, the gap between the heat transfer tube wall forming the rear heat transfer section and the bent end of the loop tube, Since a gentle and sufficient flow rate of combustion gas will pass, pressure loss will be reduced, abrasion of the bent end due to coal ash contained in the combustion gas will be prevented, and combustion will occur at the bent part of the loop pipe. Since the gas comes into contact, the heat exchange efficiency is improved, and the coal ash contained in the combustion gas comes to fall from the coal ash distribution hole, so that the coal ash may be deposited on the erosion baffle. Since there is no need to remove the coal ash during the boiler inspection, the inspection work is shortened and the boiler operating efficiency is improved. or,
In the present invention, the diameter of the coal ash circulation hole is about 5 mm to 20 mm.
mm and the open area ratio is about 40% to 70%, the flow velocity and flow rate of the combustion gas flowing in the gap between the heat transfer tube wall forming the rear heat transfer section and the bent end of the loop tube are optimal. Therefore, abrasion of the bent end due to coal ash can be more reliably prevented, heat exchange can be performed more efficiently, and the accumulation of coal ash on the erosion baffle can be more reliably prevented. It can exert an excellent effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a loop tube wear prevention device for a rear heat transfer section of the present invention.

2 is a II-II enlarged arrow view of FIG. 1. FIG.

FIG. 3 is a perspective view showing an example of a conventional arrangement state of erosion baffles.

FIG. 4 is an enlarged view of IV-IV in FIG.

FIG. 5 is a perspective view showing a part of a reheater and a superheater in a conventional rear heat transfer section.

6 is a VI-VI enlarged arrow view of FIG.

FIG. 7 is a side view showing a reheater and a superheater in a conventional rear heat transfer section.

FIG. 8 is a plan view showing an example of a heat transfer tube wall in a coal-fired boiler.

FIG. 9 is an overall view showing an example of a commonly used coal-fired boiler.

[Explanation of symbols]

 3 Furnace 4 Sub-sidewall 5 Rear heat transfer part 5a Reheater side flow path (flow path) 5b Superheater side flow path (flow path) 7 Heat transfer tube wall 9 Bent end 10 Loop tube 11 Reheater 12 Overheat Vessel 19 erosion baffle 20 coal ash distribution hole

Claims (2)

[Claims] 1. A rear heat transfer unit for a coal-fired boiler having a rear heat transfer unit which is connected to a rear side of a furnace via a side wall and in which a reheater and a superheater composed of a plurality of loop tubes are arranged. Loop tube wear prevention device of the part, in the upper position of the bent end of the loop tube of the reheater and the superheater in the heat transfer tube wall constituting the rear heat transfer section, the required width in a substantially horizontal direction. Attach an erosion baffle that has and overhangs in the flow path,
A loop tube wear prevention device for a rear heat transfer section, characterized in that a coal ash circulation hole is formed on the entire surface of the erosion baffle. 2. The diameter of the coal ash flow holes formed in the erosion baffle is about 5 mm to 20 mm and the opening ratio is about 4.
The loop tube wear prevention device for the rear heat transfer portion according to claim 1, wherein the wear resistance is set to 0% to 70%.