JP2002228105A - Combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustor in which wear and corrosion of straight tubes 25 laid in a fluidized bed 7 can be reduced. SOLUTION: The combustor 1 comprises a combustion furnace 3 being fed with a fluid medium 5A forming the fluidized bed 7 to the bottom section thereof, an opening 12 made in the bottom section of the combustion furnace 3 and injecting air into the fluidized bed 7, and straight tubes 25 laid in the fluidized bed 7. Since the main part of the straight tube 25 is laid along the injecting direction of air 29, the fluid medium 5 being blown away by the air 29 injected into the layer of the fluid medium 5 can be prevented from colliding from the front face of the tube wall of the straight tube 25 and the fluid medium 5 collides against the entirety of the straight tube 25. Consequently, wear of the straight tube 25 due to collision of the fluid medium 5 can be reduced and, at the same time, corrosion of straight tube 25 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus having a fluid medium at the bottom thereof, and more particularly to a combustion apparatus having a heat transfer tube in a layer of the fluid medium.

[0002]

2. Description of the Related Art In order to make effective use of heat generated from a combustion furnace, many plants are provided with heat recovery means such as heat transfer tubes and power generation equipment utilizing the recovered heat. However, when burning fuel or waste containing chlorine in the combustion furnace, chlorides such as NaCl and KCl and hydrogen chloride were generated.These chlorides were installed at the later stage of the combustion furnace. There was a problem that the superheater tubes for heat recovery were corroded. On the other hand, in the invention described in Japanese Patent Application Laid-Open No. 11-193901, a heat transfer tube for heat recovery is provided in a bed of a fluidized medium provided in a combustion furnace having a fluidized medium, for example, a fluidized bed incinerator. It was configured to be arranged. With such a configuration, the layer of the fluidized medium that is brought into a fluidized state by blowing air, that is, the fluidized medium in the fluidized bed collides with the heat transfer tube. Thereby, the adhered ash, which is the molten ash of the chloride adhered to the heat transfer tube, is scraped off by the fluid medium, and corrosion of the heat transfer tube due to chloride is reduced.

[0003]

By the way, the moving speed and the moving direction of the fluid medium in the fluidized bed differ depending on each position of the fluidized bed. Therefore, the speed at which the fluid medium collides with the heat transfer tube and the angle at which the fluid medium collides with the heat transfer tube also differ depending on the portion of the heat transfer tube. However, since the speed of the fluid medium blown off by the air ejected from the ejection port is faster than the speed of the fluid medium flowing by convection in the fluidized bed, the fluid medium was blown from the ejection port. Susceptible to air. That is, the flowing medium to which the air is blown moves in the direction in which the air flows.

However, in the conventional combustion apparatus, FIG.
As shown in FIG. 6, since the axis of the straight pipe is arranged so as to be orthogonal to the flow direction of the air injected from the injection port, the flowing medium blown off by the air is, as shown in FIG. , Mainly colliding with part A of the straight pipe. Therefore, the wear amount of the portion A of the straight pipe is larger than the wear amount of the portion B. In particular, since the fluid medium having a higher speed collides with the portion A of the straight pipe arranged near the air injection port, the wear amount further increases. In addition, there is a case where the fluid medium enough to sufficiently scrape the attached ash does not collide with the portion B of the straight pipe. In this case, the straight pipe is corroded by the attached ash that cannot be removed.

It is an object of the present invention to reduce wear and corrosion of heat transfer tubes arranged in a fluidized bed.

[0006]

The amount of wear of the heat transfer tube varies depending on the speed and angle at which the fluid medium collides.
For example, if the speed of the fluid medium is the same, compared to the case where the fluid medium collides with the outer peripheral surface of the heat transfer tube from the front,
The amount of wear of the heat transfer tube can be reduced to a smaller extent when the collision occurs at an angle with respect to the front direction of the outer peripheral surface of the heat transfer tube. That is, if the angle at which the fluid medium collides with the surface of the heat transfer tube is the elevation angle, the wear amount of the heat transfer tube can be reduced by reducing the elevation angle. On the other hand, if the collision angles of the colliding fluid media are the same, the slower the colliding speed of the fluid media, the smaller the amount of wear of the heat transfer tubes.

Therefore, the combustion apparatus of the present invention is provided with a combustion furnace in which a fluidized medium is supplied and a fluidized bed is formed at the bottom by the fluidized medium, and is provided at the bottom of the combustion furnace and injects air into the fluidized bed. The above-described object is achieved by providing a configuration in which a main part of the heat transfer tube is provided along a direction in which air is blown out, comprising:

[0008] With this configuration, it is possible to prevent the flowing medium blown off by the injection of the air injected into the fluidized bed from colliding from the front of the tube wall of the main part of the heat transfer tube. Thereby, the wear of the heat transfer tube due to the collision of the flowing medium can be reduced. In addition, the flowing medium
It moves along the straight pipe and collides with the whole straight pipe. Therefore, the attached ash can be scraped off all around the straight pipe, and the corrosion of the straight pipe can be reduced.

Further, the combustion apparatus of the present invention has a combustion furnace in which a fluidized medium is supplied and a fluidized bed is formed at the bottom by the fluidized medium, and an injection device provided on the bottom surface of the combustion furnace for injecting air upward. The above object is achieved by providing a mouth and a heat transfer tube arranged in a fluidized bed, wherein a main part of the heat transfer tube is vertically arranged. With such a configuration, the air injected upward from the bottom of the combustion furnace blows up the fluidized medium to the upper portion of the bed, and the blown up fluidized medium moves below the fluidized bed according to gravity. That is, by moving more fluid medium in the vertical direction, it is possible to further suppress the collision of the main part of the heat transfer tube from the front of the tube wall. Thereby, the wear of the heat transfer tube due to the collision of the fluid medium can be further reduced.

[0010] The heat transfer tubes arranged in the bed of the fluid medium are generally provided in a meandering manner. That is, it is composed of a plurality of straight pipes and a bent pipe that connects the ends of the straight pipes alternately. Therefore, the heat transfer tube included in the combustion device of the present invention is composed of a plurality of straight pipes provided in parallel and bent pipes that respectively communicate the straight pipes, and it is assumed that a main part of the heat transfer pipe is a straight pipe. be able to. Further, the Vickers hardness of the surface of the heat transfer tube can be 500 HV or more. With such a configuration, it is possible to further reduce wear due to collision of the fluid medium.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a combustion apparatus according to the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view showing a schematic configuration and operation of a combustion apparatus to which the present invention is applied. FIG. 2 is a cross-sectional view showing a schematic configuration of a straight tube 25 which is a heat transfer tube included in the combustion apparatus 1 to which the present invention is applied, and a movement of the flowing medium 5 colliding with the straight tube 25.

The structure of the combustion device 1 is as shown in FIG.
The combustion furnace 3 includes, for example, a particulate fluid medium 5 such as silica sand, an air chamber 9, and a heat transfer tube 11. The air chamber 9 is provided at the bottom of the combustion furnace 3, and the fluid medium 5 is spread over the air chamber 9 in a layered manner. The heat transfer tube 11 is buried inside the layer of the fluid medium 5. Air chamber 9 and fluid medium 5
Is separated from the layer by a plate-shaped air distribution plate 13 in which a plurality of injection ports 12 are formed.

In the upper part of the combustion furnace 3, there are formed an inlet 15 for charging fuel or waste 14 containing chlorine into the combustion furnace 3, and an outlet 17 for discharging exhaust gas, fly ash 16 and the like. A hot air blower 2 that blows hot air 20 into the fluidized bed 7
1 is provided.

The heat transfer tube 11 is composed of a plurality of vertically arranged straight tubes 25 and alternately connects the upper and lower portions of the straight tubes 25, for example, U
A heat medium (not shown) flows through the straight pipe 25 and the bent pipe 27. The heat transfer tube 11 is connected to, for example, equipment or devices that use heat (not shown), such as a steam turbine. The heat medium circulates between the inside of the heat transfer tube 11 and devices or devices that use heat (not shown). A hardened layer 28 is formed on the surface of the straight pipe 25, as shown in FIG.
The hardened layer 28 has a Vickers hardness of 500 HV or more.

The operation of the combustion device 1 having such a configuration and the features of the present invention will be described. First, the hot air 20 is supplied from the hot air blower 21 to the layer of the fluid medium 5, and the fluid medium 5 is heated. At the same time, air 29 is supplied from an air supply means (not shown) to the air chamber 9, and the air 29 supplied to the air chamber 9 flows into the bed of the fluid medium 5 through the injection port 12. The fluid medium 5 near the injection port 12 in the bed is blown up by the injected air 29 along the straight pipe 25 to the upper part of the bed. The fluid medium 5 blown up at the top of this layer
By natural fall, it moves below the layer along the straight pipe 25. At this time, the fluid medium 5 also moves in the horizontal direction,
It is mainly moving in the vertical direction along the straight pipe 25.
As described above, the fluid medium 5 is agitated and circulated by the air 29, so that the layer of the fluid medium 5 is in a fluid state.

A fuel or waste 14 containing chlorine is introduced into the fluidized bed of the fluidized medium 5, that is, the fluidized bed 7, and burned. When burning the fuel or the waste 14, for example, chlorides such as NaCl and KCl are generated and adhere to the straight pipe 25 and the bent pipe 27. However, the attached ash is scraped off and removed by the flowing medium 5 moving along the straight pipe 25. When the combustion of the fuel or the waste 14 is started, the heat medium circulates between the heat transfer tube 11 and equipment or devices that use heat (not shown), and recovers the heat generated by the combustion. Exhaust gas and fly ash 16 generated from the burned fuel or waste 14 are discharged to an exhaust port 17.
And discharged into the atmosphere through an exhaust gas treatment device such as a cyclone or a bag filter (not shown) provided downstream of the combustion device. The ash that is not scattered by the combustion, that is, the bottom ash 31 is discharged out of the furnace by a discharge unit (not shown).

As described above, in the combustion device 1 of the present embodiment,
In the fluidized bed 7 provided at the bottom of the combustion furnace 3, a heat transfer tube 11 composed of a plurality of straight pipes 25 provided in parallel and bent pipes 27 which respectively communicate the straight pipes 25 is buried. By arranging the pipe 25 vertically, the fluid medium 5 in the fluidized bed 7
Can be moved along the straight pipe 25. This makes it possible to reduce the angle at which the flowing medium 5 collides with the wall of the straight tube 25, which is the main part of the heat transfer tube, that is, the angle of elevation at which the flow medium 5 collides, so that wear of the straight tube 25 can be suppressed. Further, as shown in FIG.
Similarly collides with the entire outer periphery of the straight pipe 25,
Can be prevented from being partially worn. Furthermore, since the attached ash on the entire straight pipe 25 can be scraped off, the corrosion of the straight pipe 25 can be reduced.

FIG. 3 shows the relationship between the deposited ash and the amount of corrosion. FIG. 3 is a graph showing the amount of corrosion of the heat transfer tubes when STBA24 (2.25Cr1Mo) is coated with ash 1 and ash 2 collected from an actual machine and when it is not applied. Ash 1 is 8
% Na ₂ O-9% Cl-12% K ₂ O-24% SO ₃ , Ash 2 is 5% Na ₂ O-5
% Has a composition of _{Cl-16% K 2 O-} 27% SO 3. The exam is
550 ℃, 1000ppmHCl-10% O ₂ -10% CO ₂ -50ppmSO ₂ -20%
The test was performed in an atmosphere of H ₂ O-bal and N ₂ for 50 hours. As is apparent from the figure, the amount of corrosion in the absence of ash is very small, and it is possible to effectively reduce the amount of corrosion of the straight pipe 25 by suppressing the adhesion of the attached ash to the straight pipe 25. it can.

In addition, the air 29 is ejected in a vertical direction, and the straight pipe 25 is formed vertically, so that the fluid medium 5 in the fluidized bed 7 is blown up and the fluid medium 5 falls according to gravity. A straight pipe 25 can be provided along the direction. Thereby, the angle at which the flowing medium 5 collides with the straight pipe 25 can be further suppressed, and the wear of the straight pipe 25 due to the collision of the flowing medium 5 can be further reduced.

Further, the Vickers hardness of the surfaces of the straight pipe 25 and the bent pipe 27 can be 500 HV or more. In addition,
FIG. 4 shows the relationship between the hardness and the wear amount. Such a configuration is preferable because wear of the fluid medium 5 due to collision can be further reduced by increasing the hardness of the surface of the heat transfer tube.

Further, the combustion device of the present invention is not limited to the combustion device 1 used in the present embodiment, and the main part of the heat transfer tube provided in the fluidized bed 7 in the combustion furnace 3 is a fluid medium of the fluidized bed 7. 5 can be used as long as they are formed along the moving direction of 5. Further, the straight pipe 25 and the bent pipe 27 used in the combustion device of the present invention are not limited to the materials and shapes used in the present embodiment, and various types of heat transfer tubes can be used. For example, cermet-based materials such as Cr carbide-NiCr, self-fluxing alloys represented by Ni-Cr-Si-B,
Co-based materials such as stellite, high Cr cast iron, and the like can be used.

[0022]

According to the present invention, it is possible to reduce wear and corrosion of the heat transfer tubes arranged in the layer of the fluidized medium.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration and operation of a combustion device to which the present invention is applied.

FIG. 2 is a cross-sectional view showing a schematic configuration of a straight pipe as a heat transfer pipe included in a combustion apparatus to which the present invention is applied, and a movement of a fluid medium which collides with the straight pipe.

FIG. 3 is a graph showing the amount of corrosion of a heat transfer tube in a case where ash 1 and ash 2 collected from an actual machine are applied to STBA24 (2.25Cr1Mo) and in a case where it is not applied.

FIG. 4 is a graph showing the relationship between the surface hardness of a heat transfer tube and the amount of wear.

FIG. 5 is a cross-sectional view showing a schematic configuration and operation of a conventional combustion device.

FIG. 6 is a cross-sectional view showing a schematic configuration of a straight tube which is a heat transfer tube included in a conventional combustion device and a movement of a flowing medium which collides with the straight tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion device 3 Combustion furnace 5 Fluid medium 7 Fluidized bed 11 Heat transfer tube 12 Injection port 25 Straight tube 27 Bent tube

Claims (4)

[Claims] 1. A combustion furnace to which a fluidized medium is supplied and a fluidized bed is formed at the bottom by the fluidized medium, and an injection unit provided at the bottom of the combustion furnace for injecting air into the fluidized bed;
A combustion device comprising: a heat transfer tube disposed in the fluidized bed, wherein a main portion of the heat transfer tube is disposed along a direction in which the air is ejected. 2. A combustion furnace to which a fluidized medium is supplied and a fluidized bed is formed at the bottom by the fluidized medium, an injection port provided at the bottom of the combustion furnace to inject air upward, and And a heat transfer tube disposed in the combustion device, wherein a main part of the heat transfer tube is vertically disposed. 3. The heat transfer tube according to claim 1, wherein the heat transfer tube comprises a plurality of straight pipes provided in parallel and bent pipes connecting the straight pipes, and the main part is the straight pipe. Item 3. The combustion device according to Item 1 or 2. 4. The Vickers hardness of the surface of the heat transfer tube is 50.
The combustion device according to any one of claims 1 to 3, wherein the combustion device is 0 HV or more.