JP2001280632A - Device for recovering heat from exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for recovering heat with a structure from which an adhering matter is easily removed. SOLUTION: The air pipe type device for recovering heat from exhaust gas in which a heating medium passes through heat transfer pipes and the exhaust gas passes outside the heat transfer pipes supports only the upper parts of a plurality of heat transfer pipes so as to be suspended and has a vibrating means for applying a vibration to the lower parts of the heat transfer pipes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for recovering heat from exhaust gas.

[0002]

2. Description of the Related Art Waste such as general waste, industrial waste, and metal-containing waste is treated by a waste incinerator that treats waste by combustion. As the waste incinerator, an apparatus having a configuration as shown in FIG. 6 is used.

A waste incinerator 30 includes a rotary kiln 31 for incinerating waste and a secondary combustion chamber 3 for burning exhaust gas.
2, waste heat boiler 33 for obtaining steam using exhaust gas heat, air preheater 34 for obtaining preheated air, exhaust gas treatment facility 35 for removing harmful substances contained in exhaust gas, and attraction for inducing exhaust gas from which harmful substances have been removed. It has a blower 36 and a chimney 37 for discharging harmless exhaust gas to the atmosphere.

Then, the waste is incinerated in the rotary kiln 31 of the waste incinerator 30, the exhaust gas is treated in the secondary combustion chamber 32, and the steam is removed from the waste heat boiler 33 using the exhaust gas heat of the exhaust gas. The preheater 34 obtains preheated air. Further, harmful substances contained in the exhaust gas are removed by an exhaust gas treatment facility 35, and harmless exhaust gas is attracted by an induction blower 36 and is discharged from a chimney 37.

An exhaust gas containing a large amount of dust and dust is emitted from a waste incinerator, and the exhaust gas is high in temperature and contains a large amount of heat. In order to save energy and reduce operating costs, heat recovery from exhaust gas is being studied in various ways. Table 1 shows the configuration of a typical conventional heat recovery apparatus and the adhesion of dust and dust contained in exhaust gas.

[Table 1]

The prior art 1 is a vertical smoke tube system, in which a large number of heat transfer tubes are arranged vertically, supporting near both ends, the exhaust gas passes through the heat transfer tubes, and the outside of the heat transfer tubes such as air and water. It is a structure through which a heat medium passes. Prior art 2 is a horizontal trachea method, in which a large number of heat transfer tubes are arranged horizontally and supported near both ends.
In this structure, a heat medium such as air or water passes through the transmission pipe, and exhaust gas passes outside the transmission pipe. Prior art 3 is a plate-type heat exchanger.

[0007]

However, conventionally, the waste heat boiler, the air preheater, and the exhaust gas treatment equipment are each configured as separate devices, and the size of the equipment as a whole is increased, and the equipment location is increased. there were.

Further, the heat recovery apparatus of the prior art 3 has a problem that when the corrosion occurs in a part, the entire surface of the plate must be replaced, and the repair cost is high. On the other hand, in the prior arts 1 and 2 of the multi-pipe system, only the pipe containing the corroded portion needs to be replaced.
Repair costs are also relatively low.

[0009] However, the prior art 1 has a problem that although the deposits adhere to only the inside of the tube and are easily removed, the deposits easily adhere and the tube is easily clogged.

In the prior art 2, since exhaust gas passes through a relatively large space outside the pipe, it is difficult for deposits to adhere, but there is a problem that it is difficult to remove the deposits outside the pipe or between the pipes. .

[0011]

The above-mentioned problem is caused by the heat circuit device for exhaust gas according to claim 1, that is, the heat medium passes through the heat transfer tube and the exhaust gas passes outside the heat transfer tube. This problem is solved by a trachea-type heat recovery device, which supports only the upper portions of a plurality of heat transfer tubes, is disposed in a hanging manner, and has a vibrating means for applying vibration to a lower portion of the heat transfer tubes. You.

Further, the above-mentioned problem is caused by the heat circuit device from exhaust gas according to claim 3, that is, the heat recovery device from exhaust gas according to claim 1 or 2, wherein the heat medium is steam. It is effectively solved by a heat recovery apparatus for exhaust gas, wherein the heat recovery apparatus for exhaust gas according to claim 1 or 2 is arranged at predetermined intervals in a flow direction of the exhaust gas.

In a preferred embodiment of the present invention, as set forth in claim 2, the vibrating means strikes a striking shaft which penetrates a wall surface of the heat recovery device and whose tip reaches the lower part of the heat transfer tube, and a striking shaft. Consisting of a hammer and

[0014]

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

FIG. 1 is a schematic front view of a heat recovery apparatus according to an embodiment of the present invention. FIG. 2 is a front perspective view of the waste heat boiler or the air preheater of the embodiment. 3 and 4 are schematic side sectional views of the heat recovery device according to the embodiment of the present invention.

The heat recovery device 12 of the present embodiment is connected downstream of a secondary combustion chamber 11 connected to a rotary kiln, and is provided between the secondary combustion chamber 11 and the heat recovery device 12.
A partition plate 13 is provided. The secondary combustion chamber 11 has a vertical cylindrical shape, and its upper end extends horizontally to form a partition plate 13.
Through the heat recovery device 12.

The heat recovery unit 12 includes a waste heat boiler (boiler convection section) A for recovering heat from exhaust gas and an air preheater B.
And another waste heat boiler (boiler convection section) C are arranged at predetermined intervals in the direction in which the exhaust gas flows.
The waste heat boiler (boiler convection section) A and the other waste heat boiler (boiler convection section) C are arranged such that a heat transfer tube 14a hangs vertically in the heat recovery device 12 as shown in FIG. A large number of heat tubes 14a are arranged,
Only the upper part of a is supported (cantilever supported) by the support 15a,
The bottom is free. In the overall configuration, as shown in FIG. 2, a number of heat transfer tubes 14a are arranged in parallel with each other.

The heat transfer tube 14a is a so-called tracheal boiler heat exchanger through which water as a heat medium passes and exhaust gas flows outside the tube.

A striking shaft 18a, which penetrates the wall 16 of the heat recovery unit 12 and has a tip reaching the free lower part of the heat transfer tube 14a, is disposed below the heat transfer tube 14a. The striking shaft 18a is urged by a spring 17a so that the striking shaft 18a moves away from the heat transfer tube 14a. When the hammer 21 strikes the rear end of the striking shaft 18a, the spring 7a
, The tip of the impact shaft 18a abuts the heat transfer tube 14a, and vibration is given to the entire heat transfer tube 14a.

As shown in FIG. 4, the air preheater B is similarly arranged such that heat transfer tubes 14b hang vertically in the heat recovery device 12, and a large number of the heat transfer tubes 14b are provided. Only the upper part is supported (cantilevered) by the support 15b, and the lower part is free. Air preheater B
2 is also as shown in FIG.
4a are arranged in parallel close to each other.

The heat transfer tube 14b is a so-called tracheal preheater heat exchanger through which air as a heat medium passes and exhaust gas flows outside the tube.

A striking shaft 18b penetrating the wall 16 of the heat recovery device 12 and having a tip reaching the free lower portion of the heat transfer tube 14b is disposed at a free lower portion of the heat transfer tube 14b. The striking shaft 18b is urged by a spring 17b so that the striking shaft 18b moves away from the heat transfer tube 14b. When the hammer 21 strikes the rear end of the striking shaft 18b, the spring 7
b, the tip of the impact shaft 18b abuts on the heat transfer tube 14b, and vibration is given to the entire heat transfer tube 14b.

Immediately below each of the heat exchangers (waste heat boiler A, air preheater B, other waste heat boiler C) and the partition plate 13, hoppers 20a and 20 for discharging dust to the outside of the heat recovery device 12 are provided.
b, 20c and 20d are provided, and the dust is discharged downward through these hoppers.

A monitoring window 22 is provided at an appropriate position on the wall surface 16 of the heat recovery device 12 to monitor the amount of dust adhering to the heat transfer tubes 14a and 14b. When adhering to the above, the removing device 19
By operating a and 19b, it is possible to remove the adhering dust adhering to the outside of the heat transfer tubes 14a and 14b and the adhering dust adhering between the heat transfer tubes.

Exhaust gas generated at the time of waste incineration is supplied from the rotary kiln to the secondary combustion chamber 11, passes through the secondary combustion chamber 11, bypasses the partition plate 13, and is sent to the heat recovery unit 12 side. Heat is recovered by the boiler A, the air preheater B, and the other waste heat boiler C, and flows to the exhaust gas treatment equipment side.

The temperature of the exhaust gas in the secondary combustion chamber 11 is about 10
00 ° C., which is reduced to 650 ° C. or less behind the waste heat boiler by the heat recovery of the waste heat boiler A, is reduced to 580 ° C. or less behind the air preheater by the heat recovery of the air preheater B, and Due to the heat recovery, the temperature becomes about 250 ° C. behind the waste heat boiler.

At this time, dust (fly ash) floating in the exhaust gas is deposited on the outer surface of the partition plate 13 and the outer surfaces of the heat transfer tubes 14a and 14b of each waste heat boiler A, the air preheater B, and the other waste heat boiler C. They adhere, and the amount of dust attached increases with time.

Next, the operation of the heat recovery apparatus of the present embodiment will be described. The heat recovery device 12 of the present embodiment includes waste heat boilers A and C, and heat transfer tubes 14a and 14b of an air preheater B.
Removing means 19 for removing adhering dust at the free lower part of
a and 19b are provided. That is, the heat recovery device 1
The heat transfer tube 14 is connected to the wall surface 16 of the second through springs 17a and 17b.
Removal means 19a, 19b comprising striking shafts 18a, 18b extending to reach a, 14b are provided.

For this purpose, for example, when the adhering amount of dust reaches a predetermined amount, the rear ends of the striking shafts 18a, 18b protruding outside the heat recovery device 12 are hit with a hammer 21 or the like, so that the heat transfer tubes 14a, Vibration or impact is applied to the heat transfer tube 14b, so that the deposits attached to the outer surfaces of the heat transfer tubes 14a, 14b and the deposits between the adjacent transfer tubes fall, and the heat recovery device passes through the hoppers 20a, 20b, 20c. It is discharged out of 12.

Therefore, it is possible to easily remove the attached dust while the operation is continued, that is, without stopping the operation. And the work of removing the attached dust becomes easy,
The work efficiency is improved, the flow of exhaust gas is improved, the heat exchange efficiency is improved, and stable heat recovery is performed.

Even in the case of dust containing salt, the dust attached to the impact shafts 18a and 18b is removed by applying an impact to the impact shafts 18a and 18b, thereby preventing the heat transfer tubes 14a and 14b from being corroded.

In the heat recovery apparatus 12 of this embodiment, the waste heat boilers A and C and the air preheater C are arranged close to each other to form one apparatus. For this reason, the structure of the entire apparatus is simplified, and downsizing (reduction in size) can be realized.

As described above, the heat recovery apparatus according to the embodiment of the present invention has been described as an example in which two waste heat boilers and one air preheater are incorporated, but the present invention is not limited to such a configuration. . For example, only a waste heat boiler and a plurality of air preheaters may be arranged.

The means for removing the adhering dust is not limited to the hitting shaft type having a spring, but may be a type employing a cam mechanism and a motor or a vibrator type operating by electric power. Any type that can apply a mechanical impact or the like to the lower portion may be used.

FIG. 5 is a schematic view of the attached dust removing means of another embodiment. The attached dust removing means 20 of the present embodiment includes:
It is surrounded by the soundproof cover 20f, and is internally driven by the drive shaft 20b and the drive shaft 20b to form the rotating orbit 2
0c, a hammer 20d for transmitting the impact generated by the collision of the impact rod 20a and the rear end to the front end, and a spring 20e for urging the impact rod 20a.
And is composed of The hammering device 20d penetrates through the wall surface 16 and its tip is located near an impact transmitting component 21 attached to a free lower portion of the heat transfer tube 14a.

When the impact rod 20a is driven by the drive shaft 20b and collides with the rear end of the hammer 20d, the hammer 2
The impact is transmitted through Od, moves against the spring 20e, and the tip collides with the impact transmission component 21. Then, the entirety of the heat transfer tube 14a vibrates, and the deposits attached to the outer surface of the heat transfer tube 14a fall and are removed.

[0037]

According to the present invention, since only the upper portion of the heat transfer tube is supported and the lower portion is free, and the free lower portion of the heat transfer tube is provided with a removing device for removing the adhering dust, the removing device operates. By doing so, shocks such as vibrations are applied to the heat transfer tubes and the attached dust between the outer surface of the heat transfer tubes and the adjacent heat transfer tubes can be dropped, and the attached dust can be easily removed without stopping the operation. It is. Therefore, the work of removing the adhered dust is facilitated, the work efficiency can be improved, the flow of the exhaust gas can be improved, the heat exchange efficiency can be improved, and stable heat recovery can be performed. In addition, corrosion of the heat transfer tube due to dust containing salt is also prevented.

Since the impact shaft is provided on the wall surface of the heat recovery unit, vibration and impact are applied to the heat transfer tube by hitting the impact shaft with a hammer or the like. And easily removed.

Further, according to the present invention, since a plurality of boilers and air preheaters are arranged close to the inside of the heat recovery device, the overall structure of the heat recovery device is simplified and the size is reduced. Can be

[Brief description of the drawings]

FIG. 1 is a schematic front view of a heat recovery device according to an embodiment of the present invention.

FIG. 2 is a front perspective view of the waste heat boiler or the air preheater of the embodiment.

FIG. 3 is a side sectional view of the heat recovery device according to the embodiment of the present invention.

FIG. 4 is a side sectional view of the heat recovery device according to the embodiment of the present invention.

FIG. 5 is a schematic view of an attached dust removing unit according to another embodiment of the present invention.

FIG. 6 is a configuration diagram of a conventional waste incineration apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Secondary combustion chamber 12 Heat recovery device 14a, 14b Heat transfer tube 16 Wall surface 17a, 17b Spring 18a, 18b Impact shaft 19a, 19b Removal means A, C Waste heat boiler (boiler convection section) B Air preheater

Claims (3)

[Claims] 1. A tracheal heat recovery device in which a heat medium passes through a heat transfer tube and exhaust gas passes outside the heat transfer tube,
An apparatus for recovering heat from exhaust gas, comprising a vibrating means for supporting and suspending only the upper part of a plurality of heat transfer tubes and providing vibration to the lower part of the heat transfer tubes. 2. The exhaust gas according to claim 1, wherein the vibrating means comprises: a striking shaft that penetrates a wall surface of the heat recovery device and has a tip reaching a lower portion of the heat transfer tube; and a hammer striking the striking shaft. Heat recovery equipment. 3. The heat recovery device from exhaust gas according to claim 1 or 2, wherein the heat medium is steam, and the heat recovery device from exhaust gas according to claim 1 or 2, wherein the heat medium is air. A heat recovery device from exhaust gas arranged at predetermined intervals in the direction of exhaust gas flow.