JP4401995B2 - Heat transfer tube repair and removal method for high temperature air heater - Google Patents

Description

  The present invention recovers the thermal energy of high-temperature pyrolysis gas generated by heat treatment of waste in an incinerator for municipal waste and industrial waste by exchanging heat with air, thereby achieving high utilization of thermal energy. The present invention relates to a method for repairing a heat transfer tube of an air heater.

  In the incinerator for municipal waste and industrial waste, in order to recover the thermal energy of the high-temperature pyrolysis gas generated from the waste heat treatment furnace and use it effectively as a heating source for the above-mentioned heat treatment furnace In addition, a high-temperature air heater is provided on the downstream side.

  FIG. 7 shows a cross section of the fuel melting furnace in which the high-temperature air heater is installed.

  The combustion melting furnace 1 has a U-shape, the upstream side is a combustion melting part 2, and the high-temperature air heater 3 is disposed on the downstream side. A supply line 5 and a burner 6 for pyrolysis gas 4 generated from a heat treatment furnace (not shown) are installed at the top of the fuel melting section 2, and the combustion components in the pyrolysis gas 4 are about 1300 ° C. by the burner 6. The molten slag 7 and the high-temperature combustion gas 8 are generated.

  This combustion gas 8 is a corrosive gas containing chlorine and the like, has a temperature of 1000 ° C. to 1300 ° C., flows toward the high-temperature air heater 3 at a speed of 2 m to 3 m per second, and is disposed therein. Heat is exchanged with the heated air 15 via the heat transfer tube 9.

  The thermal energy recovered as high-temperature air by the high-temperature air heater 3 in this manner is returned to the upstream heat treatment furnace that generates the pyrolysis gas 4 and reused as a heat source.

  Further, the heat transfer tube 9 constituting the high-temperature air heater 3 has a double tube structure including a heat transfer outer tube 13 and a heat transfer inner tube 14 as shown in FIG. The tip portion 17 is processed into a hemispherical shape.

  The other end of the heat transfer tube 9 is fixed to the outside of the combustion melting furnace 1 in a cantilevered manner, and through a through hole 12 provided in the outer wall 11 of the combustion melting furnace 1, as shown in FIG. Ten pieces are arranged as a unit so as to protrude into the combustion melting furnace 1.

  In the heat transfer tube 9 arranged in this way, the heated air 15 flowing through the gap 13a between the heat transfer outer tube 13 and the heat transfer inner tube 14 is heated by heat exchange with the combustion gas 8, and the heated air 16 is recovered through the inside 14 a of the heat transfer inner tube 14. (See Patent Document 1)

  Therefore, since the heat transfer tube 9 is sprayed with corrosive high-temperature combustion gas 8 from the lateral direction, the heat transfer outer tube 13 of most of the heat transfer tubes 9 is made of a ceramic material having corrosion resistance at high temperatures. However, a metal heat transfer outer tube 13 is employed for some heat transfer tubes 9 that require strength.

  Here, when the heat transfer outer tube 13 is made of ceramics, the heat conductivity is inferior to that of metal, so that there is a drawback that the heat transfer outer tube 13 is vulnerable to thermal shock and easily damaged.

  Further, when the heat transfer outer tube 13 is made of metal, there is a drawback that it is easily corroded at a high temperature as described above.

  Therefore, when the degree of damage progresses and a hole or crack (hereinafter referred to as a defective portion) reaching the inside of the heat transfer outer tube 13 occurs, the heat recovery of the high-temperature air heater 3 is performed. The efficiency is lowered, and the high-temperature atmosphere in the furnace is damaged by the heated air 15 flowing out into the melting and heating furnace 1.

Therefore, it is necessary to repair, remove, or replace the heat transfer tube 9 in which the defective portion 20 is generated in the heat transfer outer tube 13.
JP 2003-21479 A

  However, as described above, since several tens of heat transfer tubes are installed in the air heater as a unit, even if only one heat transfer tube needs to be replaced, the entire high-temperature air heater is melted and heated. It had to be pulled out and dismantled, and the replacement work was large, requiring time and cost.

  In addition, during the above repair work, the operation of the melting and heating furnace must be stopped, which has been an obstacle to efficient waste disposal.

The present invention has been made in view of such problems, and provides a simple repair methods and removal how the heat transfer outside the tube caused the defect.

  In order to achieve the above object, a method of repairing a heat transfer tube in a high-temperature air heater according to the present invention includes a metal inner tube, and an outer tube disposed coaxially with a space around the outer periphery of the inner tube. In a high-temperature air heater that heats the air flowing in the inner tube by exchanging heat with the high-temperature gas through the outer tube, the heat transfer tube comprising a heat transfer tube made of A method of repairing a defect such as a hole or a crack generated in the outer tube, wherein a cylindrical steel plate is closely attached to an outer periphery of the outer tube so as to cover an outer surface of the defect, and further, A heat transfer tube repairing method comprising filling a gap between both ends of a fixed cylindrical steel plate and the outer tube with a heat insulating material.

  By such a repair method, it is possible to simply repair a defective portion generated in the heat transfer outer tube.

  Further, the method for removing the heat transfer tube in the high-temperature air heater according to the present invention is a method for removing the heat transfer tube in which the defective portion is generated in the outer tube, and the heat transfer tube is cut in a radial direction, and after the cutting, A cylindrical or disk-shaped jig is inserted and fixed from the cut surface of the heat transfer tube remaining in the high-temperature air heater, and a space defined by the fixed jig and the cut surface is filled with a heat insulating material. It is the removal method of the heat exchanger tube characterized by this.

  By such a removal method, the heat transfer tube in which a defective portion that affects the heat recovery efficiency of the high-temperature air heater or the like in the heat transfer outer tube can be easily removed.

As described above, according to the present invention, the heat transfer tube having a defective portion in the heat transfer outer tube can be easily repaired or removed, so that the time and cost required for the work can be reduced, and the efficiency of the waste can be reduced. It becomes possible to perform a typical process.

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

  First, when the defective portion 20 generated in the heat transfer outer tube 13 has a size that does not greatly affect the heat recovery efficiency of the air heater 3, the defective portion is repaired and the heat transfer tube Extending the service life is desirable from the viewpoint of cost rationalization.

  Therefore, a method for simply repairing the defective portion will be described with reference to FIG.

  FIG. 1 shows a cross section of a heat transfer tube when a defective portion generated in the heat transfer outer tube is simply repaired.

  The repair of the defective portion 20 generated in the heat transfer outer tube 13 is a width that sufficiently covers the defective portion 20 of the heat transfer outer tube 13 with the heat transfer tube 9 to be repaired still protruding into the combustion melting furnace 1. As shown in FIG. 1, the cylindrical steel plate 30 having the above is adhered by being brought into close contact with the outside.

  Therefore, since the repair work is performed from the inside of the combustion melting furnace 1 after stopping, it is not necessary to pull out the high-temperature air heater 3 to the outside.

  Since the tubular steel plate 30 is exposed to the corrosive combustion gas 8 at a high temperature after the repair, like the heat transfer outer tube 13, it is desirable that the cylindrical steel plate 30 be made of stainless steel or the like that is corrosion resistant even at a high temperature.

  Further, in order to maintain the atmosphere and sealing inside the heat transfer tube 9, a slight gap formed between the tubular steel plate 30 and the heat transfer outer tube 13 is filled with a heat insulating material 31 having sealing performance and heat resistance. .

  Examples of the heat insulating material 31 include alumina, silica, zirconia ceramic materials, and ceramic fibers.

  Since such a simple repair method can reduce the work required for repair, the period of stoppage of the combustion melting furnace 1 can be significantly shortened, and the life of the heat transfer tube 9 can be extended, so that the air heater 3 The operating cost can be rationalized.

  In order to further improve the sealing performance, the sealing plug 32 may be inserted into the defective portion 20 in advance.

  In this case, as shown in FIG. 2, after mechanically processing the periphery of the defective portion 20 having a discontinuous shape so as to match the shape of the sealing plug 32, the sealing plug 32 is inserted, It becomes the repair method of fixing the cylindrical steel plate 30 from the top.

  About the material of this sealing plug 32, it is desirable that it is the same material as the heat-transfer outer tube | pipe 13 from a viewpoint of preventing the failure | damage by a thermal expansion difference.

  Next, when the defective portion 20 of the heat transfer outer tube 13 has developed to a size that greatly affects the heat recovery efficiency of the high-temperature air heater 3, the heat transfer tube 9 is removed. Or it needs to be replaced.

  The removal method of the heat exchanger tube which concerns on this invention is demonstrated based on FIG.

  FIG. 3 shows the procedure of the method for removing the heat transfer tube 9.

  First, the heat transfer tube 9 is cut in the radial direction at an appropriate position from the portion where the defective portion 20 is generated toward the direction in which the heat transfer tube 9 is held, and the heat transfer tube 9a having the defective portion 20 is removed. . (First step)

  Next, jigs 41 and 42 are inserted into the inside of the cut surface 40 of the remaining portion 9b of the heat transfer tube. These jigs 41 and 42 are for forming the bottom of a filler 43 to be described later. The gap 13a between the heat transfer outer tube 13 and the heat transfer inner tube 14 is as shown in FIG. The inner ring 14a of the inner ring-shaped heat transfer tube 14 has a bowl-like shape as shown in FIG. 4B, and both have a C-shaped cross section. Therefore, when inserted into the heat transfer tube 9, the C-shape can be fixed inside by a repulsive force (elastic force) caused by being crushed in the radial direction. (Second step)

  The jigs 41 and 42 are preferably made of stainless steel having excellent heat resistance.

  Finally, a heat insulating material 43 having a sealing property and heat resistance is filled from the cut surface 40 into the heat transfer tube 9 (third process).

  Thereby, the remaining portion 9b of the heat transfer tube is sealed, and the melting furnace 1 can be operated even after the heat transfer tube is removed.

  In addition, about the heat insulating material 43, there exist materials, such as an alumina, a silica, a zirconia series ceramic material, and a ceramic fiber similarly to the case of a repair method.

For reference, the replacement is possible heat transfer tube of the heat transfer outside the tube, it will be described with reference to FIG.

FIG. 5 shows a structural cross section of a heat transfer tube in which the heat transfer outer tube can be replaced .

  The heat transfer outer tube 13 can be detachably separated at the inner position near the through hole 12 of the heat transfer tube 9. Here, for the detachable part A, the heat transfer outer tube 13 can be separated into two parts, a separation part 13c and a fixed part 13d.

  As for the structure of the detachable part A, for example, there are a structure that fits each other 50 as shown in FIG. 6A and a structure that screws 51 each other as shown in FIG. 6B.

  This replaceable structure is limited to the case where the heat transfer outer tube 13 is made of metal from the viewpoint of strength in the detachable portion A.

  Thus, since the heat transfer tube 9 has a structure that allows the heat transfer outer tube 13 to be replaced, the heat transfer outer tube 13 in which the defective portion 20 is generated in the separation portion 13c can be easily replaced. The life of the heat transfer inner tube 14 can be extended, and the period and cost for the replacement work of the heat transfer outer tube 13 can be rationalized.

It is explanatory drawing of the repair method of the heat-transfer outer tube | pipe which concerns on this invention. It is an example of the sealing method of the defective part of a heat exchanger outer tube. It is explanatory drawing of the removal method of the heat exchanger outer tube which concerns on this invention. It is a structural diagram of the jig according to the removal method of the heat transfer outer tube. Is a structural cross-sectional view exchange of the heat transfer tube capable of heat transfer outside the tube. It is an example of the detachable part of a heat-transfer outer tube. It is sectional drawing of a combustion melting furnace. It is a structure sectional view of a heat exchanger tube. It is the perspective view which showed arrangement | positioning of the heat exchanger tube in a high temperature air heater.

Explanation of symbols

1 Combustion melting furnace
2 Fuel melting part
3 High-temperature air heater 4 Pyrolysis gas 5 Gas supply line 6 Burner 7 Molten slag 8 Combustion gas 9 Heat transfer tube 9a Heat transfer tube portion 9b having a defective portion Heat transfer tube portion remaining after cutting 10 Slag outlet 11 Combustion melting furnace outer wall 12 Through-hole 13 Heat transfer outer tube 13a Gap 14 between heat transfer outer tube and heat transfer inner tube Heat transfer inner tube 14a Inside heat transfer inner tube 15 Heated air 16 Heated air 17 Heat transfer tube tip 18 Heat transfer outer tube Holding part 19 Heated air supply line 20 Defective part 30 Cylindrical steel plate 31 Heat insulating material 32 in gap part Seal plug 40 Cutting surface 41 Jig 42 for gap part between heat transfer outer tube and heat transfer inner tube Heat transfer inner tube The jig 43 for the inside of the heat insulating material 50 of the cutting part 50 fitting structure 51 screwing structure

Claims (2)

A plurality of heat transfer tubes are protruded from through holes provided in the wall surface of the combustion melting furnace in the atmosphere of the high temperature gas flowing in the combustion melting furnace, and the air flowing in the heat transfer tubes is heated by heat exchange with the high temperature gas. A method of repairing the heat transfer tube in a high-temperature air heater,
The heat transfer tube is composed of a metal inner tube, and an outer tube disposed coaxially with a space on the outer periphery of the inner tube,
A cylindrical steel plate is closely attached to the outer periphery of the outer tube so as to cover the outer surface of the defective portion such as a hole or crack generated in the outer tube, and fixed.
Further, a heat transfer tube repairing method is characterized in that a gap between the fixed cylindrical steel plate and the outer tube is filled with a heat insulating material. A plurality of heat transfer tubes are protruded from through holes provided in the wall surface of the combustion melting furnace in the atmosphere of the high temperature gas flowing in the combustion melting furnace, and the air flowing in the heat transfer tubes is heated by heat exchange with the high temperature gas. A method for removing the heat transfer tube in the high-temperature air heater,
The heat transfer tube is composed of a metal inner tube, and an outer tube disposed coaxially with a space on the outer periphery of the inner tube,
The heat transfer tube is cut in the radial direction in the vicinity of the axial direction of the defective portion such as a hole or crack generated in the outer tube,
Inserting and fixing a jig for closing the gap in the remaining heat transfer tube from the cut surface of the heat transfer tube remaining in the high-temperature air heater,
A heat transfer tube removing method, wherein a space defined by the fixed jig and the cut surface is filled with a heat insulating material.

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