JP2001255098A - Regenerative air preheater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a regenerative air preheater for improved corrosion resistance and erosion resistance of an element, longer element life, less maintenance cost, and smooth operation as the entire plant. SOLUTION: A metal 43 is sprayed to an end-part surface of an element 3 by a spraying gun 42 so that high-temperature/wear resistant coat is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regenerative air preheater.

[0002]

2. Description of the Related Art Generally, in a boiler plant, a regenerative air preheater is used in order to recover heat of boiler exhaust gas and save heat energy.

[0003] As such a regenerative air preheater,
As shown in FIG. 3, there is a stator 1 supported on a gantry 2 and having a cylindrical shape and having a large number of partition walls therein. An element 5 formed by laminating thin plates, a main shaft rotatably supported so as to extend in the vertical direction through a main shaft chamber 1a formed in the center of the stator 1, and a main shaft 5 disposed below the element 3 , A butterfly-shaped air inlet side hood, which is mounted on the main shaft 5 and is disposed above the element 3 and has a butterfly shaped air outlet side hood; A driving device for rotating and driving an air outlet side hood 7 connected to the air inlet side hood 6 via a main shaft 5; 9, an air inlet duct for sending air 10 to the air inlet side hood 6; Food 7
An air outlet duct for sending preheated air 12 from the boiler to the boiler, a gas inlet duct 13 for supplying the hot gas 14 discharged from the boiler to the element 3, and a low temperature gas 15 which has passed through the element 3 and exchanged heat. 16 is a gas outlet duct for discharging 16.

As shown in FIG. 4, the air outlet side hood 7 is a hood having a butterfly shape in plan view, and a lower surface of a hood frame 19 formed at a lower edge portion of the air outlet side hood 7 has A sealing frame 21 is attached via an expansion joint 20. The sealing frame 21 includes an arc-shaped member 21a having an I-shaped cross section extending in a circumferential direction 17 and an edge member 21b having an I-shaped cross section extending radially in a radial direction 18. A sealing shoe 22 is attached to a lower surface of the sealing shoe 2.
2 is the upper surface of the stator 1 and the stator flange portion 23
The upper surface has a very small gap or has a slight clearance, so that the air 12 does not leak to the gas inlet duct 13 through the gap between the upper surface of the stator 1 and the lower surface of the air outlet side hood 7. It is. Although not shown, the air inlet side hood 6 has substantially the same structure as that of the air outlet side hood 7, and the air 10 is supplied with gas 10 through a gap between the upper surface of the air inlet side hood 6 and the lower surface of the stator 1. It does not leak to the outlet duct 15 side.

[0005] As shown in FIG.
It is rotatably supported by the thrust bearing 24 via the support disk 5a and is rotatably supported by the bearings 25 and 26.

In the regenerative air preheater as described above, when preheating air, the drive unit 8 drives the air inlet side hood 6 and the air outlet side connected to the air inlet side hood 6 via the main shaft 5. The hood 7 is rotated in the horizontal direction, and the high-temperature gas 14 discharged from the boiler is introduced into the element 3 from the gas inlet duct 13 through the outside of the air outlet side hood 7 to heat the element 3. The gas is discharged to the gas outlet duct 15 through the outside of the air inlet side hood 6 and sent downstream from the gas outlet duct 15 as the low-temperature gas 16, while the air 10 is
Is introduced into the element 3 through the air inlet side hood 6, is heated by the heat of the element 3, is sent out into the air outlet side hood 7, passes through the air outlet side hood 7 and the air outlet duct 11, and is preheated. The air 12 is supplied to the boiler.

Since dust contained in the gas 14 discharged from the boiler adheres to the element 3, a soot blower for removing the dust adhering to the element 3 includes the air inlet side hood 6 and the soot blower. The air outlet side hood 7 is provided.

FIGS. 5 and 6 show an example of a soot blower provided in the hood 6 on the air inlet side. The soot blower is disposed at the center of rotation of the hood 6 on the air inlet side and sprays steam or the like. Supply pipe 28 for supplying medium 27
, A fixed pipe 29 fixed to the air inlet side hood 6 is connected via a rotary joint 30, and a nozzle header 32 provided with a plurality of nozzles 31 is connected to the fixed pipe 29 via a swivel joint 33. At the same time, the tip of a swing arm 34 projecting from the side of the air inlet side hood 6 so as to swing freely from the side of the air inlet side hood 6 is pivotally attached to both ends of the nozzle header 32. A nozzle header drive mechanism 35 for moving the nozzle header 32 by a required amount in a direction substantially parallel to the radial direction of the element 3 in conjunction with the rotation and reciprocating the nozzle header 32 is provided.

The nozzle header driving mechanism 35 has a wheel 37 provided with a plurality of paddles 36 arranged at a required pitch in the circumferential direction at a required position on the outer peripheral side of the side of the air inlet side hood 6 so as to be horizontally pivotable. A turning link 3 protruding radially from a rotation shaft 38 of the wheel 37.
9, the other end of the connection link 40 whose one end is pivotally attached to a required portion in the longitudinal direction of the nozzle header 32,
A stopper 41 for turning the wheel 37 by one pitch when the paddle 36 comes into contact with a circumferentially required position of the gas outlet duct 15 is provided so as to be able to be pushed and pulled.

[0010] The soot blower shown in FIGS.
During soot blowing, the stopper 41 is pushed out to a position where the stopper 41 interferes with the paddle 36 of the wheel 37, and every time the air inlet side hood 6 makes one rotation, the paddle 36 of the wheel 37 rotates. When the wheel passes the position where the stopper 41 is disposed, the wheel 37 horizontally turns by one pitch, and the turning link 39 and the connecting link 40
, The nozzle header 32 intermittently moves by a required amount in a direction substantially parallel to the radial direction of the element 3 and reciprocates, so that the position of each nozzle 31 in the radial direction of the element 3 changes, In this state, the supply pipe 28
To the nozzle header 32 via the rotary joint 30, the fixed pipe 29 and the swivel joint 33 from the spray medium 27 such as steam.
Is supplied, the spray medium 27 is sprayed from the plurality of nozzles 31 toward the lower surface side of the element 3,
The dust adhering to the element 3 is finally removed over the entire surface.

Although not shown, the air outlet side hood 7 also has a soot blower having the same structure as that provided in the air inlet side hood 6 and is vertically symmetrical at a position shifted by 180 ° in phase. The spray medium 27 is sprayed from the plurality of nozzles 31 toward the upper surface side of the element 3.

[0012]

In the conventional regenerative air preheater as described above, the low temperature side (the lower side in the example of FIG. 3).
Although the corrosion-resistant steel is used as the element 3 of the element 3, the lower end of the element 3 into which the air 10 flows is corroded by the condensation of sulfuric acid or the like, and the spray medium 2 such as steam from the soot blower is used.
The erosion caused by the injection of No. 7 causes the teeth to be lost in a saw-tooth shape, which shortens the life of the element 3 and necessitates replacement of the element 3 in a relatively short period of time. Also had the disadvantage of affecting.

In view of such circumstances, the present invention can improve the corrosion resistance and erosion resistance of the element, can extend the life of the element, can reduce the maintenance cost, and can smoothly operate the entire plant. An object of the present invention is to provide a regenerative air preheater that can contribute to operation.

[0014]

SUMMARY OF THE INVENTION The present invention provides a stator having a tubular shape and a heat exchange element disposed therein, and a rotatably disposed element connected to an opening of the stator. In a regenerative air preheater provided with an air hood for flowing air and a gas duct connected to an opening of a stator so as to cover the air hood and for flowing high-temperature gas to the element, the air in the element And a metal or cermet having a particle size of 3 to 60 [μm]
A regenerative air preheat, wherein a high-temperature abrasion-resistant film having a film thickness of 50 to 500 [μm] is formed by spraying a powder having a [%] or more at a particle flight speed of 100 [m / sec] or more. It is a container.

As the metal to be sprayed, 80 to 50% by weight of Ni and 50 to 20% by weight of C
An alloy containing r can be used. In addition, the alloy containing 5% by weight or less of Si, 5% by weight or less of B, 3% by weight of Cu or less, 3% by weight of Mo or less can be used. And 1% by weight or less of C may be added.

The cermet to be sprayed is 50 to
95% by weight of tungsten carbide or chromium carbide
Type or a combination of two types of carbides, the balance being Ni,
It is possible to use one composed of one or two kinds of combinations of metals or alloys of Cr and Co.

According to the above means, the following effects can be obtained.

If a high-temperature abrasion-resistant coating is formed on the end surface of the element in the flow direction of air and gas by spraying a metal or a cermet, the end of the element will be corroded by dew condensation of sulfuric acid and the like, and vapors from a soot blower will be formed. Erosion due to the injection of the spray medium is less likely to occur,
Saw tooth defects are less likely to occur, prolonging the life of the element, eliminating the need for frequent element replacement, lowering maintenance costs and reducing the impact on the operation of the entire plant. .

[0019]

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

FIGS. 1 and 2 show an embodiment of the present invention. In the drawings, the portions denoted by the same reference numerals as those in FIGS. 3 to 6 represent the same components. 3 to 6
1 and 2, the characteristic feature of the illustrated example is that, as shown in FIGS. 1 and 2, the end surface of the element 3 on the low temperature side on the inflow side of the air 10 (see FIG. 3). Another point is that a high-temperature wear-resistant coating 44 is formed by spraying a metal or cermet (mixed or composite material of metal and ceramic) 43 from a thermal spray gun 42.

Prior to element spraying, a roughening process is performed on the sprayed region by blasting. At this time, it is necessary to select conditions that do not cause deformation of the corrugate of the element 3.

When metal is sprayed from the spray gun 42, the particle flight speed is 100 [m / sec] or more, and the metal 43 to be sprayed has a particle diameter of, for example, 3 to 60 [μm].
Powder having 0% or more, and 80 to 80%
An alloy containing 50% by weight of Ni and 50 to 20% by weight of Cr can be used, and 5% by weight or less of Si, 5% by weight or less of B, 3% by weight %] Or less, 3 [% by weight] or less of Mo, and 1 [% by weight] or less of C may be added.

When the cermet is sprayed from the spray gun 42, the particle flying speed is 100 [m / sec] or more, and the cermet 43 to be sprayed is, for example, 3 to 60.
Powder having a particle size of [μm] of 80% or more,
95% by weight of tungsten carbide or chromium carbide
Type or a combination of two types of carbides, the balance being Ni,
It is possible to use one composed of one or two kinds of combinations of metals or alloys of Cr and Co.

On the other hand, as a spraying method for obtaining a particle flight speed of 100 [m / sec] or more, there is a plasma spraying method or a supersonic flame spraying method, and the distance between the tip of the spray gun 42 and the element spraying region is 50 to 300. The range of [mm] is selected.

The thickness of the high-temperature wear-resistant coating 44 is as follows:
About 50 to 500 [μm] is desirable.

Next, the operation of the illustrated example will be described.

When a metal or cermet 43 is sprayed from a thermal spray gun 42 onto the end surface of the element 3 on the low temperature side on the inflow side of the air 10 to form a high temperature wear-resistant coating 44, the air 10 of the element 3 flows in. The lower end of the element 3 is less likely to cause corrosion due to sulfuric acid condensation and erosion due to the injection of the spray medium 27 such as steam from a soot blower, and is also less likely to have saw-tooth-shaped defects. As a result, the element 3 does not need to be replaced frequently, so that maintenance costs are reduced and the operation of the entire plant is less affected.

If the thickness of the high-temperature abrasion-resistant coating 44 is too large, cracks may easily occur in the high-temperature abrasion-resistant coating 44. By setting the thickness to about 50 to 500 [μm], there is almost no fear that cracks will occur in the high-temperature wear-resistant coating 44.

Thus, the corrosion resistance and the erosion resistance of the element 3 can be improved, the life of the element 3 can be extended, the maintenance cost can be reduced, and the smooth operation of the whole plant can be contributed. .

The regenerative air preheater according to the present invention is not limited to the above-described embodiment, and the spraying gun is similarly applied to the end surface of the element 3 on the high temperature side on the inflow side of the gas 14. Of course, various changes can be made without departing from the gist of the present invention, such as forming a high-temperature abrasion-resistant coating 44 by spraying a metal or a cermet 43 from 42.

[0031]

As described above, according to the regenerative air preheater of the present invention, the corrosion resistance and erosion resistance of the element can be improved, the life of the element can be extended, and the maintenance cost can be reduced. It is possible to achieve an excellent effect that it is possible to reduce the amount and to contribute to the smooth operation of the whole plant.

[Brief description of the drawings]

FIG. 1 is a perspective view of an example of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of an element according to an example of an embodiment of the present invention.

FIG. 3 is an overall schematic configuration diagram of a general regenerative air preheater.

FIG. 4 is a perspective view of each part from the air outlet side hood to the stator of the regenerative air preheater.

FIG. 5 is a side view illustrating an example of a soot blower of a regenerative air preheater.

FIG. 6 is a plan view illustrating an example of a soot blower of a regenerative air preheater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator 3 Element 6 Air inlet side hood (air hood) 7 Air outlet side hood (air hood) 10 Air 13 Gas inlet duct (gas duct) 14 Gas 15 Gas outlet duct (gas duct) 42 Thermal spray gun 43 Metal or cermet 44 High temperature resistance Abrasive coating

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Miyoshi Hatakeyama 5292 Aioi, Aioi-shi, Hyogo Ishikawajima-Harima Heavy Industries Co., Ltd.Aioi Plant (72) Inventor Yusuke Takeishi 4--8 Honjo, Hachimanishi-ku, Kitakyushu-shi, Fukuoka Prefecture No. 16 Fujiki Kosan Co., Ltd. Head Office (72) Inventor Kazunori Sakata 4-8-16 Honjo, Hachimanishi-ku, Kitakyushu-shi, Fukuoka F-term (reference) 3L103 AA12 BB05 CC24 CC27 DD26 DD95 4K031 AA04 AB02 AB08 AB09 BA01 CB09 CB18 CB21 CB22 CB23 CB28 CB29 CB46 DA04 EA12

Claims (4)

[Claims] 1. A stator having a tubular shape and a heat exchange element disposed therein, and an air hood rotatably disposed so as to be connected to an opening of the stator and allowing air to flow through the element. And a gas duct connected to the opening of the stator so as to cover the air hood, and a gas duct for flowing high-temperature gas through the element. A metal or cermet is sprayed with a powder having a particle diameter of 3 to 60 [μm] of 80 [%] or more at a particle flight speed of 100 [m / sec] or more, and a film thickness of 50 to 500 [μm]. A regenerative air preheater characterized by forming a high-temperature abrasion-resistant coating. 2. The metal to be sprayed has a main component of 80%.
The regenerative air preheater according to claim 1, wherein the regenerative air preheater contains 50 to 20% by weight of Ni and 50 to 20% by weight of Cr. 3. The metal to be sprayed has an S content of 5% by weight or less.
i, B at 5% by weight or less, Cu at 3% by weight or less,
3. The regenerative air preheater according to claim 2, wherein 3% by weight or less of Mo and 1% by weight or less of C are added. 4. A cermet to be sprayed contains 50 to 95% by weight of a carbide of one or two kinds of tungsten carbide or chromium carbide, and the balance is Ni, Cr, C
2. The regenerative air preheater according to claim 1, comprising a composition of a metal or an alloy of one or two types of o.