WO2014136527A1

WO2014136527A1 - Corrosion control method for heat exchanger and corrosion control structure for heat exchanger

Info

Publication number: WO2014136527A1
Application number: PCT/JP2014/052929
Authority: WO
Inventors: 庸孝深海; 藤井　幹也; 修司高田
Original assignee: 住友重機械工業株式会社
Priority date: 2013-03-08
Filing date: 2014-02-07
Publication date: 2014-09-12
Also published as: PH12015501977A1; JPWO2014136527A1; TW201434728A; TWI520894B; JP6320992B2; MY177269A; PH12015501977B1

Abstract

A corrosion control method for a heat exchanger equipped with heat transfer pipes which exchange heat with a gas flowing in a flow path on the inside of heat transfer pipe securing members, wherein a configuration is adopted whereby the heat transfer pipes are equipped with cylindrical sleeves inserted or fitted around the outside of the heat transfer pipes, and the heat transfer pipes and/or the sleeves are moved relative to the heat transfer pipe securing members.

Description

Heat exchanger corrosion countermeasure method and heat exchanger corrosion countermeasure structure

The present invention relates to a heat exchanger corrosion countermeasure method and a heat exchanger corrosion countermeasure structure.

For example, a boiler or the like is provided with a heat exchanger for recovering the heat of the combustion exhaust gas generated in the furnace. In this heat exchanger, a flow path of the combustion exhaust gas is formed between the tube plates by arranging the flat tube plates so as to be orthogonal to the flow of the combustion exhaust gas flowing between these tube plates. A large number of heat transfer tubes are disposed in the tube, and as described in Patent Document 1 below, both sides of these heat transfer tubes are passed through the tube plates orthogonal to the heat transfer tubes, and the tube plates and the heat transfer tubes are welded together. The fixing configuration is widely known.

Here, in Non-Patent Document 1 below, in a gas air preheater (GasGaAir Heater) that exchanges heat with combustion exhaust gas and preheats air, if SOx and HCl are contained in the combustion exhaust gas, In particular, it is described that sulfuric acid dew point corrosion and hydrochloric acid dew point corrosion, which are low temperature corrosion, occur from condensation due to sulfuric acid dew point and hydrochloric acid dew point at a position on the air (preheated air) inlet side.

If the acid dew point corrosion occurs in the heat transfer tube and the thinning proceeds in this way, the worst hole will be opened, and the heat transfer tube must be replaced before that. In this case, it is common to remove the welded portion joining the tube plate and the heat transfer tube with, for example, a grinder and replace it with a new heat transfer tube.

Non-Patent Document 2 below, for example, in a gas air preheater (Gas Air Heater) that exchanges heat with combustion exhaust gas and preheats air, if SOx and HCl are contained in the combustion exhaust gas, In addition, sulfuric acid dew point and hydrochloric acid dew point cause dew point corrosion and hydrochloric acid dew point corrosion, which are low temperature corrosion, but by using the new S-TEN1 steel pipe (registered trademark) as the heat transfer tube, the above acid dew point corrosion can be prevented. Are listed.

JP 2007-296552 A

Here, in order to replace the heat transfer tube, when the welding between the tube sheet and the heat transfer tube is removed, the tube sheet is damaged, so an improvement is required. In addition, since it takes great care not to damage the tube sheet as much as possible, the construction time and cost due to labor are problems.

In addition, when using a new S-TEN1 steel pipe as the heat transfer pipe, the new S-TEN1 steel pipe is expensive and has a large number of heat transfer pipes. Therefore, the life should be extended without using such an expensive heat transfer pipe. Is required.

In any case, suitable anti-corrosion measures to solve the above problems are required.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a suitable heat exchanger corrosion countermeasure method and a heat exchanger corrosion countermeasure structure.

A corrosion countermeasure method for a heat exchanger according to an aspect of the present invention is a corrosion countermeasure method for a heat exchanger that includes a heat transfer tube that exchanges heat with a gas flowing in a flow path inside a heat transfer tube fixing member. A configuration including a cylindrical sleeve that is extrapolated or inserted into the tube is employed, and at least one of the heat transfer tube and the sleeve is moved with respect to the heat transfer tube fixing member.

According to such a heat exchanger corrosion countermeasure method, when at least one of the heat transfer tube and the sleeve is corroded, according to the corrosion, at least one of the heat transfer tube and the sleeve is moved with respect to the heat transfer tube fixing member. For example, corrosion can be moved in the axial direction, corrosion can be dealt with at low cost without using an expensive heat transfer tube, and a long life can be achieved. The heat transfer tube fixed to the heat transfer tube fixing member can be exchanged by moving it in the axial direction while the sleeve is fixed to the heat transfer tube fixing member, and the heat transfer tube is corroded without damaging the heat transfer tube fixing member. Heat tubes can be easily replaced. Thus, various suitable corrosion countermeasures can be realized.

Here, as a corrosion countermeasure method of the heat exchanger, a configuration including a sleeve that is passed through the heat transfer tube fixing member and fixed to the heat transfer tube fixing member, and a heat transfer tube that is passed through the sleeve and fixed to the sleeve. A method may be adopted in which the heat transfer tube and the sleeve are released from being fixed in accordance with the corrosion of the heat transfer tube, and the heat transfer tube is moved and replaced while the sleeve is fixed to the heat transfer tube fixing member.

According to such a heat exchanger corrosion countermeasure method, the heat transfer tube is fixed to the heat transfer tube fixing member by fixing the sleeve and the heat transfer tube fixed to the heat transfer tube fixing member. When the heat transfer tube is corroded, the heat transfer tube and the sleeve are unfixed according to the corrosion, and the heat transfer tube is moved and replaced while the sleeve is fixed to the heat transfer tube fixing member. . For this reason, the corroded heat transfer tube can be easily replaced without damaging the heat transfer tube fixing member.

Further, as a corrosion countermeasure method of the heat exchanger, a configuration including a sleeve passed through the heat transfer tube fixing member and fixed to the heat transfer tube fixing member, and a heat transfer tube passed through the sleeve and fixed to the sleeve is adopted. Then, according to the corrosion of at least one of the heat transfer tube and the sleeve, the fixing of the sleeve and the heat transfer tube fixing member, or the fixing of the heat transfer tube and the sleeve is released, and the released sleeve or heat transfer tube is moved in the axial direction. A method may be adopted in which the moved sleeve or heat transfer tube is fixed to the mating member that has been fixed before the fixing is released.

According to such a heat exchanger corrosion countermeasure method, a structure in which the heat transfer tube is fixed to the heat transfer tube fixing member via the sleeve is adopted, and if at least one of the heat transfer tube and the sleeve is corroded, In one method, the fixing of the sleeve and the heat transfer tube fixing member is released, and the heat transfer tube and the sleeve are moved in the axial direction while the heat transfer tube is fixed to the sleeve, and then the sleeve is moved to the heat transfer tube fixing member. Fixed to. In another method, the heat transfer tube and the sleeve are unfixed, the heat transfer tube is moved in the axial direction with the sleeve being fixed to the heat transfer tube fixing member, and then the heat transfer tube is fixed to the sleeve. The In any case, the corrosion can be moved in the axial direction, and the portion not corroded can be moved to the axial position where the corrosion has been formed. As a result, corrosion can be dealt with at a low cost without using an expensive heat transfer tube, and the life can be extended.

Also, as a method for preventing heat exchanger corrosion, a method of arranging a corrosion resistant material on the outer peripheral surface of the heat transfer tube on the sleeve side may be employed.

According to such a heat exchanger corrosion countermeasure method, the corrosion resistant material disposed on the outer peripheral surface of the sleeve side of the heat transfer tube can prevent corrosion of the heat transfer tube at a low cost without using an expensive heat transfer tube. Life can be extended.

Further, as a corrosion countermeasure method of the heat exchanger, a configuration including a sleeve passed through the heat transfer tube fixing member and fixed to the heat transfer tube fixing member, and a heat transfer tube passed through the sleeve and fixed to the sleeve is adopted. The corrosion-resistant material is coated on the outer peripheral surface of the heat transfer tube on the sleeve side, the axially outer end thereof is located in the sleeve, and the axially inner end thereof is the end of the sleeve axially inner side. You may employ | adopt the method of extending and exposing to an axial direction inner side from a part.

According to such a heat exchanger corrosion countermeasure method, the heat transfer tube is fixed to the heat transfer tube fixing member via the sleeve, and the outer peripheral surface of the heat transfer tube on the sleeve side is coated with the corrosion resistant material. The corrosion-resistant material has an end portion on the inner side in the axial direction extending and exposed to the inner side in the axial direction from the end portion on the inner side in the axial direction of the sleeve, so that corrosion of the heat transfer tube is prevented by the corrosion-resistant material, Since the end portion on the outer side in the axial direction of the corrosion resistant material is located in the sleeve, the sleeve and the heat transfer tube are fixed without hindrance. As a result, corrosion of the heat transfer tube can be prevented at low cost without using an expensive heat transfer tube, and the life can be extended.

Further, as a corrosion countermeasure method for a heat exchanger, a heat transfer tube that is passed through a heat transfer tube fixing member and fixed to the heat transfer tube fixing member, and a fluid that is passed through and supported in the heat transfer tube and exchanges heat with gas is contained inside. And a method of moving the sleeve according to the corrosion of the heat transfer tube.

According to such a heat exchanger corrosion countermeasure method, a structure in which the sleeve is engaged with the heat transfer tube fixing member via the heat transfer tube is adopted, and if the heat transfer tube corrodes, the heat transfer tube is transferred according to the corrosion. While being fixed to the heat tube fixing member, the sleeve in the heat transfer tube is moved in the axial direction. In one method, the position of the sleeve outlet serving as the outlet of the fluid flowing in the sleeve is set to the axis of the heat transfer tube. The low-temperature region that occurs near the sleeve outlet and causes corrosion of the heat transfer tube can be moved in the axial direction. In another method, the sleeve is moved in the axial direction and replaced with another sleeve having a different length, for example, so that the position of the sleeve outlet that causes corrosion of the heat transfer tube is changed from the position of the sleeve outlet before replacement. Can be moved in the axial direction. In any case, the position of the sleeve outlet can be moved in the axial direction, and the corrosion position of the incoming heat transfer tube can be changed in the axial direction. As a result, corrosion can be dealt with at a low cost without using an expensive heat transfer tube, and the life can be extended.

Here, a corrosion-resistant material may be disposed on the outer peripheral surface of the heat transfer tube on the sleeve side. According to this, the corrosion resistant material disposed on the outer peripheral surface of the heat transfer tube on the sleeve side can prevent corrosion of the heat transfer tube at a low cost without using an expensive heat transfer tube, and can extend the life.

The structure for preventing corrosion of a heat exchanger according to an aspect of the present invention includes a heat transfer tube fixing member, a heat transfer tube that exchanges heat with a gas flowing in a flow path inside the heat transfer tube fixing member, and an extrapolation or internalization of the heat transfer tube. A cylindrical sleeve to be inserted, and at least one of the heat transfer tube and the sleeve is movably supported with respect to the heat transfer tube fixing member.

According to such a heat exchanger corrosion countermeasure structure, the same actions and effects as the heat exchanger corrosion countermeasure method described above can be achieved.

Thus, according to the present invention, it is possible to provide a heat exchanger corrosion countermeasure method and a heat exchanger corrosion countermeasure structure capable of realizing a suitable corrosion countermeasure.

It is a schematic block diagram of the circulating fluidized bed boiler to which the corrosion countermeasure method of the heat exchanger of this invention is applied. It is a longitudinal cross-sectional view which shows the fixing structure of the heat exchanger tube to which the corrosion countermeasure method of the heat exchanger which concerns on 1st Embodiment of this invention is applied. It is explanatory drawing which shows the procedure of the corrosion countermeasure method of the heat exchanger which concerns on 1st Embodiment of this invention. It is explanatory drawing following FIG. It is explanatory drawing which shows the procedure of the corrosion countermeasure method of the heat exchanger which concerns on 2nd Embodiment of this invention. It is explanatory drawing following FIG. It is explanatory drawing following FIG. It is a longitudinal cross-sectional view which shows the fixing structure of the heat exchanger tube to which the corrosion countermeasure method of the heat exchanger which concerns on 3rd Embodiment of this invention is applied. It is a longitudinal cross-sectional view which shows the fixing structure of the heat exchanger tube to which the corrosion countermeasure method of the heat exchanger which concerns on 4th Embodiment of this invention is applied.

Hereinafter, a preferred embodiment of a heat exchanger corrosion countermeasure method according to the present invention will be described with reference to FIGS. 1 to 4 show the first embodiment of the present invention, FIGS. 5 to 7 show the second embodiment of the present invention, FIG. 8 shows the third embodiment of the present invention, and FIG. 9 shows the present invention. 4th Embodiment is shown, respectively, In each figure, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted.

First, the first embodiment shown in FIGS. 1 to 4 will be described. FIG. 1 is a schematic configuration diagram of a circulating fluidized bed boiler to which the heat exchanger corrosion countermeasure method of the present invention is applied, and FIG. 2 is a diagram of the heat exchanger corrosion countermeasure method according to the first embodiment of the present invention. FIG. 3 is an explanatory view showing the procedure of the corrosion countermeasure method for the heat exchanger according to the first embodiment of the present invention, and FIG. 4 is an explanatory view following FIG. is there.

As shown in FIG. 1, a circulating fluidized bed boiler 100 is generally heat-exchanged with a furnace 1 serving as a combustion furnace, a cyclone 2 that separates solid particles from the combustion exhaust gas generated in the furnace 1, and combustion exhaust gas from the cyclone 2. And a heat exchanging unit 3 for recovering exhaust heat.

The furnace 1 has a combustion chamber in the furnace wall. In the combustion chamber, a fluid material such as silica sand is accommodated, and fuel such as biomass and coal, or incineration of waste tires and garbage, which are to be combusted. A raw material such as a target waste is introduced, and a fluidized bed is formed while the raw material is flowed by combustion air described later to burn the raw material.

The cyclone 2 separates solid particles such as fluidized material, combustion ash, and unburned ash accompanying the combustion exhaust gas from the furnace 1 and returns them to the fluidized bed in the furnace 1.

The heat exchanging unit 3 includes a superheater 4, a economizer 5, and an air preheater 6 in this order from the upstream side to the downstream side in the flow path of the combustion exhaust gas downstream from the cyclone 2.

The economizer 5 preheats the boiler feed water by transferring the heat of the combustion exhaust gas to the boiler feed water through the heat transfer pipe. The boiler feed water preheated by the economizer 5 is converted into steam by a steam drum, and the steam is supplied to the superheater 4.

The superheater 4 is a superheated steam by transferring the heat of the combustion exhaust gas to the steam from the steam drum through the heat transfer tube. The superheated steam heated by the superheater 4 is used for a power generation turbine or the like.

The air preheater 6 preheats the air by transferring the heat of the combustion exhaust gas to the air through the heat transfer tube. The air preheated by the air preheater 6 is supplied to the furnace 1 as combustion air.

In this air preheater 6, as shown in FIG. 2, the flow path of the combustion exhaust gas is formed between the flat plate plates (heat transfer tube fixing members) 7, 7 arranged opposite to each other, A large number of heat transfer tubes 8 are arranged so as to be orthogonal to the flow (the vertical direction in the drawing) of the combustion exhaust gas flowing through the flow path on the inner side (the left side in the drawing) from the tube plate 7. In the figure, only one tube plate 7 is shown on the air inlet side, and only one heat transfer tube 8 is shown.

Here, in the present embodiment, the heat transfer tube 8 is fixed to the tube plate 7 via a cylindrical sleeve 9. Specifically, the sleeve 9 is passed through the tube plate 7 and fixed to the tube plate 7 by welding, and the heat transfer tube 8 is passed through the sleeve 9 and fixed to the sleeve 9 by welding.

More specifically, the outer peripheral surface of the sleeve 9 and the end surface on the outer side (the right side in the drawing) of the tube plate 7 are joined via a first welded portion 10 by fillet welding, for example, and the heat transfer tube 8. The outer peripheral surface and the outer end surface of the extrapolated sleeve 9 are joined via a second welded portion 11 by fillet welding, for example. The joining of the tube plate 7 and the sleeve 9 and the joining of the sleeve 9 and the heat transfer tube 8 can be performed not only by welding but also by pressure welding, mechanical installation, and the like. The heat transfer tube 8, the sleeve 9, and the tube plate 7 are made of steel. However, any material such as S-TEN1 (registered trademark) or SUS will corrode, so S-TEN1 (registered trademark). ) Or SUS or the like may be used.

Here, as an assembling procedure, the tube plate 7 and the sleeve 9 are welded to the tube plate 7 through the sleeve 9, and then the sleeve 9 and the heat transfer tube 8 are welded to the sleeve 9 fixed to the tube plate 7 through the heat transfer tube 8. Also in the procedure, the sleeve 9 and the heat transfer tube 8 are welded to the sleeve 9 through the heat transfer tube 8, and then the sleeve 9 to which the heat transfer tube 8 is fixed is passed through the tube plate 7 to weld the sleeve 9 and the tube plate 7.

Since the tube plate 7 and the sleeve 9 are fixed and the sleeve 9 and the heat transfer tube 8 are fixed by welding, the flow path inside the tube plate 7 is surely sealed to ensure airtightness. Here, the

welds

10 and 11 are formed by fillet welding, but may of course be formed by groove welding.

According to the circulating fluidized bed boiler 100 having such a configuration, the combustion exhaust gas discharged from the furnace 1 and solid particles separated by the cyclone 2 is supplied to the superheater 4, the economizer 5, and the air preheater 6. By passing, heat exchange is performed with each heat transfer tube, and exhaust heat is recovered.

Here, the air preheater 6 is located on the most downstream side of the flow path through which the combustion exhaust gas flows, and the exhaust heat of the combustion exhaust gas is recovered by the superheater 4 and the economizer 5 upstream of the air preheater 6. Therefore, the temperature of the combustion exhaust gas that exchanges heat with the air preheater 6 is low. In particular, the temperature on the air inlet side (near the tube plate 7) of the heat transfer tube 8 of the air preheater 6 is low. When the temperature is 60 to 80 ° C. or lower, hydrochloric acid dew point corrosion tends to occur.

Then, as shown in FIG. 2, when acid dew point corrosion C occurs in the heat transfer tube 8, in this embodiment, the heat transfer tube 8 is replaced according to the degree of the corrosion C (before the hole is opened). . Although FIG. 2 shows an example in which corrosion C occurs on the outer peripheral side of the heat transfer tube 8, corrosion C may occur on the inner peripheral side. The same applies to the drawings after FIG. Further, FIG. 5 and the like which will be described later also show an example in which the corrosion C occurs on the outer peripheral side of the sleeve 9, but the corrosion C may occur on the inner peripheral side.

Specifically, the second welded portion 11 that joins the sleeve 9 and the heat transfer tube 8 is removed as shown in FIG. 3 by, for example, a grinder, and the sleeve 9 remains fixed to the tube plate 7. Then, the heat transfer tube 8 is moved in the direction of the arrow shown in the drawing and pulled out. Then, as shown in FIG. 4, the heat transfer tube 18 is replaced with a new heat transfer tube 18, and the outer peripheral surface of the heat transfer tube 18 and the outer end surface of the sleeve 9 are It joins via the 2nd welding part 21 by meat welding.

Here, the corrosion C of the heat transfer tube 8 is visually recognized, and the heat transfer tube 8 is replaced according to the degree of the corrosion C. For example, the degree of the corrosion C is automatically detected by a sensor or a camera. It is also possible to automatically recognize the replacement time by a computer.

Thus, according to the corrosion countermeasure method of the present embodiment, the cylindrical sleeve 9 that is passed through the tube plate 7 and fixed to the tube plate 7, and the transmission that is passed through the sleeve 9 and fixed to the sleeve 9. When the heat transfer tube 8 is corroded and the heat transfer tube 8 corrodes, the heat transfer tube 8 and the sleeve 9 are unfixed according to the corrosion C, and the sleeve 9 remains fixed to the tube plate 7. Since the heat transfer tube 8 is moved and replaced, the corroded heat transfer tube 8 can be easily replaced without damaging the tube plate 7.

In addition, when the outer end of the sleeve 9 is deformed by repeated replacement of the heat transfer tube, the outer end of the sleeve 9 may be cut off and used continuously.

FIG. 5 is an explanatory diagram showing the procedure of the corrosion countermeasure method according to the second embodiment of the present invention, FIG. 6 is an explanatory diagram following FIG. 5, and FIG. 7 is an explanatory diagram following FIG.

The heat transfer tube fixing structure to which the corrosion countermeasure method according to the second embodiment is applied is the same as that shown in FIG. 2 of the first embodiment.

In the second embodiment, when acid dew point corrosion C occurs in the sleeve 9 or the heat transfer tube 8 (corrosion C occurs in the sleeve 9 in FIG. 5), depending on the degree of corrosion C ( For example, before the hole is formed in the heat transfer tube 8, the heat transfer tube 8 and the sleeve 9 are moved in the axial direction.

Specifically, the first welded portion 10 (see FIG. 2) that joins the tube plate 7 and the sleeve 9 is removed by, for example, a grinder as shown in FIG. 5, and the heat transfer tube 8 is fixed to the sleeve 9. In this state, the heat transfer tube 8 and the sleeve 9 are moved in the axial direction as indicated by arrows in FIG. Here, the heat transfer tube 8 and the sleeve 9 are moved inward (left side in the figure).

Then, when the heat transfer tube 8 and the sleeve 9 are moved, as shown in FIG. 7, the outer peripheral surface of the sleeve 9 and the outer end surface (the right side in the drawing) of the tube plate 7 are, for example, a first weld 20 by fillet welding. Join through.

Here, the corrosion C is visually recognized and the heat transfer tube 8 and the sleeve 9 are moved in the axial direction according to the degree of the corrosion C. However, the degree of the corrosion C is automatically detected by, for example, a sensor or a camera. It is also possible to automatically recognize the movement time and determine the movement time automatically by a computer.

Further, the movement of the sleeve 9 and the heat transfer tube 8 is such that the acid dew point corrosion C occurs in both the sleeve 9 and the heat transfer tube 8 regardless of whether the acid dew point corrosion C occurs in the sleeve 9 or the acid dew point corrosion C occurs in the heat transfer tube 8. Corrosion C may be generated. In short, it may be performed when acid dew point corrosion C occurs in at least one of the heat transfer tube 8 and the sleeve 9.

Thus, according to the corrosion countermeasure method of the second embodiment, the tubular sleeve 9 passed through the tube plate 7 and fixed to the tube plate 7, and passed through the sleeve 9 and fixed to the sleeve 9. When at least one of the heat transfer tube 8 and the sleeve 9 is corroded, the sleeve 9 and the tube plate 7 are released according to the corrosion C, and the heat transfer tube 8 is attached to the sleeve 9. Since the heat transfer tube 8 and the sleeve 9 are moved in the axial direction in a state where they are fixed, and then the sleeve 9 is fixed to the tube plate 7, the corrosion C can be moved in the axial direction and is corroded. The part which has not corroded can be moved to the axial direction position where C was formed. As a result, corrosion can be dealt with at a low cost without using an expensive heat transfer tube, and the life can be extended.

Note that, as shown in FIG. 5, when the sleeve 9 corrodes, the time until the corrosion C reaches the heat transfer tube 8 can be increased, so that the life can be further extended.

When the sleeve 9 is not corroded and only the heat transfer tube 8 is corroded, the heat transfer tube 8 and the sleeve 9 are unfixed as another method different from the above one method, and the sleeve 9 is replaced with the tube plate. 7, the heat transfer tube 8 may be moved in the axial direction, and then the heat transfer tube 8 may be fixed to the sleeve 9. Also in this case, the corrosion C can be moved in the axial direction, and a portion that is not corroded can be moved to the axial position where the corrosion C was formed. As a result, corrosion can be dealt with at a low cost without using an expensive heat transfer tube, and the life can be extended.

As described above, the fixing structure shown in FIG. 2 functions as the corrosion countermeasure structure 200 of the heat exchanger. The anti-corrosion structure 200 includes a tube plate 7 as a heat transfer tube fixing member, a heat transfer tube 8 that exchanges heat with a gas flowing in a flow path inside the tube plate 7, and a cylindrical sleeve that is extrapolated to the heat transfer tube 8. 9, and at least one of the heat transfer tube 8 and the sleeve 9 is movably supported with respect to the tube plate 7. The heat exchanger anti-corrosion structure 200 supports the sleeve 9 and the heat transfer tube 8 by the tube plate 7. As shown in FIG. 3, the heat transfer tube 8 can move relative to the tube plate 7 (and the sleeve 9) by removing the second welded portion 11 between the heat transfer tube 8 and the sleeve 9. it can. The state in which the movement of the heat transfer tube 8 is temporarily restricted by the removable second welded portion 11 is a state in which the movement of the heat transfer tube 8 is allowed by the removal of the second welded portion 11. This corresponds to a state in which the heat transfer tube 8 is supported so as to be movable with respect to the tube plate 7. As shown in FIG. 5, the heat transfer tube 8 and the sleeve 9 can move with respect to the tube plate 7 by removing the first welded portion 10 between the tube plate 7 and the sleeve 9. In the state where the movement of the heat transfer tube 8 and the sleeve 9 is temporarily restricted by the removable first welded portion 10, the movement of the heat transfer tube 8 and the sleeve 9 is allowed by the removal of the first welded portion 10. Therefore, it corresponds to a state in which the heat transfer tube 8 and the sleeve 9 are supported so as to be movable with respect to the tube plate 7.

FIG. 8 is a longitudinal sectional view showing a heat transfer tube fixing structure to which the corrosion countermeasure method according to the third embodiment of the present invention is applied.

The heat transfer tube fixing structure of the third embodiment is different from the heat transfer tube fixing structure of the first and second embodiments shown in FIG. 2 in that a corrosion resistant material 12 is provided on the outer peripheral surface of the heat transfer tube 8 on the sleeve 9 side. This is the point that was placed. Note that the fixing structure shown in FIG. 8 functions as a corrosion countermeasure structure 300 that has the same effect and effect as the corrosion countermeasure structure 200 of the heat exchanger shown in FIG.

Specifically, the corrosion-resistant material 12 is provided on the outer peripheral surface of the heat transfer tube 8 on the sleeve 9 side so as to enter the gap 13 between the inner peripheral surface of the sleeve 9. The end portion on the outer side in the axial direction of the corrosion-resistant material 12 is located in the sleeve 9, and the end portion on the inner side in the axial direction extends from the end portion on the inner side in the axial direction of the sleeve 9 to the inner side in the axial direction. Thus, the heat transfer tube 8 is covered.

Here, the corrosion-resistant material 12 is a corrosion-resistant coating applied to the outer peripheral surface of the heat transfer tube 8, and specific examples thereof include thermal spraying, painting, lining, and the like. Further, for example, a glass tube which is a corrosion-resistant material may be inserted into the gap 13 between the heat transfer tube 8 and the sleeve 9 so that the glass tube is covered with the heat transfer tube 8. In addition, it is more preferable that the corrosion-resistant material 12 has wear resistance in addition to corrosion resistance.

Here, as an assembly procedure, the tube plate 7 and the sleeve 9 are welded to the tube plate 7 through the sleeve 9, and then the sleeve 9 fixed to the tube plate 7 is passed through the heat transfer tube 8 coated with the corrosion resistant material 12 to the sleeve 9. Also in the procedure of welding the heat transfer tube 8, the sleeve 9 and the heat transfer tube 8 are welded to the sleeve 9 through the heat transfer tube 8 coated with the corrosion resistant material 12, and then the sleeve 9 to which the heat transfer tube 8 is fixed is passed through the tube plate 7. Alternatively, the procedure of welding the sleeve 9 and the tube sheet 7 may be used.

And in this 3rd Embodiment, the corrosion countermeasure method of the 1st, 2nd embodiment mentioned above is applied with respect to the heat exchanger tube 8 which has the said corrosion-resistant material 12. FIG.

Therefore, according to the third embodiment, in addition to the operations and effects of the first and second embodiments, an expensive heat transfer tube is used by the corrosion resistant material 12 disposed on the outer peripheral surface of the heat transfer tube 8 on the sleeve 9 side. Therefore, corrosion of the heat transfer tube 8 can be prevented at low cost, and the life can be extended.

In addition, according to the third embodiment, the sleeve 9 is passed through the tube plate 7 and fixed to the tube plate 7, and the heat transfer tube 8 is passed through the sleeve 9 and fixed to the sleeve 9. And the outer peripheral surface of the heat transfer tube 8 on the sleeve 9 side is coated with a corrosion-resistant material 12, and the end portion on the inner side in the axial direction of the corrosion-resistant material 12 extends inward in the axial direction from the end portion on the inner side in the axial direction of the sleeve 9. Since the corrosion-resistant material 12 prevents the heat transfer tube 8 from being corroded and the end portion on the axially outer side of the corrosion-resistant material 12 is located in the sleeve 9, the axial direction of the sleeve 9 is exposed. The outer end portion and the outer peripheral surface of the heat transfer tube 8 can be welded by the second welding portion 11 without any hindrance. When not welding, the sleeve 9 and the heat transfer tube 8 can be fixed without hindrance. That is, in addition to the operations and effects of the first and second embodiments, the corrosion resistant material 12 can prevent corrosion of the heat transfer tube 8 at a low cost without using an expensive heat transfer tube, and can extend the life. .

In addition, since the heat exchange efficiency falls, the structure which coat | covers the corrosion-resistant material 12 to the outer peripheral surface of the heat exchanger tube 8 cannot be employ | adopted.

FIG. 9 is a longitudinal sectional view showing a heat transfer tube fixing structure to which the corrosion countermeasure method according to the fourth embodiment of the present invention is applied.

In the fourth embodiment, the heat transfer tube 8 is passed through the tube plate 7 and fixed to the tube plate 7 by, for example, welding, and the sleeve 19 is inserted into the heat transfer tube 8 and supported by the heat transfer tube 8. It is an inner sleeve.

Specifically, the sleeve 19 is inserted into the heat transfer tube 8, and the end portion on the inner side in the axial direction is arranged so as to extend in a shorter direction toward the inner side than the tube plate 7 on the air inlet side. A pair of O-

rings

30 and 31 are disposed between the outer peripheral surface of the sleeve 19 and the inner peripheral surface of the heat transfer tube 8 so as to be separated in the axial direction. The O-

rings

30 and 31 are located on both sides of the tube plate 7, and the sleeve 19 is centered and supported by the O-

rings

30 and 31 with respect to the heat transfer tube 8. Further, the O-

rings

30 and 31 seal between the sleeve 19 and the heat transfer tube 8, and air (fluid) exchanging heat with the combustion exhaust gas leaks from between the sleeve 19 and the heat transfer tube 8. To prevent.

In such a heat transfer tube fixing structure of the fourth embodiment, air for performing heat exchange flows in the sleeve 19 by entering the axially outer end of the sleeve 19 as an inlet. The inside end portion flows out as an outlet and flows through the heat transfer tube 8 toward the downstream side, whereby heat exchange with the combustion exhaust gas is performed.

Here, since low-temperature air for heat exchange flows out from the outlet of the sleeve 19, the vicinity of the outlet of the sleeve 19 in the heat transfer tube 8 becomes the lowest temperature region, and acid dew point corrosion C is caused here. Become.

Therefore, in this fourth embodiment, when acid dew point corrosion C occurs in the heat transfer tube 8, the sleeve 19 is attached according to the degree of the corrosion C (for example, before a hole is opened in the heat transfer tube 8). Move in the axial direction.

Specifically, the sleeve 19 is moved in the axial direction as indicated by an arrow in FIG. 9 while the heat transfer tube 8 is fixed to the tube plate 7. Here, the sleeve 19 is moved inward (left side in the figure). At this time, since the sleeve 19 is supported by the heat transfer tube 8 via the O-

rings

30 and 31, it can be easily moved in the axial direction.

And, since the outlet of the sleeve 19 moves in the axial direction relative to the heat transfer tube 8 by such movement of the sleeve 19, the low temperature region of the heat transfer tube 8 causing corrosion can be moved in the axial direction.

Here, the corrosion C of the heat transfer tube 8 is visually recognized and the sleeve 19 is moved in the axial direction in accordance with the degree of the corrosion C. For example, the corrosion C of the heat transfer tube 8 is detected by a sensor or a camera. It is also possible to automatically recognize the degree of movement and automatically determine the movement time by a computer.

According to such 4th Embodiment, the structure which the sleeve 19 engages with the tube plate 7 via the heat exchanger tube 8 is employ | adopted, and when the heat exchanger tube 8 corrodes, according to the corrosion C, the heat exchanger tube 8 is made. Since the sleeve 19 in the heat transfer tube 8 is moved in the axial direction while being fixed to the tube plate 7, the position of the outlet of the sleeve 19 serving as an outlet for the air flowing in the sleeve 19 is set to the heat transfer tube. 8 can be moved in the axial direction, and a low temperature region that occurs near the outlet of the sleeve 19 and causes corrosion of the heat transfer tube 8 can be moved in the axial direction. That is, by moving the position of the outlet of the sleeve 19 in the axial direction, the corrosion position of the incoming heat transfer tube 8 can be changed in the axial direction. As a result, corrosion can be dealt with at a low cost without using an expensive heat transfer tube, and the life can be extended.

Also, as another method different from the above one method, the sleeve 19 may be moved in the axial direction and replaced with another sleeve having a different length, for example. Also in this case, the position of the outlet of the sleeve 19 that causes corrosion of the heat transfer tube 8 can be moved in the axial direction with respect to the position of the outlet of the sleeve 19 before replacement. That is, by moving the position of the outlet of the sleeve 19 in the axial direction, the corrosion position of the incoming heat transfer tube 8 can be changed in the axial direction. As a result, corrosion can be dealt with at a low cost without using an expensive heat transfer tube, and the life can be extended.

In addition, it is preferable to arrange the corrosion-resistant material described in the third embodiment on the inner peripheral surface of the heat transfer tube 8 on the sleeve 19 side (position causing corrosion). According to this, the corrosion resistant material can prevent corrosion of the heat transfer tube 8 at a low cost without using an expensive heat transfer tube, and can extend the life.

As described above, the fixing structure shown in FIG. 9 functions as the corrosion countermeasure structure 400 of the heat exchanger. The anti-corrosion structure 400 includes a tube plate 7 as a heat transfer tube fixing member, a heat transfer tube 8 that exchanges heat with a gas flowing in a flow path inside the tube plate 7, and a cylindrical sleeve that is inserted into the heat transfer tube 8. 19, and at least one of the heat transfer tube 8 and the sleeve 19 is movably supported with respect to the tube plate 7. The heat exchanger anti-corrosion structure 400 supports the sleeve 19 and the heat transfer tube 8 by the tube plate 7. As shown in FIG. 9, the sleeve 19 can move with respect to the tube plate 7 (and the heat transfer tube 8) while being supported by the O-

rings

30 and 31.

The present invention has been specifically described above based on the embodiment. However, the present invention is not limited to the above embodiment. For example, in the above embodiment, the circulating fluidized bed boiler 100 is applied to the combustion exhaust gas. Although described, it can be applied to combustion exhaust gas from other boilers, combustion exhaust gas from incinerators, melting furnaces, etc., and can also be applied to pyrolysis gas (combustible gas) of gasification furnaces, etc. .

Moreover, in the said embodiment, although application to the heat exchanger tube 8 of the air preheater 6 is described as being especially suitable, not only the acid dew point corrosion which becomes low temperature corrosion but the molten salt which becomes high temperature corrosion It can also be applied to, for example, a heat exchanger tube of a superheater where corrosion occurs. In short, it is a heat exchanger tube for heat exchange that exchanges heat with gas. It can be applied to.

7 ... Tube plate (heat transfer tube fixing member), 8, 18 ... Heat transfer tube, 9, 19 ... Sleeve, 10, 20 ... First weld, 11, 21 ... Second weld, 12 ... Corrosion resistant material, 200 , 300, 400 ... Corrosion countermeasure structure of heat exchanger, C ... Corrosion.

Claims

It is a corrosion countermeasure method for a heat exchanger provided with a heat transfer tube for exchanging heat with a gas flowing through a flow path inside the heat transfer tube fixing member,
Adopting a configuration comprising a cylindrical sleeve extrapolated or inserted into the heat transfer tube,
A corrosion countermeasure method for a heat exchanger, wherein at least one of the heat transfer tube and the sleeve is moved relative to the heat transfer tube fixing member.
Adopting a configuration comprising the sleeve passed through the heat transfer tube fixing member and fixed to the heat transfer tube fixing member, and the heat transfer tube passed through the sleeve and fixed to the sleeve,
In response to corrosion of the heat transfer tube, release the fixing of the heat transfer tube and the sleeve,
The heat exchanger corrosion countermeasure method according to claim 1, wherein the heat transfer tube is moved and replaced while the sleeve is fixed to the heat transfer tube fixing member.
Adopting a configuration comprising the sleeve passed through the heat transfer tube fixing member and fixed to the heat transfer tube fixing member, and the heat transfer tube passed through the sleeve and fixed to the sleeve,
In response to corrosion of at least one of the heat transfer tube and the sleeve, the sleeve and the heat transfer tube fixing member are fixed, or the heat transfer tube and the sleeve are fixed, and the sleeve or the heat transfer tube is released. Move in the axial direction,
The corrosion countermeasure method for a heat exchanger according to claim 1, wherein the moved sleeve or the heat transfer tube is fixed to a mating member fixed before the fixing is released.
The heat exchanger corrosion countermeasure method according to any one of claims 1 to 3, wherein a corrosion-resistant material is disposed on the outer peripheral surface of the heat transfer tube on the sleeve side.
Adopting a configuration comprising the sleeve passed through the heat transfer tube fixing member and fixed to the heat transfer tube fixing member, and the heat transfer tube passed through the sleeve and fixed to the sleeve,
The corrosion-resistant material is coated on the outer peripheral surface of the heat transfer tube on the sleeve side, and its axially outer end is located in the sleeve, and its axially inner end is in the axial direction of the sleeve. 5. The heat exchanger corrosion countermeasure method according to claim 4, wherein the heat exchanger is exposed to extend inward in the axial direction from the inner end.
The heat transfer tube that is passed through the heat transfer tube fixing member and is fixed to the heat transfer tube fixing member, and a sleeve that is passed through and supported by the heat transfer tube and in which a fluid that exchanges heat with the gas flows. Adopting the configuration
The heat exchanger corrosion countermeasure method according to claim 1, wherein the sleeve is moved in accordance with corrosion of the heat transfer tube.
The method for preventing corrosion of a heat exchanger according to claim 6, wherein a corrosion-resistant material is disposed on the outer peripheral surface of the heat transfer tube on the sleeve side.
A heat transfer tube fixing member, and a heat transfer tube that exchanges heat with the gas flowing in the flow path inside the heat transfer tube fixing member,
A tubular sleeve extrapolated or inserted into the heat transfer tube,
A heat exchanger anti-corrosion structure for supporting at least one of the heat transfer tube and the sleeve so as to be movable with respect to the heat transfer tube fixing member.