JP2016061542A - Exhaust gas heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas heat exchanger having a superior acid corrosion resistance, capable of quite easily and efficiently performing inspection, repairing and replacement of a heat transfer pipe and having a simple structure.SOLUTION: A heat exchanger shell 1 has a fixable or removable lid plate 11, its inner side is partitioned into an upstream side sub-chamber 13 and a downstream side sub-chamber 14 and a water conduction pipe passage 4 is connected between both sub-chambers 13, 14 through each of connection headers. Many heat transfer pipes 2 suspended from the heat exchanger shell show double-pipes by an outer pipe having lower end closed and coated with fluorine resin and an inner pipe of fluorine resin having its lower end opened, every plurality of pipes constitute a group of pipes corresponding to each of the headers, each of the outer pipes is inserted, fitted and fixed to bottom walls 15 of both sub-chambers at its opened upper end part, upper sides of the inner pipes are extended into the sub-chambers, collected at their corresponding headers and communicated therewith, cold water W1 fed into the inlet header 31 is heat exchanged with combustion exhaust gas G1 of high temperature at a process reaching the outlet header 32 while being reciprocated in each of the heat transfer pipes and then the water is fed out as hot water W2.SELECTED DRAWING: Figure 1

Description

  The present invention is installed in an exhaust gas duct of combustion exhaust gas such as boiler exhaust gas, and heat recovery is performed by warming and recovering cold water introduced by heat exchange with the combustion exhaust gas, and for exhaust gas used for lowering the temperature of the combustion exhaust gas. It relates to a heat exchanger.

  Generally, as means for recovering heat from high-temperature combustion exhaust gas such as boiler exhaust gas, a heat transfer pipe is disposed in an exhaust gas duct through which the combustion exhaust gas flows, and cold water (tap water) supplied to the heat transfer pipe is used as combustion exhaust gas. The method of raising the temperature by heat exchange and taking it out as hot water is widely adopted (for example, Patent Documents 1 and 2).

However, combustion exhaust gas generally contains sulfurous acid gas (SO ₂ ) and sulfuric acid gas (SO ₃ ) derived from sulfur in the fuel, and strong corrosiveness due to these (especially acid due to condensation in a low temperature part below the dew point). Since there is dew point corrosion), there is a problem that metal parts in contact with the exhaust gas such as the heat transfer pipe of the heat exchanger for exhaust gas and its pipe support part corrode quickly. Therefore, conventionally, as a countermeasure against acid corrosion of heat exchangers for exhaust gas, a metal material with high corrosion resistance such as stainless steel or low alloy steel is used for the gas contact part, or a fluorine resin lining is used for the metal surface of the gas contact part. At present, the following exhaust gas heat exchangers have been put into practical use only as those having excellent acid corrosion resistance (Non-patent Document 1).

  As shown in FIG. 6, the exhaust gas heat exchanger in practical use includes a large number (several hundreds) of heat transfer tubes 200 from a heat exchanger shell 100 made of carbon steel disposed on the ceiling of the exhaust gas duct 10. Is drooping. The heat exchanger shell 100 is divided into upper and lower parts by a horizontal partition plate 101, and the partitioned upper space is partitioned into an inlet side compartment 111, an outlet side compartment 112 and an intermediate compartment 113 by a vertical partition wall 110. In addition, the lower space is also divided into an upstream chamber 121 and a downstream chamber 122 by the vertical partition wall 120. The inlet-side compartment 111 is provided with an inlet header 131 for introducing the cold water W1, and the outlet-side compartment 112 is provided with an outlet header 132 for extracting the hot water W2 after heat exchange. On the other hand, each heat transfer tube 200 has an outer tube 201 whose upper end is fixed to a seal plate 102 that forms the bottom wall of the heat exchanger shell 100 and an upper end that is inserted into the outer tube 201 and is fixed to the horizontal partition plate 101. It is a double tube made up of an inner tube 202 shown by a dashed dotted line in the figure. A cleaning water nozzle 300 is provided upstream of the exhaust gas duct 10 to inject cleaning water W3 toward the heat transfer tube 200 to wash away the adhering dust. It is discharged from the lower drain 400.

  As shown in detail in FIG. 7, the outer tube 201 of each heat transfer tube 200 is provided with a coating layer 212 of fluororesin PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) on the outer surface of the stainless steel tube 211. The lower end is closed with a plug (not shown), the opened upper end is inserted into the locking hole 102a of the seal plate 102, and the upper, middle, lower and upper three portions of the insertion portion are expanded in diameter 213. It is fixed to 102. The inner tube 202 is made of a fluororesin FEP (tetrafluoroethylene / hexafluoropropylene copolymer) tube, and both upper and lower ends are open, and the upper end side penetrates through the mounting hole 101a of the horizontal partition plate 101. The stainless steel short pipe 221 is press-fitted on the inner side, thereby being fixed to the horizontal partition plate 101. A loose lining 150 of fluororesin PFA is applied to the surface of the gas contact portion of the heat exchanger shell 100 including the bottom surface of the seal plate 102.

  In this heat exchanger for exhaust gas, the heat exchange part is divided into four regions Z1 to Z4 from the inlet side to the outlet side as shown in FIG. 6 by the above configuration, and the cold water introduced from the inlet header 131 to the inlet side compartment 111. W1 distributes and flows into the inner tube 202 of each heat transfer tube 200 in the region Z1 directly below the inlet-side compartment 111, flows out from the lower end thereof, rises inside the outer tube 201, and flows into the upstream chamber 121. . Next, in the region Z2 where the upstream chamber 121 faces the intermediate compartment 113, it flows into the outer tube 201 of each heat transfer tube 200, flows into the inner tube 202 from its lower end, rises, and enters the intermediate compartment 113. leak. Subsequently, in the region Z3 where the intermediate compartment 113 faces the downstream chamber 122, it flows into the inner tube 202 of each heat transfer tube 200, flows out from its lower end, rises inside the outer tube 201, and flows into the downstream chamber 122. Spill to Further, in the region Z4 immediately below the outlet side compartment 112, it flows into the outer pipe 201 of each heat transfer pipe 200, flows into the inner pipe 202 from the lower end inside, rises, and flows out into the outlet side compartment 112. The hot water W2 heated by heat exchange with the exhaust gas in the process is led out from the outlet header 132. In addition, FIG. 7 has shown the operating line of heat exchange, and while the introduced cold water W1 goes through each area | region Z1-Z4 sequentially, it heats up in steps and derives as hot water W2, while high temperature exhaust gas G1 is On the other hand, the temperature is continuously lowered by passing through the region Z4 → Z1, and moves to the downstream side as the low temperature exhaust gas G2.

JP 2010-255925 A JP 2014-126330 A

Internet Web Airflow Rich / Acid Resistance Heat Exchanger / ITOCHU Machine Technos Co., Ltd. Search Date: July 7, 2014, http://www.itcmt.co.jp/products/industrial/plant/airflow.html

  However, in the case of the conventional exhaust gas heat exchanger, as shown in FIG. 7, the upper wall portion of the heat exchanger shell 100 is constituted by a detachable lid plate 103 that is bolted to the periphery via a packing 104. However, when checking whether there is an abnormality in the heat transfer tube 200, even if the cover plate 103 is removed, the horizontal partition plate 101 is present, so the state of each heat transfer tube 200 cannot be visually confirmed as it is, In order to inspect, it is necessary to pull up a large number of inner pipes 202 to which the horizontal partition plate 101 is fixed, and take them out of the heat exchanger shell 100. This work requires a great deal of labor and time, and repair and replacement. However, there was a problem that it was very time-consuming. Further, the horizontal partition plate 101 has a structure in which the heat exchanger shell 100 is screwed to the heat exchanger shell 100 through the packing 104 at the peripheral edge, but has a large area that covers substantially the entire inner side of the heat exchanger shell 100 and is relatively Since it is a thin plate body, sealing failure due to bending or distortion is likely to occur, and there are many concerns that the peripheral portion may be deformed due to the attachment / detachment operation at the time of inspection, leading to sealing failure.

  In view of the above-described circumstances, the present invention has excellent acid corrosion resistance, and high-temperature combustion exhaust gas containing sulfurous acid gas and sulfuric acid gas is used as a heat exchange target, and high heat exchange efficiency is obtained over a long period of time. The object is to provide a heat exchanger for exhaust gas that can be inspected, repaired, and replaced very easily and efficiently and that is structurally simple.

  If the means for achieving the above object is shown with reference numerals in the drawings, the heat exchanger for exhaust gas according to the invention of claim 1 is arranged on the ceiling portion of the exhaust gas duct 10 in which the combustion exhaust gas flows in the lateral direction. A heat exchanger shell 1 and a large number of heat transfer tubes 2 hanging from the heat exchanger shell 1 are provided. The heat exchanger shell 1 is composed of a lid plate 11 with a detachable ceiling, and the interior is partitioned. The wall 12 is divided into a plurality of compartments 13 and 14 and includes an inlet header 31 facing the upstreammost compartment 13 and an outlet header 32 facing the downstreammost compartment 14, and an adjacent upstream compartment 13. A water pipe 4 is connected to each of the downstream compartments 14 via connection headers 33 and 34, and the heat transfer pipe 2 is a metal pipe whose outer surface is coated with a fluororesin 51 and whose lower end is closed ( Stainless steel pipe 20) The outer tube 21 and the inner tube 22 made of a fluororesin flexible tube that is inserted into the outer tube 21 and has an open lower end form a double tube. A group corresponding to each of the outlet header 32 and the connection headers 33 and 34 is configured, and the outer tube 21 of each heat transfer tube 2 is hermetically inserted into the mounting hole 15a provided in the bottom wall 15 of the compartments 13 and 14 at the upper end. The header 31 is fitted and fixed so that the inside communicates with the compartments 13 and 14, and the upper side of the inner tube 22 of the heat transfer tube 2 extends into the compartments 13 and 14 to be assembled for each group. To the outlet header 32 through the respective compartments 13 and 14 of the heat exchanger shell 1 while reciprocating in the double tubular heat transfer tubes 2. , High-temperature combustion flowing in the exhaust gas duct 10 With gas and exchanges heat derived as hot W2 from the outlet header 32, it is configured to low temperature flue gas by heat exchange.

  According to a second aspect of the present invention, in the exhaust gas heat exchanger of the first aspect, the partition plate 6 is interposed between the inner space 30 of each of the headers 31 to 34 and the compartments 13 and 14, and is provided on the partition plate 6. The upper end portion of each inner tube 22 in the heat transfer tube 2 is inserted into the mounting hole 6a, and this inserted portion is welded 53 with a thermoplastic fluororesin.

  According to a third aspect of the present invention, in the heat exchanger for exhaust gas according to the first or second aspect, the inside of the heat exchanger shell 1 is divided into two sections, an upstream compartment 13 and a downstream compartment 14, and the side wall of the upstream compartment 13 An inlet header 31 and a connection header 33 on one end side of the water conduit 4 are provided in the portion 13a, and an outlet header 32 and a connection header 34 on the other end side of the water conduit 4 are provided on the side wall portion 14a of the downstream compartment 14. It is supposed to be made.

  According to a fourth aspect of the present invention, in the exhaust gas heat exchanger according to any one of the first to third aspects of the present invention, the cleaning water is washed with respect to the heat transfer tube 2 upstream of the arrangement portion of the heat transfer tube 2 in the exhaust gas duct 10. A cleaning water nozzle 8 for injecting W3 is provided, and a water reservoir 10a is provided below the arrangement portion of the heat transfer tube 2, and the lower ends of the heat transfer tubes 2 are contained in the cleaning water W4 collected in the water reservoir 10a. It is assumed that the part is immersed.

  Next, effects of the present invention will be described with reference numerals in the drawings. First, in the exhaust gas heat exchanger according to the first aspect of the present invention, each of the double tubular heat transfer tubes 2 hanging from the heat exchanger shell 1 into the exhaust gas duct 10 has an outer tube 21 coated with a fluorine resin on the outer surface. 51, and the inner tube 22 is made of a fluororesin flexible tube. Therefore, it has excellent acid corrosion resistance, and heat exchange is performed on high-temperature combustion exhaust gas containing sulfurous acid gas and sulfuric acid gas. As a result, high heat exchange efficiency can be obtained over a long period of time. In addition, the heat transfer tubes 2 communicate with the inlet header 31 and the outlet header 32 and the connection headers 33 and 34 in a group of a plurality of inner tubes 22, while the outer tubes 21 of the heat transfer tubes 2 are connected to each other. At the upper end, it is inserted and fixed to the bottom wall 15 of the compartments 13 and 14, and the interior communicates with the compartments 13 and 14, so that when inspecting the heat transfer tube 2, it forms the ceiling part of the heat exchanger shell 1. By simply removing the cover plate 11, the fastening portions of the outer tube 21 and the inner tube 22 are exposed. Accordingly, by pulling out each inner tube 22 from the outer tube 21, the state of the inner and outer tubes 22, 21 can be easily confirmed visually, and defects such as breakage and deterioration are found in the inner and outer tubes 22, 21. Repair and replacement work can be done easily and efficiently. Further, the heat exchanger shell 1 itself has an advantage that it is structurally simple and can be manufactured at low cost because the inside is only divided into the plurality of compartments 13 and 14 by the partition wall 12.

  According to the invention of claim 2, the inner pipe 22 group corresponding to each header 31 to 34 is integrated with the partition plate 6 interposed between the inner space 30 of each header 31 to 34 and the compartments 13 and 14. Therefore, at the time of the inspection, by pulling the partition plate 6, the inner tube 22 group can be pulled out from each outer tube 21 at a stroke, so that the workability is improved and the upper end of each inner tube 22 is Since the partition plate 6 is welded 53 with thermoplastic fluororesin, the inner tube 22 can be easily replaced by heating and melting the welded portion.

  According to the invention of claim 3, the inside of the heat exchanger shell 1 is divided into the upstream compartment 13 and the downstream compartment 14, and the inlet header 31, the outlet header, and the connection headers 33 on both sides of the water conduit 4, 34 is provided in the side wall portions 13a and 14a of both the compartments 13 and 14, and the cold water W1 introduced into the inlet header 31 reciprocates in the heat transfer pipe 2 in each of the regions Z1 to Z4 corresponding to the headers 31 to 34, and the exhaust gas. Since the inside of the duct 10 is reciprocated four times and led out as the hot water W2 from the outlet header 32, it is simple and functional as an exhaust gas heat exchanger, and high heat exchange efficiency is obtained.

  According to the fourth aspect of the present invention, the dust adhering to the surface of the heat transfer tube 2 is washed away by the cleaning water W3 sprayed from the cleaning water nozzle 8, thereby preventing the heat exchange efficiency from being lowered, and the heat transfer tube 2 Since the lower end of each heat transfer tube 2 is immersed in the wash water W4 accumulated in the water reservoir 10a below the arrangement portion, boiling in the heat transfer tube 2 is prevented, and the heat transfer tube 2 accompanying the boiling of the heat transfer tube 2 is prevented. It is possible to avoid the destruction of the coating layer 51 of the fluororesin on the surface due to expansion.

It is a schematic longitudinal cross-sectional side view which shows typically the installation state of the heat exchanger for waste gas which concerns on one Embodiment of this invention. It is a cross-sectional plan view of the heat exchanger shell of the exhaust gas heat exchanger. It is a temperature operation diagram of the heat exchanger for exhaust gas. It is a longitudinal cross-sectional view which shows the fixation part of the outer tube | pipe of the heat exchanger tube in the heat exchanger shell of the heat exchanger for exhaust gas. It is a cross-sectional top view which shows the fixation part of the inner tube | pipe of the heat exchanger tube in the heat exchanger shell of the heat exchanger for exhaust gas. It is a general | schematic longitudinal cross-sectional side view which shows typically the installation state of the conventional heat exchanger for waste gas. It is a longitudinal cross-sectional view which shows the fixation part of the heat exchanger tube in the heat exchanger shell of the heat exchanger for exhaust gas. It is a temperature operation diagram of the heat exchanger for exhaust gas.

  Hereinafter, an exhaust gas heat exchanger according to an embodiment of the present invention will be specifically described with reference to the drawings.

  As shown in FIG. 1, the exhaust gas heat exchanger has a heat exchanger shell 1 made of carbon steel disposed on a ceiling portion of an exhaust gas duct 10 in which combustion exhaust gas flows in a lateral direction. A large number (several hundreds) of the heat transfer tubes 2 are suspended in the exhaust gas duct 10. The heat exchanger shell 1 is composed of a lid plate 11 with a detachable ceiling portion, and the interior is divided into an upstream compartment 13 and a downstream compartment 14 by a partition wall 12. The upstream side compartment 13 is provided with an inlet header 31 for introducing cold water W1 such as tap water, and the downstream side compartment 14 is provided with an outlet header 32 for deriving hot water W2 after heat exchange. , 14 is connected to a water conduit 4 arranged outside the heat exchanger shell 1. Each heat transfer tube 2 includes an outer tube 21 having an upper end fixed to a bottom wall 15 that forms a seal plate of the heat exchanger shell 1, and an inner tube 22 made of a flexible tube inserted into the outer tube 21. It has a double tube configuration.

  A cleaning water nozzle 8 for injecting the cleaning water W3 to the heat transfer tube 2 is disposed upstream of the heat transfer tube 2 arrangement portion in the exhaust gas duct 10, and the heat transfer tube 2 arrangement portion. A water reservoir 10a having a flat bottom is provided below the lower end of the heat transfer tube 2. The lower end of each heat transfer tube 2 is immersed in the cleaning water W4 accumulated in the water reservoir 10a.

  As shown in FIG. 2, the inlet header 31 and the outlet header 32 are provided in the side wall portions 13 a and 14 a of both the branch chambers 13 and 14, and both end portions of the water conduit 4 are the side wall portions 13 a and 14 a of both the branch chambers 13 and 14. Are attached via connection headers 33 and 34, respectively. The plurality of heat transfer tubes 2 constitute four groups, each of which corresponds to the inlet header 31, the outlet header 32, and the connection headers 33 and 34, and the upper portion of the inner tube 22 of each group. The side extends from the outer tube 21 into the two compartments 13 and 14 and is gathered and connected to each of the corresponding headers 31 to 34. In FIG. 2, a part of the multiple heat transfer tubes 2 is illustrated so that the arrangement of the heat transfer tubes 2 and the assembled state of the inner tubes 22 can be easily understood, and the other heat transfer tubes 2 are only positioned (+ ) Symbol. Further, the actual number of the heat transfer tubes 2 is several times as shown in FIG.

  As shown in detail in FIGS. 4 and 5, the outer tube 21 of each heat transfer tube 2 is obtained by coating the outer surface of the stainless steel pipe 20 with a coating 51 of a fluorine-based resin PFA, and the lower end of which is not illustrated is fluorine. It is closed by fusing the stopper of the resin PFA, welding the stainless steel end plate, etc., and the open upper end side is inserted into the locking hole 15a of the bottom wall 15 of the heat exchanger shell 1, and the insertion portion The middle and lower portions are enlarged in diameter 21 a and the upper peripheral edge of the stainless steel pipe 20 is welded 7 to be fixed to the bottom wall 15. In addition, an annular recess 15 b that allows an enlarged diameter 21 a of the outer tube 21 is formed on the inner periphery of the locking hole 15 a of the bottom wall 15.

  On the other hand, the inner tube 22 of each heat transfer tube 2 is made of a flexible tube made of fluororesin FEP, and both upper and lower ends are open, and each upper end portion extending into the compartments 13 and 14 has headers 31 to 34. The inner space 30 and the compartments 13 and 14 are inserted into the mounting holes 6a of the partition plate 6, and the outer peripheral portion of the tip is fixed to the partition plate 6 by resin welding 53 using a fluororesin PFA. The surface of the gas contact portion of the heat exchanger shell 1 including the bottom surface of the bottom wall 15 is coated with a fluorine resin PFA coating 52.

  As shown in FIG. 5, the partition plate 6 is made of a stainless steel plate having a fluorine resin PFA coating 54 on the surface thereof, and an opening 1 a provided in the side wall portions 13 a and 14 a of the heat exchanger shell 1. The peripheral portion is clamped between the annular reinforcing plate 17 fixed to the outer peripheral edge of the plate and the peripheral flange portion 35a of the cup member 35 of each header 31 to 34, and the opening is secured by bolting the clamped portion. The unit 1a is detachably attached.

  In the exhaust gas heat exchanger configured as described above, as shown in FIG. 2, the heat exchange part is divided into four regions Z1 to Z4 from the inlet side to the outlet side, and cold water introduced into the inlet header 31 is formed. W1 distributes and flows into the inner pipe 22 of each heat transfer pipe 2 connected to the inlet header 31 in the region Z1 on the inlet header 31 side half in the upstream side compartment 13 and flows out from the lower end of the outer pipe 21. The inside rises and flows into the upstream compartment 13. Next, in the region Z2 on the connection header 33 side half of the upstream side chamber 13, it flows into the outer tube 21 of each heat transfer tube 2, flows into the inner tube 22 from the lower end inside, and rises. It flows into the connection header 33 through the pipe 22 and is led out to the water conduit 4. Subsequently, in the area Z3 on the side of the connection header 34 in the downstream side compartment 14, it flows into the inner pipe 22 of each heat transfer pipe 2 connected from the connection header 34 through the water conduit 4, and flows out from its lower end. As a result, the inside of the outer tube 21 rises and flows into the downstream compartment 14. Further, in the region Z4 on the outlet header 32 side half portion of the downstream side compartment 14, it distributes and flows into the outer pipe 21 of each heat transfer pipe 2, flows into the inner pipe 22 from the lower end inside thereof, rises, It flows into the outlet header 32 through the tube 22.

  In other words, the cold water W1 introduced into the inlet header 31 reciprocates once in the heat transfer tube 2 in each of the four regions Z1 to Z4 and exchanges heat with the high-temperature exhaust gas G1 in the process of reciprocating four times in the exhaust gas duct 10 in total. Thus, the heated water W2 having been heated is led out from the outlet header 32. In addition, FIG. 3 has shown the operating line of heat exchange, and while the introduced cold water W1 goes through each area | region Z1-Z4 sequentially, it heats up in steps and derives as hot water W2, while high temperature exhaust gas G1 is On the other hand, the temperature is continuously lowered by passing through the region Z4 → Z1, and moves to the downstream side as the low temperature exhaust gas G2.

  In addition, as shown in FIG. 1, the washing water nozzle 8 disposed in the exhaust gas duct 10 flushes the dust adhering to the surface of the heat transfer tube 2 by the jetting of the washing water W3, and thereby heat exchange caused by the adhering dust. This prevents a decrease in efficiency. Accordingly, the cleaning water W4 containing the dust after the cleaning is accumulated in the water reservoir 10a below the arrangement portion of the heat transfer tube 2, and the excess amount is discharged through the overflow pipe 9, but the accumulated cleaning is performed. Since the lower ends of the heat transfer tubes 2 are immersed in the water W4, boiling in the heat transfer tubes 2 is prevented, and the coating layer 51 of the fluororesin on the surface is formed by expansion of the heat transfer tubes 2 accompanying the boiling. You can avoid being destroyed.

  According to such a heat exchanger for exhaust gas, each double-tubular heat transfer tube 2 is coated with a fluororesin coating 51 on the outer surface of the outer tube 21, and the inner tube 22 is a flexible tube made of a fluororesin. In addition, since the gas contact surface of the heat exchanger shell 1 is also coated with a fluorine-based resin coating 51, it has excellent acid corrosion resistance, and a high-temperature combustion exhaust gas G1 containing sulfurous acid gas and sulfuric acid gas is provided. As a heat exchange target, high heat exchange efficiency can be obtained over a long period of time. In addition, when the heat transfer tubes 2 are inspected, the fixing portions of the outer tube 21 and the inner tube 22 are exposed only by removing the cover plate 11 that forms the ceiling of the heat exchanger shell 1. By pulling out from the tube 21, the state of the inner and outer tubes 22, 21 can be easily confirmed visually, and repair and replacement work is easily performed when defects such as breakage or deterioration are found in the inner and outer tubes 22, 21. Can be done efficiently. Further, since the heat exchanger shell 1 itself is only divided into the upstream compartment 13 and the downstream compartment 14 by the partition wall 12, it is structurally simple and can be manufactured at low cost. There is.

  In the configuration of the embodiment, the inner pipe 22 group corresponding to each header 31 to 34 is integrated with the partition plate 6 interposed between the inner space 30 of each header 31 to 34 and the compartments 13 and 14. Therefore, at the time of the inspection, the inner pipe 22 group can be pulled out from each outer pipe 21 at a stroke by pulling the partition plate 6, and the workability is improved accordingly, and the upper end portion of each inner pipe 22 is connected to the partition. Since the plate 6 is welded 53 with thermoplastic fluororesin, the inner tube 22 can be easily replaced by heating and melting the welded portion.

  The exhaust gas heat exchanger of the present invention is not limited to the configuration in which the heat exchanger shell 1 is divided into two sections, that is, the upstream compartment 13 and the downstream compartment 14 as in the embodiment. The upstream compartment and the downstream compartment may be connected by a water conduit 4 via a connection header. However, the configuration divided into two sections as in the embodiment has an advantage that it is simple and functional as a heat exchanger for exhaust gas, and high heat exchange efficiency can be obtained. In the present invention, the heat exchanger shell 1 and the multiple heat transfer tubes 2 depending from the heat exchanger shell 1 are used as a heat exchange unit, and the plurality of units are arranged in parallel according to the size of the exhaust gas duct 10 and the amount of passing gas. Also good.

  In addition, in the heat exchanger for exhaust gas of the present invention, the shape of the heat exchanger shell 1, the mounting positions of the inlet and outlet headers 31 and 32 and the connection headers 33 and 34 with respect to the heat exchanger shell 1, The structure, the number and arrangement of the heat transfer tubes 2, the fastening structure of the outer tube 21 and the inner tube 22 of the heat transfer tube 2, the type of thermoplastic fluororesin used for the coatings 51 and 52, etc. Various design changes are possible.

DESCRIPTION OF SYMBOLS 1 Heat exchanger shell 11 Cover plate 12 Partition wall 13 Upstream side compartment 13a Side wall part 14 Downstream side compartment 14a Side wall part 15 Bottom wall 15a Mounting hole 2 Heat transfer tube 20 Stainless steel pipe (metal pipe)
21 Outer pipe 22 Inner pipe 31 Inlet header 32 Outlet header 33, 34 Connection header 4 Water conduit 51 Coating 53 Welding 6 Partition plate 6a Mounting hole 10 Exhaust gas duct 10a Water reservoir G1 High temperature exhaust gas G2 Low temperature exhaust gas W1 Cold water W2 Hot water W3, W4 Wash water

Claims (4)

A heat exchanger shell disposed on a ceiling portion of an exhaust gas duct in which combustion exhaust gas flows laterally, and a plurality of heat transfer tubes hanging from the heat exchanger shell,
The heat exchanger shell is composed of a cover plate with a detachable ceiling, and the interior is divided into a plurality of compartments by a partition wall, and faces an inlet header facing the most upstream compartment and a most downstream compartment. An outlet header, and a water conduit is connected between each of the adjacent upstream and downstream compartments via a connection header,
The heat transfer tube is composed of an outer tube made of a metal pipe whose outer surface is coated with a fluorine resin and closed at the lower end, and an inner tube made of a fluorine resin flexible tube inserted into the outer tube and having the lower end opened. A pipe and a double tube, each of which constitutes a group corresponding to each of the inlet header and outlet header and each connection header;
The outer tube of each heat transfer tube is hermetically inserted and fixed in a mounting hole provided in the bottom wall of the compartment, and the inside communicates with the compartment.
The inner pipe of the heat transfer pipe has an upper side extending into the branch chamber and is assembled for each group and communicates with a corresponding header,
The cold water introduced from the inlet header exchanges heat with the high-temperature combustion exhaust gas flowing in the exhaust gas duct in the process of reciprocating in each double-tube heat transfer tube and passing through each compartment of the heat exchanger shell to the outlet header. Then, the exhaust gas heat exchanger is configured to be led out as hot water from the outlet header and to reduce the temperature of the combustion exhaust gas by the heat exchange.   A partition plate is interposed between the inner space of each header and the compartment, and an upper end portion of each inner tube in the heat transfer tube is inserted into a mounting hole provided in the partition plate, and this insertion portion is thermoplastic. The heat exchanger for exhaust gas according to claim 1, which is welded with a fluorine-based resin.   The inside of the heat exchanger shell is divided into an upstream compartment and a downstream compartment, and the inlet header and a connection header on one end side of the water conduit are provided on the side wall of the upstream compartment, and the downstream compartment The heat exchanger for exhaust gas according to claim 1 or 2, wherein a connection header on the other end side of the outlet header and the water conduit is provided on a side wall portion of the exhaust gas.   A cleaning water nozzle for injecting cleaning water to the heat transfer tube is disposed upstream of the heat transfer tube arrangement portion in the exhaust gas duct, and a water reservoir is provided below the heat transfer tube arrangement portion. The exhaust gas heat exchanger according to any one of claims 1 to 3, wherein a lower end portion of each heat transfer tube is immersed in the wash water provided and stored in the water reservoir.

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