JP2008039227A - Air preheater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air preheater capable of avoiding damage or the like of a body by reducing thermal stress generated in the body when starting an energy system such as a gas turbine and a high temperature fuel cell. <P>SOLUTION: In this air preheater composed by laminating and arranging an exhaust gas passage circulating exhaust gas for heating, and an air passage forming a heat exchanging channel distributing air supplied from a direction orthogonal to the exhaust gas passage by an inlet side distributor to flow it parallel to exhaust gas and distributing heat-exchanged air by an outlet side distributor to deliver it in a direction orthogonal to the exhaust gas passage, the inlet side distributor 11 or the outlet side distributor 12 is laminated and arranged in a position separated from the inlet end of the exhaust gas passage at a predetermined distance in an exhaust gas flow direction. Thereby, steep temperature gradients can be avoided occurring in a stiffened corner part, the inlet end of the exhaust gas passage and an outlet side header tank, and thermal stress can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air preheater used in an energy system such as a gas turbine or a high-temperature fuel cell. More specifically, the present invention relates to damage to the body by reducing thermal stress generated in the body when the energy system is activated. The present invention relates to an air preheater that can prevent deformation and maintain excellent heat exchange efficiency.

  In recent years, a distributed energy system has been considered promising as an energy system replacing a large power generation system from the viewpoint of effective use of energy. Distributed energy systems include a variety of distributed energy conversion technologies such as gas engines, solar cells, and wind turbines. Among them, heat engines such as gas turbines and high-temperature types that generate electricity directly from fuel through chemical processes. Fuel cells are actively being developed.

  Examples of the high-temperature fuel cell include a solid oxide fuel cell (hereinafter referred to as “SOFC”) and a molten carbonate fuel cell (hereinafter referred to as “MCFC”). It is done. In addition, a hybrid system in which a gas turbine and a high-temperature fuel cell are combined is intended for use as a distributed power source, and is being studied for its realization.

  Since gas turbines and high-temperature fuel cells are characterized by a high temperature of exhaust gas, in order to improve thermal efficiency, a regeneration cycle that heats air using exhaust heat of exhaust gas is often adopted. . In these distributed energy systems, exhaust heat recovery performance greatly affects the performance of gas turbines and high-temperature fuel cells. Use of a regenerative heat exchanger is essential.

  An air preheater is used as a regenerative heat exchanger in a high-temperature fuel cell having a high operating temperature such as SOFC or MCFC or a gas turbine. An air preheater is a heat exchange device that recovers exhaust heat from the exhaust gas for the purpose of increasing thermal efficiency and preheats combustion air, for example, a tube type (tubular type), a plate type (plate type) Type), rotary regeneration type, etc.

  As a plate-type air preheater, a plate fin heat exchanger using corrugated fins has become the mainstream. The plate fin heat exchanger is composed of very dense parts and has a high heat transfer area per unit volume.

  In addition, since gas turbines and high-temperature fuel cells are repeatedly started and stopped, it is required to employ an air preheater having high durability against a temperature cycle.

  As a means for extending the product life of the air preheater against thermal stress, Patent Document 1 discloses a protection device for a preheating heat exchanger. This preheat heat exchanger protection device bypasses the air preheater and directs it to the double-pipe heat exchanger to exchange heat with the high temperature side of the air preheater. The temperature difference on the side is reduced to reduce thermal fatigue. However, the invention described in Patent Document 1 has a problem that equipment such as a double pipe heat exchanger and a bypass pipe must be installed in addition to the air preheater, which requires equipment costs.

  Further, in Patent Document 2, in a plate fin type heat exchanger, for example, high-temperature combustion gas flows in by separating each fin in the high-temperature side passage independently without brazing the whole fin in the high-temperature side passage. There has been proposed a configuration that can alleviate thermal stress due to non-uniform temperature distribution in the fluid passage and the whole, that is, a so-called flexible structure. If the structure proposed in Patent Document 2 is adopted, the thermal stress in the fluid passage and the whole can be relaxed by reducing the number of restraint points in the heat exchanger.

  In this way, the air preheater used for heat exchange between exhaust gas and air has durability that can withstand uneven temperature distribution in the fluid passage caused by sudden heat input and severe fluctuations in heat load. It is required to maintain heat exchange efficiency while holding.

Japanese Patent Laid-Open No. 05-105402 WO01 / 48432 A1 publication

  As described above, the air preheater is required to realize excellent heat exchange efficiency.

  1A and 1B are diagrams schematically showing an example of a conventional air preheater, in which FIG. 1A is a plan view showing an exhaust gas passage, and FIG. 1B is a plan view showing an air passage. In the air preheater shown in FIG. 1, the high-temperature exhaust gas passes through the inlet end 5 of the exhaust gas passage and flows into the exhaust gas passage 9 from the direction indicated by the black arrow 1. On the other hand, the low-temperature air passes through the inlet header tank 7 from the direction indicated by the white arrow 3, is distributed in a direction countercurrent to the exhaust gas via the inlet distributor 11, and flows into the air passage 10. . The high temperature exhaust gas and the low temperature air exchange heat with each other, the cooled exhaust gas passes through the outlet end 6 of the exhaust gas passage, flows out in the direction indicated by the white arrow 2, and the heated air is discharged from the outlet distributor. 12 passes through the outlet header tank 8 and flows out in the direction indicated by the black arrow 4.

  In the conventional air preheater, as shown in FIG. 1, in order to maximize the heat exchange efficiency, in order to increase the contact area between the high temperature fluid and the low temperature fluid, the exhaust gas passage 9 and the air of the same size are used. It is common to adopt a device configuration in which the passages 10 are stacked and arranged so that the outlet distributor 12 is positioned at the inlet end 5 of the exhaust gas passage through which high-temperature exhaust gas flows.

  Furthermore, in order to secure structural strength and increase the heat exchange area and improve the exchange efficiency, a laminated structure by brazing is adopted, so a normal air preheater has a so-called rigid structure. Adopted a characteristic configuration.

  When the air preheater is configured as described above, the heat of the high temperature fluid can be efficiently conducted to the low temperature fluid. However, when the exhaust gas having the highest temperature and the low-temperature air come into contact with each other through the plate, a large temperature gradient is generated in the corner portion 13 having a rigid structure, the inlet end 5 of the exhaust gas passage, and the outlet header tank 8. There's a problem.

  As described above, when a temperature change occurs due to the restraint of the container, or when a temperature change occurs in a container in which members having different thermal expansion coefficients are combined, the expansion and contraction of the container becomes uneven. As a result, thermal stress is generated in the body, and as a result, the air preheater may be deformed or damaged.

  The present invention has been made in view of the above problems, and by reducing the thermal stress generated in the body at the start-up of an energy system such as a gas turbine or a high-temperature fuel cell, damage and deformation of the body are reduced. An object of the present invention is to provide an air preheater capable of preventing and maintaining excellent heat exchange efficiency.

  The present inventors have studied various structures in an air preheater that can alleviate thermal stress due to uneven temperature distribution in the exhaust gas passage when high-temperature exhaust gas flows.

  First, in order to grasp the temperature distribution inside the air preheater at the time of starting the energy system, the present inventors conducted a heating test using the heat exchanger to be tested as a test body, and the air preheater by rapid heating The impact on As the test body, a heat exchanger having a configuration in which an air passage in which corrugated fins are arranged and an exhaust gas passage is laminated is used. Hereinafter, the length of the exhaust gas passage from the inlet end to the outlet end (hereinafter also referred to as “the length of the heat exchanger”) will be denoted as L, and the heating test will be described.

  An electric furnace was used for the heating test, and the prepared specimen was heated from the furnace heater and from the direction of the exhaust gas inlet, and rapidly heated to 800 ° C. In order to investigate the temperature distribution in the length direction of the test body during the heating test, the inlet end of the exhaust gas passage, the position of the length L / 4 from the inlet end, and the position of the length L / 2 from the inlet end (center Part) was measured with a thermocouple.

  FIG. 2 is a diagram showing the relationship between the distance from the inlet end of the exhaust gas passage of the heat exchanger and the temperature ratio based on the temperature of the inlet end. As shown in FIG. 2, the temperature of the entire specimen becomes substantially constant as the temperature at the inlet end of the exhaust gas passage rises, that is, the temperature ratio of the center of the specimen based on the inlet end temperature. Has been confirmed to approach 100%. Further, it has been found that in the temperature rising stage where the temperature at the inlet end of the exhaust gas passage is 500 ° C. or 700 ° C., a temperature drop of 20 to 30% occurs in the central portion as compared with the inlet end.

  Moreover, the temperature gradient increases as the distance from the inlet end of the exhaust gas passage increases, and it has been confirmed that a temperature drop of about 10% occurs in the portion of the temperature rising stage at a distance of L / 6 from the inlet end of the exhaust gas passage. .

  From the above test results, the present inventors have moved the outlet distributor of the low temperature fluid passage in the exhaust gas flow direction, thereby reducing the temperature difference between the high temperature side and the low temperature side of the air preheater, resulting in a large temperature gradient. It was found that the thermal stress generated in the corner portion, the exhaust gas inlet end, and the outlet header tank, which are rigid structures, can be effectively reduced. Furthermore, in order not to generate a large temperature gradient in the corner portion and the outlet header tank which are rigid structures, by moving the end of the air passage where the outlet distributor is arranged from the end of the exhaust gas passage in the air discharge direction, That is, it has been found that the thermal stress can be reduced by adopting a structure in which the high temperature fluid does not flow in the corner portion and the outlet header tank.

The present invention has been completed on the basis of the above findings, and the gist of the present invention is the air preheater described in (1) to (6) below.
(1) An exhaust gas passage through which exhaust gas for heating flows from the inlet end to the outlet end, and a heat exchange flow in which air supplied from a direction orthogonal to the exhaust gas passage is distributed by the inlet distributor to be parallel to the exhaust gas An air preheater having a structure in which a passage is formed and an air passage that distributes the heat-exchanged air by an outlet distributor and discharges the air in a direction orthogonal to the exhaust gas passage is disposed in the air passage. An air preheater, characterized in that a side distributor or an outlet distributor is stacked and disposed at a position spaced apart from the inlet end of the exhaust gas passage by a predetermined distance in the exhaust gas flow direction.
(2) In the air preheater described in (1) above, the parallel flow between the exhaust gas flowing through the body and the air is made countercurrent so that the temperature difference between the exhaust gas and air generated at the inlet end of the exhaust gas passage is reduced. It is desirable because it becomes smaller.
(3) In the air preheater described in (1) or (2) above, the separation distance is set to about L / 6 with respect to the length L from the inlet end to the outlet end of the exhaust gas passage. This is desirable because the temperature difference between the high temperature side and the low temperature side of the preheater can be reduced.
(4) An exhaust gas passage through which the exhaust gas for heating flows from the inlet end to the outlet end, and a heat exchange flow in which air supplied from a direction orthogonal to the exhaust gas passage is distributed by the inlet distributor to be parallel to the exhaust gas. An air preheater having a configuration in which a passage is formed and an air passage that distributes the heat-exchanged air by an outlet distributor and discharges the air in a direction perpendicular to the exhaust gas passage is disposed, and the inlet distributor is A position where the end of the arranged air passage is separated from the end of the exhaust gas passage by providing a predetermined distance in a direction opposite to the supply of air, or the end of the air passage where the outlet distributor is arranged, An air preheater, wherein the air preheater is stacked and disposed at a predetermined distance from the end of the exhaust gas passage in the air discharge direction.
(5) In the air preheater described in (4) above, the parallel flow of the exhaust gas flowing through the container and the air is made countercurrent so that the temperature difference between the exhaust gas and air generated at the inlet end of the exhaust gas passage is reduced. It is desirable because it becomes smaller.
(6) In the air preheater described in (4) or (5) above, it is generated by providing a separation distance of L / 6 or less with respect to the length L from the inlet end to the outlet end of the exhaust gas passage. This is desirable because the thermal stress can be reduced and the non-contact area between the high temperature fluid and the low temperature fluid can be reduced.

  The air preheater according to the present invention is configured by stacking the outlet distributor of the air passage with a separation distance from the inlet end of the exhaust gas passage in the exhaust gas flow direction, or the end of the air passage where the outlet distributor is arranged. Laminating and disposing the air exhaust from the end of the exhaust gas passage reduces the thermal stress generated in the air preheater and prevents damage and deformation of the airframe. Heat recovery can be performed.

  In addition, the air preheater of the present invention reduces the thermal stress generated in the vessel body by changing the arrangement of the outlet distributor and the like and preventing the occurrence of a large temperature gradient. Without requiring a complicated structure, high heat exchange efficiency and high durability can be realized under fluctuations in heat load.

  Hereinafter, an air preheater according to the present invention will be described in detail with reference to the drawings.

  FIG. 3 schematically shows an example of the counterflow type air preheater according to the present invention, in which the outlet distributor of the air passage is stacked and arranged with a separation distance from the inlet end of the exhaust passage in the exhaust gas flow direction. FIG. 2A is a plan view showing an exhaust gas passage, and FIG. 1B is a plan view showing an air passage. In the air preheater shown in FIG. 3, the high-temperature exhaust gas passes through the inlet end 5 of the exhaust gas passage from the direction indicated by the black arrow 1 and flows into the exhaust gas passage 9. On the other hand, the low-temperature air passes through the inlet header tank 7 from the direction indicated by the white arrow 3, is distributed in a direction countercurrent to the exhaust gas via the inlet distributor 11, and flows into the air passage 10. . The high temperature exhaust gas and the low temperature air exchange heat with each other, the cooled exhaust gas passes through the outlet end 6 of the exhaust gas passage, flows out in the direction indicated by the white arrow 2, and the heated air is discharged from the outlet distributor. 12 passes through the outlet header tank 8 and flows out in the direction indicated by the black arrow 4.

  At this time, the inlet end 5 of the exhaust gas passage has the highest temperature, but the outlet distributor 12 of the air passage is stacked and disposed at a position separated from the inlet end 5 of the exhaust passage by a predetermined distance l. It is possible to suppress the occurrence of a large temperature gradient at the inlet end 5 of the exhaust gas passage, the corner portion 13 and the outlet header tank 8. Thereby, the thermal stress which arises in the inlet end 5 of the exhaust gas passage which is a rigid structure, the corner part 13, and the exit side header tank 8 is reduced, and the failure | damage and deformation | transformation of an air preheater can be prevented.

  On the other hand, in the case of a co-flow type air preheater, the inlet header tank and the inlet distributor are arranged on the inlet side of the exhaust gas passage, unlike the counterflow type.

  FIG. 4 schematically shows an example of the co-current type air preheater according to the present invention in which the inlet distributor of the air passage is stacked and arranged with a separation distance from the inlet end of the exhaust passage in the exhaust gas flow direction. FIG. 2A is a plan view showing an exhaust gas passage, and FIG. 1B is a plan view showing an air passage. In the air preheater shown in FIG. 4, the low-temperature air supplied from the direction indicated by the hollow arrow 3 passes through the inlet header tank 7 and is distributed in the same direction as the exhaust gas flow via the inlet distributor 11. And flows into the air passage 10. The hot exhaust gas and the low temperature air exchange heat with each other as they flow toward the outlet end of the exhaust gas passage.

  In this way, the cooled exhaust gas passes through the outlet end 6 of the exhaust gas passage and flows out in the direction indicated by the hollow arrow 2, and the heated air passes through the outlet header tank 8 via the outlet distributor 12. And flows out in the direction indicated by the black arrow 4.

  At this time, the temperature at the inlet end 5 of the exhaust gas passage is highest, but the inlet distributor 11 of the air passage is stacked and disposed at a position separated from the inlet end 5 of the exhaust gas passage by a predetermined distance l. Since a large temperature gradient can be suppressed from occurring at the inlet end 5 of the exhaust gas passage, the corner portion 13 and the inlet header tank 7, the thermal stress generated in the rigid structure is reduced as in the counterflow type.

  In addition, as shown in FIG. 2, when rapid heating up to 800 ° C. is performed using an air preheater having a length L, in the temperature rising stage, L / 6 away from the inlet end of the exhaust gas passage. It was confirmed that a temperature drop of about 10% occurred in the part. Further, when the length L of the air preheater is extremely long, it is possible to effectively relieve the thermal stress even if the predetermined distance 1 is set to L / 6 or less, and the air preheater When the length L is extremely short, the predetermined distance l can be set to L / 6 or more as long as the heat exchange efficiency can be maintained.

  Therefore, depending on the heating conditions such as the size of the air preheater and the temperature of the exhaust gas, in the air preheater having the length L shown in FIG. 3, the outlet distributor 12 of the air passage is about L / 6 from the inlet end 5 of the exhaust gas passage. By laminating and disposing at distant positions, it is possible to greatly relieve thermal stress due to non-uniform temperature distribution.

  Furthermore, in the air preheater according to the present invention, it is desirable that the parallel flow of the exhaust gas flowing through the body and the air is countercurrent. The reason will be described below.

FIG. 5 is a diagram schematically showing a change in temperature when a high-temperature fluid and a low-temperature fluid flow in parallel inside the heat exchanger, and FIG. 5 (a) is a diagram showing a counter-current heat exchanger. FIG. 2B is a view showing a cocurrent type heat exchanger. ΔT ₁ in FIG. 5A is the difference between the temperature T ₁ of the high-temperature fluid before heat exchange and the temperature t _{2 of the} low-temperature fluid heated by heat exchange, and ΔT ₁ ′ in FIG. This is the difference between the temperature T ₁ of the hot fluid before exchange and the temperature t ₁ of the cold fluid before heat exchange. Therefore, at the inlet of the high-temperature fluid, the temperature difference ΔT ₁ of the countercurrent heat exchanger becomes smaller than the temperature difference ΔT ₁ ′ of the cocurrent flow heat exchanger.

  That is, by constructing the parallel flow of the exhaust gas flowing through the container and the air as a countercurrent, it is possible to prevent the occurrence of a large temperature gradient and to reduce the thermal stress generated in the air preheater. Because.

  FIG. 6 is a counterflow type air preheater according to the present invention, in which the end of the air passage in which the outlet distributor is arranged is stacked with a separation distance from the end of the exhaust gas passage in the air discharge direction. FIG. 2A is a plan view showing an exhaust gas passage, and FIG. 2B is a plan view showing an air passage. As shown in FIG. 6, the end of the air passage where the outlet distributor is arranged is stacked and disposed at a position separated from the end of the exhaust gas passage by a predetermined distance b in the air discharge direction. Therefore, the high temperature exhaust gas does not flow in the vicinity of the fluid passage corner portion 13 and the outlet header tank 8, and a large temperature gradient does not occur. Therefore, the thermal stress generated in the corner portion 13 and the outlet header tank 8 which are rigid structures is reduced. It can be effectively reduced.

  When a cocurrent air preheater is used, the end of the air passage provided with the inlet distributor is separated from the end of the exhaust gas passage by a predetermined distance in the direction opposite to the air supply. By adopting the device configuration in which the layers are stacked at the positions, the thermal stress generated in the corner portion and the inlet header tank having a rigid structure can be effectively reduced as in the case of the counterflow type.

  FIG. 7 is an air preheater according to the present invention in which the end portion of the air passage is stacked with a separation distance from the end portion of the exhaust gas passage in the air discharge direction, and the widths of the exhaust gas inlet and the exhaust gas outlet are different. It is a figure which shows an example of a case typically. In the present invention, in order not to cause a large temperature gradient in the corner portion 13 and the outlet header tank 8 having a rigid structure, the end portion of the air passage is provided with a separation distance b from the end portion of the exhaust gas passage in the air discharge direction. By disposing, thermal stress can be effectively reduced.

  Therefore, if the width of the exhaust gas inlet 14 is made to coincide with the width of the exhaust gas passage 9, it is also possible to adopt a structure in which the width of the exhaust gas outlet 15 is made to coincide with the width of the air passage as shown in FIG. Similarly to the exhaust gas inlet 14, it is possible to adopt a structure that matches the width of the exhaust gas passage 9. Thus, the width of the exhaust gas outlet 15 can be appropriately selected according to the enforcement conditions, equipment conditions, and the like.

  Further, in the air preheater shown in FIG. 3, the outlet distributor of the air passage is located at a position about L / 6 away from the inlet end of the exhaust gas passage based on the relationship between the distance from the inlet end of the exhaust gas passage and the temperature distribution. By arranging the layers, thermal stress can be effectively reduced. In contrast, the air preheater shown in FIGS. 6 and 7 reduces thermal stress by adopting a structure in which high-temperature exhaust gas does not flow in the vicinity of the fluid passage corner portion 13 and the outlet header tank 8. is there.

  Therefore, even if the separation distance in the air discharge direction between the end portion of the air passage and the end portion of the exhaust gas passage is smaller than the desired separation distance L / 6 of the air preheater shown in FIG. It is thought that the effect of reducing stress is exhibited. Therefore, in the air preheater having a length L shown in FIGS. 6 and 7, the end of the air passage provided with the outlet distributor is separated from the end of the exhaust gas passage by L / 6 or less in the air discharge direction. By stacking and arranging at the provided positions, it is possible to effectively reduce the thermal stress generated in the corner portion and the outlet header tank, and to reduce the non-contact area between the high temperature fluid and the low temperature fluid.

  FIG. 8 shows an air preheater according to the present invention, in which the outlet distributor of the air passage is separated from the inlet end of the exhaust passage by a predetermined distance in the exhaust gas flow direction, and the end of the air passage is separated from the exhaust passage. It is a top view which shows typically an example at the time of providing a predetermined distance from the edge part in the air discharge direction, and laminating | stacking in the position spaced apart. As shown in FIG. 8, if the movement of the outlet distributor 12 in the exhaust gas flow direction and the movement of the end of the air passage in the discharge direction of air are combined, the corner portion 13 of the air preheater, the exhaust gas inlet end 5 and the thermal stress generated in the outlet header tank 8 can be further reduced.

  The air preheater according to the present invention is configured by stacking the outlet distributor of the air passage with a separation distance from the inlet end of the exhaust gas passage in the exhaust gas flow direction, or the end of the air passage where the outlet distributor is arranged. Laminating and disposing the exhaust gas passage from the end of the exhaust gas passage in the air discharge direction reduces the thermal stress generated in the air preheater and prevents damage and deformation of the airframe. Heat recovery can be performed.

  In addition, the air preheater of the present invention reduces the thermal stress generated in the vessel body by changing the arrangement of the outlet distributor and the like and preventing the occurrence of a large temperature gradient. Without requiring a complicated structure, high heat exchange efficiency and high durability can be realized under fluctuations in heat load.

  Thereby, while being able to maintain the outstanding heat exchange efficiency, it can apply widely as an air preheater which can endure the fluctuation | variation of a heat load.

It is a figure which shows typically an example of the conventional air preheater, the same figure (a) is a top view which shows an exhaust gas channel | path, The same figure (b) is a top view which shows an air channel | path. It is a figure which shows the relationship between the distance from the entrance end of the exhaust gas passage of a heat exchanger, and the temperature ratio on the basis of the temperature of an entrance end. FIG. 2 is a diagram schematically showing an example of a counterflow type air preheater according to the present invention, in which an outlet distributor of an air passage is stacked and arranged with a separation distance in an exhaust gas flow direction from an inlet end of an exhaust gas passage; The figure (a) is a top view which shows an exhaust gas channel | path, The figure (b) is a top view which shows an air channel | path. It is a parallel flow type air preheater of the present invention, and is a diagram schematically showing an example of a case where the inlet distributor of the air passage is stacked and arranged with a separation distance in the exhaust gas flow direction from the inlet end of the exhaust passage, The figure (a) is a top view which shows an exhaust gas channel | path, The figure (b) is a top view which shows an air channel | path. It is a figure which shows typically the mode of a temperature change when a high temperature fluid and a low temperature fluid flow through the inside of a heat exchanger in parallel, The figure (a) is a figure which shows a countercurrent type heat exchanger, (B) is a figure which shows a parallel flow type heat exchanger. FIG. 1 is a schematic diagram illustrating an example of a counterflow type air preheater according to the present invention in which an end of an air passage in which an outlet distributor is arranged is stacked with a separation distance from an end of an exhaust gas passage in an air discharge direction. (A) is a plan view showing an exhaust gas passage, and (b) is a plan view showing an air passage. An air preheater according to the present invention in which an end portion of an air passage is stacked and arranged with a separation distance from an end portion of the exhaust gas passage in the air discharge direction, and an example in which the width of the exhaust gas inlet and the exhaust gas outlet is different It is a figure shown typically. In the air preheater of the present invention, the outlet distributor of the air passage is separated from the inlet end of the exhaust gas passage by a predetermined distance in the exhaust gas flow direction, and the end of the air passage is separated from the end of the exhaust passage. It is a top view which shows typically an example at the time of providing the predetermined distance in the discharge direction of this, and laminating | stacking in the position spaced apart.

Explanation of symbols

1. Direction of inflow of exhaust gas 2. Direction of outflow of exhaust gas 3. Air inflow direction 4. Air outflow direction 5. Inlet end of exhaust gas passage 6. Outlet end of exhaust gas passage Inlet side header tank 8． Outlet header tank 9. Exhaust gas passage 10. Air passage 11. Incoming distributor 12. Outgoing distributor 13. Fluid passage corner 14. Exhaust gas inlet 15. Exhaust gas outlet

Claims (6)

An exhaust gas passage through which the exhaust gas for heating flows from the inlet end to the outlet end, and a heat exchange passage that becomes parallel flow with the exhaust gas by distributing air supplied from a direction orthogonal to the exhaust gas passage with an inlet distributor In the air preheater having a configuration in which an air passage that distributes the heat-exchanged air by an outlet distributor and discharges the air in a direction orthogonal to the exhaust gas passage is laminated,
An air preheater, wherein an inlet distributor or an outlet distributor of the air passage is stacked and disposed at a position spaced apart from the inlet end of the exhaust passage by a predetermined distance in the exhaust gas flow direction.   The air preheater according to claim 1, wherein the parallel flow of the exhaust gas and air is a countercurrent.   The air preheater according to claim 1 or 2, wherein the separation distance is about L / 6 with respect to a length L from an inlet end to an outlet end of the exhaust gas passage. An exhaust gas passage through which the exhaust gas for heating flows from the inlet end to the outlet end, and a heat exchange passage that becomes parallel flow with the exhaust gas by distributing air supplied from a direction orthogonal to the exhaust gas passage with an inlet distributor In the air preheater having a configuration in which an air passage that distributes the heat-exchanged air by an outlet distributor and discharges the air in a direction orthogonal to the exhaust gas passage is laminated,
The position where the end of the air passage in which the inlet distributor is arranged is separated from the end of the exhaust gas passage by a predetermined distance in the direction opposite to the air supply, or the air passage in which the outlet distributor is arranged The air preheater is characterized by being stacked and disposed at a position spaced apart from the end of the exhaust gas passage by a predetermined distance in the air discharge direction.   The air preheater according to claim 4, wherein the parallel flow of the exhaust gas and air is a countercurrent. The air preheater according to claim 4 or 5, wherein the separation distance is L / 6 or less with respect to a length L from an inlet end to an outlet end of the exhaust gas passage.

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