JPH10148402A - Catalytic combustion heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalytic combustion heater with a safety and a higher heat exchange efficiency by properly adjusting a heating value by a catalytic reaction to prevent an abnormal rise in the temperature of a fin and a tube. SOLUTION: A heater exchanger with a catalyst which has a plurality of tubes 2 through which a fluid to be heated flows and a fin 21 which is joined on the outer circumference thereof and supports an oxidation catalyst is installed in a fuel gas passage 11 provided in a container 1. The ongoing direction of the fluid to be heated is made opposite to the direction of a fuel gas flows to enhance a heat exchange efficiency while the surface area of the fin 21 is made smaller on the upstream side of the fuel gas passage 11. Thus, the heating value on the upstream side is kept from increasing beyond the necessity thereof to prevent an abnormal rise in the temperature of the fin 21 or the like thereby achieving a higher safety.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic combustion heating apparatus which is used as a heat source of a heater for a home or an automobile and heats a fluid to be heated by utilizing heat of oxidation reaction of a fuel gas catalyst.

[0002]

2. Description of the Related Art There is known a catalytic combustion heating device that burns a combustible gas (fuel gas) using an oxidation catalyst and heats a fluid to be heated by using generated heat. It is expected to be used for various purposes. Such a catalytic combustion heating device usually includes a heat exchanger with a catalyst carrying an oxidation catalyst such as platinum or palladium on a large number of fins integrally joined to the outer periphery of a tube through which a liquid or a gas to be heated flows. The fuel gas is brought into contact with the large number of fins to cause an oxidation reaction.

FIG. 4 shows an example of a conventional catalytic combustion heating apparatus. In FIG. 4, a plurality of tubes 51 spanning between left and right side walls are joined in a vessel 5 and an oxidation catalyst is formed on the surface thereof. And a heat exchanger with a catalyst comprising a large number of fins 52 carrying the catalyst. The plurality of tubes 51 are connected at their left and right ends to form a continuous flow path of the fluid to be heated therein, and the upper end opening is an inlet for the heated fluid, and the lower end is an outlet for the heated fluid. The fluid to be heated flows from above to below in the figure.

[0004] A fuel gas supply port 53 is provided at the lower end of the container 5, and a fuel gas outlet 54 is provided at the upper end. Thus, the fuel gas flows between the fins 52 on the outer periphery of the tube 51 from the lower side to the upper side in the drawing, and comes into contact with the surface of the fins 52 carrying the oxidation catalyst and burns by a catalytic reaction. The heat generated by the combustion is transmitted to the fluid to be heated flowing inside the tube 51 via the wall of the tube 51, and the exhaust gas after the catalytic combustion is discharged to the outside of the container 5 from the discharge port 54. Note that a flow straightening plate 55 having a large number of through holes is disposed above the supply port 53 so as to cross the fuel gas flow path, and above it, the catalyst is heated to an activation temperature or higher. Heater 56 is provided.

[0005]

In the above-mentioned conventional catalytic combustion heating apparatus, the fuel gas flows in the vessel 5 while burning from the bottom to the top in the figure, and the concentration of the fuel gas is lower than the lower end of the vessel 5 near the supply port 53. Highest in. On the other hand, the fluid to be heated flows while increasing the temperature in the container 5 from above to below, and the temperature becomes highest at the lower end of the container 5. When the flow direction of the fuel gas and the traveling direction of the fluid to be heated are opposite to each other, the temperature of the fluid to be heated is low in the vicinity of the discharge port 54, so that the heat of the exhaust gas is transferred to the fluid to be heated at a lower temperature. Thus, the generated heat can be more effectively utilized.

However, near the outlet of the fluid to be heated,
That is, since the fuel gas having a high concentration is continuously supplied in the vicinity of the fuel gas supply port 53, the fins 52 carrying the catalyst and the tubes 51 through which the fluid to be heated flows become abnormally high.
There was a possibility that the catalytic combustion heating device was adversely affected.

[0007] The present invention has been made in view of the above circumstances,
The purpose is to properly adjust the amount of heat generated by the catalytic reaction,
It is an object of the present invention to provide a catalytic combustion heating device that prevents abnormal temperature rise of fins and tubes and is safe and has high heat exchange efficiency.

[0008]

According to a first aspect of the present invention, there is provided a catalytic combustion heating apparatus comprising: a container; a fuel gas passage formed in the container; And a heat exchanger with a catalyst having a plurality of tubes through which a fluid to be heated flows and having a fin carrying an oxidation catalyst which is joined to the outer periphery thereof and which comes into contact with fuel gas to generate an oxidation reaction. The moving direction of the fluid to be heated in the heat exchanger with catalyst is configured to be opposite to the flow direction of the fuel gas. The surface area of the fin differs depending on the installation position of the tube to be joined, and is small on the upstream side of the fuel gas flow path and large on the downstream side.

In the above configuration, since the surface area of the fin provided around the tube is reduced on the upstream side of the fuel gas flow path, the fuel gas concentration is high and the temperature of the fluid to be heated is high on the upstream side of the fuel gas flow path. The calorific value on the side does not become unnecessarily large, and abnormal heating of the fins and tubes can be prevented to enhance safety. On the other hand, on the downstream side of the fuel gas flow path, a sufficient calorific value is obtained because the surface area of the fin is large, and the temperature of the fluid to be heated is low on the downstream side of the fuel gas flow path. Utilization can improve heat exchange efficiency.

According to the second aspect of the present invention, the fins are not joined to the tube located on the upstream side of the fuel gas flow path, but instead, irregularities are formed on the outer surface of the tube to directly oxidize the irregular surface. The catalyst is supported. Specifically, as in the configuration of the third aspect, spiral, star-shaped, corrugated, or lattice-shaped irregularities are formed on the outer surface of the tube.

Since the surface area of the fin may be small on the upstream side of the fuel gas flow path, the outer surface area may be increased by forming irregularities instead of the fin. In this case, the temperature gradient between the outer surface of the tube, which is the heat generating part, and the fluid to be heated can be reduced, and the temperature can be controlled more safely and easily. In addition, since the heat stress of the heat exchange part is small, there is no fear of peeling of the catalyst or the like, and the production is easy.

In the configuration of the fourth aspect, the fin is provided in common for a plurality of the tubes. Since a plurality of tubes can be connected by one fin, assembly is easy and manufacturing cost can be reduced.

According to a fifth aspect of the present invention, the plurality of tubes are arranged in the fuel gas flow path in a layered manner in the flow direction of the fuel gas, and the tubes constituting each layer constitute a tube constituting an adjacent layer. To be staggered. Since the tubes are arranged alternately with respect to the flow direction of the fuel gas, the fuel gas flows while meandering along the outer periphery of the tube, and the contact with the fins increases.
The heat exchange efficiency can be improved, and the size of the catalytic combustion heating device in the flow direction of the fuel gas can be reduced.

According to the sixth aspect of the present invention, the interval between the plurality of fins joined to the tube is increased on the upstream side of the fuel gas flow path and reduced on the downstream side. Accordingly, excessive heat generation on the upstream side can be suppressed, and heat of the exhaust gas can be more effectively recovered on the downstream side. Further, the unburned gas fuel can be completely catalytically burned to prevent the unburned gas from being released together with the exhaust gas.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the catalytic combustion heating apparatus according to the present invention will be described below with reference to FIG. FIG. 1 (a)
In FIG. 2B, the inside of the cylindrical container 1 serves as a fuel gas flow path 11, and the fuel flows from a fuel supply port 12 provided at the left end in the drawing to an exhaust port 13 provided at the right end. The gas is made to flow. In the fuel gas passage 11,
A large number of tubes 2 through which a fluid to be heated flows are arranged in layers in the flow direction of the fuel gas (FIG. 1B).
In each layer, the tubes 2 are arranged in parallel in a direction orthogonal to the flow of the fuel gas, and a number of ring-shaped fins 21 carrying a catalyst on the surface are joined to the outer periphery of each tube 2 by brazing or the like. ing.

In the layer 2A of the tube 2 located on the most upstream side in the fuel gas flow channel 11, the fin 21
Has a smaller outer diameter than the fins 21 in the layers 2B to 2E of the tube 2 on the downstream side. Also,
In the layer 2A of the tube 2 on the most upstream side, the number of tubes is larger than that on the downstream side. This is because the liquid is changed to a gas, so that the pressure loss increases unless the total cross-sectional area is increased. In the downstream layers 2B to 2E, the fins 21 have the same shape, but the attachment intervals are narrower in the most downstream layers 2D and 2E than in the intermediate layers 2B and 2C. Further, in the downstream layers 2B to 2E, the tubes 2 are alternately arranged so as to be located between the tubes 2 of the adjacent layers. The outer diameter and the number of the fins 21 are appropriately set according to the amount of heat required for the fluid to be heated in the tube 2 to be joined.

The tube 2 constituting the uppermost stream layer 2A is:
They are connected by fluid reservoirs 31 and 32 provided at both ends (FIG. 1A). Similarly, the second layer 2B and the third layer 2C are connected to the fluid reservoirs 32 and 33, and the fourth layer 2D and the fifth layer 2E are connected to the fluid reservoirs 33 and 34. By connecting the lead-in path 42 to the fluid reservoir 31 with the introduction path 41, a flow path of the heated fluid from the downstream side to the upstream side of the fuel gas flow path 11 is formed as shown by the arrow in the figure. .

A temperature sensor 43 for controlling the outlet temperature of the fluid to be heated is provided on the pipe wall in the passage 42 for the fluid to be heated. The fuel gas flow path 1 near the fuel supply port 12
A rectifying plate having a large number of through-holes and a heater for heating the catalyst as shown in the above-described conventional configuration can be provided in the device 1.

Thus, in the fuel gas flow path 11, a heat exchange unit with a catalyst comprising the tube 2, the fins 21 on the outer periphery thereof, the fluid reservoirs 31 to 34, the introduction passage 41 and the exit passage 42 for the fluid to be heated is constituted. Then, the fuel gas supplied from the fuel supply port 12 into the fuel gas flow path 11 undergoes an oxidation reaction with the catalyst on the fins 21 in the heat exchange section with the catalyst, and travels toward the exhaust port 13 while performing catalytic combustion. Heat generated by the oxidation reaction is transmitted from the fins 21 to the tube 2 and heats the heated fluid flowing inside the tube.

Here, the flow direction of the fluid to be heated is opposite to the flow direction of the fuel gas, and the fluid to be heated is heated to a higher temperature toward the upstream side of the fuel gas flow path 11, The heated fluid flowing in the close tube 2 has the highest temperature. Therefore, the tube 2 and the fin 21
However, in the above configuration, since the surface area of the fin 21 located in the uppermost layer 2A of the fuel gas flow path 11 is smaller than the downstream layers 2B to 2E, the heat generation amount is appropriately controlled. , Does not become larger than necessary. Therefore, the fin 21 and the tube 2 do not become abnormally high in temperature, and stable catalytic combustion and heat exchange can be performed. Also,
By reducing the size of the fins 21 on the upstream side of the fuel gas flow path 11 where the temperature becomes high, deformation of the fins 21 due to thermal stress in the radial direction is suppressed, and a problem such as separation of the catalyst does not occur.

On the other hand, since the temperature of the fluid to be heated is lower on the downstream side of the fuel gas flow path 11, that is, closer to the exhaust port 13, the exhaust gas discharged from the exhaust port 13 flows through the tube 2 through which the lower temperature fluid flows. , The heat in the exhaust gas can be efficiently recovered. Further, since the tubes 2 are arranged alternately between adjacent layers, the fuel gas flow path 11
And the heat exchange efficiency is further improved, and the size of the catalytic combustion heating device in the flow direction of the fuel gas can be reduced. In addition, by reducing the mounting interval of the fins 21 located on the downstream side and increasing the contact area with the exhaust gas, the heat of the exhaust gas can be more effectively recovered, and the unburned gas fuel can be completely catalyzed. The exhaust gas can be purified by combustion.

In the above embodiment, the amount of heat generated is controlled by reducing the size of the fins 21 located in the uppermost stream layer 2A of the fuel gas flow path 11. However, as shown in FIG. Irregularities may be formed on the outer surface of the tube 2 constituting the layer 2A to directly support the catalyst. For example, the tube 2 has a spiral shape (FIG. 2A) according to the required heat amount,
By performing irregularities such as a star (FIG. 2B) and a waveform (FIG. 2C), the surface area can be easily increased, and a necessary catalyst carrying area can be secured. FIG.
As shown in (d), fine grid-like irregularities may be formed on the entire surface.

According to the above configuration, the thermal resistance from the end of the heat generating portion of the tube 2 to the inside of the tube 2 is reduced.
Since the temperature gradient in the radial direction of the tube 2 is reduced, the heat transfer to the fluid to be heated is favorably performed, and the catalytic combustion can be performed more safely. In addition, not only the tube 2 located in the uppermost stream layer 2A but also the layer in the vicinity of the tube 2A can control the heat generation amount to a desired value by forming irregularities on the outer surface or reducing the size of the fins 21 as necessary. Can be easily done.

Further, as shown in FIG.
May be provided in common for each layer of the tubes 2 arranged in layers. If the plurality of tubes 2 are connected by one fin 21 in this manner, the number of parts can be reduced and the assembling work is easy, so that the manufacturing cost can be reduced.

In each of the above embodiments, the catalytic combustion heating device is set horizontally, but may be set vertically.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment of the present invention, wherein FIG. 1A is an overall sectional view of a catalytic combustion heating device, and FIG.
It is Ib line sectional drawing.

FIG. 2 is a sectional view of a catalytic combustion heating device showing another example of a tube shape on the upstream side.

FIG. 3 is an overall sectional view of a catalytic combustion heating device according to a second embodiment of the present invention.

FIG. 4 is an overall sectional view of a conventional catalytic combustion heating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 11 Fuel gas flow path 12 Fuel gas supply port 13 Exhaust port 2 Tube 21 Fin 31-34 Fluid reservoir 41 Heated fluid introduction path 42 Heated fluid outlet path

Continued on the front page (72) Inventor Shoji Hirose 14 Iwatani, Shimowasumi-cho, Nishio-shi, Aichi Prefecture Inside Japan Automotive Parts Research Institute Co., Ltd.

Claims (6)

[Claims] 1. A container, a fuel gas flow passage formed in the container, a plurality of tubes disposed in the fuel gas flow passage, through which a fluid to be heated flows, and joined to the outer periphery of the tube and provided with a fuel A heat exchanger with a catalyst having fins carrying an oxidation catalyst that causes an oxidation reaction in contact with the gas, wherein the flow direction of the fluid to be heated in the heat exchanger with the catalyst is opposite to the flow direction of the fuel gas. Wherein the surface area of the fins is different depending on the installation position of the tube to be joined, and is smaller on the upstream side of the fuel gas flow path and larger on the downstream side. Heating equipment. 2. The method according to claim 1, wherein the fin is not joined to the tube located on the upstream side of the fuel gas flow path, but instead an irregularity is formed on the outer surface of the tube and the oxidation catalyst is directly supported on the irregularity surface. Item 2. A catalytic combustion heating device according to Item 1. 3. The catalytic combustion heating device according to claim 2, wherein spiral, star-shaped, corrugated or lattice-shaped irregularities are formed on the outer surface of the tube. 4. The catalytic combustion heating device according to claim 1, wherein said fin is provided in common for a plurality of said tubes. 5. The fuel gas flow path according to claim 1, wherein the plurality of tubes are arranged in layers in the fuel gas flow direction, and the tubes constituting each layer are alternately arranged with the tubes constituting adjacent layers. Item 5. The catalytic combustion heating device according to any one of Items 1 to 4. 6. The fuel gas flow path according to claim 1, wherein an attachment interval between the plurality of fins joined to the tube is large on an upstream side of the fuel gas flow path and small on a downstream side. A catalytic combustion heating device as described in the above.