JP3678855B2 - Catalytic combustion device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a catalytic combustion apparatus applied to domestic or commercial hot water supply and heating.
[0002]
[Prior art]
There has been proposed a catalytic combustion apparatus in which a catalyst body in which a noble metal catalyst such as platinum or palladium is supported on a carrier such as cordierite is catalytically combusted and a heat exchange part is provided to use the combustion heat for heating or the like (for example, Application No. 4-302347). A heat exchange unit is installed upstream of the mixture of honeycomb-shaped catalyst bodies to receive radiation from the catalyst bodies. At the start of catalytic combustion, the catalyst bodies are heated to a temperature higher than the activation temperature by burning with a preheating burner. After that, the supply of the air-fuel mixture was stopped, the flame of the preheating burner was extinguished, and the air-fuel mixture was supplied again to cause catalytic combustion.
[0003]
[Problems to be solved by the invention]
The conventional catalytic combustion apparatus has the following problems. First, since the combustion temperature is low in the catalytic combustion, when trying to increase the amount of heat exchange, the catalyst body becomes large and it is difficult to realize downsizing of the entire device. When the catalyst body becomes large, the combustion stability tends to be insufficient, particularly in the low combustion amount region, and it becomes difficult to expand the combustion amount variable range. In addition, after the flame combustion is performed by the preheating burner at the start of the catalytic combustion, the supply of the air-fuel mixture is stopped to extinguish the flame of the preheating burner, and the air-fuel mixture is supplied again to perform the catalytic combustion, so that the control tends to be complicated. In addition, there is a problem that nitrogen oxides (NOx) are generated during flame combustion.
[0004]
The present invention provides a catalytic combustion apparatus that can increase the efficiency of heat transfer performance, reduce the size of equipment, reduce costs, enable radiant heating over a wide range, and improve radiation efficiency. It is for the purpose.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides, as a first means, a mixed gas supply part of fuel and air, a gas-permeable catalyst body provided downstream in the flow direction of the mixed gas supply part, and a mixed gas of the catalyst body An infrared transmitting body provided facing the catalyst body on the upstream side in the flow direction, a radiation heat receiving body having a heat exchange section facing the catalyst body via the infrared transmitting body, and between the infrared transmitting body and the radiation heat receiving body The catalytic combustion apparatus is provided with an exhaust passage communicating with the downstream of the catalyst body so that the combustion gas formed and passed through the catalyst body flows .
[0006]
As a second means, there is provided a catalytic combustion apparatus provided with an infrared absorber in the first means without an infrared transmitting body.
[0007]
As a third means, a mixed gas supply part of fuel and air, two planar catalyst bodies having air permeability provided downstream in the flow direction of the mixed gas supply part, and two provided on the outside of the catalyst body The catalyst combustion apparatus is provided with an infrared transmitting body or an infrared absorbing body and two air-fuel mixture paths formed between the catalyst body and the infrared transmitting body or the infrared absorbing body.
[0008]
As a fourth means, the catalyst body is formed between an infrared transmitting body or a radiation heat receiving body having a heat exchanging portion facing through the infrared absorbing body, and between the infrared transmitting body or the infrared absorbing body and the radiation receiving body, A catalytic combustion apparatus of a third means provided with an exhaust path communicating with the downstream side of the catalyst body is provided.
[0009]
As fifth means, two planar catalyst bodies, an auxiliary catalyst body positioned on the downstream side of the two catalyst bodies, and an electric heater positioned between the two catalyst bodies and the auxiliary catalyst body The electric heater is energized at the start of combustion, the catalyst body and the auxiliary catalyst body are heated, the energization to the electric heater is stopped, and after a predetermined time, the air-fuel mixture is supplied to start catalytic combustion. A fourth catalytic combustion apparatus is assumed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the first embodiment. The main parts of the catalytic combustion apparatus of the first embodiment are a catalyst body 1, a catalyst body support 2, a fixed plate 3, a combustion chamber wall 4, an electric heater 5, an auxiliary catalyst body 6, an auxiliary catalyst body support 7, and a radiation heat receiving body 8. , A heat exchanging section 9, an infrared transmitting body 10, an infrared transmitting body support 11, an exhaust path 12, and an exhaust hole 13. The catalyst body 1 and the auxiliary catalyst body 6 are made by supporting a noble metal catalyst such as palladium or platinum using a cordierite honeycomb having air permeability as a carrier.
[0011]
Two catalyst bodies 1 are provided, and are inclined to face each other with a predetermined distance so that the upstream side of the air-fuel mixture is on the outside. The auxiliary catalyst body 6 is provided on the downstream side of the catalyst body 1, and the electric heater 5 is positioned between the catalyst body 1 and the auxiliary catalyst body 6. The radiation heat receiving body 8 is provided on the upstream side of the catalyst body 1 so as to face the catalyst body 1 so as to easily receive radiation, and the heat receiving section 8 is provided with a heat exchanging portion 9. The infrared transmitting body 10 is made of glass, and an exhaust path 12 is provided between the infrared transmitting body 10 and the copy heat receiving body 8. On the upstream side of the catalyst body 1, an air-fuel mixture path 14, a partition plate 15, an air-fuel mixture injection hole 16, and a gas mixture supply unit 17 are provided.
[0012]
Next, the operation of the present embodiment will be described. First, the electric heater 5 is energized at the start of combustion, the catalyst body 1 or the auxiliary catalyst body 6 is heated to the activation temperature or higher, and then the electric power to the electric heater 5 is stopped, and the surface temperature of the electric heater 5 is set to the ignition temperature. After making it less than, the air-fuel mixture is supplied to the catalyst body 1 and catalytic combustion is performed. The air-fuel mixture passes through the gas mixture supply section 17 and is ejected from the air-fuel mixture ejection hole 16. At the time of catalytic combustion, the upstream surface of the catalyst body 1 is heated red, and radiant energy is emitted upstream. This radiant energy passes through the infrared transmitting body 10, is absorbed by the radiant heat receiving body 8, and is converted into thermal energy again, whereby radiant heat is transferred from the catalyst body 1 to the radiant heat receiving body 8. Thereafter, heat is transferred to the fluid to be heated by the heat exchanging portion 9 provided in the radiation heat receiving body 8 by heat conduction. Since the radiant heat transfer does not disturb the flow of the air-fuel mixture, the combustion reaction at the upstream surface of the catalyst body 1 is not hindered, and the combustion stability can be ensured even if the amount of heat exchange with the heated fluid is increased. it can.
[0013]
The combustion gas that has passed through the catalyst body 1 is purified by the auxiliary catalyst body 6, passes through the exhaust passage 12 outside the infrared transmitting body 10, and is discharged from the exhaust hole 13. In the exhaust path 12, the heat of the combustion gas is transferred to the radiation heat receiving body 8 by convective heat transfer. That is, the heat transfer to the radiation heat receiving body 8 takes a form in which the radiant heat transfer from the catalyst body 1 and the convective heat transfer from the combustion gas coexist. With this configuration, it is possible to increase the efficiency of heat transfer performance and reduce the size of the device.
[0014]
As described above, the mixed gas supply unit 17, the two planar catalyst bodies 1 having air permeability provided downstream in the flow direction of the mixed gas supply unit 17, and the two infrared transmissions provided outside the catalyst body 1. By providing the body 10 and the two air-fuel mixture paths 14 formed between the catalyst body 1 and the infrared transmitting body 10, the catalytic combustion apparatus can be reduced in size and radiant energy can be applied to the front and rear surfaces of the apparatus. In this way, a wide range of radiant heating is possible. Furthermore, by making two catalyst bodies 1 face each other, the downstream side of the catalyst body 1 can be used as a heat retaining region, and exhaust energy and heat dissipation loss can be reduced to increase the radiation energy to the upstream side of the catalyst body 1, Radiation efficiency is improved.
[0015]
A radiation heat receiving body 8 having a heat exchanging portion 9 facing the catalyst body 1 via the infrared transmission body 10 and an exhaust path formed between the infrared transmission body 10 and the radiation heat reception body 8 and communicating with the downstream of the catalyst body 1 12, two planar catalyst bodies 1, two infrared transmission bodies 10 provided outside the catalyst body 1, and two air-fuel mixture paths 14 formed between the catalyst body 1 and the infrared transmission body 10. By providing the above, it is possible to realize a high load type heat exchange integrated catalytic combustor.
[0016]
By making the catalyst body 1 incline and face each other, the concentration distribution and flow velocity distribution of the air-fuel mixture can be improved and the catalytic reaction can be made uniform. Installation of the auxiliary catalyst body 6 for purification is also facilitated.
[0017]
Two planar catalyst bodies 1, an auxiliary catalyst body 6 positioned downstream of the two catalyst bodies 1, and an electric heater 5 positioned between the two catalyst bodies 1 and the auxiliary catalyst body 6 The electric heater 5 is energized at the start of combustion, the catalyst body 1 and the auxiliary catalyst body 6 are heated, the energization to the electric heater 5 is stopped, and after a predetermined time, an air-fuel mixture is supplied to start catalytic combustion By doing so, there is no abnormal ignition in the vicinity of the electric heater 5 or generation of NOx, so that the temperature can be kept between the catalyst body 1 and the auxiliary catalyst body 6 and the start-up time can be shortened. Furthermore, since the upstream temperature of the catalyst body 1 does not rise at the time of start-up, heat does not move to the radiation heat receiving body 8, and the heat of the electric heater 5 can be utilized efficiently for start-up.
[0018]
By using the radiation heat receiving body 8 as a metal plate and covering the heat receiving surface side with a high radiation material, the radiation heat transfer efficiency from the catalyst body 1 can be further improved.
[0019]
By forming a protrusion (not shown) that receives the exhaust heat on the exhaust path side of the radiation heat receiver 8, the heat transfer area can be increased to improve the convective heat transfer performance and to increase the efficiency.
[0020]
(Embodiment 2)
Next, a second embodiment of the present invention will be described. FIG. 2 is a cross-sectional view of the second embodiment. The catalytic combustion apparatus of the second embodiment does not have the infrared transmitting body 10 but is provided with an infrared absorbing body 18. As the infrared absorber 18, stainless steel having an oxidized surface is used, but any material having a high emissivity and excellent heat resistance may be used.
[0021]
In Embodiment 2, after the radiation energy from the catalyst body 1 is absorbed by the infrared absorber 18, the radiation energy from the infrared absorber 18 is absorbed by the radiation heat receiving body 8 and converted into thermal energy. There is radiant heat transfer from the infrared absorber 18 to the infrared absorber 18 and radiant heat transfer from the infrared absorber 18 to the radiation heat receiver 8. Even the infrared transmitting body 10 (glass) does not transmit 100% of the radiant energy. Therefore, by increasing the temperature of the infrared absorbing body 18, the efficiency of radiant heat transfer from the catalyst body 1 to the radiation heat receiving body 8 can be increased. It is also possible to approach the case of using. In Embodiment 2, since it is not necessary to install the infrared transmitting body 10 (glass), it becomes easy to achieve cost reduction.
[0022]
Radiation heat transfer efficiency from the catalyst body 1 to the radiation heat receiving body 8 can be further improved by using the infrared absorber 18 as a metal plate and covering both surfaces with a high radiation material.
[0023]
【The invention's effect】
As is clear from the above description, according to the catalytic combustion apparatus of the present invention, the following effects can be obtained.
[0024]
By providing a radiation heat receiver on the upstream side of the air-fuel mixture of the catalyst body via an infrared transmission body and an exhaust path, a heat transfer form in which radiant heat transfer from the catalyst body and convective heat transfer from the combustion gas coexist, High efficiency in heat transfer performance and downsizing of equipment are possible.
[0025]
Cost reduction can also be achieved by using an infrared absorber without using an infrared transparent body (glass).
[0026]
By making two catalyst bodies face each other with a predetermined distance so that the upstream side of the mixture is on the outside, it is possible to reduce the size and to emit radiant energy to the front and rear surfaces of the equipment. Heating is possible and radiation efficiency is improved.
[0027]
An electric heater is provided between the two catalyst bodies and the auxiliary catalyst body. The electric heater is energized at the start of combustion, the catalyst body or the auxiliary catalyst body is heated, the energization to the electric heater is stopped, and a predetermined time later By supplying the air-fuel mixture and performing catalytic combustion, there is no abnormal ignition in the vicinity of the electric heater or generation of NOx, so that the temperature can be kept between the catalyst body and the auxiliary catalyst body, and the startup time can be shortened.
[Brief description of the drawings]
FIG. 1 is a sectional view of a catalytic combustion apparatus according to a first embodiment of the present invention. FIG. 2 is a sectional view of a catalytic combustion apparatus according to a second embodiment of the present invention.
DESCRIPTION OF SYMBOLS 1 Catalyst body 5 Electric heater 6 Auxiliary catalyst body 8 Radiation heat receiving body 9 Heat exchange part 10 Infrared transmitting body 12 Exhaust path 18 Infrared absorber

Claims (9)

A fuel and air mixed gas supply unit, a gas-permeable catalyst body provided downstream in the flow direction of the mixed gas supply unit, and the catalyst body facing the catalyst body upstream in the flow direction of the air-fuel mixture of the catalyst body An infrared transmitting body provided; a radiation heat receiving body having a heat exchange portion facing the catalyst body through the infrared transmitting body; and formed between the infrared transmitting body and the radiation heat receiving body, A catalytic combustion apparatus comprising an exhaust passage communicating with the downstream side of the catalyst body so as to flow the passed combustion gas . A fuel and air mixed gas supply unit, a gas-permeable catalyst body provided downstream in the flow direction of the mixed gas supply unit, and the catalyst body facing the catalyst body upstream in the flow direction of the air-fuel mixture of the catalyst body An infrared absorber provided, a radiation heat receiver having a heat exchange section facing the catalyst body via the infrared absorber, and formed between the infrared absorber and the radiation heat receiver, the catalyst body A catalytic combustion apparatus comprising an exhaust passage communicating with the downstream side of the catalyst body so as to flow the passed combustion gas . A fuel / air mixed gas supply section, two air-permeable planar catalyst bodies provided downstream in the flow direction of the mixed gas supply section, and two infrared transmissions provided outside the catalyst bodies A catalytic combustion apparatus comprising: a body or an infrared absorber; and two air-fuel mixture paths formed between the catalyst body and the infrared transmitter or the infrared absorber. A radiation heat receiving body having a heat exchange part facing the infrared ray transmitting body or the infrared absorbing body on the catalyst body, the infrared transmitting body, or formed between the infrared absorbing body and the radiation heat receiving body, The catalytic combustion apparatus according to claim 3, further comprising an exhaust path communicating with the downstream side of the catalyst body. The catalytic combustion apparatus according to claim 3 or 4, wherein the catalyst bodies are inclined and face each other. The catalyst bodies are two planar catalyst bodies, and an auxiliary catalyst body positioned on the downstream side of the two catalyst bodies, and an electric body positioned between the two catalyst bodies and the auxiliary catalyst body. A heater, and energizes the electric heater at the start of combustion, heats the catalyst body and the auxiliary catalyst body, stops energization of the electric heater, and after a predetermined time, supplies an air-fuel mixture to form a catalyst The catalytic combustion apparatus according to claim 3 or 4, wherein combustion is started. The catalytic combustion apparatus according to claim 1, 2 or 4, wherein the radiation heat receiving body is a metal plate, and the heat receiving surface side is coated with a high radiation material. The catalytic combustion apparatus according to claim 2, 3 or 4, wherein the infrared absorber is a metal plate and both surfaces thereof are coated with a high radiation material. 5. The catalytic combustion apparatus according to claim 1, wherein a projection for receiving exhaust heat is formed on the exhaust path side of the radiation heat receiving body.

Images