JP2806018B2 - Catalytic combustion device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic fuel device, and more particularly to a catalytic combustion device for gaseous or liquid fuel used for heating, heating, drying and the like.

2. Description of the Related Art A conventional catalytic combustion device has a configuration as shown in FIG. Fuel and air are supplied to a mixing chamber 4 by a pump 2 and a fan 3 provided in a fuel tank 1. The fuel is vaporized in the mixing chamber 4 and mixed with the air, and then reaches a primary combustion section 5, where an ignition device is provided. 6 to form a flame there. The high-temperature combustion exhaust gas is discharged from the exhaust port 8 through the catalyst layer 7, during which the catalyst layer 7 is heated and heated.
When it is detected that the temperature of the catalyst layer 7 has reached a temperature sufficient to supply the catalyst fuel (the detection unit is not shown), the pump 2 is stopped and the flame of the primary combustion unit 5 is extinguished. Thereafter, when the pump 2 is operated again to supply fuel, the fuel reaches the catalyst layer 7 in the primary combustion section 5 without forming a flame and as a premixed gas. Here, since the temperature of the catalyst layer 7 has risen sufficiently, catalytic combustion is started, and complete combustion is performed. Since catalytic combustion proceeds exclusively on the upstream side surface of the catalyst layer 7, that portion becomes a radiation radiator and passes through the glass window 9 to radiate radiation to the entire surface.

Problems to be Solved by the Invention In a catalytic combustion device, fuel premixed with air causes an oxidation reaction in a catalyst layer, and generates carbon dioxide and water along with reaction heat. Here, if the temperature and time are sufficient, a complete reaction is performed. At a low temperature part such as the peripheral part of the catalyst layer, or at a position where it is in contact with an excessively rich or lean part of the premixed gas, a part of the fuel cannot be completely burned (hereinafter abbreviated as HC after hydrocarbon).
And the generation of intermediate products (especially CO).

In particular, the catalytic activity cannot avoid thermal deterioration, and there is a problem that the activity of the catalyst decreases with time and the generation of HC and CO increases.

An object of the present invention is to solve the above-mentioned problems of the prior art, prevent incomplete combustion, and maintain clean exhaust gas generation for a long period of time.

Means for Solving the Problems In order to solve this problem, the catalytic combustion device of the present invention includes an auxiliary catalyst layer having a large number of communication holes downstream of a main catalyst layer having a large number of communication holes. In another aspect of the present invention, a temperature detecting means is provided in the vicinity of the auxiliary catalyst layer, and the amount of cooling heat of the cooling section is controlled by a signal from the temperature detecting means. Is configured to control the temperature of the combustion gas reaching the combustion gas.

Operation With this configuration, in the catalytic fuel device of the present invention, at a low temperature portion such as the peripheral portion of the main catalyst layer, or at a position where the premixed gas is in contact with an excessively rich or excessively lean portion, the premixed gas cannot be completely burned, and the Some (HC) and intermediate products (especially CO) are generated. HC and CO contained in the combustion gas in the main catalyst layer are completely reacted by the auxiliary catalyst layer provided downstream of the main catalyst layer. Then, in order to prevent the auxiliary catalyst layer from being thermally degraded, the combustion gas is cooled between the main catalyst layer and the auxiliary catalyst layer, the temperature of the combustion gas is lowered, and the combustion gas reaches the auxiliary catalyst layer.

Further, a temperature detector is provided near the auxiliary catalyst layer, and the temperature of the combustion gas reaching the auxiliary catalyst layer is controlled by a signal from the temperature detector.

An embodiment of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, 10 is a fuel tank, 11 is a fuel supply pump, 12 is a blower fan, and both are mixing chambers 13.
Is in communication with The mixing chamber 13 is provided with a heater for heating (not shown). A primary combustion section 14 is provided downstream of the mixing chamber 13, and an ignition device 15 is provided near the primary combustion section 14. Primary combustion section
Downstream of 14 is a main catalyst layer 16 made of a honeycomb-shaped ceramic.
The auxiliary catalyst layer 17 is provided downstream of the main catalyst layer 16 and communicates with the exhaust port 22.

Fuel and air are supplied to a mixing chamber 13 by a fuel supply pump 11 and a blower fan 12, and the fuel is vaporized in the mixing chamber 13 and mixed with air, and then reaches a primary combustion section 14, where it is ignited by an ignition device 15. Being here forms a flame. The high-temperature combustion exhaust gas heats and raises the temperature of the main catalyst layer 16. Main catalyst layer 16
When it is detected that the temperature has reached a temperature sufficient to perform catalytic combustion (the detection unit is not shown), the fuel supply pump 11 is stopped, and the flame of the primary combustion unit 14 is extinguished. Thereafter, when the fuel supply pump 11 is operated again to supply fuel to the mixing chamber 13, the primary combustion portion 14 does not form a flame, but reaches the main catalyst layer 16 as a premixed gas, and In layer 16, catalytic combustion starts.

At this time, in a low temperature portion such as the peripheral portion of the main catalyst layer 16 or a position where the premixed gas is in contact with an excessively rich or excessively lean portion, the premixed gas cannot be completely burned, and HC and CO are generated. In this embodiment, since the auxiliary catalyst layer 17 is provided downstream of the main catalyst layer 16,
HC and CO contained in the combustion gas in the main catalyst layer 16 can be completely reacted and purified in the auxiliary catalyst layer 17 to produce clean exhaust gas.

In general, thermal degradation of the activity of the catalyst cannot be avoided, and the activity of the catalyst decreases with time and the generation of HC and CO increases. In order to suppress the thermal degradation of the catalyst, the combustion temperature of the catalyst layer may be reduced. However, in consideration of the use of the catalyst combustor, the temperature of the catalyst layer cannot be reduced. Therefore, as the combustion time elapses, the generation amount of HC and CO contained in the combustion gas discharged from the main catalyst layer 17 increases. This thermal degradation of the catalyst activity is caused by the main catalyst layer 16.
This phenomenon occurs not only in the auxiliary catalyst layer 17 but also in the auxiliary catalyst layer 17. However, since the auxiliary catalyst layer 17 is for burning a small amount of CO and HC that could not be burned in the main catalyst layer 16, the main catalyst layer 16
As described above, there is no need to raise the temperature of the catalyst, and there is no restriction on the catalyst temperature due to the use of the catalytic combustion device.

Therefore, in the present embodiment, a cooling unit including a radiating fan 19 is provided on a side surface of the combustion tube 18 connecting the main catalyst layer 16 and the auxiliary catalyst layer 17, and the combustion tube 18 is forcibly cooled by blowing air from the radiating fan 19. By doing so, the temperature of the combustion gas from the main catalyst layer 16 decreases, and reaches the auxiliary catalyst layer 17. For this reason, the auxiliary catalyst layer 17 does not reach a high temperature, is not thermally degraded even after the combustion, and the CO generated from the main catalyst layer 16 is reduced.
And HC were completely burned, and it was possible to maintain clean exhaust gas generation for a long period of time.

As yet another embodiment, when the temperature detecting section 20 is provided near the auxiliary catalyst 17 as shown in FIG. 1, the following operation and effect can be obtained.

Although the temperature detector 20 is provided near the auxiliary catalyst layer 17 to detect the temperature of the combustion gas as in the present embodiment, the temperature of the auxiliary catalyst layer 17 May be detected. Here, the temperature detection unit 20 detects temperature, light, and the like with a thermocouple, an optical sensor, and the like.
The temperature of the combustion gas and the temperature of the auxiliary catalyst layer 17 can be detected. In this embodiment, a thermocouple is used.

The signal from the temperature detection unit 20 is sent to the temperature controller 21 to control the amount of air blown by the heat radiating fan 19 so that the combustion gas temperature and the temperature of the auxiliary catalyst layer 17 become set values. Therefore, the combustion temperature of the auxiliary catalyst layer 17 can be controlled accurately.

For this reason, it is possible to appropriately cope with the fluctuation of the combustion load in the main catalyst layer 16, suppress the increase in the temperature of the auxiliary catalyst layer 17, and dramatically improve the durability of the auxiliary catalyst layer 17.

Further, since the temperature of the combustion gas reaching the auxiliary catalyst layer 17 is accurately controlled, the specifications of the auxiliary catalyst layer 17 can be optimized. Therefore, the capacity of the auxiliary catalyst layer 17 can be minimized, and the exhaust gas can be more effectively purified at low cost.

Although the above example describes oil burning,
Similar results have been obtained for gaseous fuel and the like, and the fuel type is not limited. Further, there is no significant difference depending on the material and shape of the catalyst body, and similar results are obtained by using a braided ceramic fiber body or a metal honeycomb body.

Effects of the Invention As is apparent from the above description of the embodiment, according to the catalytic combustion device of the present invention, the auxiliary catalyst layer having a large number of communication holes is provided downstream of the main catalyst layer having a large number of communication holes, By providing a cooling portion for the combustion gas between the layer and the auxiliary catalyst layer, incomplete combustion can be prevented and clean exhaust gas generation can be maintained for a long period of time.

[Brief description of the drawings]

FIG. 1 is a sectional side view of a catalytic combustor according to an embodiment of the present invention, and FIG. 2 is a sectional side view of a conventional catalytic combustion device. 13 ... mixing chamber, 16 ... main catalyst layer, 17 ... auxiliary catalyst layer, 19
…… a heat dissipation fan, 20 …… a temperature detector.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F23D 11/40 F23C 11/00 306 F23C 11/00 312

Claims (2)

(57) [Claims] 1. A fuel / air mixing chamber, a main catalyst layer having a plurality of communication holes provided downstream of the mixing chamber, and an auxiliary having a plurality of communication holes provided downstream of the main catalyst layer. A catalytic combustion apparatus comprising: a catalyst layer; and a combustion gas cooling unit provided between the main catalyst layer and the auxiliary catalyst layer. 2. A fuel / air mixing chamber, a main catalyst layer having a plurality of communication holes provided downstream of the mixing chamber, and an auxiliary having a plurality of communication holes provided downstream of the main catalyst layer. A catalyst layer, a cooling unit for combustion gas is provided between the main catalyst layer and the auxiliary catalyst layer, a temperature detection unit is provided near the auxiliary catalyst layer, and reaches the auxiliary catalyst layer by a signal from the temperature detection unit. A catalytic combustion device that controls the temperature of the combustion gas.