JPS61291819A - Catalytic burner - Google Patents

Abstract

PURPOSE:To make it possible to hold an activation temperature over the full surface of a combustion catalyst thereby to obtain an efficient catalytic combustion by providing a second insulator between the outer peripheral portion of the combustion catalyst provided on its back surface with a first heat insulator and a burner case. CONSTITUTION:Within a burner case 1 made of a heat resisting metal are successively provided a first heat insulator 5 made of a heat resisting ceramic fiber formed member, a preheater 6 made of a nichrome heater wire, a combustion catalyst, and a holding net 8 made of a heat resisting metal. On the other hand, at the outer peripheral portion of the combustion catalyst 7 is provided a second heat insulator 9 made of the heat resisting ceramic fiber formed member which is the same as the first heat insulator. The second heat insulator 9 is filled in a space between the same and a burner case 1. Since the cooling operation from the external case to the burner case 1 is prevented from being transmitted to the combustion catalyst 7 by the second heat insulator 9, the combustion catalyst 7 can hold the activation temperature up to its outer peripheral end.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention supplies a gaseous fuel containing city gas such as methane or propane to a combustion catalyst, and causes the gaseous fuel to undergo a catalytic oxidation reaction with the combustion air. , relates to a catalytic burner that utilizes the resulting heat of reaction.

BACKGROUND OF THE INVENTION Conventionally, this type of catalytic burner uses Pt and Pd as a heat-resistant porous ceramic fiber aggregate, as shown in FIG.

A combustion catalyst A supporting a platinum group metal such as Rh as an oxidation catalyst is installed in a burner case B made of a heat-resistant metal, and the outer periphery of the combustion catalyst A is in direct contact with the burner case B. was.

Problems to be Solved by the Invention However, in the case of the configuration of the conventional technology, the outer circumference of the combustion catalyst A is in contact with the burner case B, so the cooling effect from the outside air is transmitted through the burner case B to the combustion chamber. As a result, the outer periphery of the combustion catalyst body forms a region below the activation temperature of the oxidation catalyst. Therefore, the reactivity in this region is lower than that in the central part of the combustion catalyst body A, and as a result, the amount of unburned gas discharged increases. As a result, the fuel gas that passes through the center to the combustion catalyst is almost completely oxidized, while about 5 to 10% of the fuel gas that passes through the outer periphery to the smoldering catalyst remains unoxidized. The proportion of unburned components discharged as-is from the entire catalytic burner was about 1 to 5% of the total fuel gas.

The present invention solves such conventional problems, and by minimizing the slip rate of unburned gas from around the outer periphery of the combustion catalyst body, it is possible to minimize the slip rate from the entire catalytic burner. purpose.

Means for Solving the Problems In order to solve the above problems, the catalytic burner of the present invention includes a second heat insulating material made of a heat-resistant ceramic fiber molded body provided around the outer periphery of the combustion catalyst body, A partition plate made of heat-resistant metal and having an L-shaped cross section is installed between the combustion catalyst and the second heat insulating material, and between the first heat insulating material and the second heat insulating material, so that the fuel gas flow is controlled. A configuration that does not pass through the second insulation material -
It's a J-co thing.

Due to the structure described above, the cooling effect from outside the burner case is prevented from being transmitted to the combustion catalyst body by the second heat insulating material, so that the entire combustion catalyst body maintains the activation temperature. obtain. Further, due to the presence of the partition plate, the fuel gas does not pass through the completely inert second heat insulating material, but passes through the combustion catalyst body. As mentioned above, the effect of maintaining the activation temperature of the combustion catalyst,
Also, due to the effect of preventing leakage of fuel gas, the slip rate of unburned gas from the combustion catalyst body is significantly reduced.

Embodiments Hereinafter, embodiments of the melt burner of the present invention will be described based on the accompanying drawings.

In FIG. 1a, a fuel dispersion nozzle 2 is installed through the bottom of a burner case 1 made of heat-resistant metal.

A gas chamber 4 is formed in the space between the spacer 3 made of heat-resistant metal and the burner case 1. On the downstream side of the spacer 3 with respect to the fuel gas flow, there is a first heat insulating material 5 made of a heat-resistant ceramic fiber molded body, a preheater 6 made of a nichrome heater wire, and a heat-resistant porous ceramic fiber aggregate used as an oxidation catalyst. A combustion catalyst body 7 carrying about 0.5 w% of Rh and a holding net 8 made of a heat-resistant metal are installed in this order. On the other hand, a second heat insulating material 9 made of a heat-resistant ceramic fiber molded body, like the first heat insulating material 5, is installed on the outer peripheral portion of the combustion catalyst body 7, and fills the space between it and the burner case 1. Furthermore, between the combustion catalyst body 7 and the second heat insulating material 9, and between the first heat insulating material 5 and the second heat insulating material 9,
A partition plate 10 made of heat-resistant metal and having an L-shaped longitudinal section is installed between them.

Next, the operation in configuration 1 will be explained.

The electrical heat generated by energizing the preheater 6 is transmitted to the combustion catalyst body 7, the first heat insulating material 5, and the second heat insulating material 9, and when the combustion catalyst body 7 reaches the activation temperature. Fuel gas is supplied into the gas chamber 4 through the fuel distribution nozzle.

The supplied fuel gas is uniformly diffused within the first heat insulating material 5 and reaches the combustion catalyst body 7 while being heated to some extent, where it is catalytically combusted by the combustion air that convects on the surface of the combustion catalyst body 7. Start. When the catalytic combustion reaches the entire combustion catalyst body 7 and the temperature of the combustion layer medium 7 rises to a certain value, the power supply to the preheater 6 is stopped and a stable combustion state is reached in the combustion catalyst body 7. . At this point, the cooling effect from the outside air to the burner case 1 is prevented from being transmitted to the combustion catalyst body 7 by the second heat insulating material 9, so the combustion layer medium 7 maintains the activation temperature up to its outer peripheral edge. It is possible. In addition, the fuel gas that has passed through the first heat insulating material 5 does not enter the second heat insulating material 9, which is completely inactive, due to the partition plate 1o, and all of it flows into the combustion catalyst body 7, resulting in stable activation. An efficient catalytic oxidation reaction is carried out by the combustion catalyst that maintains the oxidation temperature. As a result, the proportion of unburned gas in the exhaust gas discharged from the combustion catalyst body 7 is about 0.3 to 0.4%, and high reaction efficiency can be obtained.

The effect of the catalytic burner of the present invention is shown in Figure 1, which shows the difference in combustion efficiency from that of the conventional example. The combustion catalyst used in the present invention was exactly the same as in the conventional example, and CH4 was used as the fuel gas.

In FIG. 1, black circles indicate the embodiment of the present invention, and white circles indicate the conventional example. As can be seen from the figure, the combustion rate shows a high value in the case of the embodiment of the present invention over the entire range, and especially in the vicinity of 1100 to 120 OkcaVb, the combustion rate is 99.
．． The combustion rate is around 7%, which is a state close to complete combustion. Thus, it is clear that the examples of the present invention maintain superior combustion performance.

Effects of the Invention As described above, the catalytic burner of the present invention provides the following effects.

(1) By installing a first heat insulator on the back side of the combustion catalyst and a second heat insulator between the outer circumference of the combustion catalyst and the burner case, the cooling effect from the outside air is reduced. This is prevented by the second heat insulating material, and the entire combustion catalyst body can maintain the activation temperature.

(2) Since the combustion catalyst body and the second heat insulating material and the first heat insulating material and the second heat insulating material are partitioned by partition plates with an L-shaped cross section, no fuel gas is It does not flow into the inert second heat insulating material.

(3) With the configurations shown in (1) and (2) above,
Efficient catalytic combustion conditions can be obtained in the combustion catalyst body.

[Brief explanation of the drawing]

1A and 1B are a vertical cross-sectional view and a characteristic diagram of an embodiment of the catalytic burner of the present invention, and FIG. 2 is a vertical cross-sectional view of a conventional example. 1. Burner case, 2. ... Fuel dispersion nozzle, 5 ... First heat insulating material, 7 ...
Combustion catalyst body, 9... Second heat insulating material, 10...
...Partition board. Name of agent: Patent attorney Toshio Nakao and 1 other person 4-
Figure 1 Methane combustion amount (Kcal/h)

Claims (2)

[Claims] (1) In the burner case made of heat-resistant metal and having a fuel dispersion nozzle at the bottom, from the upstream side with respect to the fuel gas flow, a heat insulating material made of a heat-resistant ceramic fiber molded body, a heat-resistant porous ceramic fiber assembly. A combustion catalyst body supporting an oxidation catalyst is provided on the body, a second heat insulating material made of a heat-resistant ceramic fiber molded body is provided around the outer periphery of the combustion catalyst body, and the first heat insulating material and the second heat insulating material are provided. and a catalytic burner in which a partition plate made of heat-resistant metal and having an L-shaped cross section is installed at the boundary between the second heat insulator and the combustion catalyst. (2) The catalytic burner according to claim 1, wherein at least one of a platinum group metal or a transition metal oxide is used as an oxidation catalyst.