JPS6053711A - Catalytic combustion apparatus - Google Patents

Abstract

PURPOSE:To keep stabilized combustion in a catalytic combustion apparatus, by providing a honeycomb heat insulating plate, a honeycomb catalyst body, and a back fire preventive plate in the combustion apparatus from the downstream side to the upstream side in order, and by providing a diffusion plate made of expanded ceramics between a vaporizing cylinder and a back fire preventive plate. CONSTITUTION:A combustion cylinder 17 made of heat-resistant metal is composed of a honeycomb heat insulating plate 14 and a honeycomb catalyst body 15, and an ignition heater 16 is provided between them. A mixing cylinder 18 made of metal of high thermal conductivity, Al, for example, is fitted to the bottom of a combustion cylinder 17, and a vaporizing cylinder 20, having built-in sheath heater 19 in it, is fitted to the bottom of a mixing cylinder 18. A diffusion plate 23 made of expanded ceramics is provided in the mixing cylinder 18 underneath a back fire preventive plate 21, consisting of porous plate made of ceramics, and a punched injection plate 22. A resistance 24 consisting of wire net is provided to the opening to connect the mixing cylinder 18 with the vaporizing cylinder 20. With such an arrangement, comparatively compact combustion chamber can be composed, in which stabilized combustion can be taken place, if the rate of combustion and the rate of air are largely changed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention supplies various gaseous fuels or vaporized liquid fuels together with combustion air onto a catalyst body, causes an oxidation reaction on the surface of the catalyst body, and causes the catalyst body to generate heat. This invention relates to a catalytic combustor that uses the generated heat.

Structure of the conventional example and its problems As shown in Fig. 1, the conventional catalytic combustor consists of a cylindrical combustion cylinder 1, a honeycomb-shaped cylindrical catalyst body 2, and a circular plate provided with a large number of small ejection holes. It is equipped with a flashback prevention plate 3 having a shape of
A punching metal 5 and a ceramic perforated plate 6 were provided between the backfire prevention plate a and the backfire prevention plate a. Furthermore, as a fuel supply means, although not shown, a pulse supply method using an electromagnetic pump was used. When catalytic combustion is performed using this method, the electromagnetic pump's PALNU causes pulsation, which causes uneven mixing of fuel and air due to the PALNU type fuel supply.
It was difficult to achieve uniform catalytic combustion on the catalyst body 2. In particular, when burning a low combustion amount, the electromagnetic pump inevitably had a long parnu interval. In addition, in the conventional example shown in FIG. 2, even if a honeycomb catalyst body is not used, a catalyst layer 9 filled with pellet-shaped catalyst particles 8 in the combustion tube 7, and a perforated plate holding the catalyst layer 9. 10. It is the same as having a flashback prevention plate 11 similar to that shown in FIG. 1, and instead of the ceramic porous plate 6 shown in FIG. 1, a diffusion layer 13 filled with a ceramic ring 12 is used to hold the catalyst layer 9. It was held by a perforated plate 10. In this method, the mixing and diffusion of fuel and air is maintained uniformly by the diffusion layer 13 and the catalyst layer 9, but the diffusion layer 13 and the catalyst layer 9 require a large layer length. , the entire combustor was in a state of dependence.

OBJECT OF THE INVENTION The present invention solves the problems of the conventional art, and provides a catalytic combustor that has a relatively compact combustion chamber and can maintain a stable combustion state even when the combustion amount and air amount are varied widely. Our goal is to provide the following.

1111'' of the Invention In order to achieve the above object, the present invention is provided with a honeycomb heat retaining plate, a honeycomb catalyst body, and a flashback prevention plate from the downstream side to the upstream side of the fuel-air premixed air flow, and the vaporization cylinder and the above-mentioned The basic configuration is that a foamed ceramic diffusion plate is installed between the flashback prevention plate.In this configuration, when a pulse supply method using an electromagnetic pump is used as the fuel supply method, the pulsation during fuel supply is as follows. The fuel is absorbed while passing through the labyrinth-like pores spread in the vertical and horizontal directions of the foamed ceramic diffusion plate, and is supplied onto the catalyst body as a stable premixed fuel mixture, thereby achieving a stable combustion state on the catalyst body. Therefore, the exhaust gas is also cleaner.

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a catalytic combustor according to the present invention is shown in FIG. 3 and will now be described.

At the rear of the combustion tube 17 made of a heat-resistant metal, which includes a honeycomb heat insulating plate 14, a honeycomb catalyst body 15, and an ignition heater 16 installed between them, there is a mixing tube 18 made of a metal with good thermal conductivity, such as A1. A sheathed heater 19 is attached to the rear of the mixing cylinder 18, and a foamed ramic diffusion plate 23 according to the present invention is installed inside the ring through a backfire prevention plate 21 made of a ceramic porous plate and a punched spout plate 22. Mixing tube 18
A resistor 24 made of wire mesh is provided at the connection port of the vaporizer cylinder 20. Further, the bottom of the mixing cylinder 18 is supported and fixed by an outer case 26. A blower pipe 26 is fitted into the bottom of the vaporizer cylinder 20, and an oil supply pipe 27 is introduced so as to pass through the blower pipe 26 from the side. Two fuel ejection pipes 2 are provided in the portion of the fuel supply pipe 27 that exists inside the blower pipe 26.
8 are connected, and the jet ports of the fuel jet pipes 28 are directed in opposite directions,
Moreover, the fuel is ejected and collides with the high temperature portion of the carburetor cylinder 20. Furthermore, a thermocouple 29 for regulating the vaporization temperature passes through the vaporization cylinder 20 from the side and faces into the vaporization cylinder 20.

Next, the operation of the embodiment with the above configuration will be explained.

When the thermocouple ship detects that the sheathed heater 19 is energized and the side wall temperature of the vaporizer cylinder 19 has reached a predetermined temperature,
The fan and electromagnetic pump (both not shown on page 6) are energized and the supply of air and liquid fuel is started. Since the liquid fuel is introduced into the vaporizer cylinder 20 from the fuel supply pipe 27 through the extremely thin fuel jet pipe 28, the fuel jet pipe 28
Since the tip collides with the side wall of the vaporization tube 20 with considerable force, it is vaporized while becoming fine particles. On the other hand, the air introduced into the carburetor from the blower pipe 26 mixes with the vaporized fuel to a certain extent, but when it passes through the resistance plate 24 at the outlet of the carburetor 20, it becomes a fairly unmixed fuel premixture. It is in a uniform state. When the fuel mixture in this state reaches the foamed ceramic diffusion plate 23, the labyrinth-like pores of the foamed ceramic diffusion plate 23 cause the fuel mixture in the unevenly mixed state to undergo turbulent diffusion, resulting in punching jets. At the time of passing through the plate 22, a uniform mixed state is maintained. When the fuel mixture in this state passes through the honeycomb catalyst body 15, it is ignited by the ignition heater 16, which maintains a high temperature red heat of 900° C. to 1000° C. when energized. Immediately after ignition, a film-like flame is formed directly above the honeycomb catalyst body 15, and the heat generated by this flame gradually reaches the honeycomb catalyst formation temperature, forming a stable catalytic combustion state. Furthermore, since the honeycomb heat insulating plate 14 is present on the second portion of the hemi-cam catalyst body 15, the cooling effect of outside air can be suppressed, and a more stable catalytic combustion state can be obtained. 1, the pulsation i when fuel is supplied by the electromagnetic pump is absorbed by the foaming-1 and the pores of the lamic diffusion plate 23, and does not affect the combustion on the honeycomb catalyst body 15.

A graph showing the effects of the catalytic combustor according to the present invention is shown in FIG. 4 in comparison with the conventional example shown in FIG.

Since the combustion ability of a honeycomb catalyst body is influenced by the opening area and diameter of the catalyst body, the same honeycomb catalyst body (size 130×720) was used in both the embodiment of the present invention and the conventional example.

As the material, a material mainly composed of Zr○2 was used. In FIG. 4, the vertical axis shows the excess air ratio (m value), the horizontal axis shows the combustion amount of kerosene, the black circles show the embodiment of the present invention, and the white circles show the conventional example.

Note that the upper curve is the blow-off limit, and if the excess air ratio is increased, the combustion balance in the catalyst body 2 and the honeycomb catalyst body 15'2 will be disrupted, and the flame may be blown away from some parts.
The lower curve indicates the limit at which stable combustion is no longer possible due to the generation of Co, and the lower curve indicates the flashback limit, and when the excess air ratio is reduced to approach the theoretical combustion air amount, the flashback prevention plate 3, backfire A flame is formed behind the fire prevention plate 21, and the catalyst body 2,
The limit at which flameless catalytic combustion is no longer possible on the honeycomb catalyst body 15 is shown, and the stable combustion region is defined as the area between the blow-off limit and the flashback limit. From FIG. 4, in the case of the conventional example, the blow-off limit value is shifted to the lower m value side compared to the example of the present invention, indicating that the combustion balance is more likely to collapse than in the example of the present invention. Thus, it can be seen that the embodiment of the present invention is capable of stable combustion even at a high air-fuel ratio compared to the conventional example.

Effects of the Invention According to the catalytic combustor of the present invention, the following effects can be obtained.

(1) From the downstream side of the fuel mixture flow, a foamed ceramic heat insulating plate, a honeycomb catalyst body, and a flashback prevention plate are provided, and between the vaporization cylinder located on the most second flow side and the flashback prevention plate, By installing the diffuser plate, the mixture of fuel gas and air is maintained in a uniform state, and the /X Nicum catalyst body is
It can be supplied to the second.

2. With the above configuration, stable combustion is possible even at a high excess air ratio.

(The configuration described in item 31 does not require a multistage punching metal or diffusion plate such as a wire mesh for uniformly mixing fuel gas and air, so a relatively compact mixer is sufficient, that is, the combustor itself can be made compact.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a conventional catalytic combustor, FIGS. 2 a and b are longitudinal sectional views of another conventional catalytic combustor and a perspective view of a ceramic ring, and FIG. 3 is a catalytic combustor according to the present invention. FIG. 4 is a longitudinal sectional view of one embodiment of the present invention, and is a comparison diagram of combustion characteristics between the conventional example shown in FIG. 1 and the embodiment of the present invention. 14.Honeycomb heat retention plate, 15..2 cam catalyst body, 20.. Vaporization cylinder, 21..
・Flashback prevention plate, 23... Foamed ceramic diffusion plate. Figure 1 Figure 2 Ca,)

Claims (1)

[Claims] (1) A honeycomb heat retaining plate, a honeycomb catalyst body, and a flashback prevention plate made of heat-resistant lamic are provided from the downstream side to the upstream side of the fuel air premix air flow, and furthermore, the upstream side vaporization cylinder and the above-mentioned backfire prevention plate are provided. A catalytic combustor with a foamed ceramic diffuser plate installed between fire prevention plates. e The honeycomb catalyst body contains Fe on a honeycomb carrier. The catalytic combustor according to claim 1, which supports at least one kind of transition metal oxides such as Ni, Co, and Cr. (a) The catalytic combustor according to claim 2, wherein a heat-resistant ceramic such as alumina, mullite, mullite-zircon, or zirconia is used as the carrier material. 4. The catalytic combustor according to claim 1, wherein cordierite is used as the material of the foamed ceramic diffusion plate. 2 pages