JPS59131815A - Catalyst burner - Google Patents

Abstract

PURPOSE:To subject the fuel to a stable and efficient oxidization reaction under an air-to-fuel ratio in a wide range and to clean the exhaust gas by providing a first catalyst member carrying an oxidized catalyst other than CuO at the upstream side of a pre-mixed air current, and a second catalyst member carrying CuO as an oxidized catalyst at the downstream side. CONSTITUTION:The first catalyst member 11 carrying an oxidized catalyst other than CuO is provided at the upstream side of a pre-mixed air current formed by pre-mixing a gaseous fuel or an evaporated liquid fuel with combustion air, and a second catalyst 12 carrying CuO as an oxidized catalyst is provided at the downstream side of the pre-mixed air current. The interval between the first catalyst member 11 and the second catalyst member 12 is set so that the temperature of the second catalyst 12 becomes about 800-1,000 deg.C. Further, the first catalyst 11 carries on the carrier one or more members selected from the group consisting of transient oxides such as Ni, Co, Cr and the like. The CuO carrying rate of the second catalyst member 12 is set to 1-5wt% with respect to the weight of the carrier.

Description

Detailed Description of the Invention Page 2 Industrial Application Field The present invention is a method of premixing various gaseous fuels or vaporized liquid fuels with combustion air, supplying the mixture to a catalyst body, and carrying out an oxidation reaction on the surface of the catalyst body. This invention relates to a catalytic combustor that causes a catalytic body to generate heat and utilizes the generated heat.

Structure of the conventional example and its problems In the conventional catalytic combustor, as shown in FIG.
The catalyst body 2 was cooled by contact with the outside air, and a low temperature region below the activation temperature was formed at the outer periphery and front surface of the catalyst body 2. Therefore, there is a drawback that the premixture passing through this portion is not completely combusted and is discharged as unburned gas containing hydrocarbons and CO. This tendency was particularly severe when the excess air ratio was increased in the low combustion area.

OBJECT OF THE INVENTION The present invention solves these conventional problems, and provides a catalyst that allows fuel to undergo a stable and efficient oxidation reaction on a catalyst body even under a wide range of air-fuel ratios, and also produces clean exhaust gas. The purpose of 3 pages is to provide a combustor.

Structure of the Invention In order to achieve the above object, the present invention uses two types of catalyst bodies, a first catalyst body carrying an oxidation catalyst other than CuO on the upstream side of the premixed air flow, and a first catalyst body supporting an oxidation catalyst other than CuO on the downstream side of the premixed gas flow. A second catalyst body supporting CuO, which has excellent performance as an oxidation catalyst, is installed at a distance. With this configuration, the first catalyst body forms a low temperature part to some extent due to the cooling effect due to contact with the combustion cylinder. The unburned gas discharged from the outer periphery of the medium collides with the second catalyst body installed in front, and a part of the unburned gas is returned to the first catalyst body and reoxidized, and the second catalyst body The arrangement causes a stagnation of the exhaust gas stream, and as a result cooling of the first catalytic body is prevented. Furthermore, the exhaust gas that can be completely oxidized by the above action and contains unburned components such as Co is sent onto the second catalyst body heated by the radiant heat from the first catalyst body, It is almost completely oxidized by the oxidizing action of Co of CuO supported on the catalyst body. Therefore, in the low combustion amount region, stable combustion can be achieved even if the air-fuel ratio is increased, and it has become possible to expand the combustion width and, by extension, the TDR.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the catalytic combustor according to the present invention is shown in FIG. 2 and will be described accordingly.

Behind the vaporization premixing cylinder 4 in which the sheathed heater 3 is embedded,
A fixed plate 6 having an air port 15 in the center is joined, and a horizontal cylindrical combustion cylinder 7 made of a heat-resistant metal is fitted in front of the vaporizing premix cylinder 4.

Inside the combustion tube 7, toward the front thereof, there is a resistance plate 8 made of wire mesh or punched metal. 9. Rectifier plate made of heat-resistant ceramic material. Flashback prevention plate 10 also made of heat-resistant ceramic. The cylindrical first catalyst body 11° has CuO in front of it.
The second catalyst bodies 12 carrying . Further, a spark plug 13 is located immediately in front of the current plate 9 in the combustion tube 7.
It is installed in such a way that it penetrates. On the other hand, the vaporization premixer 4
At the tip of the shaft 14 facing inward, a circular trapezoidal cone 152 whose diameter increases toward the front, a rotary plate 169, and a mixing plate 17 having small stirring blades on the circumferential edge are fixed in sequence. . Further, the tip of the oil supply pipe 18 is installed so as to open on both sides of the cone 16''.

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

When the sheathed heater 3 is energized and the side wall of the vaporization premix cylinder 4 reaches a predetermined temperature, the fan and electromagnetic pump (both not shown) are energized and the supply of air and liquid fuel is started. The liquid fuel is sent onto the rotating cone 15 by the fuel supply pipe 18, and is sent to the rotating plate 1 along the taper of the cone 16.
When the temperature reaches 6, the particles are scattered as fine particles in the circumferential direction due to the rotational force, contact the side wall of the vaporization premix cylinder 4 in a constant temperature state, and immediately vaporize. On the other hand, the air taken in by the fan is sent from the air port 6 into the vaporization premixing cylinder 4, and the mixing plate 17
The gas is uniformly mixed with the vaporized liquid fuel to form a premixed gas. After the premixed gas passes through the resistor plate 8 and the rectifier plate 9, the spark plug 13 emits a spark when energized.
is ignited. At the initial stage of ignition, a blue flame is formed on the front side of the baffle plate 9 to cause flame combustion. In this state, radiant heat from the flame and heat transfer from the combustion tube 7 cause the catalyst body 11 to reach the activation temperature necessary for catalyst 6 vapor combustion. Afterwards,
Once the fuel supply is stopped to extinguish the blue flame, and then the fuel supply is restarted, the premixed gas does not form a flame and the catalyst body 11, which maintains the activation temperature, undergoes flameless combustion. will be started.

At this point, the surface temperature of the central part of the catalyst body 11 is 800°C.
The temperature reaches about 1200°C, and the reaction by the oxidation catalyst becomes steady. However, since the outer peripheral part of the catalyst body 11 is cooled by contact with the combustion cylinder 7 and does not reach the activation temperature, the premixed gas passing through this part cannot be completely oxidized and contains a large amount of hydrocarbons, Co, etc. Passes through as unburned gas containing On the other hand, the catalyst body 12 located in front of the catalyst body 11 is
The activation temperature is reached by radiant heat from 1. When the unburned gas reaches the catalyst body 12 in this state, the catalyst body 12
It is completely oxidized by the CuO supported on it. Further, as the unburned gas collides with the catalyst body 12, a portion of the unburned gas flows back onto the catalyst body 11 and is reoxidized, and a stagnation of the exhaust gas flow occurs, so that the temperature of the catalyst body 11 is maintained.

Page 7 As data to demonstrate the effects of the catalytic combustor of the present invention, the differences in combustion characteristics when using the conventional example shown in Figure 1 and the embodiment of the present invention shown in Figure 2 are presented in the text. It is shown in Figure 3. In addition, as the medium for the catalyst body 12, a medium containing several layers of N i O was used, as an oxidation catalyst for the catalyst body 12, one containing several layers of CuO was used, and as the liquid fuel, kerosene was used.

Note that the black circles indicate the embodiment of the present invention, and the white circles indicate the conventional example.

The upper limit indicates the upper limit of combustion, and the lower limit indicates the lower limit of combustion.

In the figure, the definition of the combustion upper limit is that when the CO2 concentration is increased by restricting the amount of air, 00, which is the limit at which a flame is formed behind the catalyst body 2 and flameless combustion is no longer possible.
2 concentration (flashback limit), and the lower combustion limit is defined as the limit 002 concentration (blow-off limit) at which Co starts to be generated in the exhaust gas when the amount of air is increased and the CO2 concentration is decreased. show. The difference between the upper limit of combustion and the lower limit of combustion is defined as the combustion width, and when the value is 2.8 vo1% or more, it is defined as the stable combustion region, and the ratio of the minimum combustion amount to the maximum combustion amount at that time is defined as the combustion width. It was called TDR.

From FIG. 3, in the case of the conventional example, the combustion lower limit is particularly high in the low combustion amount region. That is, it shows that the excess air ratio cannot be increased. In contrast, the embodiment of the present invention maintains a stable combustion width from 1000 to 320 degrees 1 m/h, making it possible to obtain a higher air-fuel ratio than in the conventional example.

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

(1) In the same combustion cylinder, a first catalyst body supporting an oxidation catalyst other than CuO is installed on the upstream side of the premixed air flow, and a second catalyst body supporting CuO as an oxidation catalyst is installed downstream at intervals. As a result, the unburned gas discharged from the outer circumferential portion of the first catalyst body, which forms a low IA 4, can be completely oxidized on the second catalyst body due to the additive action of the combustion tube.

Page 9 (2) With the above configuration, a stagnation of the exhaust gas flow occurs between the first catalyst body and the second catalyst body, and the entire first catalyst body is heated by the heat of the exhaust gas, and especially the outside of the first catalyst body is heated. Cooling of the surrounding area is suppressed.

(3) With the above configuration, stable combustion is possible even in the low combustion amount region and with a higher excess air ratio than before.
As a result, it has become possible to secure a wide range of TDR.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional catalytic combustor, FIG. 2 is a longitudinal sectional view of an embodiment of a catalytic combustor according to the present invention, and FIG. 3 is a longitudinal sectional view of an embodiment of the catalytic combustor according to the present invention. FIG. 3 is a diagram showing a comparison of combustion characteristics. 7... Combustion cylinder, 11... First catalyst body, 12... Second catalyst body. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure!

Claims (1)

[Scope of Claims] 0) A first catalyst body supporting an oxidation catalyst other than CuO on the upstream side of a premixed airflow in which gas fuel or vaporized liquid fuel is premixed with combustion air, and a first catalyst body supporting an oxidation catalyst other than CuO on the downstream side. A catalytic combustor in which second catalyst bodies supported as oxidation catalysts are installed at intervals. (2) The temperature of the second catalyst body during combustion is 800 to 1000
2. The catalytic combustor according to claim 1, wherein the distance between the first catalyst body and the second catalyst body is set so that the temperature is about .degree. (3) The first catalyst body has Ni, Fe, Co,
The catalytic combustor according to claim 1, which supports one or more types of transition metal oxides such as Cr. (4) The supporting rate of CuO in the second catalyst body relative to the carrier weight,
The catalytic combustor according to claim 1, having a weight of 1 to 5 wt.