JPS5847905A - Catalytic combustor - Google Patents

Abstract

PURPOSE:To obtain a safety catalytic combustor having a large variable range of input, by a method wherein a catalytic reaction layer is made into a cross flow heat exchanger shape, an oxidation catalyst, such as platinum is applied on a premixing duct, and a coolant is passed through a duct meeting at right angles with the premixing duct for an improvement of thermal efficiency. CONSTITUTION:A rotation of a blower 10 for cooling a catalyst is controlled by a controller 9 according to a signal of a temperature detector 5. A catalyst layer 3' of a cross flow shape is constituted by a method wherein ceramic or heat resisting metal body formed of a plurality of thin metallike fins which are in parallel with one face of a flat plate on a thin corrugated plate or a thin plate is made into a unit, and axial directions of corrugated plates and fins of a plurality of the units are made to meet at right angles with each other for piling up. A coolant is supplied to a duct meeting at right angles with the catalyst layer 3' through the foregoing blower 10. With this, a variation of combustion quantity is easy and a safety catalyst combustor having high thermal efficiency and a large variable range of input can be obtained by realization of an optional temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to improving the durability of a catalytic combustion device.

An example of a conventional premix combustion device that uses city gas or the like as fuel will be described with reference to FIG. 1. In the figure, 1 is a combustion air blower, 2 is a gas or other fuel supply device, 3 is an oxidation catalyst made of platinum, palladium, etc. coated on foamed metal, nicum ceramics, etc., and 4 is an igniter. 5 is a temperature detector embedded in the oxidation catalyst 3, and 6 is the combustion machine body.

7 is a multi-tubular heat exchanger, and 8 is a heat exchange blower.

The operation of the device configured as described above is as follows: 1. Almost simultaneously with the operation of the blower 1, a large amount of fuel is supplied to the fuel supply device 2, and the mixture of air and fuel is delivered to the igniter 4 and then to the downstream side of the i3. is ignited. The heat is received by the fire, the temperature rises gradually, and the combustion slows down to a steady state so that it progresses sequentially within the catalyst. Then, the temperature pattern of the catalyst 3 was detected by the detector 5, and the combustion 4A was confirmed, and the heat exchange blower 8 and the multi-tubular heat exchanger 7 exchanged heat with the combustion scum and heated it as warm air. Used for elbow%. Therefore, the catalytic combustion is carried out on the surface of a catalyst carrier such as a porous material, foamed metal, honeycomb ceramic, or clay, or within a narrow space, so that the flame temperature is low and the reducing effect of the catalyst and raw materials during combustion is also reduced. Because of this, nitrogen oxides (NOXJ), a harmful exhaust gas component, are
It is extremely low, less than 1 ppm. In addition, since oxidized longitudinal lines (CO) are also permeated on the catalyst surface, there are very few discharge lids.

However, in the conventional catalytic combustion apparatus described above, it was necessary to raise the catalyst layer temperature by approximately 600 to 700°C. In other words, in the observation using an active catalyst such as platinum or palladium, the temperature of the catalyst layer is 6 as shown in Figure 2.
If the temperature drops below 00℃, the combustion efficiency* will decrease and a large amount of unfueled (H
,C) is discharged. On the other hand, even the catalysts currently available on the market that have a high mixing resistance during continuous use are at most 4 Asoo°C.
In addition, if the amount of furnace material flowing into the catalyst reaction layer increases due to some external 1LK, the catalyst layer tA degree will rise to 900 degrees.
If the temperature rises excessively above ℃υ, the life of the catalyst will be extremely shortened, and the catalyst layer will become an ignition source, causing backfire in the air-fuel mixture upstream, which could cause major damage to the combustion equipment. be.

Therefore, the 11th! ! ! In the conventional combustion device shown in 4, the air ratio μ of the combustion premixture (supply air fi/theoretical air*)
k2. When the combustion temperature is lowered by setting it to a higher value than o,
I carefully measured the combustion amount per unit volume of the catalyst so that the catalyst temperature would reach the above set value (about 600 to 700 degrees Celsius).However, when I burned it at a high air ratio, I was surprised at how low the flammability was. At the time of fire, O, HC emissions are large, and it takes a long time for the medium to heat up, so it takes a long time to reach steady combustion. Furthermore, as shown in the example of catalyst temperature measurement in Section 3V, the temperature of the catalyst depends directly on the combustion amount and air ratio, so the trap of keeping it at 600 to 700℃ is that the air temperature is lower than the combustion amount. It is difficult to vary the combustion amount with the catalytic combustion machine described above, and even if the combustion amount is constant,
The problem with the cape was that it was necessary to set the air ratio in a narrow area.

Jin's invention was developed to eliminate the above-mentioned drawbacks of the conventional device, and the catalytic reaction layer was formed in the shape of a heat exchanger to realize an arbitrary temperature.
Seven objectives are to provide a safe catalytic combustion device with a wide input variable range.

Hereinafter, one embodiment of Jin's invention will be specifically explained based on FIGS. 4 and 5. In FIG. 4, parts corresponding to 1(g) are given the same reference numerals for explanation. 3I is a cross-flow shaped catalyst layer 1 FIG. 5(a), Φ) K1 shows its detailed shape. It is also a controller that controls the rotation of the tactile cooling air blower @10 in accordance with the signal from the 9 company temperature sensor &. The above-mentioned cross-flow catalyst layer 3' line, a corrugated sheet or a plurality of ceramic or heat-resistant gold ingots formed with a number of thin plate-like fins t' parallel to -1 of the flat plate on the thin plate are formed as a unit. The fins are stacked with their axial directions perpendicular to each other.

Next, the operation according to the present invention configured as described above will be explained. First, the excess Ntj until steady combustion is reached
- It is performed using the same movement as the example in Figure 1 above, but
The air ratio of the premixture is set to μ = 1.1 to 1 to increase the force efficiency.
5@[lC selected. Since the flame ignited by the igniter 4 twists at a high temperature, the catalyst layer quickly heats up.
The emission of harmful gas components (CO, HC) during fires can be kept to a low level*. When the catalyst layer is heated to 600 to 700't:, cooling air is supplied to the blower 10 via the 11 degree detector 5 and the controller 9. 'i? - Blower 1 to maintain within range
00 rotation speed is controlled. According to Jin's invention, even if the air ratio fluctuates or the combustion lid changes, by reducing the cooling air volume by tiiiit, the catalyst layer can be set at the optimal temperature, so the combustion lid can be adjusted to a significantly lower temperature than K114. At the same time, it is possible to provide a highly efficient catalytic combustion device with a large margin for 9-air ratio fluctuation #C. Furthermore, since combustion heat is partially exchanged in the cross-flow catalyst layer, the convection heat exchanger 7 can be made smaller in size, and the blower 8 can also have a smaller capacity. In addition, it is desirable to configure the premixed air passageway shape of the crossflow catalyst layer so that the contact area between the premixed air and the catalyst layer is large, but this is not the case.

It has also been found that if the diameter is approximately 3 mm or less, the catalytic reaction can be carried out in a fractional manner.

In addition, although Fig. 1114 shows a case in which a frame gas fuel is used in the air supply, vaporized gas of liquid fuel such as kerosene may also be used, and the voltage applied to the blower motor may be used to control the cooling air volume Alternatively, the rotational speed r may be controlled by changing the rotation speed r, or alternatively, the air flow rate ki may be controlled using a damper installed in the air path or other means. Also cooling fluid #
In addition to air, it is also possible to use water, etc. for C.

As described above, according to the present invention, the catalyst layer T of the catalytic combustion device is shaped like a cross-flow heat converter, and the premixed air Im passage wall of the cross 70-catalyst layer is coated with platinum.

I applied an oxidation catalyst such as palladium and fired it directly in the oven.I bought it as if it were made to be cooled and cooled, so it is easy to change the combustion amount to 6J, which is different from the conventional equipment9. By realizing an arbitrary mK', it was possible to obtain safety in the catalytic combustion device 1 with low thermal efficiency and a wide input variable range.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of a conventional catalytic combustion equipment. 2nd @Ju, graph showing catalyst temperature and combustion efficiency. Figure 3 is a graph showing the relationship between catalyst temperature and air ratio.
In the figure, a schematic explanation of the catalytic combustion device according to the present invention-0 No. 5 is shown.
Figure (2)) is a perspective view showing details of the cross-flow shaped catalyst layer according to the present invention. l...Blower, 2...Fuel supply device, 3''...Cross flow catalyst layer, 4...Igniter, 5...S degree detector, 7...Heat exchanger, 8 ...Blower, 9...
controller. lO: Catalyst cooling blower. % Applicant: Mitsubishi Electric Corporation Agent Makoto Kuzuno (5 others) Bone 3 t”a

Claims (4)

[Claims] (1) In a premixed catalytic combustion system* equipped with a fuel and air supply device, a mixing chamber, and a catalytic reaction layer, the catalyst layer is shaped like a cross-flow heat exchanger, and the premixture side of the cross-flow catalyst layer is A catalytic combustion device characterized in that a passage #C is coated with an oxidation catalyst such as platinum or palladium, and a cooling fluid is allowed to flow through the other crossing passage #C. (2) The above-mentioned cross-flow catalyst layer is formed into a ceramic or heat-resistant metal body in which a plurality of thin plate-like fins are formed in a corrugated thin plate or parallel to -rM of a flat plate on a thin plate, and the axis of the plural mktjl plates and fins is formed. The catalytic combustion device according to claim III, characterized in that the catalytic combustion device is constructed by stacking the catalytic combustion devices at right angles to each other in directions of %/m. (3) The equivalent diameter t of the premixture passage in the cross-flow catalyst layer is approximately 3 m+ or less, according to any one of claims 'a1 or 2. Combustion device. (4) A temperature detector for the cross-flow catalyst layer is provided, and the supply amount of the coolant is adjusted in accordance with the output signal of the temperature detector.
Combustion device according to any of paragraphs.