JPH03164617A - Catalyst combustion device - Google Patents

Abstract

PURPOSE:To prevent any trouble due to abnormal operation of a catalyst layer by detecting the existence of harmful combustible gas by detecting a change in detected temperature by an auxiliary catalyst layer temperature detector element or a deviation between the detected temperature and an initial set value. CONSTITUTION:Whilst a catalyst combustion device is operated and a combustion catalyst layer 1 is preheated for transition to a stationary combustion state, an auxiliary catalyst layer 2 is also heated by high temperature waste gas discharged from the combustion catalyst layer 1 and is stabilized after reaching a catalyst activation temperature of about 210 deg.C or higher. Once abnormality is produced on the catalyst combustion device, harmful combustible gas is discharged which gas is mainly oxidized and combusted at an inlet of the auxiliary catalyst layer 2 to raise temperature. The abnormality is decided when said temperature changes to a higher temperature by 10 to 20 deg.C than stable temperature detected at the inlet side of the auxiliary catalyst layer 2, and fuel is interrupted but operation of a fan 16 is continued for extinguishment and cooling. Hereby, an abnormality lamp is lighted. Also when the combustion catalyst layer 1 is deteriorated, the abnormality is decided when the harmful gas is discharged and the inlet temperature of the auxiliary catalyst layer 2 is detected to be higher about 20 deg.C than a normal one.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a catalytic combustion device used for heating by flamelessly burning gaseous or liquid fuel in a combustion catalyst layer.

<Prior Art> The catalytic combustion method generally has higher radiant energy efficiency than the conventional flame combustion method, is a heating method rich in far infrared rays, and has the advantage of emitting almost no CO or NOx. However, as platinum group metal catalysts such as platinum and palladium supported in the catalytic combustion layer continue catalytic combustion over a long period of time, their activity gradually decreases and their initial characteristics deteriorate, resulting in incompletely burned components and unburned components. Harmful flammable gas consisting of components, etc. will be emitted.

Further, even if some abnormality occurs in the catalytic combustion device and stable combustion is not possible, harmful combustible gases may be emitted, which has a negative effect on the human body.

As a conventional means for detecting the life of the combustion catalyst layer of the above-mentioned catalytic combustion device and the emission of harmful combustible gases, for example,
As described in Publication No. 53601, a temperature detection element is provided on the upstream side of the combustion catalyst layer, and if the detected temperature becomes higher than that during stable combustion, it is considered a backfire, and if it becomes lower, it is considered as a blowout and these abnormalities are detected. There are known devices that detect this and cut off the fuel supply.

<Problems to be Solved by the Invention> In the conventional method as shown in the above-mentioned Japanese Patent Publication No. 61-53601, when the opening area of the combustion catalyst layer is relatively large, one temperature sensing element can cover the entire area of the combustion catalyst layer. It is difficult to detect temperature, and in particular, if slip age occurs locally due to the distance between the temperature detection element and the combustion catalyst layer, it cannot be detected accurately.
It is difficult to prevent the emission of harmful flammable gases.

Means for Solving the Problems> The present invention provides a catalytic combustion device for flameless combustion of gaseous or liquid fuel, converting the combustion heat into width-to-air heat mainly consisting of far infrared rays, and using it for space heating. , an auxiliary catalyst layer is provided in the path through which the exhaust gas passes through the combustion catalyst layer to purify the exhaust gas by burning harmful combustible gases such as incompletely combusted gas and unburned gas. A temperature detection element for detecting temperature is provided so that abnormal combustion can be determined when the detected temperature changes or deviates from the initial value.

Function> After preheating, when some abnormality occurs in the catalytic combustion device during steady combustion and harmful flammable gas is generated in the combustion catalyst layer, the harmful flammable gas is burned in the auxiliary catalyst layer. The temperature at the inlet of the auxiliary catalyst layer rises rapidly. This is detected by the temperature detection element, recognized as an abnormal operation, and the combustion of the catalytic combustion device is stopped.

Alternatively, even when harmful combustible gas is generated due to deterioration of the combustion catalyst layer, the temperature at the inlet of the auxiliary catalyst layer takes a higher value compared to the initial normal state.

This is detected by the temperature detection element, recognized as an operational abnormality, and combustion in the catalytic combustion device is similarly stopped.

<Example> An embodiment of the present invention will be described below.

FIG. 1 is a schematic cross-sectional view of the front surface of the catalytic combustion apparatus of the present invention, and FIG. 2 is a schematic cross-sectional view taken along line LL' in FIG. 1 from the side. Reference numeral 1 denotes a combustion catalyst layer in which a platinum group metal catalyst such as platinum or palladium is supported on a honeycomb-shaped carrier made of a heat-resistant inorganic material that has excellent far-infrared radiation efficiency. It is attached to the section. A one-side ejector burner 6 and a vaporizer 7 are provided at the bottom of the mixing chamber 5, and a decompression chamber 12 is provided at a part of the lower part of the mixing chamber 5.
There is a throat hole 6A of the burner 6 on one side, and a fuel injection nozzle 7A of the carburetor 7 is on the opposite side.

A primary air port 17 is provided at the front of the decompression chamber 12 . A plurality of appropriately sized secondary air ports 18 are opened at the bottom of the mixing chamber 5, and the upper part of the rear wall promotes the mixing and diffusion of combustion air and vaporized fuel, and spreads them evenly over the combustion catalyst layer l. A diffusion plate 8 and a combustion catalyst layer temperature detection element 13 are attached. Further, the outer periphery of the mixing chamber 5 except for the front side is provided with a pressurizing chamber 9, a shielding plate 11, and a heat exchange duct 10 for preheating combustion air sent from a blower 16. The exhaust gas flow path in the front space on the exit side of the combustion catalyst layer I is partitioned off from the outside by a heat-transmitting glass plate 3.
Above the exhaust gas flow path, there is an auxiliary catalyst layer 2 in which a honeycomb-shaped carrier made of a heat-resistant inorganic material supports a platinum group metal catalyst in an amount of 1 to 2 g/l, and an inlet side of the auxiliary catalyst layer 2. An auxiliary catalyst layer temperature detection element 4 is provided to detect the surface temperature of the catalyst layer. Note that the heat-transmitting glass plate 3 may be a wire mesh guard as long as all the exhaust gas discharged from the combustion catalyst layer 1 passes through the auxiliary catalyst layer 2 due to natural convection.

Next, the operation of the embodiment of the present invention will be described.

First, the heater (not shown) built into the vaporizer 7 and the ignition heater 14 are energized, and when the temperature of the vaporizer 7 reaches 250 to 300°C, the oil feed pump (not shown) is activated to vaporize the vapor. Liquid fuel is fed into the vessel 7, vaporized, and ejected from the ejection nozzle 7A. Air blower 16 at the same time
operates, and the combustion air is transferred from the pressurized chamber 9 to the heat exchange duct) IO.
A part passes through the primary air port 17 to the burner 6, and the rest passes through the secondary air port +8 to the mixing chamber 5. Thereafter, a constant amount is sent until the fire is extinguished. The amount of air sent to the burner 6 is determined by the ejector effect (suction effect) when liquid fuel is ejected from the ejection nozzle 7A and the blower 16.
It is determined by the amount of air pumped from the primary air port 17 and the opening area of the primary air port 17. Since the amount of air to be pumped is constant, - The opening area of the large air port 17 is adjusted in advance to adjust the air ratio to 1.0 to 1.5, which is suitable for flame combustion in a burner for preheating.
Let the range be . The premixed gas sent out from the burner 6 is ignited by the ignition heater 14 and burns with flame on the upper surface of the burner 6. The amount of combustion at this time can be adjusted by the amount of oil fed to the carburetor 6.

Even if the power supply to the ignition heater 14 is cut off after a certain period of time, flame combustion continues on the upper surface of the burner 6, and the high-temperature combustion gas generated by the flame combustion mixes with secondary air to preheat the combustion catalyst layer 1. do. When the combustion catalyst layer temperature detection element 13 detects that the temperature of the combustion catalyst layer l has reached the activation temperature or higher, the oil feed pump is stopped to stop flame combustion. If the oil feed pump is operated again after the flame combustion has stopped, the power to the ignition heater 14 remains cut off, so the premixed gas is sent to the mixing chamber 5 via the burner 6 without being ignited, and the secondary air is Approximately 2 to 4 particles suitable for catalytic combustion by mixing with the secondary air sent in from the port 18
The air ratio is increased to , and the air is fed into the combustion catalyst layer 1 to start catalytic combustion.

The combustion catalyst layer l is made to have a thickness that has a space velocity sufficient for complete combustion of the premixed gas, ignites and raises the temperature without emitting harmful combustible gas, and maintains a steady combustion state. Become. FIG. 3 shows an example of detection of the inlet temperature of the auxiliary catalyst layer 2 by the auxiliary catalyst layer temperature detection element 4, where the solid line indicates the temperature when combustion is normal, and the dashed-dotted line indicates the temperature when abnormal combustion occurs. The figure shows the rise in temperature and the change in temperature when the operation is stopped after abnormal combustion has been determined. When the catalytic combustion device starts operating, while the combustion catalyst layer 1 is preheated and transitions to a steady combustion state, the auxiliary catalyst layer 2 is also heated by the high temperature exhaust gas discharged from the combustion catalyst layer I, and its temperature rises. , it reaches a temperature of about 210° C. or higher, which is the catalyst activation temperature, and becomes stable. The temperature at the inlet of this auxiliary catalyst layer 2 is determined by the amount of combustion in the combustion catalyst layer 1. Now, when some kind of abnormality occurs in the catalytic combustion device and a harmful amount of combustible gas is discharged from the combustion catalyst layer 2 which would be harmful if combustion continues as it is, the cross-sectional temperature distribution diagram of the auxiliary catalyst layer 2 shown in Fig. 4 As shown in , since the harmful combustible gas is mainly oxidized and burned at the inlet of the auxiliary catalyst layer 2, the temperature at the inlet increases more rapidly than the temperature at the outlet. Therefore, when the temperature changes to a value that is at least 10 to 20 degrees Celsius higher than the stable temperature detected at the inlet side of the auxiliary catalyst layer 2 corresponding to each combustion amount, it is determined that there is an abnormality and the supply of liquid fuel is immediately stopped. The blower 16 is shut off, and the blower 16 continues to operate to extinguish the fire and cool the air, and at the same time, turns on the abnormality lamp. Note that this abnormality determination is not performed during preheating for 2 to 3 minutes after the start of operation and in a transient state such as when the combustion amount is switched from weak combustion to strong combustion. Furthermore, even when combustion catalyst layer 1 deteriorates, harmful combustible gases are emitted, so the temperature at the inlet of auxiliary catalyst layer 2 is lower than the value initially stored as a normal value or the set value. approximately 2 times higher than the normal value corresponding to the amount of combustion.
When a value 0°C higher is detected, it is determined that there is an abnormality, and the fire is promptly extinguished and cooled in the same way, and the abnormality lamp is turned on.

<Effects of the Invention> As in the present invention, in a catalytic combustion device in which an auxiliary catalyst layer is provided in a path through which exhaust gas passes through the combustion catalyst layer, an auxiliary catalyst layer temperature detection element is provided to detect changes in the detected temperature or the initial state. By looking at the deviation from the set value, it is possible to know the presence of harmful combustible gas in the exhaust gas, and it is possible to prevent accidents due to abnormal operation of the catalytic combustion device or deterioration of the combustion catalyst layer.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of the front side of the catalytic combustion apparatus of the present invention. FIG. 2 is a schematic sectional view taken along line LL' in FIG. 1 from the side. FIG. 3 is a state diagram showing the temperature at the inlet of the auxiliary catalyst layer during normal combustion and abnormal combustion, as detected by the auxiliary catalyst layer detection element. FIG. 4 is a temperature distribution diagram of a cross section of the auxiliary catalyst layer. DESCRIPTION OF SYMBOLS 1... Combustion catalyst layer, 2... Auxiliary catalyst layer, 4... Auxiliary catalyst layer temperature detection element, 6... Burner 7... Vaporizer, 9... Heat exchange duct, 15...・Warm air outlet, 16...Blower.

Claims (1)

[Claims] 1. A combustion catalyst layer for flameless combustion of gaseous or liquid fuel, and an auxiliary catalyst for purifying unburned or incompletely burned gas in a path through which exhaust gas passes. A catalytic combustion device provided with layers, characterized by being provided with a temperature detection element for detecting the temperature of the auxiliary catalyst layer, and a determination means for outputting a combustion state determination signal based on the output of the temperature detection element. Catalytic combustion equipment.