JPS5864413A - Catalytic combustion equipment - Google Patents

Abstract

PURPOSE:To keep the temperature of a catalyst constant at all times and consequently prevent the abnormality such as slip (blow-off) and the like from occurring by a method wherein the temperature of the catalyst is monitored with a temperature detecting element and an air flow controlling mechanism is controlled by the output of the element. CONSTITUTION:The catalytic combustion equipment burns the liquid fuel, which is supplied from a feed oil pipe 30 to a cone 27 and a rotating disc 28 so as to be dispersed to contact with the inside surface of a premixing chamber 18 in order to be evaporated there, by mixing with the air, which is fed through an air hole 12 in the premixing chamber 18, by means of mixing plates 29 and sending through a resistance plate 17 and a straightening plate 20 to the catalyst 22. In the equipment as described above, the temperature detecting element 24 is provided on the outer wall of a combustion tube 15 at the location, to which the catalyst 22 is installed. The temperature detection output is inputted to a controlling box 31 so as to be compared therein with the reference value in order to regulate the opening of a damper arranged at a suction port 6 by driving a servomotor 8 or to regulate the amount of air to be sucked.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention detects the temperature of the catalyst body during combustion and combustion in which a premixed gas of gaseous fuel and air is supplied to the oxidation catalyst body and flameless combustion is performed by a catalytic oxidation reaction. However, the present invention relates to a catalytic combustion device that controls the amount of air to be supplied based on this, and always performs stable catalytic combustion.

Generally, when fuel is catalytically combusted, if a larger amount of air is supplied than a predetermined amount, the amount that can be oxidized decreases as the passing speed increases, and the cooling effect of the extra air causes the temperature of the catalytic body to rise. decreases rapidly.

As a result, the reaction cannot be completed and carbon oxide and hydrocarbons, which are incomplete combustion components, are released, resulting in so-called slip. On the other hand, if the amount of air is decreased, in addition to the opposite effect described above, an increase in the amount of fuel decomposition and oxidation in the high-temperature atmosphere will be added, and the catalyst body, especially the premixed gas inflow side, will become particularly high temperature. come. Furthermore, if the inflow velocity of the premixed gas into the catalyst is lower than the flame propagation velocity and the catalyst surface temperature is higher than the ignition point, backing occurs and flame combustion starts before the catalyst. In this way, when slip occurs, odor is generated due to carbon oxide and unburned components, and when back occurs, the combustion cylinder and catalyst body are heated abnormally,
There were cases where the catalytic combustion device was damaged.

The present invention aims to solve the above-mentioned problems by monitoring the temperature of the catalyst body using a temperature sensing element and controlling the amount of air supplied so that a stable temperature is always obtained.

An embodiment in which the present invention is applied to a catalytic combustion apparatus using liquid fuel is shown in FIG. 1, and its structure will be explained below.

Reference numeral 1 denotes a cylindrical fan case with a bottom, and an air supply inlet 2 is provided at the bottom. A motor 4 inserted into the fan case 1 from the air supply inlet 2 on the center line is covered by a motor case 7 having an air supply inlet 6. Further, a servo motor 8 and a damper 9 driven by the servo motor 8 are provided outside the air supply chamber 6. On the other hand, the shaft 5 has a fan 1o
However, guide blades 11 are also fixed to the fan case 1,
They are arranged alternately in multiple stages. A fixing plate 13 having an air port 12 in the center is fitted to the other end of the fan case 1, and a combustion cylinder 15 is attached to the fixing plate 13 outwardly via a backing 14. A sheathed heater 16 is embedded in the side wall of the combustion tube 15 near the fixed plate 13, and a resistance plate 17 made of gold steel or punched metal is provided in front of the sheathed heater 16.
The space surrounded by the fixed plate 13 and the fixing plate 13 is configured as a vaporization premixing chamber 18. In front of the resistance plate 17 in the combustion tube 15, a spacer 19, a rectifying plate 2o having a rectifying effect, and a catalyst holding metal fitting 21 are installed, and are made of heat-resistant inorganic materials such as alumina, cordierite, mullite, silicon carbide, alumina titanate, etc. A catalyst body 22 supporting an oxidation catalyst made of platinum group metal or the like is formed into a honeycomb shape to serve as a carrier, and holding fittings 23 for fixing the catalyst body 22 are sequentially attached. A temperature detection element 24 is provided on the outer wall of the combustion tube 15 at the part where the catalyst body 22 is attached, so that the heat transmitted from the catalyst body 22 to the combustion tube 15 can be detected, and the temperature of the catalyst body 22 can be monitored secondarily. be. In this example, a sheath type thermocouple was used. Further, the tip of the combustion tube 15 is connected to a heat exchanger 25.

On the other hand, the ignition plug 26 is connected to the combustion tube 15 and the catalyst holding metal fitting 2.
1 and faces the vicinity of the current plate 2o. At the tip of the motor shaft 5, which reaches the vaporization premixing chamber within one day, there is a trapezoidal cone 27 whose diameter increases toward the tip from the motor 4 side, and a rotating plate 28 has small stirring blades at the peripheral end. The mixing plates 29 are fixed one after another. Further, the oil supply pipe 30 is set to pass through the fan case 1 and open above the cone 27. A control box 31 houses a control circuit that compares the thermoelectromotive force of the temperature detection element 24 with a reference voltage, drives the servo motor 8, and adjusts the degree of opening.

In the above configuration, the operation in a steady state of catalytic combustion will be described below.

Liquid fuel is supplied to the fuel supply pipe 30 by an electromagnetic pump (not shown).
through the rotating cone 27, and the cone 2
7 surface to the rotary plate 28, is scattered in the form of particles from the outer peripheral edge of the rotary plate 28 due to the circular force, and comes into contact with the inner surface, which is kept at a constant temperature by heat transfer from the front of the sheathed heater 16 and the combustion cylinder 15. Vaporize. On the other hand, the amount of air is controlled by the fan 1o and the damper 9, and the air is sent to the premixing chamber 18 from the air port 12. Here, after being sufficiently stirred and mixed with the vaporized fuel by the mixing plate 29, the resistance plate 17
, is rectified by the rectifier plate 2o, and sent to the catalyst body 22. The catalyst body 22 is in a high temperature state, and the premixed gas generates heat by combustion due to the action of the oxidation catalyst supported on its surface, keeping the catalyst body temperature constant and increasing the temperature to approximately 700 to 1,000 yen.
It flows into the heat exchanger 25 as combustion gas at .degree. Therefore, during steady combustion, there is no flame, and the catalyst body 22 undergoes a catalytic reaction or undergoes decomposition and oxidation in the high temperature atmosphere in the nitrogen cell of the catalyst body 22, leading to complete combustion. If it fluctuates and exceeds the allowable range, it will cause abnormalities such as slipping or buckling. Slip occurs when the amount of air is excessive, leading to a decrease in the temperature of the catalyst body 22 and a decrease in the activity of the oxidation catalyst, and causes carbon oxide and unreacted components to be discharged. Conversely, backing occurs when the amount of air is insufficient, and as the temperature of the catalyst body 22 increases and the amount of decomposition and oxidation reaction increases in a high temperature atmosphere,
When most of the fuel reacts on the premixed gas inflow side and the premixed gas inflow speed is less than the flame propagation speed, the premixed gas burns with flame before it reaches the catalyst body 22. Therefore, if backing occurs, the combustion tube 16 may be heated abnormally, the life of the catalyst body 22 may be shortened, and the catalyst body 22 may be melted depending on the caking.

In this way, catalytic combustion can be maintained in a normal state by controlling the amount of air supplied.

That is, if the amount of air supplied is appropriate, the temperature of the catalyst body can be maintained at an appropriate level, and stable catalytic combustion can be obtained. The present invention attempts to control catalytic combustion by considering the relationship between the amount of supplied air and the temperature of the catalyst body.

Figure 2 shows that when the fuel supply amount is constant, the maximum temperature of the catalyst changes as the reading rate changes within the catalyst in response to changes in air amount (changes in excess air ratio). It is fully possible to monitor the temperature of the catalyst body as it fluctuates as the temperature changes. That is, in the state shown in FIG. 2, the damper may be adjusted so that the temperature of the temperature sensing element falls within the range of 300 to 380°C. Specifically, a thermocouple is used as a temperature sensing element, and its electromotive force is compared with a reference voltage (voltage that ranges from 3oO to 380℃ for a K thermocouple).If it is high, the damper is opened, and if it is low, it is This is possible by driving the damper in the closing direction. In the example, the temperature sensing element was installed on the side wall of the combustion tube, but
It is also possible to monitor the temperature of the catalyst by detecting radiation from the catalyst by facing the rear of the catalyst. Further, although a damper is used to control the amount of air, a method of controlling the amount of supplied air by controlling the motor rotation speed will have the same effect.

To directly measure the temperature of the catalyst, 1400-1500
Although it is necessary to select a temperature sensing element that can withstand high temperatures of ℃ or higher, catalytic combustion can be easily controlled by secondarily and indirectly monitoring the temperature of the catalyst as in the present invention. It has become possible. In addition, by automatically adjusting the amount of air and keeping the temperature of the catalyst body constant, abnormalities such as slip and back-up can be prevented, and abnormalities that may occur as a result of abnormalities can be prevented. −
It is also possible to prevent phenomena such as the generation of carbon oxides and odors, abnormal heating of the combustion cylinder, and accelerated deterioration of the catalyst.

In the example, an apparatus for liquid fuel is shown, but the effects of the present invention do not change in any way even when gas fuel is used.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a catalytic combustion device for liquid fuel showing an embodiment of the present invention, and FIG. 2 shows the maximum temperature of the catalyst body and the 1 is a diagram plotting the indicated temperature of the temperature sensing element installed as shown in Figure 09...Damper, 16...
・Combustion tube, 22...Catalyst body, 24...
Temperature sensing element.

Claims (1)

[Claims] A catalytic combustion device comprising means for supplying a premixed gas of fuel and air, and a catalyst body supporting an oxidation catalyst, the premixed gas being oxidized and burned by the catalyst body, wherein the temperature of the catalyst body is A catalytic combustion device equipped with a temperature sensing element that monitors temperature, and an air amount adjustment mechanism that is controlled based on the temperature detected by the temperature sensing element.