JPH06331108A - Combustion device - Google Patents

Abstract

PURPOSE:To prevent smell, from generating upon ignition or extinguishment of fire, and improve the start of combustion efficiently in a short period of time with a compact constitution by a method wherein a conductive catalyst body, capable of generating heat by excitation, is provided in a fuel supplying space near a combustion plate. CONSTITUTION:A combustion plate 3, having a multitude of flame ports 3a, is provided at the downstream opening of a mixing tube 1 while a conductive catalyst body 5, capable of generating heat by excitation, is provided in a fuel supplying space or a mixture chamber 4 near the lower part of the combustion plate 3. The conductive catalyst body 5 is ignited upon igniting and/or extinguishing fire and the temperature of the catalyst is increased to a catalyst activating temperature. On the other hand, a fire detector 21 is provided above the combustion plate 3 while the operating level of the fire detector 21 is set lower than the time of stationary combustion when the conductive catalyst body 5 is excited or upon ignition and extinguishing fire. According to this method, smell or while smoke, readily generated upon igniting and/or extinguishing fire, is prevented and preheating as well as ignition can be finished in a short period of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion device for burning a supplied fuel on a combustion plate.

[0002]

2. Description of the Related Art As a conventional combustion apparatus, a mixture of fuel and combustion air is ignited and burned by a discharge using an ignition heater or an ignition transformer on a combustion plate (burner) made of metal or ceramic. There is something. In this case, because the combustion area is spread over the entire plate by flame propagation from one point on the combustion plate, it is unavoidable that a part that causes ignition delay occurs, especially in the case of initial ignition where the ambient temperature is low. is there. As for odor,
Even if the combustor installed outdoors or the combustor installed indoors is a combustor of forced air supply / exhaust type, it is almost unnoticeable, but it is uncomfortable when the fan heater is open indoors.
Even with a good combustion plate that has improved combustion during steady combustion, the problem of odor at the time of ignition and extinguishing is difficult to solve.

[0003]

[Problems to be Solved by the Invention] Under these circumstances,
A combination with catalytic combustion is possible. However, when the catalyst body is simply used for the combustion plate, in addition to the above-mentioned problems, the following problems occur, which is a disadvantage that cannot be improved.

That is, the temperature of the back surface (upstream side) of the combustion plate rises and the temperature near the combustion plate rises, causing flashback. This is especially true for some premixed burners with a low air ratio. If the amount of catalyst supported is reduced, the temperature will decrease, but the reaction gas will not be able to be completely processed, causing incomplete combustion. If the volume of the catalyst body and the size of the air-fuel mixture chamber on the upstream side of the combustion plate are made large enough to increase the amount of air, it will be a solution, but it will be far from the aspect of making the combustion device compact. .

In order to carry out catalytic reaction combustion on the catalyst body,
It is necessary to keep the temperature above the temperature at which the catalyst is sufficiently active with respect to the reaction gas. Usually, in a combination of a noble metal catalyst such as platinum (Pt) and palladium (Pd) and a hydrocarbon fuel, this temperature is at least about 300 ° C. That is, sufficient reaction does not occur unless the temperature reaches about 300 ° C. In an actual device, since the temperature of the catalyst body is lowered to the ambient temperature at the time of ignition, even if the reaction gas is supplied as it is, the reaction gas is not ignited and the unreacted gas is exhausted. Therefore, it is necessary to perform an ignition operation such as preheating the catalyst body and then supplying the reaction gas. As a general preheating method, a method is used in which a preheating burner or a preheating heater is provided on the upstream side of the catalyst body, the air is heated once, and the heated air is fed into the catalyst body to preheat the catalyst body. When such preheating is performed, there are many problems as described below.

In both cases of the preheating burner and the preheating heater,
It is inefficient because the catalyst body is indirectly preheated after heating air as a heat medium. That is, it is necessary to heat a large amount of air in addition to the catalyst body, and the surrounding air passages are also heated at the same time, which leads to a large waste of energy and a long time.
In addition, it is unavoidable that the preheated air itself has temperature unevenness, and therefore the temperature of the catalyst body also has unevenness, and the reaction gas passing through the low temperature portion during ignition passes through the catalyst body without reaction,
Problems such as odor and white flame occur. Further, since it is necessary to provide a space for installing the preheating burner or the preheating heater, there is a drawback that the device becomes large. It also leads to an extra cost increase.

When an oil burner is used as the preheating burner, more time is required because the preheating burner itself has a rising time such as the preheating time of the carburetor. Moreover, since the preheating burner uses gas-phase combustion, NOx is naturally generated, and it is not preferable that the characteristics of low NOx are impaired even at the initial stage of ignition. Further, carbon is a type of catalyst poison, and even carbon (soot), which is slightly generated when the preheating burner is ignited or extinguished, may deteriorate the performance of the catalyst if it is adsorbed on the catalyst.

When the preheater is used, it is necessary to provide a large-capacity heater for heating the air, and the accompanying increase in the number of electric parts such as a large-capacity relay circuit and thick conductor that are not originally required in the combustion device. However, this causes a cost increase and a running cost increase.

Therefore, an object of the present invention is to prevent the odor that tends to occur during the extinguishing and extinguishing of a fire, and to efficiently start the combustion in a short time with a compact structure.

[0010]

In order to achieve the above-mentioned object, the present invention is, firstly, the combustion in which the fuel from the fuel supply means is supplied to the combustion plate forming the flame through the fuel supply space for combustion. In the apparatus, a conductive catalyst body capable of generating heat when energized is provided in the fuel supply space near the combustion plate.

Secondly, in the first structure, the conductive catalyst is energized at the time of ignition or extinction on the combustion plate.

Thirdly, in the second configuration, a flame detector is provided in the vicinity of the combustion plate, and the operation level of the flame detector is set to be lower than that during steady combustion while the conductive catalyst body is energized. is there.

[0013]

According to the first and second configurations, when the conductive catalyst is energized at the time of ignition or extinction, the temperature of the conductive catalyst rises and the supplied fuel is efficiently burned to cause the adhesion. Generation of odor during fire extinguishing is prevented. Since the catalyst body is preheated by self-heating by energizing the conductive catalyst body, compared to indirect heating using a heating medium such as air, no wasteful energy is generated, and in a short time. Preheat and complete ignition. Further, since the catalyst body can be uniformly preheated, discharge of unburned components is prevented, and clean ignition / extinguishing is possible. Further, since no extra space is required, the entire combustion apparatus becomes compact and cost reduction is achieved.

According to the third configuration, the operating level of the flame detector is set lower than that during steady combustion during energization of the conductive catalyst body, that is, during ignition or extinguishing, so that it is small during ignition and extinguishing. Erroneous detection such as determining the flame as abnormal combustion is prevented.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a combustion apparatus showing an embodiment of the present invention. This shows an example applied to a burner of an oil fan heater. This burner has a large number of flame ports 3a at the downstream side opening located at the upper part of the mixing tube 1 in the figure.
Is provided, and a conductive catalyst body 5 capable of generating heat when energized is provided in the air-fuel mixture chamber 4 as a fuel supply space near the lower portion of the combustion plate 3. A pair of electrodes 7 and 9 are attached to both ends of the conductive catalyst body 5,
The conductive catalyst body 5 is energized by a control device (not shown) at the time of ignition and extinguishing, and rises to the catalyst activation temperature.

A bell mouth-shaped fuel supply port 1a is formed on the lower side of the mixing tube 1. A carburetor 13 containing a carburetor heater 11 is arranged near the fuel supply port 1a. A fuel passage through which liquid kerosene fuel supplied from a fuel pump (not shown) passes is formed in the vaporizer 13, and the liquid fuel passing through the fuel passage is heated by the vaporizer heater 11 and vaporized. On the fuel supply port 1a side of the vaporizer 13, a fuel injection nozzle 17 is provided as a fuel supply means for ejecting the fuel vapor vaporized by the vaporizer 13 into the air-fuel mixture chamber 4. The fuel vapor injected from the fuel injection nozzle 17 entrains ambient air due to the ejector effect and becomes a mixture and is supplied into the mixture chamber 4. The combustion air may be supplied by a fan separately provided in addition to the method of supplying the combustion air by utilizing the ejector effect. The carburetor 13 is controlled to a constant temperature (300 ° C.) by the electric heater 11 driven by the above-described control device, and the fuel pump is also controlled by the control device to supply kerosene according to the difference between the room temperature and the set temperature. .

Above the combustion plate 3, an ignition heater 19 for igniting the air-fuel mixture supplied to the fuel plate 3 through the air-fuel mixture chamber 4 and a state of the flame 20 after ignition by ignition are detected to detect an abnormality. A flame detector 21 for stopping the supply of fuel is installed. The ignition heater 19 and the flame detector 21 are also operated by the control device described above, but the flame detector 21 is set to have a lower operation level when the conductive catalyst body 5 is energized, that is, when igniting and extinguishing, as compared with the steady combustion. In addition, erroneous detection such that a small flame at the time of ignition and at the time of extinguishing is determined to be abnormal combustion is prevented.

Next, FIG. 2 showing the control operation by the control device.
Also, the operation of the combustion device will be described based on the flowchart of FIG.

FIG. 2 shows the state at the time of ignition. When the heater is started, the heater 11 for the vaporizer and the conductive catalyst body 5 are energized (steps 201 and 203) to turn on the vaporizer 13 and the conductive catalyst body 5. Raise the temperature. When the temperatures of the vaporizer 13 and the conductive catalyst body 5 reach the set temperatures (steps 205 and 207), the ignition heater 19 is energized (step 209), and the kerosene corresponding to the difference between the room temperature and the set temperature becomes fuel. It is sent to the vaporizer 13 by the pump (step 211). Since the vaporizer 13 has risen to a predetermined temperature, the kerosene becomes vapor and is jetted from the fuel injection nozzle 17 toward the inside of the air-fuel mixture chamber 4 and entrains the ambient air to form a gas-air mixture in the air-fuel mixture chamber 4. Flows in.

The air-fuel mixture flowing into the air-fuel mixture chamber 4 reaches the electroconductive catalyst body 5, and the electroconductive catalyst body 5 having reached the set temperature starts a catalytic reaction. Then, after an unstable period at the beginning of combustion has passed, combustion is performed on the combustion plate 3 by the preheated ignition heater 19. When a flame is detected by the flame detector 21 in such a combustion process (step 213), the energization of the ignition heater 19 is stopped (step 215) and the steady combustion is performed (step 21).
7). Although the flame at the time of ignition is smaller than that at the time of steady combustion, since the flame detector 21 sets the operation level at the time of ignition / extinction to a low level, this small flame is not judged as abnormal combustion. The burned gas is heated by a convection fan (not shown).

FIG. 3 shows the operation at the time of extinguishing a fire. At the time of extinguishing the fire, by controlling the operation of the heater, the fuel pump is controlled to reduce the fuel supply amount until the preset combustion amount is reached (step 301), and at the same time, the conductive catalyst body 5 is energized (step 303). . When the conductive catalyst body 5 reaches the set temperature (step 305), the fuel supply is stopped (step 307). Thereafter, when the temperature of the conductive catalyst body 5 falls below the set temperature (step 309), it is determined that the supplied fuel has completely burned, and the power supply to the conductive catalyst body 5 and the carburetor heater 11 is stopped (step 311).
313). Even at this time of extinguishing, the flame is smaller than that at the time of steady combustion, but since the flame detector 21 sets the operation level at the time of extinguishing the fire to a low level, this small flame is not judged as abnormal combustion.

As described above, in order to preheat the catalyst body by self-heating due to the energization of the conductive catalyst body 5, wasteful energy is generated as compared with indirect heating using a heat medium such as air. It does not occur, and it preheats in a short time and ignition is completed. Furthermore, since the entire conductive catalyst body 5 can be uniformly preheated, discharge of unburned components is prevented, and odor and clean extinguishing can be performed. Since a preheating burner and a preheating heater are not required, an extra space is not required, the entire combustion apparatus becomes compact, and the cost is reduced. Further, since the conventional combustion plate 3 and its peripheral component parts can be used, the thermal power adjustment range can be widened as compared with the case where the catalyst body is used for the combustion plate. Since the conductive catalyst body 5 is energized only at the time of ignition and extinguishing, it can be used at a low temperature for a short time and can have a long life.

The carrier of the conductive catalyst 5 is a honeycomb structure of ceramic or metal, or a laminate of foils,
The plate may be provided with a plurality of flame openings, or may be foamed or net-shaped. However, when the material is a metal, the surface of the material is subjected to a non-conductive treatment, and then a catalyst peeling prevention treatment is performed to support the catalyst.

[0025]

As described above, the first and second
According to the invention, since the conductive catalyst body capable of generating heat by energization is provided in the fuel supply space near the combustion plate to preheat the conductive catalyst body, the following effects can be obtained.

(1) It is possible to prevent the generation of odors by preheating at the time of extinguishing the fire.

(2) Since the conductive catalyst body is directly heated by electricity, it can be preheated efficiently in a short time.

(3) Since the conventional components around the combustion plate can be used, the thermal power adjustment range can be widened as compared with the case where the catalyst body is used for the combustion plate.

(4) Since the heater and burner dedicated to preheating are not required, the installation space is not required, and the apparatus itself can be made compact.

(5) Since the conductive catalyst is used only at the time of ignition or extinguishing, it can be used at a low temperature for a short time and a long life can be achieved.

According to the third aspect of the present invention, the operation level of the flame detector provided near the combustion plate is set lower than during steady combustion while the conductive catalyst is energized, so that a small flame during ignition and extinguishing It is possible to prevent erroneous detection such as determining that the combustion is abnormal.

[Brief description of drawings]

FIG. 1 is a sectional view of a combustion apparatus showing an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation at the time of ignition in the combustion device of FIG.

FIG. 3 is a flowchart showing the operation of the combustion apparatus of FIG. 1 when extinguishing a fire.

[Explanation of symbols]

 3 Combustion Plate 5 Conductive Catalyst 17 Fuel Injection Nozzle (Fuel Supply Means) 21 Flame Detector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Kubota 8 Shinsita-cho, Isogo-ku, Yokohama, Kanagawa Kanagawa, Ltd. In the Institute for Living Space Systems Technology Co., Ltd. (72) Yuka Kawabata 8 Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa Banchi Co., Ltd. Toshiba Living Space Systems Engineering Laboratory

Claims (3)

[Claims] 1. In a combustion device for supplying fuel from a fuel supply means to a combustion plate forming a flame through a fuel supply space and burning the same, a conductive material capable of generating heat by energizing the fuel supply space near the combustion plate. A combustion device provided with a catalyst body. 2. The combustion apparatus according to claim 1, wherein the electrically conductive catalyst is energized at the time of ignition or extinction on the combustion plate. 3. A flame detector is provided in the vicinity of the combustion plate,
The combustion apparatus according to claim 2, wherein the operation level of the flame detector is set to be lower than that during steady combustion during energization of the conductive catalyst body.