JP2001272007A - Catalytic combustion heating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalytic combustion heating equipment in which a catalyst can be heated efficiently by stabilizing the combustion by a pilot burner, and by using generated exhaust combustion gas, which is returned partly after shifting to a steady operation to well preheat the premixed gas and improve the thermal efficiency. SOLUTION: A premixed gas of the liquid fuel injected from a fuel nozzle 18 and combustion air introduced into an inner tube 11 is ignited by an ignition equipment 19 in the case of a pilot combustion. In the pilot combustion, the generated exhaust combustion gas heats the catalyst, but the exhaust combustion gas is not returned to the peripheral space of the inner tube 1. While in the case of the steady combustion, the exhaust combustion gas is returned though an exhaust combustion gas return tube 12 to the outer peripheral space of the inner tube 11 to heat it, and fuel adhered to the internal peripheral face of the tube 11 is vaporized, and the premixed gas is preheated, and mixed with exhaust combustion gas by a mixing equipment 15 to be starred and mixed, the mixture is sent to a catalytic combustion device 17 in a catalyst tube 16 to carry out a catalytic combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic combustion type heating apparatus in which a premixed gas of a liquid fuel and combustion air is catalytically combusted, heating is performed by generated combustion exhaust gas, and the premixed gas is preheated. Things.

[0002]

2. Description of the Related Art Catalytic combustion is characterized in that it can be burned without forming a flame. However, in order to activate a catalyst, it is necessary to maintain the activation temperature at a predetermined value or higher. Preheats a premixed gas of fuel and combustion air supplied to the fuel cell.

Conventionally, as a method of preheating a premixed gas, as shown in Japanese Patent Application Laid-Open No. 30908/1985, a premixed gas of combustion gas and combustion air is burned using a pilot burner to generate gas. The catalyst is heated by the combustion exhaust gas, a part of the combustion exhaust gas that has passed through the catalyst is refluxed, mixed with the premixed gas, and preheated.

[0004]

However, in the above-described structure, the combustion exhaust gas is directly recirculated to the space where the flame is generated by the pilot burner, so that the combustion becomes unstable and the exhaust gas component becomes non-uniform. There is a risk.

[0005] In addition, since the low-temperature flue gas that has passed through the catalyst that has not been sufficiently heated is recirculated from the start of the combustion of the pilot burner, the temperature of the combustion atmosphere is reduced, and the temperature of the flue gas is also reduced. It takes time to heat sufficiently.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and can stabilize combustion by a pilot burner, efficiently heat a catalyst with generated flue gas, and shift to a steady operation. Thereafter, it is an object of the present invention to provide a catalytic combustion type heating device that recirculates a part of the combustion exhaust gas, preheats the premixed gas satisfactorily, and improves thermal efficiency.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method of burning a premixed gas of a liquid fuel and combustion air with a catalyst and using the heat of the generated combustion exhaust gas. In a catalytic combustion type heating device that performs heating and preheats the premixed gas, a liquid fuel injection device that injects the liquid fuel for the catalytic combustion and pilot combustion, and the liquid that is injected for the pilot combustion An ignition device for igniting fuel, an inner cylinder including the liquid fuel injection device and the ignition device therein, and introducing the combustion air into the interior to premix with the injected liquid fuel; and A part of the combustion exhaust gas is recirculated to the outer peripheral space of the combustion exhaust gas introducing section for preheating the premixed gas by heating the inner cylinder, and a premixed gas flowing out of the inner cylinder. A mixing section that mixes the combustion exhaust gas flowing out from the combustion exhaust gas introduction section and guides the mixed gas to the catalyst; and a combustion that stops supplying the combustion exhaust gas to the outer peripheral space of the inner cylinder during the pilot combustion. Exhaust gas supply control means.

In this configuration, first, in the inner cylinder, a premixed gas of the liquid fuel injected from the liquid fuel injection device and the introduced combustion air is ignited by an ignition device to perform pilot combustion, and the catalyst is removed. Heat. At this time, the entire amount of the combustion exhaust gas is used for heating the catalyst. However, under the control of the combustion exhaust gas supply control means, the combustion exhaust gas is not returned to the outer peripheral space of the inner cylinder from the combustion exhaust gas introduction portion, and the inner cylinder is not cooled. That is, during the pilot combustion, the supply of the combustion exhaust gas is cut off and the combustion is performed using only the combustion air, so that the pilot combustion is stabilized without being unstable by the recirculated combustion exhaust gas, and the temperature of the combustion atmosphere is reduced. There is no.

After the completion of the pilot combustion, steady operation is performed. At this time, by the control of the combustion exhaust gas supply control means,
The flue gas is recirculated from the flue gas introduction portion to the outer peripheral space of the inner cylinder, and the inner cylinder is heated. As a result, the atmospheric temperature in the inner cylinder is increased, the premixed gas of the injected fuel and the combustion air is preheated, and the liquid fuel attached to the inner peripheral surface of the inner cylinder is vaporized. The premixed gas flowing out of the inner cylinder is mixed with the combustion exhaust gas flowing out of the combustion exhaust gas introduction section in the mixing section, and is heated by the heat of the combustion exhaust gas. The mixed gas of the premixed gas and the combustion exhaust gas is guided to the catalyst to perform catalytic combustion. In this way, at the time of catalytic combustion, by utilizing the heat of the high-temperature combustion exhaust gas, the liquid fuel attached to the inner peripheral surface of the inner cylinder is prevented from becoming a wall flow, and is quickly and sufficiently promoted to vaporize. The combustion air can also be preheated well. Also, by mixing the combustion exhaust gas with the premixed gas and using the oxygen, the supply of combustion air can be reduced,
The exhaust heat loss can be reduced by reducing the exhaust gas amount of the combustion exhaust gas.

[0010] The mixing section may include a mixing device for positively mixing the premixed gas and the combustion exhaust gas. In such a configuration, during the steady combustion, the mixing device actively mixes the premixed gas flowing out of the inner cylinder and the combustion exhaust gas flowing out of the combustion exhaust gas introduction section to make the distribution of the fuel in the mixed gas more uniform. Promotes catalytic combustion.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The catalytic combustion type heating device shown in FIG. 1 includes a combustion device 1 that performs pilot combustion and catalytic combustion,
Combustion air supply pipe 2 for supplying combustion air to combustion device 1
A radiator pipe 3 for transferring the combustion exhaust gas flowing out of the combustion device 1, a branch pipe 4 for returning a part of the combustion exhaust gas transferred by the radiator tube 3 to the combustion device 1, and a control device 10. This is a device that performs heating using the heat of the combustion exhaust gas and preheats the premixed gas.

The combustion device 1 is supplied with combustion air from a combustion air supply pipe 2, and the liquid fuel stored in a fuel tank 8 is supplied or cut off by a fuel pump 9. The combustion device 1 performs pilot combustion using a premixed gas of the supplied liquid fuel and combustion air, thereby heating the catalyst, stopping the pilot combustion after a lapse of a predetermined time, and performing catalytic combustion as steady combustion. Do only. Combustion device 1
From the combustion exhaust gas generated in the pilot combustion and the catalytic combustion.

The radiator tube 3 is provided with a blower 7 for promoting the transfer of the combustion exhaust gas. The radiator tube 3 radiates the heat of the flue gas to the outside while the flue gas is transferred inside to obtain a heating effect.

The branch pipe 4 is branched from the heat radiation pipe 3 on the downstream side of the blower 7, and is formed so that a part of the combustion exhaust gas returns to the combustion device 1. The branch pipe 4 is provided with a control valve 6 as combustion exhaust gas supply control means. The control valve 6 includes an electromagnetic valve or the like. By controlling the opening and closing of the control valve 6, the recirculation of the combustion exhaust gas from the branch pipe 4 to the combustion device 1 is stopped during the pilot combustion, and a part of the combustion exhaust gas is returned to the combustion device 1 only during the steady combustion.

The control device 10 is internally provided with a switch device and a timer (not shown), and in accordance with the switch operation, the opening and closing time of the fuel pump 9, the blower 7 and the control valve 6, and the ignition described later. The ignition time of the device 19 (FIG. 2) is controlled.

Next, the configuration of the combustion device 1 will be described. As shown in FIG. 2, the combustion device 1 includes an inner cylinder 11, a combustion exhaust gas supply cylinder 12, an outer cylinder 20, a mixing cylinder 14, and a combustion cylinder 16.
And a flue gas discharge tube 13 and the like.

The inner cylinder 11 is formed of a heat-resistant thin metal plate such as stainless steel into a cylindrical shape, and one end in the axial direction is communicated with the end of the combustion air supply pipe 2 shown in FIG. Introduce working air inside. Inside the inner cylinder 11,
A fuel nozzle 18 as a liquid fuel injection device and an ignition device 19 are provided.

The fuel nozzle 18 injects liquid fuel supplied by the fuel pump 9 shown in FIG. As the liquid fuel, kerosene, light oil, heavy fuel oil A and the like can be used.

The ignition device 19 includes electrodes, and generates electric fireworks at the start of the operation under the control of the control device 10. As a result, the mixed gas of the injected liquid fuel and the combustion air is ignited to generate a flame, and pilot combustion, which is burner combustion, is started.

The outer cylinder 20 has a cylindrical shape made of a heat-resistant metal sheet and is formed on the outer periphery of the inner cylinder 11. The inner cylinder 11 is airtightly fitted into one end wall in the axial direction, and the other end is communicated with the mixing cylinder 14.

The combustion exhaust gas supply cylinder 12 is formed in a cylindrical shape by a heat-resistant metal thin plate, and has one end communicating with the combustion exhaust gas outflow end of the branch pipe 4 shown in FIG. And is communicatively joined to the peripheral side surface.

The outer cylinder 20 and the flue gas supply cylinder 12 correspond to a flue gas introduction part. During steady combustion, the branch pipe 4
The high temperature (about 2
The combustion exhaust gas of 50 to 350 ° C. is bypassed by the outer cylinder 20 and introduced into the outer peripheral space of the inner cylinder 11 while heating the entire surface of the inner cylinder 11 with the combustion exhaust gas. Thereby, the inner cylinder 11
The outer peripheral surface of is uniformly heated, and the injected fuel adheres to the inner peripheral surface of the inner cylinder 11 to be vaporized as droplet fuel.
The premixed gas in the inner cylinder 11 is also preheated.

The mixing cylinder 14 is formed of a heat-resistant metal sheet into a cylindrical shape, and the downstream end is connected to the catalyst cylinder 16.
A mixing device 15 for positively mixing the premixed gas and the recirculated combustion exhaust gas is provided inside the mixing cylinder 14. The mixing cylinder 14 corresponds to a mixing section.

As shown in FIG. 3, for example, the mixing device 15 cuts a circular heat-resistant thin metal plate 30 in which a hole 32 for reducing pressure loss is formed at the center thereof, and a plurality of blade-shaped cut-and-raised portions. 31. Then, the premixed gas flowing out of the inner cylinder 11 and the combustion exhaust gas flowing out of the outer cylinder 20 are directed to a swirl flow by a plurality of wing-shaped cut-and-raised portions 31, and are stirred to promote mixing. Things. Further, as shown in FIG. 4, a device in which a circular heat-resistant metal closing thin plate 34 is bonded to the center of a circular heat-resistant punched metal plate 33 can be used as the mixing device 15. By having the heat-resistant metal closing thin plate 34,
Can mix well. A mixed gas (about 150 to 300 ° C.) of the premixed gas and the combustion exhaust gas by the mixing device 15 is sent to a catalytic combustor 17 disposed in a catalyst tube 16.

The catalytic combustor 17 is filled with a catalyst layer carrying a catalyst with a heat-resistant carrier. Catalytic combustor 1
The catalyst layer of No. 7 is preheated by the combustion exhaust gas at the time of pilot combustion, and quickly reaches the activation temperature. In the subsequent steady combustion, the mixed gas sent from the mixing device 15 is burned under the catalytic reaction. As the heat-resistant carrier, for example, cordierite, mullite, α-
Ceramics such as alumina and titania can be used. An active metal is used for the catalyst.
Examples thereof include platinum group elements such as platinum and palladium. The shape of the heat-resistant carrier can be a honeycomb shape, a granular shape, a pellet shape, a rod shape, or the like. The catalyst layer in which the heat-resistant carrier is granular, pellet-shaped or rod-shaped is used by filling it in a box-shaped or cylindrical-shaped container made of a heat-resistant metal such as stainless steel, and the honeycomb-shaped catalyst layer is formed to a required size. Is used as it is.

The flue gas discharge tube 13 is formed of a heat-resistant metal sheet into a cylindrical shape, and the downstream end is connected to the flue gas inflow end of the radiator tube 3 shown in FIG. The flue gas discharge tube 13 discharges the flue gas generated by the pilot combustion and the steady combustion to the radiator tube 3.

Next, the operation of the catalytic combustion type heating apparatus of the present embodiment will be described. At the start of the operation, the operation of the blower 7 is started under the control of the control device 10 based on the switch operation, and immediately after the electric spark is generated by the ignition device 19, the fuel pump 9 is operated to supply the liquid fuel from the fuel nozzle 18. Inject and start pilot combustion. The combustion exhaust gas generated by the pilot combustion heats the catalyst layer of the catalytic combustor 17 and performs catalytic combustion by itself, and is discharged to the radiating pipe 3 to release heat and perform heating. During this pilot combustion, the control valve 6 is controlled to be completely closed. Therefore, since the inner cylinder 11 is not cooled by the recirculation of the combustion exhaust gas by the pilot combustion, the catalyst heating is rapidly promoted. In addition, since the flame in the pilot combustion has no recirculated flue gas, it is not blown out by the flue gas or is not in an unstable state, so that the combustion is performed smoothly and stably and a misfire is prevented. To prevent.

After the catalyst layer is sufficiently heated to the activation temperature, the supply of the liquid fuel to the combustion device 1 is interrupted by the control of the fuel pump 9 to temporarily stop the pilot combustion. Thereafter, the supply of the liquid fuel to the combustion device 1 by the fuel pump 9 is started immediately, but the electric spark by the ignition device 19 is not generated. As a result, the premixed gas of the liquid fuel and the combustion air injected into the inner cylinder 11
1 to the mixing cylinder 14, agitated and mixed together with the combustion exhaust gas flowing through the outer peripheral space of the inner cylinder 11, and sent to the catalyst combustor 17 of the catalyst cylinder 16 to start steady catalytic combustion. .

The combustion exhaust gas generated by the catalytic combustion is discharged to the outside through the radiator tube 3 and a part of the exhaust gas flows into the branch tube 4 as described above. Further, the control valve 6 is controlled to be fully opened, and the combustion exhaust gas diverted from the heat radiation pipe 3 is returned to the combustion device 1 via the branch pipe 4.

The high temperature combustion exhaust gas is recirculated to the outer peripheral space of the inner cylinder 11 and heats the outer peripheral surface of the inner cylinder 11.
The fuel adhering to the inner peripheral surface of the inner cylinder 1 is vaporized and the inner cylinder 1
The premix gas in 1 is preheated.

Therefore, the premixed gas generated in the inner cylinder 11 is heated in the inner cylinder 11 while the droplet fuel is vaporized by heating the inner cylinder 11 by the recirculated combustion exhaust gas.
Then, the premixed gas is sufficiently heated in the mixing cylinder 14 by mixing and stirring with the inflowing flue gas.
Thereby, catalytic combustion is performed stably.

By continuously performing the above-described catalytic combustion, the temperature inside the apparatus during steady-state combustion is in an equilibrium state, and stable catalytic combustion is continuously performed. It is preferable that the flow rate ratio between the combustion air and the combustion exhaust gas during steady combustion is about 1: 2. The oxygen concentration of the mixed gas of the combustion air and the combustion exhaust gas is about 5 to 10%, which is lower than the oxygen concentration in the atmosphere (about 21%), but the catalytic combustion can be performed using a mixed gas having a low oxygen concentration. It utilizes the property that it can be burned. As a result, a so-called reverse flash phenomenon of generating and burning a flame does not occur, and smooth catalytic combustion can be performed.

The transition time from the pilot combustion to the steady-state combustion varies depending on the type and amount of the liquid fuel and the catalyst to be used. Therefore, the fuel pump 9, the control valve 6, the ignition device and the The setting time of the timer in the control device 10 is adjusted so that the operation of the control device 19 is controlled.

When the operation is stopped, the operation of the fuel pump 9 is stopped while the blower 7 is operated, and the supply of the liquid fuel to the combustion device 1 is stopped. Then, when the temperature inside the device has sufficiently decreased, the blower 7 is stopped.

In the above-described embodiment, the operations of the fuel pump 9, the blower 7, the control valve 6, and the ignition device 19 are controlled by the switch device and the timer of the control device 10. However, a sensor or the like is used. It is also possible to adopt a configuration in which the temperature of the combustion exhaust gas or the like is detected by the temperature detecting means, and the operations of the fuel pump 9, the blower 7 and the control valve 6 are controlled in accordance with the detected temperature.

A part of the combustion exhaust gas at the time of catalytic combustion is
A configuration may be adopted in which the heat is circulated directly to the combustion device 1 without passing through the radiator tube 3. Further, in the present embodiment, a part of the combustion exhaust gas is discharged after the transfer of the radiator tube 3.
The entire amount of the combustion exhaust gas after the transfer may be introduced into the outer peripheral space of the inner cylinder 11 and used for heating the inner cylinder 11, and then a part may be discharged to the outside. Further, after premixing the combustion air and the entire amount of recirculated combustion exhaust gas outside the inner cylinder 11, a part of the mixture is introduced into the inner cylinder 11 as combustion air (mixed combustion exhaust gas). You may.

As described above, the catalytic combustion type heating apparatus according to the present invention does not recirculate the combustion exhaust gas during the pilot combustion. Therefore, the catalyst heating flame is not affected by the flow of the combustion exhaust gas having a low oxygen concentration and the pilot combustion Is performed well, and the catalyst layer can be efficiently heated. Also,
The pilot combustion temperature is not reduced by the low-temperature combustion exhaust gas after the heat is released for heating, and thus the prolonged heating time of the catalyst layer can be avoided.

Further, during steady combustion, the heat of the generated high-temperature combustion exhaust gas is used to prevent the liquid fuel adhering to the inner peripheral surface of the inner cylinder 11 from becoming a wall flow, thereby allowing rapid and sufficient vaporization. Along with acceleration, the combustion air can also be preheated. As a result, good catalytic combustion can be performed using the premixed gas having a desired mixture ratio and concentration, so that the generation of incompletely combusted substances such as carbon monoxide and hydrocarbons and unburned substances can be suppressed.

Further, it is not necessary to use a special preheating device such as an electric heater, a burner, and a heat exchanger for preheating the premixed gas, so that the size and cost of the device can be reduced. Therefore, the present device can be applied in a wide range from a small heating device for home use to a large heating device for industrial use.

Furthermore, by mixing the combustion exhaust gas acting as a gas for suppressing the maximum temperature of catalytic combustion for protecting the catalyst from heat damage with the premixed gas, the supply amount of combustion air is reduced, and the exhaust gas of the combustion exhaust gas is reduced. The amount can be reduced to reduce exhaust heat loss. By reusing the combustion exhaust gas, running costs can be reduced and fuel can be saved.

[0041]

As described above, according to the first aspect of the present invention,
According to the invention according to the invention, since the combustion exhaust gas is not recirculated during the pilot combustion, the catalyst heating flame is not affected by the flow of the combustion exhaust gas, the pilot combustion is performed favorably, and the catalyst layer is efficiently heated. be able to. In addition, since the inner cylinder is not cooled by the low-temperature combustion exhaust gas after releasing heat for heating, the pilot combustion temperature is not reduced,
As a result, the prolonged heating time of the catalyst layer can be avoided. Furthermore, at the time of catalytic combustion, the heat of the high-temperature combustion exhaust gas is utilized to prevent the liquid fuel adhering to the inner peripheral surface of the inner cylinder from becoming a wall flow, thereby promptly and sufficiently promoting the vaporization, and at the same time, the combustion air Can also be preheated well. In addition, by reusing the combustion exhaust gas, the exhaust gas amount of the combustion exhaust gas can be reduced, and the exhaust heat loss can be reduced.

According to the invention of claim 2 of the present invention, the agitation and mixing of the premixed gas and the combustion exhaust gas are positively promoted to make the fuel distribution more uniform and to promote good catalytic combustion. it can.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a catalytic combustion type heating device according to the present invention.

FIG. 2 is a schematic configuration diagram of an embodiment of the combustion device of FIG. 1;

FIG. 3 is a schematic configuration diagram of an embodiment of a mixing device.

FIG. 4 is a schematic configuration diagram of another embodiment of a mixing device.

[Explanation of symbols]

 1. Combustion device 2. Combustion air supply pipe 3. Radiation pipe 4. Branch pipe 6. Control valve 7. Blower 8. Combustion tank 9. Fuel pump 10. Control device 11. Inner cylinder 12. Combustion exhaust gas supply cylinder 13. Combustion exhaust gas discharge cylinder 14. Mixing cylinder 15. Mixing device 16. Catalyst column 17. Catalyst combustor 18. Combustion nozzle 19. Ignition device 20. Outer cylinder

Continued on the front page (72) Inventor Hisashi Nagano 3-390 Koyasudori, Kanagawa-ku, Yokohama, Kanagawa Prefecture Nishiishi Mitsubishi Refinery Co., Ltd. Yokohama Refinery (72) Inventor Tsutomu Tanabe 3-390 days, Koyasudori, Kanagawa-ku, Yokohama, Kanagawa (72) Inventor Yukio Aizawa 8 Chidori-cho, Naka-ku, Yokohama-shi, Kanagawa Prefecture Nishiishi Mitsui Co., Ltd.Central Research Laboratory (72) Inventor Yasushi Mizuno Chidori-cho, Naka-ku, Yokohama, Kanagawa Prefecture No. 8 Inside the Central Research Laboratory, Nishiishi Mitsui Co., Ltd. (72) Inventor Masayoshi Yoshida 6-26-11 Sagamigaoka, Zama City, Kanagawa Prefecture Nissei Oval Corporation Engineering Department F term (reference) 3K052 AA02 AB06 AB10 AC01 FA01 FA03 FA05 FA08

Claims (2)

[Claims] 1. A catalytic combustion type heating device in which a premixed gas of a liquid fuel and combustion air is burned by a catalyst to heat by the heat of the generated combustion exhaust gas and to preheat the premixed gas, A liquid fuel injection device for injecting the liquid fuel for combustion and pilot combustion, an ignition device for igniting the liquid fuel injected for the pilot combustion, and the liquid fuel injection device and the ignition device therein. Prepared,
Heating the inner cylinder by introducing the combustion air into the interior and premixing the injected liquid fuel with the inner cylinder; and recirculating a part of the combustion exhaust gas to an outer peripheral space of the inner cylinder. A combustion exhaust gas introduction section for preheating the premixed gas, and a mixing section for mixing the premixed gas flowing out of the inner cylinder and the combustion exhaust gas flowing out of the combustion exhaust gas introduction section to guide the mixed gas to the catalyst. And a combustion exhaust gas supply control means for stopping supply of the combustion exhaust gas to the outer peripheral space of the inner cylinder at the time of the pilot combustion. 2. The catalytic combustion type heating device according to claim 1, wherein the mixing section includes a mixing device for positively mixing the premixed gas and the combustion exhaust gas.