JP2532152B2 - Catalytic combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a catalytic combustion device for liquid fuel and the like.

<Prior Art> Conventionally, in this type of catalytic combustion apparatus, as shown in Japanese Patent Publication No. 61-31778, it is necessary to preheat the catalyst body to an activation temperature or higher prior to catalytic combustion. After igniting and the catalyst body reaching the activation temperature, it was shifted to catalytic combustion.

The operation will be described with reference to FIG. 3. At the start of combustion, the sheath heater 130 is first energized to heat the combustion cylinder 100. Since the combustion cylinder 100 is made of aluminum die-cast, not only the vaporization surface 112 but also the diffusion plate 122 and the preheating burner 11 are used.
1 and the catalyst body 101 are also preheated. However, while the activation temperature of the catalytic body 101 required for catalytic combustion is 800 to 1400 ° C,
In the case of kerosene, the suitable temperature of the vaporizing surface 112 is 250 to 300 ° C, so
It cannot be catalytically burned from the beginning.

Therefore, when a temperature sensor (not shown) attached to the combustion cylinder 100 near the vaporization surface detects that the vaporization surface 112 has reached the above-mentioned appropriate temperature, the motor 115 rotates and the turbofan 1
34 and the liquid fuel atomizing plate 133 are rotated. The electromagnetic pump 131 is activated with a few seconds delay, and the liquid fuel is rotating.
Is transmitted to the vaporizing surface 112 through the atomizing plate 133 and is instantly vaporized. On the other hand, the combustion air is the above turbo fan.
By 134, the air is divided into two through the outside air intakes 137, 138 → the heat insulating space 139 → the air intake 140 → the air blower chamber 141, and one passes through the combustion air introduction port 142 and enters the combustion cylinder 100 to enter the vaporization surface 112.
The liquid fuel gas vaporized by is mixed by the diffusion plate 122 into a premixed gas, which passes through the preheating burner 111.

At that time, the electrode 123 on the back side of the catalyst body 101 is sparked, a small flame is formed in the minute holes 135 formed in the preheating burner 111, and the catalyst body 101 is heated. When the temperature of the catalyst body 101 reaches the activation temperature, increasing the ratio of the premixed gas amount and the air causes the premixed gas to pass through the micropores 135 at a higher acceleration rate than the combustion speed in the micropores 135, thereby holding the flame. And the hole diameter is larger than the micro hole 135,
And the small pores 1 of the catalyst body 101, which has a high combustion speed due to the supported oxidation catalyst and maintains the balance between the passing speed and the combustion speed.
At 36, catalytic combustion is initiated.

<Problems to be Solved by the Invention> However, in the above-described conventional catalytic combustion device, when transitioning from preheating combustion to catalytic combustion, it is necessary to change both the amount of fuel and the amount of blown air, which complicates the structure and control system. There was a problem of becoming.

The present invention has been made to solve such a problem, and since the fuel gas is supplied through the preheating burner of the ejector system even during the catalytic combustion, the combustion gas corresponding to the primary air during the preheating combustion is used. Air is supplied in proportion to the amount of fuel gas. On the other hand, a fixed amount of air supplied as secondary air from the periphery of the preheating burner at the time of preheating combustion is also mixed with the premixed gas discharged from the preheating burner as all primary air. Therefore, it is not necessary to control the amount of fuel gas or the amount of blown air when transitioning from preheating combustion to catalytic combustion. Also, during steady catalytic combustion, when the fuel gas amount decreases, the air ratio increases and the combustion speed slows, so the amount of premixed gas passing through the catalyst body decreases, and even if the passing acceleration slows, It is an object of the present invention to provide a catalytic combustion device that does not burn and has a simple structure and control system.

<Means for Solving the Problems> To achieve the above object, the present invention has a preheating burner for igniting and burning a premixed gas to heat a catalyst body provided downstream, and the catalyst body is activated. When the temperature is reached, in the catalytic combustion device that shifts from combustion in the preheating burner to catalytic combustion using the catalyst body, a mixing chamber is provided between the catalyst body and the preheating burner, and A divided decompression chamber is provided, and the preheating burner opens a throat hole in this decompression chamber, and sucks the primary air by the ejection effect generated along with the combustion gas flow supplied to the preheating burner. Then, the gas after combustion is discharged to the mixing chamber.

On the other hand, the air from the blower bypasses the outer periphery of the mixing chamber and is preheated by exchanging heat with the side wall of the mixing chamber heated by the radiant heat from the catalyst body, and the primary air at the time of preheating combustion passes through the primary air port. Introduced into the decompression chamber through, secondary air is introduced into the mixing chamber through a secondary air port, during the catalytic combustion, the primary air and the secondary air are combined into a total primary air To do.

<Operation> In the above-described configuration, the preheating burner used for preheating the catalyst body for catalytic combustion naturally sucks the primary air for combustion by the ejection effect generated along with the gas flow for combustion and burns it. When the catalyst body reaches a predetermined temperature due to the flame combustion of the preheating burner, the fuel supply is stopped to extinguish the flame, and the fuel is supplied again, and then the catalytic combustion is started.

Even during catalytic combustion, the preheating burner is used to supply a part of the total primary air for combustion in proportion to the combustion gas amount, and the secondary air for combustion during preheating combustion is supplied from the preheating burner. It can be mixed with the premixed gas in the mixing chamber and supplied to the catalytic body as a gas for all primary air combustion to perform catalytic combustion.

Further, the combustion air sent from the blower is preheated when bypassing the periphery of the mixing chamber, and the entire blowing path is heated, so the vaporized combustion gas contacts the preheating burner or the like. Does not condense.

<Example> Hereinafter, the present invention will be described in detail with reference to the drawings illustrating an example thereof. FIG. 1 is a schematic sectional view of the catalytic combustion apparatus according to this embodiment, and FIG. 2 is a sectional view taken along the line AA ′ in FIG. Reference numeral 1 denotes a catalyst body in which at least one or more of platinum group metal oxidation catalysts such as Pt, Rh, Pd, Ru, and Ir are supported on a heat-resistant inorganic carrier having excellent far infrared radiation efficiency. It is attached to the opening. Box 2 is outer box 3 and middle box 4
And the inner box 5 are substantially triple-layered. Burner mounting plates 6 are attached to the inner surface of the inner box 5 above the inner box bottom surface 5a so that the four sides are in close contact with each other. Between the burner mounting plate 6 and the bottom 5a of the inner box,
The first partition plate 7 and the second partition plate 8 are closely attached to the burner mounting plate 6 and the inner box 5 on four sides to form a decompression chamber 9. An adjustment hole 10 is provided on the side wall of the decompression chamber 9 so that the primary air supplied to the throat portion 11a of the preheating burner 11 can be adjusted to substantially atmospheric pressure. The throat portion 11a of the preheating burner is embedded in the partition plate 7. A nozzle portion 12a of a carburetor 12 is embedded in the partition plate 8, and the throat portion 1
The central axis of 1a is arranged so as to substantially coincide with the central axis of the nozzle portion 12a. One or more secondary air holes 13 are provided in the bottom surface 5a of the inner box. The air surrounded by the bottom surface of the outer box, the bottom surface of the inner box, and the side wall of the outer box forms a pressurizing chamber 14, and the total combustion air sent from the blower 15 is a blower port provided on the side wall of the outer box.
First, the pressure chamber 14 is entered from 15a.

Next, it is sent upward through the space between the outer box 3 and the inner box 4. Then, the above-mentioned all air reaching the upper part of the box body 2 is returned from the return port 19 formed by the inner box top surface and the inner box top surface and the inner box side wall to the space between the inner box side wall 4b and the inner box side wall 5b. Go down 20. Then, this total air is divided into primary air and secondary air by the name at the time of preheating combustion, and the primary air enters the decompression chamber 9 through the adjustment hole 10,
Due to the ejection effect of the vaporized gas ejected from the nozzle portion 12a of the vaporizer, the vaporized gas is sucked into the throat portion 11a of the preheating burner. One secondary air is supplied from the secondary air hole 13 to the mixing chamber 21 through the gap between the preheating burner 11 and the bart mounting plate 6. Further, the inner box side wall 5b promotes the mixing and diffusion of the flame at the time of preheating combustion or the premixed gas at the time of catalytic combustion and the combustion air supplied from the secondary air holes, and the uniform combustion heat to the catalytic body 1, Alternatively, a diffusion plate 22 having a V-shaped cross section for attaching the premixed gas is attached. By adjusting the bending angle of the diffusion plate 22, the catalyst body 1 is formed so as to be uniformly heated during flame combustion for preheating the catalyst body 1 and during catalyst combustion.

Next, the operation of the catalytic combustion device will be described. First, the preheater (not shown) of the vaporizer 12 and the ignition heater 23 are energized. When the temperature of the vaporizer 12 reaches, for example, 250 to 300 ° C. in the case of kerosene, an oil feed pump (not shown) is operated to vaporize the vaporizer 12
Supply kerosene to. Kerosene is immediately vaporized in the vaporizer 12 and jetted from the nozzle portion 12a toward the throat portion 11a of the preheating burner. At the same time, the blower 15 operates, and all the combustion air is sent through the inside of the box body 2 through the above-mentioned path. The primary air during preheating flows into the decompression chamber 9 through the adjustment hole 10. The pressure in the decompression chamber 9 is close to the atmospheric pressure. Therefore, it is formed so that the primary air in proportion to the ejection amount and ejection velocity of the combustion gas from the nozzle portion 12a is supplied,
The ratio of the amount of liquid fuel and the amount of primary air is autonomously adjusted to an appropriate combustion range, for example, 1.0 to 1.5. The premixed gas of the combustion gas and the primary air mixed in the preheating burner 11 is discharged from the flame port 11b of the preheating burner. Since the fire heater 23 is red-hot at this point, the premixed gas ignites and starts flame combustion. When the flame sensor 24 fixed above the flame outlet 11b detects the flame combustion at the flame outlet 11b, the energization of the ignition heater 23 is stopped, and the flame combustion is continued for about 1 minute thereafter. At that time, the secondary air hole
The secondary air, which passes through the space 13 between the burner mounting plate 6 and the preheating burner 11 and is supplied to the mixing chamber 21, is uniformly mixed with the flame by the diffusion plate 22 and diffused to carry out secondary combustion to heat the catalyst body 1. .

When the temperature sensor 25 detects that the temperature of the catalyst body 1 has reached an activation temperature required for catalytic combustion, for example, 750 ° C., the oil feed pump is stopped for 5 to 6 seconds, and flame combustion in the preheating burner 11 is performed. To stop. After that, when the oil supply is restarted, the premixed gas discharged from the flame port 11b becomes the ignition heater 2
Since electricity is not applied to 3, flame combustion at the flame port 11b cannot be performed. Then preheat burner 11
The secondary air at the time of preheating supplied from the surroundings and is diffused by the diffusion plate 22, diffused, and reaches the catalyst body 1 as a premixed gas of lean primary air that is difficult to burn in flame. Since the catalyst body 1 has a heat capacity, only a short time has passed since the flame combustion was stopped, and the activation temperature required for the catalyst combustion, for example, 500 to 750 ° C., is maintained, so that the catalyst combustion is immediately started.

Catalyst 1 has a sufficient size for premixed gas is completely combusted, CO, HC, no throat generate N殆harmful gas such as NO _X. Further, since the air-fuel ratio of the premixed gas is 2 to 4, the flashback is unlikely to occur first. However, due to a strong headwind and some abnormalities, it flashes back and the burner tip of the preheating burner
When flame combustion in 11b occurs, the combustion is stopped based on the detection of the flame sensor 24.

During steady-state catalytic combustion, the initial heat quantity can be changed without changing the combustion air quantity by simply changing the oil feed quantity by the oil feed pump while keeping the air quantity of all combustion air constant. The temperature of the catalyst body 1 is always maintained at 500 to 750 ° C. At this time, in particular, the temperature of the side wall 5b of the inner box rises due to the heat of flame combustion by the preheating burner 11 at the time of preheating the catalyst body and the radiant heat of the catalyst body 1 at the time of catalyst combustion. However, when all the air for combustion passes through the space 20 between the side wall 5b and the middle box side wall 4b, heat is exchanged to cool not only the side walls 5b and 4b but also the whole box body 2 and the whole air is warmed. It will be about 100 ℃. Therefore, the vaporized gas ejected from the nozzle portion 12a is not heated by the preheating burner 1
It does not condense even if it touches the inside of 1 or the diffusion plate 22.

When extinguishing the fire, the fuel in the path from the carburetor 12 and the preheating burner 11 to the catalyst body 1 does not disappear instantly even if the oil pump is stopped. Therefore, when the blower 15 is also stopped, unburned gas is generated. The catalyst body 1 has a heat capacity and maintains an activation temperature for a while because it causes an odor. Therefore, the stop of the blower 15 is delayed for about one minute to completely burn the fuel and the catalytic combustion device Also cool.

<Effects of the Invention> Since the catalytic combustion apparatus of the present invention is configured as described above, it is not necessary to change the air flow rate even when transitioning from preheating combustion to catalytic combustion, so the rotation speed of the blower is controlled. In addition, the structure and control system can be simplified compared to the case of controlling the air flow rate by switching the damper, and even when only the blower suddenly stops due to some failure, it is possible to use the preheating burner. Since complete combustion is possible, unburned gas is not emitted, and abnormalities can be detected from changes in the temperature of the catalyst body, and it can be stopped, so safety can always be maintained.In addition, primary air and secondary air can be maintained in the preheating passage. Since the preheating is performed, the current supply to the carburetor and the like is reduced, and the power consumption can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front sectional view schematically showing a catalytic combustion apparatus according to the present invention, FIG. 2 is a schematic sectional view taken along the line AA ′ shown in FIG. 1, and FIG. It is a side sectional view showing a catalytic combustion device. 1 ... Catalyst, 2 ... Box, 11 ... Preheating burner, 12 ...
… Vaporizer, 13 …… Secondary air hole, 22 …… Diffuser

Claims (1)

(57) [Claims] 1. A preheating burner that ignites and burns a premixed gas to heat a catalyst body provided downstream, and uses the catalyst body from combustion in the preheating burner when the catalyst body is activated. In the catalytic combustion apparatus that shifts to the catalytic combustion, the mixing chamber is provided between the catalyst body and the preheating burner, and a decompression chamber is provided which is separated from the mixing chamber, and the preheating burner has a throat hole in the decompression chamber. Is used as a burner for sucking the primary air by the ejection effect generated along with the combustion gas flow supplied to the combustion chamber to perform combustion and discharging the burned gas to the mixing chamber. A preheating passage is provided to preheat the primary air and the secondary air blown by the blower by bypassing the outer periphery of the mixing chamber and exchanging heat with the wall surface of the mixing chamber, and depressurizing the primary air preheated in the preheating passage. In the room Ku catalytic combustion apparatus provided with a secondary air inlet leading to the mixing chamber of the secondary air preheated in the primary air inlet and the preheater passageway.