JPH10169927A - Catalytic combustion device - Google Patents

Abstract

(57) [Summary] [Purpose] The catalyst body can be reliably prevented from dissolving.
Provided is a catalytic combustion device capable of maintaining combustion with a small amount of x for a long period of time. The temperature of a lean mixture formed in a vaporization pot 1 provided with a vaporization heater 2 is increased by catalytic combustion through a catalytic body 7, and the vapor is burned in a combustion chamber 18 in a gas phase. The temperature of the catalyst body 7 is always kept constant by controlling the electromagnetic pump 43 via the control circuit 42 in accordance with the temperature detected by the temperature sensor 14 and varying the air ratio. It is to keep the temperature and prevent the dissolution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic combustion device constituting a combustion portion of a heater such as a domestic water heater or a fan heater.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 2-238206, a fuel gas is heated to a catalyst activation temperature by a preheater and then heated in a catalytic combustion region. The purpose of the present invention is to provide a combustion method that does not generate harmful substances such as NOx by performing catalytic combustion and then performing gas phase combustion in a gas phase combustion region.

[0003]

By the way, in this conventional apparatus, as the gas phase combustion continues, the temperature of the catalyst gradually rises due to the heat, and finally, the gas phase combustion occurs in the catalyst and the melting occurs. However, in order to prevent this, a catalyst having heat resistance may be used, but the gas phase combustion temperature is 1200 ° C.
As a result, there has been a great problem that a catalyst having such high temperature and durability has not been put to practical use at present.

[0004] This prior art relates to an industrial gas turbine, and it is difficult to apply it to a small household heater or the like because it is very difficult. NOx is generated if the concentration of
The generation of NOx cannot be reliably suppressed.

[0005]

In order to solve the above-mentioned drawbacks, the present invention focuses on this point. In particular, the present invention comprises a mixture supply means for supplying a lean mixture with an excessive amount of air, and a mixture supply means. A catalyst body for catalyzing combustion by flowing a lean mixture from the means to raise the temperature of the mixture, and a combustion chamber for performing gas phase combustion of the mixture flowing out of the catalyst body, A temperature sensor for detecting the temperature of the catalyst is provided, and the air ratio is controlled in accordance with the temperature detected by the temperature sensor to keep the temperature of the catalyst at a predetermined constant temperature.

[0006]

A fuel oil, which is a fuel, is sprayed into a vaporization pot 1 constituting a mixture supply means heated to a vaporizable temperature by a vaporization heater 2, and combustion air having an air ratio of about 2 is supplied. Premix to form a lean mixture with excess air.

[0007] The lean mixture flows into a honeycomb-shaped catalyst body 7 communicated above the vaporization pot 1, and is heated by heat generated by reacting on a catalyst 12 formed on a support 10. Due to heat exchange with 7, the lean mixture further increases its temperature.

Next, the lean air-fuel mixture flows out of the catalyst body 7 and flows into the combustion chamber 18 covering the upper part of the catalyst body 7, where it is ignited by an appropriate ignition means 41 so that it can be burned at a high temperature. The resulting lean mixture performs gas phase combustion.

During the gas phase combustion, the temperature of the upper portion of the catalyst 7 is detected by the temperature sensor 14, and the electromagnetic pump 43 is controlled so that this temperature is a predetermined temperature equal to or lower than the melting temperature of the catalyst 7, here 800 ° C. To increase or decrease the amount of combustion.

That is, a voltage value at 800 ° C. is determined in advance and input to the control circuit 42 as a reference voltage, and the temperature detected by the temperature sensor 14 is converted into a voltage value to convert the temperature into a voltage value.
The control circuit 42 compares the two values to calculate a deviation value, and outputs this value as a drive pulse to the electromagnetic pump 43, thereby maintaining the temperature of the catalyst body 7 at a constant temperature. Things.

Therefore, the temperature of the catalyst 7 does not rise above the temperature at which gas phase combustion occurs in the catalyst 7 and is easily maintained at a constant temperature. There is no, it can always be used with confidence.

Further, since the gaseous combustion of a lean air-fuel mixture is used, the NOx value in the combustion gas is extremely small, and it is possible to provide, for the first time, a small-sized household heater with little effect on the environment and low-pollution combustion that is gentle to humans. Things.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment in which a catalytic combustion device according to the present invention is provided in a fan heater of a heater will be described. Reference numeral 1 denotes a vaporization pot made of aluminum die-cast in which a vaporization heater 2 is cast at an upper portion, and an ejection port 5 for blowing out combustion air from a combustion fan 3 through an air passage 4 communicates with one side thereof. The jet port 5 is provided with a nozzle 6 for spraying fuel oil, and forms a premixed gas of the vaporized gas and the combustion air to constitute a mixture supply device.

Reference numeral 7 denotes a cylindrical catalyst body provided so as to close the upper end opening of the vaporization pot 1. A protective layer 9 made of an alumina-based heat-resistant material having a heat-resistant steel plate 8 on the outside is provided all around the side wall. -The amount of feedback is adjusted, and here, it is 10 mm.

The catalyst 7 has a washcoat layer 11 formed on one side of a support 10 made of a corrugated metal sheet, on which palladium, platinum or (mainly containing palladium or platinum) is formed. Selected from silver, gold, platinum, palladium, ruthenium, rhodium, or iridium,
After coating and calcining a catalyst 12 containing one or more auxiliary catalysts, the support 10 is spirally wound up and housed in a metal tube 13 to form a honeycomb shape.
When the catalyst 12 is activated, catalytic combustion, which is a chemical reaction, is performed by the flow of the air-fuel mixture.

14 is inserted into the catalyst body 7,
Although a temperature sensor for detecting the temperature of the inner upper portion can directly convert the temperature into a voltage and has a high heat resistant temperature, a thermocouple is used here, but a sensor such as a thermistor may be used.

Reference numeral 15 denotes a combustion cylinder surrounding the catalyst 7 projecting above the partition plate 17 in the main body frame 16. An alumina heat-resistant material which hangs downward from the upper portion and covers the upper portion of the catalyst 7 to form a combustion chamber 18. Is provided with a heat insulating material 19 having a vertical U-shaped vertical section,
In the combustion chamber 18, flame combustion is performed at the time of ignition, and gas phase combustion is performed after the temperature of the catalyst 7 reaches the activation temperature.

Numeral 20 denotes a flow passage through which the combustion gas after combustion in the combustion chamber 18 flows, and from the side wall of the catalyst 7 protruding into the combustion chamber 18, passing under the heat insulating material 19 and the heat insulating material 19 and the combustion tube 15. Is formed so as to increase the distance from the inner wall and discharge the combustion gas from the discharge hole 21 at the upper end of the combustion cylinder 15.

Reference numeral 22 denotes a convection fan provided on the back of the main body frame 16 behind the combustion cylinder 15. And the room is heated with hot air.

Reference numeral 24 denotes a heat shield plate which partitions a space between a partition frame 25 from the upper end of the combustion tube 15 to the outlet 23 into a hot air passage 26 through which the convection fan 22 blows air and a cooling passage 27 through which cooling air flows. is there.

Numeral 28 denotes a heating ring located in the middle of the flow passage 20, which stands up from the upper end of the vaporizing pot 1 to recover heat from the combustion gas and heats it back to the vaporizing pot 1.

Reference numeral 29 denotes a frame rod which penetrates the heat insulating material 19 and is provided in the combustion chamber 18. The flame rod and the gas-phase combustion apply a voltage between the catalyst rod 7 and the flame rod, and detect a current value flowing through the flame rod. Is what you do.

Reference numeral 30 denotes a packing material for hermetically sealing the lower portion of the combustion tube 15, reference numeral 31 denotes a fan cover of the convection fan 22, and reference numeral 32 denotes a burner cover of the vaporization pot 1.

Reference numeral 33 denotes an operation unit provided on the upper part of the main body frame 16, and 34 denotes a cartridge tank (not shown) for the main body frame 1.
A tank lid 35 for taking in and out of 6, a handle 35 and a lower plate 36 are provided.

Next, the electric circuit diagram shown in FIG. 7 will be described. Reference numeral 37 denotes a microcomputer which has various functions such as comparison, calculation, storage, and timer and performs overall control. On the input side, a vaporization temperature sensor 38 for detecting the temperature of the vaporization pot 1 and a desired room temperature are set. , A room temperature sensor 40 for detecting the room temperature, and the frame rod 29 are connected.

Further, the output side of the microcomputer 37 is provided with a vaporizing heat source.
The ignition means 41 such as the heater 2 and the combustion fan 3 and the convection fan 22 and the igniter are respectively connected and controlled according to each situation.

Reference numeral 42 denotes a control circuit for feedback-controlling the drive of the electromagnetic pump 43 connected to the nozzle 6 in accordance with the temperature of the catalyst body 7 to adjust the amount of fuel, and inputs the detected temperature from the temperature sensor 14 as a voltage value. And a reference voltage circuit 45 for inputting a reference voltage value corresponding to a predetermined constant temperature of 800 ° C. to the judgment circuit 44 and comparing the two values, and a deviation value obtained by the comparison operation And a pulse setting circuit 46 for outputting a drive pulse of the electromagnetic pump 43 according to the above.

Next, the operation of this embodiment will be described. When the vaporization heater 2 is now energized and the vaporization pot 1 is heated to reach a vaporizable temperature, the vaporization temperature sensor 38 detects this and starts driving the combustion fan 3 via the microcomputer 37, and the combustion air is vaporized first. When the amount of combustion air is stabilized after several tens of seconds, the microcomputer 37
The electromagnetic pump 43 starts to be driven by the output from the nozzle and sprays the fuel oil into the vaporization pot 1 through the nozzle 6 to form a premixed air with the combustion air.

However, since the premixed gas at this time is at room temperature without heating the catalyst body 7 yet, the voltage of the temperature detected by the temperature sensor 14 is much smaller than the reference voltage, and the deviation value becomes large. The drive pulse supplied from 46 becomes the maximum, the maximum fuel oil amount is supplied from the electromagnetic pump 43, and the air having an air ratio of 1 is supplied. 41
At the time of ignition as shown in FIG. 8, ordinary flame combustion is performed at the maximum combustion amount.

When the catalyst body 7 is heated by the flame combustion and gradually rises to an activation temperature of the catalyst of 250 ° C. or more, this temperature is detected by the temperature sensor 14 and the judgment circuit 4
4, the detected voltage value gradually increases, the deviation value from the reference voltage from the reference voltage circuit 45 decreases, and the drive pulse of the electromagnetic pump 43 moves in a direction to decrease.
The fuel oil amount decreases and the air-fuel mixture gradually becomes lean, and the air ratio becomes 2
In the vicinity, the temperature of the catalyst body 7 is also kept constant at 800.
Reach ° C.

As a result, a lean mixture is formed in the vaporization pot 1 and flows into the catalyst body 7 which has reached 800 ° C., so that the fuel and air react on the catalyst 12 in the catalyst body 7. Due to heat exchange with the catalyst 7 heated by the heat generated by the heat, the temperature of the lean mixture rises,
Within the catalyst body 7, a mixture of 120 to 150 ° C.
The temperature is rapidly raised to 50 to 900 ° C., ignited by the self-ignition phenomenon in the combustion chamber 18 through the transient state shown in FIG.
The gas phase combustion at 0 to 1500 ° C. is performed.

Therefore, the combustion gas after the combustion is supplied to the flow passage 2
0, and is discharged from above the combustion tube 15 to the convection fan 22.
The air is blown as warm air from the air outlet 23 to heat the room. However, since the air is heated by the combustion of a lean air-fuel mixture, the NOx value is 1 to 20 ppm. NOx value of 110 to 120 pp
The value is extremely low with respect to m, and it is possible to realize a low-pollution heater with little effect on the environment and people.

On the other hand, the combustion gas after the gaseous phase combustion in the combustion chamber 18 flows through the flow passage 20, passes through the outer peripheral side wall of the catalyst 7, and heats back via the protective layer 9, so that the catalyst 7 is always The heating temperature is maintained at the activation temperature, and the heating ring 28 protruding into the flow passage 20 can also obtain the heat back of the combustion gas in the vaporization pot 1, and the energization of the vaporization heater 2 is almost stopped during combustion. Is what you do.

Therefore, the combustion chamber 18 made of the heat insulating material 19 having an inverted U-shaped vertical section and the flow passage 20 communicating therewith,
Heat-back to the catalyst 7 and the vaporization pot 1 is performed well, unnecessary power and complicated control are not required, the catalyst 7 can be easily maintained at the activation temperature, and the above-mentioned NO is hardly burned.
The combustion of a lean mixture having a small x value can be continued without difficulty.

Next, when the temperature of the catalyst 7 rises abnormally due to the continuation of the gas phase combustion, the temperature of the catalyst 7 is detected by the temperature sensor 14, and the voltage detected by the determination circuit 44 and the reference voltage The detection voltage is larger than
Since the pulse setting circuit 46 reduces the drive pulse of the electromagnetic pump 43 and reduces the fuel oil amount, the air ratio moves to the lean side,
Due to the decrease in the catalytic reaction rate and the amount of generated heat, the temperature of the catalyst body 7 drops to maintain a constant temperature of 800 ° C.

Conversely, when the temperature of the catalyst 7 drops below 800 ° C., the control circuit 42 controls the electromagnetic pump 43 to
The fuel amount is increased, the air ratio is shifted to the rich side, and the catalytic reaction speed and the amount of generated heat are increased, so that the temperature of the catalyst body 7 is increased to maintain 800 ° C.

Therefore, by controlling the air ratio of the air-fuel mixture according to the temperature detected by the temperature sensor 14, the catalyst 7 can always be maintained at a constant temperature that is optimal for activation. There is no problem of misfiring, and it can always be used with peace of mind.

Further, the variable combustion amount of the heater is calculated by comparing the set temperature of the room temperature setting means 39 after activation of the catalyst with the current room temperature from the room temperature sensor 40 in the microcomputer 37, and the combustion supplied from the combustion fan 3. This is performed by controlling the amount of air, that is, by varying the amount of combustion air, the temperature of the catalyst body 7 changes, and the electromagnetic pump 43 is controlled as described above so as to maintain this temperature at 800 ° C. As a result, the amount of combustion is varied.

Therefore, by controlling the temperature of the catalyst body 7 to be constant, the combustion amount can be varied by a very simple control of only the combustion air amount control, so that complicated control is not required and there is no need to worry about failure.

Further, the catalyst 7 is a catalyst 12 containing palladium as a main component, and the catalyst 12 is provided only on one side of the support 10.
Is applied, heat is dissipated by heat conduction from the wall surface of the support 10 having the catalyst 12 to the wall surface having no catalyst 12 and through which only the air-fuel mixture flows.
~ 950 ° C, there is no risk of melting or misfiring due to temperature rise, and even if the temperature sensor 14 fails, the temperature will not rise and double safety measures are taken. Things.

By projecting the upper end of the catalyst 7 into the combustion chamber 18, the lower end of the heat insulating material 19 becomes lower than the catalyst 7,
The combustion gas can surely come into contact with the outer periphery of the catalyst body 7, and a good heat back can be obtained.

In this embodiment, the microcomputer 37 and the control circuit 42 are separately provided. However, the present invention is not limited to this configuration.

[0043]

In short, the present invention provides a mixture supply means for supplying a lean mixture having an excess amount of air, and a catalytic combustion by flowing the lean mixture from the mixture supply means to raise the temperature of the mixture. And a combustion chamber for performing gas phase combustion of an air-fuel mixture flowing out of the catalyst body, comprising a temperature sensor for detecting the temperature of the catalyst body. Since the air temperature is controlled to maintain the temperature of the catalyst body at a predetermined constant temperature, it is possible to reliably prevent a problem that the catalyst body abnormally rises in temperature and melts or misfires. Good combustion can be maintained over a long period of time without generation of odor, and a combustor that is friendly to the environment and humans can be easily provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a heater equipped with a catalytic combustion device according to one embodiment of the present invention.

FIG. 2 is a sectional view of the same.

FIG. 3 is a sectional view of the main part.

FIG. 4 is a perspective view of the catalyst body.

FIG. 5 is a plan view of the catalyst body.

FIG. 6 is an enlarged sectional view of the catalyst body.

FIG. 7 is a block diagram of the electric circuit.

FIG. 8 is a characteristic diagram at the time of ignition.

[Description of Signs] 1 vaporization pot 2 vaporization heater 7 catalyst body 14 temperature sensor 18 combustion chamber 42 control circuit 43 electromagnetic pump

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshiji Tokita 7-7 Higashi Shinbo, Sanjo-shi, Niigata Prefecture Inside (72) Inventor Katsumi Moruga 7-7 Higashi-Shinbo, Sanjo-shi, Niigata Prefecture Corona Co., Ltd. (72) Inventor Kazuhiro Takeda 7-7 Higashi Shinbo, Sanjo, Niigata Prefecture Corona Co., Ltd. (72) Inventor Masaki Takachi 7-7 Higashi Shinbo, Sanjo City, Niigata Prefecture Corona Co., Ltd. (72) Inventor Tohru Shoji 2nd 73, Shinmachi, Hiratsuka-shi, Kanagawa Prefecture Inside the Technology Development Center, Tanaka Kikinzoku Kogyo Co., Ltd. (72) Inventor Masahiro Sasaki 2-73, Shinmachi, Hiratsuka-shi, Kanagawa Prefecture Inside the Technology Development Center, Tanaka Kikinzoku

Claims (2)

[Claims] An air-fuel mixture supply means for supplying a lean air-fuel mixture with an excess amount of air, a catalyst body for catalyzing combustion by flowing the lean air-fuel mixture from the air-fuel mixture supply means to raise the temperature of the air-fuel mixture, A combustion chamber for performing a gas phase combustion of the air-fuel mixture flowing out of the catalyst body, wherein a temperature sensor for detecting a temperature of the catalyst body is provided, and an air ratio is controlled according to a temperature detected by the temperature sensor. A catalytic combustion device for maintaining the temperature of the catalyst at a predetermined constant temperature. 2. The method according to claim 1, wherein the control of the air ratio is performed by controlling a fuel supply amount with respect to a combustion air amount.
A catalytic combustion device according to any of the preceding claims.