JP3701424B2 - Hot air heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a warm air heater that mixes combustion gas generated by combustion of a burner and air sucked by a blower fan and blows the warm air outside the device.
[0002]
[Prior art]
As a conventional hot air heater of this type, as disclosed in Japanese Patent Application No. 7-134997, a combustion housing provided with a burner having a combustion cover is disposed in the hot air heater and discharged from the combustion cover. This is a warm air heater that mixes the combustion gas and the air sucked in by the blower fan and blows it as warm air outside the device, and burns until the combustion gas is discharged from the combustion cover and flows to the blower fan for a predetermined distance A hot air heater has been proposed in which a flow dividing plate is provided to partition a gas flow and a sucked air flow, and heat is exchanged between the combustion gas and air via the flow dividing plate.
[0003]
[Problems to be solved by the invention]
When nitrogen gas (NO), which is the main component of nitrogen oxides in the combustion gas, is rapidly cooled by touching the high-temperature combustion gas with air at once, the rate of conversion to nitrogen dioxide (NO2) (nitrogen dioxide conversion rate) is large. It is known that the amount of nitrogen dioxide generated increases. Further, it is known that the generation amount of the entire nitrogen oxide increases as the temperature of the combustion gas increases.
[0004]
By the way, in the hot air heater previously proposed, the combustion gas discharged from the combustion cover is divided by the flow dividing plate and heat exchange is performed through the flow dividing plate before being mixed with the air. There is no rapid cooling. However, in order to prevent the combustion cover from opening in the combustion housing and flowing air to prevent overheating of the upper end portion of the combustion housing, the combustion cover extends over the entire circumference of the combustion cover between the combustion cover and the inner peripheral surface of the combustion housing. A continuous gap is formed, so that the combustion gas discharged from the combustion cover is immediately mixed with the air in the combustion casing rising through the gap and quenched, and at that time, a certain amount of nitrogen dioxide is already contained in the combustion gas. Is included. In addition, the combustion gas discharged from the combustion cover remains in a high temperature state until it is mixed with air, so the total amount of nitrogen oxides generated increases, and even if the conversion rate to nitrogen dioxide does not increase, nitrogen dioxide There arises a problem that the amount of conversion to increases.
[0005]
Then, in view of said problem, this invention aims at providing the warm air heater which can further reduce content of nitrogen dioxide of the warm air sent.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has a combustion housing with a burner inside and a combustion cover surrounding the flame of the burner, and the air introduced into the combustion housing is opened in the combustion cover. In the warm air heater that supplies the flame through the air hole, mixes the combustion gas discharged from the combustion cover and the air sucked by the blower fan, and blows it as warm air outside the device, the outlet of the combustion cover is An enclosing partition wall is provided, and an opening is opened in the partition wall over a predetermined range along the flow direction of the combustion gas discharged from the outlet of the combustion cover, and the opening is formed in the combustion gas surrounded by the partition wall. Air is supplied through the part, and an opening is formed in a part of the partition part so as to cross the flow of the combustion gas, thereby providing a cooling part for the combustion gas.
[0007]
Even if the combustion gas is discharged from the outlet of the combustion cover, the partition wall prevents the combustion gas from being rapidly mixed by preventing the air in the combustion housing from being mixed rapidly with the combustion gas. However, just surrounding the outlet of the combustion cover with the partition wall portion, the combustion gas is rapidly cooled by the air flowing along the outer periphery of the partition wall portion when passing through the partition wall portion, and the generation amount of nitrogen dioxide cannot be suppressed. Accordingly, the opening is formed in the partition wall, and air is gradually taken into the partition wall from the opening and mixed with the combustion gas, so that the combustion gas is gradually discharged until the combustion gas is discharged through the partition wall. It was decided to cool.
[0008]
Further, as described above, the combustion gas is discharged from the outlet of the combustion cover, but a large amount of unburned gas is also contained. Unburned gas discharged from the outlet of the combustion cover changes to combustion gas before the cooling unit provided so as to cross the flow of combustion gas. Therefore, by providing the cooling section, the temperature of the combustion gas itself that has changed in front of the cooling plate is lowered. Therefore, the temperature of combustion gas falls and the generation amount of the whole nitrogen oxide is reduced.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2, reference numeral 1 denotes a main body of a hot air heater according to the present invention. In the main body 1, a combustion housing 2 having a burner 21 and a spark plug P and a blower fan 3 below the combustion housing 2 are provided. When the blower fan 3 is operated, the outside air is sucked into the main body 1 from the suction port 11 provided on the back surface of the main body 1, and the combustion gas discharged from the combustion housing 2 and the suction It mixes with the air which was done, and it is comprised so that it may ventilate out of the apparatus as warm air from the ventilation port 12 provided in the front surface of the main body 1. FIG. In FIG. 1, the flow of air is indicated by a white arrow, the flow of combustion gas is indicated by a black arrow, and the flow of warm air mixed with air and combustion gas is divided into white and black. Shown with an arrow. By the way, a box-shaped combustion cover 22 is attached to the burner 21, and combustion gas is discharged from an opening 23 which is an outlet opened on the upper surface of the combustion cover 22. A partition wall cover 5, which will be described later, is attached to the upper portion of the combustion cover 22, and the opening 23 is surrounded by the partition wall cover 5. In this embodiment, the partition wall cover 5 is formed separately from the combustion cover 22 and the partition wall cover 5 is screwed to the combustion cover 22. However, the partition wall cover 5 may be formed integrally with the combustion cover 22. . In addition, a pair of throttle members 24 are provided inside the combustion cover 22 to form a throttle portion 24 a that narrows the rising passage of the combustion gas in the combustion cover 22, and for combustion above the throttle member 24. An air hole 24b for introducing a small amount of secondary air into the combustion cover 22 is formed, the rising speed of the combustion gas from the burner 21 toward the opening 23 is delayed, and the secondary air for combustion is placed near the flame outlet of the burner 21 The air holes 21a and the air holes 24b are provided in two stages. As a result, the gas was gradually burned in a state where the combustion air was insufficient, so that the combustion reaction was delayed. As described above, when the combustion reaction of the flame becomes slow, the combustion temperature does not become high, so the amount of nitrogen monoxide (NO), which is a raw material of nitrogen dioxide, is reduced. An air intake 20 is opened at the lower part of the rear surface 2B of the combustion housing 2 and air is sucked into the combustion housing 2 from the air intake 20 by the suction force generated by the operation of the blower fan 3. Part of the air sucked into the combustion casing 2 is used as secondary air for combustion of the primary flame formed in the flame opening of the burner 21 through the air hole 21 a, and the rest passes through the outside of the combustion cover 22. Flow upward. The air flowing outside the combustion cover 22 rises while being heated through the combustion cover 22. A part of the heated air is introduced into the combustion cover 22 through the air hole 24b, and is used as secondary air for combustion of the secondary flame rising from the throttle portion 24a. The remaining air further rises along the partition cover 5. As shown in FIG. 3, the partition cover 5 has a plurality of slit hole-shaped openings 51 arranged in the left-right direction along the flow direction F of the combustion gas discharged from the openings 23 in the present embodiment. It is established side by side (for example, 15 rows).
[0010]
On the other hand, a shunt plate 4 that covers the exhaust port 25 over the entire width in the left-right direction is attached to the combustion housing 2 with a small clearance between the combustion housing 2 and the rear surface 2B. The flow dividing plate 4 covers the upper side of the exhaust port 25 from the rear surface 2B of the combustion housing 2, and further hangs down to the front side to form a combustion gas passage 26 between the front surface 2F of the combustion housing 2. The lower end edge 41 of the flow dividing plate 4 is positioned below the upper edge of the front face 2F, which is the front peripheral edge of the exhaust port 25, that is, the combustion gas discharged from the partition cover 5 is combusted by the combustion housing 2. The air flows through the combustion gas passage 26 for a distance L without being mixed with the air flowing outside. On the other hand, the portion of the upper half of the front surface 2F that opposes the front hanging portion of the flow dividing plate 4 is bent inward so that the combustion gas passage 26 expands in the passage toward the upstream portion 26a. Thus, if the volume of the upstream part 26a is expanded, the exhaust port 25 and the flow dividing plate 4 will leave | separate, and it can prevent that the flow dividing plate 4 is heated more than necessary by the combustion gas discharged | emitted from the exhaust port 25. FIG. By the way, the front hanging portion of the flow dividing plate 4 is not inflated outward and away from the exhaust port 25, but the upper half of the front plate 2F is bent inward in this way, so that the main body 1 does not become large. In this embodiment, the distance L is set to approximately 50 mm so that the temperature of the combustion gas at the outlet of the exhaust passage 26 is approximately 600 degrees. 2 is a lid plate, which is inserted into the combustion housing 2 from the opening with the combustion cover 22 and the partition wall cover 5 attached to the burner 21, and then the opening of the combustion housing 2 is opened by the lid plate 6. The combustion cover 22 and the partition wall cover 5 are covered with the combustion housing 2 by closing them so that the suction force of the blower fan 3 is short-circuited so as not to act.
[0011]
By the way, the combustion housing 2, the blower fan 3, and the flow dividing plate 4 are disposed in a hot air passage 4B defined by a wall plate 13 provided in the main body 1, and an electric device and the like not shown are stored. The warm air was prevented from flowing into the space 4C. Therefore, the air sucked from the suction port 11 by the operation of the blower fan 3 flows to the blower fan 3 through the gap 4A between the wall plate 13 and the flow dividing plate 4. The combustion gas discharged from the combustion cover 22 flows while being guided by the flow dividing plate 4, so that heat exchange is performed between the air and the combustion gas via the flow dividing plate 4. As a result, the air is heated by the combustion gas through the flow dividing plate 4 while flowing through the gap 4A, and the combustion gas is gradually cooled by being deprived of heat by the air through the flow dividing plate 4. Therefore, the temperature difference between the air and the combustion gas is small when the air and the combustion gas are mixed downstream from the lower end edge 41 of the flow dividing plate 4, and the combustion gas is rapidly cooled even when the air is mixed with the combustion gas. It is never done. An opening 14 is provided in the lower part of the wall plate 13, and air is allowed to flow from the suction port 11 through the space 4C and the opening 14 to the hot air passage 4B to cool the electrical components and the like. Further, although the volume of the upstream portion 26a of the combustion gas passage 26 is increased, the opening at the outlet of the combustion gas passage 26 is restricted to the dimension H, so that the amount of air taken in from the air intake 20 is limited, and the combustion gas The combustion gas in the passage 26 is not rapidly cooled by excess air.
[0012]
Referring to FIG. 4, the air rising along partition wall cover 5 is introduced into partition wall cover 5 through opening 51 formed in back surface part 5 a and inclined part 5 b of partition wall cover 5, and partition wall cover 5. It is gradually mixed with the combustion gas inside. The combustion gas gradually cooled in the partition wall cover 5 is discharged through an opening 51 formed in the front surface portion 5 c of the partition wall cover 5. Further, when the combustion gas generated in the vicinity of the upstream side of the front surface part 5c passes through the opening 51 of the front surface part 5c, the front surface part 5c acts as a cooling part, and lowers the temperature of the combustion gas itself.
[0013]
Note that the openings formed in the partition cover 5 are not limited to the slit-shaped openings 51 shown in FIG. 3, and for example, the circular holes may be arranged in a plurality of rows along the combustion gas flow direction F. Good. By the way, as shown in FIG. 1, the air rising between the combustion cover 22 and the combustion housing 2 is heated by the combustion cover 22 during the rising. However, since the front surface 2F of the combustion housing 2 is in contact with the combustion gas passage 26 through which a relatively high-temperature combustion gas passes, the rear surface 2B faces the suction port 11, so that the air rising on the rear side of the combustion cover 22 is not When the temperature is lower than that of the air rising on the front side and mixing with the combustion gas discharged from the opening 23, the cooling rate of the combustion gas is increased. In the present embodiment, the inclined portion 5b that extends upward while being inclined forward is provided on the partition wall on the rear side of the partition cover 5, so that the air that has risen to the rear side of the combustion cover 22 is gradually increased with respect to the combustion gas. To be mixed. Since the inclined portion 5b is inclined so as to be parallel to the flow dividing plate 4, the passage of the air rising on the rear side of the combustion cover 22 is not narrowed.
[0014]
By the way, the rapid cooling can be further prevented by increasing the opening area of the opening 51 along the flow direction of the combustion gas and increasing the upstream side as it goes downstream. In order to increase the opening area of the opening portion as it goes downstream, the width of the opening portion 51 is formed so as to become narrower as it goes downward, or the depth of a part of the plurality of opening portions 51 opened. Should be shallow.
[0015]
As an example of the partition cover 5 shown in FIG. 3, the concentration of nitrogen dioxide, the concentration of nitrogen oxides when the input to the burner is 3000 kilocalories using 15 rows of slits having a width of 2 mm and 10 mm intervals are provided. Nitrogen dioxide conversion rates were 5.9 ppm, 12.5 ppm, and 47.2%, respectively.
[0016]
In the above-described embodiment, the secondary air of the combustion cover is taken in two stages, but it may be taken in one stage or in three or more stages. Further, although the flow dividing plate 4 is attached without leaving a gap between the rear surface 2B of the combustion housing 2, a small gap is provided, or a small hole is formed in the flow dividing plate 4 to make a small amount in the combustion gas passage 26. You may make it adjust the slow cooling rate of the combustion gas discharged | emitted from the combustion housing | casing 2 by taking in air. In addition, you may form the opening part 51 in the slit-shaped long hole shape long in a horizontal direction.
[0017]
By the way, in said embodiment, the circular air hole 24b was provided in the side wall of the combustion cover 22 other than the air hole 21a. This is because a small amount of secondary air is introduced while the combustion gas is rising. Therefore, instead of the air holes 24b, slit-like air holes 24c are provided in the combustion cover 22 as shown in FIG. 5, and secondary air is continuously introduced into the combustion cover 22 along with the rise of the combustion gas. May be.
[0018]
【The invention's effect】
As is apparent from the above description, according to the present invention, the cooling rate of the combustion gas discharged from the combustion cover is delayed and the temperature of the combustion gas itself is lowered to reduce the temperature of the combustion gas itself. The nitrogen content can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an embodiment of the present invention. FIG. 2 is an exploded perspective view showing a structure of a combustion housing. FIG. 3 is a partial perspective view showing details of a shape of a partition cover. FIG. 5 is a partially enlarged view showing the flow of air. FIG. 5 is a partial perspective view showing another embodiment of the combustion cover.
DESCRIPTION OF SYMBOLS 1 Main body (of warm air heater) 2 Combustion housing 3 Blower fan 5 Bulkhead cover 11 Suction port 12 Blower port 21 Burner 22 Combustion cover

Claims (1)

It has a combustion housing with a burner inside, and a combustion cover that surrounds the flame of the burner, and supplies the air introduced into the combustion housing to the flame through an air hole opened in the combustion cover. In the hot air heater that mixes the combustion gas discharged from the air and the air sucked by the blower fan and blows it as hot air outside the device, a partition wall is provided that surrounds the outlet of the combustion cover. Opening an opening over a predetermined range along the flow direction of the combustion gas discharged from the outlet of the combustion cover, supplying air to the combustion gas surrounded by the partition wall through the opening, and A warm air heater characterized in that an opening is formed in a part of the partition wall so as to cross the flow of the combustion gas to provide a cooling unit for the combustion gas.

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