JP4494346B2 - Combustion heater - Google Patents

Description

  The present invention relates to a combustion heater.

Microcombustors are being developed as an alternative to electric heaters.
The micro combustor is a small combustion heater having a diameter of about several centimeters, and has a combustion chamber, an unburned gas passage, and a combustion gas passage in a main body container. And the unburned gas flowing through the unburned gas flow path is preheated by the heat of the combustion gas flowing through the combustion gas flow path, and the extinction distance where the flame cannot normally propagate through the dimensions of the portion facing the combustion chamber in the unburned gas flow path By forming it smaller than this, excess enthalpy combustion is realized in the combustion chamber.
As a micro combustor, a so-called Swiss roll type in which an unburned gas flow path and a combustion gas flow path are arranged in a spiral shape around a combustion chamber has been proposed. The Swiss roll type can sufficiently preheat the unburned gas, thereby realizing stable excess enthalpy combustion in the combustion chamber.
Japanese Patent Laid-Open No. 2004-20083 JP-A-2005-76973

By the way, the Swiss roll type micro combustor burns unburned gas in a narrow space (combustion chamber) in the center of the main body container. For this reason, there is a problem that the combustion load factor (the amount of heat generated per unit volume in the combustion chamber) becomes extremely large, and the main body container is locally degraded and damaged.
Moreover, since the shape of the flow path is complicated (spiral), there is a problem that the cost of the apparatus becomes high, and the realization of an inexpensive apparatus is required.

  This invention is made | formed in view of the situation mentioned above, and it aims at proposing the combustion heater which can suppress a combustion load factor by increasing the volume of a combustion chamber easily. Another object of the present invention is to propose a combustion heater having a simple structure.

The combustion heater according to the present invention employs the following means in order to solve the above problems.
The present invention includes a combustion chamber and a non-combusted gas that is guided into the combustion chamber in a main body container including a pair of flat plates of the same shape arranged in parallel and an outer peripheral wall surrounding the outer periphery of the pair of flat plates. The combustion gas flow path, the combustion gas flow path for guiding the combustion gas from the combustion chamber to the outside of the main body container, the unburned gas flow path and the combustion gas flow path are separated, and the unburned gas is heated by the heat of the combustion gas. A combustion heater comprising a heat transfer wall for preheating combustion gas, wherein the unburned gas flow path and the combustion gas flow path are overlapped in a direction perpendicular to the pair of flat plates between the pair of flat plates. And the combustion chamber is arranged along the outer peripheral wall .
According to the present invention, an apparatus having a flow path capable of heat exchange can be realized at low cost without the need to form a complicated flow path.
Moreover, since the volume of the combustion chamber can be increased, the problem that the combustion load factor is lowered and the main body container is locally deteriorated or damaged can be avoided.

  Further, in the case where the heat transfer wall is made of a flat plate smaller than the pair of flat plates and is spaced apart from the pair of flat plates, the flat heat transfer wall is simply disposed, and the unheated The gas channel and the combustion gas channel can be arranged so as to overlap each other in a direction perpendicular to the pair of flat plates.

When the main body container is formed in a circular shape or a rectangular shape as viewed from the flat plate side, a combustion heater suitable for heating an object to be heated can be obtained.

According to the present invention, the following effects can be obtained.
Since the volume of the combustion chamber in the main body container can be easily increased, the combustion load factor can be lowered. Further, the unburned gas passage and the combustion gas passage can be easily formed in the main body container, and an inexpensive apparatus can be realized.
“Unburned gas” means a gas before combustion, and “combusted gas” means a gas after combustion.

Hereinafter, a combustion heater according to the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view and a cross-sectional view showing a configuration of a combustion heater 10 according to an embodiment of the present invention.
The combustion heater 10 is supplied in a state (premixed gas G1) in which fuel gas such as city gas and air as combustion oxidant gas are premixed in the closed internal space of the main body container 11. This is a so-called premix type combustion heater.
The main body container 11 of the combustion heater 10 is formed by closing the upper and lower sides of a cylindrical outer peripheral wall 15 with a disk-shaped upper wall 16 and a lower wall 17 (hereinafter also referred to as upper and lower walls 16, 17). The diameters of the upper wall 16 and the lower wall 17 are larger than the height of 15.
The upper and lower walls 16 and 17 occupy most of the outer surface of the main body container 11. The upper and lower walls 16 and 17 are heated by the combustion of the premixed gas G1, and the object to be heated (not shown) is heated by the heat released from the upper and lower walls 16 and 17.
The upper and lower walls 16 and 17 are made of a material having high heat conductivity (for example, brass (brass)). Moreover, you may use as the surface which discharge | releases heat by making the outer peripheral wall 15 into the same material as the upper and lower walls 16,17.

A heat transfer wall 18 having a smaller diameter than the upper and lower walls 16, 17 is disposed in the main body container 11. The heat transfer wall 18 is disposed substantially parallel to the upper and lower walls 16 and 17 while being separated from the outer peripheral wall 15 and the upper and lower walls 16 and 17, respectively. The heat transfer wall 18 is formed of a material having high heat transfer properties, like the upper and lower walls 16 and 17.
As a result, a disc-shaped space sandwiched between the lower wall 17 and the heat transfer wall 18 is formed as a premixed gas flow path 13 for supplying the premixed gas (unburned gas) G1 to the combustion chamber 12.
A disk-shaped space sandwiched between the upper wall 16 and the heat transfer wall 18 is formed as a combustion gas passage 14 for discharging the combustion gas G2 from the combustion chamber 12 to the outside.
Further, an annular space surrounded by the outer peripheral wall 15, the upper wall 16, the lower wall 17 and the heat transfer wall 18, that is, a space along the outer peripheral wall 15 is formed as the combustion chamber 12. An ignition device (not shown) is provided in a part of the combustion chamber 12.
In other words, as shown in FIG. 1B, the premixed gas flow path 13 and the combustion gas flow path 14 are disposed in the main body container 11 in the thickness direction (the direction perpendicular to the upper wall 16 and the lower wall 17). Are placed one on top of the other.

A double pipe 30 having an inner channel 31 and an outer channel 32 is connected to the center of the lower wall 17 of the main body container 11.
A hole 17h having the same diameter as the inner diameter of the outer flow path 32 is provided at the center of the lower wall 17, and the outer flow path 32 is connected to the outer peripheral portion of the hole 17h. A hole 18h having the same diameter as the inner diameter of the inner flow path 31 is provided at the center of the heat transfer wall 18, and the inner flow path 31 is connected to the outer peripheral portion of the hole 18h.
Thereby, the inner side flow path 31 and the combustion gas flow path 14 are connected, and the outer side flow path 32 and the premixed gas flow path 13 are connected.

With such a configuration, when the premixed gas G1 is supplied to the outer flow path 32 of the double pipe 30, the premixed gas G1 flows into the premixed gas flow path 13 from the center of the main body container 11, and further, the outer peripheral wall 15 It flows radially toward the annular combustion chamber 12 formed along the line.
Then, the premixed gas G1 is combusted in the combustion chamber 12 to generate combustion gas G2. The combustion gas G <b> 2 flows from the combustion chamber 12 through the combustion gas channel 14 toward the center of the main body container 11 and flows into the inner channel 31 of the double pipe 30.

At this time, the premixed gas G1 is preheated by the heat of the combustion gas G2. As described above, since the heat transfer wall 18 is formed of a material having high heat transfer properties, the heat of the combustion gas G2 is transferred to the premixed gas G1 through the heat transfer wall 18. In particular, the combustion gas G2 flowing through the combustion gas flow path 14 and the premixed gas G1 flowing through the premixed gas flow path 13 are counterflows (counter flow) with the heat transfer wall 18 interposed therebetween, so the combustion gas G2 It is possible to efficiently preheat the premixed gas G1 with this heat.
Thus, since the premixed gas G1 is sufficiently preheated before being introduced into the combustion chamber 12, stable combustion is obtained in the combustion chamber 12.

Further, in order to enable stable combustion in the combustion chamber 12, the representative dimension in the cross-sectional shape of the premixed gas flow path 13 is a flame extinguishing distance (a flame extinguishing equivalent diameter) that does not allow a flame to pass (the combustion reaction is not propagated). Including)).
In general, the extinction distance d of the premixed gas is expressed by the size of the diameter of the tube wall model, and is obtained by the equation (1).
d = 2λ · Nu ^1/2 / C _p · ρ _u · S _u (1)
In equation (1), d is the flame extinguishing distance, λ is the thermal conductivity, Nu is the Nusselt number, C _p is the constant pressure specific heat, ρ _u is the premixed gas density, and _Su is the combustion rate.
The representative dimensions of the cross-sectional shape of the premixed gas flow path 13 vary depending on the cross-sectional shape of the portion facing the combustion chamber 12. For example, when the channel cross-sectional shape is circular, the representative dimension indicates a diameter of a circular cross section, and when the channel cross-sectional shape is other than a circular shape, the representative dimension indicates a hydraulic equivalent diameter of the cross section.

Here, the hydraulic equivalent diameter is obtained by the following equation (2).
Hydraulic equivalent diameter D = 4 × channel cross-sectional area / wetting edge periphery length (2)
In addition, the site | part which takes a representative dimension is not only the site | part which faces the combustion chamber 12, but the site | part which predominates this combustion phenomenon among the premixed gas flow paths 13. FIG.

  Specifically, as shown in FIG. 1B, the distance L between the lower wall 17 and the heat transfer wall 18 is defined to be equal to or less than the flame extinguishing distance. As a result, the flame does not enter the premixed gas flow path 13 and stable combustion in the combustion chamber 12 is realized.

The representative dimension of the premixed gas flow path 13 is not limited to the distance between the lower wall 17 and the heat transfer wall 18. For example, as shown in FIG. 2A, an annular protrusion 25 is provided on the outer periphery of the lower surface 18b of the heat transfer wall 18, and the distance L between the protrusion 25 and the lower wall 17 may be a representative dimension. .
In addition, the protrusion 25 is not limited to an annular shape, and a plurality of protrusions 26 are arranged at regular intervals at predetermined intervals on the outer peripheral portion of the lower surface 18b of the heat transfer wall 18 as shown in FIG. 2 (b). May be. In this case, the distance L between the protrusions 26 is the representative dimension.

  With the above configuration, in the combustion heater 10, the combustion of the premixed gas G <b> 1 is stably performed in the combustion chamber 12. Further, the combustion temperature can be accurately controlled by adjusting the flow rate of the premixed gas G1.

In addition, since the combustion chamber 12 is disposed along the outer peripheral wall 15 in the main body container 11, the volume of the combustion chamber 12 increases. Thereby, since a combustion load factor becomes low, the malfunction that the main body container 11 deteriorates locally and is damaged is avoided.
Moreover, since the combustion heater 10 only has the flat plate-shaped heat transfer wall 18 in the main body container 11, the premixed gas channel 13 and the combustion gas channel 14 can be easily formed. Thereby, it is possible to realize an inexpensive apparatus as compared with the Swiss roll type.

  Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, as shown in FIG. 3, a plurality of heat dissipation protrusions 21 may be provided on the lower surface 18 b of the heat transfer wall 18. By providing the heat dissipation projections 21, the area where the premixed gas G1 touches the heat transfer wall 18 increases, and heat exchange with the premixed gas G1 can be performed more efficiently.

Further, as shown in FIG. 4A, a plurality of heat absorption protrusions 22 may be provided on the upper surface 18 a of the heat transfer wall 18. By providing the heat absorption protrusion 22, the area where the combustion gas G <b> 2 touches the heat transfer wall 18 is increased, and heat exchange with the heat transfer wall 18 can be performed more efficiently.
In addition, you may make it heat the upper wall 16 more efficiently by providing the protrusion for heat absorption in the upper wall 16 of the main body container 11, and may increase the thermal radiation amount to the exterior.

  Further, for example, as shown in FIG. 4B, a spiral heat absorption protrusion 23 may be provided on the upper surface 18 a of the heat transfer wall 18. Since the length of the combustion gas channel 14 is extended, heat exchange between the combustion gas G2 and the heat transfer wall 18 can be performed more efficiently.

  Further, the shape of the heat transfer wall 18 is not limited to the disk shape, and may be formed in a star shape or the like as shown in FIG. By setting it as such a shape, the volume of the combustion chamber 12 can further be increased.

Further, the shape of the main body container 11 viewed from the thickness direction is not limited to a circular shape or an elliptical shape, and may be a triangular shape, a rectangular shape, a polygonal shape higher than that, or a star shape.
For example, when the shape of the main body container 11 viewed from the thickness direction is a quadrangle, the combustion chambers 12 may be disposed on all four sides as shown in FIG. Moreover, as shown in FIG.6 (b), you may arrange | position the combustion chamber 12 only to two opposing sides.
Furthermore, as shown in FIG. 6C, the combustion chamber 12 may be disposed only on a specific side. In this case, the double pipe 30 connected to the premixed gas flow path 13 and the combustion gas flow path 14 does not need to be provided at the center of the main body container 11.

  In addition, the “premix type” in which the fuel and the oxidant for combustion are mixed in advance has been described as an example, but the present invention can also be applied to a “diffusion type” combustion heater in which both are mixed in the combustion chamber to perform diffusion combustion. .

The inner channel 31 and the combustion gas channel 14 of the double pipe 30 are connected, and the outer channel 32 and the premixed gas channel 13 are not connected. That is, the inner flow path 31 and the premixed gas flow path 13 of the double pipe 30 may be connected, and the outer flow path 32 and the combustion gas flow path 14 may be connected.
Further, the gas supply pipe connected to the premixed gas flow path 13 is connected to the lower wall 17 and the gas discharge pipe connected to the combustion gas flow path 14 is connected to the upper wall 16, not necessarily when the double pipe 30 is used. You may connect.

  In addition, as shown in FIG. 7, by arranging two heat transfer walls 18 and 19 in parallel in the main body container 11, the combustion gas flow path 14 a, the heat transfer wall 18, the premixed gas flow path 13, The heat transfer wall 19 and the combustion gas flow path 14 b may be arranged so as to overlap in the thickness direction of the main body container 11. With such a configuration, the upper wall 16 and the lower wall 17 are similarly heated, so that heat can be radiated to the outside more uniformly.

  Further, the combustion heater 10 is not limited to a small one having an outer shape of about several centimeters, but may be one having several tens of centimeters to several tens of meters.

It is the perspective view and sectional drawing which show the combustion heater 10 which concerns on embodiment of this invention. It is a figure which shows the case where the projection parts 25 and 26 are provided in the lower surface 18b of the heat-transfer wall 18. FIG. It is a figure which shows the case where the protrusion 21 for thermal radiation is provided in the lower surface 18b of the heat-transfer wall 18. FIG. It is a figure which shows the case where the heat absorption protrusions 22 and 23 are provided in the upper surface 18a of the heat transfer wall 18. FIG. It is a figure which shows the modification of the heat-transfer wall. It is a figure which shows the modification of the combustion heater 10 which concerns on embodiment of this invention. It is a figure which shows the modification of the combustion heater 10 which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Combustion heater 11 ... Main body container 12 ... Combustion chamber 13 ... Premixed gas flow path (unburned gas flow path)
14 ... Combustion gas flow path 15 ... Outer peripheral wall 16 ... Upper wall (flat plate)
17 ... Lower wall (flat plate)
18, 19 ... Heat transfer wall 18a ... Upper surface (wall surface on the combustion gas flow path side)
18b ... lower surface (wall surface on the unburned gas flow path side)
21 ... Radiation projection 22, 23 ... Endothermic projection 25, 26 ... Projection 30 ... Double pipe 31 ... Inner channel (second channel)
32 ... Outer channel (first channel)
G1 ... Premixed gas (unburned gas)
G2 ... Combustion gas

Claims (4)

An unburned gas flow path for introducing unburned gas into the combustion chamber and the combustion chamber in a main body container constituted by a pair of flat plates of the same shape arranged in parallel and an outer peripheral wall surrounding the outer periphery of the pair of flat plates A combustion gas flow path for guiding combustion gas from the combustion chamber to the outside of the main body container, the unburned gas flow path and the combustion gas flow path, and preheating the unburned gas with the heat of the combustion gas A combustion heater comprising a heat transfer wall,
Between the pair of flat plates, the unburned gas flow path and the combustion gas flow path are arranged in a direction perpendicular to the pair of flat plates ,
A combustion heater, wherein the combustion chamber is disposed along the outer peripheral wall .   2. The combustion heater according to claim 1, wherein the heat transfer wall includes a flat plate that is smaller than the pair of flat plates and is spaced apart from the pair of flat plates.   The combustion heater according to claim 1, wherein the main body container is formed in a circular shape when viewed from the flat plate side.   The combustion heater according to claim 1 or 2, wherein the main body container is formed in a rectangular shape when viewed from the flat plate side.

Images