JP5724686B2 - Combustion heater - Google Patents

Description

  The present invention relates to a combustion heater that heats an object to be heated by burning fuel.

  2. Description of the Related Art Conventionally, a combustion heater that heats a radiator with combustion heat obtained by burning fuel gas and heats industrial materials, foods, and the like with radiation heat from a radiation surface of the radiator has been widely used. For such a combustion heater, for example, a technique of applying a material and shape having a high emissivity to the radiation surface in order to improve the radiation intensity has been proposed (for example, Patent Document 1).

  In addition, a technique for increasing the flame holding effect by providing a vortex portion in the vicinity of the outlet of the flame hole where the fuel gas flows out and burns so that the flow path of the fuel gas expands to generate a vortex is proposed. (For example, Patent Document 2).

  Furthermore, a combustion heater with improved thermal efficiency has been proposed. This combustion heater has a sealed structure from the fuel gas introduction path to the combustion chamber and the exhaust gas outlet path after combustion, and the introduction path and the outlet path are adjacent to each other, so that the heat of the exhaust gas before combustion The fuel gas is preheated to increase the thermal efficiency (for example, Patent Document 3).

JP 2004-324925 A Japanese Patent Laid-Open No. 6-147431 JP 2007-212082 A

  In the combustion heater as in Patent Document 3 described above, in the fuel gas introduction path in the vicinity of the combustion chamber, a plurality of protrusions narrow the flow path, thereby shortening the extinguishing distance and preventing backfire. The fuel gas flowing out into the combustion chamber collides with the wall surface of the combustion chamber, flows upward along the wall surface, and then turns back in a direction away from the wall surface. The flame holding property is improved by reducing the flow rate of the fuel gas in this folding.

  However, when the fuel gas flows into the combustion chamber through the gaps between the plurality of protrusions before the fuel gas collides with the wall surface, the flow path gradually expands, so that a vortex is formed as in Patent Document 2. However, in the combustion heater as in Patent Document 3, the vortex generated when entering the combustion chamber becomes a factor that weakens the collision of the fuel gas with the wall surface. For this reason, the flow of the fuel gas that is folded back in the vicinity of the wall surface that should originally be flame-stabilized is not stable, and the flame-holding property of the combustion heater is reduced.

  In view of such a problem, an object of the present invention is to provide a combustion heater capable of improving flame holding properties and realizing stable combustion heating.

  In order to solve the above problems, a combustion heater of the present invention is arranged along the outer periphery of a heating plate, an arrangement plate disposed opposite to the heating plate, the heating plate and the arrangement plate, the heating plate and the arrangement plate, The outer wall surrounding the space, the partition plate arranged between the heating plate and the arrangement plate, the heating plate, the arrangement plate, the combustion chamber arranged in the space enclosed by the outer wall, the arrangement plate and the partition plate And an inlet passage that leads the fuel gas continuously to the combustion chamber with the side wall as a side wall, and guides the exhaust gas from the combustion chamber to the outside of the combustion heater continuously from the combustion chamber with the heating plate and the partition plate as the side wall. A lead-out path for preheating the fuel gas with the heat of the exhaust gas through, and a protrusion that narrows the flow path of the fuel gas at a position where the introduction path and the combustion chamber are continuous, the protrusion from the introduction path to the combustion chamber It has a gradual decrease part where the thickness gradually decreases in the flow direction of the fuel gas to

  The protrusion may be provided only on the partition plate in the introduction path.

  The protrusion may be provided only on the arrangement plate in the introduction path.

  According to the combustion heater of the present invention, flame holding property can be improved and stable combustion heating can be realized.

It is an assembly drawing for demonstrating the structure of a combustion heater. It is AA sectional drawing of FIG. It is explanatory drawing for demonstrating a some projection part. It is explanatory drawing for demonstrating an eddy current. It is explanatory drawing for demonstrating the fall of CO discharge density | concentration. It is explanatory drawing for demonstrating the other example regarding a some projection part. It is explanatory drawing for demonstrating a some projection part.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  In conventional combustion heaters, exhausted exhaust gas (combustion gas: gas after combustion) is exhausted to the surrounding environment without being recovered, and the heat efficiency of the exhaust gas is low because the heat of the exhaust gas cannot be used. In some cases, the heat of the exhaust gas increases the temperature of the environment around the device or the exhaust gas fills up, making it impossible to improve the working environment. On the other hand, in the closed combustion heater, the combustion chamber, the introduction path of the fuel gas (unburned gas: gas before combustion), and the exhaust gas outlet path are sealed in the main body container. Excess enthalpy combustion is realized in the combustion chamber by preheating the fuel gas flowing through the inlet passage with the heat of the exhaust gas flowing through the outlet passage. Since such a combustion heater recovers the heat of the exhaust gas, the heat efficiency is high and the exhaust gas itself is also recovered, so that the working environment is not impaired. In addition, since the flame opening is unnecessary, there is an advantage that the area of the radiation surface is not reduced and the radiation intensity is high.

  As such a hermetic combustion heater, a Swiss roll type or a disk type has been proposed. In the Swiss roll type, a combustion chamber is formed at the center of the main body container, and the introduction path and the discharge path are arranged in parallel in a spiral shape. This Swiss roll type combustion heater has a difficulty in that the manufacturing cost becomes high due to its complicated shape. On the other hand, in the disk-type combustion heater, the partition plate responsible for heat transfer is a thin plate that is smaller than the pair of thin plates (heating plate, arrangement plate) constituting the main body container, and between the heating plate and the arrangement plate. Heat is exchanged between the introduction path and the outlet path with a simple configuration in which a gap is provided. In addition, the disc-type combustion heater has a higher degree of freedom in the shape of the heating plate having a radiation surface than the Swiss roll type, and is not limited to a substantially circular shape like the Swiss roll type, but can be an oval or It can be formed in a rectangular shape. Furthermore, since the arrangement of the combustion chamber is not limited to the center of the main body container, the disk type combustion heater can increase the volume of the combustion chamber itself as compared to the Swiss roll type, and the combustion load factor (per unit volume in the combustion chamber) (Heat generation) can be suppressed.

  By the way, in the introduction path of the fuel gas in the vicinity of the combustion chamber, a plurality of protrusions narrow the flow path, and the representative distance is made shorter than the extinguishing distance to prevent backfire. However, when the gas flows into the combustion chamber from the gaps between the plurality of protrusions, the flow path expands stepwise, so that a vortex is formed. Such a vortex inherently destabilizes the flow of the fuel gas in the vicinity of the wall surface of the outer peripheral wall to be flame-fixed, so that the flame holding performance in the vicinity of the wall surface of the outer peripheral wall is degraded.

  Therefore, the combustion heater 100 of the present embodiment aims to improve the flame holding property and stabilize the combustion heating. Hereinafter, a detailed configuration of the combustion heater 100 capable of realizing such an object will be described.

(First embodiment: combustion heater 100)
FIG. 1 is an assembly diagram for explaining the structure of the combustion heater 100, and FIG. 2 is a cross-sectional view taken along line AA in FIG. As shown in FIG. 2A, the combustion heater 100 includes a heating plate 118, an arrangement plate 120, an outer peripheral wall 122, a partition plate 124, a combustion chamber 126, an introduction path 128, and a lead-out path 130. The first piping part 132 and the second piping part 134 are configured. In the present embodiment, the combustion heater 100 will be described by taking an example in which the outer shape is about 220 mm × 140 mm. However, the external shape of the combustion heater 100 is not limited to such a size, and can be set to an arbitrary size.

  The combustion heater 100 in the present embodiment is a premixed type in which a main body container is supplied with a fuel gas (premixed gas) in which city gas or the like and air as a combustion oxidant gas are mixed in advance. It is not limited to such a case, but may be a diffusion type in which both are mixed to perform diffusion combustion in the combustion chamber 126 or the introduction path 128 immediately before the combustion chamber 126.

  The heating plate 118 and the arrangement plate 120 are arranged to face each other and are made of a material having high heat resistance and oxidation resistance, such as stainless steel (SUS: Stainless Used Steel), or a material having high thermal conductivity, such as brass (brass). ) And the like, and are arranged substantially parallel to each other (substantially parallel for causing excess enthalpy combustion in the present embodiment). The heating plate 118 and the arrangement plate 120 also function as a radiator that is heated by the combustion heat generated in the combustion chamber 126. However, the arrangement | positioning board 120 is not restricted to the structure which functions as a radiator, For example, it is good also as a heat insulation structure.

  The outer peripheral wall 122 has an inner periphery formed into a track shape (a shape composed of two substantially parallel line segments and two arcs (semicircles) connecting the two line segments) and a rectangular outer periphery when viewed from above. The heating plate 118 and the arrangement plate 120 are arranged along the outer periphery, and the heating plate 122 and the arrangement plate 120 surround the space. Moreover, the outer peripheral surface of the outer peripheral wall 122 can also be used as a radiation surface.

  The main body container of the combustion heater 100 is formed by closing the outer peripheral wall 122 and the upper and lower sides of the outer peripheral wall 122 with the heating plate 118 and the arrangement plate 120, and the upper and lower wall surfaces from the area of the outer peripheral surface (the outer surface of the outer peripheral wall 122). The area of (the outer surface of the heating plate 118 and the arrangement plate 120) is larger. That is, the upper and lower wall surfaces occupy most of the outer surface of the main body container. Of these upper and lower wall surfaces, for example, the upper surface becomes a radiation surface, and when the fuel gas burns in the combustion chamber 126, heat is transmitted from the radiation surface by radiation or air convection to heat the object to be heated. In the present embodiment, the upper surface (the upper surface of the heating plate 118) of the upper and lower wall surfaces is the radiation surface. However, the present invention is not limited to this, and the lower surface (the lower surface of the arrangement plate 120) is the radiation surface. Both the upper and lower wall surfaces may be radiation surfaces.

  The partition plate 124 has a smaller outer shape than the heating plate 118 and the arrangement plate 120, and is formed in a shape along the inner peripheral surface of the outer peripheral wall 122, and the heating plate 118 and the arrangement plate are interposed between the heating plate 118 and the arrangement plate 120. 120 is arranged substantially parallel to 120. Gaps are formed between the partition plate 124, the heating plate 118, and the arrangement plate 120, respectively. The partition plate 124 is formed of a material having high heat resistance and oxidation resistance, such as stainless steel, or a material having high thermal conductivity, such as brass. The partition plate 124, the heating plate 118, and the arrangement plate 120 may be disposed to face each other as long as a gap is formed therebetween. In addition, the partition plate 124, the heating plate 118, and the arrangement plate 120 are not limited in thickness, and may be formed in an uneven shape without being limited to a flat plate.

  Here, the positional relationship among the heating plate 118, the arrangement plate 120, the outer peripheral wall 122, and the partition plate 124 will be described with reference to the assembly diagram of FIG. A partition plate 124 is disposed on the placement plate 120, and the outer peripheral wall 122 is overlaid on the placement plate 120 so as not to overlap the partition plate 124. Specifically, as shown in FIG. 2A, the arrangement plate 120 is fixed to the end of the first piping portion 132, while the partition plate 124 protrudes from the first piping portion 132. The arrangement plate 120 and the partition plate 124 are separated by the difference between the end portion of the first piping portion 132 and the end portion of the second piping portion 134. At this time, a gap as a combustion chamber 126 is formed between the side surface of the partition plate 124 and the cylindrical inner peripheral surface of the outer peripheral wall 122. Finally, the heating plate 118 is overlaid on the outer peripheral wall 122.

  The combustion chamber 126 is arranged in a space surrounded by the outer peripheral wall 122, the heating plate 118, and the arrangement plate 120. The combustion chamber 126 faces the outer peripheral end of the partition plate 124, and is formed along the outer peripheral wall 122 inside the outer peripheral wall 122. Thus, by the structure which forms the combustion chamber 126 along the outer peripheral wall 122, the volume of the combustion chamber 126 can fully be ensured, and a combustion load factor can be made low compared with a Swiss roll type. An ignition device (not shown) is provided at an arbitrary position of the combustion chamber 126.

  As shown in FIG. 2A, in the main body container, the introduction path 128 and the lead-out path 130 are formed so as to overlap in the thickness direction (the direction orthogonal to the upper surface of the heating plate 118).

  The introduction path 128 is a space sandwiched between the placement plate 120 and the partition plate 124 with the placement plate 120 and the partition plate 124 as side walls, and is continuously disposed in the combustion chamber 126 and flows into the center of the main body container. The fuel gas is guided radially to the combustion chamber 126.

  The lead-out path 130 has a heating plate 118 and a partition plate 124 as side walls, and is continuously arranged in the combustion chamber 126. The exhaust gas is concentrated from the combustion chamber 126 to the center of the main body container and out of the combustion heater 100. Lead. Further, as shown in FIG. 2A, in the main body container, the introduction path 128 and the outlet path 130 are formed so as to overlap in the thickness direction, so that the heat of the exhaust gas is transmitted through the partition plate 124, The fuel gas can be preheated.

  The first piping part 132 is inserted into the introduction path 128 and guides the fuel gas into the combustion heater 100. Specifically, a hole 158 having the same diameter as the inner diameter of the first piping portion 132 is provided at the center of the arrangement plate 120, and the first piping portion 132 is connected to the inner peripheral portion of the hole 158. .

  The second piping part 134 is arranged inside the first piping part 132. That is, the first pipe part 132 and the second pipe part 134 form a double pipe. Further, the second piping part 134 is inserted into the outlet path 130 and guides the exhaust gas to the outside of the combustion heater 100. Specifically, a hole 160 having the same diameter as the outer diameter of the second pipe part 134 is provided at the center of the partition plate 124, and the second pipe part 134 is fitted to the inner peripheral portion of the hole 160. The Furthermore, the second piping part 134 also plays a role of transmitting the heat of the exhaust gas to the fuel gas flowing through the first piping part 132.

  In the present embodiment, the second piping part 134 is arranged inside the first piping part 132, but the present invention is not limited to this, and the first piping part 132 and the second piping part 134 are introduced from the heating plate 118 side. The first piping part 132 may be arranged inside the second piping part 134 by being inserted through the path 128 and the outlet path 130.

  Here, the flow of the fuel gas and the exhaust gas will be specifically described. In FIG. 2 (b) in which the circle portion of FIG. 2 (a) is enlarged, the white arrow indicates the flow of fuel gas, the gray arrow indicates the flow of exhaust gas, and the black arrow indicates heat transfer. Show. When the fuel gas is supplied to the first piping part 132, the fuel gas flows into the introduction path 128 from the center of the arrangement plate 120 and flows toward the combustion chamber 126 while spreading radially in the horizontal direction. Then, the fuel gas collides with the outer peripheral wall 122 in the combustion chamber 126 and burns to become high-temperature exhaust gas. After the heat is transferred to the heating plate 118, the exhaust gas is transferred from the combustion chamber 126 to the second pipe through the outlet passage 130. Flows into the section 134.

  The partition plate 124 is formed of a material that is relatively easy to conduct heat, and the heat of the exhaust gas that passes through the outlet passage 130 is transmitted to the fuel gas that passes through the introduction passage 128 via the partition plate 124. Here, the exhaust gas flowing through the lead-out path 130 and the fuel gas flowing through the introduction path 128 are opposed to each other (counter flow) with the partition plate 124 interposed therebetween. Preheating is possible, and high thermal efficiency can be obtained. By so-called excess enthalpy combustion, in which fuel gas is preheated in this way, combustion of fuel gas can be stabilized and the concentration of CO (carbon monoxide) generated by incomplete combustion can be suppressed to an extremely low concentration. .

  Further, in order to enable stable combustion in the combustion chamber 126, a representative dimension in a cross-sectional shape perpendicular to the flow of exhaust gas (hereinafter referred to as a flow-path cross-sectional shape) at the boundary between the introduction passage 128 and the combustion chamber 126. In consideration of a flame extinguishing distance (including a flame extinguishing equivalent diameter) that does not allow a flame to pass through the introduction path 128 (a combustion reaction is not propagated toward the introduction path 128), it is preferable to set the flame extinguishing distance or less. Here, the representative dimension is a dimension determined by the cross-sectional shape of the flow channel immediately before the fuel gas flows into the combustion chamber 126. 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. The hydraulic equivalent diameter D is obtained by 4 × channel cross-sectional area / wetting edge length. The wetting edge length indicates the length of the wall (arrangement plate 120, partition plate 124) portion in contact with the fuel gas in the cross section of the flow path.

  For example, if the distance between the arrangement plate 120 and the partition plate 124 is set to be equal to or less than the flame extinguishing distance, the flame does not enter the introduction path 128 and the combustion is stabilized. However, in order to make the distance between the arrangement plate 120 and the partition plate 124 equal to or less than the extinguishing distance, it is necessary to increase the surface accuracy and the mounting accuracy of the arrangement plate 120 and the partition plate 124. Therefore, in this embodiment, the distance between the arrangement plate 120 and the partition plate 124 may be made larger than the flame extinguishing distance, and the arrangement plate is located near the combustion chamber 126 on the lower surface of the partition plate 124 (on the arrangement plate 120 side). A plurality of protrusions 152 that are in contact with 120 are arranged at a predetermined interval L.

  FIG. 3 is an explanatory diagram for explaining the plurality of protrusions 152. 3A is a perspective view of the combustion heater 100 that has passed through the heating plate 118 indicated by a broken line, and FIG. 3B is an explanatory view of the BB cross section of FIG. 3A viewed from the direction of the arrow. It is. In FIG. 3B, in order to facilitate understanding of the structure of the plurality of protrusions 152, a portion of the protrusion 152 hidden by the partition plate 124 is indicated by a broken line. An arrow 154 indicates the direction of fuel gas flow. The introduction channel 128 has a channel cross-section narrowed by a plurality of protrusions 152 provided on the partition plate 124. The fuel gas flows into the combustion chamber 126 through the gap between the adjacent projections 152 as shown in the partial enlarged view of FIG. 2B and the explanatory view of FIG. . At this time, the interval L between the protrusions 152 becomes the representative dimension of the cross-sectional shape of the flow path.

Here, the flame extinguishing distance d of the fuel gas is represented by the size of the diameter of the tube wall model, and is obtained by the equation (1).
d = 2λ · Nu ^1/2 / ( Cp · ρu · Su ) (1)
In equation (1), λ is the thermal conductivity, Nu is the Nusselt number, Cp is the constant pressure specific heat, ρu is the density of the fuel gas, and Su is the combustion rate.

  The combustion heater 100 according to the present embodiment is designed so that the above-described representative dimension (interval L between the protrusions 152) is equal to or less than the extinguishing distance d, so that stable combustion is possible in the combustion chamber 126.

  In such a combustion heater 100, a phenomenon has occurred in which the generation of eddy currents at a location different from the vicinity of the outer peripheral wall 122 that should originally hold the flame reduces the flame holding properties. Such a phenomenon will be described with reference to FIG.

  FIG. 4 is an explanatory diagram for explaining the eddy current. 4A shows only the vicinity of the two protrusions 152 in the CC sectional view in FIG. Moreover, in FIG.4 (b), sectional drawing corresponding to Fig.4 (a) in the conventional combustion heater is shown. Further, in FIGS. 4A and 4B, the flow of the fuel gas is indicated by arrows.

  As shown in FIG. 4B, in the conventional protrusion 10, the flow path sharply expands when fuel gas flows into the combustion chamber 126 from the gaps between the plurality of protrusions 10, so that a vortex is formed. End up. If it does so, as mentioned above, before a fuel gas collides with the outer peripheral wall 122, a flow will weaken originally and flame holding property will fall. As a result, the exhaust concentration of incompletely burned CO may increase.

  Therefore, the combustion heater 100 of the present embodiment includes a protrusion 152 having a shape as shown in FIG. The protrusion 152 narrows the fuel gas flow path 128 a at a position where the introduction path 128 and the combustion chamber 126 are continuous. Further, the protruding portion 152 gradually decreases in thickness in the flow direction of the fuel gas from the introduction path 128 to the combustion chamber 126 on the combustion chamber 126 side of the protruding portion 152, and a gradually decreasing portion 156 shown by a broken line in FIG. Have The protrusion 152 has a streamline shape with respect to the flow direction of the fuel gas.

  With this configuration, the fuel gas is less likely to generate a vortex until it collides with the outer peripheral wall 122, and after it collides with the outer peripheral wall 122, the fuel gas is turned back in the vicinity of the outer peripheral wall 122 (shown by a dashed line ellipse 158 in FIG. The gas flow is stabilized. Therefore, the combustion heater 100 has a high flame holding property in the vicinity of the outer peripheral wall 122.

  FIG. 5 is an explanatory diagram for explaining a decrease in the CO emission concentration. FIG. 5 shows an approximate relationship between the flow rate of the fuel gas and the CO emission concentration in the exhaust gas when the equivalence ratio of the fuel gas is constant. When a protrusion having no gradually decreasing portion 156 is provided, the CO emission concentration approaches or exceeds the self-regulated value of 100 ppm when the fuel gas flow rate is low and the load is low as in the legend 170. .

  However, when the protrusion 152 having the gradually decreasing portion 156 is provided as in the present embodiment, as shown in the legend 172, the combustion heater 100 can stably perform the combustion heating even at a low load. The operable load range can be expanded.

  FIG. 6 is an explanatory diagram for explaining another example of the plurality of protrusions 152. As shown in FIG. 6A, the protrusion 152 may be formed such that the width on the combustion chamber 126 side is narrower than the side opposite to the combustion chamber 126. Further, as shown in FIG. 6B, the width opposite to the combustion chamber 126 may be formed narrower than the combustion chamber 126 side. Further, as shown in FIG. 6C, the protrusion 152 may only be provided with an R at the corner.

  In any case, the protrusion 152 has a gradually decreasing portion 156 where the thickness of the protrusion 152 gradually decreases in the direction perpendicular to the outer periphery. Therefore, it is difficult for the fuel gas to generate a vortex until it collides with the outer peripheral wall 122, the flow of the fuel gas is stabilized, and the flame holding property is improved.

  FIG. 7 is an explanatory diagram for explaining the plurality of protrusions 152. In FIG. 7, in order to explain the shape of the protrusion 152, a portion of the partition plate 124 where the protrusion 152 is disposed is cut out, and a perspective view in which the protrusion 152 is an upper surface is shown.

  As shown in FIG. 7, the gradually decreasing portion 156 of the tip portion of the protrusion 152 is rounded so that the gaps between the plurality of protrusions 152 gradually increase in the direction of the arrow 158 and the height of the protrusion 152 gradually decreases. I am tinged.

  In other words, the gradually decreasing portion 156 is not limited to a portion where the thickness gradually decreases in the width direction of the protrusion 152, and may be a portion where the thickness gradually decreases in the height direction of the protrusion 152. Further, the gradual decrease portion 156 only needs to expand the flow path of the fuel gas constricted by the hole 160 side of the protrusion 152 toward the combustion chamber 126 side along the gradual decrease portion 156.

  With such a configuration, the flow of the fuel gas is more difficult to separate from the protrusion 152, and the combustion heater 100 further suppresses the generation of unnecessary vortex flow, and the generation of vortex flow in the vicinity of the outer peripheral wall 122 that should originally hold the flame. It becomes possible to stabilize.

  Further, compared to the conventional protrusion 10 shown in FIG. 4B, the protrusion 152 in the present embodiment has no corners, and thus can be easily formed by pressing, and the combustion heater 100 reduces the manufacturing cost. it can.

  In the present embodiment, the protrusion 152 is provided only on the partition plate 124 in the introduction path 128. Therefore, the process for forming the protrusion 152 may be performed only on the partition plate 124, and the manufacturing cost of the combustion heater 100 can be reduced as compared with the case where both are provided on the arrangement plate 120 and the partition plate 124.

  Further, the protrusion 152 may be provided only on the arrangement plate 120 in the introduction path 128. With this configuration, the partition plate 124 can be easily processed as a thin plate, and the combustion heater 100 can reduce manufacturing costs.

  As described above, the combustion heater 100 described above can improve flame holding properties and realize stable combustion heating.

  In the above-described embodiment, the combustion chamber 126 is formed along the outer peripheral wall 122. However, the combustion chamber 126 is not limited to this case, and the combustion chamber 126 includes the outer peripheral wall 122, the heating plate 118, and the arrangement plate 120. It suffices if it is within the enclosed space. However, in order to sufficiently secure the preheating effect of the fuel gas by the exhaust gas, the combustion chamber 126 is, for example, a space between the heating plate 118 and the partition plate 124 or a space between the partition plate 124 and the arrangement plate 120. Among them, it is desirable to be provided at any position in the space closer to the outer peripheral wall 122 than the intermediate position from the hole 158 provided in the arrangement plate 120 to the outer peripheral wall 122.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  The present invention can be used in a combustion heater that heats an object to be heated by burning fuel.

DESCRIPTION OF SYMBOLS 100 ... Combustion heater 118 ... Heating plate 120 ... Arrangement plate 122 ... Outer peripheral wall 124 ... Partition plate 126 ... Combustion chamber 128 ... Introducing path 128a ... Flow path 130 ... Outlet path 152 ... Protruding part 156 ... Gradually decreasing part

Claims (3)

A heating plate;
An arrangement plate disposed opposite to the heating plate;
An outer peripheral wall disposed along the outer periphery of the heating plate and the arrangement plate, and surrounding the space by the heating plate and the arrangement plate;
A partition plate disposed between the heating plate and the arrangement plate;
A combustion chamber arranged in a space surrounded by the heating plate, the arrangement plate, and the outer peripheral wall;
An introduction path that leads the fuel gas continuously to the combustion chamber using the arrangement plate and the partition plate as side walls;
Using the heating plate and the partition plate as side walls, the exhaust gas is led out of the combustion heater continuously from the combustion chamber to the combustion chamber, and the fuel gas is preheated by the heat of the exhaust gas through the partition plate. A lead-out path;
A protrusion that narrows the flow path of the fuel gas at a position where the introduction path and the combustion chamber are continuous;
The combustion heater according to claim 1, wherein the protrusion has a gradually decreasing portion whose thickness gradually decreases in the flow direction of the fuel gas from the introduction path to the combustion chamber.   The combustion heater according to claim 1, wherein the protrusion is provided only on the partition plate in the introduction path.   The combustion heater according to claim 1, wherein the protrusion is provided only on the arrangement plate in the introduction path.