Hearth with two stage combustion

Abstract

To provide a hearth for forming a large and bright flame without increasing the amount of wood of fuel.SOLUTION: In a combustion chamber characterized in that an opening area of a combustion chamber upper plate is smaller than a bottom area of the combustion chamber and a height dimension is short, a two stage combustion system that performs first stage combustion in which wood as fuel is incompletely combusted by primary air at a flow rate smaller than a theoretical air amount and second stage combustion in which an unburned combustible component remaining due to the incomplete combustion is combusted by secondary air above the combustion chamber upper plate is adopted, and an air preheating system that preheats the primary air supplied to the combustion chamber by heating from a flame in the combustion chamber is adopted.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to wood-burning hearths. [Background technology]

[0002] Prior art hearths have been used since ancient times as lighting, cooking and heating devices, but to date, no significant structural improvements have been made to increase the amount of light. Summary of the Invention [Problem to be solved by the invention]

[0003] The problem to be solved by the present invention is to provide a hearth that allows for the creation of a large, bright flame without increasing the amount of wood burned. [Means for solving the problem]

[0004] The problem of providing a hearth that allows for the formation of a large, bright flame without increasing the amount of wood burned is solved by employing a two-stage combustion system as a means for forming a large flame and an air preheating system as a means for forming a bright flame.

[0005] A two-stage combustion system is a combustion method that completely burns wood by first-stage combustion using a smaller amount of air (primary air) than the theoretical amount supplied in the combustion chamber, and then second-stage combustion, in which the unburned combustible material generated in the first-stage combustion is burned with surrounding air (secondary air) outside the combustion chamber. This two-stage combustion system makes it possible to form a large flame that extends from inside the combustion chamber to outside the combustion chamber.

[0006] An air preheating system is a combustion method that preheats the air used for combustion, thereby increasing the combustion temperature of wood and promoting combustion. This air preheating system makes it possible to form a bright flame. [Effects of the Invention]

[0007] The present invention has the advantage of providing a hearth that produces a large, bright flame without increasing the amount of wood burned.

[0008] If it becomes possible to provide an irori that produces a large, bright flame without increasing the amount of wood burned, it will have the economic effect of reducing wood consumption, the effect of reducing the risk of fires, and the effect of allowing the irori to be made smaller. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a hearth employing a two-stage combustion system according to a first embodiment of the invention of this application. [Figure 2] FIG. 1 is a schematic diagram of a hearth employing a two-stage combustion system and an air preheating system according to a second embodiment of the invention of this application. DETAILED DESCRIPTION OF THE INVENTION

[0010] The hearth employing the two-stage combustion system of the first embodiment of the present application shown in Figure 1 is composed of a combustion chamber upper plate 11, multiple combustion chamber side plates 13, a combustion chamber bottom plate 15, and other components. The space surrounded by the combustion chamber upper plate 11, the combustion chamber side plates 13, and the combustion chamber bottom plate 15 forms the combustion chamber 10.

[0011] The two-stage combustion system completely burns wood 1 put into the hearth by first-stage combustion of incomplete combustion carried out inside the combustion chamber 10 and second-stage combustion of unburned combustible components produced by the incomplete combustion carried out outside the combustion chamber 10.

[0012] The combustion chamber top plate 11 has an opening 12, the area of ​​which is approximately 70 percent or less of the bottom area of ​​the combustion chamber 10. The purpose of making the area of ​​this opening 12 smaller than the bottom area of ​​the combustion chamber 10 is to prevent air above the combustion chamber top plate 11 from flowing into the combustion chamber 10. The combustion chamber side plate 13 has an opening 14, through which the air for the first stage of combustion (= primary air 3) flows into the combustion chamber 10. The width and depth dimensions of the combustion chamber 10 are set to be equal to or greater than the length of the wood 1 used as fuel. The difference in height between the opening 12 on the combustion chamber top plate 11 and the opening 14 on the combustion chamber side plate 13 is set to 10 to 20 centimeters, in order to limit the flow velocity of the primary air 3 flowing in from the opening 12 to approximately 1 meter per second due to the chimney effect.

[0013] In the combustion chamber 10 where the first stage of combustion takes place, the wood 1 introduced into the combustion chamber 10 reacts with the primary air 3 flowing in through the opening 14 at a flow rate less than the theoretical air volume, causing incomplete combustion and forming a flame 5. The unburned combustible components and combustion gases produced by the incomplete combustion pass through the opening 12 in the combustion chamber top plate 11 and exit the combustion chamber 10. The unburned combustible components react with the air above the combustion chamber top plate 11 (= secondary air 5), causing the second stage of combustion and completely burning the wood 1. The flow rate of the primary air 3 can be adjusted as necessary by reducing the area of ​​the opening 14 in the combustion chamber side plate 13.

[0014] At this time, if the flow rate of the primary air 3 is reduced, the proportion of combustible components outside the combustion chamber 10 that are burned in the second stage of combustion increases, causing the flame 5 to extend significantly outside the combustion chamber 10. However, an extreme reduction in the flow rate of the primary air 3 is not performed because it would make it impossible to continue combustion.

[0015] In the hearth employing the two-stage combustion system according to the first embodiment of the present invention, it is possible to form a flame 5 that extends widely outside the combustion chamber 10.

[0016] The hearth employing the two-stage combustion system and air preheating system of the second embodiment of the present application shown in Figure 2 has an equipment configuration in which the combustion chamber 10 shown in Figure 1 is housed in a casing 20 composed of a plurality of casing side plates 23, a casing bottom plate 25, and other components. The casing bottom plate 25 has an opening 26 for taking in primary air 4. An air flow path change plate 27 is installed between the combustion chamber side plate 13 and the casing side plate 23.

[0017] The combustion of wood 2 is similar to the combustion in an hearth in the embodiment of the present invention shown in Figure 1, with the first stage of combustion occurring inside the combustion chamber 10 and the second stage of combustion occurring outside the combustion chamber 10. Primary air 4 supplied to the combustion chamber 10 is taken in through opening 26 in the casing bottom plate 25, passes between the combustion chamber bottom plate 15 and the casing bottom plate 25, passes between the casing side plate 23 and the air flow path changing plate 27, passes between the air flow path changing plate 27 and the combustion chamber side plate 13, and then flows into the combustion chamber 10 through opening 14.

[0018] The air preheating system is a combustion system in which the temperature of primary air 4 taken in through opening 26 of casing 20 is increased by being heated by the combustion flame 8 of wood 2 while flowing into combustion chamber 10 through opening 14 of combustion chamber side panel 13. By adopting the air preheating system, the temperature at opening 14 is increased by 200 to 300°C compared to the temperature at opening 26.

[0019] Thermodynamically, the amount of energy radiated from a high-temperature object is proportional to the fourth power of the absolute temperature, according to the Stefan-Boltzmann law. According to this relationship, if the temperature of flame 6 before the air preheating system was 1000°C (1273K), when the air preheating system is adopted, the temperature of flame 8 will rise from 1200°C (1473K) to 1300°C (1573K), and the amount of energy radiated from flame 8 will increase from approximately two to three times its temperature before the system is adopted.

[0020] Flame 8 formed within combustion chamber 10 passes from inside combustion chamber 10 through opening 12 in combustion chamber top plate 11 to the outside of combustion chamber 10, where combustion continues with secondary air 6, which is air above combustion chamber top plate 11. The temperature of flame 8 from combustion with secondary air 6 outside combustion chamber 10 is also affected by the high combustion temperature within combustion chamber 10, and becomes higher than before the air preheating system was adopted, and the amount of radiant energy from flame 8 becomes greater than before the air preheating system was adopted.

[0021] In a hearth employing a two-stage combustion system and an air preheating system according to the second embodiment of the present invention, the effect of forming a large flame due to the use of the two-stage combustion system and the effect of increasing the amount of light due to the use of the air preheating system are obtained, making it possible to form a large, bright flame without increasing the amount of wood being burned.

[0022] The above is an explanation of the hearth of the present invention that burns wood, but it can also be used in hearths that burn materials other than wood.

[0023] This invention can also be used in hearths that burn kerosene instead of wood. [Explanation of symbols]

[0024] 1:Wood 2:Wood 3: Primary air 4: Primary air 5: Secondary air 6: Secondary air 7: Flame 8: Flame 10: Combustion chamber 11: Combustion chamber upper plate 12:Aperture 13: Combustion chamber side plate 14:Aperture 15: Combustion chamber bottom plate 20: Casing 23: Casing side plate 25: Casing bottom plate 26:Aperture 27: Air flow change plate

Claims

1. A two-stage combustion hearth, characterized in that in a combustion chamber consisting of a combustion chamber upper plate having an opening, a combustion chamber side plate having an opening, a combustion chamber bottom plate, and other components, the area of ​​the opening in the combustion chamber upper plate is 70 percent or less of the bottom area of ​​the combustion chamber.

2. 2. The two-stage combustion hearth according to claim 1, wherein the combustion chamber is housed within a plurality of casing side plates and a casing bottom plate.

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