JPH0235883B2 - - Google Patents

Description

[Detailed description of the invention]

``Object of the Invention'' (Industrial Application Field) The present invention relates to a heat exchange device that forms a main part of an oil water heater or the like. (Prior Art and Problems to be Solved) A conventional heat exchange device uses a gun type burner as its combustion means. The burner pressurizes liquid fuel (for example, kerosene) with an electromagnetic pump and sprays it into a combustion chamber, mixes the sprayed liquid fuel with air from a blower, ignites this mixture by high-pressure electric discharge, etc. It was meant to be burned.
In this case, the proportion of air in the mixture must be higher than the theoretical amount of air, but conventional burners require even more air supply because of the desire to give the flame a predetermined length and spread. There was a tendency to increase the amount. For this reason, conventional burners tend to produce a yellow flame state that is unsuitable as a combustion means for heat exchange devices, and the temperature of the combustion gas is further cooled by excess air, resulting in poor thermal efficiency. Further, the amount of carbon generated increases with cooling due to an increase in the amount of air supplied, and the carbon adheres to the inner surface of the combustion chamber, resulting in poor heat exchange efficiency. Furthermore, when the combustion chamber is filled with combustion gas containing unburned matter, the unburned matter in the combustion gas is intermittently re-ignited by the flame of the burner, and this state continues. was vibrating, making the combustion noise excessive.
Moreover, when the flame from the burner collides with the inner wall surface of the combustion chamber, a turbulent flow of combustion gas occurs at the collision portion, and the turbulent flow causes vibration noise throughout the apparatus. On the other hand, in today's era of energy and resource conservation, there is a strong demand for higher efficiency combustion means, and there is also a desire for lower noise from the perspective of preventing neighborhood pollution in urban areas. Therefore, a rotary gasification burner or a heater gasification burner has been developed that provides blue flame combustion and is suitable as a combustion means for a heat exchange device. However, the former has the disadvantage of generating a bad odor due to incomplete vaporization of the liquid fuel from ignition until the flame stabilizes and when extinguishing, while the latter requires time to preheat the heater, so it is necessary to wait before starting combustion. This was an inconvenience that required time. In particular, the above-mentioned heater gasification burner has a drawback in that the mechanism required to control the temperature of the heater is complicated. Both burners require basic improvements to vaporize liquid fuel, but the structure is expected to be extremely large and complex, and maintenance and inspection will require special skills. I was afraid. Moreover, both the rotary gasification burner and the heater gasification burner have not solved the problem of vibration noise caused by the turbulent flow of combustion gas. The present invention has been made in view of the above circumstances, and provides stable blue flame combustion without complicating the structure of the combustion means.
The purpose of this invention is to provide a novel heat exchange device (hereinafter referred to as the present device) that improves the heat exchange coefficient and the heat exchange rate, and also makes it possible to reduce combustion noise and prevent vibration noise. "Structure of the Invention" (Means for Solving the Problems) The gist of the present device is that the can body has a contact area for a fluid to be heat exchanged on the outer wall and a cylindrical combustion chamber is formed inside; A combustion air blow pipe having a tip opening facing toward the combustion chamber in the can body, a liquid fuel spray nozzle disposed inside the blow pipe, and a spray nozzle facing the nozzle end of the spray nozzle. an ignition electrode provided with an ignition electrode, a mixing tube connected to the tip opening of the blast tube and having at least an expanded diameter at the tip, and a mixing tube formed of a porous plate or a mesh plate and disposed in the spray nozzle inside the mixing tube. It is a heat exchange device consisting of a flame stabilizing plate fixed perpendicular to the spray direction, and a vertically elongated direct flame receiver is erected inside the combustion chamber with its back to the wall portion facing the spray nozzle. , Concave curved return surfaces for combustion gas that smoothly continue to the inner surfaces of the cylinders of the combustion chambers located on the left and right sides of the direct flame receiver are formed adjacent to each other on the front surface of the direct flame receiver, and the blower pipe and the mixing pipe are connected to each other. A vaporization heat inlet is formed between the connections for guiding the left and right return flow of combustion gas along the cylindrical inner surface of the combustion chamber into the mixing tube again. (Function) The liquid fuel particles sprayed from the spray nozzle into the combustion chamber are mixed with the combustion air from the blast pipe, and this mixture is ignited by the ignition electrode and combusts. The situation up to this point is almost the same as that of a conventional gun type burner, and therefore, if you observe the instantaneous flame, you will find that it is in a yellow flame combustion state. However, in the present apparatus, the yellow flame moves to the flame holding plate provided in front of the tip opening of the blast pipe due to its combustion dynamic pressure. In addition, the direct flame radiated through the flame stabilizing plate does not directly collide with the inner surface of the cylinder facing the spray nozzle in the combustion chamber, but rather with the direct flame emitted in front of the direct flame receiver installed directly in front of it. It becomes obstructed. In addition, since two mutually adjacent return surfaces are formed in front of the direct flame receiver, the combustion gas of the direct flame is
The air is naturally divided to the left and right sides in the radial direction, and flows smoothly and quickly to the left and right cylinders in the combustion chamber. Therefore, since no turbulent flow occurs at this point of flow division, vibration noise of the entire apparatus, which is caused by the turbulent flow, does not occur. Then, the divided left and right combustion gas flows return to the vaporization heat introduction port between the tip opening of the blast pipe and the mixing pipe connected in front of it. This return flow of combustion gas rapidly heats the liquid fuel particles sprayed into the mixing pipe just before they are combusted, so that the liquid fuel particles become even finer or vaporized. Mixed with combustion air. Naturally, the combustion air itself and the mixing tube are also heated by the return flow of the combustion gas, which helps complete combustion of the air-fuel mixture. Furthermore, by mixing as described above, the air-fuel ratio in the mixture of liquid fuel and combustion air is corrected so as to approximate the stoichiometric mixture ratio. Therefore, the yellow flame combustion changes to blue flame combustion, which becomes stable. Therefore, thermal efficiency and heat exchange rate are significantly improved, and combustion noise is also reduced. (Example) The present invention will be described below based on drawings showing examples thereof. FIG. 1 to FIG. 4 show an oil water heater A equipped with the present device. The oil water heater A has a can body 2 housed inside an exterior body 1, and a combustion chamber 3 is formed in the lower half of the can body 2. Moreover, the can body 2 is formed into a vertically elongated cylindrical shape including the combustion chamber 3, and the outer wall portion has a double structure consisting of an inner cylinder 2a and an outer cylinder 2b. Therefore,
A contact area 4 that stores water as a fluid to be heat exchanged is formed in an annular space between the inner cylinder 2a and the outer cylinder 2b. The main parts of this device are the internal structure of the combustion chamber 3,
There is a combustion means B provided in the combustion chamber 3. First, the combustion means B will be explained. As shown in FIG. 1, the combustion means B basically utilizes a gun-type burner that is substantially the same as the conventional one. That is, a hydraulic pump 7 for spraying kerosene as liquid fuel, a blower fan 9 for blowing up combustion air, and a blower pipe 10 for guiding the combustion air into the combustion chamber 3. Become.
As shown in a plan cross-sectional view in FIG. 3, a spray nozzle 8 is disposed inside the blast pipe 10 coaxially with the blast pipe 10 so as to face toward the center of the can body 2.
Further, an ignition electrode 14 is provided at the nozzle end of the spray nozzle 8 so as to face it. At the tip of the blast pipe 10, there is a complete combustion cylinder 15, which is not found in conventional gun-type burners.
is coaxially connected to the blower pipe 10. A high-speed fluidizing jet plate 11 is attached to the tip of the blast pipe 10. As shown in FIG. 4, the ejection plate 11 has a central hole 12 and a plurality of circumferential holes 13, 13, . It is set up. The central hole 12 is for ejecting kerosene particles, and some combustion air is also drawn into the kerosene particles. Further, the peripheral hole 13 is for blowing out most of the combustion air. Each of the peripheral holes 13 is bored at a predetermined angle in the circumferential direction, and is designed to cause a swirling flow in the ejected air and promote uniform mixing of kerosene particles and combustion air. . On the other hand, the complete combustion cylinder 15
consists of a mixing tube 20, a flame rectifying tube 19, a flame fixing tube 18, and a flame holding plate 17. The mixing tube 20 is formed so that its front half has an enlarged diameter, and the flame rectifying tube 1 is aligned along the internal shape of this enlarged diameter portion.
9 and a flame fixing tube 18 are adapted to be inserted. Further, the flame stabilizing plate 17 is located at the center of the complete combustion cylinder 15 and is fixed so as to be perpendicular to the direction in which the kerosene particles are sprayed in the spray nozzle 8 . The flame stabilizing plate 17 and the flame rectifier tube 19 are both made of stainless steel punched metal (porous plate material). The most important point in such a complete combustion cylinder 15 is that it maintains a predetermined distance between it and the blast pipe 10. That is, the interval is determined to form a vaporization heat inlet 16 (see FIG. 1 or FIG. 3) for introducing combustion gas between the mixing pipe 20 of the complete combustion cylinder 15 and the blower pipe 10. It is something. The function of the vaporization heat introduction port 16 will be described later. Next, the internal structure of the combustion chamber 3 will be explained.
As shown in FIG. 1, inside the combustion chamber 3, a direct flame receiver 6 is provided upright from a refractory 26 at the bottom thereof. The direct flame receptor 6 is located in the combustion chamber 3 so as to face a wall portion facing the spray nozzle 8 (see FIG. 3) of the combustion means B. Moreover, the cross-sectional shape of the direct flame receiver 6 is
As shown in the figure, it is like a deformed fan shape turned sideways, and two return surfaces 6a and 6b are formed on the front side facing the combustion means B. These return surfaces 6a, 6b are concave adjacent to each other so as to smoothly continue with the cylindrical surface of the combustion chamber 3 positioned on the left and right sides, with a portion that coincides with the extension of the central axis of the combustion means B as a tip 6c. It is formed into a curved surface. The height dimension of the direct flame receiver 6 is:
As shown in FIG. 1, it is formed vertically so that the installation height H from the refractory 26 to the central axis of the combustion means B is 2H. As a result, the combustion chamber 3
Direct collision of the flame from the combustion means B with the inner surface of the cylinder is also completely prevented. In the oil water heater A shown in Fig. 1, reference numeral 5 indicates a heat insulating material, 22 indicates an exhaust chimney, 23 indicates a hot water outlet, 24 indicates a water supply port, 25 indicates a drain section, and 27 indicates a combustion gas diffusion tube (internal structure). (not shown). The operating status of the device thus constructed is as follows. When combustion air is blown into the blast pipe 10, kerosene particles are sprayed from the spray nozzle 8, and park is blown off by the electrode 14, yellow flame combustion occurs near the front of the blow plate 11 in the blast pipe 10. Begins. This combustion flame gradually moves in the direction of spraying kerosene particles, and the flame rectifying tube 19 and the flame stabilizing plate 17
It comes to extend to The flame becomes stable on the flame stabilizing plate 17, and becomes a straight radiant flame that spreads to a certain extent from the flame fixing tube 18 toward the front thereof. The flame fixing tube 18 makes the flame distribution in the radiant flame uniform and further stabilizes it. The direct flame from the combustion means B reaches both return surfaces 6a and 6b of the direct flame receiver 6, and the combustion gas flows from both sides of the direct flame receiver 6 to the can body 2 with the tip 6c as a boundary. The flow is divided smoothly along the inner surface of each cylinder. The left and right flow of the combustion gas eventually reaches the vaporization heat introduction port 16 formed between the tip opening of the blast pipe 10 and the mixing pipe 20, and is sucked into the mixing pipe 20. Therefore, inside the mixing tube 20, the combustion gas is further mixed with the mixture of combustion air and kerosene particles. Therefore, the air-fuel mixture is rapidly heated, and in particular, the kerosene particles therein become finer or vaporized, and the yellow flame combustion described above changes to blue flame combustion. Further, the air-fuel ratio of the air-fuel mixture is appropriately adjusted to approximate the stoichiometric mixture ratio (approximately 14.8) by mixing the combustion gas, and the adjusted air-fuel mixture is supplied to the flame stabilizing plate 17. Moreover, since the amount of excess air contained in the air-fuel mixture is reduced in this way, cooling of the combustion gas is also suppressed, resulting in an excellent heat exchange coefficient.
Furthermore, since the amount of carbon generated is reduced, adhesion of carbon to the cylindrical inner surface of the combustion chamber 3 is also inhibited, and the heat exchange rate is also improved. Of course, since re-ignition of the combustion gas does not occur continuously, the combustion noise is quiet. In order to maintain the above-mentioned blue flame combustion, it is important to set an appropriate amount of the combustion gas return flow to the air-fuel mixture. That is, the magnitude of the suction action (negative pressure) at the vaporization heat inlet 16 formed between the connection between the blast pipe 10 and the mixing pipe 20 is an important factor. Therefore, the inventor of the present invention conducted experiments to find conditions under which an ideal suction effect could be obtained by variously changing the flow rate of the combustion air. The experiment was conducted by keeping the output of the blower fan 9 and the inner diameter of the blower pipe 10 constant, and by changing the hole diameters of the central hole 12 and peripheral hole 13 bored in the ejection plate 11 of the blower pipe 10. Although the size of the distance between the center hole 12 and the peripheral hole 13 can be almost ignored, the air-fuel ratio is necessary to enable ignition of the air-fuel mixture, and if it significantly deviates from the appropriate value, Not taken into account. <Table 1> and <Table 2> are the results of an experiment conducted by removing the subject device from inside the exterior body 1 of the oil water heater A.
The distance between the center hole 12 and the peripheral hole 13 in 1 is 32
mm. In addition, the experimental results shown in Table 1 are as follows:
It is assumed that the diameter of the central hole 12 is 18 mm and the number of peripheral holes 13 is 16, and the diameter of the peripheral holes 13 is varied. On the other hand, the experimental results shown in Table 2 show that the hole diameter of the peripheral hole 13 was determined to be 8 mm and the hole diameter of the central hole 12 was changed, and that the central hole 12 and all the peripheral holes 13, 13, ... The effect of the ratio of the opening area of the central hole 12 to the total opening area on the mixing amount of the combustion gas return flow (indicated as "gas mixing amount" in each table) is examined.

【table】

【table】

[Table] As is clear from Table 1, if the diameter of the peripheral hole 13 is made smaller, the flow velocity of the ejected air becomes faster.
It can be seen that the suction effect generated at the vaporization heat introduction port 16 becomes stronger. However, on the other hand, it has been found that the mixed amount of the combustion gas return flow sucked into the mixing tube 20 (hereinafter referred to as the gas mixed amount) tends to decrease.
Therefore, the suction action is within the required range,
In addition, the optimum gas mixing amount was determined when the diameter of the peripheral hole 13 was 8 mm.
Also, as is clear from Table 2, the center hole 1
The same is true for No. 2, and if the hole diameter is made smaller, the flow velocity of the ejected air becomes faster, but on the contrary, the mixed amount of gas sucked into the mixing tube 20 tends to decrease. Furthermore, it has been found that the increase or decrease in the gas mixture amount is proportional to the increase or decrease in the opening area ratio.
Therefore, in consideration of the balance between the flow velocity of the ejected air and the amount of gas mixture, the diameter of the central hole 12 was set to an optimum value of 18 to 20 mm. In this way, the diameter of the central hole 12 is 18 mm, and the diameter of the peripheral hole 1 is 18 mm.
3, the diameter of the hole 13 is 8 mm, the number of peripheral holes 13 is 16, and the inner diameter of the blast pipe 10 is 80 mm. When this device is installed inside the exterior body 1 of the oil water heater A, the ejected air flow velocity was measured to be 21 m. /second, and a sufficient suction effect was obtained even at the vaporization heat introduction port 16. Similar measurements were made with conventional commercially available combustion methods, but the velocity of the ejected air was only around 12.5 m/sec at most. Of course, in conventional combustion means, there is almost no effect of re-inhaling the combustion gas once ejected. (Study of Alternative Aspects) FIG. 5 is a plan sectional view showing a second embodiment of the present device. In this embodiment, in addition to the structure of the embodiment shown in FIGS. 1 to 4, two partition bodies 28, 28 each having a semicircular cross section are vertically provided in the combustion chamber 3. be. And the partition body 28,2
Combustion gas return flow passages 29, 29 are formed between the arcuate surface of 8 and the cylindrical inner surface of the can body 2. Therefore, the direct flame and combustion gas radiated from the combustion means B and the left and right return flows of the combustion gas never interfere with each other, and the return flow of the combustion gas to the vaporization heat introduction port 16 in the combustion means B never occurs. The flow has become more efficient. FIG. 6 is a plan sectional view showing a third embodiment of the present device. In this embodiment, the can body 2 and the combustion chamber 3
This makes it possible to form a rectangular prism shape. Inside the combustion chamber 3, combustion gas guides 30 are erected at all four corners along with the direct flame receiver 6. Therefore, in this embodiment, the can body 2 and the combustion chamber 3 can be manufactured extremely easily, and the manufacturing cost can be reduced. Of course, effects such as improvement in thermal efficiency and heat exchange rate, prevention of vibration noise, and reduction in combustion noise can be obtained almost the same as in the embodiments shown in FIGS. 1 to 4. In this way, the shape and configuration of the present device can be changed as appropriate depending on the mode of implementation. ``Effects of the Invention'' As is clear from the above explanation, the heat exchange device according to the present invention is different from the conventional common combustion means by using a mixing tube, a flame stabilizing plate, etc. through the vaporization heat inlet. By providing a simple configuration in which a direct flame receiver is installed in the combustion chamber, stable blue flame combustion can be obtained.
In other words, the cylindrical surface of the combustion chamber is used to flow the combustion gas smoothly and quickly back to the tip opening of the blast pipe, and the return flow of the combustion gas is used to vaporize the liquid fuel and improve the air-fuel ratio of the mixture. It is used for adjustment. Therefore, the thermal efficiency and heat exchange rate are significantly improved. Further, since turbulent flow of combustion gas does not occur within the combustion chamber, vibration noise of the entire apparatus that would otherwise be caused by the occurrence of the turbulent flow is prevented. Furthermore, when the combustion means uses blue flame combustion, the combustion gas does not continue to be re-ignited, so the direct flame does not vibrate.
The combustion noise is also quieter. Moreover, since the direct flame is prevented from colliding orthogonally with the cylinder inner surface of the combustion chamber by the direct flame receiver, no impact noise is generated by the flame. This also prevents the cylindrical inner surface of the combustion chamber from being locally heated, thereby providing the advantage of improving the durability of the combustion chamber and the can body. Further, as mentioned above, the present device can be implemented extremely easily by adding a few components to the conventional combustion means, and there is no need to go to the trouble of remanufacturing the combustion chamber or the can body. Furthermore, it has many excellent advantages, such as being easy to maintain, like conventional combustion means.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present device, in which FIG. 1 is a side sectional view, FIG. 2 is a plan sectional view, and FIG. 3 is a plan sectional view of the combustion means. 4
The figure is a partially cutaway perspective view of the combustion means, FIG. 5 is a plan sectional view showing a second embodiment of the present device, and FIG. 6 is a plan sectional view showing a third embodiment of the present device. 2... Can body, 3... Combustion chamber, 4... Contact area, 6... Direct flame receiver, 6a, 6b... Return surface, 8... Spray nozzle, 10... Blower pipe, 14... Electrode, 16... Vaporization heat introduction port, 17...Flame holding plate, 20...Mixing tube.

Claims (1)

[Claims] 1. A can body with a contact area for a heat exchange fluid on the outer wall and a cylindrical combustion chamber formed inside, and a combustion air blow pipe in which a tip opening is positioned toward the combustion chamber. a spray nozzle for liquid fuel disposed inside the blast pipe; an ignition electrode provided facing the nozzle end of the spray nozzle; and at least a tip portion connected to the tip opening of the blast pipe. A heat exchange device comprising a mixing tube with an enlarged diameter and a flame-holding plate formed of a porous plate or a mesh plate and fixed inside the mixing tube perpendicular to the spray direction of the spray nozzle, Inside the combustion chamber, a vertically elongated direct flame receiver is installed with its back facing the wall portion facing the spray nozzle, and in front of the direct flame receiver, there is a direct flame receiver located on the left and right sides of each of the cylindrical inner surfaces of the combustion chamber. Smoothly continuous concave curved return surfaces for combustion gas are formed adjacent to each other, and between the connection between the blast pipe and the mixing pipe, the left and right return flow of combustion gas along the cylinder inner surface of the combustion chamber is mixed again. A heat exchange device characterized by being formed with a vaporization heat introduction port that leads into the pipe.