JPH028203B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a heat exchange device comprising a combustion device that gasifies and burns a mixture of air and fuel by circulating combustion gas to a mixing pipe provided in front of a spray nozzle. It is related to. [Prior Art] Conventionally, combustion devices such as oil water heaters include what is called a gun-type burner. In this system, a mixture of fresh air sent out from a blower and atomized fuel pressurized by an electromagnetic pump or the like and sprayed from a spray nozzle is ignited and combusted using a high-pressure electric discharge or the like. However, the conventional combustion device known as a gun-type burner has a drawback that yellow flame combustion occurs due to the large amount of air in the air-fuel mixture, resulting in poor combustion efficiency. Another drawback is that carbon particles generated by yellow flame combustion adhere to the heat transfer surface inside the casing, reducing heat exchange efficiency, and furthermore, the vibration of the flame increases combustion noise. . Recently, there has been a demand for high combustion efficiency, low noise, and clean exhaust gas from the viewpoint of energy conservation and the environment, and so-called rotary gasification burners or heater gasification systems that gasify fuel oil and combust it with blue flame have become popular. A burner has been developed. However, the former method had the disadvantage that the gasification of the fuel oil was insufficient at the time of ignition and extinguishment, resulting in odor. Also, the latter requires a long time to preheat the heater, so
It is inconvenient to use, and has the disadvantage of requiring complicated controls such as controlling the heater. Furthermore, both had the disadvantage that their fuel oil gasification structures were complicated and required special skills for maintenance and inspection. Therefore, in order to solve the above-mentioned drawbacks, the present applicant has proposed the
An application has been filed for an unknown heat exchange device 29 shown in the figure. In this heat exchange device 29, a cylindrical combustion chamber 33 is formed inside a housing 32, and a blower pipe 35 is installed facing the combustion chamber 33. A spray nozzle 34 is installed inside the blast pipe 35 . Further, within the combustion chamber 33 and in front of the spray nozzle 34, a mixing pipe 30 having a flame stabilizing plate 31 therein is installed. Further, a combustion gas inlet 36 is formed between the mixing pipe 30 and the blower pipe 35. The combustion flame extension center line G of the mixing tube 30 and the axial length center line H of the combustion chamber 33 are arranged to be perpendicular to each other. [Problems to be Solved by the Invention] By the way, when it is necessary to reduce the inner diameter of the cylindrical combustion chamber 33 due to restrictions on the installation location of the heat exchange device 29, it is necessary to pay attention to the following points. It is. That is, from the mixing tube 30, which is the starting end of the combustion flame, to the inner peripheral wall surface 32 facing the mixing tube 30.
The distance to a' must be a predetermined distance that does not cause local heating on the inner circumferential wall surface 32a'. However, in the heat exchanger 29, since the combustion flame extension center line G of the mixing tube and the axial length center line H of the combustion chamber 33 are perpendicular to each other, the mixing tube 30
Since the distance to the inner circumferential wall surface 32a' facing 0 is the shortest distance, there are restrictions on reducing the diameter of the cylindrical combustion chamber 33, and there are cases where such requirements cannot be met. Further, since the combustion gas rises through the entire cylindrical combustion chamber 33, the combustion gas is discharged too smoothly. Moreover, the combustion gas that comes into contact with the inner circumferential wall surface 32a of the housing 32 is only in a very small part of the outer circumferential side of the combustion chamber 33, excluding the central part, and wasteful combustion gas is discharged without undergoing heat exchange. There will be more. Therefore, due to the uneconomical flow of combustion gases,
The drawback was that the heat exchange efficiency was extremely poor. [Means for Solving the Problems] In view of the above-mentioned conventional problems, the present invention further improves the technology related to the above-mentioned unknown combustion device previously filed by the present applicant, and achieves high combustion efficiency, low noise, and cleanliness. It is an object of the present invention to provide a heat exchange device capable of reducing the inner diameter of a cylindrical combustion chamber without causing local heating while maintaining exhaust gas. Therefore, the means adopted by the present invention to solve the above problem includes a combustion air blower tube having an open end facing the combustion chamber, and a combustion air blower tube arranged to cover the tip opening of the blower tube. , a high-speed air jetting plate having a central jetting hole and a circumferential air jetting hole, a spray nozzle and an ignition electrode disposed inside the blast pipe;
a tapered cone-shaped mixing tube located forward in the spraying direction from the tip opening of the blast tube and connected to the blast tube so that its axis coincides with the blast tube; and a tapered cone-shaped mixing tube located at the center of the mixing tube and connected to the spray nozzle. and a porous or mesh-like flame stabilizing plate provided facing directly in the spraying direction, and a connecting portion between the blast pipe and the mixing pipe is provided with a combustion gas circulating along the wall of the cylindrical combustion chamber. In a heat exchange device having a combustion device provided with an annular inlet large enough to flow into the rear end opening of a mixing tube, a cylindrical combustion tube with an open bottom end is suspended inside a cylindrical case. forming a combustion exhaust gas path between the cylindrical case and the combustion tube, and forming a cylindrical combustion chamber with an open lower end in the combustion tube,
The combustion device is hung down from the top of the cylindrical case and faces into the combustion chamber, and the mixing pipe of the combustion device is installed in such a manner that the extension center line of the combustion flame ejected through the mixing pipe is in the combustion chamber. It is oriented in the axial direction. [Function] In the heat exchange device of the present invention, the combustion gas, which has once directed downward, passes through the opening on the lower end side of the cylindrical combustion chamber.
The exhaust gas ascends through the annular exhaust gas path between the combustion tube and the cylindrical housing and is discharged. Therefore, the entire combustion gas comes into contact with the inner wall surface of the cylindrical case and undergoes heat exchange, resulting in extremely high efficiency. In addition, since the combustion gas flows downward through the combustion chamber and bypasses the combustion tube, the residence time of the combustion gas in the combustion chamber and heat transfer surface area (combustion exhaust gas path) becomes longer, further improving the heat exchange efficiency. Become. Furthermore, in the heat exchange device of the present invention, since the extension center line of the combustion flame ejected from the mixing tube is oriented in the axial direction of the cylindrical combustion chamber,
Combustion flames do not cause localized heating. Therefore, the patent application filed earlier by the applicant in 1983
It is possible to make the inner diameter of the housing smaller than in the case of the heat exchange device according to No. 83799. Furthermore, in the combustion apparatus of the present invention, the circulating combustion gas sucked into the mixing tube warms the mixed mist of extremely fine kerosene particles and fresh air by the swirling air flow, and instantly transforms the kerosene particles into gas. to a state at or close to this. Therefore, the combustion state becomes gasification combustion or a state close to this, and blue flame combustion from the flame stabilizing plate is obtained. In other words, kerosene particles, fresh air, and circulating combustion gas are mixed in a mixing tube and then rectified, and what used to be combustion with excess air becomes an ideal combustion that is close to the stoichiometric air ratio and is rectified. Therefore, combustion with low combustion noise and excellent heat exchange efficiency can be obtained. [Example] Below, the configuration of the present invention will be described based on an example shown in the drawings. 2 and 3 show a heat exchange device 1 according to a first embodiment of the present invention. In this heat exchange device 1, a combustion tube 4 is arranged inside a cylindrical case 2, and an annular combustion exhaust gas path 23 is formed between an inner circumferential wall 2a of the case 2 and the combustion tube 4. The combustion tube 4 has a lower end opening 4a formed therein, and
It is connected and fixed to a lower end flange portion 6b of a hanging cylinder portion 6a of a top plate 6 attached near the upper end of the housing 2. The housing 2 has a double pipe structure in which a water chamber 2c is formed between an annular inner peripheral wall 2a having an appropriate cross-sectional shape such as a circular cross-section or a polygonal cross-section, and an outer peripheral wall 2b. The outer periphery of the housing 2 is covered with a heat insulating material 5. Note that the housing 2 is not limited to the double pipe structure, and although not shown in the drawings, it is of course possible to have a structure formed by winding a long small diameter pipe in a spiral shape. Near the upper end of the combustion chamber 3 formed inside the combustion tube 4, the tip of the blow pipe 10 inserted into the downwardly downward tube portion 6a of the top plate 6 is connected to the upper end opening 4b of the combustion chamber 3. The combustion chamber 3 is positioned so as to be directed into the combustion chamber 3 through the combustion chamber 3. The flange 10a of the air pipe 10 is connected and fixed to the top plate 6. A spray nozzle 8 is installed inside the blast pipe 10 . A mixing pipe 20 having a built-in flame stabilizing plate 17 is installed in the combustion chamber 3 and in front of the blast pipe 10 . The mixing pipe 20 is the same as the blower pipe 10.
A predetermined gap W (for example, 15 mm) is formed between the mixing tube 20 and the tip of the mixing tube 20, and the extension center line B of the combustion flame ejected through the mixing tube 20 is oriented in the axial direction of the combustion chamber 3. being done. In the illustrated embodiment, the combustion flame extension center line B
Although the mixing tube 20 is installed so that the axial center line A of the combustion chamber 3 and the axial center line A of the combustion chamber 3 are concentric, the present invention is not limited thereto. For example, although not shown,
The combustion flame extension center line B may be inclined with respect to the axial length center line A by an appropriate inclination angle (for example, 30 degrees), and the combustion flame extension center line B may be appropriately eccentric with respect to the axial length center line A. Of course, it is also possible to eccentrically shift it toward the outside of the combustion chamber 3 by a dimension (for example, 1/3 to 1/2 of the half diameter of the combustion chamber 3). Due to the gap W, a circulating gas inlet (hereinafter referred to as a circulating inlet) 16 is formed between the mixing pipe 20 and the blower pipe 10 near the top plate portion 4c of the combustion tube 4. Flame stabilizing section 1 having a multi-tube structure having the mixing tube 20
As shown in FIG. 3, 5 has a flame-holding plate 17 made of punched stainless steel metal or the like near its center.
is installed. A tapered cone-shaped flame stabilizing tube 18 that expands in the downstream direction is installed on the outer periphery of the flame stabilizing plate 17. On the outer periphery of this flame-holding tube 18, a sub-flame-holding tube 19 made of stainless steel punched metal or the like is installed. Further, a mixing pipe 20 is installed around the outer periphery of the sub-flame stabilizing cylinder 19.
These flame-holding plates 17, flame-holding tubes 18, and sub-flame-holding tubes 19
and the mixing tube 20 are connected by support legs 21, 21..., and the mixing tube 20 is suspended on the blower tube 10 by legs 22, 22.... Note that the flame-holding tube 18 and the sub-flame-holding tube 19 are installed as necessary, and are not necessarily required. A spray nozzle 8 is installed behind the flame holding section 15 so as to be substantially coaxial with the combustion flame extension center line B, and sprays fuel oil pressurized by a hydraulic pump 7 (see FIG. 5 described later). It is configured to eject the particles into atomized fine particles. On the outer periphery of the spray nozzle 8,
A blower pipe 10 is installed for blowing fresh air generated by a blower 9 (see FIG. 2) to the mixing pipe 20. The opening at the tip of the air pipe 10 includes:
A high-speed air jet plate 11 is installed as required. This jetting plate 11 has a central jetting hole 12 that jets atomized fuel and fresh air, and a plurality of air jetting holes 13 that are formed at appropriate circumferential pitches at a predetermined distance from the center. There is. This air outlet 1
3, each of which is inclined at a predetermined angle in the circumferential direction, causes a swirling flow in the ejected air to further refine the fuel particles, and evenly distributes the mixture of the atomized fuel and fresh air. . 14 is
This is an electrode rod that generates a spark using high-voltage electricity near the tip of the spray nozzle 8 and ignites the fine particles of fuel oil that are ejected. In FIG. 2, 24 is an exhaust chimney, 25 is a combustion tube, and 27 is a hot water supply port. Next, the operation of the heat exchange device 1 configured as above will be explained based on the case where the fluid to be heat exchanged is water, the fuel oil is kerosene, and the amount of supplied kerosene and the amount of fresh air supplied are constant. do. The atomized kerosene particles ejected from the spray nozzle 8 are ignited by the spark of the electrode rod 16, and at first, yellow flame combustion begins near the tip of the ejection plate 11. In this condition there is an excess of air. After that, this combustion flame gradually moves in the spray direction, propagates to the sub flame stabilizing tube 19, and further moves to the flame stabilizing plate 17,
The flame is rectified on the way to the flame stabilizing plate 17, stabilized by the flame stabilizing plate 17, and guided to the flame stabilizing tube 18 to maintain steady combustion. In this way, the auxiliary flame stabilizing cylinder 19 functions to smooth the propagation of the combustion flame when it moves to the flame stabilizing plate 17. In addition, the ejection plate 1
1. When the flame-holding tube 18 and the sub-flame-holding tube 19 are not installed, stable combustion is started and maintained on the flame-holding plate 17 by spark ignition near the flame-holding plate 17. As shown in FIG. 2, part of the combustion gas (not shown) ejected from the mixing pipe 20 downward in the axial direction of the combustion chamber 3 flows into the combustion chamber 3 due to its own buoyancy.
It rises inside and reaches the circulation inlet 16. Then, the combustion gas passes through the gap W from the blower pipe 10 to the mixing pipe 2.
Due to the negative pressure generated by the swirling air flow passing through the air at high speed, air is forcibly drawn into the mixing tube 20 from around the circulation inlet 16 in a substantially uniform state, and becomes a mixture of kerosene particles and fresh air. Mix instantly. On the other hand, the remaining combustion gas ejected from the mixing pipe 20 travels downward in the axial direction of the combustion chamber 3 and flows into the combustion exhaust gas path 23 from the lower end opening 4a of the combustion tube 4. While passing through the combustion exhaust gas path 23, the combustion exhaust gas comes into contact with the entire circumference of the inner circumferential wall 2a of the housing 2, and after sufficiently exchanging heat with the water in the water chamber 2c, is discharged to the outside via the exhaust chimney 24. be done. In this way, in this embodiment, the mixing tube 20
Since the extension center line of the combustion flame ejected from the cylindrical combustion chamber 3 is oriented in the axial direction of the cylindrical combustion chamber 3, the combustion flame does not cause local heating. Therefore, compared to the case of the heat exchange device related to Japanese Patent Application No. 57-83799, which was filed earlier by the present applicant,
It is possible to reduce the inner diameter of the housing 2. Further, the combustion gas is discharged from the lower end side opening of the cylindrical combustion chamber, rising through the annular exhaust gas path between the combustion tube and the cylindrical casing. Therefore, the entire combustion gas comes into contact with the inner wall surface of the cylindrical case and undergoes heat exchange, resulting in extremely high efficiency. In addition, since the combustion gas flows downward through the combustion chamber and bypasses the combustion tube, the residence time of the combustion gas in the combustion chamber and heat transfer surface area (combustion exhaust gas path) becomes longer, further improving the heat exchange efficiency. Become. By the way, the circulating combustion gas sucked into the mixing tube 20 warms the mixture of extremely fine kerosene particles and fresh air by the swirling air flow, and instantly gasifies or converts the kerosene particles into gas. make it close. Therefore, the combustion state becomes gasification combustion or a state close to this, and blue flame combustion from the flame stabilizing plate 17 is obtained. In other words, kerosene particles, fresh air, and circulating combustion gas are mixed in the mixing tube 20 and then rectified, and what used to be combustion with excess air becomes an ideal combustion that is close to the stoichiometric air ratio and is rectified. Become. Therefore, combustion with low combustion noise and excellent heat exchange efficiency can be obtained. From then on, this blue flame combustion is maintained. In order to obtain the above-mentioned blue flame combustion, it is necessary to mix an appropriate amount of combustion gas into the mixture of fresh air and kerosene particles. ) is the problem. Therefore, in this example, we conducted an experiment by changing the flow rate of the ejected air, which has the greatest effect on the negative pressure, and as a result, we were able to set a flow rate that was sufficient to suck in the amount of combustion gas required for the ideal air ratio. . The factors that affect the flow velocity of the ejected air are the diameters of the central ejection hole 12 and the air ejection hole 13 and the diameters of both the air ejection holes 12 and The area ratio is 13. In addition,
The number of air jets 13 and the distance between the central jet hole 12 and the air jet hole 13 have little effect on the flow velocity of the jet air and can be ignored. however,
If the distance between the two nozzles 12 and 13 exceeds an optimum value, good mixing of kerosene particles and air will not be achieved. In the case of this embodiment in which the diameter of the blast pipe 10 was 80 mm (combustion output was 35000 Kcal/Hr), the appropriate distance between the central nozzle 12 and the air nozzle 13 was 32 mm. Tables 1 and 2 are experimental results showing the relationship between the diameter of the ejection holes 12 and 13 and the air flow velocity and amount of air supplied when ejected from the ejection holes 12 and 13 into the natural atmosphere.

[Table] As is clear from Table 1, if the diameter of the air jet holes 13 is made smaller, the flow velocity of the jet air becomes faster and the negative pressure generated at the circulation inlet 16 becomes larger. However, the amount of supplied air tends to decrease as the diameter of the air jet hole 13 becomes smaller. For this reason,
A hole diameter of 8 mm is required to ensure a sufficient amount of supplied air and a high flow rate.

〔Effect of the invention〕

As explained above, the heat exchange device according to the present invention has the following excellent effects. Combustion gas is discharged from the lower end side opening of the cylindrical combustion chamber, rising through an annular exhaust gas path between the combustion tube and the cylindrical casing. Therefore, the entire combustion gas comes into contact with the inner wall surface of the cylindrical case and undergoes heat exchange, resulting in extremely high efficiency. In addition, since the combustion gas flows downward through the combustion chamber and bypasses the combustion tube, the residence time of the combustion gas in the combustion chamber and heat transfer surface area (combustion exhaust gas path) becomes longer, further improving the heat exchange efficiency. Become. Since the extension center line of the combustion flame ejected from the mixing tube is oriented in the axial direction of the cylindrical combustion chamber, local heating of the inner circumferential wall of the casing is eliminated, which is different from conventional Compared to a heat exchange device in which the combustion flame extension center line of the mixing tube and the axial length center line of the combustion chamber are perpendicular to each other, the inner diameter of the casing can be made smaller, making it possible to meet the demand for smaller diameters. By circulating the combustion gas through the mixing pipe and warming the combustion particles, they are brought to a state close to gasification, and at the same time, the combustion gas is added to the mixture of fresh air and fuel particles to create an air ratio close to the stoichiometric air ratio. By burning it, blue flame combustion can be achieved, a large amount of heat is generated for a given amount of fuel, and the device has excellent thermal efficiency. It has the advantage of low combustion noise due to the combustion flame being a steady blue flame and the rectification effect of the mixing tube.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a conventional heat exchange device, FIGS. 2 and 3 are according to the first embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional view of the heat exchange device, and FIG. 4 is a partially cutaway perspective view showing the mixing pipe, blower pipe, etc.
The figure is a longitudinal cross-sectional view of a heat exchange device showing a second embodiment of the present invention. 2... Housing, 3... Combustion chamber, 4c... Partition wall, 8... Spray nozzle, 10... Air pipe, 16... Circulation inlet, 1
7... Flame holding plate, 20... Mixing tube, 23... Combustion exhaust gas path, A... Axial length center line, B... Combustion flame extension center line.

Claims (1)

[Claims] 1. A combustion air blast pipe with an open end facing the combustion chamber, and a high-speed air jet plate arranged to cover the opening at the end of the blast pipe and having a central jet hole and a circumferential air jet hole. and a spray nozzle and an ignition electrode disposed inside the blast pipe, which are located forward in the spraying direction from the tip opening of the blast pipe and are connected and arranged so that their axes coincide with the blast pipe. A tapered cone-shaped mixing pipe, and a porous or mesh-like flame holding plate provided in the center of the mixing pipe and facing directly in the spraying direction of the spray nozzle, and the blower pipe and the mixing pipe are connected to each other. In a heat exchanger having a combustion device, the connecting portion is provided with an annular inlet having a size that allows combustion gas circulating along the wall of the cylindrical combustion chamber to flow into the rear end opening of the mixing tube. A cylindrical combustion tube with an open bottom end is suspended inside the cylindrical case to form a combustion exhaust gas path between the cylindrical case and the combustion tube. A combustion chamber is formed, the combustion device is made to hang down from the upper part of the cylindrical case and faces into the combustion chamber, and the installation position of the mixing pipe of the combustion device is set such that the combustion flame ejected through the mixing pipe is extended. A heat exchange device characterized in that a center line is oriented in the axial direction of the combustion chamber.