JPS59147914A - Heat exchanger - Google Patents

Abstract

PURPOSE:To increase the heat exchanging efficiency of a heat exchanger, by positioning a mixing pipe so that the extended center line of combustion flames runs along the arbitral section crossing with the longitudinal center line of a combustion chamber, and by displacing the pipe biasedly close to the outside direction of a combustion chamber by a suitable distance. CONSTITUTION:A mixing pipe 20 is positioned so that the extended center line B of combustion flames runs along the section C crossing at right angles with the longitudinal center line A extended to the discharge side of a combustion chamber 3, passing through its center part, and the pipe 20 is fitted to the combustion chamber eccentrically slipped off to the outer side of a combustion chamber 3 as much as a suitable distance D to the longitudinal center line A. The combustion gas is sprayed to the vicinity of the crossing point of the extended center line B of combustion flames and an inside wall 2a, and part of the gas flows to the direction of an arrow sign F along the surface 2a' of an inside wall, coming down to the circulation flow inlet port 16, being forcibly sucked into the mixing pipe 20, and is momentarily mixed with the mixed mist of kerosene particles and fresh air. The combustion gas dispersed to the direction of an arrow sign E flows upwardly, spirally circulating along the circumferential direction of the surface 2a' of an inside wall, and is discharged to the outside, exchanging heat with the water in a water chamber 2c. By this method, the heat exchanging efficiency of a heat exchanger can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchange device comprising a combustion device configured to gasify and burn a mixture of air and fuel by circulating combustion gas to a mixing pipe provided in front of a spray nozzle. .

BACKGROUND ART Conventionally, combustion devices such as oil water heaters include a type called a gun-type burner. This involves igniting and burning a mixture of fresh air sent from a blower and atomized fuel pressurized by an electromagnetic pump or the like and sprayed from a spray nozzle using a high-pressure electric discharge or the like. However, with this conventional method, the amount of air in the mixed mist is large, resulting in yellow flame combustion, resulting in poor combustion efficiency, and the carbon particles generated by yellow flame combustion adhere to the heat transfer surface inside the cone, reducing heat exchange efficiency. In addition, there was a drawback that the combustion noise caused by the vibration of the flame was loud.

゛ Also, recently, there has been a demand for higher combustion efficiency, lower noise, and cleaner exhaust gas from the viewpoint of energy saving and the environment, and so-called rotary gasification burners or heater gasification, which gasify fuel oil and combust it with blue flame, have been developed. Type burners have been developed.

However, in the former case, at the time of ignition and extinguishment,
There was a drawback that gasification of fuel oil was insufficient and odor was generated. Furthermore, the latter method requires a long time to preheat the heater, which is inconvenient in use, and also has the drawback of requiring complicated control of the heater. Furthermore, both have complicated fuel oil gasification structures and require special skills for maintenance and inspection.

The applicant of the present application has filed a heat exchange device in Japanese Patent Application No. 57-83799 to solve the above-mentioned drawbacks. That is, as shown in FIG. 1, the heat exchange device 29 has a cylindrical combustion chamber 33 formed inside a cone 32, and a spray nozzle inside a blast pipe 35 facing the combustion chamber 33. 34 is installed in the combustion chamber 33 and in a position in front of the spray nozzle 34, a mixing pipe 3 having a flame stabilizing plate 31 therein.
0 forms a combustion gas inlet 36 between the mixing pipe 30 and the blast pipe 35, and is perpendicular to the combustion flame extension center line G of the mixing pipe 30 and the longitudinal center line l of the combustion chamber. It was set up like this.

However, in the heat exchanger 29, since the combustion flame extension center line G of the mixing tube and the longitudinal center line H of the combustion chamber 33 are perpendicular to each other, the combustion gas ejected from the mixing tube 30 (not shown)
After being blown onto the inner circumferential wall surface 32a facing the mixing tube 30, the gas rises toward the exhaust side along the longitudinal direction of the inner circumferential wall surface 32a, and the gas flows along the circumferential direction of the inner circumferential wall surface 32a. It is dispersed into gas.

The gas dispersed clockwise and counterclockwise along the circumferential direction of the inner circumferential wall surface 32a collides on the inner circumferential wall surface 32a on the side where the mixing tube 30 is installed, and then the gas is sucked into the mixing tube 30. The remaining gas rises toward the discharge side along the longitudinal direction of the inner circumferential wall surface 32a. In this way, when looking at the device as a whole, most of the combustion gas is caused by the kinetic force component in the longitudinal direction of the inner peripheral wall surface 32a being larger than the kinetic force component in the circumferential direction of the inner peripheral wall surface 32a. The contact movement distance between the combustion gas and the inner circumferential wall surface 32a becomes shorter, and the combustion gas is discharged to the outside without sufficient contact with the inner circumferential wall surface 32a, which is a heat transfer surface. As a result, the conventional heat exchange device 29 has a drawback of low heat exchange efficiency.

The present invention aims to provide a heat exchange device with high heat exchange efficiency that can maintain sufficient combustion efficiency, low noise, and clean exhaust gas, while ensuring sufficient contact between the combustion gas and the inner peripheral wall surface that is the heat transfer surface. purpose.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIGS. 2 and 3 show a heat exchange device 1 according to an embodiment of the present invention. The main improvement of the heat exchange device 1 is that the extension center line B of the combustion flame ejected through the mixing tube 2o is different from the vertical center line A extending through the center of the combustion chamber 3 toward the exhaust side. Mixing pipe 2o along any perpendicular cross section C
, and the combustion flame extension center line B of the mixing tube 20 is eccentric to the outside of the combustion chamber 3 by an appropriate amount with respect to the longitudinal center line A.

The cone 2 has a double tube structure in which an ice chamber 2c is formed between an outer circumferential wall 2b and an inner circumferential wall 2a, and is a cylinder surrounded by the inner circumferential wall 2a and having an appropriate cross-sectional shape such as a circular cross-section or a polygonal cross-section. A combustion chamber 3 having a shape is formed. The outer periphery of the cone 2 is covered with a heat insulating material 5. Note that the cone 2 is not limited to a cylindrical shape, and may have a cross-sectional shape that changes along the longitudinal direction, such as a spherical or conical shape, although not shown. Further, the cone 2 is not limited to the double pipe structure, and although not shown, it may of course have a structure in which a long small diameter pipe is wound spirally to form a combustion chamber inside. It is possible, and any structure may be used as long as the inner circumferential wall surface forming the combustion chamber is a heat transfer surface for heat exchange. The combustion chamber 3
Inside and at the front position of the blast pipe 1°, which will be described later, a mixing pipe 20 is arranged with a predetermined gap W (for example, 15 mm) along a vertical center line that extends through the center of the combustion chamber 3 toward the exhaust side (in the illustrated embodiment, upward). The combustion flame extension center line B is located along the cross section C perpendicular to A, and the combustion flame extension center line B is set to an appropriate dimension D (for example, 1 of the radius of the combustion chamber 3) with respect to the vertical center line A. /3 to 1/2) is eccentrically installed toward the outside of the combustion chamber 3. Due to this gap W, a circulating gas inlet (hereinafter referred to as a circulating inlet) 16 is formed between the mixing pipe 20 and the blower tube 10 near the inner peripheral wall 2a of the cone 2 forming the combustion chamber 3. has been done. As shown in FIG. 4, the flame stabilizing section 15 having a multi-tube structure including the mixing tube 20 has a flame stabilizing plate 17 made of punched stainless steel metal or the like installed near the center thereof, and a flame stabilizing plate 17 made of punched metal made of stainless steel or the like is installed on the outer periphery of the flame stabilizing plate 17 in the downstream direction. A tapered cone-shaped flame-holding cylinder 19 that expands is installed. A sub-image flame tube 19 made of stainless steel punched metal or the like is installed on the outer periphery of this flame-holding tube 18, and a mixing tube 20 is further installed on the outer periphery of this.

The flame holding plate 17. Flame-holding cylinder 18. Sub-flame holding tube 19 and mixing tube 2
0 is connected by support legs 21, 21..., and the mixing pipe 20 is suspended on the blower pipe 10 by legs 22, 22.... In addition, the flame holding cylinder 18 and the sub-image flame cylinder 1
9 is installed as needed and is not necessarily required. A spray nozzle 8 is installed behind the flame holding section 15 so as to be substantially parallel to the combustion flame extension center line B, and sprays fuel oil pressurized by a hydraulic pump 7 (see FIG. 2). It is configured to eject in the form of fine particles.

A blower pipe 10 is installed around the outer periphery of the spray nozzle 8 for blowing fresh air blown by a blower 9 (see FIG. 2) to the mixing pipe 20. A high-speed air jetting plate 11 is installed at the tip opening of the blower pipe 10 (Q) as required. The air jet hole 13 has a plurality of air jet holes 13 which are bored at an appropriate circumferential pitch with a predetermined distance between each other.The air jet holes 13 are each inclined at a predetermined angle in the circumferential direction, and create a swirling flow in the ejected air. 14 generates a spark by high-voltage electricity near the tip of the spray nozzle 8 to further refine the fuel particles and evenly distribute the mixture of atomized fuel and fresh air. This is an electrode rod that ignites fine particles of fuel oil.In Fig. 1, 25 is a combustion tube, 24 is an exhaust chimney, 26 is a water supply port, and 27 is a hot water supply port.

Next, the operation of the heat exchange device 1 configured as described above will be explained as follows.
The explanation will be based on the case where water is used as the heat exchange fluid, kerosene is used as the fuel oil, and the amount of kerosene and fresh air supplied are constant.

The atomized kerosene particles ejected from the spray nozzle 8 are ignited by the spark of the electrode rod 16, and at first begin yellow flame combustion near the tip of the ejection plate 11.

In this condition there is an excess of air. After that, this combustion flame gradually moves toward the spray direction and is propagated to the secondary flame cylinder 19,
Further, it moves to the flame stabilizing plate 17, is rectified on the way to the flame stabilizing plate 17, becomes stable on the flame stabilizing plate 17, and is guided to the flame stabilizing tube 18 to maintain steady combustion. In this way, the sub-image flame cylinder 19
serves to smooth the propagation of the combustion flame when it moves to the flame holding plate 11. Note that the ejection plate 11. When the flame stabilizing tube 18 and the subimage flame tube 19 are not installed, stable combustion is started and maintained at the holding roots 17 by spark ignition near the flame stabilizing plate 17.

As shown in FIG. 3, the combustion gas is blown around the intersection of the combustion flame extension center line B and the inner circumferential wall 2a of the string 2, and a part of it is blown inside the string 2 due to the kinetic energy of the combustion gas. It flows along the peripheral wall surface 2a' in the direction of arrow F, and reaches the circulation inlet 16 while exchanging heat with the water in the ice chamber 2c. Then, the combustion gas is forcibly drawn into the mixing pipe 2o by the negative pressure generated by the swirling airflow passing through the gap W from the blast pipe 10 to the mixing pipe 20 at high speed, and instantaneously becomes a mixed mist of kerosene particles and fresh air. Mix with. On the other hand, the combustion gas dispersed in the direction of arrow E flows upward while circulating spirally along the circumferential direction of the inner peripheral wall surface 2a' of the string body 2 due to the kinetic energy of the combustion gas, During the long period of contact with the combustion tube 25, while sufficiently exchanging heat with the water in the ice chamber 2C,
and is exhausted to the outside via the exhaust chimney 24. The circulating combustion gas sucked into the mixing tube 20 warms the mixed mist of very fine kerosene particles and fresh air due to the swirling air flow, and instantly turns the kerosene particles into a gaseous state or a state 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 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 gastritis combustion is maintained.

In order to obtain the gastritis combustion described above, it is necessary to mix an appropriate amount of combustion gas into the mixed mist of fresh air and kerosene particles, and to reduce the negative pressure (suction effect) generated at the circulation inlet 16. The size of is a 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. Ta. The four factors that affect the flow velocity of the blowing air are the output of the blower III 9 and the blower pipe 1.
If the inner diameter of 0 (in this case, the diameter is 8 On+m 2 ) is constant, then the hole diameters of the central nozzle 12 and the air nozzle 13 and the area ratio of both nozzles 12 and 13 are the same. In addition, the air jet hole 13
The number of and the distance between the central nozzle 12 and the air nozzle 13 have almost no effect on the flow velocity of the ejected air and can be ignored. However, if the distance between the two nozzle holes 12 and 13 exceeds an optimum value, good mixing of kerosene particles and air will not be obtained. In this embodiment, the diameter of the blast pipe 10 is 80 mm (combustion output is 35,0OOK cal/[(r
), 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 hole diameter of the nozzle 12.13 and the air flow rate and amount of supplied air when ejected from the nozzle 12.13 into the natural atmosphere.

Table 1 As is clear from Table 1, if the diameter of the air jet hole 13 is made smaller, the flow velocity of the jet air becomes faster, and the circulation inlet 1
6, the negative pressure generated becomes larger. However, the amount of supplied air tends to decrease as the diameter of the air jet hole 13 becomes smaller. Therefore, the diameter of the hole must be 8 mm to ensure a sufficient amount of supplied air and a high flow rate.

(Left below) Table 2 However, the aperture ratio of the holes 12 is the value obtained by dividing the opening area of the central nozzle 12 by the sum of the opening areas of the central nozzle 12 and the air nozzle 13 multiplied by 100. It is.

Further, as is clear from Table 2, if the hole diameter of the central jet hole 12 is made smaller, the flow velocity increases, but the amount of air supplied decreases. Moreover, the central nozzle 12 and the air nozzle 13
The ratio of the opening area of the central jet hole 12 to the entire opening area of the central jet hole 12 takes a value proportional to the amount of air. Therefore, the diameter of the central ejection hole 12 is optimally 18 to 20111111, without considering the balance between the amount of supplied air and the flow rate of ejected air.

When the diameter of the central nozzle 12 was 18 mm, the diameter of the air nozzle 13 was 8 nua, the diameter of the air nozzle 13 was 8 mm, and the diameter of the blast pipe 10 was 80 mm, the air flow velocity in the spire was measured to be 21 m/sec. . For your reference,
The air flow velocity of conventional commercially available combustion devices is usually 12.
The speed was about 5m/sec.

In short, the flame stabilizing section 15 warms the kerosene particles in the mixing tube 20 with circulating combustion gas to turn them into a gasified state or a state close to this, and also adds combustion gas to the mixed mist of air and kerosene particles. Since gastritis combustion is performed at an air ratio close to the air ratio, a large amount of heat is generated for a given amount of fuel, resulting in excellent thermal efficiency. Furthermore, since gastritis combustion is rectified, there is also the advantage that the combustion noise is low.

As explained above, the heat exchange device according to the present invention has the following excellent effects.

■ Position the mixing tube so that the extended center line of the combustion flame ejected through the mixing tube is along an arbitrary cross section perpendicular to the vertical center line extending through the center of the combustion chamber to the exhaust side; In addition, since the combustion flame extension center line of the mixing tube is oriented eccentrically toward the outside of the combustion chamber by an appropriate dimension with respect to the vertical center line, most of the combustion gas is directed toward the inner circumferential wall surface of the cone. It flows upward while circulating in a spiral along the circumferential direction, and after sufficient heat exchange occurs while in contact with the inner circumferential wall surface for a long time, it is discharged to the outside, improving heat exchange efficiency. .

■ In addition, by circulating the combustion gas through the mixing tube and warming the fuel particles, it is possible to achieve gasification or a state close to this, and by adding the combustion gas to the mixture of fresh air and fuel particles, the air ratio is close to the stoichiometric air ratio. By burning at a ratio of
It can burn gastritis, generates a large amount of heat for a given amount of fuel, and has excellent thermal efficiency.

(2) Another advantage is that combustion noise is low because the combustion flame is a steady blue flame and the mixing tube has a rectifying effect.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a conventional heat exchange device, Fig. 2 is a longitudinal cross-sectional view showing an embodiment of the heat exchange device according to the present invention, Fig. 3 is a cross-sectional view of the same, and Fig. 4 is a mixing tube. FIG. 2... String 3... Combustion chamber 8... Spray nozzle 10... Air pipe 16... Circulation inlet 20...
・Mixing tube A...Vertical center line B...Central line of combustion flame extension C...Cross section Patent applicant Ina Seito Co., Ltd. Representative Patent attorney Toshihiko Uchida Figure 3/L/

Claims (1)

[Claims] 1. A combustion chamber is formed inside the stationary body, a spray nozzle is installed inside a blow pipe whose tip faces the combustion chamber, and a mixing pipe with a built-in flame holding plate is installed in the front position of the blow pipe. In the heat exchange device installed so as to form a combustion gas inlet between the tip of the blast pipe, the installation orientation of the mixing pipe is such that the installation position of the mixing pipe is aligned with the extension center line of the combustion flame ejected through the mixing pipe. but,
It is positioned along an arbitrary cross section perpendicular to a longitudinal center line extending through the center of the combustion chamber to the exhaust side, and is eccentric to the outside of the combustion chamber by an appropriate dimension with respect to the longitudinal center line. A heat exchange device characterized in that it is oriented in such a manner.