JPH0247644B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a liquid fuel combustion device, and more specifically, the present invention relates to a liquid fuel combustion device, and more specifically, the present invention relates to a liquid fuel combustion device that vaporizes liquid fuel and sends the liquid fuel together with primary air as a premixed gas to the flame nozzle for combustion. Related to fuel combustion equipment.

(Prior art) Conventionally, this type of liquid fuel combustion device
This is well known as disclosed in Japanese Patent No.-160724, and the conventional device was constructed as shown in FIGS. 1 and 2.

First, the conventional example shown in FIG. 1 will be explained. The conventional liquid fuel combustion device is equipped with a vaporizer cylinder 1, and the vaporizer cylinder 1 has a heating heater 2 embedded in the upper wall and an outlet section in the upper part. The mixing plate 3 has an attached mixing plate 3 having a diaphragm shape, and is connected to a blowing fan 5 via a blowing passage 4 formed in a lower side wall portion thereof. Inside the carburetor cylinder 1, the tip nozzle portion of the fuel capillary 6 is arranged above the center axis of the ventilation passage 4.
The fuel tube 6 is connected to a fuel tank 8 via a fuel pump 7.
It is connected to the.

At the upper end of the vaporizing cylinder 1, there is a flame hole cylinder body, that is, a cylinder body 1 formed by forming a wire mesh into a cylindrical shape through a ring-shaped cylinder 9.
0 is arranged, and the upper end of the cylindrical body 10 is connected to the cap 11.
is blocked by. As a result, the cylindrical body 10
A rectifying chamber 12 is formed inside the cylinder body 10 , and a combustion chamber 13 is formed between the cylinder body 10 and the outer cylinder 14 .

Such a conventional liquid fuel combustion device operates as follows.

The interior of the vaporizer cylinder 1 is maintained at a high temperature range by the heater 2, and the vaporized gas generated in the vaporizer cylinder 1 by the drive of the blower fan 5 and fuel pump 7 is passed through the mixing plate 3.
It is sufficiently mixed with air by the constriction part of the rectifying chamber 1.
2 and flows out from the cylindrical body 10 toward the combustion chamber 13, where a combustion flame is formed by an igniter (not shown).

(Problem to be Solved by the Invention) However, according to the conventional liquid fuel combustion device as described above, the vaporized gas and air are sufficiently mixed in the vaporizing tube 1 in the mixing plate 3 due to the throttling effect; The rectification chamber 12 has a large spatial volume, and the cylinder 10 itself does not have a large passage resistance, so the flow speed of the premixed gas is increased by the constriction part of the mixing plate 3.
The forced flow continues upward, increasing the amount of ejection from the vicinity of the closed cap 11, and as shown in Fig. 2, the ejection pressure distribution in the cylinder 10 becomes unbalanced, resulting in flame uniformity. I can't. As a result, ignitability deteriorates and combustion starts locally, and it takes time for the entire body to heat up. This results in the generation of CO and odors due to disturbances in the air-fuel ratio, as well as high temperatures in some parts. area and nitrogen oxides are generated. Furthermore, since the temperature distribution of the cylindrical body 10 becomes non-uniform, the degree of thermal expansion becomes non-uniform, leading to deformation. Furthermore, because the distribution of the ejection pressure between the upper and lower parts is uneven, as the upper part becomes hot during steady state, an imbalance occurs between the ejection speed and the combustion speed, causing a flashback phenomenon.

In addition to the non-uniform distribution of the ejection pressure mentioned above as a cause of the flashback phenomenon, the premixture
On the way to the upper part 10a of the cylinder, the flame formed on the surface of the cylinder 10, which is already in a red-hot state, heats up the premixture temperature, causing an increase in the combustion rate. That is, in the conventional example, the causes of the flashback phenomenon from the upper part 10a of the cylinder body 10 are (1) uneven distribution of ejection pressure, (2) rise in temperature of the premixture; (2) It had the disadvantage that backfire was likely to occur due to the synergistic effect of the causes described above.

Furthermore, in those that perform this type of fully premixed surface combustion, the excess air ratio is 1 or more (usually 1.2 to 1).
1.5), which significantly degrades the ignition performance.Therefore, in order to increase the certainty of ignition, a pre-purge is performed to raise the temperature of the cylinder 10 and prevent the vaporized liquid fuel from recondensing, but this pre-purge time also This had the disadvantage that it had to be set for a somewhat long time.

An object of the present invention is to eliminate the drawbacks of such conventional liquid fuel combustion devices, and to maintain the flame hole cylinder forming the flame port in a uniform red-hot state at all times, thereby preventing thermal deformation and
It is an object of the present invention to provide a liquid fuel combustion device that prevents flashback phenomena or the generation of nitrogen oxides and performs stable, completely premixed surface combustion.

(Means for Solving the Problems) The present invention includes a vaporizer cylinder for vaporizing liquid fuel and a flame hole cylinder disposed on the upper part of the vaporizer cylinder, and the liquid fuel is vaporized in the vaporizer cylinder, and the liquid fuel is vaporized together with primary air. In a liquid fuel combustion device in which a premixed mixture is sent to the flame hole cylinder for combustion, a closed cap having a bottom depressed into the inside of the flame hole cylinder is provided at the upper end of the flame hole cylinder, and the closed cap is It is characterized by forced cooling.

(Function) According to the liquid fuel combustion apparatus of the present invention, the temperature of the vaporization cylinder is raised to a temperature suitable for vaporizing the fuel by a heater or the like, and at that point, combustion air is introduced into the vaporization cylinder. Accordingly, the fuel that has been atomized by the combustion air and transported into the vaporization cylinder instantly becomes vaporized gas within the vaporization cylinder, and becomes a premixture. This premixed gas flows out from the opening in the surface of the cylinder, is ignited by the ignition means, and the flame propagates to the entire surface of the cylinder. During the combustion of liquid fuel, the temperature distribution in the cylinder body is conventionally high at the top, but in the present invention, the closed cap is forcibly cooled, so the temperature distribution is uniform, and the premixture is distributed over the entire surface of the cylinder body. The ejection speed and combustion speed are kept in balance.

(Embodiments) Hereinafter, the liquid fuel combustion apparatus of the present invention will be described in more detail with reference to embodiments shown in the accompanying drawings.

FIG. 3 shows an example in which a liquid fuel combustion device according to an embodiment of the present invention is mounted on a hot air blower.
In FIG. 3 showing this embodiment, parts that are the same as or correspond to the components of the conventional liquid fuel combustion apparatus shown in FIG.

This liquid fuel combustion device consists of a mixing plate 3 which is arranged above a vaporizing cylinder 1 attached to a mounting member 15 and has a constricted part in the center, and is made of porous metal such as punched metal, which is arranged to cover the constricted part. It is provided with blastosphere-shaped current plates 16a and 16b made of members. A circumferential heat recovery wall 1a is formed upright on the outer peripheral edge of the vaporization cylinder 1. The reason why two such large and small rectifying plates are provided is to make the outflow of the premixture into the rectifying chamber 12 more uniform.

The tip of the ventilation passage 4 forms a nozzle 4a, which is connected to the vaporizer cylinder 1. The lower end of the cylindrical body 10 is inserted into a narrow circumferential groove 3a formed in the mixing plate 3, and then integrally crimped and fixed. A closed cap 30 in the shape of an inverted cone with a bottom is disposed inside the cylinder 10 from the upper end, and the upper end peripheral edge of the closed cap 30 forms a stepped shoulder 30b and a ring-shaped fixing part 30a with an enlarged diameter. is formed. Therefore, a tapered surface 30c that tapers downward from the stepped shoulder portion 30b extends to the bottom 30d. This closing cap 30 is disposed from the top of the cylinder 10 into the interior, and its ring-shaped fixing portion 30a is integrally fixed to the upper end of the cylinder 10 by seam welding or the like.
As a result, the rectification chamber 12 becomes tapered toward the top.

A cooling air blowing passage 1 is inserted into the inside of the closed cap 30, which is formed in a concave shape and has an inverted conical shape with a bottom.
8 is arranged so that one end thereof is open facing the bottom 30d. A guide plate 17 having a tapered body 17a and a horizontal edge 17b is fixed to the outer circumferential wall of this cooling air blowing duct 18. The surface 30c and the edge 17b form the stepped portion 30.
b, and are fixed at positions that form cooling air passages 19a and 19b, respectively. This cooling air passage 19b is perpendicular to the ring-shaped fixing part 30a,
The cooling effect of the ring-shaped fixed part is maximized. The other end of the cooling air blowing passage 18 forms a tapered air intake port 18a that expands to a large diameter.
The opening is positioned in the air duct.

In the upper part of the cylindrical body 10, a cooling air blowing passage 1 is provided.
A baffle plate 21 is fixed to 8 to protect the flame part from being affected by hot air blowing. Note that 22 is a lower partition plate of the combustion chamber 13, 23 is a gasket for preventing leakage of hot air, 24 is a glass window for taking out radiant heat, and 25 is a looper for rectifying the flow of hot air.

FIG. 5 shows a method of fixing the mixing plate 3 to the vaporization tube 1. A plurality of notches 1b are provided in the heat recovery wall 1a of the vaporization tube 1, and screw holes are formed in the notches 1b. A protrusion 3b formed on the mixing plate 3 corresponding to the notch 1b is fitted and fixed with a screw 26.

Next, the operation of this liquid fuel combustion device will be explained.

When the heating heater 2 is energized and the temperature of the vaporization cylinder 1 rises to a predetermined temperature suitable for vaporizing the fuel, a combustion blower fan (not shown) is driven, and the air is sent to the vaporization cylinder 1 through the ventilation passage 4. Inject combustion air. On the other hand, fuel is also pushed out from the tip of the fuel thin tube 6 by a fuel supply means such as an electromagnetic pump, and the fuel is pushed out from the tip of the fuel tube 6.
The combustion air atomizes the gas and transports it into the interior, instantly turning it into vaporized gas, which then becomes a premixture mixed with the combustion air at the molecular level. This premixture is mixed at mixing plate 3.
The concentration is made uniform by collecting the fluid at the constriction part, and the upward flow velocity of the constriction part is adjusted by the rectifying plate 16a so as to be distributed in all directions, and the rectifying plate 16b
As a result, the outflow distribution in all directions is made more uniform as shown by the dotted line arrows in FIG. 4, and the outflow is guided to the rectification chamber 12.

The premixture flow velocity becomes smaller in the rectification chamber 12,
It flows out into the combustion chamber 13 from the opening of the cylinder 10,
At this time, ignition is performed by an ignition means (not shown), and the flame propagates to the entire surface of the cylindrical body 10. The ignition point is selected at the lower part of the cylinder 10, where the temperature of the wire gauze increases by heat conduction to a temperature at which recondensation of the premixture does not occur. When a flame is formed, it receives a signal from a flame detection means (not shown) such as a flame rod, and
The hot air blowing fan 20 is driven. A part of the air blown by the hot air blowing fan is introduced into the cooling air blowing passage 18 through the air intake port 18a, and hits the bottom 30d of the closed cap 30 as shown by the solid line arrow in FIG. Via roads 19a and 19b,
It is guided to the combustion chamber 13.

At this time, the cooling air cools the closed cap 30 to cool the premixture in contact with the cap, thereby preventing the temperature of the premixture from rising.
By hitting the ring-shaped fixing part 30a adjacent to the upper part 10a, which has the highest temperature of the cylindrical body 10, and to which the cylindrical body 10 is fixed, the upper part 1 of the cylindrical body
0a is also cooled. Since the rectification chamber 12 is an upwardly tapering passage, and the pressure loss increases upward, the ejection pressure of the cylinder 10 does not increase upward as seen in FIG. However, the pressure is equalized, and temperature unevenness in the cylinder body 10 is eliminated. The heat from the flame is received by the heat recovery wall 1a, and the heat is used to vaporize the fuel and heat the combustion air in the vaporizer cylinder 1, so that after ignition, the electricity consumption of the heater 2 is zero or small. .

Fig. 6a shows a modification in which the tapered body 17a of the guide plate 17 is removed and the horizontal edge 17b is extended to the cooling air blowing path, but the cooling effect of the premixture is compared with Fig. 4. Although the cooling effect of the upper part 10a of the cylindrical body 10 is slightly weakened, there is no change in the cooling effect. 6b shows an example in which, contrary to the case of FIG. 6a, the horizontal edge 17b of the guide plate 17 is eliminated and the tapered body 17a is extended to the ring-shaped fixing part 30a of the closing cap 30.

FIG. 7 shows a modification in which air for cooling the closed cap is guided not from a hot air blowing fan but from a combustion blowing fan. Reference numeral 27 indicates a combustion fan, and 28 indicates a ventilation passage.The ventilation passage 28 is branched into a combustion ventilation passage 4 and a cooling air passage 18. An air volume adjustment screw 29 is interposed at the bend of the cooling air blowing passage 18 . Note that the effect is the same as that of the previous embodiment.

(Effects of the Invention) As explained above, according to the liquid fuel combustion device of the present invention, a closed cap is provided at the upper end of the flame hole cylinder, the bottom of which is sunken into the inside of the flame hole cylinder. By forcibly cooling the air-fuel mixture with cooling air, the air-fuel mixture outflow distribution from the flame hole cylinder is made uniform and the flame distribution is improved. The temperature of the burner body is reduced, which maintains the burner tube in a uniform red-hot state and prevents thermal deformation, flashback, and the generation of nitrogen oxides.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional liquid fuel combustion device, Fig. 2 is a characteristic diagram drawn in a half cross section of the conventional device to show the pressure loss distribution in the conventional device of Fig. 1, and Fig. 3 is a A sectional view showing a liquid fuel combustion device according to an embodiment of the present invention, FIG. 4 is a fragmentary sectional view showing an enlarged main part of the liquid fuel combustion device shown in FIG. 3, and FIG. FIG. 3 is a partial perspective view showing the mounting structure of the cylinder in the combustion device shown in FIG. 3, and FIGS. 6a and 6b are partial perspective views showing modifications of the combustion device shown in FIG. 7 is a sectional view showing a liquid fuel combustion apparatus according to a modification of FIG. 3 in which cooling air is guided from a combustion fan. DESCRIPTION OF SYMBOLS 1... Vaporization cylinder, 3... Mixing plate, 10... Flame hole cylinder, 10a... Upper part of cylinder, 12... Rectification chamber, 16
a, 16b... Current plate, 18... Cooling air blowing path, 20... Warm air blowing fan, 27... Combustion blowing fan, 30... Closed cap. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A vaporizing cylinder for vaporizing liquid fuel and a flame hole cylinder disposed at the upper part of the vaporizing cylinder, the liquid fuel being vaporized in the vaporizing cylinder, and the flame being produced as a premixed gas together with primary air. A liquid fuel combustion device in which liquid fuel is sent to a cylindrical hole for combustion, characterized in that a closed cap with a bottom depressed into the inside of the cylindrical flame hole is provided at the upper end of the cylindrical flame hole, and the closed cap is forcibly cooled. liquid fuel combustion equipment. 2. The liquid fuel combustion device according to claim 1, wherein the flame hole cylinder is formed of a cylindrical wire mesh. 3. The liquid fuel combustion device according to claim 1 or 2, wherein the air for forcibly cooling the closed cap is guided from a hot air blowing fan. 4. The liquid fuel combustion device according to claim 1 or 2, wherein air for forcibly cooling the closed cap is guided from a combustion fan. 5. The closing cap enters into the flame hole cylindrical body with a cross-sectional shape that becomes narrower toward the upper part of the rectifying chamber defined between the closing cap and the inner surface of the flame hole cylindrical body. A liquid fuel combustion device according to claim 1, 2, 3, or 4.