JPS6153602B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a forced premix gas burner having flame hole cooling means.

For example, when a conventional forced premix gas burner is used in a water heater, as shown in Figs. 4 to 6,
It has a rectangular cross section and a cylindrical shape with one end open.
The flame holes 2 were small holes provided in stainless steel perforated plates 1 on both sides. The upper and lower parts of this burner are made of sheet metal members 3 made of stainless steel or the like, which are the same as the perforated plate 1, and a flange 4 is provided at the open end, and a mixture chamber 5 is fixed to this flange 4. An air supply port 6 is provided. Further, the cooling pipe 7 is connected to the perforated plate 1.
There are 3 pieces fixed on the left and right sides of the inner surface. Further, the space inside the burner constituted by the perforated plate 1 and the sheet metal member 3 is a mixture flow path 8. Further, the cooling pipes 7 are connected by a U-bend 9. This burner consists of a sealed combustion chamber 1 with a heat exchanger 10 at the top.
It is located within 1. The cooling pipe 7 is branched from and connected to the water supply pipe 12, and constitutes a bypass path with respect to the water supply path from the combustion chamber drum 13 to the heat exchanger 10.

In the above configuration, the premixture of gas fuel and air flowing in from the mixture supply port 6 is forcibly mixed using a fan, and the amount of air required for combustion is reduced.
This is a completely premixed mixture of 100% or more. Combustion of this mixture is called fully premixed combustion or all primary air combustion, and unlike Bunsen combustion, it does not require any secondary air, so the flame is only the primary flame, and so-called external flames do not occur. Therefore, since the flame is short, it has the great advantage of being able to achieve high-load combustion. However, on the other hand, since a high-temperature flame is formed near the flame hole, the flame hole becomes hot due to radiation from the flame, and it is very dangerous because it may backfire. For this reason, it was essential to cool the flame hole. Therefore, conventionally, a method has been adopted in which a cooling pipe 7 is fixed to the perforated plate 1 and cooling water is branched from a water supply pipe and passed through to cool the flame hole. However, the fixation of the perforated plate 1 and the cooling pipe 7 is because the cross section of the cooling pipe 7 is circular, and even if it is fixed to the perforated plate 1, which is a flat plate, with a stopper or the like, it is a line contact, and it does not contact completely.
Since a reliable cooling effect cannot be expected, brazing is generally used. However, since the perforated plate 1 is made of stainless steel, an oxide film is formed on the surface and cannot be fixed by ordinary furnace brazing (for example, a nitrogen atmosphere furnace, a propane atmosphere furnace, etc.). Therefore, since the brazing method involves a complicated process using a furnace such as a vacuum furnace or a hydrogen atmosphere furnace, the production cost is extremely high. but,
The perforated plate 1 to which the cooling pipes 7 are brazed by the method described above is cooled to a temperature lower than the flame hole temperature of a normal gas burner near the cooling pipes 7 during combustion, but on the other hand, near the center of the cooling pipes 7 Due to the high temperature, local deformation occurs, causing metal fatigue and deteriorating durability. Furthermore, since the outer surface of the perforated plate 1 in the vicinity to which the cooling pipe 7 is brazed is cooled at an abnormally low temperature for a burner flame hole as described above, the outer surface of the perforated plate 1 is formed in the vicinity of the perforated plate 1 when the combustion amount is low. When the base of a flame touches a low-temperature area, condensation water containing sulfate ions, nitrate ions, etc. is generated, causing corrosion and deteriorating durability. Furthermore, when the base of the flame cools, it interferes with the combustion reaction and generates CO, making it impossible to continue stable combustion. On the other hand, the air-fuel mixture supplied from the air-fuel mixture supply port 6 has a flow velocity near the burner entrance and tends to advance toward the tip of the burner, so more air-fuel mixture is ejected from the flame hole 2 near the tip. The disadvantage was that the flame caused by this process tended to float, making combustion unstable.

The present invention solves the above-mentioned conventional drawbacks. It prevents local deformation and dew condensation through a uniform flame hole cooling effect, allows stable combustion to continue, and eliminates the need for expensive fixing means such as brazing in the furnace. Another object of the present invention is to provide a forced premixing gas burner that can be manufactured easily and inexpensively.

In order to achieve this purpose, the present invention uses a plurality of fins each having a slit-like notch, a mixture through-hole connected to the slit-like notch, and a cooling pipe through-hole separate from this hole, and these fins are the same. The pipe is shaped like a fin row with two types of fins arranged at both ends for the end without a slit-like notch, one end of which is closed for the air-fuel mixture to flow in, and a plurality of air-fuel mixture jet holes. A cooling pipe for introducing a cooling medium is passed through to form a structural member, and this structural member is formed of a perforated plate having a plurality of small holes serving as flame holes, and has a cross section of the same shape as the fins and internal dimensions. are provided inside substantially the same cylindrical member, and the fins and the perforated plate are brought into contact with each other.

In the above configuration, a cooling medium flows through the cooling pipe to cool the fins. As a result, the perforated plate in contact with the fins is also cooled. Further, the mixture introduced into the mixture pipe is supplied into the burner from each mixture jet hole.

Hereinafter, a burner for a water heater according to an embodiment of the present invention will be described using FIGS. 1 to 3. In these figures, the same members as those in FIGS. 4 to 6 are given the same numbers. A cylindrical member having a triangular cross section is constituted by a perforated plate 1,
A large number of flame holes 2 are opened on the oblique side, but no flame holes are provided on the bottom side 14. Inside this cylindrical member, there is provided a structural member composed of a mixture pipe 17 and a cooling pipe 7 that pass through a fin row composed of a plurality of fins 15 and end fins 16. The fin 15 has a mixture pipe through hole 1 through which the mixture pipe 17 passes.
8 and a cooling pipe through hole 19 through which the cooling pipe passes.
are opened, especially the mixture pipe through hole 18
The slit-like notches 20 are opened continuously. The end fins 16 have substantially the same shape as the fins 15, but are not provided with the slit-like notches 20. These two types of fins are made of aluminum plates, and their outer dimensions are about 0.1 to 0.2 mm smaller than the inner dimensions of the cylindrical member.

Further, one end of the mixture pipe 17 is closed, a flange 21 is attached to the other end, and a plurality of mixture jet holes 2 are provided between the left and right end fins 16.
2 is dawning. A total of three cooling pipes 7 pass through the cooling pipe 7, but they are connected at two locations by U-bends 9. Fin 15 and perforated plate 1 or fin 15
The space formed by the end fins 16 and the perforated plate 1 is the air mixture chamber 8. In addition, a fin row composed of fins 15 and 16 is connected to a pipe 17.
After passing through the cooling pipe 7, the pipes are expanded and brought into close contact with each other.

In the burner configured as described above, the premixture forcibly mixed by a fan is guided to the pipe 17, passes through each mixture chamber 8 from the mixture jet port 22, and is sent to the perforated plate 1.
The flame is ejected from the flame hole 2 provided in the flame hole 2 and burns. At this time, as in the conventional example, the water bypasses the water supply path and flows through the cooling pipe.

In the above burner, when the fins 15 are cooled by water flowing in the cooling pipe, the perforated plate 1 is also cooled by heat conduction, so the perforated plate 1 is not cooled to an abnormally low temperature as in the conventional case. No local deformation occurs in 1, suppresses metal fatigue, and improves durability. Further, even when the amount of combustion is reduced, no condensation water is formed on the surface of the perforated plate 1, so corrosion will not occur. Furthermore, since the base of the flame is not abnormally cooled, it has the effect of stably continuing combustion. Further, the fin 15 has a slit-like notch 20.
are provided at three locations, and when the pipe 17 is expanded, these notches are pushed out and the end face of the fin 15 is brought into close contact with the inner surface of the perforated plate 1. There is no need to use processing means by attachment. Therefore, it has a great effect on reducing manufacturing costs. In addition, the mixture pipe 17 has a large number of mixture jet ports 22, which has a pressure equalizing effect to disperse the mixture, so that the flame formed on the burner surface is uniform, preventing the phenomenon of the flame rising locally. This allows stable combustion to continue.

As described above, the forced premixed gas burner of the present invention has the following effects.

(1) It has a structure in which a perforated plate with flame holes is placed in close contact with the fins that pass through the cooling pipe. When the cooling medium flows into the cooling pipe, the fins are first cooled, and as a result, the perforated plate is cooled by heat conduction. This eliminates the possibility of the perforated plate being abnormally cooled and causing local deformation, as was the case in the past.
Improve durability.

(2) Even when the combustion amount of the burner is reduced, the perforated plate 1
is not cooled abnormally, so the flame base does not touch and condensate on the surface of the perforated plate 1. This prevents corrosion caused by this condensed water. Further, since the flame base becomes abnormally low temperature and the combustion reaction is not hindered, stable combustion can be continued.

(3) In the conventional structure, as mentioned above, the flame hole could not be cooled by heat transfer unless expensive processing methods such as furnace brazing were used to fix the perforated plate and the cooling pipe, but in the present invention, the cooling pipe Since the fins that are in close contact with each other are efficiently cooled and the perforated plate that is in close contact with these fins is also cooled well, there is no need to use expensive processing means as described above.
Therefore, it has a great effect on reducing manufacturing costs.

(4) The mixture pipe has a large number of air-fuel mixture outlets and is installed inside the burner, and the air-fuel mixture is uniformly supplied to each flame hole, so the flame is formed evenly and phenomena such as local floating are avoided. This allows stable combustion to continue.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional perspective view of a forced premix gas burner for a water heater that is an embodiment of the present invention, FIG. 2 is a cross-sectional view of the burner shown in FIG. 1, and FIG. 4 is a cross-sectional view of a water heater using a conventional burner, FIG. 5 is a perspective view of the conventional burner, and FIG. 6 is a cross-sectional view of the burner of FIG. 5. 1... Perforated plate, 2... Flame hole, 7... Cooling pipe, 15... Fin, 16... End fin, 1
7...Mixture pipe, 18...Mixture mixture pipe through hole, 19...Cooling pipe through hole, 20...Slit-shaped notch, 22...Mixture mixture jet hole.

Claims (1)

[Claims] 1. A plurality of fins each having a slit-shaped notch, a mixture pipe through-hole connected to the slit-like notch, and a cooling pipe through-hole different from the fin, the fins having the same shape and without the slit-like notch. A fin row with end fins arranged at both ends has a plurality of air-fuel mixture jet holes with one end closed, and a mixture pipe serving as a mixture flow path and a cooling pipe serving as a flow path for a cooling medium. A structural member made by penetrating each through hole of the fin and the end fin is placed inside a cylindrical member formed of a perforated plate having a plurality of flame holes and having the same external shape as the fin in cross section. Forced premixed gas burner installed.