JPS61223428A - Burning device - Google Patents

Abstract

PURPOSE:To prevent generation of harmful carbon monoxide and permit low NOx combustion in a burner head during stationary combustion by a method wherein combustion air is divided and one part thereof is supplied to an exhaust gas path by a switching valve upon igniting while the same air is switched to supply it into a flow regulating chamber during the stationary combustion. CONSTITUTION:The combustion air, supplied by a combustion fan 8, is divided and one part of it is supplied into an evaporating chamber 4 through primary air path 9 while the other part is supplied into the air regulating chamber 17, sending out premixed gas from the evaporating chamber 4 into the primary combustion burner head 14, through secondary air path 22. Third air path 33, supplying a part of the combustion air into an exhaust gas path 23, is branched and is provided with a switching valve 20, guiding a part of the combustion air into the flow regulating chamber 17 during the stationary combustion and guiding the same air into the exhaust gas path 23 upon igniting the fuel. According to this method, fuel is ignited easily and the harmful carbon monoxide, easily generated, is oxidized and burnt by the combustion air, supplied into the exhaust gas path 23 by the switching valve 20. During the stationary combustion after ignition, the low NOx combustion may be effected on allover the surface of the primary combustion burner head 14.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improvement in the ignition characteristics of a combustion device that mixes force-fed combustion air and fuel to perform total combustion.

2. Description of the Related Art As shown in FIG. 3, a conventional combustion apparatus of this type is divided into a vaporizing cylinder 52 heated by a heater 51 and an auxiliary burner 53 disposed at its upper opening. A vaporization chamber 56 that vaporizes the liquid fuel supplied from the tank 55 to form a premixture, and a vaporization chamber 56 disposed above the auxiliary burner 53 to mix the premixture from the vaporization chamber 56, are made of a ceramic plate and have a surface. a rectifying chamber 58 that sends out the premixture to the main burner 57 where it performs the primary combustion; a primary air system passage 60 that leads from the combustion fan 59 that supplies combustion air to the vaporization chamber 56; A secondary air system path 61 that branches off from the main burner 57 and reaches the rectification chamber 58, and a secondary air system path 53 provided at the branch section for heating the main burner 57. During combustion, the combustion air is divided into a primary air system path 60 and a secondary air system path. The switching valve 62 guides the entire amount of combustion air to the primary air line when the main burner 57 is in combustion, and the igniters 63 and 64 ignite the auxiliary burner 53 and the main burner 57. In the above configuration, when the vaporization cylinder 52 is heated to a predetermined temperature, fuel is supplied by the pump 54 and combustion air is supplied by the combustion fan 59. At this time, the switching valve 6
Since the second valve body 62A is biased downward and closes the primary air hole 62B, the combustion air is divided by the secondary air port 62C and the bypass hole 62D and guided to the vaporizing chamber 56 and the rectifying chamber 58, respectively. Part of the combustion air that has entered the vaporization chamber 56 and the vaporized fuel gas are mixed to form a premixture, which is ejected from the auxiliary burner 53 into the rectifying chamber 58 and ignited by the igniter 6a to cause combustion. bypass hole 62
Since the amount of air supplied to the vaporization chamber 56 through D is less than the theoretical air amount of the fuel, the concentration of the premixture ejected from the auxiliary burner 53 is high, and ignition by the igniter 6a becomes easy. However, since combustion in the auxiliary burner 53 is performed with less than the theoretical amount of air, a large amount of carbon monoxide is generated due to incomplete combustion due to lack of air. Carbon monoxide is not emitted because it is re-combusted using the supplied combustion air. Secondary burner 5
The high temperature exhaust gas from the combustion of No. 3 passes through the rectifying chamber 58 and is discharged from the main burner 57, heating the main burner 57 at this time. Next, when the main burner 57 is heated to a predetermined temperature, the pump 54 is stopped to stop combustion in the auxiliary burner 53, and the valve body 62A is energized to 1 to close the secondary air port 62C and the combustion air is The entire amount of is guided to the primary air system path,
The pump 54 is started again to supply fuel to the vaporization chamber 56. As a result, the premixture supplied from the vaporization chamber 56 through the rectification chamber 58 to the main burner 57 becomes a relatively thin premixture in which the combustion air contained therein is greater than the stoichiometric air amount of the fuel. The premixture ejected from the main burner 57 is ignited by the igniter 64, and complete combustion occurs on the surface of the main burner 57. However, since the main burner 57 is heated by the combustion heat of the auxiliary burner 53, It became possible to easily ignite even a relatively thin premixture containing more than the amount of air. (For example, Japanese Unexamined Patent Publication No. 58-72807) Problems to be Solved by the Invention However, in the conventional example described above, two ignition devices are required, one for the main burner and one for the sub-burner, and after extinguishing the sub-burner, Since the main burner was ignited, there was a problem in that an odor was generated during extinguishing and ignition. moreover,
In order to perform low NOX e-firing as a combustion device, it is effective to use wire mesh, ceramic plates, etc. to perform full combustion with a small surface combustion load. At an air-fuel ratio at which normal combustion occurs even when sufficiently heated, there is a problem in that it is difficult to ignite using discharge ignition, which is a common ignition means.

The present invention solves such conventional problems, and has low NO.
The purpose of this invention is to improve the ignitability of a combustion device using a full-secondary combustion burner head that performs X-combustion.

Means for Solving the Problems and Description: In order to solve the problems, the combustion apparatus of the present invention divides the combustion air supplied from the combustion fan and supplies one part to the vaporization chamber through the primary air system path. and a tertiary air system that supplies a part of the combustion air to the exhaust gas passage while supplying the premixture from the vaporizing chamber to the rectifying chamber that sends the premixture from the vaporizing chamber to the full-primary combustion burner head via the secondary air system passage. The passage is branched from the secondary air system passage, and a switching valve is provided at the branch part to guide part of the combustion air to the rectifying chamber during steady combustion and to the exhaust gas passage during ignition.

According to the above-described configuration, the present invention allows a rich mixture of a small amount of combustion air and vaporized fuel gas, which is supplied to the vaporization chamber through the primary air system path at the time of ignition, to undergo total combustion via the rectification chamber. Since it is supplied to the burner head, it is easily ignited by the igniter, and carbon monoxide, which is likely to be generated due to air-starved combustion, is oxidized by the combustion air supplied to the exhaust gas passage via the switching valve and the tertiary air system path.・Since it is burned, harmful carbon monoxide is not emitted from the combustion device.

Also, during steady combustion after ignition, the switching valve is switched and a part of the combustion air is supplied to the rectifying chamber through the secondary air system path, so it mixes with the rich air-fuel mixture from the vaporization chamber. A relatively thin premixture with an optimal primary air ratio of 1 or more for combustion in the all-fire combustion burner head is formed in the rectifier chamber, and low NOx combustion is performed on the surface of the all-fire combustion burner head. It will be done.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

In FIG. 1, a pot-shaped vaporizing cylinder 2 in which a heater 1 is embedded is shown.
An air chamber main body 3 is disposed in a part of the frontage of the vaporizer cylinder 2, and a vaporization chamber 4 is defined inside the vaporization cylinder 2.

A fuel supply pipe 7 from a pump 6 connected to a fuel tank 5 and a primary air line 9 connected to a combustion fan 8 are opened in the side wall of the vaporization chamber 4 . On the other hand, on one side of the air chamber body 3,
An all-primary combustion burner head 14 (hereinafter referred to as burner head) composed of combustion made of wire mesh is provided, and an air chamber main body 3 is provided at the lower end of the burner head 14.
A partition plate 15 is disposed at the boundary between the air chamber body 3 and the burner head 14 to partition the inside of the air chamber body 3 and the burner head 14 into an air chamber 16 and a rectification chamber 17, respectively. At the top of the air chamber 16,
An air port 19 is opened, which is formed by a gap between the air-fuel mixture passage 18 that passes through the air chamber 16 from the vaporization chamber 4 to the rectification chamber 17, and the opening of the partition plate 15. A switching valve 20 is provided in the middle of the pipe to open a secondary air pipe 21 connected to the combustion fan 8, and the air chamber 1
6 and the secondary air pipe 21 form a secondary air system path 22. Furthermore, on the outer periphery of the burner head 14, the air chamber body 3, and the vaporization tube 2, there is a heat transmission tube 25 whose upper end is closed by an exhaust cap 24 across the exhaust gas passage 23, and a heat transmission tube 25 whose lower end is closed and which is exhausted near the vaporization tube 2. An outer cylinder 2B consisting of an exhaust pipe 27 with an opening 26 is arranged. An igniter 29 is attached to the exhaust cap 24. A tertiary air port 30 and a tertiary air chamber 31 are provided in one part of the exhaust pipe 27, and a tertiary air pipe 32 is arranged to connect the tertiary air chamber a1 and the switching valve 20. 30, the tertiary air chamber 31, and the tertiary air pipe 32 form a tertiary air system path a3.

In the above configuration, when the heater 1 is energized and the vaporizer cylinder 2 is heated to a predetermined temperature, the pump 6 and the combustion fan 8
operates, and one of the fuel and the separated combustion air is sent to the fuel supply pipe 7.
and is supplied to the vaporization chamber 4 via the primary air system path 9.

The fuel supplied to the vaporization chamber 4 is vaporized on the inner wall of the vaporization cylinder, mixed with a portion of the combustion air to form a rich mixture, and enters the rectification chamber 17 through the mixture passage 18 . At this time, the switching valve closes the secondary air line 22 as shown in FIG.
4, and is ignited by the igniter 29 and combusts. On the other hand, one part of the divided combustion air guided to the tertiary air system passage 33 by the switching valve 20 is ejected from the tertiary air port 30 into the exhaust gas passage 23 . Next, when the burner head 14 is ignited, the switching valve is switched, and the combustion air that has been supplied to the tertiary air system path 33 is supplied to the secondary air system path, and is passed through the air port 19 to the rectifying chamber 17. flows into.

As a result, the rich air-fuel mixture from the vaporization chamber 4 mixes with the combustion air from the air port 19, resulting in a relatively lean air-fuel mixture with an optimal primary air ratio of 1 or more for combustion in the burner head 14. It is burned on the surface of the combustion tube 10 of the burner head 14. Due to this combustion heat, the combustion tube 10 made of a wire mesh with a small heat capacity becomes red hot, and radiant heat is radiated through the heat transmission tube 25, and the high-temperature exhaust gas is discharged from the exhaust port 26 via the exhaust gas passage 23. However, at that time, it comes into contact with the outer circumferential wall of the vaporization cylinder 2 and heat is recovered to the vaporization cylinder 2.

In the formation and operation described above, when the burner head 14 is ignited, the amount of combustion air supplied to the vaporizing chamber 4 via the primary air line 9 is small, and the amount of combustion air supplied to the secondary air line 22 to the rectifying chamber 17 is small. Since there is no combustion air flowing through the burner head 1, the mixture remains a rich mixture with a primary air ratio of 1 or more.
4. Such a rich mixture can be easily ignited by a discharge igniter 29, which is a conventional ignition means, even if the burner head 14 is not sufficiently heated. However, since combustion in this state is a combustion in an air-deficient state, harmful carbon monoxide is generated due to incomplete combustion if left as is. Since the combustion air supplied to the passage 23 makes up for the lack of combustion air, the -carbon oxide is oxidized and burned to become harmless carbon dioxide and is discharged from the exhaust port 26. Next, after ignition, the switching valve 20 is switched, and the combustion air that was led to the tertiary air system path 33 at the time of ignition is passed through the secondary air system path 22 and into the rectifying chamber 17 from the air port 19. As the mixture flows in, the rich air-fuel mixture from the vaporization chamber 4 is diluted and becomes a relatively thin air-fuel mixture with an optimum primary air ratio of 1 or more for surface combustion on the surface of the combustion tube 10 of the burner head 14, resulting in combustion. Complete combustion occurs in the cylinder 10. Combustion in the combustion tube 10 is surface combustion with a small surface combustion load, so the flame temperature is low and NO is low.
X combustion can be performed. Furthermore, since the amount of combustion air flowing into the vaporization chamber 4 is small, there is no local cooling on the wall surface of the vaporization cylinder 2, and the temperature of the vaporization cylinder can be maintained at a high temperature, so that generation of 1 tar during fuel vaporization can be suppressed. In addition, during steady combustion, the air-fuel mixture temperature is kept relatively low by the combustion air that enters the straightening chamber 17 in a cooled state without passing through the heated vaporization chamber 4, so that backfire in the burner head 14 is prevented. It has the effect of preventing

Next, another embodiment of the present invention will be described using FIG. 2. The difference in FIG. 2 from the previous embodiment is that a tertiary air port 41 is opened in the exhaust cap 24, and a tertiary air chamber 42 is provided in the upper part of the exhaust cap 24.
In addition, a tertiary air pipe 43 is provided to connect the tertiary air chamber 42 and the switching valve 20, and a tertiary air system path 44 is formed by the tertiary air port 41, the tertiary air chamber 42, and the tertiary air pipe 43. In this case, the igniter 45 is attached to the base of the exhaust pipe 27. According to this configuration, at the time of ignition, combustion air is supplied to the exhaust gas from the upper end of the exhaust gas passage 23, that is, from the upstream side of the exhaust gas via the tertiary air system path 44, so that mixing with the exhaust gas is promoted. Highly effective in suppressing carbon monoxide during ignition.

Effects of the Invention As described above, the combustion apparatus of the present invention provides the following effects.

Combustion air used for combustion is divided, one part is supplied to the vaporization chamber via the primary air system path, and mixed with fuel and ejected from the burner head via the rectification chamber as a rich mixture.
During ignition, the other combustion air is supplied to the exhaust gas passage via the tertiary air system path using a switching valve, and during steady combustion, the switching valve is switched to supply combustion air to the rectification chamber via the secondary air system path. Therefore, it is easy to ignite at the burner head even with a discharge igniter, which is a normal ignition method, and it also prevents the emission of harmful carbon monoxide, and during steady combustion, low NOx combustion is performed at the burner head. There is an effect.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a combustion device showing a first embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of the second embodiment, and FIG. 3 is a vertical cross-sectional view of a conventional combustion device. It is. 4... Vaporization chamber, 8... Combustion fan, 9
...Primary air system path, 14...Full-fire combustion burner head, 20...Switching valve, 22...
...Secondary air system path, 2a...Exhaust gas path,
33 and 44...Tertiary air system path. Name of agent: Patent attorney Toshio Nakao and 1 other person m2
Figure 3

Claims (2)

[Claims] (1) A vaporization chamber that converts fuel into a premixture, a rectification chamber that rectifies the premixture from the vaporization chamber and sends it to the primary combustion burner head, and a vaporization chamber that converts a portion of the combustion air supplied from the combustion fan into the vaporization chamber. A primary air system path leads the remaining combustion air to the rectifying chamber, and a part of the combustion air is branched from the secondary air system path to the exhaust gas path from all primary combustion burner heads. and a tertiary air system path for supplying the combustion air, and a switching valve in the branch part that guides a part of the combustion air to the secondary air system path during steady combustion and to the tertiary air system path during ignition. (2) Claim 1 in which the amount of combustion air supplied to the vaporization chamber via the primary air system path is equal to or less than the theoretical air amount of the fuel.
Combustion device as described in section.