KR950013964B1 - Premix gas burner with flame control - Google Patents

Abstract

1. A gas burner for compact immersed tube, comprising a combustible air and gas premixture inlet discharging into a distribution chamber (2) which communicates through a metal flame stabilising grille (5) sensitive to thermal stresses, with a combustion chamber (6) in which the premixture is ignited by a lighting electrode (8) which is mounted through the metal flame stabilizing grille, the said burner being likewise equipped with flame monitoring means (12), the said burner being characterised in that it comprises as a flame monitoring means an ionizing electrode (12) mounted through the metal grille (5) and comprising a suitably insulated tip which extends straight into the combustion chamber (6).

Description

Premixed and Flame Regulating Gas Burners

1 is a schematic view of a gas burner according to the present invention.

2 is a reduced diagram of the burner assembly.

* Explanation of symbols for main parts of the drawings

2: distribution chamber 3: supply pipe

4: radial hole 5: flame stabilization grill

6: combustion chamber 7: wall

8: ignition rod 9, 10: cable

11 front metal flange 12 ionization electrode

10 ', 13 Tip 16: Combustible gas pipe

17 compressor 18 air duct

21: smoke exit

The present invention relates to a premixed and flame regulated gas burner.

The type burners are routinely used industrially.

The premixed and flame-regulated gas burners according to the invention are of a special type having an inlet for premixed air and combustible gas in a distribution chamber in which the mixture is injected through a flame stabilizer into a combustion chamber ignited by an ignition electrode. .

Various work has been done to solve the problems caused by the ignition and flame control of the burner as described above.

A reference is made to French patent application No. 8 309 468, "Premixed and flame-regulated gas burners used especially for submerged tube devices," filed June 8, 1983, in the name of the same applicant. .

The burner that is the object of the application and the industrial application of the burner according to the invention are closely related. In addition, there are certain problems that can be compared.

In the above-mentioned application, there is provided a device capable of observing the operation or combustion state of a flame by means of an observation cell device sensitive to ultraviolet rays.

The cell is arranged towards the bottom of the socket which extends behind the distribution chamber with respect to the flow direction of the gas mixture.

The small flow of air injected through the socket alone provides additional cooling of the cell. In this way, the flame observation cell is particularly reduced in high thermal stress in burners of this type operating in a submerged apparatus with a compact combustion chamber.

However, the above flame control with the cells arranged as above is not suitable in some cases.

The problem is in the case of backfire resulting from unstable flame conditions due to pressure fluctuations, and the flame propagates into the distribution chamber and not into the combustion chamber.

In practice, the position occupied by the cell in the rear of the distribution chamber allows continuous observation of the presence of a flame, thus causing the destruction of flame stability grilles and excessive thermal stresses that damage the burners. It allows for normal operation of the burner without detecting the abnormal position of the flame.

In addition, the necessary thermal protection that must be provided to the observation cell in relation to the compactness of the burner requires a fairly complex burner design that causes problems of rising production costs and standardization.

Other methods of controlling flame combustion and operating conditions have been invented and used. The method is to provide an ionizing electrode located at the combustion chamber level.

Such electrodes, placed in a space where the flames tend to develop under normal operating conditions, allow for the detection of actual combustion conditions and the effective location of the flames. This makes it possible to adjust the burner stop in case of excessive instability or abnormal position of the flame.

However, this form of ionizing electrode observation has been used so far for burners (ceramic plate burners, water heater burners) which prefer a completely different operating state than the premixed and flame stable grill type burners according to the invention. The water heater burner is very low power.

Therefore, no comparison is made in terms of thermal stress. There is no problem of flame instability resulting from significant pressure fluctuations caused by the combustion of high power flames in a compact environment.

In the case of ceramic plates, the flame is of the "backfire" type and develops inside the plate. The operating state and the field of application differ from the burners according to the invention.

In order to avoid disturbing the flow of the gas mixture and not to deteriorate the operation of the burner, when the ionizing electrode is provided as an ignition electrode, the ionizing electrode has a body and head connected to the power supply, so that only the tip penetrates into the mixture. It is arranged to be located away from the flow of the mixture.

In contrast, in the present invention, providing an ionizing electrode and an ignition electrode directly to the center of the gas mixture on the flame stabilizer of the burner, in which the problem of flame instability is particularly difficult to solve, has the potential to adversely affect the satisfactory operation of the burner. It was observed that it did not cause.

Given the many advantages described above provided by the ionization electrode at the flame observation level, the present invention is equipped with an ionization electrode mounted across the flame stabilizer grill in the same way as the ignition electrode, and is provided with a grille. A mixed and flame-regulated gas burner is provided, wherein the two electrodes are arranged with insulated tips extending into the combustion chamber and vertically bent with respect to the grille, and also with heads respectively connected to a power source through the distribution chamber. It is.

In this way, satisfactory observation of the flame position and combustion state can be ensured and it is possible to avoid any damage arising from the abrupt turn-off of the burner and flame instability or backfire during the combustion process.

The invention applies to the use of burners applied to compact water immersed tubes and combustion chamber assemblies.

The features and advantages of the present invention will become more apparent by reference to the following accompanying drawings.

Referring first to FIG. 1, the burner 1 has a distribution chamber 2 through which the air / combustible gas premix arrives via a supply pipe 3 which injects generally into the chamber 2 through a radial hole 4. Equipped with.

The distribution chamber 2, which is generally cylindrical in the shape of a circular cross section, is blocked by the metal flame stabilizer grill 5. The grill, which is relatively thermally stress sensitive (compared to the ceramic plates) under the particular operating conditions of the burner, is of the type described in the aforementioned French Patent Application No. 8 309 468.

More particularly, the orifice of suitable diameter and distribution is provided at the inlet of the combustion chamber 6 for the stability and satisfactory attachment of the flame. On the rear side, the tank constituting the distribution chamber 2 is blocked by the wall 7.

The letters AV and AR shown in FIG. 1 are the "front" and "rear" of the burner, referring to the circulation of the combustible mixture in the burner as schematically shown by the arrows.

As explained, the burner is ignited by an electrode 8 provided with an insulated high voltage cable, shown by (9), the ignition being an adjacent wall of the grille 5 and the bent tip 10 'of the ignition electrode. Or by the flame between the front metal flanges 11 where the grille 5 is fixed and grounded by a tank constituting the distribution chamber 2.

In order to observe the satisfactory function of the burner, ie not only the position of the flame, but also the combustion state of the flame, which develops especially in the combustion chamber, the ionizing electrode 12 is adjacent to the tip 13 and the grille 5 of the electrode 12. An insulated voltage cable 10 is provided which detects a flame development occurring between the two.

The tip 13 of the ionizing electrode 12 is generally straight as described and parallel to the flow direction of the gas mixture.

The two electrodes 8 and 12 are mounted generally parallel to the direction of flow of the gas mixture in a way towards the center across the flame stabilizer grille 5 and with the respective tips 10 and 13 extending into the combustion chamber. have.

The power supply cables 9 and 10 of the electrode extend into the distribution chamber 2 across the wall in a way that can withstand the operating pressures at 14 and 15 as described. Sealing is accomplished by compression packing plugs.

There is a visual flame observation device 23 toward the rear of the distribution chamber 2 and toward the bottom of the socket 22 which is injected into the chamber. The observation device 23 is installed to be protected from thermal stress.

Referring to FIG. 2, the burner is supplied with combustible gas through pipe 16 and the premix is supplied to pipe 3 in a generally theoretical state. The air necessary for combustion is supplied through the main air duct 18 by a fan or a compressor 17. The fan is powered via 24.

As in FIG. 2, the burner described above enables the supply of a device with a submerged tube specially made (or with a combustion chamber which can be submerged in the liquid 19 to be heated).

In FIG. 2, reference numeral 20 denotes a tube immersed in water for discharging the combustion products exiting the combustion chamber 6 and directed to the smoke outlet. The device for turning the burner on and off is not shown in the figure.

However, stopping the burner is performed by the ionizing electrode at the moment it senses that the ionizing electrode is free of flame.

Claims (4)

In a compact water consisting of an inlet of a combustible gas premix which is injected into a distribution chamber in which the premix is ignited by means of an ignition electrode mounted through a metal flame stabilizer grill and a chamber in communication through a thermal stress sensitive metal flame stabilizer. A gas burner for a submerged tube, the burner further comprising a flame observation device comprising an ionizing electrode rod mounted through the metal grill and having an insulating tip extending into the combustion chamber. The gas burner of claim 1, wherein the ignition electrode comprises an insulating tip extending into the combustion chamber and bent in the direction of the grille. The gas burner according to claim 1, wherein the ignition electrode and the ionization electrode are mounted toward the center of the flame stabilizer grill in parallel to the flow direction of the combustible gas mixture circulated from the distribution chamber to the combustion chamber. The gas burner according to claim 1, wherein the ignition electrode and the ionization electrode are respectively connected to an electric supply cable passing through the distribution chamber by the head.

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