DE3105540A1 - METHOD FOR IGNITIONING A DUST POWER BURNER DESIGNED AS A CIRCULAR BURNER WITH A CENTRAL DUST BURNER ARRANGED IN THE POWER BURNER WITH PNEUMATIC HOLDING OF THE IGNITION FLAME AND BURNER ARRANGEMENT FOR CARRYING OUT THE PROCEDURE - Google Patents

Description

Process for igniting a dust power burner designed as a round burner with a centralized power burner arranged dust pilot burner with pneumatic holding of the pilot dust flame and burner arrangement for implementation of the procedure.

The invention relates to a method for igniting a dust power burner designed as a round burner, in particular pulverized coal power burner, with a centrally located power burner, also as a round burner trained dust pilot burner, in particular pulverized coal pilot burner, where the ignition energy for the power burner flame from the pilot dust flame ignited centrally in the internal return flow area of the power burner is introduced and in which the pilot dust flame is stabilized.

The task of the dust pilot burner is to initiate the safe ignition of the power burner and, if necessary as long as the conditions necessary for self-stabilization are not yet met or as long as the fuel of the power burner is not able to reliably ignite even during the To ensure continuous operation. This may be necessary if the fuel is not ignitable enough, if its calorific value does not lead to a sufficiently hot flame due to a high proportion of ballast and / or if the fuel has not been sufficiently prepared for safe combustion.

It is known to use pilot burners to ignite pulverized coal flames, which are used as pilot fuel or oil Need gas. Gas and oil are relatively flammable fuels, so that to stabilize the pilot flame itself only sufficient mixing with the;

same burner amount of air fed and the excess _; ■

Exceeding the initial temperature on the F'l; \ mm «nwur £« .l necessary is. The ignition energy required to reach the ignition temperature normally supplies a downstream of the back vortex standing at the burner mouth, the hot gases ■ returns from the pilot flame along the beam axis. ; Combustion of oil and gas occurs quite quickly. A relatively small back vertebral zone, as it is caused by so-called. Forcing a flame holder or impeller is sufficient.

Usually the pilot burner is used in a round burner arranged in a central tube, which also ensures the air supply. The pilot burner itself usually consists of an oil or gas lance, an electrical,

tric or also gas-supplied igniter and;

a flame monitor. This pilot burner is surrounded '.-. from the coal dust pipe of the power burner.

The secondary air flows around the outside, also guided in a pipe, into the combustion room. D.lobps out-r « ⁵ ο.Μ ·: πιΐ -därluftrohr is conical towards the combustion chamber to one

Burner muffle expanded. This burner muffle guides the secondary air jet because of the swirl imposed on it flows along the wall of the muffle into the furnace in a funnel shape and after leaving the muffle mixed with the gases in the furnace. Inside the secondary air jet there is a negative pressure zone that leads to Formation of the jerk vortex necessary for flame stabilization leads. Besides, this back vortex is pushing that Coal dust-primary air mixture emerging from the coal dust nozzle of the power burner into the funnel-shaped outflowing secondary air jet. Before this happens, however, the coal dust must be ignited by the hot flue gases sucked back from the burning flame. Find the burning coal particles after entering the secondary air flow, the combustion necessary oxygen.

From the D-AS 2933o4o is a method for igniting a Known coal dust round burner flame, in which the ignition energy is centered in the internal return flow area of the power burner flame is introduced by an ignited dust pilot flame, the pilot flame with a Fuel, in particular coal dust, is operated, which differs from the coal dust used as the main fuel differs in grain size and / or consistency.

A corresponding burner arrangement with a pilot burner arranged in the power burner is shown in FIG DE-AS 2933o6o known.

The structure of a dust pilot burner in the central cross section of a dust power burner, in particular in one The core tube of a power burner can, of course, be based on the same construction principles as those for the power burners are used. In the known burner arrangement, the pilot burner has its own conically widening burner muffle inside the core tube.

Furthermore, it is often assumed that as much air should penetrate the coal dust pilot burner as for complete combustion of the abandoned coal is necessary is. Compared to a gas-oil lance, the larger cross-section for the primary air-coal dust mixture of the pilot burner, the cross-section for the secondary air required for complete combustion of the ignition coal dust and the burner muffle, which is seen as absolutely necessary in extension of the secondary air pipe lead together to a large outer diameter of the pilot burner; this is particularly disadvantageous when retrofitting existing power burners, since then major modifications must be made. Also at neu su erstolLondon

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Boiler systems can be affected by the large increase in the the central cross-section required to accommodate the pilot burner the known burner geometry are sensitively disturbed, so that up to now ' as yet unknown difficulties.

It is the object of the present invention to provide a method where the stabilization of the pilot flame can take place without a special component.

This object is achieved in that the stabilization of the ignition dust flame by impressing a strong Swirl and a high speed on the secondary air flow of the dust pilot burner takes place, where the Secondary air of the dust pilot burner and the supporting air of the ignition dust are only part of the total Combustion · Supply the necessary air to the pilot flame.

As previously known, the primary air / ignition dust mixture is used fed to the pilot burner in a central "tube, in the middle of which the igniter is placed, e.g. in the form a small propane gas burner that can be ignited electrically or an electric igniter in the form of a glow rod or an electric arc. The primary air / ignition dust mixture exits the primary air pipe at the lowest possible speed.

LJm the primary air pipe, also called the ignition dust pipe, i: ¹ .1. the secondary air cross-section arranged. The air exits from a narrow cross-section of the ring at high speed. Their amount is only a fraction of the amount of air that is required for complete combustion of the ignition dust. In addition, a controllable strong swirl is impressed on this secondary air flow.

During or after the dissolution of this ring, which is ring-shaped in cross-section, the high impulse leads to -. 'In ^ v i nhmu; i '"' n Mixing with the environment, ie with the primary air emerging from the primary air cross-section of the power burner at relatively low speed during the ZUnd -.- n and with the air emerging from the secondary air cross-section of the power burner, the quantity and speed of which are adapted to the requirements of the ignition In this way it is ensured that the ignition dust, in particular ignition coal dust, finds the air necessary for combustion after ignition.

The strong swirl of the secondary air jet from the pilot burner causes a funnel-shaped expansion of the ring jet even without a fixed burner muffle like her in the DE-AS 2933o4o and DE-AS 2933o6o is considered absolutely necessary, and a backscatter in the beam axis. Even with a relatively small ignition

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burner cross-section, the ignition energy from the burning flame is returned to the flame root along the beam axis. ·

The swirl and the speed of the secondary air jet of the pilot burner must have such a strong impulse that the funnel-shaped "pneumatic burner muffle" is also retained when the primary air cross-section of the power burner is started up with a fuel dust-air mixture, in particular a coal dust-air mixture, is applied. The large mixing energy of the pilot burner secondary air jet is improved In addition, by mixing the pilot flame with the flame of the power burner, if the pilot burner in poor combustion conditions the main burner runs continuously to support its ignition.

The invention is not only directed to a method for igniting a dust power burner designed as a round burner with a dust pilot burner arranged centrally in the • power burner, but also directed towards a burner arrangement to carry out the process. The invention is based on the burner arrangement according to FIG DE-AS;? 933o6o from. According to the invention in this burner arrangement provided that the secondary air pipe opens straight-cylindrical towards the combustion chamber and the in swirl vane ring arranged on it near the air

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outlet cross-section is arranged. Otherwise the secondary air would be large in the narrow ring cross-section Part of the swirl energy is lost due to the friction of the air flowing at high speed.

The method according to the invention is expediently carried out in such a way that the pilot flame with an Luftzalil Im Range from o, 2-o, 8 is operated.

It is also advantageous if the axial speed component the combustion air for the pilot dust flame is greater than that for the power burner flame is held.

It is also desirable if the twist and / or speed can be adjusted.

Further subclaims relate advantageously to Ausist a L-tung the device according to the invention.

The invention will now be explained in more detail with reference to the attached figure, which shows a preferred embodiment the burner assembly shows.

In the secondary air supply (1) of a power burner is a twist vane ring (2) vorg ^ seh ^ n, whose Γ rn 1 "1 blades are adjustable. The Dm I! ..; ι · ΐι \ nf> -1 l.r.-m: ·, (.'ι

is arranged in the secondary air pipe (not designated further) of the secondary air supply. A burner muffle (3) connects to 'the secondary air pipe'. The fuel-air mixture supply of the power burner is labeled (4) 'and the fuel-air mixture supply of the pilot burner is labeled (5). The power dust pipe (4 ') and the ignition dust pipe (5 ¹ ) are particularly emphasized. Secondary air is fed to the pilot burner via a connection piece (6) and swirl blades (8) are arranged in a ring in the secondary air cross-section (7) just before the outlet. Arranged centrally in the interior of the primary air cross-section of the pilot burner is an igniter (9) which has an air supply (lo) and a gas supply (11). The burner arrangement is - as indicated schematically - arranged in the wall (12) of a combustion chamber. In the embodiment shown, the central cross section of the power burner is delimited by a secondary air pipe (7 ¹ ) delimiting the secondary cross section (7) of the pilot burner.

But it is also possible that the inner limitation of the fuel / air mixture supply of the power burner is formed by a central pipe into which the secondary air pipe (7 ¹ ) is inserted; this is particularly the case when retrofitting burner assemblies with a core air pipe. Basically it just depends on

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that the corresponding cross-sections are designed for secondary air and primary air-fuel mixture. The ignition dust pipe (5 ¹ ) is centered by means of the swirl vane ring (8) from the secondary air pipe (7 '). The swirl blades of the swirl blade ring (8) are expediently arranged in such a way that the swirl strength can be changed in order to be able to adapt the burner to the different operating conditions.

With the use of coal dust as fuel it can ever according to the quality of the available ignition coal dust (quality features are: grinding, the ballast content and the gas content) it may be useful to impress a twist on the primary air ignition carbon as well. this would cause the dust to mix more quickly with the secondary air. When using ignition carbon dust with poor ignition properties, it can be particularly useful to use the secondary air swirl of the pilot burner set particularly strong.

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Claims (9)

Method for igniting a circular burner Dust performance burner, with a central in the performance burner arranged dust pilot burner with pneumatic holding of the pilot dust flame and burner arrangement for implementation of the procedure. Expectations l. \ Method for igniting a dust power burner designed as a circular burner, in particular a coal dust power burner with centrally arranged in the power burner also designed as circular burners Dust pilot burners, especially coal dust pilot burners, in which the ignition energy is used for power consumption from the central in the internal backpack area of the power burner ignited pilot dust flame is introduced and in which the pilot dust flame is stabilized, characterized in that the ignition dust flame is stabilized by applying a strong twist and a high velocity on the secondary airflow of the dust pilot burner takes place, whereby the secondary air of the dust pilot burner and the carrying air of the Ignition dust only a part of the complete Supply the necessary air for combustion. 2. The method according to claim 1, characterized in that the pilot flame with a Air ratio in the range of 0.2-0.8 is drifted. - 2 3. The method according to claim 1 or 2, 'characterized in that the axial speed component the combustion air for the ignition .! is kept larger than that of the lead ■ stungsburner. 4. The method according to any one of claims 1-3, characterized in that the twist and / or the speed are kept adjustable. 5. Burner arrangement, consisting of a dust-power burner with a central cross-section, a power dust pipe surrounding the central cross-section and a the secondary air pipe surrounding the power dust pipe with a swirl vane ring arranged at the air inlet and from a dust pilot burner arranged concentrically in the central cross-section of the power burner with a centrally arranged detonator, one concentric to the igniter arranged ignition dust tube and a secondary air duct surrounding the ignition dust tube with swirl vane ring, characterized in that the secondary air ^{pipe (7 1} ) opens in a straight line towards the combustion chamber and its swirl vane ring (8) is arranged in the vicinity of the Luffaui outlet cross section. ■ - 3 - 6. burner arrangement according to claim 5, characterized in that the central cross-section of the power burner is formed by a central tube and the secondary air pipe is pushed into the central pipe is. 7. burner arrangement according to claim 7, characterized _{in that the} secondary air pipe (7 ') delimits the central cross-section. 8. Burner arrangement according to one of claims 5 or 7, characterized in that the swirl vane ring (8) is adjustable ^{in the secondary air pipe (7 1).} 9. Burner arrangement according to one of claims 5-8, characterized in that a swirl vane ring is also arranged ^{in the ignition dust tube (5 1).} lo. Burner arrangement according to one of claims 5-9, characterized in that the swirl vane ring (8) of the secondary air pipe (7) serves to center ^{the ignition dust pipe (5 1).}