WO1988008503A1

WO1988008503A1 - Process and device for combustion of fuel

Info

Publication number: WO1988008503A1
Application number: PCT/EP1988/000364
Authority: WO
Inventors: Michael G. May
Original assignee: May Michael G
Priority date: 1987-04-30
Filing date: 1988-04-29
Publication date: 1988-11-03
Also published as: EP0312562A1; AU1688488A

Abstract

In a process and device for combustion of fuel, a primary gas containing oxygen is fed into a fire chamber (12). The primary gas is introduced in several jets through nozzles (22) into a combustion chamber (20) of a gas channel (15). Fuel is also introduced into the said combustion chamber. In the combustion chamber of the gas channel, the primary gas jets generate counter-jets of the burning gas-fuel mixture which are directed against a baffle (16).

Description

Method and device for burning fuel

The invention relates to a method for burning fuel and a device for carrying out this method

The invention relates to the combustion of fuel in a combustion chamber. This combustion can serve different purposes, for example the heating of heat transfer medium or the operation of a gas turbine or other purposes. The device in the combustion chamber of which the fuel is burned can be a boiler, a combustion chamber, any heat generator or the like. The combustion can preferably serve to generate usable heat, in particular also heat that can be used industrially. E.g. , the burning of the fuel ^'s are of heat generation in power plants or for driving turbines, or the like., the heating media of any kind, such as water, air or the like. or other purposes. For example, it can also be used to heat buildings or the like, and also numerous others z -

Have application areas. It can preferably be used to generate high heat output, but the method and the device according to the invention are also advantageous at low and medium heat outputs.

With such methods and devices, it is desirable that the flue gases contain as little pollutants as possible in order to keep the pollutant emissions as low as possible. It is also an often unsatisfactorily solved problem to keep the flame lit in the combustion chamber stable. To achieve this, it is known to arrange so-called flame holders in the combustion chamber at a distance from its wall, which form mechanical obstacles placed in the flame path, such as wires, rods, disks, etc. However, such flame holders can adversely affect the combustion process and increase pollutant emissions and often do not satisfy for other reasons.

It is therefore an object of the invention to provide a method of the type mentioned in the preamble of claim 1, in which the flame control is achieved with a simultaneous reduction in pollutant emissions.

This object is achieved by the method specified in claim 1. A device according to the invention for performing this method is described in claim 22. By means of the invention it is possible to achieve safe flame retention of the ignited flame in the gas channel combustion chamber at the Fangwaπd, so that no additional flame holder is required. At the same time, this trap wall forms the boundary wall of the combustion chamber on the inlet side and thus does not constitute an obstacle to flow in the combustion chamber, which has a favorable effect on the combustion process. Due to the backflow generated by primary gas jets in the combustion chamber of the gas channel towards the trap wall, the flame roots can stick to or near this trap wall and this results in extremely stable and thus continuous combustion. At the same time, reduction of harmful flue gas components is achieved, so that this method also makes it possible to keep the pollutant emissions particularly low.

The combustion taking place in the method according to the invention can be referred to as continuous combustion of fuel, since the combustion of the fuel in each case continues as long as desired or required continuously until the fuel supply is stopped again by shutting off the fuel supply, the supply of oxygen-containing substances also being carried out Gas in the combustion chamber can also be stopped. A pause time of any length can then follow, during which, however, at least one pilot flame may continue to burn to re-ignite the flame or flames used to generate heat, unless other means of ignition are provided. In the case of heat-generating heat generators, such as boilers, boilers, ovens or the like, but also in other devices according to the invention, it is often or must be provided to control or regulate the heat generation by continuously burning the fuel, which is used to generate the respective heat to let it last for more or less long and to take breaks in between, during which fuel supply which serves the heat generating Brenn¬ _^ - optionally with the exception of the fuel supply for at least one pilot flame - is interrupted, so that in the relevant combustion chamber, no heat, or at most only low multiple of one or

10 pilot lights generated heat is generated. E.g. it is common in boilers of heating systems for buildings or the like to switch the supply of fuel and combustion air for power control alternately on and off. When the fuel supply is switched on, the amount of fuel supplied / time is often constant Xo

In the invention, this is of course also possible accordingly, the device according to the invention also being a boiler, but also one

20 other device for burning fuel. Alternatively or additionally, if desired, power-modulated operation is also possible in the method and the device according to the invention. Power-modulated operation means that

25 Fuel supply and possibly also the supply of oxygen-containing gas - possibly with the exception of the fuel and air supply for at least one pilot flame - for controlling or regulating the generation of heat, i.e. to values of different sizes continuously or gradually 0

35 to be able to adjust. One can then provide continuous combustion of fuel with variable fuel quantity / time in uninterrupted continuous operation and, if desired, alternate the continuous combustion of the fuel with additional power control or regulation with pause times during which the fuel supply used for heat generation is used _. and possibly also the supply of oxygen-containing gas and thus the heat generation is interrupted, again possibly with the exception of the supply of fuel and air for at least one pilot flame.

The trap wall forms a transverse wall in the gas duct. Since it causes flame retention, it can also be referred to as the flame holder wall. It also forms the upstream end wall of the combustion chamber in the gas duct, in which the flame begins.

The combustion chamber of the gas channel can preferably only form a partial area of the combustion chamber in which it is provided that the combustion chamber of the gas channel opens out into the rest of the combustion chamber. However, it is also possible to allow the entire combustion to take place in the combustion chamber of the gas duct and, for example, to connect the outlet of the gas duct directly to a flue gas outlet. - to β ^~ is particularly favorable, however, when the combustion chamber of the gas passage preferably forming only a small area, only a relatively small portion of the entire combustion chamber. The flue gases that form in the combustion chamber can be extracted from it through a flue gas outlet or in some other way.

Although in some cases it is sufficient if there is only at least one passage for flowable medium between one of the existing primary gas nozzles and the trap wall, preferably between at least two primary gas nozzles and the trap wall, particularly expediently between all primary gas nozzles and the Catch wall openings for flowable medium may be provided.

The primary gas jets flow from the primary gas nozzles into the combustion chamber of the gas channel at or near the trap wall, or preferably at high to very high flow rates. The primary gas jets have an intense effect _. Backflows of the gas in combustion towards the trap wall, the primary gas jets flowing into the combustion chamber at a height of the trap wall or so close to the trap wall that the trap wall keeps the flames ignited in the combustion chamber by burning the fuel in the combustion chamber caused

Flame in connection with the back flows generated by the primary gas jets in the combustion chamber.

Fuel is also introduced into the combustion chamber. It can be the entire fuel to be burned or part of this fuel. If not all of the fuel is introduced into this combustion chamber, then it can preferably be the largest part of the total fuel to be burned in the combustion chamber -? - act and the remaining part of the fuel can then be burned outside the combustion chamber of the gas channel in the rest of the combustion chamber. E.g. At least one gas burner can be arranged outside the gas duct in the combustion chamber to generate additional heat during extreme load operation.

It when the primary gas jets are blown into the combustion chamber of the gas channel so that they are in a through the

Catch wall separated from the gas channel combustion chamber can cause pressure reduction. This pressure reduction in such an antechamber can then be used to suck any media into this antechamber, which medium can then also be conveyed from this antechamber by the action of the primary gas jets into the combustion chamber of the gas channel. This medium can preferably be flue gas drawn in from the combustion chamber. However, other media can also be used alone or in combination with flue gas. E.g. may be the medium serving as a fuel containing coal dust, preferably inert gas, so that coal dust is thereby introduced into the combustion chamber for its combustion. Other media are also suitable for being sucked into the combustion chamber due to the action of the primary gas jets, for example, favoring the combustion or in any other desired manner. influencing media, etc. It is often also expedient to convey this medium to the openings between the primary gas nozzles and the trap wall in a preferably adjustable volume flow through at least one turbo machine, for example a blower or a fan, so that the primary gas jets do not emit it suck in or only support its promotion into the combustion chamber.

The invention makes it possible due to the good flame retardancy by means of the trap that such medium in the amount / time of the primary gas relatively large amount / time of the Primary gas jets sucked into the combustion chamber of the gas channel or in some other way into the combustion chamber through the passages between the primary gases and the

Catch wall can be initiated in any other way. If this medium is recirculated flue gas, this allows particularly high dilution of the primary gas by flue gas without impairing the flame stability, so that extremely low pollutant emissions can be achieved.

The length, thickness, etc. of the flame can also be influenced by the combustion chamber of the gas channel, the flue gas recirculation, the primary gas jets and the backflows generated by them and optimally adapt the combustion chamber or design the combustion chamber in the desired manner.

The number of primary gas jets blown into the combustion chamber of the gas channel can be two or, preferably, more than two. Likewise, a plurality of openings can preferably be arranged in the trap wall, through which primary gas jets flow or which protrude into or penetrate the primary gas nozzles.

The primary gas nozzles, which blow the primary gas jets into the combustion chamber of the gas channel, can be arranged with blowing directions that are axially parallel to one another or can also have another arrangement. In many cases it is expedient to arrange them so that the blowing directions of at least two primary gas nozzles do not run parallel to one another, but rather are inclined to one another. In many cases it is useful if the blowing directions are at least a part of the Primary gas nozzles diverge or converge to one another. These primary gas nozzles can also be arranged in such a way that they produce a vortex flow circulating about the longitudinal axes of the preferably straight gas channel in the combustion chamber of the gas channel by being arranged at an appropriate angle.

The peripheral wall of the gas channel can preferably be designed as a tube, preferably as a straight tube. This tube can be approximately circular cylindrical, but other designs are also suitable.

If it is provided that the primary gas jets are blown into the combustion chamber through openings in the trap wall, the clear cross sections of which are larger, preferably considerably larger than the cross sections of the primary gas jets in height, it can preferably be provided that through each such opening the A single primary gas jet is blown into the combustion chamber. However, it is also possible to inject several parallel and / or converging and / or diverging primary gas jets into the combustion chamber through such an opening, for example by using a single primary gas nozzle which has a corresponding plurality of openings for blowing out primary gas jets, or by means of several primary gas nozzles.

The gas channel can preferably be at least two inches for blowing out the primary gas jets ΛO

have primary gas nozzles arranged at lateral distances from one another.

In many cases it can be expediently provided that the openings assigned to the primary gas nozzles are arranged in the trap wall relative to the primary gas nozzles in such a way that the primary gas nozzles protrude into these openings or penetrate these openings and protrude somewhat beyond them into the combustion chamber, with between the Edges of these openings and the primary gas nozzles as passages are still clear spaces, preferably ring gaps, which form flow openings for medium, which preferably consists of a gas channel antechamber separated from the combustion chamber of the gas channel by the trap wall by means of the

Primary gas jets can be sucked into the combustion chamber.

The Rückströmungeπ generated by the primary gas jets in the combustion chamber of the gas channel also have ien advantage that the flame length is shortened ^" , which enables correspondingly shorter or smaller design of the combustion chamber with all the advantages resulting therefrom.

It when the openings of the trap wall, through which primary gas jets flow or into which primary gas jets are used to blow out the primary gas jets at a distance from their walls, is particularly favorable if they taper in the downstream direction.

The fuel can be fed into the combustion chamber in any suitable manner. E.g. can preferably at least one fuel supply nozzle, preferably an atomizer nozzle for fuel, can be arranged in the long center of the gas channel, or there can be several such nozzles for fuel, which can preferably be inserted into the trap wall and introduce atomized liquid fuel into the combustion chamber in suitable directions , such as injecting or the like., such as light, medium or heavy heating oil, liquid hydrocarbons or the like. However, gaseous fuels or gases containing fuel particles such as coal dust or the like can also be provided, and in this case it is particularly expedient to design the trap wall as a double wall or cavity wall. The cavity or cavities formed by this double wall can then be provided as a flow channel or channels for introducing the gaseous fuel or the fuel particles carried by gas into the combustion chamber. This introduction can be provided directly into the openings of the trap wall for the primary gas jets or the primary gas nozzles and / or away from these openings through one or more separate openings of the trap wall. All of this is also particularly favorable in terms of flow and combustion technology.

The flame can be ignited in any suitable manner, for example by a continuously lit pilot flame.

The primary gas becomes the primary gas nozzles under pressure promoted. This can preferably be done by means of at least one blower. It is particularly expedient if the medium sucked in from an antechamber by the action of the primary gas jets is accelerated in these openings when flowing through the relevant openings of the trap wall, which can take place by correspondingly tapering these openings in the downstream direction.

The primary gas jets can preferably be blown into the combustion chamber next to one another at relatively large intervals.

The invention also enables combustion of the fuel with a blue flame, which is particularly favorable.

Exemplary embodiments of the invention are shown in the drawing. Show it:

1A is a schematic sectional view of a device for burning fuel according to an embodiment of the invention,

1B is an enlarged section of the device of FIG. 1A,

Own 2 shows a partial section through FIG. 1A, seen along section line 2-2 in an enlarged view, -

FIG. 1 shows a detail from a device for burning fuel in a longitudinal section according to a further exemplary embodiment of the invention,

FIG. 1 shows a top view of the outlet mouth of a primary gas nozzle according to one exemplary embodiment,

FIG. 1 shows a section of a gas channel in a longitudinal section according to a further exemplary embodiment of the invention,

6 is a partial plan view of a hollow catch wall according to a further embodiment of the invention,

Fig. A section through the catch wall of Fig. 6, seen along the section line 7-7.

The device 10 for combusting fuel shown in FIG. 1A can be a boiler, a combustion chamber or the like. It has a housing 11, in which there is a large combustion chamber 12, to which a flue gas outlet 13 'connects at the top, which can, for example, continue to a chimney, chimney or the like.

The combustion chamber 12 is penetrated in the vicinity of its upper end by a tube 13 or a plurality of tubes through which a preferably liquid heat transfer fluid is passed for heating it. This heat transfer fluid can be, for example, water, oil, steam or the like. - Λ A -

A horizontal gas channel 15 projects into the lower half of the combustion chamber 12 at a distance above its base 14, the circumferential wall of which is formed by a straight, preferably circular-cylindrical tube 17. This tube 17 is divided within the combustion chamber 12 by two spaced vertical partition walls 16 and 25 into a pressure chamber 19, an intermediate space 30 and a combustion chamber 20. The intermediate wall 16 forms a catch wall which separates the intermediate space 30 which forms an antechamber in front of the combustion chamber 20 from this combustion chamber 20. The combustion chamber 20 is a partial area of the combustion chamber 12 and the area outside the combustion chamber 20 is designated by 36.

A blower 21 is connected to the upstream end of the pressure chamber 19 and serves to suck in primary gas containing oxygen, which may preferably be air, and conveys it into the pressure chamber 19.

From this pressure chamber 19, this primary gas can flow into the combustion chamber 20 through a plurality of primary gas nozzles 22 which are fixedly arranged in the preferably flat intermediate wall 25 at lateral distances from one another. In this exemplary embodiment, a ring of a total of six primary gas nozzles 22 is provided, which are arranged around the longitudinal axis of the straight gas channel 15 at the same central angle distances from one another and at the same radial distances from this longitudinal axis as shown in FIG. 2.

The catching wall 16 is solid here with an approximately constant thickness - for example it can be formed by a sheet metal - and runs perpendicular to the longitudinal axis of the gas channel 15 and is essentially flat, but can also have a different shape, for example it can be completely flat, slightly curved be or have any other suitable training, e.g. - AS

often also be a hollow wall.

The pressure chamber 19 is connected to the antechamber 25 and the combustion chamber 20 in a gas-conducting manner through the primary gas nozzles 22. The circumferential wall of the gas channel 15 formed by the tube 17 is closed in this exemplary embodiment against the area 36 of the combustion chamber 12 surrounding it and outside of the housing 11 against the ambient atmosphere 38, that is to say that the PxOhr 17 has no openings on its circumference through which gas 36 could flow into the gas duct 15 from the area 36 of the fire room ^" or from the ambient atmosphere 38 of the housing 11.

In the pressure chamber 1-9 of the gas duct 15, a fuel line 28 leads through the wall of the tube 17, which is connected to a fuel atomizing nozzle 23 which is fixedly inserted in the intermediate wall 25 and in the collecting wall 16 in the center and coaxially with them. This nozzle 23 projects with its head a little bit into the combustion chamber 20 of the

Gas passage 15 via the trap wall 16 also into and ^¬ se nozzle 23 protrudes with its head a small distance into the combustion chamber 20 of the gas passage 15 via the trap wall 16 also in, and this nozzle 23 includes atomization means for atomizing the injected at high pressure in it liquid Fuel on. As indicated by the dashed jets, the atomized fuel is sprayed in jets directed obliquely to the longitudinal axis of the straight gas channel 15 in the direction of the primary gas jets blown into the combustion chamber 20 from the primary gas nozzles 22. An ignition or pilot flame, not shown, can ignite the fuel-primary gas mixture in the combustion chamber and then there is continuous combustion of the fuel introduced through the nozzle 23 into the space 20 until the fuel supply to the nozzle 23, for example for regulating or controlling the thermal output of the device 10, is temporarily interrupted or to switch it off completely, where appropriate, the fan 21 can also be switched off. If the flame which can be generated by supplying fuel by means of the nozzle 23 is ignited by means of at least one pilot flame, this pilot flame can of course continue to burn during the interruption of the supply of fuel to the nozzle 23 or, if the boiler 10 is to be completely shut down, the at least one can also be used Pilot light should be switched off. The fuel supply to the nozzle 23 can be constant when it is switched on, or variable fuel supply can also be provided.

It is also It is possible to design the fuel nozzle 23 as a two-substance nozzle, i.e., to pass through it the atomizing of the liquid fuel in a normally relatively small amount relative to the primary gas. This secondary gas can preferably also be air and, in addition to the oxygen introduced into the combustion chamber by the primary gas, also enter oxygen into it, which then also participates in the combustion.

The fuel atomizing nozzle 23 is only schematically Darge and can be of any suitable type, for example a Dral 1 atomizing nozzle or have other suitable training. Instead of such an atomizing nozzle, several atomizing nozzles may also be arranged on the collecting wall 16 in the case of larger outputs. - AI - 1

To an opening in the U wall of the anteroom 30, a feed line 18 is connected, which serves to introduce flowable medium into this anteroom 30, _r - from which this medium i'_ ⁿ . The combustion chamber 20 together with b from the primary gas nozzles 22 can flow out flowing primary gas jets. For this purpose, are provided ^"• ⁿ the trap wall 16 openings 29, the trumpet-shaped erjüngen from their outlet openings 32 in the upstream direction to its stro upstream inlet orifices 33, as illustrated. These openings 29 may Rotati onssymmetri see his or other suitable Have a shape or, in a manner not shown, can also be formed only by holes in a flat trap wall. A small upstream distance 5 before each inlet mouth 33 there is the outlet mouth 31 of a primary gas nozzle 22 assigned to the opening 29 in question. However, these primary gas nozzles 22 can optionally also protrude into the openings 29 or penetrate them.

Each primary gas nozzle 22 is arranged coaxially with the opening 29 assigned to it. The clear cross sections of the inlet mouth 32 and outlet mouth 33 of each opening 29 are larger than the clear cross section of the outlet mouth 35 of the associated primary gas nozzle 22. Between each primary gas nozzle 22 and the opening 29 assigned to it there is an annular gap which has a passage 29 into the combustion chamber 20 for the flowable medium that can be introduced into the antechamber 30 by means of the line 18, so that this medium can flow into the combustion chamber 20 from this antechamber 30. This medium can be, for example, gas containing coal dust, for example air containing coal dust, which coal dust is burned in the combustion chamber 12, this coal dust being at least partially already in the combustion chamber 20 forming a region of the combustion chamber 12 Gas channels 15 burns. This medium can also be another medium, e.g. only air, exhaust gas to be burned from the combustion chamber 12 or other flowable medium, or preferably flammable or non-combustible gaseous medium or carrier gas which carries solid and / or liquid particles with it in the combustion chamber support the combustion or should be burned._.

In this exemplary embodiment, a throttle and shut-off valve 44 is interposed in the line 18, which can be adjusted continuously or stepwise between its maximum open position and its shut-off state by means of a motorized actuator 50. A medium flow machine 45 upstream of the valve 44, such as a pump, blower or the like, is used to convey the medium. However, the primary gas jets can also assist the conveyance or the flow machine 45 can be omitted solely by the action of the primary gas jets. In this exemplary embodiment, the line 8 opens openly into the ambient atmosphere 38 of the device 10. However, it can also be connected to any supply line, for example to a return line branching off from the combustion chamber 12 or the smoke exhaust 13 'for returning flue gas into the Combustion chamber 20 for post-combustion or it can be connected to a supply line for other medium that is introduced into the combustion chamber.

In general, it is expedient for 44 at least close off the Startvorg ^'anges of the device 10 the line by means of the valve during an initial phase of the starting process or to slow or to throttle strongly, which can be automatically time-dependent provided and / or state-dependent or manually. - 13 -

It is also possible to provide manual or automatic adjustment of the valve 44 at the operating temperatures of the device 10, for example depending on air pressure fluctuations, the power output of the device 10 or the like.

The starting process means starting the device 11 from its cold state and starting it up until the operating temperature is reached. For this purpose, the actuator 50 can be adjusted in this exemplary embodiment by means of a control device 46 via the action line 49. A temperature sensor 47 arranged in the combustion chamber 12 is connected to this control device 46 and senses the respective internal temperature of the combustion chamber 12 at one point in its area 36, ie outside the combustion chamber 20. Since it is particularly expedient to simplify the starting process, at least in an initial phase of the starting process, to shut off or strongly throttle the valve 44, it can now preferably be provided for the starting process that the valve 44 is dependent on the temperature sensor 47 feels Temperature is adjusted during the described starting process. E.g. it can be provided that it is shut off when the device 10 is cold and remains shut off until its predetermined temperature, which it feels during an initial phase of the starting process, has risen to, for example, 100 to 200 ° C. and then can be provided that, as the temperature rises further, the shut-off valve 44 is opened gradually or steadily more and is opened to the maximum at a predetermined, sensed combustion chamber temperature which, for example, can expediently be somewhat below normal operating temperatures or can also be in the operating temperature range. This allows the start process to improve - to -

.and facilitate. Automatic or manual adjustment of the valve 44 can serve to influence the operation of the device 10 at operating temperatures, for example to minimize pollutant emissions, to control the power or the like.

Instead of controlling the valve 44 as a function of the combustion chamber temperature sensed by the sensor 47, it can also be provided that a timer 48 is switched on at the start of the starting process, which measures a predetermined period of time and then is reset to zero by the beginning of the next starting process. As long as this time period runs from the start of the starting process, the control device 46 causes the valve 44 to be shut off in a predetermined manner or to be throttled constantly or variably as a function of time during this time period or to be shut off during a range of this time period and during the remaining range of this period is throttled constant or variable. When this period of time has elapsed, the shut-off valve 44 can then be opened further, preferably set to the maximum open position or to a predetermined constant throttle position, or can be adjusted automatically, for example, as a function of the combustion chamber temperature sensed by the temperature sensor 47.

As mentioned, the turbomachine 45 can also be omitted, if necessary, since the primary gas jets in the antechamber 30 generate underpressure, which causes the medium to be sucked in through the line 18 into the antechamber 30 of this medium from the antechamber 30, from where this medium also flows through the passages 43 through the action of the primary gas jets into the combustion chamber 20. - M - The primary gas jets flow preferably with high VELOCITY _k eit out of the primary gas nozzle 22nd This primary gas Uesen _d 22 have a respective flared trumpet-shaped inlet mouth, and then to extend in _t he Nä _h e _d it forward, cylindrically in the flow direction tapered end portion.

This primary gas nozzle 22 may be preferably formed so that the cross sections of the flow out of them _d s primary gas jets are not circular, but non-circular, preferably undulating or have gear-like outline by the clear cross section of the primary gas 22 has corresponding to its outlet opening outline. An exemplary embodiment of such a primary gas nozzle is shown in FIG. 4 in a top view of its gas outlet end face 31 having the outlet mouth 35. The outline of the clear cross section at the outlet opening 35 has a serpentine corrugation here. The axial grooves in the circumferential wall of the clear interior of the nozzle 22 caused by this undulating course of the outline can extend over the axial length of the nozzle 22 or only begin inside the nozzle 22, for example, approximately in the middle thereof and then extend to the outlet continue at the mouth * 35. As a result, the outer surface of the primary gas jet flowing out of the nozzle 22 is considerably enlarged, which has a favorable effect on the generation of strong backflows in the combustion chamber 20 and relatively short flame lengths. Namely, the primary gas jets, owing to their high velocities when they flow out of the primary gas nozzles 22, produce considerable pressure reductions which, in the combustion chamber 20 of the gas channel 15, produce backflows, as indicated by the arrows, of the medium located therein in the direction of the wall 16. These reverse currents lead - 2.2. -

practically up to the catching wall 16, since the

Primary gas jets in the combustion chamber 20 generated pressure reduction on the trap wall 16 fully affects. This makes the

Fangwaπd 16 as a flame holder, so that you can also as

Flameπhalterwand can designate and apart from it no other flame holder are necessary. It is also possible to have the outlet openings of the primary gas nozzles 22 flush with the catching wall or to have them in

To allow recesses of the catch wall 16 to open.

The combustion of the fuel is also improved by the backflows of the mixture burning in the combustion chamber 20 towards the trap wall 16, which thus practically run or can run as far as the trap wall. achieved a higher degree of burnout, as well as reducing pollutant emissions. This device 10 is characterized by the structural simplicity of the gas channel 15 with primary gas nozzles 22 and catch wall 16. The gas duct 15 can also be relatively short, as can the rest of the combustion chamber 36, and the flame length is also reduced by the backflows.

FIG. 3 shows a longitudinal section of a gas channel 15, which in the details not shown can correspond to the gas channel 15 according to FIG. 1.

The other details of the device 10, not shown in FIG. 3, can also correspond to those of the device 10 according to FIG. 1.

The pressure chamber 19 of the gas channel 15, in which the fan, not shown, which preferably delivers primary gas consisting of air, is here 25th

also by a preferably flat partition 25 from one of the

Combustion chamber 20 upstream antechamber 30. In this antechamber 30, the primary gas nozzles 22 inserted into the partition wall 25 forming an end wall of the pressure chamber 19 protrude close to the trap wall 16 which delimits this antechamber 30 on the right side and forms an intermediate wall between it and the combustion chamber 20. Openings 29 tapering in a trumpet shape are arranged in this catch wall 16 and lead from the antechamber 30 into the combustion chamber 20, so that the antechamber 30 is connected to the combustion chamber 20 in a fluid-conducting manner via these openings 29. Each such opening 29 is arranged coaxially with a primary gas nozzle 22 arranged upstream of it. The smallest clear diameter of the opening 29 is larger than the cross section of the primary gas jet blown out of the relevant nozzle 22 through this opening 29 at the level of this opening 29, so that this primary gas jet by induction from the anteroom 30 medium through the annular-shaped passages 43 between the primary gas nozzles 22 and the trap wall 16 and through the openings 29 into the combustion chamber 20. In this particularly expedient exemplary embodiment, this medium is a part of the area 36 of the combustion chamber 12 that surrounds the gas chamber 15 and is sucked into the antechamber 30 by the action of the primary gas jets. There is therefore a return of flue gas generated in the combustion chamber 12 from the area 36 of the combustion chamber 12 through the anteroom 30 into the combustion chamber 20 of the gas channel 15 instead, namely by the action of the primary gas jets and not by means of a turbomachine 45 as in the exemplary embodiment according to FIG. 1A. ^L As in the device according to FIG. 1A, the combustion chamber 20 of the gas duct 15 opens out into the region 36 of the combustion chamber 12. This area 36 of the combustion chamber 12 is preferably larger, in particular essential

³ larger than the combustion chamber 20 of the gas channel 15, which also forms a region of the combustion chamber 12, so that flue gas can be sucked into the antechamber 30 from the region 36 of the combustion chamber 12 by the underpressure generated by the primary gas jets, the peripheral wall of the gas channel 15 that is, openings 26 are arranged in the pipe 17 of the gas channel at the level of the antechamber 30 and lead from the combustion chamber area 36 into the antechamber 30. The size of these openings 26 can be reduced to that of the circular tube 17 of the gas channel 15

° pushed on short tube 27 trained Schie-. Be adjusted via 27, this slide 27 until these openings 25 are shut off manually or by an actuator or the like. can be pushed. By axially moving the slide 27, the return of flue gas 0 can thus be shut off and optionally throttled variably, and the volume flow of the recirculated exhaust gas can thus be adjusted relative to the volume flow of the primary gas. The invention enables very strong dilution of the primary gas by recirculated flue gas, which allows extremely low pollutant emissions to be achieved. The flue gas recirculation means that further reductions in pollutant emissions can be achieved, and even extremely low pollutant emissions can be achieved. 0

Instead of designing the tube 17 of the gas channel 15 as cylindrical in the region of the combustion chamber 20, as shown, in many cases it can also have a different design, preferably over the entire length 5 of the combustion chamber 20 or over at least one - 2nd

Part of the combustion chamber 20 in the direction of its outlet opening, which opens into the area 36, diverge.

In this exemplary embodiment, the primary gas nozzles 22 arranged axially parallel to one another can be arranged, for example, to form a ring as in FIG. 2, wherein they are also held in the intermediate wall 25. E.g. can also have six here

Primary gas nozzles can be provided, but their number can also be smaller or larger. Instead of a single ring, several rings of such smaller primary gas nozzles can also be provided, or else they can have any desired arrangement and distribution by means of which the desired effects of the primary gas jets are achieved.

It is also possible, in a manner not shown, to arrange these straight primary gas nozzles 22 in such a way that their blowing directions, ie the longitudinal axes of their primary gas channels, are inclined obliquely to the longitudinal axis of the combustion chamber 20, in which case it is then expedient to also close the assigned openings 29 of the catching wall 16 tend that the respective primary gas nozzle 22 and the associated opening 29 of the catch wall 16 are arranged coaxially with each other. With such inclinations, all primary gas nozzles 22 can preferably be arranged with their jet directions diverging or converging to one another and / or all can be inclined in the circumferential direction of the combustion chamber 20 in the same sense that there is one around it in the combustion chamber ~ L €

Circulating flow results in the longitudinal axis.

A fuel atomizing nozzle 23 is in turn arranged in the center of the collecting wall 16, which preferably atomizes liquid fuel in the atomized state as jets 24 at an angle to the

Introduces primary gas jets in inclined directions into the combustion chamber 20.

The primary gas conveyed by the blower (not shown) during operation flows from the pressure chamber 19 into the primary gas nozzles 22 and through them as primary gas jets at high speeds into the anteroom 30 at a short distance from the associated openings 29 of the collecting wall 16 and as free primary gas jets through these openings 29 into the combustion chamber 20 at high speed.

The cross sections of these primary gas jets are smaller in the openings 29 of the collecting wall 16 than the clear cross sections of these openings 29, so that these

Primary gas jets from the region 36 of the furnace 12 through the _east openings 26 and ^{the antechamber} 30 toward ^d urch Rauc ^h gas suck in the combustion chamber 20 of the gas passage 15, the entrance room 30 through the passages 43 and the openings 29 and into the combustion chamber 20 flows in and is only conveyed by the primary gas as with a jet pump. As a result, the primary gas is diluted by this flue gas flowing into the combustion chamber, wherein, as mentioned, very high dilutions, that is to say very high volume flows of the sucked-in flue gas, are possible and permissible and are also very advantageous because of the strong pollutant reduction that can be achieved thereby. - I

As a result of the strong reverse flows generated in the combustion chamber 20 of the gas channel 15 by the plurality of primary gas jets, which lead approximately to the Fanggwand 16, the flame roots of the flame can practically hold onto the Fangwand 16 and no separate flame holders are required, since the Fangwand 16 causes the flame to be ignited in the combustion chamber 20 of the gas duct.

The combustion chamber 20 of the gas channel 15 is in each case so long that the backflows are reliably generated in it. However, the flame starting in it can extend from this combustion chamber 20 into the remaining, larger area 36 of the combustion chamber 12, preferably even quite far.

The primary gas nozzles 22 in the gas duct 15 according to FIG. 3 can also preferably be used to generate

Primary gas jets with a non-circular cross-section must be formed at the level of the outlet opening of the primary gas nozzles, since this further optimizes the combustion process and can further reduce the pollutant emissions. E.g. The outlet openings 35 of these nozzles 22 can also be of the same or similar design as shown in FIG. 4. This out-of-round design of the outlet opening of the nozzle 22 allows, inter alia, the amount of smoke gas drawn in through the antechamber 30 to be increased and the backflow in the combustion chamber 20 to be influenced even more favorably. The length of the flame can also be shortened as a result. - 1 -

In the exemplary embodiment according to FIG. 5, a short section from a gas duct 15 is shown, which is designed similarly to that according to FIG. 3 and is part of a device for the continuous combustion of fuel, for example a device similar to that according to FIG differs from that of FIG. 3 essentially in that the catch wall 16, the anteroom 30, in the flue gas from the area 36 of the combustion chamber 12 surrounding the gas channel 15 through the primary gas jets through openings 26 in the peripheral wall 17 of the gas channel 15 also can be sucked in, separates from the combustion chamber 20 of the gas channel 15, here is designed as a hollow wall or double wall. This design can be used to introduce gaseous fuel or fuel particles carried by gas, in particular coal dust, into the combustion chamber 20 of the gas channel 15 in a particularly simple manner and not disturbing the flow in the combustion chamber 20. For this purpose, a fuel feed line 28 ′ for flowable fuel opens into the cavity 37 of the collecting wall 16, which is introduced under pressure and through annular gaps 39 provided in the openings 29 for the primary gas jets of the collecting wall 16 and / or through openings 29 provided on or near these other outlet openings in the collecting wall 16 flow from it into the combustion chamber 20 together with the primary gas jets ^* and the recirculated flue gas. There is also a further outlet opening 41 leading into the combustion chamber 20 for the fuel in the middle of this catch wall 16. It is also possible for a plurality of such fuel outflow openings 41 in the - Z -

A distance from the openings 29 may be provided for the primary gas jets or only such outlet openings for the fuel may be provided at a distance from the openings 29 of the trap wall 16 for the primary gas jets. An exemplary embodiment is shown in FIGS. 6 and 7, where the cut-out hollow catch wall 16 directly adjacent to the downstream edge of each of its openings 29, only one of which is shown here, has outlet openings 39 'for fuel only in the area 40 adjacent to the combustion chamber 20 which are designed as small holes arranged in a ring, which enclose the opening 29 at a short distance.

Provision can also be made for the mixture of the combustion chamber 20 to be recirculated through the or at least one cavity of the hollow collecting wall 16 through the primary gas jets. E.g. For this purpose, the fuel feed line 28 ′ can be omitted in FIG. 5 and the relevant opening of the cavity 37 can be closed. The primary gas jets then suck in mixture from the combustion chamber 20 through the cavity 37 of the trap wall 16, which flows into the cavity 37 through the central opening 41 and flows out again through the annular gaps 39 and flows back into the combustion chamber. It can also be provided here that the cavity 37 of the trap wall 16 is divided into areas which are sealed off from one another in a fluid-tight manner, at least one area of which flows through a recirculating mixture from the combustion chamber and at least one other area of fuel for introducing it - S -

is flowed into the combustion chamber

Instead of arranging the primary gas nozzles 22 upstream of the openings 29 of the collecting wall 16, as in FIGS. 2, 3 and 5, provision can also be made for them to protrude into these openings 29 or for them to protrude through these openings 29, in the latter If a short distance can then reach into the combustion chamber, as indicated by two-dot dash lines in FIGS. 3 and 5 at 22 'and 22 ", these nozzles 22', 22" from the walls of the openings 29 in Distance are included, so that here the passages 43 for medium sucked in from the antechamber 30 into the combustion chamber 20 by the primary gas jets are present.

It is also conceivable to provide that smoke gas sucked in by the primary gas jets from the surroundings 38 of the gas channel 15 flows directly into the combustion chamber 20, for example in the device according to Fig. 1A for this purpose in the pipe 17 at the height of the combustion chamber 20 near the trap wall 16 or at least one inlet opening for flue gas is provided adjacent to them. Or in some cases it can also be provided that the flue gas sucked in from the vestibule 30 by the primary gas jets into the pulp chamber 20 from the area 36 of the combustion chamber 12 flows through at least in part at least one opening in the trap wall 16 which is not flowed through by primary gas. It is normally sufficient for devices according to the invention if they each have a single firing chamber. In the case of very large facilities, however, the facility can optionally also have a plurality of combustion chambers in which, if desired, fuel can be burned independently of one another or simultaneously or in parallel to generate heat.

It is also possible to provide that the passages 43 can be variably throttled and / or shut off, for example by means of flange sleeves arranged on the primary gas nozzles 22 and slidably connected to one another, the flanges of which form annular disks, the flanges of which form a maximum open position in the Distance in front of the catching wall 16, preferably up to the contact with the catching wall 16, can be moved axially and back manually or by means of an actuator and can be adjusted to any axial position.

In some cases it is also conceivable that only between one primary gas nozzle or a part of the total number of primary gas nozzles and the trap wall there is at least one passage for medium flowing into the combustion chamber 20 from the antechamber 30 and accordingly that the at least one other primary gas nozzle is spaced in the catch wall 16 is inserted so that there is no passage for medium between it and the catch wall.

Claims

- i -

Claims

Method for burning fuel using oxygen-containing primary gas which is conveyed into a combustion chamber, the primary gas being introduced into a combustion chamber of a gas duct, into which fuel is also introduced and in which combustion chamber the combustion of the fuel begins and takes place at least partially, characterized in that that the primary gas is blown into this combustion chamber by means of several primary gas nozzles in a plurality of primary gas jets in a direction leading away from a trap wall delimiting it on the input side in such a way that the primary gas jets in the combustion chamber of the gas channel towards the trap wall are directed backflows of the combustion

Generate gas-fuel mixture, and that between at least one primary gas nozzle and the trap wall there is at least one passage through which medium can flow into the combustion chamber.

2. The method according to claim 1, characterized in that between at least two primary gas nozzles and the wall, preferably between all primary gas nozzles and the trap wall, passages for medium are present, which in the Brenπraum through can flow through these passages.

Method according to claim 1 or 2, characterized in that a plurality of openings are provided in the trap wall through which the primary gas jets are blown into the combustion chamber, the cross sections of the primary gas jets in these openings being smaller, preferably considerably smaller than the smallest clear cross sections of these openings are.

Method according to claim 1 or 2, characterized in that the primary gas jets are blown out of the primary gas nozzles at the height of the trap wall or downstream of it.

Method according to one of the preceding claims, characterized in that the volume flow of the medium, which can flow into the combustion chamber through the passage or passages between the primary gas nozzle (s) and the trap wall, can be variably throttled and / or shut off, preferably automatically as a function of it the time and / or the temperature of the furnace.

Method according to one of the preceding claims, characterized in that during the respective starting process the volume flow of the medium flowing through the passages between the primary gas nozzles and the trap wall into the combustion chamber, relative to the size of this volume flow -i4

Operating temperatures are reduced at least in a start-up phase of the starting process, preferably the supply of this medium is shut off, the starting process being understood to mean the starting of the combustion chamber from its cold state to operating temperatures.

7. The method according to any one of the preceding claims, characterized in that the combustion chamber is preceded by an antechamber separated by the trap wall, into which antechamber flowable medium is sucked in by the action of the primary gas jets and further conveyed from it into the combustion chamber by the action of the primary gas jets can be, which medium can preferably be flue gas originating from the combustion chamber.

8. The method according to any one of the preceding claims, characterized in that at least one primary gas jet, preferably each primary gas jet flows into the combustion chamber through a separate opening of the trap wall assigned to it, through which no other primary gas jet flows.

9. The method according to any one of the preceding claims, characterized in that at least two primary gas jets flow into the combustion chamber of the gas channel through at least one opening of the trap wall. -5- ^■) ? -

10. The method according to any one of the preceding claims, characterized in that at least two primary gas jets, preferably all primary gas jets are blown into the combustion chamber parallel to one another, preferably parallel to the longitudinal axis of the combustion chamber.

11. The method according to any one of the preceding claims, characterized in that at least two primary gas jets, preferably all primary gas jets are blown into the combustion chamber with blowing directions inclined to its longitudinal axis, preferably at least two, preferably all of the mutually inclined blowing directions of the primary gas nozzles diverge or converge with one another.

12. The method according to any one of the preceding claims, characterized in that between at least one primary gas nozzle and the trap wall there is at least one annular passage for medium, preferably between all

Primary gas nozzles and the trap wall annular passages are present.

13. The method according to any one of the preceding claims, characterized in that a plurality of primary gas jets are blown into the combustion chamber from at least one primary gas nozzle serving to blow out primary gas. 14. The method according to any one of the preceding claims, characterized in that a single primary gas jet is blown into the combustion chamber from at least one primary gas nozzle serving to blow out primary gas, preferably from all of these nozzles.

15. The method according to any one of the preceding claims, characterized in that the openings in the trap wall, through which primary gas jets and / or medium can flow into the combustion chamber from the anteroom, taper in the downstream direction.

16. The method according to any one of the preceding claims, characterized in that the cross sections of the primary gas jets blown out of the primary gas nozzles at the height of the outlet openings of the primary gas nozzles are out of round, preferably have approximately gear-shaped or wave-shaped outlines.

17. The method according to any one of the preceding claims, characterized in that the entire fuel is introduced into the combustion chamber of the gas channel or that fuel can be introduced into the remaining combustion chamber in addition to the combustion chamber of the gas channel.

18. The method according to any one of the preceding claims, characterized in that at least two primary gas jets, preferably all primary gas jets through separate openings in the Catch wall are blown into the combustion chamber and / or by means of primary gas nozzles arranged at a distance from one another.

19. The method according to any one of the preceding claims, characterized in that liquid fuel, preferably in the atomized state, is introduced into the combustion chamber of the gas channel.

20. The method according to any one of claims 1-18, characterized in that gaseous fuel is introduced into the combustion chamber of the gas channel, which is preferably introduced into the combustion chamber through at least one cavity of the trap wall.

21. The method according to any one of claims 1-19, characterized in that solid fuel particles contained in a gas, preferably coal dust, can be introduced into the combustion chamber of the gas channel, preferably through at least one cavity in the trap wall.

22. Device for performing the method according to one of the preceding claims, characterized in that it has a combustion chamber (12) which is at least partially formed by a combustion chamber (20) of a gas channel (15), which combustion chamber (20) of the gas channel on the input side is limited by a flame-retaining wall (16) that in -3 * -

this combustion chamber (20) from a blower (21) or the like. Primary gas conveyed by means of primary gas nozzles (22) can be introduced in several jets, the primary gas nozzles (22) being arranged relative to the collecting wall (16) in such a way that they pass through the combustion chamber of the gas channel to give the primary gas jets generated backflows towards the trap wall and that between the trap wall (16) and at least one primary gas nozzle (22) there is at least one passage (43) for flowable medium that can flow into the combustion chamber, preferably between all primary gas nozzles and the trap wall openings for medium are available.

23. Device according to claim 22, characterized in that the catch wall (16) is an intermediate wall between the chamber (20) and an antechamber (30) connected upstream thereof, in which antechamber flowable medium, preferably from the combustion chamber Coming flue gas, which can be introduced and passed through the openings (29) between the primary gas nozzles (22) and the collecting wall (16) into the combustion chamber.

24. Device according to claim 22 or 23, characterized in that the fluid medium is sucked in by the primary gas jets and is conveyed into the combustion chamber.

25. Device according to one of claims 22 to 24, characterized in that the primary gas nozzles -33 -

(22) at a distance from one another are preferably arranged to form at least one ring

26. Device according to one of claims 22 to 25, characterized in that the outlet openings (35) of the primary gas nozzles (22) are arranged at a short downstream distance in front of the openings (29) of the collecting wall (16) assigned to them, and that these openings ( 29) of the catch wall preferably have clear cross sections which are considerably larger than the clear cross sections of the outlet openings (35) of the primary gas nozzles (22).

27. Device according to one of claims 22 to 25, characterized in that the primary gas nozzles (22) in the openings (29) of the catch wall (16) assigned to them protrude or penetrate them.

28. Device according to one of claims 22 to 27, characterized in that in the catch wall (16) at least one fuel nozzle (23) for introducing fuel into the combustion chamber (20) of the gas channel (15) is arranged.

29. Device according to one of claims 22 to 28, characterized in that the catching wall (16) is a hollow wall or double wall, the at least one cavity of which as a fuel feed line for introducing fuel into the combustion chamber (20) of the gas channel and / or as a through-flow chamber for at least one recirculating flow, the caused by at least one primary gas jet flows from the combustion chamber into a cavity of the trap wall and flows out of it back into the combustion chamber.

30. Device according to one of claims 22 to 29, characterized in that it comprises throttling means and / or shut-off means (27; 44) for throttling and / or shutting off the passages (43) between the primary gas nozzles (22) and the collecting wall (16) inflowing medium and / or these passages.

31. Device according to one of claims 22 to 30, characterized in that it is a heat generator, preferably a boiler (10).