PT683883E - OPTIMIZED COMBUSTION BLUE FLAME BURNER - Google Patents

Abstract

The invention concerns a liquid-fuel burner comprising a housing (10), a precombustion chamber (48) containing a nozzle assembly (24) with a nozzle (28) which produces a jet of fuel (80), a combustion chamber (92) in which the fuel jet broadens out, a partition (90) between the precombustion and combustion chambers, and a fan (16) designed to force a stream of combustion air into the combustion chamber, the fuel burning essentially stoichiometrically with a blue flame. In order to improve the burner to minimize the amounts of pollutants in the combustion gases, the invention proposes that, in addition to a stream of combustion air (102) entering the combustion chamber near the fuel jet, a second, recirculation-stabilizing stream of air (106) enters opposite the first stream, at a defined radial distance further out from the first stream. Inside the combustion chamber, an inner recirculation stream (112) is formed which is stabilized by the second stream of combustion air.

Description

DESCRIPTION " BURNER WITH OPTIMIZED COMBUSTION BLUE FLAME " The present invention relates to a burner for fluid media comprising a burner body, having a support tube with an antechamber disposed therein and a flame tube connected to the former, a nozzle holder placed within the antechamber which produces a fuel jet, a combustion chamber located within the flame tube, essentially not corresponding to a mixing tube, in which the jet of fuel expands, a separating element with a central aperture through which the jet of and is disposed between the antechamber and the combustion chamber, the combustion chamber being connected to the separation element, a blower for generating the flow of combustion air entering the combustion chamber comprising a partial flow near the jet of fuel, the fuel being burned in the combustion chamber substantially at or near the stoichiometric combustion conditions, which provide a blue flame. DE-OS 40 09 222 describes a burner for burning under the stoichiometric conditions of combustion of liquid or gaseous fuels from a spray nozzle. In this burner the air is passed around the spray nozzle and through a diaphragm into a combustion chamber in which the fuel is also fed out of the nozzle. 1

Additionally, there are provided in the combustion chamber wall tear-shaped openings parallel to the flow direction through which a recirculation of cold combustion gases from the outside of the burner tube is generated which mix with the fuel and with the incoming air, passing around the spray nozzle, in order to achieve the stoichiometric combustion conditions in the space where the firing occurs. EP-A-0 430 011 also discloses a blue flame burner in which, around a spray nozzle, a mixture of recirculated air and flue gases is introduced therein mixing with the fuel from the spray nozzle before combustion takes place under stoichiometric conditions.

In all examples of embodiments there is provided a mixture of combustion air and flue gases recirculated prior to the plane where the outlet opening of the nozzle is located and only then in a mixing chamber does the mixture of the combustion air and the gases recirculated with the fuel which then enter the combustion chamber itself. In special examples of embodiments the fresh air is introduced in parts, on the one hand a first part that mixes directly with the flue gases in recirculation and on the other hand a second part that passes around the spray nozzle and which serves to cool the spray nozzle so that the cooling of the spray nozzle, in particular in the case of oil nozzles, can be regulated. This fresh air is then also introduced into a mixing chamber together with the rest of the fresh air and mixed with the recirculating flue gases as well as the fuel. 2

DE-OS 27 12 564 discloses an adjustable burner in which there is a dam disk and, downstream of the dam disk, an underpressure region achieved by a hollow rotary air column, so that the gases are sucked back into this region of underpressure. The hollow rotary air column is created by radially arranged radially and boss-covered radial slots.

In addition, in the case of high powers, fresh air inlets are also provided from outside.

In addition, the spray nozzle is disposed in conjunction with ignition electrodes in a separate space in which only as much fresh air as is required for the displacement of the ignition sparks enters. DE-PS 29 08 427 discloses a burner in which, first, with the addition of flue gases, combustion is carried out under substoichiometric conditions in a first combustion zone with the immediately following introduction of an air flow from the which surrounds the fuel flow and then in a second secondary combustion zone in which the remaining air is introduced, surrounding the periphery zone of the primary combustion zone, combustion takes place under stoichiometric conditions. The remaining air is fed in at least two adjustable partial flows which surround the burner which, after passing through a certain free flow path, reach the flame from the mouth of the burner.

DE-OS 31 09 988 discloses a burner designated as a blue flame burner in which, by means of a mixing tube,

recirculation, a jet of fuel being introduced by a spray nozzle, on the one hand directly introduced into the surrounding combustion air, on the other hand, there are provided air passage holes which are disposed radially inside the mixer tube.

In a blue flame burner according to this document, the mixing tube has the function of ensuring that an internal recirculation takes place to ensure the characteristic blue flame of the burner.

According to patent EP-A-0 538 761 a burner with a recirculation was known in which the outer recirculation is generated by effect of the longitudinal direction of the slits, these slits being developed, with their longitudinal axes, along the periphery .

In addition, fresh air is blown into the combustion space, the injector being bathed all the way through the air entering through a diaphragm.

Similar burners are known for example from DE-PS 27 00 671 or DE-PS 39 01 681.

In such burners, in order to form a stable recirculation flow, a so-called mixing tube is required which establishes a single recirculation flow of hot gases and thus enables a blue flame burn.

By the blue flame of the burn it is understood that the flame is the burning of a fully gaseous fuel which, especially when using oil as fuel, makes it necessary that the oil droplets leaving the nozzle in the 4

of the fuel jet are practically completely vaporized prior to their burning in the flame. The problem with these known burners is that the general design of the burner makes it necessary to match all the parts to a single burner power so that a burner for another power requires an entirely new construction.

From DE-A-40 09 222 it is the object of the present invention to provide improvements in a burner of the type referred to which allows combustion which, as far as possible, does not give rise to harmful products and takes place under stable or stoichiometric conditions or near them.

This object is achieved by a burner having the features set forth in claim 1. The advantage of the solution advocated by the invention lies in the fact that, by the additional partial flow of air which promotes a recirculation stabilization, it is possible to achieve a stabilization of the internal flow of recirculation inside the combustion chamber.

Thus, it is possible to have a burner in which, by the local definition of the combustion air supply, it is possible, essentially without mechanical flow guiding elements, to ensure that stable recirculation flows occur in the combustion chamber and thus a burning with blue flame.

An advantageous variant of the solution advocated by the invention provides that, in the burner body, there are openings through which external recirculation streams which conduct cold combustion gases entering the combustion chamber pass through.

combustion, that the external recirculation flow enters the combustion chamber in the vicinity of the separation element and is so large that the flame root is at least 1 cm away from the nozzle and that between the nozzle and the flame root , there is a part of the fuel jet in which no combustion occurs and, by mixing with the combustion air, the jet expands in a cone. The advantage of the solution according to the invention consists in particular of the fact that the external recirculation flow which according to the current state of the art would only be employed to reduce the content of harmful combustion gases, in particular nitrogen oxides, according to the invention are employed to position the root of the flame at a sufficiently large distance, in particular in that, with the aid of the external recirculation flow, essentially non-oxidizing gases are introduced in sufficient quantities into the combustion chamber or are only to a limited extent so as to increase the mass flow passing through the combustion chamber and thereby achieve the spacing between the flame root and the injector which is necessary to achieve a part of the fuel jet where if no combustion occurs, which is in turn necessary to achieve complete vaporization of the fuel droplets.

In particular, in this exemplary embodiment, by the sufficient length of the part of the fuel jet in which no combustion occurs, it is possible to mix the gases from the inner recirculation flow with the jet of fuel and, again the possibility of completely vaporizing the fuel droplets, surely before they reach the base of the flame, so that ultimately a stable blue flame is obtained which to a large extent is not sensitive to slight changes in the setting parameters. 6

An advantageous variant of the solution according to the invention provides that in the burner body there are openings through which an external recirculation flow, leading to cold combustion gases and entering the proximity of the separating element, passes into the combustion chamber and that this flow to protect the internal recirculation flow relative to the separating element, which flow inside the combustion chamber takes the form of a return flow between the blue flame and the part of the fuel jet in which no combustion takes place.

In this solution according to the invention, the external recirculation flow, which is normally employed for the reduction of harmful products, in particular the nitrogen oxides, according to the invention is used to protect the hot combustion flue gases of internal recirculation with respect to the cold separating element and thus prevent a strong cooling of these hot combustion gases by the influence of the cold separating element. In addition, these hot flue gases are brought into contact with the jet of fuel practically uncooled or have been very little so that, by the amount of heat added, vaporization, as far as possible optimized, of the droplets of fuel. The solution according to the invention in conjunction with the use of an external recirculation flow further has the great advantage that, in the absence of mechanical flow guiding elements in the combustion chamber, in particular the absence of a mixing tube, do not cause emissions of harmful products at the start of the burner which cause the external recirculation to be regulated variably. In addition, the solution according to the invention offers the great advantage that, at the start of the burner, the

The combustion of the combustion chamber can be carried out at an optimum low content in noxious products, so that the labor-intensive regulation of the external recirculation, such as that described in DE-PS 39 06 854, can in fact still be done, but However, due to the good values for toxic products without this regulation, the latter is not necessary.

Concerning the development of the internal recirculation flow inside the combustion chamber, no detailed data have yet been provided. Thus the present invention provides, in an advantageous example of embodiment, that the internal recirculation flow, starting from the flame, flows along the inner side of the flame tube towards the separating element. In this situation, the internal recirculation flow can be particularly easily and permanently stabilized by the partial flow of the combustion air which promotes the stabilization.

In the case of an example of an especially convenient embodiment with internal recirculation flow, the inner recirculation flow has a yellow flame.

A particularly advantageous effect of the internal recirculation flow, in particular with respect to heat transfer to the fuel, in order to vaporize the oil droplets, can be achieved when the internal recirculation flow passes through the partial flow promoting the recirculation stabilization.

With regard to the direction in which the partial flow promoting recirculation stabilization enters the combustion chamber, no explanations relating to the examples of embodiments have so far been given. For example, the partial flow promoting the recirculation stabilization 8

could be parallel to the conical outer surface of the fuel jet. It is, however, particularly convenient that the partial flow promoting the stabilization of the flow is, when entering the combustion chamber, essentially parallel to the fuel jet. It is especially advantageous in these circumstances that the partial flows are independent of the amount of air to be regulated at the same points of entry into the combustion chamber.

By locally fixing the partial flow in the combustion chamber, the stabilization of the recirculation flows can be achieved in a particularly advantageous way for each adjustment of the air and fuel quantities, using very simple means.

With regard to the explanations hitherto provided on the individual examples of embodiments, no details have been given as to which partial flows in which the amount of air is regulated.

From the calculation of the combustion process it would be possible, in a purely theoretical way, to establish the way in which the quantities of air introduced by the partial flow in the vicinity of the jet of fuel or introduced by the partial flow which promotes the stabilization of the recirculation or both would be adjustable.

For the sake of simplification and in order to achieve a suitable flow solution, it is advantageous, however, that, for regulation of the quantity of air, only one of the partial flows is adjustable, in order to achieve the necessary adaptation to the quantity of fuel introduced. 9

For stabilization of the recirculation flows for each regulation of the amounts of air and fuel, it has proved to be particularly advantageous that the partial flow which promotes the stabilization of the recirculation is adjustable with respect to the amount of air. By virtue of the possibility of regulating the partial flow which promotes recirculation stability, it is possible in particular to achieve an advantageous recirculation flow stabilization for each control of the burner power, since the partial flow acts directly on the formation of the recirculation flows and thus it is possible to adjust them in such a way that the recirculation flow is directly stabilizable as a result of the position of the point of entry of this partial flow in the combustion chamber.

Advantageously, the recirculation stabilizing flow enters the combustion chamber in the form of an interrupted annular flow around the respective fuel jet, whereby the stabilization of the recirculation flow can still be improved since, at the breakpoints, it becomes very easy to introduce a " cross-flow " of the annular flow in a radial direction, while between the interruptions there are created stabilizing swirls.

Since the maximum speed of the fuel in the flame for the maximum quantity of fuel is moreover, it is particularly advantageous if the quantity of air in the partial stream which promotes recirculation is the maximum for the maximum quantity of fuel and the minimum for the minimum amount of fuel, so that the amount of air from the partial stream which promotes recirculation, for a maximum amount of fuel, and therefore, for a higher velocity of the flue gases in the combustion chamber, the flow of 10

recirculation is sufficient for combustion to remain with blue flame.

With respect to the possibility of regulating the recirculation flow, it has also been found advantageous that the amount of air in the partial stream near the jet of fuel is kept constant for all fuel quantity adjustments so that the partial flow close to the fuel jet ensures a continuous supply of air to the fuel jet. At the limit, the amount of air in the near partial stream of the fuel jet will be sized so that for the maximum amount of fuel the amount of air in the partial stream that promotes recirculation stabilization is maximum and for the minimum amount of fuel the combustion air stream is only formed by the near partial flow of the fuel jet.

In an advantageous example of embodiment of the burner according to the invention, it is envisaged that the amount of air in the partial stream near the jet of fuel will be approximately between 0.6 times and 0.2 times the amount of air in the stream which provides for the stabilization of recirculation, it is expected that this field of regulation will be variable for a special burner whose power can vary up to that resulting from the application of a factor 5.

With regard to the type of fuel jet formation, no detailed explanations have been provided in the descriptions of the examples of previous embodiments. Thus, in an exemplary embodiment, a particularly simple and effective solution is provided in which the jet of fuel exiting the nozzle opening and depending on the shape of the nozzle opens into a cone, in particular a cone 11

complete, in which oil droplets of as homogeneous dimensions as possible are dispersed in as homogeneous a distribution as possible.

As far as the direction of the partial flow near the coextensive jet to the combustion chamber is concerned, no detailed considerations were also made. Thus, in an example of an advantageous embodiment, the near partial flow of the jet of fuel is expected to enter the combustion chamber in a direction essentially parallel to the direction of the jet of fuel.

Advantageously, the near partial flow of the fuel jet enters the combustion chamber enveloping the fuel jet in order to enable a good mixing of this part of the combustion air with the jet of fuel within the combustion chamber.

This is particularly advantageously achieved when the near partial flow of the jet of fuel and the jet of fuel enters the combustion chamber through the central passage opening provided in the separating element.

Concerning the point of entry of the partial flow near the fuel jet in the combustion chamber, no detailed observations have so far been made. Thus, in an example of an advantageous embodiment, the near partial flow of the fuel jet is predicted to enter the fuel chamber passing through a region of the peripheries of the injector head.

Still more advantageously is that, in particular in view of the availability of space in the injector zone, the near partial flow of the fuel jet flows along a profile 12

defined exterior of the injector head and thus enters the combustion chamber in the immediate vicinity of the fuel jet.

In the simplest case the cross section necessary for the passage of the near partial flow of the fuel jet is achieved when the partial flow near the jet of fuel passes through a passageway between the head of the injector and an edge of an opening in the combustion chamber, provided for passage of the near flow of the fuel jet, so that the size of the through aperture defines the free area of the through section to the near partial flow of the fuel jet.

A particularly advantageous degree of mixing of the fuel with the near partial flow of the fuel jet, already inside the combustion chamber, is achieved when the inlet opening for the near flow of the fuel jet is configured so as to impart turbulence to the same.

In the simplest case, it is envisaged that, for this purpose, the inlet opening of the stream is provided with turbulence-inducing edges or knives which provide the same effect.

With regard to the construction of the burner body, in correlation with the examples of embodiments, no details were given. In this context it is provided in an example of an advantageous embodiment that the burner body comprises an antechamber in which the nozzle is arranged and is separated from the combustion chamber by a separating element. Such a burner body construction has the advantage of being of great ease and constructive flexibility. 13

In correlation with the exemplary forms of construction described up to now, no detail has been given as to how the combustion air flow enters the combustion chamber. It is especially advantageous if the entire combustion air is conducted through the antechamber since, in this way, a particularly simple burner construction is ensured.

For this purpose, also for reasons of ease of construction, it is envisaged that the flow of combustion air enters the combustion chamber passing through the separating element.

With respect to the guide of the combustion air in passing through the separating element, it is advantageously provided that the separating element has, on the side facing the injector, a through opening for the partial flow near the fuel jet.

It is furthermore conveniently foreseen that, in order to let the partial flow promoting the stabilization of the recirculation at the desired point of the combustion chamber enter, the separation element has, in relation to the partial flow inlet opening near the fuel jet , at least one radial opening on the outside for the partial flow which promotes the stabilization of the recirculation.

With regard to the configuration of the combustion chamber, no detailed observations have heretofore been made, in correlation with the examples of embodiments already described. Thus, in an example of an advantageous construction form, it is envisaged that the combustion chamber is surrounded by a flame tube of the burner so that this flame tube of the burner allows to establish a defined geometry 14

for the surrounding space of the combustion chamber and therefore in particular a defined form of the recirculation stabilization flow.

This flame tube is provided with openings for formation of the external recirculation flow, in order to reduce the emissions of nitrogen oxides.

With regard to the configuration of the combustion chamber itself, no detailed observations have so far been made, in correlation with the descriptions given above. Thus, in an example of an advantageous embodiment, it is envisaged that the combustion chamber will extend from a certain plane located in the vicinity of the nozzle opening. Such a combustion chamber construction provides optimum guidance of the individual recirculation flows, in particular of the inner and outer recirculation flows, towards the part of the non-burning fuel jet.

A particularly simple and efficient construction of the combustion chamber provides that it has an essentially constant cross-section between the separating element and the area where the flame root is located. This provides the advantage of having sufficient space for guiding and forming the recirculation flows, in particular the inner recirculation flow. As regards the separating element, no comments were made. The separating element can be made as described in EP 0 430 011. Especially constructively easy is the solution of the separating element being a diaphragm. The diaphragm may, in turn, be bulged as hereinafter referred to. For example, as described in DE-OS 40 09 222. It is particularly advantageous, however, for the diaphragm to extend over a plane in that such a shape also allows optimum guidance of the recirculation flows to the zone where the part of the non-burning fuel jet in the vicinity of the diaphragm. It is especially advantageous for the combustion chamber to have a recirculation space which is passed through the part of the fuel jet which is not burning and which surrounds that same part of the fuel jet, which space provides optimum possibilities for introducing the individual streams recirculation towards the part of the fuel jet which is not burning.

Conveniently, in such circumstances, the recirculation space is configured such that it extends at least to the root of the flame in order to provide sufficient space for the passage of the inner recirculation flow. In order to achieve the stabilization of the recirculation flows in an optimized manner, it is envisaged that the partial flow of recirculation stabilization enters the recirculation space.

Advantageously, the recirculation stabilizing flow is formed such that it is symmetrical about an axis of the combustion chamber and therefore enters the recirculation space symmetrically with respect to a same river axis.

Preferably the partial flow promoting the recirculation stabilization is formed in such a way that it enters the combustion chamber with a cylindrical flow profile lying down. This form 16

of the partial flow promoting the recirculation stabilization allows for optimized stabilization of the internal recirculation flow.

In this case, the cylinder is especially a circular straight cylinder which is defined by a primitive circumference situated in the middle thereof.

As far as the flow profile is concerned, no detailed comments have yet been made. For example, it would be possible to configure the flow profile as a closed annular flow with the shape of the cylinder. It is, however, particularly advantageous if the flow profile is composed of parallel individual streams since these individual streams provide the possibility of, in a particularly advantageous way, passing the recirculation flows through the recirculation stabilizing flow in the zone where the part of the jet of fuel that is not burning is located.

This is particularly advantageous when the individual streams are distributed so as to have constant angular distances relative to one another in order to establish defined intermediate spaces through which the recirculation flows can pass.

With regard to the dimensioning of the individual flows in relation to the angular distances therebetween, it has proved to be particularly advantageous that the ratio between the angular distances between two individual streams and the angular width of the inlet cross-sections of each individual flow is approximately between 10 and 0.1. 17

It is more advantageous for this ratio to be in the range of about 3 to about 0.1, or more preferably about 2 to about 0.1, and still more preferably about 1 to about 0.1, and the results obtained with a ratio lying approximately between 1.5 and 0.3.

In addition, no data regarding the design of the recirculation space has yet been presented. Advantageously, it is envisaged that the circular annular zone has a diameter of the initial circumference that is approximately 0.2 to 0.7 of the outer diameter of the combustion chamber or the recirculation chamber.

An optimum effect of the recirculation stabilizing partial flow is obtained when the recirculation space has, for example, an outer diameter corresponding to the inner diameter of the flame tube, the said outer diameter having a value of 1.5 to 3 times the diameter of the circumferential circumference of the circular straight cylinder.

Still more advantageous is the case where the recirculation space has an outer diameter equal to approximately 1.8 to 2.6 times, or rather 2 to 2.5 times the diameter of the circumference of the circular straight cylinder. Especially optimized results are obtained when the diameter of the recirculation space is approximately equal to 2.4 + 10%, or better still, approximately 2.5 times the diameter of the primitive circumference.

In particular, in order to optimize the flame stabilization and prevent the flame from flickering in space, it has proved to be especially convenient that a flame space is present after the recirculation space. 18

This flame space may, in the case of high powers, have the same diameter as the recirculation space but, especially in the case of small powers, with regard to stabilization in space, it has proved advantageous that the flame space has a diameter which is at most equal to or less than that of the recirculation space.

Particularly preferred values occur when the diameter of the flame tube is approximately 0.6 to 0.9 times the diameter of the recirculation space. Particularly advantageous has been shown to be the case where the inner diameter of the flame space is approximately 0.8 times the inner diameter of the recirculation space.

As far as the expansion of the combustion chamber is concerned, no specific data were also provided. Also, in order to keep the flame as stable as possible, it has proved advantageous that the flame has a root within the combustion chamber.

Concerning the creation of the external recirculation flow in the combustion chamber, detailed observations have not yet been made. Thus, for example, the creation of the external recirculation flow in the combustion chamber can be achieved as described in the patent EP 0 430 011. It is however especially advantageous that the external recirculation flow enters the combustion chamber, separated from the flow of combustion air.

This example of embodiment has the great advantage of being able, on the one hand, to conduct a defined external recirculation flow and, on the other hand, a definite regulation can be made with respect to the mass flow, which for the aspects of characterization of the invention is important, in particular with respect to conducting the outer recirculation flow 19 17 for purposes of protecting the internal recirculation flow relative to the separating element and the mass flow dimensioning, which is important in view a sufficiently large part of the area of the non-burning fuel jet is reached. In this way, the internal recirculation flow volume is also set.

With particularly simple means this construction can be achieved when the outside recirculation flow enters directly into the combustion chamber, through recirculation openings provided in the flame tube.

As far as the design of the external recirculation flow is concerned, no quantitative data have yet been presented. Thus, in an example of an advantageous embodiment, it is envisaged that the area of the inlet for the combustion air inlet in the combustion chamber is at most approximately equal to the area of the recirculation openings provided in the flame tube for the flow of recirculation. With this design, a sufficiently large mass flow is ensured in the recirculation stream in order to obtain a portion of the non-burning fuel jet of sufficient length within the combustion chamber.

In addition, it is possible to provide in the flame tube a flow stabilizing member extending from the diaphragm towards the flame root zone by a maximum length of about a quarter of the distance between the diaphragm and the flame. This flow stabilizer element has nothing to do with the mixing tube known in the prior art, since the mixing tube only allows to set up a single recirculation flow, while the recirculation stabilizing element is provided such that

allows the configuration of various recirculation flows to be defined by the recirculation partial flow of recirculation, in particular the configuration of the recirculation flows required for each set of quantities of fuel and combustion air.

For this reason, it is particularly advantageous for the flow stabilizer member to extend over a maximum length of about one-sixth the distance between the diaphragm and the root zone of the flame.

The above details about the flow stabilizer element need not be respected in order to achieve a sufficient stabilization of the recirculation flows but always ensure that there is no risk of formation of soot deposits in the burner.

In particular, in order to avoid the formation of soot deposits in the combustion chamber as far as possible, it is expected that the combustion chamber will be constructed in such a way that its interior is free of any elements flow stabilization.

Concerning the issue of regulating the amount of air in the combustion air stream, no details have been reported so far. Thus, in an exemplary embodiment it is provided that for regulating the amount of air in the combustion air stream a regulating device is used. The control device is preferably constructed in such a way that, for the regulation of the amount of air, the point of entry of the combustion air flow into the combustion chamber remains unchanged in the radial direction relative to the jet of fuel. This has the great advantage that, by fixing the point of entry of the combustion air flow,

optimum recirculation for all fuel and combustion air quantity adjustments.

It has been found to be especially advantageous if the regulating device has fixed local openings for the combustion air flow which can be regulated so as to have different cross-sectional passageways.

This detail is suitably constructively resolved when the adjustment device has a rotatable regulating element supported on the diaphragm by means of which the free cross-sectional area of an aperture provided in the diaphragm can be regulated.

In the simplest case, the regulating element is constructed as a regulating disk which is rotatably supported on the diaphragm and which can assume various positions with respect to the diaphragm and therefore in relation to apertures in the diaphragm. This adjustment element can be made in such a way as to be able to take control positions with slight variations.

Alternatively, it is also advantageous that the adjusting member may be able to allow continuous adjustments so that the passage area between a maximum value and a minimum value can be continuously varied. The adjusting device may be made so that the adjustment is effected manually, for example by means of a suitable tool.

In the case of variable air quantity control, it is particularly advantageous if the control device is actuated by a controllable variable position drive. 22

As far as the possibility of regulation of the injector is concerned, no details have hitherto been given. Thus, in an example of an advantageous embodiment it is envisaged that the injector is a fuel return injector.

A fuel return type injector can be easily adjusted when an adjustable return valve is associated with the injector, which makes it possible to adjust the return flow rate of the injector and thereby regulate the amount of fuel exits the injector.

In the simplest case, the return valve is constructed so that, through it, fixed settings can be established for various amounts of fuel supplied by the injector. More advantageous however is the solution in which the return valve has a continuous adjustment, so that it is possible to make a continuous adjustment and adjustment of the amount of fuel.

In particular when the quantity of fuel must be controlled, it is advantageously provided that the return valve is regulated by means of a variable position drive.

In an example of an advantageous embodiment for the application of the solution according to the present invention, it is envisaged that the burner has a control by means of which the amount of fuel and the amount of air in the combustion air stream can be adjusted. With such a control, it is particularly easy to achieve optimum regulation of both the amount of fuel and the amount of combustion air, especially with a view to achieving combustion under or near stoichiometric conditions. 23

Advantageously, in this case, it may be envisaged that the control system commands the actuation of variation of positions of the adjustment device.

In the case of a control of only one or both of the position change actuators, it is conceivable to set the fuel quantity or the air quantity from the start and use the other variable position drive for the other variable, fine adjustment. It is especially advantageous, however, for the control system to control the variable position drives of both the return valve and the control device.

In addition, it is advantageous, in particular to ensure complete combustion of the fuel, that the control is associated with a probe which detects whether the combustion is being made completely.

In this way it is further possible to control the amount of air and the quantity of fuel to make the necessary adjustments for the combustion if it is done in or near stoichiometric conditions.

With regard to the burner powers previously established, a number of possibilities can be envisaged in applying a control according to the invention. Thus, in an example of an advantageous embodiment, it is envisaged that the burner power control may be pre-set to a fixed value. Alternatively it may also be thought of performing the control of the burner powers based on previously set values. 24

In an example of an advantageous embodiment it is foreseen that the control regulates, on the one hand, the amounts of fuel and air for a given pre-set power and, on the other hand, regulates the combustion in order to provide a combustion under the stoichiometric conditions or close to them.

In the examples of embodiments according to the invention it was assumed that the possibility of regulating the amount of fuel was possible by the injector itself.

Alternatively, in an example of an advantageous embodiment of the invention, it is envisaged that the amount of fuel is adjustable by means of a burner constructed as a set of mounting elements ("kit") installed in the same burner body and with different injectors. The amount of fuel is regulated by the commissioning of the corresponding nozzle installed in the burner.

Advantageously, it is envisaged that the nozzles all have the same spray profile, and in particular an outer contour of the essentially equal airflow, and only provide different amounts of fuel.

In addition, it is provided, in an example of an advantageous embodiment, that in regulating the amount of air it is adjustable in such a way that the burner, consisting of a set of nozzles, is constructed in such a way that, body, interchangeable parts can be installed to regulate the amount of air in the combustion air stream. Due to the fact that the different adjustment parts are provided, it is possible to regulate the combustion air flow. 25

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In this case it is particularly advantageous that, by means of the control pieces, the timed intake of the combustion air in the combustion chamber is also adjustable.

Advantageously, it is envisaged in this case that in all the control pieces at least one partial flow of the combustion air flow can be regulated. It is especially advantageous if the inflow point of the flow is the same for all control pieces.

In an example of an advantageous embodiment it is envisaged that in the regulating parts the near partial flow of the fuel jet is constant, whereas the partial recirculation stabilizing flow can be regulated to various values by means of different control pieces .

With regard to the constructive solution, in an example of a particularly advantageous embodiment, it is envisaged that the set of mounting parts, for all the burner powers, includes an identical burner body.

In particular, it is anticipated that the set of mounting parts will include an identical fan for all burner powers.

In addition, it is advantageous that the assembly of assembly pieces includes in all cases an identical combustion chamber.

Finally, it is advantageous that the set of mounting parts, for all the powers include a same nozzle holder. 26

Other features and advantages of the solution advocated by the invention are the subject of the following description as well as the drawings referring to some examples of embodiments.

Furthermore, the aim proposed at the outset is achieved by the adoption of a method of operating a fluid burner which corresponds to the features set forth in claim 53.

An improved version of the method of operation according to the invention provides for openings in the burner body through which an external recirculation flow enters the combustion chamber and includes cold combustion gases, the external recirculation flow between the combustion chamber in the vicinity of the separation element and is maintained at such a level as to cause the flame of a blue flame to remain at a distance of at least 1 cm from the nozzle and injector and the root of the flame, there is an area where the fuel jet is not burning and, by the action of the combustion air, it expands into a cone.

Another improved and advantageous form of the process of operating a burner according to the invention provides that in the burner body there are openings through which a recirculation flow containing cold combustion gases passes and enters the combustion chamber in the vicinity of the separating element, that, by means of this flow, the internal recirculation flow is protected with respect to the separating element, which flow inside the combustion chamber takes the form of a flow that recedes from the blue flame zone to the part where the fuel jet is not burning. 27

Fig. 1 is a longitudinal section of an exemplary burner of one embodiment of the present invention; Fig. 2 is a partial longitudinal section of an injector according to the present invention, Fig. 3, an enlargement of the front zone of the injector shown in Fig. 2, Fig. 4, a section along the line IV-IV of Fig. 3, Fig. 5, a section through the line VV of Fig. 1, in the case of partial flow FIG. 6 is a section similar to that of FIG. 5 with a reduced recirculation stabilizing flow, with the regulating disk partially seen in withdrawal, FIG. FIG. 7 is a section similar to that of FIG. 5 in the case of a partial recirculation stabilization partial flow, FIG. 8 shows a perspective view of the proportions in the combustion chamber with the flame tube partially started, FIG. 9, an enlargement of the cutout shown in Fig. 1 FIG. 10 shows an enlargement of a section detail shown in FIG. 1 in the diaphragm region in the case of maximum recirculation stabilizing flow in the region of the diaphragm in the case of maximum partial recirculation stabilizing flow; FIG. lower half. FIG. 10 is a section similar to that of Fig. 1 of a burner according to a second example of the embodiment of the invention; Fig. 11 is a section similar to that of Fig. 1 of a burner according to a third embodiment of Fig. Fig. 12 is a section similar to that of Fig. 1 of a fourth example of an embodiment of the invention, Fig.

Fig. 13 is a section similar to that of Fig. 1 of a fifth example embodiment of the invention, Fig. 14 is a section similar to that of Fig. 1 of a burner according to a sixth example of embodiment Fig. 15 is a section through line XII-XII of Fig. 14 in the case of a maximum partial recirculation stabilizing flow and of the diaphragm provided for the adjustment thereof, Fig. 16, a cut similar to that shown in Fig. 15 with a diaphragm applied to provide a reduced recirculation stabilization flow, Fig. 17 is a section similar to that shown in Fig. 15 with a diaphragm applied so as to provide a reduced recirculation partial stabilization flow to zero.

A first exemplary embodiment of the burner according to the invention shown in Fig. 1 comprises a burner body generally indicated by reference 10, with a support tube 12 and a flame tube 14 connected to the first.

In the support tube 12, at the end opposite the side where the flame tube is located, there is disposed a fan generally indicated by the reference 16 which has a drive 18 and a rotor 20. This fan 16 generates an air flow 22 which passes along the support tube 12 and is directed towards the flame tube 14.

In addition, within the support tube 12, there is a nozzle holder generally indicated at 24 which comprises a nozzle holder 26 with a nozzle screwed thereto. The injector is constructed as a return injector, as will be explained in more detail below, and is fed with a liquid fuel, in particular oil, by means of a

supply piping 30 while, via a return line 32, part of the fuel passed through the feed line 30 is returned, the return flow rate being regulated by a return throttling commanded by a return valve 34 installed in the feed line 30. return of the tubing 32. The fuel feed in the nozzle feed pipe 30 is effected by means of a fuel pump 36 which is preferably driven together by the drive 18 of the fan 16, in particular by the same shaft. This fuel pump 36 is fed with fuel through a fuel inlet line 38 and is furthermore connected to a return line 40 in which the excess fuel supplied by the fuel pump 36 flows. return pipe 40 also opens the return pipe 32 which is installed downstream of the return valve 34. The nozzle head 50 is also in turn screwed onto the nozzle holder 26 so that the nozzle body 52 is placed in a recess 56, the recess 56 forming a fuel conduction zone 58 which is connected to the inlet 30 of the injector and a return zone 60 which is connected to the return line 32 of the injector. The fuel entering the fuel feed zone 58 preferably passes through a filter 62 and then flows through two inlet channels 64, located at diametrically opposed points, opened in the nozzle body 52, into the fuel supply channels 58, inlet ports 64 open in the vortex body 54 and as shown in Fig. 3 to an annular inlet chamber 68 of the vortex body 54 which is capped by a platen 70 which closes the top of the vortex body 54. Inlet annular chamber 68 the fuel passes through 30

of swirl channels 72 to a swirling inlet chamber 74, situated within the annular inlet chamber 68, in which turbulent flows are formed which are in agreement with the direction of the swirling channels and, from this swirl chamber 72, the fuel passes through a slit peripheral ring 76 to a spray bore 78 from which a conical shaped jet of fuel 80 emerges.

In front of the spray bore 78 there is a return channel 82 which flows through the turbulence body 54 and is in communication with a return channel 84 provided in the nozzle body 52 which eventually opens into the turbulent body 54. the return zone 60 of the recess 56, which in turn is in communication with the return line of the injector 32.

Further details of the injector 28 applied in the present invention can be seen from the German patent 42 15 122 to which, in this context, reference is made in full. The injector holder 24, including the injector 28, is disposed within an antechamber 48 forming part of the antechamber support tube 12 which is also traversed by the airflow 22. The antechamber 48 is covered by a diaphragm, marked generally by reference 90 which is installed in the support tube, a combustion chamber 92 being enveloped by the flame tube 14 is located downstream of the injector 28. The flame tube 14 is preferably also supported by the support tube 12 The diaphragm 90 is arranged such that the spray hole 78 is in the vicinity or even in the plane 89 of 31

a jet through aperture, open in the diaphragm, from which the jet of fuel 80, which exits the injector 28, expands substantially completely into the combustion chamber 92.

To this end, the diaphragm 90 is provided with an inlet port 94, coaxial with the longitudinal axis of the injector. The inlet aperture 90 further has a size chosen such that, between an edge 96 of the inlet aperture and an outboard side 98 of the nozzle head 50, facing this edge 96, a port 100 is opened through from which passes a fuel-jet partial flow 102 which is coupled to a flow of combustion air passing from the antechamber 48 to the combustion chamber 92.

To reduce the velocity of the partial flow 102, the edge 96 of the flow inlet 94 has an edge 104 which introduces a swirling disturbance, which causes swirls to form in the partial flow 102 and is configured, for example, as a step provided in Inlet opening 94.

Another partial combustion air stream 106 exits the antechamber 48 and enters the combustion chamber 92 through apertures 110, disposed in an annular zone 108 surrounding the inlet opening 94, the centers of which are on a primitive circumference 109 and divide the zone 108 in sectors with a constant angle, leaving intermediate spaces 111, equidistant from the center of the annular zone 108.

Preferably, the apertures 110 are distributed along the primitive circumference 109 in an azimuthal direction corresponding to an angle of magnitude equal to one to two times the length of the intermediate spaces 111.

The apertures 110 may, however, extend in the azimuth direction, over an angle which is approximately 0.1 to 9 times, the angle encompassed by the intermediate spaces 111.

The openings 110 are then arranged such that the partial flow 106 of the combustion air stream, by effect of the intermediate spaces 111 between the inlet openings 110, takes the form of an interrupted peripheral flow entering the combustion chamber 92 by creating an inner recirculation flow 112 and an outer recirculation flow 119 stabilized in the combustion chamber 92 so that flame base 114 of the flame 116 is formed which is formed inside the combustion chamber 92, at substantially the same distance of the diaphragm 90 regardless of the amount of fuel introduced by the fuel jet 80 and the corresponding amount of combustion air introduced by the partial flows 102 and 106 in the combustion chamber 92.

The flows according to the invention occurring inside the combustion chamber 92, shown in Figure 8, thus comprise the jet of fuel 80 in the form of a complete cone, cylindrical, circumferential partial flows 102 , which enter the combustion chamber 92 in a direction 103, which is parallel to the direction 79 of the fuel jet 80. In addition to the recirculation stabilizing partial flow 106 having a direction 107 parallel to the direction 79 of the fuel jet 80, flow, enter the combustion chamber 92, individual streams 105, the individual streams 105 being distributed over a circular base cylinder which, in cross section, in the region of the diaphragm 90, take the form of a circular annular zone 108 and are maintained fixed as a consequence of the positioning of the primitive circumference 109, concentric with the mantle. 33

r The root of the flame 114 is in turn connected to an unlit portion 81 of the fuel jet 80 having a length of about 1 to 4 cm, preferably 1 to 3 cm, and, from this point, the flame 116 expands along the inner wall 15 of the flame tube 14, to which it slopes before it exits outwards. The zone 92 of the combustion chamber between the diaphragm 90 and the zone 15 of the inner wall to which the flame abuts forms a so-called recirculation space 91. In this space there flows, on the one hand, an inner recirculation 112 of hot gases which occurs between the flame tube 14 and the partial flow 106, which recedes towards the diaphragm and, in front of the diaphragm 90, flows inwardly, passing through the flow 105 towards the unlit part 81 of the jet of fuel 80 in order to heat the unlit part of the fuel, towards the root of the flame 115, and also the combustion air.

In addition, following the diaphragm 90, also enters the flame tube 14 cold combustion gases admitted into the recirculation chamber 91 through recirculation openings 118, coming from a boiler, in the form of recirculation flow 119 that significantly prevent a contact between the hot gases of the inner recirculation flow 112 and the cold diaphragm 90. The outer recirculation flow 119 lies with the individual stream 105 just ahead of the diaphragm and is mixed at that time with the combustion air stream 102, 106 in order to increase the mass flow through the tube of flame 14 to a point where the root of the flame 114 is maintained at a constant distance of at least 2 cm from the diaphragm 90 and thus is also immobile relative to the injector 28 so that the non-illuminated part 81 of the fuel jet 90 34

be sufficiently long so that the fuel droplets there are completely vaporized.

Advantageously, the sum of the areas of the surfaces of the combustion air inlet openings in the combustion chamber, in particular the sum of the areas of the inlet openings 110 with that of the inlet openings 94 is such that at most it is equal to sum of the areas of the recirculation openings for the outer recirculation and in particular corresponds to the sum of the areas of the longitudinally open traces on the periphery constituting the recirculation openings 118. The ratio between the area of the recirculation openings 118 and the area of the opening central input 94 is between about 0.3 and about 19.2, preferably between about 0.9 and 5.1. The flame tube 117 is then connected to the recirculation chamber 91.

Advantageously, in the first exemplary embodiments, shown in Figures 1 to 9, the partial flow 102 near a jet of fuel is constructed such that that flow, even for the lowest burning power, the corresponding recirculation , without the stabilizing recirculation flow 106 remaining stable (Fig. 9 lower half) and for large firing powers the recirculation stabilizing partial flow 106 assuming the role of the stabilization (Fig. 9, upper half) for the which partial flow 102 near a jet of fuel is no longer able to satisfy.

With other burner sizes it is also possible, in the case of low firing power, to provide 35

both partial streams 102 close to fuel jets and also a minimum recirculation flow 106.

Stabilization of the recirculation flows 112, 119 of this type can be achieved when, for example, the outside diameter of the recirculation chamber 91 of the combustion chamber 92 is approximately 1.5 to 3.9 times the inner diameter of the combustion chamber 92. flame 92 or even better two to three times the diameter of the primitive circumference 109 of the annular zone 108 or even better that the inner diameter of the recirculation chamber 91 of the combustion chamber 92 is approximately 2.2 to 2.6 times or even better about from 2.2 to 2.5 times the diameter of the partial flow 109. The ratio of the diameter of the primitive circumference 109 to the diameter of the inlet central opening 94 is between about 1.0 and 4.2, d preferably between about 2.6 and 4.0 or more preferably between about 2.8 and 3.5 and preferably between about 1.82 and 2.0.

Furthermore, it is advantageous for the diameter of the inlet opening of the flow 94 to be dimensioned such that the outside diameter of the recirculation chamber 91 of the combustion chamber 92 is approximately 3.4 to 8.5 times or better about 4 to 6 times or better still 4.4 to 5.9 times the diameter of the central inlet opening 94. The ratio between the diameters in which the blue flame burner is adjustable according to the invention and may still be in operation for all power ranges are summarized in Table I where the outer diameter of the recirculation chamber 91 corresponding to the inner diameter of the flame tube is designated &quot; flame tube 14 &quot; the diameter of the primitive circumference designated 36

$ I

&numsp; &numsp; &numsp; &numsp; &numsp; &numsp; &numsp; &numsp; &numsp; &numsp; &numsp; &numsp; &numsp;

Preferred ranges of the ratio between stepped diameters according to the individual firing burner powers are shown in Table II, with the burner working with these diameters with very low emission rates. The optimum emission values are achieved when the values of the ratios between diameters in Tables III and IV are adopted.

In order to adjust the amount of combustion air in the combustion air flow to different burner powers, there is provided a regulating device generally indicated by the reference 120 in Figs. 5 to 7, said regulating device comprising a regulating disc 122 having a circular shape having apertures 124 equal to the apertures 110 and being distributed at the same angular distances as the apertures 110 and the same distance from the center of the implantation circumference 108 of these openings. The regulating disk 122, in a circular fashion, is in turn located, as can be seen in enlargement in Fig. 9, inside a cylindrical cavity 126 provided in the diaphragm 90, opened on the side of the antechamber 48. The guide in rotation of the adjusting disk is made by the seating of its outer edge 128 on a cylindrical inner edge 130 of the cavity 126. The adjusting disc 122 may be adjusted such that, as shown in Figs. 5 through 7, or the apertures 124 are aligned with the apertures 110 so as to have the maximum cross-section of the partial flow 106 passing through each of the apertures 110, or are rotated so that the apertures 124 leave to be aligned with the 37

7, and only the portions of the overlapping openings 110 and 124 allow partial flow 106 to pass, causing the amount of air in the partial flow 106 to be reduced, as seen in Fig. 6. The flow can be completely interrupted, as shown in Fig. 7, i.e. when the apertures 124 are closed, become capped by the spaces between the apertures 110.

In order to rotate the adjusting disk it has, at a part of its periphery, a pinion 132 in which it engages the cog 134 of a control gear generally indicated by the reference 136, which is part of the adjusting device 120. This adjusting gear , on the other hand, is supported on the diaphragm 90 so as to be able to rotate and, in the simplest case, is placed in a further cylindrical bearing cavity 138 provided in the diaphragm 90, the abutment 134 being supported by the abutment on the wall cylindrical portion 140 of the bearing cavity 138. In this case, the bearing cavity has a through aperture 138 which is in communication with the antechamber 48.

Both the adjusting disk 122 and the adjusting gear 136 are supported in the corresponding cavities 126 or 138 by means of elements, not shown in Fig. 9 which means that they are seated in the bottom of the cavities.

In the case of the first embodiment, the adjusting gear 36 is self-supporting in the bearing cavity 138 and, for example, is provided with a slot 142 which allows, by means of a standard screwdriver, to rotate the adjusting gear 136 so that by this process the adjustment disc 122 can be adjusted, the setting of the adjustment disc being in each case ensured by the position occupied by the adjusting gear 136. 38 ν:

The operation of the first exemplary embodiment is such that with a partial flow 106 interrupted the amount of burning air is only that which is supplied by the partial flow 102 passing through the passage 100 in the outlet. combustion chamber 92. Corresponding to this amount of air is the regulation of the amount of fuel supplied by the injector 28 to the fuel jet 80, the amount of fuel being regulated in such a way that the flame 116 blazes with a blue color, making this adjustment so that the burning takes place under or near stoichiometric conditions. This regulation of the amount of fuel is effected by the regulation of the return valve 34 and therefore by regulating the fuel flow returning from the injector 28 through the return line 32 towards the return line 40.

In the case of larger powers, by regulating the regulating disc 122, it is possible to make an additional combustion air inlet for the partial flow 102 which will aid the partial flow of air 106, this partial flow 106 being in the case of powers in the case of the maximum amount of combustion air in the partial flow 106, in the passage from the pre-chamber 48 to the combustion chamber 92, there is an inlet area for the flow of combustion air which is approximately five times that available when the partial flow 106 is completely prevented from forming.

A further regulation of the amount of fuel which is introduced by the injector 28 into the fuel jet is effected by the aforesaid regulation of the return valve 34, the throttling of the passage of the fuel returning from the injector 28 varying.

In all burner power settings according to the invention, the distance between the flame root 114 of the flame 116 and the diaphragm 90 is substantially constant and at all burner power settings combustion can always be achieved under the conditions stoichiometric or near them.

In a second example embodiment of the burner according to the invention, shown in Fig. 10, parts identical to those of the first example are indicated with the same reference numerals. With respect to these parties, therefore, the first example of embodiment may be fully reported.

Contrary to the first exemplary embodiment, which has no additional flow guiding element in the combustion chamber 92, in this second embodiment example there is provided a flow guiding ring 150 which is arranged at a certain distance of the diaphragm 90, its edge 152 having a maximum distance of up to a quarter of the distance between the diaphragm 90 and the root 114 of the flame 116. In addition the flow guiding ring 150 has, on the side of the diaphragm 90, an edge bottom portion 154 disposed a distance away from the diaphragm 90 so that the recirculation flow 112 may enter the space between the edge 154 and the front portion 156 of the diaphragm, through the diaphragm 90, and then into the flow guide ring 150. The flow guide ring 150 serves at the same time to further stabilize the recirculation flow 112, for which purpose it is necessary to maintain a significant distance between the air this front 152 and the root 114 of the flame 116 and, for different burner power settings according to the invention, ensure a strong flow of 40

recirculation valve 112 and protect the effectiveness of the partial flow 106 which stabilizes the recirculation.

Preferably, the flow guiding ring 150 is supported on the diaphragm 90 by feet 158.

In a third exemplary embodiment of the burner according to the invention, shown in Fig. 11, parts identical to those used in the first exemplary embodiment are indicated by the same references whereby, with respect to these parts, one may also make full reference to the construction of the first exemplary embodiment. Contrary to the first example of an embodiment, in this case, for regulating the return valve 34 a regulating drive 160 is provided and for actuating the adjusting gear 136 a regulating drive 162 is provided, both of which are controlled by a command ate 164. To this control 164 are associated, through the burner power input 166 according to the invention, the control 164 through the input 166 receiving the data for each setting of the return valve 34 and the drive regulating device 162 of the regulating device 120. For example, this can be achieved by means of storage in the command 164 of previously selected conditions of the regulating drives 160 and 162. In order to further ensure that the flame 116 corresponds to the stoichiometric conditions the combustion of or near the combustion of the fuel represented by blue flame combustion, is a Lambeda probe 168 is further provided in the flue gas outflow from the flame 116 which in turn is connected to the mode 164 controller 164

the control, after a gross power adjustment by means of the regulating drives 160, 162 is additionally still able to fine-tune the amount of combustion air or the quantity of fuel in order to maintain the conditions stoichiometric or near combustion. The control 164, in the most simplified case, is constructed so that by means of a control command, for example manual, it provides the desired power in the burner according to the invention.

In an improved embodiment of the third exemplary embodiment, control 164 is constructed so that, via the general control of an installation, for example a heating installation in which the burner according to the invention is integrated, there is data previously chosen for the required powers in the burner according to the invention so that the control 164, according to the power required in the burner according to the invention, actuates correspondingly the regulating drives 160, 162 and makes a fine adjustment based on the values measured on the Lambeda 168 probe.

In a fourth embodiment example, shown in Fig. 12, parts identical to those of other already described embodiments are indicated by the same reference numerals so that, as to the description thereof, there is made full reference to those embodiments .

Contrary to the other exemplary embodiments the flame tube 14, of the flame space 117 which lies ahead of the recirculation space 91, is tapering radially along a given length until it reaches the diameter of the end so that the region 15 of the inner wall to which the flame 116 abuts is already radially reduced with respect to its inner dimension.

This flame tube allows to achieve, in particular in the case of reduced burner powers, preferably less than 20 kW, a flame 116 stable in the flame tube 14. In addition this geometry avoids undesirable suctioning of combustion gases from of the front end of the flame tube 14.

In a fifth example of embodiment, shown in Fig. 13, likewise parts identical to those existing in the previous embodiments are indicated by the same references, also making reference to the already made descriptions.

Contrary to the examples of prior embodiments, the closures of the apertures 110 are made by means of tapered buffers 172 which are supported by bars 174 and can be moved axially along the axis of the support tube 12 with the aid of guides 176 which slide over the injector holder 24, located inside the support tube 12. As the plugs 172 are further inserted into the apertures 110, the free area of the cross-section of each aperture 110 can be reduced.

In a sixth exemplary embodiment of the burner according to the invention, shown in Fig. 14, parts identical to those shown in the first exemplary embodiment are indicated by the same references so that as far as the description of such parts is concerned, to the description of the first example embodiment. 43

Contrary to the first exemplary embodiment, in the sixth example of embodiment, shown in Figs. 14 to 17, although it is also possible to make a power adjustment, in this example embodiment of the burner according to the invention, the construction is designed as a set of kit parts. Instead of an injector 28 constructed with a return pipe 32 with fuel return from the injector and a return valve 34 for regulating the fuel flow, in this case there is provided a set of several injectors 228 which have the same shape of spray and the same outer contour with respect to the air flow and thus have shapes equal to those of the fuel jets 80 but nevertheless provide different amounts of fuel. In these nozzles 228 the fuel feed does by means of a fuel feed pump 36 and the fuel supply line 30, however, a return line 32 having been dispensed with.

The different nozzles 228 correspond in this case to the various required powers of the burner according to the invention.

To adjust the combustion air flow to the different fuel quantities of the various injectors 228 various diaphragms 290a to 290c are provided, the diaphragm 290a corresponding to the greater amount of fuel supplied by the injector 228 and the diaphragm 290c to the smaller amount of fuel supplied by the injector and the diaphragm 290b to an injector 228 whose quantity of fuel supplied is between the maximum and minimum amounts.

The diaphragms 290a to 290c are differentiated by the intended cross-section of the apertures 210 of the partial flow 106, the apertures 210a being identical to the apertures 110 in which 44

with respect to the cross-sectional areas while the apertures 210b have a total cross-sectional area representative of an intermediate position shown, for example, in Fig. 6 and thus also of an intermediate power of the corresponding nozzle 228. In the case of the diaphragm 290c the apertures 210 have completely disappeared so that it corresponds to a position of the regulating device 120 shown in Fig. 7 in which the partial flow 106 is completely prevented from forming and the combustion air stream is formed only by partial flow 102. Each injector 228 mounted on the injector holder 24 corresponds to a diaphragm 290a to 290c to be mounted to the support tube 12, the diaphragm 190 of the fourth embodiment example being supported by the support tube in a collapsible manner. To this end, a tripod 294 is supported by the injector holder 24 by means of a support ring 292, the diaphragm 290 being chosen, propelled towards the flame tube and thus being tightened by the tripod at its side 296 facing for the antechamber 48, and on the other side by a sealing ring 298. Thus, the injector holder 26 can slide as a set along the longitudinal axis 300 of the support tube 12 and can be pressed by a spring, not shown in Fig 14 towards the flame tube 114. In this way, the diaphragm 290 can be withdrawn towards the antechamber while the diaphragm 290 is pressed towards the flame tube 14 and is secured to a counter-support constituted, for example by a sealing ring 298.

In addition, the combustion chamber 92, as advantageous and shown in correlation with the first exemplary embodiment has a construction free of any mechanical fluid guiding elements so that, upon the installation of a nozzle 228 corresponding to required power and 45

the respective diaphragm 290 ensures proper recirculation flow stability 112 and likewise ensures that the flame 116 is formed by a combustion having the characteristics of a blue flame, that is formed at or near stoichiometric conditions. Moreover, by the free areas of the cross-section of the openings 210 made available for forming a partial flow 106, operation corresponding to that of the embodiment exemplified in the first exemplary embodiment is ensured.

Table I

Power 1 Primitive Circumference (109) Inlet Opening (94) 1.0 - 4.2 2 Flame Tube (14) Primitive Circumference (109) 1.7 - 3.9 3 Flame Tube (14) Inlet Opening 94) 3.4 - 8.5 4 Trace area (118) Inlet opening (94) 0.3 - 19.2 46

Table II

Potentia 4-10 kff 10-20 kw 20-30 kw 30-40 kw 40-50 kw 50-60 kw 60-70 kw 70-80 kw 80-90 kw 90-100 kw 1 Preference Circumference HW) 94) 1.8 + 20% 1.8 + 20% 2 + 20% 2.30 + 20% 2.3 + 20% 2.0 + 20% 2.0 + 20% 1.8 + 20% 1 , 82: 20% 1.8+ 20% 2 Flame Tube Π4 prim Primitive Circumference (109) 2.4 + 15% 2.4 + 15% 2.4 + 15% 2.4 + 15% 2.4 + 15 2.4 + 15% 2.4 + 15% 2.4 + 15% 2.4 ± 15% 3 Flame pipe (14 &quot;) Inlet opening (94) 4.4 + 20 % 4.4 + 20% 5.9 + 20% 5.5 + 20% 5.5 + 20% 4.4 + 20% 4.4 + 20% 3.5 + 20% 3.5 + 20% 3 , 3 + 20% 4 Area of features (Ί181 Entrance opening (94) 0.9 + 20% 2.0 + 20% 5.0 + 20% 5.7 + 20% 4.1 ± 20% 4.3 + 20 % 3.8 + 20% 3.8 + 20% 3.5 + 20% 3.5 + 20%

Table III

Power 4-10 kw 10-20 kw 20-30 kw 30-40 kw or 7 * o * * · 50-60 kw 1 Ordinary circumference Π09) Inlet opening (94) 1,8 1,8 2,5 2, 5 2.0 2.0 2 Flame tube (14) Primitive circumference (109) 2.4 2.4 2.3 2.3 2.2 2.2 3 Flame pipe (14) Inlet opening (94) 4.4 4.4 5.9 5.9 4.4 4.4 4 Routing area (118) Ingress opening (94) 0.9 2.1 5.0 5.8 4.1 5.0 47

Table IV

Power 4-10 kw 10-20 kw 20-30 kw 30-40 kw 40-50 kw 50-60 kw 1 Limiting Circumference (109) Inlet opening (94) 1.82 1, 82 2.69 2.69 2 , 00 2.0 2 Flame tube (14) Primitive circumference (109) 2.47 2.47 2.20 2.20 2.20 2.20 4 Flame pipe (14) Inlet opening (94) 4, 48 4.48 5.92 5.92 4.40 4, 40 4 Area of ratios (118) Inlet opening (94) 0.93 2.09 5.00 5.83 4.17 5.08

Lisbon, 14 May 2001.

48

Claims (34)

A fluid burner comprising a burner body (10) including a support tube (12) with an antechamber (48) and a flame tube (14) connected thereto, a nozzle holder (24) disposed within the interior of the antechamber 48 with a nozzle 28 producing a jet of fuel 80, a combustion chamber 92 disposed within the flame tube 14 in which the fuel jet 80 a separation member 90 with a central aperture 94 through which a jet of fuel passes 80 is located between the antechamber 48 and the combustion chamber 92, the combustion chamber 92 is connected to the separating element 90, a blower 16 for generating a flow of combustion air entering the combustion chamber 92 and of which a partial flow 102 is formed. ) next to the fuel jet, wherein in the combustion chamber (92) the fuel is burned with a blue flame (116) in or near the stoichiometric combustion conditions, characterized in that, in the combustion chamber (92), in addition to the partial flow (102) of the fuel jet also enters a certain distance from the first, a partial flow ( 106), by the recirculation stabilizing partial flow stream (106) entering the combustion chamber (92), with a flow profile corresponding to the shape of an annular flow interrupted at the periphery, by the combustion chamber (92) forming a flow of 1 recirculation flow (112) which recedes from the blue flame zone (116) to the non-burning portion (81) of the fuel jet (80) and that the recirculation flow recirculation (106) of the combustion air stabilizes the recirculation flow (112). Burner according to claim 1, characterized in that apertures (118) are provided in the burner body through which a recirculation flow (119) containing cold combustion gases passes and enters the combustion chamber (92) , in that the outer recirculation flow (119) enters the combustion chamber (92) in the vicinity of the separation element (90) and has a dimension such that the flame root (114) of the blue flame (116) is at a distance of the injector 28 of at least 1 cm and between the nozzle 28 and the root of the flame 114 there is a part 81 which is not burning from the jet of fuel 80 and mixing with the combustion air (102, 106), expands in the form of a cone. Burner according to claim 1 or 2, characterized in that openings (118) are provided in the burner body (10) through which an external recirculation flow (119) including cold combustion gases enters the combustion chamber ( 92, in that the outer recirculation flow (119) enters the combustion chamber (92) in the vicinity of the separation element (90) and by that flow protecting the inner recirculation flow (112) relative to the separating element (90 forming a stream which, within the combustion chamber 92, recedes from the blue flame 116 to the non-burning part of the fuel jet 80. 2 Burner according to one of the preceding claims, characterized in that the inner recirculation flow (112), from the flame (116), flows over the inner side of the flame tube (14) towards the separating element (90). Burner according to one of the preceding claims, characterized in that the inner recirculation flow (112) has a yellow flame. Burner according to one of the preceding claims, characterized in that the internal recirculation flow (112) traverses the partial recirculation stabilizing flow (106). Burner according to one of the preceding claims, characterized in that the recirculation stabilizing partial flow (106) enters the combustion chamber (92) in a direction essentially parallel to the direction of the stream (79) of the fuel jet (80). Burner according to one of the preceding claims, characterized in that the partial flows (102, 106) either enter the combustion chamber (92) at the same point independently of the air quantity adjustments. Burner according to one of the preceding claims, characterized in that, in order to adjust the quantity of air, at least one of the partial flows (102, 106) is adjustable in order to adjust the system to the quantity of fuel. 3 Burner according to claim 9, characterized in that the partial flow (106) is adjustable with respect to the quantity of air. A burner according to claim 10 characterized in that the amount of air in the recirculation stabilization flow (106) is maximum for the maximum amount of fuel and minimum for the minimum amount of fuel. Burner according to one of the preceding claims, characterized in that the amount of air in the partial stream (102), close to the fuel jet, is constant for all fuel quantity adjustments. Burner according to one of the preceding claims, characterized in that the jet of fuel expands into a cone depending on the opening of the injector. Burner according to one of the preceding claims, characterized in that the partial flow (102) proximate the fuel jet enters the combustion chamber (92) in a direction parallel to the direction (79) of the fuel jet (80). Burner according to one of the preceding claims, characterized in that the partial flow (102) proximate the fuel jet enters the combustion chamber (92) surrounding the fuel jet (80). % A burner according to claim 15, characterized in that the partial flow (102) proximate the fuel jet enters the combustion chamber through an area of a periphery (228). Burn through c (92) inje (94) of c or 19 20. The combustion chamber according to Claim 16, characterized in that the combustion chamber (70) comprises a partial flow (102) near the fuel jet along an outer profile (98). ) as defined in claim 15, characterized in that the partial flow (102) and the jet of fuel (80) pass into the combustion chamber (92) through the same inlet port ( 94) according to claim 18 characterized in that the partial flow (102) enters the combustion chamber through a passage (100) between the head of the torch (28, 228) and the edge of an inlet opening of the partial flow (102) proximate the fuel jet according to the claimed claims in that the inlet port (94) for the flow (102) is configured to create turbulence. according to claim 20 characterized in that the inlet opening (94) is provided with an edge which gives rise to turbulence. according to one of the preceding claims, characterized in that the total combustion air flow (102) passes through an antechamber (48). Burner according to claim 22, characterized in that the air flow (102, 106) enters the combustion chamber (92) through a separating element (90). Burner according to claim 23, characterized in that the separating element (90, 290) has an inlet opening (94) facing the injector (28, 228) for passing the partial flow (102) near the jet of fuel. Burner according to one of Claims 22 to 24, characterized in that the separating element (90, 290) with respect to the inlet opening (94) for the partial flow (102) near the fuel jet has an outer opening (110 , 210) positioned radially for passage of the partial recirculation stabilizing flow (106). Burner according to one of the preceding claims, characterized in that the combustion chamber (92) extends from a plane (89) which is in the vicinity of the nozzle opening. Burner according to one of the preceding claims, characterized in that the combustion chamber (92) has a substantially constant cross-section between the separating element (90) and the flame root zone. Burner according to one of the preceding claims, characterized in that the separating element is a diaphragm Burner according to one of the preceding claims, characterized in that the diaphragm (90) lies on a plane (89). 6 - ~ 7 A burner according to one of the preceding claims, characterized in that the combustion chamber (92) has a recirculation space (91) surrounding a part (81) of the fuel jet (80) which is not burning and is passed through for this. Burner according to claim 30, characterized in that the recirculation space (91) extends at least to the root of the flame (114). A burner according to claim 30 or 31, characterized in that the partial flow (106), which promotes the stabilization of the recirculation, enters the recirculation space (91). Burner according to one of the preceding claims, characterized in that the partial flow (106) which promotes and stabilizes the recirculation is symmetrical with respect to an axis of symmetry of the combustion chamber (92). Burner according to one of the preceding claims, characterized in that the partial flow (106), which promotes recirculation stabilization, enters the combustion chamber (92) with a flow profile in the form of a lying cylinder. A burner according to claim 34, characterized in that the flow profile is composed of parallel individual streams (105). Burner according to claim 35, characterized in that the individual streams (105) are arranged at angular distances (111) which are constant with respect to one another. 7 Burner according to claim 36, characterized in that the ratio between the angular distance (111) between two individual flows (105) and the angular cross-section (110) of each individual flow (105) is approximately between 10 and 0.1. Burner according to claim 37, characterized in that the ratio between the angular distance (111) between two individual flows (105) and the angular width of the cross-section of the inlet (110) of each individual flow (105) is approximately between 1.5 and 0.1. Burner according to claim 38, characterized in that the ratio between the angular distance (111) between the individual flows (105) and the angular cross-section (110) of each individual flow (105) is approximately 0, 7 and 0.25. Burner according to claims 33 to 39, characterized in that the cylinder is a circular cylinder defined by a primitive circumference (109) situated in the middle thereof. A burner according to claim 40, characterized in that the recirculation space (91) has an outer diameter equal to 1.5 to 3 times the diameter of the circumference (109) of the circular cylinder. &amp; The burner according to claim 41, characterized in that the recirculation space (91) has an inner diameter approximately 2 to 2.5 times the diameter of the circumference (109) of the circular cylinder. 8 Burner according to claim 42, characterized in that the recirculation space (91) has an inner diameter approximately equal to 2.4 times the diameter of the circumference (109) of the circular cylinder. Burner according to claims 30 to 43, characterized in that the flame space (117) is connected to the recirculation space (91). Burner according to claim 44, characterized in that the flame space (117) has an inner diameter smaller than that of the recirculation space (91). A burner according to claim 45, characterized in that the inner diameter of the flame space (117) is 0.6 to 0.9 times the inner diameter of the recirculation space (91). Burner according to claim 46, characterized in that the inner diameter of the flame space (117) is approximately 0.8 times the inner diameter of the recirculation space (91). Burner according to one of the preceding claims, characterized in that the flame (116) has a flame root (114) within the combustion chamber (92). Burner according to claim 48, characterized in that the combustion chamber (92) extends beyond the root of the flame (114). Burner according to one of the preceding claims, characterized in that the outer recirculation flow (119) enters the combustion chamber (92) separate from the combustion air stream (102, 106). A burner according to claim 50 characterized in that the outer recirculation flow (119) enters directly into the combustion chamber (92) through apertures (118) in the flame tube (14). Burner according to one of the preceding claims, characterized in that the area of the openings (94, 110) provided in the combustion chamber (92) for inflow of the combustion air stream (102, 106) is at most approximately equal to area of the recirculation openings (118) provided in the flame pipe (14) for the outer recirculation flow (119). Method of operating a burner for fluid media comprising a burner body (10) having a support tube (12) with an antechamber (48) disposed therein and a flame tube connected to the support tube, a door (24) with an injector (28) producing a jet of fuel (80), a combustion chamber (92), located inside the flame tube (14), essentially without the characteristics of a mixing tube, within the (80) expands a separating member (90) with a central aperture (94) through which the jet of fuel passes (80) and is located between the antechamber (48) and the combustion chamber combustion chamber (92), the combustion chamber (92) being connected to the separation element, a blower (16) for generating a flow of combustion air entering the combustion chamber (92) and including a partial flow (102) proximate the fuel jet, wherein the fuel burns in the chamber combustion conditions with a blue flame (116), essentially at or near the stoichiometric combustion conditions, characterized in that, in the combustion chamber (92), in addition to the partial flow (102) proximate the fuel jet, of the recirculation (106) located radially at a certain distance and in a certain external position relative to the first partial flow, in that the recirculation partial flow of the recirculation enters the combustion chamber with a flow structure corresponding to an interrupted annular flow, by the combustion chamber 92 to create an internal recirculation flow 112 which recedes from the blue flame 116 to the non-burning portion 81 of the fuel jet 80 and, with the aid of the partial recirculation stabilizing flow 106, which is part of the combustion air, the internal recirculation flow 112 is stabilized. The method of operating a burner according to claim 53 characterized in that apertures (118) are provided in the burner body through which a recirculation flow (119) enters the combustion chamber (92) which entrains combustion gases (119) enters the combustion chamber (92) proximate the separation member (90) and is maintained so large that the flame root (114) of the blue flame (116) is maintained at a distance of at least 1 cm from the injector 28, and that between the injector 28 and the root of the flame 114, a non-burning portion 11 of the fuel jet (80) to expand in a cone, mixing with the combustion air (102, 106). The process of operating a burner according to claim 53 or 54, characterized in that there are provided in the burner body (10) apertures (118) through which an external recirculation flow enters the combustion chamber (92). 119) which entrains cold combustion gases into the combustion chamber (92) in the vicinity of the separating element (90) and, by means of this flow, an inner recirculation (112) is protected from the combustion chamber (90), thereby forming a recirculation flow which recedes into the combustion chamber from the blue flame (116) to the part (81) which is not burning from the fuel jet (80). Lisbon, 14 May 2001. (/ official industrial property agent 12