Burner for operating a heat generator

Technical field

0001The invention relates to a burner for operating a heat generator according to Preamble of claim 1.

State of the art

0002From EP-A2-0 780 630 and from EP-0780629 A2, a burner has become known, the inlet flow from a swirl generator, wherein the flow formed herein seamlessly in a Mixing section is transferred. This is done using a the beginning of the mixing zone formed for this purpose Strömungssgeometrie consisting of transition channels exists, the sectoral, according to the number of acting partial body of the swirl generator, detect the end face of the mixing section and in the flow direction swirl-shaped run. The outflow side of the transition channels, the Mixing section a number Filmlegungsbohrungen on which the increase ensure flow velocity along the tube wall. There then follows a combustion chamber, wherein the transition between the mixing section and the Combustion chamber is formed by a jump in cross section, in the plane located a backflow zone or backflow forms.

0003The swirl intensity in the swirl generator is denmach chosen so that the bursting of the carried vertebra not within the mixing zone, but further downstream, as above carried out in the area of ​​the jump in cross section. The length of the mixing section is so dimensioned such that sufficient mixing quality guaranteed for all fuel types is.

0004Although these burners to those from the previous state art, a significant improvement in strengthening the flame stability, lower pollutant emissions, lower pulsations, complete burnout, large operating range, good cross-ignition between the different Burners, compact design, improved mixing, etc., has brought, it shows that further strengthen the flame stability and an improved adaptation the flame to the given combustor geometry for a smooth Operating at the highest level in the premix combustion of the newer Generation has become necessary, especially when it comes to the pulsations to eliminate.

Summary of the Invention

0005The invention aims to remedy this. The invention as in the claims is in the object is an object in a burner of the aforementioned propose type arrangements which strengthen the flame stability and an adjustment of the flame to the given combustor geometry effect without the other advantages of this burner to reduce in any way.

0006To this end, the head end and acting swirler of the burner associated with the fuel nozzle, which is preferably on the axis of the swirl generator or of the burner is positioned and which, as a rule with a liquid Fuel is fed, surrounded by an annular spaced jacket, in which circumferential holes are mounted through which a Air volume flow to flow around the fuel nozzle. In operative connection with this Holes act additional injectors which are preferably with a gaseous Fuel to operate. A small amount of fuel is through this Injectors injected in the amount of air to flow around the fuel nozzle, such that is important for the stability of the flame center of the burner flow always is supplied in the right degree. This ensures that a uniform Fuel concentration over the flow cross section of the burner is adjusted, which lead to a suppression of combustion oscillations. This uniform Fuel concentration over the flow cross section becomes particularly noticeable on the burner axis, where experience has shown that due to uneven Fuel enrichment in the oscillations of flame front occur, which cause pulsations. Moreover, with the suppression of Combustor oscillations of the operating range of the burner substantially expanded, since no instability of the flame is more to be feared, which to a deterioration the extinction limit leads.

0007Another advantage of the invention is to be seen in that the scavenging air through the said Openings in the region of the fuel nozzle a wetting of the inner wall the conical swirl generator prevented by the injected liquid fuel.

0008Advantageous and expedient further developments of the inventive task solution are defined in the further claims.

0009Hereinafter, with reference to the drawings, embodiments of the invention explained in more detail. All non-essential for the immediate understanding of the invention, Features have been omitted. The same elements are in different Figures with the same reference numerals. The flow direction of the media is indicated by arrows.

Brief Description of the Drawings

0010It shows:<dl tsize="6"><dt>Fig. 1</dt><dd>a designed as a premix burner with a mixing zone downstream of a swirl generator,</dd><dt>FIG. 2</dt><dd>a schematic representation of the burner according to FIG. 1 with MRP the additional fuel injectors,</dd><dt>Fig. 3</dt><dd>one consisting of several shells swirl generator in perspective Illustration, cut, respectively,</dd><dt>Fig. 4</dt><dd>a cross section of a bivalve swirl generator,</dd><dt>Fig. 5</dt><dd>a cross section of a four-shell swirl generator,</dd><dt>Fig. 6</dt><dd>a view through a swirl generator, profiled its shovel-shaped shells are,</dd><dt>Fig. 7</dt><dd>An embodiment of the transition geometry between swirl generator and Mixing section and</dd><dt>Fig. 8</dt><dd>a spoiler for the spatial stabilization of the backflow.</dd></dl>

WAYS OF IMPLEMENTING THE INVENTION, COMMERCIAL APPLICABILITY

0011Fig. 1 shows the overall construction of a burner. Initially a swirl generator 100 effectively shown its embodiment in the following FIGS. 3-6 in more detail and will be described. It is in this swirl generator 100 to a conical Structure which tangentially multiply by a tangentially inflowing combustion air stream 115 is applied. The to herein forming flow is based on a downstream of the swirl generator 100 provided transition geometry seamlessly transferred to a transition piece 200, such that there is no can occur detachment areas. The configuration of this transition geometry will be described with FIG. 6 in more detail. This transition piece 200 is the outflow side the transition geometry prolonged by a mixing tube 20, both Parts form the actual mixing section 220th Of course, the mixing section, 220 consist of a single piece, that is then, that the transition piece 200 and the mixing tube 20 to form a single coherent entity merge, while maintaining the performance characteristics of each part. Will Transition piece 200 and mixing tube 20 created in two parts, these are connected by a connector ring 10, wherein the same socket ring 10 on the head side serves as anchoring surface for the swirl generator 100th Such a socket ring 10 moreover has the advantage that different mixing tubes are used can. The outflow side of the mixing tube 20 is the actual combustion chamber 30 which is merely symbolized here by a flame tube. The Mixing section 220 largely fulfills the task that downstream of the swirl generator 100 a defined distance is provided in which a perfect premixing can be achieved by fuels of different kinds. This mixing section, ie ostensibly the mixing tube 20, a lossless flow guide enables further, so also in operative connection with the transition geometry initially can not form a backflow zone or backflow, which on the Length of the mixing section 220 to the mixing quality for all types of fuel impact can be exerted. However, this mixing section 220 has another property, which is that in itself the Axialgeschwindigkeits profile a has pronounced maximum on the axis, so that a flashback of the Flame from the combustion chamber is not possible. However, it is true that in such a configuration, this axial velocity to the wall falls down. Around To prevent re-ignition in this area, the mixing tube 20 is in Flow and circumferential direction with a number of regularly or irregularly distributed holes 21 of different cross-sections and directions provided, through which a quantity of air flows into the interior of the mixing tube 20 and along the wall in terms of Filmlegung an increase in the flow rate induce. These holes 21 can also be designed so that at the inner wall of the mixing tube 20 at least in addition a effusion adjusts. Another possibility to increase the velocity of the mixture to achieve within the mixing tube 20, is that its Flow cross-section downstream side of the transition ducts 201, which already form said transition geometry, undergoes a constriction, whereby the entire speed level is raised within the mixing tube 20th In FIG extend these holes 21 at an acute angle relative to the Brenner axis 60. Furthermore, corresponding to the outlet of the transition passages 201 the narrowest flow cross-section of the mixing tube 20. The transition channels mentioned 201 thus bridge the respective cross-sectional difference, without negatively affecting the flow formed. If the selected Precaution in the management of the flow tube 40 along the mixing tube 20 a intolerable pressure loss triggers, then here to be remedied, by the end of this mixing tube in the figure not shown diffuser is provided. At the end of the mixing tube 20 closes then a combustor 30, wherein between the two flow cross sections through a Burner front 70 formed cross-sectional discontinuity is present. It is here that a forms central flame front with a backflow zone 50, which is opposite to the Flame front has the characteristics of a bodiless flame retention. makes within this jump in cross section during operation a flow regular Border zone in which by the vacuum prevailing there Vortex shedding occur, this leads to an increased ring stabilization of Backflow 50th the front end, the combustion chamber 30 a number of openings 31, through which a quantity of air flows directly into the jump in cross section, and there lower other contributes to the ring stabilization of the backflow zone 50 is strengthened. Danebst should be mentioned that the creation of a stable Backflow 50 also requires a sufficiently high swirl number in a tube. If such a first undesirable as can stable backflow by adding small strongly swirled air flows at the tube end, for example, produced by tangential openings. Here it is assumed here, that the air quantity required for this purpose amounts to about 5-20% of the total air amount. What the design of the burner face 70 at the end of the mixing tube 20 for stabilizing the backflow zone or backflow bubble 50 is concerned, to the description referenced under Fig. 8.

0012Fig. 2 shows a schematic view of the burner according to Fig. 1, in particular on the flow around a centrally disposed fuel nozzle 103 and Attention is drawn to the effect of fuel injectors 170th The operation the remaining major components of the burner, namely swirl generator 100 and transition piece 200 are described in detail under the following figures. The fuel nozzle 103 is encased in a spaced ring 190, in which a number disponierter circumferentially holes are placed 161, by which an amount of air 160 flows into an annular chamber 180 and there the Flushing of the fuel lance carries. These holes 161 are obliquely Front applied, such that an adequate axial component on the Brenner 60 arises. are in operative connection with these bores 161 additional Fuel injectors 170 provided that a certain amount of preferably Enter a gaseous fuel into the respective air flow 160, in such a way that in the mixing tube 20 a uniform fuel concentration 150 sets over the flow cross-section as the emblem shown in the figure want. Exactly this uniform fuel concentration 150, especially The strong emphasis on the burner axis 60 ensures that a Stabilization of the flame front at the output of the burner is adjusted, thus emerging Combustion-chamber are avoided.

0013To better understand the structure of the swirler 100, it is advantageous if at the same time to FIG. 3, at least FIG. 4 is used. In the following, 3 referred in the description of FIG. As needed to the remaining figures.

0014The first part of the burner according to Fig. 1 forms the swirl generator shown in FIG. 3 100. This consists of two hollow conical Teilkörpem 101, 102, the are offset from each other nested. The number of conical partial body may of course be larger than two, as the figures 5 and 6; this will depend in each case, as will come in greater detail below for explanation of mode from the entire burner. It is in certain operating situations not excluded, a characteristics of a single spiral swirl generator provide. The offset of the respective center axis or longitudinal axes of symmetry 101b, 102b (See. FIG. 4) of the conical part bodies 101, 102 to one another creates in the adjacent wall, in a mirror-image arrangement, a tangential channel, that an air inlet slot 119, 120 (See. FIG. 4) through which the combustion air 115 in the interior of the swirl generator 100, that is, into the conical cavity 114 thereof flows. The conical shape of the sectional bodies 101, 102 shown in Flow direction has a certain fixed angle. Of course, depending according to operational use, the partial bodies 101, 102 in the flow direction an increasing have or decreasing conicity similar to a trumpet respectively. Tulip. The latter two forms are not included in the drawing as they for the skilled worker nachempfindbar readily. The two conical sectional bodies 101, 102 each have a cylindrical annular top part 101a. In the area this cylindrical initial part is the already mentioned under Fig. 2 fuel 103 housed, which is preferably with a liquid fuel operates 112th The injection 104 of this fuel 112 coincides approximately with the the narrowest cross section of the cone cavity formed by the conical part bodies 101, 102 114 together. The Eindüsungskapazität and the nature of this fuel 103 is determined by the predetermined parameters of the respective burner. The conical sectional bodies 101, 102 have further each have a fuel line 108, 109, which are arranged along the tangential air inlet slots 119, 120 and are provided with injection openings 117, preferably through which a gaseous fuel 113 is injected into the combustion air flowing through there 115 is how this will represent 116 arrows. These fuel lines 108, 109 are preferably not later than the end of the tangential inflow, before Enters into the conical cavity 114, arranged at this optimal to receive air / fuel mixture. In the zoom out through the fuel nozzle 103 Fuel 112 is, as mentioned, normally a liquid Fuel, a mixture formation with another medium, for example, with a recirculated flue gas, is readily possible. This fuel 112 is at a preferably very acute angle into the conical cavity 114 injected. From the fuel nozzle 103 to THEREFORE forms a conical fuel spray 105, the rotating of the tangentially entering combustion air 115 is enclosed and degraded. In the axial direction is then the concentration of the injected fuel 112 continuously by the combustion air flowing 115 decomposed to mixing direction evaporation. Becomes a gaseous fuel introduced 113 on Oeffnungsdüsen 117, takes the Formation of the fuel / air mixture directly at the end of the air inlet slots 119, 120. If the combustion air 115 is additionally preheated, or for example, a enriched recirculated flue gas or exhaust gas, this strongly supports the vaporization of the liquid fuel 112 prior to using this mixture in the downstream stage flows here into the transition piece 200 (See. FIG. 1 and 7). The same considerations also apply if liquid through lines 108, 109 Fuels should be fed. When designing the conical part bodies 101, 102 in terms of the cone angle and the width of the tangential air inlet slots 119, 120 are to be observed to be strict limits, so that the desired 115 Set flow field of the combustion air at the outlet of the swirl generator 100 can. Generally it can be said that a reduction of the tangential Air inlet slits 119, 120, the rapid formation of a backflow zone already in favored area of ​​the swirl generator. The axial velocity inside the swirl generator 100 can be explained by a corresponding with Fig. 2 (pos. 160) closer increase or stabilize described supply a quantity of air. A corresponding Swirl generation in operative connection with the downstream transition piece 200 (See. FIG. 1 and 7) prevents the formation of flow separation within of the swirl generator 100 downstream mixing tube. The construction the swirl generator 100 is further excellent, the size of the tangential To change the air inlet slots 119 120, thus without changing the overall length the swirl generator 100 detects a relatively large operating range can be. Of course, the body part 101, 102 in another Level to one another, whereby even an overlap provided the same can be. It is also possible that part bodies 101, 102 by a counter-rotating motion spirally to nest together. Thus it is possible, the shape, size and configuration of the tangential air inlet slots 119, 120 to be varied as desired, whereby the swirl generator 100 without change is its length universally.

0015From Fig. 4 is among others the geometric configuration of optionally be provided Baffles 121a, 121b shown. You have a flow introduction function, said, according to their length, each end of the conical part bodies 101, 102 extend in the direction of inflow over combustion air 115th The canalization of the combustion air 115 in the conical cavity 114 can be obtained by Opening or closing the guide plates 121a, 121b in a region of the inlet this optimized channel in the conical cavity 114 placed fulcrum 123 are, in particular, this is necessary if the original gap size of the tangential air inlet slots 119, 120 is to be changed dynamically, for example, a change in velocity of the combustion air 115 to to accomplish. Of course, this dynamic arrangements can also statically be provided by regular needs baffles an integral part of form the tapered Teilkörpem 101 102nd

0016Fig. 5 shows in comparison with FIG. 4, that the swirl generator 100 now consists of four Teilkörpem 130, 131, 132, 133 constructed. The corresponding longitudinal axes of symmetry to any part of the body are marked with the letter a. For this configuration, is to say that they are due to the thus generated, lower swirl intensity and in interaction with a correspondingly enlarged groove width optimally is, the bursting of the vortex flow downstream side of the swirl generator in prevent mixing tube, thus the mixing tube, the role intended for it well can meet.

0017Fig. 6 5 differs from FIG. To the extent that here the body part 140, 141, have 142, 143, a blade profile form which to provide a certain Flow is provided. Otherwise Betreibungsart the swirl generator is the remained the same. The admixture of fuel 116 into the combustion air stream 115 takes out from the interior of the blade profiles, ie the fuel line 108 is now integrated into the individual blades. Again, the The longitudinal axes of symmetry in the individual sub-bodies with the letter a.

0018Fig. 7 shows the transition piece 200 three-dimensional view. The transition geometry is a swirl generator 100 with four partial bodies, in accordance with of FIG. 5 or 6, constructed. Accordingly, the transition geometry has as natural extension of acting upstream subfield four transition passages 201, whereby the cone surface of said quarter subfield is extended until it intersects the wall of the mixing tube. The same considerations also apply, if the swirl generator consists of a different principle than those described with Fig. 3, is constructed. The downwardly extending in the direction of flow area of ​​the individual Transition passages 201 has a flow direction in spiraling Shape which describes a sickle-shaped course according to the Fact that in the present case, the flow cross-section of the transition piece 200 flared in the flow direction. The helix angle of the transition passages 201 in the flow direction is selected such that the flow tube is then up to jump in cross section at the combustion chamber inlet nor a sufficiently large Strekke remains to accomplish a perfect premixing with the injected fuel. Furthermore increased by the measures mentioned above, the Axial velocity at the mixing tube wall downstream of the swirl generator. The transition geometry and the measures in the area of ​​the mixing tube effect significant increase in Axialgeschwindigkeitsprofils the center of the mixing tube out, so that the risk of premature ignition is decisively counteracted.

0019Fig. 8 shows the already mentioned separation edge, which formed at the burner outlet is. The flow cross-section of the tube 20 is replaced in this area a transition radius R whose size generally of the flow within the Tube 20 depends. This radius R is selected so that the flow to the Wall applies and thus the swirl number can rise sharply. Quantitatively, the define the size of the radius R so that the> 10% of the inner diameter d of the tube 20. Compared with a flow without radius enlarges Now the backflow 50 huge. This radius R extends to the exit plane the tube 20, said Winkei β between the beginning and end of curvature <90 ° is. Along the one leg of the angle β, the separation edge extends into A Interior of the tube 20 and thus forms a breakaway step S opposite to the front Point of the breakaway edge A, the depth of which is> 3 mm. Of course, the here parall the outlet plane of the tube 20 extending edge based on a curved Course be brought back to stage exit plane. The angle β ' extending between the tangent of the breakaway edge A and perpendicular to the exit plane of the tube 20 spreads out, is equal to β angle. The benefits of this training this separation edge going from EP 0780629 A2 under The chapter "Presentation the invention "hervor.Eine further embodiment of the tear-off edge for the same purpose can be achieved with the combustion chamber side torus-like notches.

LIST OF REFERENCE NUMBERS

0020<dl tsize="22" compact="compact"><dt>10</dt><dd>Buchenring</dd><dt>20</dt><dd>Mixing tube, part of the mixing section 220</dd><dt>21</dt><dd>Holes, openings</dd><dt>30</dt><dd>combustor</dd><dt>31</dt><dd>Openings</dd><dt>40</dt><dd>Flow, pipe flow in the mixing tube, mainstream</dd><dt>50</dt><dd>Backflow, backflow</dd><dt>60</dt><dd>Brenner</dd><dt>100</dt><dd>swirler</dd><dt>101, 102</dt><dd>Tapered body part</dd><dt>101a</dt><dd>Ring-shaped top part</dd><dt>101b, 102b</dt><dd>Longitudinal axes of symmetry</dd><dt>103</dt><dd>fuel nozzle</dd><dt>104</dt><dd>fuel injection</dd><dt>105</dt><dd>Fuel Spray (Brennstoffeindüsungsprofil)</dd><dt>108, 109</dt><dd>fuel lines</dd><dt>112</dt><dd>liquid fuel</dd><dt>113</dt><dd>Gaseous fuel</dd><dt>114</dt><dd>conical cavity</dd><dt>115</dt><dd>Combustion air (combustion air stream)</dd><dt>116</dt><dd>Fuel injection from the lines 108, 109</dd><dt>117</dt><dd>fuel nozzles</dd><dt>119, 120</dt><dd>Tangential air inlet slots </dd><dt>121a, 121b</dt><dd>baffles</dd><dt>123</dt><dd>Fulcrum of the baffles</dd><dt>130, 131, 132, 133</dt><dd>subfield</dd><dt>131a, 131a, 132a, 133a</dt><dd>Longitudinal axes of symmetry</dd><dt>140, 141, 142, 143</dt><dd>Aerofoil shaped body part</dd><dt>140a, 141a, 142a, 143a</dt><dd>Longitudinal axes of symmetry</dd><dt>150</dt><dd>fuel concentration</dd><dt>160</dt><dd>Amount of air mixed air</dd><dt>161</dt><dd>Holes, openings</dd><dt>170</dt><dd>Fuel injectors</dd><dt>180</dt><dd>Annular air chamber</dd><dt>190</dt><dd>ring</dd><dt>200</dt><dd>Transition piece, part of the mixing section 220</dd><dt>201</dt><dd>Transition passages</dd><dt>220</dt><dd>mixing section</dd></dl>