RU2152559C2 - Hydrogen combustion process and burner - Google Patents

Abstract

FIELD: fuel combustion processes. SUBSTANCE: for diffusion combustion of hydrogen the latter and oxidizing agent are fed to burner; in the process, main flow depends on direction of oxidizing agent while hydrogen usually flowing crosswise and perpendicular to main flow is distributed among combustion zones; novelty is that used as oxidizing agent is air and crosswise flow depends on finely dispersed distribution among great number of combustion microzones. In spite of greater number of combustion zones process charges remain at same level. EFFECT: reduced emission of nitric oxides. 33 cl, 5 dwg

Description

 The invention relates to a method for burning hydrogen and a burner for burning hydrogen.

Hydrogen (H ₂ ) as a fuel for all types of burners, for example for combustion chambers of gas turbines, is characterized by a particularly high reactivity and thereby also extremely great combustion stability, namely even with the excess air that appears in the combustion chambers of modern gas turbines. Thanks to the publications of Haywood and Mikus in the combustion technique, it is known that in an area with sufficiently high excess air, an increase in the degree of mixing leads to a decrease in the formation of nitric oxide (NO). This results in a minimum of formation of nitric oxide with completely homogeneous air-fuel combustible mixtures, which can be achieved approximately by preliminary mixing in front of the immediate combustion zone. A related proposal for homogeneous, pre-mixed hydrogen combustion is available from Pratt & Whitney of Canada. Despite the advantages that pre-mixing gives in terms of reducing the formation of nitric oxide, a significant drawback of this measure is that, in principle, a flame can slip into the mixing zone.

 The technical solutions of the respective premix burners show a relatively simple design. In this case, for example, a plate-shaped distribution chamber for hydrogen is inserted transversely to the air flow direction, hereinafter referred to as the main flow direction, into the combustion chamber, wherein the distribution chamber is pierced in the main direction by a large number of air tubes with an inlet and an outlet. Each air tube is connected via small holes, which are located near the inlet, to the distribution chamber. If now hydrogen is directed into the distribution chamber, then it flows across the main direction of flow to the individual holes and thus enters the air ducts. If now air is simultaneously blown into the combustion chamber through air ducts, both gases are mixed inside the air duct. The mixture thus formed then enters the combustion chamber and ignites. Due to the location of the distribution chamber, the design of the burner is greatly simplified, since in this way individual pipelines for supplying hydrogen to individual air pipes or combustion zones are avoided.

 Given the value of the degree of mixing, taking into account the formation of nitric oxide during the combustion of hydrogen, the well-known hydrogen burners and hydrogen combustion chambers that operate without preliminary mixing, i.e., according to the principle of diffusion combustion, have an increased number of injection nozzles for supplying hydrogen. In this case, it is usually a question of traditional vortex nozzles, the corresponding solutions were presented by the LABOR / Kuznetsov society in Russia and Germany by the company Motoren und Turbinen-Union GibH. When using this principle, for example, by the LABOR society, the number of mono combustion zones can be increased by a factor of five or more, so that in a certain combustion chamber the amount of combustion can be increased, for example, from 30 to 150 or more. In this case, individual combustion zones still have a diameter of about 20 mm. A further reduction in the combustion zones and thereby an increasing number of underlying nozzles is hindered by the large number of individual pipelines for supplying hydrogen required in this case.

 In accordance with this, the invention is based on the task of improving the method of diffusion combustion of hydrogen and a burner to implement this method so that, due to a noticeable increase in the number of combustion zones, a clear reduction in the formation of nitric oxide is achieved compared to previous burners with diffusion combustion.

 With a typical method, as well as the corresponding burner, this problem is solved using the distinguishing features of paragraphs 1, 4 and 10 of the claims.

 Moreover, in particular, the advantage is that the technological costs despite the significant increase in the number of combustion zones remain low.

 Preferred improved embodiments of the invention are indicated in the additional claims.

 Thus, an advantage of the embodiment according to claim 2 is that, with the aid of hydrogen, a particularly good cooling effect is exerted on the structure.

The invention is presented using the drawing and is explained in more detail below. The drawing shows:
FIG. 1: view of a matrix-type burner for a combustion chamber,
FIG. 2: section along line II-II in accordance with FIG. 1,
FIG. 3: guide finger
FIG. 4: section along line IV-IV in accordance with FIG. 3
FIG. 5: guide tube with a guide pin,
FIG. 6: view of a two-dimensional burner structure,
FIG. 7: a section along line VII-VII in accordance with FIG. 6
FIG. 8: matrix view of another burner,
FIG. 9: section along line IX-IX in accordance with FIG. eight,
FIG. 10: guide tube in accordance with FIG. 9 with a guide finger
FIG. 11: view XI in accordance with FIG. ten,
FIG. 12: section along line XII-XII in accordance with FIG. ten,
FIG. 13: detail XIII in accordance with FIG. ten,
FIG. 14: image in accordance with FIG. 13 with a modified axial arrangement of the guide pin,
FIG. 15% image in accordance with FIG. 14 with a modified angular arrangement of the guide finger,
FIG. 16: an embodiment of a guide tube system — a guide pin with guide channels,
FIG. 17: section along the line XVII-XVII in accordance with FIG. 16,
FIG. 18: view of a two-dimensional structure of another burner,
FIG. 19: section along the line XIX-XIX in accordance with FIG. 18,
FIG. 20: burner with solid perforated wall.

FIG. 21: view XXI in accordance with FIG. 20,
FIG. 22: burner with a curved distribution channel and
FIG. 23: a section along line XXIII-XXIII in accordance with FIG. 22.

 FIG. 1-4 show a hydrogen burner for installation in, for example, a combustion chamber of a gas turbine. The burner has a plate shape and is installed in the combustion chamber across the main direction of flow. The edge zone of the burner and its connection with the furnace chamber housing not shown in the drawing are not represented and can be performed as desired. The burner consists of a first perforated partition 2 and a second perforated partition 3, which are held at a constant distance "d" by a large number of guide tubes 4. In this case, the holes can be arranged in accordance with certain matrix patterns. The first perforated partition 2 consists, for example, of the proper metal and is gas tight. In contrast, the second perforated baffle 3 is gas permeable and consists of a suitable porous material, for example, a cermet alloy. The holes in both partitions 2, 3 are located with the same overlap, so that each hole in the first partition 2 forms a pair of holes with the corresponding hole in the second partition 3. The connection of the burner is mainly due to the fact that a guide tube 4 is inserted and fixed in each pair of holes as a spacer. The guide tubes 4 have circular grooves rolled outward 5. The guide tubes 4 are fixed in the perforated partition 2, for example, by soldering or welding , while fixing in the partition 3 can be carried out by flaring or flanging. In this case, in cooperation with the groove 5 between the guide tubes 4 and the perforated partition 3, a connection with a geometric closure is obtained, respectively. Thus, basically perforated partitions 2, 3 with guide tubes 4 form a distribution chamber. A guide pin 6 is inserted into each guide tube 4, as shown on an enlarged scale in FIG. 3 and 4. In essence, the guide pin consists of a cylindrical body of revolution with a stop 6a, a guide part 6b, a fastening device 8 and a disk 9. The outer diameter of the guide part 6b approximately corresponds to the inner diameter of the guide pipe and in the shown embodiment has four axial guide channels 7 The mounting device of FIG. 3 is attached to the right of the guide part and is practically a zone with a reduced diameter, which has a concentrically attached disc 9, the outer diameter of which approximately corresponds to the outer diameter of the guide part 6b. An abutment 6a is formed by an axially short zone whose outer diameter is larger than the outer diameter of the guide portion 6b. A guide pale 6 is inserted into each guide tube 4 from the burner air supply side to the stop 6a, which abuts the perforated partition 2, and is firmly fixed in this position. A similar kind of node forms an injector, respectively. For commissioning the burner, gaseous hydrogen is supplied to the distribution chamber between the perforated partitions 2, 3. In addition, air is blown into the combustion chamber through the guide tubes. In this case, hydrogen inside the distribution chamber flows across the main direction and is distributed in the form of a finely dispersed distribution over the local zones of the porous perforated partition 3, through which it enters the combustion chamber and forms a hydrogen atmosphere here. At the same time, at the exit of each guide tube 4, due to deflection by the disk, an air flow is formed according to the type of the side surface of the cone, which enters during the formation of the mixture with the surrounding hydrogen, and an axisymmetric diffusion flame is formed. Useful for enhancing the mixing process is in this case the interaction of colliding adjacent conical flares. The geometry of the guide fingers 6 is selected in such a way that when inserted to the corresponding stop 6a, a predetermined deviation is obtained, i.e. predefined torch shape. It is also permissible that the stops are omitted for weight reasons. In this case, the insertion of the guide fingers 6 into the guide pipes 4 in a predetermined axial position is carried out using a technological requirement. Due to the extremely simple design of the injectors, they can be miniaturized in such a way that much more can be installed in each combustion chamber. Due to miniaturization of this order, combustion zones made in accordance with the invention are called combustion microwaves.

 FIG. 6 and 7 show another embodiment of a burner in accordance with the invention, consisting of separate elongated distribution channels 11 for a U-shaped cross-section provided for hydrogen, which are closed on the side of the combustion chamber by walls 12 of a porous cermet alloy. The channels 11 are connected to each other by means of perforated profiles having a cross-sectional angle shape so that the corresponding longitudinal longitudinal edges of the perforated profile 13 are fixed to the longitudinal edges of two adjacent distribution channels 11. At the same time, the holes 14 are located at the same distance in the strip bends of the perforated profiles 13 . To commission this burner, hydrogen gas is supplied to the distribution channels 11. At the same time, air is blown into the combustion chamber through openings 14. When this hydrogen in the distribution channels 11 flows across the main direction of flow and due to the fine distribution is distributed over the local zones of the porous walls 12, through which it enters the combustion chamber and forms a hydrogen atmosphere. Due to the air supply in the zone of each hole, a stoichiometric zone is formed, which, when the burner ignites, forms its own torch. This burner is especially simple and can be made in the form of a sheet structure. Thus, for example, it is possible to act in such a way that the U-shaped distribution channels 11 are made of sheet material, with each U-shaped elbow connected as a unit with a bent perforated strip. After the porous walls 12 are inserted, adjacent channels 11 are connected to each other, for example, by welding along the free edges of the perforated strips. This burner can be miniaturized in such a way that several thousand combustion zones can be achieved inside the combustion chamber.

 With the fine-dispersed distribution occurring in the burners described above, hydrogen is distributed to thousands of combustion microzones by means of a distribution chamber or distribution channels, so that microdiffusion combustion of hydrogen occurs. Due to the fact that in the burners described above a hydrogen atmosphere is formed inside the combustion chamber, into which air jets are injected, inverse diffusion combustion is obtained, which can be stabilized in the resulting mixing zones in most cases with a turbulent characteristic. A significant advantage of this inverse diffusion combustion of hydrogen is that good cooling of the structure with hydrogen is achieved.

 In the above-mentioned burners, other porous metal materials can also be used instead of porous cermet alloys. For example, porous materials based on metal fibers, which are known, for example, under the name “Felt Metal”, are taken into account. In addition, it is permissible that the porous material consist of a ceramic material. In order to limit the effects of inhomogeneities possibly present in the porous material, a perforated sheet with a specific fine solution of holes relative to a thin layer of porous material can be preliminarily included or used.

 FIG. 8-11 show another embodiment of the burner, which, however, in contrast to the previous ones, does not work with inverse, but with regular diffusion combustion. This burner again consists mainly of two perforated partitions with the same overlap, which in this case are indicated by the numbers 15 and 16. Both perforated partitions are firmly connected to each other by means of guide pipes 17, which respectively have an inlet and an outlet, so that it forms again distribution chamber. Near the outlet holes on the guide tubes 17 there are several holes 18 with the same angular pitch. A guide pin 19 is inserted into each guide tube 17, consisting of an abutment 20, a guide part 21 and a free-jet part 22, the free-jet part being practically an axial section of a reduced diameter. The stop 20 and the guide part 21 have a certain number of grooves 23 extending in the axial direction, the depth of which can reach the outer diameter of the free-jet part 22. The number of holes 18 corresponds to the number of grooves 23. When the burner is commissioned, air is blown into the furnace through the guide tube 17 the camera. At the same time, hydrogen is supplied to the distribution chamber, so that it is introduced into the guide pipes through separate openings 18 and is carried away by the air entering through the grooves 23. In this case, accordingly, a combustion microzone is formed downstream of the hole 18, in which the flame stabilizes upon ignition of the combustion chamber. Since the guide tubes 17 in the shown embodiment have six holes 18, respectively, six combustion microzones are obtained for each guide tube. This results in a further increase in the number of combustion zones. The application of this principle in the furnace chamber of LABOR mentioned at the beginning would increase the number of established combustion zones to approximately 5000. This again contributes to the fact that even without preliminary mixing a very high degree of mixing is achieved, which results in the fact that the formation of nitric oxide is significantly reduced. By turning and / or axially displacing the guide bolts 19 relative to the guide tubes 17, various burner adjustments can be made. In this case, it is also possible to lower the stops 20 and to establish the axial position of the air duct fingers using the appropriate instructions.

 FIG. 12-15 show various settings for the burner described above. In FIG. 12, a guide pin with grooves 23 is mounted relative to the guide pipe 17 with holes 18 in such a way that hydrogen is introduced through the holes 18 into the gaps between the air jets that enter through the grooves 23. FIG. 13 shows a guide pin in a position in which the guide part 21 fits snugly to the holes 18. As a result, the hydrogen stream can only deviate downstream. However, if the guide portion 21 is fixed in the guide tube 17 so that there is a slightly greater distance from the holes 18, as shown in FIG. 14, some recirculation may occur. FIG. 15 finally shows a configuration in which the air jets coming through the grooves 23 exactly hit the hydrogen jets coming through the holes. In all these cases, finely dispersed jets of hydrogen are supplied through the openings 18 into the air atmosphere, so that regular diffusion combustion is obtained, with only individual combustion zones still having a diameter of about 2 mm. Moreover, in many cases, the flares are stabilized at the openings 18. It should be mentioned that the free-jet part 22 in the embodiment of the invention can also be omitted, in particular, during air injection in accordance with FIG. fifteen.

 FIG. 16 and 17 show an embodiment of the invention, the jets of hydrogen and air being sent separately to the combustion chamber. For this purpose, the guide pipes 17 with holes 18 are described above. These guide pipes are reinserted into the perforated partitions 15 and 16, of which only the perforated partition shown at 16 can be seen here. The guide pin 24 used in this case, although it has recesses 23 however, in addition, it is equipped with two significant changes. Firstly, a finger with a constant diameter is installed approximately up to the output cross section. Secondly, in the middle zones located between the grooves 23 of the material, axially extending small guide channels 25 are located. The corresponding guide pin 24 is inserted into the corresponding guide pipe 17 so that each hole 18 enters the guide channel 25. Thus, the beginning diffusion between hydrogen and air is shifted to the area downstream of the perforated septum 16, for example, to avoid excessive thermal stresses on the structure. With these solutions, the torches stabilize at the mouths of the guide channels 25.

 FIG. 18 and 19 show an embodiment of a burner for regular diffusion combustion of a two-dimensional type. This burner again consists of separate elongated distribution channels 26 provided for supplying hydrogen, which, in contrast to the distribution channels 11 in accordance with FIG. 6 and 7 have a closed cross section. This cross section is determined mainly by a flat rectangular shape, which, however, has a roof-shaped edge 26a in the right-hand region of the figure. Small openings 27 are located on both sides of the roof-shaped edge with offset. The individual channels 26 are held mutually away from each other by means of a fastening device not shown so that they form a grating through which, in accordance with FIG. 19, air can flow from left to right. The burner also contains strip transition sheets 28, in the longitudinal edges of which recesses 29 are selected. The transition sheets 28 are fixed respectively between two distribution channels 26 in the area of the openings 27 by means of an unshown mounting unit so that a recess 29 is associated with each hole 27. In this case, instead of one of the shown holes 27, several smaller holes may also be located. When this burner is commissioned, air in accordance with arrows 30 through recesses 29 and hydrogen through holes 18 in accordance with arrows 31 are blown into the combustion chamber, as a result of which an air atmosphere with a large number of combustion microzones is formed inside the combustion chamber in the corresponding zones of the openings 27. After ignition of the combustion chamber, the torches stabilize at openings 27.

 FIG. 20 and 21 show a burner with a solid perforated partition 32 with openings 32a, on which several distribution channels 33 are fixed using fastening devices 34. The distribution channels 33 have an elongated circular cross section and a large number of holes 35 in the area facing the perforated partition 32. Fixing devices 34 are made of wire or sheet material. As shown in FIG. 21, two holes 35 are associated with each hole 32a of the perforated partition 32, so that hydrogen can exit in accordance with arrows 37.

 When commissioning this burner, air is blown into the combustion chamber in accordance with the arrows 36 through the perforated wall 32, whereby an air atmosphere with a large number of combustion microzones is formed inside the combustion chamber in the respective zones of the openings 35. After ignition of the combustion chamber, the torches at holes 35 stabilize.

 FIG. 22 and 23 show another embodiment of the burner. A partial view in accordance with FIG. 22 shows curved distribution channels 38, which are part of an annular burner, and in accordance with FIG. 23 have an elongated circular cross section. In addition, each distribution channel forms a closed ring, which is connected to the hydrogen supply line using its own connecting element. The burner connection is created, for example, by means of wave-shaped separators 39 located between the individual distribution channels 38, which are connected to the distribution channels, for example, by welding. The separators 39 are respectively made of strips of sheet material and provide a residual distance between the individual distribution channels 38 for the passage of air. It is also conceivable that the distribution channel 38 be wound together with a separator 39 for a disk or ring burner, so that the distribution channel takes a spiral shape. To create a large number of combustion microzones on the distribution channel 38, the holes are again located, which in this case are indicated by the position 40. A common feature of the annular and spiral distribution channels is that they have a curved shape. These burners operate according to the principle of the same action, as already described in connection with FIG. 18-21.

Claims (33)

 1. A method of burning hydrogen in diffusion combustion, whereby hydrogen and an oxidizing agent are supplied to the burner, and the main flow direction is determined by the direction of flow of the oxidizing agent, and hydrogen is distributed for individual combustion zones in a direction that is mainly perpendicular to the main direction of flow of the cross flow, characterized in that as oxidizing agents use air and the cross flow is associated with a finely dispersed distribution over a larger number of individual combustion microzones.  2. The method according to claim 1, characterized in that in separate combustion microzones, air is sent to a hydrogen atmosphere.  3. The method according to claim 1, characterized in that in separate combustion microzones hydrogen is directed into the air atmosphere.  4. A hydrogen burner according to claim 1, comprising a generally plate-shaped distribution chamber, characterized in that the distribution chamber consists of a first perforated partition (2) and a second perforated partition (3) that are held at a constant distance (d) and An air guide pin (6) with several axial guide channels (7, 23) is inserted into each guide tube (4).  5. Burner according to claim 4, characterized in that the second perforated partition (3) consists of a gas-permeable porous material.  6. A burner according to claim 4, characterized in that the perforated partitions (15, 16) are composed of a gas-tight material.  7. The burner according to one of claims 4 to 6, characterized in that the air guide pin (6) has a mounting device (8) with a disk (9).  8. The burner according to one of claims 4 to 6, characterized in that the air guide pin (6, 19) has a guide part (21) and a free-jet part (22).  9. The burner according to one of claims 4 to 6, characterized in that the air guide pin (6, 19, 24) extends from the input cross section to the output cross section of the corresponding guide tube and here has a constant diameter in the grooves between the grooves (23) In the middle of the material zones, axially extending guide channels (25) are arranged.  10. Burners according to one of claims 5 to 9, characterized in that the porous material is a cermet alloy.  11. The burner according to one of claims 5 to 9, characterized in that the porous material is a ceramic material.  12. The burner according to one of claims 5 to 9, characterized in that the porous material is a material based on metal fibers.  13. The burner according to one of paragraphs.5-9, characterized in that in front of the porous material included a transition sheet with a certain fine raster of holes.  14. The burner according to one of claims 5 to 9, characterized in that the porous material is replaced by a perforated sheet with a certain fine raster of holes.  15. The burner according to one of claims 4 to 9, characterized in that the air guide pin (6, 19) has a stop (6a, 20).  16. A burner for implementing the method of burning hydrogen according to claim 1, wherein the burner contains at least one distribution channel, characterized in that the distribution channel (11) has a U-shaped cross section, which is closed by the walls on the side of the combustion chamber (12) of a porous material and a distribution channel (1) by means of a perforated profile (13), with an angular cross-section, is connected to an adjacent distribution channel so that the free longitudinal edges of the perforated profile (13) are fixed us on the longitudinal edges of adjacent distribution channel (11).  17. The burner according to clause 16, characterized in that the distribution channel (11, 26, 33, 38) has a curved shape.  18. The burner according to claim 17, characterized in that the burner has a wave-like separator (39).  19. The burner according to one of paragraphs.16-18, characterized in that the porous material is a cermet alloy.  20. The burner according to one of paragraphs.16-18, characterized in that the porous material is a ceramic material.  21. The burner according to one of paragraphs.16-18, characterized in that the porous material is a material based on metal fibers.  22. The burner according to one of paragraphs.16-18, characterized in that in front of the porous material included a transition sheet with a certain fine raster of holes.  23. The burner according to one of paragraphs.16-18, characterized in that the porous material is replaced by a perforated sheet with a certain fine raster of holes.  24. A burner for implementing the method of burning hydrogen according to claim 1, wherein the burner contains at least one distribution channel, characterized in that the distribution channel (11, 26) has a closed cross section of a generally flat rectangular shape, which is towards the fuel the camera is equipped with a large number of holes (27).  25. The burner according to paragraph 24, wherein the adapter sheets (28) respectively between the two distribution channels (11, 26) are fixed in the area of the holes (27) so that a recess (29) is associated with each hole (27).  26. The burner according to paragraph 24, wherein the burner has a solid perforated partition (32), on which several distribution channels (33) are fixed using fasteners (34), and an opening (35) is associated with each hole of the perforated partition, or group of holes (35).  27. The burner according to one of paragraphs.24-25, characterized in that the distribution channel (11, 26, 33, 38) has a curved shape.  28. The burner according to claim 27, wherein the burner has a wave-like separator (39).  29. The burner according to one of paragraphs.11-28, characterized in that the porous material is a cermet alloy.  30. The burner according to one of paragraphs.11-28, characterized in that the porous material is a ceramic material.  31. The burner according to one of paragraphs.11-28, characterized in that the porous material is a material based on metal fibers.  32. The burner according to one of paragraphs.11-28, characterized in that in front of the porous material included a transition sheet with a certain fine raster of holes.  33. The burner according to one of paragraphs.11-28, characterized in that the porous material is replaced by a perforated sheet with a certain fine raster of holes.

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