A FEEDING DEVICE FOR A FLUID TO A COMBUSTION CHAMBER

Abstract: A device for supplying a fluid to a combustion chamber (3) in a kiln (2) or the like has a tube supported outside its combustion chamber (3) and provided with circumferential orifices (5e), and drive means for axial displacement of said tube into and out from a hole in the chamber wall. The fluid is supplied via a flexible hose (7). In a housing (11) for said supply device there is arranged a cleaning means for cleaning said tube during its inward and/or outward movement. The supply device is shaped like an elongate module unit (1) having a frame portion (10) surrounding said tube (5) and replaceably applicable on the wall (2a) of the plant. The module unit has a flange shaped connection means with a seal which, in the operational position of said tube, engages the tube, said engagement being released for withdrawal of the tube.

Description: A FEEDING DEVICE FOR A FLUID TO A COMBUSTION CHAMBER Background of the Invention The present invention relates to a device for supplying a fluid to a combustion chamber in a heat-generating plant, e.g. a heating boiler or a kiln, said device being of the type defined in the preamble of Claim 1. The standing of the prior art Such supply devices are previously known through SE,C, 9201747-4 (publication number 502 188) and SE,C, 9304038-4 (publication number 502 283) (ECOMB applicant in both cases) and the corresponding foreign patents. Prior art supply devices of this kind offer reduced emis- sion levels and increased flexibility, making it possible in a rapid and reliable way to switch to a desired emission level. Further, the prior art supply devices simplify the proce- dure of sooting and cleaning the tubes which also increases the yield of the combustion or gasification process, respectively. In addition thereto there is also offered a possibility, at different points of time, to supply different fluids or solid particles, respectively, via one or more of the tubes for the purpose of setting a new optimal operational level in response to the actual operational status of the combustion chamber. A particular advantage of both prior art devices is that one or a few tubes can be withdrawn simultaneously the combustion or gasification process proceeding continuously with the use of the remaining tubes. " Other types of supply devices are described in e.g. DE,A1,4 306 765 (Bauer), US,A, 5 343 592 (Peter-Hoblyn et al) and US,A, 5 112 216 (Tenn) . A supply device of the type here discussed must function reliably during a long period of time in a severe environ- ment in which not at least the tube inserted into the combustion chamber is exposed to high stresses due to the high temperature and the corrosive environment. It is also necessary to pay attention to the temperature variations arising when the tube is extracted for cleaning purposes which normally takes place 3-6 times a day. The useful life of a heating plant is essentially longer than that of a supply device of the type here under discussion which creates the problem how to design the supply device so that it can in the best way satisfy the existing requirements for service and maintenance. Another problem is related to the fact that the dimensions of new combustion plants do within wide limits vary in comparison with those existing on the market, so that the length of the displaceable tube must be varied correspondingly. This does in turn create problems concerning the design of the complete supply device in order for it to satisfy the different requirements at issue. Objects of the Invention One object of the invention is to provide a supply device of the type mentioned which permits simple service and replacement when called for. Another object is to provide a supply device which can in a simple way be adjusted to different dimensions of the combustion chamber in the plant, which efficiently protects vital parts of the device from influence by the high* temperatures and the corrosive environment, and which efficiently guarantees the intended function of the device by making it possible closely to clean the tube in connection with its axial displacement movements. Summary of the Invention The above and other objects are fulfilled by a supply device of the type mention above and designed according to the invention and which exhibits the features set out in the characterizing portion of Claim 1. The design of the device as a module unit facilitates the manufacture thereof and makes it a simple task to adjust it to the dimensions of the combustion chamber in question. Moreover, service and replacement of its components is facilitated and the replacement of all of the device at regular intervals amounts to an economically advantageous alternative since it will for that reason become possible practically completely to avoid expensive breakdowns of all of the plant. A sealing member of this kind comprising movable parts and actuated by a drive means also prevents gases which are corrosive and detrimental to the environment to pass from the combustion chamber into the space outside the chamber where the unit is mounted and facilitates cooperation with the module unit as a whole. According to a preferred embodiment the sealing member mounted at the inner end of the supply device comprises elements shaped like portions of a circular ring and rotatably mounted on a connecting flange surrounding the hole in the wall of the combustion chamber The parts of the annular sealing member will then like an iris diaphragm move in towards the tube to engage it and out from the tube to release it. In practice it is preferred that the module unit comprises a frame portion surrounding the tube and of the type defined in Claim 3. This design of the module unit makes it possible simply to select a desired length of the frame portion as well as of the means used for displacing the tube. In order to facilitate the displacement the frame portion may exhibit a guide extending along it for a carriage supporting the tube directly or via link means in the area around its outer end. As an alternative it is possible via the tube to supply to the combustion chamber another fluid than air, e.g. a com- bustible fluid like methane, propane or ammonium. In order to avoid the risks associated with such a supply of a combustible substance it is, according to a corresponding embodiment of the invention, suggested that the module unit supports an additional valve for the supplied com- bustible fluid which is designed in such a way that, when the tube carries out a displacement movement out from the combustion chamber, said valve is immediately closed whereby the supply of combustible fluid is shut off. An alternative possibility could be that, when the valve is open, a axial displacement of the tube in the outward direction is impeded. Further characteristics of and advantages with the inven- tion will appear from the following description of an embodiment. The description refers to the annexed drawings. Short Description of the Drawing Fig. 1 is a perspective view which in cross-section shows * the combustion chamber of a heat-generating plant such as a waste combustion furnace which is provided with a supply device according to the invention for the purpose of supplying air, said device being shown in its active position; Fig. 2 is a perspective view showing some essential compo- nents of the supply device according to Fig. 1; Fig. 3 does, with some parts removed, in a perspective view show the fluid tube for the supply device according to Figs 1 and 2 which is provided with a outer jacket and with cooling tubes; Fig. 4 is a lateral view illustrating the outer end of the fluid tube as well as suspension arrangements and connections for the fluid and for a cooling agent; Fig. 5 is a detail view in the shape of a cross-section through a portion of the wall of the combustion plant and the housing at the end of the supply device supporting the tube cleaning means; Fig. 6 is a vertical section through the inner end of the flange connection of the supply device, the associated sealing arrangement being shown in its open position; Fig. 7 corresponds to Fig. 6 but the sealing arrangement is in its closed position; Fig. 8 is a detail view of a valve provided with an automatic closing device for supplying a combustible fluid to the combustion chamber; Fig. 9 is a vertical section through the tube illustrating three threaded holes at different angular distances therein; and Figs 10A-10C illustrate three different types of plugs which can be screwed into the threaded holes in Fig. 9. Description of Preferred Embodiments In Fig. 1 reference numeral 2 indicates a combustion plant in the shape of a kiln for burning solid fuel comprising a lower grate (not shown) and an upper combustion chamber 3. The fuel can be supplied intermittently or continuously and combustion air is in the shape of primary air blown in from below and up through the grate which generates combustion gases to the combustion chamber 3. According to the present invention secondary air is supplied via a number of supply devices, one of which, designated 1, has been shown in Fig. 1. The supply device exhibits an axially displaceable tube 5 passing into the combustion chamber 3 through an opening in the wall of the kiln 2. The supply devices 1 add secondary air for the purpose of finalizing the combustion of reaction products formed in the shape of gas and solid particles in the combustion chamber 3. Some of the particles are deposited on the inner side of the combustion chamber 3 which is covered by water or steam tubes 4 and an external insulation layer. Dust particles settle also on the supply tubes 5, which may completely or partly clog the holes 5e for the supply of secondary air, thus negatively affecting the supply of secondary air. This results in the combustion becoming incomplete involving further problems of the kind mentioned. In a plant of the type here at issue the supply tubes 5 for a fluid, e.g. secondary air, are arranged so as to form a curtain system comprising a number of parallel such tubes 5 at one or more levels in the combustion chamber 3. Tubes 5 are provided with nozzle-shaped openings 5e along all of the circumferential area of the tubes. Openings 5e may be equidistant and include several rows of openings at different angular distances, which openings can be provided with plugs which may serve as muzzles and they can be located along the tubes in a manner described below in greater detail with reference to Figs 9 and 10. A fluid, e.g. secondary air under high pressure, is supplied via a fan (not shown) connected to a manifold 6 from which extend flexible hoses 7 which by means of quick couplings are connected to the end flanges 5b of tubes 5. In response to the combustion process taking place tubes 5 are axially pushed into and withdrawn from the chamber 3 with longer or shorter time intervals, for instance 3-6 times a day. In this way the emission level of the combustion process can be maintained optimal. The supply device 1 shown in Fig. 1 will now be described in greater detail, reference being made to that figure and to the other figures of the drawing. The supply device 1 does accordingly consist of an elongate module unit which is replaceably applied to the wall 2a of the combustion plant 2 in the area of a hole therein made for tube 5. The module unit is constructed around a frame portion 10 having approximately square cross-section and at its one end exhibiting a cleaning means in the shape of steel pins 8 acting as brushes, and its drive device which will be described with reference to Fig. 5, surrounded by a housing 11 which housing is pro- vided with a connecting flange 11a surrounding the hole in the wall 2a. The frame portion 10 also has an upper guide 12 extending along it and adapted for a carriage 13 which via links 14, 15 and a clamp 16, surrounding tube 5, supports tube 5 in the area of its outer end. As has been mentioned above, the tube is mounted for rotation whereby the directions of the exiting fluid flows can be optimally adjusted. The drive device for the tube consists of an electric motor 20 mounted at the inner end of the frame portion 10 and, via a chain 21, rotating a shaft 22 carrying a sprocket wheel 23. Another sprocket wheel 25 is mounted on a shaft 26 at the other end of frame portion 10. A chain 24 passes around the sprocket wheels 23, 25 and is via a connecting element 27 attached to the link arm 15 so that tube 5 will be displaced in either direction in response to the rotational direction of the electric motor 20. The guide 12, disposed in the area of the roof of frame portion 10, exhibits lower bent shanks defining an opening facing downwards and receiving the downwards directed central part 13a of the T-shaped carriage 13. Carriage 13 can slide on the beam serving as a guide or have wheels or rollers which facilitate the movement. As appears from Fig. 3, tube 5 consists of a outer jacket 5a provided with muzzles or nozzle orifices 5e and an inner tube 5b which, at its outer end, has a connecting flange 5k for a coupling 7a on the flexible hose 7. Each tube 5 may have for instance three rows of muzzles or nozzle orifices 5e, said rows being disposed at different angular distances from each other. This provides a possi- bility either by rotation to select the most optimal position for the tube and/or, in connection with the installation of the device, to plug one or more muzzle orifices or all of them in one or more rows using plugs without holes or nozzles having orifices with the same or * different diameter so that the fluid flow from the tube is given the direction and magnitude most suitable for the combustion process, see Figs 9 and 10. The outer jacket 5a, and also the inner tube 5b, has a closed inner end and is to a certain extent occupied by three cooling agent tubes 5e extending helically around the inner tube 5b. At the outer end the cooling agent tubes 5c are provided with a connector, e.g. a quick coupling, covered by a cap 51 and connected to a flexible hose 30 for supplying cooling agent. A similar cap 5f covers a connector, e.g. a quick coupling, for another flexible hose 31 through which the cooling agent exits. The cooling agent tubes 5c are open at its inner end, so that the cooling agent leaving the tubes is given a helical return passage 5i in the spaces between the outer jacket 5a, the inner tube 5b and the cooling agent tubes 5c. The arrangement shown in Fig. 3 allows a most efficient cooling of tube 5. Figs 6 and 7 illustrate a sealing device, operating like an iris diaphragm and disposed at a connector flange 35 at the inner end of the supply unit. Sealing device 36 comprises elements 37 shaped like parts of a circular ring which are rotatably mounted on the connector flange 35 and, under the influence of a drive device 38, movable so that in one position (Fig. 6) tube 5 is released for its axial displacement movement and, in another position (Fig. 7) , they are in sealing engagement with tube 5 in its assumed position. Drive device 38 may e.g. be constituted by a piston rod of a hydraulic cylinder mounted in frame portion 10 (not shown) . The purpose of the cross-sectional view in Fig. 5 is to illustrate that the housing 11 for the cleaning means exhibits two or more opposed sets of steel pins 8 supported by holder means and serving as brushes. During the displacement movement of the tube into or out of the combustion chamber 3 each holding member does itself carry out a governed rotational movement around tube 5. In this way the centrifugal force is utilized for an efficient cleaning of the tube. More exactly stated, brushes 8 are mounted on a holder 40 which is supported by a rotatable shaft 41 at the one end of which there is a gear wheel 42 in engagement with a stationary ring 43 having internal cogs. Shaft 41 is via a ball bearing 50, a bushing 51 and the holder 49 connected to a sprocket wheel 48. The rotational power is transmitted via a chain 47 driven by a motor not illustrated and engaging the sprocket wheel 48. Sprocket wheel 48 is in turn connected with the ring 43 via V-shaped wheels 44 which are in engagement with a V-shaped groove in the circumference of ring 43. The structure described will cause the brushes 48 to rotate at high speed and to with force - but also in a linient way - strike against the tube 5 whereby soot and other particle coatings are efficiently removed. At the same time the axial displacement of the tube will result in a working treatment of all of its envelope surface and of the muzzle orifices. All of unit 39 including the steel pins 8 can be simply replaced upon release of shaft 41 provided with a nut and a screw head. Fig. 8 does diagrammatically illustrate a valve device intended for use when a combustible fluid, e.g. propane, is supplied to the combustion chamber 3 via tube 5. In that case it is important to make sure that no combustible fluid can via the tube pass to the space occupied by device 1 outside the combustion chamber 3. Valve 55, which has a supply line 56 and a outlet line 57 for the alter- * native fluid, is mounted on the frame portion 10 and has a downwardly directed control member 58 which can be actuated by a swingable tongue element 59. When the tube is completely inside the combustion chamber 3, tongue element 59 assumes the position shown in solid lines in Fig. 8 and valve 55 is open. As soon as the outward movement of tube 5 has been initiated the tongue element is by a nob 5m on tube 5 brought into the position shown in dashed lines in Fig. 8 which causes immediate closure of valve 55. In an alternative arrangement the valve is designed so that it becomes impossible to initiate the outward movement of the tube as long as valve 55 remains open. At the mounting and the trimming of the supply unit it is necessary accurately to determine which muzzle orifices 5e shall be open which accordingly also means that the others shall be plugged. In connection with that analysis it is of significant importance to know the temperature in the combustion zone where tube 5 is located. The tube itself can be used for that important determination, namely if a temperature probe 60 is mounted in the area of the inner end of the tube, e.g. in the closed inner end wall of the tube as has been shown in Fig. 3. An accurate mapping of the temperature zones of interest can be carried out in the way that the tube is pushed in stepwise, e.g. half a meter at a time, the temperature being observed at each such stop. When the sizes of the temperature zones have been mapped one determines which muzzles shall be open and which shall be plugged in order to secure the best function. During that testing it is also possible to rotate the tube since, as has been mentioned above, the tube is arranged so that such a rotation is permitted. ' According to the arrangement shown in Figs 9 and 10A-10C the tube has three rows of muzzle orifices 5e located at mutually different angular distances, namely 90°, 120° and 150°, respectively. If all muzzle orifices 5e in one row are provided with plugs 5f of the type shown in Fig. 10A, i.e. they are lacking orifices, then - taking into account the rotational position of tube 5 - the two outlet fluid streams can form corresponding angles between themselves. The other muzzle orifices 5e can be provided with muzzles 5g and 5h, respectively, of the type shown in Fig. 10B and Fig. 10C, respectively, whereby it becomes possible also to control the magnitude of the flows leaving the tube. By way of example, muzzles 5g having small orifices are disposed close to the outer end of the tube, whereas muzzles 5h having large orifices are screwed into the inner end of the tube. In this way it becomes possible to establish different flows in the longitudinal direction of the tube. It is possible to use several different types of threaded muzzles, e.g. having the hole diameters of 5, 10, 12, 15 and 20 mms. The normal way of carry out service work on the kiln plant is to remove the used module unit and to mount a new one which is then connected at the same place as the one removed. To get the best function a test of the type mentioned is carried out before normal use of the new module unit begins. For that reason, maintenance and service of the removed module unit can be carried out, e.g. in a factory. In normal combustion plants at which supply units according to the invention can be used, the length of the tubes usually is 3-6 meters. However, both greater and smaller tube lengths may be used. The module structure of the * supply unit means that it is a comparatively simple operation to make it match the tube lengths wanted in different singular cases.

Claims: Claims 1. A device for supplying a fluid to a combustion chamber (3) in a heat-generating plant, e.g. a boiler or a kiln (2) , said supply device (1) comprising a) a tube (5) located outside the plant and having circumferential holes (5e) , b) drive means (20-27) for axial displacement of said tube (5) into and out of the plant through a hole in the wall thereof, c) means (13-16) for displaceable support of said tube at its outer end, said means being arranged so as to permit rotation of said tube, d) connector means (5g) located in the outer end of the tube (5) for a flexible hose (7) for supply of the fluid from a supply source, e) rotatable means, e.g. steel pins (8) or brushes for cleaning said tube during its inward and/or outward movement, f) means (30) for supplying a cooling agent to said tube (5) , c h a r a c t e r i z e d t h e r e i n that said supply means is constituted by an elongate module unit (1) which, to permit replaceable application on the wall (2a) of said plant (2) , exhibits a preferably flange-shaped connector means (35) surrounding the hole in the wall and having a sealing (37) comprising a number of parts, said parts, when actuated by a drive means (38) , being movable so as to in one position release said tube (5) to perform its axial displacement movement and, in another position to be kept in sealing engagement with said tube in its assumed position. 2. A supply device as claimed in Claim 1, c h a r a c t e r i z e d i n that said sealing means comprises elements (37) shaped like portions of an annular ring and rotatably mounted on a connector flange (35) surrounding the hole in the wall. 3. A supply device according to Claim 1 or Claim 2, c h a r a c t e r i z e d i n that said module unit (1) comprises a frame portion (10) surrounding said tube (5) and preferably having square or rectangular cross-section, and a housing (11) surrounding said cleaning means (8) and their drive means (41-47) at the end facing said wall, said housing (11) exhibiting the connector means (35) of the module unit and said frame portion (10) exhibiting a guide (12) extending along it and being directly or via link means (14, 15, 16) supporting said tube in the area of its outer end. 4. A supply device according to any of Claims 1-3 , a combustible fluid, e.g. methane, propane or ammonium, being supplied to said combustion chamber via said tube (5), c h a r a c t e r i z e d i n that the module unit (10) has an additional valve (55) for the combustible fluid supply and arranged so that, upon a displacement movement of the tube out of the combustion chamber (3) , said valve is immediately closed whereby the supply of combustible fluid is shut off.

Inventors: HAGSTROEM ULF, NORELIUS ERIC, HAGSTROEM, ULF, NORELIUS, ERIC
Applicants: ECOMB AB
Application year: 1999
Main classification: F23J3
IPC codes: F23J3, F23J7, F23L9