AU780381B2 - A feeding device for a fluid to a combustion chamber - Google Patents

Abstract

A device for supplying fluid to a combustion chamber (3) of a furnace (2) or technically equivalent plant includes a pipe which has peripheral openings (5e) and which is supported externally of the furnace combustion chamber (3), and means for moving the pipe axially into and out of an opening in the chamber wall. The fluid is supplied through a flexible hose (7). A cleaning device is arranged in a supply device housing (11) and functions to clean the pipe as the pipe moves inwardly and/or outwardly. Threaded plugs that function as nozzles through which fluid is delivered to the chamber are screwed into one or more of the openings (5e). One (9) of the plugs is provided with a camera lens (60) that enables an on-line-study and/or photoelectric recording of the combustion process in the chamber (3) to be made.

Description

WO 01/51854 PCT/SE01/00051 A feeding device for a fluid to a combustion chamber Field of invention The present invention relates to a supply device for supplying fluid to an internal combustion chamber of a heat generating plant, such as a boiler, incinerator furnace and technically corresponding apparatus, said supply device being of the kind defined in the preamble of Claim 1.

Background of the invention Supply devices of this kind are known to the art from SE,C,9201747-4 (publication number 502 188) and SE,C,9304038-4 (publication number 502 283) (both in the name of ECOMB) and their foreign counterparts.

These known fluid supply devices provide lower emission levels and greater flexibility and enable adjustments to desired emission levels to be achieved quickly and reliably.

Said devices also simplify de-sooting and cleaning of the pipes included in the device, a feature which also enhances the yield of the combustion and vaporisation processes respectively.

The device also enables different fluids or solids to be supplied at different time points, through one or more of said pipes, so that a new optimal operating point can be set in relation to the prevailing operating state of the combustion chamber.

A particular advantage afforded by the known devices is that one or more pipes can be withdrawn while still enabling the combustion or gasification process to continue with the use of the remaining pipes.

Other types of supply devices are described in DE,AI,4 306 765 (Bauer) and 112 216 (Tenn) for example.

A supply device of the kind defined must be able to operate reliably over a long period of time in a demanding environment, in which not least the pipe inserted in the combustion chamber is subjected to high stresses and strains as a result of the high temperature and the corrosive environment that prevail. It is also necessary WO 01/51854 PCT/SEOI/00051 2 to take into 4ccount the changes in temperature that occur when the pipe is withdrawn for cleaning, normally 3-6 times per calendar day.

When using combustion plants that are equipped with fluid supply devices of the aforedescribed kcind, there is a desire to make the combustion process more effective and to reduce the emission of environmentally harmful substances. In order to achieve this, it is necessary to be thoroughly aware of the prevailing state of the combustion process. Proposals hitherto put forward in this regard have not been fully satisfactory, among other things because it. has not been possible to carefully study several of the parametric features or characteristic factors that are significant to an effective combustion process, for instance such as the colour of the combustion gases and the particles, and the intensity in various parts of the combustion chamber. One object of the present invention is to eliminate this deficiency.

Summar of the invention An inventive supply device that fulfils this object is of the aforedescribed kind and has the features set forth in the characterising clause of Claim 1.

One advantage afforded by the invention is that in principle the whole of the hearth can be filmed and displayed continuously downstream of the pipe concerned, e.g. on a display screen in a control room. This advantage is particularly afforded when at least one of the camera lenses is a wide angle lens. This enables the combustion process to be controlled automatically through the medium of computer supported image analysis, for the greatest possible effectiveness while accurately observing environmental aspects.

Outlet openings through which cleaning fluid and cooling fluid can be blown are disposed conveniently around the lens in a lens-accommodating plug. This fluid is preferably the same fluid as that delivered to the combustion chamber and the injection-cleaning action amplifies the effect achieved by the rotatable elements, WO 01/51854 PCT/SE01/00051 3 e.g. steel pins or brushes, used to clean the pipe as it moves inwards and/or outwards.

The possibility of using the process air delivered to the remaining air nozzles of the pipe, these nozzles varying between, 10 and 50 in number, for blowing clean the camera lens and also for cooling said lens is of particular benefit.

The lens and its associated part accommodated in the plug is suitably placed radially from the peripheral surface of the plug at a distance which will enable convection and radiation energy to be transferred from the cold pipe wall to the lens.

Claims 6 and 7 define a supply device with which effective cooling of both the nozzle-equipped supply device and the camera lens are cooled effectively.

The invention also enables the exit angles, the rate of flow and the pressure of the exiting fluid to be adapted continuously with the aid of computer supported image analysis, by rotating the pipe to positions that are in accord with the signals or information that are constantly provided by the image analysis and that disclose changes in ambient conditions, in accordance with the invention.

It is preferred that the supply device is provided in practice with a motor, e.g. an electric motor that includes a chain drive, which turns the pipe automatically to appropriate settings in relation to the result obtained with the image analysis.

The aforesaid helical path travelled by the coolant, both during its passage to said inner end and in its return to said outer end, means that cooling will be particularly effective and therewith increase the useful life of the supply device.

The coolant pipe or pipes and the return passageway are conveniently provided on their outer surfaces with connections, preferably quick-couplings, for connecting-up flexible hoses that are able to accompany the pipe as it moves axially out from and into the uombustion chamber.

Further characteristic features of the invention and the advantages afforded thereby will be apparent from the following description of an exemplifying em- WO 01/51854 PCT/SE01/00051 4 bodiment of the invention. The description is made with reference to the accompanying drawings.

Brief description of the drawings Figure 1 is a perspective sectioned view of the combustion chamber of a heat generating plant, such as a trash or garbage incinerator, equipped with an inventive air supply device, said device being shown in an active state.

Figure 2 is a perspective view of some of the essential components of the supply device shown in Figure 1.

Figure 3 is a broken perspective view of the fluid conveying pipe of the supply device shown in Figures 1 and 2, said pipe having an outer barrel and cooling pipes or ducts.

Figure 4 is a side view of the outer end of the fluid conveying pipe, and shows a suspension arrangement and fluid connections and coolant connections.

Figure 5 is a detailed sectional view of part of the wall of the combustion plant, and a housing which is located at the end of the supply device and which functions to house the pipe cleaning elements.

Figure 6 is a vertical sectional view through the pipe, and shows three threaded openings spaced at different angular distances apart.

Figure 7 is a cross-sectional view of part of a supply device in which there is screwed a plug that accommodates a camera lens and that includes openings through which cleaning air is blown.

Figures 8A-8C illustrate three different types of plug that can be screwed into the threaded openings shown in Figure 6.

Figure 9 is an end view of the inner end of the supply device, said inner end including a flange connection with associated releasable sealing arrangements for co-action with the displaceable pipe.

WO 01/51854 PCT/SE01100051 Finally, Figure 10 is a sectional view taken on the line X-X in Figure 9, from which it will be seen that the sealing arrangement is duplicated and that the intermediate space is placed under pressure by the secondary air supplied, so as to reduce boiler leakage as a result of displacement of the pipe.

Detailed description of preferred embodiments Figure 1 illustrates a combustion plant 2 in the form of a furnace for burning solid fuels, said furnace including a bottom grating (not shown) and an upper combustion chamber 3.

The fuel may be delivered to the furnace either intermittently or continuously, and the air of combustion is injected in the form of primary air, from beneath and up through the grating, thereby generating combustion gases in the combustion chamber 3.

Secondary air is supplied via a number of supply devices, of which one, referenced 1, is shown in Figure 1. The supply device includes an axially movable pipe 5 which enters the combustion chamber 3 through an opening in the furnace wall. The supply device 1 supplies secondary air for the final combustion of gaseous reaction products and solid particles in the combustion chamber 3.

Some of these particles settle on the inner surfaces of the combustion chamber 3, these surfaces being clad with externally insulated water or steam carrying tubes 4. Thus particles also settle on the supply pipes 5, wherewith the openings through which the secondary air is delivered may become blocked either completely or partially, therewith negatively affecting the secondary air supply. As a result, combustion will be incomplete and will result in the type of problem mentioned above.

In the case of the illustrated plant, the fluid supply pipes 5, e.g. for the supply of secondary air, are arranged to form a curtain system that includes a plurality of mutually parallel pipes 5 of this kind at one or more levels in the combustion chamber 3. The pipes 5 are provided with nozzle-shaped openings 5e along the WO 01151854 PCT/SE01/00051 6 full length of the barrel surface of respective pipes. The openings 5e may have mutually different pitches or spacings, and several mutually angled rows of openings may be disposed along the pipes in a manner described in more detail hereinafter with reference to Figures 6 and 8. These openings may be fitted with plugs 5f, 5g, 5h that may optionally function as nozzles.

A fluid, e.g. secondary air with an admixture of concentrated ammonia, recycled flue gas and/or gaseous oxygen at high pressure, is delivered through the medium of a fan or blower (not shown) connected to a collection box 6 from which flexible hoses 7 extend, said hoses being connected to the end-flanges 5b ofrespective pipes 5 by means of quick-couplings.

Depending on the combustion process concerned, the pipes 5 are moved axially into and out of the chamber 3 at longer or shorter time intervals, for instance 3-6 times per calendar day. This enables the emission level of the combustion process to be kept at an optimum level.

The supply device 1 illustrated in Figure 1 is comprised of an elongate module unit that can be applied detachably to the wall 2a of the combustion plant in the region of a pipe accommodating opening in said wall. The modular unit is constructed around a frame part 10 of generally square cross-section. The frame part has at one end a cleaning device in the form of steel pins 8, which function as brushes, and their drive means as described hereinafter with reference to Figure A housing 11 in which the cleaning device 8 and its drive means 41-47 are housed is provided with connecting means that have a connecting flange 35 which surrounds the pipe accommodating opening in the wall 2a.

Extending along the frame part 10 is an upper guide 12 for a carriage 13 which supports the pipe 5 in the region of its outer end, through the medium of links 14, J I.

WO 01/51854 PCT/SE01/00051 7 and a generally U-shaped element 16 surrounding the pipe 5. As before mentioned, the pipe is rotatably mounted to enable the direction of outgoing fluid flows to be optimally set.

The pipe drive means is comprised of an electric motor 20 disposed at the inner end of the frame part 10, said electric motor 20 rotating a shaft 22 via a chain 21 that runs around a sprocket wheel or chain wheel 23 carried by the shaft 22,. Another chain wheel 25 is mounted on a shaft 26 at the other end of the frame part Extending over the chain wheels 23, 25 is a chain 24 which is connected to the link arm 15 via a connecting element 27, such that the pipe 5 will be moved in either direction, depending on the direction of rotation of the electric motor The guide 12 arranged in the region of the roof of the frame part 10 has lower angled legs that define a downwardly facing opening from which the downwardly directed central part 13a of the T-shaped carriage 13 projects. The carriage 13 is able to slide on the beam serving as a guide means, or may be equipped with wheels or rollers for facilitating said movement.

As will be evident from Figure 3, the pipe 5 is comprised of a pipe barrel 5a provided with nozzles or nozzle-like openings 5e, and an inner tube 5b which has at its outer end a connecting flange 5k for co-action with a coupling 7a on the flexible hose 7. Each pipe 5 may have, for instance, three rows of nozzles or jet openings 5e that are disposed at different angular distances from each other. This enables the pipe to be set to its most optimum position, either by rotating the pipe and/or by plugging one or more of the jet openings or all of said jet openings in one or more rows in conjunction with installing the device, said plugs either being devoid of openings, i.e. may be blind, or including nozzles that have nozzle orifices of mutually the same or mutually different diameters, so that the direction WO 01/51854 PCT/SE01/00051 8 and size of the flow of fluid exiting from the pipe will be at an optimum for the combustion process concerned.

The outer barrel 5a and the inner pipe 5b both have a closed inner end and accommodate to some extent three coolant ducts 5c that extend helically around the inner pipe 5b. The coolant ducts 5c are provided at their outer ends with a connection, e.g. a quick-coupling, which is covered by a casing 51 and which is intended for co-action with a flexible coolant-supply hose 30. A connection, e.g. a quick-coupling, for a further flexible hose through which the coolant departs is covered by a similar casing The coolant ducts 5c are open at their inner ends, so that the coolant leaving the ducts obtains a helical return passageway 5i in the spaces defined between the outer barrel 5a, the inner pipe 5b, and the coolant ducts 5c. The arrangement illustrated in Figure 3 affords very effective cooling of the pipe The cross-sectional view shown in Figure 5 is intended to illustrate that the housing 11 for the cleaning devices has two or more mutually opposing steel pins which are carried by holder elements and which function as brushes, wherein said holder elements execute a controlled or guided rotary movement around the pipe as the pipe moves into and out of the combustion chamber 3, thereby utilising the centrifugal force thus generated to effectively clean the pipe.

More specifically, the brushes 8 are disposed on a holder 40 carried by a rotatable shaft 41 which has at one end thereof a gearwheel 42 that rolls against the inner teeth of a fixedly mounted toothed wheel 43. The shaft 41 is fitted to a chain wheel 48, via a ball bearing 50, a bushing 51 and the holder 49. The rotational force is transferred via a motor-driven chain 47 that engages the chain WO 01/51854 PCT/SE01/00051 9 wheel 48, the motor driving said chain not being shown in the figure. The chain wheel 48 is, in turn, mounted for co-action with the toothed ring 43 via V-shaped wheels 44 that engage in a similar V-shaped groove in the periphery of the toothed ring 43.

As a result of the construction described above, the brushes 8 rotate at a high speed and strike against the pipe 5 forcibly, although also gently, so as to effectively dislodge soot and other particle deposits. The axial displacement of the pipe also results in the treatment of the entire barrel surface and the nozzle openings disposed therein. The unit 39 with its steel pins 8 can be easily exchanged in its entirety, after loosening the shaft 41, by releasing its nuts and bolts.

Figure 7 illustrate a plug 9 screwed into the opening 5c in the pipe 5. The plug 9 is provided with a camera lens 60 which enables an on-line-study and/or photoelectric recording of the combustion process to be made through the medium of a conductor connection 61. This enables the combustion process in the chamber 3 to be influenced through the medium of signals sent, for instance, to a pressureand-flow regulating fan or blower. The illustrated lens 60 is a wide angled lens that enables, in principle, the entire hearth to be filled and displayed continuously directly on a display screen or via a video in a control room.

The plug 9 includes a large number of exit openings 63 of small diameter, through.

which air, consisting of the process air delivered to the combustion chamber 3, is injected to blow clean the lens 60 and to cool said lens.

The lens 60 and its conductor connection 66 are also cooled by surrounding coolant, i.e. water, in the aforedescribed helical flow path, and can thereby be kept WO 01/51854 PCT/SE01/00051 free from deposits. The "coarser" cleaning process effected via the brush system described with reference to Figure 5 is also a contributory factor in this regard.

That part of the camera lens 60 accommodated in the plug 9 is spaced at a distance from the plug periphery such as to enable convection and radiant energy to be transmitted from the cold pipe wall to the lens. Although not shown, the pipe is also provided with an electric motor by means of which the pipe can be rotated through 1800 in either direction via a chain drive (not shown).

It is thus possible with the aid of computer-supported image analysis via the camera lens 60 to continuously adapt the direction, the flow rate, and the pressure of the air exiting from the plugs 5g, 5h (Figure 8) such as to enable an effective combustion process to be achieved in response to signals and information disclosed by the image analysis with respect to changes in underlying conditions.

When fitting and tuning the fluid supply device, a carefully considered decision is made as to which nozzle openings 5e shall be open and therefore also which of the openings shall be plugged. The camera can also be utilised in making this decision. It is also important to know the temperature in the combustion zone in which the pipe 5 is situated, in conjunction with said analysis. This important parameter can be determined with the aid of the pipe itself, namely by placing a temperature sensor in the region of the inner end of said pipe, for instance in the closed inner end-wall of said pipe as illustrated in Figure 3.

Accurate mapping of current temperature zones can be effected by inserting the pipe stepwise, for instance through half a meter at a time, and reading-off the temperature each time insertion of the pipe is stopped. The camera can also be used in this process.

WO 01/51854 PCT/SE01/00051 11 After having mapped the propagation of these temperature zones, those nozzles 9 that shall be open and those nozzles that shall be plugged to obtain the best function are determined. The pipe may also be rotated during the course of the testing process, said pipe being rotatable as mentioned in the aforegoing.

In the case of the embodiment illustrated in Figure 6 and in Figures 8A-8C, the pipe has three rows of nozzle openings 5e which are disposed at mutually different angular distances, e.g. angular distances of 90°, 120° and 1500 respectively.

When all nozzle openings 5e in one row are fitted with blind plugs 5f of the kind illustrated in Figure 8A, the two exiting jets of fluid are able to define corresponding angles relative to one another in relation to the position to which the pipe 5 has been rotated.

Remaining nozzle openings 5e may be fitted with respective nozzles 5g and 5h of the type illustrated in Figure 8B and in Figure 8C respectively, thereby also enabling the magnitude of the flow exiting from the pipe to be regulated. For instance, nozzles 5g that have small openings may be placed close to the outer end of the pipe, whereas nozzles 5h that have large openings may be screwed into the inner end of the pipe. This will thus enable different flows to be obtained in the longitudinal direction of the pipe.

Several different types of threaded nozzles 5g, 5h, e.g. having opening-diameters of 5, 10, 12, 15 and 20 mm, may be used.

Figures 9 and 10 illustrate a double sealing arrangement 35 which functions similarly to two iris diaphragms or shutters and which is disposed on a connecting flange 36 for connection to the boiler wall 2a at the inner end of the supply device, said inner end having a bottom flange 47. The sealing arrangement 35 has WO 01/51854 PCT/SEOI/00051 12 two arrays of sealing elements on a sealing device 37 which has the form of a circular ring and which includes a turning flange 49, said device being rotatably carried via a centre bolt 39 and provided with arcuate slots 38 in which the bolt 39 can run.? Respective turning flanges 49 are also provided with arcuate slots in which the bolt 39 can run. The turning flange 49 is provided with a turning arm 40 by means of which the flange 49 can be rotated through the medium of the piston rod (not shown) of a pneumatic or an hydraulic cylinder (not shown) fitted to the frame part 10, wherewith rotation of said flange 49 causes the sealing elements 37 to move radially outwards or radially inwards, depending on the direction in which the flange is rotated.

Radial inward movement of the sealing elements causes said elements to abut the pipe 5. The sealing elements are moved out of engagement with the pipe 5 when rotated in the other direction, therewith enabling the pipe to be moved axially.

As will be seen from Figure 10, the two parts of the double sealing arrangement are spaced axially apart. A fluid, in the illustrated case secondary air, is delivered to the intermediate space 42 via a peripherally disposed air sleeve or nipple There is maintained in the space 42 in this way an overpressure in relation to the boiler that prevents leakage from the combustion chamber 3 when the pipe is in its inserted position.

251 The sileeve 45 IS supplid with the same seconduary airu as that delivered to LIM combustion chamber, via a separate conduit (not shown). The fluid supplied thus has a double purpose.

WO 01/51854 PCT/SE01/00051 13 A double seling arrangement of the described kind with separate supply of secondary air for sealing purposes in conjunction with axial movement of the pipe has been found in practice to be much more effective than an arrangement that includes only one single set of sealing elements of the aforedescribed kind that function similarly to an iris diaphragm or shutter. The arrangement also ensures a reliable result from the aforedescribed tuning process in which the camera lens is used.

The reference numeral 47 in Figure 10 identifies bottom flanges associated with the double sealing arrangement, while reference numeral 48 identifies a spacing element, 49 identifies two turning flanges and 50 identifies two guide flanges.

Servicing of the furnace plant proceeds as normal, where earlier used modular units are removed and a new unit is applied by connecting the unit in the same place as that earlier occupied by the removed unit. In order to obtain the best function, a test of the aforedescribed kind is carried out prior to commencing normal use of the new modular unit. Maintenance and servicing of the removed modular unit can therefore be carried out in the factory, for instance.

In the case of typical combustion plants with which the inventive supply device can be used, the pipes will normally have a length of 3-6 meters. Both longer and shorter pipe lengths, however, may be used. The module construction of the supply device enables the device to be adapted relatively easily to pipe lengths desired in different individual cases.

Claims (9)

1. A supply device for supplying fluid to a combustion chamber of an heat generating plant, for instance to as boiler, incinerator or furnace wherein the supply device includes a) a pipe which is supported externally of the plant and includes peripheral openings b) drive means (20-27) for moving the pipe axially into and out of the plant through an opening in the wall of said plant, c) means (13-16) for displaceably supporting the pipe at its outer end, said means being constructed to enable the pipe to be rotated about its longitudinal axis, d) means (5g) disposed at the outer end of the pipe for connection with a flexible hose that functions to deliver the fluid from a supply source, e) rotatable elements e.g. steel pins or brushes for cleaning the pipe in con- junction with its inward and/or outward movement, f) means (30) for delivering coolant to the pipe g) one or more preferably threaded openings (5e) in the pipe said openings being adapted to receive plugs 5f, 5g, 5h), preferably plugs that can be screwed into said openings, and wherein the supply device is characterised in that one or more of said plugs includes a camera lens (60) which enables an on- line-study and/or photoelectric registration to be made, via an associated con- ductor connection that can be used to influence the combustion process in the chamber

2. A supply device accor'ding to Claim 1, characterized in that at least one lens is a wide angle lens. WO 01/51854 PCT/SE01/00051

3. A supply .device according to Claim 1 or 2, characterized in that the plug has around the lens outlet openings (63) through which cleaning and cooling fluid can exit.

4. A supply device according to Claim 3, characterized in that the cleaning and cooling fluid is the same fluid as that delivered to the combustion chamber A supply device according to Claim 3 or 4, characterized in that the lens and that part of the lens accommodated in the plug are spaced at a radial dis- tance from the peripheral surface of the plug such as to allow convection and ra- diant energy to be transmitted from the cold pipe wall to the lens.

6. A supply device according to any one of Claims 1-5, wherein the pipe has an outer barrel surface (5a) that includes the peripheral plug-accommodating open- ings, characterized in that one or more coolant ducts (5c) extends or extend heli- cally between the inner pipe (5b) at its outer barrel surface wherein the coolant duct or ducts (5c) is/are open at their inner end and the inner pipe and the outer barrel (5a) are closed at their inner end, so as to obtain a helical fluid return passageway (5a) in the spaces between the outer barrel the inner pipe (5b) and the coolant duct or ducts

7. A supply device according to Claim 6, characterized in that the helical coolant ducts are replaced with walls between the pipe and the surrounding barrel.

8. A supply device according to any one of Claims 1-7, which includes drive means for rotating said pipe, characterized by means for adapting the outflow di- rection, rate of flow and pressure of the fluid supplied via the pipe nozzles with the aid of computer supported image analysis and in response to signals and in- WO 01/51854 PCT/SE01/00051 16 formation, obtained in said image analysis with respect to the state of combustion in the combustion chamber.

9. A supply device according to any one of Claims 1-8, wherein the pipe is pro- vided with a sealing arrangement (35) which surrounds the opening in the wall (2a) and which includes sealing elements which engage the pipe in their seal- ing position and which can be moved by drive means (40) to a first position in which the pipe is free for axial movement and a second position in which said sealing elements are held in sealing abutment with the pipe in the set position of said pipe, characterized in that a double array of sealing elements (37) are dis- posed in axially spaced relationship; and in that the spaces (42) between the two array of sealing elements are held under an overpressure at least in the inserted position of the pipe

10. A supply device according to Claim 9, characterized in that the same fluid as that delivered to the interior of the pipe and the combustion chamber, e.g. secondary air, is delivered to the intermediate spaces (42) from said supply source via a separate supply conduit.