WO2011063912A1 - A waste disposal plant with fire bar approaching system. - Google Patents

A waste disposal plant with fire bar approaching system. Download PDF

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Publication number
WO2011063912A1
WO2011063912A1 PCT/EP2010/007027 EP2010007027W WO2011063912A1 WO 2011063912 A1 WO2011063912 A1 WO 2011063912A1 EP 2010007027 W EP2010007027 W EP 2010007027W WO 2011063912 A1 WO2011063912 A1 WO 2011063912A1
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WO
WIPO (PCT)
Prior art keywords
fire bars
grate
fire
fixed
tie
Prior art date
Application number
PCT/EP2010/007027
Other languages
French (fr)
Inventor
Emanuele Corbani
Original Assignee
Tm.E S.P.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tm.E S.P.A. filed Critical Tm.E S.P.A.
Publication of WO2011063912A1 publication Critical patent/WO2011063912A1/en

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23GCREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/002Incineration of waste; Incinerator constructions; Details, accessories or control therefor characterised by their grates
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23HGRATES; CLEANING OR RAKING GRATES
    • F23H17/00Details of grates
    • F23H17/08Bearers; Frames; Spacers; Supports
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23HGRATES; CLEANING OR RAKING GRATES
    • F23H7/00Inclined or stepped grates
    • F23H7/06Inclined or stepped grates with movable bars disposed parallel to direction of fuel feeding
    • F23H7/08Inclined or stepped grates with movable bars disposed parallel to direction of fuel feeding reciprocating along their axes
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23GCREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2203/00Furnace arrangements
    • F23G2203/101Furnace arrangements with stepped or inclined grate

Definitions

  • the present invention relates to a combustion grate, having a modular frame, and being installed in the furnace of a waste disposal plant, in which the aforesaid waste is burnt and so disposed of as ashes.
  • Such disposal generally comprises also an energy recovery system through the production of overheated steam and the exploitation of steam in a turbine, which in turn is coupled to an electric generator.
  • Such plants generally comprise a combustion chamber inside which the waste laid on a combustion grate is burnt, through which an adequate quantity of air is inputted.
  • the combustion grate is adapted to sustain and put forward the waste during the combustion permitting at the same time the insufflation of combustion air under the waste bed.
  • the grate forms the lower portion of the combustion chamber.
  • the combustion chamber begins physically immediately above the grate.
  • the walls of the combustion chamber are completely or partially cooled, by means of evaporation tube bundles protected by the refractory itself.
  • the region at the interface between grate and combustion chamber is made by the refractory-carrying beam.
  • the flame produced by the combustion of waste is spread, reaching temperatures over 1400°C.
  • the surface of the grate is hit only occasionally by the radiation of the flame, as it is normally protected by the waste bed in transit.
  • the surface of the grate is made by plates
  • fire bars which are normally made of molten steel having a high chromium content, in order to show high wear characteristics when hot.
  • the advancement of waste is obtained through the relative movement of the fire bars which can have several characteristics.
  • the actuation system is normally made of hydraulic pistons.
  • the fire bars are provided with apertures or holes to allow the combustion air to flow from underneath the plane of the grate, through the waste.
  • the combustion air has in fact the double function of providing the oxygen for the oxidation of the waste and of cooling the fire bar by maintaining it at an acceptable temperature in order to maintain the mechanical characteristics.
  • the cooling is necessary, as the grates normally work covered by the forwarded fuel, but they can also be directly exposed to the combustion flames.
  • the steps making the grate can also be provided with an additional cooling with water, particularly when they are used for the combustion of fuels with high calorific power.
  • Such cooling is made by a liquid circulation which is forced to lap the surfaces which do not contact the fuel of each fire bar, through a liner or an equivalent apparatus for the accumulation of liquid.
  • the fire bars at the initial and terminal ends of each step are separated from the carrying structure of the grate by means of plates, generally of the same material of the fire bar, which are approached with pressure against the side of the side bar itself.
  • plates have the function of laterally containing the fuel forwarded in the region immediately above the fire bars, and of separating it from the lateral portions of the grate, which do not tolerate the direct exposition to the burning material.
  • the lateral plates eventually join the plane made by the fire bars with the vertical surfaces of the combustion chamber, which are disposed immediately above the grate.
  • the grate further comprises a plurality of handling groups, each formed by the cited fire bars organized in bundles, which relatively move one with respect to the other putting forward the waste on the grate.
  • the fire bars are divided in fixed and movable fire bars, which through slides cause a back-and- forth movement, by sliding one on another and determining the advancement of the waste in each handling group, and so in general on the grate.
  • the disposal of the solid urban waste is an activity particularly sensible from' a point of view of the reliability and the guarantees of the function.
  • the complex integrated system of the waste disposal (the accumulation, the collection, the transport, the stockpiling and the disposal) requires that the technological components employed in the last stage of the supply chain permit a continuous operation over 24 hours and minimize the risks of stopping due to damages (minor or catastrophic damages as they can be) .
  • the operator of the disposal plant requires reliability robustness and simplicity of the component "grate" , both in the operation and in the maintenance.
  • Patent application MI2004A001746 describes a plant of this kind having a movable combustion grate, in which the handling group is formed by a plurality of fire bars, which alternatively move one with respect to the other by putting forward the waste on said grate, which realizes a substantially horizontal and at least partially continuous combustion plane.
  • the movable fire bars are bound to a movable frame, which is pushed by two pistons, one on each side.
  • the fixed fire bars are in turn connected with a fixed frame, common to all fixed fire bars.
  • the relative movement between the fixed frame and the movable frame is of a simple alternate translation.
  • the grate is further provided with sliding elements able to determine the sliding between the two frames and elements limiting the movement between them which determine its stroke.
  • the movable fire bar pushes the waste on the back of the fixed fire bar until causing its fall onto the subsequent movable fire bar, and at the same time it drags the waste on its own back.
  • the waste on the back of the movable fire bar finds an obstacle on the front of the fixed fire bar and, instead of moving back, it is pushed onto the back of the fixed fire bars downwards and then it is pushed forwards in the subsequent displacement, so determining the advancement of the waste in each handling group on the grate in general.
  • the sliding elements are substantially made by bearings or rolls upon which a pad slides substantially integrally with the moveable frame with an inclination dependent on the direction of movement which the moveable frame must communicate to the fire bars.
  • the movement limiting elements comprise a track integral with the carrying or fixed frame, whereas to the movable frame of the grate two wheels are in turn connected, bound to a fixed axis.
  • the wheels are mounted with a transversal clearance with respect to the track.
  • the movable frame is usually handled by hydraulic pistons with interposed crank gears and traditionally it is made by a carrying frame, made of longitudinal and transversal beams.
  • a carrying frame made of longitudinal and transversal beams.
  • fire bar-carrying beams are fixed, on which the same fire bars rest.
  • pads are instead fixed, which slide on the rolls of the sliding elements by giving to the mobile frame the correct direction of movement .
  • the fire bars are kept mutually aligned along the plane of the grate, through lateral plates which are maintained kept together on each side of them through fire bar . approaching systems.
  • Aim of such systems is to compensate the transversal displacements of the outer surfaces of the end fire bars, due for example to the movement of the fire bars integral with the movable frames and to the thermal expansions.
  • a first kind of system is called a "pusher" system, i.e. it is made of a cylindrical sliding pusher inside a seat and provided with a glass-shaped head which pushes the lateral plates against the fire bars by acting on the outer surface of the plates themselves.
  • the pushing force is given by an elastic member, compressed between the pusher and a support integral with the fixed frame of the grate.
  • Such kind of technological solution has a remarkable constructive complexity and increases the transversal encumbrance of the modules of the grate.
  • the presence of pushing assemblies impairs the approaching of two parallel modules of the grate for the realization of grates for combustion chambers with a high transversal width.
  • the unavoidable accumulation of ashes and unburned substances in the region of the glass-shaped head can then cause malfunctions of the pusher for the accumulation of ashes between the pusher itself and the seat within which it flows, with the risk of seizures.
  • a second kind of system is called a "tie-rod" system, in which the approaching of the lateral plates to the fire bars is obtained by means of a tie-rod provided with ends so formed to engage in a seat formed in the lateral plates.
  • the tie-rod has an elastic element (provided with a tension regulator) the traction force of which is transferred through the profiled ends to the lateral plates, which are kept forcibly together to the fire bars.
  • the elastic elements and the tension regulator are mounted under the fire bars and are so exposed to the fall of ashes from the plane of the fire bar themselves.
  • the ashes can accumulate on the elastic elements and on the tension regulator so impairing their correct function.
  • Both the elastic elements, and the regulator and the tie-rod must further be made of materials able to sustain both the air temperature of the pressurized volume (near to 200°C) , and the chemical aggression of the combustion ashes .
  • the tension regulator is mounted at the symmetry axis of the module and requires an operator to enter inside the pressurized volume under the plane of the grate in order to regulate it, which operation can be made with safety only with the grate still and cold, with considerable burdens for plant shutdown.
  • figure 1 is a schematic presentation of a waste disposal plant according to the known art, which provides for a three -level combustion grate ;
  • figure 2 is a schematic presentation of a handling group of the grate of the plant of figure 1;
  • figure 3 is a perspective view of the upper portion of the grate according to the present invention, usable in the plant of figure 1 ;
  • figure 4 is a perspective view of the lower portion of the grate according to the present invention usable in the plant of figure 1;
  • figure 5 shows a handling assembly comprising sliding elements and movement limiting elements ;
  • figure 6a shows a side view of a movable frame of the grate of figures 3 and 4;
  • figure 6b shows a top view of a movable frame of the grate of figures 3 and 4.
  • figure 7 shows a sectional view of the system for approaching the fire bars according to the present invention.
  • a typical waste disposal plant comprises a combustion chamber 2 inside which the waste disposed on a combustion grate 3 are burnt, through which an adequate quantity of combustion air is inputted.
  • the grate makes the lower region of the combustion chamber, above which a beam 4 is present, which has also the function of supporting lateral refractory walls 5.
  • the walls of the combustion chamber are completely or partially cooled, through evaporating tube bundles 6 which are protected by the refractory material itself.
  • the combustion grate comprises at least a handling group made by a plurality of fire bars 7, which move alternately one with respect to the other by advancing the waste on the grate .
  • the handling groups are three disposed offset one with respect to the other, in order to obtain a horizontal discontinuous placement (stepped or with jumps) .
  • Each handling group is actuated by handling means 8 made for example by at least a hydraulic piston.
  • Such handling means allow the alternate movement of fire bars 7 which are divided in movable fire bars 7a and fixed fire bars 7b, alternately disposed one with respect to the other, on transversal rows resting one on the other according to a longitudinal disposition with alternate steps, respectively with one fixed and one movable .
  • the movable fire bars are connected to movable beams 9a and are bound to a movable frame 10a, which is pushed by two pistons, one on each side.
  • the fixed fire bars are in turn connected through fixed beams 9b with a fixed frame 10b common to all fixed fire bars.
  • the relative movement between the fixed frame and the movable frame is of a simple alternate translation.
  • the relative movement of the fire bars is of an alternate translation preferably according to a direction inclined of 20° on the horizontal.
  • the grate is also provided with sliding elements 11 adapted to determine the sliding between the two frames and elements 12 limiting the movement between them, which determine their movement according to predefined trends.
  • the movable fire bar pushes the waste on the back of fixed fire bar 7b until causing its fall from the subsequent movable fire bar, and at the same time it drags the waste on its own back.
  • the waste on the back of the movable fire bar finds an obstacle in the front of the fixed fire bar, and instead of going back, it is pushed downwards onto the back of the fixed fire bar and therefore it is pushed forward in the subsequent stroke, by determining the advancement of the waste in each handling group and then on the grate in general.
  • a handling group of the grate comprising a carrying frame including two lateral beams 36 and two transversal cross-beams 37.
  • Lateral beams 36 are preferably realized with a closed square or rectangular cross section and are connected to crossbeams 37 by means of a knot 38 structurally equivalen to a joint, positioned on the upper portion of lateral beams 36 themselves.
  • Knot 38 also comprises a reference (plug or equivalent device - non represented) which permits to precisely position cross-beams 37 with respect to lateral beams 36 during the assembly of the module of the grate.
  • axes of wheel assemblies 39 are mounted, which permit the relative movement between the carrying frame and movable frame 40.
  • the supports of bearings 41 of actuating shafts 42 are on the contrary fixed.
  • an upper sheet 43 is fixed to the upper portion of beams 36 .
  • Such sheet separates the lateral plates from the outside and forms the connecting element between the carrying frame and the upper portion of the furnace (non represented) , for example comprising thermal insulating panels and respective fixing sheeting.
  • apertures 44 are formed which permit the access to the sealing elements of the lateral plates. Apertures 44 must be air-tightly closed through flanges 45, doors or other closures of equivalent function.
  • a lower non-structural sheet 47 is instead fixed. Sheet 47 together with beams 36 delimits from the two sides of the module of the grate the pressurized volume which provides supply air to fire bars 7.
  • flanges 48 and 49 are fixed, whose outer surfaces are made to match in order to couple two successive modules, for example through bolts with gasket or other equivalent air-tight connection.
  • Flanges 48 and 49 are provided with upper extensions 50 and lower extensions 51, which permit to directly couple two successive modules also at upper sheets 43 and of lower sheets 47.
  • Front flanges 48 are finally provided with a lateral extension 52 to which a connection element 53 is fixed, for the hydraulic cylinder moving actuating shaft 42. The handling of the actuating shaft takes place through a lever 54 fitted flush on shaft 42 itself.
  • Beams 36 as well as having a structural function incorporate the seats of all the inner and outer mechanical parts of the module of the grate, lateral sheets 43 and 47, which make the sides of the module itself and connecting flanges between successive modules .
  • the assembly of the carrying frame of each module requires exclusively the coupling of the beams 36 specular for the two sides of the module, to cross- beams 37 by means of knot 38, provided with reference elements (non represented) for the correct coupling.
  • beams 36 nearly all the working operations on the machine tools are further concentrated, which are necessary in order to provide for the assembly of the module of the grate, as beams 36 are integral with the seats of all the inner and outer mechanical parts, flanges 48 and 49 coupling the successive modules and the coupling and reference surfaces to cross-beams 37 (non represented) .
  • beams 36 have a reduced length in order to permit the transport of the modules without resorting to exceptional transport means, they can be worked with reduced times and costs with respect to the completely assembled modules of the today produced grates.
  • the only working operations at the machine tools which are not positioned on beams 36 are those of the coupling surfaces of knot 38 which are integral with cross-beams 37 and which must be referred to the corresponding surfaces on beams 36.
  • FIG 5 a guide assembly of the movement of the movable frame is shown, comprising a sliding element and a movement limiting element integrally mutually coupled.
  • Such assembly 39 comprises essentially an axis 55, which is associated to the fixed or carrying frame, formed by an outer shaft 56, which engages in a seat 57 realized inside lateral beams 36 of the carrying frame, and an inner shaft 58 instead cantilevered under the plane of the grate.
  • On such inner shaft one or more wheels 71 with a substantially horizontal axis are fitted flush, eventually separated by a spacer 95, on which movable 40 slides (non represented in this figure) .
  • a bushing 72 is instead fitted flush with a sliding, coupling along axis 55, to which .one or more wheels 73 with a substantially vertical axis are fixed, which encounter a movable edge of the frame, in order it to be forced to move on a seat inferiorly delimited by wheels 71 and laterally by wheels 73.
  • bushing 72 is separated by the side of seat 57 by an elastic member 97, for example realized by a cup spring or an equivalent device.
  • the slipping of the axis from seat 57 is prevented by two ring nuts 74 which clamp between them sequentially wheels 71, spacer 95, bushing 72, elastic element 97 and seat 57.
  • the deformation of the elastic element permits to regulate the transversal position of the axis in order to bring wheel 73 in contact with movable frame 40.
  • Wheels 73 are aligned with the direction of movement of the movable frame by utilizing a reference mark (non represented) integral with the bushing to which the wheels themselves are anchored. The reference mark is blocked in a seat made in the carrying frame (non represented) .
  • Elastic element 97 allows bushing 72 a limited sliding on outer shaft 56 following the contact with movable frame 40, and with its deformation, continuously increases starting from zero the force which maintains movable frame 40 within the correct trajectory.
  • lubrication ducts 98 are advantageously provided, for sending greases or oils to sliding wheels 71 and to movement limiting wheels 73.
  • the guide assembly according to the present invention has a remarkably simpler construction with respect to the known ones. First, it integrates in a single assembly made from few pieces both sliding elements 11 and movement limiting elements 12 of the movable frame. The entire assembly is further bound to the carrying frame through a single coupling shaft-hole between axis 55 and seat 57.
  • Assembly 39 is installed at the lateral beams 36, and so it is more protected from the dust present in the pressurized volume underneath the plane of fire bars 7, and it is immediately accessible for inspection. Wheels 71 are further cantilevered inside the pressurized volume underneath the plane of fire bars 7 and do not have any support structure, in which dust can accumulate . The result is a greater predictable feasibility and duration of wheels 71 themselves.
  • the assembly in the indicated position permits to position the inlet hole of the lubricant on the surface of the axis facing the outside of the module. In this way it is not necessary to install any lubrication tubing inside the machine.
  • movable frame 40 comprising a front fire bar-carrying beam 114 with a carrying function and a rear fire bar-carrying beam 115 also with a carrying function.
  • a front fire bar-carrying beam 114 with a carrying function
  • a rear fire bar-carrying beam 115 also with a carrying function.
  • To the front fire bar- carrying beam two tracks 116 are fastened which slide, during the movement of the movable frame, on wheels 71.
  • To the rear fire bar-carrying beam two similar tracks 117 are fastened, which also are sliding on wheels 71 of underlying assembly 39. Tracks 116 and 117 can advantageously be provided with replaceable wear plates 118.
  • vertical carrying guides 120 are fastened, also possibly provided with replaceable wear plates 121.
  • the vertical carrying guides are fastened, at the lower ends, to tracks 116.
  • the alternate rectilinear movement of the movable frame is exerted on shaft 42, by means of lever 54 for example actuated by the hydraulic cylinder (see figure 4), provided with two pushing wheel assemblies 122.
  • Wheel assemblies 122 engage in vertical guides 120 and by alternatively sliding in contact with front 123 and rear 124 sides of guide 120, due to the rotation of actuating shaft 42, cause the back and forth movement of the movable frame.
  • the movable frame which is the object of the present invention and is represented in figure 6 has a much more simple construction with respect to those produced nowadays, as it incorporates in the structural elements all the functional parts for its movement and for supporting the fire bars.
  • the front and rear tracks serve in fact also as support beams of the frame itself.
  • an ad hoc structure is not required for housing guides, as the latter are made in columns 120 necessary for realizing the difference in level between front fire bar-carrying beam 114 and rear fire bar-carrying beam 115.
  • Wheels limiting the movement 73 come in fact in contact directly with outer sides 125 of tracks 116 and 117, possibly with a wear plate (non represented) interposed.
  • an approaching systems of the fire bars comprising a tie-rod, inserted inside a resting tube 711 of fire bars 7 integral with cross-beam 37 of the carrying frame provided at opposite ends of abutment discs resting at the outside of lateral plates 80, and provided with elastic means able to exert a traction force between the two discs which is transferred through the lateral plates, which are forcibly approached to the fire bars.
  • such system comprises an elastic pusher 139 provided at one end of a first abutment disc 140, resting on supporting saddle 141 of the lateral plates.
  • the first abutment disc is connected, through threading or other equivalent system, to a spring-carrying cylinder 142.
  • Spring-carrying cylinder 142 has the double function of relating pusher 139 to the fire bar- carrying tube and to bind abutment disc 140 to coil spring 143 which gives elasticity to the pusher.
  • Spring 143 is connected, at the other end, with a terminal of a tie-rod attachment 144, a cylinder threaded at one end which has the function of connecting pusher 139 to a tie-rod 145.
  • a rigid pusher 146 is mounted, comprising a second abutment disc 147 associated to a reference cylinder 148. Also in this case second abutment disc 147 rests on support saddle 141 of the lateral plates. Cylinder 148 has a through hole 149 which is traversed by the threaded end of tie-rod 145. At the end of tie-rod 145 and in contact with the outer end of abutment disc 147, a nut 150 is mounted.
  • tie-rod 145 and elastic pusher 139 is inserted, from the side of the tie-rod, into the fire bar-carrying tube until bringing abutment disc 140 in contact with the outer end of support saddle 141 of lateral plates 80.
  • rigid pusher 146 is inserted in turn inside the fire bar-carrying tube, by sliding the end of tie-rod 145 inside through hole 149 until bringing abutment disc 147 in contact with support saddle 141 of lateral plates 80.
  • the approaching system of the fire bars according to the present invention has following advantages in comparison with those of normal production. First of all, all the components are mounted inside the fixed fire bar-carrying tube. Therefore they are completely protected both from the dust coming from the plane of the fire bars and from the hot air of the pressurized volume underneath the fire bars. They have therefore a greater feasibility and lesser production costs.
  • the regulation of the contact pressure between plates 80 and fire bars 7 is done by uniquely acting on nut 150, from a single side of the module of the grate through apertures 44. This means that the regulation is done from the outside of the machine and it does not require an access to the pressurized volume under the grate. Therefore it can be . done in a safety way by stopping and depressurizing just one module without stopping the entire grate, with a dramatic reduction of the plant shutdown times.
  • system according to the present invention permits to exactly obtain the same approaching force between plates 80 and end fire bars 7 through the only regulation of the position of nut 150. In this way dissymmetries of the approaching force are avoided, which can amplify the sideslip of movable frame 40.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Processing Of Solid Wastes (AREA)
  • Refuse Collection And Transfer (AREA)
  • Incineration Of Waste (AREA)

Abstract

A waste disposal plant comprising a combustion chamber (2) inside which waste laid on a combustion grate (3) are burnt, which permits the entrance of an adequate quantity of combustion air in the chamber through it, said combustion grate comprising at least a handling group formed by a plurality of fire bars or plates (7), which move alternatively one with respect to the other by advancing the waste on said grate and are divided in movable fire bars (7a) and fixed fire bars (7b), alternately disposed one with respect to the other, on transversal rows resting one upon the other according to a longitudinal placement with alternate steps, such fixed fire bars being bound to a fixed frame and such movable fire bars being bound to a movable frame, which moves through handling means (8) with respect to the fixed one. Such fire bars (7) are kept mutually aligned along the plane of the grate, through lateral plates. (80) which are kept approached on both sides of them through a fire bar approaching system.

Description

A WASTE DISPOSAL PLANT WITH FIRE BAR APPROACHING SYSTEM
The present invention relates to a combustion grate, having a modular frame, and being installed in the furnace of a waste disposal plant, in which the aforesaid waste is burnt and so disposed of as ashes.
Such disposal generally comprises also an energy recovery system through the production of overheated steam and the exploitation of steam in a turbine, which in turn is coupled to an electric generator.
Such plants generally comprise a combustion chamber inside which the waste laid on a combustion grate is burnt, through which an adequate quantity of air is inputted. The combustion grate is adapted to sustain and put forward the waste during the combustion permitting at the same time the insufflation of combustion air under the waste bed. The grate forms the lower portion of the combustion chamber. The combustion chamber begins physically immediately above the grate. In some cases, the walls of the combustion chamber are completely or partially cooled, by means of evaporation tube bundles protected by the refractory itself. The region at the interface between grate and combustion chamber is made by the refractory-carrying beam. Inside the combustion chamber, the flame produced by the combustion of waste is spread, reaching temperatures over 1400°C. The surface of the grate is hit only occasionally by the radiation of the flame, as it is normally protected by the waste bed in transit.
The surface of the grate is made by plates
(typically called "fire bars") which are normally made of molten steel having a high chromium content, in order to show high wear characteristics when hot. The advancement of waste is obtained through the relative movement of the fire bars which can have several characteristics. The actuation system is normally made of hydraulic pistons. The fire bars are provided with apertures or holes to allow the combustion air to flow from underneath the plane of the grate, through the waste. The combustion air has in fact the double function of providing the oxygen for the oxidation of the waste and of cooling the fire bar by maintaining it at an acceptable temperature in order to maintain the mechanical characteristics. The cooling is necessary, as the grates normally work covered by the forwarded fuel, but they can also be directly exposed to the combustion flames.
The steps making the grate can also be provided with an additional cooling with water, particularly when they are used for the combustion of fuels with high calorific power. Such cooling is made by a liquid circulation which is forced to lap the surfaces which do not contact the fuel of each fire bar, through a liner or an equivalent apparatus for the accumulation of liquid.
The fire bars at the initial and terminal ends of each step are separated from the carrying structure of the grate by means of plates, generally of the same material of the fire bar, which are approached with pressure against the side of the side bar itself. Such plates have the function of laterally containing the fuel forwarded in the region immediately above the fire bars, and of separating it from the lateral portions of the grate, which do not tolerate the direct exposition to the burning material. The lateral plates eventually join the plane made by the fire bars with the vertical surfaces of the combustion chamber, which are disposed immediately above the grate.
The grate further comprises a plurality of handling groups, each formed by the cited fire bars organized in bundles, which relatively move one with respect to the other putting forward the waste on the grate. In particular, the fire bars are divided in fixed and movable fire bars, which through slides cause a back-and- forth movement, by sliding one on another and determining the advancement of the waste in each handling group, and so in general on the grate.
The disposal of the solid urban waste, even if it is not characterized by a highest technological content, is an activity particularly sensible from' a point of view of the reliability and the guarantees of the function. The complex integrated system of the waste disposal (the accumulation, the collection, the transport, the stockpiling and the disposal) requires that the technological components employed in the last stage of the supply chain permit a continuous operation over 24 hours and minimize the risks of stopping due to damages (minor or catastrophic damages as they can be) . The operator of the disposal plant requires reliability robustness and simplicity of the component "grate" , both in the operation and in the maintenance.
Patent application MI2004A001746 describes a plant of this kind having a movable combustion grate, in which the handling group is formed by a plurality of fire bars, which alternatively move one with respect to the other by putting forward the waste on said grate, which realizes a substantially horizontal and at least partially continuous combustion plane.
The movable fire bars are bound to a movable frame, which is pushed by two pistons, one on each side. The fixed fire bars are in turn connected with a fixed frame, common to all fixed fire bars.
The relative movement between the fixed frame and the movable frame is of a simple alternate translation.
The grate is further provided with sliding elements able to determine the sliding between the two frames and elements limiting the movement between them which determine its stroke.
In the forward stroke the movable fire bar pushes the waste on the back of the fixed fire bar until causing its fall onto the subsequent movable fire bar, and at the same time it drags the waste on its own back. In the return stroke, the waste on the back of the movable fire bar finds an obstacle on the front of the fixed fire bar and, instead of moving back, it is pushed onto the back of the fixed fire bars downwards and then it is pushed forwards in the subsequent displacement, so determining the advancement of the waste in each handling group on the grate in general.
The sliding elements are substantially made by bearings or rolls upon which a pad slides substantially integrally with the moveable frame with an inclination dependent on the direction of movement which the moveable frame must communicate to the fire bars.
The movement limiting elements comprise a track integral with the carrying or fixed frame, whereas to the movable frame of the grate two wheels are in turn connected, bound to a fixed axis. The wheels are mounted with a transversal clearance with respect to the track. When the movable frame moves in different directions with respect to the required one for the correct feeding of the fire bar, the clearance between the wheels and the frame is reduced up to zero by- stopping the movement of the movable frame.
The movable frame is usually handled by hydraulic pistons with interposed crank gears and traditionally it is made by a carrying frame, made of longitudinal and transversal beams. To the upper surface of the longitudinal beams fire bar-carrying beams are fixed, on which the same fire bars rest. To the lower surface of the longitudinal beams the pads are instead fixed, which slide on the rolls of the sliding elements by giving to the mobile frame the correct direction of movement .
The fire bars are kept mutually aligned along the plane of the grate, through lateral plates which are maintained kept together on each side of them through fire bar . approaching systems.
Aim of such systems is to compensate the transversal displacements of the outer surfaces of the end fire bars, due for example to the movement of the fire bars integral with the movable frames and to the thermal expansions.
A first kind of system is called a "pusher" system, i.e. it is made of a cylindrical sliding pusher inside a seat and provided with a glass-shaped head which pushes the lateral plates against the fire bars by acting on the outer surface of the plates themselves. The pushing force is given by an elastic member, compressed between the pusher and a support integral with the fixed frame of the grate.
Such kind of technological solution has a remarkable constructive complexity and increases the transversal encumbrance of the modules of the grate. The presence of pushing assemblies impairs the approaching of two parallel modules of the grate for the realization of grates for combustion chambers with a high transversal width. Furthermore, the unavoidable accumulation of ashes and unburned substances in the region of the glass-shaped head can then cause malfunctions of the pusher for the accumulation of ashes between the pusher itself and the seat within which it flows, with the risk of seizures.
A second kind of system is called a "tie-rod" system, in which the approaching of the lateral plates to the fire bars is obtained by means of a tie-rod provided with ends so formed to engage in a seat formed in the lateral plates. The tie-rod has an elastic element (provided with a tension regulator) the traction force of which is transferred through the profiled ends to the lateral plates, which are kept forcibly together to the fire bars.
In such technological solution the elastic elements and the tension regulator are mounted under the fire bars and are so exposed to the fall of ashes from the plane of the fire bar themselves. The ashes can accumulate on the elastic elements and on the tension regulator so impairing their correct function. Both the elastic elements, and the regulator and the tie-rod must further be made of materials able to sustain both the air temperature of the pressurized volume (near to 200°C) , and the chemical aggression of the combustion ashes .
Furthermore such solution is impractical . The tension regulator is mounted at the symmetry axis of the module and requires an operator to enter inside the pressurized volume under the plane of the grate in order to regulate it, which operation can be made with safety only with the grate still and cold, with considerable burdens for plant shutdown.
Consequently the present invention solves the abovementioned drawbacks by realizing a waste disposal plant having the characteristics of the annexed claim 1.
The characteristics and advantages of the plant according to the present invention will be better clarified and evident from the following, by way of example and non limitative, description of an embodiment with reference to the annexed figures, in which :
• figure 1 is a schematic presentation of a waste disposal plant according to the known art, which provides for a three -level combustion grate ;
• figure 2 is a schematic presentation of a handling group of the grate of the plant of figure 1;
• figure 3 is a perspective view of the upper portion of the grate according to the present invention, usable in the plant of figure 1 ;
• figure 4 is a perspective view of the lower portion of the grate according to the present invention usable in the plant of figure 1; • figure 5 shows a handling assembly comprising sliding elements and movement limiting elements ;
• figure 6a shows a side view of a movable frame of the grate of figures 3 and 4;
• figure 6b shows a top view of a movable frame of the grate of figures 3 and 4.
• figure 7 shows a sectional view of the system for approaching the fire bars according to the present invention.
With reference to cited figures a typical waste disposal plant comprises a combustion chamber 2 inside which the waste disposed on a combustion grate 3 are burnt, through which an adequate quantity of combustion air is inputted.
The grate makes the lower region of the combustion chamber, above which a beam 4 is present, which has also the function of supporting lateral refractory walls 5. Preferably, the walls of the combustion chamber are completely or partially cooled, through evaporating tube bundles 6 which are protected by the refractory material itself.
The combustion grate comprises at least a handling group made by a plurality of fire bars 7, which move alternately one with respect to the other by advancing the waste on the grate .
In the example of embodiment shown in the figure the handling groups are three disposed offset one with respect to the other, in order to obtain a horizontal discontinuous placement (stepped or with jumps) .
Alternatively, still within the present invention, it is possible to obtain a slightly inclined placement (up to 15°) , without substantial modifications.
Each handling group is actuated by handling means 8 made for example by at least a hydraulic piston. Such handling means allow the alternate movement of fire bars 7 which are divided in movable fire bars 7a and fixed fire bars 7b, alternately disposed one with respect to the other, on transversal rows resting one on the other according to a longitudinal disposition with alternate steps, respectively with one fixed and one movable .
The movable fire bars are connected to movable beams 9a and are bound to a movable frame 10a, which is pushed by two pistons, one on each side. The fixed fire bars are in turn connected through fixed beams 9b with a fixed frame 10b common to all fixed fire bars.
The relative movement between the fixed frame and the movable frame is of a simple alternate translation. The relative movement of the fire bars is of an alternate translation preferably according to a direction inclined of 20° on the horizontal.
The grate is also provided with sliding elements 11 adapted to determine the sliding between the two frames and elements 12 limiting the movement between them, which determine their movement according to predefined trends.
In the forward stroke the movable fire bar pushes the waste on the back of fixed fire bar 7b until causing its fall from the subsequent movable fire bar, and at the same time it drags the waste on its own back. In the return stroke the waste on the back of the movable fire bar finds an obstacle in the front of the fixed fire bar, and instead of going back, it is pushed downwards onto the back of the fixed fire bar and therefore it is pushed forward in the subsequent stroke, by determining the advancement of the waste in each handling group and then on the grate in general.
In figures 3 and 4 a handling group of the grate is illustrated according to the present invention, comprising a carrying frame including two lateral beams 36 and two transversal cross-beams 37. Lateral beams 36 are preferably realized with a closed square or rectangular cross section and are connected to crossbeams 37 by means of a knot 38 structurally equivalen to a joint, positioned on the upper portion of lateral beams 36 themselves. Knot 38 also comprises a reference (plug or equivalent device - non represented) which permits to precisely position cross-beams 37 with respect to lateral beams 36 during the assembly of the module of the grate. Inside lateral beams 36 axes of wheel assemblies 39 are mounted, which permit the relative movement between the carrying frame and movable frame 40. To the lower portion of beams 36 the supports of bearings 41 of actuating shafts 42 are on the contrary fixed.
To the upper portion of beams 36 an upper sheet 43 is fixed. Such sheet separates the lateral plates from the outside and forms the connecting element between the carrying frame and the upper portion of the furnace (non represented) , for example comprising thermal insulating panels and respective fixing sheeting. On upper sheet 43 apertures 44 are formed which permit the access to the sealing elements of the lateral plates. Apertures 44 must be air-tightly closed through flanges 45, doors or other closures of equivalent function. To the lower portion of beams 36 a lower non-structural sheet 47 is instead fixed. Sheet 47 together with beams 36 delimits from the two sides of the module of the grate the pressurized volume which provides supply air to fire bars 7. To the front and back ends of beams 36 two flanges 48 and 49 are fixed, whose outer surfaces are made to match in order to couple two successive modules, for example through bolts with gasket or other equivalent air-tight connection. Flanges 48 and 49 are provided with upper extensions 50 and lower extensions 51, which permit to directly couple two successive modules also at upper sheets 43 and of lower sheets 47. Front flanges 48 are finally provided with a lateral extension 52 to which a connection element 53 is fixed, for the hydraulic cylinder moving actuating shaft 42. The handling of the actuating shaft takes place through a lever 54 fitted flush on shaft 42 itself.
Beams 36 as well as having a structural function incorporate the seats of all the inner and outer mechanical parts of the module of the grate, lateral sheets 43 and 47, which make the sides of the module itself and connecting flanges between successive modules .
Due to the fact that the support cross-beams of the fire bars are structural elements in the present invention, the assembly of the carrying frame of each module requires exclusively the coupling of the beams 36 specular for the two sides of the module, to cross- beams 37 by means of knot 38, provided with reference elements (non represented) for the correct coupling. On beams 36 nearly all the working operations on the machine tools are further concentrated, which are necessary in order to provide for the assembly of the module of the grate, as beams 36 are integral with the seats of all the inner and outer mechanical parts, flanges 48 and 49 coupling the successive modules and the coupling and reference surfaces to cross-beams 37 (non represented) . As beams 36 have a reduced length in order to permit the transport of the modules without resorting to exceptional transport means, they can be worked with reduced times and costs with respect to the completely assembled modules of the today produced grates. The only working operations at the machine tools which are not positioned on beams 36 are those of the coupling surfaces of knot 38 which are integral with cross-beams 37 and which must be referred to the corresponding surfaces on beams 36.
In figure 5 a guide assembly of the movement of the movable frame is shown, comprising a sliding element and a movement limiting element integrally mutually coupled. Such assembly 39 comprises essentially an axis 55, which is associated to the fixed or carrying frame, formed by an outer shaft 56, which engages in a seat 57 realized inside lateral beams 36 of the carrying frame, and an inner shaft 58 instead cantilevered under the plane of the grate. On such inner shaft one or more wheels 71 with a substantially horizontal axis are fitted flush, eventually separated by a spacer 95, on which movable 40 slides (non represented in this figure) . On the outer shaft a bushing 72 is instead fitted flush with a sliding, coupling along axis 55, to which .one or more wheels 73 with a substantially vertical axis are fixed, which encounter a movable edge of the frame, in order it to be forced to move on a seat inferiorly delimited by wheels 71 and laterally by wheels 73. In a transversal direction, bushing 72 is separated by the side of seat 57 by an elastic member 97, for example realized by a cup spring or an equivalent device. The slipping of the axis from seat 57 is prevented by two ring nuts 74 which clamp between them sequentially wheels 71, spacer 95, bushing 72, elastic element 97 and seat 57.
The deformation of the elastic element permits to regulate the transversal position of the axis in order to bring wheel 73 in contact with movable frame 40. Wheels 73 are aligned with the direction of movement of the movable frame by utilizing a reference mark (non represented) integral with the bushing to which the wheels themselves are anchored. The reference mark is blocked in a seat made in the carrying frame (non represented) . When movable frame 40 moves in different directions with respect to that provided for the correct advancement of fire bars 7, wheels 73 come in contact with movable frame 40 preventing its further deviation from the predetermined trajectory. Elastic element 97 allows bushing 72 a limited sliding on outer shaft 56 following the contact with movable frame 40, and with its deformation, continuously increases starting from zero the force which maintains movable frame 40 within the correct trajectory. Inside axis 55 lubrication ducts 98 are advantageously provided, for sending greases or oils to sliding wheels 71 and to movement limiting wheels 73.
The guide assembly according to the present invention has a remarkably simpler construction with respect to the known ones. First, it integrates in a single assembly made from few pieces both sliding elements 11 and movement limiting elements 12 of the movable frame. The entire assembly is further bound to the carrying frame through a single coupling shaft-hole between axis 55 and seat 57.
Assembly 39 is installed at the lateral beams 36, and so it is more protected from the dust present in the pressurized volume underneath the plane of fire bars 7, and it is immediately accessible for inspection. Wheels 71 are further cantilevered inside the pressurized volume underneath the plane of fire bars 7 and do not have any support structure, in which dust can accumulate . The result is a greater predictable feasibility and duration of wheels 71 themselves. The assembly in the indicated position permits to position the inlet hole of the lubricant on the surface of the axis facing the outside of the module. In this way it is not necessary to install any lubrication tubing inside the machine.
Finally, if necessary the substitution of an entire guide assembly can be done with extreme rapidity. It is in fact sufficient to remove the ring nut 74 mounted at the outside of the machine and slip the entire group from seat 57. The operation frees automatically the remaining parts, i.e. bushing 72 and elastic member 97. With the same simplicity it is possible, by repeating in reverse the above indicated operations, to install a new assembly 39. In this way the machine shutdown times for the ordinary and extraordinary maintenance of the wheels assemblies are minimized.
In figures 6a and 6b movable frame 40 according to the present invention is illustrated, comprising a front fire bar-carrying beam 114 with a carrying function and a rear fire bar-carrying beam 115 also with a carrying function. To the front fire bar- carrying beam two tracks 116 are fastened which slide, during the movement of the movable frame, on wheels 71. To the rear fire bar-carrying beam two similar tracks 117 are fastened, which also are sliding on wheels 71 of underlying assembly 39. Tracks 116 and 117 can advantageously be provided with replaceable wear plates 118.
To lower surface 119 of rear fire-carrying beam 115 vertical carrying guides 120 are fastened, also possibly provided with replaceable wear plates 121. The vertical carrying guides are fastened, at the lower ends, to tracks 116.
The alternate rectilinear movement of the movable frame is exerted on shaft 42, by means of lever 54 for example actuated by the hydraulic cylinder (see figure 4), provided with two pushing wheel assemblies 122. Wheel assemblies 122 engage in vertical guides 120 and by alternatively sliding in contact with front 123 and rear 124 sides of guide 120, due to the rotation of actuating shaft 42, cause the back and forth movement of the movable frame.
The movable frame which is the object of the present invention and is represented in figure 6 has a much more simple construction with respect to those produced nowadays, as it incorporates in the structural elements all the functional parts for its movement and for supporting the fire bars. The front and rear tracks serve in fact also as support beams of the frame itself. Furthermore, an ad hoc structure is not required for housing guides, as the latter are made in columns 120 necessary for realizing the difference in level between front fire bar-carrying beam 114 and rear fire bar-carrying beam 115. Finally it is not necessary any interfacing element with the movement limiting groups. Wheels limiting the movement 73 come in fact in contact directly with outer sides 125 of tracks 116 and 117, possibly with a wear plate (non represented) interposed.
In figure 7 an approaching systems of the fire bars is illustrated comprising a tie-rod, inserted inside a resting tube 711 of fire bars 7 integral with cross-beam 37 of the carrying frame provided at opposite ends of abutment discs resting at the outside of lateral plates 80, and provided with elastic means able to exert a traction force between the two discs which is transferred through the lateral plates, which are forcibly approached to the fire bars.
In detail, such system comprises an elastic pusher 139 provided at one end of a first abutment disc 140, resting on supporting saddle 141 of the lateral plates. The first abutment disc is connected, through threading or other equivalent system, to a spring-carrying cylinder 142. Spring-carrying cylinder 142 has the double function of relating pusher 139 to the fire bar- carrying tube and to bind abutment disc 140 to coil spring 143 which gives elasticity to the pusher. Spring 143 is connected, at the other end, with a terminal of a tie-rod attachment 144, a cylinder threaded at one end which has the function of connecting pusher 139 to a tie-rod 145.
At the opposite end of the tie-rod at which spring 143 is connected, a rigid pusher 146 is mounted, comprising a second abutment disc 147 associated to a reference cylinder 148. Also in this case second abutment disc 147 rests on support saddle 141 of the lateral plates. Cylinder 148 has a through hole 149 which is traversed by the threaded end of tie-rod 145. At the end of tie-rod 145 and in contact with the outer end of abutment disc 147, a nut 150 is mounted.
At the moment of the assembly the group formed by tie-rod 145 and elastic pusher 139 is inserted, from the side of the tie-rod, into the fire bar-carrying tube until bringing abutment disc 140 in contact with the outer end of support saddle 141 of lateral plates 80. At the opposed end rigid pusher 146 is inserted in turn inside the fire bar-carrying tube, by sliding the end of tie-rod 145 inside through hole 149 until bringing abutment disc 147 in contact with support saddle 141 of lateral plates 80. By installing and turning the nut 150 first of all tie-rod 145 is stretched and subsequently spring 143 is extended. The equilibrium of the tie-rod makes that the elastic force of spring 143 generates two identical forces between abutment discs 147 and 140 and lateral plates 80. Due to the fact that plates 80 are slideably mounted on the fire bar-carrying tube, such forces are the same as the contact forces between lateral plates 80 and end fire bars 7. This means that by regulating through nut 150 the extension of spring 143, it is possible to regulate the approaching force between plates 80 and end fire bars 7.
The approaching system of the fire bars according to the present invention has following advantages in comparison with those of normal production. First of all, all the components are mounted inside the fixed fire bar-carrying tube. Therefore they are completely protected both from the dust coming from the plane of the fire bars and from the hot air of the pressurized volume underneath the fire bars. They have therefore a greater feasibility and lesser production costs. The regulation of the contact pressure between plates 80 and fire bars 7 is done by uniquely acting on nut 150, from a single side of the module of the grate through apertures 44. This means that the regulation is done from the outside of the machine and it does not require an access to the pressurized volume under the grate. Therefore it can be. done in a safety way by stopping and depressurizing just one module without stopping the entire grate, with a dramatic reduction of the plant shutdown times.
Furthermore the system according to the present invention permits to exactly obtain the same approaching force between plates 80 and end fire bars 7 through the only regulation of the position of nut 150. In this way dissymmetries of the approaching force are avoided, which can amplify the sideslip of movable frame 40.

Claims

1. Waste disposal plant comprising a combustion chamber (2) inside which waste laid on a combustion grate (3) are burnt, which permits the entrance of an adequate quantity of combustion air in the chamber through it, said combustion grate comprising at least a handling group formed by a plurality of fire bars or plates (7) , which move alternatively one with respect to the other by advancing the waste on said grate and are divided in movable fire bars (7a) and fixed fire bars (7b) , alternately disposed one with respect to the other, on transversal rows resting one upon the other according to a longitudinal placement with alternate steps, such fixed fire bars being bound to a fixed frame and such movable fire bars being bound to a movable frame, which moves through handling means (8) with respect to the fixed one,
such fire bars (7) being kept mutually aligned along the plane of the grate, through lateral plates (80) which are kept approached on both sides of them through a fire bar approaching system,
characterized in that such fire bar approaching system comprises at least a tie-rod, inserted inside a support tube (711) of the fire bars realized on the cross-beams (37) of the carrying frame, provided at opposite ends of abutment discs (140, 147) resting at the outside of such plates, and provided with elastic means adapted to exert a traction force between the two discs which is transferred to the lateral plates, which are forcibly approached to the fire bars.
2. Plant according to claim 1, in which such system comprises an elastic pusher (139) provided at one end of a first abutment disc 140, resting on the support saddle 141 of the lateral plates.
3. Plant according to claim 1, in which such elastic means comprise a coil spring (143) .
4. Plant according to preceding claims, in which the first abutment disc is connected to a spring- carrying cylinder (142) , which has the double function of relating the pusher (139) to the fire bar-carrying tube and of binding the abutment disc (140) to an end of such coil spring (143) .
5. Plant according to claim 4, in which the spring (143) is connected, at the other end, with an attachment terminal (144) of the tie-rod, which connects the pusher (139) with a tie-rod (145) .
6. Plant according to claim 5, in which at the opposite end of the tie-rod to which the spring (143) is connected a rigid pusher (146) is mounted comprising a second abutment disc (147) associated to a reference cylinder (148) resting on the support saddle (141) of the lateral plates (80) .
7. Plant according to claim 6, in which the cylinder (148) has a through hole (149) traversed by the threaded end of the tie-rod (145) .
8. Plant according to claim 7, in which at the end of the tie-rod (145) and in contact with the outer end of the second abutment disc (147) , a nut (150) is mounted .
PCT/EP2010/007027 2009-11-26 2010-11-19 A waste disposal plant with fire bar approaching system. WO2011063912A1 (en)

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IT000918A ITTO20090918A1 (en) 2009-11-26 2009-11-26 WASTE DISPOSAL PLANT PROVIDED WITH A BARROTTI COMBINATION SYSTEM.
ITTO2009A000918 2009-11-26

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EP2584264A1 (en) * 2011-10-21 2013-04-24 Martin GmbH für Umwelt- und Energietechnik Grate stage module for a push combustion grate

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US3987738A (en) * 1974-05-27 1976-10-26 Polysius Ag Seal for a traveling grate
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US5377663A (en) * 1993-06-07 1995-01-03 Wheelabrator Environmental Systems, Inc. Grate combustion system
EP0650017A1 (en) * 1993-10-21 1995-04-26 ABB Management AG Grate for a furnace
US20040231573A1 (en) * 2001-08-01 2004-11-25 Martin Gmbh Fur Umwelt- Und Energietechnik Grate furnace
EP1840463A1 (en) * 2006-03-27 2007-10-03 Babcock & Wilcox Voelund ApS Combustion grate spanning system

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Publication number Priority date Publication date Assignee Title
GB298286A (en) * 1927-07-14 1928-10-11 Alfred William Bennis Improvements in or connected with furnace grates
US3987738A (en) * 1974-05-27 1976-10-26 Polysius Ag Seal for a traveling grate
EP0165432A1 (en) * 1984-05-21 1985-12-27 KOCH, Theodor Furnace, especially for the combustion of refuse, coal, wood and industrial waste
US5377663A (en) * 1993-06-07 1995-01-03 Wheelabrator Environmental Systems, Inc. Grate combustion system
EP0650017A1 (en) * 1993-10-21 1995-04-26 ABB Management AG Grate for a furnace
US20040231573A1 (en) * 2001-08-01 2004-11-25 Martin Gmbh Fur Umwelt- Und Energietechnik Grate furnace
EP1840463A1 (en) * 2006-03-27 2007-10-03 Babcock & Wilcox Voelund ApS Combustion grate spanning system

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2584264A1 (en) * 2011-10-21 2013-04-24 Martin GmbH für Umwelt- und Energietechnik Grate stage module for a push combustion grate
WO2013056687A1 (en) * 2011-10-21 2013-04-25 Martin GmbH für Umwelt- und Energietechnik Grate step module for a thrust combustion grate
JP2014532161A (en) * 2011-10-21 2014-12-04 マルティン ゲーエムベーハー フュー ウンヴェルト− ウント エネルギーテクニーク Grating step module for sliding grate
US9845951B2 (en) 2011-10-21 2017-12-19 Martin Gmbh Fuer Umwelt-Und Energietechnik Grate step module for a thrust combustion grate

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