EP3885651B1 - Rotary de-ashing grate system for furnace of a combustion or gasification installation - Google Patents
Rotary de-ashing grate system for furnace of a combustion or gasification installation Download PDFInfo
- Publication number
- EP3885651B1 EP3885651B1 EP21163539.6A EP21163539A EP3885651B1 EP 3885651 B1 EP3885651 B1 EP 3885651B1 EP 21163539 A EP21163539 A EP 21163539A EP 3885651 B1 EP3885651 B1 EP 3885651B1
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- EP
- European Patent Office
- Prior art keywords
- plates
- plate
- fuel
- lower plate
- air
- Prior art date
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Links
- 238000002485 combustion reaction Methods 0.000 title claims description 21
- 238000009434 installation Methods 0.000 title claims description 16
- 238000002309 gasification Methods 0.000 title claims description 12
- 238000004380 ashing Methods 0.000 title claims 2
- 239000000446 fuel Substances 0.000 claims description 38
- 238000002347 injection Methods 0.000 claims description 12
- 239000007924 injection Substances 0.000 claims description 12
- 239000004449 solid propellant Substances 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 239000002028 Biomass Substances 0.000 claims description 4
- 230000005484 gravity Effects 0.000 claims description 4
- 239000002956 ash Substances 0.000 description 38
- 235000002918 Fraxinus excelsior Nutrition 0.000 description 23
- 238000010586 diagram Methods 0.000 description 6
- 230000033001 locomotion Effects 0.000 description 6
- 238000012423 maintenance Methods 0.000 description 6
- 239000000428 dust Substances 0.000 description 5
- 235000021183 entrée Nutrition 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000009825 accumulation Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000003546 flue gas Substances 0.000 description 2
- 239000003517 fume Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000010882 bottom ash Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000007726 management method Methods 0.000 description 1
- 230000009347 mechanical transmission Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23H—GRATES; CLEANING OR RAKING GRATES
- F23H7/00—Inclined or stepped grates
- F23H7/06—Inclined or stepped grates with movable bars disposed parallel to direction of fuel feeding
- F23H7/08—Inclined or stepped grates with movable bars disposed parallel to direction of fuel feeding reciprocating along their axes
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/02—Fixed-bed gasification of lump fuel
- C10J3/20—Apparatus; Plants
- C10J3/34—Grates; Mechanical ash-removing devices
- C10J3/40—Movable grates
- C10J3/42—Rotary grates
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23H—GRATES; CLEANING OR RAKING GRATES
- F23H9/00—Revolving-grates; Rocking or shaking grates
- F23H9/02—Revolving cylindrical grates
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K3/00—Feeding or distributing of lump or pulverulent fuel to combustion apparatus
- F23K3/10—Under-feed arrangements
- F23K3/14—Under-feed arrangements feeding by screw
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23H—GRATES; CLEANING OR RAKING GRATES
- F23H2700/00—Grates characterised by special features or applications
- F23H2700/005—Rotary grates with vertical axis
Definitions
- the present invention relates to an ash removal grate system for the hearth of a combustion or gasification installation supplied with solid fuel, said grate system comprising a lower circular plate of diameter D1 and surface S1 mounted to rotate 360° along an axis vertical rotation A, and an installation comprising such an ash grate system.
- Combustion or gasification installations include a hearth inside which a fixed bed of a solid fuel, for example biomass, is burned to provide heat. They also generate residues, such as ashes, char or various unburnt materials, which must be continuously evacuated from the hearth, to avoid operational stoppages.
- a solid fuel for example biomass
- residues such as ashes, char or various unburnt materials
- the grid systems are advantageously designed to respond to different problems in combustion or gasification installations including - the reception of the fuel injection system in the hearth; - setting the fuel in motion to advance the fuel towards the ash evacuation system, the drive system must be adapted to the heat and the presence of any dust, and be protected from it; - controlling the speed of advance of the fuel bed to avoid the formation of unburnt materials (residence time too short) or bottom ash (residence time too long).
- Some systems include vibrating screens, others include rotating screens, still others include tilting screens, and still others include stepped screens.
- the EP 3 338 024 A1 shows the features specified in the preamble of claim 1.
- a problem that the invention proposes to solve is to produce an ash grate system for the hearth of a combustion or gasification installation supplied with solid fuel, which overcomes the aforementioned problems of the state of technology.
- This system also responds to the variability of the fuel composition, which requires varying the residence times of the ashes on the grid depending on the nature of the ashes evacuated. If the ashes coming out of the grids are clumped or partially melted: the residence time is too long. It is necessary to increase the speed of certain platforms. If the ashes contain unburned matter, the residence time must be extended.
- the solution of the invention to this problem posed has as its first object an ash removal grate system for the hearth of a combustion or gasification installation supplied with solid fuel, said grate system comprising a lower circular plate of diameter D1 and surface S1 mounted to rotate 360° along a vertical axis of rotation A, and further comprising at least one upper plate, superimposed on said lower plate, and mounted to rotate 360° along the vertical axis of rotation A, said at least one plate upper having a surface S2 less than the surface S1 of the lower plate and a maximum dimension at most equal to the diameter D1 of this lower plate, said plates being mobile, the center of gravity of said plates (being on the axis of rotation A, the or the upper plates having a shape different from the circular shape and a largest dimension substantially equal to the smallest dimension of the plate on which they are superimposed, the lower and upper plates not rotating at the same speed.
- Its second object is a combustion or gasification installation supplied with solid fuel comprising a grid system as defined above.
- the fuel is a fuel derived from biomass.
- a gasification or combustion installation according to the invention is intended to burn or gasify a solid fuel, in particular from biomass, with a view to producing heat.
- the fuel is therefore by nature heterogeneous. Its composition varies. In particular, it is more or less dry.
- Such an installation according to the invention comprises a hearth which is provided around a vertical axis of symmetry.
- This hearth is delimited by a side wall, for example cylindrical.
- Fuel is admitted into the hearth through a fuel inlet corresponding to a fuel supply channel.
- This supply channel is preferably formed of a vertical cylindrical tube centered on a set of superimposed rotating plates forming a grid.
- solid fuel is admitted into the firebox, vertically, from bottom to top, through the supply channel, to the fuel inlet, a mound of solid fuel forms on the grate .
- the grid system 1 comprises a lower plate P1 and one or more upper plates.
- the number of upper plates is advantageously two or three.
- system 1 includes three upper plates P2, P3 and P4.
- the upper plate(s) P2 to P4 are positioned on the lower plate P1, stacked on this plate P1. All plates P1 to P4 are rotating plates, mounted to rotate around a vertical axis A at an angle of 360°.
- the lower plate P1 is mounted on a fixed circular base 2.
- the lower plate P1 is circular with a diameter D. It is the largest of the plates.
- the surface of the upper plates S2, S3, S4 is less than S1. These surfaces S2, S3 and S4 are decreasing: S2 > S3 > S4.
- the plates P2 to P4 are in an elliptical shape.
- the plates P2 to P4 are triangular.
- they are star-shaped.
- other conformations of the upper plates are possible and in particular, an ellipsoidal conformation.
- the upper plates P2 to P4 have at least one larger dimension and smaller dimensions.
- the largest dimension of the upper plate P2 positioned immediately above the lower plate P1 is equal to or approximately equal to the diameter D of the lower plate P1.
- the surface S2 of the upper plate P2 is less than that S1 of the lower plate.
- FIGS. 3A and 3B have a superposition of two upper plates, for example the plates P2 and P3, the plate P3 being superimposed on the plate P2.
- the plates P2 and P3 are in an ellipse. They therefore each have a larger dimension, namely the major axis of the ellipse, and a smaller dimension: the minor axis of this ellipse.
- the major axis of the ellipse formed by the plate P3 is approximately equal to or equal to the minor axis of the ellipse formed by the plate P2.
- the plates P2 and P3 are triangular and the triangles they define are equilateral.
- the largest dimension of the triangle forming P3, namely the side of this triangle, is approximately equal to the smallest dimension defined by the triangle forming P2.
- the plate P3 fits into the plate P2 with a greater dimension, for P3 equal or approximately equal to the smallest dimension of P2.
- the aforementioned characteristics of the P2 and P3 plates apply in the same way to the P3 and P4 plates and so on.
- the shape of the upper plate(s) can be diverse as long as it combines the following characteristics.
- the center of gravity of the plates is on the axis of rotation. This makes it possible to avoid having mechanical forces distributed in a non-symmetrical manner on the supports of the plate. This improves the lifespan of the system.
- this allows the surface of the lower plate to be alternately covered and uncovered during rotation. This makes it possible to “scrape” the surface of a lower plate by an upper plate and thus to advance the fuel towards the periphery of the reactor.
- the thickness of the plates P1, P2, P3, P4 increases in the stacking of said plates in the grid system.
- the lower plate P1 has a thickness of 100 mm
- that of the upper plate P2 which is immediately above it has a thickness of 80 mm
- that of the plate P3 is 60 mm
- that of the plate P4 is 60 mm. This allows an equivalent quantity of fuel to be generated for each tray.
- Plates P1 to P4 are made so that they can be dismantled in portions to facilitate maintenance and installation operations. This also allows to optimize maintenance costs by replacing only the portion of a damaged tray and not the entire tray.
- the plates P1 to P4 are perforated so that the primary air can pass through said plates.
- the trays have, for example, holes or slots.
- they are provided with substantially radial slots, namely starting from the periphery of the plates and going towards the center of these.
- Some F1 slots are not complete and do not extend to the perimeter of the decks.
- Other F2 slots are complete and extend to the periphery of the plates. They allow the trays to expand without creating distortion.
- the slots F1, F2 advantageously extend, on the side of the center of the plates, by openings 0 wider than the slots F1, F2. These openings 0 allow air to pass through and prevent the formation of microcracks at the level of the slots F1, F2.
- the slots F1, F2 may not be strictly positioned radially on the plates. In other words, they may not pass through the center of these. They are then slightly inclined so that, for the same number of slots, the surface area allowing the passage of air is greater.
- the slot surfaces are calculated so as to optimize the air flow rates and thereby the combustion/gasification profile of the solid fuel, at the level of each plate.
- the section of the slots is calculated so as to create a determined pressure loss of the air passing through them, ensuring a homogeneous flow rate per slot, independent of the local quantity of fuel located above, and in particular avoiding uncontrolled air leaks in the event of a lack of fuel above the slots.
- a circular fuel inlet 3 is arranged in the center of the plates P1 to P4 of the grid system 1. All the plates P1 to P4 can rotate around the axis of rotation A, identical to the axis of revolution of the fuel inlet 3. The rotational movement of a given plate creates relative movement with respect to the plates above and below and the elliptical, or other, shape of the upper plates P2 to P4, which allows you to sweep the surface of the trays on which they are superimposed and to advance the fuel towards the outside.
- the plates P1 to P4 do not rotate at the same time and at the same speed so that there is relative movement between the plates. In other words, each of the plates P1 to P4 rotates at a different speed. Furthermore, each of the plates can rotate at a variable speed to adjust the residence time of the ashes which must be variable depending on the nature of the ashes.
- the rotation speeds of the plates are adjustable independently of each other. They are independently controlled. They vary over time independently.
- the plates rotate at variable speed depending on the nature of the fuel used.
- the fact that the plates can vary their speed makes it possible to vary the residence time in the gasifier, depending on the nature of the fuel. and ashes.
- a residence time that is too long can cause the ashes to melt and therefore block or even destroy the grid.
- a residence rate that is too short leads to the presence of unburnt material at the bottom of the grid, which reduces the efficiency of the installation and increases the risk of blockage.
- waste by nature of variable composition, only a grid with variable rotation speed can work.
- the grid according to the invention is the only one that can adapt to a variable waste composition over time.
- a large slot 4 is fitted around the perimeter of the grid to evacuate the ashes.
- the ashes are thus continuously evacuated from the hearth through this slot 4.
- the grid system according to the invention is also designed not to create any unwanted ash accumulation points.
- the function of the trays is to spread the fuel and bring the ashes outwards, namely towards the wide slot 4, in order to evacuate them.
- the fact that all the trays are mobile has two advantages compared to systems with fixed trays. First, a single moving plate allows the fuel to be swept from the moving plate plus the fuel on the lower plate. There is therefore less need to run the engines for the same service. We save energy. In addition, the system is less sensitive to possible blockages. If a tray becomes blocked for any reason, the trays above and below can be used to continue operating the grid, and therefore the power generation unit, while planning and carry out a maintenance operation at the most suitable time. Grid system availability and repair flexibility are higher.
- the evacuation of ashes present in the hearth is done through the wide slot or groove 4 positioned around the entire perimeter of the grid system.
- the ashes fall through this slot onto a conveyor system not shown in the figures, which allows the ashes to be brought into a storage space.
- This wide slot 4 is made so that the largest pieces that can be injected into the hearth can be evacuated.
- the majority of the ashes are pushed by the rotating plates towards the outside of the grid and therefore towards this slot 4.
- small ashes can also be brought under the plates. Ultimately, these small ashes are likely to block or disrupt the flow of primary air. To avoid this phenomenon, scraping devices are installed under the trays. These devices are not shown in the figures.
- One or more openings can also be placed at a point around the edge of the tray(s) so that the ashes fall into the throat.
- the section of the opening is precisely calculated so as not to have a preferential air leak, which could affect the main air flow passing through the slots.
- An injection system makes it possible to supply the fireplace with primary air from two independent air inlets in the system. These entries are referenced 5 and 6 in figures 6A And 6B .
- These inlets 5 and 6 are primary air inlets of two independent air circuits: the cooling air circuit C1 and the main circuit C2.
- the cooling air circuit C1 allows atmospheric air to pass through the system for rotating the system and to cool it to protect it from damage due to a rise in temperature.
- the primary air admitted into inlet 5 thus makes it possible to cool the mechanical movement transmission system to preserve its integrity. This air also makes it possible to avoid any intrusion of ash dust into the mechanical part of the system according to the invention. Part of this primary air is injected through this inlet 5 and emerges at each plate, via a set of dedicated lights, arranged in each coaxial tube.
- the injected air then joins the circuit under the plates of the grid system, before entering the solid fuel bed.
- the second main C2 circuit allows most of the primary air flow to be injected into the hearth through the grille.
- This circuit is independent of the cooling circuit and is not in contact with sensitive mechanical parts. This makes it possible to inject preheated air or directly to recirculate fumes which can reach 200°C and be loaded with dust.
- the air admitted into inlet 6 therefore supplies the hearth through the grille. Its flow is controlled.
- the circuit corresponding to this input is never in contact with elements sensitive to temperature or dust. This makes it possible, if necessary, to inject other gases such as recirculated flue gases which still contain fly ash and can reach 200°C.
- a third air circuit is composed of an air ring denoted CA in Fig. 1 injection located on the periphery of the bottom grid (the lower plate). It allows you to finalize the combustion of any unburnt food on the bottom grill. Smoke recirculation optimizes the combustion of very dry and volatile fuels and reduces the production of atmospheric pollutants such as NOx.
- quick-opening hatches 7 are advantageously arranged on the primary air circuit under the grid system. They allow the air intake circuit pipes to be quickly evacuated in the event of ash accumulation.
- the rotational movements of the plates P1 to P4 are communicated to the plates by means of coaxial vertical tubes.
- the coaxial vertical tubes are attached to the plates.
- the axis of the tubes coincides with the axis A.
- a coaxial tube rotates a plate to which it is assembled.
- Tube T1 is assembled to plate P1
- tube T2 is assembled to plate P2, and so on until tube T4 assembled to plate P4.
- the coaxial tubes T1 to T4 are cylindrical of revolution and have different diameters as well as different heights. The diameter of the coaxial tubes increases from the smallest plate P4 to the largest P1.
- the coaxial tube T4 which is assembled in the lower part of the plate P4, has a diameter smaller than the diameter of the coaxial tube T3 and so on.
- the coaxial tubes T1 to T4 are arranged around the central fuel injection tube 8. The smaller the diameter of a tube, the greater the height of the tube is large. So, tube T4 is the tallest and tube T1 is the smallest.
- tubes T1 to T4 are equipped, at their base, with a drive system.
- This drive system is formed for example of toothed wheels 9 driven by a pinion 10, namely a toothed wheel of smaller diameter, fixed to a motor axis 11 parallel to the coaxial tube, actuated by a geared motor group 12. It may however be any other suitable drive system, for example, a similar system comprising an assembly provided with a toothed wheel, a chain, and a motor or piston.
- having trays with a center of gravity on the axis of rotation allows the use of larger and heavier grids.
- this characteristic makes it possible to avoid wearing out the mechanical transmission system prematurely while unbalanced plates create an overhang that is damaging to the entire mechanical performance over time.
- the fact of having all the moving plates makes it possible to run the engines for less time for the same effect of advancing the fuel cell. This results in energy savings during operation and limits wear on mechanical parts.
- Another advantage of this solution is that the grid is more resilient in the event of a blockage. It can continue to operate with a blocked plate, the trays located above and below the blocked tray operating independently.
- Grid availability is thus improved and maintenance can be planned at the most convenient time.
- the trays can all be dismantled in portions. This makes maintenance operations easier and can be carried out with a minimum of tools, even for a large diameter grid.
- the complete slots in the trays and the use of refractory steel allow the trays to hold the temperature well and to have thinner trays. This provides an economic gain in manufacturing but it also facilitates maintenance with trays that are lighter to handle.
- the variable height of the trays makes it possible to overcome the paradox of a circular grid fed from the center. Indeed, on this type of grid there is a lot of material in the center (unburned fuel) but little surface area whereas on the outside of the grid there is much less material (ash) but a larger grid surface area. . The variable height of the plates makes it possible to compensate for this phenomenon and better control combustion.
- the double primary air circuit makes it possible to inject recirculated fumes or air preheated to a high temperature, for example of the order of 200°C, while ensuring that the mechanical system is cooled and not polluted by flying dust. Flue gas recirculation or air preheating are an advantage for reducing NOx production and for low calorific value fuels. Then, the injection system primary air ensures the distribution of air under the grille and therefore better controls combustion. It also allows the grid to be cooled with primary air.
- the drive system based on concentric tubes allows great flexibility in the choice of the drive mechanism used. It can be adapted according to the characteristics of the grid and the fuel.
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Description
La présente invention concerne un système de grille de décendrage pour foyer d'une installation de combustion ou de gazéification alimentée en combustible solide, ledit système de grille comprenant un plateau circulaire inférieur de diamètre D1 et de surface S1 monté rotatif à 360° selon un axe de rotation vertical A, et une installation comprenant un tel système de grille de décendrage.The present invention relates to an ash removal grate system for the hearth of a combustion or gasification installation supplied with solid fuel, said grate system comprising a lower circular plate of diameter D1 and surface S1 mounted to rotate 360° along an axis vertical rotation A, and an installation comprising such an ash grate system.
Les installations de combustion ou de gazéification comprennent un foyer à l'intérieur duquel un lit fixe d'un combustible solide, par exemple de la biomasse, est brûlé pour fournir de la chaleur. Elles génèrent également des résidus, tels que des cendres, du char ou divers imbrûlés, qui doivent être évacués en continu hors du foyer, pour éviter des arrêts de fonctionnement. A cet effet, les installations de combustion ou de gazéification selon l'art antérieur sont équipées de systèmes de grille de décendrage.Combustion or gasification installations include a hearth inside which a fixed bed of a solid fuel, for example biomass, is burned to provide heat. They also generate residues, such as ashes, char or various unburnt materials, which must be continuously evacuated from the hearth, to avoid operational stoppages. For this purpose, the combustion or gasification installations according to the prior art are equipped with ash removal grid systems.
Les systèmes de grille sont avantageusement prévus pour répondre à différentes problématiques dans les installations de combustion ou de gazéification parmi lesquelles - l'accueil du système d'injection de combustible dans le foyer ; - la mise en mouvement du combustible pour faire avancer le combustible vers le système d'évacuation des cendres, le système d'entrainement devant être adapté à la chaleur et à la présence d'éventuelles poussières, et en être protégé ; - la maitrise de la vitesse d'avance du lit de combustible pour éviter la formation d'imbrulés (temps de séjour trop court) ou de mâchefers (temps de séjour trop long). Cela doit aussi permettre de faire fonctionner le foyer à différents niveaux de charge ; - la possibilité d'injecter l'air primaire au travers de la grille ; - la maitrise de la distribution de l'air primaire sur différentes portions de la grille pour contrôler la combustion ; - l'évacuation des cendres du foyer au fur et à mesure de la combustion, les plus gros morceaux ne devant pas bloquer cette évacuation ; - la grille doit tenir à des niveaux de température élevées sans déformation ; et - le contrôle de la température et de la vitesse d'évacuation des cendres pour éviter la formation de mâchefer.The grid systems are advantageously designed to respond to different problems in combustion or gasification installations including - the reception of the fuel injection system in the hearth; - setting the fuel in motion to advance the fuel towards the ash evacuation system, the drive system must be adapted to the heat and the presence of any dust, and be protected from it; - controlling the speed of advance of the fuel bed to avoid the formation of unburnt materials (residence time too short) or bottom ash (residence time too long). This should also make it possible to operate the fireplace at different load levels; - the possibility of injecting primary air through the grille; - control of the distribution of primary air over different portions of the grid to control combustion; - the evacuation of ashes from the hearth as combustion progresses, the largest pieces not having to block this evacuation; - the grid must hold up to high temperature levels without deformation; and - controlling the temperature and speed of ash evacuation to avoid the formation of clinker.
De nombreux système de grille de décendrage ont été développés pour répondre à certaines ou à l'ensemble des problématiques exposées ci-dessus. Certains systèmes comprennent des grilles vibrantes, d'autres comprennent des grilles rotatives, d'autres encore comprennent des grilles basculantes, et d'autres enfin comprennent des grilles à gradins.Many ash grate systems have been developed to respond to some or all of the problems set out above. Some systems include vibrating screens, others include rotating screens, still others include tilting screens, and still others include stepped screens.
Par exemple, le
Compte tenu de ce qui précède, un problème que se propose de résoudre l'invention est de réaliser un système de grille de décendrage pour foyer d'une installation de combustion ou de gazéification alimentée en combustible solide, qui pallie les problématiques précitées de l'état de la technique. Ce système répond aussi à la variabilité de la composition du combustible, qui nécessite de faire varier les temps de séjour des cendres sur la grille en fonction de la nature des cendres évacuées. Si les cendres qui sortent des grilles sont agglomérées ou partiellement fondues : le temps de séjour est trop long. Il faut augmenter la vitesse de certains plateaux. Si les cendres contiennent des imbrûlés, il faut rallonger le temps de séjour.Taking into account the above, a problem that the invention proposes to solve is to produce an ash grate system for the hearth of a combustion or gasification installation supplied with solid fuel, which overcomes the aforementioned problems of the state of technology. This system also responds to the variability of the fuel composition, which requires varying the residence times of the ashes on the grid depending on the nature of the ashes evacuated. If the ashes coming out of the grids are clumped or partially melted: the residence time is too long. It is necessary to increase the speed of certain platforms. If the ashes contain unburned matter, the residence time must be extended.
La solution de l'invention à ce problème posé a pour premier objet un système de grille de décendrage pour foyer d'une installation de combustion ou de gazéification alimentée en combustible solide, ledit système de grille comprenant un plateau circulaire inférieur de diamètre D1 et de surface S1 monté rotatif à 360° selon un axe de rotation vertical A, et comprenant en outre au moins un plateau supérieur, superposé audit plateau inférieur, et monté rotatif à 360° selon l'axe de rotation vertical A, ledit au moins un plateau supérieur ayant une surface S2 inférieure à la surface S1 du plateau inférieur et une dimension maximale au plus égale au diamètre D1 de ce plateau inférieur, lesdits plateaux étant mobiles, le centre de gravité desdits plateaux (étant sur l'axe de rotation A, le ou les plateaux supérieurs ayant une forme différente de la forme circulaire et une plus grande dimension sensiblement égale à la plus petite dimension du plateau sur lequel ils sont superposés, les plateaux inférieur et supérieur ne tournant pas à la même vitesse.The solution of the invention to this problem posed has as its first object an ash removal grate system for the hearth of a combustion or gasification installation supplied with solid fuel, said grate system comprising a lower circular plate of diameter D1 and surface S1 mounted to rotate 360° along a vertical axis of rotation A, and further comprising at least one upper plate, superimposed on said lower plate, and mounted to rotate 360° along the vertical axis of rotation A, said at least one plate upper having a surface S2 less than the surface S1 of the lower plate and a maximum dimension at most equal to the diameter D1 of this lower plate, said plates being mobile, the center of gravity of said plates (being on the axis of rotation A, the or the upper plates having a shape different from the circular shape and a largest dimension substantially equal to the smallest dimension of the plate on which they are superimposed, the lower and upper plates not rotating at the same speed.
De manière avantageuse, - chaque plateau est mobile en rotation selon une vitesse de rotation Vi, cette vitesse de rotation étant variable dans le temps en fonction de la composition du combustible ; - les vitesses de rotation des plateaux supérieurs sont différentes et sont variables de manière individuelle ; - le système comprend une pluralité de plateaux supérieurs superposés les uns aux autres, l'ensemble des plateaux supérieurs étant superposés au plateau inférieur, la surface S2 du plateau immédiatement supérieur au plateau inférieur s'inscrit dans celle S1 dudit plateau inférieur, et la surface S3, et éventuellement la surface S4, du ou des plateaux supérieurs positionnés au-dessus du plateau immédiatement supérieur au plateau inférieur sont décroissantes en fonction de leur position dans la superposition des plateaux ; - les plateaux supérieurs ne se présentent pas sous une forme circulaire ; - le ou les plateaux supérieurs ont une forme elliptique ; - les plateaux sont ajourés ;
- les plateaux présentent des fentes et/ou des ouvertures ;
- une entrée circulaire de combustible est aménagée au centre de l'empilement des plateaux, le centre de ladite entrée circulaire étant positionné sensiblement sur l'axe A et en ce qu'un tube relié à cette entrée permet l'admission du combustible, verticalement, au travers des plateaux superposés ; - le système comporte deux entrées d'air primaire de deux circuits d'air indépendants, un circuit d'air principal et un circuit d'air de refroidissement ; le système comporte une couronne d'air d'injection autour du plateau inférieur, ladite couronne d'air injectant de l'air radialement sur le plateau inférieur, pour éliminer la présence d'imbrûlés dans les cendres par combustion ; - des tubes cylindriques coaxiaux sont fixés aux plateaux, un tube cylindrique étant fixé à chaque plateau, et en ce que les plateaux sont entraînés en rotation au moyen de ces tubes, qui sont eux-mêmes entraînés en rotation de manière indépendante par des moyens d'entraînement.
- the trays have slots and/or openings;
- a circular fuel inlet is arranged in the center of the stack of trays, the center of said circular inlet being positioned substantially on axis A and in that a tube connected to this inlet allows the admission of fuel, vertically, through the superimposed trays; - the system has two primary air inlets of two independent air circuits, a main air circuit and a cooling air circuit; the system comprises an injection air ring around the lower plate, said air ring injecting air radially onto the lower plate, to eliminate the presence of unburnt material in the ashes by combustion; - coaxial cylindrical tubes are fixed to the plates, a cylindrical tube being fixed to each plate, and in that the plates are rotated by means of these tubes, which are themselves driven to rotate independently by drive means.
Elle a pour second objet, une installation de combustion ou de gazéification alimentée en combustible solide comprenant un système de grille tel que défini ci-dessus.Its second object is a combustion or gasification installation supplied with solid fuel comprising a grid system as defined above.
De manière avantageuse, le combustible est un combustible issu de la biomasse.Advantageously, the fuel is a fuel derived from biomass.
L'invention sera mieux comprise à la lecture de la description non limitative qui suit, rédigée au regard des dessins annexés, dans lesquels :
- la
figure 1 montre, en perspective, un mode de réalisation du système de grille selon l'invention ; - la
figure 2A est un schéma illustratif d'un premier mode de réalisation d'un plateau supérieur d'un système de grille selon l'invention ; - la
figure 2B est un schéma illustratif d'un deuxième mode de réalisation d'un plateau supérieur d'un système de grille selon l'invention ; - la
figure 2C est un schéma illustratif d'un troisième mode de réalisation d'un plateau supérieur d'un système de grille selon l'invention ; - la
figure 3A est un schéma qui illustre une superposition de deux plateaux supérieurs selon un premier mode de réalisation d'un système de grille selon l'invention ; - la
figure 3B est un schéma qui illustre une superposition de deux plateaux supérieurs selon un deuxième mode de réalisation d'un système de grille selon l'invention ; - la
figure 4 est une vue partielle, en perspective, d'un ensemble de plateaux superposés d'un système de grille selon l'invention ; - la
figure 5 est une vue de dessus, d'un plateau d'un système de grille selon l'invention, montrant les fentes ménagées à l'intérieur ce plateau ; - la
figure 6A montre, en perspective, la partie inférieure d'un système de grille selon l'invention, et les trappes à ouverture rapide que comporte ce système, pour le nettoyage des circuits d'injections d'air primaire ; - la
figure 6B montre, en coupe, un système de grille selon l'invention, ainsi que les circuits principal et de refroidissement de ce circuit ; - est un schéma illustrant le positionnement des tubes de support des plateaux du système de grille selon l'invention ; et
- la
figure 8 est une vue en perspective et en coupe d'un système de grille selon l'invention, qui montre en particulier le système d'entrainement des plateaux de ce système.
- there
figure 1 shows, in perspective, an embodiment of the grid system according to the invention; - there
Figure 2A is an illustrative diagram of a first embodiment of an upper plate of a grid system according to the invention; - there
Figure 2B is an illustrative diagram of a second embodiment of an upper plate of a grid system according to the invention; - there
Figure 2C is an illustrative diagram of a third embodiment of an upper plate of a grid system according to the invention; - there
Figure 3A is a diagram which illustrates a superposition of two upper plates according to a first embodiment of a grid system according to the invention; - there
Figure 3B is a diagram which illustrates a superposition of two upper plates according to a second embodiment of a grid system according to the invention; - there
figure 4 is a partial perspective view of a set of superimposed plates of a grid system according to the invention; - there
figure 5 is a top view of a plate of a grid system according to the invention, showing the slots provided inside this plate; - there
Figure 6A shows, in perspective, the lower part of a grid system according to the invention, and the quick-opening hatches that this system includes, for cleaning the primary air injection circuits; - there
Figure 6B shows, in section, a grid system according to the invention, as well as the main and cooling circuits of this circuit; - is a diagram illustrating the positioning of the support tubes of the plates of the grid system according to the invention; And
- there
figure 8 is a perspective and sectional view of a grid system according to the invention, which shows in particular the drive system of the plates of this system.
De manière générale, une installation de gazéification ou de combustion selon l'invention est destinée à brûler ou gazéifier un combustible solide, notamment issu de la biomasse, en vue d'une production de chaleur.Generally speaking, a gasification or combustion installation according to the invention is intended to burn or gasify a solid fuel, in particular from biomass, with a view to producing heat.
Le combustible est donc par nature hétérogène. Sa composition est variable. Notamment, il est plus ou moins sec.The fuel is therefore by nature heterogeneous. Its composition varies. In particular, it is more or less dry.
Une telle installation selon l'invention comprend un foyer qui est ménagé autour d'un axe de symétrie vertical. Ce foyer est délimité par une paroi latérale, par exemple cylindrique. Le combustible est admis dans le foyer par une entrée de combustible en correspondance avec un canal d'approvisionnement en combustible. Ce canal d'approvisionnement est préférentiellement formé d'un tube cylindrique vertical centré sur un ensemble de plateaux tournants superposés formant une grille. Au fur et à mesure de l'admission du combustible solide dans le foyer, verticalement, du bas vers le haut, par le canal d'approvisionnement, jusqu'à l'entrée de combustible, un monticule de combustible solide se forme sur la grille.Such an installation according to the invention comprises a hearth which is provided around a vertical axis of symmetry. This hearth is delimited by a side wall, for example cylindrical. Fuel is admitted into the hearth through a fuel inlet corresponding to a fuel supply channel. This supply channel is preferably formed of a vertical cylindrical tube centered on a set of superimposed rotating plates forming a grid. As solid fuel is admitted into the firebox, vertically, from bottom to top, through the supply channel, to the fuel inlet, a mound of solid fuel forms on the grate .
Ainsi que cela est montré à la
Le ou les plateaux supérieurs P2 à P4 sont positionnés sur le plateau inférieur P1, empilés sur ce plateau P1. Tous les plateaux P1 à P4 sont des plateaux tournants, montés mobiles en rotation autour d'un axe vertical A selon un angle de 360°. Le plateau inférieur P1 est monté sur une embase circulaire fixe 2.The upper plate(s) P2 to P4 are positioned on the lower plate P1, stacked on this plate P1. All plates P1 to P4 are rotating plates, mounted to rotate around a vertical axis A at an angle of 360°. The lower plate P1 is mounted on a fixed
Le plateau inférieur P1 est circulaire de diamètre D. Il s'agit du plus grand des plateaux. La surface du plateau supérieur P1 est égale à S1 (S=π(D/2)2)). La surface des plateaux supérieurs S2, S3, S4 est inférieure à S1. Ces surfaces S2, S3 et S4 sont décroissantes : S2 > S3 > S4.The lower plate P1 is circular with a diameter D. It is the largest of the plates. The surface of the upper plate P1 is equal to S1 (S=π(D/2) 2 )). The surface of the upper plates S2, S3, S4 is less than S1. These surfaces S2, S3 and S4 are decreasing: S2 > S3 > S4.
Des exemples de formes de ces plateaux supérieurs sont montrés aux
On notera que la forme du ou des plateaux supérieurs peut être diverse du moment qu'il rassemble les caractéristiques suivantes. Tout d'abord, le centre de gravité des plateaux est sur l'axe de rotation. Cela permet d'éviter d'avoir des efforts mécaniques répartis de manière non symétrique sur les supports du plateau. Cela permet d'améliorer la durée de vie du système. De plus, cela permet de couvrir et découvrir alternativement la surface du plateau inférieur lors de la rotation. Cela permet de « racler » la surface d'un plateau inférieur par un plateau supérieur et ainsi de faire avancer le combustible vers le pourtour du réacteur.Note that the shape of the upper plate(s) can be diverse as long as it combines the following characteristics. First of all, the center of gravity of the plates is on the axis of rotation. This makes it possible to avoid having mechanical forces distributed in a non-symmetrical manner on the supports of the plate. This improves the lifespan of the system. In addition, this allows the surface of the lower plate to be alternately covered and uncovered during rotation. This makes it possible to “scrape” the surface of a lower plate by an upper plate and thus to advance the fuel towards the periphery of the reactor.
L'épaisseur des plateaux P1, P2, P3, P4 est croissante dans l'empilement desdits plateaux dans le système de grille. Plus le plateau est positionné en hauteur dans cet empilement, plus son épaisseur est importante. Par exemple, le plateau inférieur P1 a une épaisseur de 100 mm, celle du plateau supérieur P2 qui lui est immédiatement supérieur a une épaisseur de 80 mm, celle du plateau P3 est de 60 mm et celle du plateau P4 est de 60 mm. Cela permet d'entraîner une quantité équivalente de combustible pour chaque plateau.The thickness of the plates P1, P2, P3, P4 increases in the stacking of said plates in the grid system. The higher the tray is positioned in this stack, the greater its thickness. For example, the lower plate P1 has a thickness of 100 mm, that of the upper plate P2 which is immediately above it has a thickness of 80 mm, that of the plate P3 is 60 mm and that of the plate P4 is 60 mm. This allows an equivalent quantity of fuel to be generated for each tray.
Les plateaux P1 à P4 sont réalisés de sorte qu'ils soient démontables par portion pour faciliter les opérations de maintenance et d'installation. Cela permet aussi d'optimiser le cout de maintenance en ne remplaçant que la portion d'un plateau abimé et pas l'ensemble du plateau. Ainsi que cela est montré à la
En outre, cela améliore la solidité des plateaux. Par ailleurs, les surfaces de fentes sont calculées de façon à optimiser les débits d'air et par làmême le profil de combustion/gazéification du combustible solide, au niveau de chaque plateau. Enfin, la section des fentes est calculée de façon à créer une perte de charge déterminée de l'air les traversant, assurant un débit homogène par fente, indépendant de la quantité locale de combustible située au-dessus, et évitant en particulier des fuites d'air incontrôlées en cas de manque de combustible au-dessus des fentes.In addition, this improves the strength of the trays. Furthermore, the slot surfaces are calculated so as to optimize the air flow rates and thereby the combustion/gasification profile of the solid fuel, at the level of each plate. Finally, the section of the slots is calculated so as to create a determined pressure loss of the air passing through them, ensuring a homogeneous flow rate per slot, independent of the local quantity of fuel located above, and in particular avoiding uncontrolled air leaks in the event of a lack of fuel above the slots.
Si l'on se réfère de nouveau à la
Les plateaux P1 à P4 ne tournent pas en même temps et à la même vitesse de telle sorte qu'il y ait un mouvement relatif entre les plateaux. Autrement dit, chacun des plateaux P1 à P4 tourne à une vitesse différente. Par ailleurs chacun des plateaux peut tourner à une vitesse variable pour ajuster le temps de séjour des cendres qui doit être variable en fonction de la nature des cendres. Les vitesses de rotation des plateaux sont réglables indépendamment les unes des autres. Elles sont contrôlées de manière indépendantes. Elles varient dans le temps de manière indépendante.The plates P1 to P4 do not rotate at the same time and at the same speed so that there is relative movement between the plates. In other words, each of the plates P1 to P4 rotates at a different speed. Furthermore, each of the plates can rotate at a variable speed to adjust the residence time of the ashes which must be variable depending on the nature of the ashes. The rotation speeds of the plates are adjustable independently of each other. They are independently controlled. They vary over time independently.
A noter que dans l'invention, les plateaux tournent à vitesse variable en fonction de la nature du combustible utilisé. Le fait que les plateaux puissent faire varier leur vitesse, permet de faire varier le temps de séjour dans le gazéifieur, en fonction de la nature du combustible et des cendres. Un temps de séjour trop long peut impliquer la fusion des cendres et donc le blocage, voire la destruction de la grille. Un taux de séjour trop court conduit à la présence d'imbrûlés au bas de la grille, ce qui diminue le rendement de l'installation et augmente le risque de blocage. Avec des déchets, par nature de composition variable, seule une grille avec vitesse de rotation variable peut fonctionner. En conclusion, la grille selon l'invention est la seule qui puisse s'adapter à une composition de déchets variable au fil du temps.Note that in the invention, the plates rotate at variable speed depending on the nature of the fuel used. The fact that the plates can vary their speed makes it possible to vary the residence time in the gasifier, depending on the nature of the fuel. and ashes. A residence time that is too long can cause the ashes to melt and therefore block or even destroy the grid. A residence rate that is too short leads to the presence of unburnt material at the bottom of the grid, which reduces the efficiency of the installation and increases the risk of blockage. With waste, by nature of variable composition, only a grid with variable rotation speed can work. In conclusion, the grid according to the invention is the only one that can adapt to a variable waste composition over time.
Une large fente 4 est aménagée sur le pourtour de la grille pour évacuer les cendres. Les cendres sont ainsi évacuées en continu du foyer au travers de cette fente 4.A
Le système de grille selon l'invention est aussi conçu pour ne pas créer de point d'accumulation de cendres indésirables.The grid system according to the invention is also designed not to create any unwanted ash accumulation points.
Les plateaux ont pour fonction d'étaler le combustible et d'amener les cendres vers l'extérieur, à savoir vers la large fente 4, afin de les évacuer. Le fait que tous les plateaux soient mobiles a deux avantages par rapport à des systèmes avec plateaux fixes. Tout d'abord, un seul plateau en mouvement permet de balayer le combustible du plateau mobile plus le combustible sur le plateau inférieur. On a donc moins besoin de faire tourner les moteurs pour le même service. On économise de l'énergie. De plus, le système est moins sensible aux éventuels blocages. Si un plateau est bloqué pour une raison quelconque, les plateaux au-dessus et au-dessous peuvent être utilisés pour continuer de faire fonctionner la grille, et donc l'unité de production d'énergie, le temps de planifier et de réaliser une opération de maintenance au moment le plus propice. La disponibilité du système de grille et la flexibilité vis-à-vis de la réparation sont plus élevées.The function of the trays is to spread the fuel and bring the ashes outwards, namely towards the
L'évacuation des cendres présentes dans le foyer se fait par la large fente ou gorge 4 positionnée sur tout le pourtour du système de grille. Les cendres tombent par cette fente sur un système de convoyage non représenté sur les figures, qui permet d'amener les cendres dans un espace de stockage. Cette large fente 4 est réalisée de sorte que les plus gros morceaux pouvant être injectés dans le foyer puissent en être évacués. La majorité des cendres est poussée par les plateaux rotatifs vers l'extérieur de la grille et donc vers cette fente 4. Cependant, des cendres de petites dimensions peuvent aussi être amenées sous les plateaux. A terme, ces cendres de petites dimensions sont susceptibles de bloquer ou de perturber l'écoulement de l'air primaire. Pour éviter ce phénomène, des dispositifs de raclage sont aménagés sous les plateaux. Ces dispositifs ne sont pas représentés dans les figures. Ils sont orientés de telle sorte que les cendres soient poussées vers l'extérieur de chaque plateau, puis collectées sur le plateau inférieur, jusqu'au plateau P1, où les cendres seront alors poussées vers la fente 4. Une ou plusieurs ouvertures peuvent en outre être ménagées en un point du pourtour du ou des plateaux de telle sorte que les cendres tombent dans la gorge. La section de l'ouverture est calculée précisément de façon à ne pas avoir une fuite d'air préférentielle, qui pourrait affecter le débit d'air principal transitant par les fentes.The evacuation of ashes present in the hearth is done through the wide slot or
Un système d'injection permet d'alimenter le foyer en air primaire à partir de deux entrées d'air indépendantes dans le système. Ces entrées sont référencées 5 et 6 aux
Ainsi que cela est monté à la
Ainsi que cela est plus particulièrement montré aux
En définitive, le système selon l'invention présente de nombreux avantages.Ultimately, the system according to the invention has numerous advantages.
Des premiers avantages découlent de la forme et de la conception des plateaux formant la grille du système de grille selon l'invention. Tout d'abord, le fait d'avoir des plateaux avec un centre de gravité sur l'axe de rotation permet d'utiliser des grilles plus grandes et plus lourdes. En effet, cette caractéristique permet d'éviter d'user le système de transmission mécanique de manière prématurée alors que des plateaux non équilibrés créent un porte-à-faux dommageable pour l'ensemble de la tenue mécanique dans le temps. Ensuite, le fait d'avoir tous les plateaux mobiles permet de faire fonctionner les moteurs moins longtemps pour un même effet d'avancement de la pile de combustible. Cela engendre des économies d'énergie pendant le fonctionnement et limite l'usure des pièces mécaniques. Un autre avantage de cette solution est que la grille est plus résiliente en cas de blocage. Elle peut continuer de fonctionner avec un plateau bloqué, les plateaux situés dessus et dessous le plateau bloqué fonctionnant de manière indépendante. La disponibilité de la grille est ainsi améliorée et la maintenance peut être planifiée au moment le plus propice. Ensuite encore, les plateaux sont tous démontables par portions. Cela permet de faciliter les opérations de maintenance et de les réaliser avec un minimum d'outils même pour une grille de grand diamètre. Par ailleurs, les fentes complètes dans les plateaux et l'utilisation d'un acier réfractaire permettent une bonne tenue des plateaux à la température et d'avoir des plateaux plus fins. Cela confère un gain économique à la fabrication mais cela facilite aussi la maintenance avec des plateaux plus légers à manipuler. Enfin, La hauteur variable des plateaux permet de s'affranchir du paradoxe d'une grille circulaire alimentée par le centre. En effet, sur ce type de grille on a beaucoup de matière au centre (combustible non brûlé) mais peu de surface alors que sur l'extérieur de la grille il y a beaucoup moins de matière (cendres) mais une surface de grille plus importante. La hauteur variable des plateaux permet de compenser ce phénomène et de mieux maîtriser la combustion.First advantages arise from the shape and design of the plates forming the grid of the grid system according to the invention. First of all, having trays with a center of gravity on the axis of rotation allows the use of larger and heavier grids. In fact, this characteristic makes it possible to avoid wearing out the mechanical transmission system prematurely while unbalanced plates create an overhang that is damaging to the entire mechanical performance over time. Then, the fact of having all the moving plates makes it possible to run the engines for less time for the same effect of advancing the fuel cell. This results in energy savings during operation and limits wear on mechanical parts. Another advantage of this solution is that the grid is more resilient in the event of a blockage. It can continue to operate with a blocked plate, the trays located above and below the blocked tray operating independently. Grid availability is thus improved and maintenance can be planned at the most convenient time. Then again, the trays can all be dismantled in portions. This makes maintenance operations easier and can be carried out with a minimum of tools, even for a large diameter grid. Furthermore, the complete slots in the trays and the use of refractory steel allow the trays to hold the temperature well and to have thinner trays. This provides an economic gain in manufacturing but it also facilitates maintenance with trays that are lighter to handle. Finally, the variable height of the trays makes it possible to overcome the paradox of a circular grid fed from the center. Indeed, on this type of grid there is a lot of material in the center (unburned fuel) but little surface area whereas on the outside of the grid there is much less material (ash) but a larger grid surface area. . The variable height of the plates makes it possible to compensate for this phenomenon and better control combustion.
Des deuxièmes avantages découlent du système d'injection d'air primaire selon le système de l'invention. Tout d'abord, le double circuit d'air primaire permet d'injecter des fumées recirculées ou de l'air préchauffé à une température élevée, par exemple de l'ordre de 200 °C, tout en assurant au système mécanique d'être refroidi et non pollué par des poussières volantes. La recirculation de fumées ou le préchauffage de l'air sont un avantage pour diminuer la production de NOx et pour les combustibles à bas Pouvoir Calorifique. Ensuite, le système d'injection d'air primaire permet d'assurer la distribution de l'air sous la grille et donc de mieux maîtriser la combustion. Il permet aussi de refroidir la grille avec l'air primaire.Second advantages arise from the primary air injection system according to the system of the invention. First of all, the double primary air circuit makes it possible to inject recirculated fumes or air preheated to a high temperature, for example of the order of 200°C, while ensuring that the mechanical system is cooled and not polluted by flying dust. Flue gas recirculation or air preheating are an advantage for reducing NOx production and for low calorific value fuels. Then, the injection system primary air ensures the distribution of air under the grille and therefore better controls combustion. It also allows the grid to be cooled with primary air.
Des troisièmes avantages découlent de la gestion de l'évacuation des cendres selon le système de l'invention. Tout d'abord, la gorge d'évacuation des cendres sur tout le pourtour de la grille est large et permet d'évacuer la totalité des intrants solides ou des mâchefer produits. Ensuite, le système de racleurs sous les plateaux permet d'évacuer les éventuelles petites particules de cendres qui se glisseraient sous les plateaux de manière continue. Cela permet de prévenir des blocages mécaniques ou des bouchages d'injection de l'air.Third advantages arise from the management of ash evacuation according to the system of the invention. First of all, the ash evacuation throat all around the grid is wide and allows all solid inputs or clinker produced to be evacuated. Then, the scraper system under the trays makes it possible to evacuate any small particles of ash which would slip under the trays continuously. This helps prevent mechanical blockages or air injection blockages.
Des quatrièmes avantages découlent de la conception du système d'entrainement du système de grille selon l'invention. Le système d'entrainement basé sur des tubes concentriques permet une grande flexibilité pour le choix du mécanisme d'entrainement utilisé. Il peut être adapté en fonction des caractéristiques de la grille et du combustible.Fourth advantages arise from the design of the drive system of the grid system according to the invention. The drive system based on concentric tubes allows great flexibility in the choice of the drive mechanism used. It can be adapted according to the characteristics of the grid and the fuel.
Claims (13)
- De-ashing grate system (1) for a furnace of a combustion or gasification installation supplied with solid fuel, said gate system comprising a lower circular plate (P1) of diameter D1 and surface area S1 mounted so as to rotate through 360° on a vertical rotation axis (A), and furthermore comprising at least one upper plate (P2, P3, P4), superimposed on said lower plate (P1), and mounted so as to rotate through 360° on the vertical rotation axis (A), said at least one upper plate (P2, P3, P4) having a surface area S2 smaller than the surface area S1 of the lower plate (P1) and a maximum dimension of no more than the diameter D1 of this lower plate (P1), said plates (P1, P2, P3, P4) being movable, the centre of gravity of said plates (P1, P2, P3, P4) being on the vertical rotation axis (A), characterised in that the upper plate or plates (P2, P3, P4) have a shape different from the circular shape and a largest dimension substantially equal to the smallest dimension of the plate on which they are superimposed, the lower (P1) and upper (P2, P3, P4) plates being adapted not to turn at the same speed.
- System (1) according to claim 1, characterised in that each plate (P1, P2, P3, P4) is able to rotate at a rotation speed Vi, this rotation speed being variable over time according to the composition of the fuel.
- System (1) according to one of claims 1 or 2, characterised in that the upper plate or plates are adapted to turn at different and variable rotation speeds individually.
- System (1) according to one of the preceding claims, characterised in that it comprises a plurality of upper plates (P2, P3, P4) superimposed on one another, all the upper plates (P2, P3, P4) being superimposed on the lower plate (P1), in that the surface S2 of the plate (P2) immediately higher than the lower plate (P1) fits in that S1 of said lower plate, and in that the surface S3 and optionally the surface S4 of the upper plate or plates (P3, P4) positioned above the plate (P2) immediately higher than the lower plate (P1) decrease according to their position in the superimposition of the plates.
- System (1) according to one of the preceding claims, characterised in that the upper plate or plates (P2, P3, P4) have an elliptical shape.
- System (1) according to one of the preceding claims, characterised in that the plates (P1, P2, P3, P4) are perforated.
- System (1) according to one of the preceding claims, characterised in that the plates (P1, P2, P3, P4) have slots (F1, F2) and/or openings (O).
- System (1) according to one of the preceding claims, characterised in that a circular fuel inlet (3) is provided at the centre of the stack of plates (P1, P2, P3, P4), the centre of said circular inlet being positioned substantially on the vertical rotation axis (A) and in that a tube (8) connected to this inlet (3) enables fuel to be admitted, vertically, through the superimposed plates (P1, P2, P3, P4).
- System (1) according to one of the preceding claims, characterised in that it includes two primary-air inlets (5, 6) of two independent air circuits (C1, C2), a main air circuit (C2) and a cooling air circuit (C1).
- System (1) according to one of the preceding claims, characterised in that it includes an injection air ring (CA) around the lower plate (P1), said air ring being adapted to inject air radially onto the lower plate, to eliminate the presence of unburnt material in the ash by combustion.
- System (1) according to one of the preceding claims, characterised in that coaxial cylindrical tubes (T1, T2, T3, T4) are secured to the plates (P1, P2, P3, P4), one cylindrical tube being secured to each plate, and in that the plates are rotated by means of these tubes, which are themselves rotated independently by drive means.
- Combustion or gasification installation supplied with solid fuel, comprising a grate system (1) according to one of the preceding claims.
- Installation according to claim 12, characterised in that the fuel is a fuel coming from biomass.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR2002937A FR3108709B1 (en) | 2020-03-25 | 2020-03-25 | Ash grate system for the hearth of a combustion or gasification installation |
Publications (3)
Publication Number | Publication Date |
---|---|
EP3885651A1 EP3885651A1 (en) | 2021-09-29 |
EP3885651C0 EP3885651C0 (en) | 2023-11-08 |
EP3885651B1 true EP3885651B1 (en) | 2023-11-08 |
Family
ID=70457053
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP21163539.6A Active EP3885651B1 (en) | 2020-03-25 | 2021-03-18 | Rotary de-ashing grate system for furnace of a combustion or gasification installation |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP3885651B1 (en) |
ES (1) | ES2965055T3 (en) |
FR (1) | FR3108709B1 (en) |
MA (1) | MA55152A (en) |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR870351A (en) * | 1940-11-07 | 1942-03-10 | Fireplace grate allowing the use as fuel: coal dust, all household waste, green or dry sawdust, all wood waste | |
CH226199A (en) * | 1941-03-06 | 1943-03-31 | Forni Ed Impianti Ind Ingg De Bartolomeis Spa | Rotating grid. |
ITUB20153154A1 (en) * | 2015-08-18 | 2017-02-18 | Paolo Gaggero | Grill for burners or gas generators for solid fuels and gas for biomasses |
-
2020
- 2020-03-25 FR FR2002937A patent/FR3108709B1/en active Active
-
2021
- 2021-03-18 ES ES21163539T patent/ES2965055T3/en active Active
- 2021-03-18 EP EP21163539.6A patent/EP3885651B1/en active Active
- 2021-03-18 MA MA055152A patent/MA55152A/en unknown
Also Published As
Publication number | Publication date |
---|---|
EP3885651C0 (en) | 2023-11-08 |
EP3885651A1 (en) | 2021-09-29 |
FR3108709B1 (en) | 2022-03-11 |
MA55152A (en) | 2022-05-11 |
FR3108709A1 (en) | 2021-10-01 |
ES2965055T3 (en) | 2024-04-10 |
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