Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C10/00—Fluidised bed combustion apparatus
  • F23C10/005—Fluidised bed combustion apparatus comprising two or more beds
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C10/00—Fluidised bed combustion apparatus
  • F23C10/18—Details; Accessories
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C6/00—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion
  • F23C6/04—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
  • F23G5/02—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment
  • F23G5/027—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment pyrolising or gasifying stage
  • F23G5/0276—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment pyrolising or gasifying stage using direct heating
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
  • F23G5/30—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having a fluidised bed
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C2201/00—Staged combustion
  • F23C2201/10—Furnace staging
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C2900/00—Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor
  • F23C2900/10007—Spouted fluidized bed combustors

Definitions

• the invention relates to an arrangement in a boiler using fluidized-bed technology.
• the invention further relates to a method in a boiler using fluidized-bed technology.
• BFB bubbling fluidized bed boilers
• the temperature of the bed is adjusted to a required level by grate dimensioning, primary air volume and circulation gas.
• the volume of circulation gas may become very large, because the temperature of the fluidized bed typically needs to be kept at 600 to 750°C to prevent sintering.
• inventive embodiments are also disclosed in the specification and drawings of this application.
• inventive contents of the application may also be defined in ways other than those described in the following claims.
• inventive contents may also consist of several separate inventions, particularly if the invention is examined in the light of expressed or implicit sub-tasks or in view of obtained benefits or benefit groups. In such a case, some of the definitions contained in the following claims may be unnecessary in view of the separate inventive ideas.
• Features of the different embodiments of the invention may be applied to other embodiments within the scope of the basic inventive idea.
• the idea of the invention is that the boiler is divided by a partition wall and roof structure into two sections or spaces, in the first of which fuel is gasified and in the second of which the fuel is burned.
• the advantage is that it is possible to use, even without limitations, fuels, the ash of which melts in low temperatures.
• Another advantage may be the flexibility of the boiler in relation to the fuels that can be burned in it.
• Yet another advantage may be a better efficiency and reduced internal consumption due to the fact, among other things, that less high-pressure air is required to maintain a smaller fluidized bed and that less sand mass is required, which means that the bed weighs less and the structure of the boiler can be correspondingly lightened.
• the arrangement comprises at least two first spaces that are arranged on different sides of a second space of a furnace.
• the advantage is that the arrangement can be efficiently applied to large-scale boilers.
• the idea of an embodiment is that it comprises nozzles arranged at the bottom or in the bottom part of the second space of the furnace for feeding bottom air.
• the advantage is that any fuel that ends up at the bottom of the second space can be burned.
• the partition wall and/or roof structure is at least partly made of a membrane wall connected to the water/vapour circulation of the boiler.
• the advantage is that the recovery of thermal energy can be improved and the thermal expansions of the partition wall and/or roof structure can be controlled.
• the partition wall comprises a bend that increases the rigidity of the partition wall.
• the idea of an embodiment is that the partition wall extends to a distance from the roof structure, whereby the gap between them forms a flow path.
• the advantage is that a flow path is achieved that has a low flow resistance.
• the partition wall and/or roof structure is at least partly made of a membrane wall connected to the water/vapour circulation of the boiler and that the membrane walls are connected to each other through a lattice pipe system, and the gaps in the lattice pipe system form the flow path.
• the advantage is that the recovery of thermal energy is boosted and a partition wall - roof structure having good strength is formed.
• the roof structure comprises a bottom surface that is arranged to ascend to the end of the roof structure, and a top surface that is arranged to descend to the end of the roof structure.
• the advantage is that the bottom surface guides gases toward the second space and the top surface guides the residue falling from the walls of the second space to the bottom of the second space.
• Figure 1 is a schematic sectional side view of an arrangement of the invention
• Figure 2 is a schematic view of an embodiment of a detail of the arrangement according to the invention in cross-section
• Figure 3a is a schematic sectional side view of a second arrangement of the invention
• Figure 3b is a schematic view of the cross-section of the detail of the arrangement shown in Figure 3a.
• Figure 4 is a schematic sectional side view of a third arrangement of the invention.
• Figure 1 is a schematic sectional side view of an arrangement and method of the invention.
• the boiler 10 is a bubbling fluidized bed boiler (BFB).
• BFB bubbling fluidized bed boiler
• the boiler 10 may be supported from below and/or the top.
• a BFB boiler like other boiler types based on fluidization, is especially well suited for burning so-called poor-grade fuels, such as wet bio- masses, sludges, recycled fuels, and waste coals; naturally other fuels can also be used.
• the boiler is used in burning so-called agro fuels.
• An agro fuel refers to straw, straw pellets, palm oil waste or any other waste produced in agricultural production, for example.
• Agro fuels typically originate from fast-growing plants and, thus, contain lots of alkalis, chlorine and phosphor.
• the boiler 10 comprises a furnace that is divided into two spaces: a first space 1 and a second space 2.
• the boiler also has, among other things, a flue gas channel and channels for feeding combustion air, fuel, reagents and other additives possibly needed in burning into the furnace 2.
• Thermal energy generated in the thermal process taking place in the boiler 10 can be recovered by means of walls formed of water pipes and other heat delivery surfaces.
• the figures do not show all details of the boiler 10 to simplify the presentation.
• the first space 1 of the furnace comprises means known per se for forming 21 a fluidized bed, and from the second space 2, they are missing.
• Fuel F is fed to the first space of the furnace with appropriate means that comprise, among other things, one or more feed channels 4.
• the feed channel 4 is preferably directed to the middle of the bottom 15 of the first space, whereby the entire surface area of the bottom 15 is utilized as well as possible.
• the boiler 10 may be a front wall-fed furnace as shown in Figure 1 or a side wall-fed furnace.
• the boiler 10 comprises nozzles 22 for feeding primary air and/or circulation gas into the first space 1 of the furnace.
• nozzles 22 for feeding primary air and/or circulation gas into the first space 1 of the furnace.
• the amount of necessary circulation gas is also rather small due to the small surface area of the grate in the first space.
• the temperature of the first space 1 is adjusted with circulation gas in such a manner that it is below the sintering temperature, that is, typically below 750°C.
• Circulation gas comprises flue gases generated during the process in the boiler 10.
• a sub-stoichiometric state prevails in the first space 1 and its air coefficient may be 0.2 to 0.5, for instance, depending on the used fuel.
• a partition wall 3 and roof structure 5 are arranged between the first space 1 and the second space 2.
• the partition wall 3 is at least mainly vertical, whereas the roof structure 5 arranged above the first space 1 forms a horizontally extending obstacle or space divider between the first space 1 and part of the second space 2 above it.
• the partition wall 3 extends to a distance from the roof structure 5, whereby the gap between them forms a flow path 18. Gases rising from the fluidized bed can flow through the flow path 18 from the first part 1 to the second part 2 as shown by arrow G.
• the partition wall 3 may have additional functional features, for instance in the partition wall shown in Figure 1 , there is a bend 17 that increases the rigidity of the wall 3.
• the location, direction, shape, depth, and number of the bend may differ from the example shown in the figure.
• the partition wall 3 is bent at its top toward the first part 1 . It is then possible to use a shorter roof structure 5, which in turn increases the effective volume of the boiler.
• the partition wall 3 may also naturally be straight without any specific functional shapes.
• the height of the partition wall 3 is selected to only just prevent the fuel from flying over to the second space 2.
• the height of the partition wall is approximately 5 m, when the height of the boiler is approximately 20 m.
• the wall surfaces of the first space 1 and thus also the partition wall 3 may comprise brickwork that extends to a height of 2.5 m, for instance.
• the wall 3 is at least partly formed of a membrane wall 16 connected to the water/vapour circulation of the boiler 10.
• a membrane wall 16 connected to the water/vapour circulation of the boiler 10.
• An example of the structure of the membrane wall is shown in Figure 2.
• the roof structure 5 can also be at least partly formed of the membrane wall 16 connected to the water/vapour circulation of the boiler 10.
• the wall 3 and roof structure 5 that comprise a membrane wall 16 provide the advantage that they boost the recovery of thermal energy in the boiler 10.
• the partition wall 3 and/or roof structure 5 can naturally be implemented using different solutions, such as a plate structure or a combination of a plate structure and brickwork.
• the roof structure 5 is preferably shaped to improve the natural flow of the gases G.
• the bottom surface 6 of the roof structure may be arranged to ascend toward the end 20 of the roof structure and, on the oth- er hand, the top surface 7 of the roof structure may be arranged to descend toward the end 20 of the roof structure.
• the roof structure 5 covers the first space 1 of the furnace entirely; most preferably the roof structure 5 extends to some extent past the partition wall 3. When it is dimensioned in this way, the roof structure 5 prevents the fall of detaching ash layers and other layers into the fluidized bed from the top part of the furnace in the second space 2. According to an idea, the roof structure extends approximately 0.5 m or more past the partition wall 3.
• the layers may detach by themselves or be detached by sweepers 1 1 , such as hydraulic guns, vapour sweepers, and audio sweepers.
• sweepers 1 1 such as hydraulic guns, vapour sweepers, and audio sweepers.
• the roof structure 5 also prevents thermal radiation from the top part of the second space 2 to the fluidized bed, thanks to which the temperature of the fluidized bed or first space 1 is easier to keep sufficiently low. Further, the roof structure 5 may cause turbulence in the flow of the gas G, which boosts the mixing of the fuel and air and, therefore, burning.
• the second space 2 of the furnace is the combustion section, into which the remaining combustion air is fed to burn the fuel.
• Air nozzles 9 for feeding secondary, tertiary and possible other higher airs are arranged in the second space 2; the second space may also have nozzles for feeding circulation gas, among other things.
• the temperature may rise substantially higher than in the first space 1 , to 1 100° to 1400°, for instance.
• the air coefficient of the top part of the second space 2 may be over one, and the fuel is burned out there.
• the fuel gasifies and may also partly burn already in the first space 1 .
• the walls of the second space 2 may scorify and/or foul due to melted ash. However, this does not cause problems, because the walls can be cleaned with above-mentioned sweepers 1 1 .
• the second space 2 may have a nose 8 guiding the flow of the flue gases.
• a slag and ash removal system 12 to remove the fallen matter from the boiler 10 has been arranged at the bottom of the second space 2.
• the slag and ash removal system 12 may also be extended to the first part 1 , as shown in Figure 1 .
• the first space 1 has its own bottom ash removal system.
• bottom air-feeding nozzles 24 can be arranged in the second space 2, at its bottom 23 or in its bottom part. With the bottom air fed through them, it is possible to burn any fuel particles that may fly there from the first space 1 .
• Flue gases are led from the second space 2 of the furnace away from the furnace to a so-called empty pass and on to thermal surfaces.
• the second space 2 of the furnace may have thermal surfaces, but this is not necessary.
• Figure 2 is a schematic cross-sectional view of an embodiment of the partition wall and/or roof structure of the arrangement according to the invention.
• the partition wall 3 and roof structure 5 may be at least partly formed of a membrane wall 16 connected to the water/vapour circulation of the boiler 10.
• the membrane wall 16 typically comprises cooling pipes 13 arranged side by side and in the same direction and fastened to each other by fins 14. This type of gas-tight structure is known from furnace walls.
• the membrane wall 16 may be made by welding, for example.
• the structure of the membrane wall 16 can naturally also be made in some other way, for instance by directly joining adjacent cooling pipes 13 or by doing the opposite, that is, by increasing the width of the fin 14 in view of the embodiment shown in Figure 2.
• Figure 3 is a schematic sectional side view of another arrangement and method of the invention, and Figure 3b is a schematic view of the cross-section of a detail of the arrangement.
• the partition wall 3 extends to the roof structure 5.
• Gas G flows from the first part 1 to the second part 2 through one or more openings 19 arranged in the partition wall 3.
• the flow path 18 is formed of one or more openings 19.
• the openings 19 are formed of the cooling pipes 13 of the membrane wall 16, from the gaps of which the fins 14 are left out along a suitable length and which are grouped in a lattice form.
• the membrane walls of the partition wall 3 and roof structure 5 are then connected to each other.
• Fig- ure 3b shows a possible lattice 25.
• the lattice 25 can naturally be of some other kind, as long as the cooling pipes 13 are arranged loosely so that the gases G can flow through them via the openings 19.
• the cooling pipes 13 of the lattice 25 can be connected to the cooling pipes 13 of the partition wall 3 and/or roof structure 5 through collector chambers 26.
• the lattice 25 may be formed of cooling pipes 13, the diameter of which differs from that of the cooling pipes 13 of the membrane wall 16.
• the number of cooling pipes 13 forming the lattice 25 may differ from the number of cooling pipes 13 of the membrane wall 16 connected to the collector chambers 26.
• the lattice 25 is directed obliquely downward by dimensioning the partition wall 3 and roof structure 5.
• the roof structure 5 forms a lid over the lattice 25 to prevent matter detached from the second space 2 from falling into the first space 1 .
• a bend 17 toward the first space 1 in the wall below the lattice 25 stiffens the structure, increases the effective volume of the second space 2 and guides the matter detached from the second space 2 to the bottom 23 of the second space.
• the direction of the bend 17 is selected to be the most advantageous for the entity.
• Figure 4 is a schematic sectional side view of a third arrangement and method of the invention.
• the arrangement may comprise at least two first spaces 1 that are arranged on different sides of the second space 2 of the furnace.
• first spaces 1 there are two first spaces 1 .
• the features of both first spaces 1 may be as already described above: both may have a fuel feed channel 4 connected to them, for example. This type of solution is especially advantageous for use in large boilers 10.
• the shapes and structure of the partition wall 3 and roof structure 5 may also be implemented in some other manner, for instance as in Figure 3a.
• features disclosed in this application may be used as such, regardless of other features.
• features disclosed in this application may be combined in order to provide different combinations.
• the arrangement of the invention is characterised in that it comprises a first space of a furnace that comprises means for forming a fluidized bed, a second space of a furnace that does not have means for forming a fluidized bed, means for feeding fuel into the first space of the furnace, a partition wall that is at least mainly vertical and arranged between said spaces of the furnace to separate them from each other, and the arrangement further comprises a roof structure arranged above the first space of the furnace to separate the first space of the furnace from parts of the second space of the furnace above it, and that the first space of the furnace is connected to the second space of the furnace through a flow path that is arranged on the side of the first space of the furnace to lead gases rising from the fluidized bed to the second space of the furnace.
• the method of the invention is characterised by feeding fuel into a first space of a furnace that comprises means for forming a fluidized bed, allowing gases rising from the fluidized bed move to the second space of the furnace past a partition wall and under a roof structure arranged above the first space of the furnace, the partition wall being at least mainly vertical and arranged between said spaces of the furnace to separate them from each other, and the roof structure being arranged to separate the first space of the furnace from parts of the second space of the furnace above it.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Fluidized-Bed Combustion And Resonant Combustion (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (3)

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ID=50884937

Family Applications (1)

Country Status (7)

Families Citing this family (1)

Family Cites Families (13)

• 2013
  • 2013-05-14 FI FI20135507A patent/FI126744B/fi active IP Right Grant
• 2014
  • 2014-05-13 DK DK14728236.2T patent/DK2997307T4/da active
  • 2014-05-13 PL PL14728236T patent/PL2997307T5/pl unknown
  • 2014-05-13 WO PCT/FI2014/050356 patent/WO2014184437A1/en active Application Filing
  • 2014-05-13 PT PT147282362T patent/PT2997307T/pt unknown
  • 2014-05-13 ES ES14728236T patent/ES2636452T5/es active Active
  • 2014-05-13 EP EP14728236.2A patent/EP2997307B2/de active Active

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