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
  • F23C10/18—Details; Accessories
  • F23C10/20—Inlets for fluidisation air, e.g. grids; Bottoms
• • 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
  • F23C10/24—Devices for removal of material from the bed

Definitions

• the presented solution relates to a grate assembly for use in a bottom section of a combustion chamber of a fluidized bed boiler.
• the grate assembly includes a grate module or at least two adjacent grate modules constituting the bottom section.
• the presented solution relates to a fluidized bed boiler for use in steam production and having a combustion chamber.
• a bottom section of a combustion chamber of a fluidized bed boiler may include a sloping floor or sloping floor sections for facilitating removal of solids when transferring the solids into a solids removal opening by means of air jets and gravity, the sloping floor being formed by a protective refractory material layer.
• the air jets are brought about by nozzle devices providing air for combustion and fluidization.
• the nozzle devices extend from the protective refractory material layer to varying heights.
• the nozzle devices may obstruct the removal of solids or the orientation of the air jets is not optimal.
• the nozzle devices may be abraded by the air jets carrying solids or fluidized bed material.
• the height differences in the sloping floor including the nozzle devices may vary strongly depending on the dimensions of the combustion chamber. Thus, the operation of the fluidized bed of the combustion chamber may be affected.
• the shape and structure of the protective refractory material layer may differ between boilers.
• Document JP 59197714 A discloses a grate assembly in a fluidized bed boiler.
• Document EP 2802410 B1 discloses a grate assembly in a fluidized bed boiler, the grate assembly including concentric rings arranged at various levels.
• Document KR 2013 0074303A discloses the features in the preamble of the appended independent claim 1.
• the grate assembly according to the invention is presented in claim 1.
• a fluidized bed boiler including the above-mentioned grate assembly is presented in claim 15.
• the grate assembly according to the invention is for use in a bottom section of a combustion chamber of a fluidized bed boiler.
• the grate assembly comprises a grate bottom wall having a plurality of cooling tubes that are attached to the grate bottom wall; a protective refractory material layer on the grate bottom wall and covering the plurality of cooling tubes; and a plurality of nozzle devices for supplying fluidizing primary air above the grate bottom wall and the protective refractory material layer into the combustion chamber for maintaining combustion of fuel and fluidization of bed material.
• the grate assembly further comprises at least one grate module formed on the grate bottom wall, each grate module comprising a solids removal opening in the refractory material layer via which solids on the refractory material layer are guided downwards to a solids removal conduit adapted to guide the solids through the refractory material layer and the grate bottom wall.
• Each grate module further comprises a plurality of concentric landings each formed in the refractory material layer, the landings being situated at intervals in a vertical direction and being separated by frontal surfaces between the landings.
• Each frontal surface surrounds one of the landings and follows the shape of the perimeter of a rectangle or a rectangle with at least one shaped corner.
• the landings define a stepped structure that descends towards the solids removal opening situated in the center of the landings.
• Each landing comprises a group of nozzle devices belonging to the plurality of nozzle devices and being embedded in the refractory material layer. The group of nozzle devices is directed to jet the air through one of the frontal surfaces along one of the landings that is adjacent to the frontal surface.
• the at least one shaped corner includes a chamfer, multiple chamfers, a step, multiple steps, a shape extending inwards the rectangle, and/or a shape extending outwards the rectangle.
• each landing comprises four rows of nozzle devices each with nozzle devices aligned in a row and belonging to the group of nozzle devices.
• the frontal surface comprises four corners each having at least one nozzle device belonging to the group of nozzle devices and being between two of the rows of nozzle devices.
• the fluidized bed boiler for use in steam production comprises a combustion chamber with a bottom section including the above-mentioned grate assembly.
• the presented invention is particularly advantageous and solves the above-mentioned problems.
• the grate module of the presented invention provides a modular and expandable system for constructing the bottom section of the combustion chamber of the fluidized bed boiler.
• the use of the grate modules of the presented invention provides a way of restricting the height differences between the nozzle devices.
• the height differences and the height of the stepped structure of the grate assembly and the grate module can be chosen in such a way that the motion of the fluidizing primary air above the grate assembly takes place in a desired or controlled manner.
• rows of additional nozzle devices are easily integrated into or between the grate modules for facilitating the design of the layout of the grate assembly and the bottom section of the combustion chamber.
• the central location of the solids removal opening in the grate module provides an efficient way of removing solids.
• the size and dimensions of the grate module can be chosen in such a way that solids are efficiently transferred to the solids removal opening.
• the presented invention provides a simple structure in which the grate bottom wall and the plurality of parallel cooling tubes extend horizontally.
• the presented invention provides the plurality of nozzle devices embedded in the refractory material layer constituting the stepped structure and thereby unobstructed removal of solids is facilitated by the surfaces of the stepped structure of the grate module.
• the nozzle devices in corners of the grate module are oriented to remove solids efficiently from the surfaces of the stepped structure.
• the terms “horizontal” and “vertical” refer to the intended operating positions of the device or component in question when installed in place for implementing the functions of the described solution.
• the terms “horizontal” and “vertical” are used to indicate direction relative to an absolute reference, i.e. ground level.
• the vertical direction is denoted by an arrow Z and the two orthogonal, horizontal directions are denoted by arrows X and Y.
• the horizonal directions are orthogonal in relation to the vertical direction.
• the terms “upper”, “lower”, “on top”, “below”, “upward”, and “downward” relate to the above-mentioned, intended operating positions.
• the terms “parallel” and “perpendicular” should not be construed to require structures to be absolutely parallel or absolutely perpendicular to each other.
• the term “opposite” should not be construed to require opposite directions to be absolutely parallel to each other.
• the fluidized bed boiler 10 may be a part of a power plant, a steam boiler plant, or a hot water boiler plant, adapted for the production of electric energy, steam, and/or heating energy.
• the boiler 10 includes a combustion chamber 12, i.e. a furnace, for the combustion of fuels and a flue gas channel 16 for conveying flue gases, i.e. combustion product gases, coming from the combustion chamber 12.
• a combustion chamber 12 i.e. a furnace
• flue gas channel 16 for conveying flue gases, i.e. combustion product gases, coming from the combustion chamber 12.
• the boiler 10 may comprise further devices that are relevant for the design in question but are not necessarily shown in the figures.
• the boiler 10 may additionally comprise a cyclone separator 14 connected to the combustion chamber 12 for separating solid particles from the flue gases coming from the combustion chamber 12 and for guiding the flue gases to the flue gas channel 16.
• the boiler 10 may further comprise a support frame 18 for supporting the combustion chamber 12 and the flue gas channel 16 to the ground.
• the support frame 18 may, for example, include columns 22, supporting beams 24 and/or hangers 26 for supporting the combustion chamber 12 and/or the flue gas channel 16 to the support frame 18.
• the boiler 10 may be a fluidized bed boiler of CFB design (circulating fluidized bed) or BFB design (bubbling fluidized bed).
• the fuel may be a gas, solid fuel or solid waste from various sources, e.g. municipal waste. Fluidizing air realizing a fluidized bed and to be used as primary air for combustion is fed into the combustion chamber 12 via a bottom section 28 constituting the lower part of the combustion chamber 12.
• the grate assembly for use in the bottom section 28 of the combustion chamber of the fluidized bed boiler 10 comprises a grate bottom wall 32, a protective refractory material layer 36, a plurality of nozzle devices 38, and at least one grate module 40.
• the grate bottom wall 32 includes a plurality of cooling tubes 34 that are attached to the grate bottom wall 32.
• the grate bottom wall 32 extends horizontally and the plurality of cooling tubes 34 are parallel, extend horizontally, and are attached to the grate bottom wall 32 at intervals along the grate bottom wall 32.
• the grate bottom wall 32 is constituted by the plurality of cooling tubes 34 separated by fins attached between the cooling tubes 34.
• the protective refractory material layer 36 is situated on the grate bottom wall 32 and covers the plurality of cooling tubes 34.
• the plurality of nozzle devices 38 are for supplying fluidizing primary air for maintaining combustion of fuel and fluidization of bed material above the grate bottom wall 32 and the protective refractory material layer 36 into the combustion chamber 12.
• Each nozzle device 38 is adapted to guide primary air that arrives through the grate bottom wall 32 and the refractory material layer 36 and to jet the air to be used as the fluidizing primary air.
• the nozzle device 38 includes a conduit section attached to and going through the grate bottom wall 32, and a mouth section for jetting out the air guided via the conduit section.
• the grate assembly 30 comprises, for example, one grate module 40 or 2 to 36 adjacent grate modules 40.
• the grate modules 40 constitute a N x M grid, with N equaling 1, 2, or 3 and M equaling 2, 12, or a whole number between 2 and 12.
• all the grate modules 40 of the grate assembly 30 are similar.
• the grate assembly 30 may include similar and/or dissimilar grate modules 40.
• Each grate module 40 comprises a solids removal opening 42, a solids removal conduit 44, and a plurality of concentric landings 46.
• the solids removal opening 42 is formed in the refractory material layer 36 via which solids removal opening 42 solids on the refractory material layer 36 are guided, by means of air in motion and gravity, downwards through the refractory material layer 36 and the grate bottom wall 32.
• the solids are guided downwards to a solids removal conduit 44 of the fluidized bed boiler 10 or the grate assembly.
• Each landing 46 is formed in the refractory material layer 36.
• the landings 46 are situated at intervals in relation to a vertical direction and are separated from each other by frontal surfaces 48 that are situated between the landings 46.
• the landings 46 constitute a stepped structure, e.g. a funnel, that descends towards the solids removal opening 42 that is situated in the centre of the landings 46.
• the frontal surfaces 48 extend vertically.
• Each frontal surface 48 surrounds one of the landings 46 and follows the shape of the perimeter of a rectangle, or the shape of the perimeter of a rectangle with at least one shaped corner.
• each frontal surface 48 surrounds one of the landings 46 and follows the shape of the perimeter of a square, or the shape of the perimeter of a square with at least one shaped corner.
• the square, representing a rectangle, is a special case of the rectangle with four sides of equal length.
• the at least one shaped corner includes a chamfer ( Fig. 5(b) ), multiple chamfers ( Fig. 5(c) ), a step ( Fig. 5(d) (g) ), multiple steps ( Fig. 5(e) (f) ), a shape extending inwards the rectangle ( Fig. 5(b) (c) (d) (e) ), and/or a shape extending outwards the rectangle ( Fig. 5(f) (g) ).
• all the four corners of the rectangle are similar.
• the corner is formed of two perpendicular edges ( Fig. 5(a) ).
• Each landing 46 comprises a group of nozzle devices 38 belonging to the plurality of nozzle devices 38.
• the group of nozzle devices 38 is embedded in the refractory material layer 36 and are configured, directed, or oriented to jet the air through one of the frontal surfaces 48 and further along one of the landings 46 that is adjacent to the one frontal surface 48.
• the one landing 46 is between the one frontal surface 48 and another frontal surface 48 situated lower in relation to a vertical direction.
• the one landing 46 is between the one frontal surface 48 and the solids removal opening 42 at the centre of the grate module 40.
• the solids removal opening 42 is circular.
• the solids removal opening 42 may be, for example, of rectangular, e.g. a square, or polygon shape.
• the nozzle devices 38 are adapted to jet the air to horizontal directions.
• each nozzle device 38 is adapted to jet the air to a predetermined horizontal direction specific to the nozzle device 38.
• each frontal surface 48 is formed by surfaces of the group of nozzle devices 38 or by the refractory material layer 36, or by both the surfaces of the nozzle devices 38 and the refractory material layer 38. According to an example there are alternating nozzle devices 38 and sections of refractory material layer 36 in the frontal surface 48.
• a front surface of the nozzle device 38 constitutes a part of the frontal surface 48.
• the front surface is included in the mouth section of the nozzle device 38.
• the air is jetted out via an opening in the front surface.
• the group of nozzle devices 38 is embedded in the refractory material layer 36 in such a way that the air is jetted out from the nozzle device 38 to a conduit and an opening formed in the refractory material layer 36 for jetting the air through the frontal surface 48.
• the group of nozzle devices 38 is embedded in the refractory material layer 36 in such a way that a top surface of the nozzle device 38 constitutes a part of the landing 46. According to an example there are alternating nozzle devices 38 and sections of refractory material layer 36 on the landing 46. According to another example the nozzle device 38 is embedded below the surface of the landing 46.
• each landing 46 comprises a first row 381 of nozzle devices 38, a second row 382 of nozzle devices 38, a third row 383 of nozzle devices 38, and a fourth row 384 of nozzle devices 38.
• the nozzle devices 38 in each row are aligned in a row and belong to the above-mentioned group of nozzle devices 38.
• the rows are arranged horizontally in such a way that the first and second rows 381, 382 are parallel and are situated on opposite sides of the landing 46, and that the third and fourth rows 383, 384 are parallel, situated on opposite sides of the landing 46, and perpendicular to the first and second rows 381, 382.
• two or more nozzle devices 38 belonging to the plurality of nozzle devices 38 and being situated on different landings 46 are aligned in a row along a direction perpendicular to one of the rows 381, 382, 383, 384.
• each nozzle device 38 in each row 381, 382, 383, 384 is configured, directed, or oriented to jet the air in a horizontal direction perpendicular to the above-mentioned opposite row towards the opposite row along the landing 46.
• nozzle devices 38 there are eight to eighty nozzle devices 38 in the above-mentioned group of nozzle devices 38.
• each frontal surface 48 comprises four corners 58 constituting the corners of the rectangle, each corner includes at least one nozzle device 38 belonging to the above-mentioned group of nozzle devices 38 and being between two of the rows 381, 382, 383, 384 that are perpendicular to each other.
• the at least one nozzle device 38 is configured, directed, or oriented to jet the air in a horizontal direction towards the solids removal opening 42 or the one of the four corners 58 that is situated diagonally opposite.
• the at least one nozzle device 38 jets the air at an angle of 45 degrees or at an angle of 35 to 55 degrees, or at an angle of 20 to 70 degrees, in relation to the above-mentioned two rows that are perpendicular to each other.
• the grate assembly 30 further comprises on at least one side of at least one of the grate modules 40 an additional landing 52.
• the additional landing 52 is formed in the refractory material layer 36.
• the additional landing 52 forms an extension to the stepped structure of the grate module 40.
• the additional landing 52 is separated from the uppermost landing 46 of the grate module 40 by an additional frontal surface 54 between them.
• the additional landing 52 is separated from another additional landing 52 by an additional frontal surface 54 between them.
• the additional landing 52 and/or the additional frontal surface 54 follows the shape of a line, i.e. the additional landing 52 and/or the additional frontal surface 54 extends rectilinearly.
• the additional landings 52 extend horizontally.
• the additional landing 52 extends rectilinearly along one side of at least two of the grate modules 40 that are adjacent.
• the additional landing 52 comprises a group of additional nozzle devices 56 embedded in the refractory material layer 36 and are configured, directed, or oriented to jet the air through one of the additional frontal surfaces 54 and further along the above-mentioned uppermost landing 46 or the above-mentioned other additional landing 52 that is adjacent to the one additional frontal surface 54.
• the additional nozzle devices 56 are adapted to jet the air to horizontal directions.
• the landings 46 of the grate module 40 and the additional landings 52 situated on one side, on two adjacent or opposite sides, or on three adjacent sides of the grate module 40 form a grate module 40 following a rectangular shape.
• the grate module 40 follows a square shape which grate module 40 together with the additional landings 52 forms a non-square, rectangularly shaped structure.
• the additional landings 52 are to be situated between two adjacent grate modules 40.
• the additional landing 52 comprises an additional row 561 of additional nozzle devices 56.
• the additional nozzle devices 56 in the additional row are aligned in a row and belong to the above-mentioned group of additional nozzle devices 56.
• the additional row is arranged horizontally in such a way that the additional row 561 is parallel to the first and second rows 381, 382 or the third and fourth rows 383, 384.
• each additional nozzle device 56 in the additional row 561 is configured, directed, or oriented to jet the air in a horizontal direction perpendicular to and towards the above-mentioned rows that are parallel to the additional row 561.
• at least one additional nozzle device 56 at one or both ends of the additional row 561 is configured, directed, or oriented to jet the air in a horizontal direction towards the solids removal opening 42 or the one of the four corners 58 that is situated diagonally opposite, the at least one additional nozzle device 56 belonging to the above-mentioned group of additional nozzle devices 56.
• the at least one additional nozzle device 56 jets the air at an angle of 45 degrees or at an angle of 35 to 55 degrees, or at an angle of 20 to 70 degrees, in relation to the other additional nozzle devices 56 of the additional row 561.
• the fluidized bed boiler 10 includes a solids collecting and handling system for receiving the solids coming via one or more of the solids removal opening 42 and/or the solids removal conduit 44.
• the fluidized bed boiler 10 or the grate assembly further comprises one or more air plenum chambers 50.
• the air plenum chamber 50 is adapted to receive the air to be supplied via the plurality of nozzle devices 38, 56 as the fluidizing primary air.
• the air plenum chamber 50 is situated below the grate bottom wall 32.
• the conduit section of the nozzle device 38, 56 is in communication with the air plenum chamber 50.

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

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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Citations (1)

Family Cites Families (10)

• 2021
  • 2021-07-07 FI FI20215793A patent/FI130549B/en active IP Right Grant
• 2022
  • 2022-06-29 JP JP2024500437A patent/JP2024525089A/ja active Pending
  • 2022-06-29 HR HRP20251007TT patent/HRP20251007T1/hr unknown
  • 2022-06-29 US US18/569,930 patent/US20240280258A1/en active Pending
  • 2022-06-29 PL PL22735461.0T patent/PL4367439T3/pl unknown
  • 2022-06-29 WO PCT/EP2022/067819 patent/WO2023280646A1/en not_active Ceased
  • 2022-06-29 CN CN202280047702.8A patent/CN117597546A/zh active Pending
  • 2022-06-29 EP EP22735461.0A patent/EP4367439B1/en active Active

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