Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
  • F23B30/00—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber
  • F23B30/02—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber with movable, e.g. vibratable, fuel-supporting surfaces; with fuel-supporting surfaces that have movable parts
  • F23B30/06—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber with movable, e.g. vibratable, fuel-supporting surfaces; with fuel-supporting surfaces that have movable parts with fuel-supporting surfaces that are specially adapted for advancing the fuel through the combustion zone
  • F23B30/10—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber with movable, e.g. vibratable, fuel-supporting surfaces; with fuel-supporting surfaces that have movable parts with fuel-supporting surfaces that are specially adapted for advancing the fuel through the combustion zone with fuel-supporting surfaces having fuel advancing elements that are movable, but remain essentially in the same place, e.g. with rollers or reciprocating grate bars
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23H—GRATES; CLEANING OR RAKING GRATES
  • F23H17/00—Details of 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

Definitions

• this invention relates to a grate for heaters for burning solid fuel bodies of the type that comprises a plurality of interspaced elements, at least some of which are rotatable in order to, during burning of fuel bodies on the same, set the fuel bodies in motion while tumbling the , same as the burning gradually progresses and as ashes or other residual deposits automatically fall down into a subjacent ash space via interspaces between adjacent elements, a plurality of grate elements being drivable in one and the same direction of rotation in order to convey the fuel bodies in a direction from one end of the grate towards the opposite end thereof.
• a grate that forms a bottom in the burning chamber where the fuel is burnt and gasified is usually included.
• some type of feeder device mouths on a level above the grate, e.g. a worm conveyer, which continuously or intermittently feeds out the fuel bodies so that these fall down on the grate.
• Below the grate there is a space in which ashes or other residual deposits are allowed to fall down and accumulate.
• Prior art grates for small heaters have generally been composed of solid and rigid constructions, which on one hand are able to retain the fuel bodies during the time required for burning and on the other hand allow supply of primary air from below. Perforated sheet metal plates, for instance, have been employed for this purpose. The purpose of these holes is to let through primary air to the fuel, the ashes subsequently being allowed to fall down over an edge of the sheet metal.
• Said rolls are all formed with external, cog-like projections and are arranged to interact in pairs, more precisely in such a way that the two rolls in each pair rotate in opposite direc- tions so that the projections of the same will press down and disintegrate powdered, granular or cluster-like components in the interspace between the rolls.
• This known grate is, however, associated with the disadvantage that the down-falling, fresh fuel bodies remain in the drop area without being conveyed sur- face-wise on top of the grate. The consequence of this may easily be that parts of unburnt fuel bodies still rich in energy may be disintegrated and fall down into the ash space situated below the grate.
• US 5 452 670 an installation is known to destruct car tyres by means of burning or gasification.
• This installation includes a grate-like set of rotatable rolls by means of which tyres that are fed in at one end of a surrounding housing may during burning be conveyed surface-wise on the top side of the rolls to an opposite exit end, at which resid- ual deposits may fall down onto a conveyer via the interspaces between the rolls. All rolls, with the exception of one roll situated nearest to the exit end, are rotatable in one and the same direction of rotation, whereas said last roll in the set of rolls is rotatable in a direction of rotation being opposite to the others.
• the rolls have a diameter that is approximately equal to the diameter of the tyres.
• the wedge- shapedly or V-shapedly tapering flutes between adjacent rolls become utmost deep.
• the instal- lation is intended for destruction and not for burning with the objective of extracting heat from high-energy solid fuel bodies.
• a primary object of the invention is to provide a grate that is suitable for use in small heaters and that not only facilitates the passage of the ashes down into a subjacent ash space, but also guarantees an even distribution and burning of solid fuel bodies of limited size.
• the grate should be suited for burning biomaterial pellets of the type that is fed out on the grate at one end thereof through a fuel feeder tube.
• at least the primary object is attained by means of the features defined in the characterizing clause of claim 1.
• Preferred embodiments of the invention are furthermore defined in the dependent claims 2 and 3.
• the invention also relates to a heater as such.
• the features of the heater according to the invention are defined in the independent claim 4.
• Fig. 1 is a vertical section through a heater made in accordance with the invention in which a grate according to the invention is included,
• Fig. 2 is a vertical section A-A in a 90° angle to the section in fig. 1,
• Fig. 3 is a horizontal section B-B in fig. 1,
• Fig. 4 is an enlarged detailed cut showing the grate in cross- section
• Fig. 5 is a partly cut planar view from above of the grate only together with an appurtenant driving source.
• the heater shown in the drawings comprises an outer wall 1 and a roof in the form of a removable lid 2.
• a water jacket, in its entirety designated 3 is arranged in the interior of the heater, which water jacket is composed of two concentric, cylindrical sheet-metal plates that define a rotation- ally symmetrical space 4 in which water may be present.
• the water jacket 3 is intersected by a plurality of individual tubes 5A, 5B through which flue gases may pass. More specifically, the flue gases pass in the direction upward through the tubes 5A (the ones to the left in fig. 3) and in the direction downward through the tubes 5B (the ones to th'e right in fig.
• Cooled water may be led into the water jacket via a conduit 6, while heated water is fed out through a conduit 7.
• a burning chamber 8 and under this an ash space 9 are arranged.
• the burning chamber 8 is confined by a vertical tube construction 10, as well as a grate in its entirety designated 11, which constitutes a bottom in the burning chamber 8. Said grate will be described in detail below with reference to figs. 4 and 5.
• the tube construction 10 includes an external tube 12 and an internal tube 13, in the upper part of which a plurality of small holes 14 are recessed for supply of secondary air to the burning chamber, more precisely through the gap 15 that is formed between the tubes 12, 13.
• a fireproof tube 16 is arranged, e.g., a ceramic tube.
• Primary air to the burning chamber is in a suitable way led in from the ash space 9 via the grate 11, as is outlined by the arrow C in fig. 1.
• the requisite fuel is fed into the grate through a tube 17 having an internal feed worm 18.
• This feeder tube 17 intersects the tube construction 10 and mouths at one end of the grate 11 (to the left in fig. 2) .
• the tube construction 10 together with the ceramic tube 16 are carried by a horizontal carrier 21, which at the bottom side thereof also carries the grate 11.
• the carrier 21 may advantageously consist of a plate or sheet metal plate that separates the ash space 9 from a space 22 where the flue gases turn upward. Said space 22 is accessible via a side door 23.
• An analogous side door 24 enables access to the ash space 9.
• the grate 11 is composed of a plurality of interspaced elements 25 that are rotatable.
• said grate elements are exemplified in the form of cylindrical rolls that are mounted in a common frame 26.
• the frame 26 may advantageously be quadrangular and composed of a pair of parallel side pieces 27, 28 and a pair of end pieces 29, 30, the first- mentioned one of which is situated in the proximity of the feeder tube 17. More precisely, the frame 26 is placed in such a way that the mouth of the feeder tube 17 is located somewhat inside the end piece 29 of the frame, as shown in fig. 4.
• grate elements or rolls 25 are rotatable, the same being drivable by means of a common driving source 31, e.g., an electric motor, by a transmission in its entirety designated 32.
• the rolls 25 are at one end thereof connected to bars or shanks 33 that are more slender than the rolls and carry cogwheels 34 at the free ends thereof.
• Chains or notched belts 35 are included in the transmission, which transfer power to the cogwheels from an output shaft 36 of the driving source.
• every second shank 33 is longer than the other shanks, the cogwheels 34 being arranged in two rows displaced laterally in relation to each other.
• the function of the grate according to the invention is best seen in fig. 4.
• the fuel bodies 37 e.g., in the form of cylindrical pellets (e.g. of a diameter within the range of 6-10 mm)
• the same fall down a short distance onto the rolls 25 being nearest to the end piece 29 of the frame, i.e. at an in-feeding end of the grate.
• the burning of the bodies is started, more precisely by means of the primary air that is brought in from 0 below through the grate.
• the rolls 25 are rotating, the fuel bodies will successively be conveyed in a direction towards the opposite end of the grate, i.e. in the direction of the furthest end piece 30 of the frame.
• the fuel bodies are distributed evenly along the grate while guaranteeing an even and clean process of burning.
• the choice of dimensions of the rolls 25 and the interspaces there-between, respectively, is important.
• these interspaces should have a maximum width of approx. 4 mm.
• the interspaces should not be narrower than approx. 2 mm in order to guarantee an unimpeded passage of the fine ashes. In practice a width of the interspaces of approx. 3 mm is pre ⁇ ferred.
• the diameter of the rolls should be within the range of 10-18 mm and preferably amount to 11 to 12 mm. In this way, it is guaranteed that the upwardly directed, substantially V-shaped flutes that are formed between adjacent rolls do not become so deep that they render the horizontal feed of the fuel along the top side of the grate difficult.
• the rolls 25 of the grate advantageously may be conformal and mutu ⁇ ally parallel, as is shown in the drawings. All interspaces or gaps 38 between the rolls may advantageously - though not necessarily - be equally wide.
• the grate advantageously is horizontally oriented, although it is also feasible to arrange the same at a certain limited inclination, e.g.
• the described grate may also be modified in other respects.
• the grate elements do not necessarily need to consist of rolls of a cylindrical shape.
• the grate elements may be of a polygonal, e.g. hexagonal shape, or of a cross-section shape being not circular in another way.
• projections or combs e.g. helicoidal combs with the purpose of improving the disintegration of granular residual deposits.
• the grate according to the invention is useful in other types of heaters than precisely the type being exemplified in figs. 1-3.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Solid-Fuel Combustion (AREA)
• Gasification And Melting Of Waste (AREA)
• Pre-Mixing And Non-Premixing Gas Burner (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 2001
  • 2001-11-22 SE SE0103885A patent/SE520631C2/sv not_active IP Right Cessation
• 2002
  • 2002-11-05 EP EP02775676A patent/EP1454094B1/fr not_active Expired - Lifetime
  • 2002-11-05 DE DE60220943T patent/DE60220943T2/de not_active Expired - Fee Related
  • 2002-11-05 AU AU2002341528A patent/AU2002341528A1/en not_active Abandoned
  • 2002-11-05 AT AT02775676T patent/ATE365894T1/de not_active IP Right Cessation
  • 2002-11-05 PL PL02371294A patent/PL371294A1/xx not_active IP Right Cessation
  • 2002-11-05 WO PCT/SE2002/002005 patent/WO2003044429A1/fr not_active Ceased

Non-Patent Citations (1)

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