WO1999000626A1 - Overfeed burner for solid fuel and method of its operation - Google Patents

Overfeed burner for solid fuel and method of its operation Download PDF

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Publication number
WO1999000626A1
WO1999000626A1 PCT/SE1998/001218 SE9801218W WO9900626A1 WO 1999000626 A1 WO1999000626 A1 WO 1999000626A1 SE 9801218 W SE9801218 W SE 9801218W WO 9900626 A1 WO9900626 A1 WO 9900626A1
Authority
WO
WIPO (PCT)
Prior art keywords
burner
combustion chamber
fire grate
secondary air
duct
Prior art date
Application number
PCT/SE1998/001218
Other languages
French (fr)
Swedish (sv)
Inventor
Tore Gustafsson
Ture Marklund
Original Assignee
Tore Gustafsson
Ture Marklund
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tore Gustafsson, Ture Marklund filed Critical Tore Gustafsson
Priority to AU81358/98A priority Critical patent/AU8135898A/en
Priority to EA200000079A priority patent/EA001628B1/en
Priority to EP98931172A priority patent/EP0993582A1/en
Priority to CA002293779A priority patent/CA2293779A1/en
Publication of WO1999000626A1 publication Critical patent/WO1999000626A1/en
Priority to NO996247A priority patent/NO996247L/en

Links

Classifications

    • 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
    • F23K3/16—Over-feed arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
    • F23B1/00—Combustion apparatus using only lump fuel
    • F23B1/16—Combustion apparatus using only lump fuel the combustion apparatus being modified according to the form of grate or other fuel support
    • F23B1/24—Combustion apparatus using only lump fuel the combustion apparatus being modified according to the form of grate or other fuel support using rotating grate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
    • F23B5/00—Combustion apparatus with arrangements for burning uncombusted material from primary combustion
    • F23B5/04—Combustion apparatus with arrangements for burning uncombusted material from primary combustion in separate combustion chamber; on separate grate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23H—GRATES; CLEANING OR RAKING GRATES
    • F23H17/00—Details of grates
    • F23H17/06—Provision for vertical adjustment of grate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J1/00—Removing ash, clinker, or slag from combustion chambers
    • F23J1/06—Mechanically-operated devices, e.g. clinker pushers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L11/00—Arrangements of valves or dampers after the fire
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L9/00—Passages or apertures for delivering secondary air for completing combustion of fuel 
    • F23L9/04—Passages or apertures for delivering secondary air for completing combustion of fuel  by discharging the air beyond the fire, i.e. nearer the smoke outlet
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23M—CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR
    • F23M11/00—Safety arrangements
    • F23M11/02—Preventing emission of flames or hot gases, or admission of air, through working or charging apertures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2209/00—Specific waste
    • F23G2209/26—Biowaste
    • F23G2209/261—Woodwaste
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Definitions

  • the present invention refers to a top-feed burner according to the introduction to the claim 1.
  • the invention is a completely new design of a burner with an output adjustable all the way down to below 10% (excluding, of course, when the burner is completely shut down) of the normal output.
  • Fig. 1 shows a schematic cross- sectional view a burner according to the invention
  • Fig. 2 shows a section along line II-II in Fig. 1
  • Fig. 3 shows schematically an embodiment of a fire grate viewed in section from the side.
  • the burner according to the invention consists of a combustion chamber housing 1 surrounding a combustion chamber 2.
  • the combustion chamber 2 is circular when viewed from above and is limited at the bottom by a fire grate 3.
  • the fire grate 3 is supported by a telescopic casing 4 and driven by a axle 4 ' in the form of a splined fitting, for example, via angled gearing 5 of a motor 6 that can be operated at intervals and that simultaneously drives an ash screw 7.
  • a scraping device 8 in the form of vanes can also be arranged on axle 4 ' .
  • the fire grate 3 which in Fig, 1 is shown in its lower position, can be raised and lowered with the help of, for example, a linkage as indicated schematically with the designation 9.
  • a number of ceramic spheres 10 are loosely distributed on top of the fire grate.
  • the spheres 10 can lay in several layers on the fire grate 3, which can also support a stirrer 11.
  • an adjustable draught vent 13 In the gas outlet 12 from the circular combustion chamber, there is an adjustable draught vent 13 arranged, which by being raised or lowered respectively restricts or opens the gas outlet, which is connected to a burner duct 14.
  • the adjustable draught vent 13 is arranged so that it can be displaced to restrict the gas outlet 12 and is even equipped with one (or more) channels 15, through which even secondary air can be introduced into the gas outlet. Secondary air can even be introduced via a channel 16 (or channels) arranged over the top of the draught vent 13.
  • the high speed of gas flow in the gas outlet 12 generates turbulence and thereby a good mixing of gases in all positions of the draught vent 13.
  • Channel 15 (or channels) in draught vent 13 open at the side of the draught vent, so that when they close, the channels will be reduced due to the channels' inlet being cut-off by the draught vent's 13 outer guide 15 ' .
  • the upper channel 16 (or channels) can be restricted or closed by a draught vent 17.
  • the combustion chamber housing 1 is surrounded by an outer and an inner shell, 18 and 19 respectively. Air for combustion is drawn in between shells 18 and 19 through an opening 20 in the outer shell 18 by a blowing fan 21 and is led on further between the inner shell 19 and the combustion chamber housing 1 to the area of channels 15 and 16. The air is even led through a channel 22 to the underside of the fire grate 3 through which the air passes as primary air.
  • a scavenging air draught vent 23 with a nozzle connects the combustion chamber 2 with the combustion chamber housing scavenged with air for combustion.
  • a fuel duct 24 opens centrally above the combustion chamber 2 and is supplied with fuel such as chippings or wood pellets via a feed duct 25 from, for example, a larger store (not shown).
  • a slowly rotating geared motor 26 turns a suitably formed stirrer of steel wire 27 that extends down into the fuel duct 24.
  • the level of fuel in fuel duct ' 24 rises, the resistance to the turning of the stirrer 27 increases, which causes the motor 26 mounted on ball bearings to attempt to turn itself, against the action of a spring, against a stop bolt.
  • a shunt duct 29 connects feed duct 25 with the pressurised side of the blowing fan 21, which means that over-pressure occurs upstream in the opening of fuel duct 24 into the combustion chamber 2. This impedes smoke rising up fuel duct 24.
  • Fig. 1 designates a sealable ignition and inspection hole for the combustion chamber 2 and 31 designates a container for ash, which is fed by the ash screw 7.
  • the functions of the burner are as follows.
  • Fuel in the form of wood pellets, chippings or similar is fed through feed duct 25 and down into the vertical fuel duct 24 where the steel wire formed and suitably shaped stirrer 27 slowly rotates and prevents the fuel from fastening in the duct.
  • Fuel from fuel duct 24 fills combustion chamber 2 and, according to the rate at which the fuel is consumed in the combustion chamber, will sink down through fuel duct 24 and maintain a certain level in combustion chamber 2.
  • the fire grate 3 rotates at a suitable speed driven by the motor 6 operated at intervals and that also drives the ash screw 7 via gearing 5. The speed of motor 6 is adjusted to match the intended output from the burner.
  • a stirrer 11 arranged on the on the fire grate distributes the fuel in the combustion chamber 2.
  • the glowing bed When fire grate 3, which is perforated, for example, turns, the glowing bed provides a certain resistance and the spheres 10 currently on the fire grate and lying in a sufficiently thick layer develop an uneven movement, whereupon a slow "boiling" movement occurs that keeps the glowing bed sufficiently aerated but that which prevents blow through.
  • the ash falls through the bed of spheres and any glow remaining burns out.
  • the spheres even protect against heat radiation in a downwards direction and the heat taken up by the spheres is passed on to the primary air streaming up from below.
  • the air feed or the air of combustion is drawn in by the blowing fan 21 from the opening 20 and between the outer and inner shell, 18 and 19 respectively, to later scavenge the combustion chamber housing 1.
  • the air flows on through channel 22 as primary air in under the fire grate 3. Secondary air can be admitted at regular intervals through channels 15 and 16 into the areas for the adjustable draught vent 13 after the combustion chamber 2 but before the burner duct 14.
  • the nozzle of scavenging air draught vent 23 blows a stream of air towards the wall of the combustion chamber above the glowing bed to prevent the build-up of a coating of ash.
  • the combustion air is drawn in between the outer and inner shell, 18 and 19 respectively, the outer shell is cooled at the same time as the combustion air is preheated.
  • the combustion air is pre-heated further by it thereafter scavenging the combustion chamber housing 1.
  • Ignition of the fuel takes place through the sealable opening 30 with, for example, the help of an ignition spiral.
  • blowing fan 21 When the burner is at full output, blowing fan 21 operates with maximum rated output. By the use of the shunt duct 29, the blowing pressure can in principle be unlimited without smoke leaking out.
  • the speed of the blowing fan is first reduced, and then stops, by means of the which the burner, at a lower output of about 60%, works by self- ventilation.
  • the adjustable draught vent 13 begins to close and simultaneously restricts the channel (channels) 15 while the draught vent 17 restricts the channel (channels) 16 and the secondary air supply to the burner duct 14 diminishes. At the same time, the interval for the fire grate's motor 6 for the slow rotation of the fire grate 3 changes.
  • the fire grate 3 can even be raised and, at the lowest output, less than 10% , the scavenging air draught vent 23 closes.
  • the supply of secondary air is completely cut-off and the adjustable draught vent almost completely closed.
  • the fire grate is raised so that the glowing bed only comprises a small area under the fuel duct 24. This means that part of the primary air flows past the fire grate and the combustion of the gas begins in the combustion chamber 2.
  • draught vent 13 is shut-down to a level so that only a small hole is left, which causes all the gas to pass to the boiler pan (not shown), whereby a small concentrated hot flame occurs, which burns up any possible non-combusted gasses that pass by.
  • the temperature in the combustion chamber can be kept high, and similarly so in the entrance to the burner duct 14. Even the primary air that is drawn in through duct 22 is pre-heated to a very high degree.
  • a temperature detector (not shown) is arranged somewhat above the burner duct's 14 outlet in the boiler pan (not shown).
  • the hot gasses travel upwards as soon as they have left the burner duct 14, but at higher outputs, the gasses blow out under the temperature detector that, if the flame becomes too hot, stops the fire grate motor completely, whereupon ash quickly begins to buildup in the glowing bed and the flame diminishes.
  • Fig. 3 shows one embodiment of fire grate 3 that in this case comprises a centre section 32 plus an outer fire grate ring 33 and an inner fire grate ring 34. Ring-shaped gaps occur between rings 33, 34, and the centre section 32. The latter has a hole or perforations 35.
  • the centre section is supported by the axle 4 that rotates the section, and rings 33 and 34 are supported by three extended axles 36 that are radially symmetrical in relation to one another and that are fastened to a central axle support 37 (casing 4, for example, see Fig.
  • a groove 38 is machined in each respective axle 36.
  • Each respective groove 38 is machined off-centre in relation to the centre line of axle 36 and is done so that in each axle, the two grooves are machined with opposite off-centres.
  • Rings 33 and 34 rest against supporting edges 39 in the grooves, as is evident from the figure. If the axles 36 are turned or manoeuvred in relation to one another with 1/3 of a turn, a skewed up and down movement occurs with opposite movement between the outer ring 33 and the inner ring 34. Due to this, the glowing bed is kept in motion and ash can easily fall down between the rings.
  • the respective axles 36 are driven at the same speed via an angled gearing 40 and the inner ring 34 will turn at a greater speed than the outer ring 33. It should, of course, be understood that more than two rings 33, 34 can be used.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Solid-Fuel Combustion (AREA)

Abstract

Overfeed burner with controllable output for solid fuels, such as chips or coal, comprising a combustion chamber (2), downwardly delimited by a grate (3), a burner pipe (14) for unburned gases connected to the combustion chamber, and means for supplying primary and secondary air. Distinguishing features are that the grate (3) is horizontally rotatable and vertically movable for changing the volume of the combustion chamber (2), that a restrictable secondary air inlet (16) and a damper (13), which is equipped with a controllable secondary air inlet (15), are arranged in the passage (12) between the combustion chamber and the burner pipe, and a controllable fan (21) for feeding combustion air. A method of operation includes lowering the output by lowering the speed of the fan (21), then throttling the passage (12) between the combustion chamber and the burner pipe, reducing the supply of secondary air, reducing the rotation speed of the grate (3) and closing a damper (23) for over-fire air.

Description

Overfeed burner for solid fuel and method of its operation
The present invention refers to a top-feed burner according to the introduction to the claim 1.
The invention, as is evident from the characteristics section of claim 1 , is a completely new design of a burner with an output adjustable all the way down to below 10% (excluding, of course, when the burner is completely shut down) of the normal output.
The invention will therefore be described in greater detail in the form of examples with reference to the drawings, where Fig. 1 shows a schematic cross- sectional view a burner according to the invention, Fig. 2 shows a section along line II-II in Fig. 1 and Fig. 3 shows schematically an embodiment of a fire grate viewed in section from the side.
The burner according to the invention consists of a combustion chamber housing 1 surrounding a combustion chamber 2. The combustion chamber 2 is circular when viewed from above and is limited at the bottom by a fire grate 3. The fire grate 3 is supported by a telescopic casing 4 and driven by a axle 4 ' in the form of a splined fitting, for example, via angled gearing 5 of a motor 6 that can be operated at intervals and that simultaneously drives an ash screw 7. A scraping device 8 in the form of vanes can also be arranged on axle 4 ' . The fire grate 3 , which in Fig, 1 is shown in its lower position, can be raised and lowered with the help of, for example, a linkage as indicated schematically with the designation 9. A number of ceramic spheres 10 are loosely distributed on top of the fire grate. The spheres 10 can lay in several layers on the fire grate 3, which can also support a stirrer 11.
In the gas outlet 12 from the circular combustion chamber, there is an adjustable draught vent 13 arranged, which by being raised or lowered respectively restricts or opens the gas outlet, which is connected to a burner duct 14. The adjustable draught vent 13 is arranged so that it can be displaced to restrict the gas outlet 12 and is even equipped with one (or more) channels 15, through which even secondary air can be introduced into the gas outlet. Secondary air can even be introduced via a channel 16 (or channels) arranged over the top of the draught vent 13. The high speed of gas flow in the gas outlet 12 generates turbulence and thereby a good mixing of gases in all positions of the draught vent 13. Channel 15 (or channels) in draught vent 13 open at the side of the draught vent, so that when they close, the channels will be reduced due to the channels' inlet being cut-off by the draught vent's 13 outer guide 15 ' . The upper channel 16 (or channels) can be restricted or closed by a draught vent 17.
The combustion chamber housing 1 is surrounded by an outer and an inner shell, 18 and 19 respectively. Air for combustion is drawn in between shells 18 and 19 through an opening 20 in the outer shell 18 by a blowing fan 21 and is led on further between the inner shell 19 and the combustion chamber housing 1 to the area of channels 15 and 16. The air is even led through a channel 22 to the underside of the fire grate 3 through which the air passes as primary air. A scavenging air draught vent 23 with a nozzle connects the combustion chamber 2 with the combustion chamber housing scavenged with air for combustion. A fuel duct 24 opens centrally above the combustion chamber 2 and is supplied with fuel such as chippings or wood pellets via a feed duct 25 from, for example, a larger store (not shown). A slowly rotating geared motor 26 turns a suitably formed stirrer of steel wire 27 that extends down into the fuel duct 24. A momentum-sensing device 28, including a drive motor 26 for the stirrer, detects the load on the stirrer 27, which is intended to rotate slowly in the fuel duct 24 to prevent the fuel fastening in the fuel duct 24 and forming aggregates, which can be a problem, especially when chippings are used. When the level of fuel in fuel duct '24 rises, the resistance to the turning of the stirrer 27 increases, which causes the motor 26 mounted on ball bearings to attempt to turn itself, against the action of a spring, against a stop bolt. In contrast, when the level of fuel in the fuel duct 24 falls, the resistance to the turning of the stirrer 27 decreases, and the motor 26 is influenced by the spring to turn in the opposite direction against another stop bolt. These tendencies to movement of the motor are detected and influence a micro-switch, for example, in such a way that when the momentum of the stirrer 27 increases, the motor 26 stops, while a reduced momentum causes the motor to start. Such momentum-detecting arrangements can be executed in many different ways and are well known within the area of technology. For these reasons, they do not form part of the actual invention and will not be described in greater detail here.
A shunt duct 29 connects feed duct 25 with the pressurised side of the blowing fan 21, which means that over-pressure occurs upstream in the opening of fuel duct 24 into the combustion chamber 2. This impedes smoke rising up fuel duct 24.
In Fig. 1, 30 designates a sealable ignition and inspection hole for the combustion chamber 2 and 31 designates a container for ash, which is fed by the ash screw 7.
According to the invention, the functions of the burner are as follows.
Fuel in the form of wood pellets, chippings or similar is fed through feed duct 25 and down into the vertical fuel duct 24 where the steel wire formed and suitably shaped stirrer 27 slowly rotates and prevents the fuel from fastening in the duct. Fuel from fuel duct 24 fills combustion chamber 2 and, according to the rate at which the fuel is consumed in the combustion chamber, will sink down through fuel duct 24 and maintain a certain level in combustion chamber 2. The fire grate 3 rotates at a suitable speed driven by the motor 6 operated at intervals and that also drives the ash screw 7 via gearing 5. The speed of motor 6 is adjusted to match the intended output from the burner. A stirrer 11 arranged on the on the fire grate distributes the fuel in the combustion chamber 2. When fire grate 3, which is perforated, for example, turns, the glowing bed provides a certain resistance and the spheres 10 currently on the fire grate and lying in a sufficiently thick layer develop an uneven movement, whereupon a slow "boiling" movement occurs that keeps the glowing bed sufficiently aerated but that which prevents blow through. The ash falls through the bed of spheres and any glow remaining burns out. The spheres even protect against heat radiation in a downwards direction and the heat taken up by the spheres is passed on to the primary air streaming up from below.
The air feed or the air of combustion is drawn in by the blowing fan 21 from the opening 20 and between the outer and inner shell, 18 and 19 respectively, to later scavenge the combustion chamber housing 1. The air flows on through channel 22 as primary air in under the fire grate 3. Secondary air can be admitted at regular intervals through channels 15 and 16 into the areas for the adjustable draught vent 13 after the combustion chamber 2 but before the burner duct 14. The nozzle of scavenging air draught vent 23 blows a stream of air towards the wall of the combustion chamber above the glowing bed to prevent the build-up of a coating of ash. As the combustion air is drawn in between the outer and inner shell, 18 and 19 respectively, the outer shell is cooled at the same time as the combustion air is preheated. The combustion air is pre-heated further by it thereafter scavenging the combustion chamber housing 1.
Ignition of the fuel takes place through the sealable opening 30 with, for example, the help of an ignition spiral.
When the burner is at full output, blowing fan 21 operates with maximum rated output. By the use of the shunt duct 29, the blowing pressure can in principle be unlimited without smoke leaking out. When the output is to be reduced, the speed of the blowing fan is first reduced, and then stops, by means of the which the burner, at a lower output of about 60%, works by self- ventilation. The adjustable draught vent 13 begins to close and simultaneously restricts the channel (channels) 15 while the draught vent 17 restricts the channel (channels) 16 and the secondary air supply to the burner duct 14 diminishes. At the same time, the interval for the fire grate's motor 6 for the slow rotation of the fire grate 3 changes. At a lower output, the fire grate 3 can even be raised and, at the lowest output, less than 10% , the scavenging air draught vent 23 closes. During the lowest output, the supply of secondary air is completely cut-off and the adjustable draught vent almost completely closed. The fire grate is raised so that the glowing bed only comprises a small area under the fuel duct 24. This means that part of the primary air flows past the fire grate and the combustion of the gas begins in the combustion chamber 2. At this time, draught vent 13 is shut-down to a level so that only a small hole is left, which causes all the gas to pass to the boiler pan (not shown), whereby a small concentrated hot flame occurs, which burns up any possible non-combusted gasses that pass by. As the space in the combustion chamber 2 is now small, the temperature in the combustion chamber can be kept high, and similarly so in the entrance to the burner duct 14. Even the primary air that is drawn in through duct 22 is pre-heated to a very high degree. To maintain the minimum output without the flame going out or increasing, a temperature detector (not shown) is arranged somewhat above the burner duct's 14 outlet in the boiler pan (not shown). At this low output, the hot gasses travel upwards as soon as they have left the burner duct 14, but at higher outputs, the gasses blow out under the temperature detector that, if the flame becomes too hot, stops the fire grate motor completely, whereupon ash quickly begins to buildup in the glowing bed and the flame diminishes.
As the adjustable draught vent, which is of critical importance at low output, is responsible for restricting flow to the boiler pan, there is no risk of disturbing false draughts either in the combustion chamber or in the fuel duct 24. Fig. 3 shows one embodiment of fire grate 3 that in this case comprises a centre section 32 plus an outer fire grate ring 33 and an inner fire grate ring 34. Ring-shaped gaps occur between rings 33, 34, and the centre section 32. The latter has a hole or perforations 35. The centre section is supported by the axle 4 that rotates the section, and rings 33 and 34 are supported by three extended axles 36 that are radially symmetrical in relation to one another and that are fastened to a central axle support 37 (casing 4, for example, see Fig. 1) as shown in Fig. 3 to allow the raising and lowering of the fire grate. A groove 38 is machined in each respective axle 36. Each respective groove 38 is machined off-centre in relation to the centre line of axle 36 and is done so that in each axle, the two grooves are machined with opposite off-centres. Rings 33 and 34 rest against supporting edges 39 in the grooves, as is evident from the figure. If the axles 36 are turned or manoeuvred in relation to one another with 1/3 of a turn, a skewed up and down movement occurs with opposite movement between the outer ring 33 and the inner ring 34. Due to this, the glowing bed is kept in motion and ash can easily fall down between the rings. The respective axles 36 are driven at the same speed via an angled gearing 40 and the inner ring 34 will turn at a greater speed than the outer ring 33. It should, of course, be understood that more than two rings 33, 34 can be used.
The complete regulation of the blowing fan 21, the adjustable draught vent 16, the draught vent 17, the turning of the fire grate 3 with the help of motor 6 and the raising and lowering with the help of the slewing bracket system 9, the scavenging air vent 23 and the stirrer 27 to achieve the desired combustion sequence with different levels of output takes place with the help of commands from a controlling computer. This is neither shown nor described here since the programming only involves an optimisation of the burner's operating conditions and is not in itself an invention but can be considered to be what is now commonly applied programming and computer technology.

Claims

Claims
1. Top-feed burner for solid fuel such as chippings, coal or similar with an adjustable output where the burner includes a combustion chamber (2) limited at the bottom by a fire grate (3) that rotates in a horizontal plane, a burner duct (14) connected to the combustion chamber for the non-combusted fumes and means of supplying primary and secondary air characterised in that the fire grate (3) can be adjusted by movement in a vertical direction to decrease or increase the volume of the combustion chamber (2), that in the outlet (12) from the combustion chamber to the burner duct there is a secondary air opening (16) that can be closed, as well as an adjustable draught vent (13) equipped with an adjustable secondary air channel (15) and that a per se known blowing fan (21) that can be regulated is arranged to regulate the feed of combustion air to the burner.
2. Burner according to claim 1 characterised in that the opening of the adjustable draught vent (13) consists of one or more channels (15) arranged to be automatically restricted when the adjustable draught vent (13) restricts the outlet (12).
3. Burner according to claim lor2characterised in that a stock of loosely lying spheres (10), preferably of differing sizes and of ceramic material is arranged on top of the fire grate (3).
4. Burner according to claim 1, 2 or 3 characterised in that a scavenging air vent (23) is arranged between the blowing fan and the combustion chamber (2) in the flow path of the combustion air between the blowing fan and the combustion chamber.
5. Burner according to claim 4 characterised in that the fire grate (3), the adjustable draught vent (13), the secondary air opening (16), the scavenging air vent (23) and the blowing fan (21) are manoeuvred with the help of motor devices.
6. Burner according to any of the previous claims characterised in that the fuel is supplied to the combustion chamber from above by what is essentially a vertical fuel duct (24) opening above the fire grate (3).
7. Burner according to any of the previous claims characterised in that the fire grate (3) has the form of two or more concentric rings (33, 34) seated at a distance from one another and arranged to rotate with tipping movements of mutually displaced phases.
8. Procedure for the operation of a burner for dry fuel such as chippings or similar in regulated amounts, where the burner includes a combustion chamber (2) limited at the bottom by a rotating fire grate (3), a burner duct (14) connected to the combustion chamber (2) for the non-combusted fumes plus a blowing fan (21) for the supply of primary and secondary air to a scavenging air vent (23) opening into the combustion chamber, characterised in that to lower the output of the burner, the speed of the blowing fan (21) is reduced, after which the passage from the combustion chamber (2) to the burner tube (14) is restricted at the same time as the secondary air flow to the combustion chamber's (2) outlet is restricted and the fire grate's (3) speed of rotation is reduced and the scavenging air vent (23) closes.
9. Procedure according to claim 8 characterised in that the fire grate (3) can be moved in an upward direction.
10. Procedure according to claim 8or9characterised in that the combustion air under pressure after the blowing fan (21) is led (29) to a fuel duct (24) for the fuel arranged at the top of the burner.
11. Procedure according to any of claims 8-10 characterised in that the primary and secondary air is pre-heated by scavenging the combustion chamber (2) and the burner duct (14) within a shell (18,19) surrounding the burner.
PCT/SE1998/001218 1997-06-30 1998-06-23 Overfeed burner for solid fuel and method of its operation WO1999000626A1 (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
AU81358/98A AU8135898A (en) 1997-06-30 1998-06-23 Overfeed burner for solid fuel and method of its operation
EA200000079A EA001628B1 (en) 1997-06-30 1998-06-23 Overfeed burner for solid fuel and method of its operation
EP98931172A EP0993582A1 (en) 1997-06-30 1998-06-23 Overfeed burner for solid fuel and method of its operation
CA002293779A CA2293779A1 (en) 1997-06-30 1998-06-23 Overfeed burner for solid fuel and method of its operation
NO996247A NO996247L (en) 1997-06-30 1999-12-16 Top feed burner for solid fuel and its operation

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9702515-9 1997-06-30
SE9702515A SE520073C2 (en) 1997-06-30 1997-06-30 Top-rated burner for solid fuels and method for operating such a burner

Publications (1)

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WO1999000626A1 true WO1999000626A1 (en) 1999-01-07

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EP (1) EP0993582A1 (en)
CN (1) CN1258342A (en)
AU (1) AU8135898A (en)
CA (1) CA2293779A1 (en)
EA (1) EA001628B1 (en)
NO (1) NO996247L (en)
SE (1) SE520073C2 (en)
WO (1) WO1999000626A1 (en)

Cited By (8)

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FR2806783A1 (en) * 2000-03-23 2001-09-28 Clerc De Bussy Le Rotating hearth, for combustion of broken up wood, comprises internal grille and is installed in stove combustion chamber, hearth internal volume communicates with external atmosphere
KR100489052B1 (en) * 2001-12-24 2005-05-12 윤기철 Coke Boiler
AT503043B1 (en) * 2006-04-26 2007-07-15 Haslmayr Johann Dipl Ing KIPPROST FOR BIOMASS BOILER
EP1967791A2 (en) * 2007-03-06 2008-09-10 Oy Manacation AB Burning method and a burner for solid fuel
EP2320140A1 (en) * 2008-07-22 2011-05-11 Yazaki Corporation Method of burning wood pellet and burner
GB2551106A (en) * 2016-04-26 2017-12-13 Elliott Brian Solid fuel burner
GB2572281A (en) * 2016-04-26 2019-09-25 Elliott Brian Solid fuel burner
GB2573217A (en) * 2016-04-26 2019-10-30 Elliott Brian Solid fuel burner

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DE50204095D1 (en) * 2002-09-07 2005-10-06 Fisia Babcock Environment Gmbh Waste incineration plant with a combustion grate
SE536195C2 (en) * 2011-10-12 2013-06-18 Ecomb Ab Publ Supply device for combustion chamber and method therefore
CN105627294B (en) * 2016-03-29 2017-09-15 中南大学 Oil char particle burner
CN106287661B (en) * 2016-08-30 2018-08-17 上海交通大学 A kind of grate-firing combustion device of vertical lift
CN107228355A (en) * 2017-08-02 2017-10-03 安徽海螺集团有限责任公司 A kind of low heat value combustible combustion device and the method for fuel combustion
CN112524621B (en) * 2020-12-10 2022-09-16 西安西热控制技术有限公司 Automatic slag tapping control system and method for combustion furnace of thermal power plant

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GB640635A (en) * 1943-11-11 1950-07-26 Robert Amedee Emile Andre Rabe Improvements in or relating to installations comprising automatic furnaces
GB1459023A (en) * 1974-04-17 1976-12-22 Abernethy A W G Method and improved unit for heating using solid
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US4672899A (en) * 1984-09-17 1987-06-16 Ernst Kainer Preburning plant for burning solid fuel materials having a high ash contents

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2806783A1 (en) * 2000-03-23 2001-09-28 Clerc De Bussy Le Rotating hearth, for combustion of broken up wood, comprises internal grille and is installed in stove combustion chamber, hearth internal volume communicates with external atmosphere
KR100489052B1 (en) * 2001-12-24 2005-05-12 윤기철 Coke Boiler
AT503043B1 (en) * 2006-04-26 2007-07-15 Haslmayr Johann Dipl Ing KIPPROST FOR BIOMASS BOILER
EP1967791A2 (en) * 2007-03-06 2008-09-10 Oy Manacation AB Burning method and a burner for solid fuel
EP1967791A3 (en) * 2007-03-06 2014-02-26 Oy Manacation AB Burning method and a burner for solid fuel
EP2320140A1 (en) * 2008-07-22 2011-05-11 Yazaki Corporation Method of burning wood pellet and burner
EP2320140A4 (en) * 2008-07-22 2014-07-30 Yazaki Energy System Corp Method of burning wood pellet and burner
GB2551106A (en) * 2016-04-26 2017-12-13 Elliott Brian Solid fuel burner
GB2551106B (en) * 2016-04-26 2019-07-31 Elliott Brian Solid fuel burner
GB2572281A (en) * 2016-04-26 2019-09-25 Elliott Brian Solid fuel burner
GB2573217A (en) * 2016-04-26 2019-10-30 Elliott Brian Solid fuel burner
GB2573217B (en) * 2016-04-26 2020-04-15 Elliott Brian Solid fuel burner

Also Published As

Publication number Publication date
NO996247D0 (en) 1999-12-16
CA2293779A1 (en) 1999-01-07
EA001628B1 (en) 2001-06-25
EA200000079A1 (en) 2000-06-26
AU8135898A (en) 1999-01-19
SE520073C2 (en) 2003-05-20
EP0993582A1 (en) 2000-04-19
NO996247L (en) 1999-12-16
CN1258342A (en) 2000-06-28
SE9702515D0 (en) 1997-06-30
SE9702515L (en) 1998-12-31

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