EP0232249B1 - Allumage en suspension d'un combustible a base de dechets de bois ou autres materiaux tels que la biomasse ou la tourbe - Google Patents

Allumage en suspension d'un combustible a base de dechets de bois ou autres materiaux tels que la biomasse ou la tourbe Download PDF

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Publication number
EP0232249B1
EP0232249B1 EP19850903767 EP85903767A EP0232249B1 EP 0232249 B1 EP0232249 B1 EP 0232249B1 EP 19850903767 EP19850903767 EP 19850903767 EP 85903767 A EP85903767 A EP 85903767A EP 0232249 B1 EP0232249 B1 EP 0232249B1
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Prior art keywords
fuel
air
burner
particles
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EP19850903767
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German (de)
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EP0232249A4 (fr
EP0232249A1 (fr
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John Rivers
Charles David Kramer
Robert Lewis Cox
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Weyerhaeuser Co
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Weyerhaeuser Co
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23K—FEEDING FUEL TO COMBUSTION APPARATUS
    • F23K1/00—Preparation of lump or pulverulent fuel in readiness for delivery to combustion apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D1/00—Burners for combustion of pulverulent fuel
    • F23D1/02—Vortex burners, e.g. for cyclone-type combustion apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2207/00—Ignition devices associated with burner

Definitions

  • This invention deals with heat recovery from wet wood waste or other biomass material and certain fuels such as peat.
  • wood waste generated by wood processing facilities commonly called "hog fuel”.
  • Wood wastes from sawmilling and related raw wood handling operations have a number of characteristics that make efficient recovery of heating values difficult.
  • Hog fuel is generally wet, usually in excess of 50 percent by weight moisture and often in excess of the 69% moisture limit of self-sustaining combustion.
  • Each mill source of waste has its own characteristic moisture content.
  • Much sawmill and pulp mill wood waste is accumulated and stored out in the weather where it soaks up rainwater during wet periods of the year.
  • a second problem with hog fuel is that it varies greatly in size. Hog fuel wastes are generated from every wood handling and processing operation. The wastes range from sander dust of 0.1-3 mm diameter particle size to bark and log yard debris which may exceed dimensions of 200 mm in diameter and be over a meter in length.
  • US-A-4 492 171 discloses a process for burning an organic fuel by means of a solid fuel burner into which air is introduced to cause rotation of powdered fuel.
  • the fuel is to be pulverized and dehydrated to a desirable overall moisture content of approximately 20%.
  • the size of the particles is not relevant. Both powdered particles as well as pallets of about 6 mm in diameter and about 18 mm long may be used.
  • An adjustable gas nozzle is provided within the centre of the burner for burning additional fossil or other fuels (gas or oil) in order to sustain the flame.
  • US-A-433 405 discloses an improved burner for burning powdered coal. Nowhere in the publication is it shown how to size and treat powdered particles of wet organic materials other than coal for providing a self-sustaining flame without the need of burning additional fuel.
  • a state-of-the-art process that successfully accomplishes the pre-drying and burning of hog fuel is described by Spurrell in U.S. Patent No. 4,235,174.
  • a portion of the largest size material from the hog fuel pile is burned in a fluid bed burner.
  • the products of combustion from the fluid bed are then used to dry the balance of the hog fuel pile in a rotary dryer before it is fed into a combination oil-wood waste boiler.
  • the dried fuel is separated by size.
  • the coarse fraction, at about 35 percent moisture burns on a furnace grate while a fines fraction at 15 percent moisture and a particle size of less than 3.2 mm diameter is injected in air suspension into the boiler.
  • the Spurrell process requires an oil pilot on the injected fines portion of the fuel in order to sustain stable combustion.
  • the oil pilot represents a substantial use of fossil fuel, up to 30% of the total burner rating in terms of BTUs per hour at full burner loads. This usage of expensive fossil fuel is particularly unsatisfactory since it is not needed for its energy value per se but only to serve as an ignition energy source to achieve stable burning of the hog fuel material.
  • Special materials such as sander dust, however, generally constitute only a very minor portion of the hog fuel pile which accumulates at the typical lumber mill, particularly those integrated with pulp production facilities.
  • the amounts of these dry, fine wastes at most facilities are not, in general, sufficient to meet a significant percentage of the energy requirements of the typical mill.
  • the hog fuel pile as a whole has this capability.
  • Certain larger size and higher moisture ranges of wood material can be burned without oil support in refractory lined furnaces or kilns.
  • a refractory furnace the firebox is lined with ceramic which attains a temperature of roughly 800°C or higher. The hot gases then contact the steam generating tubes. The heat retained by the mass of ceramic is continually reradiated to help sustain stable combustion in the fire box, permitting otherwise difficult to burn materials or wastes to be burned without oil support.
  • Refractory furnaces have a high initial cost and the effects of high firebox temperatures result in high maintenance costs. They also normally require a larger boiler tube surface area since the tubes have poor exposure to the hottest part of the furnace.
  • Fagerlund Tappi 63(3): 35-36 (1980) further describes the Eneroth method as grinding the wood fuel down to a particle size of 1-3 mm. An oil pilot equivalent to 5% of the burner rating is required for flame control. Fagerlund expresses the hope that control systems in the future will be developed so that no auxiliary oil will be needed.
  • the present invention converts the entire hog fuel pile or any other coarse or poorly graded biomass or even peat into a fuel that burns in air suspension in a boiler without the necessity for supplemental supporting fossil fuels, hot refractories or grate burning, in contrast to the prior art.
  • the fuel preparation and method of burning the resulting fuel system can be used to fire kilns, product dryers, and particularly water wall furnaces or any other "cold" wall type of heat recovery processes.
  • a principal object of the fuel preparation method of this invention is to provide a properly dried and sized hog fuel which upon discharge from a pulverizer may be fed to an air suspension burner of the swirl stabilized type and efficiently burned therein.
  • the invention permits a steam boiler to follow varying energy process demands as effectively as with oil or pulverized coal firing.
  • the method of the invention compares substantially more favorably with firing #6 oil than coal because of wood's greater volatile content and volatility rate.
  • the ash produced is somewhat greater in amount but sulfur dioxide emissions are relatively insignificant, a major advantage in view of concerns about acid rain. NOX emissions are also less than for coal or oil which is a concern of the utilities and other boiler operators subject to environmental scrutiny and regulation.
  • a principal advantage of the invention is elimination of the oil pilot necessary to provide ignition energy to sustain stable combustion of wood wastes in water wall boilers.
  • Present commercial wood burners specify that 5-15% of the burner BTU design load must be met by oil or other conventional fossil fuel in order to maintain flame stability.
  • Another primary advantage of the invention is the elimination of the grate required by prior art boilers to burn oversize material that does not burn in suspension. All of the hog fuel may be burned in air suspension.
  • the system has an excellent capability for turning up or down to meet changing process demands. A burner turn down of at least 2.5:1 is attained.
  • the burning process and apparatus of this invention will operate similarly to a utility boiler burning pulverized lignite or oil.
  • the system of this invention permits a substantial savings in operating costs over conventional systems through substitution of cheaper wood for oil or coal. Also, elimination of the need for a grate eliminates an industry restriction on maximum size of boilers due to grate size limits. Also, boiler size may be reduced because the fuel is dried prior to firing.
  • the invention requires drying the hog fuel, which in general has an initial moisture content of 50% or more. Drying may involve mechanical or thermal processes so long as a moisture content of less than about 30% by weight results. No more than about 15-20% weight moisture content is preferred.
  • the hog fuel is then pulverized to a particle size distribution so that: (a) no particles are larger than will substantially burn within the confines of the heat recovery boiler; and (b) there is a fines portion of such particle size and in such amount that the fines portion ignites to provide sufficient ignition energy to sustain stable combustion of the entire fuel flow.
  • the upper size limit of the pulverized wood is a function of the specific boiler employed to burn the prepared fuel and the emission limitations prevalent.
  • An upper limit of 65-100% less than 1 mm has been found suitable for hog fuels burning in a boiler without a grate. Where the boiler includes a grate the upper size limitation is less strict. Most oversize in such case will just fall to the grate.
  • the characteristics of the necessary fines portion of the pulverized fuel are a function of the moisture content of the fuel and the type of burner employed in combusting the fuel in the boiler. A higher moisture content will require more time to dry, delaying ignition. A wetter hog fuel will, in such cases, have to have more fines content, if time to ignition is limiting.
  • the fuel of the invention is specifically designed for use in a swirl stabilized air suspension burner which is well known commercially, particularly for burning pulverized coal.
  • a fines portion including at least 15% by weight less than 150 ⁇ m was found suitable for the burner shown in Figure 2.
  • the fuel size distribution is a critical element of the invention. A distribution of about 100% less than 1 mm and 50% less than 150 mm is a preferred fuel specification where burner characteristics are not optimized for operation on wood.
  • the balancing of fuel moisture content, particle size distribution, and the manner in which fuel is mixed with combustion air and injected into the furnace defines a method of fuel preparation and burning which eliminates any need for supporting fossil fuel for stability.
  • Moisture content and size distribution are not independent, but may be adjusted so long as reactive fuel is produced that is adequate for the burner utilized.
  • the complete air suspension burning of the fuel permits furnace operation without the necessity of a grate and has good capability to follow boiler load demand variations.
  • the process is operable for all furnace configurations, kilns and the like, but is most particularly suitable for use with water wall furnaces and boilers, in contrast to prior art systems.
  • hog fuel from the mill pile typically at about 60% moisture content, comprising a mixture of wood ranging from sander dust through large log handling debris and bark, is fed to a drying and screening process 10.
  • the Spurrell patent is exemplary of a suitable drying process for this invention but other methods are equally suitable.
  • the Spurrell process is operated to produce a hog fuel having less than about 30% moisture content as required by the present invention.
  • Final moisture content is a function of the operation of the dryer and the average particle size of the resulting dried fuel.
  • the Spurrell process produces material ranging from about 40 mm by 100 mm chips to fines less than 3.2 mm in diameter. The moisture content of these particles may range from about 10% for the finer material up to about 30% for the larger chips.
  • the dried hog fuel is conveyed to a temporary surge storage and metering unit 11 which may be similar to a pulverized coal feeder.
  • the hog fuel is initially held in a bin 12 designed to avoid "bridging" flow interruptions.
  • the hog fuel is discharged through a column 13 onto a weighing belt means 14.
  • Column 13 is of such a length as to impose a 550 kPa explosion protection on the bin system 12. In other words, an explosion at the pulverizer would not propagate into the bin 12 because of the dimensions of the column 13.
  • the fuel is transported through line 16 to a pulverizer 15.
  • the metering system 14 in contrast to volumetric systems, provides a consistent, measured weight of hog fuel to the pulverizer, which weight of fuel may be varied over a wide range.
  • Pulverizer 15 is a high speed rotary hammer mill. A preferred machine is manufactured by Pulverizing Machinery Division of Mikropul Corp., Summit, New Jersey and is described by Duychinck, et al. in U.S. Patent 3,285,523.
  • the fuel preparation and burning methods of this invention are designed to burn the fuel in air suspension, using a swirl stabilized burner.
  • the amount of air for pulverizing, provided by a fan 17, is preferably limited to just that amount necessary to transport the fuel into the furnace ignition zone.
  • a preferred pulverizer would produce the pulverized fuel suspended in a minimal amount of air, about 0.6-2 kilograms air per kilogram of fuel, to match fuel burner needs.
  • the transport or primary air carries the fuel through a burner 18 injecting it into the boiler 20 combustion zone 21. Secondary air is introduced by blower 19 into the burner 18 along with the fuel. Boiler load or mill demand is depicted by water-filled heat transfer tubes 22 which in actual construction substantially surround the burner flame 21.
  • a key parameter of the process of the invention is the burner 18 which injects the dried pulverized hog fuel into the furnace and mixes it with air such that the fuel is substantially completely burned in suspension.
  • a swirl stabilized burner of the type used to burn pulverized coal in air suspension, was the starting point for the design of a burner suitable for burning the pulverized hog fuel.
  • FIG. 2 depicts a swirl stabilized burner 18 of the type generally suitable for use with the fuel prepared by the methods of this invention.
  • the burner 18 is installed in an aperture in the wall 23 of boiler 20.
  • An oil nozzle igniter 24 is provided for flame initiation and start-up.
  • a pipe 25 concentric about the oil pipe 24 transports dried, pulverized hog fuel and primary combustion air from the pulverizer into the boiler.
  • Primary swirler vanes 26 impart angular momentum to the fuel and primary air stream as it leaves the burner 18 and is injected into the boiler 20.
  • Secondary combustion air generated by blower 19 enters the burner 18 through an air register 27 which can vary the amount of air admitted and the degree of swirl imparted to the air.
  • Secondary swirler vanes 28 also impart angular momentum to the secondary air.
  • the ratio of the opening area between the burner fuel pipe 25 and the boiler entry wall tiles 29, commonly called “blockage”, also partly determines secondary air flow characteristics into the boiler.
  • the presence of the fines portion as an ignition energy source imparts stability to the flame.
  • the presence of the fines portion is the heart of the invention.
  • the fines portion eliminates the requirement for continual running with supplemental oil in order to obtain burner stability.
  • a preferred burner is characterized as having a high blockage ratio, i.e., the ratio of primary burner area to throat area, and low swirl.
  • high blockage is considered to be a burner area to throat area ratio of 0.5 or greater.
  • the principal goal of the combination of swirl and blockage is generation of the recirculation zone. Also, mixing of secondary air with the primary stream occurs only as fast as needed for combustion. Limiting secondary air mixing avoids adding an excessive amount of "cold" air which would delay ignition.
  • a major advantage of the process and equipment of this invention is the ability of the system to respond to varying mill stream or other heat load demands.
  • the burners of the invention may be turned down below 100% capacity.
  • the system of the invention is capable of at least a 2.5:1 turndown ratio. That is, the burner, in response to load changes, may be turned down to 100/2.5 or 40% of maximum output. Below the 2.5 turndown level the burner operation is generally unstable as the recirculation zone collapses.
  • the primary air to fuel ratio at 100% load of 0.6-2 kilograms air per kilogram of fuel or 16-32% of stoichiometric air for complete combustion is required for best combustion of the dry pulverized fuel in the boiler.
  • the ratio of air to fuel increases to 3:1. It is preferred to use the minimum amount of primary air to minimize the amount of "cold" air which must be heated with the fuel to reach ignition temperature.
  • a bin system would be interposed between the pulverizer 15 and the burner 18 to provide the required primary air/fuel ratios. This was true because all existing pulverizing designs required air to fuel ratios on the order of 3 kg air/kg fuel at high load and 8 kg air/kg fuel at low load or 50-150% of stoichiometric. Such high air to fuel ratios render a burner directly connected to such a pulverizer incapable of adequate turndown.
  • the principal critical element of this invention is the particle size distribution of the dried hog fuel fed to the burner.
  • Figure 3 shows a series of pulverized hog fuel particle size distributions, including a range of fuels that are embodiments of this invention, and three lettered prior art fuel distributions.
  • a basic conclusion established by this invention is that hog fuels must be substantially reduced in size to provide an ignition energy source in order to burn in suspension without oil support.
  • a further discovery reached through experimentation was that all the dried, pulverized wood fuels described in the prior art are too coarse to burn in a water wall or cold boiler without supporting fossil fuels.
  • curve A is the fines portion of the hog fuel produced by the drying and screening process of Spurrell, described in U.S. Patent 4,235,174. Attempts to burn this fuel in a water walled boiler without some oil fuel to support combustion were unsuccessful.
  • curve A fuel is somewhat finer than the pulverized hog fuel of Baardson described in U.S. Patent 3,831,535 as successfully burned in a refractory lined combustion chamber.
  • the Baardson fuel was characterized as having a maximum particle size of 7.9 mm in diameter igniting due to the high temperature at the wall's surface, which may be in the range between 1200-1315°C. If Baardson's fuel were plotted on Figure 3, it would fall somewhat to the left of curve A which is believed is representative of the prior art fuels. These are incapable of combustion in air suspension in a cold walled combustion chamber without supporting fossil fuel.
  • Curve B is another prior art fuel, described by Fagerland, cited above at page 4, as typical of the Eneroth (Flakt, Inc.) and ASSI fuels. This fuel also proved unstable in combustion trials as it was too coarse.
  • Curve C is a pulverized coal sample of the prior art. This is substantially finer than hog fuels.
  • Curve 1 defines the largest particle size dried, pulverized hog fuel suitable to this invention.
  • Curve 2 represents the smallest particle size fuel that would normally be used. Most fuels will fall between these limits. The preferred fuel particle size range for any given boiler can readily be determined experimentally. The fuel particle size distribution must be such that the fuel as a whole is self-igniting and thus burns in a cold walled combustion chamber. Fuels having size distributions which fall between Curves 1 and 2 are within the limits of the invention. Successful fuels must have distributions of coarse and fine portions substantially similar to Curves 1 and 2. That is, the slope of an acceptable fuel distribution must approximate those of Curves 1 and 2.
  • a top size limit of about 65-100% of less than 1 mm will ensure sufficient "burnout” or combustion in the boiler during the available residence time to meet emissions requirements.
  • the lower limit or fines portion expressed as at least 15% less than 150 urn is required to insure stable burning conditions. Fuels much finer than 85% less than 150 ⁇ m are likely to be too “dusty", increasing dust explosion hazards and otherwise requiring an excess of pulverizing power to produce.
  • Curves 3 and 4 are the size distributions of specific fuels employed in the example detailed below.
  • characteristics and operating conditions may be adjusted to burn fuels that only marginally meet the fuel specification requirements of this invention.
  • certain coarse range fuels may be more stably burned without oil support if the transporting air is heated several hundred degrees.
  • Tests indicate that while stability of a marginal fuel is improved, the effect is not large enough to allow stable combustion of "as is", i.e., coarsely pulverized fuels such as those produced by the Spurrell process fines screen on the order of 3 mm particle size.
  • Heating transport air improves burnability through (1) decreasing moisture content of the fuel particles at the burner; (2) increasing initial temperature at the fuel/air jet; and (3) allows operation at decreased primary to secondary momentum ratios.
  • Varying fuel characteristics can effect pulverizer performance. High wood to bark ratios can substantially increase power requirements.
  • Wood pulverizing requires a high impact type pulverizer in contrast with crushers typically used to pulverize coal. Grinding wood requires power usages on the order of 27.5 kW.h/t for bark and 55-90 kW.h/t for fuels having a large percentage of fiber while coal may require only 11-16.5 kW. hit. Experiments demonstrated that wood was easiest to grind when dry.
  • a key advantage of the process of this invention is the arrangement whereby the fuel is first dried to less than 30% moisture by weight and then pulverized.
  • the reverse arrangement as adopted, for example, by Eneroth and described by Fagerland, cited above, requires twice the size or number of machines to accomplish a given production rate and even more importantly four times the power, which is a critical operating expense in the pulverizing arrangements.
  • FIG. 4 shows a schematic of an operating hog fuel heat recovery process in which there is intermediate storage of dry pulverized hog fuel prior to firing into the boiler.
  • the hog fuel dried according to the Spurrell process, for example, is collected in a first storage bin 30. From bin 30 the material is mixed with air provided by blower 31 for transport in line 32 into a pulverizer 33. Make up air 34 is drawn into the pulverizer 33 by a fan 37 as needed to satisfactorily move the hog fuel through the pulverizing process.
  • the pulverized hog fuel and air discharges through a transport line 35 to a bag house dust collector 36.
  • the carrier air is discharged through fan 37.
  • the pulverized dried hog fuel drops into conveyor 40 which delivers the fuel to storage/surge bin 38.
  • Hog fuel is then fed to boiler 44 as needed by mill process heat demands.
  • Fuel as required, is combined with air 41 supplied by primary air fan 39.
  • the air-fuel mixture 42 is injected into boiler 44 through a suspension burner 45.
  • Such secondary air as is necessary for combustion is supplied by conventional boiler air system 47.
  • the system provides fuel to two burners, similar to the burner 45 shown in Figure 4.
  • the boiler is a water wall furnace wherein the heat recovery portion of the boiler comprises surrounding the combustion zone with water filled elements for capturing the heat.
  • the pulverizer was a standard Mikro-ACM TM Pulverizer, Model 200 with internal classifier manufactured by Pulverizing Machinery Division of MikroPul, U.S. Filter Corporation of Summit, New Jersey.
  • the pulverizer machine was fitted with a 225 kW motor producing air to fuel ratios of 2.8:1 at high pulverizer loads and 8.1:1 at low loads. With these air flows, the intermediate bin was necessary to obtain turndown capability of the boiler.
  • Figure 5 shows an alternative arrangement wherein high air flow pulverizer 59 discharges a fuel-air mixture 60 to a baghouse or cyclone 36'. A portion of the air stream exiting the baghouse or cyclone 36' is used as secondary air 64 for the burner 45'. Fuel discharges from bin or cyclone 36' and is entrained with air provided by the primary air fan 63.
  • a number of parallel dryers, pulverizers and burners may be needed to meet the entire load of a boiler energy recovery system.
  • one pulverizer will be required for every 100-200 million kJ per hour of hog fuel burned.

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Abstract

Procédé de préparation d'un combustible à base de déchets de bois ou autres matériaux tels que la biomasse ou la tourbe permettant une combustion et une récupération de chaleur efficaces dans une chaudière à chemise (20). Le procédé exige le séchage du combustible jusqu'à obtenir une teneur en humidité inférieure à 30%. Le combustible est ensuite pulvérisé jusqu'à obtenir une taille de particule telle que même les particules les plus grosses brûleront dans une suspension d'air dans les limites de la zone de combustion (21). De plus, l'étape de pulvérisation est régulée de sorte qu'une portion de fines du combustible est créée avec une taille telle et dans une quantité telle que la portion de fines s'allume aisément lors de l'apparition d'une flamme. Les fines produisent une énergie d'allumage suffisante pour que la totalité du combustible brûle sans avoir besoin d'un combustible fossile conventionnel comme support pilote. Le combustible est dimensionné pour brûler dans une suspension d'air par injection dans la chaudière (20) à l'aide d'un brûleur du type à tourbillonnement stabilisé (18). Pour un type de brûleur qui n'est pas particulièrement optimal pour brûler du bois, on a trouvé que la plage de la grosseur des particules appropriées est comprise entre 65-100% de particules inférieures à 1000 microns et 15-85% de particules inférieures à 150 microns. La pulvérisation est effectuée de préférence avec de faibles écoulements d'air de sorte que le mélange obtenu d'air et de combustible pulvérisé d'environ 1-2 kilogrammes d'air par kilogramme de combustible peut être directement injecté par le brûleur du type à suspension d'air à tourbillonnement stabilisé dans le four, ensemble avec de l'air secondaire (19). La combustion dans le four ne nécessite aucun combustible supplémentaire ou pilote pour maintenir la stabilité. Le procédé présente de bonnes caractéristiques de maintien de la charge avec un rapport de réduction ou abaissement de la puissance de 2,5:1.

Claims (8)

1. Procédé pour brûler un combustible organique humide dans une chaudière (20, 44, 44') à paroi remplie d'eau ou d'un autre type à froid qui comprend:
l'agencement d'au moins un brûleur stabilisé à troubillonnement (18, 45, 45') pour brûler un combustible réduit en poudre;
le séchage du combustible humide jusqu'à une teneur moyenne en humidité inférieure à 30% environ avec au moins une partie des plus fines particules ayant une teneur en humidité ne dépassant pas 20% environ;
la pulvérisation du combustible séché pour qu'au moins 60% en poids des particules soient inférieures à 1000 microns environ et qu'au moins 15% des particules soient inférieures à 150 microns environ;
le réglage de la fraction des particules inférieures à 150 microns environ dans la partie pulvérisée pour que le combustible produise une flamme auto-entretenue;
le transport des particules séchées et broyées vers le brûleur tout en étant en suspension dans un courant d'air primaire; et
l'inflammation des particules, de sorte que la fraction inférieure à 150 microns environ fournisse une énergie d'inflammation suffisante pour entretenir une combustion stable de tout le combustible.
2. Procédé selon la revendication 1, dans lequel pratiquement toutes les particules sont inférieures à 1000 microns et au moins 50% en poids sont inférieures à 150 microns environ.
3. Procédé selon la revendication 1, dans lequel l'humidité moyenne du combustible est inférieure à 20% environ.
4. Procédé selon la revendication 1, dans lequel le brûleur a un rapport de blocage élevé pour minimaliser le mélange d'air secondaire avec le courant de combustible-air primaire.
5. Procédé selon la revendication 1, dans lequel le combustible organique est composé de déchets de bois comprenant des particules de bois et d'écorce.
6. Procédé selon la revendication 1, dans lequel le combustible organique est de la tourbe.
7. Procédé selon la revendication 1 employant une proportion en poids d'air primaire par rapport au combustible de l'ordre de 1-3 kg d'air pour chaque 1 kg de combustible.
8. Procédé selon la revendication 1, dans lequel le combustible humide est d'abord tamisé avant d'être séché pour que les plus grosses particules qui sont séchées ne dépassent pas 100 mm environ dans n'importe quelle dimension.
EP19850903767 1985-07-18 1985-07-18 Allumage en suspension d'un combustible a base de dechets de bois ou autres materiaux tels que la biomasse ou la tourbe Expired EP0232249B1 (fr)

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PCT/US1985/001371 WO1987000604A1 (fr) 1985-07-18 1985-07-18 Allumage en suspension d'un combustible a base de dechets de bois ou autres materiaux tels que la biomasse ou la tourbe

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EP0232249A1 EP0232249A1 (fr) 1987-08-19
EP0232249A4 EP0232249A4 (fr) 1987-11-10
EP0232249B1 true EP0232249B1 (fr) 1989-09-27

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EP (1) EP0232249B1 (fr)
AU (1) AU574498B2 (fr)
DE (1) DE3573305D1 (fr)
FI (1) FI87834C (fr)
WO (1) WO1987000604A1 (fr)

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US6193768B1 (en) * 1994-09-27 2001-02-27 Mcx Environmental Energy Corp. Particulate waste wood fuel, method for making particulate waste wood fuel, and a method for producing energy with particulate waste wood fuel
CA2354330A1 (fr) * 2000-07-31 2002-01-31 William Shaw Combustible organique broye
GB2448547A (en) * 2007-04-21 2008-10-22 Drax Power Ltd Electrical power generation using biomass
US8006407B2 (en) * 2007-12-12 2011-08-30 Richard Anderson Drying system and method of using same

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Also Published As

Publication number Publication date
FI871138A0 (fi) 1987-03-16
AU574498B2 (en) 1988-07-07
EP0232249A4 (fr) 1987-11-10
WO1987000604A1 (fr) 1987-01-29
AU4633485A (en) 1987-02-10
FI871138A (fi) 1987-03-16
FI87834B (fi) 1992-11-13
EP0232249A1 (fr) 1987-08-19
DE3573305D1 (en) 1989-11-02
FI87834C (fi) 1993-02-25

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