Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
  • F23B90/00—Combustion methods not related to a particular type of apparatus
  • F23B90/04—Combustion methods not related to a particular type of apparatus including secondary combustion
  • F23B90/06—Combustion methods not related to a particular type of apparatus including secondary combustion the primary combustion being a gasification or pyrolysis in a reductive atmosphere
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
  • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
  • C10J3/02—Fixed-bed gasification of lump fuel
  • C10J3/20—Apparatus; Plants
  • C10J3/30—Fuel charging devices
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
  • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
  • C10J3/02—Fixed-bed gasification of lump fuel
  • C10J3/20—Apparatus; Plants
  • C10J3/34—Grates; Mechanical ash-removing devices
  • C10J3/36—Fixed grates
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
  • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
  • C10J3/58—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels combined with pre-distillation of the fuel
  • C10J3/60—Processes
  • C10J3/64—Processes with decomposition of the distillation products
  • C10J3/66—Processes with decomposition of the distillation products by introducing them into the gasification zone
• • 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
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
  • C10J2300/00—Details of gasification processes
  • C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
  • C10J2300/0913—Carbonaceous raw material
  • C10J2300/0916—Biomass
  • C10J2300/092—Wood, cellulose
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
  • C10J2300/00—Details of gasification processes
  • C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
  • C10J2300/0913—Carbonaceous raw material
  • C10J2300/0946—Waste, e.g. MSW, tires, glass, tar sand, peat, paper, lignite, oil shale
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
  • C10J2300/00—Details of gasification processes
  • C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
  • C10J2300/0953—Gasifying agents
  • C10J2300/0956—Air or oxygen enriched air
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
  • C10J2300/00—Details of gasification processes
  • C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
  • C10J2300/0953—Gasifying agents
  • C10J2300/0973—Water
  • C10J2300/0976—Water as steam
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
  • C10J2300/00—Details of gasification processes
  • C10J2300/12—Heating the gasifier
  • C10J2300/1253—Heating the gasifier by injecting hot gas
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
  • C10J2300/00—Details of gasification processes
  • C10J2300/18—Details of the gasification process, e.g. loops, autothermal operation
  • C10J2300/1846—Partial oxidation, i.e. injection of air or oxygen only
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
  • C10J2300/00—Details of gasification processes
  • C10J2300/18—Details of the gasification process, e.g. loops, autothermal operation
  • C10J2300/1861—Heat exchange between at least two process streams
  • C10J2300/1884—Heat exchange between at least two process streams with one stream being synthesis gas

Definitions

• the present invention applies to a procedure for burning wood fuel and other similar non-slagging biofuels like peat etc. which are contained in a fuel container. These fuels are characterized also by a low ash content and considerable production of pyrolysis gas during heating with limited supply of air already at comparatively low temperatures. The residues which are formed during the pyrolysis are also quite reactive in the final prpcesses of gasification and combustion.
• This category of fuels is potentially very attractive from an environmental point of view because of, among other things, a frequently very low sulphur content. On the contrary these fuels contain organic nitrogen which gives nitrogen oxides also at rather low temperatures of combustion when these fuels are subjected to burning.
• thermoche ical roperties which have been indicated above have, however, so far constituted a complication.
• the large production of pyrolysis gas already at low temperatures constitutes a risk for uncontrolled emissions of cancerogenic polyaromatic compounds as well as precipitation of so-called creosote or tar in the chimney.
• Chimney fires in houses with wood burners have caused considerable damage.
• a primary purpose with the present invention is to supply a procedure which permits complete and environ- mentally acceptable combustion particularly of wood, peat and lignite also on a small scale for residential heat etc. with small emissions of nitrogen oxides, cancerogenic substances and particulate matter at a small excess of air.
• a second purpose is to supply fast control of the heat ⁇ ing power within wide limits to suit the actual demand.
• a third purpose is to produce a high efficiency and a high final temperature of combustion at good fuel economy and efficient utilization of the fuel gas heat.
• fourth purpose is to achieve the above advantages and properties also in the combustion of fuel in the form of larger fuels like boiler wood or briquettes.
• the invention will also produce a number of other advan ⁇ tages which will be evident from the following description.
• the procedure according to the invention has been deve ⁇ loped particularly for biofuels like wood and peat but can also be used with other fuels like lignite, etc.
• the procedure is also particularly suited for burning of boiler wood and logs but may also be used with wood chips and other fuels in a finely divided shape. It can be dimensioned and designed in detail for the fuel preferred.
• the invention is using a new combustion technical com ⁇ bination.
• the new principle permits a new combustion process which is on one hand adapted to the special pro ⁇ perties of the fuels which has been mentioned above and which are preferred and on the other hand satisfies the requirements indicated above with respect to complete and efficient combustion.
• the Swedish patent 6251 thus describes a furnace with a fuel container and a space surrounding this container where the combustion air is pre-heated.
• the wood is sinking down in the upright fuel container towards a horizontal grid with an ash box below the grid.
• the Swedish patent 7454 describes supply of primary air to the hearth which is arranged on a vertical grid with final combustion with supply of secondary air.
• the Swedish patent 99156 describes combustion with an inverted container. Combustion is taking place in a horizontal hearth in the upper part of the fuel charge .
• the Swedish patent 99532 aims at complete combustion with secondary air by means of a furnace chamber which has a comparatively small width in relation to its length which gives the flame space the shape of a slot.
• the Swedish patent 148925 shows also how pre-heated air is supplied for final combustion in a special chamber prior to " this " flame space.
• the Swedish patent 118540 describes a gas flame outlet which is disposed in the middle part of a watercooled plane grid.
• FIG. 3 shows in principle other embodiments of furnaces for the procedure according to the invention.
• Figure 1 shows a fuel container (1) with a grate (2) and the solid fuel (3) .
• Hot flue gas with a temperature of more than 200° (4) from the flame space (5) is supp ⁇ lied to a narrow gasification zone (6) in and within the grate (2) in the grate space (7) .
• the fuel gas (8) which is formed during the gasification of the fuel flowing against the slot (9) at the upper edge of the grate (10) where it is mixed with combustion air (11) for combustion in the flame space (5) to the flue gas (12) whereby the flow (4) is recirculated whereas the remaining flue gas (13) is utilized in heat exchangers etc. prior to leaving to the chimney.
• Figure 2 shows the principle for a furnace according to the invention in a preferred embodiment.
• the fuel container (1) which may have a length of about 1 meter and a square section of about 0,2 x 0,2 meter for a small house, is ending downwards with the grid (2) which is inclined towards the horizontal plane.
• the fuel container (1) contains the fuel charge (3) , e.g. logs, which are standing on the grid (2) .
• ⁇ XJR£A fication zone (6) is discharged from the upper part of the flame space with the channel (16) containing the fan (17) and the heat exchanger (18) for reheat of the flue gas.
• the flue gas is then fed to the inlet (19) by means of a pipe system in the hottest part of the fur ⁇ nace, (this pipe system is not shown in the drawing) .
• the fuel gas thus formed is flowing up along the grid (2) towards the slot or the constriction (9) .
• the slot connects the grid space (7) with the flame space (5) .
• the hot " flue gas contains nitrogen, carbon dioxide, steam and a small quantity of oxygen.
• the oxygen con ⁇ tent is controlled by the air/fuel gas ratio in the flame space and by eventual extra supply of recirculated flue gas by the conduit (20) with the damper (21) and the fan (22) .
• Cf Sv. pat. appl. 8001801-3 A very fast pyrolysis and gasification of the fuel'is taking place in the thin zone of gasification.
• the pyro ⁇ lysis and gasification residue is oxidized by the oxy ⁇ gen in the reaction gas.
• Organic nitrogen compounds are decomposed down to nitrogen.
• the solid wood fuel is thus converted to an environmentally acceptable fuel gas.
• the fuel gas is burnt in the flame space (5) by addition of air in or next -to the slot where intense mixing is taking place.
• the area of the flame space is then in- creasing upwards which causes separation of particulate matter.
• the flame space may also contain buffles (23) so as to produce a circular gas movement. Additional air for final combustion and dilution can be added in inlets which are tangentially disposed (24) to produce a cyclone effect.
• the technical effect of the invention is of course governed by the combustion properties of the fuel gas.
• the properties of the fuel gas can not be described completely by means of analysis of fuel gas samples.
• the gas has a different composi ⁇ tion immediately after the pyrolysis and gasification reactions and may contain reactive intermediate products of different kind like ions, radicals, etc.
• the flash pyrolysis and the short residence time which is in th ' e range from about 0.1 second or below to a couple of seconds, is of great importance for the properties of the fuel gas.
• reaction pattern at the procedure according to the invention with a reaction gas for pyrolysis and gasi ⁇ fication consisting of hot recirculated flue gas, with a content of reactive intermediate products, differs completely from e.g. partial oxidation with preheated air.
• the temperature in the recirculated flue gas should be above 200°C and may preferably amount to 550 - 750 C.
• Another important circumstance is the low oxygen content in the recirculated flue gas which should not exceed about 10% and preferably be below
• a very small part of the fuel charge is in each moment taking part in the gasification process.
• the process may be described so that the fuel charge is burnt like a cigar with its glo.w towards the grate. This is caused by the remarkable feature that only the lowest part of the fuel charge is taking part in the process. Thanks to this the heating power can be rapidly changed from spare power to f ll power and vice versa.
• the combustion process is of course controlled by con ⁇ trolled supply of the reaction gas e.g. air and the re ⁇ circulated combustion gas.
• the reaction gas e.g. air
• the re ⁇ circulated combustion gas In general it is desired to work with as low excess of air as possible. It is pos- sible to operate near a stoichiometric air supply by careful adjustment of process conditions.
• FIG. 3a thus shows a horizontal gasification zone (6) whereby the grate (2) has an oblong shape so that the residence time of the fuel gas in the gasification zone is short.
• Figure 3b shows a vertical gasification zone (6) and Figure 3c a fuel con- tainer ending downwards with a double grate so as to produce two opposite gasification zones.
• the symbols in Figure 3a, b and c are the same as in Figure 1 and 2.
• the technical effects of the invention can be illustra ⁇ ted by the following example.
• the methane content of the fuel gas is a good indicator of the properties of the gas .
• Two-stage combustion can take place in a furnace according to Figure 2 - which by the way is subject to a simultaneous patent application (Sw. pat. appl. 8001801-3) - either with addition of preheated air to the gasification zone which is described in the said simultaneously filed patent application or with addition of hot recirculated flue gas.
• the recirculated flue gas has a temperature around 750°C and an oxygen content of 2% .
• Air for the partial combustion in the control experiment is preheated to 150 C.
• the invention can be used with many different fuels by modification of existing furnaces or by new design so as to adapt the furnace for conditions for the new pro ⁇ cedure. It should be no difficulty for the artisan knowing the spirit of this invention and the state of art in combustion technology to design, manufacture and use furnaces for the new procedure so as to be able to obtain the great advantages with the invention in parti ⁇ cular complete combustion of solid fuels in an environ- mentally acceptable manner. , .

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Solid-Fuel Combustion (AREA)
• Solid Fuels And Fuel-Associated Substances (AREA)
• Portable Nailing Machines And Staplers (AREA)
• Debarking, Splitting, And Disintegration Of Timber (AREA)

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• 1981
  • 1981-03-06 WO PCT/SE1981/000072 patent/WO1981002620A1/en not_active Ceased
  • 1981-03-06 EP EP81900629A patent/EP0054546A1/de not_active Withdrawn
  • 1981-11-05 NO NO813744A patent/NO813744L/no unknown

Non-Patent Citations (1)

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