Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS
  • C10L5/00—Solid fuels
  • C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
  • C10L5/34—Other details of the shaped fuels, e.g. briquettes
  • C10L5/36—Shape
  • C10L5/361—Briquettes
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS
  • C10L5/00—Solid fuels
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS
  • C10L5/00—Solid fuels
  • C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
  • C10L5/04—Raw material of mineral origin to be used; Pretreatment thereof
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS
  • C10L5/00—Solid fuels
  • C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
  • C10L5/34—Other details of the shaped fuels, e.g. briquettes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
  • F23G5/02—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G2201/00—Pretreatment
  • F23G2201/60—Separating
  • F23G2201/602—Separating different sizes
• • 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
  • Y02E20/12—Heat utilisation in combustion or incineration of waste

Definitions

• the invention relates to a fuel, a process to produce the fuel from coal ash and a method of burning the fuel.
• the process to produce the fuel from coal ash is based on a pneumatic separation where the coal ash is separated into at least two size fractions.
• the size fractions obtained by the process of this invention include; a major fine fraction containing lower carbon and a minor coarse fraction containing increased levels of carbon in sufficient quantity, to be used as a fuel.
• Coal ash is a very fine granular solid residue obtained as a by-product of coal ' combustion. Due to its abundance and cementitious properties, coal ash is widely used in the production of concrete. Coal ash is made up of various categories and comprises fly ash. Fly ash is a specific type * of coal ash collected from the combustion gases of coal fired heaters and coal burning power plants. Fly ash is further segregated into several groups which are classified in large part, by the coal source the fly ash is derived from.
• Cochran in US Patent 5,160,539 teaches a method and low carbon product obtained in an bubbling fluid bed produced by the introduction of air and whose operating conditions are between 1300 and 1800°F.
• the product of this invention is a useful pozzolanic material.
• US Patent 5,555,821 by Martinez discloses a stainless steel apparatus arid a process for removing unburned carbon from fly ash. The fly ash is heated from 800 to 1200 °C in a double auger where an oxygen containing gas is injected, .cooled and then finally recovered. The oxygen is said to accelerate the burning of the carbon in the fly ash and the process is said to achieve carbon levels of 0.7% in the fly ash.
• One object of this invention is to provide a process for producing a fuel from coal ash having an initial amount of carbon. This process comprising the pneumatic separation of coal ash into at least two size fractions;
• the two size fractions comprise and are separated into
• a minor coarse fraction being the fuel; and containing at least 45% of the initial carbon amount
• Another object of the invention is a fuel derived from coal ash having an initial amount of carbon.
• the fuel is produced by a pneumatic separation of the coal ash wherein the coal ash is separated into at least two fractions;
• the two size fractions comprise and a.re separated into
• Yet another object of the invention is a method of burning a fuel derived from coal ash.
• the coal ash having an initial carbon amount and the fuel being produced by, the pneumatic separation of coal ash into at least two size fractions;
• the two size fractions comprise and are separated into
• a minor coarse fraction being the fuel; and containing at least 45% of the initial carbon amount
• Fig. 1 is a process flow diagram for producing the fuel derived from coal ash with a single classifier means illustrated.
• Fig. 2 is a process flow diagram for producing fuel ⁇ derived from coal ash, where the fuel is classified and removed from the solid gas contactor.
• Fig. 3 is a process flow diagram wherein there are multiple particle size classification steps and intermediate products .
• Fig. 1 illustrates the process of the separation used to obtain the coal ash derived fuel.
• the coal ash is introduced into the process via the coal ash inlet (10) near the bottom of the circulating solid gas contactor (100) .
• the coal ash to be added to the solid gas contactor should contain at least 5% initial carbon amount (%LOI) , and preferably at least 10% initial carbon and most preferably 14% initial carbon. It must also be noted, that nearly half of the carbon initially present in the coal ash is found in the coarse fraction
• This fraction contains at least 45% (w/w) of the initial carbon, and preferably more than 50% (w/w) of the initial carbon.
• the type of solid gas contactor represented in Fig. 1 is, a fluidized bed, a circulating fluidized bed, a transport vessel or a classifying transport vessel.
• These four equipment types would usually be referred to as a fluidized bed reactor, a circulating fluidized bed reactor, a transport reactor or a classifying transport reactor, but because there is only particle classification without a reaction taking place, the word "reactor" has been either omitted or replaced with "vessel".
• the gas distributor in the solid-gas contactor may be a perforated plate, although no plate is needed if the solid gas contactor is a transport vessel or classifying transport vessel.
• the gas used as the means of separation of the coal ash is typically ambient air (20) and no particular pretreatment other than that required for the efficient operation of the blower is required.
• the coal ash may be damp with moisture
• the gas (22) may be heated to temperatures where the surface moisture is removed while the carbon content is unaffected.
• the maximum , gas temperature would be 200 °C but preferably temperatures around 150 °C are used. This heating can be accomplished through combustion of a fuel, or some other hot gas source, with the mixing of the hot gases (21) and ambient air used to attain the relatively low temperatures required. This mixing would occur near the intake of the blower (400) which would be designed to handle the higher temperatures.
• the velocity of the gas in the contactor is such, that the coal ash is elutriated almost completely in the gas.
• the blower is design to be of a sufficient size (pressure and flowrate) to perform this elutriation.
• the gas stream with the suspended coal ash particles entrained (24) leaves the contactor and enters a size classifier, which is represented in the flowsheet as one cyclone (200) but can also be a bank of multiple cyclones arranged in parallel.
• the size classifier is designed to separate the coarse fraction containing carbon from the fine fraction (28) .
• the coarse fraction leaving the bottom of the cyclone is split into two streams.
• the major portion of the stream (26) is returned to the bottom of the solid gas contactor, while the minor portion (30) is the coal ash fuel product.
• the fuel is recovered in a silo from where it can be transferred towards it eventual utilization.
• the coal ash fuel obtained is found to have a carbon content of between 40% and 60% and a thermal value between 4000 and 6000 Btu/lb. '
• Stream (26) is returned to the solid gas contactor to increase the solids loading in the contactor, which improves the efficiency of separation in the cyclone.
• the fine particle size fraction leaving the cyclone (28) is treated in a dust collector (300) where almost all of the fine fraction is collected (32) .
• the gas leaving the dust collector is typically drawn away by a fan (not shown on the diagram) and depending on the collection efficiency of the dust collector, the gases are exhausted to the atmosphere.
• Fig. 2 is very similar to Fig. 1 but represents an embodiment of- the invention where the solid gas contactor has a gas velocity that is reduced in the contactor itself by an increase in the cross sectional area of the contactor or other means.
• the lower gas velocity will be such that the coarse particles will no longer be elutriated into the classifier and can be collected.
• the vessel used is a circulating fluidized bed, or a classifying transport vessel and most preferably a toroidal (TorbedTM) vessel.
• the elutriating gas (22) can once again be optionally heated by the addition of hot gases (21) at the intake of the blower (400) .
• the elutriated portion of the dust once again enters the cyclone system (24) where two fractions are separated.
• the fine fraction (28) going towards the dust collector.
• the return coarse solid stream (26) from the classifier underflow once again serves to increase the solids loading in the contactor.
• the coarse particle stream from the cyclone (26) can be split to obtain another size fraction represented in Fig. 2 as stream (31) .
• the fuel derived from fly ash thus obtained can be transported towards a combustion system that is suitable for the combustion of fine combustible solids.
• the fuel is meant to be used in a same way as coal and in installations that include; coal fired heaters, coal fired boilers, cement kilns and a coal burning power generating stations .
• the means of transporting the fuel include pneumatic or mechanical means.
• ⁇ larger size fuel feed such as briquettes, to ensure that the fuel be burned in a safe manner.
• This agglomeration or densification step will increase the fuel value by at least 15% (becoming 4600 Btu/lb. to 6900 Btu/lb) and reduce the difficulties of handling a combustible powder.
• the TorbedTM used in the testing gave the possibility of removing various size fractions of coal ash directly from the vessel.
• the air temperature of 20 °C was measured at the inlet of the blower.
• the thermal value of the combined fraction was measured at 5372 Btu/lb, and the percentage of carbon in the final fuel product obtained is 52.1% weight percentage.
• the thermal value of the coal ash fuel obtained places it in the range typically considered that of lignite coal which is between 4000 and 8300 Btu/lb.

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• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Geology (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Solid Fuels And Fuel-Associated Substances (AREA)
• Fluidized-Bed Combustion And Resonant Combustion (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 2002
  • 2002-12-16 US US10/320,069 patent/US20040111958A1/en not_active Abandoned
• 2003
  • 2003-12-15 EP EP03767353A patent/EP1572843A2/de not_active Withdrawn
  • 2003-12-15 WO PCT/CA2003/001932 patent/WO2004055139A1/en not_active Ceased
  • 2003-12-15 CA CA002509352A patent/CA2509352A1/en not_active Abandoned
  • 2003-12-15 AU AU2003291895A patent/AU2003291895A1/en not_active Abandoned

Non-Patent Citations (1)

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