US20160304800A1 - Torrefaction Process - Google Patents
Torrefaction Process Download PDFInfo
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- US20160304800A1 US20160304800A1 US14/783,782 US201414783782A US2016304800A1 US 20160304800 A1 US20160304800 A1 US 20160304800A1 US 201414783782 A US201414783782 A US 201414783782A US 2016304800 A1 US2016304800 A1 US 2016304800A1
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L9/00—Treating solid fuels to improve their combustion
- C10L9/08—Treating solid fuels to improve their combustion by heat treatments, e.g. calcining
- C10L9/083—Torrefaction
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L5/00—Solid fuels
- C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
- C10L5/06—Methods of shaping, e.g. pelletizing or briquetting
- C10L5/10—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L5/00—Solid fuels
- C10L5/40—Solid fuels essentially based on materials of non-mineral origin
- C10L5/44—Solid fuels essentially based on materials of non-mineral origin on vegetable substances
- C10L5/442—Wood or forestry waste
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L5/00—Solid fuels
- C10L5/40—Solid fuels essentially based on materials of non-mineral origin
- C10L5/44—Solid fuels essentially based on materials of non-mineral origin on vegetable substances
- C10L5/445—Agricultural waste, e.g. corn crops, grass clippings, nut shells or oil pressing residues
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L5/00—Solid fuels
- C10L5/40—Solid fuels essentially based on materials of non-mineral origin
- C10L5/44—Solid fuels essentially based on materials of non-mineral origin on vegetable substances
- C10L5/447—Carbonized vegetable substances, e.g. charcoal, or produced by hydrothermal carbonization of biomass
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
- C10L2290/02—Combustion or pyrolysis
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
- C10L2290/06—Heat exchange, direct or indirect
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
- C10L2290/08—Drying or removing water
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
- C10L2290/30—Pressing, compressing or compacting
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
- C10L2290/48—Expanders, e.g. throttles or flash tanks
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
- C10L2290/58—Control or regulation of the fuel preparation of upgrading process
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
- C10L2290/60—Measuring or analysing fractions, components or impurities or process conditions during preparation or upgrading of a fuel
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L5/00—Solid fuels
- C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
- C10L5/06—Methods of shaping, e.g. pelletizing or briquetting
- C10L5/10—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders
- C10L5/14—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders with organic binders
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L5/00—Solid fuels
- C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
- C10L5/06—Methods of shaping, e.g. pelletizing or briquetting
- C10L5/10—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders
- C10L5/14—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders with organic binders
- C10L5/143—Methods of shaping, e.g. pelletizing or briquetting with the aid of binders, e.g. pretreated binders with organic binders with lignin-containing products
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- 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, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- 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
- C10L5/363—Pellets or granulates
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B2200/00—Drying processes and machines for solid materials characterised by the specific requirements of the drying good
- F26B2200/02—Biomass, e.g. waste vegetative matter, straw
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- 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
- Y02E50/00—Technologies for the production of fuel of non-fossil origin
- Y02E50/10—Biofuels, e.g. bio-diesel
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- 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
- Y02E50/00—Technologies for the production of fuel of non-fossil origin
- Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel
Abstract
A process for producing compacted torrefied biomass from pre-processed biomass. The process includes drying the pre-processed biomass in a dryer with heater exhaust gas from a heater, yielding dried biomass; torrefying the dried biomass with heat generated by the heater; compacting and pre-cooling the torrefied biomass in a cooling compactor and further cooling the compacted torrefied biomass in a cooling tunnel, yielding the compacted torrefied biomass.
Description
- The present application relates to torrefaction of pre-processed biomass such as wood chips or wood particles for the production of feedstock for biofuels and the production of fuel feedstock for a power plant.
- Torrefaction, also referred to as torrification, retification or mild pyrolysis, is a process used for the treatment of biomass which changes the chemical and physical structure of the biomass. Torrefaction usually involves heating the biomass in a torrefaction reactor to a predetermined temperature for a predetermined length of time. A heater can be used to provide thermal energy to the torrefaction reactor.
- Torrefaction of pre-processed biomass can be used to produce fuel. The torrefied biomass can replace coal, or can be co-fired with coal. The torrefied biomass can also be used as a feedstock for the production of biofuels, such as syngas, bio-oils, torrefied wood pellets or briquettes.
- The moisture content in wet basis (WB) (i.e. the weight percentage of water in the wet material) of pre-processed biomass is usually used to determine the market value of the biomass as feedstock because higher moisture content reduces capacity and increases energy costs of torrefaction. Fresh wood in a forest has a moisture content (MC) of about 50%. If the wood is allowed to dry in the forest, for example if dead wood is harvested, the moisture content is about 35% or lower.
- Pre-processed biomass can have a moisture content and density that results in a net calorific value (e.g. GJ/tonne) which makes the pre-processed biomass an economically undesirable alternative to coal or other fossil fuels. Net calorific value is also referred to as “lower heating value” (LHV). For example, pre-processed wood chips can have a moisture content of 30-70 wt % and a density of 250 to 450 kg/m3. As a result, pre-processed wood chips of the trunk wood with bark of a pine tree can have a net calorific value of 6.2 GJ/tonne at 60% moisture. In contrast, coal can have a net calorific value between 15 and 27 GJ/tonne, while wood chips of trunk wood with bark of a pine tree that has been dried to 0% moisture can have a net calorific value of 19.3 GJ/tonne.
- In an example of a torrefaction process, torrefaction of wood at a temperature of 180−220° C. results in wood which is hydrophobic and resistant to microbial growth and decomposition. This temperature range may be used to improve the qualifications and color of solid lumber and the resulting product is sometimes referred to as ThermoWood. Torrefaction of wood particles or wood chips at a higher temperature, such as 260° C., results in wood particles or wood chips which have about 70% of their original mass, are brittle, hydrophobic, and which have a 15-25% greater net calorific value than wood on dry basis. Torrefaction of wood chips or wood particles at a temperature between 200 and 300° C. for 15-30 minutes can result in processed wood chips or wood particles with fuel properties comparable to coal. Such torrefied biomass is also referred to as BioCoal. Torrefied biomass can have a net calorific value over 23 GJ/tonne.
- Torrefied biomass coming out of torrefaction reactor is usually at a high temperature and low density and is typically dusty without further processing. If the material is released into oxygen rich atmosphere it can catch fire due to self ignition. Torrefied biomass is therefore usually cooled and compacted to ease further handling and to reduce dust content.
- In a first aspect, the present application provides a process for producing compacted torrefied biomass from pre-processed biomass, the process includes: drying the pre-processed biomass in a dryer with heater exhaust gas from a heater, yielding dried biomass; torrefying dried biomass with the heat coming from heater and pre-cooling and compacting torrefied biomass in a torrefaction processor, yielding pre-cooled compacted torrefied biomass; and further cooling torrefied biomass, yielding compacted torrefied biomass. Drying the pre-processed biomass can include pre-drying the pre-processed biomass in a pre-dryer with the exhaust gas from the dryer. Pre-drying the pre-processed biomass with the exhaust gas from the dryer can filter dust fines from the exhaust gas from the dryer, condense volatile organic compounds from the exhaust gas from the dryer, or both filter dust fines and condense volatile organic compounds from the exhaust gas from the dryer.
- Drying the pre-processed biomass can include flash drying the pre-processed biomass in a flash dryer with the heater exhaust gas. The exhaust gas from the flash dryer can be used for pre-drying the pre-processed biomass in a belt dryer prior to flash drying. Pre-drying the pre-processed biomass with the exhaust gas from the flash dryer can filter dust fines from the exhaust gas from the flash fryer, condense volatile organic compounds from the exhaust gas from the flash dryer, or both filter dust fines and condense volatile organic compounds from the exhaust gas from the flash dryer.
- The heater can be a combustion heater, torrefying the dried biomass can yield syngas, and the syngas can be used as a fuel in the combustion heater. Natural gas and/or syngas can be used as fuels in the combustion heater.
- Torrefying the dried biomass in a torrefaction processor can include heating the dried biomass to temperature between 220 and 280° C. for between 15 and 30 minutes in a low-oxygen environment.
- The torrefaction processor can include processing torrefied biomass into pre-cooled compacted torrefied biomass in a cooling compactor directly connected to the torrefaction reactor maintaining the low-oxygen environment through the process.
- The heater can include a burner, where the burner generates combustion gases, and dilution air is added to the combustion gases to yield the heater exhaust gas.
- The heat generated by the heater can be delivered to the torrefaction reactor by a thermal transfer fluid.
- The pre-processed biomass can be any suitable biomass such as, for example, agricultural waste, wood or woody biomass. The woody biomass can be any suitable material such as, for example, wood or wood waste. The process includes processing the wood or wood waste into wood chips or hog fuel, and sizing the wood chips or hog fuel into wood particles.
- The process can be a continuous process and operating parameters of the process can be determined based on measurements obtained from at least one gauge in the process. The process can be automatically controlled with Programmable Logic Control.
- The heater exhaust gas and the dryer exhaust gas can be in fluid communication and can be moved using a fan and a booster fan.
- A process for producing compacted torrefied biomass from pre-processed biomass, the process including: pre-drying the pre-processed biomass in a belt pre-dryer with exhaust gas from a flash dryer, yielding pre-dried biomass; flash drying the pre-dried biomass in a flash dryer with heater exhaust gas from a heater, yielding flash dried biomass; torrefying the flash dried biomass in a torrefaction reactor with heat generated by the heater, yielding torrefied biomass; and pre-cooling and compacting the torrefied biomass in a cooling compactor, yielding the pre-cooled torrefied biomass and further cooling the pre-cooled torrefied biomass in a cooling tunnel; yielding compacted torrefied biomass.
- This summary does not necessarily describe all features or aspects of the invention. Other aspects and features will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the application in conjunction with the accompanying figures.
- Embodiments of the present application will now be described, by way of example only, with reference to the attached figures, wherein:
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FIG. 1 is a simplified flow diagram illustrating a process to torrefy pre-processed biomass according to an embodiment of the present application; -
FIG. 2 is a flow diagram illustrating a process to torrefy pre-processed wood particles according to a specific embodiment of the process illustrated inFIG. 1 ; and -
FIG. 3 is a flow diagram depicting an example of the process illustrated inFIG. 2 . - The present application provides a process of torrefaction of pre-processed particles of biomass. The biomass can be any suitable such as agricultural waste (e.g. straw or bagasse) woody biomass, or the like. Examples of woody biomass include wood chips, hogfuel, pre-processed wood waste, and the like. Woody biomass can be sized into wood particles. Wood waste can include urban wood waste from demolitions or renovations, process waste from sawmills or pulp mills, or waste from harvesting trees, such as tree branches. Wood chips can be produced using a wood chipper, which takes wood logs and chips the logs into the wood chips. Hog fuel can be produced using a “hog” or a “crusher”, which takes woody biomass, such as bark or wood waste, and produces chips of bark and wood fiber. Wood particles can be produced by taking a woody biomass, such as wood chips or hog fuel, and breaking the woody biomass into wood particles.
- The process equipment can be located near a utility power plant and used as a fuel refining process, where the utility power plant co-burns BioCoal with fossil coal using existing equipment. The process equipment can be located near a source of pre-processed biomass and compacted torrefied biomass can be more economically shipped by train or truck than the pre-processed biomass due to the higher net caloric value, higher density and low moisture content of the compacted torrefied biomass. The higher net calorific value, higher density, low moisture content and hydrophobic nature of material supports the more economically-viable storing and handling of the compacted torrefied biomass.
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FIG. 1 shows a simplified flow diagram illustrating a process according to the present application. Pre-processed biomass 101 is dried in a two-stage dryer 104, generating dried biomass. The second stage of thedryer 104, themain dryer 103, is heated using aheater exhaust gas 106 from aheater 108. Theheater exhaust gas 106 entering themain dryer 103 is exhausted from themain dryer 103 as adryer exhaust gas 110. The dryer exhaust gas heats a pre-dryer 102 and is released into atmosphere asvent gas 130. The dried biomass is torrefied in atorrefaction processor 105 using heat generated by theheater 108. Theheater 108 provides the heat to thetorrefaction reactor 112 using aheat transfer fluid 114. Theheat transfer fluid 114 can be thermal oil. Theheater 108 is fueled using asyngas 116, produced by thetorrefaction reactor 112 and by supportingfuel 118. The supportingfuel 118 andsyngas 116 are combusted using oxygen fromatmospheric air 120. - The pre-cooled torrefied biomass is produced by the
torrefaction processor 105 consisting of thetorrefaction reactor 112 and the coolingcompactor 122.FIG. 2 shows a flow diagram that illustrates a process according to a specific embodiment of the process illustrated inFIG. 1 . While the description of the flow diagram shown inFIG. 2 refers towood particles 202, other biofuels can also be used. - In one example of the embodiment illustrated in
FIG. 2 , the process takes 11 tonnes per hour of wood particles that have a moisture content of 35 wt % (WB), and produces 5.0 tonnes per hour of BioCoal that has a moisture content of 2.8 wt % (WB). - Sand, grit and metal are removed from the
wood particles 202. Thewood particles 202 are stored in a pile or in storage bins or in silos until they are used in the process illustrated inFIG. 2 . Thewood particles 202 are fed on a conveyor leading into thedryer 104 using a feeder, such as a reclaimer. - Smaller wood particles facilitate drying and torrefaction. However, size reduction creates dust and fine particles (fines), and more power is utilized to make smaller particles, thus adding to process material loss and cost. Small amount of moisture is evaporated during sizing. Optimum size of wood particles may require screening and depends on a number of variables, such as the species of wood, the moisture content of the material, and the equipment available for sizing (e.g. hammer mills, knife grinder or rotary hogs). In the present example, the
wood particles 202 are size reduced to particle size less than 6 mm, with moisture content of 34.7 wt % (WB) after sizing. - Wood particles can have a moisture content between 20% and 65% (WB) and can be dried to a moisture content between 6 and 20 wt %. In the present example, the
wood particles 202 have a moisture content of 34.7 wt % moisture and are dried to a moisture content of 8.2 wt % moisture. Thewood particles 202 are dried in thedryer 104, which includes abelt dryer 204 and aflash dryer 206. Alternatively, theflash dryer 206 can be a rotary dryer which allows longer drying time for the wood particles. A flash dryer and a rotary dryer are air dryers that use hot gas and separate the dried wood particles with a cyclone. - The
wood particles 202 are conveyed, for example, on a conveying wire mesh belt through thebelt dryer 204 as a mat having a material thickness from 10 to 30 cm. The mat is leveled, for example, with a leveling screw at an infeed of thebelt dryer 204. The mat is moved through thebelt dryer 204 and thewood particles 202 are heated by theexhaust gas 110 from theflash dryer 206. The dryer belt speed can be varied, based on the moisture content of the material, to adjust the residence time of the wood particles in thebelt dryer 204. The residence time can be between, for example, 10 and 60 minutes, and is varied to result in pre-dried wood particles having a moisture content of less than 50%. Thehot exhaust gas 110 can be distributed into thebelt dryer 204 through a manifold on top of the conveying mesh belt. Thehot exhaust gas 110 penetrates through the mat of thewood particles 202 and the conveying mesh belt. Thehot exhaust gas 110 heats thewood particles 202 and removes moisture from thewood particles 202, resulting in the pre-dried wood particles. The pre-dried wood particles are collected from the conveying belt at an outfeed of thebelt dryer 204 using, for example, a conveying screw, chain or belt. - The mat of wood particles filters dust and condenses volatile organic compounds (VOCs) present in the
hot exhaust gas 110. Thehot exhaust gas 110, which has been filtered by the mat, is collected with a fan from under the conveying belt and is vented as thevent gas 130 into the atmosphere through a stack. Thevent gas 130 temperature is kept above the dew point to prevent moisture from condensing inside the dryer. - The
hot exhaust gas 110 can be between 100 and 230° C. Thevent gas 130 can be between 60 and 130° C. The pre-dried wood particles can be between 50 and 110° C. and can have moisture content between 15 and 50 wt % (WB). In the present example, thehot exhaust gas 110 is at a temperature of 178° C.; thevent gas 130 is at a temperature of 102° C.; and the pre-dried wood particles are at a temperature of 60° C. and have a moisture content of 27% (WB). - Flash drying, also known as flash tube drying, is a method of removing surface water from a material in an enclosed ducting, where escape of dust and VOCs is reduced. To flash dry the pre-dried wood particles at 206, the pre-dried wood particles are fed from the pre-dryer 204 into a flash drying duct of the
flash dryer 206 through a rotary feeder, where the pre-dried wood particles are transported airborne in theheater exhaust gas 106 from theheater 108. Theheater exhaust gas 106 evaporates surface water on the wood particles and is exhausted from theflash dryer 206 as theexhaust gas 110. The wood particles are separated from theexhaust gas 110 using a flash dryer cyclone and airlock at the end of the dryer ducting. Theexhaust gas 110 from the flash dryer cyclone of theflash dryer 206 has a higher moisture content (e.g. vol water vapor/vol air) than theheater exhaust gas 106 from theheater 108. Theexhaust gas 110 is blown by a dryer fan into a manifold distributing air on top of the belt of the pre-dryer 204. - The dried wood particles can be between 50 and 100° C. and can have a moisture content between 6 and 20% (WB). The
heater exhaust gas 106 can be between 220 and 350° C. and can include water vapor between 0.5 and 5% vol water vapor/vol air. Thedryer exhaust gas 110 can be between 120 and 220° C. and can include water vapor between 3 and 8% vol water vapor/vol air. - In the present example, the dried wood particles are at a temperature of 70° C. and have a moisture content of 8.2%; the
heater exhaust gas 106 is at a temperature of 300° C. and includes 2.2% vol water vapor/vol air. Thedryer exhaust gas 110 is at a temperature of 178° C., is pumped at a rate of 53,800 am3/h, and includes 5.2% vol water vapor/vol air. - The flash dried wood particles from the
flash dryer 206 are fed into thetorrefaction reactor 112 with, for example, a screw conveyor and a rotary or dual-gate airlock. The airlock can reduce excess oxygen in the reactor. The flash dried wood particles are heated to a predetermined temperature for a predetermined length of time, yielding torrefied wood particles. The temperature can be between 180 and 330° C., and the time period can be, for example, 15, 30, 60, 120, or 240 minutes. In industrial applications, in order to reduce costs, wood particles can be torrefied at a temperature between 220 and 280° C. so that the torrefaction process takes between 15 and 30 minutes. - During the torrefaction process, the wood particles are dried and heated under reduced oxygen levels, changing the physical and chemical properties of the wood particles. The torrefaction process can affect the hemicelluloses and evaporate condensable and non-condensable gases with low calorific value, thereby increasing the calorific value of the remaining material. The torrefied wood particles can have a darker color, higher carbon concentration and higher calorific value than the un-torrefied, dried wood particles. The torrefied wood particles are more hydrophobic and lose fiber structure, making them more easily pulverized by grinders. The torrefied wood particles can lose about 25 to 40% of mass and about 10% of energy content in comparison to pre-processed wood on dry basis.
- In the present example, the wood particles are heated to a temperature of 260° C. for 25 minutes, resulting in torrefied wood particles that have a moisture content of 2.8 wt % (WB) and a calorific value of 23.4 GJ/tonne.
- The evaporated gases (e.g. the syngas 116) can be burned as fuel in a
burner 208, along with thesupport fuel 118. Thesupport fuel 118 can be natural gas, propane, heating oil, or any other fuel that can support combustion of thesyngas 116. Theburner 208 mixes thesyngas 116, thesupport fuel 118 and theair 120, ignites the resulting mixture and generates a flame which yieldsheat 210 and theheater exhaust gas 106. Theburner 208 can be connected to a refractory-lined combustion chamber 212 to allow additional combustion of anyunignited syngas 116. Alternatively, theburner 208 can be connected directly to aheat exchanger 214 of theheater 108. Theheater exhaust gas 106 is used in theflash dryer 206, as described above. Thesyngas 116 can be produced at a rate between 120 to 400 kg of syngas per tonne of wood particles on dry basis depending on wood species, torrefaction temperature and residence time in the torrefaction reactor. In the present example, thesyngas 116 is produced at a rate of 2,283 kg syngas per 11 tonnes of wood particles at 35% moisture (WB), or at a rate of 320 kg syngas per tonne of wood particles on dry basis. - The
heat 210 generated in theburner 208 is used to heat theheat transfer fluid 114 in aheat exchanger 214. Thetorrefaction reactor 112 is heated indirectly using theheat transfer fluid 114 in order to provide accurate temperature control to thetorrefaction reactor 112. Accurate temperatures in thetorrefaction reactor 112 controls torrefaction results and can reduce mass loss of the wood particles. Thetorrefaction reactor 112 can include a commercially available screw, disk wheel or paddle-type dryer adapted to the torrefaction process. In such dryers, the wood particles are convection heated by direct contact with heated rotating elements that move the material through thetorrefaction reactor 112 at a predetermined rate, resulting in a predetermined residence time. The torrefied wood particles are released into the coolingcompactor 122. - The reactor casing is sealed and evaporated water vapor and
syngas 116 are removed from the casing and piped into theburner 208. - The torrefied wood particles can be compacted with a cooling
compactor 122 connected directly to the outlet of thetorrefaction reactor 112 thus maintaining the low oxygen environment of thetorrefaction reactor 112. The coolingcompactor 122 compacts the torrefied wood particles at an elevated temperature while the torrefied wood particles are plastic and can be bond together with the lignin forming part of the torrefied wood particles. If necessary other starch-based, lignin-based, or polymer based liquid binder can be pumped into cooling compactor to improve bonding and to reduce dust formation. The cooling compactor can be, for example, a screw compactor, where the compacting screw is water cooled with coolingwater 215 to pre-cool thetorrefied wood particles 215 to a temperature lower than self ignition temperature. The cooling compactor releases the pre-cooled compactedwood particles 216 in form of nuggets having density of 400 to 700 kg/m3 and temperature 100 to 180° C. - The pre-cooled
torrefied wood particles 216 can be cooled to a lower temperature and the heat can be recovered from a coolingtunnel 220, yielding compactedtorrefied wood particles 218. The pre-cooledcompacted wood particles 216 are conveyed through a cooling tunnel where material is exposed to coolingair 217. The cooling tunnel can pre-heats thedilution air 218. Pre-heating of thedilution air 218 leads to energy savings in theheater 108. - The pre-cooled compacted
torrefied particles 216 or compactedtorrefied wood particles 218 can be further processed into pellets or briquettes in a separate process to increase the density of the material. - The
heater 108 is used to generate the thermal energy utilized for thetorrefaction reactor 112 and thedryer 104. Theheater 108 includes theburner 208, the combustion chamber 212 and theheat exchanger 214. Alternatively, theburner 208 can be directly connected to theheat exchanger 214. Theburner 208 accepts a fuel and combusts the fuel using oxygen from theair 120. Theburner 208 can burn natural gas, propane or heating oil, thesyngas 116 produced in thetorrefaction reactor 112, another appropriate fuel such as wood fines, or a combination thereof. - In the specific embodiment illustrated in
FIG. 2 , theheater 108 uses syngas 116 produced from thetorrefaction reactor 112 as a main fuel source, with natural gas as a flame carrier to sustain the combustion. Because thesyngas 116 includes water vapor produced in the torrefaction process, the water vapor is also heated during combustion. Predetermined combustion parameters are used to provide appropriate retention time of the fuel for desired combustion levels. Theatmospheric air 120 can be added at a rate between 600 and 1100 m3/h for each megawatt (MW) heat created by burner. The natural gas can be added at a rate between 1 and 40% of syngas depending on wood species and the moisture content of the wood particles. - In the present example, the
burner 208 creates 4.75 MW heat, theair 120 is added at a rate of 5173 m3/h, and 67 kg of natural gas is used per 2,283 kg of syngas (i.e. 2.9 wt % natural gas). -
Dilution air 218 is blown into an inlet of theheat exchanger 214 and mixed with the hot gases from the combustion chamber 212. Alternatively,dilution air 218 can be blown into a mixing box following theheat exchanger 214. Thedilution air 218 adds to the drying capacity of theheater exhaust gas 106. The hot gases from theburner 208 are used in theheat exchanger 214 to heat theheat transfer fluid 114 that is circulated through the heated rotating elements in thetorrefaction reactor 112, as described above. Theheat exchanger 214 is sized to provide theheat transfer fluid 114 to thetorrefaction reactor 112 at a suitable temperature and flow rate. Theheater exhaust gas 106 exhausted from theheat exchanger 214 is used to dry the wood particles in theflash dryer 104, as described above. Exhaust gas ducting from theheat exchanger 214 is connected to a material infeed point of theflash dryer 206 and provides theheater exhaust gas 106 to theflash dryer 206. - The
heat transfer fluid 114 can be pumped at a rate between 800 and 900 kg/min for each MW heat used for material drying and torrefaction in thetorrefaction reactor 112. Thedilution air 218 can be added at a rate between 6800 and 13600 m3/h for each MW net heat used for thedryer 104. In the present example, thetorrefaction reactor 112 consumes 1.08 MW heat and theheat transfer fluid 114 is pumped at a rate of about 900 kg/minute, or 1.4 m3/min. Thedryer 104 consumes 2.85 MW heat. Thedilution air 218 is added at a rate of 30700 m3/h while a portion of the heat is transferred with combustion gases and water vapor from theburner 208. Certain part ofheat 210 is covering process and stack losses. - Because the
heater 108 of the present example uses thesyngas 116 produced in thetorrefaction reactor 112 as the main fuel source, and because the torrefaction process of the present example uses wood particles, the cooledtorrefied wood particles 216 are nearly CO2 neutral. For each kWh produced in a power plant, the CO2 emissions of the cooledtorrefied wood particles 216 can be about 1.5% of the CO2 emissions of fossil coal. - Because the heating gases (106, 110, 130) are propelled along a continuous, enclosed flow path, once the gases are flowing at the desired flow rate, booster fans with reduced electric power requirements can be utilized to overcome system resistance and maintain the flow rate. The desired flow rate can be set based on the flow rate of the
dilution air 218 resultingheater exhaust gas 106. Booster fans can be positioned afterexhaust gas 110 leaving theflash dryer 206 and after the pre-dryer 204. Booster fans can additionally be utilized to adjust the flow rate in a particular process step. The flow rate could be adjusted to account for the thermal expansion of a gas in the particular process step. - Additionally, because the gases are in a closed system and the
exhaust gas 110 is filtered using the mat of wood particles in the pre-dryer 204, the amount of dust and volatile gases escaping into the atmosphere can be limited. Filtering theexhaust gas 110 using the mat of wood particles in the pre-dryer 204 can result in an process where thevent gas 130 from the pre-dryer 204 is not further cleaned with an air cleaning device, such as with a cyclone, or a baghouse, or a wet scrubber, or a wet electrostatic precipitator, or a combination thereof. - By utilizing one or more of: (a) efficient heat transfer in the
torrefaction reactor 112, (b) syngas 116 as the main fuel, (c) efficient drying system, (d) thermal energy recovery, and (e) closed gas flow through the system, the thermal energy efficiency of the process is improved and use of thesupport fuel 118 is reduced. - For example, in the process illustrated in
FIG. 2 , the combustion chamber 212 operates at a temperature which allows clean burning of thesyngas 116. Theheat exchanger 214 heats theheat transfer fluid 114 which heats moving parts of thetorrefaction reactor 112. The moving parts are in direct contact with dried wood particles and heat the wood particles using convection heating and accurate temperature control. Thetorrefaction reactor 112 generates thesyngas 116 and torrefied wood particles. The coolingtunnel 220 recovers heat from the torrefied wood particles and pre-heat thedilution air 218. Theheater exhaust gas 106 is used in theflash dryer 206. The thermal energy of the resultingexhaust gas 110 is used in the pre-dryer 204 to reduce the amount of usable thermal energy being released to the atmosphere by thevent gas 130. - Thermal energy efficiency is also improved in the process illustrated in
FIG. 2 by using a multi-stage drying process. In the multi-stage drying process, thewood particles 202 are slowly heated in the pre-dryer 204 to move free water and capillary water to the surface of the wood particles and partly evaporate the moisture, thereby reducing the moisture content of the wood particles; the pre-dried wood particles are rapidly heated in theflash dryer 206 to evaporate the surface water; and the flash dried wood particles are heated in thetorrefaction reactor 112 to remove free and cellular water from the wood particles. - Process Controls
- Material and gas of the process illustrated in
FIG. 2 are moved from one portion of the process to another portion of the process in a continuous manner. A control point for the material is thetorrefaction reactor 112. The amount of wood particles is metered through theflash dryer 206 to allow adequate processing time in thetorrefaction reactor 112, where the processing time in thetorrefaction reactor 112 is determined based on the desired torrefaction results. Similarly, the flow rate and the temperature of theheat transfer fluid 114 are determined based on the desired torrefaction results. Temperature gauges in set location inside thetorrefaction reactor 112 can be used to collect control information. The pre-dryer 204 can be used as an intermediate storage location by varying the speed of the conveying mesh belt. Temperature measurement at the end of theflash dryer 206 can be used to adjust the air flows and rate of cooling water addition of the coolingcompactor 122. The process controls can be automated with Programmable Logic Control (PLC) or similar technology. - The flow diagram shown in
FIG. 3 is an example of the process illustrated inFIG. 2 . - In the example illustrated in
FIG. 3 ,wood chips 302 are stored in awood chip silo 304. Thewood chips 302 have a moisture content of 35% (WB) and a density of 250 kg/m3. Thewood chips 302 are delivered to achip sizer 306 at a rate of 11 tonnes/hour. - The
chip sizer 306 generates 44 m3 ofwood particles 202 per hour. Thewood particles 202 have a density of 250 kg/m3 and a moisture content of 34.7% (WB). - The
wood particles 202 are delivered to the pre-dryer 204. Thewood particles 202 are conveyed on a conveying mesh belt through the pre-dryer 204 as a mat having a material thickness of 20 cm, and which is 4 m wide and 15 m long. The total volume of the mat is 13.5 m3 and the conveying mesh belt travels at a rate such that thewood particles 202 have a residence time in thepre-dryer 204 of 0.3 hours. - The mat is moved through the pre-dryer 204 and the
wood particles 202 are heated by theexhaust gas 110 from theflash dryer 206. Theexhaust gas 110 is blown from theflash dryer 206 by a dryer exhaust fan 316 that provides 53,770 actual cubic meters per hour (am3/h) at 178° C. temperature. Theexhaust gas 110 includes water vapor at a rate of 2,790 kg water per hour. The pre-dryer 204 dries thewood particles 306 and generatespre-dried wood particles 310. - The mat of wood particles filters dust and condenses volatile organic compounds (VOCs) present in the
exhaust gas 110. Theexhaust gas 110, which has been filtered by the mat, is vented asvent gas 130 at a flow rate of 41,900 am3/h, and at a temperature of 100° C. Thevent gas 130 includes water vapor at a rate of 5,000 kg/h. Thevent gas 130 is propelled by avent gas fan 312. - The
pre-dried wood particles 310 are delivered to theflash dryer 206 at a rate of 9.8 tonnes/h. Thepre-dried wood particles 310 have a moisture content of 27%, resulting in 2661 kg of water per hour entering theflash dryer 206. - The
pre-dried wood particles 310 are transported airborne in theheater exhaust gas 106 from theheat exchanger 214. Theheater exhaust gas 106 evaporates surface water on thepre-dried wood particles 310, generating flash-dried wood particles 314. Theheater exhaust gas 106 is exhausted from theflash dryer 206 asexhaust gas 110. - The
heater exhaust gas 106 is blown from theheat exchanger 214 at a rate of 83,500 am3/h and at a temperature of 300° C. Theheater exhaust gas 106, including water vapor at a rate of 1690 kg water per hour, enters theflash dryer 206. - The
exhaust gas 110 is blown from theflash dryer 206 using a flash dryer exhaust fan 316. The flash dryer exhaust fan 316 provides theexhaust gas 110 at 56,600 am3/h and at a temperature of 178° C. Theexhaust gas 110, including water vapor at a rate of 2,794 kg water per hour, enters the pre-dryer 204 - The flash-dried wood particles 314 are at 70° C. and have a moisture content of 8.2%. The
flash dryer 206 provides 7.8 tonnes of the flash-dried wood particles 314 per hour to thetorrefaction reactor 112. Thetorrefaction reactor 112 produces 5.0 tonnes of torrefied wood particles 318 per hour. The torrefied wood particles 318 have a moisture content of 2.8% and are at a temperature of 260° C. - The
torrefaction reactor 112 also generates, at a temperature of 260° C., thesyngas 116 at a rate of 2,280 kg/hour and water vapor at a rate of 500 kg/hour. Thesyngas 116 is burned in theburner 208 and the combustion chamber 212 along withnatural gas 320. Thenatural gas 320 is burned at a rate of 70 kg/hour. - Heat generated in the
combustion chamber 214 is used to heatthermal oil 322 in theheat exchanger 214. Thethermal oil 322 circulates between theheat exchanger 214 and thetorrefaction reactor 112 at a rate of about 900 kg/min, which corresponds to 1.4 m3/min. Thethermal oil 322 enters theheat exchanger 214 at a temperature of 265° C. and exits theheat exchanger 214 at a temperature of 290° C. Thecombustion air 120 is blown into theburner 208 using an air fan 324 at a rate of 5,200 m3/h. The hot gases from the combustion chamber 212 are mixed in theheat exchanger 214 with thedilution air 218, which can be pre-heated by sucking air through the coolingtunnel 220. Thedilution air 218 is blown into theheat exchanger 214 using a dilution air fan 326 at a rate of 30,700 nm3/h. - The torrefied wood particles 318 are pre-cooled and compacted in the
cooling compactor 122. The coolingcompactor 122 receives the torrefied wood particles 318 at a rate of 5.0 tonnes/hour. The torrefied wood particles 318 have a moisture content of 2.8%. - The cooling
compactor 122 produces pre-cooled compactedwood particles 216 with density of 500 kg/m3 and temperature of 150° C. The coolingtunnel 220 yields compactedtorrefied wood particles 218 at a temperature of 50° C. Thedilution air 218 is pre-heated from 20° C. to temperature of 40° C. - Mass and energy balances of a process according to the present application is shown in Table 1, below.
-
Input Output Combustion + Compacted Wood Dilution torrefied Particles Air Natural Gas Electricity Vent Gas wood particles 11 tonnes/h 5,170 + 30,730 Nm3/h 0.8 kW(h) 450 kW 41,915 Nm3/h 5.0 tonnes/h (e) 35% MC 20° C. 67 kg/h 5,000 kg 2.8% MC vapor 250 kg/m3 42.9 MJ/ kg 102° C. 450 kg/m3 20° C. 2.9 GJ/h 58,765 am3/h 50° C. 11.2 kJ/kg 38.2% RH 24 MJ/kg LHV LHV 34.2 MW 51° C. dew 32.6 MW Heat point Heat capacity capacity - In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments of the application. However, it will be apparent to one skilled in the art that these specific details are not required in order to practice the application.
- The above-described embodiments of the application are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art without departing from the scope of the application, which is defined solely by the claims appended hereto.
Claims (24)
1. A process for producing compacted torrefied biomass from pre-processed biomass, the process comprising:
drying the pre-processed biomass in a dryer, comprising a pre-dryer and a main dryer, with heater exhaust gas from a heater, yielding dried biomass;
torrefying the dried biomass in a torrefaction processor, comprising a torrefaction reactor and a cooling compactor, with heat generated by the heater, yielding pre-cooled compacted torrefied biomass; and
combusting syngas from torrefaction processor with support fuel in a heater, yielding heat for the dryer and torrefaction reactor.
2. The process according to claim 1 , wherein the dryer consists essentially of a pre-dryer and a main dryer.
3. The process according to claim 1 , wherein the torrefaction processor consists essentially of a torrefaction reactor and a cooling compactor.
4. The process according to claim 1 , wherein drying the pre-processed biomass comprises pre-drying the pre-processed biomass in a pre-dryer with the exhaust gas from the main dryer.
5. The process according to claim 4 , wherein pre-drying the pre-processed biomass with the exhaust gas from the main dryer: filters dust fines from the exhaust gas from the main dryer, condenses volatile organic compounds from the exhaust gas from the main dryer, or both filters dust fines and condenses volatile organic compounds from the exhaust gas from the main dryer.
6. The process according to claim 1 , wherein drying the pre-processed biomass comprises flash drying the pre-processed biomass in a flash dryer with the heater exhaust gas, and wherein the exhaust gas is obtained from the flash dryer.
7. The process according to claim 6 , wherein exhaust gas from the flash dryer is used to pre-dry the pre-processed biomass in a pre-dryer.
8. The process according to claim 7 , wherein pre-drying the pre-processed biomass with the exhaust gas from the flash dryer: filters dust fines from the hot exhaust gas from the flash dryer, condenses volatile organic compounds from the exhaust gas from the flash dryer, or both filters dust fines and condenses volatile organic compounds from the hot exhaust gas from the flash dryer.
9. The process according to claim 1 , wherein the heater is a combustion heater, torrefying the dried biomass yields syngas, and the syngas is used as a fuel in the combustion heater.
10. The process according to claim 9 , wherein natural gas and syngas are used as fuels in the combustion heater.
11. The process according to claim 10 , wherein the dilution air is added to the heater in order to have heat capacity of the exhaust gas for drying requirements
12. The process according to claim 1 , wherein torrefying the dried biomass comprises heating the dried biomass to temperature between 220 and 280° C. for between 15 and 30 minutes in a low-oxygen environment.
13. The process according to claim 1 , wherein the torrefied biomass is processed into pre-cooled compacted torrefied biomass in a cooling compactor, directly connected to the torrefaction reactor thus maintaining the low-oxygen environment.
14. The process according to claim 12 further comprising adding a liquid binder.
15. The process according to claim 13 wherein the pre-cooled compacted biomass is cooled in a cooling tunnel
16. The process according to claim 14 wherein the cooling tunnel pre-heats the dilution air
17. The process according to claim 1 , wherein the heater comprises a burner, the burner generates combustion gases, and dilution air is added to the combustion gases to yield the heater exhaust gas.
18. The process according to claim 1 , wherein the heat generated by the heater is delivered to the torrefaction reactor by a thermal transfer fluid.
19. The process according to claim 1 , wherein the pre-processed biomass is agricultural waste or woody biomass.
20. The process according to claim 17 , wherein the pre-processed biomass is woody biomass, the woody biomass is wood or wood waste, and the process further comprises processing the wood or wood waste into wood chips or hog fuel, and sizing the wood chips or hog fuel into wood particles.
21. The process according to claim 1 , wherein the process is a continuous process and operating parameters of the process are determined based on measurements obtained from at least one gauge in the process.
22. The process according to claim 19 , wherein the process is automatically controlled with Programmable Logic Control.
23. The process according to claim 1 , wherein the heater exhaust gas and the dryer exhaust gas are in fluid communication and are moved using a fan and a booster fan.
24. A process for producing compacted torrefied biomass from pre-processed biomass, the process comprising:
pre-drying the pre-processed biomass in a pre-dryer, yielding pre-dried biomass;
flash drying the pre-dried biomass in a flash dryer with heater exhaust gas from a heater, yielding flash dried biomass and exhaust gas from the dryer;
torrefying the flash dried biomass in a torrefaction reactor with heat generated by the heater, yielding torrefied biomass; compacting and pre-cooling the torrefied biomass in a cooling compactor with the cooling water, yielding the pre-cooled torrefied biomass, and:
further cooling the pre-cooled compacted torrefied biomass in a cooling tunnel, yielding compacted torrefied biomass and preheated dilution air.
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- 2014-04-09 CA CA2909407A patent/CA2909407A1/en not_active Abandoned
- 2014-04-09 WO PCT/CA2014/050364 patent/WO2014165995A1/en active Application Filing
- 2014-04-09 US US14/783,782 patent/US20160304800A1/en not_active Abandoned
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US11248845B2 (en) | 2017-03-03 | 2022-02-15 | Douglas Technical Limited | Apparatus and method for continuously drying bulk goods, in particular wood chips and/or wood fibers comprising a heat exchanger |
US11543124B2 (en) | 2017-03-03 | 2023-01-03 | Kronoplus Limited | Apparatus and method for continuously drying bulk goods, in particular wood chips and/or wood fibers comprising a hot gas cyclone |
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US20180355268A1 (en) * | 2017-06-13 | 2018-12-13 | Arr-Maz Products, L.P. | Structured composite wood pellets for dust/fines mitigation and method of producing them |
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WO2021084016A1 (en) * | 2019-10-29 | 2021-05-06 | Michiel Cramwinckel | Process for a plastic product conversion |
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US11952548B2 (en) * | 2021-07-26 | 2024-04-09 | Michigan Technological University | Systems, methods and techniques for torrefaction |
Also Published As
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CA2909407A1 (en) | 2014-10-16 |
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