WO2017062793A1

WO2017062793A1 - Pyrolyzer design for processing of biomass

Info

Publication number: WO2017062793A1
Application number: PCT/US2016/056035
Authority: WO
Inventors: Daren Einar DAUGAARD; Brian Buege; Victoria PUTSCHE; Bradley Dale WAITES
Original assignee: Cool Planet Energy Systems, Inc.
Priority date: 2015-10-09
Filing date: 2016-10-07
Publication date: 2017-04-13

Abstract

Various biomass reactors systems and methods of pyrolyzing biomass are disclosed. One type of biomass reactor system comprises a plurality of stacked biomass pyrolysis stations configured in series.

Description

PYROLYZER DESIGN FOR PROCESSING OF BIOMASS

REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit and priority to U.S. Provisional Application No. 62/239,545 filed October 9, 2015 and entitled "Pyrolyzer Design For Processing Of Biomass," the contents of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

[0002] The present application relates to a method and system for fuel production from pyrolysis of biomass. A subfield is a stacked auger system for the production of renewable fuel.

BACKGROUND

[0003] Rising energy costs, concerns about the continued use and availability of nonrenewable sources, and concerns about the effects of the use of fossil resources on global climate change have become some of the major technological challenges facing humanity. Finding ways to more effectively use alternative sources of energy such as renewable biomass is an important avenue for addressing these issues. Prior to the beginning of the industrial revolution, wood and plant oils were the primary source of energy for pre-industrial civilizations, which used this energy mainly for heating, cooking, and light. During this early period, biomass was simply burned in open air to produce heat and light. Several thousand years ago, it was discovered that if the air supply was restricted during the burning process, a dense black residual (which we now call coke) could be extracted from burning wood. This hot coke could be quenched with water, dried, and re-burnt to produce a much hotter, denser fire. The emergence of coke proceeds in parallel with the development of metallurgy, which is dependent upon its hotter and cleaner fire along with its reducing capabilities to both extract metals from ore and form them into useful products. The process of roasting a combustible material in either a reduced oxygen environment or oxygen-free environment is now called pyrolysis. Pyrolyzing wood and other forms of mixed biomass produces coke (also called char or biochar) and, depending on the temperature of pyrolysis, a mixture of hydrogen, carbon monoxide and carbon dioxide, sometimes referred to as syngas, or a more complex mixture of volatile and non-volatile gaseous compounds sometimes referred to as pygas. Roasting fossil fuel hydrocarbons in an oxygen-free environment first causes a breakdown of longer chain hydrocarbons into shorter chain hydrocarbons, ultimately resulting in more elemental forms such as methane (CH₄), hydrogen, and elemental carbon. In fact, pyrolysis is a fundamental mechanism of petrochemical cracking, which is the backbone of oil refinery processes. More extreme pyrolysis is used in the refinery process to produce hydrogen and high purity carbon.

[0004] Likewise, biomass (which is made up of cellulose, hemicelluloses, lignin, starches, and lipids) proceeds through multiple stages of decomposition when subject to the pyrolysis process. Depending on the conditions of the pyrolysis, the composition of the products can be varied. In general, when subject to high temperatures (e.g., 800°C) for prolonged periods of time, pyrolysis ultimately yields syngas. As the temperature and exposure time interval is reduced, an increasing amount of biochar residue remains. At still lower temperatures and time intervals, increasingly complex hydrocarbons and oxygenated hydrocarbons are present in the gas stream from the pyrolyzed biomass. These molecules form vapors that can be condensed and used as a liquid product (bio-oil) or converted immediately to other products. At the low extreme, simple everyday cooking typically drives off water and starts to de-hydrolyze the biomass, causing the darkening and carmelization that we all associate with cooked foods.

[0005] Various forms of laboratory and small scale commercial biomass pyrolyzers have been developed to generate useful chemical products from the controlled pyrolysis of biomaterials ranging from wood chips to sewage sludge. Although some pyrolyzers are focused simply on producing syngas, there is considerable effort in the development of milder pyrolyzing conditions, which typically results in a condensed liquid commonly called bio-oil. Many forms of pyrolyzers have been developed at the laboratory level to produce these intermediate compounds, which are collectively referred to as bio-oil or pyrolysis oil. Configurations include simple tube furnaces where the biomass is roasted in ceramic boats, ablative pyrolyzers where wood is rubbed against a hot surface, various forms of fluidized bed pyrolyzers where biomass is mixed with hot sand, and various simpler configurations that are based on earlier coking oven designs. [0006] One common class of pyrolysis systems is the rotary kiln/screw auger that moves material by rotation through a channel using flights on a shaft and providing heat in some method.

[0007] The fundamental problem with the resultant pyrolysis oil from a biomass feedstock is that it is made up of hundreds to thousands of compounds, which are the result of subjecting the raw biomass to a wide range of temperature, time, and pressure profiles in bulk. When this process is complicated by the thousands of major bio-compounds in the original bio-feedstock, the result is a nearly intractable array of resultant compounds all mixed together. Pyrolysis oils from such processes are typically not thermodynamically stable. They contain active oxygenated free radicals that are catalyzed by organic acids and bases such that these oils typically evolve over a period of a few days from light colored liquids to dark mixtures with tar and resinous substances entrained in the mix. Also, attempts to re-vaporize pyrolysis oil typically result in additional chemical reactions, which produce additional biochar and a shift to lower molecular weight components in the resulting gas stream. Although fairly high yields of pyrolysis oil can be achieved in laboratory scale experiments, larger industrial scale demonstration projects typically produce much lower yield. This is presumably due to the wider range of temperatures, hold-times, and localized pressures within the much larger heated three dimensional volumes of such scale-up architectures.

[0008] Physical properties of typically used pyrolyzer materials can make long, linear construction of pyrolyzers impractical on larger scales. Longer pyrolyzers may be necessary to provide sufficient conditions to effectively fractionate biomass into the desired vapor streams. However, longer pyrolyzers are prone to distortion, such as excessive warping, auger twist and bowing. Furthermore, longer pyrolyzers require facilities capable of housing the longer units.

[0009] Pyrolyzers employing conventional auger designs tend to suffer from poor mixing, which leads to inconsistent pyrolysis due to increased conductive heating of biomass in direct contact with metallic surfaces of the unit as well as decreases in the efficiency of removing the pyrolysis vapors from the particles immediately after they are produced through the use of sweep gasses. [0010] The present invention aims to address how biomass may be more effectively fractionated.

SUMMARY

[0011] A method and system is described by which carbon containing material such as biomass is heated and thermally decomposed in a reactor comprising stacked pyrolysis stations. The stacked pyrolysis stations may be designed to allow for more efficient heating of biomass, reduced space consumption and improved transfer between stations. They may also be separated by pressure boundaries to allow operation of each reactor or station to be operated at varying temperature and pressure.

[0012] A system designed to carry out the method may include a stacked auger system having a plurality of biomass pyrolysis stations configured in series, each station comprising an auger or portion of an auger including an auger inlet for receiving carbonaceous solid such as biomass and a transfer screw for conveying the solid through the reactor.

[0013] Each auger may further comprise a motor for driving the transfer screw and one or a plurality of exit ports for fractions of the pyrolysis vapor and associated systems configured for fractions of a pyrolysis vapor stream originating from the reactor.

[0014] In further embodiments, a first pyrolysis station in the series includes an exit port that terminates in a transfer chamber, which terminates in an inlet of a second pyrolysis station, and a last pyrolysis station in the series terminates in an exit port that removes partially and/or fully pyrolyzed product from the system.

[0015] In one or more embodiments, one or more stations comprises an auger used to convert the biomass to vapor and solid streams.

[0016] In one or more embodiments, the first station is preceded by one or more stations for drying of biomass.

[0017] In one or more embodiments, renewable chemicals are synthesized from one or more vapor products. [0018] In one or more embodiments, each auger further comprises a motor or engine for driving the transfer screw. In another embodiment, one motor or engine could drive multiple screws.

[0019] In one or more embodiments, an auger can be oriented on a slant of 0° to 85° with respect to horizontal.

[0020] In one or more embodiments, filters, temperature quench, or cyclones are used to remove heavy coke forming or particulate components whereby catalyst coking rates are further decreased.

[0021] In one or more embodiments, a first pyrolysis station in the series includes an exit port that terminates in an inlet of the second pyrolysis station.

[0022] In one or more embodiments, a last pyrolysis station in the series terminates in an exit port that removes a partially and/or fully pyrolyzed product of the system.

[0023] In one or more embodiments, a plurality of vapor streams are removed from the system.

[0024] In one or more embodiments, the temperature of each auger comprises a varying temperature along the length of the auger.

[0025] In one or more embodiments, said transfer screw has continuously decreasing distance between flights whereby the biomass material is compressed and the pressure in the biomass and its thermal decomposition products increases.

[0026] In one or more embodiments, the system further includes a second reactor comprising a pyrolyzer station having an auger for receiving the biomass from the first reactor and further pyrolyzing the biomass. In some cases, the two reactors are contained in the same furnace box, but operated at different heat ranges.

[0027] Other features and aspects of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features in accordance with embodiments of the invention. The summary is not intended to limit the scope of the invention, which is defined solely by the claims attached hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention, in accordance with one or more various embodiments, is described in detail with reference to the following figures. The drawings are provided for purposes of illustration only and merely depict typical or example embodiments of the invention. These drawings are provided to facilitate the reader's understanding of the invention and shall not be considered limiting of the breadth, scope, or applicability of the invention. It should be noted that for clarity and ease of illustration these drawings are not necessarily made to scale.

[0029] Figure 1 is a sectional view illustrating a biomass fractionation system incorporating a stacked pyrolysis station according to one or more embodiments.

[0030] Figure 2 is an illustration of the auger screw flights in the inlet region of the solid feed according to one or more embodiments.

[0031] Figures 3 A and 3B are illustrative example auger screw flights connecting structures, in accordance one or more embodiments.

[0032] Figures 4A, 4B, and 4C illustrate flight designs that promote vapor flow and solids mixing, in accordance one or more embodiments.

[0033] Figures 5 A and 5B illustrate a screw design that promotes vapor flow and a feature to improve reliability of solids handling.

[0034] It should be understood that the invention can be practiced with modification and alteration, and that the invention be limited only by the claims and the equivalents thereof.

DETAILED DESCRIPTION

[0035] The following diagrams and description present examples of the invention, but in no way, limit the application of the above concepts. The following designs are simply illustrative of their application. Unless specifically defined otherwise, all technical or scientific terms used herein have the same meaning as commonly understood by one possessing ordinary skill in in the art.

[0036] As used herein, the term "pyrolysis" refers to thermal transformation of a material into one or more substances by heat in a reduced oxygen environment.

[0037] As used herein, the term "biomass" includes any material derived or readily obtained from plant or animal sources. Such material can include without limitation: (i) plant products such as bark, leaves, tree branches, tree stumps, hardwood chips, softwood chips, grape pumice, sugarcane bagasse, switchgrass; and (ii) pellet material such as grass, wood and hay pellets, crop products such as corn, wheat and kenaf. This term may also include seeds such as vegetable seeds, sunflower seeds, fruit seeds, and legume seeds. The term 'biomass' can also include: (i) waste products including animal manure such as poultry derived waste; (ii) commercial or recycled material including plastic, paper, paper pulp, cardboard, sawdust, timber residue, wood shavings and cloth; (iii) municipal waste including sewage waste; (iv) agricultural waste such as coconut shells, pecan shells, almond shells, coffee grounds; and (v) agricultural feed products such as rice straw, wheat straw, rice hulls, corn stover, corn straw, and corn cobs. Although the description herein emphasizes the processing of biomass, the systems disclosed herein can also be used to process other non- biomass materials, such as tires and plastics. These materials could be processed along with biomass in certain cases.

[0038] As used herein, the term "reactor" means a unit that operates at one set of temperatures and pressures with at least one exit point for each of vapors and solids.

Variations in temperature and pressure can occur within various components of a reactor.

[0039] As used herein the term "bio-oil" means any liquid oxygenated hydrocarbon fuel thermally quenched from the pyrolysis vapors of a biological substrate including, without limitation, an oil containing the elements carbon, hydrogen, or oxygen, and which may be referred to in the art as a "bio-crude" and/or a "pyrolysis oil".

[0040] The term "vapor", as used herein, means a phase of a substance including a liquid- vapor mixture, saturated vapor, superheated vapor or vapor/gas mixture. It is appreciated that vapor will include both the condensable portions as well as the light gases due to the difficulty of separation. [0041] The term "gas", as used herein, means a phase of a substance including an ideal gas, real gas, gas mixtures, or a gas/vapor mixture. It is appreciated that a gas may include a condensable component as well as the light gases due to the difficulty of separation.

[0042] The term "shaft", as used herein, means the center structure of the transfer screw to which the flights are attached.

[0043] The term "flights", as used herein, means the structures attached to center shaft of the auger screw which have the primary function to move material through the auger.

[0044] The term "biochar", as used herein, means the solid carbonaceous material produced after pyrolysis of biomass. Biochar may have a plurality of uses including but not limited to a soil amendment, combustion feedstock, or means for sequestering carbon.

[0045] The term "fuel", as used herein, means liquid hydrocarbons that may be used as an energy source. Fuel as a liquid hydrocarbon may have a plurality of uses including transportation fuel, fuel for stationary internal combustion engines, and other such purposes common in the world.

[0046] Methods and systems are described for which carbon containing material such as biomass are processed to produce a plurality of product streams that may have one or more beneficial characteristics. It is appreciated that any methods or materials similar or equivalent to those described herein can be used in the practice or deployment of the present invention.

[0047] The method and system provides pyrolysis of carbon containing material such as biomass by heating and thermally decomposing the carbon-containing material in a reactor comprising a plurality of stacked pyrolysis stations. The stacked stations allow for longer biomass processing times in a processor having a smaller footprint than would be required for a reactor with a linear construction. The pyrolysis stations may be stacked vertically, horizontally or at various orientations in between. The stacked pryolysis stations are typically arranged such that the material flows in opposite directions in adjacent stations. In this case, the stacked configuration not only reduces the space consumption but also allows for more efficient heating because of the opposing directions of flow for biomass in adjacent stations. [0048] In one embodiment, the pyrolysis processing stations include one or more rotating screw augers or rotating kilns (herein referred to as auger). The auger system pyrolyzes carbon containing material such as biomass to produce a vapor stream and a may result in the production of biochar. Auger technology relies on mechanical movement of the solids through the reaction zone. This characteristic means that the auger can be operated across a wide range of temperatures, pressures, and residence times of the solids. Tuning the conditions to produce an optimal vapor for fuel yield is practical when an auger is selected.

[0049] In certain embodiments, the method and system provide a vapor stream for catalytic conversion into fuel that results in increased catalyst life without compromise to the efficiency of fuel production. The catalyst process includes catalyst columns that contain catalysts that come into contact with the vapor streams from the pyrolysis process. The catalysts convert the components of the vapor stream into renewable fuels. Catalyst and catalytic processes for fuel production known and suitable catalyst include hydration catalysts, aromatization catalyst, dehydration catalyst, dehydrogenation catalysts and the like. Alternatively, the vapor stream may be directed to a condensing system for conversion to fuel.

[0050] According to one or more embodiments, biomass can be processed in a processing station (optionally after processing to remove an acetic acid-rich vapor stream) to produce a vapor stream suitable for conversion into biofuel. Vapor streams rich in one or more of various compounds, including but not limited to: (i) long chain dehydrated sugars; (ii) lignin derived aromatics; (iii) lipid based oils; (iv) carbohydrate based furans can be considered suitable for conversion into biofuel. The resultant solid stream can be further processed at a subsequent processing station to generate a solid stream that can be used as a soil amendment or for carbon sequestration. The vapor stream (which may be suitable for either a differing type of fuel production due to low content of fuel-producing components or high content of coke-producing components) can either be converted to fuel using different conversion technologies from the previous streams or be diverted for other uses (such as for heat or energy production, e.g., by combustion).

[0051] In certain embodiments, the method and system provide both a vapor stream for catalytic conversion into fuel and a biochar product that can be optimized for use as a soil amendment or carbon sequestration. [0052] The systems and methods described herein may be used in conjunction with other processes or stations to assist in reducing coke formation during catalytic production of fuels. In certain embodiments, the vapor streams removed from the pyrolysis stations for fuel production can pass through a filter used to remove heavy coke forming components or particulate components before entering the catalytic process. In other embodiments, the vapor streams removed from the pyrolysis stations for fuel production can be subjected to a partial quench to remove or reduce the vapor stream content of heavy coke forming components or particulate components before entering the catalytic process. The temperature quench can be accomplished using a condenser. The quench is a partial condensation in that it does not remove fuel-forming components from the vapor stream. In other embodiments, a filter or cyclone is used to remove heavy coke forming components or particulate

components before entering the catalytic process. In other embodiments, the catalyst process can include a catalyst regeneration system that restores catalytic activity. In some

embodiments, the catalytic process can include a continuously regenerating catalyst system with multiple catalytic reactors.

[0053] Figure 1 illustrates a carbon containing fractioning system 100 comprising a first reactor 110 for stage 1 pyrolysis and second reactor 120 for stage 2 pyrolysis. In this example, the two reactors are contained in a single furnace box with the second reactor 120 positioned below the first reactor 110. The first reactor 110 contains a plurality of pyrolysis stations. As shown in Fig. 1, the first reactor 110 contains two horizontally stacked pyrolysis stations 130, 140, each of which contains an auger, connected in series. The auger-containing pyrolysis station can be employed to carry out any of the fractioning and/or pyrolyzing processes set forth herein. In the illustrated embodiment, pyrolysis station 130 comprises a feeder 145 for receiving biomass, auger 150 for receiving the biomass from feeder 145 and including a transfer screw 160 for conveying the biomass, a motor 170 for driving the transfer screw 160, and an exit port 180 leading to transfer chamber 190 connecting the first and second pyrolysis stations 130, 140, respectively. The second pyrolysis station as shown in Fig. 1 also includes an auger 200 for receiving the biomass from the transfer chamber 190 and including a transfer screw 210 for conveying the biomass, a motor 220 for driving the transfer screw 210, and an exit port 230 leading, in this case, to a discharge lock hopper 240 connecting the first and second reactors 110, 120, respectively. [0054] The second reactor 120, as shown in Fig. 1, includes a single pyrolyzer station 250 having an auger 260 for receiving the biomass from the discharge lock hopper 240 and including a transfer screw 270 for conveying the biomass, a motor 280 for driving the transfer screw 270, and an exit port 290 leading, in this case, to a high temperature discharge lock hopper 265. The biomass may be conveyed using a cut and folded flight auger to promote mixing. The cut flights allow material in the biomass stream to be dropped and folded back into the stream. These augers also increase the biovapor's flow rate. In some cases, at least a portion of the auger near the exit port 290 will only have cut flights to reduce the amount of solids lifted into the gas stream before the biovapors exit the station. In some cases, this portion may correspond to the last 1/3, ¼, 1/5 or 1/6 of the auger.

[0055] The biomass fractioning system 100 typically includes one or more heat sources for heating the biomass as it is conveyed through the system 100. In some embodiments, the heat source comprised indirect heating by combustion of natural gas or other fuel. In some embodiments, the heat source can include one or more heating components. In other embodiments, auger 150, 200, or 260 can heat the biomass by way of hot transfer fluid passing through the auger. The heat may be varied along the auger to create multiple stages for fractionation. In further embodiments, the transfer screw 160, 210 or 270 can itself be heated. In another embodiment, hot sand or other heat transfer media (e.g., steel) is passed through the auger 150, 200, or 260 during operation, thereby heating the biomass. In a particular embodiment, specific designed phase changing heat transfer media can be used to more precisely control the pyrolysis temperature. For example, a specific heat transfer media that changes phase at a specified temperature may be used in stage 1 and a second specific heat transfer media that changes phase at a different specified temperature may be used in stage 2. In another embodiment, heat could be provide through electrical resistance thus passing heat from the auger to the biomass.

[0056] With further reference to Figure 1, transfer screw 160 is mounted to rotate inside the auger 150, and is driven by associated external motor 170. The auger 150 has an inlet connected to a feeder 145. In operation, biomass is loaded into the feeder 145, which feeds the biomass into auger 150 by way of the inlet. Transfer screw 160 conveys the biomass at a constant and regulated speed through the auger 150. The biomass is subjected to heat resulting in its decomposition during transport through the auger. This decomposition creates partially and/or fully pyrolyzed product and a pyrolysis vapor stream 300. In accordance with other embodiments, the auger could be fixed with a rotating outside housing or the pyrolysis reactor could comprise a rotating housing without an auger.

[0057] Auger 150, 200, or 260 may comprise a shaft with one or more flight(s) attached. In combination, the shaft and attached flight(s) constitute a transfer screw 160, 210, or 270. The transfer screw rotates relative to a housing that encloses the screw and said housing is substantially gas tight. The rotation may be accomplished by any mechanical driver 170, 220, or 280 such as but not limited to electrical motor, engine, gas turbine, or any other suitable mechanical means. The rotation of the transfer screw relative to housing transports the carbon containing material through the length of an auger. In another embodiment, the auger may comprise of a collection of flights without a center shaft.

[0058] Further considering Figure 1, each reactor includes an exit port for release of vapor streams 300, 310 generated during use. The vapors at 300, 310 can be collected as they are released or continuously processed as they are emitted. At the end of reactor 110, the biovapor discharge 300 can be passed through a cyclone separator 320 and a guard bed (not shown) before being delivered to a catalytic column, combustion system or condensing system for conversion to fuel. The biovapors are cooled and processed into a liquid fuel stream and a lights stream. A portion of the lights stream can be recirculated back into the inlet 325 of the first pyrolysis station 130 to sweep biovapor out of the pyrolyzer and reduce the biovapor' s residence time. Biochar can be recovered from exit port 230 or 290, or, if further processing is desired, exit port 230 or 290 can lead to a next stage in the system.

[0059] Transfer chambers 190 can be utilized at the end of each reaction chamber to facilitate mixing and resequencing of the feedstock or partially and/or fully pyrolyzed feedstock (biomass) in the next reaction chamber. Other optional methods for improving mixing include, but are not limited to, the use of fairings, ridges, or other mechanical structures and devices. Furthermore, injection of sweep gas through directed ports can be used to improve processing of the biomass. Optionally, sweep gas flow and/or other mechanical means can be engineered to extract or separate feedstock based on size, weight, aerodynamic characteristics at each transfer chamber and route the feedstock accordingly to a suitable destination (e.g., recycle to beginning of chamber, extract from primary process path, or bypass next chamber). For example, gas can be injected into the transfer chamber to facilitate separation of fines from the rest of the processed biomass. Also, in any of these methods can be used in combination with alternative auger design (cut flights, tabs, rods), as discussed in more detail below. Typically, the transfer chambers are vertically oriented but could be at an angle of from about -75 to 75. These transfer chambers may also contain vertically mounted augers to control the vertical movement of the solids.

[0060] In accordance with certain embodiments, the transfer chamber can be designed to dynamically create pressure gradients at intermediate points in the reactor where it is suitable to extract one gas stream, and reinject sweep gas shortly thereafter. In accordance with one aspect, the transfer chamber may comprise a collection container and lockhopper to allow for staged runs through each auger flight. In accordance with another aspect, the transfer chamber may be designed to include a tapering/ constricting section of the transfer chamber that creates a larger pressure transfer, which in turn would allow for an outflow of gas from the high pressure area above the "throat" and injection of new sweep gas into the low pressure area below the throat. This would allow some leakage of gas through the constriction, but also allows for a much higher extraction rate of vapors from the preceding phase than would be possible in either a linear design or a transfer chamber with no constriction.

[0061] The transfer chambers may also be used to improve processing of biomass as it is transferred through the system. As char is removed from the transfer chamber(s), it can be replaced with catalyst to keep the biovapors flowing across catalyst. Catalyst could also be added at various points in the process, such as a fraction of the way along an auger, to facilitate processing of the biomass. This introduction of catalyst during processing of the biomass could reduce or eliminate the need for a separate catalyst reactor.

[0062] In yet another embodiment, the process could include the introduction of reactive gas at one or more points in the process to improve internal heating, groom biovapors. For example, a relatively low amount of reactive vapors could be introduced and fully reacted at only a fraction of the entire flowpath through the system. Examples of reactive gases include, but are not limited to, methane, hydrogen, oxygen, also ethanol and methanol.

[0063] Although the illustrated embodiment features two pyrolysis stations in the first reactor and one pyrolysis processing station in the second reactor, any number of biomass pyrolysis stations can be employed without departing from the scope of the invention. For example, the first reactor may contain anywhere from 2 to 100 pyrolysis stations. The second reactor may contain anywhere from one to 100 pyrolysis stations. Furthermore, the second reactor for purposes of the present invention is optional. In addition, the system may include additional optional stations preceding the pyrolysis stations. For example, the system may include stations for pre-treatment of the biomass, including stations for drying, torrifaction and acid washing of the biomass. Moreover, although the pyrolysis stations are shown as being vertically stacked, they could be horizontally stacked or stacked at any other configuration that would allow for suitable transfer of the biomass through the system.

[0064] Because each biomass fractionation reactor may be substantially isolated, for example by using a valve system, the pressure in each reactor can be independently controlled. The pressure is created by the generation of pyrolysis vapors and by introducing gases/vapors from a compressor. The pressure is controlled by the outlet valve which provides the back pressure necessary to have a pressure in a stage. The control is by the rate at which vapors are removed from the system.

[0065] In some embodiments, the temperature T and pressure P within a pyrolysis station is controllable such that it can be varied in each successive pyrolysis station. In one exemplary embodiment, the temperature rises in each successive pyrolysis station to an incrementally higher temperature Tl, T2, T3 than the previous station. Each temperature stage is selected to drive off an appropriate vapor fraction from the biomass by way of vapor stream 300, 310. At the same time, the pressure PI, P2, P3 can transfer across each successive pyrolysis station, thereby facilitating volatilization of heavier components near the end of the pyrolysis stage. The temperature and pressure profile of the system may therefore utilized to produce product streams with desirable characteristics.

[0066] In another embodiment of the invention one or more of the individual pyrolysis stations may employ a temperature profile along the length of the station.

[0067] In yet another embodiment, one or more of the individual auger stations may employ a pressure profile across the length of the auger. A pressure profile may be employed through screw design wherein the changing diameter of the screw or distance between the flights increases the pressure on the biomass as it is forced through the system. Thus, the screw may use a decreasing flight pitch or an increasing shaft diameter to increase pressure on the biomass within a processing station. A pressure profile also means different stages are at different pressures.

[0068] Still referring to Figure 1, the dimensions of each stage can be adjusted to allow more or less residence time at a particular station. In particular, the length of the auger at each station can be increased for a longer residence time, or decreased for a shorter residence time. Longer residence times can also be obtained by increasing the number of stacked stations in the reactor. In the illustrated embodiment, each auger in the first reactor 110 is depicted as having the same dimensions, and therefore similar vapor residence times. In further embodiments, the length of one or more augers can be varied to achieve a desired residence time at each station. Residence time can also be modified by using sweep gases to reduce the amount of time that the biovapors reside in the pyrolysis station.

[0069] The pyrolysis vapor fractions produced in the various pyrolysis stations can comprise commercially viable bio-intermediary compounds. By way of example, various reactor designs and operating conditions can be utilized to extract various compounds, including but not limited to: (i) long chain dehydrated sugars; (ii) lignin derived aromatics; (iii) lipid based oils; (iv) carbohydrate based furans; (v) shorter hydrocarbons; (vi) oxygenates such as butane, butanol, acetone, acetic acid, acetylaldehyde, aldehyde, methane, methanol, etc.; and (vii) ultimate syngas components (hydrogen, carbon monoxide, and carbon dioxide). At each successive processing stage, a station may be heated to a higher temperature via the various heating schemes detailed above and/or a higher pressure using the various schemes detailed above. In other embodiments, the pressure may vary (e.g., increase and decrease) as the solid stream advances through the process.

[0070] In other aspects of the invention, a modified auger system is provided that improves the feeding and transport of biomass through the auger. Certain carbon feeds and heat carriers are rigid or non-breakable and it is possible for the feeder entrance to clog or jam as the particles are fed from a hopper into the narrow opening in the auger. In one aspect shown in Fig. 2, the auger screw 715 is modified to facilitate the introduction of material into the reactor system and to reduce jamming. The auger system may include a specifically designed "step", shown in Fig. 2, at the location where solids and/or heat carrier are introduced into any of the one or more augers. The step includes a series of flights 720 that extend radially from the shaft a distance r' (indicated by arrow 725 in Fig. 2). The distance r' for the flight features 720 located proximate to the material feeder 330 is less than a distance r" (indicated by arrow 745 in Fig. 2) that defines the distance from the auger shaft 750 to the reactor wall 735. The distance r' is selected to provide a gap 730 from end or tip of the flight to the auger housing 735. The gap 710 can be greater than the axial length of the solid non- breakable particles which are introduced into the auger reactor. The flights that exhibit this characteristic are those in the section(s) where solids material is introduced into the auger as seen in Fig. 2. The gap 740 for the flights 730 not in the region of solid entrance 330 may be smaller than the axial length of said solid non-breakable particles.

[0071] The step illustrated in Figure 2 is advantageous for embodiments of the invention where solid non-breakable particles may be fed to the auger. The solid non-breakable particles can easily become trapped between the flights and the auger housing and inhibit or stop the movement of the screw relative to the housing. The step allows for the easy passage of non-breakable particles and reduces feedstock attrition. In addition the step reduces the initial attrition where particles of feedstock become trapped between the flights and the auger housing and are broken up by the force of the screw drive.

[0072] Figure 3 illustrates yet another embodiment of the auger screw having a modified screw structure. Screw structures 860 and 870 connect to two adjacent flights 830 of the screw. Figure 3 illustrates two (2) versions of these structures, a paddle 860 and a rod 870. As evident from Figure 3, the structures span the distance between flights and may be in any number of configurations and orientations. These structures promote mixing of solids. A separate function of these structures is to promote screw rigidity. Yet another separate function of these structures is to change the natural frequency of the screw. Hence the structures may be used for any combination of solids mixing, screw rigidity, and modification of the natural frequency of the screw. It will be appreciated by one skilled in the art that for long screws the additional rigidity provided by the structures will decrease deflection of the screw. It will also be appreciated by one skilled in the art that various components of the system such as the motor operate with a certain frequency which can be transmitted to the screw. The structures can modify the natural frequency. It will also be appreciated by one ordinarily skilled in the art that said structures will promote mixing as the screw is rotated [0073] In yet another embodiment of the invention the flights 930 may exhibit a design feature 920 in which a portion of the flight is removed as seen in Figure 4 to form smaller 'fins' that recesses along the edge of the screw flights. The removed portion may extend from the edge of the flight furthest from the shaft to the shaft to create a notch 910. Figure 4A is a view along the screw shaft illustrating this embodiment. In other embodiments, the removed portion may extend only a fraction of the total distance from the edge of the flight to the shaft to create notch 920. Figure 4B is a view along the screw shaft illustrating this embodiment. The feature maybe periodically repeated along the flight edge as seen in Figure 4C. Notch features 910 or 920 promote mixing of material and also allows for vapors produced to flow more easily toward exit ports in auger housing.

[0074] In yet another embodiment the flights are not continuous but broken into a plurality of flights distributed along the length of the shaft.

[0075] In yet another embodiment seen in Figure 5, the screw 1010 may be substantially smaller than the auger housing leaving a gap 1030 above the screw. In this embodiment the screw would nominally operate such that the distance from the bottom of the flights to the auger housing is less than the axial length of the particles to be conveyed. Said embodiment allows for vapor flow above the auger to the one or more exit ports in the auger housing. Due to the clearance space generated in this configuration, the vertical position of the screw can be adjusted for a plurality of reasons including but not limited to clearing of particle jams, operation with larger particles or maintenance. See, Figures 5A and 5B.

Example 1.

[0076] In accordance with this example, biomass (e.g., wood chips) is fed into the feeding system at feeder 145 and introduced into the first pyrolysis station 130 as shown in Fig. 1. The biomass entering the feeder is nominally 1" x 1" x 3/8", 70°F to 190°F, with 10% maximum moisture by weight. The biomass bulk density is 12 lb/ft3. The auger is heated externally such that the auger internal temperature is about 1000°F and the biomass temperature is between 480°F and 707°F. The pyrolyzer operating pressure can be between 10 and 40 psig.

[0077] Between about 10% and 60% of the biomass (on a bone dry basis) that enters the pyrolyzer (first reactor) exits as intermediate or volatile char at a temperature of between about 350°F and 900°F. The remainder exits the pyrolyzer as biovapors through the transfer line. The pyrolyzer varies the residence time of the biomass solids from about four (4) to ten (10) minutes before it passes through the exit valve. In accordance with this example, the biovapors typically have a residence time of less than ten (10) seconds and preferably less than four (4) seconds before they exit through the transfer line.

[0078] In the second reactor 120, the biomass is conveyed using one (1) cut and folded flight auger to promote mixing. The cut flights also increase the biovapor's flow rate. The folds in the flights assist in uniform mixing and heat transfer to the biomass. The last segment, about one-third of the auger, only contains cut flights to reduce the amount of solids lifted into the gas stream before the biovapors enter the transfer line. The biomass operating temperature is between 752°F and 1112°F and the auger housing metal temperature is above 1225°F. Between 20% and 35% of the biomass (on a bone dry basis) that enters the first reactor, exits the second reactor as char at a temperature of between 700°F and 1500°F. The remainder exits the pyrolyzer as biovapors through the transfer line. The pyrolyzer varies the residence time of the biomass solids from 2 to 5 minutes before it passes through the exit valve by utilizing motors to control the speed of the auger screws. A sweep gas rate of between 200-600 lb/hr is used to reduce gas residence time and provide convective heat transfer. Recaptured intermediate char from the first reactor cyclone is further processed in the second reactor.

[0079] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not of limitation. Likewise, the various diagrams may depict an example architectural or other configuration for the invention, which is done to aid in understanding the features and functionality that can be included in the invention. The invention is not restricted to the illustrated example architectures or configurations, but the desired features can be

implemented using a variety of alternative architectures and configurations. Indeed, it will be apparent to one of skill in the art how alternative functional, logical or physical partitioning and configurations can be implemented to implement the desired features of the present invention. Also, a multitude of different constituent module names other than those depicted herein can be applied to the various partitions. Additionally, with regard to flow diagrams, operational descriptions and method claims, the order in which the steps are presented herein shall not mandate that various embodiments be implemented to perform the recited functionality in the same order unless the context dictates otherwise.

[0080] Although the invention is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations, to one or more of the other embodiments of the invention, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments.

[0081] Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term "including" should be read as meaning "including, without limitation" or the like; the term "example" is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; the terms "a" or "an" should be read as meaning "at least one," "one or more" or the like; and adjectives such as "conventional," "traditional," "normal," "standard," "known" and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future.

Likewise, where this document refers to technologies that would be apparent or known to one of ordinary skill in the art, such technologies encompass those apparent or known to the skilled artisan now or at any time in the future.

[0082] A group of items linked with the conjunction "and" should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as "and/or" unless expressly stated otherwise. Similarly, a group of items linked with the conjunction "or" should not be read as requiring mutual exclusivity among that group, but rather should also be read as "and/or" unless expressly stated otherwise. Furthermore, although items, elements or components of the invention may be described or claimed in the singular, the plural is contemplated to be within the scope thereof unless limitation to the singular is explicitly stated.

[0083] The presence of broadening words and phrases such as "one or more," "at least," "but not limited to" or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent.

Claims

CLAIMS What is claimed is:

1. A method of biomass fractioning comprising:

loading biomass into a biomass fractioning system, the biomass fractioning system comprising a reactor, wherein the reactor comprises a plurality of stacked pyrolysis stations and at least one transfer chamber, said plurality of pyrolysis stations comprising at least one first pyrolysis station and one last pyrolysis station and the at least one transfer chamber connects at least one pyrolysis station to another pyrolysis station;

transferring said biomass through said reactor from said first pyrolysis station to said last pyrolysis station to produce a solid stream and a vapor stream at the last pyrolysis station; and

directing said fuel-producing vapor stream to a catalytic column, combustion system or condensing system for conversion to fuel.

2. The method of claim 1 wherein one or more stations comprises an auger.

3. The method of claim 1, or 2, wherein the reactor is preceded by one or more stations for drying of biomass.

4. The method of any one of claims 1-3, wherein renewable chemicals are synthesized from the vapor stream.

5. The method of any one of claims 1-4, wherein adjacent pyrolysis stations provide opposing directions of flow.

6. The method of any one of claims 1-5, wherein the transfer chamber promotes mixing of the biomass thermal decomposition products as they are conveyed from one pyrolysis station to another pyrolysis station.

7. The method of claim 6 wherein the transfer chamber comprises an inlet at one end of the chamber and an outlet at the other end wherein the chamber is narrowed at at least one point between the inlet and the outlet.

8. The method of claim 7, wherein the transfer chamber outlet is wider than the inlet to create a higher pressure adjacent the inlet as compared to the outlet.

9. A biomass fractioning system comprising:

a reactor, wherein the reactor comprises a plurality of stacked pyrolysis stations and at least one transfer chamber, said plurality of pyrolysis stations comprising a first pyrolysis station and a last pyrolysis station and the at least one transfer chamber connects at least one pyrolysis station to another pyrolysis station;

a transfer conduit for transferring said biomass through said reactor from said first pyrolysis station to said last pyrolysis station;

a source of heat to pyrolyze the biomass as it is conveyed through the reactor to produce a solid stream and a vapor stream at the last pyrolysis station; and

a catalytic column for converting said vapor stream to a fuel.

10. The system of claim 9 wherein one or more stations comprises an auger.

11. The system of claim 10, wherein an auger can be oriented on a slant of 0° to 85° with respect to horizontal.

12. The system of claim 9 further comprising a station for drying of biomass.

13. The system of claim 9, wherein adjacent pyrolysis stations provide opposing

directions of flow.

14. The system of claim 9, wherein the transfer chamber promotes mixing of the biomass thermal decomposition products as they are conveyed from one pyrolysis station to another pyrolysis station.

15. The system of claim 9 wherein the transfer chamber comprises an inlet at one end of the chamber and an outlet at the other end wherein the chamber is narrowed at at least one point between the inlet and the outlet.

16. The system of claim 15, wherein the transfer chamber outlet is wider than the inlet to create a higher pressure adjacent the inlet as compared to the outlet..

17. The system of any one of claims 9-16, further comprising filters to remove heavy coke forming or particulate components from a vapor stream, whereby catalyst coking rates are further decreased.

18. The system of any one of claims 9-17, further comprising a cyclone to remove heavy coke forming or particulate components from a vapor stream, whereby catalyst coking rates are further decreased.

19. The system of any one of claims 9-18, wherein the last pyrolysis station terminates in an exit port that removes a partially and/or fully pyrolyzed biomass from the system.

20. The system of claim 10 or 11, wherein the auger comprises a transfer screw.

21. The system of claim 20, wherein the transfer screw comprises flights wherein said flights are attached to said shaft; and a plurality of structures connecting two or more of said flights, wherein design of the transfer screw promotes mixing of biomass,

wherein design of flights promotes mixing and/or vapor flow to exit ports; and whereby design of said screw promotes vapor flow and/or promotes ease of solids flow.

22. The system of claim 21, where said flights have a plurality of portions of the flight that are not present to promote vapor flow and solids mixing.

23. The system of claim 21, wherein the flight is separated into a plurality of

discontinuous flights whereby vapor can flow between discontinuous flights.

24. The system of claim 9, wherein each of said pyrolysis stations comprises an auger.

25. The system of claim 24, wherein said auger in said last pyrolysis station comprises a transfer screw with cut flights.

26. The system of claim 9, further comprising a second reactor comprising a pyrolyzer station having an auger for receiving the biomass from the first reactor and further pyrolyzing the biomass.

27. The system of claim 9, wherein the pyrolysis stations are stacked horizontally.