Not Applicable.

DESCRIPTION OF THE INVENTION

1. Technical Field.

The present invention relates to the pyrolytic conversion of particulate substrates into a renewable fuels and chemicals. In particular, it relates to a fast pyrolysis system for the conversion of particulate materials into bio-oil, from a pyrolytic vapor reaction product.

2. Background Art.

Processes for the pyrolysis of particulate biomass materials into oxygenated hydrocarbon vapors are generally known in the art. Such systems are generally known to impart a high-heat-flux to organic substrates in order to cleave their chemical bonds, and to transform the substrate material into molecular fragment components. Various configurations employ the use of fluidized, transported, ablative, or vacuum bed reactors are presently in use. Fluidized and transported bed reactors have become the most widely accepted processes, in the industry, for the pyrolysis of particulate materials into smaller oxygenated hydrocarbon vapor fragments for use as renewable a energy fuel or chemical.

Various configurations of pyrolysis reactors have been used to transport the particulate substrates, to be vaporized, across a heated surface. For example, such reactors employ the use of screw type augers, which propel the particles through a heated barrel surrounding the particles, reactors which entrain the particles in an inert vapor directed to flow across a heated surface, and reactors which channel the particles through heated plates or rollers.

One screw auger wood gasification apparatus, which has found acceptance in the field, is disclosed in U.S. Pat. Ser. No. 7,144,558, to Smith et al., filed 1 July, 2004. This apparatus uses an auger to transport a cellulosic substrate through an auger-housing where it is heated by friction in order to vaporize the cellulosic material into a gas. Together, the auger and housing define a spiral void through which the cellulosic material is propelled, from an inlet to the outlet, which is continually decreasing in volume. The ever decreasing volume of the void increases pressure on the cellulosic material so that the frictional heating is maximized until the material reaches a heat of vaporization. This disclosure is incorporated by reference, as though fully set forth herein.

While the foregoing processes offer some utility in the use of pyrolysis reactors to produce a gas, a major disadvantage with each lies in the fact that, while they do provide for the conversion of the substrate into a useable hydrocarbon gas, they do not provide for the conversion of larger particulate substrates into pyrolysis vapors for conversion into bio-oil. Moreover, they are not designed for use in remote locations where the renewable substrate materials are located. Thus, the biomass substrates must be transported from their natural location, for subsequent processing, which is costly, labor intensive, and time consuming. Thus, it is desirable to provide a process intensified fast pyrolysis system which is capable of generating pyrolysis vapors, from a particulate substrate, for conversion into bio-oil fuels or chemicals, but which is also simple in design and configured for deployment in remote locations. The present invention satisfies these needs.

DISCLOSURE OF THE INVENTION

It is therefore an object of the present invention to provide a process intensified fast mobile pyrolysis system which is capable of providing for the conversion of the particulate substrate into pyrolysis vapors for conversion into bio-oil fuels and chemicals

It is another object of the present invention to provide a process intensified fast mobile pyrolysis system which is simple in design and construction.

It is yet another object of the present invention to provide a process intensified fast mobile pyrolysis system which is capable of deployment and operation in remote locations. To overcome the problems associated with the prior art methods, and in accordance with the purpose of the present invention, as embodied and broadly described herein, briefly a fast pyrolysis system is provided which includes an auger housing having an inner and an outer wall and an inlet and an outlet. A rotatable auger is mounted in the housing. The auger has surfaces defining at least one spiral channel. The spiral channel is tapered from a first depth adjacent the housing inlet to a second lesser depth adjacent the housing outlet. The auger is rotatable to propel particulate materials from the housing inlet toward the housing outlet to heat the particulate material to a first temperature sufficient to convert at least a portion of the particulate material into a vapor. A heat exchanger is connected about the outer wall of the auger housing for transferring a heat of vaporization from a heated medium to the auger housing inner wall. A filter assembly is connected downstream to the housing outlet in order to filter a converted char portion of the particulate material from the vapor. A condenser, connected downstream to the filter assembly, is adapted to remove a heat of vaporization from the vapor stream so that a bio-oil condensate is produced.

Additional advantages of the present invention will be set forth in part in the description that follows and in part will be obvious from that description or can be learned from practice of the invention. The advantages of the invention can be realized and obtained by the system particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and which constitute a part of the specification, illustrate at least one embodiment of the invention, and together with the description, explain the principles of the invention.

FIG. 1 is a schematic drawing of the present invention.

FIG. 2 is a flow chart of the process in accordance with the present invention. BEST MODES FOR CARRYING OUT THE INVENTION

Unless specifically defined otherwise, all technical or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

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

The term "vapor", as used herein, means a phase of a pure substance including a liquid-vapor mixture, saturated vapor, superheated vapor or vapor / gas mixture.

The term "gas", as used herein, means a phase of a pure substance including an ideal gas, real gas, gas mixtures, or a gas / vapor mixture. Although any of the methods and materials similar or equivalent to those described herein can be used in the practice or deployment of the present invention, the preferred methods and materials are now described. Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings wherein like numerals represent like features of the invention.

Referring now to the drawing figures, this invention relates to the new use of a screw type auger gasification reactor for converting particulate substrates 12 into a bio-oil 13 renewable fuel, or chemical, from pyrolysis vapors 14. In the preferred embodiment, of the present invention, the system first deopolymerizes the particulate substrates 12 feedstock in a jacketed ablative pyrolysis reactor into char fines 16, oxygenated hydrocarbon pyrolytic vapors 14, and fuel gases. The char fines 16 are filtered from the vapors 14, and the vapors 14 are thermally quenched into a bio-oil 13 product, and an off-gas 19 containing smaller molecular weight hydrocarbons. It can be appreciated, by one of skill in the art, that certain operational parameters including, without limitation, particulate substrate 12 composition, agitation speed, flow rates, and pyrolysis temperature can be widely varied within the system 10 in order to achieve a predetermined conversion efficiency, together with bio-oil 13 quality, all of which enables the use of the present invention in a wide variety of applications.

Referring now to FIG. 1 , shown generally at 10 is the preferred embodiment of the system in accordance with the present invention. The system 10 generally includes a pyrolysis reactor which is similar in design to the gasification reactor shown and described in U.S. Pat. Ser. No. 7,144,558, to Smith et al. Thus, the Smith et al., disclosure is incorporated by reference, as though fully set forth herein. In the present invention, the ablative pyrolysis reactor includes a generally U-shaped auger housing 20 having inner and outer walls.

The auger housing 20 includes an inlet 21 aperture and an outlet 24 aperture. The inlet 21 aperture is configured for loading the reaction vessel with a particulate substrate 12 feedstock, to be converted. The outlet 24 aperture is configured to discharge the pyrolytic reaction products, propelled out of the pyrolysis reactor, including char fines 16 and pyrolysis vapor 14, and fuel gases into the filter assembly 30. The inlet 21 and the outlet 24 apertures are spaced apart along two spiral channels 25 and 26, connected by a transverse channel 27, which is defined within the housing by the augers 28, 29 and the inner walls of the housing 20. The transverse channel 27 includes a valve 8 for rejection of water vapor from the system 10. Also, not shown, but specifically contemplated herein, is the use of an ablative pyrolysis reactor which includes a single auger 28, contained within a single spiral channel 25, in order to generate the vapors 14 to be thermally quenched. The first auger 28 is preferably driven by a power take-off 72

assembly connected to an internal combustion engine 70. The second auger 29 is desirably driven from the first auger 28 drive pulley 76 by a driven pulley 78 and a drive belt 79. However, as can well be appreciated by one of skill in the art, any drive assembly, which is well known, may be used in order to drive the second auger 29, including, without limitation, a second internal combustion engine (not shown) or any arrangement of a drive gear and driven gear assembly (not shown). The drive pulley 72 is connected to any drive shaft assembly, well known in the art, of an internal combustion engine 70. The augers 28, 29 include spiral blades 22, 23 which, when rotated by the power take off assembly, propel the particulate materials 12 through the auger housing 20, from the inlet 21 to the outlet 24, for discharge of the vapors 14 and char 16 reaction products into the filter assembly 30. The U shaped reactor further includes a water vapor relief valve 8 for venting water vapor resulting from drying the particles 18 in the first spiral channel 25.

The gasification reactor disclosed in the incorporated reference yields reaction products in the form of dried particles 18, a gas, and char 16. In accordance with the present invention, the ablative pyrolysis reactor is heated with a heat exchanger, such as a jacket 2, surrounding the auger housing 20, having a void for circulating a heated medium 4. The heated medium 4 is of any medium well known in the art such as steam, superheated steam and, but in the preferred embodiment is an exhaust gas 74 flowing from the internal combustion engine 70. In this manner, the system is similar in design to those jacketed reaction vessels well known in the art, and may be operated as an Open' system, where all the materials which compose the system may enter and leave it, such as 'plug flow' reactor, typically defined as a batch type process in an 'open' system design, or as a continuous process where all the materials continually enter and leave the process. A steam generator assembly 80, is included as a component of the system in order to generate superheated steam for use as the heated medium 4. However, in the preferred embodiment the heated medium is an exhaust gas 74 product of the internal combustion engine 70.

In practice, the auger 28, 29 and housing 20 components of the system 10 function to receive wood particulate substrates 12 into the inlet 21. The wood particulate substrates 12 are propelled through the housing 20 by the spiral blades 22, 23 and increasingly compress the particulate feedstock causing frictional heating of the particles 12 between the housing 20 and the auger 28, 29 surfaces. The frictional heating normally yields a gas and the char fines 16. Further heating of the housing 20 with the heat exchanger jacket 2 enhances the operating temperature of the system 10 to a temperature in the range of 300° - 700° C, thereby generating the pyrolysis vapor 14 reaction product to be condensed.

The heating medium 4 can be introduced at any point in the jacket 2, so that the jacket 2 optimally reaches the desired temperature profile, which is dependent upon the particular material to be vaporized. This exchange of heat from the heated medium 4 to the housing 20 walls is also advantageous in that it dramatically reduces the overall amount of energy input into the system 10. In this manner, the wood particulate substrates 12 reach a temperature which is sufficient to drive off free-moisture in the first channel 25 and, upon further heating in the second channel 26, transition the particles into a plastic state which is helpful in molding the particles to the interior surfaces of the housing 20 and the auger 28, 29 forming a substantially vapor-tight pressure seal. The system 10 is further heated with the heated medium 4 in the jacket 2 until it reaches a temperature at which the solid wood particulate substrate 12 is transformed into the pyrolytic vapors 14 containing carbon, hydrogen, and oxygen. The pyro lytic vapors 14 escape through the outlet 24 and into the filter assembly 30 for separation and removal of the char fines 16 from the pyrolytic vapors 14 so as to not contaminate the composition of the resulting bio-oil 13 product and fuel gases.

The system 10 is powered by an internal combustion engine 70. The engine 70 may be fueled completely, or in part, from the off-gas 19 which is vented under pressure, from the condenser 50. The off-gas 19 typically contains small chain hydrocarbons, such as butane, pentane, and propane. It is thus desirable to provide a gas driven internal combustion engine 70 to drive the augers 28, 29 which propel the particulate substrate 12 feedstock through the drying and pyrolysis zones of the system 10. The internal combustion engine 70 may, but need not, also operate to drive a pump (not shown) for circulating the heated medium 4 through the heat exchanger jacket 2, such as by directing the exhaust gas 74 from the engine 70 to the annular space within the heat exchanger jacket 2. In this manner, the temperature, or the exhaust gas 74, may be closely matched to a desired heat of pyrolysis for exchange to the housing 20 walls. The annular space of the heat exchanger jacket 2 is configured so that a pressure drop, across the engine exhaust 74 system, is not compromised while maintaining adequate exhaust gas velocities which are necessary in order to provide the desired heat transfer and temperature distribution across the reactor auger housing 20 for a given feedstock. Because exhaust gas 74 is a relatively poor conductor of heat, the auger housing 20 is of a design and constructed of materials, which are well known in the heat transfer art, to effectively capture the heat in the exhaust 74 gas and to transfer that heat to the auger housing and spiral channel 25, 26 of the pyrolysis reactor portion of the system 10. In this manner, both thermal and rotational work is derived from the pyrolysis gas 19 stream thereby maximizing the overall conversion efficiency of the system.

The filter assembly 30 is housed in a housing 31. The filter assembly 30 is a hot vapor filter 32 having an inlet 34 for receiving the vapors 14. The inlet 34 is connected to the outlet 24 of the pyrolytic reactor. The filter 32 is preferably a rotating drum having a scraper blade or other solids "filter cake" removal device. As the drum rotates the scraper blade removes particulate cake build up so that the char fines 16 are separated in a continuous process. In the alternative, one or more hot vapor filters could be included for use at locations either up or downstream the post pyrolysis catalytic reactor 40, depending on the need to prevent components in the char 16 from interfering with the chemical reactions in the post pyrolysis catalytic reactor 40 as described below. Pore size of the filter 32 is established in a predetermined range so that char fines 16 are removed from the vapor 14 stream and discharged, as a by-product of the pyrolysis. The filter assembly 40 is preferably configured so as to allow the system, in accordance with the present invention, to operate in a continuous 'open' process so as to prevent clogging of the pores with the char 16. In the preferred embodiment, the filter assembly 30, is also jacketed 2 for circulation of the heated medium 4 around the filter assembly 30 housing in order to thermally enhance the filtration step, and prevent the premature condensation of the pyrolysis vapors in the filter cake, thereby improving the operability of the system 10. The pyrolytic vapors 14 are thermally quenched in a condenser 50.

The condenser 50, in accordance with the present invention is of any construction well known in the art, such as a surface condenser or spray condenser. In the preferred embodiment the condenser is a spray condenser. Other modifications, to the present invention, may be incorporated in order to reduce the net energy input into the system 10, improve the conversion efficiency of the system 10, and to improve the stability of the bio-oil 13 product. To this end, the system 10 may, but need not, include the use of certain catalytic materials, deposited along the inner wall of the auger housing 20, in order to further depolymerize and/or deoxygenate the particulate substrate 12 feedstock during the pyrolysis step. Selection of the type of catalysts for this use is largely dependent upon the chosen dynamics of the system, and the bio-oil 13, to be produced. It follows then: that one of the advantages with the present invention lies in its flexibility, as the system 10 is easily tailored for the conversion of a specific substrate, to be vaporized, and a specific bio-fuel 13 or chemical, to be produced.

In yet another embodiment of the present invention, a post-pyrolysis catalytic reactor 40 may, but need not, be connected to the filter assembly 30 for the catalytic manipulation, such as deoxygenation, of the pyrolytic vapors 14 prior to thermal quenching in the condenser 50. With this embodiment, the post- pyrolysis catalytic reactor 40 includes an inlet 42, connected to the filter assembly 30 outlet 36, and an outlet 46 connected to the condenser 50 inlet 52. The catalytic pyrolysis reactor 40 is preferably configured to include a plurality of multiple tubes 44, such as a shell and tube heat exchanger, which include the direct introduction of suitably small fragments or beads of catalytic materials into the tubes or in the form of catalytically active static in-line mixers. These catalytically-active materials are either prepared by depositing a catalyst onto an inert, abrasion-resistant substrate, either monolithic or porous, or are available as ceramic glass based catalysts having the desired catalytic formulation and ability to be fabricated into desired shapes, such as in line mixers. The addition of these catalysts to the tubes allows the catalysts to become intimately involved in the mixing process and achieve good contact with the raw pyrolysis vapors, to achieve desired chemical reactions.. These glass ceramic catalysts are particularly suited for producing catalysts suitable for use in harsh environments such as the environment found in the pyrolysis reactor vessels and catalytic reactor. These catalytic static inline mixers are desirably fabricated from a glass ceramic material similar to those shown and described U.S. Patent Ser. No. 7,449,424, to Felix et al., filed 8 March 2005, and incorporated herein by reference. Other catalyst formulations may be used in the fabrication of the static in-line mixers depending on the desired chemical manipulation of the raw pyrolysis vapors 14 exiting the pyrolysis reactor. In addition, additional hydrogen and other hydrocarbon gases may, but need not, be introduced at the catalytic reactor 40 inlet 42 again, in formulation, depending on the desired chemistry of the bio-oil 13 product to be produced. The static in-line catalytic mixers combine an intense mixing of the pyrolysis compounds and selected gases in a very low pressure drop environment, together with a precise temperature control in the reaction obtained by adjusting the flow rate of a heat transfer fluid on the shell side of the reactor tubes 44. It can also be appreciated that the reactor length is calculated at an optimum length as a function of the desired residence time.

In yet another embodiment of the present invention, a hydrogen membrane separator 60 is connected to the condenser off-gas line 62 to recycle hydrogen from the off-gas 19 back into the system 10. The hydrogen separation membrane 61 is connected downstream from the condenser 50 in order to separate hydrogen from the off-gas 19 of the condenser 50 prior to directing the off-gas 19 into the intake manifold of the gas fueled internal combustion engine 70. The hydrogen may, but need not, be recycled at various points along the system such as a point which feeds it back into the pyrolytic reactor auger housing 20 or just upstream from the catalytic reactor 40. In this manner, the hydrogen stream is then directed to an inlet on the auger pyrolysis reactor housing 20 at a location where compression of the feed material has formed a pressure seal to prevent the hydrogen from leaking back through the inlet 21. The hydrogen is then present during the catalytic pyrolysis reactions (either at the housing barrel surface, post pyrolysis catalytic reactor, or both) further enhancing the ability to catalytically manipulate or deoxygenate the bio-oil 13 product.

Collectively the foregoing embodiments of the invention disclose a process intensification scenario which is capable of having a high volume throughput of organic materials in a relatively small process footprint. It can be appreciated that the foregoing embodiments will be integrated together in such a manner that heat and process flow management is accomplished with a variety of well known process sensors, valves and microprocessor controllers which may, but need not, be useful in a computer control of certain parameters within the system. Referring now to FIG. 2, where it is shown a flow chart of the process of the system in accordance with the present invention, in use the particulate substrate is treated by ablative pyrolysis 100 yielding bio-oil vapor and char reaction products 200. The bio-oil pyrolysis vapor and char are filtered 300 in order to remove the char fines 325 component, so as not to contaminate the resultant bio-oil product 350. The pyrolysis vapor may or may not be

deoxygenated in the presence of a catalyst 400. The pyrolysis vapor is then condensed 500, resulting in the bio-oil 350 condensate and an off-gas 550. The off-gas 550 passes through the hydrogen membrane separator for the separation of hydrogen 600 from the separated off-gas 560 and the hydrogen may be recycled back into the system at points either downstream from the condenser 400, the ablative pyrolysis reactor 100, or both. The off-gas 550 is finally used to fuel the internal combustion engine 700. Depolymerization and/or deoxygenation catalysts may be deposited 800 on the inner walls of the ablative pyrolysis 100 reactor in order to further enhance the process.

The present invention is advantageous in its ability to process larger particles than those used with traditional biomass fast pyrolysis systems. When integrating together all of the foregoing embodiments as elements in the system, the present invention also provides a new and useful process intensification system ideally suited for small scale mobile applications such as those deployable for use in remote locations. In contrast, it can also be appreciated that the apparatus and process, in accordance with the present invention, is also capable of scaling up, in size, or coupled, in sequence, with one or more of the foregoing systems in order to provide a large-scale process for bio-oil production utilizing the same technical embodiments described herein.

While the present invention has been described in connection with the embodiments as described and illustrated above, it will be appreciated and understood by one of ordinary skill in the art that modifications may be made to he present invention without departing from the true spirit and scope of the invention, as broadly described and claimed herein.