Patent Application
20240376384
The present invention relates generally to the efficient production of biofuel and more specifically to the production of renewable oil from woody biomass,
Biomass has been a primary source of energy over much of human history. During the late 1800's and 1900's the proportion of the world's energy sourced from biomass dropped, as the commercial development and utilization of fossil fuels occurred, and markets for coal and petroleum products dominated. Nevertheless, some 15% of the world's energy continues to be sourced from biomass, and in the global South the contribution of biomass is much higher at 38%. Biomass is well recognized as a sustainable component of a future non-fossil economy see for example: Bioenergy & Sustainability: bridging the gaps/edited by Glaucia Mendes Souza, Reynaldo L. Victoria, Carlos A. Joly and Luciano M. Verdade. SCOPE 72. Includes bibliographical references and index. ISBN: 978-2-9545557-0-6
There is a large amount of literature on the conversion of biomass to energy and fuels. The major source of terrestrial biomass is the material embodied in wood and straw which is by far the majority of biomass either cultivated or harvested from the wild. Wood and straw are known as lignocellulosics on account of their composition, namely lignin, cellulose and hemicellulose polymers that comprise greater than 90% of the dry biomass. The residual materials are minerals, and nutrients remaining from the processes of growth and respiration, along with specialized chemicals used by the plant in protection from pests, and bacterial degradation. Typically, cellulose is 50% of the polymer biomass while lignin and hemicellulose are about 25% each. Cellulose is a homopolymer comprised of cellobiose monomers, cellobiose is a dimer of glucose. With a degree of polymerization >10,000, cellulose is the major source of strength in the cell wall, and is utilized commercially in textiles, paper and board products after a pulping process that isolates it from the other polymers. Hemicellulose is a heteropolymer of different sugars with Xylose the major component along with other functional groups such as acetate. It is believed to act as a bonding agent between cellulose and the lignin in the cell wall. Lignin is also a heteropolymer primarily composed of C-9 phenyl-propane units. There are different lignin monomers depending on the degree of substitution of methoxy groups in the phenyl ring, syringols the major component of grasses, and softwoods have two, while guaiacyls in Hardwoods have only one. Lignins are the most energy rich of the 3 polymers and their aromatic composition makes them a preferred precursor for fuels and specialty chemicals.
Isolating the polymers without causing major chemical changes is challenging, and typical industrial processes such as pulping that target one of the polymers e.g. cellulose, by chemically modifying the other two polymers discussed above to make them soluble and separatable from the cellulose fibres, are not efficient.
Therefore, it is the object of this invention to provide an improved method for the recovery of oil from woody biomass that leaves the cellulose component intact and usable. Another object is to do so without forming an emulsion during the process, so that all components separate by gravity and distillation.
Described is a process comprising a series of steps for the production of renewable oil from woody biomass. This oil can be processed directly by a traditional petroleum refinery producing transportation fuels or other similar downstream petroleum products. The cellulosic fraction, substantially reduced in lignin, can be used in various downstream processing. The method involves a series of steps: step 1, comminuting woody biomass to pass a #20 screen mesh size: step 2, mixing the pulverized material with ethanol, elevating the temperature of the mixture at atmospheric pressure, then subjecting the mixture to high shear (which comprises a pretreatment step): step 3, elevation of the wood/ethanol mixture to supercritical conditions while mixing: Step 4, recover the ethanol for reuse via distillation. The resulting oil contains lignin, solid cellulose, and carbohydrate derivatives. After filtration to remove the cellulosic fraction in Step 5, the water soluble materials are removed in a counter current wash to purify the hydrophobic oil. The resulting products are a hydrophobic free flowing oil, cellulose, and a carbohydrate derived water soluble stream. Applications of the products include co-firing and co-processing of the oil with hydrocarbon streams, use of the cellulose in biochemical conversion, and solid products. The aqueous carbohydrate stream can provide sufficient energy to supply the entire process via anaerobic digestion to biogas to generate heat and electricity.
This invention relates to an improved method for processing woody biomass into two distinct usable products comprising 100% of the biomass. Described is a process comprising a series of steps for the extraction of renewable oil from woody biomass. This extracted oil can be processed directly by a traditional petroleum refinery producing transportation fuels or other similar downstream petroleum products. The method involves a series of steps: Step 1, sizing chipped woody biomass to passing #20 screen mesh size. Step 2, mixing small particle size woody biomass with ethanol (1 part biomass to 8 parts ethanol by weight), elevating the temperature of the mixture to about 65° C., then subjecting the mixture to high shear (which comprises a pretreatment step) at atmospheric pressure. Step 3, elevation of the wood/ethanol mixture to supercritical conditions (about 285° C. and 2000 psi) while mixing. During this supercritical step, oil is separated from the celluosic component and ETOH is reacted with the free lignin. Step 4, separates the spent biomass from the oil rich ethanol and recovers the ethanol for reuse via distillation. Step 5, water wash the oil as required to purify. The resulting two products are a liquid that is an energy dense, thermally stable, water free, sugar free non-corrosive to carbon steel, and is a free-flowing liquid suitable for use as fuel oil or for upgrading to transportation fuels, the second product is a clean lignin free cellulosic biomass suitable for use in a furnace or as feed in the pulping industry.
The dried oil stream product has a low total acid number (TAN) and is a free flowing liquid at close to ambient temperatures and is miscible with hydrocarbon fluids at up to 15% mass fraction, and is suitable for hydrodeoxygenation to manufacture, aromatic chemicals, renewable diesel and SAF.
A more complete understanding of the present invention and benefits thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings in which:
Chipped wood enters the Wood Chip Grinder I which reduces the size allowing the wood to pass a #20 mesh filter. This passing 20 mesh wood then enters the Wetting Wessel 2 with a flow of heated ethanol (ETOH), via stream A, while being mixed under low shear creating a proper mix ratio of ETOH to wood (approximately 8:1).
This mixture enters the High Shear Mixing Vessel 3 through a Heat Exchanger 14 at approximately 65° C. The High Shear Mixing Vessel further reduces the wood's particle size while also working the ETOH into pore spaces displacing water. Oil is beginning to be released during this phase.
The high sheared mixture (at atmospheric conditions) is then pumped to the supercritical reactor 4 identified on the figure as High Temp & Pressure Extraction Vessel. During this phase, the temperature and pressure is increased bringing the mixture to supercritical ETOH conditions (excess of 240° C. and 1300 psi). This mixture is held at these conditions while being mixed (low shear) in supercritical reactor 4. In our tests, operating conditions of 285° C. and 2100 psi mixing or 15 to 30 minutes at stabilized temperature and pressure yielded acceptable results.
After a predetermined mixing time determined by lab experiments, which for the disclosed embodiment was between 15 min to 60 min, this mixture is then cooled in Exchanger 5 to approximately 40° C. and atmospheric pressure. The energy recovered is used for heating incoming materials such as the ETOH. This cooled mixture then enters the screw extruder 6 which separates the liquid and solid phases. All ETOH is recovered for reuse at ETOH Recovery and Storage 13.
Transfer Supercritical mixture through a heat exchanger to lower temp and pressure to 40C and atmospheric pressure. Energy collected will be used to preheat incoming materials for steps above (pretreatment and supercritical). The cooled mixture is passed through a 0.5-micron absolute filter bed (not shown) to remove all cellulosic material (wood fibers).
The solid phase (cellulose and hemicellulose) is dried in wood dryer 7 and used for such applications as furnace feed. The ETOH/Oil phase is centrifuged at centrifuge 8, or a cyclone can be used for this purpose, to remove very fine particulates. This cleaned mixture then is distilled in Ethanol (ETOH) Distillation Column 9 under conditions to recover the ETOH for reuse. In our lab experiments these conditions were generally approximately 140° F. at 8 psi vacuum.
The oil (free of ETOH) is then subjected to the Counter Current Water Wash Column 10 to remove sugars, and impurities like metals, phenols, etc.) The approximate ratio of water/oil is approximately 10:1. The resultant mixture is then sent to the flash evaporator 11 to remove water. The oil is then sent to storage 12, ready for use as a transportation fuel feedstock or other.
The figure identifies other components, the purpose of which will be understood by a person skilled in the art.
The dried purified oil can be tested for compliance of the applicable standards by analytical tests described below
Viscometry measurements were performed at 40 degrees C., with a Brookfield DV-II+Pro viscometer with small sample adaptor and spindle SC4-18.
To determine the higher heating value (HHV) of the bio-fuels and different phases, approximately 1 g of samples were burned in an IKA C5003 type bomb calorimeter under bar oxygen pressure and in dynamic method of operation. Standardization and thermochemical corrections followed the ASTM D 240 test method. Samples with high water content were combusted with paraffin strips as spiking material (45.78 MJ/kg).
The total acid number (TAN) and water content of the fuel samples were determined by Aquamax TAN and Aquamax KF Volumetric titrators (GR Scientific) according to ASTM D 664 and ASTM E 203 standards.
The elemental composition analysis of the samples (C, H and N) was carried out at 900 degrees C. by a Flash 2000 analyzer and the oxygen content (O) was calculated by difference.
Sugar compounds analyzed by gas chromatography-mass spectrometry (Agilent 7890A GC-MS) after a standard trimethylsilylation with HMDS. The injection unit temperature of the GC was 300 degree C. and it was coupled to a HP-VOC column. The GC oven was heated from 45 degree C., to 280 degree C. at a rate of 3 degree C./min while the system was purged with helium carrier gas with a split ratio of 25. Separated compounds were recorded with the Agilent 5975C mass selective detector with ionization energy of 70 eV and a scanning range of m/z 30-550 in the full scan mode.
Wood bio mass (sawdust) made of a composite of pine, spruce, and redwood with a H2O % of 12.5 was sieved collecting the passing #20 sieve size material. 240 grams of this sawdust was placed in a 4000 ml beaker. To this beaker, 2040 grams of 200 proof ETOH was added and stirred by hand to homogenize. This beaker with mixture was then placed in a heating mantle with probe and the temperature raised to 65° C. The Silverson L4R high shear mixer with a single shear head is then lowered into the mixture as the temperature was rising. The mixer rpm was set at 5000. Once 65° C. was reached, the mixture was sheared for 30 minutes. At 30 minutes the mixer was stopped and head raised from the mixture. The mixture was allowed to cool to 40° C., then mixed by hand and poured through a 0.2 micron filter bed pulled by vacuum to remove all wood particles. The ETOH oil mixture was then placed in a rotary evaporator and the ETOH recovered. All flasks weighed before and after. The yield of biocrude was 9.5%.
Wood bio mass (sawdust) made of a composite of pine, spruce, and redwood with a H2O % of 12.5 was sieved collecting the passing #20 sieve size material. 240 grams of this sawdust was placed in a 4000 ml beaker. To this beaker, 2040 grams of 200 proof ETOH was added and stirred by hand to homogenize. This beaker with mixture was then placed in a heating mantle with probe and the temperature raised to 65° C. The Silverson L4R high shear mixer with a single shear head was then lowered into the mixture as the temperature was rising. The mixer rpm was set at 5000. The mixture was high sheared for 15 minutes as the temperature was rising. At the end of 15 minutes, the temperature of the mixture just reached 65° C. The mixer was stopped, and head raised from the mixture. The mixture was allowed to cool to 40° C., then mixed by hand and poured through a 0.2-micron filter bed pulled by vacuum to remove all wood particles. The ETOH oil mixture was placed in a rotary evaporator and the ETOH recovered. All flasks weighed before and after. The yield of bio-oil was 2.9%. This oil was set aside to combine with oil from Example 3.
The recovered wood bio mass from Example 2 above was placed in an oven to assure all ETOH/H2O was removed (dried to constant weight). 10 grams of this dried biomass was mixed 10:1 with ETOH and placed in an autoclave reactor. Following the following procedure.
Apparatus: 300 cc AE Hast C autoclave fitted with a SS type K TC, mag drive internal stirrer, internal cooling coils and ports for N2 purge, pressure sensing and venting. The lower reactor section is heated with an external heater controlled with an electronic temperature controller.
Procedure: Prior to the first experiment the autoclave was cleaned mechanically with brushes and abrasive pads and finally with hot ethanol. The autoclave was then purged several hours with dry nitrogen. The autoclave is then opened and the premeasured wood powder and dry ethanol is added to the autoclave. The autoclave is then reassembled with a fresh PTFE gasket and the head bolts torqued to the prescribe gasket crush. A brief N2 purge is performed (˜10 minutes) prior to the application of heat. All ports are blocked in except the pressure gauge and the stirrer is started at 500 rpm. Monitoring of the run progress includes logging of the heater jacket temperature, internal reactor temperature and system pressure. After the run is complete the heater is switched off and compressed air is delivered to the cooling coils. The reaction mix is cooled to <100° F. prior to opening the autoclave.
Product recovery: The reaction mix is quantitatively transferred to a filter funnel fitted with a Whatman #41 paper filter. The filtrate is collected in a tared glass bottle. The autoclave is flushed with clean ethanol repeatedly to achieve the complete transfer of the oil and treated wood to the filter funnel. The treated wood mass on the filter is also washed with clean ethanol to remove as much of the residual oil as possible. The combined ethanol, oil and washings are then placed on a low temp hot plate and evaporated to dry oil with a stream of nitrogen. Multiple weights of the final oil are taken near the end of the evaporation process to confirm the removal of the ethanol. Yield including oil from Step 2 is 33.9%
We performed 10 runs. Runs 1 to 4 were to perfect the procedure. Run #'s 5-10 were to produce enough oil for complete testing.
Reactants: 10 grams of pre-sheared dried (overnight@110° C.) wood powder (Eucalyptus) added to 87 cc of Ethanol (200 proof Aldrich Cat #459828, water <=0.2 wt %)
Apparatus: 300 cc AE Hast C autoclave fitted with a SS type K TC, mag drive internal stirrer, internal cooling coils and ports for N2 purge, pressure sensing and venting. The lower reactor section is heated with an external heater controlled with an electronic temperature controller.
Procedure: Prior to the first experiment the autoclave was cleaned mechanically with brushes and abrasive pads and finally with hot ethanol. The autoclave was then purged several hours with dry nitrogen. The autoclave is then opened and the premeasured wood powder and dry ethanol is added to the autoclave. The autoclave is then reassembled with a fresh PTFE gasket and the head bolts torqued to the prescribe gasket crush. A brief N2 purge is performed (˜10 minutes) prior to the application of heat. All ports are blocked in except the pressure gauge and the stirrer is started at 500 rpm. Monitoring of the run progress includes logging of the heater jacket temperature, internal reactor temperature and system pressure. After the run is complete the heater is switched off and compressed air is delivered to the cooling coils. The reaction mix is cooled to <100° F. prior to opening the autoclave.
Product recovery: The reaction mix is quantitatively transferred to a filter funnel fitted with a Whatman #41 paper filter. The filtrate is collected in a tared glass bottle. The autoclave is flushed with clean ethanol repeatedly to achieve the complete transfer of the oil and treated wood to the filter funnel. The treated wood mass on the filter is also washed with clean ethanol to remove as much of the residual oil as possible. The combined ethanol, oil and washings are then placed on a low temp hot plate and evaporated to dry oil with a stream of nitrogen. Multiple weights of the final oil are taken near the end of the evaporation process to confirm the removal of the ethanol. Yield including oil from Step 2 is 33.9%
While the invention has been described with reference to a preferred embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to a particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/500,656 filed May 8, 2024, titled “High Shear Method to Separate Fractions in Woody Biomass”, which is hereby incorporated by reference herein for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 63500656 | May 2023 | US |
