Patent Application
20130134351
The present disclosure is directed to systems and methods for the conversion of biomasses to alternative petrochemical feedstock. More specifically, the present disclosure is directed to the recomposition and conversion of biomasses to alternative petrochemical feedstock.
Lignocellulosic biomasses typically refer to plant biomasses that are composed of cellulose, hemicelluloses and lignin. The carbohydrate polymers (cellulose and hemicelluloses) are tightly bound to the lignin. Typically, lignocellulosic biomasses can be grouped into four main categories: (1) agricultural residues (including corn stover and sugarcane bagasse), (2) dedicated energy crops, (3) wood residues (including sawmill and paper mill discards) and (4) municipal paper waste. Lignocellulosic biomasses can be employed as a sustainable source of energy and can be a valuable alternative to fossil fuels.
PCT publication WO2009064204 relates to a process for the treatment of a lignocellulosic biomass in the form of a feedstock involving a high pressure hydrothermal processing system and a process for treating organic or waste materials. The process includes a pressurizing section, a processing section and an output section. In operation, the pressurizing section pressurizes a charge of a feedstock, the processing section heats and processes the pressurized feedstock and then cools a resultant product stream. The output section depressurizes the product stream before discharging the product.
PCT publication WO2009028969 relates to a process for isolating high grade lignin polymers derived from plant materials as well as methods for isolating lignin from plant materials. The publication also relates to isolated lignin and other extraction products derived from such materials.
PCT publication WO2007129921 relates to an integrated process for efficient and cost effective use of plant biomass for the production of ethanol, natural lignin, xylose and other co-products.
Improved systems and methods for the recomposition and conversion of biomasses to alternative petrochemical feedstock are herein disclosed.
Systems and methods for the recomposition and conversion of biomasses to alternative petrochemical feedstock are herein disclosed. According to one embodiment, a process involves reducing the particle size of at least one constituent of a biomass feedstock, removing at least one constituent from the biomass feedstock and adding at least one constituent to the biomass feedstock.
The foregoing and other objects, features and advantages of the present disclosure will become more readily apparent from the following detailed description of exemplary embodiments as disclosed herein.
The following figures form part of the present specification and are included to further demonstrate certain aspects of the present disclosure. The disclosure may be better understood by reference to one or more of the figures in combination with the detailed description of specific embodiments presented herein. Embodiments of the present disclosure are described, by way of example only, with reference to the attached figures, wherein:
It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the example embodiments described herein. However, it will be understood by those of ordinary skill in the art that the example embodiments described herein may be practiced without these specific details. In other instances, methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein.
A. Recomposition and Generation of Aqueous Biomass Slurries
Typically, cellulosic biomasses, such as dry matter feedstocks, seaweed, algae, wood particles and other cellulosic materials have a propensity to separate if allowed to stand. The separation of a cellulosic biomass can result in a two phase system including a water phase on top of hard matter phase. The separation of a raw biomass feedstock prevents the feedstock from being pumped and processed into alternative petrochemical feedstock.
In an exemplary method for the recomposition of biomass, raw biomass material can be recomposed into an aqueous biomass slurry. The aqueous biomass slurry can include a raw biomass material. The raw biomass material can include, but is not limited to, constituents such as, a lignocellulosic biomass, a cellulosic biomass, chitin, plant matter, plant waste, algae, and/or any other biological mater or combinations thereof that can be converted to alternative petrochemical feedstock, such as crude oil, hydrocarbons or green chemicals used, for instance for the production of plastic.
The raw biomass material can be recomposed into biomass particles of predetermined sizes in order to limit separation of the recomposed biomass material. The recomposed biomass material can be used in a feedstock for conversion to alternative petrochemical feedstock, such as crude oil, hydrocarbons or green chemicals used, for instance for the production of plastic. Optimal variations in particle size can be achieved by grinding raw biomass material via a flour mill apparatus (e.g. alternating rotational grinding) or a hammer mill apparatus (e.g. vertical grinding in order to shatter the raw biomass material). Such milling can result in a 5% variation in particle sizes per reducing/milling stage. In an exemplary embodiment, the resulting raw biomass material consists of biomass particles varying in size from about 1 μm to about 2 mm.
The aqueous biomass slurry can also include one or more additive materials in addition to the raw biomass material. Additive materials can be mixed with the raw biomass material to achieve optimum particle size variation. Additive materials can include, but are not limited to constituents such as, water, chitin, rocks, sand, cement, algae, plant waste, wetting agents such as aqueous solutions, lignin extraction solutions such as those herein disclosed, catalysts that affect the yield of biofuel or any combination thereof. Optimal variations in particle size can be achieved by grinding additive material via a flour mill apparatus or a hammer mill apparatus as herein disclosed. The aqueous biomass slurry can contain biomass particles that are smaller in size than the additive particles. Conversely, the aqueous biomass slurry can contain additive particles that are smaller in size than the biomass particles.
It is contemplated that a wetting agent can be added to the raw biomass material to affect the yield of alternative petrochemical feedstock or the conversion of biomass in a later thermal treatment process. The wetting agent can also contain a catalyst including, but not limited to sodium carbonate, sodium hydroxide, calcium carbonate or other calcium salts. The catalyst can be added separately or with the wetting agent to affect the yield of alternative petrochemical feedstock or the conversion of biomass in a later thermal treatment process.
It is also contemplated that a biomass material or additive material such as algae can be combined with the raw biomass material (e.g., cellulosic biomass material after removal of lignin) to form the aqueous biomass slurry. In an exemplary embodiment, the algae content in the aqueous biomass slurry is about 3 to about 10% by weight relative to other constituents (e.g., cellulosic biomass material) that form the aqueous biomass slurry. The algae can be concentrated in a preliminary processing step before the algae is combined with raw biomass material to form the aqueous biomass slurry. In an exemplary embodiment, the protein structure of the algae cell wall can be altered and degraded with heat to release encapsulated water therein. The water can be removed by decantation or other means to increase the concentration of algae before adding the algae to the raw biomass material to form the aqueous biomass slurry.
In another exemplary method for the recomposition of biomass, the raw biomass material is a lignocellulosic biomass material. Lignin is removed from the lignocellulosic biomass material to form a cellulosic biomass material. The cellulosic biomass material can be recomposed by combining with additive material and/or grinding/milling to vary the particle size of the cellulosic biomass material and/or the additive material to form an aqueous biomass slurry. The recomposition can be achieved before a lignin removal process or after a lignin removal process herein disclosed.
B. Lignin Removal
In exemplary embodiments wherein a lignocellulosic biomass material is used to form the aqueous biomass slurry, a milling process can be used to grind and shatter the lignocellulosic biomass material prior to lignin removal. After the milling process, the lignin component is removed to create a cellulosic biomass material. The cellulosic biomass material can be used alone to form the aqueous biomass slurry or the cellulosic biomass material can be combined with one or more additive materials to form the aqueous biomass slurry.
In an exemplary method for the removal of lignin from a lignocellulosic biomass material, a lignocellulosic biomass material is pumped into an extraction column with a counter-current flow of a lignin extraction solution comprising short chain polar hydrocarbons including, but not limited to methanol, ethanol, propanol, isopropyl alcohol, or acetone. Water can be added to the lignin extraction solution or the solution can be free of water. Additionally, any other polar hydrocarbon capable of removing lignin from a lignocellulosic biomass material can also be added to the lignin extraction solution to extract lignin. The lignocellulosic biomass material is continuously contacted in the extraction column with a counter-current flow of a lignin extraction solution at a temperature of approximately 150° C. to 210° C. and a pressure from approximately 10 bar to 24 bar. The extraction column can be a screw contactor extraction column and the lignocellulosic biomass material can be fed and discharged through the use of cup and cone pressure plugs or feed screws. Alternatively, the extraction column can also include a simple series of ball valves. The lignin extraction solution can be flowed counter to the flow of the lignocellulosic biomass material to continuously expose the biomass material to fresh lignin extraction solution.
Lignin extraction solution entering the column can be pressure pumped to maintain the operating pressure therein and to provide a hydraulic drive to pass against the flow of lignocellulosic biomass material. Lignin extraction solution from within the column may be re-circulated through external heaters, for example, steam heaters, on a continuous basis to maintain the temperature of the extraction solution. Operating conditions such as time, temperature profile and pressure within the extraction column can be optimized to provide maximum removal of water insoluable lignin from the lignocellulosic biomass material. As the lignocellulosic biomass material exits the column and is exposed to lower pressures, a portion of the lignin extraction solution may evaporate, resulting in cooling of the now cellulosic biomass material (with lignin removed). However, subsequent to lignin removal, a portion of the lignin extraction solution can remain in the cellulosic biomass material. The lignin extraction solution can be separated from the cellulosic biomass in subsequent processing steps such as a steam stripping step.
The lignocellulosic biomass material preferably possesses a higher specific gravity than the lignin extraction solution. This can be achieved either by preparing the lignocellulosic biomass material to have a greater specific gravity or by preparing the lignin extraction solution to have a lower specific gravity. The lignocellulosic biomass material is typically introduced into the top of the vertical column 80 and valves are sequenced to effect a gradual sequential movement downward through the lignin extraction solution. Preferably, the lignin extraction solution is introduced by pumping into the bottom of the column 80. This movement is effected by opening every second valve except for the highest and lowest valves in the vertical column 80. This action can result in a series of double sized chambers which allows the lignocellulosic biomass material to descend through the open valve space to the lower end of each double chamber in the vertical column 80.
The lignin extraction solution is displaced by the movement of the lignocellulosic biomass and the lignin extraction solution moves to the upper end of each double chamber, generally through the falling lignocellulosic biomass material. After a period of consolidation, which can be for example 10 minutes, the open valves close, every second valve opens to create a new series of double chambers, and the process is repeated. The counter-current flow between the lignocellulosic biomass material and the lignin extraction solution results in a lignin extraction solution having a high concentration of lignin at the top of the column 80 and a cleansed cellulosic biomass material at the bottom of the column 80. Following this lignin removal process, the lowest valve in the vertical column 80 can be opened to deposit the cellulosic biomass material and the vacated space in the column 80 can be filled with lignin extraction solution. Likewise, the top valve can be opened to collect the extracted lignin. The top vacated space can be filled with fresh lignocellulosic biomass material for lignin removal.
The product from the top of the column can be further separated by a first separation means 81, such as a settling tank. In an exemplary embodiment, lignin sludge precipitates in the separation means 81 and lignin extraction solution and lignin sludge is removed from the separation means 81.
If necessary impurities or other material can be removed from the cleansed cellulosic biomass material from the bottom of the column 80 in a second separation means 82. The second separation means can be a distillation column, steam stripper o other means for purifying or separating material. In an exemplary embodiment, water, dirt and/or lignin extraction solution is removed from the cleansed cellulosic biomass material in the second separation means 82. The purified cellulosic biomass material can be used as feedstock in systems and processes herein disclosed to produce an alternative petrochemical feedstock that can include, but is not limited to crude oil, hydrocarbons and/or green chemicals used, for instance in the production of plastic.
C. Converting Biomass into Alternative Petrochemical Feedstock
The system 1 includes a pressurizing section 2, a processing section 3 and an output section 4. The pressurizing section 2 pressurizes the aqueous biomass slurry 7 to be processed; the processing section 3 heats and processes the aqueous biomass slurry 7, then cools a resultant raw product stream; and the output section 4 depressurizes and outputs the product stream.
The pressurizing section 2 includes a feed tank 10 connected to a first pump 11 via a conduit on which is located a non-return valve 13. The first pump includes a ram 12 that moves up and down within a cylinder and that is driven by any suitable means. However, if alternative forms of pump are used, the ram can be replaced with other suitable pumping means as would be apparent to a person skilled in the art.
The first pump 11 is configured to draw the aqueous biomass slurry 7 from the feed tank 10 and provide an initial low pressurization. For example, the aqueous biomass slurry 7 can be drawn from the feed tank 10 by moving the ram 12 to create a vacuum. This causes the aqueous biomass slurry 7 to move from the feed tank 10 to the first pump 11 via the conduit and non-return valve 13. The non-return valve 13 prevents the aqueous biomass slurry from moving back toward the feed tank 10.
The pressurizing section 2 can also contain an additive tank 14, adapted to contain an additive 14a. The additive tank is connected with an additive pump 15 that pumps one or more additives 14a to the first pump 11 via a conduit that connects the additive tank 14 to the first pump 11. This creates a pumpable aqueous biomass slurry 7 including raw biomass material and additive material 14a in the first pump 11.
A first valve 16 is positioned on a conduit connected with the first pump 11 and with pressurizing means, in the form of a second pump 17. The first valve 16 can be closed to allow the first pump 11 to mix the aqueous biomass slurry 7 with additive material 15a within the pump 11, and the valve can be opened to allow the aqueous biomass slurry 7 to be pumped from the first pump 11 to the second pump 17 via the conduit.
The second pump 17 is a high pressure pump that includes a pump housing in the form of a cylinder within which a second floating piston or ram 18 is located. The second ram 18 is able to slide back and forth along the cylinder in the usual manner. If alternative forms of pumps are used, the ram may be replaced with other pumping means as would be apparent to a person skilled in the art.
The second pump 17 is configured to pressurize the aqueous biomass slurry 7. In particular, the pump 17 is configured so that one side of the ram 18 is adapted to be in contact with a pure fluid, such as pure water, which has been pressurized independently by a conventional separate pumping system connected with the second pump 17. The other side of the ram 18 is adapted to be in contact with the aqueous biomass slurry 7 and optionally additive material 15a combined therewith.
A first valve 16 is positioned on a conduit connected with the first pump 11 and with pressurizing means, in the form of a second pump 17. The first valve 16 can be closed to allow the first pump 11 to mix the aqueous biomass slurry 7 with the additive 14a within the pump 11, and the valve can be opened to allow the aqueous biomass slurry 7 to be pumped from the first pump 11 to the second pump 17 via the conduit.
The second pump 17 is a high pressure pump that includes a pump housing in the form of a cylinder within which a second floating piston or ram 18 is located. The second ram 18 is able to slide back and forth along the cylinder in the usual manner. If alternative forms of pump are used, the ram may be replaced with other pumping means as would be apparent to a person skilled in the art.
The second pump 17 is configured to pressurize the aqueous biomass slurry 7. In particular, the pump 17 is configured so that one side of the ram 18 is adapted to be in contact with a pure fluid, such as pure water, which has been pressurized independently by a conventional separate pumping system (not shown) connected with the second pump. The other side of the ram 18 is adapted to be in contact with the aqueous biomass slurry 7 held within the cylinder or pump housing.
The system 1 works by pumping the aqueous biomass slurry 7 into the cylinder of the second pump 17 by opening the first valve 16 and actuating the first pump 11. As the aqueous biomass slurry 7 enters the second pump 17, the second ram 18 is caused to move along the cylinder and push the pure fluid out from the other end of the cylinder and into a reservoir (not shown) via an open release valve.
The second pump 17 is also connected with a second valve 19. After the aqueous biomass slurry 7 is pumped into the second pump 17 by the first pump 11, the first and second valves 16 and 19 are closed.
The pure fluid remaining in the second pump 17 is then pressurized by the separate pump (not shown). This causes the ram 18 to transmit the pressure of the fluid by pushing against the aqueous biomass slurry 7, thereby pressurizing the aqueous biomass slurry 7 in an indirect way. The second valve 19 can then be opened to allow the pressurized aqueous biomass slurry 7 to be moved from the second pump 17 to the processing section 3. The first and second valves 16, 19; first and second pumps 11, 17; and first and second rams 12, 18, all form part of the pressurizing section 2. Although the indirect pressurization has been described in relation to a pump having a cylinder with a floating ram therein, other forms of pump may be used instead, as would be appreciated by a person skilled in the art.
The system 1 can be adapted to allow the aqueous biomass slurry 7 to be moderately preheated in the pressurizing section by including heating means (not shown) along a section of the conduit, or in other suitable locations as would be readily apparent to a person skilled in the art.
The processing section 3 includes processing means for heating the pressurized aqueous biomass slurry 7 to supercritical temperatures. Typically, the aqueous biomass slurry 7 is heated to a temperature between about 250° C. and about 400° C. However, it is envisaged that the system 1 can also be used to process aqueous biomass slurry feedstock 7 at temperatures outside this range.
Although it is contemplated the aqueous biomass slurry 7 is pressurized in the pressurizing section 2, the aqueous biomass slurry 7 can be alternatively or additionally pressurized or further pressurized in the processing section 3.
Referring still to
The first stage 21 of the pressure vessel is a first tube having a first end 27 that connects with the opening to form an inlet 28 to the pressure vessel 20. The first tube or stage 21 is positioned concentrically within a second tube or stage 22 that forms the casing of the pressure vessel 20. A space 26 (preferably an annular space) is provided between the outer peripheral surfaces of the first tube 21 and the inner surfaces of the second tube 22. This space defines the second stage 22 within the processing vessel 20 and leads to the outlet 24.
The first tube 21 is shorter than the processing vessel 20 and comprises a distal end 32 that terminates before the second end 31 of the processing vessel 20. A space is provided between the distal end 32 of the first tube 21 and the second end 31 of the processing vessel 20. This space forms a reaction zone or reaction chamber 23 where pressurized, high temperature aqueous biomass slurry 7 reacts to form a raw product stream of alternative petrochemical feedstock. The inlet 28, first stage 21, reaction zone 23, second stage 22, and outlet 24 form a fluid pathway along which the aqueous biomass slurry 7, and then the raw product stream, passes through the pressure vessel 20.
Each end 30, 31 of the processing vessel 20 is sealed, except where the inlet 28 enters the vessel 20 and where the outlet 24 exits the vessel. This arrangement allows the processing vessel 20 to be used as a pressure vessel in which the same pressure is maintained within the vessel. The inner and outer surfaces of both the first and second tubes 21, 22 are heat transfer surfaces.
The aqueous biomass slurry 7 enters the first stage via the inlet 28. The aqueous biomass slurry 7 moves or is pumped through the fluid flow path defined by the first stage 21 and is heated before reaching the reaction zone 23, where the aqueous biomass slurry 7 is further heated to a desired temperature by heating means 25 that causes the aqueous biomass slurry 7 to react and form a raw product stream of alternative petrochemical feedstock.
The heating means 25 is configured to heat the pressurized aqueous biomass slurry 7 in the reaction chamber 23 up to between 250° C. and 400° C. The heating means 25 can be in the form of an element or other suitable heating means. The heating means 25 can be inserted directly into the reaction chamber 23 to heat the aqueous biomass slurry 7 or it may be adapted to be located externally from the reaction chamber 23 so as to heat the walls of the processing vessel 20 at or near the location of the reaction chamber 23.
The heating means 25 can heat the pressurized aqueous biomass slurry 7 in the reaction chamber 23 by radiation, convection, conduction, electromagnetic radiation, including microwave and ultrasonic radiation, or any combination of such heating methods or by similar heating methods. Heating means can also include use of gas turbine exhaust gasses in a co-generation arrangement.
The raw product stream and any unreacted aqueous biomass slurry 7 then moves along the fluid flow path defined by the second stage 22 where the raw product stream is cooled to an ambient or near ambient temperature, preferably at or below 80° C., before being discharged from the processing section 3 via the outlet 24.
In effect, the first and second tubes 21, 22 form a counter-flow heat exchanger, with the first tube 21 being made of a highly heat conductive material, such as a thin walled metal tube, to ensure a high heat transfer co-efficient. In addition, fins or other surface features that improve heat transfer can be incorporated onto or into the heat transfer surfaces of the processing vessel 20, tubes 21, 22 or reaction chamber 23.
The outlet 24 of the pressure vessel 20 is located on the periphery of the processing vessel 20 close to the inlet 28. However, in certain embodiments, the outlet 24 could be located at other suitable locations on the processing vessel depending on the internal arrangement of the vessel, as would be apparent to a person skilled in the art.
In one form, the volume of the processing vessel 20 is at least six times that of the swept volume of the second pump 17. This volume difference enables the aqueous biomass slurry 7 to be moved through the processing vessel in intermittent stages as the pump 17 is actuated. That is, one cycle of the pump 17 would cause a single charge of aqueous biomass slurry 7 to move one sixth of the way through the processing vessel 20, thereby allowing for a longer residence time of the aqueous biomass slurry 7 within the processing vessel 20. By allowing for a longer residence time, the aqueous biomass slurry 7 is able to be heated to the desired temperature easily and is given sufficient time to undergo the desired reaction within the processing vessel 20 to produce alternative petrochemical feedstock including, but not limited to crude oil, hydrocarbons, green chemicals, and/or water.
As mentioned above, the first and second tubes 21, 22 of the processing vessel 20 are preferably concentric, with the first tube 21 being positioned inside the second tube 22 and defining an annular space 26 between. However, it is envisaged that the first and second stages 21, 22 of the processing vessel 20 can be of different shapes and arrangements, as would be apparent to a person skilled in the art. For example, the processing vessel 20 can have a housing with an inlet and an outlet and a counter-flow heat exchange system in between. Such arrangements allow incoming aqueous biomass slurry 7 to be heated by heating means 25 and by outgoing aqueous biomass slurry 7 that has already been heated. Similarly, the outgoing aqueous biomass slurry 7 is cooled by the incoming aqueous biomass slurry 7 and by being separated from or distanced from the heating means 25.
The processing vessel 20 can have other suitable arrangements by which the aqueous biomass slurry 7 can be held under pressure while being heated and then cooled.
Turning now to the output section 4 of the system 1, the outlet 24 connects the processing vessel 20 to the output section 4 via a conduit. The discharged raw product stream of alternative petrochemical feedstock moves along this conduit to the output section 4.
The output section 4 optionally includes a high pressure gas separator 40 for separating out gases from the raw product stream. When a gas separator is used, the outlet 24 of the processing vessel 20 is connected with the inlet of the high pressure gas separator 40, which can be of a known type, so that the raw product stream moves from the processing vessel 20 to the gas separator 40 via a conduit. Any gases entrained, or formed in the processing vessel 20, and which remain within the aqueous biomass slurry 7, are able to exit the system 1 by being purged from the gas separator 40 through a purge valve 48 connected with the gas separator 40.
The output section 4 also includes a third valve 41 that is connected with the outlet 24 of the processing vessel 20 or with an outlet 42 of the gas separator 40, if the gas separator 40 is included within the system 1. The third valve 41 is also connected with a third pump 44.
The third pump 44 is a high pressure pump that acts as both a depressurizing means and as a discharge pump. In particular, the third pump 44 can include a pump housing in the form of a cylinder within which a floating third ram 45 is located. One side of the ram 45 is in contact with the raw product stream as it enters the third pump 44. The other side of the ram 45 is in contact with a pure fluid, such as water, which is the pressurized output of a separate conventional pumping system (not shown) connected with the third pump 44. As the raw product stream enters the cylinder via the open third valve 41, the ram 45 presses against the pure fluid at the other end of the cylinder and the fluid is pushed out into a reservoir (not shown) via an open release valve at the pure fluid end of the cylinder.
The third valve 41 is controlled to open at the same time as the first valve 16 in the pressurizing section 2. This allows a charge of product to leave the processing section 3 at the same time as a charge of aqueous biomass slurry 7 enters the processing section 3, via the first valve 16, without significantly changing the pressure level in the processing section 3. The release valve acts to automatically maintain the pressure within the third pump 44 at about the same pressure as in the processing system 3, and as created by the pump action of the second pump 17 as the second pump transfers the charge of aqueous biomass slurry 7 into the processing section 3. When the transfer of the new charge of aqueous biomass slurry 7 is complete and the transfer of the latest charge of product is complete, both the second valve 19 and third valve 41 are closed. Further opening movement of the third ram 45 continues. This causes the capacity of the aqueous biomass slurry 7 of the cylinder to increase, thereby depressurizing the aqueous biomass slurry 7. Preferably, the raw product stream is depressurized to ambient or near ambient levels.
Any gases that were dissolved in the raw product stream and that were not purged in the gas separation stage can then be ejected via a fourth valve 47, which is connected with the third pump 44 and which can also act to depressurize the raw product stream.
The third pump 44 is also connected with a fifth valve in the form of an outlet valve 46. This allows the depressurized raw product stream to be pumped by actuation of the third pump 44, out through the outlet valve 46, which is opened to allow the raw product stream to be discharged from the system 1.
Because the raw product stream is at an ambient or near ambient pressure, the outlet valve 46 is subject to less wear and is, therefore, more reliable than if the raw product stream was discharged through the outlet valve 46 under high pressure.
Normally, the fourth valve 47 helps to reduce the pressure of the raw product stream in the third pump 44 after the third valve 41 has closed but before the outlet valve 46 has opened, so that rapid wear is avoided when the outlet valve 46 is opened.
The systems and processes herein disclosed for converting biomass to alternative petrochemical feedstock can be used with any suitable pumping systems, as would be appreciated by a person skilled in the art. However, the preferred form of pumping systems disclosed herein are unique, because the pumps are adapted to pressurize and depressurize feedstock (e.g., aqueous biomass slurry 7) or a raw product stream by using indirect pressurizing means whereby the pumps or various pump parts are not exposed to corrosive process fluids.
A particular advantage of using this form of pumping system is that the valves and sensitive component parts of the indirect pump are in contact with the fluid or water, which is clean, and are not in contact with corrosive process fluids. Therefore, the component parts of the pump are less likely to become clogged and worn by the raw materials and chemicals within the aqueous biomass slurry 7 that may be viscous, corrosive, dirty, or of a nature that is otherwise harmful to the component parts of the pumps and valves. By pressurizing a pure fluid, such as pure water, indirect pumping methods herein disclosed can pressurize and depressurize process fluids more accurately relative to direct pressuring methods known in the art. The pumps can operate reliably to raise and lower the pressure of process fluids more accurately, because a working fluid with known properties is being used to pressurize process fluids.
Although a pure fluid in the form of pure water is preferred as the working fluid, it is contemplated that other suitable fluids (even impure, but relatively clean fluids) can be used instead.
It is important to note that when the raw product leaves the processing vessel 20 by means of the product outlet 24, the temperature of the raw product stream has been reduced to at or near ambient temperatures, preferably below 80° C. and more preferably below 50° C. The third pump 44 and the valves 41, 46, and 47, in the outlet section 4 are therefore able to operate at near ambient temperatures with the following advantages: enhanced performance of the components; low wear on the components; and prolonged equipment life. As a result, the equipment, valves, pump components and other process materials can be selected for high sealing and pumping reliability. In effect, the areas of the system 1 wherein the pressures are raised in the second pump 17 with the associated valves, and the areas of the system 1 wherein the pressures are brought down to ambient levels, are free to utilize highly efficient materials and components to provide good sealing performance without risking the effectiveness of those materials and components by subjecting them to high temperatures. The valves and pumps can be of any specification capable of withstanding high pressures and corrosive chemicals without needing to withstand high temperatures as well. Accordingly, the system 1 does not require the use of heat resistant valves in areas of high process temperature.
The reaction zone 23, and the first and second stages 21, 22 of the processing means where the temperature is raised and lowered respectively, are maintained at constant pressure and can be made from suitable materials and components that can cope with these high temperatures without being required to use moveable seals, which would otherwise be required to change pressure and which are vulnerable to high temperatures.
The system 1 can be used to remove contaminants from a aqueous biomass slurry or the system 1 can be used to produce a product, such as an alternative petrochemical feedstock containing hydrocarbons, crude oil, water and/or green chemicals that can be suitable for use as a fuel or as feedstock for other processes, such a plastic production processes. Thus, the product stream can contain a desirable product produced in the processing section 3 or the product stream can be a material that is free from, or has a lower level of contaminants. Corrosion is favorably handled by the ability to vary the pH of process fluids. Preferably a pH between about 7 to about 9 is used for all process fluids. The alternative petrochemical feedstock can be separated (for instance into useful fractions of hydrocarbons) in additional processing steps to form one or more product sub-streams by solvent extraction, distillation, settling, membrane filtration, centrifuging, ion exchange, drying, evaporation, vacuum distillation/separation or any other suitable separation process or combination of separation processes as would be readily apparent to a person skilled in the art
In an exemplary embodiment, one or more additive(s) 64a from an additive tank 64 can be added to the raw material 55 in the preparation stage 50 via additive pump 59 to form the aqueous biomass slurry 53.
The processing stage 51 pressurizes and heats the aqueous biomass slurry 53 to predetermined optimal temperatures and pressures to cause a reaction in the aqueous biomass slurry 53. A raw product 54 is produced by heating and pressurizing the aqueous biomass slurry 53 in the processing stage. The processing stage can include a pressurizing section 56, a processing section 57 and an output section 58. The pressurizing section 56 pressurizes the aqueous biomass slurry 53. The processing section 57 heats the pressurized aqueous biomass slurry 53 and cools the resultant raw product stream 54. The output section 58 depressurizes and outputs the raw product 54. The raw product 54 can be cooled and depressurized in a controlled manner. The raw product 54 can contain a desirable product produced in the processing section 57 or can be a material that is free from, or has a lower level of, contaminants that were removed.
In the separation stage 52, gas can be separated from the raw product 54. The discharged raw product stream 54 is passed through a product separator to be separated into one or more product sub-streams 60, 61, and 62. This may be achieved by solvent extraction, distillation, settling, membrane filtration, centrifuging, ion exchange, drying, evaporation, vacuum distillation/separation or any other suitable separation process or combination of processes as would be readily apparent to a person skilled in the art.
In an exemplary embodiment, product sub-streams 60, 61, 62 including a hydrocarbon oil rich stream are produced. The hydrocarbon oil rich stream can be used in place of crude oil or similar product for producing materials such as diesel, aviation fuel, lubricating oil, petrol, or similar products.
The process can be used to remove contaminants from the aqueous biomass slurry or the process can be used to produce a product, such as a product containing hydrocarbons or crude oil that may be suitable for use as a fuel. Thus, the product stream 54 can contain a desirable product produced in the processing stage or the product stream may be a material that is free from, or has a lower level of contaminants.
i. prepare an aqueous biomass slurry from a raw material;
ii. optionally introduce an additive material to the aqueous biomass slurry;
iii. pressurize the aqueous biomass slurry to between 100 bar and 350 bar;
iv. transfer the pressurized aqueous biomass slurry to a processing means, preferably in the form of a processing vessel;
v. raise the temperature of the pressurized aqueous biomass slurry to between 250° C. and 400° C. within the processing vessel to form a pressurized raw product stream;
vi. cool the raw product stream to ambient or near ambient temperatures;
vii. optionally separate the gases from the raw product stream using a gas separator; and
viii. depressurize the raw product stream prior to discharging the product stream from the system.
In step A, the raw material is formed into a aqueous biomass slurry. The raw material used in the process can be any organic or contaminated material such as de-lignitised timber, biomass, algae or drycleaning sludge. Many of the raw materials will require some mechanical/thermal or chemical processing to break them down into a pumpable form as herein disclosed and other materials will require only the addition of water. The processes used to break down the raw materials can include one or more of grinding, shredding, crushing, liquification, heating, chemical, thermal decomposition or other degradation processes. For example, if dry cleaning sludge is used as a raw material, the sludge is formed into a aqueous biomass slurry by adding between 30% to 50% water. If using cyanide waste as a raw material, no additional water is generally required. If using algae as a raw material, then between 50% and 98% water is left in the algae to produce a aqueous biomass slurry. Other materials, such as delignitised timber may need to be mechanically broken down with some water required at times. One or more additive(s) can be added to the raw material to form the aqueous biomass slurry. The aqueous biomass slurry is then transferred to the feed tank.
In step B a preset volume of aqueous biomass slurry is drawn from the feed tank through and optionally at the same time one or more additives can be added to the aqueous biomass slurry. The additive(s) can be catalysts or reactants to help process the aqueous biomass slurry. The additive(s) used can include acids and bases. However, it is contemplated that oxidizing and reducing agents can also be used. In other embodiments, each additive can be selected from the group of carbonates, hydroxides, bicarbonates and similar bases. Although it has been found that certain processed materials do not benefit from any additive being used, these are generally limited to when the process is used for decontamination purposes. Thus, the addition of one or more additives to the aqueous biomass slurry is an optional step in the process. The aqueous biomass slurry is transferred to the pressurization stage.
In step C, the aqueous biomass slurry is pre-pressurized to about 9 bar in a pump further pressurized with a second pump to the required processing pressure of between 100 bar to 350 bar, preferably by using indirect pressurizing means, as described herein.
Step D is undertaken once the aqueous biomass slurry is at the desired pressure. The aqueous biomass slurry is preheated by heat transferred, from a raw product stream.
In step E, the aqueous biomass slurry is pumped into the reaction chamber and its temperature is adjusted to the desired processing temperature of between 250° C. and 400° C. by the heating means. The aqueous biomass slurry undergoes a reaction to form a raw product stream of alternative petrochemical feedstock.
In step F, the high pressure raw product stream is cooled by incoming aqueous biomass slurry. Additional cooling can also occur by using a heat exchanger positioned between the processing vessel and a separation column, if a gas separator is used, or between the processing vessel and a third valve, if no gas separator is used. This cooled high pressure raw product stream is preferably at an ambient or near ambient temperature that will not damage valves in the process. For example, the raw product stream can be cooled to a temperature of at or below 80° C. or to about 50° C. (though this is dependent on the type of valve used). The cooled raw product stream exits the processing vessel via the outlet and is pumped to the third pump, or to the gas separator if the system includes a gas separator. In a further embodiment, optional step G includes the additional step of degassing the cooled high pressure raw product stream in a gas separator to remove any gas that is insoluble in that stream. The solubility of gases varies with temperature and pressure. Thus, by cooling the high pressure raw product stream, some gases may come out of the product. The gas formed is purged through purge valves or the like on the gas separator.
In step H, the cooled high pressure raw product stream within is depressurized, with pumps or other method. The depressurized product stream is discharged from the system process. In an exemplary embodiment, the discharged raw product stream can then be passed through a product separator to be separated into one or more product sub-streams. This can be achieved by solvent extraction, distillation, settling, membrane filtration, centrifuging, ion exchange, drying, evaporation, vacuum distillation/separation or any other suitable separation process or combination of processes as would be readily apparent to a person skilled in the art. The process can be used to produce a product sub-stream in the form of an alternative petrochemical feedstock including a hydrocarbon oil rich stream, which can be used in place of crude oil or similar, for producing materials such as diesel, aviation fuel, lubricating oil, petrol, or similar products.
It should be noted that although described in a sequential manner these steps can be re-ordered.
It has been found that the residence time influences the yield of oil and/or level of decontamination achieved in the raw product of alternative petrochemical feedstock. In certain embodiments, the minimum time between charges of aqueous biomass slurry is about 20 seconds. In other embodiments, the minimum processing time and/or residence time of the aqueous biomass slurry can be greater than 20 seconds.
Although the process contemplate the use of a pump with a ram it is further contemplated that each of the pumps can be any suitable pump or fluid transfer means known to those skilled in the art, such as a positive displacement pump, or a floating ram with one side connected to a high pressure pump of known type, or other mechanical means to accomplish the same role. For example, there can be more than one ram and each of these may be used in sequence to generate a near continuous series of small charges passing through the system.
It is also envisaged that the processing vessels may be of different lengths to suit the particular raw material used and to suit the desired residence time in the processing vessel and the desired outcome of the process. For example, in one embodiment, the process can include six or more processing vessels. Each of these processing vessels can be equipped with an extra inlet valve in series with the individual inlets, so as to allow sequential charging of aqueous biomass slurry with catalyst.
The following examples are included to demonstrate exemplary embodiments of the present disclosure. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit or scope of the disclosure. The following examples are not intended to limit the scope of the present disclosure and they should not be so interpreted.
An aqueous lignocellulosic, biomass slurry can be created prior to processing into an alternative petrochemical feedstock by subjecting willow chips to a lower mill apparatus with alternating rotational grinding or a hammer mill apparatus. The willow chips were ground to a particle size between about 1 mm to about 20 mm. Size was determined by microscopic analysis. The willow chips were wetted with water or a lignin removal solution and subjected to a lignin removal process by which the aqueous biomass slurry was placed into the top of a lignin removal column. The lignin removal column has a series of valves, equally spaced. The valves are sequenced to effect a gradual sequential movement downward through the lignin removal column and lignin removal solution. Likewise, the lignin removal solution is pumped into the bottom of the column. Sequencing of the valves results in the simultaneous rise of the lignin removal solution and the descent of the aqueous biomass slurry. The movement is effected by the opening of every second valve, except for the highest and lowest valves in order to create a double chamber which allows the aqueous biomass slurry to descend through the open valve space to the lower end of each double chamber. Likewise, the lignin removal solution (e.g., 90% methanol in water solution), moves upward to the upper end of each double chamber through the falling aqueous biomass slurry. Each set of valves were opened for 10 minutes and then closed while alternate sets of valves were opened. After passing through the column, the aqueous biomass slurry was cleaned of lignin and an aqueous cellulosic biomass slurry was formed.
The aqueous cellulosic biomass slurry created from the lignin removal is ground again to a particle size of approximately 2 μm to about 2 mm. The aqueous cellulosic biomass slurry is easier to grind after lignin removal. A column was reconstituted or recomposed with a solution of 6 molar sodium carbonate in water to form a pumpable, aqueous, cellulosic biomass slurry. The aqueous cellulosic biomass slurry was heated or processed to at a temperature of 320° C. and a pressure of 160 bar or higher with a charge time of 1500 seconds. A raw product stream was formed and yielded at least 2% mobile crude oil of a light low viscosity nature.
Example embodiments have been described hereinabove regarding improved systems and methods for the recomposition and conversion of biomass to alternative petrochemical feedstock. Various modifications to and departures from the disclosed example embodiments will occur to those having ordinary skill in the art. The subject matter that is intended to be within the spirit of this disclosure is set forth in the following claims.
This application claims the benefit of U.S. Provisional Application No. 61/332,449 entitled “LIGNOCELLULOSIC AND CELLULOSIC BIOMASSES FOR THE PRODUCTION OF BIOFUELS” filed on May 7, 2010, and which is hereby expressly incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/NZ2011/000066 | 5/5/2011 | WO | 00 | 1/22/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61332449 | May 2010 | US |
