Patent Application
20130167603
1. Technical Field
The present disclosure relates to processing technology for extracting lignin from plant material and converting the delignified cellulosic residue to crude bio-oils.
2. Description of Related Art
The demand for oil-based transport fuels and petrochemicals is global. Air, sea and land-based transport fuels, as well as petrochemicals, are produced from fossil fuels in the form of oil, coal and natural gas reserves. Petrochemicals are feed stocks for the plastics industry as well as for the production of resins, adhesives, paints, insulation and many other related products. It is mainly the phenol and polyols recovered from fossil fuels that are the major petrochemical feed stocks used in these manufacturing industries.
It is recognized that large scale use of fossil fuels has long been a major contributor to the degradation of the global land and water environments and the accumulation of greenhouse gases in the atmosphere. The search for green energy producing technologies to replace fossil fuels has led to the use of wind and solar power, wave motion and plant biomass. Nonetheless, such uses have not yet slowed the global demand for fossil fuels and today there are serious concerns about reliable, affordable long term supplies of transport fuel and petrochemical feedstock. Nations seek energy security to protect their people from the consequences of severe reductions in the supply of fossil fuels, ranging from reduced transport, decreased food production, decreased heating and electricity production and manufacturing.
The major land-based renewable energy source is plant biomass. Plant biomass can be used as a feedstock for biodiesel and chemicals for a wide range of manufacturing industries. For example, the lignin in plant biomass is a natural alternative to petrochemical feed stocks used for the manufacture of resins, adhesives, insulation, plastics, and paints. The chemistry of lignin is such that it is a natural substitute for phenol and polyols. Some industries already make use of woody biomass as feed stocks; however, process costs are typically high, waste generation is high, and there is limited yield of high value products. Also fermentation of wood is difficult and slow due to lignin presence
Alcohols have been used for more than ninety years to extract and separate wood components. The pulp and paper industry is largely reliant on cellulose and the removal of lignin is a major process step. However, removal of lignin in these industries is a harsh chemical process that degrades the lignin rendering lignin a low value by-product of processing and often burnt to produce heat. Organic solvents such as ethanol, methanol and acetic acid have been used for this purpose. For example, the use of a counter current flow of 20-70% aqueous ethanol to solubilise wood components is described in U.S. Pat. No. 3,585,104 (Kleinert), and a modification is later disclosed in U.S. Pat. No. 4,100,016 (Diebold, et al.), addressing increased lignin removal, solvent recovery and the production of pulp, using a flow of 40-60% aqueous ethanol.
In addition, other patents and published applications such as, for example, U.S. Pat. No. 4,764,596 (Lora, et al.) and international patent application no. PCT/NZ2008/000309 (published as WO 2009/063204) (Bathurst, et al.), disclose lignin extraction from woody feedstock by solubilisation in an ethanol aqueous solution leaving a cellulosic pulp. The lignin produced has a low molecular weight (e.g., 2,400 to 3,100 g/mol) with a low polydispersity (e.g., 1.6 to 2.0) and a phenolic hydroxyl, aliphatic hydroxyl and methoxyl group numbers of 2.9 to 4.3, 3.6 to 3.8 and 4.5 mmol/g respectively. The high process costs associated with these methods relate to the treatment conditions, the cost of recycling the organic solvent, and batch processing.
Using woody cellulosic material for degradation to sugars, and allowing fermentation to bioethanol, is another growing industry but is hampered by the costs of processing wood.
Biodiesel generated using plant feed stocks suffers the problem of competing for food feed stocks. Biodiesel, also referred to as FAME for “Fatty Acid Methyl Ester” is produced from vegetable oils and animal fats, by reaction with alcohol, commonly methanol, and a base catalyzed process called trans-esterification.
Biodiesel produced from soy, canola, palm oil and rapeseed oil generally have better cold flow properties than animal fat biodiesel. With the growth of the biodiesel industry worldwide, vegetable oil and animal fat feedstock costs have arisen and account for some 70% of production costs.
Algae, which lack lignin, are also used as a feedstock for biodiesel but suffer, particularly in temperate climates, from seasonal growth restrictions limiting available quantity of biomass and the cost of harvesting and removal of water before processing. The crude oil produced by this technology is roughly equivalent to Texas Light sweet crude, and as such is immediately able to enter the existing infrastructure as a true alternative to any other crude oil feedstock. Other sustainable fuels such as biodiesel, ethanol, and hydrogen suffer as their introduction requires major infrastructure changes.
Some embodiments of the present disclosure comprise a lignin extractor capable of processing wood chips to remove lignin and a bioconverter that uses a super critical water process to covert the cellulosic waste to produce biocrude. In some embodiments, the process leaves a sludge, which is converted to a high phosphate fertilizer. Re-usable solvents can be used to extract lignin and supercritical water to produce biocrude.
In some embodiments, the initial biomass starting point for the extraction of natural lignin can be wood from forest plantations, including softwoods, such as pine and other conifers, hardwoods such as eucalyptus, as well as wood process waste from pulp and paper mills and sawmills, and urban woody biomass. Softwoods and hardwoods produce chemically different lignins, the former known as guaiacyl lignin, the latter as syringyl lignin. The lignin extraction process can use ethanol to dissolve both types of these lignins. The lignin can remain natural and is not degraded by the process. Thus, the lignin can be more readily used as a substitute for industrial products used in the petrochemical industry.
A super critical water process can be linked directly to the cellulosic wood waste to produce a crude oil which can then be distilled to yield a range of high value chemicals, oil and transport fuel, products.
In one aspect, this disclosure provides a method for the processing of woody plant biomass by treating wood chips with an ethanol solution in a unit to extract lignin generating a black liquor; using the black liquor to heat ethanol solution entering the unit; separating the lignin from the aqueous ethanol solution; recovering and recycling the ethanol from the black liquor; removing cellulosic residue generated after the lignin extraction; producing a slurry from the cellulosic residue; feeding the slurry to a bioconvertor to convert the cellulosic and other cellular biological material into a hydrocarbon oil sludge; using the heat from the hydrocarbon oil sludge to heat additional slurry entering the bioconverter; recovering bio-crude from the hydrocarbon sludge by extraction; and collecting residual sludge remaining after the extraction of bio-crude from the hydrocarbon sludge.
In another aspect, this disclosure provides a method for the processing of plant biomass comprising extracting lignin from plant biomass using a solvent to generate a black liquor; separating the lignin from the black liquor; removing cellulosic residue generated after the lignin extraction; producing a slurry from the cellulosic residue and combining with other organic materials not containing lignin; feeding the slurry to a bio-convertor to convert the cellulosic and other cellular biological material into a hydrocarbon oil sludge; recovering bio-crude from the hydrocarbon sludge by extraction; and sending residual sludge remaining after the extraction of bio-crude to a fertilizer plant to recover high phosphate fertilizer product.
In a further aspect, this disclosure provides a method for the processing of plant biomass comprising extracting lignin from plant biomass using a solvent to generate a black liquor; separating the lignin from the black liquor; removing cellulosic residue generated after the lignin extraction; producing a slurry from the cellulosic residue; feeding the slurry at high pressures to a bio-convertor to convert the cellulosic and other cellular biological material into a hydrocarbon oil sludge; adjusting and equalizing pressures across valves in conditions of high gaseous content, by installing equalization cylinders upside down to enable surplus gas to be rapidly flushed out; controlling valves proximate the bioconverter to rapidly open valves at the instant of minimum pressure difference between opposite sides of valves; and recovering bio-crude from the hydrocarbon sludge by extraction.
In yet a further aspect, this disclosure provides a process for equalizing pressure of a flow stream across a valve comprising providing a process valve having an abrasive flow stream with a first pressure on a pump side and a second pressure on a second side of the process valve; providing a pump upstream from the pump side of said process valve; providing a slave cylinder in fluid connection with the abrasive flow stream downstream from the second side of the process valve, wherein the fluid connection with the abrasive is connected to a top portion of the slave cylinder; arranging a needle valve along a first non-abrasive fluid line between the pump and the slave cylinder; and actuating the needle valve to permit flow between the slave cylinder and the pump, whereby, the first pressure with the second pressure are equalized.
In still another aspect, this disclosure provides a system for equalizing pressure of a process flow stream across a valve comprising a process valve having an abrasive flow stream with a first pressure on a first side and an abrasive flow stream with a second pressure on a second side; a pump upstream from the first side of the process valve; a slave cylinder in fluid connection with the abrasive flow stream downstream from the second side of the process valve, the fluid connection being connected to a top portion of the slave cylinder; a valve disposed to control flow of a non-abrasive fluid line between the slave cylinder and the pump; and wherein upon actuation of the needle valve, the fluid flow is permitted between the slave cylinder and the pump thereby equalizing the first pressure with the second pressure.
In yet another aspect, this disclosure provides a method for the processing of plant biomass comprising extracting lignin from plant biomass using a solvent to generate a black liquor, the wood chips being fed to a top inlet of a counter current extraction column comprising a series of vertically aligned valves, and the solvent being fed into a bottom inlet of the counter current extraction column, the valves being operated sequentially to transfer wood chips down the column while providing cooking periods for extracting lignin; opening a containment valve disposed at the top of the counter current extraction column, above a valve housing a top level cooking chamber of the column, to feed wood chips to the top inlet; opening a containment valve downstream of valve that houses a bottom cooking chamber of the counter current extraction column, to remove pulp; separating the lignin from the black liquor; and recovering and recycling the solvent from the black liquor.
In another aspect, this disclosure provides a plant for processing plant biomass comprising an extraction unit for extracting lignin from plant biomass; a high pressure bioconverter reactor for converting residue from the extraction unit; a plurality of pressure equalization cylinders fluidly connected to the bioconverter; a control system for controlling at least one valve proximate the bioconverter to rapidly open the at least one valve at the instant of minimum pressure difference between opposite sides of the valve; and a recovery section for recovering bio-crude from hydrocarbon sludge generated by the bioconverter.
In the present description, certain specific details are set forth in order to provide a thorough understanding of various embodiments of the disclosure. However, upon reviewing this disclosure one skilled in the art will understand that the various embodiments disclosed herein may be practiced without many of these details. In other instances, some well-known structures, devices, control system configurations, instrumentation, valves, and other equipment and operations, and materials and compositions associated with lignin extraction, plant operations, and conversion of cellulosic residue to crude bio-oils, have not been described in detail to avoid unnecessarily obscuring the descriptions of the embodiments of the disclosure.
In the present description, the terms “about” and “consisting essentially of” mean±20% of the indicated range, value, or structure, unless otherwise indicated. It should be understood that the terms “a” and “an” as used herein refer to “one or more” of the enumerated components. The use of the alternative (e.g., “or”) should be understood to mean either one, both, or any combination thereof of the alternatives, unless otherwise indicated. As used herein, the terms “include” and “comprise” are used synonymously, which terms and variants thereof are intended to be construed as non-limiting.
Various embodiments in this disclosure are described in the context of using woody biomass or wood chips as a feed stock. However, as will be understood by those skilled in the art after reviewing this disclosure, other plant biomass, or materials that do not contain lignin, may be suitable for processing in one or more unit operations or sections of the process and plant described herein, such as, for example, without limitation, those operations or sections generally illustrated in
In various embodiments of the present disclosure discussed herein, unless the context indicates otherwise, the process steps can be controlled by one or more control systems, as will be understood by those skilled in the art after review of this disclosure. The control systems can comprise, for example, without limitation, one or more processors, memory(s), display devices, and communication ports, and be capable of use for automated or manual actuated control or combined automated and manual control, to control process equipment or their components, or to monitor process conditions, among other things.
Wood used in the present disclosure can be obtained from softwood or hardwood species from woody shrub garden waste, plantation or forest trees, forest residues and sawmill waste. Some embodiments of the present disclosure comprise a process for extracting lignin from wood chips, such as can be carried out using the equipment generally represented in the process flow diagram shown in
Referring to
Referring to
Water with dilute ethanol can be withdrawn from the bottom of the floatation tank 26 and re-circulated in the process along with a small residual of lignin that failed to float. During re-circulation, ethanol can be distilled from the water and lignin in a heater 6. The lignin particles can be recycled with the relatively pure water and to re-enter the aeration vessel, then the verturi mixer, for a second chance to be floated off and recovered in the flotation tank 26.
Again, referring to
The extraction column 8 can be composed of a series of large valves V1, V2, V3, V4, V5 & V6 separated by short spools, or chambers 1′, 2′, 3′, 4′ & 5′ of the same diameter pipe. In some embodiments, such as in a pilot plant scale utilized by the inventors hereof, the extraction column has a diameter of 150 mm. However, there is no restriction to the size and the design of the extraction column can be scaled up to suit any desired plant production requirements. In some embodiments, the chambers 1′, 2′, 3′, 4′ & 5′ are jacketed and lagged to maintain the process temperature, as discussed above, in the extraction column 8.
In some embodiments, a containment valve, such as a knife valve 16, is provided at the top of the extraction column 8, above the top valve (e.g., valve V1), to provide an extra fully enclosed chamber above the top valve V1, and another containment valve, such as a knife valve (V22 illustrated in
In some embodiments, the top V1 valve is opened by control system along with the third valve V3 and fifth V5 valve in the sequence. Knife valve 16 is then opened and an initial charge of wood chips can fall into the first chamber 1′. At the same time any material in the second 2′ and fourth 4′ chambers drops down one chamber and ethanol/black liquor rises into those chambers. Those valves, including the knife valve 16 can then be closed. Hot ethanol can then be injected into the top first chamber 1′, to bring the pressure up to operating pressure (as discussed above), and thereafter, valves remain closed during a cooking period. In some embodiments, the duration of the cooking period can be about 10 minutes. In other embodiments, the cooking period can be longer or shorter than 10 minutes. Ethanol can then be temporally removed from the bottom chamber, the fifth chamber 5′, to drop the pressure there. The second V2, fourth V4, and sixth V6 valves can then be open and material in the first 1′, third 3′ and fifth 5′ chambers each drop down one chamber. Note that the material dropping out of the final fifth 5′ chamber can empty into a bath of water. All valves can then be closed and hot ethanol can be re-injected into the fifth 5′ chamber to bring up to full operating pressure. Again, the valves can remain closed during a cooking period. Finally, all ethanol containing dissolved lignin (also referred to herein as “black liquor”) can be removed from the top first 1′ chamber and the pressure can be reduced to close to atmospheric pressure. Thereafter, the cycle described above can be re-initiated.
Hot black liquor discharged from the extraction column 8 can progress through the heat recovery section for cooling by entering the heat exchanger 4 at the top, in counter flow to the fresh ethanol, then the cooler 10. The pressure of the black liquor is reduced to atmospheric in the cooler, and eventually the low temperature black liquor is unloaded for storage in the black liquor container 12. Also fresh ethanol can be loaded from the ethanol container 2 and progresses first through the heat exchanger 4 to be preheated by the outgoing black liquor, then second into the heater 6 where it is pressurized to operating pressure and heated to the full operating temperature ready for loading into the extraction column 8.
At the bottom end of the extraction column, the spent wood chips without the lignin, can progress up the wash conveyor by auger 20 until they are discharged washed into the pulp product container 21.
Some embodiments of the present disclosure comprise a process for separating lignin from the extraction medium (which in the above example, is ethanol), and recycling the extraction medium, such as can be carried out using the equipment generally represented in the process flow diagram shown in
Referring to
In the flotation tank 26, air contained by the water can form tiny bubbles which carry the lignin crystals up to the surface of the floatation tank 26 where a paddle mechanism 28 can scrape the lignin sludge 26′ out of the flotation tank 26 into a pump 30, along with fresh water for washing.
The pump 30 can convey the water plus lignin crystals from the flotation tank 26 into a hydro cyclone 32. The lignin crystals, now separated from the air bubbles in the hydro cyclone 32, can sink to the bottom of the hydro cyclone 32 and drain into the dewatering tank 34.
From the dewatering tank 34, wet lignin can be transferred into the dewatering auger 36, which can slowly convey the lignin out of the water and into a rotating dryer tube 38, with heated air flowing through the drying tube at temperature between 100 to 200 deg C., in some embodiments. Surplus water can be allowed to overflow for from the dewatering tank to the floatation tank 26 for further treatment before disposal.
The rotating dryer tube 38 can slowly rotate and convey the lignin sludge, by regularly lifting and pouring the sludge into a current of warm air, in much the same way as a clothing dryer operates. By the time the lignin reaches the lower end of the tube, the moisture has evaporated and the lignin powder can pour into the receiving product container 40.
In some embodiments, the ethanol/water mixture in the flotation tank 26 can decant out from the bottom of the tank 26 without the lignin. This mixture can be sucked first through the cooler 10 (which is at higher temperature than the mixture), then through the heat exchanger 4 in counter-flow to the black liquor, finally entering the heater 6 at the lower end. The temperature of the mixture in the heater 6 can rise until the ethanol in the mixture distils off at the top. This can be aided in part by a vacuum operation at reduced pressures of about 0.3 to 0.5 bar in some embodiments. In some embodiments of the present disclosure, the level in the heater 6 top can be controlled by detecting the level and controlling the inlet valve closed until the level drops to a low level sensor.
The distilled ethanol vapors from the heater 6 can enter the heat exchanger 4 and condense while dropping down tubes within the heat exchanger. At the lower end of the heat exchanger 4, the cooled liquid ethanol can enter a vacuum pump 9 and finally be discharged into the fresh ethanol container 2.
In some embodiments, periodically in the heater 6, the proportion of residual water can rise to a point where the proportion of water in the vapor is no longer suitable for the lignin extraction process. A control system can determine this condition by monitoring the temperature of distillation at the top of the heater and sending a control signal when a threshold temperature has been reached due to rising water level, as will be appreciated by those skilled in the art after reviewing this disclosure. In some embodiments, the threshold temperature is about 70 to 80 degrees centigrade, when the absolute pressure in the system is about 0.5 bar to 0.7 bar. When this occurs, a valve (not illustrated in
Some embodiments of the present disclosure comprise a process for converting the organics, such as wood pulp, to oil sludge, such as can be carried out using the equipment generally represented in the process flow diagram shown in
The cellulose pulp, contained in the pulp product container 21, as delivered from the lignin extraction process, can be milled sufficiently to form a pumpable sludge at a mill 44 (see, e.g.,
While various embodiments of the present process provide a continuous process, they can also operate as a series of discrete charges which are periodically passed from one step to the next. In particular, the sludge can be increased in pressure in two stages (as further described below) until it is able to be forced into a supercritical water reactor, having, via one of the reaction tubes 56. The supercritical water reactor can include reaction tubes 56, having inner tube 55a, outer tube 55b, and an annular space therebetween, with a heating section 56′. In the reaction tubes 56, the inlet charges are progressively increased in temperature as they move along an inner tube 55a, by heat exchange with hot product material which is also progressively moving in the reverse direction in an annular space 55c between the outer tube 55b and inner tube 55a, while cooling. Eventually the incoming sludge now at a significant temperature reaches a heater section 56′. The temperature in this section 56′ raises the sludge temperature to a reaction set point, which in some embodiments can be between about 280 to 360 degrees Celcius, while at the same time, the pressure, which can be at about 170 to 250 [bar] in some embodiments (near supercritical water), is such that the sludge with the water is prevented from turning to steam. At the high temperature, water can change its characteristics and start to dissolve the sludge. Certain reactions then occur between the sludge and the water, which generate other substances as dictated by the materials and the thermodynamic conditions in the mixture at the set point temperature and pressure. The original sludge is converted into product sludge with the main components being a hydrocarbon with a very high carbon number, carbon dioxide gas, water, and a residual series of minerals of the original constituent non-hydrocarbon elements.
Eventually the cooled product sludge exits the reaction tubes 56 still at the high pressure, and enters a decompression slave cylinder 58. After being decompressed the product sludge enters the product vessel 60 and the gases, being principally carbon dioxide, are allowed to separate from the liquids and solids. The gases exit from the top of the product vessel through a gas meter 62 to ensure volumes can be recorded and then discharged to the atmosphere.
The liquids and solids exit from the product at the bottom of the product vessel 60 and enter a sludge product container 64 to be stored for the next extraction process (as described in further detail below).
In some embodiments, due to the very high pressures in this part of the process represented generally in
Equalization cylinders (C & P) in
That is, a needle valve 15 with a slave cylinder C is disposed downstream therefrom. The slave cylinder C contains a piston capable of reciprocation, namely sliding within the cylinder. On the side of the slave cylinder C having needle valve 15 can be a clean non-abrasive fluid. The clean non-abrasive fluid can be contained within a line from the high pressure pump 54, in the clean liquid source 18a across the needle valve 15, to slave cylinder C. This way, the fluid passing through and on either side of the needle valve 15 is clean and will not damage the needle valve 15. The needle valve 15 is configured to prevent flow of the clean non-abrasive fluid when closed, and upon actuation and opening to permit fluid flow therethrough.
On the other side of the slave cylinder C is a line connected with column (separator) containing the abrasive flow stream sludge. By means of the barrier of the piston in the slave cylinder C, the abrasive flow stream is prevented from contaminating the clean nonabrasive fluid on the other side of the piston in cylinder C. However, because the piston slidingly reciprocates freely within the slave cylinder C, the pressure on either side of the slave cylinder C can be equalized.
The pressure on either side of the piston is equalized prior to opening of the needle valve V15 by positioning the piston within the slave cylinder at a designated point. Namely, in some embodiments, the piston may slide toward the top of the cylinder and the pressure of the clean non-abrasive fluid on one side of the slave cylinder C will be equal to the pressure of the abrasive flow stream on the other side of the cylinder C. The position of the piston can be predetermined to equalize the pressure on either side of the piston. The clean fluid properties, the abrasive fluid properties, the process or system pressure, the process or system temperature and the characteristics of the process or system volume including vessels, conduits and pumps can be used to determine the initial position of the piston to equalize the pressure on either side of the piston. Further, because the line is connected to the clean non-abrasive liquid on the one side of piston, this pressure will equalize with the pressure of Column (separator). Moreover, the pressure will be the same on the other side of piston (abrasive flow stream side of piston), thus resulting in an equalization of the abrasive flow stream pressure on the pump 54 side of valve V2′ with the abrasive flow stream pressure on the other side of valve V2′, including Column (separator). In this way, pressure P1 (upstream from valve V2′) of the abrasive flow stream can be equalized with pressure P2 (between valve V2′ and valve V3′).
However, if pressure is too great on one side or the other of slave cylinder C, the piston may not be able to slide further in either the top or bottom of the cylinder and thus the pressure would not be equalized. Therefore, in some embodiments, the initial position of the piston within any working slave cylinder is predetermined in order to assure an equalization of pressure across any valve associated with or corresponding to the working slave cylinder.
Similar to the above, the clean non-abrasive fluid source is also connected with needle valve V16′ with slave cylinder P arranged subsequent needle valve V15′. Slave cylinder C contains a piston capable of reciprocation, namely sliding back and forth along the cylinder. In some embodiments, such cylinder P begins with the piston at the top of the cylinder prior to commencement of the charge stroke by pump 54. In such embodiments, the lower end of slave cylinder P is connected with decompression pump 58 on the abrasive flow stream side of the piston. Upon opening of needle valve V16′, the pressure will equalize. Therefore, the pressure downstream from valve V3′, including decompression pump 58, will equalize with the pressure of the abrasive flow stream upstream from valve 2′. Accordingly, the pressure P1 (upstream from valve V2′) of the abrasive flow stream will equalize with pressure P3 (downstream from valve V3′).
In some embodiments, just before commencement of the charge stroke by high pressure pump 54, pressures P1, P2, and P3 are equalized by opening valves V15′ and
V16′. This enables pressure differences to be transmitted via slave cylinders P and C as described above, thus ensuring that the pressure at high pressure pump 54 equals the pressure at the column and decompression pump 58. As such, in some embodiments, valves V2′ and V3′ can then be opened without wear. After opening of valves V2′ and V3′, needle valve V16′ is then closed. Subsequent to the closure of needle valve V16′, the high pressure pump 54 is commenced with a stroke. Such stroke can occur by the pressurization and pushing of the piston in the cylinder against the abrasive flow stream and through valve V2′.
At the end of the charging stroke by the high pressure pump 54, the piston in cylinder C will have naturally returned to the bottom of the slave cylinder C by the increased pressure from the non-abrasive clean source at the piston due to the charging action. The needle valve V15′, and valves V2′ and V3′ can then be closed.
Further, just prior to the discharge stroke by the decompression pump 58 while valve V4′ is still closed, the pressure is raised by action of the piston within the pump with valve V16′ opened and the pressure at high pressure pump 54 discharged. In some embodiments, the piston in slave cylinder P is thereby raised to the top. At the end of the discharge stroke by the decompression pump 58, valve V16′ is also then closed.
Because the pistons in slave cylinders C and P have been reset, and the raw product stream discharged, the pumping cycle is complete and can be repeated.
By this cycle the non-abrasive fluid is provided for the needle valves V15′ and V16′ while also equalizing pressures across valves V2′ and V4′. In this way the high pressure abrasion of component parts can be avoided.
Despite the above equalization system and process, such technique or system can be insufficient when working with certain sludges wherein there are a high proportion of solids. Without being bound by theory, the inventor(s) hereof note that after the reaction phase in the reaction tube 56, some organic materials have been converted to simple oils and a carbon dioxide amount of as much as 55% of total product. At high pressures around 250 bar or more bar, gas can be contained in tiny bubbles in the product, and can expand greatly when the product is decompressed. Thus, in the system and methods described above for equalizing pressure across valves, the equalizing cylinders would need to be very large in order to effectively equalize pressure, which may not be practical. Alternatively, various embodiments of the present disclosure may include employing enlarged equalizing cylinders having, for example, dimensions of 75 mm in diameter and 3 meters in length. In addition, the equalization cylinders can be installed upside down, as shown in
Still referring to
The milled pulp feedstock in tank 46 can then be mixed with water and other thickeners as may be required, combined with a small amount of catalyst, flowing into the tank 46 from source 45, to produce a pumpable sludge in tank 46. A feed pump 48 can periodically pump the pumpable sludge to a feed vessel 50.
In some embodiments, the feed vessel 50 can be capable of containing, or be rated for, pressurization up to two (2) bar, for convenient loading of the reactor plant as the control system requires. In some embodiments, the feed vessel 50 is rated for higher pressures or lower pressures than two (2) bar. After filling, the feed vessel 50 is automatically pressurized (e.g., up to two (2) bar).
A stage one pump 52 can be loaded from the feed vessel 50 with a charge and this charge can be transferred under pressure through valve V1′ to a high pressure (HP) slave pump 54. The HP slave pump 54 can load the charge through valve V2′ at the high system pressure into a single selected reaction tube 56, while simultaneously allowing a reacted charge to flow through valve V3′ into the slave product pump (Decompression pump) 58 while still under pressure. Valves V2′ and V3′ can then be closed. The decompression pump 58 can then reduce the pressure in the pump down to near atmospheric pressure. Valve V4′ can then open and the charge can be pushed out into a product vessel 60. After settling, the product gas, which can be mainly CO2, can be allowed to be discharged through a gas meter 62. The sludge product can then be allowed to flow from the product vessel 60 into the product container 64.
As discussed previously, in some embodiments, pressure equalization cylinders are provided to ensure pressures are equalized on both sides of valves V2′ and V3′ before they are allowed to open. This can eliminate major wear by the sludge.
The number and length of reaction tubes 56 can be determined as a function of capacity of throughput required and the length of reaction time considered necessary by a user. In some embodiments, a practical number is considered to be at least six tubes 56 each at least twenty (20) meters long.
Each tube 56 can have co-axial walls, with an inner tube 55a of diameter 25 mm and outer tube 55b of diameter 76 mm, in some embodiments. The feed material can enter at one end through an inner tube 55a and proceed in stages along the length to the heater end 56′. In transit, the charge will push the preceding charge in front of it.
At the heater end 56, the open inner tube 55a allows the feed material to enter the outer tube 55b which has a closed end so that the material is forced to return along the annular space 55c between the inner and the outer tubes. The heater section 56′ can be configured to heat the whole outer tube 55b in its area to set point temperature. The reactor tube 56 will heat the contents by heat exchange, and effect the desired reaction of cellulosic material and water into hydrocarbon oil sludge.
As proceeding charges enter the inner tube 55a the material is forced to move down the inner tube 55a then back along the outer tube 55b in stages. During the time while moving, and while at rest, the heated material in the annular space between the inner tube 55a and outer tube 55b will transfer heat to the incoming material in the inner tube 55a. As the entire tube 56 can be well insulated to retain heat, most of the heat required for any one charge to reach temperature can be obtained by heat transfer from outgoing reacted material, and only a top-up heating may be required to be input by the heaters 56′. When the reacted material then leaves the tube assembly 56, it can flow out through a manifold section at the initial end of entry at a conveniently low temperature, which can be typically less than 60 degrees Celsius. A control system can be used to control the heaters 56′ and regulate the rate of charge to the tube reactors, to suit the temperatures, pressures and cooking time as desired. In some embodiments, the variables to control around the reactor tubes 56 can thus be charge rate and heater 56′ temperature. Also, safety can be enhanced by three levels of control over temperature and pressure levels.
In some embodiments of the present disclosure, the process generally depicted in
Without being bound by theory, the inventors hereof theorize that during process step (i) carbohydrates are converted to a mixture of acid gasses and alcohols, then during step (ii), gasses are converted to complex high end carbon solid molecules (commonly known as “kerogen” to geologists). Finally, during step (iii) lighter hydrocarbons are extracted from the high carbon broken down molecules.
Referring to
In some embodiments of the present disclosure, the product sludge derived from the reactor tubes 56 rapidly settles to a heavy sludge and a water layer. The water can be decanted off the sludge which then needs to be processed with a light hydrocarbon solvent. This process can be carried out in a counter current extraction column 8′ to maximize oil extraction and minimize the required solvent use. The solvent can act on the heavy sludge and break out the hydrocarbons as lighter hydrocarbons of a much lower carbon number, typically in the C8 to C14 range. This oil laden solvent solution, called a black liquor, can then be distilled to recover the original solvent which is then returned for processing with further sludge. The crude oil remaining after this operation can then be drained off to form the product crude oil. Some residual water from the sludge can be decanted from the oil. This water will be surplus and can be sent to be reused in another part of the plant, or disposed to waste.
Referring to
To process the oil sludge, the top valve V1 of the extraction column 8′ can then be opened along with the third valve V3 and fifth valve V5 in the sequence. An initial charge of sludge can then be transferred into the first chamber 1′. At the same time any sludge in the second chamber 2′ and fourth chamber 4′ can drop down one chamber. Valves can then be closed for an extraction period (which can be, for example, 15 minutes). The second valve V2, fourth valve V4, and sixth valve 6 can then be opened and material in the first chamber′, third chamber 3′ and fifth chamber 5′ can drop down one chamber. In some embodiments, when this happens, the sludge dropping out of the final fifth chamber 5′ empties into a base pipe 20′. Again, valves can then closed for the extraction period. Solvent can then be injected into the fifth 5′ chamber and all solvent containing dissolved oil and black liquor can be removed from the top first 1′ chamber. This cycle can be repeated. In some embodiments, the operating temperature and pressure range of the extraction column can be maintained at about 15 to 25 degrees C. and 0.5 to 1.4 bar.
After the black liquor leaves the extraction column 8′, it can progress through the heating section by entering the heat exchanger 4′ at the bottom, then the heater/distillation unit 6′. Distillation proceeds after heating to the vaporization temperature of the solvent (e.g., hexane), which can be in the range of about 80 to 95 degrees C. Black liquor is added until a level in the heater unit 6′ reaches a maximum level, based on a level sensor, and then distillation continues until a final set point temperature signifies completion of solvent distillation. When the set point temperature is reached, it indicates all solvent has been distilled and the heater product chamber is full of oil product. Oil product can be drained automatically into an oil product drum 12′ until the lower level indicator on the heater 6′ is reached. Then another charge of black liquor can be added and distillation recommences.
The distilled solvent vapors from the heater 6′ can proceed to the heat exchanger 4′ wherein they condense into liquid while exchanging heat with the incoming black liquor from the extraction column 8′. After leaving as a liquid from the bottom of the heat exchanger 4′, the solvent enters the cooler 10′ for further cooling and also storage 2′. As may be required by the process, cool solvent can be withdrawn and injected into the fifth (5) chamber of the extraction column when emptied of the proceeding charge. The solvent is thus recycled.
At the bottom end of the extraction column 8′, the spent residue without oil, can progress into the residue discharge pump and then to the container 21′, an initial fertilizer sludge container. This initial fertilizer sludge can have a residue high phosphate fertilizer with significant traces of solvent and water. The fertilizer can be extracted from the sludge to be useful, as discussed below.
Some embodiments of the present disclosure comprise a process for separating residue from the fertilizer sludge and drying the purified material to fertilizer, such as can be carried out using the equipment generally represented in the process flow diagram shown in
Referring to
Some solvent and water trapped in the sludge may be vaporized by the heated conveyor 66 surface and travel to a suction point 74 just higher than the initial sludge entry point 66′. The vapors can be drawn and directed to a cooler 76, and cooled by cooling water. That vapor which condenses will join the pipe towards the suction of the transfer pump 72. A small simple separation column 78 downstream of the cooler 76 can separate vapors from liquids. Liquids can join the pipe to the transfer pump 72, and vapors will enter the lower temperature chiller unit 80 so that further condensation can take place. That vapor which reaches the top of the chiller 80 will be deemed to be non condensable gases including air, and be directed by pipe 82 to a fume ducting system. Any further condensate will join the pipe to the suction of the transfer pump 2.
After leaving the transfer pump the discharge can enter the liquid-liquid phase separation column 84. Two separate liquid phases can separate. The light hydrocarbon liquids can form a top layer, and the heavier water will be the lower layer. Water can leave the bottom of the column 84 and is directed to waste, while the hydrocarbon liquids can be directed to the hydrocarbon storage container 2′ in the extraction plant area. Meanwhile, the heated and dried sludge can reach the top of the drying conveyor 66 and drop down to the dried fertilizer product container 86 as fertilizer.
This example illustrates a trial for the conversion of cellulose (from woodchips) into crude oil using a super critical water reactor (SCWR), such as that described above. Additionally the trial included the conversion of waste printer toner into oil as a separate experiment. This example is provided for illustrative purposes only and is not intended to limit the scope of the invention.
Batch Preparation: Initially a batch named W1 was prepared from the following recipes as shown below in Table 1.
The addition of NaOH thickened the mixture into a light gel. Batch W1 was then separated into two 100 L batches. Half of batch W1 was processed in the SCWR. However, 50 L of additional water was added into the 100 L batch to reduce its viscosity.
This brought the total volume of the mixture to 150 L. The other half was mixed with toner to make a new batch named Batch W1A. The recipe for Batch W1A is shown below in Table 2.
The average mixing time for the two batches are given below in Table 3.
Sieving was carried out with a sieve plate hole sized 5 mm×5 mm. The total mass of the woodchips sludge removed from both the Batches were 14 kg.
The SCWR was disassembled and thoroughly cleaned prior to processing the feed. This was done in order to prevent contamination of the feed with material deposited inside the reactor previously. Then the SCWR was assembled and water was used as a feed stock to bring the reactor temperature and pressure to operational condition which are above 300 degree and 200 bar respectively.
Once the operational condition is reached the feed stock was switched to Batch W1, then to Batch W1A. However, water was also used as a feed stock in between the processing of the two batches (i.e., Batch W1 and W1A) to prevent mixing between the two batches.
When the additional water was added to Batch W1A the mix became less viscous and consequently some of the suspended woodchips began to settle to the bottom of the drum, forming two layers. In order to avoid reactor tube blockage, only the top layer of the batch was put though the reactor. The sludge had a depth of 75 mm in the drum (D=575 mm). The total volume of the sludge was about 13 L.
A method was proposed to work out how much of the woodchips settled to the bottom of the drum and unprocessed.
Working out the amount of toner in the Batch W1A sludge was important in order to know the amount of toner that had been processed. The following method was used to calculate the water and toner content of the W1A sludge. Also the sludge density was calculated to be 910 kg/m3. Hence the total mass of the sludge would be 11 kg.
Previously the percentage of water, toner and woodchips in the sludge has been calculated. Now it is important to know the water content of the top layer of batch W1A. It is difficult to work out the amount of toner and woodchips separately in the top layer since it is a homogenous mixture. The following steps were taken to calculate the amount of water in Batch W1A.
Results: The results collected from processing Batches W1 and W1A in SCWR MK1 are given below.
Gas released during the process from Batch W1 and W1A are shown below in
Although specific embodiments of the present disclosure have been described supra for illustrative purposes, various equivalent modifications can be made without departing from the spirit and scope of the disclosure, as will be recognized by those skilled in the relevant art after reviewing the present disclosure. The various embodiments described can be combined to provide further embodiments. The described systems, structures and methods can omit some elements or acts, can add other elements or acts, or can combine the elements or execute the acts in a different order than that illustrated, to achieve various advantages of the disclosure. These and other changes can be made to the disclosure in light of the above detailed description.
In general, in the following claims, the terms used should not be construed to limit the invention to the specific embodiments disclosed in the specification. Accordingly, the invention is not limited by the disclosure, but instead its scope is determined entirely by the following claims
This application claims the benefit of, and priority to, U.S. provisional patent application Ser. No. 61/504,219, filed Jul. 3, 2011, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61504219 | Jul 2011 | US |
