AU2021100983A4

AU2021100983A4 - Plastics & Packing Materials: Plastics, Non-Recyclable Packing Materials Convert into a Useful Products

Info

Publication number: AU2021100983A4
Application number: AU2021100983A
Authority: AU
Inventors: Pawan Kumar Bharti; S. B. Chordiya; Narendra D. Phatangare; Laxmi Deswal; R. Karthic Kumar; Shailendra Kumar Pandey; Beg Raj; M Nagabhushana Rao; B.K. Sarkar; Pari Nidhi Singh
Original assignee: Bharti Pawan Kumar Prof; D Phatangare Narendra Dr; Pandey Shailendra Kumar Dr; Raj Beg Prof; Rao M Nagabhushana Dr; Sarkar B K Prof; Singh Pari Nidhi Miss
Current assignee: Bharti Pawan Kumar Prof; D Phatangare Narendra Dr; Pandey Shailendra Kumar Dr; Raj Beg Prof; Rao M Nagabhushana Dr; Sarkar BK Prof; Singh Pari Nidhi Miss
Priority date: 2021-02-22
Filing date: 2021-02-22
Publication date: 2021-05-06
Anticipated expiration: 2029-02-22

Abstract

Our invention "Plastics & Packing Materials "is a biodegradable packaging material comprising an expanded high amylose starch product having at least 45% by weight amylose content, said expanded product having a low density, closed cell structure with good resilience and compressibility. The invention also provides a method of preparing a low density, biodegradable packaging material comprising extruding a starch having at least 45% by weight amylose content, in the presence of a total moisture content of 21% or less by weight, at a temperature of from 150 to 250° C. The invented technology also includes a Conversion of waste and other organic feedstock into sustainable energy, feed, fertilizer, and other useful products of reliable purities is accomplished using water, heat, and pressure. The invention is also providing methods and apparatus that handle mixed streams of various feed stocks, e.g. agricultural waste, biological waste, municipal solid waste, municipal sewage sludge, and shredder residue, to yield gas, oil, specialty chemicals, and carbon solids that can be used as is or are further processed. Useful products can be diverted at various points of the process or internalized to enhance the efficiency of the system. 26 CiDI 100 121peaa 110 112 SaurY 116 Resoled 122 Fwld 132 10134 138 2g Ste137 143 53 M~nis~ig 14 1151 117F= 148 142 F&e Sd Oa FIG. 1 is a flowchart illustrating an exemplary process according to the present invention.

Description

CiDI 121peaa 110

112 SaurY 116

Resoled 122 Fwld 132 10134

138 2gSte137 143

53 M~nis~ig 14 1151 117F=

148 142 F&e Sd Oa

FIG. 1 is a flowchart illustrating an exemplary process according to the present invention.

Plastics & Packing Materials: Plastics, Non-Recyclable Packing Materials Convert into a Useful Products

FIELD OF THE INVENTION

Our Invention "Plastics & Packing Materials" is related to a plastic, non-recyclable packing materials convert into a useful products and also relates to methods and apparatuses for sustainable waste management and production of fuels and other useful materials therefrom.

BACKGROUND OF THE INVENTION

Starch, a readily available, known biodegradable material, has been used to prepare foamed and film products as well as other shaped products for different purposes including selected packaging applications. In Patent Cooperation Treaty (PCT) Publication No. WO 83/02955, a foamed starch product is formed by extruding starch in the presence of a gas expanding agent, the product being useful in various applications such as foam sheets or fillers for packing.

The use of starch materials to form film products is well known, as shown e.g., in British Patent No. 965,349 which discloses the extrusion of amylose material without using solvents, to form films having excellent tensile strength. Another film forming operation using starch is shown in U.S. Pat. No. 3,116,351 where an unsupported amylose film is made by extruding an aqueous alkali-amylose solution into a coagulation mixture of ammonium sulfate and sodium sulfate.

U.S. Pat. No. 4,156,759 discloses a process for preparing low cost polyurethane foam by incorporating a starch containing amylaceous material into the foamed material yielding rigid or flexible and high resilient products.

U.S. Pat. No. 3,137,592 shows the extrusion of starch to produce an expanded gelatinized product in different shapes and forms, such as ribbon, ropes and tubes, which are useful in a variety of applications.

U.S. Pat. No. 3,336,429 involves a method for producing clear, thin. elongated shaped structures of amylose in forms such as film, tubes, bands and filament, by extruding an aqueous caustic solution of high amylose material through an aqueous acid bath.

U.S. Pat. No. 3,891,624 discloses the preparation of a dispersible, hydrophobic porous starch product by extrusion of a selected hydrophobic starch material at a temperature of 100 to 250° C. and a moisture content of 4 to 15 percent.

The use of starch in foods and confectionery products is well known. One area where starch use has been of particular interest involves expanded products such as snack foods and dry pet foods. The quality of such products, as evidenced by their crispiness, is affected by expansion volume which was studied and reviewed in two recent articles by R.

Chinnaswamy and M. A. Hanna: "Relationship Between Amylose Content and Extrusion Expansion Properties of Corn Starch", Cereal Chemistry, Vol. 65, No. 2, 1988, pp. 138 to 143 and "Optimum Extrusion-Cooking Conditions for Maximum Expansion of Corn Starch", Journal of Food Science, Vol. 53, No. 3, 1988, pp. 834 to 840.

The use of starch in the manufacture of confectionery products is disclosed in U.S. Pat. No. 3,265,509 where a mixture of high amylose starch and sugar is passed through an extruder in the presence of less than 25% moisture, to form a solid, plastic, shape retaining confectionery mass.

While the disclosures noted above show the use of amylose containing starch materials in forming films and various other shaped products, the use of such materials in packaging has generally been limited to selected applications such as film wrappings for food. The area involving resilient, compressible, low density packaging materials for uses such as protective packaging, has been generally left to lightweight plastics, including expanded polystyrene, more particularly Styrofoam (registered trademark of Dow Chemical Co.).

However, as noted earlier, these materials are not biodegradable and, therefore, the need still exists for a material which will meet the demanding requirements of the packaging industry while Due to the continuing depletion of fossil fuels, the emerging effects of C0 2 emissions, and the rising demands for energy, there is a greater need than ever for alternatives to traditional fossil fuels. The relatively high rate of waste production is another problem the world must grapple with. Waste management has become an increasingly complex matter as improvements in technology and recycling schemes are often not sufficient to counter growing waste production, obsolescence of existing waste management facilities, and shortage of space for the construction of new facilities.

Agricultural waste, biological waste, municipal sewage sludge (MSS), municipal solid waste (MSW), and shredder residue are amongst the types of waste being produced today. Agricultural waste, which includes waste from the food processing industry and agricultural industry, typically contain large amounts of water and are perishable, generating malodorous fumes in the process. When this type of waste is usually discarded, the deposit of these substances as landfill results in their decay, producing large amounts of nitrate/nitrite and methane gas which can then contaminate groundwater. Alternatively, such materials are sometimes incorporated into animal feed, thus potentially passing on pathogens and maintaining other undesirable characteristics in the food chain.

Proper management, handling, and disposal of biological waste are also imperative in the face of increasing population density. Nationally, hospitals are the major generators of medical waste, producing in excess of 500,000 tons each year in the United States. Many states concerned with the growing threat of Acquired Immune Deficiency Syndrome (AIDS) have caused more and more articles and materials to come under the definition of medical waste, which is expected to more than double the amount of medical waste being generated. The health and environmental dangers posed by biological waste mandate that special collection, transportation and disposal techniques be developed.

Municipal sewage sludge ("MSS"), by virtue of its origin, contains a large percentage of human waste and thus a high concentration of phosphates and nitrates, which are desirable components of fertilizer. However, the industrial wastes present in the sewage leaves highly toxic materials such as industrial solvents, heavy metals, behind in a sludge. When applied to the fields, the sludge releases both nutrients and high concentrations of toxic chemicals to the environment. Live pathogens also remain in the sludge and, when propagated, contaminate the soil and leach into groundwater. Disposal of the sludge is expensive and normally constitutes up to 50% of the total annual costs of wastewater treatment. The major sludge disposal options currently used include agricultural utilization, landfill, and incineration.

Wastewater treatment plants currently are designed to minimize sludge production and all efforts are taken to stabilize and reduce its volume prior to disposal or utilization. Furthermore, increasing sludge disposal costs and diminishing landfill capacities are continually driving interest in sludge drying. Although drying reduces the bulk and weight of sludge, thereby lowering the transport and disposal costs, it is a very energy intensive and expensive process. While numerous sludge processing options have been proposed and have the potential to convert a fraction of organic material into usable energy, only a few have been demonstrated to have a net energy yield at full scale.

Generally, municipal solid waste materials are landfilled and/or incinerated. Environmental restrictions on both landfills and incinerators demand that an alternative solid waste solution be implemented. The public outcry concerning pollution caused by incinerators has also halted construction of many new incinerator projects.

Treatment of industrial waste, namely shredder residue, likewise presents another challenge. Shredder residue generally consists of the nonmetallic content of the automobile and other materials (and their constituents), such as air conditioners, refrigerators, dryers, and dishwashers, the latter products being commonly known as white goods. The shredder industry recovers about 10-12 million tons/yr. of ferrous scrap, most of which is from shredded automobiles.

However, for each ton of steel recovered, about 500 lbs. of shredder residue is produced. While many components of end-of-life automobiles, household and commercial appliances can be recycled, reused, or recovered, a significant portion is left over from the shredding process and finds its way into landfills. Disposal of shredder residue is made all the more difficult by the toxic materials found therein, e.g. cadmium, lead, mercury, and other heavy metals. Due to the limited amount of space available for landfill use and the increasing costs of hazardous waste disposal, an alternative solution is needed. The automotive and recycling industries are currently under pressure to devise ways of using shredder residue in a cost-effective and energy-efficient manner.

Although a number of waste management methods are currently employed, they are either impractical, generate further pollution, or are too costly in terms of energy and economics. Some of these methods include composting, incineration, disposal as landfill, agricultural application, and dumping at sea. As indicated in Table 1 below, each method is beset by various drawbacks.

TABLE 1 Prior Art Drawbacks Composting Warehousing Landfill Disposal Agricultural Use Marine Dumping Pathogen Limited Space Limited Space Heavy Metal Marine Life Contamination Available Available Buildup Poisoning Haulage/Transport Leaching into Disease Cost Groundwater Transmission Greenhouse Haulage/ Emissions Transport Cost Haulage/Transport Cost

Other recycling approaches to waste management, including incineration, bio treatment, pyrolysis, and gasification have their own attendant problems. As case in point, bio treatment in the form of aerobic and anaerobic digestion requires long holding times, strict monitoring and control of operating conditions, e.g. oxygenation, pH, temperature, etc. for the selected microbes, specialized equipment, and generally results in non uniform treatment and final products filled with pathogens. Additionally, bacteria that may have been developed to consume specific compounds will, when exposed to the waste substrate, activate alternative enzyme systems to consume other more easily processed compounds.

Incineration/combustion involves the use of equipment and parts to comply with toughened emission regulations. Large volumes of gas are produced and must be disposed of using large specialized equipment. Most conventional systems cannot process a variety of waste substrates, such as solid waste, which would oxidize too high up in the furnace, or high-moisture feed stocks, for which a tremendous amount of energy must be expended to remove the water content. As such, there is a great heat/energy loss to the system.

Paralyzers have been used to break down organic matter to gas, oils and tar, and carbonaceous materials. A pyrolyzed typically heats organic materials at high temperatures, about 400-500° C., with poor energy efficiency and little, if any, control over the product composition. Most waste materials, especially agricultural waste, are high in moisture. As with incineration, pyrolysis aims to boil off the water using a very energy intensive process. The typically large holding vessels used in pyrolysis results in significant interior temperature gradients, non-uniform waste treatment, and yields contaminated end products.

Gasification achieves a partial combustion of waste materials but, like pyrolysis, does not operate efficiently with wet waste as energy is expended to remove water from the feedstock. There is little control over the type or composition of products due to non uniform treatment of the feedstock and the principal usable energy-containing products are gases that are not as useful as other products. Traditional thermal oxidation treatments also produce noxious gases and dioxins.

Both the products of pyrolysis and gasification methods, respectively, can contain unacceptably high levels of impurities, e.g. tar, asphalt, and have low calorie content. For instance, sulfur- and chlorine-containing waste yields sulfur-containing compounds, e.g., mercaptans, and organic chlorides in the end products. Typically, chlorinated hydrocarbons at levels of 1-2 ppm can be tolerated in hydrocarbons, but neither gasification nor pyrolysis methods can achieve such low levels with any reliability. Poor heat transfer, no uniform treatment, and an energy intensive water removal process have generally limited pyrolysis methods and gasification approaches to only about 30% energy efficiency.

In recent years, methods as disclosed in U.S. Pat. Nos. 5,269,947, 5,360,553, and ,543,061, have been developed to attempt to produce higher quality and more useful oils. However, such processes can have drawbacks. For example, the disclosed processes may not adequately handle sulfur- and chlorine-containing compounds, or efficiently process wet waste substrates due to significant energy requirements and thus have not been widely commercialized. As illustrated by the foregoing, there remains a need for sustainable recycling processes that are sound from a technical, economic, and environmental perspective.

PRIOR ART SEARCH

US07/292,0891988-12-3OBiodegradable packaging material and the method of preparation thereof. CA 6025231989-06-12Biodegradable shaped products and the method of preparation thereof DK298289A1989-06-16Biodegradable formed products and procedures for producing thereof F1892972A1989-06-16Biodegrader for made product for far oil framstaellning daerav. N0892551A1989-06-2Biodegradable products and process for preparation thereof. EP198901112951989-06-2lBiodegradable shaped products and the method of preparation thereof PT91032A1989-06-30Process for the preparation of amino products contained biodegradable AU46945/89A1989-12-18Biodegradable shaped products and the method of preparation thereof EP198901238011989-12-22Biodegradable shaped products and the method of preparation thereof

TW078104696A011989-12-22

OBJECTIVES OF THE INVENTION

1. The objective of the invention is to a biodegradable packaging material comprising an expanded high amylose starch product having at least 45% by weight amylose content, said expanded product having a low density, closed cell structure with good resilience and compressibility. 2. The other objective of the invention is to a method of preparing a low density, biodegradable packaging material comprising extruding a starch having at least 45% by weight amylose content, in the presence of a total moisture content of 21% or less by weight, at a temperature of from 150 to 250° C. 3. The other objective of the invention is to a Conversion of waste and other organic feedstock into sustainable energy, feed, fertilizer, and other useful products of reliable purities is accomplished using water, heat, and pressure.

4. The other objective of the invention is to a methods and apparatus that handle mixed streams of various feed stocks, e.g. agricultural waste, biological waste, municipal solid waste, municipal sewage sludge, and shredder residue, to yield gas, oil, specialty chemicals, and carbon solids that can be used as is or are further processed. Useful products can be diverted at various points of the process or internalized to enhance the efficiency of the system.

SUMMARY OF THE INVENTION

The present invention provides a biodegradable packaging material comprising an expanded amylose starch product having at least 45% by weight amylose content, said expanded product having a low density, closed cell structure with good resilience and compressibility properties. More particularly, the expanded packaging material of this invention has a uniform closed cell structure with a bulk density of less than about 2.0 lb/ft 3 , a resiliency of at least about 50% and a compressibility of from about 100 to 800 2 g/cm .

Another embodiment of this invention relates to a method of preparing low density, biodegradable packaging material comprising extruding an amylose starch having at least % amylose content, in the presence of a total moisture content of 21% or less by weight, at a temperature of about 150 to 250° C.

Methods and apparatus for generating sustainable energy, fuel, feed, fertilizer, specialty chemicals, and other useful products, from low value or waste feed streams are provided by the present invention. In some embodiments, a method involves preparing a slurry from a feedstock; heating the slurry at least to a first temperature under a first pressure to form a composition comprising an inorganic material, a liquid organic material, and water; separating the inorganic material, the liquid organic material, and water; and heating the liquid organic material to a second temperature higher than the first temperature under a second pressure higher than the first pressure to yield at least one product selected from the following: a fuel, a feed, a fertilizer, or a specialty chemical. In further embodiments, the method may comprise depolymerizing the slurry followed by hydrolyzing certain products of the depolymerization.

Methods and apparatus for treatment of waste materials are also provided by the invention. In some embodiments, the feedstock includes agricultural waste. In other embodiments, the feedstock includes municipal solid waste. In still other embodiments, the feedstock includes municipal sewage sludge. In yet other embodiments, the feedstock includes shredder residue.

BRIEF DESCRIPTION OF THE DIAGRAM

FIG. 2 is a schematic diagram depicting exemplary apparatuses used to perform an exemplary process of the present invention.

FIG. 3 is a flowchart illustrating a feed preparation stage through second stage of an embodiment of the present invention;

FIG. 4 is a flowchart illustrating a separation stage of an embodiment of the present invention;

FIG. 5 is a flowchart illustrating an oil finishing storage of an embodiment of the present invention;

FIG. 6 is a block diagram, illustrating an exemplary process of the present invention adapted for full scale processing of animal based agricultural wastes;

FIG. 7 is a schematic diagram of an exemplary depolymerization reactor;

DESCRIPTION OF THE INVENTION

The ability to provide a packaging material which is biodegradable, is an important feature of this invention. The term "biodegradable "as used herein refers to the susceptibility of a substance to decomposition by living things (organisms/microorganisms) and/or natural environmental factors, e.g., the ability of compounds to be chemically broken down by bacteria, fungi, molds and yeast. Plastics used in packaging, especially polystyrene are not biodegradable. This creates a problem in the area of low density packaging, where expanded polystyrene such as Styrofoam is used in large volumes in many applications, particularly protective packaging or fillers. While starch is a material with known biodegradable properties, its use in packaging has not been widespread primarily because it lacked many of the physical attributes required of packaging materials.

Now, in accordance with this invention, a biodegradable, low density, low cost packaging material is obtained by expanding a high amylose starch material, having at least 45% by weight of amylose content, through an extruder in the presence of a total moisture content of 21% or less by weight, at a temperature of from about 150 to 250° C. The expanded, high amylose starch material has excellent resilience and compressibility properties, which coupled with its low density, make it attractive for use as a packaging material, particularly in the area of protective packaging.

The starting starch material useful in this invention must be a high amylose starch, i.e., one containing at least 45% by weight of amylose. It is well known that starch is composed of two fractions, the molecular arrangement of one being linear and the other being branched. The linear fraction of starch is known as amylose and the branched fraction amylopectin. Starches from different sources, e.g., potato, corn, tapioca, and rice, etc., are characterized by different relative proportions of the amylose and amylopectin components. Some plant species have been genetically developed which are characterized by a large preponderance of one fraction over the other. For instance, certain varieties of corn which normally contain about 22-28% amylose have been developed which yield starch composed of over 45% amylose. These hybrid varieties have been referred to as high amylose or amyl maize.

High amylose corn hybrids were developed in order to naturally provide starches of high amylose content and have been available commercially since about 1963. Suitable high amylose starches useful herein are any starches with an amylose content of at least 45% and preferably at least 65% by weight. While high amylose corn starch has been especially suitable, other starches which are useful include those derived from any plant species which produces or can be made to produce a high amylose content starch, e.g., corn, peas, barley and rice. Additionally, high amylose starch can be obtained by separation or isolation such as the fractionation of a native starch material or by blending isolated amylose with a native starch.

The high amylose starch used in this invention may be unmodified or modified and the term starch as used herein includes both types. By modified it is meant that the starch can be derivatized or modified by typical processes known in the art, e.g., esterification, etherification. oxidation, acid hydrolysis, cross-linking and enzyme conversion. Typically, modified starches include esters, such as the acetate and the half-esters of dicarboxylic acids/anhydrides, particularly the alkenyl succinic acids/anhydrides; ethers, such as the hydroxyethyl- and hydroxypropyl starches; starches oxidized with hypochlorite; starches reacted with cross-linking agents such as phosphorus oxychloride, Epichlorohydrin, hydrophobic cationic epoxides, and phosphate derivatives prepared by reaction with sodium or potassium orthophosphate or tripolyphosphate and combinations thereof. These and other conventional modifications of starch are described in publications such as "Starch: Chemistry and Technology", Second Edition, edited by Roy L. Whistler et al., Chapter X; Starch Derivatives: Production and Uses by M. W. Rutenberg et al., Academic Press, Inc., 1984.

One modification of the high amylose starches used in this invention that is especially advantageous, is the etherification with alkylene oxides, particularly those containing 2 to 6, preferably 2 to 4, carbon atoms. Ethylene oxide, propylene oxide and butylene oxide are exemplary compounds useful in etherifying the starting starch materials with propylene oxide being especially preferred. Varying amounts of such compounds may be used depending on the desired properties and economics. Generally, up to 15% or more and preferably, up to about 10%, by weight, based on the weight of starch will be used. Extruded starches modified in this manner, showed improved expansion, uniformity and resiliency.

Additive compounds may also be combined or blended with the starch starting material to improve properties such as strength, flexibility, water resistance, resiliency, color, etc. as well as to provide repellency to insects and rodents, if needed or desired. Compounds such as polyvinyl alcohol, monoglyceride, and polyethylene vinyl acetate are typical additives which may be used. They are used in any amount provided the extrusion of the starch and the properties of the expanded product are suitable. Typically, up to about % by weight of such additives, and preferably up to about 10% by weight, may be used.

In addition to the above noted modified starches and additive compounds, a pregelatinized form of the starch starting material may be used, if desired. The method used in preparing the packaging materials of this invention is an extrusion process wherein the starting high amylose starch is fed into an extruder and conveyed through the apparatus under select conditions. The product emerging from the extruder is an expanded, closed cell, low density material with good resilience and compression properties making it particularly suitable for packaging applications. Extrusion is a conventional well known technique used in many applications for processing plastics and has been used to a lesser or limited extent in processing food starches as noted in some of the disclosures cited earlier which show extrusion of starch materials to produce products such as films, foods and confectioneries and gelatinized starches.

The essential feature of this invention is the ability to produce an expanded, biodegradable starch product having a uniform, closed cell structure with low density and good resilience and compressibility properties. This is accomplished by the extrusion of a high amylose starch, i.e., starch having at least 45% and preferably at least 65% by weight amylose content, at a total moisture or water content of 21% or less by weight and at a temperature of from about 150 to 250° C.

The important property characteristics of the extruded product of this invention are its relatively light weight, as evidenced by bulk density, as well as its resilience and compressibility. The uniform, closed cell structure of the product with its characteristic tiny bubble formation, not only results in a Styrofoam-like appearance and density, but gives it the necessary resilience and compressibility needed for different packaging applications. A closed cell structure is defined as one having largely no connecting cells, as opposed to open cells which are largely interconnecting or defined as two or more cells interconnected by broken, punctured or missing cell walls. The tiny bubble formation generally results in a small cell size of typically about 100 to 600 microns.

The bulk density, resilience and compressibility properties of the product are measured in accordance with procedures described hereinafter The bulk density of the product is less than about 2.0 lb/ft3 , preferably less than about 1.0 and more preferably less than about 0.6 lb/ft 3 . The resilience is at least about 50% and preferably at least about 60% and the compressibility will range from about 100 to 800, preferably about 150 to 700 and more preferably from about 400 to 600 g/cm 2 .

In order to obtain the expanded, closed cell structure characteristic of the desired product, it is important that the total moisture content of the high amylose starch material feed be at a level of 21% or less by weight, based on the dry weight of starch material. By total moisture or water content is meant both the residual moisture of the starch, that is the amount picked up while stored at ambient conditions, and the amount of water fed to the extruder. Typically, starch, and particularly high amylose starch, will contain about 9 to 12% residual moisture. Enough water must be present to allow the material to be processed, mixed and heated to the desired temperatures.

While some water may be added to the extruder, only an amount which will bring the total moisture level to 21% or less can be added. This is necessary to allow for the desired expansion and cell structure formation in the prepared product. Accordingly, while the total moisture content that is used for carrying out the process may vary somewhat, depending on the actual material used and other process variations, a range of from about to 21%, preferably from about 13 to 19% and more preferably from about 14 to 17% by weight, will generally be suitable. The temperature of the material in the extruder will beincreased toreachabout1500to250C.

This temperature must be maintained in at least the section of the extruder closest to the die and just before the material leaves the extruder. The die is positioned at the point or location at the end of the extruder from which the extruded material emerges or exits the apparatus into the ambient air. Depending on the particular material being processed, as well as other process variations, this temperature can vary somewhat within the noted range and preferably will be from about 1600 to 210 C. When modified starch such as the etherified material is used, the temperature used will preferably be from 160 to 180° C. while the use of unmodified starch will have a preferred temperature of from about 170° to 2100 C. in at least the section of the extruder closest to the die. By maintaining these conditions in the extruder, the material upon leaving the die and extruder outlet into the open air, expands and cools to form an expanded, low density, resilient and compressible starch product.

The apparatus used in carrying out this process may be any screw. type extruder. While the use of a single, or twin-screw extruder may be used, it is preferred to use a twin-screw extruder. Such extruders will typically have rotating screws in a horizontal cylindrical barrel with an entry port mounted over one end and a shaping die mounted at the discharge end. When twin screws are used, they may be corrugating and intermeshing or no intermeshing. Each screw will comprise a helical flight or threaded section and typically will have a relatively deep feed section followed by a tapered transition section and a comparatively shallow constant-depth meter section. The screws, which are motor driven, generally fit snuggly into the cylinder or barrel to allow mixing, heating and shearing of the material as it passes through the extruder.

Control of the temperature along the length of the extruder barrel is important and is controlled in zones along the length of the screw. Heat exchange means, typically a passage, such as a channel, chamber or bore located in the barrel wall, for circulating a heated media such as oil, or an electrical heater such as carload or coil type heaters, is often used. Additionally, heat exchange means may also be placed in or along the shaft of the screw device.

Variations in any of the elements used in the extruder may be made as desired in accordance with conventional design practices in the field. A further description of extrusion and typical design variations can be found in "Encyclopedia of Polymer Science and Engineering", Vol. 6, 1986, Pp. 571 to 631.

The expanded product resulting from the extrusion of the high amylose starch has excellent properties for packaging, particularly in the areas of protective packaging. The finished product has properties making it comparable in most aspects to Styrofoam, or expanded polystyrene with the added feature that it is biodegradable.

An additional and important feature of the product of this invention is that is does not retain an electrostatic charge buildup as commonly found in plastics. This static-free characteristic, makes the material especially attractive for the protective packaging of sensitive electrical apparatus or devices, unlike the traditional commercially available Styrofoam material which requires a special or different grade product for this purpose.

It is also noted that the expanded starch product may be formed in different shapes by varying the size and configuration of the die opening. The product thus may be obtained in forms, such as sheets which differ from the typical rope or cylindrical product thereby extending the type of packaging and configuration in which it might be used. The product, accordingly, may be used as a filler or as a protective cushioning packaging material, particularly for sensitive electrical equipment and devices.

In the following examples which are merely illustrative of the various embodiments of this invention, all parts and percentages are given by weight and all temperatures are in degrees Celsius unless otherwise noted.

The following procedures were used to determine the characteristic properties of material being evaluated and as specified throughout the specification and claims:

Bulk Density

The method used to determine the bulk density of the material was the volume replacement method described by M. Hwang and K. Hayakawa in "Bulk Densities of Cookies Undergoing Commercial Baking Processes", Journal of Food Science, Vol. 45, 1980, pp. 1400-1407. Essentially, this involved taking a beaker of known volume, i.e., 500 ml. and determining the weight of small glass beads (diameter 0.15-0.16 mm) needed to fill the beaker. This allowed the density of the glass beads to be established (formula below). The weight of a sample was measured and by measuring the weight of glass beads that were needed to replace the volume of that sample, the density of the sample was calculated using the following equations: ##EQU1## where d, =density or sample Ws =weight of sample Wgr =weight of glass beads needed to replace volume of sample dg =density of glass beads Wgb =weight of glass beads needed to fill beaker Vb =volume of beaker Resiliency The resiliency (also called rebound resilience or relaxation) refers to the ability of a material to recover to its original shape after it has been deformed by a force and was determined using a Stevens LFRA Texture Analyzer employing a cylindrical probe (TA-6, 0.25"diameter) run at a probe speed of 0.5 mm/sec. and a probe distance of 0.1 mm. Sample extrudates were cut into 1-inch long pieces, placed on the texture analyzer's sample table, and secured with pins. The probe was lowered automatically using the above conditions. After the probe was fully lowered, it was held at that distance for one minute before it was released. The force required to initially compress the sample and the force required to compress the sample after one minute were determined. The percent recovery of the sample is determined by dividing the compression force after one minute by the initial compression force and multiplying by 100. A higher percent recovery corresponds to a material having a better resiliency.

Compressibility

The compressibility, i.e., the force necessary to deform a material, of a sample was determined using a Stevens LFRA Texture Analyzer employing the conditions as noted above in measuring resiliency. Sample extrudates cut into 1-inch long pieces were placed on the analyzer's sample table and secured with pins. The probe was lowered and raised automatically with the force required to compress the sample being measured in g/cm 2

. This analysis was repeated two additional times using a fresh piece of sample extrudate each time. The average of the three measurements was taken as the compressibility value. A high value is attributed to a sample that is relatively hard, i.e., less compressible, while a lower value is attributed to a sample that is easily compressible.

EXAMPLE I

Several samples of unmodified starch materials containing varying amounts of amylose content, i.e., corn (~25-28% amylose), waxy maize corn (~0-1% amylose), potato (~23% amylose), Hylon V (~50% amylose) and Hylon VII (70% amylose) were fed to a Werner and Pfleiderer twin screw corotating extruder, model ZSK30. Hylon is a registered trademark of National Starch and Chemical Corporation for starches. The extruder had a screw having a high shear screw design, a barrel diameter of 30 mm, two die openings of 4 mm diameter each, a L/D of 21:1, and oil heated barrels The samples were fed to the extruder which had a screw speed of 250 rpm, at a rate of 10 kg/hr with input moisture of about 6.7% based on weight of starch added (residual moisture of starting starch materials was ~9 to 12%). The temperature in the extruder was increased to a level of about 2000C. in the barrel or section nearest or just before the die and the extruder pressure was between about 200 to 500 psi.

Embodiments of the present invention can handle and process a mixed stream of waste materials without the need for presorting into pure streams. In some embodiments of the invention, as illustrated by the figures, raw feed 100, used synonymously herein with the term "feedstock," is subjected to a feed preparation step 110 before entering the first stage 120. See FIG. 1 and FIG. 3, inter alia. An objective of the feed preparation step is to increase flow ability of the feed stock for improved handling, heat transfer and mixing, etc. in subsequent process steps. In some feed stocks this may be accomplished by reducing semi-solids in the feedstock to a size that can be consistently pumped (or metered) into the first stage 120. Other feed stocks may be already adequately sized and require only addition of an appropriate liquid agent.

Feed preparation is achieved through pulping, slurrying, mixing, and other grinding mechanisms, singly or in combination with preheating. Specific examples of slurrying devices include, without limitation, pulpers, in-line grinder, and macerators. A mixture of steam and gases 121 may be given off from feed preparation step 110 depending on process parameters. Feed preparation may involve adding water or other fluids and/or solvents to raw feed 100, depending on the moisture content or other chemical properties of the incoming waste substrate. Feed preparation generally may take place at ambient pressures and temperatures. However, in some alternative embodiments slightly elevated pressures or temperatures may be desired. For example, the prepared feed may be accumulated in a holding tank at temperatures in excess of about 1200 F. but not so high as to prematurely initiate reactions. Elevated temperatures and pressures can help limit unwanted biological activity and introduction of contaminants at this stage.

The mixing or slurrying in feed preparation step 110 is not restricted to any particular grinding or feed rate as the system can employ buffer storage to minimize perturbations resulting from variations in feedstock quantity and initial product size. The slurry can either be transferred through a piping system into on-site storage tanks for later processing or immediately introduced into the process. This ability to prepare and store incoming waste prior to processing provides flexibility to accommodate high degrees of variability in the delivery times and composition of wastes.

As will be apparent from the following disclosure, embodiments of the present invention may utilize wet grinding to move material through pipes, tanks, and various equipment of the invention. Larger particles are conveyed through the process as mentioned above. Slurrying or wet grinding, as in the feed preparation step 110, reduces friction and energy consumption. In general, a minimal slurry moisture content of about 40% can be useful for optimal processing in embodiments described herein due to pump viscosity limitations. Those of ordinary skill will recognize that this minimum moisture content threshold can be shifted lower with the use of alternative pumping or conveying technology and depending on particular feedstock parameters. The energy efficiency of the processes described herein is fairly high since most of the water that enters the system leaves as a liquid rather than as vapor or gas. Addition of solvents may or may not be called for at this stage depending on feedstock and process parameters.

According to embodiments of the present invention, these incoming streams can be processed as is, while conventional methods, which function poorly with wet feedstock, typically aim to first remove the water as well as other contaminants. Embodiments of the present invention, however, use the water already in the feedstock to further enhance efficiency and to help remove contaminants and toxic chemicals from organic streams.

Apparatus

Feedstock preparation and slurrying can be carried out in a feedstock preparation apparatus 210, as diagramed in FIG. 2. Devices such as airlock devices in concert with screw conveyors can be employed to feed larger particles to the first stage reactors without the need for fine grinding. Initial raw material handling can be done using live bottom bins, conventional augured conveyors, and/or bucket elevators under ambient conditions. Vibratory screens may be used for fines scalping to remove loose dirt and debris if desired.

The size to which the substances in the feedstock should be reduced will vary with the composition of the feedstock. For instance, with agricultural waste, a useful particle size is in the range of about / inch to about 1 inch. In another example, with feedstock comprising primarily mixed plastics and rubber, the particle size can be dependent on the size reduction capabilities of the contracted shredder company. As another example, an embodiment of the apparatus provided herein is capable of handling larger size material such as whole tires. However, for practical considerations, a material size of about % inch to about 6 inches is typical.

In general, initial material size is largely dependent on the capacity and capability of the equipment. Upon exiting the feedstock preparation stage, particle size should be such that subsequent treatments are optimized as explained herein. In other embodiments of the invention, the feed preparation step may further comprise adding materials to, or driving materials off from the raw feed. Those of ordinary skill in the art will also readily appreciate that certain types of more fluid feedstock can be fed directly to the first stage decomposition 120 a without detracting from the objects and advantages of the present invention.

First Stage Separation of Organic and Inorganic Waste: Decomposition

Referring to FIG. 1, the slurry 112 from the feed preparation step 110 is delivered to the first stage 120, and more specifically, first stage decomposition 120 a, where it is heated and pressurized. The combined effect of temperature, pressure and time causes molecular breakdown of the feedstock. The first stage decomposition 120 a thus effectively depolymerizes the feedstock by breaking down organic matter into simpler compounds and separating the bulk of organic and inorganic materials contained in the slurry. Decomposition 120 a can therefore also be characterized as a depolymerization step. Various solids 116, including, for example, heavy-ash solids, minerals (e.g., calcium, phosphorous), fixed carbon and other carbonaceous materials in the slurry that are not hydrogen rich are removed at this stage and may be optionally directed to the finished product separation step 130 as will be described below.

The removal of solids 116 at this stage allows for improved contact of the organic with water in the subsequent hydrolysis reaction 120 b. Examples of organics remaining in liquid mixture 118 at this point include, but are not limited to, fats, protein, fiber, and various other hydrocarbons. Those of skill in the art will recognize that the composition of inorganic and organic matter will differ from batch to batch, depending on the nature of the feed stocks used.

In some embodiments of the invention, bulk/mineral separation is accomplished at this point in the process through a combination of hydrocyclone separation and gravity decanting.

The inorganic material or other solids thus separated out can optionally be committed to storage. Generally, first stage decomposition 120 a can occur at a temperature range of from about 125° C. (~260° F.) to about 400° C. (~750° F.) depending on feedstock. However, temperature is preferably controlled for specific feedstock compositions to minimize or at least substantially eliminate formation of char, ash or unwanted reactions to the extent possible. Preferably no char or ash is formed. In exemplary embodiments, again depending on feedstock, the pressure ranges between about 20 psig to about 800 psig. The run time of this step will typically range from about 15 minutes to about 180 minutes. In certain embodiments, the average pH of the materials in this stage is about 6.5. On average, in exemplary embodiments of the invention, the temperature, pressure, and time are at or greater than about 150° C. (~300° F.), 100 psig and 30 minutes, respectively. As those of ordinary skill in the art will appreciate, run time will depend on the conditions employed, with as little as 15 minutes required at higher temperatures, and more than an hour at lower temperatures in the range.

Heating to such temperatures decreases the overall viscosity of the slurry and breaks down various components for further processing. For example, proteins are broken down into their shorter chain amino acid sequences or single amino acids. In SR type feed stocks, plastic and rubber compounds are melted, long chain molecules broken and solids such as fixed carbon and metals released. Such a reduction in viscosity also permits separation of attached insoluble solids 116 such as minerals, including, e.g. bone material, silica, etc. thereby yielding a liquid mixture 118 that subsequently enters first stage hydrolysis 120 b. In exemplary embodiments, a large portion, if not the majority, of solid materials may be removed at this stage. First stage decomposition 120 a also serves essentially as a pretreatment step for fiber where the hemicellulose hydrolyzes to sugars, halogens are solubilized in the water phase, and the minerals potentially are removed. Cellulose and lignin (the other fiber components) are assumed to be unconverted in the depolymerization reactions of the first stage.

Apparatus

In an exemplary implementation of first stage decomposition, as shown in FIG. 2, slurry 112 is passed through a heat exchanger 212 and into a reactor and/or separator vessel 216, which may serve as a decomposition/depolymerization reactor. Alternatively, decomposition or depolymerization may occur primarily in and just after heat exchanger 212, with vessel 216 then serving primarily as only a separator. The feed may be subjected to heating in and/or prior to reaching vessel 216 to produce a heated slurry that is pressurized. Such heating and pressurizing can be done using the vessel to retain the slurry, a pump for increasing the pressure of the slurry, and a heat exchanger to heat the slurry. Alternatively, rather than using separate components, heating, pressurizing, reacting and separating can occur in a single vessel.

Decomposition reactor designs can be implemented using simple existing technologies, e.g. batch or flow through jacketed reactors, as relatively low pressures are being utilized in the current process. Readily accessible devices such as vibratory screens, single and double screw presses, and off-the-shelf centrifugal machines can also be used to effectuate separation of the bulk/minerals. Those of ordinary skill in the art will appreciate that such separation can be achieved by gravity separation or can be achieved with other separation apparatus currently known or unknown in the art, e.g. a liquid/solid centrifuge, a screen, or a filter. One exemplary decomposition reactor 1014A is described below in connection with FIG. 7; another alternative is described below in connection with FIG. 19.

A further alternative embodiment of the apparatus is diagramed in FIG. 3 as applied to agricultural waste feedstock. However, such an apparatus may be utilized with other feed stocks with appropriate adjustment to process parameters as described herein. During first stage decomposition, slurry 112 may be transferred to feed storage 320 in a feed storage tank ("FST" or homogenizer) via a heat exchanger 114 where it is heated to break down proteinaceous material, including material attached to bones and other hard body parts in the mixture when feed stocks are animal by-products. Separator 310 separates the solids comprising minerals and bone material 116 from the liquid mixture 118.

The liquid mixture, comprising a mixture of water and water-insoluble organic components and some trace minerals, is cooled and directed to the feed storage tank 320 ("FST" or homogenizer). The contents are heated to about 275-280° F. (~135° C. 140° C.) and subjected to pressure of about 50 PSI in order to produce conditioned feed 322, a relatively homogeneous feed suitable for passing to the hydrolysis reactor. Steam and gaseous impurities 338 may be vented 336.

An advantage of this embodiment is that degassing can occur in FST 320 to remove unwanted gaseous impurities early in the general process. Slurry 112 may remain in feed storage 320 for any convenient time until it is due to be further processed by the methods of the present invention. Preferably, FST 320 supplies a constant feed stream to a high pressure slurry pump that pressurizes the feed and transports it to hydrolysis stage reactor 330.

In the heat exchanger 114, steam and gases also can be separated. The steam can be condensed and combined with condensate 151 (FIGS. 1 & 4). Preferably this condensate is redirected to combine with "produced water" that results from later stages of the process of the present invention, further described hereinbelow. Residual no ncondensable vented gases may be combined with other gases that are produced by later stages of the process of the present invention to give fuel gas.

First Stage Conversion to Oil: Hydrolysis

As generally illustrated in FIG. 1, the organic liquid mixture 118, still potentially including some small mineral or other entrained solid particles, is delivered to first stage hydrolysis 120 b and again subjected to high temperature and pressure to complete the breaking down of longer chain molecules in to shorter chains. The result is a reacted feed 122, i.e. a mixture of renewable fuel/oil, produced water, and fine entrained solids, the composition of which will be discussed in detail below in connection with the second or separation stage. Generally, first stage hydrolysis 120 b is carried out at temperatures in the range from about 200° C. (~392° F.) to about 350° C. (~660° F.) so that at least one of a number of transformations or reactions may occur.

For example, depending on feedstock composition, such transformations may include breaking of peptide linkages in proteins to yield individual amino acid residues (at about 150-220° C.), fat degradation into triglycerides, fatty acids, and glycerol (at about 200 2900C.), deamination and decarboxylation of amino acids, breaking of halogen and metal salt bonds and breaking of sulfur bonds. Those of ordinary skill in the art will readily appreciate that certain homogeneous feed stocks with little to no inorganic content, e.g. liquid raw feed, blood, etc., not requiring depolymerization can be fed directly to the first stage hydrolysis 120 b without detracting from the objects and advantages of the present invention.

The carboxylic acid groups, if allowed to proceed to a further processing step, still attached to their respective amino acid moieties, are converted to hydrocarbons at relatively mild operating conditions. Typically, amino acid deamination occurs in the range of about 210-320° C. (~410-610° F.). Thus, substantially all of the proteins present in the slurry are converted to amino acids at hydrolysis operating temperatures. Partial degradation of lignin occurs even at lower temperatures, e.g. 250 C.

(~480° F.), in the range provided above. Cellulose typically degrades at temperatures around 2750 C. (~530° F.) and hemicellulose starts to degrade around 150° C. (~300° F.). As will be appreciated by those of ordinary skill in the art, the degree of amino acid deamination can be controlled by a judicious choice of operating temperature. The actual conditions under which the first stage hydrolysis reactor is run can be modified according to the feedstock employed. Run time of this step may take anywhere between about 30 min to about 60 min, depending on the conditions employed.

The pressure in the first stage hydrolysis reactor is preferably selected to be close to the saturation pressure of the entrained water in the liquid mixture at the operating temperature in question. The saturation pressure is the pressure that needs to be applied at a given temperature to keep the water from boiling, and also depends on the presence and quantity of other gases in the purified feed slurry. The total pressure in the reactor is greater than the vapor pressure of the water in the slurry mixture, so that the water does not boil off. Typically, the pressure is adjusted by amounts up to, and in the range of, about 0-100 psi above saturation so that unwanted gases may be vented. Generally, the pressure may range between about 75 psig to about 800 psig.

As illustrated in FIG. 1, a mixture of steam and gaseous products 126 is also typically liberated from the slurry in first stage hydrolysis 120 b. The reacted feed 122 resulting from this stage typically consists of a mixture of reacted solid products and a mixture of reacted liquid products. These various products may be characterized as an oil phase, a water phase, and a wet solid mineral phase. The water phase and the oil phase typically contain various dissolved organic materials. In some embodiments of the invention, the mixture of steam and gases 126 produced in the first stage 120 is separated by a condenser, and the steam is routed to pre-heat incoming slurry to enhance the energy efficiency of the system.

As previously stated, complex organic molecules are broken down into smaller simpler molecules and hydrolyzed during the first stage hydrolysis reaction. It is in this step that fats are fully or partially split into fatty acids and glycerol groups, some of the amino acids decarboxylase or delaminated, and lignin partially or fully degraded. Carbohydrates are largely broken down into simpler, water soluble, sugars. Whatever proteins remained intact from the first stage decomposition will be generally broken down into constituent polypeptides, peptides, and amino acid subunits. Metals, metal salts and halogen ions also are freed under these conditions and reacted with water to facilitate their removal.

During first stage hydrolysis 120 b, some degasification takes place in which, inter alia, partial removal of nitrogen and sulfur compounds occur. Also deamination and decarboxylation reactions can take place in which significant quantities of protein dissociate into products such as ammonia and carbon dioxide. Decarboxylation reactions can be disfavored in some circumstances as the amines produced tend to be water soluble and volatile.

As such, deamination reactions may be preferred to decarboxylation reactions under appropriate conditions, and the reacted liquid products obtained from the end of the first stage 120 typically include carboxylic acids where the feedstock comprises proteins and fats. Accordingly, since decarboxylation reactions typically occur at higher temperatures than deamination reactions, first stage hydrolysis 120 b may be run at the lowest temperature possible at which fat molecules are split. Generally, hydrolysis can occur at a pH range from about 4 to about 8. Alternatively, the pH in the hydrolysis reaction can be adjusted to discourage decarboxylation reactions.

First stage hydrolysis 120 b provides an environment for the removal of such gaseous impurities as ammonia, carbon dioxide, and sulfur-containing gases and venting of sulfur containing gases from the breakdown of sulfur-containing moieties in the feedstock. Sources of sulfur may include various rubbers and protein molecules (which include cysteine and methionine residues). The combinatory effect of heat, pressure and time employed in this step also assures that any pathogens contained in the waste are destroyed. As such, embodiments of the present invention can be applied for the sterilization and treatment of biological waste.

Removal of halogen, metal salts, nitrogen and sulfur compounds at this stage, and the optional preheating step in feed preparation, prevents significant formation of organic nitrogen compounds, ammonia, and various sulfur compounds that might become undesirable components of the resulting hydrocarbons if allowed to proceed further along the system described herein.

Apparatus

In an exemplary embodiment of the present invention, first stage hydrolysis 120 b may be performed in a hydrolysis reactor 230 shown in FIG. 2, which may comprise a multi chamber vessel so that there is a narrow distribution of residence times of the constituent materials of the slurry. In alternative embodiments, the hydrolysis reactor can also be an augured reactor. In some embodiments, the heating and/or pressurizing of the slurry takes place in several stages ahead of the reactor vessel, for example in separate storage, pressurizing and heating unit 220. The reactor vessel may be equipped with baffles, and a multi-blade motorized stirrer that can simultaneously stir the slurry in each of the chambers. In one exemplary embodiment, the vessel has four chambers. The vessel should have sufficient strength to withstand pressure generated by the gas phase when the feed stream is subjected to operating conditions.

Second Stage: Separation

Referring to FIG. 1, reacted feed 122, which typically comprises at least one reacted liquid product and at least on reacted solid product and water, is fed to a second separation stage 130 to separate the components therein into steam and gases 132, produced water 13, hydrocarbon liquid or unfinished oil 500, and solids/minerals 134. The various components of reacted feed 122 can be separated, for example, by techniques described herein. Steam and gases 132 can be driven off and redirected to preheat incoming slurry.

Separation stage 130 may comprise one or more steps performed in series or simultaneously. In exemplary embodiments, the reacted feed first undergoes a solid/liquid separation then a liquid/liquid separation. The order of solid/liquid separation and liquid/liquid separation can be rearranged but, as recognized by those of ordinary skill in the art, the overall efficiency of the separation process may be affected. Mineral and other solid particles that were not removed during first stage 120 can be separated from the liquids by decanting, and the renewable oil and produced water separated using a centrifuge or by gravity separation. Once substantially isolated, the hydrocarbon liquid or unfinished oil can be piped into storage tanks and held for storage or further refined or processed into higher-value products.

In some embodiments of separation stage 130, as illustrated in FIG. 3, the reacted feed 122 is flashed to a lower pressure 340, and permitted to release excess heat back to the earlier heating stages. Typically, flashing is achieved through multiple pressure reductions, for example in two to three stages. The effect of flashing is to vent off remaining steam and gases 132 associated with the reacted feed. Dehydration via depressurization is efficient because water is driven off without using heat. The effective use of the excess heat is known as heat recovery, and represents a further advance of the process of the present invention.

After the reacted feed has been flashed 340, and heat has been recovered, the intermediate feed 400 still typically comprises at least one reacted liquid product, at least one reacted solid product, and water. The at least one reacted liquid product is typically a constituent of hydrocarbon liquid; the at least one reacted solid product typically comprises minerals. The intermediate feed preferably is substantially free of gaseous products.

FIG. 4 shows a sequence of separations that may be applied to the intermediate feed. It is another advantage of embodiments of the present invention that the intermediate feed resulting from first stage 120 may be subjected to one or more separation stages that remove minerals and water before processing in third stage or oil finishing step 140.

Intermediate feed 400, typically comprising hydrocarbon liquid, water, and some minerals or other contaminated solids is preferably subjected to a first separation 410 that removes most minerals and solids 412 and produces a mixture of hydrocarbon liquid and water 414. Such a separation may be characterized as a solid/liquid separation and may be achieved with a first centrifuge or via other known solid/liquid separation devices. Minerals and other solids 412 that are separated out are typically wet and thus may be subjected to a drying stage 420 before passing to a dry mineral storage 430. Drying typically takes place under normal atmospheric conditions. The resulting dry minerals may find considerable commercial application as a soil amendment or other industrial precursor.

The hydrocarbon liquid/water mixture 414 is subject to a second separation 440 to drive off the water and leave the hydrocarbon liquid 500. Such a second separation may be achieved using a second liquid/liquid centrifuge, gravity separation column or other separation device. Differences in the specific gravity allow centrifugal separation of the produced water and hydrocarbon liquid. The produced water 138 that is driven off typically contains significant amounts of dissolved small organic molecules such as glycerol and some water soluble amino acids that derive from the breakdown of proteins. The produced water also typically includes ash, chloride, and other impurities. Separating out such impurities prior to the oil finishing reactions when thermal-chemical platforms are used as described below represents an additional benefit of the present invention because later products are thereby not contaminated, which enhances the combustibility of the fuels produced.

The produced water 138 may be subject to concentration 139, such as by evaporation, producing a water condensate 151 that may be recycled within the process of the present invention, and a concentrate 153 that is dispatched to a concentrate storage 460. Evaporation is typically achieved by application of a slight vacuum. With feed stocks that yield a concentrate 153 largely comprising a slurry of amino acids, glycerol and, potentially ammonium salts such as ammonium sulfate or phosphate, the produced water will typically have commercial value as, for example, fertilizers known as "fish solubles" that are sold in domestic garden stores.

It is to be understood that the present invention is not limited to a separating stage comprising two steps. Nor is the present invention limited by the order in which any separation steps are carried out. Thus, it is consistent with the present invention if the separation of the intermediate feed 400 into products such as hydrocarbon liquid, minerals, and water occurs in a single step or in more than two steps.

Apparatus

Referring to the exemplary apparatus of FIG. 2, the flashing of the reacted feed second stage can be achieved in one or more flash vessels 240 with vents. Preferably the pressure in the flash vessel 240 is considerably lower than that in the hydrolysis reactor 230. In one embodiment, the pressure in the flash vessel is about 300 psig, where the pressure in the hydrolysis reactor is around 600 psig.

Various equipment can be used to achieve separation of the materials that come out of the first stage hydrolysis reactor 230. Such separations provide a mixture of steam and gases 132, hydrocarbon liquid 500, minerals 134, and produced water with solubles 138. Steam and gases 132 are preferably diverted back to the preparation stage to assist with feed heating.

Separation of the solids or particulate from the hydrocarbon liquid and water can be achieved with centrifuges, hydrocyclone or with a static tank. Drying of the minerals 134 can be achieved with, for example, a drying kiln or other mineral drier such as a "ring" dryer. In alternate embodiments, separation can be facilitated by adding agents to break up the emulsions or other unwanted combinations.

Produced water 138 with solubles resulting from the separation of the hydrocarbon liquid from the water, can be concentrated in a conventional evaporator 250. The hydrocarbon liquid 500 that has been separated from the minerals and the water may be contained in a hydrocarbon liquid holding vessel 252 prior to transfer to the an optional third stage or oil finishing reactor 260. Such a holding vessel may be an ordinary storage vessel as is typically used in the industry.

Based on the teachings contained herein, a person of ordinary skill in the art may optionally include in the second stage separation centrifuges, hydrocyclone, distillation columns, filtration devices, and screens. It will also be understood that distillation can be employed to remove very fine carbon solids from an intermediate feed 400. In general, further pressure reduction recovers more steam, and facilitates solid/liquid separation to recover minerals and other solids.

Useful Products and Third Stage: Oil Finishing

Products and intermediates of the invention described above can optionally be used as is or subjected to further processing, as can be discerned by those of ordinary skill in the art directed by the present disclosure. For example, hydrocarbon oil bearing similar constituency to a #4 diesel oil can be produced with minimal oil finishing 140, essentially consisting of on-site processing to further separate oil and residual water and particulate fractions from the hydrocarbon liquid 500. Such minimal processing may be characterized as oil polishing and may comprise gravity decanting and/or dehydrating with heat to achieve minimal moisture content. Additional fine filtering, such as bag filters, may be used to achieve further particulate removal as necessary.

In some embodiments, as indicated in FIG. 1, some or the entire portion of hydrocarbon liquid 500 can optionally be directed for processing ahead of the oil finishing stage 140 to yield one or more specialty chemicals 143. For example, a portion of hydrocarbon liquid 500 may be diverted to an optional separation step 137 to form specialty organic chemicals 143 such as fatty acids or amino acids, e.g. via fractional distillation. The hydrocarbon liquid that is subjected to fractional distillation is typically distilled in a distillation column 254 (FIG. 2).

The hydrocarbon liquid may be subjected to an acid wash to separate out trace amino acids before passing it to the distillation column. More volatile materials from the hydrocarbon liquid, such as fatty acids, are distilled off and collected. In some embodiments, any residual fractions, fractionated liquor 145, often called "heavy liquor," that comprises fractions not useful as specialty chemicals, can be redirected to third stage 140. Such residual fractions may contain non-volatilized fats and fat derivatives that are found in the bottom of the distillation column and can be passed on to an oil finishing stage reactor 260.

Optionally, the solids/minerals 134 isolated from separation 130 can be directed to a calciner to burn off any residual organic therefrom and be calcined. Other materials generated at various points of the process described herein, e.g. concentrated noncondensable gas, solid inorganic 116, and aqueous concentrate fuel, can likewise be routed to a calciner for further processing. In some embodiments, the calciner serves a dual function in producing calcined solids and producing hot oil and/or steam for use in a variety of applications. For example, the hot steam can be used to drive a steam turbine in electric power plants or other industrial and manufacturing contexts.

While the produced water 138 from separation stage 130 can be used as-is, it also may be diverted for concentration 139 to yield a condensate 151 and concentrate 153. Depending on the composition of feedstock used, e.g. PVC, switch grass, or proteins, the produced water 138 may contain sulfur- and/or chlorine-containing materials. Condensate 151 is typically of a purity above that of municipal-strength waste water. Where nitrogenous waste, for instance, is received as the feedstock to the process, the composition of concentrate 153 can be used as an organic fuel or liquid fertilizer, having a chemical constituency similar to fish solubles. Alternatively, the produced water 138 can be piped directly into storage tanks for characterization before choosing a manner of disposal.

Alternatively, in some embodiments, third stage 140 may involve further in a thermal chemical platform. For example, the hydrocarbon liquid 500 may be coked either on-site or at a refinery according to methods known in the art to produce fuel-gas 146, carbon solids 142, and finished oil 144. Other thermal-chemical treatments include vis-breaking, hydro treating, gasifying and paralyzing. While techniques such as gasifying and paralyzing raw waste streams have proven less than successful, due to the homogeneity of the output from second stage separation 130 in embodiments of the present invention, such treatments can be more successfully employed.

In exemplary oil finishing 140 involving a thermal chemical platform, hydrocarbon liquid 500 is subjected to conditions wherein it undergoes a reaction that may involve one or more processes known in the art, such as distillation for fatty acids, thermal cracking, catalytic cracking, etc. It is also possible that the hydrocarbon liquid contains some quantity of reacted solid product that is also passed to oil finishing 140. Together, the hydrocarbon liquid and reacted solid product may be referred to as a solid matrix. In this instance, the hydrocarbon liquid is converted to a mixture of useful materials that usually includes carbon solids 142, and a mixture of hydrocarbons that is typically released as hydrocarbon vapor and gases 148.

Such a conversion may involve a decomposition of one or more materials in the hydrocarbon liquid. Suitable conditions in the oil finishing 140 typically use temperatures that are elevated with respect to the first stage, and pressures that are reduced with respect to the first stage hydrolysis 120 b. The oil finishing typically does not involve the use of added water. A number of different apparatuses may be employed to effect the oil finishing in third stage 140.

In one exemplary embodiment of the third stage 140, the water content of the hydrocarbon liquid 500 is almost zero, so that the conditions of the third stage are such that the remaining organic molecules are broken down largely by application of a high temperature, rather than by hydrolysis by excess, or added, water or steam. Temperature conditions for carrying out such third stage reactions may be around 400 C.-600° C. (~750-1110° F.). Such a third stage reaction typically takes from about 5 minutes to about

120 minutes. In practice, the various phases of the liquor spend varying amounts of time in the third stage reactor. For example, the vapors pass through relatively quickly, and the liquids take longer.

The output from the third stage comprises, separately, a mixture of hydrocarbon vapor and gases 148 such as carbon dioxide, CO, and nitrogen and sulfur containing compounds, and carbon solids 142. The carbon solids 142 preferably resemble high quality coke. The mixture of hydrocarbon vapor and gases 148 typically contains oil vapor. The conditions of the third stage are preferably selected to optimize the purity of the carbon solids 142, and the mixture of hydrocarbon vapor and gases 148. Rapid quench of hot vapors, such as the mixture of hydrocarbon vapor and gases 148, stops reactions and minimizes carbon char formation after the third stage.

In an exemplary embodiment, rapid quenching of vapors may be achieved by directing the vapors into a drum full of water or by multiple quenching steps using thermal fluids and cooling mediums. Where such multiple quenching steps are employed, it is advantageous to take multiple cuts (diesel, gasoline, etc.) from the oil so that the various fractions can be diverted to separate commercial applications. Alternatively, in another embodiment, the oil vapor may be quenched in the presence of the incoming hydrocarbon liquid, thereby also facilitating energy recovery.

Where a thermal chemical platform is employed in the third stage, typically it will be carried out at temperatures in the range of about 400° C. (~7500 F.) to about 600° C. (~1110° F.), so that at least one of the following two transformations can occur. First, carboxylic acids are broken down to hydrocarbons. This can be achieved by removing the carboxyl group from each fatty acid molecule at temperatures in the range approximately 315-400° C. (~600-750° F.). Second, hydrocarbon molecules themselves are "cracked" to form a distribution of molecules of lower molecular weights, a process that can occur in the range approximately 450-510° C. (~840-950° F.). Typically, however, hydrocarbon cracking occurs at temperatures above 480° C. (~895° F.). The third stage may be carried out at a higher temperature than that for the first stage.

In at least one embodiment, the third stage reactor is pressurized to a pressure between about 15 psig and about 70 psig. In some embodiments, the pressure in the third stage reactor may be lower than that in the first stage.

An example of third step stage oil finishing is illustrated in FIG. 5. Carbon solids 142 generated from a third stage reactor as described above are typically first passed to a carbon solids cooler 630 wherein the carbon is permitted to lose its residual heat. After cooling, the carbon sol ids 142 are passed to carbon storage 540 and subsequent use. The mixture of hydrocarbon vapor and gases 148 produced by the third stage reactor can be directed to a cooler/condenser 850 which separates the mixture into fuel-gas 146 and a hydrocarbon oil 144.

Other optional third stage and oil finishing apparatuses and methods are described in detail in U.S. patent application Ser. No. 11/529,825, filed Sep. 29, 2006, now published as

U.S. publication no. 20070098625, the contents of which is incorporated herein by reference in its entirety for all purposes.

Claims

WE CLAIM

1) Our invention "Plastics & Packing Materials "is a biodegradable packaging material comprising an expanded high amylose starch product having at least 45% by weight amylose content, said expanded product having a low density, closed cell structure with good resilience and compressibility. The invention also provides a method of preparing a low density, biodegradable packaging material comprising extruding a starch having at least 45% by weight amylose content, in the presence of a total moisture content of 21% or less by weight, at a temperature of from 150 to 250° C. The invented technology also includes a Conversion of waste and other organic feedstock into sustainable energy, feed, fertilizer, and other useful products of reliable purities is accomplished using water, heat, and pressure. The invention is also providing methods and apparatus that handle mixed streams of various feed stocks, e.g. agricultural waste, biological waste, municipal solid waste, municipal sewage sludge, and shredder residue, to yield gas, oil, specialty chemicals, and carbon solids that can be used as is or are further processed. Useful products can be diverted at various points of the process or internalized to enhance the efficiency of the system.

2) According to claims# the invention is to a biodegradable packaging material comprising an expanded high amylose starch product having at least 45% by weight amylose content, said expanded product having a low density, closed cell structure with good resilience and compressibility.

3) According to claiml,2# the invention is to a method of preparing a low density, biodegradable packaging material comprising extruding a starch having at least 45% by weight amylose content, in the presence of a total moisture content of 21% or less by weight, at a temperature of from 150° to 250° C.

4) According to claim,2,3# the invention is to a Conversion of waste and other organic feedstock into sustainable energy, feed, fertilizer, and other useful products of reliable purities is accomplished using water, heat, and pressure.

5) According to claiml,2,4# the invention is to a methods and apparatus that handle mixed streams of various feed stocks, e.g. agricultural waste, biological waste, municipal solid waste, municipal sewage sludge, and shredder residue, to yield gas, oil, specialty chemicals, and carbon solids that can be used as is or are further processed. Useful products can be diverted at various points of the process or internalized to enhance the efficiency of the system.

FIG. 7 is a schematic diagram of an exemplary depolymerization reactor;