SYSTEMS AND METHODS FOR STILLAGE FRACTIONATION
20210214659 · 2021-07-15
Inventors
Cpc classification
C12M43/00
CHEMISTRY; METALLURGY
Y02E50/10
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
C12M47/10
CHEMISTRY; METALLURGY
C11B1/00
CHEMISTRY; METALLURGY
Y02P60/87
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
International classification
C10L1/02
CHEMISTRY; METALLURGY
C11B1/00
CHEMISTRY; METALLURGY
Abstract
Systems and methods for fractionating whole stillage from an ethanol production facility are provided. Whole stillage undergoes a separation of its liquid portion (thin stillage) from the solid portion (fiber cake). In some embodiments, the solids and liquids in whole stillage may be separated utilizing a screening centrifuge. The fiber cake may be dried to generate a high fiber animal feed. The thin stillage may be provided to a three-phase separator for separation into an oil emulsion, an aqueous clarified stillage, and a protein paste. The protein paste may be dried to generate a high protein animal feed with greater than about 45% protein content. The clarified thin stillage is condensed to yield a syrup with greater than around 60% solids. The oil emulsion is subjected to a pH adjustment to liberate the oil from the emulsion, which is then separated.
Claims
1-19. (canceled)
20. A method for processing whole stillage in an ethanol plant, comprising: a) separating thin stillage liquid from the whole stillage; b) separating protein paste and clarified liquid stillage output from the thin stillage liquid; and c) sending at least a portion of the clarified liquid stillage output to an evaporation system to concentrate the clarified liquid stillage output into a concentrated, clarified liquid stillage having at least 60% solids.
21. The method of claim 20, wherein separating the thin stillage liquid from the whole stillage produces a fiber cake.
22. The method of claim 21, further comprising drying the fiber cake to provide a high fiber animal feed product.
23. The method of claim 20, further comprising drying protein paste to provide a high protein animal feed product.
24. The method of claim 20, wherein the concentrated, clarified liquid stillage is used as an animal feed supplement.
25. The method of claim 20, further comprising recycling a portion of the clarified liquid stillage output upstream for utilization as fermentation backset.
26. The method of claim 20, wherein separating thin stillage liquid from the whole stillage comprises separating thin stillage liquid from the whole stillage via filtration, centrifugation, pressing, and combinations thereof.
27. The method of claim 20, wherein separating thin stillage liquid from the whole stillage comprises separating thin stillage liquid from the whole stillage via one or more membranes, one or more screw presses, one or more decanters, one or more centrifuges, one or more filters, and combinations thereof.
28. The method of claim 20, wherein separating thin stillage liquid from the whole stillage comprises separating thin stillage liquid from the whole stillage via one or more filtration centrifuges.
29. The method of claim 20, wherein the thin stillage liquid is not subjected to an evaporator prior to separating protein paste and clarified liquid stillage output from the thin stillage liquid.
30. The method of claim 20, wherein separating protein paste and clarified liquid stillage output from the thin stillage liquid comprises separating protein paste and clarified liquid stillage output from the thin stillage liquid via filtration, centrifugation, and combinations thereof.
31. The method of claim 20, wherein separating protein paste and clarified liquid stillage output from the thin stillage liquid comprises separating protein paste and clarified liquid stillage output from the thin stillage liquid via a separation system comprising one or more separators, wherein the one or more separators are chosen from chosen from a three phase separator, a disk nozzle type centrifuge, a decanter centrifuge, and combinations thereof.
32. A method for processing whole stillage in an ethanol plant, comprising: a) separating thin stillage liquid from the whole stillage; b) separating protein paste output and oil emulsion from the thin stillage liquid; c) drying protein paste output via a dryer system to form a protein animal feed product; and d) separating oil from the oil emulsion.
33. The method of claim 32, wherein the protein animal feed product has at least 45% protein.
34. The method of claim 32, wherein separating protein paste output from the thin stillage liquid comprises separating the thin stillage liquid into a clarified liquid stillage, an oil emulsion and the protein paste output.
35. The method of claim 34, further comprising sending at least a portion of the clarified liquid stillage to an evaporation system to concentrate the clarified liquid stillage into a concentrated, clarified liquid stillage.
36. The method of claim 32, wherein separating oil from the oil emulsion forms a residual aqueous layer, wherein the residual aqueous layer comprises protein; and further comprising forming an animal feed product with at least a portion of the residual aqueous layer.
37. The method of claim 36, wherein the at least a portion of the residual aqueous layer and protein paste output are dried in a dryer system to form an animal feed product.
38. The method of claim 36, wherein separating thin stillage liquid from the whole stillage comprises separating the whole stillage into thin stillage liquid and fiber cake, wherein the at least a portion of the residual aqueous layer is combined with the fiber cake.
39. The method of claim 32, wherein separating thin stillage liquid from the whole stillage comprises separating thin stillage liquid from the whole stillage via filtration, centrifugation, pressing, and combinations thereof, and wherein separating protein paste output and oil emulsion from the thin stillage liquid comprises separating protein paste output and an oil emulsion from the thin stillage liquid via filtration, centrifugation, and combinations thereof.
40. The method of claim 32, wherein separating thin stillage liquid from the whole stillage comprises separating thin stillage liquid from the whole stillage via one or more membranes, one or more screw presses, one or more decanters, one or more centrifuges, one or more filters, and combinations thereof, and wherein separating protein paste output and oil emulsion from the thin stillage liquid comprises separating protein paste output and an oil emulsion from the thin stillage liquid via a separation system comprising one or more separators, wherein the one or more separators are chosen from a three phase separator, a disk nozzle type centrifuge, a decanter centrifuge, and combinations thereof.
41. The method of claim 32, wherein separating thin stillage liquid from the whole stillage comprises separating thin stillage liquid from the whole stillage via one or more filtration centrifuges.
42. A method for processing whole stillage in an ethanol plant, comprising: a) separating thin stillage liquid and fiber cake from the whole stillage; b) separating protein paste and oil emulsion from the thin stillage liquid; c) separating oil from the oil emulsion to form a residual aqueous layer, wherein the residual aqueous layer comprises protein; and d) forming an animal feed product with at least a portion of the residual aqueous layer and at least a portion of the protein paste and/or at least a portion of the fiber cake.
43. A method for processing whole stillage in an ethanol plant, comprising: a) separating a liquid portion from the whole stillage; b) separating clarified liquid stillage output and oil emulsion from the liquid portion; c) separating oil from the oil emulsion; and d) recycling a portion of the clarified liquid stillage output upstream for utilization as fermentation backset.
Description
DESCRIPTION OF THE DRAWINGS
[0018] In order that the various aspects may be more clearly ascertained, some embodiments will now be described, by way of example, with reference to the accompanying drawings, in which:
[0019]
[0020]
[0021]
[0022]
[0023]
[0024]
DESCRIPTION OF THE EMBODIMENTS
[0025] The various aspects will now be described in detail with reference to several embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the various aspects. It will be apparent, however, to one skilled in the art, that embodiments may be practiced without some or all of these specific details. In other instances, well known process steps and/or structures have not been described in detail in order to not unnecessarily obscure the disclosed aspects. The features and advantages of embodiments may be better understood with reference to the drawings and discussions that follow.
[0026] The following description relates to systems and methods for fractionating stillage from an ethanol production plant or other processing facility. Ethanol plants generate large quantities of stillage as a low value product. Stillage is generally a low value co-product that requires substantial energy to dry into solubles for addition to distillers dried grains, or must be disposed of in some other manner. There is the potential for the generation of high value co-products from stillage, thus, the disclosed aspects provide for systems and methods that improve stillage utilization, which can generate multiple high quality co-products without unduly influencing the water balance of the ethanol production facility. Such systems and methods can provide increased revenue from co-products and a lower impact on the environment.
[0027] The disclosed systems and methods provide a means to substantially improve the quality and value of stillage by fractionating the stillage into components, each highly valued in their own right. The fractions generated by the disclosed systems and methods, in addition to being intrinsically valuable, provide an improved water balance for the ethanol production facility, thereby reducing the energy required to process the stillage over traditional evaporation and drying.
[0028] Referring to
[0029] Referring to
[0030] The product of fermentation (fermentation product 222) is beer, which comprises a liquid component, including ethanol and water and soluble components, and a solids component, including unfermented particulate matter (among other things). The fermentation product may be treated with agents 224 in a second treatment system 226. The treated fermentation product 228 is sent to a distillation system 230. In the distillation system 230, the (treated) fermentation product is distilled and dehydrated into ethanol 232. In some embodiments, the removed components 234 (e.g., whole stillage), which comprise water, soluble components, oil, and unfermented solids (e.g., the solids component of the beer with substantially all ethanol removed), may be dried into dried distillers grains (DDG) in a third treatment system (where the removed components may be treated with agents) and sold as an animal feed product. Other co-products, for example, syrup (and oil contained in the syrup), may also be recovered from the stillage, as will be described in further detail below.
[0031] In some systems, the thin stillage that results when solids are removed from the whole stillage can be used as a backset during the fermentation process and also can be used to increase the fat content of DDGS (Distillers Dried Grains with Solubles). However, the addition of thin stillage to DDGS requires costly evaporation processes that increase the DDGS production cost. Disclosed herein are systems and methods for fractionating the whole stillage in order to generate relevant quantities of valuable co-products in a manner which ultimately reduces the required fuel spent on evaporation.
[0032] Referring now to
[0033] The solid component comprises a high fiber cake 308, which may be dried at a dryer 310 to a high fiber dried distillers grain (DDG) 312 product. Such high fiber DDG may be particularly suited for the poly-gastric animal feed markets (ruminant feed). In some embodiments, the fiber cake may additionally undergo a washing step prior to being dried. The wash fluid may be combined with the liquid thin stillage, in some embodiments.
[0034] Separation of the fiber cake solids from the thin stillage may be performed soon after initial production of the felmentation product (whole stillage) in order to maintain co-product composition quality and to prevent undue exposure of the co-products to heat, oxygen, and potential contaminants. If the whole or thin stillage is left exposed for extended periods of time in the presence of moisture, hydrolysis of the oils may occur which leads to the formation of free fatty acids, which degrades the quality of oil produced.
[0035] The resulting liquid thin stillage 306 is provided to a three phase separator 314, which may include a disk nozzle type centrifuge or suitable filtration type system. The three phase separator 314 separates the thin stillage 306 into a top layer of oil emulsion 318, a middle aqueous clarified thin stillage 320, and a protein paste 322. One of ordinary skill in the art will appreciate that the speed or amount of centrifugal force applied will depend on various factors such as sample size and may be adjusted appropriately depending on such factors. Suitable separators and centrifuges are available from at least the manufacturers listed above.
[0036] The protein paste 322 may be dried in a dryer 324 to a high protein DDG product 326. The high protein DDG may be particularly suited for mono-gastric (non-ruminant) and young animal feed. The high protein DDG may have high metabolize-able energy and a lysine content of between about 2% and about 3%, which can be important in feed ration formulations.
[0037] The clarified thin stillage 320 may be condensed through evaporation 328 or concentrated by reverse osmosis to yield high solid syrup 330. Due to low levels of suspended solids in the clarified thin stillage, high total solids can be achieved in a concentrated syrup without substantial viscosity limitations. The high solids syrup 330 may have between about 30 and 80 percent solids, dependent upon material handling properties desired, as well as end use. In some particular embodiments, the high solid syrup may contain greater than around 60% solids. High solid syrup 330 may be marketed as a high energy animal feed supplement. In alternate embodiments, some portion of the clarified thin still age may be utilized as a backset for fermentation, thereby further reducing the need for evaporation further.
[0038] The oil emulsion 318 may be pH treated by an alkali in order to disrupt the emulsion. The adjustment of pH may be critical for the liberation of the oil from emulsion, and may result in greater oil yields and enhanced oil quality. Particularly, adjusting the pH of the oil fraction separates or breaks the oil fraction such that the resulting oil recovered has a low fatty acid content. The age of the fermented product and the organic acid content of the fermented product can affect the optimum pH for separation, however, the oil fraction is treated with the highest pH possible to reduce the overall free fatty acid content in the separated oil without sacrificing oil quality. In some embodiments, the pH is adjusted to a range of about 7 to about I 0. In some particular embodiments, the pH is adjusted to between around 8.0 and around 8.5.
[0039] Oil 332 may be separated from the remaining emulsion/aqueous layer through centrifugation, filtration, distillation or other suitable separator 334. The remaining aqueous layer/emulsion may be high in protein and recycled for addition to DDG or sold as a separate feed product.
[0040] The oil composition recovered from the aspects described herein may be further processed in a variety of ways. For example, the crude oil may be filtered and bleached to provide a food grade oil for consumer use. In one embodiment, the crude oil may be degummed, further caustic refined, and subjected to a soap removal step according to commercially available processes. Following these steps, the oil may be subjected to one or more clay bleaching steps to achieve an oil of desired content and color. If one or more clay bleaching steps are used, the clay may be an acid clay or a non-acid clay. In one embodiment, the bleaching step may include, by way of example, an acid clay or a non-acid clay at around 1% to around 5% based on the total weight. In addition to or as an alternative to clay bleaching, after the crude oil has been degummed, caustic refined and subjected to a soap removal step, a food grade oil of a desired color may be achieved using a heat bleaching step.
[0041] The oil composition can be used in a wide variety of applications. Such exemplary applications include the areas of oleochemicals, feed (e.g., animal feed) as well as oils suitable for human consumption. Oleochemicals include feedstock chemicals that are suitable for biodiesel production (fatty acid methyl esters). Industrial oleochemicals are useful in the production of soaps, detergents, wire insulation, industrial lubricants, leather treatments, cutting oils, mining agents for oil well drilling, ink removal, plastic stabilizers, ink, and in rubber production. Other industrial applications include waxes, shampoos, personal hygiene and food emulsifier or additive products. It is also possible in some embodiments, to pre-treat oil for downstream uses, such as conversion to bio-diesel.
[0042] The recovered oil composition can contain low levels of moisture, insolubles and unsaponifiables (MIU content). Moisture, as contemplated herein, includes water and any volatile material such as, for example, hexane, ethanol, methanol, or a combination thereof Insoluble matter (i.e., “insolubles”), as contemplated herein, refers to and includes any matter incapable of being dissolved in the aqueous portion, oil fraction or oil composition. Unsaponifiable matter (i.e., “unsaponifiables”) includes any variety of possible non-triglyceride materials that act as contaminants during bio-diesel production. Usaponifiable matter can significantly reduce the end product yields of the oil composition and can, in turn, reduce end product yields of processes such as, for example, bio-diesel production processes.
[0043] Maintaining low levels of moisture is especially desirable because moisture fosters the formation of free fatty acids instead of esters. In one embodiment, the oil composition contains no greater than around 1% w/w of total moisture content, alone, based on the total weight of the oil composition. In some embodiments, the moisture content, alone, is no greater than about 0.5% w/w or about 0.1% w/w.
[0044] In one embodiment, the oil composition comprises no greater than approximately 3% w/w ofunsaponifiables, based on the total weight of the oil composition. In some embodiments, the oil composition comprises no greater than around 2% w/w or around 1% w/w ofunsaponifiables.
[0045] In one embodiment, the oil composition contains no greater than about 1% w/w insolubles, alone, based on the total weight of the oil composition. In some embodiments, the insolubles content, alone, is no greater than approximately 0.5% w/w or approximately 0.1% w/w.
[0046] The oil composition may, in some embodiments, exhibit an iodine value acceptable for bio-diesel production and, in some embodiments, exhibits an iodine value higher than that expected from a neat oil sample. The oil can further comprise various carotene, carotenoid, and antioxidant or neutraceutical compounds.
[0047] In one embodiment, the oil composition contains no greater than about 5% w/w free fatty acid content, based on the total weight of the oil composition. In some embodiments, the free fatty acid content, is no greater than around 3% w/w.
[0048] The fatty acid content of the oil composition is comprised of various fatty acids known in the art. In one embodiment, the oil composition comprises C 16 palmitic acid which represents no greater than about 15% w/w of the total fatty acid content, based on the total weight of the oil composition. In another embodiment, the C 16 palmitic acid content is no greater than around 10% w/w of the total fatty acid content. In one embodiment, the oil composition comprises C 18 stearic acid which represents at least about 3% w/w of the total fatty acid content, based on the total weight of the oil composition. In another embodiment, the C18 stearic acid content is at least about 1.5% w/w of the total fatty acid content. In one embodiment, the oil composition comprises C18-1 oleic acid which represents at least around 30% w/w of the total fatty acid content, based on the total weight of the oil composition. In another embodiment, the C18-1 oleic acid content is at least about 25% w/w of the total fatty acid content. In one embodiment, the oil composition comprises C18-2 linoleic acid which represents at least around 60% w/w of the total fatty acid content, based on the total weight of the oil composition. In another embodiment, the C18-2 linoleic acid content is at least around 50% w/w of the total fatty acid content. In one embodiment, the oil composition comprises C18-3 linolenic acid which represents no greater about 1.5% w/w of the total fatty acid content, based on the total weight of the oil composition. In another embodiment, the C18-3 linolenic acid content is no greater than about 0.5% w/w of the total fatty acid content.
[0049] Since the entire thin stillage is not evaporated, in these embodiments, there is substantial fuel and cost savings over traditional stillage handling which includes the substantial evaporation of the thin stillage for addition back to the DDG to generate dried distillers grains with solubles (DDGS). As such, not only are greater quantities of higher value products generated through the disclosed treatment of the whole stillage, but additionally, the process utilizes less fuel thereby reducing pollution generated and reducing operational costs.
[0050]
[0051] In some embodiments, due to the composition of the fiber cake, there is less water retention of the product after separation of the thin stillage and washing. As the fiber cake includes less water, there is a substantial reduction in drying costs associated with the production of the high fiber dried distiller grain (HF-DDG) co-product over a more traditional DDG product. In some embodiments, the solid content of the fiber cake may be as high as between around 40% to around 45% solids before drying, as opposed to a wet cake (used to make conventional DDG) which typically includes only about 30% to around 35% solids prior to drying.
[0052] In some embodiments, the thin stillage is fractionated (at 406) into an oil emulsion, a protein paste, and a clarified thin stillage. The protein paste, which includes a high lysine content, is dried (at 408) to generate a high protein dried distillers grain (DDG HP). In some embodiments, the protein paste may also be returned to the fiber cake and dried together to generate an enhanced DDG product. Handling of the protein paste may be determined by market considerations, and equipment available at the ethanol production facility.
[0053] The thin stillage may then be condensed (at 410) to a high solids content (e.g., between around 30 to 80 percent solids) to generate a high solids syrup. High solids syrups are usable as an effective animal feed substitute, however the generation of practical high solid syrup may be difficult to obtain. This is because most syrups generated from thin stillage, once the solid content approaches about 30 percent, become prohibitively viscous, and are unusable as a marketable co-product. By processing the thin stillage to a clarified thin stillage, ultra high solids content (e.g., greater than about 30%) is achievable in a syrup which retains a viscosity of molasses. Thus, the co-product is easily transported and handled by prospective buyers.
[0054] Lastly, the oil emulsion is treated to extract valuable oil (at 412). Oil extraction is facilitated by pH adjusting the emulsion with an alkali. The addition of the caustic agent disrupts the emulsion and liberates the oil. The liberated oil may be extracted from the remaining emulsion via decanting, centrifugation, filtration or other suitable method. In some embodiments, greater than about 1.33 pounds of corn oil are achieved per bushel of corn utilizing the disclosed embodiments.
[0055] A series of limited examples were conducted according to an exemplary embodiment of the system (as shown in
Example 1
[0056] In this example experiment, whole stillage was screened utilizing a screen centrifuge in order to obtain a fiber cake and thin stillage. The fiber cake was dried and tested for composition. The thin stillage was further processed by decanter centrifuge to yield an oil emulsion, clarified thin stillage and a protein paste. The protein paste was dried. The clarified thin stillage was evaporated to over 60% solids content. The oil emulsion was treated using a caustic agent to adjust the pH to about 8. The oil emulsion was again subjected to centrifugation in order to remove the oil form emulsion. The oil, dried protein paste and high solid syrup were then subjected to compositional analysis. The results of this analysis are provided in relation to TABLE 1 of
[0057] In summary, the oil product had 0.9% moisture content, 3.03% free fatty acids (FFA), <0.01% insolubles, and 1.13% unsaponifiables. The high solids syrup composition was 31.6% moisture, 10.9% protein, 0.1% fiber, 6.1% ash, and 8.2% fat.
[0058] The protein paste composition was 58.6% protein, 12.6% fat, and <1% fiber. The high fiber DDG composition was 26.0% protein, 10% fiber, 3.5% fat, and 0.7% ash.
[0059] The yields of the four products on a percentage basis are approximately 9% oil, 13% syrup, 40% protein, and 38% fiber. These yields correspond to 1.3 lb oil, 2 lb syrup, 6 lb protein, and 6 lb fiber on a pound per bushel basis. The yields expected can lead to changes to the expected compositions due to tradeoffs between yield and purity. The expected compositional ranges from commercial production of these products are show in TABLE 2 of
[0060] The embodiments as disclosed and described in the application (including the FIGURES and Examples) are intended to be illustrative and explanatory. Modifications and variations of the disclosed embodiments, for example, of the apparatus and processes employed (or to be employed) as well as of the compositions and treatments used (or to be used), are possible; all such modifications and variations are intended to be within the scope of the various aspects presented herein.
[0061] The word “exemplary” is used to mean serving as an example, instance, or illustration. Any embodiment or design described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs, nor is it meant to preclude equivalent exemplary structures and techniques known to those of ordinary skill in the art. Rather, use of the word exemplary is intended to present concepts in a concrete fashion, and the disclosed subject matter is not limited by such examples.
[0062] Reference throughout this specification to “one aspect,” or “an aspect,” or “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the aspect or embodiment is included in at least one aspect or one embodiment. Thus, the appearances of the phrase “in one aspect,” or “in an aspect,” or “in one embodiment,” or “in an embodiment” in various places throughout this specification can, but are not necessarily, referring to the same aspect or embodiment, depending on the circumstances. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more aspects or embodiments.
[0063] The term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” To the extent that the terms “comprises,” “has,” “contains,” and other similar words are used in either the detailed description or the claims, for the avoidance of doubt, such terms are intended to be inclusive in a manner similar to the term “comprising” as an open transition word without precluding any additional or other elements.