System and method for producing pure starch slurry and alcohol using process combining wet corn milling and dry corn milling

Abstract

The present invention relates to a system and method for producing pure starch slurry and alcohol through a process combining wet corn milling and dry corn milling. The invention provides a simple and low-cost method for obtaining starch from corn flour endosperm. The starch can be highly purified to meet the requirements of green technical processes. Starch remaining within the corn kernels can be used as a feedstock for alcohol production and produce valuable by-products, such as oil and various animal feeds.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 63 / 353,480, filed on June 17, 2022, entitled “SYSTEM AND METHOD FOR PRODUCING PURE STARCH SLURRAY AND ALCOHOL USING A PROCESS THAT COMBINES WET CORN GROUNDING AND DRY CORN GROUNDING,” which is hereby incorporated by reference herein for all purposes. [Technical field]

[0003] The present invention relates to a method for producing starch, especially pure starch slurry, by combining dry grinding process and wet grinding process. The starch slurry can be used as raw material for subsequent processes requiring high-purity starch, especially biofuel, biochemistry, synthetic biology, renewal chemistry and other green technology processes. [Background technology]

[0004] For nearly fifty years, corn wet milling has been used to produce pure starch slurry. This pure starch slurry is then converted into corn syrup for human consumption. This low-cost corn syrup has largely replaced table sugar as a sweetener in processed foods. Unfortunately, excessive consumption of this high fructose corn syrup can have adverse effects on human health. At the same time, the world's population consumes a lot of petroleum fuels, producing a lot of carbon dioxide, which contributes to global warming.

[0005] Many "green" technology companies have studied the use of starch as a feedstock to replace fossil fuel hydrocarbons. In the United States, more than 200 dry-milling ethanol plants have been built, producing more than 15.8 billion gallons of fuel ethanol each year. The dry-milling process is a technology with a history of more than 2,000 years. This process converts starch from grains into alcohol and produces a low-value byproduct, dried distillers grains (DDGS), which is used as animal feed.

[0006] For a typical dry milling process, all insoluble solids (such as fiber and protein) in the liquefied starch solution can also be removed by filtration to produce a clean sugar solution. However, this clean sugar solution still contains all soluble solids, such as ash from corn flour, and a small amount of corn oil. Many new green technology processes require high-purity starch from wet milling as a raw material, but do not need the oil and soluble solids from corn kernels.

[0007] Typical corn kernels Figure 7 The corn kernel consists of the husk, floury endosperm, horny endosperm (whose cells are filled with starch granules in a protein matrix), germ and cap. Typical corn ingredients are shown in Table 1 below.

[0008] Table 1

[0009] Yellow dent corn ingredients

[0010] Dry basis

[0011]

[0012]

[0013] Figure 1 A typical corn wet milling process is shown 10. In step 11, the corn raw material is fed by continuous or batch soaking. The corn is soaked in a sulfur dioxide solution of about 200 PPM for 50-60 hours to soften the corn kernels. The corn is soaked until the water is completely absorbed to about 50% dry solids (DS). In step 15, the excess soaking liquid enters the evaporator.

[0014] In step 11, the soaked corn is sent to step 12A for the first grinding to break the whole corn and release the starch in the powdery endosperm. A starch slurry of about 12 degrees Baume is obtained in this step (the degree Baume or "Be" refers to the density of the liquid). In step 13, this 12 degrees Baume starch slurry, which serves as a liquid medium containing germ, corn grits and fiber particles, is pumped to the first set of double germ cyclone separators to separate the germ from the corn grits and fiber by utilizing the density difference in germ separation. In step 13, the germ particles, which are lighter than the 12 degrees Baume starch slurry, will come out from the top of the first germ cyclone separator as a light phase. It is then dehydrated and washed to obtain the germ (as a germ by-product) for further recovery of corn oil. Still referring to step 13, corn grits and fiber particles heavier than the 12 Baume starch slurry will come out of the bottom of the second germ cyclone separator and then undergo a second (fine) grinding and dewatering in step 12b to grind the corn grits (horny endosperm) to release more starch and remove / recover the germ from the steeped corn through the degermination process.

[0015] Baumé, or Be, is a unit commonly used in the wet milling industry to measure the starch content in starch slurries. Calculated in weight units, one Baumé is equal to 1.777 wt% of the starch content in the starch solution / slurry. In the wet milling industry, the weight percentage of starch slurries producing 23 Baumé is about 40%, a purity that can be used as a raw material for biotechnology processes.

[0016] Still referring to step 13, the heavy phase slurry from the bottom of the second germ cyclone separator for germ / corn grits separation is discharged to step 12b for liquid / solid separation. In step 12B, a pressure screen is used to separate fine particle (particles less than 50 microns (μm)) starch and corn bran from larger particle corn grits and fiber. A five-stage countercurrent fiber washing system is typically used to wash the starch and corn bran on the fiber. In step 16, the fine particle stream is sent to the starch and corn bran separation process. In step 14, the larger particle stream is sent to fiber separation / washing to recover more starch and produce a corn bran feed by-product. Typically, at least 5 countercurrent fiber washing stages are used to wash and recover the starch from the fiber.

[0017] In step 14, the washed fiber is subjected to fiber pre-dehydration treatment, and then mixed with the syrup obtained in step 15 and dried in a dryer to obtain a fiber by-product used as corn bran feed. The starch content of corn bran feed is usually as high as 20%. Even after three milling steps, some starch is still combined with fine fibers and proteins in the horny endosperm.

[0018] Referring now to step 12B, the liquid and fine starch are sent to step 16 for starch / corn bran separation after passing through a 50 micron (μm) screen containing mainly starch / corn bran slurry. Two nozzle centrifuges (primary and clarifier) ​​are connected in series for starch / corn bran separation. The 12 Baume starch slurry contains corn bran obtained from fiber separation and is sent to the primary centrifuge for centrifugal separation. The liquid overflowing from the first 10 millimeter (mm) starch washing cyclone separator is sent to the primary centrifuge for replacement and cleaning. The liquid flowing out of the bottom of the primary centrifuge carries all the heavy solids (starch) to the starch (fiber) washing process.

[0019] In step 16, starch / corn bran separation is performed using a primary centrifuge. The overflow liquid from the primary centrifuge contains light solid corn bran. It is then sent to the corn bran thickener nozzle centrifuge to produce clean overflow process water that can be used for fiber washing, sterilization and soaking. The underflow of the corn bran thickener nozzle centrifuge is sent to a vacuum drum filter to produce a gluten meal cake with about 40% DS (i.e., dry solids). The filtrate from the vacuum drum filter is sent to the corn bran thickener nozzle centrifuge.

[0020] Still referring to step 16, the underflow of the primary centrifuge contains some protein (soluble and insoluble) and some other soluble solids (such as ash in corn, etc.). These proteins and other soluble solids should be removed before using this starch as a feedstock for many green technology processes. A 12-stage countercurrent starch washing process with a 10 millimeter (mm) starch washing cyclone separator screen is used to wash / remove soluble and insoluble proteins and soluble solids (such as ash, etc.).

[0021] The primary centrifuge underflow is mixed with the third stage 10 mm cyclone feed and sent to the first stage (10 mm) cyclone. The overflow of the first stage 10 mm cyclone carries all the removed soluble and insoluble proteins to the starch / corn bran separation process. The first stage 10 mm cyclone underflow is mixed with the third stage 10 mm cyclone to feed the second stage 10 mm cyclone. This continuous countercurrent washes the starch from the first stage to the last stage (12th stage), producing pure starch out of the 12th stage 10 mm cyclone underflow.

[0022] At the same time, wash water enters from the last stage (12th stage) and flows forward, carrying all soluble and insoluble proteins out of the overflow port of the first stage 10 mm cyclone separator.

[0023] like Figure 1 As shown in the process 10 of wet milling, the wet milling process is very complex and requires a very high capital investment. However, this process can produce the maximum yield of each usable product (e.g., protein, starch, germ, etc.) and achieve the maximum purity of all compounds in corn. Similar process steps can be used in some or all embodiments disclosed herein.

[0024] Reference again Figure 7 The corn kernel 700 in the embodiment of the present invention is composed of a shell 706, a powdery endosperm 702, a horny endosperm 704, a germ 708 and a cap 710. Further, the corn kernel 700 contains two kinds of starch. The starch in the powdery endosperm 702 is very loose and can be easily separated. The starch in the horny endosperm 704 is located in the protein cell wall and is not easy to be free and separated. [Summary of the invention]

[0025] In some embodiments, the present invention provides a simpler and less expensive process to obtain starch in powdered endosperm and ensures that the starch has high purity. The remaining starch in the corn kernel can be used as a raw material for alcohol production and produce other valuable by-products such as oil and various animal feeds.

[0026] Figure 2 An improved wet grinding process according to some embodiments is shown. Figure 2The method 20 provides an improved wet milling process, the starch produced by the method can be used as a raw material for a biotechnology process, and the purity of the protein in the starch slurry is less than 0.35%. In some other embodiments, the protein purity of the raw material for the biotechnology process in the starch slurry is less than 1%. In other embodiments, the protein purity of the raw material for the biotechnology process in the starch slurry is between 1-5%. In some embodiments, the protein purity of the raw material for the biotechnology process in the starch slurry is less than 5%.

[0027] Some embodiments are summarized as follows. Figure 2A The process 20A shows a simple low-cost improved wet milling equipment. The corn grits and fiber parts obtained after removing the germ in step 13 of the improved process according to some embodiments are used as raw materials to produce fuel alcohol using the residual starch inside.

[0028] Prior to step 21, this portion of the feedstock contains more than 10% starch. After step 21, the feed stream produced in the process disclosed herein has a high fiber content (more than 30%), compared to the corn kernel portion containing 70% starch and 9% fiber. The high fiber content in the feed stream indicates that most of the starch has been removed for the intended use, such as use as a feedstock for a biotechnology process.

[0029] Further, during the liquefaction process in step 17, the fibers are removed and used as a raw material for fuel alcohol production. Figure 2 An improved wet grinding combined process is shown.

[0030] Initially, the corn kernels are sent to a soaking process in step 11, sent to a grinder for grinding in step 12A, and sent to a germ removal process in step 13, all of which can be used in a typical wet milling process. Figure 2 As shown, an improved three-stage or more paddle screen is used for fiber separation and washing (e.g., starch / corn grits / fiber separation) in step 21. In step 21, a three-stage or more paddle screen is used to separate "free" starch (particles smaller than 50 microns (μm)) from larger particle corn grits and fibers by using a 50 micron (μm) screen in a paddle screen particle separator, wherein a four-stage screen separator is preferred. In step 21, the "free" starch is separated into the filtrate of starch / germ / corn grits / fiber separation and washing, and then a 12-stage starch washing is performed in step 22 to produce a pure starch slurry of 23 degrees Baume with a protein content of less than 0.35%. In step 22, cooking water is used as washing water in starch washing to wash away protein and soluble solids. In step 23, the washing liquid containing protein, soluble solids and a small amount of starch is sent to a clarifier nozzle centrifuge to recover starch and protein.

[0031] In step 23, the overflow with soluble solids flowing out of the clarifier nozzle centrifuge is used as an infusion liquid and sent to the soaking device of step 11. Still in step 23, the bottom flow containing protein and starch flowing out of the clarifier centrifuge is sent to liquefaction and saccharification in step 17, and then sent to fermentation in step 18, and sent to distillation in step 19 to obtain alcohol. In step 19, the whole lees after recovering alcohol from the bottom of the distiller is sent to a liquid / solid separation device (for example, a paddle screen or any screen device can also be used) in step 26 to separate any solid particles (for example, corn grits and germ in the process described herein) from the liquid, wherein the size of the solid particles is smaller than the screen size of the paddle screen. In step 26, the filtrate containing all solid small particle liquid (for example, mainly protein, germ and yeast protein) is sent to a protein dehydrator (decanter) in step 24 to recover protein. The overflow of the decanter in step 24 is used as washing liquid for fiber separation and washing in steps 21 and 27. The wet cake obtained from the decanter treatment in step 24 contains mainly protein and is sent to a protein dryer in step 25 to produce a high-protein animal feed.

[0032] Referring back to step 26, the larger solid particles (e.g., corn grits and germ) obtained from the liquid / solid separation in step 26 are sent to step 12B for fine grinding to further break and release starch and oil protected by protein cell walls. The entire contents of the fine grinding device described in U.S. Pat. No. 9,352,326 are incorporated herein by reference for all purposes. The broken solid particles (e.g., corn grits and germ) finely ground in step 12B are sent to another four-stage (or more) paddle screen in step 27.

[0033] In step 27, a 50 micron (μm) screen is used for the first part (in some cases, a 35-100 micron (μm) screen can be used). A 200 micron (μm) screen can be used for the second, third and fourth parts. In some cases, a 100-500 micron (μm) screen can be used. Still in step 27, the reflux of the overflow of the decanter in step 24 is used as a washing liquid to wash the fine fibers in the germ and corn grits and discharge them from the solid outlet. After step 27, the fiber dehydration treatment of step 28 is carried out. The syrup obtained by the evaporator treatment of step 15 is mixed in the fiber dehydration of step 28. The product in step 28 is sent to a dry distillers grain dryer in step 29 to produce dry distillers grains (DDGS) for cattle feed.

[0034] Still referring to step 27, the filtrate obtained from the second, third and fourth parts of the screen contains medium-sized germ and corn grits particles. These medium-sized germ and corn grits still contain oil and starch inside, so the solid particles between the first and second screens (such as particle sizes between 50 microns (μm) and 200 microns (μm)) can be recycled to the solid-liquid separation device in step 26 to be recaptured and passed through fine grinding for a second time in step 12B, thereby ensuring that all germ and corn grits can be reduced to a minimum size to release starch and oil.

[0035] Still refer to step 27, such as Figure 8 The four-stage paddle screen separation and washing device shown in Figure 1100 of the accompanying drawings is used for liquid / solid separation steps 21 and 26 and washing process step 27. The four-stage paddle screen separation and washing device is described in U.S. application No. 63 / 131,035 filed on December 28, 2020, entitled Screening Device, the entire contents of which are incorporated herein by reference for all purposes.

[0036] In some embodiments, a four-stage paddle screen separation device (such as liquid / solid separation and washing in step 26 or 27) uses a cylindrical container having an upstream inlet for slurry and a downstream outlet for wet cake. The wall of the container is composed of four sections of screen. The first section of the screen has the smallest opening, such as 35 microns (μm). The container is installed in a shell that is configured to collect material passing through each of the four different screen sections. Material that does not pass through the screen is discharged through the outlet. The paddle extends radially from the central axis of the container to the inner surface of the screen and is close to the inner surface of the screen. The paddle rotates and pushes the material onto the screen. The rotating blades also help prevent the screen from clogging. The conduit is arranged along the central axis direction to guide the water flow as a washing water source. The washing water can flow countercurrently in the container relative to the downstream direction. Rake (Figure 1100 of FIG. Figure 8 1115) can assist in moving the material in the downstream direction. Therefore, four or more sections can be used to separate materials of different sizes.

[0037] Referring now to step 13, during the germ separation process, the overflow of the double germ cyclone separator is usually subjected to a number of process steps (not shown) to produce corn oil, such as germ / starch separation, germ washing, germ drying, solvent oil extraction and desolventizing. The germ protein in the germ denatures due to the higher temperatures in the dryer and desolventizing equipment. The germ can be broken down to particles less than 50 microns (μm) by passing through a grinder before fermentation in step 12A and fine grinding in step 12B after fermentation in step 18 to release the oil and produce oil with an oil yield of up to 1.4 pounds per bushel, as described in detail in the next improved process.

[0038] Figure 3Process 30 shows an improved dry milling process with an added pure starch production process according to some embodiments. Figure 3 The process 30 in is similar to Figure 2 The above process 20 differs in whether the germ particles are separated. The moisture content of the corn after soaking is about 50%, dehydrated in step 11, and then sent to a grinder for grinding in step 34. U.S. Patent 9,352,326 describes a fine grinder with a solid ring design, which is used to grind whole corn into very small particles, and then starch / germ / corn grits / fiber separation is performed in step 21. A new four-stage or more paddle screen with a very small screen size (such as 35 microns (μm)) is used. In step 36, the filtrate containing the "free" starch slurry is sent to a pre-concentration cycle.

[0039] In step 36, the pre-concentrated overflow obtained in step 36 is recycled back to dilute the grinding slurry of the mill obtained in step 34. The pre-concentrated underflow obtained in step 36 will be sent to the 12-stage countercurrent starch washing system in step 22. The cooking water used as fresh washing water is fed to the last stage of the 10 mm cyclone separator screen to wash out the protein and soluble solids, and then the underflow of the last stage of the 10 mm cyclone separator screen is used to produce a pure starch slurry of 23 degrees Baume with a protein content of less than 0.35%. In step 23, the washed protein stream containing a small amount of starch is sent to the clarifier nozzle centrifuge. In step 23, the overflow of the clarifier with soluble solids is sent to the steeping tank in step 11 and used as a steeping liquid for soaking corn kernels.

[0040] In step 31, the clarifier underflow from step 23 (containing starch and protein) is mixed with the wet cake from step 32 (containing primarily germ, corn grits, and fiber) and then sent to a slurry tank in step 31 to cook and liquefy the "bound" starch to release some of the corn oil in the germ.

[0041] In step 31, the liquefied starch slurry obtained from the slurry tank treatment is sent to the fiber separation / washing unit in step 32 to separate and wash larger size fibers (such as husks and top caps). The slurry is discharged as a wet cake and then sent to step 28 for dewatering. Next, the fiber is mixed with the deoiled syrup after deoiling in step 33 and enters the Dried Distillers Grains (DDGS) dryer in step 29 to produce rich (such as high lactic acid) Dried Distillers Grains (DDGS) for use as cattle feed. The selection of a three-stage or four-stage high-speed drainage wash paddle screen with a screen size of 100 microns (μm) to 1 millimeter (mm) depends on the desired fiber purity and yield and the oil yield of the previous step.

[0042] A portion of the reflux is used as a wash liquid to wash off liquefied starch, protein and oil in step 32. Still in step 32, the filtrate (containing mainly liquefied starch and some small germ particles from the fiber washing in step 32) is sent to a fermentation process in step 18 to produce alcohol and then distilled in step 19 to recover alcohol and whole stillage for by-product production.

[0043] The whole grains obtained from the distillation in step 19 are sent to a solid-liquid separation device in step 26 to separate corn grits and germs, and then sent to a fine grinder with a solid ring design in step 35, as described in U.S. Pat. No. 9,352,326, to break all germs and corn grits to as small as possible (e.g., less than 50 microns (μm)) to release bound starch and oil. The paddle screen (four-stage high-speed displacement washing) in step 27 is used to separate / wash fine fibers, which are discharged in the form of wet filter cakes, and then fiber dehydration is carried out in step 28. The fibers in step 28 are mixed with the syrup in step 33 and dried in a dried distiller's grains (DDGS) dryer in step 29 to produce dried distiller's grains (DDGS) for use as cattle feed.

[0044] Referring to step 26, the solid-liquid separation filtrate in step 26 mainly contains high-value proteins (corn protein, germ protein and yeast protein). In step 24, these materials are sent to a protein dehydration decanter to recover protein (mainly corn protein, which contains some germ protein and a small amount of yeast protein). After step 24, a protein dryer is used in step 25 to produce gluten meal containing 60% protein for chicken feed. When a typical whole grains decanter is used, Figure 3 In process 30, yeast protein and some corn oil may be more difficult to recover. Figure 4 The following processes in 40 oil / protein separation nozzle centrifuges were added.

[0045] Figure 4 Process 40 illustrates pure starch production and alcohol production, as well as production of high-value byproducts, according to some embodiments. This process is similar to the above Figure 3 The process is similar to process 30 in step 41, but with the addition of an oil / protein separation step in step 41, the addition of yeast / germ protein dehydration in step 42 to produce high value yeast / germ protein meal, and the addition of yeast / germ protein drying in step 43 to produce high value yeast / germ protein for pet and aquafeed.

[0046] In step 24, the overflow from the zein dehydration obtained in step 24 is used as Figure 3The backwash in process 30 is sent to the oil / protein separation (e.g., using a high-speed nozzle centrifuge) in step 41 to break the oil / protein emulsion and separate / recover the light phase oil from the three-phase nozzle centrifuge. In step 41, the heavy phase from the nozzle centrifuge is used as the washing liquid for fiber washing in steps 21 and 27. The underflow from the nozzle centrifuge in step 41 is sent to a protein dehydration unit in step 42 to produce a protein wet cake, and then sent to a protein dryer in step 43 to produce yeast / germ protein meal for household pet and aquaculture feed.

[0047] Figure 5 Process 50 shows the production of indigestible starch and alcohol with maximum by-product value for green technology and alcohol production according to some embodiments, with minimal capital and operating costs and energy input. In step 11, lactic acid probiotic cultures, such as Lactobacillus plantarum ZJ316, Lactobacillus amylovora, Lactobacillus fermentans, and Lactobacillus mucosa, are added to the soaking and dehydration steps of step 11 to propagate CSU probiotic units and produce up to 5% DB lactic acid in the soaked liquid. After evaporation in step 15, this probiotic-rich soaked liquid or its concentrated syrup can be used as part of an animal drinking water formula or an infant animal milk formula. In steps 51 and 52, this enriched probiotic syrup can be used as a binder to form enriched probiotic pellets / bucketed animal feed for household pets, aquaculture feed, and chicken feed.

[0048] According to some embodiments, there is provided Figure 6 The continuous dipping tank design and Figure 8 A four-stage high-speed drainage washing paddle screen is shown in Figure 1100.

Brief Description of the Drawings

[0049] Figure 1 A typical wet grinding process is shown.

[0050] Figure 2 An improved wet milling process for producing alcohol is shown according to some embodiments.

[0051] Figure 2A Another improved wet milling process for producing alcohol is shown according to some embodiments.

[0052] Figure 3 An improved dry milling process for producing pure starch according to some embodiments is shown.

[0053] Figure 4 Processes for producing pure starch and alcohol as well as high-value byproducts according to some embodiments are shown.

[0054] Figure 5A process for producing pure starch and alcohol with maximum byproduct value with minimal capital cost, operating cost, and low energy input is shown according to some embodiments.

[0055] Figure 6 A continuous dip tank design according to some embodiments is shown.

[0056] Figure 7 Corn kernels are shown.

[0057] Figure 8 Included is a drawing 1100 showing a cross-sectional view of a four section high velocity drain wash paddle screen according to some embodiments. [Specific implementation method]

[0058] Embodiments of the present invention will be described in detail below, examples of which are shown in the accompanying drawings. Although the present invention is described below in conjunction with embodiments, it should be understood that the present invention is not limited to these embodiments and examples. On the contrary, the present invention is intended to cover alternatives, modifications and equivalents, which can be included in the spirit and scope of the present invention as defined by the appended claims. In addition, in the following detailed description of the present invention, many specific details are set forth in order to more fully illustrate the present invention. However, it is obvious to those of ordinary skill in the art who have the benefit of the present application that the present invention can be implemented without these specific details. In other examples, well-known methods and procedures, components and processes are not described in detail to avoid unnecessarily obscuring various aspects of the present invention. Of course, it is understood that in the development of any such actual implementation, many implementation-specific decisions must be made to achieve the specific goals of the developer, such as complying with application and business-related constraints, and these specific goals vary from implementation to implementation and from developer to developer. In addition, it should be recognized that such development work may be complex and time-consuming, but it is still a routine engineering work for those of ordinary skill in the art who have the benefit of the content of the present application.

[0059] Figure 7 Yellow dent corn kernels are shown, and their composition is shown in Table 1. There are 34.4 pounds of starch in each bushel of corn. The starch is mainly found in two types of endosperm: powdery endosperm and horny endosperm. The starch in powdery endosperm is loosely packed in the endosperm and can be easily separated out. This starch can be used to produce pure starch for use as a feedstock for green technology processes. The starch in horny endosperm is contained in cells filled with granular starch in a protein matrix, and the starch bound to the protein is not easily separated out to produce starch.

[0060] The typical wet milling process is to steep the corn in 5-7 batches of steeping tanks for 40-60 hours, followed by two to three grinding steps to separate / produce germ and 23 degrees Baume pure starch slurry, with a starch yield of 75%-95% in the corn, while producing corn bran feed (fiber feed) and gluten meal (high protein feed) as by-products. The typical dry milling process converts all the starch in the corn into alcohol, recovers as much corn oil as possible from the corn, and produces high-value by-products for use as animal feed. The alcohol yield is 2.8-2.9 gallons / bushel, the oil yield is 0.4-0.9 pounds / bushel, and the dry distillers grains (DDGS) yield is about 14 pounds / bushel, which contains about 5% bound starch. In a typical dry milling process, about 98% of the starch in the corn is converted to alcohol.

[0061] In some embodiments, a process combining wet milling and dry milling with the use of a novel grinding device and a high-speed displacement washing paddle screen removes about 60% to 80% of the starch from the corn and produces a pure starch slurry of 23 degrees Baume containing 0.35% to 0.5% protein. The process can also recover a maximum oil yield of up to 1.4 pounds per bushel and produce a high-value, high-protein animal feed.

[0062] In some embodiments, the process provides an optimized process / system to obtain the appropriate amount of "free" starch (the purest starch obtained from the powdered endosperm) and all the remaining corn compounds (pericarp, cap, fine fiber, corn protein, germ and corn grits) in combination as a feedstock for an optimized dry milling process / system that produces the maximum alcohol yield and the most valuable by-products, including corn oil for human consumption in the front-end process (i.e., before fermentation), corn oil for biodiesel in the back-end process (i.e., after fermentation), and animal feed for cattle, chickens, pigs, fish, and domestic pets, etc.

[0063] In some embodiments, the process utilizes a simple, low-cost modified wet milling process to separate about 60%-85% of the starch in corn (i.e., 20-29 pounds per bushel of "free" starch from the powdery endosperm). In the process, the remaining starch in the corn is used as a feedstock to produce ethanol and higher value-added byproducts using a modified dry milling process.

[0064] In some embodiments, corn kernels are soaked in continuous steeping tanks for 2-40 hours (depending on the quality and quantity of pure starch required for the green technology process). Next, the corn grits and germ particles are ground in a predetermined grinder to particles less than 50 microns (μm) in size to release starch and oil, and then the fibers (peels, top caps, and fine fibers within the corn grits and germ) are separated / washed using a high-speed displacement washing paddle screen to produce a high-value protein meal (including corn protein, germ protein, and yeast protein) with 60% protein for chicken, water, and household pets.

[0065] The corn kernels are soaked / infused until the soaked corn kernels contain about 50% moisture, and the soaked corn kernels in step 34 ( Figure 3-5 ) becomes soft and easily broken in a grinding mill. Compared to the energy used in a typical dry grinding process, according to some embodiments, only 40% of the energy is used in the grinding step of the present disclosure.

[0066] In some embodiments, the process provides a most efficient way to first separate the "free" starch from the powdery endosperm and then use the remaining corn as a feedstock for the production of ethanol and high-value co-products using an improved dry milling process.

[0067] Figure 2 Process 20 illustrates an improved wet milling process for producing alcohol according to some embodiments.

[0068] In step 11, five to seven batch steeping tanks are used. In step 23, the overflow from the clarifier nozzle centrifuge can be used as the steeping liquid. The corn is soaked in a sulfur dioxide solution of about 200 PPM for 50-60 hours to soften the corn kernels. The corn is soaked until the water is completely absorbed to about 50% dry solids (DS). In step 15, the excess steeping liquid is sent to an evaporator to produce a syrup containing all soluble solids in the corn.

[0069] Still referring to step 11, in step 12A, the dehydrated steeped corn kernels are fed into a grinder to grind the whole corn kernels to form a starch slurry of about 12 degrees Baume containing germ, corn grits and fiber solids. In step 12A, the mixed slurry is fed to a double germ cyclone separator (at the germ separation) in step 13.

[0070] In step 13, the germ particles are lighter than the corn grits and fiber, so the germ floats to the top, which is the first germ cycle overflow, followed by a dewatering / washing step (not shown) to remove the starch and obtain dry germ for oil extraction, which can produce corn oil for human consumption (not shown).

[0071] Still referring to step 13, the 12 degree Baume starch slurry containing corn grits and fiber particles is separated from the second stage germ cyclone separator in the form of underflow. Then, in step 21, the underflow is sent to a four-stage paddle screen with a high-speed displacement washing design (paddle screen device such as Figure 8 1100 of the accompanying drawings). The mesh sizes of the four parts vary depending on the process requirements. For example, in some embodiments, the mesh size of the first mesh section is 50 microns (μm), which can also be in the range of 35-200 microns (μm), while the mesh sizes of the second, third and fourth mesh sections can be 300 microns (μm) or in the range of 200-1,000 microns (μm).

[0072] In step 21, the 12 Baume starch slurry obtained from the first stage screen is sent as filtrate to the 12-stage 10 mm starch countercurrent washing cyclone separator screen system in step 22 to wash and remove insoluble and soluble proteins and soluble solids (ash) in corn and produce 23 Baume pure starch slurry for the next green technology process. Fresh water is used as washing water, which is mixed with the starch slurry from the bottom flow of the 11th stage 10 mm cyclone separator screen and used as feed for the 12th stage cyclone separator screen (not shown). The 12-stage countercurrent washing in step 22 is used to perform countercurrent washing by the starch slurry flowing downwardly and forwardly from the 1st stage to the 12th stage, and the washing water flowing upwardly and forwardly from the 12th stage to the 1st stage. The fresh water carries all the protein and soluble solids and a small amount of starch, which comes out as the overflow of the first stage 10 mm cyclone separator. In step 23, this overflow is fed to the clarifier nozzle centrifuge to remove all the insoluble solids (protein and starch) which become underflow and produce a clean overflow with only soluble solids as the steep liquor for soaking / steeping the corn in step 11. The underflow from the clarifier in step 23 with a small amount of starch in the clarifier is mixed with the filtrate (containing germ and corn grit particles) from the 2nd, 3rd and 4th stage paddle screens in step 21 which is fed to liquefaction and saccharification to liquefy the starch in step 17. From step 17, the contents are sent to the fermentation tank in step 18 and distilled in step 19 to produce and recover alcohol.

[0073] In step 21, the overflow from the dehydration of zein in step 24 is used as a reflux, which is used as a wash liquid to separate medium-sized germ / corn grits particles from larger-sized fibers (peel and top cap) in the starch / germ / corn grits / fiber separation in step 21. The larger fibers are retained on the screen and exit from the solid phase outlet at the end of the paddle screen in the form of a wet cake in step 21, and then undergo fiber dehydration treatment in step 28. In step 29, the fibers obtained from step 28 are then mixed with the syrup obtained from the evaporator in step 15, and the syrup is sent to a distillers dried grains (DDGS) dryer in step 29 to produce distillers dried grains (DDGS) animal feed for cattle.

[0074] In step 19, the whole grains obtained by distillation in step 19 are sent to step 26 for liquid-solid separation. In step 26, fine protein is separated from fine fiber and germ / corn grits using a three- or four-stage paddle screen with a screen size of 50 μm (or a screen with a size of 35 μm to 100 μm).

[0075] In step 26, the filtrate containing fine protein is sent to the protein dehydration device of step 24 to produce a protein cake (the main component is corn protein), and then a gluten meal containing 60% protein is produced using a protein dryer in step 25 to make chicken feed. In step 24, the overflow of the protein dehydration in step 24 is used as a reflux and as a washing liquid in the fiber separation / washing of steps 21 and 27. Germs and corn grits larger than the screen size are retained on the screen and discharged from the solid outlet at the end of the paddle screen as a wet cake.

[0076] On the other hand, in step 26, the wet cake containing fine fibers, germs and corn grits is sent to the fine grinding step in step 12B to break it into particles as small as possible to release starch and oil. After step 12B, the process is followed by fine fiber separation and washing paddle screen in step 27 to separate fine fibers from fine corn and germ proteins by size difference. The fine fibers are discharged from the solid phase discharge port as a wet cake and mixed with the coarse fibers (peels and peaked caps) in step 21. The mixture obtained in step 27 and step 21 is sent to step 28 for fiber dehydration and dried in a DDGS dryer in step 29 to produce DDGS for cattle feed. In step 27, medium-sized germs and corn grits come out of the 2nd, 3rd and 4th sections of the mesh paddle screen in step 27 together with the washing liquid as filtrate, and are recycled back to the whole grain feed tank in step 12B again to be finely ground using a grinder.

[0077] Figure 2AProcess 20A further uses a fine germ grinding device (such as Supraton) to break up the germ particles in step 12C to release the oil and recover the corn oil during the de-oiling process in step 20.

[0078] Figure 3 Process 30 shows an improved dry milling process for producing pure starch according to some embodiments. Figure 6 A corn steeping process in a continuous steeping tank is shown according to some embodiments. Figure 3 and Figure 6 Can be read together. The continuous steeping tank has a large tank whose height is close to the size of its diameter. The continuous steeping tank is divided into about 10-16 chambers. Each chamber has a paddle connected to a central shaft that rotates at a very low speed (2-20 rpm) using a variable speed motor. In some embodiments, there are two paddle designs. One design is shown in 6A, which is a paddle design for moving corn kernels inward in the chamber. The other design is shown in 6B, which is a paddle design for moving corn kernels outward in the chamber.

[0079] The first chamber at the top starts with a paddle design that conveys the corn kernels outward using the design in 6A, followed by a design in 6B in the next chamber where the corn kernels are conveyed inward. These two paddle designs are used continuously from the top of the tank to the bottom of the tank in an alternating arrangement. The bottommost chamber will use a paddle design that conveys the corn kernels inward using the design in 6B (for example, a design pattern with 6A can be used from the top chamber to the bottom chamber, 6A for the first chamber, 6B for the second chamber, 6A for the third chamber, 6B for the fourth chamber, 6A for the fifth chamber, and 6B for the sixth chamber or the bottom chamber), so that by using a conveyor at the top of the continuous steeping tank, the corn kernels can be continuously fed into the continuous steeping tank and discharged uniformly (all the corn kernels have the same soaking time, which soaks from the bottom of the continuous steeping tank to the dewatering device before the corn kernels are fed to the grinder in step 34). In step 23, the steeping liquid overflowing from the clarifier in step 11 is sent to the bottom of the continuous steeping tank and comes out from the top of the continuous steeping tank. In step 15, the steeped liquid is sent to the evaporator to evaporate the water to form a syrup. A portion of the steeped liquid is sent to the heat exchanger to maintain the temperature just below the starch gel point (about 115°F), and the steeped liquid is recirculated to achieve the optimal steeping temperature (about 11-115°F) for the incoming corn.

[0080] Corn kernels are output from the storage bin by a conveyor system. Corn kernels are continuously fed to the top of the continuous impregnation tank and uniformly conveyed downward through each chamber by the movement of the paddle driven by a variable speed motor on the top. The impregnation time (2-40 hours) is adjusted by using a variable speed motor. The shorter the impregnation time, the lower the starch purity and the lower the alcohol yield, while the longer the impregnation time, the higher the starch purity and the higher the alcohol yield. The soluble solids in the impregnated liquid (optimum amount is 3-4 weight % of the ash content) enter the evaporator from the top of the continuous impregnation tank for the process of step 15. The impregnated corn kernels flowing out of the bottom of the continuous impregnation tank maintain a moisture content of 45%-50%. The impregnation time is set to 2-40 hours. The longer the impregnation time, the higher the moisture content of the impregnated corn kernels, and the higher the yield and purity of starch as a raw material for the green technology process.

[0081] Next, the infusion is sent to an evaporator for processing in step 15 to pre-concentrate the liquid to about 50% dry solids (DS), and then the liquid is sent for de-oiling (i.e., using a three-phase decanter) in step 33 to recover the oil and remove any fine solids. Next, a vacuum evaporator is used to further concentrate the liquid to form a syrup of maximum concentration (85% dry solids (DS)), which can bypass / bypass the dryer in step 29 and produce highly nutrient-enriched probiotic dried distillers grains (DDGS).

[0082] The overflow from the clarifier in step 23 is used as the steeping liquid, which is fed to the bottom of the continuous steeping tank. The amount of steeping liquid is sufficient to keep the soluble solids percentage (ash content) at the steeping liquid outlet below the maximum soluble solids percentage (approximately 5.6% ash content). In step 15, the steeping liquid flowing out of the top of the continuous steeping tank is fed to the evaporator. The feed tank of the evaporator has a waste heat recovery system that uses the waste heat condensed by the evaporator to heat the incoming corn kernels and maintain the optimum steeping temperature (i.e., 100-115°F) by recycling the steeping liquid between the feed tank and the top chamber of the steeping tank.

[0083] In step 34, the soaked corn kernels with about 50%-60% dry solids (DS) flowing out from the bottom of the continuous steeping tank after dehydration are fed to a grinder with a solid ring design to release "free" starch from the endosperm and grind the germ and corn grits to particles of about 200-400 microns (μm). In step 21, the ground corn slurry from the grinder in step 34 is fed to four sections of high-speed washing paddle screens, using a 50 micron (μm) (or 35-75 micron (μm)) screen in the first section of the screen, and a 300 micron (μm) (or 200 micron (μm)-1 millimeter (mm)) screen in the second, third and fourth sections of the screen. The filtrate from the first section of the screen contains mainly "free" starch (about 12 degrees Baume starch slurry), with some protein, which is sent to a pre-concentration process in step 36 and concentrated to 23 degrees Baume before being sent to the starch washing 10 mm (mm) cyclone separator screen system in step 22. In step 21, the overflow from the pre-concentration or recycling is mixed with the ground corn to form a slurry, which enters the starch / germ / corn grits / fiber separation paddle screen. The wet cake from the starch / germ / corn grits / fiber separation in step 21 and the underflow from the clarifier nozzle centrifuge in step 23 are mixed with the first filtrate from the fiber washing in step 32, which is sent to the slurry tank to liquefy the starch in step 31, and then the fiber is separated / washed using the fiber washing paddle screen in step 32 and discharged as a wet cake. The reflux (i.e., countercurrent) is used as a washing liquid. In step 32, the first filtrate containing liquefied starch flowing out of the first stage screen is sent to step 18 for fermentation to produce alcohol and the alcohol is recovered by distillation in step 19.

[0084] In step 19, the whole grains flowing out of the bottom of the distiller are sent to the solid-liquid separation paddle screen in step 26. In step 26, the filtrate containing protein is sent to the protein dehydrator in step 24 to obtain a protein wet cake. In step 24, the process then uses a protein dryer in step 25 to produce a high-value protein product with 60% protein. Still referring to step 26, the wet cake containing germ and corn grits particles flowing out of the liquid / solid separation paddle screen in step 26 is sent to a fine grinder in step 35 to break the particles to release starch and oil. In step 27, the broken germ and corn grits particles are sent to the fine fiber separation and washing paddle screen. The reflux liquid is used as a washing liquid, and the fine fiber wet cake is sent to step 28 for fiber dehydration, and then a dried distiller's grains (DDGS) dryer is used in step 29 to produce dried distiller's grains (DDGS) for cattle feed. The medium-sized germ and corn grit particles can optionally be recycled back and passed through a fine grinder once more in step 35 to further break up the particles. When a whole grains decanter is used in protein dewatering in step 24, a low gravity decanter recovers only corn protein and some germ protein. Therefore, a high-speed nozzle centrifuge is used to recover yeast protein.

[0085] Figure 4 Process 40 illustrates a combination of a wet milling process and a dry milling process for producing high value by-products according to some embodiments.

[0086] Add the oil / protein separation of step 41, the yeast / germ protein dehydration of step 42, and the yeast / germ protein dryer of step 43 to Figure 3 In the process 30, to form Figure 4 The process 40. For the sake of brevity, similar process steps mentioned above will not be repeated below. The overflow of corn dehydration obtained in step 24 contains yeast and germ proteins, which contain corn oil, which is sent to a high-speed three-phase nozzle centrifuge (with a force greater than 5000G) to break the oil / protein emulsion. Corn oil containing some emulsions and liquids flows out as a light phase, while clean thin distiller's grains flows out as a heavy phase. The bottom flow flowing out of the nozzle mainly contains yeast protein and germ protein, accounting for about 10%-30% of the volume of the rotating solids. The corn oil flow is sent to a continuous impregnation tank as a light phase for the deoiling process in step 33 to recover oil. The thin distiller's grains discharge flowing out as a heavy phase is discharged from the oil / protein separation in step 41, which is used as reflux washing water for washing fibers in the fiber separation and washing steps of steps 27 and 32. In step 28, the mixed fiber (peel tops and fine fibers) is sent to a fiber dewatering unit and then in step 29, it is mixed with de-oiled syrup and dried in a DDGS dryer to produce DDGS for cattle feed.

[0087] In step 41, the underflow of the oil / protein separation obtained in step 41 containing about 30% of the rotating solid volume of yeast / germ protein is sent to step 42 for yeast / germ protein dehydration. In step 42, a high-speed decanter is usually used for the yeast / germ protein dehydration.

[0088] Still in step 42, a wet cake containing about 25% dry solids (DS) protein cake is obtained by protein dehydration. This high moisture wet cake should be dried using a high cost ring dryer to obtain a high value yeast / germ protein meal containing 60% protein for use as a household pet and aquaculture feed. The two portions of dry corn protein dried by the corn protein dryer in step 25 are mixed with one portion of the wet cake dehydrated by yeast / germ protein in step 42 to form a semi-dried cake containing about 50% dry solids (DS). This semi-dried cake containing about 50% dry solids (DS) can be dried in a typical rotary dryer, avoiding the costly ring dryer and producing an acceptable high value yeast / germ / corn protein feed.

[0089] Figure 5 Process 50 illustrates a combined wet and dry milling process for producing maximum value by-products according to some embodiments.

[0090] The soaking and dehydration process in step 11 is further improved by adding lactic acid-producing probiotic cultures such as Lactobacillus plantarum ZJ316, Lactobacillus amylovora, Lactobacillus fermentum and Lactobacillus mucosa to step 11. These cultures convert sugars into lactic acid with a lactic acid content of up to 20% in dry solids (DS). After deoiling in step 33, the deoiled syrup contains 10 ^ 9CSU probiotic units. This probiotic-rich syrup can be used in animal drinking water formula or infant animal milk formula. Figure 5 This probiotic-rich syrup can also be used as a binder in animal pellet / chunk formation as shown in the process 50. The present invention provides a pellet / chunk formation for producing enriched probiotic high protein meal (corn protein, yeast protein and germ protein) in steps 51 and 52.

[0091] Although corn kernels are disclosed as an example, the process and apparatus described herein can also be used for other types of grains, such as rice, wheat, sorghum, etc. Therefore, other grains are also included within the scope of the present invention.

[0092] In application, the process disclosed herein can be used to produce pure starch of a quality suitable as a feedstock for new green technology processes.

Claims

1. A wet milling process for producing purified starch slurry, characterized in that: The following steps are involved: a. Soak corn kernels; b. grinding the corn kernels to produce a corn component, the corn component comprising starch primarily from the powdered endosperm of the corn kernels, germ, corn grits, and fiber, wherein the starch is present in the corn component in an amount greater than 10%; c. performing germ separation to remove the germ from the first portion containing the starch, the corn grits and the fiber; as well as d. separating the starch from the first portion to produce a starch component and a second portion, wherein the fiber content of the second portion is greater than 30%.

2. The wet milling process for producing purified starch slurry according to claim 1, characterized in that: The starch component is the filtrate from three or more stages of paddle screens.

3. The wet milling process for producing purified starch slurry according to claim 2, characterized in that: The three or more sections of paddle screen use a particle separator with a 50 micron screen to separate the starch from the corn grits and the fiber.

4. The wet milling process for producing purified starch slurry according to claim 3, characterized in that: The separated starch is 60%-85% of the starch content in the corn kernels before grinding.

5. The wet milling process for producing purified starch slurry according to claim 1, characterized in that: The method further comprises performing 12 stages of starch washing to produce a pure starch slurry at 23 degrees Baume containing less than 0.5% protein.

6. The wet milling process for producing purified starch slurry according to claim 5, characterized in that: The method further comprises sending the wash liquor containing protein and soluble solids to a clarifier nozzle centrifuge.

7. The wet milling process for producing purified starch slurry according to claim 6, characterized in that: Further comprising combining an underflow portion of the clarifier nozzle centrifuge with the second portion to be liquefied and saccharified.

8. The wet milling process for producing purified starch slurry according to claim 7, characterized in that: This further includes fermentation.

9. The wet milling process for producing purified starch slurry according to claim 8, characterized in that: This further includes distillation to produce alcohol.

10. The wet milling process for producing purified starch slurry according to claim 9, characterized in that: The method further comprises sending the whole grains after distillation to liquid and solid separation, wherein the liquid and solid separation uses a second three-stage or more-stage paddle screen to separate protein from fiber and germ / corn grits particles.

11. The wet milling process for producing purified starch slurry according to claim 10, characterized in that: This further includes fine grinding.

12. The wet milling process for producing purified starch slurry according to claim 1, characterized in that: The method further comprises finely grinding the germ using a Supraton to break up the germ particles to release corn oil.

13. The wet milling process for producing purified starch slurry according to claim 12, characterized in that Further comprising recovering the corn oil.

14. The wet milling process for producing purified starch slurry according to claim 1, characterized in that: Further comprising evaporating the corn kernels after steeping the corn kernels.

15. The wet milling process for producing purified starch slurry according to claim 14, characterized in that The method further comprises sending the evaporated material to a dryer.

16. The wet milling process for producing purified starch slurry according to claim 14, characterized in that This further includes forming distillers dried grains for use as cattle feed.

17. A dry grinding process for producing purified starch slurry, characterized in that: The following steps are involved: a. Soak corn kernels; b. grinding the corn kernels using a grinder to generate a corn component comprising starch, germ, corn grits, and fiber primarily from the powdered endosperm of the corn kernels; as well as c. separating the starch from the first portion to produce a starch portion and a first portion.

18. The dry grinding process for producing purified starch slurry according to claim 17, characterized in that: The method further comprises sending the starch portion to a pre-concentrator.

19. The dry grinding process for producing purified starch slurry according to claim 18, characterized in that: The method further comprises recycling the overflow of the pre-concentrator to dilute the material in the grinding mill.

20. The dry grinding process for producing purified starch slurry according to claim 18, characterized in that: The method further comprises sending the bottom flow of the pre-concentrator to a 12-stage countercurrent starch washing system.

21. The dry grinding process for producing purified starch slurry according to claim 20, characterized in that: It further includes using the cooking water as fresh wash water to wash out the protein and soluble solids from the filter.

22. The dry grinding process for producing a purified starch slurry according to claim 21, characterized in that: Further included is using the underflow of the 12-stage countercurrent starch washing system to produce a pure starch slurry of 23 degrees Baume containing less than 0.35% protein.

23. The dry grinding process for producing purified starch slurry according to claim 17, characterized in that: Further comprising combining a first portion from the four or more paddle screens with an underflow from a clarifier to be sent to a slurry tank to cook and liquefy the bound starch and release the corn oil within the germ.

24. The dry grinding process for producing a purified starch slurry according to claim 23, characterized in that: Further included are fiber washing, fermentation, distillation and liquid / solid separation at the output of the slurry tank, which produces high-value proteins including corn protein, germ protein and yeast protein.

25. The dry grinding process for producing a purified starch slurry according to claim 24, characterized in that The method further comprises dehydrating the protein using a protein dehydration decanter.

26. The dry grinding process for producing a purified starch slurry according to claim 25, characterized in that This further includes drying the protein using a protein dryer to produce gluten meal containing 60% protein for use as chicken feed.

27. The dry grinding process for producing a purified starch slurry according to claim 25, characterized in that: The method further comprises sending the overflow of the protein dehydration decanter to oil / protein separation using a nozzle centrifuge to grind the oil / protein emulsion and separate / recover the oil.

28. The dry grinding process for producing a purified starch slurry according to claim 27, characterized in that: The method further comprises sending the bottom flow from the nozzle centrifuge to the protein dehydration decanter to obtain a protein wet cake.

29. The dry grinding process for producing a purified starch slurry according to claim 28, characterized in that The method further comprises drying the protein wet cake to produce yeast protein / germ protein for household pet and aquaculture feed.

30. The dry grinding process for producing a purified starch slurry according to claim 17, characterized in that: The method further comprises adding a lactic acid probiotic culture to the steeped corn kernels to multiply the probiotic units and produce up to 5% lactic acid in the steeped liquid.

31. The dry grinding process for producing a purified starch slurry according to claim 30, characterized in that: The method further comprises concentrating and evaporating the impregnated liquid to form a binder for preparing probiotic-enriched granules / chunks for animal feed.

32. The dry grinding process for producing a purified starch slurry according to claim 17, characterized in that: The soaked corn kernels contain about 50% moisture.

33. The dry grinding process for producing a purified starch slurry according to claim 17, characterized in that: The screen size of four or more blades does not exceed 35 microns.

34. The dry grinding process for producing a purified starch slurry according to claim 17, characterized in that: The starch is separated by using a four-stage or more-stage paddle screen.

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