FORM 2
THE PATENT ACT, 1970
(39 OF 1970)
AND PATENT RULES; 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
SYSTEM AND METHOD FOR PROCESSING A STARCH-BASED
MATERIAL
Praj Industries Limited
A company incorporated under the Indian Company Act 1956
Having address, Praj House, Bavdhan, Pune 411021, Maharashtra,
India
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The invention relates generally to processing of starch-based materials, and particularly to a technique for separating suspended matter from a starch-based material.
BACKGROUND
A variety of starch-based materials such as broken rice, corn, millets, cassava chips, tubers, oats etc. are subjected to liquefaction and fermentation to produce various products through known bioprocesses. Such products include alcohols such as beverage grade and fuel grade ethanol, high fructose / glucose syrups and it's derivatives, organic acids and bio oils, among others. Alcohols are employed as a solvent for a wide range of industrial products such as paints, lacquers, dyes and oils.
As a example, cassava flour is utilized for alcohol production due to its high starch content resulting in high fermentable sugars and a stable shelf life. Typically, the raw material (cassava chips or tubers) may include suspended matter such as sand, fiber/filler material and peels that cause erosion of the process equipment such as stationary and rotary components, piping, fittings and other instrumentation used in the pretreatment and fermentation, distillation and solid-liquid separator plants. It is therefore desirable to separate and remove such suspended matter from the starch-based materials to improve the process efficiency and durability of the plants.
One way of separating the suspended matter from the starch-based material is through duplex strainers. Typically, a duplex strainer includes two filtration chambers for filtering the starch-based material. However, the strainers employed in the system are required to be replaced manually once they are blocked. Moreover, these strainers have substantially low sand separation efficiency and also result in loss of starch along with sand and fibers.
Another way of separating the suspended matter is through gravity settling tanks, where trough or settling tanks are employed to separate sand and other suspended matter from the starch-based material. Unfortunately, only heavy sand is

settled and separated through this technique and other suspended matters such as peels are not separated. Again, such systems also result in loss of starch along with the sand.
Some systems utilize hydrocyclone / decantation separators that separate sand and other suspended matter based upon density variations. However, such systems again have erosion issues and are susceptible to loss of starch along with sand separation.
Accordingly, it would be desirable to develop an efficient method of separating suspended matter from starch-based materials.
BRIEF DESCRIPTION
Briefly, according to one embodiment of the present invention, a method for processing a starch-based materia! is provided. The method includes liquefying the starch-based material in presence of a liquefaction enzyme to form a slurry and screening the slurry via one or more vibratory screening devices to form a first filtrate stream and a first filtration residue. The method includes mixing the first filtration residue with water to form an intermediate slurry and screening the intermediate slurry via one or more vibratory screening devices to form a second filtrate stream and a second filtration residue. The method also includes forming a fresh slurry using the second filtrate stream and optionally a portion of the first filtrate stream. The method further includes sterilizing and cooling the first and second filtrate streams and fermenting the cooled streams to form a fermentation product.
In accordance with another aspect, a system for processing a starch-based material is provided. The system includes a liquefaction unit to liquefy the starch-based material to a form a slurry and a first set of vibratory screening devices to screen the slurry for separating suspended matter from the slurry and generate a first filtrate stream and a'first filtration residue. The system also includes a slurry tank to mix the first filtration residue with water to form an intermediate slurry and a second set of vibratory screening devices to screen the intermediate slurry for separating residual suspended matter and generate a second filtrate stream and a second filtration residue.

In accordance with another aspect, a system for processing a starch-based material is provided. The system includes a liquefaction unit to liquefy the starch-based material to a form a slurry and a first set of vibratory screening devices to screen the slurry for separating suspended matter from the slurry and generate a first filtrate stream and a first filtration residue. The system includes a slurry tank to mix the first filtration residue with water to form intermediate slurry and a second set of vibratory screening devices to screen the intermediate slurry for separating residual suspended matter and generate a second filtrate stream and a second filtration residue. The system also includes a sterilization unit to sterilize the first and second filtrate streams and to form a fresh slurry using the second filtrate stream and optionally a portion of the first filtrate stream and a fermentation unit for fermenting the fresh slurry to form a fermentation product.
DRAWINGS
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
FIG. 1 illustrates an exemplary method for processing a starch-based material in accordance with aspects of the present invention;
FIG. 2 illustrates a system for processing a starch-based material in accordance with aspects of the present invention;
FIG. 3 is a table illustrating exemplary composition of the starch-based material such as cassava chips utilized by system of FIG. 2 for producing ethanol;
FIG. 4 is a table illustrating exemplary composition of the slurry provided to the first set of vibratory devices of FIG. 2;
FIG. 5 is a table illustrating exemplary composition of the first filtrate stream from the first set of vibratory devices of FIG. 2;

FIG. 6 is a table illustrating exemplary composition of the first filtration residue from the first set of vibratory devices of FIG. 2;
FIG. 7 is a table illustrating exemplary composition of the second filtrate stream from the second set of vibratory devices of FIG. 2; and
FIG. 8 is a table illustrating exemplary composition of the second filtration residue from the second set of vibratory devices of FIG. 2.
DETAILED DESCRIPTION
As discussed in detail below, embodiments of the present technique function to provide a system for separating suspended matter (including organic and inorganic matter) such as sand, filler material/fiber and peels from a starch-based material. In particular, the present technique employs liquefaction of the starch-based material to form a slurry. Moreover, the slurry is screened through a series of vibratory screening devices to separate the suspended matter. Advantageously, the technique facilitates removal of the suspended matter from the slurry, thereby enhancing the efficiency of a downstream system that processes the starch-based material to form a fermentation product, for example.
References in the specification to "one embodiment", "an embodiment", "an exemplary embodiment", indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
Turning now to drawings and referring first to FIG. 1, process steps 10 for processing a starch-based material are illustrated. At block 12, a starch-based material is received from a storage unit. An open yard (covered/un-covered) or silos may be used to store the starch-based material at ambient temperature. The starch-based

material includes tubers, roots, whole grain, grits or flour, or combinations thereof. In one exemplary embodiment of the present invention, the starch-based material includes, but is not limited to, cassava, corn, millet, rice, oat, wheat, barley, buckwheat, rye, triticale, manioc, tapioca, sorghum (all variants), potatoes, or combinations thereof.
Moreover, the starch-based material is cleaned to remove foreign particles (block 14). At block 16, the cleaned starch-based material is subjected to milling operation to form starch-based materia! of desired particle size. In one exemplary embodiment, a plurality of hammer mills may be employed to convert the raw material into a flour of desired particle size. At block 18, a slurry is formed by mixing the starch-based material with a water stream. In certain embodiments, recycled water streams from a downstream process may be utilized to form the slurry.
At block 20, the starch-based material is then liquefied in the presence of liquefaction enzyme to hydrolyse convertible starch in the raw material to dextrin. In this exemplary embodiment, the liquefaction enzyme includes alpha-amylase enzyme. The liquefaction of the starch-based material may be performed at a desired temperature and pH. In this embodiment, the liquefaction process is carried on at a temperature in a range of about 50°C to about 90°C. Moreover, the pH is maintained in the range of about 4.5 to about 6.5. In one exemplary embodiment, caustic solution is utilized to maintain the pH levels during the liquefaction process. In another exemplary embodiment, a viscosity reducing enzyme is utilized to reduce the viscosity during the liquefaction process. Examples of viscosity reducing enzyme include beta glucananses, arabino xylanases, pectinases, cellulases, hemicellulases and proteases, among others.
At block 22, the slurry is screened via one or more vibratory screening devices to form a first filtrate stream and a first filtration residue. It should be noted that a number and a size of the one or more vibratory screening devices is based upon a desired quantity of the fermentation product to be produced per day by a downstream process. For example, the mesh size and the angle of the vibratory screening devices may be selected based upon composition of the raw material used, particle size distribution of the flour and sand and other suitable parameters.

The first filtration residue includes sand, fiber, and peels as suspended matter. The first filtration residue also includes water, other dissolve solids and dextrins as dissolved solids. At block 24, the first filtration residue is mixed with hot water to form an intermediate slurry in a suitable tank with mixing device. The intermediate slurry is further screened via one or more vibratory screening devices to form a second filtrate stream and a second filtration residue (block 26). The second filtration residue further facilitates separation of suspended matter and is collected for use as a fertilizer, animal feed, fuel, land filling material and for other suitable purposes. As will be appreciated by one skilled in the art the number of processing stages can be lesser or greater based on the desired product composition in filtrate residue.
At block 28, fresh slurry is formed by mixing the second filtrate stream and the flour of the starch-based raw material. In one exemplary embodiment, the second filtrate strearn along with a portion of the first filtrate stream is mixed with the starch-based material to form the fresh slurry. In certain, embodiments, a mixture of the first and second filtrate streams is heated in range of about 90°C to about 130°C with injection of steam to control contamination of the dextrin solution- Subsequently the streams are cooled using a heat exchanger (block 30).
Moreover, the cooled stream is fermented to form a fermentation product such as, but not limited to, beverage grade alcohol, fuel grade alcohol, industrial alcohol and bio oils (block 32). Fermentation of the fresh slurry is accomplished by any organism (e.g., yeast) suitable for converting sugars, such as glucose and maltose to the desired fermentation product.
As will be appreciated by one skilled in the art, the technique described above utilizes two sets of vibratory screening devices to separate suspended matter such as sand from the starch-based material. However, the number of such screening cycles involving formation of intermediate slurry using filtration residues and screening such slurry rnay be more depending upon a variety of factors such as raw material type and composition, a capacity of the production plant producing the fermentation product, desired level of alcohol in the fermentation product, type of the fermentation product and so forth. Moreover, the present technique may also be utilized in combination with other

existing systems (e.g., gravity settling tanks and hydroclone /decantor separators) for separating suspended matter from the starch-based material.
FIG. 2 illustrates a system 50 for processing a starch-based material in accordance with aspects of the present invention. As illustrated, the system 50 includes a liquefaction unit 52 to receive a starch-based material from a storage unit 54 and to liquefy the starch-based material to form a slurry 56. In this exemplary embodiment, the starch-based material comprises cassava chips or tubers. Other starch-based materials include whole grain, flour {dry milled), slurry {dry or wet milled) corn, millet, rice, oat, wheat, barley, triticale, milo, buckwheat, rye, manioc, tapioca, sorghum, and potatoes.
Here, the starch-based material such as cassava chips is cleaned in the cleaning unit 58. The cleaning unit 58 may include a destoner 60 for removing stone and other foreign particles from the material. Moreover, a magnetic separator 62 may be employed to remove iron or other metallic material. Once the raw material is cleaned, it is subjected to milling operation in a milling section 64 to convert the material into flour such as cassava flour having a desired particle size. A set of hammer mills may be used in the milling section 64 to form the flour having the desired particle size. However, other suitable milling devices may be used. Alternatively, wet milling may be used in the milling section 64 for milling grains and tubers and to prepare slurry of desired solids concentrations.
In the illustrated embodiment, the liquefaction unit 52 utilizes fresh hot water streams, or recycled streams 66 from a downstream process for mixing with the cassava flour in a premasher (not shown) of the liquefaction unit 52. Moreover, steam 68 is introduced into the liquefaction unit 52 for maintaining a desired temperature for the liquefaction process. In this embodiment, the liquefaction process is carried on at a temperature in a range of about 50°C to about 90°C.
Furthermore, the liquefaction unit 52 employs a liquefaction enzyme 70 to hydolyse convertible starch to dextrin that solubilizes in the slurry 56. In this exemplary embodiment, the liquefaction enzyme 70 is alpha-amylase that is introduced in a dose of about 0.6 kg to about 0.9 kg per ton of the convertible starch. The alpha-amylase

enzyme is commercially available from companies, such as Novozymes and Genencor, among others.
In certain embodiments, caustic solution 72 is introduced in the liquefaction unit 52 to control the pH during the liquefaction process In this exemplary embodiment, the pH of the solution is maintained in a range of about 4.8 to about 6.5. A viscosity reducing enzyme 74 is introduced into the liquefaction unit 52 in a dose of about 0.2 kg to about 0.4 kg per ton of the convertible starch to reduce the viscosity during the liquefaction process. In this exemplary embodiment, the slurry includes about 25% w/w to about 34% w/w of dry solids. It should be noted that this composition may vary depending on the raw material type and composition as well as desired product concentration in the fermentation.
The system 10 includes a first set of vibratory screening devices 76 to screen the slurry 56 for separating suspended matter from the slurry 56. In this exemplary embodiment of the present invention, the cassava chips flour slurry 56 containing the suspended matter is transferred continuously to the first set of vibratory screening devices 76 using a pump (not shown). The suspended matter may include sand, fibers, filler materials, or combinations thereof. In this exemplary embodiment, the system may include one or more vibratory screening devices 76 for screening the slurry 56 and generate a first filtrate stream 78 and a first filtration residue 80. The first filtrate stream may be stored in a storage tank 82.
The vibratory screening devices are commercially available from companies, such as Pennwalt Ltd, India and Sharplex (India) Pvt Ltd., India and many more, it should be noted that a number and a mesh size of the vibratory screening devices 76 may be selected based upon a variety of parameters such as type of the starch material, a desired composition of a fermentation product formed by the starch-based material, among others. In this exemplary embodiment, the mesh size of the vibratory screening devices 76 is in a range of about 80 microns to about 350 microns.
The first filtration residue 80 contains fibers, peels and sand as suspended matter while water, other dissolve solids and dextrins as dissolve solids. The first filtration residue 80 is mixed with hot water stream 84 in a slurry tank 86 to form an

intermediate slurry 88. In particular, dextrin available as dissolved solids in the first filtration residue 80 is recovered via the intermediate slurry 88.
The system 10 includes a second set of vibratory screening devices 90 to screen the intermediate slurry 88 for separating residual suspended matter and generate a second filtrate stream 92 and a second filtration residue 94. The second filtration residue 94 may be dewatered by a screw press 96 to remove moisture and residual dextrin and is subsequently collected in a collection tank 98. In certain embodiments, stream from screw press 96 may be transferred to a storage tank 100 for reprocessing. The second filtration residue 94 and/or the residue from screw press 100 may be utilized as a fertilizer, animal feed, fuel, land filling material, among other suitable purposes.
The second filtrate stream 92 may be collected in the storage tank 100. In this embodiment, a portion of the second filtrate stream 92 and the stream from screw press 96 may be recycled to the liquefaction unit 52 for the liquefaction process. The second filtrate stream 92 and optionally a portion of the first filtrate stream 78 are then utilized to form a fresh slurry. In the illustrated embodiment, the first and second filtrate streams 78 and 92 are sterilized using steam 102 in a sterilization unit 104. The first and second filtrate streams 78 and 92 are heated to a temperature in a range of about 90°C to about 130°C for about 5 minutes to about 20 minutes with injection of steam supply 102 for disinfecting the dextrin solution.
The fresh slurry is formed by mixing cassava chips flour with the second filtrate stream 92 and is cooled in a heat exchanger 106 using cool water supply 108. Subsequently, the fresh slurry is fermented in a fermentation unit 110 to form a fermentation product such as ethanol.
As described above, the present technique enables suspended matter separation and removal using a series of vibratory screening devices. In one exemplary embodiment, a sand separation efficiency of the system 10 is in a range of about 75% to about 90%. Again, the sand separation efficiency may vary depending on raw material type, composition, milling, particle size distribution etc.. FIGS. 3-8 illustrate exemplary compositions of various streams generated using the system 10 of FIG. 2. FIG. 3 is a table 120 illustrating exemplary composition of the starch-based material such as

cassava chips utilized by system 10 of FIG. 2 for producing ethanoi / other products. The various chemicals employed by the system along with the operating conditions are described above with reference to FIG. 2.
As illustrated exemplary in table 120, the material includes starch in a range of about 65 % w/w to about 67 % w/w. The material further includes proteins, fats, fibers and peels, sand and water. It is desirable to separate the fibers and peels and sand from the material to increase the overall efficiency of the downstream processes and preventing erosion of the components of the system. The material is liquefied to form a slurry in the presence of the liquefaction agent.
FIG. 4 is a table 122 illustrating exemplary composition of the liquefied slurry provided to the first set of vibratory devices 76 of FIG. 2. As can be seen, the convertible starch from the raw material is converted to dextrin that is in a range of about 21.5 % w/w to about 22.5 % w/w owing to the liquefaction process. The slurry further includes reduced quantities of fats, fibers and peels and sand. The slurry is screened with the first set of vibratory devices 76 to form the first filtrate stream 78 and the first filtration residue 80.
FIG. 5 is a table 124 illustrating exemplary composition of the first filtrate stream 78. As can be seen, the quantity of suspended matter such as fibers and peels, and sand is reduced in the first filtrate stream and is separated via the first filtration residue. In the illustrated embodiment, the first filtrate stream 78 includes the fibers and peels in a range of about 0.05 % w/w and 0.06% w/w. Moreover, the first filtrate stream 78 includes sand in a range of about 0.1 % w/w and 0.15% w/w.
FIG. 6 is a table 126 illustrating exemplary composition of the first filtration residue 80. The first filtration residue 80 includes substantially high quantities of suspended matter separated through the first set of vibratory devices 76. In the illustrated embodiment, the first filtration residue 80 includes the fibers and peels in a range of about 24 % w/w and 24.5% w/w. Moreover, the first filtration residue 80 includes sand in a range of about 2 % w/w and 2.4% w/w. The first filtration residue 80 is utilized to form an intermediate slurry that is screened through the second set of

vibratory devices 90 to form the second filtrate stream 92 and the second filtration residue 94.
FIG. 7 is a table 128 illustrating exemplary composition of the second filtrate stream 92. As can be seen, the quantity of dextrin in the second filtrate stream 92 is relatively less as compared to the first filtrate stream 78. The residual suspended matter is separated via the second filtration residue 94. FIG. 8 is a table 130 illustrating exemplary composition of the second filtration residue 94. Here, the residual suspended matter i.e., fibers and peels and sand are separated and removed via the second filtration residue 94. As previously described, the second filtration residue 94 with the separated suspended matter may be disposed or utilized for suitable uses.
The various aspects of the technique described hereinabove may be used for separating suspended matter from a starch-based material used for producing fermentation products in fermentation plants. In particular, the technique described above utilizes liquefaction and series of screening steps using vibratory screening devices to substantially separate the suspended matter from the starch-based material thereby enhancing overall efficiency of such plants. Advantageously, the technique effectively separates the suspended matter while reducing loss of starch during the separation process.
The technique utilizes motor driven vibratory screening devices that have less chances to get clogged thereby requiring minimal manual intervention. Also, the separation and removal of suspended matter minimizes erosion of components of the system thereby facilitating continuity of the manufacturing processes and reducing overall capital and operating / maintenance costs of the production plants.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

WE CLAIM:
1. A method for processing a starch-based material, the method comprising:
liquefying the starch-based material in presence of a liquefaction enzyme to form
a slurry;
screening the slurry via one or more vibratory screening devices to form a first filtrate stream and a first filtration residue;
mixing the first filtration residue with water to form an intermediate slurry;
screening the intermediate slurry via one or more vibratory screening devices to form a second filtrate stream and a second filtration residue;
forming a fresh slurry using the second filtrate stream and optionally a portion of the first filtrate stream;
sterilizing and cooling the first and second filtrate streams; and
fermenting the cooled streams to form a fermentation product.
2. The method for processing a starch-based material of claim 1, further comprising repeating the steps of screening the slurry, mixing the first filtration residue and screening the intermediate slurry to achieve a desired composition of the second filtrate stream.
3. The method for processing a starch-based material of claim 1, wherein the starch-based material comprises chips, tubers, roots, whole grain, or combinations thereof.
4. The method for processing a starch-based material of claim 3, wherein the starch-based material comprises cassava, corn, millet, rice, oat, wheat, barley, triticale, buckwheat, rye, manioc, tapioca, sorghum, potatoes, or combinations thereof.
5. The method for processing a starch-based material of claim 1, wherein the fermentation product comprises beverage grade ethanol, fuel grade ethanol, industrial ethanol, high fructose/glucose syrups and their derivatives, or bio oils.

6. The method for processing a starch-based material of claim 1, wherein screening the slurry and the intermediate slurry separates suspended matter from the slurry through the first and second filtration residues.
7. The method for processing a starch-based material of claim 6, wherein the suspended matter comprises sand, filler material, fibers, or combinations thereof.
8. The method for processing a starch-based material of claim 1, wherein the liquefaction enzyme comprises alpha-amylase enzyme.
9. The method for processing a starch-based material of claim 8, wherein the liquefaction enzyme is introduced in a dose of about 0.6 kg to about 0.9 kg per ton of convertible starch.
10. The method for processing a starch-based material of claim 1, wherein the starch-based material is liquefied at a temperature in a range of about 50°C to about 90°C and at a pH in a range of about 4.8 to about 6.5.
11. The method for processing a starch-based material of claim 1, further comprising employing a viscosity reducing enzyme for liquefying the starch-based material.
12. A system for processing a starch-based material, comprising:
a liquefaction unit to liquefy the starch-based material and to a form a slurry; and
a first set of vibratory screening devices to screen the slurry for separating suspended matter from the slurry and generate a first filtrate stream and a first filtration residue;
a slurry tank to mix the first filtration residue with water to form an intermediate slurry; and
a second set of vibratory screening devices to screen the intermediate slurry for separating residual suspended matter and generate a second filtrate stream and a second filtration residue.

13. The system for processing a starch-based material of claim 12, wherein the starch-based material comprises chips, tubers, roots, whole grain, or combinations thereof.
14. The system for processing a starch-based material of claim 12, wherein the suspended matter comprises sand, filler material, fitters, or combinations thereof.
15. The system for processing a starch-based material of claim 12, wherein the liquefaction unit employs a liquefaction enzyme to hydrolyse convertible starch in the starch-based material to dextrin, wherein the liquefaction enzyme is introduced in a dose of about 0.6 kg to about 0.9 kg per ton of the convertible starch.
16. The system for processing a starch-based material of claim 12, wherein the starch-based material is liquefied at a temperature m a range of about 50° to about 90°C and at a pH in a range of about 4.8 to about 6.5.
17. The system for processing a starch-based material of claim 12, wherein the slurry comprises dry solids in a range of about 25% w/w to about 34% w/w.
18. The system for processing a starch-based material of claim 12, wherein a mesh size of the vibratory screening devices is in a range of about 80 microns to about 350 microns.
19. The system for processing a starch-based material of claim 12, further comprising a sterilization unit to introduce steam into the first and second filtrate streams and to form a fresh slurry using the second filtrate stream and optionally a portion of the first filtrate stream.
20. The system for processing a starch-based material of claim 19, further comprising a fermentation unit for fermenting the fresh slurry to form a fermentation product.

21. The system for processing a starch-based material of claim 12, wherein the liquefaction unit employs a viscosity reducing enzyme in a dose of about 0.2 kg to about 0.4 kg per ton of the convertible starch.
22. The system for processing a starch-based material of claim 12, wherein a sand separation efficiency of the system is in a range of about 75% to about 90%.
23. A system for processing a starch-based material, comprising:
. a liquefaction unit to liquefy the starch-based material and to a form a slurry; and
a first set of vibratory screening devices to screen the slurry for separating suspended matter from the slurry and generate a first filtrate stream and a first filtration residue;
a slurry tank to mix the first filtration residue with water to form an intermediate slurry;
a second set of vibratory screening devices to screen the intermediate slurry for separating residual suspended matter and generate a second filtrate stream and a second filtration residue;
a sterilization unit to sterilize the first and second filtrate streams, and to form a fresh slurry using the second filtrate stream and optionally a portion of the first filtrate stream; and
a fermentation unit for fermenting the fresh slurry to form a fermentation product.
24. The system for processing a starch-based material of claim 23, wherein the starch-based material comprises chips, tubers, roots, whole grain, or combinations thereof.
25. The system for processing a starch-based material of claim 23, wherein the suspended matter comprises sand, filler material, fibers, or combinations thereof. •