Equipment and Systems for Corn Wet Milling

Corn Wet Milling Process Flowsheet

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Dewatering, Germ Washing, and Fiber Washing

Dewatering and Germ WashingEconomical corn wet milling practice requires dewatering of the supply stream ahead of the degerminating mills. Also the separated germ must be washed to get a high purity germ product free of starch.

Gravity-Fed DSM® ScreensDewatering and germ washing are done more effectively with Dorr-Oliver DSM screens. The DSM screens for these applications are gravity fed over a weir. A single stage screen is used for dewatering. For germ washing, however, three stages of DSM screens are used. The wash water flows countercurrently and removes the starch quite efficiently as the germ moves forward from stage to stage.

Benefits of Gravity-Fed DSM Screens• No maintenance necessary as

screen media is rugged stainless steel and there are no moving parts.

• Space needed is minimal since units are compact and handle high throughputs. Cascade mounting arrangement of three screens also makes effective use of available space.

• Operation is trouble free due to non-blinding, wedge wire screen surface.

• No fumes and spillage as screens are totally enclosed.

Fiber WashingTo get maximum starch recovery, while keeping any fiber in the final product to an absolute minimum, it is necessary to wash the free starch from the fiber during processing.

Pressure-Fed 120 DSM® ScreensMost plants accomplish this very economically today with the Dorr-Oliver Fiber Washing System. The system consists of six stages of 120 DSM screens. The pressure fed screens are arranged for countercurrent washing of the fiber, with the starch reporting to the undersize. The extremely fine separations are possible only with our highly polished wedge wire screen surfaces with openings as fine as 50 microns. The DSM screen’s precisely selected screen media and its proven reliability are unmatched by equipment using fragile textiles or thin etched screens. Benefits of Pressure-Fed 120 DSM® Screens• Close tolerance, engineered feed

system distributes feed flow across screen surface with high velocity for highly effective separation.

• System’s multi-stage countercurrent flow design assures maximum starch yield.

• High capacity compact design drastically curtails space needed for fiber washing operations.

• Requires little operator attention because system is designed for small sumps, uses standard pumps and has simple instrumentation.

• Long service life due to no moving parts, quick reversible and totally enclosed design.

• Screens available in single, double and triple width configurations for maximum flexibility in system design.

Gravity-Fed DSM Screen

Pressure-Fed DSM Screen

Germ Separation & Starch Washing Systems

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Germ SeparationAfter the corn kernels are steeped for softening, they are cracked open to release the germ. The germ contains the valuable corn oil. The germ is separated from the heavier density mixture of starch, hulls and fiber essentially by “floating” the germ segments free of the other substances under closely controlled conditions. This method serves to eliminate any adverse effects of traces of corn oil in later processing steps.

Manifolded DorrClone SystemsTo accomplish this critical separation most efficiently, most plants today use Dorr-Oliver’s compact manifolded two-stage Germ Separation System. Specially sized DorrClone cyclones and

engineered flow distributions are specifically designed for the magma/germ separation. Because of the high centrifugal forces employed, germ is separated instantly. The first pass makes a selective separation for optimum purity and the second pass increases germ recovery by capturing any germ that may have been bypassed in the first stage. This system has given processors a new standard of process control and sanitation.

Benefits of Germ Separation DorrClones• Maximum germ oil recovery (very

low loss of the valuable process fraction).

• Easy maintenance and quick replacement of individual cyclone units because of the quick opening couplings.

• Rapid response to process changes through single instrument control.

• Totally enclosed design assures clean and fume-free operating area.

• Lightweight construction and shipment as a complete factory assembled package means low cost installation.

• Modular system design allows easy expansion when production demands dictate.

Starch washingThe starch slurry from the primary separation contains some insoluble protein and much of the solubles. They have to be removed before a top quality starch can be made. Modern plants are using Dorr-Oliver Starch Washing Systems for this important task.

Hydrocyclone Starch Washing SystemA typical Dorr-Clone or Hydrocyclone Starch Washing System consists of batteries of 10 mm cyclones in completely unitized and enclosed housings, arranged for efficient countercurrent washing. The centrifugal forces needed to make the separation are derived from energy supplied by pumps. The high rotational velocities in the individual cyclones cause the starch to concentrate in the underflow while the suspended gluten follows the overflow wash water stream. The multi-stage systems provide easy and precise control of the process, resulting in the uniform, high quality starch required in today’s highly demanding marketplace. The latest in starch washing technology incorporates recently developed high-efficiency 10mm cyclones for the Starch Washing System. These high capacity units incorporate advanced flow channeling with superior materials and layout to save money in installed cost and operating power. Varying plant capacities can be handled.

Benefits of Starch Washing Hydrocyclones• Easy operation because simplified

control system uses self regulation of intermediate stages.

• Improved sanitation since system is completely closed and pressurized

• Low maintenance. The only moving parts are in the standard centrifugal pumps.

• Capital cost is less because of the system’s compactness, which saves on space, and easy expandability when additional capacity is needed

5

Gluten Dewatering

Gluten DewateringBefore the gluten moves on to drying it is good practice to dewater the gluten slurry from the gluten thickener, which obviously saves on the energy required to thermally dry a high moisture product. This is usually accomplished economically on a rotary drum filter with belt discharge.

Dorr-Oliver Eimco E-Belt Drum FilterDorr-Oliver Eimco E-Belt Drum Filters for corn wet milling applications have been adapted to meet the industry’s specific needs for corrosion resistance and sanitation. Filters are of stainless steel construction and are equipped with streamlined internal piping and valves, snap-in plastic supporting media and easily adaptable discharge mechanisms.

Its reliable filtration enhances product recovery minimizing protein loss.

Benefits of E-Belt Drum Filters• No more blinding problems and

greatly improved washing and cloth tracking with the revolutionary swivel roll concept that doesn’t require filter cloth rubber edges.

• Delivers high rates of filtration and high hydraulic capacity for cake dryness enhancement.

• Hi Hydraulic capacity• Food design for cleaning and

sanitation• Innovative cloth alignment design• Low installation costs and clean

working environment due to compact design.

• No operator attention required.• Minimal maintenance

Starch Washing and Filtration

6

Pneumapress® automatic pressure filters were successfully introduced into the starch washing and dewatering process in 1997. Since that time, the Pneumapress design has evolved to meet the changing needs of the industry and Pneumapress equipment is now installed by the majority of the major starch producers worldwide. The starches processed on the Pneuma-press include corn, wheat, potato and tapioca starches – including modified, industrial and food grade varieties. Pneumapress filters are installed in starch plants the USA, Germany, Thailand, Korea, France and Italy.

The design focus of Pneumapress for the starch industry is to provide a mechanically simple, sanitary and efficient filter. Pneumapress filters do not require rubber seals or dia-phragms, simplifying the operation and maintenance of the equipment. Significant repeat business and referral sales are indicative of the success of the Pneumapress design.The most common throughput sizes for single filters on native starches are in the range of 6 to 25 metric tons per hour dry solids and for modified starch are in the range of 4 to 20 metric tons per hour dry solids.The cleaning and hygiene require-ments at food starch plants are becoming more stringent. Pneuma-press has recognized this need and created a patented sanitary design option to enable ease of cleaning and sanitization. This option incorporates a fully automatic clean in place (CIP) system.

The Pneumapress filter can be totally enclosed to prevent product contami-nation and provide increased safety for those working in the vicinity. This enclosure may be designed in 316 stainless steel to provide the ultimate in sanitary design and safety.

Benefits of Pneumapress Filters• Very dry filter cakes with highly

effective cake washing when required

• Highest throughput per unit area of any filter, which minimizes the required filter area, equipment size, number of moving parts and maintenance downtime

• Advanced filter media design and effective filter media cleaning provide very clean filtrate

• Mechanically simple design eliminates consumables such as diaphragms and seals

• Filter plates are made completely from 316 stainless steel

• An isolatable plate design provides very high equipment availability

• Sanitary or industrial design with optional filter housing, structure cladding, and CIP systems

• Single-sided cake discharge• Low installation costs

Pneumapress Sanitary Multi-Module Filter

Filter enclosed in sanitary housing

Cake discharge from filter

7

Starch Conversion and Hydrogenation

Polishing syrupTo remove impurities from syrup in the sweetener plant, general industry practice is to use a precoat vacuum filter, simply because precoat filters produce the clearest syrups.

Hydrogenation:Through Catalytic reactions, starch can be converted into a wide family of “low calories sugar” used in food and pharmaceutical products.

Dorr-Oliver Eimco’s Precoat Filterfeatures a slow and precise knife advance system that assures the lowest precoat expense without affecting the machine’s high through-put rates. The precoat material can be applied to the filter in varying thicknesses and users get longer processing cycles between filter medium replacements. The unit’s exclusive scraper design enables the operator to better control removal of impurities with minimum loss of precoat material, and this also keeps operating costs down.

Benefits of Pre-Coat Filters • Consistently clear and better

quality syrup.• Longer operating cycles and

equipment life.• Can be readily adapted to meet

varying process needs.• Effective use of precoat, without

waste, lowers operating costs.• Revolutionary precoat discharge

system electronically control for reduced precoat consumption and longer filtration cycle.

IBF, Indexing Belt FilterDorr-Oliver Eimco IBF is one of the many products in our portfolio for vacuum filtration of a wide range of hydrogenated compounds. The continuous operation together with a simple mechanical design reduce maintenance offering steady and reliable operation.

Benefits of IBF Filters• Food design, FDA validated.• Totally enclosed execution for

solvent washing• Smooth filtration with no particle

size modification.• Superior washing efficiency for

maximized product recovery.• Cleaning in place for complete

sanitation.

Dorr-Oliver Eimco Indexing Belt Filter (IBF)

Dorr-Oliver Eimco Precoat Filter

Copyright ©2010 FLSmidth A/S. ALL RIGHTS RESERVED. FLSmidth is a (registered) trademark of FLSmidth A/S. This brochure makes no offers, representations or

warranties (express or implied), and information and data contained in this brochure are for general reference only and may change at any time.

Minerals Processing Technology CenterFLSmidth Salt Lake City, Inc.7158 S. FLSmidth DriveMidvale, UT 84047-5559Tel: +1 801 871 7000email: info.slc@flsmidth.com

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Suspension @ 60°F Dry Solids Content Water Content

Be Sp Gr % D.S.* Lbs/Gal Lbs/Gal Oz/Gal Gr/Gal Gm/Liter Lbs H2O Gal Susp Lbs H2O Lb Starch Gal H2O Lb Starch

0.0 1.0000 0.00 8.328 0.000 - - - 8.328 - -

0.5 1.0035 0.89 8.357 0.074 1.184 518 8.87 8.283 111.93 13.437

1.0 1.0069 1.78 8.386 0.149 2.384 1043 17.85 8.237 55.28 6.636

1.5 1.0105 2.66 8.416 0.224 3.584 1568 26.84 8.192 36.57 4.390

2.0 1.0140 3.55 8.445 0.300 4.800 2100 35.95 8.145 27.15 3.260

2.5 1.0176 4.44 8.475 0.376 6.016 2632 45.18 8.099 21.54 2.586

3.0 1.0211 5.33 8.504 0.453 7.248 3171 54.28 8.051 17.77 2.133

3.5 1.0248 6.22 8.535 0.531 8.496 3717 63.63 8.004 15.07 1.809

4.0 1.0285 7.11 8.566 0.609 9.744 4263 72.98 7.957 13.07 1.570

4.5 1.0322 8.00 8.596 0.688 11.008 4816 82.32 7.908 11.49 1.379

5.0 1.0358 8.89 8.626 0.767 12.272 5369 91.79 7.859 10.25 1.231

5.5 1.0396 9.77 8.658 0.846 13.536 5922 101.38 7.812 9.23 1.108

6.0 1.0433 10.66 8.689 0.926 14.816 6482 110.96 7.763 8.38 1.006

6.5 1.0470 11.55 8.720 1.007 16.112 7049 120.67 7.713 7.66 0.920

7.0 1.0508 12.44 8.751 1.089 17.424 7623 130.49 7.662 7.04 0.845

7.5 1.0547 13.33 8.784 1.171 18.736 8197 140.32 7.613 6.50 0.780

8.0 1.0585 14.22 8.815 1.253 20.048 8771 150.15 7.562 6.04 0.725

8.5 1.0624 15.10 8.848 1.336 21.376 9352 160.09 7.511 5.62 0.675

9.0 1.0663 15.99 8.880 1.420 22.720 9940 170.16 7.460 5.25 0.630

9.5 1.0703 16.88 8.914 1.505 24.080 10535 180.34 7.409 4.92 0.591

10.0 1.0742 17.77 8.946 1.590 25.440 11130 190.53 7.356 4.63 0.556

10.5 1.0782 18.66 8.979 1.676 26.816 11732 200.71 7.303 4.36 0.523

11.0 1.0822 19.55 9.013 1.762 28.192 12334 211.14 7.251 4.12 0.495

11.5 1.0862 20.44 9.047 1.849 29.584 12943 221.56 7.198 3.89 0.467

12.0 1.0903 21.32 9.080 1.936 30.976 13552 231.99 7.144 3.69 0.443

12.5 1.0944 22.21 9.114 2.024 32.384 14168 242.65 7.090 3.50 0.420

13.0 1.0986 23.10 9.149 2.113 33.808 14791 253.32 7.036 3.33 0.400

13.5 1.1028 23.99 9.185 2.203 35.248 15421 263.98 6.982 3.17 0.381

14.0 1.1071 24.88 9.220 2.294 36.704 16058 274.89 6.926 3.02 0.363

14.5 1.1114 25.77 9.256 2.385 38.160 16695 285.79 6.871 2.88 0.346

15.0 1.1156 26.66 9.291 2.477 39.632 17339 296.82 6.814 2.75 0.330

15.5 1.1199 27.54 9.327 2.569 41.104 17983 307.84 6.758 2.63 0.316

16.0 1.1242 28.43 9.363 2.662 42.592 18634 318.98 6.701 2.52 0.303

16.5 1.1286 29.32 9.399 2.756 44.096 19292 330.25 6.643 2.41 0.289

17.0 1.1330 30.21 9.436 2.851 45.616 19957 341.63 6.585 2.31 0.277

17.5 1.1375 31.10 9.473 2.946 47.136 20622 353.02 6.527 2.22 0.267

18.0 1.1419 31.99 9.510 3.042 48.672 21294 364.52 6.468 2.13 0.256

18.5 1.1465 32.88 9.548 3.139 50.224 21973 376.14 6.409 2.04 0.245

19.0 1.1500 33.76 9.586 3.236 51.776 22652 387.89 6.350 1.96 0.235

19.5 1.1556 34.65 9.624 3.335 53.360 23345 397.23 6.289 1.89 0.227

20.0 1.1602 35.54 9.662 3.434 54.944 24038 411.49 6.228 1.81 2.170

20.5 1.1649 36.43 9.702 3.534 56.544 24738 423.48 6.168 1.75 0.210

21.0 1.1696 37.32 9.741 3.635 58.160 25445 435.58 6.106 1.68 0.202

21.5 1.1744 38.21 9.781 3.737 59.792 26159 447.80 6.044 1.62 0.194

22.0 1.1791 39.09 9.820 3.839 61.424 26873 460.02 5.981 1.56 0.187

22.5 1.1840 39.98 9.861 3.942 63.072 27594 472.49 5.919 1.50 0.180

23.0 1.1888 40.87 9.901 4.047 64.752 28329 484.95 5.854 1.45 0.174

23.5 1.1937 41.76 9.941 4.151 66.416 29057 497.41 5.790 1.39 0.167

24.0 1.1986 42.65 9.982 4.257 68.112 29799 510.11 5.725 1.34 0.161

24.5 1.2036 43.54 10.024 4.364 69.824 30548 522.93 5.660 1.30 0.156

25.0 1.2086 44.43 10.065 4.472 71.552 31304 535.76 5.593 1.25 0.150

Bau

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arch

Su

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- 60

°F

*% D.S. = Be deg x 1.7770

Specific Gravity of Starch 1.5 - 1.6

Temperature Corrections

Temperature Add (°Be)

67 .1

73 .2

79 .3

85 .4

91 .5

97 .6

103 .7

113 .9

118 1.0

123 1.1

These tables are based on the work of J.E. Cleland, E.E. Fauser and W.R. Fetzer.See Industrial and Engineering Chemistry, Analytical Edition, Vol. 15, pp 193-200, 1943

Customer ServiceFLSmidth is your One Source for spare parts, service, maintenance, asset management, and operational services. Our Customer Services provide a wide range of services for food processing equipment and systems including process design, equipment installation, troubleshooting, process and mechanical analysis, and commissioning of new plants.

We design and install your processing systems with quality Dorr-Oliver, EIMCO, Krebs and Pneumapress equipment. Our experts provide the tools to ensure that your systems continue to operate at optimum levels, all the time. It is by no means a radical concept. Indeed, everyone promises it; we deliver it!