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Process and ConstructCon
Refining of peanut oil is representative of type of processing and equipment in vegetable oil industry by Walter 1. Hardy
and refining of vegeTtableisolation oils have become a major inHE
dustry. These oils are extracted or pressed from nuts and seeds, the most important of which are : Oil Cottonseed Linseed (flaxseed) Soybean Coconut (copra) Peanut (shelled) Babassu (kernels) Castor (seed) Tung (nuts) Corn (seed o r germ)
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Oil Content, % 15-20 34-40 15 60-65
45-49 63-70 35-55 50-60 50
Vegetable oils are used extensively as food, in the manufacture of soap, in paints and varnishes, as lubricants, and as a n ingredient in many industrial products. Usable grades of many vegetable oils may be obtained by expression or, more recently, extraction from the raw seed without further treatment. In most cases, however, it is necessary to refine the crude oil t o free it of fatty acids, color, and odoriferous substances. The refining of peanut oil has been selected as representative of the type of processing and equipment t o be found in the vegetable oil industry. Two plants-A, capacity 220 pounds per hour of refined peanut oil, and B, capacity 500 pounds-are analyzed to illustrate investment and operating costs involved in making vegetable oils A flow diagram of this process is presented in Figure 1.
ing blower. The upper tray i 6 designed to sift, first, the fine cut, then coarser and whole kernels, which drop to the lower tray. Shells are lifted by suction and discharged to a cyclone. The discharged kernels from the lower tray are conveyed t o a disk mill, where they are ground. The ground meats are then introduced into a, continuous steamheated rotary dryer, where the water content is reduced to 2 to 4% by weight. The resulting dried meats are fed to a continuous expeller, which is essentially a continuous screw press. The rotation of a tapered screw within a slotted curb forces the material forward under increasing pressure. Crude oil is expelled and escapes through the slots in the curb. -4 cake containing from 4 to 6% by weight of residual oil is discharged continuously, ground, and collected. The crude product is collected in a holding tank, from which it is pumped through a
December 1955
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Raw peanuts are conveyed to an oscillating shaker cleaner, where adhering dirt and other contamination are removed. The cleaned nuts are then passed through a disk huller or decorticator vrhich breaks up their shells. The decorticator consists of a fixed and a rotating disk with faces sloped t o permit close contact a t the periphery. The nuts enter a t the disk shaft and are thrown centrifugally t o the periphery, where they are cut. The resulting mixture of nut kernels and broken shells falls from the disk huller discharge t o the top tray of a n oscillating separator-purifier-two inclined screen trays fitted with an aspirat-
filter press to remove suspended solids or “settlings,” which may be recycled to the expellers. The filtered crude oil is refined to remove very fine or colloidally suspended oil-insoluble impurities as well as such oil-soluble impurities as fatty acids, proteins, gums, resins, phosphatides, coloring matter, and odoriferous materials. The refining process starts with treatment of the oil with alkali. An excess of caustic soda over that required to neutralize the free fatty acid is used. As a remlt, some of the neutral fat is saponified and lost as soap. The resulting settled alkaline l‘ayer or “foots” contains most of the oil-soluble impurities and a portion of the coloring matter as well as some included oil, dispersed as an emulsion. This settled layer is pumped to waste or converted into soap. The neutralized oil is washed with salt water and then pith hot vater t o remove
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Figure 1. 1.
2. 3.
4.
5. 6.
7. 8.
9. 10.
11. 12. 13. 14. 15.
Process flow diagram of peanut oil plant
Shaker-cleaner Elevator Disk huller-decorticator Separator-cleaner Cyclone shell collector Elevator Disk mill Rotary steam dryer Elevator Expeller Surge tank Rotary pump Cake grinder-pulverizer Filter press Holding tank
16.
17. 18.
19. 20. 21. 22. 23.
24. 25. 26.
2 7. 28.
29. 30.
Rotary pump Neutralizer vessel Rotary foots pump Foots tank Holding tank Rotary pump Bleaching and drying tank Duplex piston pump Filter press Holding tank Rotary pump Deodorizing vessel Holding tank Rotary pump Filter press
INDUSTRIAL AND ENGINEERING CHEMISTRY
63 A
costs residual alkali, and dried under heat and vacuum. The dried oil is bleached by agitation with clay. The oil-clay slurry is filtered to se a rate the clay, and the bleached oiri, pumped to intermediate storage. The bleached oil is freed from odorous volatile constituents in a deodorizer vessel, where the odoriferous matter is distilled off by sparged steam in vacuum and at elevated temperatures (150’ to 250’ (2.). The deodorized oil is cooled, refiltered for final clarification, and pumped to product storage. Material balances for these two plants are given in Table I. Table I.
Material Balance Plant A 538 772 220 29 318 28.5 41.2
Shelled nuts, ib./hr. Unshelled nuts, lb./hr. Product oil, Ib./hr. Product oil, gal./hr. Cake, Ib./hr. Oil,wt. yo (on unshelled) Cake, wt. yo (on unshelled)
Plant B 1,222 1,754 500 66
722 28.5 41.2
The national average support price for all types of peanuts is 12.2 cents per pound, shelled. Current wholesale prices of peanut oil are 17.6 cents per pound of crude and 24.7 cents per pound refined; 45% protein peanut meal obtained as a by-product sells for $78 per ton.
Let’s talk “SPECIAL SIZES” The size and depth of sinks for laboratory and industrial use should be determined by the j o b they have to do - and not by available
standard sizes! With Alberene Stone sinks you can specify any size and depth without paying a premium.
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And with Alberene Stone you get - the natural silicate stone with the surface that goes all the way thru. Its all-silicate mineral components resist chemical attack. Low absorbency makes it essentially nonstaining. Discolorations can be removed by scouring or honing without harm to t h e surface. For information a n d technical assistance, address : Alberene Stone Corporation, 419 Fourth Avenue, New York 16, N. Y.
provides LOW ABSORBENCY protection For further information, circle number 64 A on Readers’ Service Card, paxe 111 A
64 A
Estimated Investment Cost of Peanut Oil Plant Plant A , 220 Lb./ Hour
Plant B , 500 Lb./ Hour
Cleaning and shelling $ 9,200 $ 10,000 equipment 48,500 Pressing equipment 23,300 33,500 42,500 Refining equipment Auxiliary electrical equip2,100 3,400 ment Total equipment $ 68,100 $104,400 ~~
Estimated erection cost (excluding building and site) Total erected cost Estimated working capital Total plant investment excluding building and site
$
60,000
$
80,000
~~
$128,100 $184,400 $ 40,000 _ _
_
60,000
$ i 6 s , i o o $244,400
Peanut requirements will be 12,912 pounds per day for Plant A and 29,328 pounds per day for Plant B based on shelled weight; 45y0 protein peanut meal will be obtained as a salable byproduct in quantities of 7632 pounds per day for Plant A and 17,328 pounds for Plant 13. If the peanuts are charged a t the support rate of 12.2 cents per shelled pound, raw material costs will be $1575 per day for Plant A and $3578 for Plant B. Against these costs may be credited the sales price of $78 per ton of by-product peanut meal-
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Vol. 47, No. 12
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TREME DRYNESS?
E
ALCOA Activated Alumina dries to lower dew points than other commercial adsorbents -.
_ _ _ ~ ~~
TYPICAL PROPERTIES OF DESICCANT GRADES ALCOA ACTIVATED ALUMINAS CHEMICAL ANALYSIS,
%
F- 1
The standard sizes far F g r a d e alumina a r e !huto %", % ' t o 8 mesh and 8 to 14 mesh. Other nonstandard sizes from 2" granules to 325 mesh powder are available. Activated Alumina H-151 is available in nominal !h'' and !4" diameter balls. F.
F-3
F-5
F-6
H-151
*Adsorption of moisture a t 100% efficiency from air under isothermal conditions a t 30°C a n d 8 4 % relative humidity under dynamic flow of 7.5 cu ft/hr/lb Activated Alumina--lfs Properties and Uses. tMethod o f Activated Alumina-/fs Properties and Uses
..
ALCOA" Activated Aluminas are a m o n g the most effective and efficient desiccants available for the dehydration of liquids a n d gases. Dew points as low as minus 100°F-and even lower -may be obtained, a n d under normal circumstances, ALCOAActivated Aluminas can be used for an almost indefinite number of drying cycles. Besides their use for dehydration, ALCOA Activated Aluminas adsorb certain gases and vapors from gaseous mixtures and serve as catalysts and catalyst carriers. They are used in the liquefaction of gases, a n d for the maintenance of transformer a n d lubricating oils.
Let us tell you more a b o u t these efficient desiccants, a n d supply you with samples. Write
to ALUMINUM COMPANY OF AMERICA,CHEMICALS DIVISION,703-M Alcoa Building, Pittsburgh 19, Pa.
L V M l N Y M C O M P A N Y OF AWEF?ICA
For further information, circle number 65 A on Reade
D e c e m b e r 1955
INDUSTRIAL AND ENGINEERING CHEMISTRY
65 A
costs $297.65 per day for Plant' A and $675.70 for Plant B. Estimated Production Cost (24-hour basis, 260 days per year) Plant A, 220 Lb./ Hour Labor (excluding maintenance labor) Unskilled. 24 manhours B)t $1.60 Semiskilled, 24 ma.nhours a t $2.10 Supervision, 24 manhours a t $3.00 Reserve a t 20% Total labor
PRECISION BORE b r STIRRERS
Utilities Steamat$1.00/1000lb. Power a t New York industrial rates Water Total utilities
with interchangeable parts
Maintenance cost (including maintenance labor) a t 5% per year of total erected cost Depreciation to cover e a u b m e n t deterioriti6n and process obsolescence a t 10% of total erected cost Other to cover taxes, insuranoe, etc.. a t 3'% of erected plant cost Total estimated D r o duction cost/day Estimated production cost per pound of product
Manufactured in a variety of styles to meet every laboratory need, Wilmad Precision Bore Stirrers are the ultimate in glassware craftsmanship. Rods and bearings fit to a closer tolerance than was ever believed possible. All stirrers, bearings, rods and blades are interchangeable and we stock them in a complete line of Standard Taper and Spherical Joints for all sizes of flasks.
WILMAD PRECISION BORE TUBING Available in Pyrex Brand Glass, Vycor and most of the electronic glasses, Wilmad Precision Bore Tubing is manufactured in various shapes and sizes square, rectangular and tapered. Unbelievably accurate and uniform, this tubing can be supplied with I.D. tolerance down to & .0002". O.D. can be ground to your specifications. A rigid 100% inspection of all our products eliminates rejects before they reach you.
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