Processing Fatty Oils A. D. RICH Fillrol Colpomtion, 10s An&$
F.
ATTY oils, as referred to in this paper, are the vegetable, annual, u r i n e oils and fats, the fatty acids, tall oil, and vegetable and insect waxes. The fatty o h constitute the raw materbk for such common household commodities as shortening, margarine, frozen dessert, salad and cooking oil, soap, p h t , plastics, candles, and the &e. During the manufacture of these commodities, the crude fatty oil is refined, or purified, by chemical and physical treatment (1, 4). One of the methods of purification is decolorking, or bleaching. The fatty oil is treated with an adsorbent clay or carbon a t a moderately elevated temperature, either exposed to the atmosphere, under vacuum, or in an inert atmosphere, T h e adsorbent k agitated with the fatty oil and separated by iitration, carrying with it the color constituents adsorbed from the oil. Most bleaching operations are the batoh type; however, in recent years continuous bleaching units have heen introduced into the industry ( 6 , 7 ) . In 1944 a fatty oil plant was constructed by the Filtrol Corp. for the purposes of developing new adsorbent clays for bleaching, solving bleaching problems encountered in the industry, and developing improved bleaching methods. Adequate laboratory scale testing would have greatly simplified the in&tigation. uu-
17, Calif.
fortunately, laboretory scale bleaching procedures are not reliable criteria of commercial scale performance; therefore i t WBB necessary t o attain the desired goals in B pilot scale plant. Table I and I1 illustrate typical differencesin color of fatty oils treated with laboratory and commercial plant bleaches when oik and fats from the same storage tank were treated with the same dosage of the same adsorbent. T h e plant blese6ed color was better in every case, as usual. The laboratory bleached color is superior only in rare instances. The r e a n for variations in results from the laboratory and commercial plants lies in the difference in equipment and opera& ing conditions employed in the two types of operation. Factors such as the volume of oil bleached, over-all time of contact b e tween adsorbent and oil, degree of agitation, thickness of filter cake, and materiale of construction of the equipment all influence the results (6). The two most important speoi6c factors, both of which favor the phnt’s performance, are the larger volume of oil treated in the plant, effecting less oxidation which in turn results in less fixation of color during bleaching (5,8), and the additional bleach imparted by the adsorbent in the commercial filter press, aince the laboratory procedure has no such supplementary assistance (#). Thus, a bleaching unit on a pilot plant
CONVERTER
OIL STORAGE
OlPRoE WMP
BLEecn BLEAM WHP
Figure 1 .
2272
PRESS
’r
CONVERTER DEWORZER DmWRDER Fs€s PIMP mss
Flow Diagram of Pilot Plant for Processing Fatty Oils
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 46, No. 11
same type equipment in which these Operations are carried out in the commercial plant (Figure 1).
Table I. Laboratory and Plant Bleaching of Oils (Off-quality neutralized expeller cottonseed oil and normal quality neutralized extracted soybean oil, double water washed and vacuum dried after neutralizing) LABORATORS Procedure : Oil (300 g.) was open-cup bleached a t 245-249" F. and 255 r.p m. niechanical agitation with 0 1% activated carbon -4 added with the clay adsorbent a t 74-76' F. Filtration was started a t bleaching temperature and finished a t 216-219' F and required 6-8 min. Time a t bleaching temperature was 5 min. after taking 5-6 min. t o reach temperature. Dosage, actirated clay adsorbent A . 5% Bleached color, Lovibond (51/4 inch) (Y-R)O
Cottonseed Oil 1.67
Soybean Oil 0 625
50-12.9
50-8 0
Units Are Miniature Counterparts of Commercial Equipment
The units comprising the pilot plant were arranged as indicated in Figure 2 with the operating units-the neutralizer, bleacher, converter, and deodorizer tanks-laid out in the form of a < L T 1, I,. The neutralizer and bleacher were located on one side of the U; on the other side were the converter and deodorizer. The control panel was set a t the base of the U and the relatively large crude oil storage tank in the immediate rear of the neutralizer and deodorizer. Storage tanks for neutralized and deodorized
PLANTA (12,000-13,000-LB. BATCHES) Procedure: Oil from same storage tanks as t h a t in the laboratory tests was atmospherically bleached a ith 63 r.p.m. mechanical agitation. Temperature of bleaching was 220-227' F. with 0.1% activated carbon A and clay adsorbent added a t 21&224° F. Weight of oil charge varied from 12,000 to 13,000 lb. Filtration was started a t 219-223' F. and finished a t 187-1WJ0 F. Time t o reach temperature of bleaching was 38-45 min., time a t temperature of bleaching was 27-35 min., while time of recirculation ranged from 2-6 min., and the time of filtration was 46-56 min.
Dosage activated clay adsorbent -4 % ' Bleache'd color, Lovibond (6114 inch) (Y-R) b a b
Cottonseed Oil Run 1 R u n 2 1.67 1.67
Soybean Oil Run 1 Run2 0 , 6 2 5 0.625
35-9.0
45-4.7
35-8.7
DEODORIZER CONTROL
RES%
\
BNEL
OEOOORIZEC OIL
=>= I \ DEOWRIZER
'
35-4.6
CONVERTER
Laboratory and Plant Bleaching of Tallows
(Tallows dry rendered under v.ebuum) LABORATORY Procedure outlined in Table I Fancy Fancy Tallow Tallow A B Dosage, activated clay adsorbent B, % 1,50 2.00 Bleached color, Lovibond (51/4 inch) (Y-R)a 34-7.0 4 5 - 6 . 1
Fancy Tallow 2.00
Prime Tallow 1.00
15-1.9
40-6.6
C
PLAXT B (23,000-30,300-Ln. BATCHES) Procedure outlined in Table I Fancy Tallow A Dosage, activated clay adsorbent B ,3' % 1 50 Bleached color, Lovibond (51/4 inch) (Y-R) 34-6.0 b
il
,NEUTRALIZER
Based on filtration of 60 ml. of oil. Color of batch.
Table II.
a
STORAGE
Fancy Tallow B 2.00
Fancy Tallow 2.00
1,OO
45-4.5
12-1.6
35-4.1
C
Prime Tallow
Based on filtration of 50 nil. of fat. Color of batch.
scale, say of 150-pound capacity instead of 300 grams, as employed in the laboratory procedure, and a unit patterned after the design of a commercial bleaching tank, including with it a filter press, tends to overcome these two handicaps. Design of the fatty oil pilot plant was based primarily on a bleaching unit that wap a miniature commercial plant unit. A batch operation was employed rather than a continuous one because of the preponderance of the former type in industry. The pilot plant included, besides the basic bleaching unit, units for the thiee other operations that are employed in the refining of fatty oils-neutralization, hydrogenation, and deodorization. These JTere also miniature commercial units, in design as well as in function, Bleaching, which follows neutralization in the refining sequence, affects hydrogenation and deodorization, neutralization affects all three, and all four operations affect color; consequently, the four operations are interrelated (8, 9). Further, improvements effected in bleaching often should be evaluated in terms of the oil that has been subjected to all four refining operations, not merely in terms of the bleached oil. Hence a complete refining layout was constructed, capable of carrying out the respective operations in the exact manner and in the
November 1954
Figure 2.
NEUTRALIZE0 OIL STOWGE
Arrangement of Pilot Plant Units
oil were located behind the converter and deodorizer, 1 espectively. The various filter presses were installed near each of their respective operating units-Le., the bleach press was in front of the bleacher, the converter or catalyst press in front of the converter, etc. Oil lines connecting the various units were so set up that, if desired, by-passing of any operation or operations was possible. Facilities available to the pilot plant were steam, compressed air, water, electricity, nitrogen, carbon dioxide, and hydrogen. Standard commercial tanks of the gases were connected to l i d inch manifold lines for conveving the gases to the various units. The three-stage steam ejector providing vacuum for the bleacher, converter, and deodorizer was located outside of the pilot plant building. With the exception of the crude oil aluminum storage tank, all the tanks were constructed of l/a-inch plain steel with selded seams made to withstand 100 pounds per square inch pressure, and ivere cylindrical with coned bottoms. The three supporting legs on each tank, and also the coned bottom, m r e nelded to the cylindrical section of the tank. Each tank except the neutralized oil and deodorized oil storage tanks was insulated over both cylindrical and cone bottom areas. Owing to the higher temperature used in the deodorizer, the top of that tank also was insulated. The insulation consisted of a chicken wire support directly over the metal, covered by a 1-inch layer of 85% magnesia pipe insulating material, and aluminum paint. The plant was laid out so that an operator could reach with comparative ease the operating tanks and also the connecting pipelines, control panel, valves, and filter presses from the open space represented by the middle of the U (Figure 3). If necessary or desired, more than one operation could be conducted simultaneously. Neutralizer. The 150-pound capacity neutralizer has the following dimensions, in inches: Inside diameter Outside diameter Height of cylindrical section Height of coned bottom Over-all height, to top of cylindrical section
TNDUSTRIAL AND ENGINEERING CHEMISTRY
1.51'2
18 24 9
60 2273
ENGINEERING, DESIGN, AND PROCESS DEVELOPMENT
Figure
3. Pilot Plant
Heating Medium: Eight loops of butt, n-rltleil eliiral coils (I/% inch cxt,ra strong) arc set in lower portion of cj-lindrical section, clearing tank n-all by 1 inch. Inlet is 12 inches from top, and out,let is in coned bottom. Coils itre also used for cooling wit'h m-ater. Temperature Measurement: Iron-const,ant,an thcrmorouple lead extends i inches into taiilr. Temperature is recorded on control panel. Agitator: A three-bladed propeller on a 6/8-inch shaft extends to bottom of cone, clearing Tall by 1 inch. Blades are 6 X 1 X inch and are pitched at, 45' angle to throw charge of oil up\yard. Shaft is braced with bar across top of tank. Belt on 6-inch horizontal pulley a t top of shaft connects with 2-inch pulley on bleacher motor. Speed of Agitation: T'ariable speed motor, drives agitator a t 75 to 150 r.p.m. Top: Neutralizer is open at top except for bar bracing the agitat,or shaft. Loose fitting aluminum sheet, covers can be used if desired, one on either side of bar. Each of three steel supporting legs is rightrangled. The legs are 2 X 36 X "18 inches. A 2 x 2 X "'8 inch piece is welded a t right, angles to one side of leg a t bottom. Oil Inlet: Inlet line ( 1 / 2 inch) enters tank 3 inches from top. Oil Outlet: A 1-inch line is provided a t bottom of cone with a gate valve attached for removal of soap stock and water washings. The oil is conveyed to neutralized tank storage in a '/%-inch line from a T-connection between the bott,om of the cone and the gate valve. Bleacher. Capacity, inside diameter, outside diameter, height of cylindrical section, height of cone bottom, over-all height, heating medium, temperahre measurement, and speed of agitation, legs, and oil inlet of bleacher are same as neutralizer (Figure 4). Agitator: The bleacher agitator is t,he same as neutralizer agitator except that the agit,ator motor is bolted to a platform which is welded to t'op of tank. Belt on 6-inch agitator shaft horizontal pulley connects shaft with 2-inch horizontal pulley on agitator motor. Top: A 1-inch thick convex flanged steel plate 6 inches higher than top of cylindrical section of tank a t center, and bolted to tank, f o r m a cover. Connections in top are for agitator shaft housing, vacuum gage, slurry cap, and nit,rogen-vacuum line. 2274
Oil Outlet: A '/*-inch line from bottom of cone provides oil outlet. Converter. Capacity, inside diamet,er, outside diameter, height of cylindrical section, height of cone, over-all height, heating medium, temperature measurements, legs, and oil inlet of converter are same as neutralizer (Figure 5 ) . Agitator: Two Turho 6-inch aerator impellers are same type used for Lzrge commorcia1 units. Each impeller discharges it high velocity stream radially and horizontally through st,at,ionarydeflecting blade rings where thct mixture of gas and liquid is deflected dontinard in the tank so as t o obtain a scrubbing action between gas and liquid as well as give thc mist,ure a long gas pat,h. Owing to :his act.iiin, an increased detention of the gas is obtained m d interface conditions accelerate gav ahsoq)tion. At the same time, the high pumping c of tho impeller ensures uniform distribution of t,lie catalyst and high heat) esciiango r:rtrs t,hrough the heating and cooling coils. Al)ove the upper impeller is a light gage shwt steel suc%ion sleeve 2 3 / r inches in diittneter and 5 inches long. This is a cylinder tha,t allom any unabsorbed hydrogen accumulating a t the surface of the oil to be inducted by the upper iinpeller and rescrulibed throughout the oil. The driviiig assembly consists of a Texrope drive; one of the heavep is adjustable to allow speeds on the vertical shaft of 56.5 to 400 r.1J.m. Vertical pulleys are used and the mot,or is bolted to a platform welded to the top of the tank. Top: A flat flanged steel plate (17/16 inchj is Iiolted to t,he tank. Connections in top are for agit,ator stuffing box, pressure gage, cat,alyst cap, and nitrogen-vacuum line. Oil Outlet: A 1/2-inch line a t bottom of cone serve$ :LS oil out'let. Hydrogen Inlet: A l/4-incli line feeds to underside of Ion-er imp(,ller welded in cone. Rate of gas flow is recorded by a rot:tmeter on control panel. Deodorizer. Capacity, inside diameter, o u t d c diameter, height of cone, temperature measurement>and legs of deodorizer are same as neutralizer. Height of cylindrical section, inches Over-all height, to top of cylindrical section, inchea
40 76
Heating Medium: Steam coils are same as neurralizcr coils hut they have 10 loops. Two 2000-wat8tpipe fitting iinmctrsion heaters located near center of cylindrical section augment heating. Temperature Control: Temperature is controlled by thoi~moregulator on control panel. Live Steam Inlet: A '/pinch steam line welded to coned bottom leads to a cross-shaped spider perforated with l./ldnch holes. Top: Convex flanged top is same as bleacher top excopt that it is insulated. Connections in top are for 3-inch vacuum liiic to steam ejector, 3-inch sight glass, vacuum gage, and manonwter. Steam Ejector: A three-stage noncondensing Ingersoll-Rand ejector consists of No. 10 first &age, S o . 10 second stag(,, and S o . 325 third stage ejectors. Unit is on outside of building Iyith dixharge to a drain trap. Oil Inlet: A '/z-inch line 18 inches from top of tank provides oil inlet. Oil Outlet: A l/Z-inch line a t bottom of cone is oil outlet. Control Panel. Square U Co. 36 X 77 inch control panel is used. It is equipped wit,h a Brown indicating potent,ioineter Model 153304-XX-P6, 0' to 600' I?., for registering temperature recordings on neutralizer, bleacher, converter, and deodorizer, and the deodorizer thermoregulator. Other opcrating unit
INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
Vol. 46, No. 11
PILOT PLANTS Table 111.
Laboratory Bleaching Tests of Grade 40 Adsorbent
(Neutralized extracted soybean oil) Procedure : Oil (300 9.) wm bleached a t 190' F. and 241 r.p.m. mechanical agitation. A vacuum of 29.2 inches was pulled on oil and adsorbent a t 8 6 O F. Temperature of filtration ~1'a.s 162-185' F. Time t o reach temperature of bleaching was 5-6.5 rnin., time at temperature of bleaching 5 rnin., and time of filtration 10-13 min. Vacuum was broken with nitrogen. Color of Oil, Lovibond (51/4 inch) (Y-R)" Grade 4 Grade 40 25-6.3 20-4.9 20-3.6 10-2.6 12-2.5 7-1.9 4 8-2.0 7-1.8 Unbleached 35-8.4 35-8.4 Bleaching efficiency of Grade 40 (Grade 4 as 100% a t 2.5R) = 143% a Based on filtration of approx. 50 ml. of oil. .4dsorbmt Dosage, 70 1 2 3
temperatures are regulated manually. A Fischer and Portcr rotameter, 160 cubic feet per minute, records rate of hydrogen gas flon . There also is a switch panel for the agitator motor servicing the neutrali~erand bleacher and the motor on the converter agitator. The switch panel also includes the switches for the pump motor and the immersiori heaters on the deodorizer. Storage Tanks. The crude oil storage tank has a capacity of 500 pounds. It is cylindrical with a coned bottom, and is constructed of '/c-inch aluminum. Outside diameter is 24 inches, height of cylindrical sections 36 inches, and height of coned bottom 10 inches. A l/&nch steam coil circles the entire cylindrical section. This and the coned bottom are covered with the usual 1-inch layer of insulation. Over-all height is 61 inches. Top is open but two loose aluminum sheet covers are used when necessary. Outlet is a '/Z-inch line a t bottom of cone. Tank is supported by three 25-inch right-angled legs of same width and thickness as those on other units. The neutralized and deodorized oil storage tanks are the same size as the neutralizer, ex-
cept that the legs are 28 inches in length. There is no agit!ator but &he tanks are insulated on side and bottom, and have same size steam coil as the neutralher. Oil inlet is a '/yinch line extending to bottom of tank. Oil outlet is a l/z-inch line a t bottom of cone. Pumps. The charge pump, bleach pump, and deodorizer pump all are centrifugals. Filter Presses. Bleach, converter, and deodorizer presses are 7-inch closed discharge plate and frame type presses. They are provided with 1/2-inch oil steam line a t one bottom corner and 1/2-inch outlet at opposite upper corner. Presses are elevated on metal frames to facilitate dropping spent cake into pan and cleaning press. NITROGEN -VACUUM
MOTOR P L A T FORM WELDED TO TOP
/VAWM
GAGE
ADSORBENT CAP
1
/I l7
BLADED PADDLE AGITATOR
OIL 0 U T u T - W
Table
IV.
Plant Bleaching Tests of Grade 40 Adsorbent
Figure 4.
Bleacher
(Seutraliaed extracted soybean oil) Procedure: Oil was bleached a t 192-193O F., using 76 r p.m. agitation late. Charge of oil in the two runs was 21.100 a n d 23,750 lb. A vacuum of 27 inches was pulled on oil and adsorbent a t 80-84' F. Temperature of filtration was 176-192' F. a t t h e s t a r t a n d 196' F. a t the finish. Time to reach temperature of bleaching was 51-62 min , time a t temperature of bleaching was 20-24 min., time of recirculation was 4--6 min., and of filtration 47-60 min. Vacuum was broken with air. Grade 4 Grade 40 Unbleached Dosage of adsorbent,, % 1.5 1.0 Free f a t t y acid ?% 0.028 0.035 0 .'030 Color Lovibonh (5'/rinc1i)(Y-Rla 10-2.1 10-2.0 25-6.7 Peroxide, meq./kg. .. .. 0.5 A . O . M . stability, hr. .. .. 9 a Color of batch.
Table V. Pilot Plant Bleaching Tests of Grade 40 Adsorbent (Neutralized extracted soybean oil) Procedure: Oil (150 Ib.) was bleached a t 188-191O F using 80 r.p.m. a-itation rate. A vacuum of 24.4 inches was pulled on oil and adsorbent a"t 65-72O F. Temperature of filtration was 176--180° F. a t s t a r t and 171-172' F. a t finish. Time to reach temperature of bleaching was 49-58 min. time a t temperature of bleaching 20-22 rnin., time of recirculation 5-10 mi;., and of filtration 28-49 min. Vacuum was broken with air. Grade 4 Dosage of adsorbent, % Analysis5 Free f a t t y acid, % Color, Lovihond (5x14 inch)
(Y-R)
Peroxide, meq./kg. A.O.M. stability. hr. a Analysis of batoh.
November 1954
Grade 40
Unbleached
1.5
1.5
1.0
..
0.024
0.050
0,045
0,030
10-2.3 0.5
9-1.9 0.0 9
10-2.4 0.5 8
25-6.7 0.5 9
11
inch, gas lines Lines. Oil, water, air, and steam lines are are '/a inch. Oil lines are provided with steam connections for cleaning. Sampling. Open tanks are sampled from aurface of oil; hleacher, converter, and deodorizer are sampled from '/*-inch drawoff on oil outlet line. Arrangement and Construction of Units Ensure Flexible Operation
The crude oil was transferred lvith a hand pump from the drum in which it was received into the crude oil storage tank. If the crude fatty oil was a solid a t room temperature, such as a tallow or lard, it was obtained in the melted state and pumped immediately into the storage tank to avoid remelting which reduces the susceptibilitv of the fat to bleaching. When liquid fatty oils were treated, the oil was pumped at room teniperature to the neutralizer from the crude oil storage tank. From this point the oil was treated in the various operations under the desired conditions in the same manner as in the commercial plant. The charge of oil was measured by a calihiatcd gage in the crude oil storage tank. Before starting a run all lines were thoroughly steamed out, then blown with air to avoid contamination with the previous fatty oil treated, which might be in an advanced state of oxidation. All tanks were thoroughly cleaned or flushed out with fresh oil.
INDUSTRIAL AND ENGINEERING CHEMISTRY
2275
ENGINEERING, DESIGN, AND PROCESS DEVELOPMENT
CTlON
DUREX
TlONAW DEFLECTG BLAW RINGS
IMPELLERS
Figure 5.
Table VI.
SLEEVE
Converter
Pilot Plant Color Reversion Tests
(Hard t o bleach. off-quality liydianlic neutralized cottonseed oil: Analysis : Tsee fatty acid, Fc 0.12 Color, Loribond (31,i inch) ( T - R j 70-8.9 10 Peroside. ineq ,?q. 107 Iodine Xuniber 300 Soap caz sodiuin oleate), i,.p.m
BI.EACII~SG Procedure: Size of b a t c h agitation rate. et?.. same as in Tablr V. I n atmospheric runs, adsqlbent u-as added at lGOO r., temperature of bleaching was 220227O F, r i m e t o reach temperature of bleaching was 47-60 min., and time a t tempesature of bleaching was 15 min. I n vacuum runs, adsorbent was added a t 85' F., wid teinperature of bleaching was 185-188° F. Times t o reach temperature of bleaching and a t temperature oi bleaching were 40-42 and 15 min , respectively. Vacuum was 28.2-28.7 inches and was broken with nitrogen. Run 1 Run 2 Run 3 Run4 Run 3 Type of bleaching Arm. Itm. Vacuum Vacuum Atm. Adsorbent Activated S a t u r a l Activated Natural .Ictivated Dosage of adsorbent. 70 1.8 6.0 1.8 0.0 1.8 Bleached color, L0T-ibond ( 5 1 i r inch) (Y-R) 30-4.0 3:-5.0 23-3.3 30-3.7 33-4.4 HYDROGEXATIOX Catalyst dosage (as X i ) , B Diatomaceous earth dosage, R Agitation rate. r.p.ni. Temperature of hydrogenation, O F. Temperature of filtration. F. Vacuum applied to 225" F. (av.), inches Hydrogen feed rate (niax ) , cu ft./hr. Hydrogen pressure (niax.), Ib./sq. inch Run 1 R u n 2 R u n 3 Hydrogenated oil rolor. Lo\-ibond (5l/a inch) jl--R) 30-4.4 3:-j 3 23-3.2
0.2 0 25 EO5
320-328 188-210 28.2-29.0 :0-55 33-40 Rim 4 Kim 5 23-3.3
35-4 0
DEODORIZ.4TIOY Temperature, 1'. Time a t deodorization temp., hr. Pressure (av.), m m . H g Steam rate, Ib /hr.
8-
Free fatty acid, Color, Lovibond io'/'< inch)
O'-R)
Run 1 0.07
Run2 0.06
395-410 71/2-8 4-18a 4-5
Run 3 0.00
Run 4 0.03
Run5 0.14
60-5.2 00-7.0 30-3.5 30-3.0 105-10.4 Peroxide, meq./kg. 3 FJ 1 5 0 a Pressure in Run 5 x a s 18 mm. Hg because of small amount of air intentionally introduced into deodorizer with steam: pressures in Runs 1-4 meIe 4-6 nim. Hg.
2276
When operations were begun in the neutralizer, agitation was started, heat applied in the coils, caustic solution added, and foot,s settled out and drawn off a t t'he outlet in the bot,toin of the tank. If water washing of the oil was conducted after neutralieing, the v-ashings also were removed from the bottom outlet. Drying of the oil was carried out in the bleacher under vacuum. Prior to vacuum bleaching tmheoil was conveyed from the neut,ralizer by pulling a vacuum on the bleacher. At the desired oil temperature, t'he adsorbent,, dry or as a sl~irry,was added to the oil tthrough t8headsorbent cap. Agitation was begun arid heat was applied. Kit'rogen was used to break the vacuum at the end of the operation, and the charge of oil was recirculated through the bleach press until the oil from the b t t e r was clear. Water \vas circulated through the coils if cooling was employed. Atmospheric bleaching was carried out in the neutralizer and the charge of oil and adsorbent m r e pumped through the bleiwh press after the operation described. Hydrogenattion was usually preceded by precoating the converter press with diatomaceous earth to ensure retent,ion of the finely divided nickel catalyst' after the operation was completed. A small batch of the oil t,o be hydrogenatcd was added to the convert,er containing the necessary amount of diatomaceous earth. This oil was circulated through the conve1,ter press with nitrogcri pressure. The batch of oil to be hydrogenated was transferred to the converter by pulling a vacuum on the 1at.ter. Catalyst, diat,omaceous earth carrier, and adsorbent if desired, were introduced into the charge through the cap a t the top of the tank in the form of a slurry with the oil to be hydrogenat,ed. Vacuum was maintained and heat was applied in the coils with the charge under agitat,ion until the temperature was approximately 225" F. At this stage the vacuum was shut off and electrolytic hydrogen was metered in a t the bottom of the tank. The desired saturation pressure was obtained by regulating the rate of hydrogen input and the temperature was increased to the desired level. When samples of oil from the tank indicat,ed the proper iodine number had been attained, t,he hydrogen was shut off and the batch was cooled by circulating vater through the coils and filt'ered a t the desired temperature through the precoated converter press by applying nitrogen pressure. The deodorizer normally was preheated by turning on the steam in the coils for several hours prior to introduction of the oil. After the oil had been charged to the t,ank by pulling a vacuum, the immersion heaters were turned on to supplement the steam coils, and live steam was int'roduced from the inlet in the cone bottom. The rate of steam usually m s increased to the desired rate and iyas balanced with the heat imparted by the coils and immersion heaters. Samples of oil were wit,hdrarvn throughout the run to determine free fatty acid, color, and flavor or odor. When deodorization -as complete, the oil was cooled by circulating water through the coils, the vacuum was broken by nitrogen, and the oil was discharged through the deodorizer "poliPhing" press under nit,rogen pressure. Filt,rat,ionTyas carried out a t t8hedesired temperature and pressure in the various presses. The presses employed the standard types of filtering media used in the commercial plant-cotton duck vith or without filter paper, etc.-and aft,er filtration vyas ended the bleach press was blown TTith steam, air, or both, in the manner employed in large plant,s. When solid fats iverc t,reated, they x-ere transferred to the various units a t a temperature slight,ly above thgir melting points instead of a t room temperature; otherwise the procedure was the same. Examples of Projects lllustrate Purposes of Pilot Plant Investigations
Development of Bleaching Adsorbent. A new activated hlcaching adsorbent called Neutrol Grade 40 adsorbent, or Grade 10, was developed in the Research Department of the Filtrol Coip.
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 46, No. 11
PILOT PLANTS type of oil submitted by the refiner. Bleach tests were made in the atmosphere and under vacuum, using a natural and an activated clay adsorbent on each type of run. The bleached oil was hy(Tallows dry rendered under vacuum) Fancy Tallow Special Tallow drogenated and deodorized. I n addition, one atmospheric run was made bleaching the oil with Analysis" Free f a t t y acid, 70 2.60 9.72 the activat,ed adsorbent, hydrogenating, and deMoisture, % 0.98 0.34 Color (F.A.C.) 9 19 odorizing with a small amount of air introduced Procedure: into the deodorizer with the steam. Operating conditions of atmospheric runs of Table V I The results, which are given in Table VI, shoxed FANCY TALLOW Run 1 Run2 Run 3 Run4 Run5 Run6 that the color reversion effect occurred with both Adsorbent d c t i v a t e d Activated Activated Activated Natural Natural the and the activated adsorbent. Water added, 70 0 1 0 1 0 1 Contact of the oil with air aggravated the reverDosage of adsorbent, 70 2 2 4 4 4 4 sion with each adsorbent during bleaching, as demBleached color, Lovibond ( 5 l / a inch) (Y-R) 35-5'0 35-3'9 21-2.2 14-1'9 28-4'3 24-4'4 onstrated by the results from atmospheric and SPECIAL TALLOW vacuum bleaching and the incorporation of air in Run 1 Run2 Run3 Run4 Run5 Run6 the deodorizer. The problem, therefore, appeared iictivated Activated Activated Activated Natural Natural Adsorbent to be one involving oxidation rather than one attribWater added, % 0 1 0 1 0 1 Dosage of adsorbent, % 3 3 5 5 5 5 utable to a certain type of absorbent. Bleached color, Lovibond Development of Bleaching Technique. Labora(51/4 inch) (Y-R) 43-6.0 28-3.6 24-2.8 24-2.3 40-4.6 40-4.9 tory tests indicated that when tallow is atmosAfter clarification, just prior t o bleaching. pherically bleached with an activated adsorbent, the resulting color is lightened if water is added a t the same t,ime the adsorbent is introduced. This product possessed a considerably higher adsorptive If such a procedure were practical and the laboratory results capacity or bleaching pover than Special Filtrol Grade 4 adsorbwere realized in the plant, its adoption would mean a substantial ent, or Grade 4-an old established product. Laboratory resavings to the tallow refiner in cost of adsorbent and in value of sults demonstrating the comparative bleaching power of the two oil lost in the filter press cake. adsorbents are presented in Table 111. These tests were conWork was undertaken in the pilot plant to substantiate the ducted under vacuum in a small stainless steel vessel equipped laboratory findings. Lots of vacuum, dry rendered fancy and with the type of agitator specificd for use in American Oil Chemspecial tallow were dried and clarified by mixing 0.5% diatomaists' Societ'y Method Cc8b-52. ceous earth \?ith the fat in the bleacher a t 160" F. under 7 mm. of At a color level of 2.5 red Lovibond color on a 5l/d-inch column mercury pressure for 30 minutes and filtering. The tvr-o fat,s were bleached in the neutralizer open tank under the conditions a bleaching power of 143% ivas indicated for Gra,de 40, compared to Grade 4 as 100%. This represented a subst'antial improveoutlined in Table IrII with different percentages of activated and natural clap adsorbents. Each run was repeat,ed except ment over Grade 4; however, it was necessary to verify the quality of Grade 40 on a larger scale. s with the adsorbent. that 1% of water w ~ added A commercial plant, operating its bleaching equipment under The tests confirmed that the bleached color of the fat was vacuum, made two runs on neutralized extracted soybean oil, markedly lower when the water was used and the activated clay comparing 1.0% of Grade 40 with 1.5% of Grade 4. These runs adsorbent was employed. S o improvement was noted with the were made on oil from the same storage tank on succeeding days zatural clay adsorbent. under as identical operating conditions as it was possible to obtain. Results are given in Table IV. literature Cited Some of the same oil x a s processed in the pilot plant, using (1) Bailey, A. E., "Industrial Oil and Fat Products," 2nd ed., Interadsorbents from the same manufacturing lots used in the science, New York, 1951. mercial plant runs. The pilot results &represented in Table Fr. ( 2 ) Baldwin, A . R., J . A ~oil, Chemists' sot., 26, 610-14 (1949). In brief, both commercial and pilot plant results verified the (3) Freyer, E., Oil & Soap, 22, 153-6 (1945). (4) Jamieson, G. S., "Vegetable Fats and Oils," 2nd ed.. Reinhold, laborstory indication that Grade 40 was superior in decolorizing New York, 1943. power to Grade 4 at commercial color levels. The pilot plant (5) King, A. E., Roschen, H. L., and Irwin, W.H., OiZ & Soap, 10, colors also were close to those obtained in the larger unit, al204-7 ( 1 9 3 3 ) . though slightly inferior despit'e a higher vacuum. ( 6 ) King, R. R., Pack, S. E., and Wharton, F. W. (to Slrs. Tucker's Foods, Inc.), U. S. Patent 2,428,082 (Sept. 30, 1 9 4 7 ) . Solution of Commercial Bleaching Problem. A refiner re(7) King, R.R..and Wharton, F. rTr., J . Am. oil Chemists' S0C.s 26, ported that afteran off-quality cottonseed oil FT-vLbs bleached with Table
VII.
Pilot Plant Tests-Effectiveness in Bleaching Tallow
of Added W a t e r
Q
activated clay adsorbents the color reverted or increased after hydrogenation and deodorization. IIe stated that this failed to occur when natural clay adsorbent's were employed. Pilot plant runs were conducted on a neutralized lot of t,his
November 1954
389-92 ( 1 9 4 9 ) .
,
( 8 ) I b i d , , pp, 201-07 ( 1 9 4 9 ) . (9) Pritchett, W. C., Taylor,
W.G . , m d Carroll, D
225-27 ( 1 9 4 7 ) . RECEIVED
for review July 8, 1954.
INDUSTRIAL AND ENGINEERING CHEMISTRY
ACCEPTED August 31, 1954.
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