Chemical & Metallurgical Engineering, Vol. 40, No. 12

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CHEMICAL

C- M E T A L L U R G I C A L

ENGINEERING

v o l u m e 4 0 Es t a b l is h e d 1902 n u m b e r 12

M C G R A W -H ILL PUBLISHING COMPANy, INC.

S. D. KIRKPATRICK, Editor

DECEMBER, 1933

HOW CONGRESS CAN HELP INDUSTRY

C O N G R E S S will soon convene, confronted w ith m any problems, all of them difficult and many of concern for process industries. Some of these problems are wholly insoluble by legis

lation. B ut that will not prevent Congressional debate, mad proposals, perhaps even some absurd enactments. O n the whole, however, F ederal legislation is m ore needed than usual.

Being by nature hopeful, we do not on this occasion, at least, endorse the cynic’s common recom m endation: “ Oh, let’s repeal Congress.”

Legislation affecting industry will take on three separate aspects. I t will deal with fiscal (and ta x ) m atters; it will concern the regula

tion of indu stry ; it will attem pt fu rth e r relief of unemployment. All will be im portant, maybe beneficial if settled in a statesm anlike m anner, but sure to be disturbing while dem

agogic debate rages. T here is little chance th at we can wholly escape the demagogue, though all sincerely hope to be spared the enactment of his theories into other new and dangerous laws.

T a x adjustm ents proposed are already in large m easure announced. T hey follow logic

ally the lines expected a fte r the Senate in

vestigations; B ut they do not yet wholly reflect the m ore radical views on new sources of needed revenue. O ne m ust here remember that liquor taxes, large though they seem in prospect, will yield little m ore than replace

ment revenue, offsetting other taxes autom atic

ally ended by Repeal. Industry is likely to be the targ et of oratory, if not worse, when attem pt is m ade to balance the budgets, norm al and extraordinary. New business taxes seem inevitable.

Sound money is a sure topic fo r debate.

Chemical industry is concerned in this mainly

as it affects public confidence and psychology of buyers— directly those who w ant new pro

ducers’ goods and new capital investment, sec

ondarily those who represent the ultim ate user of consum ers’ goods. B ut more important, and really helpful, will be the revision of the Securities A ct which has wholly protected in

vestors, a desirable result, by a wholly bad method, the destruction of both will and oppor

tunity of industry to borrow new capital. Con

gress should act here quickly and helpfully.

M any variations of form ula will undoubtedly be proposed fo r the regulatory agencies, N.R.A.

and A.A.A . T he President may have to still the howling by throw ing to the wolves some of the theories previously attempted. Late developments suggest the hope that coopera

tion with industry may be made a real part and less emphasis be given to bureaucratic regula

tion and censorship. However, it seems cer

tain that the P resident’s influence will continue to be exerted in support of the more socialistic concept that uplift of the underprivileged is a prim e duty of government.

B efore Jan u ary it will be well for thoughtful executives and engineers of process industries to exert their personal influence on all these m atters. They can do so best through senators and congressmen by asking less for specific measures and m ore fo r the general principles.

Above all, it is well to ask these legislators to re tu rn to their tasks, seeking conservative progress, neither greater speed forw ard nor wholly a tu rn in g back to old conventional ways.

Needs change with times, but law should not outrun public ability to understand and to conform.

A nd with all Chem. & M et. wishes each reader A M erry Christmas.

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DISTILLING •

BEVERAGES F R O M G R A IN

By GUSTAVE T. REICH

Pennsylvania S u g a r Co., Philadelphia, Pa.

W

I T H R E P E A L of the Eighteenth A m endm ent a fa it accompli, m any people will consider it a propitious time to enter or re-enter the m anufac

tu re of alcohol in the form of whiskey, gin or spirits.

Considerable strides have been made along technical lines since 1918 and under the present business conditions only the m anufacturer who is able to erect a well designed plant, applying on a large production scale continuous beer and rectifying stills and other efficient chemical engineering equipment and having ferm entation and other process steps under strict chemical control can hope to survive the keen competition ahead.

Chiefly g rain will be used fo r the m anufacture of bev

erage alcohol, but there are, of course, several other proc

esses by which alcohol can be produced economically.

These belong to two groups, one is by ferm entation and the other is by synthesis. In the first group, the raw m a

terials are grain, fruit, molasses and cellulosic m aterials, while the second group embraces ethylene, natural or coke-oven gas, calcium carbide and carbon monoxide.

T he present article will deal mainly w ith the m anufacture of alcohol from grain but Fig. 2, shows the general process steps with various raw m aterials. A second article discussing alcohol from molasses will appear in a later issue.

B efore Prohibition ethyl alcohol produced from agri

cultural products was made chiefly from m alt, wheat, rye, barley, corn, and oats. (S ee Tables I, II , and I I I .) T he theoretical and practical yields of alcohol from these raw m aterials are as follow s:

Ferm ent Ferm ent Alcohol

Lb. able sugar able sugar Absolute ale. practically per bu. and starch &. starch per theoretically proof gals.

(Per Cent) lb. per bu. lb. per bu. per bu.

Barley 48 65.5 31.4 17.75 4.50

M alt 34 60.6 20.6 11.57 3.00

W heat 60 64.8 38.9 22.02 5.90

MaUe(Indian corn)

Eye 56 66.0 36.9 20.94 5.00

56 59.3 33.2 18.75 4.75

T he first process step in the m anufacture of alcohol . from grain is the milling, which consists of conveying, cleaning and grinding. T h e distiller has considerable flexibility in choosing the right equipm ent depending on the capital and floor space available and quality of prod

uct desired.

T he grain is received, usually by rail, in cars contain

ing approxim ately 600 bu. I t is conveyed to a hopper scale and from there it passes first through a separator before it is stored in iron, wood, or reinforced concrete silos. In this separator most of the d irt and dust is car

ried away into a dust collector. T h e partially cleaned grain is stored in silos and from there is conveyed to the milling departm ent. All the grain entering the mill is weighed and records are kept according to Governm ent regulations. T he grain is cleaned a second tim e and be

fore being ground to the desired fineness, it passes over a magnetic separator fo r the removal of metallic sub

stances which m ight in ju re the mills.

W hen constructing a distillery, careful study should be made of the grinding equipm ent as we have three types of mills from which to choose, viz., the extensively used roller mill, the attrition mill and the ham m er mill.

Each one has its defects as well as its good points. W hen it comes to the power requirem ent, the roller mill is by fa r the most efficient. B ut in addition to pow er require

m ent consideration should be given to the am ount of fine material present in the ground m aterial as well as floor space available.

T he old type of distillery w ith its large and w asteful layout and floor space, contrasts w ith the compactness noted in distilleries under construction at present. In some instances today the milling equipm ent is being erected in the same building w ith the m ashing and fe r

menting tubs. Because of smaller investm ent it some

times pays to be quite liberal w ith mechanical conveyors rather than to build a high gravity-flow m illing plant.

618 C hem ical & M etallurgical E n g in e e rin g — V ol.40,N o.l2

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Fermentable sugar (M a/ł or acid

hydrolysis)

Fermentation Amylic process

Fermentation with yeast

Distillation

SY N T H ESIS

E t h y k n e

P g w g M ? C a ię iC ir carbiV «; '•

A íirfy lc íw

1 1

Ö B l f ; A c r n W w c

ł ł

H y f o l j w Hycfragensrfiort

ETHYL ALCOHOL

of the hour, the mash is prepared for the souring by inoculating it with lactic acid bacteria. I t requires 24 to 36 hours to obtain an acidity of 1.8 deg. to 2.1 deg. normal, while a tem perature of above 120 deg. F . is maintained. W hen the proper degree of acidity has been reached, rakes are started and the tem perature raised to 170 deg. F. and held for about half an hour. P a rt of the hot mash is re

moved to be used as a starter for the next batch while the rem ainder is rapidly cooled, by passing cold w ater through the heating coils, to a tem perature of 70 to 75 deg. F . and is inoculated with the pure culture yeast.

T he pure culture yeast may be propagated either in suitably de

signed machines such as M agne’s, or if carefully attended in wooden or iron yeast tubs. W hen the density of the first mash has dropped to 5 to 6 deg. Balling, it is transferred to a larger yeast tub stocked with a steril

ized malt donna. A fte r several hours w orking it is used in the ferm enters.

Its density is from 7 to 9 deg. Ball

ing and acidity, 0.14-0.16 normal.

F ig . 1— R e c tify in g c o lu m n s in a m o d e r n d is tille ry

A s there are several varieties of yeast, it is im portant to choose a type which is capable of producing the largest quantity of alcohol under desired conditions. W e have high and low tem perature yeasts, some fo r sour, sweet o r hops mashes, while others are capable of being active in high density mashes. R egardless of which type of yeast is selected, it is of a prim e im portance to sta rt only w ith pure culture yeast, which is used exclusively in the molasses distilleries in this country. B efore Prohibition, the typical distiller considered the preparation of his yeast a great secret and attributed every conceivable re

sult to the special method he used in its cultivation. T he progressive distiller will sta rt w ith a pure culture yeast and propagate it in the properly designed p ure culture apparatus and acclimate it to the special type of m ash he desires to ferm ent.

T he yeast m ash containing half rye meal and half malt is gelatinized and saccharified at a tem perature of from 40 to 158 deg. F . F irs t the rye is ru n into hot w ater slowly, stirrin g it vigorously and then the m alt is added, w atching carefully meanwhile, th at the tem perature shall not drop below 122 deg. F . W hile slowly stirring the mash is heated to 143 to 145 deg. F . w ithin one hour and the sides and rakes are washed down w ith a little hot w ater. T he mash stands at this tem perature fo r approxi

mately one hour to complete the saccharification. A density of 23 to 25 deg. Balling is desirable. A t the end

In the m anufacture of grain alcohol, it is im portant to know w hether the product is to be converted into whiskey or spirits ; also the size of the distillery and raw m aterials used. Small distilleries will undoubtedly be equipped w ith open mash tubs while larger distilleries may operate pressure cookers exclusively. H ow ever open

F ig . 2 — S o u rc e s a n d p ro c e sse s f o r e th y l a lc o h o l p ro d u c tio n

D ecem ber, 1933 — C hem ical & M etallurgical E ngineering 619

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Oats (Bu.) 11,502 6,563 5,654 9,807

T a b le I— Q u a n titie s o f G ra in U sed in th e P r o d u c tio n o f A lc o h o l a n d O th e r D is tille d S p irits

Others M aterials

(Bu.) 8,248 50,576 64,896 68,822 172,039

51,760 4,097,905 2,691,070 26,621 123,624 19,144 2,478 1,675 lbs. of corn lbs of hydrol acids ethyl alcohol.

Malt(Bu.) 3,704,740 4,075,991 3,938,715 4,480,588 1,689,677 215,072 679,697 1,059,985 641,032 385,238 646,574 505,613

W heat (Bu.)

10,316 25,505 10,582 3.373

11,990 3,311,441

Barley (Bu.) 2,733 1.943 2,072 148

21,320 Fiscal

Years 1910 1912 1914 1916 1918 1920 1922 1924 1926 1928 1930 19322

(1) 1931— 6,385,365 bu. (2) Year 1932 figures include 21 19,865,419 lbs. of wheat, 150,619 lbs. of malt, and 20,103,526 used a t chemical plants producing butyl alcohol, acetone, and

(Bu.) Rye 5,042,741 5,599,667 5,341,931 3,116,612 248,864 50,077 84,876 91,065 12,678 6,579

Corn (Bu.) 20,547,427 23,016,759 21,315,699 32.069,542 14,544,545 1,057,519 3,093.065 4.835,139 7,948.184 6.189,264 208,209(1) 9,966,336 217,934 4,848,133

mash tubs are sometimes p referred in distilleries m ash

ing 1,000 to 2,000 bu. per day. H ere we have two d if

ferent opinions to consider: one claims that in order to make a good grade of whiskey open mash tubs should be used while others claim to get ju st as good results with pressure cookers. T h at a much better yield of alcohol is obtained from a vacuum cooker can not be doubted, but as to the quality of the final product, a great deal depends on the mode of cooking, the proportion of ingredients, the yeast, and the method of ferm entation and still con

struction.

Cooking and m ashing generally refer to the series of process steps in which the starch cells are ruptured to produce a perfect starch paste which through enzymatic action is converted into ferm entable sugar. T he ru pture of the starch cells depends on the fineness of the grain, time and tem perature. T he more finely ground the grain, up to the point of becoming flour, the better will be the rupture of the starch and a perfect starch paste will be produced. T he grain should be such that the recovery of the insoluble solids from the slop will be practicable w ith

out im pairing the yield of alcohol. A nother advantage of finely ground grain is that the quantity of malt re

quired for hydrolyzing purposes can be reduced.

In this country m alting is not carried out in the dis

tilleries since m alt is purchased from regular m alting

plants. W hile any grain can be used fo r the preparation of malt, from a practical standpoint barley is the most suitable for this purpose. A bushel of barley, which weighs 48 lb., yields 34 lb.— also a bushel— of dried malt.

T he value of m alt from a distiller’s standpoint is judged by its diastatic power and extract. T he whole m alting process aims to develop a malt of a very high diastatic value. T he diastase is an enzyme and converts the starch of the grain, during the m ashing into maltose and d ex trin, which are ferm entable and yield alcohol. In p u r

chasing malt, a diastatic value of 1,350 to 1,450 is de

manded on the L in tn er’s scale, i.e. 100 lb. of dry lrtalt will invert 1,350 to 1,450 lb. of soluble starch.

T he function of the m alt is to liquefy and saccharify the starch. Each action is influenced by the tem perature.

The diastase of the m alt has the greatest saccharifying property between 118 deg. to 130 deg. F . and its strongest liquefying power, around 158 deg. F . T he judicious use of these above tem perature passages presages a good yield of alcohol.

The flow diagram s in Fig. 4 illustrate the way a typical grain distillery carries out these processes, depending largely on the type of equipm ent used.

T he open mash tub is a cylindrical vertical copper or steel vessel with flat bottom and domed top. U sually it is provided w ith stirring rakes, copper coils, to be used for heating and cooking purposes, and vents fo r the escape of steam. Fig. 5 shows such a m ash tub.

H o t w ater in the am ount of 20 to 24 gal. per bu. of grain and a t a tem perature from 100 to 120 deg. F. is ru n into th e tub.

T h e addition of grain depends on w hether a rye mash o r corn mash is desired. I f rye is mashed, the procedure m ust be adjusted according to w hether it has a high gluten content o r the rye m alt has a low diastatic capacity and fluidity. G enerally, half of the finely ground rye and all of the m alt (approxim ately 15 to 25 per cent of the w eight of ry e) are m ixed thoroughly and slowly run into the w ater. D uring the addition of the meal the rakes are speeded up to prevent the form ation of lumps. A fte r the addition of this m ixture, the rem ainder of rye is added slowly so th at all of the meal is run in w ithin 30 to 45 minutes. A fte r

w ards the tem perature is held a t 110 deg. F . for a t least ten minutes w ith the rakes revolving slowly. T he tem perature of

F ig . 3— C o m p le te flo w sh eet a n d e q u ip m e n t r e q u ir e d f o r d is tillin g b e v e ra g e s f r o m g ra in in a m o d e r n p la n t

Condenser.

Slop tester Pressure

bottle, * Rectifying

column Tail box^

M eal scales

mall grain masher vacovm pv<r>p_

Fermenter Mash

cooler

'Słeam Slop pump

Vacuum cooler Beer

pump

Rectifying still

GRAIN STORAGE

Grinder

Grain bins

M ASH R O O M DISTILLERY

Beer heater Condenser

Ground Corn Rye I Oats Malt

Yeast culture

Continuous

beer still Alcohol

• a moDan GRflin

d is t il l e r y

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»round g ro in storo<

Fusel oil

iHjjnigaciälJl

ií^BeE53m1 FLOW DIAGRAM OF A GRAIN DISTILLERY

ÎMOIt I

BUM

liim i the mash is now raised by adm itting steam to the coil until 145

deg. F . is reached. T he mash is held at this tem perature from 15 to 25 m inutes and finally raised to 152 to 154 deg. F. and held there from 30 to 45 m inutes. T h e saccharified mash is cooled to about 75 deg. F . and is pumped to the ferm enters. Instead of adding all the rye meal at the beginning before the tem pera

tu re is raised above 110 deg. F., we m ay also add half of the rye, a fte r the mash reached a tem perature of 152 deg. to 154 deg. F . and is cooled down to 150 deg. F. T his procedure de

pends entirely on the quality of product desired.

C orn mash requires a much higher tem perature since th e gelatinization of its starch is much m ore difficult. In this case, 7 to 10 per cent of the total m alt required, based upon th e corn to be mashed, is added first to w ater a t a tem p eratu re of 130 to 140 deg. F. and afterw ard s all th e corn meal. W hile the rakes are in motion, the tem p eratu re is raised w ithin 30 to 35 m inutes to 200 deg. F . and is m aintained th ere fo r 10 to 15 minutes. T h e gelatinized mass is cooled rapidly w ithin 20 to 25 minutes, to 158 deg. F . A s soon as th is tem perature is reached, the rem ainder of the m alt is added slowly in order th a t the tem perature shall not drop below 152 deg. F. If rye to the am ount of 10 to 20 per cent of corn is used, it is added a t a tem perature of 156 deg. F. and precaution taken th a t the mash tem perature shall not be below 150 deg. F. W h ere cold w ater is available, the mash is cooled to 100 to 110 deg. F. and when m ixed w ith w ater w ill have the proper tem perature for the ferm enters.

W hile in the open mash tub, the cooking, saccharification and cooling is done under atm ospheric pressure, in the vacuum cookers, cooking is carried on under pressure and the cooling effected under vacuum.

T he vacuum cooker is a cylindrical tank supported on legs, provided w ith a shaft and stirrers. Capacity ranges from 2,000 to 10,000 gal. capable of processing 50 to 250 bu. of grain. They stand a pressure of 100 lb. and are provided w ith several live steam inlet pipes, vent and vacuum lines, also opening for the charging of dry grain and w et m alt from the small grain masher. C ustom ary pressure and vacuum relief valves and therm om eters are also attached.

T h e cookers a re charged w ith 20 gal. of w a te r per bu. of grain. T hen steam is applied and the tem perature raised up to 300 deg. F., or 50 to 65 lb. pressure. D u rin g the heating a g re a t deal of live steam is condensed so th a t a t the end of the mashing, the original liquid volum e has increased to 22 gal.

per bu. A fte r cooking, the blow out pipe is opened to reduce the pressure. T hen the vacuum line is opened and by means of

the vacuum pump, the mash tem perature is reduced to 152 deg. F.

when the m alt mash in liquid form is added from the small g rain m asher. T he amount of m alt used to the grain is from 7 to 15 per cent. A fter allowing sufficient tim e for the sacchari

fication, as has been described for the ooen mash tub, the thick gelatinized mass is dropped into the “drop tub” and from there is pumped through coolers into the ferm enters. F o r the cooling of the mash the distiller employs either a double pipe cooler o r a shell and tube cooler, the latter being used extensively abroad.

F o r the dilution of the mash, w ater or a m ixture of w ater and slop are used. T he latter procedure is applied by Bourbon mashes or w here the slop is to be concentrated and sold for feeding purposes. One cooker is capable of handling 8 to 10 charges per day.

P

R O P E R L Y gelatinized and hydrolyzed the grain will contain m ost of its starch in the form of maltose and

T a b le I I — D is tille d S p ir its P ro d u c e d P u rin « ; th e F is c a l Y e a rs 1910 to 1932

Fiscal <I n T a x G a llo n s )

Year Whiskey Rum Gin Brandy Alcohol AKRregate

1910 82,463,894 2,253,949 2,985,435 7,656,433 68,534,247 163,893,958 1912 98,209,574 2,577,861 3,577,861 9,321,823 73,630,032 187,571,805 1914 88,698,797 3,026,085 4,012,542 7,307,897 78,874,219 181,919,540 1916 59,240,671 2,986,940 4,118.064 4,159,351 182,778,245 253,283,273 1918 17,383,51 1 1,526.743 4,178,538 5,357,325 150,387,680 178,833,797 1920 234.705 944,916 ... 1,649,445 98,436,170 101,265,236 1922 315.799 864,332 ... 1,077,063 79,906,101 82,163,295 1924 ... 784,698 ... 847,104 135,897,725 137.529,527

1926 894,306 643,968 202,271.670 203,809,945

1928 953,350 *41 1,515 169,149,904 170,514,769

1930 1.998,947 982,781 ... 416,043 191,859,342 195,257,113 1932 1.711,028 1,097,777 ... 630,786 146,950,912 150,390,503

♦Brandy manufactured in 1929—-1,194.292 tax gal.

F ig .4— S c h e m a tic d ia g r a m o f d is tille ry as sh o w n in F ig . 3

dextrine which with the addition of yeast is easily fe r

mentable. W ood, enamel-lined or steel tanks can be used fo r the ferm entation of the mash. Small distilleries will use wooden ferm enters but the progressive distiller p re

fers closed steel tanks, provided they have tapered bottom and top as illustrated. T he advantage of the closed ferm enters is the increase of the yield of alcohol from 1 to 2 per cent and the ease of the recovery of carbon dioxide fo r the m anufacture of liquid and solid C O 2 as described by the author in Chetn. & M et., Vol. 38, 1931.

T h e m ash coming from the mash tub or cooker is too concentrated to be ferm ented easily. T herefore, it is diluted w ith w ater or w ater and a slop so th at its fe r

mentable sugar content varies from 7.5 to 11 per cent.

T his is equivalent to from 30 to 45 gal. of beer per bu.

of grain. T he concentration depends a great deal on

—--- SLOP DRYING PLANT

Barometric

s+orage Slop

■tank

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Beer h e a te r

Condenser

Condenser, Wafer' o u tle t ÿ

T hree cham ber still

Doubler

Yeast

II ( htub-ttwi

Continuous beer s till

Low wines M otor-—Ü ,

Frcrn cco/er-^**

To cooler

Fermenting

W h is k i y Low wines Low wines

Doubler 5/op ouHeK

TtłR£€ CtWmWR RY€ UJHISKtY STILL OP€n mflSHTUB c o n n n u o u s ry€ o r BOURBon uuhisk€Y st ill

F ig . 5 — D e ta ils o f e q u ip m e n t f e a tu r e d in m o d e r n A m e ric a n d is tille ry

w hether or not the dealcoholized beer “ slop” has to be re

covered. T h e higher the dilution the less economical is the recovery of slop. A n average m ash will have a density of 15 to 18 deg. Balling and the tem perature d u r

ing the ferm entation depends on the density of the mash, setting tem perature and yeast. O n an average, 56 to 65 hours are required to reduce the density from 10 or 12 deg. Balling to below 0.5 deg. and the acidity of a corn mash increases from 0.045 to 0.85 normal. T o insure an even rate of ferm entation, a tem perature of approxi

mately 70 deg. F . should be m aintained in the ferm enting room.

L arge distilleries m ashing from 2,000 to 20,000 bu. of grain per day will use only continuous stills or a combina

tion of a continuous beer still and batch rectifying still.

T he latter combination is shown in Fig. 3 on a preced

ing page.

T he operation of the continuous beer still is identical on either grain or molasses. T h e ferm ented m ash is dropped into the beer well and from there pum ped con

tinuously at a uniform ra te and delivered to the elevated beer feed tank. T his tank is provided w ith an overflow pipe and is connected to the suction pipe of the beer pump.

T he ferm ented mash 'flows continuously by gravity from the beer feed tank to the beer heater. A feed gage placed in the line provides means fo r observing and regu

lating the rate of flow of ferm ented mash to the beer column. T h e ferm ented mash passing through the beer heater is heated through the tubes of the reflux con

denser by vapors passing through the inter-tubular space.

T he pre-heated beer is fed into the beer still, which is provided w ith a beer heater, condenser, live steam line, and is regulated by testing the alcoholic strength of liquid. A special “slop tester” connected to the base

of the still serves to prevent the loss of alcohol in the

“slop” discharged from the still.

The function of the beer still is to separate and con

centrate the 5 to 8 per cent alcohol contained in the ferm ented mash. T he distillate at from 100 to 140 deg.

proof strength is condensed and stored and rectified in the interm ittent rectifying still (C h e m .& M e t.,V o l. 36).

T he rectifying still consists of the kettle, a rectifying column, dephlegm ator and a condenser. T he kettle, which may be horizontal or upright, is provided with closed steam coils, pressure and vacuum valves, and a glass gage. T he still is charged w ith the distillate from the beer still, called “high wines” and, if necessary, its proof reduced to 100 deg., and in some instances treated with caustic soda or potash.

T he vapors from the kettle pass through the rectifying column which contains from 25 to 50 chambers. Each chamber is provided w ith several bubbling caps and connected w ith the one above by a downtake pipe.

Lately, considerable im provements have been made in the design of these bubbling caps, which may be long, trays w ith saw-tooth edges, straight slotted, slotted giv

ing the vapors a zig-zag direction, or they may be of the small bell type. T he function o f .th e column and dephlegm ator is to separate “heads” or low boiling im purities from the partially concentrated alcohol. These im purities, together w ith some alcohol, are distilled first, then cooled by the condenser and collected in the “alde

hyde”’ or “heads” tank. T he partially concentrated alcohol, freed from these im purities, is now distilled and vapors refluxed until a proof of 190 deg. is obtained.

T he pure alcohol a t this proof is collected until all the alcohol has been recovered from the kettle. Ultim ately, the high boiling im purities such as fusel oil are distilled off. T h e pure 190 deg. proof alcohol thus produced is

622 C hem ical & M etallurgical E ngineering — V ol.40,N o.l2

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sold as sp irit to be used for cutting aged whiskey or applied fo r other industrial purposes.

M any experim ents were made to supplant the three- chamber rye whiskey still illustrated in Fig. 5 w ith the continuous still also shown in Fig. S and know n as the

“B ourbon Still.” So far, however, no conclusive re

sults can be recorded, although the continuous still is finding m ore favor am ong the larger distilleries owing to its ease of operation.

A s w ith all whiskies, the bouquet is the governing factor and several distilleries to be erected or under construction, favor the three-cham ber still because it is claimed to produce a better grade of heavy bodied and highly flavored whiskey. Its operation will be de

scribed briefly.

T h e beer is pum ped into the top chamber of the column, which acts as a beer heater and dephlegmator.

Thence it is draw n periodically every 15 to 20 minutes, from cham ber to chamber, until it is completely de

alcoholized as it reaches the lower slop chamber. T he slop is utilized for feed as will be described later.

T he alcoholic vapors passing through the beer heater go into the doubler, boiling out the low wines, thence to the condenser and the distillate collected as “high wines” or whiskey.

F ro m a fuel economy standpoint, this type of still is not very efficient, but the product is excellent. T here is a recent tendency to use heat exchangers m ore liber

ally, resulting in a fuel economy of 20 to 30 per cent.

F ig. 5 shows a continuous still operated on the same principle as the continuous beer still shown in Fig. 3.

All the features of heat economy applied in the large continuous still are also applied here. T he upper chambers of this column are provided w ith bubbling caps while the lower cham bers containing perforated plates also have down pipes. T he beer is pum ped first through the tubular beer heater overflowing at the top and enters the column on the third or fourth plate. T he alcohol vapors pass first into the beer heater and then they may either go to the doubler or to the low wine condenser. T he doubler is either a horizontal tank or a vertical tank, crowned, provided with a perforated pipe

reaching to its bottom through which the alcohol vapor coming from the still passes through the low wine, thus producing a very highly flavored, heavy bodied product.

T o prevent condensation, the doubler contains a heating coil, usually of the “scroll type” which is controlled to prevent excessive condensation of the distillate. The vapors from the doubler are condensed and collected in the “whiskey” storage tank.

G rains contain quite a high percentage of oil. Corn, which is used m ost extensively has an oil content of 4.5 to 5.5 per cent. Owing to the poor quality of its oil, corn is not generally degerm inated but the oil is recovered in its dried slop. T he processing of slop consists of the following steps: (1 ) . Separation of the suspended solids from the liquids. (2 ) . Removal of excess liquid from the solid in presses. ( 3 ) . Concen

trating the thin clear slop. ( 4 ) . D rying th e solid and m ixing with the concentrated slop. (5 ) . Bagging.

A s the returns from the dried slop reduce consider

ably the cost of alcohol, a brief description follow s:

T h e ferm ented beer, a fte r passing through the still, is de

alcoholized and is called “slop.” T h is slop contains various amounts of solids in suspension and in solution depending on the kind of grain mashed, its quality and the concentration of the slop. A rye mash yields approxim ately 9-9.5 lb. of dried feed per bu. of g ra in ; Bourbon mash from 11 to 11.5 lb. and spirit mash 11.2 to 11.5 lb. respectively.

T h e slop coining from the beer still, passes first into a trav el

ing screen, a long inclined screen box, in which the suspended solids are separated from the liquid. T he solids then pass into the filtering machine, w here they are de-w atered and ulti

m ately put into the ro ta ry dryer.

A fte r the separation of the solid from the liquid, the distilleries usually run th eir thin slop to w aste and recover the suspended solids in dried form except w here the health authorities prohibit their doing so. T he present tendency is to recover all the slop.

T he thin slop is concentrated in a triple o r quadruple effect evaporator to a density of 25 to 30 per cent solids. T his syrup is m ixed w ith the solids and dried if necessary in several stages in ro tary dryers. T h e dryers may be heated directly or_ by ro ta ry steam tube dryers depending on the quality of feed desired and w hether the thin slop is wasted or also recovered. In distilleries m ashing corn, approxim ately 18 to 19 lb. of feed per bu. of g rain is recovered provided all the slop is being processed.

Q uite frequently distillery slop contains 35 to 37 per cent of protein while the fat runs from 10 to 13 per cent depending largely on the condition and moisture

F ig . 6— In g o t ir o n f e r m e n te r s , o f 1 0 0 ,0 0 0 g a l. F ig . 7— L o u isv ille slo p d ry e r s in p la n t o f A m erican c a p a c ity , w ith closed to p s f o r C 0 2 re c o v e ry C o m m e rc ia l A lco h o l C o., P e k in , 111.

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of the grain. Fig. 7 shows six slop dryers built by the Louisville D rying M achinery Co. for the Pekin, 111., plant of the Am erican Commercial Alcohol Co. These handle slop from 6,000 bu. of grain daily. T he value of the dried feed is approxim ately $21. per ton from a corn mash and $18 per ton from a rye mash.

A

L C O H O L produced in distilleries is not considered - whiskey, except a fte r it has been stored and aged for at least fo u r years, which is the minimum tim e re quired by the U nited States Pharm acopia. Its alcoholic content m ust be from 44 to 52 per cent or 88 to 104 proof. As to the aging, the exact reason for im prove

m ent in whiskey by m aturing in casks is by no means clearly understood. I t is usually ascribed to oxidation and the form ation of ethers in the oak casks, which have been charred on the insides.

D uring m aturing the alcohol acquires a mellow taste and its volume in the cask decreases from year to year.

T he Government takes cognizance of this by allowing the following “soakages” per year.

D istillin g : B e v e ra g e s fro m G ra in

Period of Absorption F irst y ear...

Second y ear...

Third, fourth & fifth year.

After fifth y ear...

Kind of cooperage

Plain Charred

9 lb. 13 lb.

12$ lb. 14 1b.

13 lb. 14 1b.

14 lb. 14 1b.

The alcohol in oak barrels is stored in concrete or brick warehouses securely protected against theft. The average tem perature m aintained is 95 to 100 deg. F.

and its hum idity about 20 per cent.

In aging whiskey the m anufacturer has to consider the cost of alcohol, oak barrels, loss of alcohol during storage, insurance, and also fuel for m aintaining the proper tem perature.

Anyone contem plating the erection of a distillery, m ust carefully consider the regulations issued by the U nited States T reasury D epartm ent. A ccording to these regulations, the owners are compelled to adhere to very strict Governm ent supervision. In F orm 27a to be filled out by the owners, all the stockholders, their names and residences m ust be given ; the name of the owner of the stills and other utensils, the kinds of stills and the cubic content of each ; the mode of m ashing and ferm enting, the num ber of hours the distiller will fe r

ment each tub of beer; the num ber of gallons of mash or beer which will represent a bushel of grain ; and the kind of m aterials to be used.

It is highly im portant to employ only skilled help as according to the Governm ent " the true spirit producing capacity” of a distillery is not limited to w hat the distiller

T a b le I I I — D e n a tu r e d A lc o h o l P r o d u c e d D u r in g th e F i s c a l Y e a r s 1910 to 1!>32

( I n W in e G a llo n s )

D enaturing

Year Plants

1910 12

1912 14

1914 25

1916 33

1918 49

1920 52

1922 77

1924 83

1926 97

1928 82

1930 67

1932 49

D enatured Completely

3,076,924 4,161,268 5,213,129 7,871,952 10.328,454 13,528,402 16,193,523 34,602,003 65,881,442 46,966,601 58,141,740 34,298,235

Alcohol Produced—.

Specially 3.002.102 3,933,246 5,191,846 38,807,153 39,834,561 15.307,947 17,152,224 33,085,292 39,494,443 45,451,424 47,645,796 44,031,281

Aggregate 6,079,026 8,094,514 10,404,975 46,679,105 50,163,015 28,836,349 33,345,747 67,687,295 105,375,886 92,418,025 105.787,536 78,329,516

may produce by following a particular course which he has m arked but the am ount which can be produced, using all the m achinery and apparatus under competent and skillful management.

T he governm ent has already established a certain lim it of efficiency under which no distiller is perm itted to operate a distillery without being penalized. In case of a grain or molasses distiller, the first point the G overn

ment determines is w hether the distiller has accounted for all the grain or molasses used, and the spirits pro

duced by him during the month. T h e assessm ent is based upon a production capacity of 80 per cent of the calculated capacity. If, for instance, a plant on a pro

duction capacity basis is 6,000 gal. and it produced 5,000 gal. only, the distiller would be assessed upon 1,000 gal-, as a deficiency.

Because of the maze of contradictory figures that have been issued in recent m onths, it is desirable to

■scrutinize carefully those at variance w ith the following facts: According ito the T reasu ry D epartm ent the U nited States used and produced the following amounts of grain and alcohol in 1917:

G ra in U sed (In bushels)

C orn... 33,973,268 R y e... 2,375,439 M a lt... 4,239,677 O ats... 6,730 W heat... 2,533 Other m aterials... 72,039 40,669,686

A lc o h o l P ro d u c e d (In tax gallons) W hiskey... 57,651,834 R u m ... 2,842,921 G in ... 5,756,666 B randy... 8,251,097 74,502,518 Alcohol... 21 1,582,744 T o ta l... 286,085,262

A ssum ing that the distillers obtained 4.8 pr. gal. of alcohol per bu. of grain, then the total which could be produced from this grain am ounted to 195,214,493 pr.

gal. or based upon a 300-day year, the grain consum p

tion was 135,565 bu. and the alcohol production 650,715 pr. gal. daily.

Since 1917 conditions in the alcohol industry have changed considerably. W hile the num ber of m anufac

turers, through mergers, decreased considerably, the total capacity of surviving plants increased to such an extent that distilleries m ashing molasses now produce on the average, over 20,000 pr. gal. daily. All indications are that the new distilleries will produce beverage alcohol on a much larger scale than was ever attem pted prior to Prohibition. A few distilleries under construction at present will be able to process more than 50 per cent of all the grain mashed in 1917. W h ether there will be a remunerative field for small distilleries depends entirely upon their adaptability to m odern chemical engineering methods.

W hen the enforcem ent of P rohibition restricted the supply of whiskey, the public acquired a taste fo r gin, of which the consumption in 1917 was less than 6,000,000 gal. W hether the demand fo r gin will prevail is prob

lematical. I t is anticipated that the public will gradually retu rn to the use of whiskey, of which the consum ption ratio to gin prior to P rohibition was ten to one. N ot all pre-w ar whiskey was aged over four years in plain or charred white oak barrels as is required by the law for bonded whiskey, but was “blended,” “ rectified,” or “cut”

by the addition of high-proof spirits, flavoring, color

ings, and sufficient distilled w ater to reduce the alcohol content to 50 per cent or less.

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Economic Aspects of

Chemical Process Development

By CHAPLIN TYLER

A m m o n ia D epartm ent

E . I. du P ont de N em o u rs & Co., Inc.

W ilm in g to n , Del.

A V E R Y L A R G E P R O P O R T I O N of inventions is worthless, at least in regards to commercial J L exploitation. B ut even the prom ising ideas have but little tangible value until they have passed stages o f process development. T h e typical chemical process developm ent is expensive. A brief “look” at a process, requiring one m an for three m onths, would cost about

$1,500, and a m ore complex investigation with four men fo r 12 m onths about $25,000. Development costs am ounting to $ 100,000 or m ore are not infrequent.

T he fundam ental factors involved in process devel

opm ent include a study of the underlying chemical reac

tions, changes of state and energy, time factors, and yield factors. F ro m these data a flowsheet is con

structed, showing m aterials and energy at each step of the process. Design of equipm ent and selection of con

struction m aterials is the next step followed by plant layout. O f equal im portance are economic factors such as cost of plant and production, price and m arket con

ditions, and re tu rn on investment.

P rio r to, o r early in development, production costs should be roughed out, with successive refinem ents as the development progresses. T he flowsheet is an excel

lent guide fo r rough estimates. R aw m aterial costs can be set up, first assum ing theoretical yields w ith pure m aterials, subsequently substituting the proper yield factors based on technically pure m aterials. Sufficient raw m aterials of desired specifications m ust be avail

able. H e re it is well to exam ine the depth of supply a n d the price h isto ry ; also if any raw m aterial is im

ported and thus subject to fluctuating foreign exchange, embargo or other governmental control. W a te r supply and miscellaneous factory supplies m ust also be con

sidered.

E nergy requirem ents must be set up, including electric power fo r all purposes, and fuel and steam for process use and heating. In planning metallurgical, electro

chemical, and electrotherm al processes particular pains should be taken to estim ate energy requirem ents as p re

cisely as possible for every step of the process. P ow er fo r refrigeration is a factor in some processes.

D irect labor fo r process, and indirect labor fo r repairs an d maintenance as well as repair m aterials are usually im portant items. Provisions m ust also be m ade for supervision and factory overhead, sometimes 30 per

•cent or m ore of direct labor cost. Depreciation, taxes, and insurance; generally about 10 per cent of the invest

ment per y e a r ; m ust be included in factory cost.

T he foregoing items are factory costs, to which must be added cost of selling and adm inistration, which vary much, but generally will run not less than 10 per cent of factory cost, excluding outw ard freight on the prod-

P r e s e n t e d b e f o re th e s t u d e n ts , c o u r s e o f th e F o u r t e e n t h E x p o s i

tio n o f C h e m ic a l I n d u s t r i e s , D ec. 8, 1933.

uct. F reight, sometimes a large item, usually averages not less than $5 to $10 per gross ton according to quan

tities and distance shipped, freight classification, and type of container. Finally, credits may be included for byproducts, or debits for properly disposed waste m aterials.

Cost of plant can be determined roughly by analysis of m anufacturers’ equipm ent estimates or by reference to estim ating engineers. Cost m ust also include site and im provem ents such as sewer, water, power, rail siding, and roads; buildings, and usually a steam plant.

A generous percentage must be added for contingencies, engineering design, and contractor’s profit. Cost of plant, conveniently expressed as dollars per ton-year of product varies from $ 10-$20 on very large bulk oper

ations, such as superphosphate m anufacture, to as high as $ 100-$200 on equally large operations, but with a d if

ferent underlying technique, that is, requiring high tem peratures and pressures, and nearly autom atic control.

T he total existing m arket for a product is roughly the domestic production plus imports, minus exports, w ith correction fo r stocks. However, this figure includes the entire country, and almost never represents the m arket actually available; the real task is to ascertain w hat really is available. F irst of all, a freight rate study will disclose the economic shipping area. N ext, a ter

ritorial analysis of consumption by districts should be made, which, together with the freight study will reveal the m axim um economic market. I f possible, an inde

pendent analysis should be made, showing individual consumers, by name, by point of consumption, and by quantities consumed. I t is also valuable to make an analysis of present supply, with names, location, and quantities supplied by various producers or im porters.

W ith these data in hand, a rational estimate may be made of (1 ) certain sales, (2 ) probable sales, (3 ) m axim um sales. W ithout such data, the best that can be done is to assume arbitrarily that a fixed share, say 10, 20, or 30 per cent of the total m arket can be secured, a dangerous method, as factors unknown may shut off certain outlets.

R ate of Investm ent R etu rn

W hen the proposed output is very small in relation to existing consumption the price situation is not likely to be disturbed by new production. However, if the product is to displace other products, sales can be achieved only by virtue of lower price, higher quality, superior service, or some combination of these factors.

Estim ates should be made of com petitors’ costs and of the probable increase in demand m arket at various reduced price levels. ■

R ate of investm ent return, the ultim ate test of any process is obtained by subtracting unit cost of sales from price, m ultiplying by quantity and dividing by invest

ment. Generally, if the rate is less than 20 per cent, the process is not attractive. T his may seem high, p ar

ticularly as existing chemical companies rarely earn m ore than 10 per cent on their invested capital. Con

sidering lean years and the inevitable tendency of esti

m ators to be over-optim istic a requirem ent of an indi

cated 20 per cent re tu rn is not too severe. In fact, an indicated re tu rn of 30 or 40 per cent is much more com forting.

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C H E M IC A L

ENGINEERINGS ROLE IN

By W ILLIAM FELTON BARRETT

Vice-President, Union Carbide & Carbon Corp.

Chairm an, Carbide & Carbon Chemicals Corp.

T

I

N D IV ID U A L R E S E A R C H and engineering is be

ing properly and repeatedly recognized by the con

ferring of individual aw ards, medals and honorary degrees. In fact such recognition has been so frequent and has been publicized to such a degree, th at the investor, the public and the youth of the country have perhaps been misled into believing th at whole industries emerge in full bloom from the test-tube w ork of the secluded scientist. W ith no desire to deprecate the achievement of the individual it may be hoped that such aw ards as this one fo r group achievement may tend to correct this fallacy.

Commercial research, as distinguished from academic research, to be successful m ust, from its inception, be directed tow ard ends justified by economics. Problem s m ust be constantly checked and evaluated, as they progress, by the economic yardstick. T he chemical engineer, as differentiated from the chemist, m ust enter the picture and present his judgm ent as to m any of the factors involved. I t is sometimes as im portant to abandon an unprofitable research problem as it is to encourage and assist one of promise. In m ost cases it requires much courage.

In the direction of evaluation and commercialization of such scientific w ork of the chemist, the views of the engineer, the salesman, the patent counsel and the finan

cial m an are all of varying but unquestioned value.

Each is the needed complement of the others. T hey are the five digits that make the hand a perfect mechanism

— that give it power and skill and accomplishment.

In the case of the Chemicals C orporation we pay full tribute to the essential and economic im portance of our original research along organic chemical lines, coupled w ith our physical-chemical developments in the separa

tion of mixed gases into their pure state. A t the same time we recognize th at the translation of these research results into an industry of m agnitude, especially in the relatively few years of its existence, could not have been possible w ithout the many and varied resources of our parent company to draw upon.

Perhaps a few specific instances of this coordination of resources may be of interest. In our chemical proc

esses, most of which are new, it is necessary to pioneer, not alone in the products to be created but also in the

design of equipm ent and the selection of m aterials. In many cases reactions are carried on at excessively high pressures or high tem peratures, or both— possible only in special alloy steel equipment, which alloys are the results of research and experience of our E lectro M etal

lurgical Co. T h a t company and in some cases the carbon products division of our N ational Carbon Co. are em

ployed to assist in the solution of corrosion problems.

Special oxy-acetylene welding technique is often required in fabrication of equipm ent and this knowledge is pro

vided by the engineers of our Linde A ir P roducts Co.

T h at company is also called upon fo r specialized in fo r

mation regarding fractionation and rectification, espe

cially in the low -tem perature field. I t will be rem em bered 'that the L inde Co., in addition to being the largest m anufacturer of oxygen in the world, adapted and devel

oped its processes so as to achieve, commercially, the separation from natural gas of helium, theretofore a laboratory curiosity, and was the only producer during the W orld W ar. I t will be appreciated that this source of engineering assistance is of the highest value.

W hile the foregoing may tend to minimize the romance associated with the M agic of Chemistry, they point out some of the conditions which have enabled us to have judiciously invested m any millions of dollars in the devel

opment of an industry which has resulted in m ost satis

factory sales volumes and net profits.

These facts also seem convincing in support of the decision of Chemical & M etallurgical E ngineering to recognize the force of group effort and attainm ent as a prime element in the advance of industry. B ut its editors go fu rth e r and state that the aw ard is also “ in recognition of a broader participation by the chemical engineer in the affairs of the process industries.” T he term “chemical engineer” may be defined in an extrem ely broad sense or again may be defined in term s of the various courses leading to a Ch.E. degree in our uni

versities. In the belief that Chent. & M et. uses the term in the broader meaning,— from that angle it may be pertinent to state th at every officer of the Chemicals Corporation and every m ajor departm ent head is, or started his career as, a technical m an w ith one or more degrees. I t may be of interest to know that the Chem

icals C orporation employs about 200 men holding tech-

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G RO UP A C H IE V E M E N T

O f these men approxi-

E D IT O R ’S N O T E : C h c n i. & M e t.’s fir s t aw ard f o r c h e m ic a l e n g in e e r in g a c h ie v e m e n t was m a d e to th e C a rb id e & C arbon C h e m ic a ls C o rp . at a d in n e r a t th e C h e m is ts ’ C lu b in N ew Y o r k , D ec. 8 , 1 9 3 3 . I n a tte n d a n c e tcere seven o f th e n in e m e m b e r s o f th e C o m m itte e o f A tcard a n d a g r o u p o f tw e n ty e x e c u tiv e s a n d e n g in e e r s o f th e U n io n C a rb id e & C arbon C orp. F o llo w in g a n o u tlin e b y th e e d ito r o f C h e m . & M e t. o f ' t h e p u r p o s e s fo r w h ic h th e atcard was e sta b lish e d , a n d a s ta te m e n t b y C h a irm a n J o h n V an N o str a n d D o rr, o f th e C o m m itte e ’s p ro c e d u r e h i select

in g th e w in n e r , M a lc o lm M u ir , p r e s id e n t o f th e M cG raw -H ill P u b lis h in g C o m p a n y , I n c ., p r e s e n te d th e b r o n z e p la q u e to W illia m F e lto n B a r r e tt. E x tr a c ts fr o m th e la tte r ’s a d d ress o f a ccep ta n ce a re p u b lis h e d h e re w ith .

nical degrees.

mately one-third are employed in re search and development— one-third in engineering and operating and one-third in sales activities and ex

ecutive capacities.

A significant side light on the m an

agem ent factor of an organization of so m any technicians is the fact that since the com pany’s inception, the

“ tu rn over” in our technical personnel has been practically nil. U nlike many corporations during the depression period, no technical men w ere dis

charged nor were our research and development program s curtailed. I t is this fact which has insured no ces

sation of our fixed policy of yearly introducing new products.

In building our organization, we have attem pted to use the greatest care in selecting our young technical men and, although selections are gen

erally m ade w ith specific duties in mind, all new men are first given a period of w ork as cadet engineers.

In this period an attem pt is made to

determ ine the specific adaptability of each individual, and he is then assigned to a departm ent in which it is felt he will be able to w ork m ost efficiently. I t has not always been possible in the first or second assignm ent to find the environm ent best suited to the individual, but we have been singularly fortunate in ultim ately placing m ost of these young men in types of w ork in which their inherent abilities have been given an opportunity to grow and de

velop. T hrough this m ethod of placing our technical men, there has resulted a wide dispersal of the chemical engineer into all of the various phases of our activities, not only in engineering and operation, but also in re search, development, sales, and m anagem ent as well.

W hile the usual development of a new process and its products proceeds in the order of research, development, engineering, construction, m anufacturing and sales, the relation of these different phases of our activity in our

chain of operation is such that valuable contributions are frequently m ade to one departm ent by w orkers in another departm ent fa r removed. Thus, the research and development units are linked to the sales departm ent in certain phases of their work, the research departm ent sometimes has w orkers in the m anufacturing operations, and at times the development engineer finds himself progressively engaged in phases of the engineering, design and construction of the process he has developed.

U ltim ately he m ay find himself in charge of the opera

tion of that process.

T his form of organization, as encouraged and devel

oped, has given the chemical engineer a degree of free

dom of action which does not constrain his effort nor limit his ambitions. I t has been the means of affording him that broader participation that is essential in devel

oping men, new processes and products.