Chemical & Metallurgical Engineering, Vol. 49, No. 7

CHEMICAL

& m e t a l l u r g i c a l

ENGINEERING

ESTABLISHED 1902 S. D. KIRKPATRICK. E ditor

JULY. 1942

MILESTONES AND CORNERSTONES

F i f t y y e a r s a g o

our good dean of chemical engi­

neering- educators, Professor Alfred Holmes White of Michigan, was told by his teachers that the field of physics was practically closed. “ The best you can look forward to, young man, is the opportunity to redetermine certain physical constants with a little greater accuracy — perhaps changing the fourth decimal place.” Yet today, in a very real sense, this is the war of the physicists. The mili­

tary decisions that may yet change the whole his-, tory of mankind for a fourth generation to come are now being born in the research laboratories of American universities and technological institutions.

The occasion of Colonel W hite’s remarks was in Evanston, 111. on June .15, when, as president of the Society for the Promotion of Engineering Educa­

tion, he represented the profession at the dedication of the new Technological Institute of Northwestern University. Other distinguished engineers, scien­

tists and educators shared the limelight with politi­

cal leaders of the state and nation and with men like Donald Nelson and General Knudsen, who recognized in this event another step in the mobili­

zation of science and engineering in the present national emergency.

The dedication could scarcely have come at a more appropriate time to emphasize the importance of our technological educational institutions to the welfare and safety of our country. President Karl T. Compton of M.I.T., whose address dealt with the future of engineering education, digressed long enough to note that the Office of Scientific Research and Development has already entered into 663 contracts with educational institutions for the performance of research and development work with but one objective—to improve our war effort, l ie could not even hint at the nature of the inves­

tigations “ that have already shown promise of becoming important factors in the forthcoming m ilitary decision.”

Closely paralleling the war work in the universi­

ties is that in the industrial research laboratories.

where' more than 200 contracts have been placed with about 75 commercial firms. To our knowledge, one company with a $5,000,000 research and devel­

opment budget is today devoting 90 percent of its energies to the Victory effort, but, of course, only a small part of this is on direct OS1M) contact.

Such is the change from that first industrial re­

search laboratory in the United States which Dr.

Compton told us was established in 1834 by the Merrimack Manufacturing Co. in Lowell, Mass.

and had as its objective the study of the chemistry of cow dung and of substitutes for cow dung as chemicals used in calico dyeing. Today that labora­

tory’s modern successor is working on more offen­

sive agents of chemical warfare and there is no “ e ” in the kind of “ d yin g” with which it is now con­

cerned !

Chemical engineering received a high tribute from President Compton when he remarked that

“ future improvements in engineering education may be expected to follow along a path which has been laid out by the chemical engineers.” He traced the change from the earlier method of study­

ing the details of a diversity of manufacturing processes to the modern approach through an inte­

grated conception of fundamental unit operations.

“ This new concept . . . has resulted in chemical engineering’s becoming one of the most useful and active of all engineering professional fields. The students in this program develop a power to handle situations rather than to absorb a mass of detail applicable only to appropriate specific situations.”

Dr. George O. Curme, Jr., of Northwestern’s class of 1909, saw in the new Technological Insti­

tute an important parallel with “ Research in In­

dustry,” which was the title of his address. Today research squads are used like task forces in which all types of talents and weapons are combined to reach the desired objective. The tremendous physical plant of the Institute, providing ten acres of floor area in a building 500 ft. wide and 342 ft.

deep, brings the departments of chemistry and

physics into close association with the four major branches'of engineering—chemical, civil, electrical and mechanical. Dr. Curme feels that this closer, mutually stimulating cooperation can open up new frontiers far beyond the present horizons of research.

Both the Hon. Jesse Jones and the equally honorable Donald Nelson stressed the importance of the new facilities in relation to the post-war world. The Secretary of Commerce said that

“ those who will pass through the Technological Institute of Northwestern, b en efitin g from both theoretical and practical knowledge, can contribute much when the day for peace-time conversion comes.” Nelson said, “ We need and must have engineers, not only to speed up the war program, but to aid us with the great task which will be ours when peace comes, as come it will. We are going to need engineers to mobilize for peace with the same enthusiasm, energy and determination that we are mobilizing for war. Now, and in the future, within the walls of this Institute and outside it in the laboratories and factories of industry, there can be no faltering in the continuous search for ways of achieving greater and greater results for mankind.”

Such were the highlights in dedicating a great new facility for technological education. In a broader sense it was a dedication of all technology and of all its practitioners to a new and greater spirit of service to the nation and to the cause of human liberty throughout the world.

AGAINST THE PUBLIC INTEREST

In d i c t m e n t s

have been returned at South Bend, Indiana, against numerous chemical companies and their executives. It is not yet proper here to com­

ment on the guilt or innocence of the defendants so brought to bar. B ut it is appropriate, in fact we believe it important, to point out that the action of the Department of Justice in these proceedings has

110 justification, because it is very definitely

contrary to the public interest.

The Department of Justice has appropriately from time to time investigated the basis on which chemicals are marketed. It is the duty of that De­

partment to see that the law regarding restraint of trade is in force. Under all ordinary conditions there should be prosecutions when there seems to be valid evidence of serious violation of the law.

So much for normal conditions.

Present conditions are very different. In the first place, the Department itself has been doing a slovenly job by bringing up cases which Federal judges have thrown out without defense because no proof of guilt was submitted. In the second place, there is evidence in the writings of Assistant A t­

torney General Arnold himself that it is his purpose to accomplish reform by means of these Court prosecutions. In the third place, even the Depart­

ment of Justice ought to be busy at jobs which help win the war; certainly they should not take

time from far more urgent jobs of their own. Nor should they be permitted to take thousands of man- days of useful war effort away from chemical com­

panies to defend themselves against such attacks.

In due time we shall find out what the Courts say about the recent indictments. B ut in the mean­

time, it is safe to conclude that the Department of Ju stice’s activities while perhaps technically and legally proper, are dangerously close to treason.

They are in effect equal to the taking of thousands of soldiers away from the fighting front in order to meet trumped-up traffic charges for speeding alleged to have happened months ago.

It seems high time that President Roosevelt should take charge of this situation and correct it.

This can be done without any sacrifice of the Departm ent’s right to enforce the law, a right which is also its duty.

THAT LONGER LOOK AHEAD

On e

of the greatest obstacles to date in the'whole war-time construction program has been the un­

certainty as to requirements. Some chemical com­

panies were alert enough to see the need and get ready for them. In days when priorities were not so difficult to obtain, a few organizations built plants a little beyond official requirements and are now able to do a better job because of that happy foresight. Unfortunately those are excep­

tions. Too often capacities were established and approved when those in the government responsible for supplies knew that actual requirements far exceeded the official figures. Nevertheless, there must be no complaining. I t is industry’s job to do­

its utmost to prepare itself to produce what in fact will be needed to sustain our war effort.

An executive of a leading chemical company writes us as follow s:

“W ith the very serious reduction of raw m aterial supplies entering this country follow ing the attac k on P earl H a rb o r and the continued prosecution o f Ger­

m an subm arine attacks on ou r shipping, it becomes, increasingly evident th a t w ithin a year’s time, we will need extensive expansion o f some of our chemical industries in order to fill the g ap caused by the grow­

ing scarcity o f n a tu ra l raw m aterials.

I n spite o f this ra th e r obvious situation which is developing, I know o f no effort being m ade by o u r governm ent to forecast this condition and to provide fo r it by expanding chemical p la n ts other th a n those- th a t some day will make our synthetic rubber. No country-wide survey has been m ade to estim ate the- essential requirem ents fo r substitutes th a t will soon be very badly needed. Even our N avy is rushing around try in g to find substitutes fo r m aterials which have been taken aw ay from them while in the m ean­

time the enemy’s subm arines continue to sink our sup­

plies o f other m aterials which m ight have been used as substitutes fo r the substitutes. There is need for- some agency, governm ental o r private, to make ai thorough-going study of the needs fo r chemical sub­

stitu te m aterials, to take the place o f n a tu ra l m ate­

rials no longer available in this country.”

This has an important bearing, too, on the prob­

lem of providing new plant capacity in the chem­

ical process industries—a subject which is reviewed

76—7 J U L Y 19J,2 • CHEMICAL & M ETALLURGICAL E N G IN EER IN G .

at some length in the current Cliem. & Met. Re­

port on War-Time Construction. (See pp. 99 to 106 of this issue.) We have now got to fight for such new facilities as are absolutely essential to keep the

Avar

program rolling.

O N THE POLITICAL FRONT '

Ma n y

observers of Washington have lately pointed

out that the desire for reelection is occasioning some highly undesirable delays in legislative action.

Politics are affecting many decisions on war policies that ought to be made strictly on merit.

The unwillingness to vote promptly on a tax bill, the unwillingness to give the Army more of the young men of 19 to 20 years of age, and the other postponements of embarrassing votes until after November, are the kind of criticisms commonly cited. Those who have influence with members of Congress may to some small degree offset these tendencies for delay. They can emphasize to these members that aggressive patriotic effort is the best kind of politics today. Pacing unpleasant votes frankly ought to be made the finest argument for reelection. In a few cases it may be.

W A S H I N G T O N H I G H L I G H T S

COMPETENT ENGINEERS ill the top organization of both the W a r M an­

pow er Commission and the A rm y Specialists Corps understand the technical personnel problem s of in ­ dustry. Likewise they know th a t the A rm y needs engineers in industry ju s t as badly as it needs com petent m ilitary personnel in uniform . This is encouraging. W e cannot expect th a t all diversions o f much needed m en from civilian posts to non-tech- nical A rm y jobs can be stopped a t once. B u t we can hope th a t the r e ­ cent trend of taking too large a num ­ ber of key personnel will be reversed.

Those who will establish the guiding principles here are Dr. W illiam 0 . H otchkiss, D eputy D irector General, A rm y Specialists Corps, on leave as p resident of Rensselaer Polytechnic In stitu te, and D r. E dw ard C. E llio tt o f the W a r M anpow er Commission, p resident o f P u rd u e U niversity.

DEFERMENT o f key employees m ust be requested by em ployers. W ashing­

ton does n o t think it is in the public interest fo r m anagem ent to be u n ­ willing to ca rry through aggressively its argum ents fo r deferm ent when highly skilled personnel is likely to be d rafted fo r m ilitary service in which th a t skill is less essential. I t is one thing to provide a hideout fo r slackers; it is an entirely different thing to decline to m ake necessary and u rg en t requests fo r deferm ent of essential personnel. M anagem ent has a real responsibility in this m atter.

PRICE RISES s ta rt on the farm . In the first fo u r m onths of 1942, the sales o f farm goods retu rn ed 50 p e r­

cent m ore dollars to farm ers than in the corresponding period a year ago.

Processors feel very sh a rp ly the pinch between a frozen price ceiling and these risin g costs o f both raw

m aterials and labor. No am ount of increased business helps much in these circumstances.

T.V.A. has had another reprieve. Con­

gress seriously considered lim iting its disbursem ents to the actual a p p ro ­ p riatio n s b u t it was evident th a t the corporate activities o f this quasi­

governm ent body would thus be severely restricted. Hence the use o f revolving funds has been con­

tinued. B u t the attack on T.V.A., which was by no means the last one to be expected, shows th a t Congress does not like to relinquish the ad­

m inistrative control o f funds, even when there is no question as to the desirability of the spending.

RAILROAD CAR MOVEMENT m ust be speeded. E very p la n t m anagem ent m ust, and it is a real M UST, arrange fo r p ro m p t loading o f cars when spotted on th eir sidings and imme­

diate unloading o f deliveries. A ny establishm ent failing to cooperate pro m p tly is likely to be deprived of car service.

RECRIMINATION runs in cycles. A fter each m ilitary set-back there is a new wave o f criticism. The loss o f Libya occasioned one o f the most b itter u p ­ risings o f everyone ag ain st every­

body else in the Capitol. This is dem ocratic hum an n a tu re in action.

I f it does not destroy too much o f the enthusiasm fo r su p p o rt of w ar un ­ dertaking, it is a good symptom.

SPENDING som ething over fifty bil­

lion dollars nex t y ear by the Arm y, N avy and Lease-Lend agencies in m ilitary effort will depend p rim a rily on a single facto r—availability o f es­

sential raw m aterials, p rim a rily m et­

als and chemicals. H ence there m ust be, first, a maximum production of

every wanted commodity and, second, a rigorous conservation to stretch lim ited supplies over the maximum possible essential service.

G AS w a r f a r e is expected. The w arning of the P resident th a t the United States will reta lia te i f J a p a n persists in using toxic chemicals on the Chinese was more than a ges­

ture. Definite p re p a ra tio n is being made. Chemical W a rfa re Service is establishing a huge new train in g cen­

te r where it will p re p a re both defense and offense personnel fo r this k ind of fighting. A m erica does not wish it, but does n o t intend to rem ain u n p re ­ pared.

SHORTAGES o f three things m ost w orry W ashington. (1) W e have nothing like as much m etal to cut up into im plem ents o f w ar as we could use effectively w ith p rese n t m anpow ­ er and p rese n t p la n t capacity. (2) Even present production cannot be moved p rom ptly to the fighting fro n ts because o f shortage of ships. (3) Lack o f ru b b er threatens to force civilian activities below w hat is re­

garded as a minimum essential level, even fo r war-tim e. M any decisions o f official W ashington th a t otherwise cannot be understood ro o t in these three worries.

PLANS of the new special R ubber I n ­ vestigation of the H ouse o f R ep re­

sentatives were p re tty well forecast by its newly ap p o in ted counsel, E l­

liot E . Sim pson. A m ong other things, this gentlem an stated fra n k ly th a t he will tr y “to prove conclusively th a t A m erica can su p p ly m ore than enough ru b b er for all m ilitary and civilian needs.” Ju d g in g from such preconceived conclusions, another political p illaging of in d u stry is in the offing.

CHEMICAL & M ETALLUR GICAL E N G IN E E R IN G • J U L Y 7.97/2 7— 77

Production of Acetylene by Thermal Cracking oi Petroleum Hydrocarbons

R. LEONARD HASCHE

T en n essee Eastm an Corp., K ingsport, T en n essee

--- C liem . & M e t. I N T E R P R E T A T I O N _ _ _ _ _ _

In com m on w ith m ost ch e m ica ls an d c h em ica l raw m aterials, a c e ty le n e is b ecom in g in cr ea sin g ly im portant in A m erica's V ictory program . P y ro ly sis of hydrocarbons h a s lo n g b e e n recogn ized a s a potential source of the g a s , but tech n ical difficulties h a v e heretofore ruled out com m ercial in stallation s. H ow th ese w ere o v erco m e is related here b y on e of the m en la r g e ly resp o n sib le for the s u c c e ss of a project to m ak e cracking a p ractical source of a c e ty le n e .—Editors.

JfCETYLENE has long been rec- 4 TjL ognized as one of the most im p o rta n t and versatile sta rtin g m a­

terials fo r organic syntheses, p a rtic ­ ularly fo r the p re p a ra tio n of aliphatic compounds. Although its reactivity with a g re a t variety of substances was early recognized and made use of by the chemist in the laboratory, only within com paratively recent years has it been applied to com­

mercial syntheses. The first im ­ p o rta n t development in this direc­

tion was the conversion o f acetylene, obtained from calcium carbide, to acetaldehvde as the first step in the production of acetic acid. This in ­ dustry has now assumed very large proportions both in this country and abroad. Some of the newer cliem-

icals now being m anufactured from acetylene are vinyl acetylene, vinyl acetate and the halogen derivatives

— tetrachlorethane and trichlorethyl- ene.

A much la rg e r field o f usage for acetylene is now opening u p in the m anufacture o f butadiene fo r syn­

thetic rubber. I n Germany, coinci­

dent with the developm ent o f a self- sufficiency in synthetic rubber, the construction o f calcium carbide plants was stepped up several-fold. W hile in this country the petroleum indus­

try offers possibilities of producing butadiene by cracking, there seems little doubt th at acetylene will be a form idable com petitor, due to both low cost and the p u rity of the b u ta­

diene obtainable by this method. W e

have mentioned vinyl acetylene as another product which is an in te r­

m ediate in the p re p a ra tio n of the chloroprene rubbers. Thus, we see th a t acetylene is destined to play an im p o rta n t role in our N ational Vic­

tory P rogram .

ADVANTAGES OF THERMAL CRACKING

L et us consider the facto rs th at recommend the therm al cracking method fo r the commercial produc­

tion o f acetylene. One obvious ad­

vantage o f stra ig h t therm al p y ­ rolysis o f hydrocarbons to produce acetylene over the electric arc or silent discharge is th a t the necessary heat can be supplied by burning the byproduct gases, produced in the process, which consist m ainly o f hy­

drogen and m ethane. In other words, the cost o f energy fo r the pyrolysis is included in the cost o f the hydro­

carbon m aterial processed. The net saving o f the therm al over the elec­

trical method— with equal yields of acetylene— is the cost of the elec­

trical pow er required in the la tte r method. A t a cost o f three mills p er kwh. this saving would am ount to about l j c . p er lb. o f acetylene, a substantial proportion o f the total cost.

A nother very im p o rta n t advantage following logically from the above

H I S T O R I C A L — E d m u n d D a v y * in 183«

d i s c o v e r e d a n e w g a s w h ic h h e r e p o r t e d a s b e in g f o r m e d b y t h e a c t i o n o f w a t e r o n p o t a s s i u m c a r b i d e . H e a l s o r e p o r t e d a n u m b e r o f i t s i m p o r t a n t p r o p e r t i e s w h ic h l e a v e s n o d o u b t t h a t t h e g a s h e w a s d e s c r i b i n g w a s a c e t y l e n e . B e r t h e - l o t n a m e d t h e g a s “ a c e t y l e n e ” a n d In a s e r i e s o f r e s e a r c h e s b e g u n i n 1S60 m a d e a v e r y c a r e f u l s t u d y o f i t s p h y s i c a l p r o p ­ e r t i e s . I n 1862, B e r th e lo t* s h o w e d t h a t a c e t y l e n e c o u ld b e m a d e b y t h e d i r e c t u n io n o f c a r b o n a n d h y d r o g e n in a n e l e c t r i c a r c . I n t h e s a m e y e a r W o e h l e r 1 m a d e t h e n o t e w o r t h y o b s e r v a t i o n t h a t t h e g a s w a s fo r m e d b y t h e a c t i o n o f w a t e r o n c a l c i u m c a r b i d e . T h i s o b s e r v a ­ t i o n e s c a p e d n o tic e u n t i l t h i r t y y e a r s l a t e r w h e n t h e r e a c t i o n b e c a m e o f g r e a t c o m m e r c i a l im p o r t a n c e . L c w f s 1 in 1891 c o n v e r t e d e t h y l e n e t o a c e t y l e n e b y d i r e c t t h e r m a l c r a c k i n g , o p e r a t i n g a t t e m p e r a ­ t u r e s o f 9 0 0 to 1,500 d e g . C. H o w e v e r , h i s y i e l d s o f a c e t y l e n e w e r e v e r y lo w . L a t e r , B o n e a n d C o w a r d 5 p r o d u c e d s m a l l a m o u n t s o f a c e t y l e n e f r o m m e t h a n e , e t h a n e a n d e th y le n e .

A m e r i c a p io n e e r e d i n t h e d e v e l o p m e n t o f a c o m m e r c i a l m e th o d f o r p r o d u c i n g a c e t y l e n e . W h i l e B o e h m 8 c l a im e d in a p a t e n t a p p l i c a t i o n , filed in t h e U n ite d

S t a t e s N o v e m b e r 5, 1891, t h e p r o d u c t i o n o f c a l c i u m c a r b i d e b y h e a t i n g c a r b o n a n d a n a l k a l i n e e a r t h b y m e a n s o f a n e le c ­ t r i c c u r r e n t , W ils o n in t h i s c o u n t r y is g iv e n t h e c r e d i t f o r m a k i n g t h e f i r s t c a l ­ c iu m c a r b i d e in t h e e l e c t r i c f u r n a c e . W h ile a t t e m p t i n g t o p r o d u c e a l u m i n u m In t h e e l e c t r i c f u r n a c e , h e a c c i d e n t l y d i s ­ c o v e r e d a n e w a n d p r a c t i c a l m e th o d o f m a k i n g c a l c i u m c a r b i d e . O n M a y 2, 1S92 h e r e c o g n i z e d i t s i m p o r t a n c e f o r t h e c o m m e r c i a l p r o d u c t i o n o f a c e t y l e n e . T h r e e d a y s l a t e r h e f ile d a p a t e n t a p p l i ­ c a t i o n 7. H e n r i M o is s a n r e p o r t e d s i m i l a r d i s c o v e r i e s o n D e c e m b e r 12, 1892 b e f o r e t h e A c a d e m ie d e s S c ie n c e s in P a r i s . I n 1894 L e w e s 8 in L o n d o n f i r s t e m p lo y e d a c e t y l e n e in a b u r n e r f o r l i g h t i n g p u r ­ p o s e s . A g r e a t e r d e v e l o p m e n t w a s y e t to c o m e . T w e lv e y e a r s l a t e r in 1906 a c e t y l e n e w a s f i r s t a p p l i e d in b u r n e r s f o r t h e w e l d i n g a n d c u t t i n g o f m e t a l s .

T h e p r o d u c t i o n o f c a l c i u m c a r b i d e g r e w r a p i d l y a f t e r t h e d i s c o v e r y o f a c e t y l e n e w e ld in g , r e a c h i n g a v o lu m e o f a p p r o x i m a t e l y 2 5 0 ,0 0 0 t o n s in 1928.

S in c e t h e n , t h e i n c r e a s e i n p l a n t c a p a c i t y h a s n o t b e e n v e r y r a p i d , b u t w e n o w a p p e a r t o b e o n t h e t h r e s h o l d o f a g r e a t l y i n c r e a s e d u s a g e o f a c e t y l e n e a n d i t s p r o d u c t i o n b y h i g h t e m p e r a t u r e

p y r o l y s i s o f h y d r o c a r b o n s a s a c o m p e ti­

t o r f o r c a l c i u m c a r b i d e w a r r a n t s c a r e f u l c o n s i d e r a t i o n . T h i s is p a r t i c u l a r l y t r u e n o w d u e to t h e t h r e a t e n e d s h o r t a g e o f e l e c t r i c p o w e r a s a r e s u l t o f t h e d e m a n d s o f t h e D e f e n s e P r o g r a m in t h e p r o d u c ­ ti o n o f a l u m i n u m a n d m a g n e s i u m . P o w e r

is t h e l a r g e s t s i n g l e i t e m o f c o s t in c a l ­ c iu m c a r b i d e m a n u f a c t u r e , a m o u n t i n g to a p p r o x i m a t e l y 3,0 0 0 k w h . p e r to n o r e q u i v a l e n t to a b o u t 4.5 k w h . p e r lb. o f a c e t y l e n e .

E L E C T R I C A L C R A C K IN G A c e t y l e n e i s a v e r y e n d o t h e r m i c c o m ­ p o u n d , h a v i n g a h e a t o f f o r m a t i o n f r o m i t s e l e m e n t s o f a b o u t 59,000 c a l . I n o r d e r t o p r o d u c e i t f r o m a h y d r o c a r b o n r i c h e r in h y d r o g e n , t e m p e r a t u r e s a b o v e 1.100 d e g . C . a r e r e q u i r e d . F o r h y d r o ­ c a r b o n s h i g h e r t h a n m e t h a n e , e m p lo y in g c o n t a c t t i m e s o f a b o u t 0.1 s e c ., o p t i m u m y i e l d s o f a c e t y l e n e r e q u i r e t e m p e r a t u r e s o f a p p r o x i m a t e l y 1,225 d e g . C ., a n d f o r m e t h a n e i t s e l f in t h e n e i g h b o r h o o d o f 1,5 0 0 d e g . C. I t w ill b e q u i t e e v i d e n t t h a t o n e o f t h e r e a s o n s f o r t h e s lo w p r o g r e s s In t h i s d i r e c t i o n h a s b e e n d u e to t h e d iff ic u lty in a t t a i n i n g t h e s e e l e ­ v a t e d t e m p e r a t u r e s . T h e r e a r e v e r y fe w m a t e r i a l s a t o u r d i s p o s a l t h a t w ill w i t h -

78— 7 . J U L Y 19.',2 . CHEMICAL & M ETALLURGICAL E N G IN EER IN G

consideration is th a t p la n t location is n o t confined to localities of cheap and adequate pow er supply, ft neces­

sary requirem ent fo r both calcium carbide production or the use of an electric method of cracking. A loca­

tion chosen because of suitable power conditions m ight not be where hydro­

carbon m aterials are cheap and abun­

dant. F o r therm al cracking a wide choice o f p la n t locations is possible w here am ple supplies o f petroleum or n a tu ra l gas hydrocarbons are available a t a low cost.

W orkers in the field o f high tem­

p era tu re therm al cracking of hydro­

carbons to acetylene have been aw are of the possible advantages which have ju s t been pointed o u t; they have furnished the incentive fo r the de­

velopm ent discussed in this article.

L ittle progress was m ade 011

stra ig h t therm al cracking u n til 192G when W ulfi in this country carried out an extensive stu d y o f high tem­

pera tu re , therm al cracking w ith the view to developing a commercial method fo r the production of acetyl­

ene. l i e was the first one who recog­

nized the g rea t im portance of a com­

bination of short contact tim e and ra p id quenching o f the cracked m ix­

ture, in obtaining high yields. A series o f p aten ts” have been issued to him covering the therm al cracking of hydrocarbons to acetylene em ploy­

in g tem peratures above 1,500 deg. P ., a contact period of less than five seconds, and ra p id cooling of the product.

F ischer and co-workers“1 in a series o f investigations begun in 1928, showed th a t by controlling the con­

ta ct time, good yields of acetylene w ith very little carbon form ation could be obtained a t atm ospheric p re s­

sure.

Sim ultaneously, other laboratories

investigated the pyrolytic method.

Tropseh and Egloil’2'1 studied the p y ­ rolysis of methane, ethane, pro p an e and butane u nder reduced pressure.

Subsequent work was reported by Tropseh, P a rrish and EglofF1 on the pyrolysis o f the gaseous olefins.

Pyzel22 showed the therm al cracking of n a tu ra l gas to acetylene and ethyl­

ene, injecting additional n a tu ra l gas into the hot gases issuing from the converter to produce fu rth e r quan­

tities o f ethylene.

In 1934 a program for commer­

cializing the process of therm al cracking to acetylene was initiated by the Tennessee E astm an C orpora­

tion, and it is the purpose of this article to re p o rt the development.

LABORATORY TUBE CRACKING In the earlier work, the optim um conditions fo r cracking the various saturated, aliphatic hydrocarbons were determined in a laboratory f u r ­ nace producing 4 to 10 cu.ft. of cracked gas p e r hr., depending on the type o f hydrocarbon processed.

In the furnace, a carborundum tube 4-

111. i.d. x 2-in. o.d. and 6 ft. in length served as p reh eater section. I t ex­

tended through the high tem perature zone where the tube was enclosed in an alundum sleeve wound with mo­

lybdenum wire. A round the w ind­

ing was a tig h t steel box packed with silica-free alundum sand. A slight pressure of hydrogen was m aintained in the enclosing cham ber as a reduc­

ing atm osphere to p revent oxidation of the molybdenum wire. Centered in the carborundum tube, was an alundum tube SI in. i.d. for the dual pu rp o se of enclosing a platinum -rho- dium therm ocouple and acting as a core-buster so as to allow a very high gas velocity and consequently a very short contact time.

Gas tem peratures of 1,500 deg. C., readily obtained with the furnace, were sufficient to crack m ethane, n atu ra l gas, m ixtures of heavy hy­

drocarbons separated from n atu ral gas, as well as propane, butane and n atu ra l gasoline. In all of the work, steam diluent was used and contact times were less than 1/10 sec.

In Table I are shown the results obtained in cracking 28-70 grade n atu ra l gasoline a t various tem pera­

tures. I t will be noted th a t the en­

tire tem perature range of acetylene cracking is covered, u p to a point where over-cracking occurs. A n idea o f the mechanism of the pyrolysis process may be gathered by re fe rrin g to Fig. 1, in which the results are plotted graphically showing the yield o f the various carbon containing con­

stituents obtained in the pyrolysis.

P ortions between the curves show the am ount o f the products form ed at the various tem peratures.

I t will be noted th a t even in p y ­ rolysis of n a tu ra l gasoline, which is a m ixture of paraffin hydrocarbons containing five o r more carbon atoms, ethane is the highest member o f the paraffin series presen t a t slightly above 1,000 deg. C. I t disappears above 1,150 deg. C. and the olefins are progressively converted into acetylene— butylene d isappearing at about 3,175 deg. C. and propylene at a tem perature of 1,350 deg. C. which is optim um fo r acetylene. An in te r­

esting f a c t is th at m ethane increases u n til the ethane disappears and then rem ains substantially constant until 1,400 deg. C. is approached. Benzene is a very stable com pound a t high tem peratures due to its endotherm ic O ne type of horizontal furnace in se m i­

w orks sc a le . Air and g as-steam p re­

heater are in the vertical sh ell

s t a n d t h e h i g h t e m p e r a t u r e s , h a v e s u f ­ f ic ie n t h e a t c o n d u c t i v i t y a n d a t t h e s a m e tim e b e n o n - c a t a l y t i c .

I n v e s t i g a t o r s , In s e a r c h i n g f o r a m e a n s o f h e a tin g - s a t u r a t e d h y d r o c a r b o n s t o t e m p e r a t u r e s r e q u i r e d f o r a c e t y l e n e p r o ­ d u c t i o n , f i r s t c h o s e t h e e l e c t r i c a r c a n d s i l e n t a l e c t r i c a l d i s c h a r g e m e th o d s . I t w a s p o s s ib le b y p a s s i n g a r a p i d s t r e a m o f h y d r o c a r b o n g a s o r liq u id t h r o u g h t h e a r c o r s i l e n t d i s c h a r g e , to h e a t i t to a v e r y h i g h t e m p e r a t u r e a n d b y q u ic k ly q u e n c h i n g t h e m i x t u r e to o b t a i n a p p r e ­ c i a b l e q u a n t i t i e s o f a c e t y l e n e . H o w e v e r , in o r d e r to o b t a i n g o o d y ie ld s i t w a s n e c e s s a r y t o o p e r a t e u n d e r r e d u c e d p r e s ­ s u r e o r in t h e p r e s e n c e o f a n i n e r t d i l u e n t . I n e m p l o y i n g t h e s i l e n t e l e c ­ t r i c d i s c h a r g e t h e h y d r o c a r b o n g a s w a s p a s s e d t h r o u g h t h e a p p a r a t u s a t a lo w p r e s s u r e o f t h e o r d e r o f .01 to 0.1 a t m . T h u s , o n a c c o u n t o f t h e m e c h a n i c a l d i f ­ fic u ltie s I n v o lv e d a n d t h e h ig h n o w e r r e q u i r e m e n t s t h e e l e c t r i c a l m e t h o d s d id n o t a p p e a r to o f f e r a d v a n t a g e o v e r p r o ­ d u c i n g a c e t y l e n e t h r o u g h c a l c i u m c a r ­ b id e .

I n t h e a c c o m p a n y i n g t a b l e a r e s u m ­ m a r i z e d t h e e n e r g y r e q u i r e m e n t s p e r lb . C2H2 a s d e t e r m i n e d b y i n v e s t i g a t o r s u s i n g e l e c t r i c a l c r a c k i n g m e th o d s .

I t w ill b e n o te d t h a t th e a v e r a g e r e ­ q u i r e m e n t Is a b o u t 4.5 k w h . p e r lb . o f a c e t y l e n e . I n c a l c iu m c a r b i d e m a n u ­ f a c t u r e t h e r e Is a p o w e r e x p e n d i t u r e o f a b o u t .1,000 k w h . p e r to n o r 1.5 k w h . p e r lb . N o w w h e n w e c o n s i d e r t h a t i t r e q u i r e s a b o u t 3 lb . o f c a l c iu m c a r b i d e to m a k e 1 lb . o f a c e t y l e n e , t h e e l e c t r i c a l e n e r g y is s u b s t a n t i a l l y t h e s a m e f o r t h e tw o m e th o d s . C o n s e q u e n tly , t h e e c o ­ n o m ic s o f C sH j p r o d u c t i o n b y p y r o l y z l n g h y d r o c a r b o n s w i t h e l e c t r i c a l e n e r g y d o

n o t m a k e i t a p p e a r a t t r a c t i v e . Kwh.

Hydrocarbon per Lb.

Investigatore Cracked Acetylene

L’Air Liquid Society3 GaaOil 4 .9 ’

Petere and Pranschke13 M ethane 4.7

P eters and W arner11 M ethane 5.1

Gmelin and Eiscnhut13 „ M ethane 5.35

Eisenhut, Stadler and M ethane 4.3

Baumann53 Methane 4.3

Baumann, Stadler and M ethane and 4 .3 5 -4 .9

Schilling1* Homologues

Eisenhut, Schilling and M ethane 5.4*

Baumann1*

Baumann, Stadler and Propane 4.2

Schilling13

Miloslavskii and Gliz- Solar Oil 4.2

menenko17

•F or Acetylene and C arbon Black.

CHEM ICAL & M ETALLURGICAL E N G IN E E R IN G J U L Y 19/.2

Top of the vertical furnace sh o w in g w ater- cooled, m ercury-sealed p ack in g glan d

character and the am ount form ed continues to increase u p to about 1,250 deg. C.

Table I I shows a sim ilar pyrolysis study on propane in which the crack­

ing: range was extended to lower tem­

peratures. Substantially the same contact times were used as in the case of n a tu ra l gasoline which makes possible a direct com parison o f the two as potential, commercial raw m aterials. Inspection o f the results, shown plotted in Figs. 1 and 2, re­

veals g rea t sim ilarity. The m ain differences noted are th a t pro p an e cracks to optim um yields o f acetyl­

ene and ethylene a t somewhat lower tem peratures and the over-all yields o f desirable products are consider­

ably im proved. In fact, b etter yields are expected a t lower tem peratures since the am ount o f hydrocarbon feed converted to carbon monoxide "and carbon dioxide is~ less, as is also 'th e am ount o f carbon and ta r formed.

N oteworthy, as w ith n a tu ra l gaso­

line, is the fa c t th a t p ractically no m ethane was form ed below 1,000 deg.

C., although a t this tem perature 91 percent of the p ro p an e had disap­

peared. However, approxim ately 73

1,100 1,200 1300 Temp, D eg. C

F ig. 1— Y ields of variou s products irom p y ro ly sis of nalural g a so lin e

percent of the p ro p an e had been con­

verted to hydrocarbons containing two carbon atoms—ethane, ethylene and acetylene— with only about 13 percent and 3 percent o f propylene and benzene, respectively, being form ed. This behavior o f p ro p an e d uring pyrolysis in the lower tem per­

atu re ran g e gives us an insight into th e probable mechanism of the crack­

ing. The predom inant reaction a p ­ pears to be the production of methyl, m ethylene and possibly m ethine r a ­ dicals which then combine to form ethane, ethylene and acetylene. A t higher tem peratures, above 1,000 deg.

C., m ethane form s as a side reaction a t the expense o f ethane, a p p ro x i­

m ately 25 percent of the ethane dis­

a p p e a rin g by this route. F rom the p oin t where the ethane disappears there are no fu rth e r quantities of m ethane o r the defines form ed. This would tend to show th a t a t high tem­

p era tu re s no m ethane is form ed a t the expense o f the u n sa tu ra te d hy­

drocarbons. A t still higher tem per-

Tar and carbon-.

)p00 1,100 T e m p , Deg. C

F ig. 2— Products ob tain ed b y p y ro ly sis of p rop an e in laboratory furnace

atures, as indicated in Table I, the m ethane begins to crack.

SEMI-WORKS TUBE FURNACES A fte r determ ining the optim um conditions fo r acetylene cracking in the la boratory fu rn ace as regards steam dilution, tem p eratu re and con­

ta ct tim e, em ploying various sta rtin g m aterials, the next task was to d u p li­

cate the results on la rg e r scale and in u n it sizes th a t could be expanded directly to commercial scale.

The first step was to build a gas- fired fu rn a ce with la rg e r carborun­

dum tube. As in the lab o rato ry f u r ­ nace, it was necessary to use core­

busters to obtain th e high gas veloc­

ities a t short contact tim e fo r high ra te s o f heat tran sfe r. The first fu rn ace was horizontal containing a single tube. I t was increased in size as la rg e r tubes became available from the m anufacturer.

In order to obtain the high tem ­ p e ra tu re level w ithin the tubes it was necessary to m aintain a very high flame tem perature in the com-

T able I — P y r o ly sis of N atural G a so lin e Sam ple N o.

Volume in crease...

C arbon balance— Percer Gaa analyses—Percent

C arbon dioxide A cetylene...

B u ty le n e ...

B en zen e...

O xygen...

H y d ro g en ...

C arbon monoxide.

M e th a n e ...

E th a n e ...

N itro g e n ...

1 2 3 4 5 6 7 8 9

1016 1068 1106 1128 1186 1252 1306 1344 1370

3 .3 0 3 .6 7 3.9 9 4 .2 3 4 .5 4 5 .2 0 5 .85 6.20 6 .4 8

9 2.4 93.1 92 .9 9 2.4 9 0 .7 8 8 .4 8 5 .0 8 5 .6 8 1 .2

0 .4 0 .4 0 .4 0 .5 0 .5 0 .5 0 .5 0.8 1.1

1.5 5 .5 6 .9 9 .3 11.6 15.4 16.9 17.5 16.5

3 8 .5 3 3 .8 3 4 .4 3 1 .8 2 7 .7 18.3 11.5 9 .6 7 .7

10.6 11.5 7 .7 6.0 3 .2 0 .9 0 .3 0.2 0.1

0 .4 1.1 0 .5 0.1 0.1 0.0 0.0 0.0 0.0

-- --

0 .5 0 .9 0 .9 1.1 0.8 0.6 ^{0 .4}

0.2 0.0 0.1 0.1 0.1 0.2 0.2 0.2 0.0

20.1 2 3 .1 2 4 .9 26 .7 3 1 .0 3 8 .5 4 5 .6 4 6 .7 5 1 .0

0.6 0 .7 1.2 1 .5 1.7 3 .3 4 .7 6.2 6 .5

1.5 13.9 18.7 2 3 .5 2 3 .6 21 .4 19.1 17.6 16.1

2 6 .5 10.9 4 .7 0.1 0.0 0.0 0.0 0.0 0.0

0.2 0.2 0 .5 0.0 0.2 0 .4 0 .4 0.6 0.6

T able II — P y r o ly sis of Propane

R u n n u m b e r... 1 2 3 4 5 6 7 8 ⁹ 10 11 12 13 14 15 16 17

T em perature. ° C ... soo 850 900 950 1000 ¹⁰²⁵ 1050 1075 1100 1125 1150 1190 1225 1250 1275 1300 1325

Steam d ilu tio n ... 6 .5 6 .5 6 .5 6 .5 6 .5 6 .5 6 .5 6 .5 6 .5 6 .5 6 .5 6 .5 6 .5 6 .5 6 .5 6 .5 6 .5

E x p an sio n ... 1.09 1.16 1.29 1.51 1.64 1.86 1.90 2.1 4 2 .2 8 2.4 2 2.5 6 2 .7 7 3 .0 0 3.11 3.2 6 3.5 0 3 .6 6

P ercen t carbon balance. 100 100 100 100 99 .6 99 .3 9 8 .6 9 8 .0 9 7 .6 96 .4 96 .6 96.1 9 4 .2 9 2 .8 9 2 .5 93 .2 9 1 .5

P ercen t yield—C«Hj +

C2II« ... 1.96 4 .5 2 10.65 20 .3 2 5 .5 36.1 3 7.9 4 7 .5 5 1 .8 5 6 .2 5 8 .7 61 .3 6 1 .0 60 .2 5 8 .8 5 7 .8 5 7 .6

Analysis of cracked gas

— vol. percent.

COj... ... 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0 .3 0.2 0 .4 0 .4 0.6 0.6 0 .7

C sH s

...

0.2 0.2 0 .4 1.1 ^{2 .4} 3 .7 4 .0 6.2 7 .5 8 .9 10.5 1 3.0 14.8 15.8 15.9 16.4 15.3

C1H4... 2 .5 5 .7 12.0 19.4 20 .9 25 .4 2 5 .8 27.1 26 .5 2 6 .0 2 4 .0 2 0 .3 15.7 13.3 11.2 8 .9 8 .3

Cj H e... 1.9 4 .2 7 .0 8 .4 7 .7 6.8 ^{6 .7 5 .3 4 .6 3 .5 2 .7 1.4 0 .9} 0.6 0 .4 0.2 0.0

C elle... 0.8 0 .9 0.8 0 .9 1.0 0 .9 0 .7 0 .9 0.8 0.8 1.0 1.2 1.1 1.0 1.1 0 .9 0 .7

O*

... --

_{0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.0 0.1 0.1 0.1}

H i ... 4 .0 6 .7 11.3 16.1 I S .9 2 3 .0 23.4 2 7 .3 3 0 .0 32 .6 3 5 .0 3 9 .0 4 3 .5 4 5.7 4 7 .8 4 9 .8 5 1 .7

C O ...

--

_{0.1 0.1 0.1 0.1 0 .3 0 .4 0 .5 0.8 0 .9 1.2 2.0 2 .7 3 .2 3 .9 5 .7 7 .2}

C H i...

-- -- _ _ -- --

3 .3 6 .3 15.5 17.6 20.1 2 1 .4 21.1 20 .4 19.9 18.6 17.0 15.7

C jH «... 10.7 15.5 22.0 33.7 4 0 .0 36 .2 3 2 .3 16.7 11.6 6.6 3 .5 1.4 0.2 0.0 0.0 0.0 0.0

C iH s ... 79.8 0 6 .5 46.1 20.1 8.8

-- --

_{0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0}

N *...

-- -- -- -- --

0.2 0.2 0 .3 0 .3 0 .3 0 .3 0 .3 0.2 0.1 0 .4 0 .4 0 .3

SO— 7 • J U L Y 19.',2 . CHEMICAL & M ETALLURGICAL E N G IN E E R IN G

T able III— P y ro ly sis o i N atural G asolin e with Recirculation ol E thylene

R u n n u m b e r... 1 2 3 4 5 6 7 C alc.

T em p eratu re, ° C ... . . . 1310 1266 1308 1290 1290 1306 1307 1300

M ol fraction—gasoline. . . 0.214 0.162 0.208 0.211 0.199 0.224 0.217 0.215

— recycle... . . . 0.78G 0 .8 3 8 0.792 0.789 0.801 0.776 0.783 0.7 8 5

Steam d ilu tio n ... 4 .5 4 .5 5 .0 4 .4 4 .0 4 .4 4 .S

Expansion—m easu red ... . . . 2 .5 5 2.12 2 .44 2.34 2 .37 2.21 2 .5 8 ---

— calcu la te d ... 2.54 2.0 9 2 .4 2 2.3 7 2.32 2.4 6 2.5 4 2 .4 0

P ercen t carbon b a la n c e .. . . . . . 92 .5 9 1.6 8 9.9 9 0.4 9 0.4 87 .1 89.1 9 1.3 Percen t yield C2II2...

Analysis of cracked gas

— vol. percent

5 3 .5 53 .2 49.4 48 .9 46.4 51 .5 4 8 .4

CO2... 0 .4 0 .4 0 .4 0 .4 0 .4 0 .4 0 .5

C2H2... 14.5 16.0 15.4 14.7 14.8 15.4 15.4

C2H4... 18.3 14.8 17.0 17.3 16.1 14.6 18.3

CaHe... 1 .0 1 .0 0 .8 0 .8 0 .8 0 .8 0 .5 0 .9

C ells... O.G 0 .8 0 .9 0 .8 0 .8 0 .6 0 .6 1.1

O2... 0 .2 0 .2 0 .2 0 .2 0 .2 0 .2 0 .2

I I2... . . 4 0.1 3 7 .7 4 1 .0 3 9 .0 3 8.8 40 .9 4 1 .8 3 8.5

C O ... 5 .3 3 .0 3 .8 3 .3 3 .5 3 .4 4 .5 3 .3

cir<... . . 2 1.1 23.1 2 1 .8 2 2 .8 2 2.9 2 2.4 19.9 21 .4

Nj... 0 .6 0 .4 0 .3 0 .3 0 .6 0 .4 1.2 0 .4

bustion chamber. This was accom­

plished by em ploying an a ir preheat o f 500-000 deg. C. P re h e a t w as ob­

tained from the combustion gases leaving the cracking chamber and passing through an auxiliary p re ­ h eater section. The incoming hydro­

carbon feed and steam m ixture was likewise heated“ to 800 deg. C. in alloy steel coils in the same p reheater assembly.

Although laboratory cracking r e ­ sults were duplicated w ith the various hydrocarbons processed, refra cto ry and mechanical difficulties arose.

Trouble was soon encountered with the horizontal ty p e o f furnace due to sagging o f the carborundum , al­

though the unsu p p o rted tube span was only over a 4-ft. length. A t first this was thought to be due to rig id ­ ity of connections a t the two ends of the tube but the sagging still p e r­

sisted a f te r flexible water-cooled con­

nections were provided a t the tube ends. The strain s were a p p a ren tly induced by com pression and tension a t the top and bottom respectively, because the tubes failed from circum ­ feren tial cracks a fte r only a few days.

I t is to be pointed out th a t we w’ere a ttem p tin g to operate in an unex­

plored field fo r carborundum tubes, as f a r as tem perature and ra te of heat tra n sfe r through the wall was concerned. Also the tubes were la rg e r in diam eter and length than had been fab ricated heretofore. The illustration (p. 79) shows one type of horizontal furnace. The gas-steam and a ir p reh e ate r is shown above the furnace enclosed in the vertical shell.

In the attem p t to obtain im proved tube life it was decided to build a vertical furnace. I t was designed fo r a carborundum tube 4 in. i.d. x 5 f in. o.d. and 8 ft. in length, provided with a 3J in. diam eter core-buster of the ty p e to be described. The bot­

tom of the tube was rounded to fit into a machined water-cooled seat made tight with an asbestos-lined

CHEMICAL & M ETALLURGICAL E N G IN E E R IN G . J U L Y 19.’,2 • copper gasket. The top o f the tube extended through a loose hole in the refra cto ry lining. The top of the tube was gas tight, yet perfectly free to move in all directions by a sylphon type packing gland“ w ater cooled and provided with a m ercury seal.

In o p erating the fu rn ace the gas- steam m ixture, preheated to 800 deg.

C., entered the bottom of the tube where the pressure was balanced with respect to the combustion chamber su rrounding the tube by the use of a Ila g a n regulator. The balance was m aintained by o p eratin g a by-pass valve on the N ash blower pulling the gas through the tube. A t the high*

gas velocity a 3 lb. p e r sq.in. pressure drop occurred from the bottom to the top of the tube and yet the top seal was gas-tight.

The underside of the domed top had a suspended lining of high-alum ina, re fra c to ry shapes. The accom panying illustration shows the dome, the top of which was water-cooled. The water- cooled, m ercury-sealed packing gland is also visible. Connecting with the gland was a 2-in. w ater cooled pipe 15 ft. in length which cooled the cracked gas to 400 deg» C. before it entered a gas seal box type of quencher. The velocity o f the gas was so g re a t and consequently the heat tra n sfe r was so high th a t no ta r de­

posited in the wall o f the tube. In other words, the inside wall tem pera­

ture was never lower th a n the dew- poin t o f the ta r. Based on this experi­

ence a fire-tube boiler, designed fo r the same ra te o f heat tran sfe r, would be p ractical on a la rg e r u n it to gen- T ypes of core-busters. O ne sh o w n at

the left proved most satisfactory

erate steam fo r pow er required in concentrating the gas and the neces­

sary low pressure steam fo r gas dilu­

tion.

A considerable study was m ade of core-busters. The most satisfacto ry was one with smooth sides and with centering lugs. A center hole was provided fo r insertion o f the therm o­

couple.

The furnace was fired by two tan- gentially placed burners“ located near the top o f the furnace. They were provided with sylphon dia­

phragm s to take up unequal expan­

sion due to the use of preheated air.

O peration o f the vertical tube f u r ­ nace was much more successful than with the horizontal type. A fte r a period of over a y e a r’s operation on a 24-hr. basis, a three month tube life was established. Yields of acetyl­

ene were equal to those obtained in the laboratory". Carbon was blown on the average every 36 hr., while on the laboratory fu rn ace it had to he blown every hour.

RECIRCULATORY CRACKING Inspection o f Table I, containing results on n a tu ra l gasoline cracking, indicates th a t Sam ple 6 represents about the optim um cracking condi­

tion. Acetylene and ethylene are p resent to the extent of 15.4 and 18.3 percent respectively. F o r g re a t­

est economy of raw m aterial both the acetylene and the ethylene should be utilized. A sim ple cost com putation will show th a t the process would not be very attractiv e if operated only fo r acetylene unless cracking were carried out a t a considerably higher tem perature.

I t seemed most likely th a t in the m a jo rity of eases it would be most

Sem i-works reg en er a tiv e furnace with s e a l box ty p e of quencher