CHEMICAL
Ł m e t a l l u r g i c a l
ENGINEERING
ESTABLISHED 1902 S. D. KIRKPATRICK. Editor
APRIL, 1942
“ B e c a u s e , T o o L it t le a n d T o o L a te
P r e s i d e n t H o t c h k i s s o f R e n s s e la e r P o ly te c h n ic I n s t i t u t e is a c a r e f u l s t u d e n t as w ell as a g r e a t a d m ir e r o f R u d y a r d K ip lin g . W h e n c e r ta in m u n i
tio n p l a n t s w e re c lo sin g d o w n f o r c e r ta in F e b r u a r y b ir th d a y s , h e w e n t to h is l i b r a r y a n d d u g u p th e se fa m o u s lin e s o f B r i t a i n ’s m i l i t a n t p o e t :
E P IT A P H , 191S The b a tte ry ’s out of am munition, s i r ! I f any m ourn us a t the shop, say
“W e died bccause the sh ift kept holiday."
A s w e m o v e s till f u r t h e r in to o u r o w n w a r p r o g r a m , th e g r e a t p ro b le m t h a t is obvious to u s a ll is th e n e e d to s p e e d p ro d u c tio n —-to r i d o u r w a r m a c h in e , on ce a n d f o r all, o f th e d e p lo ra b le a n d d a m n a b le slo w d o w n s t h a t a r e so m e tim es co st
in g u s 30 o r 20 o r ev e n 50 p e r c e n t o f v ita l o u tp u t.
So D r. H o tc h k is s , w ith h is m in d on B a ta a n a n d B a ta v ia , fo llo w e d M r. K i p l i n g ’s le a d w ith th e se s t i r r i n g w o r d s :
E P IT A P H , 1942
F o r lack of ships and planes and tanks W e lie here w here we fought, in serried ranks, Because, too little and too late,
The sh ift m ade six instead of eight.
T h a t, p e r h a p s , is n e g a tiv e p sy c h o lo g y a n d th e r e f o r e c o n tr a s ts u n f a v o r a b ly w ith th e p o sitiv e fig h t
in g slo g a n s o f D o n N e ls o n ’s lie u te n a n ts in th e W a r P r o d u c tio n d riv e . Y e t to som e o f u s n o th in g b r in g s th e w a r h o m e so q u ic k ly a s th e c a s u a lty lis ts a n d th e u n c o lo re d r e p o r ts o f v a l i a n t fig h tin g a g a in s t en e m ie s t h a t a r e n o t o n ly n u m e ric a lly s u p e r io r b u t b e t te r e q u ip p e d a n d b e t te r s u p p o r te d b y a i r a n d n a v a l fo rc es.
G r a d u a l ly th e p e o p le o f th is c o u n try , le d b y th e p a r e n ts a n d re la tiv e s o f th e b o y s a l r e a d y i n th e A r m y a n d N a v y , a r e g e t tin g m a d . T h e y a r e in n o m ood to trifle w ith th o se w ho offer excuses f o r s o m e th in g less th a n “ a l l - o u t ” p ro d u c tio n . T h e y a r e g e t tin g tir e d o f c o n g re ssio n a l w r a n g lin g s o v er
w ag e s a n d h o u rs , o f la b o r a n d m a n a g e m e n t b ic k e r in g o v e r “ u n io n s e c u r i t y ” a g r e e m e n ts , o f p o litic a l p e rs e c u tio n s o f A m e r ic a n i n d u s t r ia lis ts w h o se o n ly f a u l t h a s b ee n t h a t th e y h a v e b e e n too b u s y w ith w a r w o rk to w a ste tim e fig h tin g in th e c o u r ts f o r th e ir o w n d e fe n se . T h e tim e h a s com e f o r a sh o w d o w n w ith a n y b o d y a n d e v e ry b o d y w ho is n o t p r o v in g b y h is e v e ry a c tiv i ty t h a t f r o m n o w on Avar p r o d u c tio n com es f irs t!
T h e jo b to be d o n e is n o t in W a s h in g to n , ev e n th o u g h w e look th e r e f o r b e t te r le a d e rs h ip . “ T h e w a r w ill be w o n ,” s a id L lo y d G eo rg e in 1917. “ in th e w o rk s h o p s a n d la b o r a to r ie s o f i n d u s t r y . ” T h a t is ev e n m o re t r u e to d a y in th is c o u n t r y t h a n i t w as i n E n g la n d th e n . W e ’v e g o t to p r o d u c e s h ip s a n d ta n k s a n d p la n e s a t h ig h e r r a t e s a n d in b e t te r q u a l ity t h a n a n y o th e r n a tio n o r g r o u p o f n a tio n s in h is to ry . W e ’ve also g o t to h a v e m o re poAvder a n d a m m u n itio n a n d b e t te r Aveapons.
T h is is th e f ir s t a n d m o st p r e s s in g c h a lle n g e t h a t o u r ch e m ic al in d u s tr ie s m u s t m e e t. N o th in g c a n b e p e r m i tte d to in t e r f e r e Avith b u ild in g , e q u i p p in g , m a n n in g a n d o p e r a tin g th e m a n y neAv p l a n t s n ee d e d to m a k e m u n itio n s . B u t o f a lm o s t e q u a l im p o r ta n c e is th e n e e d f o r l i t e r a l l y h u n d r e d s o f c r itic a l c h e m ic a ls a n d s tr a t e g ic m e ta ls t h a t a r e e s s e n tia l som e p la c e in th e Avar p r o g ra m . I t is in th e se p la n ts t h a t c h e m ic a l e n g in e e r s w ill f in d t h e i r b e s t c h a n c e to h e lp in s p e e d in g p r o d u c tio n . O b v i
o u sly th is c a n se ld o m b e d o n e b y p u t t i n g o n m o re s h if ts o r u til iz i n g id le e q u ip m e n t, b e c a u s e Ave a r e a l r e a d y a p p r o a c h in g o u r lim its th e re . B u t th e r e a r e m a n y p la c e s, Ave su s p e c t, Avhere y ie ld s ca n be in c re a s e d o r q u a l i t y im p ro v e d b y in te n s iv e a p p l i c a tio n o f e n g in e e r in g knoAvledge a n d m e th o d s. A feAV good m e n w ith n o o th e r jo b s th a n to sm o o th o u t th e w rin k le s , e lim in a te lo s t m o tio n a n d Avaste effo rt, Avill m o re th a n e a r n t h e i r p a y in m o s t p la n ts . O u r b ig g e s t n e w s u p p ly o f e s s e n tia l raAV m a te r ia ls is th r o u g h b e t t e r u til iz a tio n o f Avhat Ave
a r e n o w w a s tin g . N o one k n o w s th is b e t t e r t h a n th e c h e m ic a l e n g in e e r w ho is r e a lly 011 h is jo b . N o o n e c a n h e lp m a n a g e m e n t m o re in m a k in g th e m o s t o f w h a t w e ’v e g ot.
W e, th e m e n w ho m a n A m e r ic a ’s w o rk s h o p s a n d la b o ra to r ie s , m u s t m a k e c e r ta in n o w t h a t th e e p i ta p h s w h ic h w ill be w r i t t e n o n A m e r ic a n g r a v e s in f a r -a w a y c o u n tr ie s w o n ’t s a y t h a t d e a th cam e
“ B e c a u se , too lit tle a n d too la te , th e s h i f t m a d e six in s te a d o f e i g h t ! ”
INDUSTRIAL AMERICANIZATION
O x Fe b. 16, 1942. th e S e c r e ta r y o f th e T r e a s u ry , u n d e r a n e x e c u tiv e o r d e r s ig n e d b y th e P r e s id e n t o f th e U n ite d S ta te s , to o k tit le to a p p r o x im a te ly 97 p e r c e n t o f th e s to c k o f th e G e rm a n -o w n e d G e n e ra l A n ilin e & F ilm C o rp . E a r l y in M a rc h f o u r w id e ly k n o w n A m e r ic a n e n g in e e rs a n d e x e c u tiv e s w e re n a m e d b y th e T r e a s u r y a s a m a n a g in g b o a r d to d ir e c t th e a tf a ir s o f th e c o r p o r a tio n a n d to o p e r a te it as a n A m e r ic a n c o m p a n y . O n e o f th e i r n u m b e r, R o b e rt E . M c C o n n ell, m in i n g e n g in e e r, c h a irm a n o f th e E n g in e e r s D e fe n se B o a r d a n d f o r m e r O P M official, w a s e le c te d p r e s id e n t a n d c h a ir m a n o f th is m a n a g in g b o a r d w h ic h c o n s is te d o f A lb e r t E . M a rs h a ll, p r e s id e n t o f R u m f o r d C h e m ic a l W o rk s , G e o rg e M. M o ffett, c h a ir m a n o f th e b o a r d o f C o rn P r o d u c t s R e fin in g Co., a n d R o b e rt E . W ils o n , P r e s id e n t o f P a n A m e r ic a n P e tr o le u m & T r a n s p o r t Co. a n d f o r m e r p e tro le u m c o n s u lta n t, to O P M . S u b s e q u e n tly M r. M c C o n n ell a n n o u n c e d th e a p p o in tm e n t o f th r e e o p e r a tin g e x e c u tiv e s : M r. M a rs h a ll to s e rv e as firs t v ice p r e s i
d e n t ; J o s e p h S . B a te s , p r e s id e n t o f th e B a te s C h e m ic a l Co. o f P h ila d e lp h ia , to b e v ic e p r e s id e n t i n c h a r g e o f p r o d u c tio n , a n d D r. W illia m F . Z im - m e rli, f o r m e r E u r o p e a n te c h n ic a l d ir e c to r o f th e d u P o n t C o m p a n y , to s e rv e a s vice p r e s id e n t in c h a r g e ot‘ r e s e a rc h a n d p a t e n ts .'
T h u s th e d ec k s a r e c le a re d f o r a n e x p e r ie n c e in A m e ric a n iz a tio n w h ic h w ill b e w a tc h e d w ith a b s o r b in g in te r e s t f o r a n u m b e r o f d if f e r e n t r e a s o n s . I n th e f irs t p la c e , g e n u in e A m e r ic a n c o n tro l is o f g r e a te s t s tr a t e g ic im p o r ta n c e b e c a u s e t h i s $67,000,- 000 o ffs p r in g o f th e I . G. F a r b e n i n d u s t r i e A . G.
o w n e d m a n y p a te n ts , c o v e r in g in v e n tio n s t h a t a r e e s s e n tia l to m o d e rn w a r f a r e a s w ell a s to p e a c e tim e p ro g re s s o f th e p h a r m a c e u tic a l, d y e s tu ff, c h e m ic al a n d p h o to g r a p h ic in d u s tr ie s . H e n c e it is e s s e n tia l t h a t th e s e re s o u rc e s b e r i d c o m p le te ly o f G e rm a n c o n tro l a n d in flu e n c e in o r d e r t h a t th e y m a y se rv e A m e ric a n w a r n ee d s.
A se c o n d r e a s o n t h a t th is m o v e is so s ig n ific a n t lie s in th e f a c t t h a t i t is th e firs t tim e th e TJ. S.
G o v e rn m e n t h a s ta k e n o v e r a n a lie n in d u s t r ia l p r o p e r t y a n d tr ie d to o p e r a te it as a g o in g e n t e r p ris e . T h is is in m a rk e d c o n t r a s t w ith th e p r a c tic e s o f th e A lie n P r o p e r t y C u s to d ia n in th e la s t w ar. W e a r e a s s u re d b y th e d ir e c to r s a n d th e T r e a s u r y D e p a r tm e n t t h a t th is is n o t to b e a y a r d s tic k to m e a s u r e g o v e rn m e n t vs. p r i v a t e o p e r a tio n , b u t it m a y w e ll .s e r v e as a m o d e l f o r h a n d l in g
o th e r f o re ig n p r o p e r tie s w h o se f u n d s n o w f ro z e n in th e T r e a s u r y D e p a r t m e n t w ill a g g r e g a te a p p r o x im a te ly $7,000,000,000.
F i n a l l y th e r e is n o d o d g in g th e f a c t t h a t th is p a r t i c u l a r p r o p e r t y is a “ b lu e c h i p ” in th e i n e v ita b le p o k e r g a m e a t th e p e a c e t a b le w h e n th is w a r is o v e r. G e rm a n y u s e d it to p la y f o r p r e t t y b ig s ta k e s — as th e A m e r ic a n lin k in a p r o je c te d c h a in to c o n tro l w o rld o r g a n iz a tio n o f c h e m ic a l i n d u s t r y . U n c le S a m w ill r e m e m b e r t h a t w h e n t h e tim e com es. M e a n w h ile lie h a s p u t th e p r o p e r t y in th e c a p a b le h a n d s o f h o n e s t, te c h n ic a lly t r a i n e d A m e r ic a n s w h o se sole p u r p o s e w ill b e to co n se rv e its re s o u rc e s f o r th e p u b lic good.
ARNOLD, RUBBER, W AR AND TREASON
Mo s t h e a r te n in g o f a ll t h e n e w s to com e f ro m W a s h in g t o n th i s m o n th is th e a n n o u n c e m e n t t h a t t h e t r u s t - b u s t i n g a c tiv itie s o f T h u r m a n A r n o ld a r e to b e p o s tp o n e d f o r th e d u r a t i o n o f th e w a r ,—
t h a t is, w h e re v e r e i th e r th e S e c r e ta r y o f W a r o r N a v y fe e ls t h a t th e p r o s e c u tio n w o u ld d e la y th e w a r effo rt. H a d th is a g r e e m e n t com e tw o y e a r s ago, w e w o u ld h a v e h a d m o re a lu m in u m , m a g n e s iu m , p o ta s h a n d a m m o n ia w ith w h ic h to fig h t th is w a r . L ik e w ise, in o u r o p in io n , w e w o u ld h a v e h a d m o re s y n th e tic r u b b e r d e s p ite th e c h a rg e s m a d e in t h e v itr o li c a t ta c k o n th e S t a n d a r d O il C o m p a n y (N . J . ) b y th is sa m e ze alo u s c r u s a d e r w h e n h e a p p e a r e d b e f o r e th e T r u m a n C o m m itte e o f th e S e n a te .
I t is q u ite s ig n ific a n t, w e b e lie v e , t h a t th e m o r a t o r iu m o n t r u s t - b u s t i n g w a s d isc lo se d a t th e e n d o f th e sa m e w ee k in w h ic h M r. A r n o ld h a d u s e d th e S e n a te in v e s tig a tio n a s a s o u n d in g b o a r d f o r b r o a d c a s ti n g th e s a m e s e n s a tio n a l c h a rg e s w h ic h h e h a d j u s t w ith d r a w n f r o m a n a n t i - t r u s t s u i t a g a in s t th e c o m p a n y in o r d e r to o b ta in a c o n s e n t d e c re e . T h u s lie g o t w h a t h e p r o b a b ly w a n te d m o st— p u b lic ity f o r h is c o n te n tio n s w h ile m o re o r less e ffe c tiv e ly s p ik i n g th e g u n s o f th o se w ho n o w h a v e no c h a n c e to h a v e t h e i r d e fe n s e h e a r d b e fo re a n i m p a r t i a l t r i b u n a l .
C h e m . ti- M e t. r e a d e r s w h o h a v e fo llo w e d th e c o u rse o f th e m a n y te c h n ic a l d e v e lo p m e n ts t h a t h a v e r e s u lt e d f r o m th e J e r s e y c o m p a n y ’s o rig in a l r e la tio n s w ith th e G e rm a n I . G. k n o w t h a t th e U n ite d S ta te s h a s b e n e f itte d g r e a tly fr o m th e s e i n t e r n a t i o n a l e x c h a n g e s o f te c h n o lo g y . L ik e w ise, m o st o f u s h a v e a p r e t t y go o d id e a a b o u t th e c h a r a c te r a n d m o tiv e s o f th e c h e m is ts, e n g in e e rs a n d e x e c u tiv e s w ho h a v e fig u re d so p r o m in e n tly in th e s tr e a m o f in v e n tio n s t h a t h a s flow ed o u t o f th e o r ig in a l tr a n s a c t io n f o r th e h y d r o g e n a tio n p a te n ts . T o in s i n u a te t h a t th e s e m e n w e re d is lo y a l to th e U n ite d S ta te s o r a s S e n a t o r T r u m a n p u t it, g u ilt y o f “ t r e a s o n ” to t h e i r o w n g o v e rn m e n t, is a n i n s u l t w h ic h w e c a n jo in M r. F a r i s h in c o n d e m n in g w ith
“ in d ig n a tio n a n d r e s e n t m e n t . ”
U n f o r tu n a te l y , th e w h o le s y n th e tic r u b b e r p ic t u r e is so c o m p lic a te d w ith a c c u s a tio n s a n d d e n ia ls , c h a r g e s a n d c o u n te r-c h a rg e s , t h a t th e A m e r ic a n
7-1— .} A P R I L 19.',2 . CHEM ICAL & M ETA LLU R G IC A L E N G IN E E R IN G
p u b lie is r e a d y to b e lie v e a lm o s t a n y t h in g . I t is lo o k in g f o r a s c a p e g o a t a n d w h e re c o u ld a b e t t e r one be f o u n d th a n in o u r la r g e s t c o r p o r a tio n w h ich f o r a d o z e n y e a r s h a s b e e n d e a lin g n o t o n ly w ith t h e G e rm a n s b u t also w ith th e I t a l i a n s a n d th e J a p a n e s e ? T h a t th e s e r e la tio n s w e re w ell k n o w n to e v e r y b o d y — som e o f th e m a c tu a lly c a r r ie d ou a t th e in s is te n c e o f o u r S ta te D e p a r t m e n t— a ll m e a n s n o th in g n o w t h a t th e w itc h h u n t is on in e a r n e s t. B u t i t is p r o b a b ly b r i n g i n g som e s n ic k e rs
a n d p e r h a p s so m e s n e e r s f o r d e m o c ra c y f ro m B e r lin a n d th e “ B ig H o u s e ” o f th e I . G. a t F r a n k f o r t - am -M a in . S tr a n g e l y e n o u g h , w h e n G e r m a n y d e c id e d to fig h t a t o ta l w a r in v o lv in g a n a ll- o u t m o b iliz a tio n o f h e r te c h n o lo g ic a l a n d in d u s t r ia l re so u rc e s, sh e d id n o t s t a r t b y p ill a g in g th e e x e c u tiv e s o f I . G. F a r b e n w ho c o u ld c o n t r i b u te m o s t to h e r w a r e ffo rt. T h a t w o u ld h a v e b e e n s a b o ta g e a n d r e a l tr e a s o n o v e r th e re . H e r e it is so cial r e f o rm , p o litic a l c a p ita l a n d p e r s o n a l p u b lic ity .
W A S H I N G T O N H I G H L I G H T S
PRIORITIES m ean little any more unless they are very high in the A series. So m any people have been given some so rt o f a p rio rity ratin g th a t the goods actually available can
n ot go very f a r down the list. This S p rin g it a p p e a rs th a t anyone with less than a A -l-j p rio rity can get no copper a t all. Thus the p ro g ram of replacing p rio ritie s w ith allocations builds up more and move momentum.
A nyone who m ust have som ething in order to do business fo r Uncle Sam m ust see to it that he gets a definite allocation o f the required m aterials, w hether they be w ar m aterials or m aterials o f construction. I t is no longer safe merely to have a p rio rity rating.
SPEED. NOT COST, is the prim ary criterion fo r an aw ard to bidders who com pete f o r business on w ar con
tracts. U nder the plan o f negotiated contracts, a preference is also given to sm all firms over big ones since the sm aller firms can usually handle sim pler jobs and the big firms are reserved fo r m ore com plicated and difficult assignm ents. W here new con
struction is required before m anu
fa c tu re o f needed goods can begin, the bidder has preference who im poses a minimum requirem ent fo r scarce m achinery, equipm ent and m aterials of construction. All these considerations show how f a r Uncle Sam has varied his buying practices to meet w artim e conditions.
CONTAINER SHORTAGES seem likely to develop. Bottles, ja rs and other glass containers, as well as tin cans and metal packaging m aterial, are affected. F o r a time it ap p eared th at the glass shortage m ight be due to lim ited supplies of soda ash. Now it is evident th a t two other facto rs will have a much earlier and more serious influence. Rubber, cork and other very scarce m aterials fo r closure gaskets are going to be se
verely restricted. In fact these m a
terials may be prohibited fo r m any types o f goods. Only a little less im minent is the restriction on the use of metals fo r closures. A lthough the problem of g ettin g m etals is going to be difficult no m a tte r w hat container is ordered, extensive re-use is being urged on every division of industry.
SECRECY in in d u stry disappears as m ilitary secrecy increases. Process industries will be disturbed to note two possibilities th a t may resu lt from over-zealous adm inistration of F ed eral regulations. U nder the guise of proving th a t a corporation is entitled to an explosive license, the lawyers of the D epartm ent o f the In terio r may p ry into m inute detail of your com pany’s stock ownership. The effect ap p e ars like malicious med
dling but may have to be tolerated.
L ittle less objectionable is the recent authorization by Presidential order th a t the Office o f P rice A dm inistra
tion may inspect corporation tax rate s in the form of transcripts.
There is nothing to indicate th a t this does not lay open much of the con
fidential inform ation of corporations to unfriendly scrutiny.
FREEZING OF LABOR RELATION
SHIPS seems to be one answer to the slow-down problem . So lrn g as the labor situation is subject to ju ris dictional disputes, possible changes in working conditions and wages, the worker is distracted from his main job o f all-out production. M ean
while m anagement is constantly plagued with demands th a t m ust soon be answered, cnce and fo r all.
INVENTORIES have been rising despite shortages o f raw m aterials.
Balance sheets for 15 leading chemi
cal companies fo r 1041 reported in ventories of $300,008,000 com pared with $248,382,000 in 19-10—u p about 20 percent. F o r industry as a whole the rise is estimated at more than a th ird o f last y ea r’s stocks.
CHEMICAL PRODUCTION GOALS
rise constantly. W ith m ilitary de
m ands as now anticipated, it is almost unbelievable th at there will lie su r
pluses o f any im p o rta n t chemicals no m atter hew hard the in d u stry may work on expanding production sched
ules. T em porary exceptions to this rule are expected, as, for example, instances where it is difficult to find storage space a t the point o f produc
tion because o f delays in sh ip p in g in structions or facilities. B ut the over
all dem and for w ar chemicals seems insatiable.
STORAGE FACILITIES i n m a n y chemical p la n ts will be strained to the lim it. U nder cu rren t im pending increases o f demand, irreg u larities in tran sp o rta tio n make it necessary th a t every m anagem ent plan for m axi
mum possible storage space fo r in coming raw m aterials, p a rtly finished goods in process and finished p ro ducts. No one can foretell the em erg
ency that may increase the need fo r any or all of these facilities. W ise executives and engineers will have th eir plans well laid.
PRICES, in the opinion o f some W ashington observers, are now get
ting out of hand. The situation is described as “dangerously explosive.”
Inflation in natio n al income to the extent of a t least 20 billion dollars in 1042 is alm ost certain.
RESEARCH LABORATORIES, as well as control laboratories, using certain specified chemicals defined as “ in
gredients o f explosives” m ust have licenses before they can buy or use such m aterials. R esponsible persons in charge o f these m aterials m ust keep a careful record o f use or dis
position. T h eft or loss must be pro m p tly rep o rted or serious penalty may follow if diverted m aterials are used fo r sabotage. All o f the techni
calities o f w artim e are involved in this set o f rigid and restrictive rules.
CHEMICAL & M ETALLURGICAL E N G IN EER IN G • A P R I L 19.',2
P rod u cin g S m o k eless P ow der By 1942 M ethods
R. E. HARDY
Colonel, U. S. Armyc h e m . & M e t I N T E R P R E T A T I O N ...
This article an d the pictorial flo w sh e e t on p a g e s 110-113 d escrib in g op eration s in on e of the n e w sm o k e le ss p ow d er p la n ts it is h o p ed w ill se rv e the u sefu l pu rp ose of instructing n e w operators in this a n d sim ilar p la n ts in the op eration s w ith w h ich th e y w ill b e con cern ed . A lso this inform ation sh ou ld b e of a ssista n c e to ra w m aterial a n d egu ip m en t su p p lies of th ese p la n ts a n d th o se still to b e built.—
Editors.
O
n e o f t h e w orld’s g rea test w ar machines f o r the production o f com bat equipm ent is being built by the O rdnance D epartm ent of the U. S. A rm y. This m ulti-billion dollar program , which is already p a rtly com pleted, consists o f num erous departm ent-ow ned factories fo r the m an u factu re o f rifles, m achine guns, cannon, tanks, bombs, shells, am m uni
tion, gunpow der, am monium nitrate, picric and other acids, toluene, etc.
C reated shortly a fte r the R evolu
tio n a ry W ar, the O rdnance D e p a rt
m ent ever since has had the responsi
bility o f designing, developing, m anu
fa c tu rin g and p ro cu rin g the w ar m a
te rial used by the arm y, which in cludes 1,200 m a jo r items, 250,000 com ponents. S ta rtlin g innovations in the realm o f m unitions have con
sta n tly stemnied fro m the research and m a n u fa ctu rin g arsenals o f the O rdnance D epartm ent. T heir in fluence on in d u stry in general has been profound. Through th eir efforts
A m erica’s com bat m ateriel today is su p e rio r to th a t o f an y country in the world. Also u n d er th e guidance of the O rdnance D epartm ent, A m er
ican factories are fa s t being con
v erted to the production of these m any w ar items.
Included in the d ep a rtm en t’s build
in g p rogram are smokeless pow der p lan ts. T ypical o f these is a p la n t which covers an . are a o f several thousand acres, and which cost in the neighborhood o f $100,000,000. Sev
eral h u ndred buildings w ith a com
bined floor space o f m ore than 2,000,- 000 sq. ft. were erected. I t was neces
sa ry to build 50 miles o f autom obile roads and lay 67.5 miles o f sta n d ard gage railro a d track w ithin this area.
Service pip in g , including steam , w ater, brine, fire and electric, totals 186 miles, and fo r sewage and ad d i
tional 27.5 miles. There are 15 miles of w ire fencing.
The w ater su p p ly is n o t taken from a river. To avoid the necessity fo r filtration, wells were sunk through a pproxim ately SO ft. o f sand and gravel close to the shore of the river.
These are of the R anney w ater col
lector type. M otor-driven pum ps will su p p ly ap p ro x im ately 50,000 g.p.m.
The w ater is pum ped into two reser
voirs, each o f immense capacity.
A djoining the two reservoirs are two steam -electric plants. Consider
able distance sep arates each pow er p la n t an d reservoir from the other pow er p la n t and reservoir. A n elec
tric transm ission line in the form of a loop connects the two pow er units so th a t in case one fa ils cu rre n t can be sent from the other to the affected areas.
The 11 kv. distribution loop has 5.3 miles o f pole line with 54 steel transm ission towers. C u rren t a t 2,300 volts is distributed through 39 miles of pole lines. In addition there are 46.4 miles o f pole lines fo r road and fence lighting. The telephone and fire alarm system s utilize 25 miles of cable.
The base o f smokeless pow der is nitrocellulose, m ade by n itra tin g cel- Cannon powder blending house equipped with drop hoppers. When
the trap door of a lilted hopper is pulled, powder drops onto an inverted umbrella-shaped bafile
I
76— .} . A P R I L 191,2 . CHEM ICAL & M ETALLUR GICAL E N G IN E E R IN G
Powder is first pressed into blocks so that it can be handled easily.
It is being charged into a screening press by the operator lulose. AVood or cotton can be used
as the source o f cellulose, b u t as wood contains ligniri, which m ust be elimi
nated, cotton is employed a t this p la n t as the source fo r cellulose. Cotton linters are used, since long staple cotton balls up and plugs slu rry lines and valves. I f the su p p ly o f linters should run low, it can be replaced w ith long stap le cotton which has been chopped up. Oils and other im p u ritie s in the cotton are removed with a sodium hydroxide treatm ent and the cotton is then washed free of alkali an d bleached. Cotton received is already processed to this stage. The first treatm en t given it here reduces the external m oisture. Since the heat o f dilution o f sulphuric acid by this m oisture would be considerable with subsequent danger of fires du r
ing n itra tin g , drying is im perative.
This is accomplished in a long con
tinuous conveyorized oven heated by rad iatio n w ith steam pipes, the cotton being fluffed out o f the solid bales a t the entrance.
M ilitary nitrocellulose is composed o f a m ixture o f high-grade nitrocel
lulose and pyro-nitrocellulose. The first o f these contains an excess of nitrogen and contributes ease of igni
tion and high potential characteris
tics, the la tte r contains a small am ount o f nitrogen and acts as the vehicle fo r the insoluble v arie ty (the high-grade ty p e is insoluble in ether-alcohol).
In the n itra tin g process the cotton, a fte r being weighed into fiber cans, is sent by conveyor to the th ird floor o f the n itra tin g houses where there are several g roups o f charging hop
pers these su p p ly the d ip p in g pots suspended below the floor. F o u r p o ts are included in one n itra tin g unit. Cotton and n itra tin g acids are charged into the d ip p in g pots. Be
neath these pots and on the second floor are several w ringers, one serv
ing each of fo u r d ip p in g pots. Sus
pended u nder the w ringers are im m ersion basins serviced with water.
The fo u r pots, w ringer, and one im mersion basin m ake a com plete n itra t
ing unit. In operation the pots are dipped in th e ir order, p ro p e rly timed so th a t by the tim e the fo u rth p o t is dipped, the first charge is ready to be dropped into the w ringer. N itro cellulose is discharged from the w ringer into the immersion basin, drowned w ith w ater, and flushed into slu rry tanks.
A system o f collecting pipes from the d ip p in g pots conducts acid fumes to a cyclone where the n itric acid is dissolved in w ater fo r concentration and reuse.
Im p u ritie s rem ain to be washed out
in the next building in the line. This operation is known as the boiling tub procedure or stabilization. W ith the cellulose is always some degraded or decomposed cellulose known as hydrocellulose or oxyeellulose. As cellulose is treated with n itric acid, n itric esters of other substances are also obtained. There also accum ulate sulphuric esters as a resu lt o f ester- fication with sulphuric acid. The function of the boiling tub house is to remove these foreign ester im p u ri
ties which are inherently unstable and unsatisfactory.
The slu rry entering the boiling tubs contains a small am ount of acid ex
pressed as sulphuric. The acid is th a t resulting from the dilution o f the acid le ft in the nitrocellulose a fte r n itration. The acidic solution is pum ped over to the boiling tub house where it is p u t into wooden tubs and heated indirectly with steam which is introduced under a false bottom.
A fte r the boil is complete, the m a
terial is ru n out of the tubs and p u t into another interm ediate slu rry tank.
A ny free acid is neutralized with sodium carbonate, b u t the nitrocel
lulose m ust be broken up to get a t the acid held between the micelle and fibrils o f the fibers. This is accom
plished, together with p rep a ra tio n for colloiding, in the p u lp in g house. The
line is still divided into high-grade and py ro nitrocellulose.
To accom plish the p u lp in g the alkaline slu rry is passed through a series o f three Jo rd a n refiners and pum ped to the poacher house. The final neutralization is accom plished here by the addition of m ore sodium carbonate. I le a t and agitatio n in sures the reaction between the acid and sodium carbonate. Boilings, set
tlings, decantations, and rew aterings follow, an d the residual sodium ca r
bonate and salts are removed by cold w ater washes. A fte r each boiling and washing, the slu rry is allowed to settle and a t least 40 percent of vol
ume m ust be decanted.
Each high-grade and py ro poacher charge is analyzed and then pum ped to huge vats w ith um brella baffles and ag itato rs in the blending and w ringer house, and blending produces th e de
sired nitrogen content. A fte r a sam ple o f the blend has been approved by the laboratory, nitrocellulose is dew atered as much as possible before going to the d ehydrating press.
C entrifu g in g reduces m oisture in pyrocotton to desired percent. The p ro d u ct is now held in tra n sfe r cars ready fo r the smokeless pow der area.
Smokeless^ pow der was the chief p ro p ellan t d u rin g the W orld W ar,
CHEM ICAL & M ETALLURGICAL E N G IN E E R IN G • A P R I L 10.’,2 /,— n
Strings or ropes of powder are cut into p ieces of desired length and then loaded into cans for conveying
Block of nitrocellulose being ejected from dehy
drating press. N ew charge appears above
b u t it had two serious defects which have been corrected since. F irs t, m oisture was absorbed by pyro pow ders; and second, the combustion pro d u cts o f the pow der flashed (burned) a t the muzzle. D eviation from ballistic sta n d a rd was caused by m oisture absorption by pyro pow ders used during the W orld W a r which were quite hygroscopic. Com position of du P o n t “ F N H ” and “ N i l ” pow ders perm its adju stm en t of m oisture to norm al hum idity a t average tem p era tu re and because o f composition, is much less hygroscopic than pyro powders.
P roduction lines in the smokeless pow der area s ta rt w ith a dehydration press house. H ere w ater p rese n t in the nitrocellulose is removed and alcohol is substituted. The n itro cellulose is charged into a hydraulic press and compressed by a low -pres
sure ram . Alcohol is forced in a t the bottom o f the press under a higher pressure, displacing the w ater. This process is aided by a p a rtia l vacuum applied through p erfo ra tio n s in the ram head.
The pressure exerted by this ram is then increased and some o f the alcohol forced out o f the cake. E nough alcohol is left in the block so th a t all alcohol requirem ents will be sa tis
fied fo r the colloidizing action within the m ixer house.
A ctual colloidizing is accomplished in the m ixer house where the de
h ydrated alcohol-containing blocks are charged into m ixers. In a few m inutes the action breaks up the blocks and p a rtia lly m ixes the n itro cellulose and insoluble Compounding
agents, and then ether containing a stabilizer and plasticizer is added.
These ingredients act as plasticising agents and control the b u rn in g of the finished product, and thus aid in the elim ination o f flash. The ingredi
ents used form a fa irly com plete colloid o f the nitrocellulose and affect the hygroscopicity o f the nitrocel
lulose to a much g re a te r extent than would be expected from the p ercen t
age com positions. Thus the W orld W a r difficulty o f absorption of w ater by pyro pow ders is eliminated. W hen pow der decomposes, nitrogen-oxide fum es ( N 0 2) are given off which rea ct w ith m oisture to form nitric acid. The acid, in tu rn , catalyzes the decompositions o f nitrocellulose. The stabilizer reacts w ith the N 0 2 and removes it.
M aterial fo r cannon pow der is mixed fo r a given tim e, and since rifle pow der m a n u fa ctu re differs from this point, f u rth e r discussion will deal only w ith cannon pow der.
The colloidal form ation is completed in m ixers o f a slightly different type, known as m acerato rs; then blocked in presses f o r convenience in h a n dling.
The n ex t building in line is the screening and g rain in g house. H ere the pow der is p u t through screens in a press in order to remove lum ps and im purities. This is called a m aca
roni press, as pow der comes out in strin g or rope-like form . This pow der is blocked once m ore and then sent to grain in g presses which extrude the pow der through screens followed by a p erfo ra ted die. S trin g s or ropes of pow der so obtained are then sent to a
cu tter where pow der g rain lengths are regulated.
Removal o f alcohol and eth er is accom plished by d istilling the solvent out o f the g rain s w ith hot a ir and then p assin g th e a ir through a con
denser in order to rem ove th e solvent.
The pow der is p u t into covered cars which are sent to the solvent recovery building. H ere a ir heated by steam coils is passed through the cars and then p a rtia lly by-passed through a condenser w here much of the picked- u p solvent is condensed. By-passed and unby-passed a ir is sent back over the coils fo r recirculation.
A fte r p assin g through the dump shed house, the uniform pow der is conveyed to th e w ater-dry-house on a conveyor, o r pum ped by fa s t flowing w ater and p u t into storage tanks in the w ater-dry-house. H ere the r e m aining solvent is removed. W a te r p reheated by steam is pum ped through the tanks so th a t the solvent m ay be quite rap id ly dissolved out o f the pow der grains. A p o rtio n of the w ater in the tub is alw ays throw n aw ay with the differential am ount of w ater being made up from a hot w ater ta n k within the w ater-dry- house. This procedure is followed until the residual solvent left in the pow der g rain s has been decreased to a low percentage. A fte r the pow der lias been in the w ater-dry-tanks fo r the required length of time, the re
moval o f solvent is considered com
plete. The pow der now contains w ater and small am ounts o f ether and alco
hol, and the rem oval of th a t w ater is le ft to the so-called C. C. (control circ u latio n ) dry-house. H ere the mass
78— .$ . A P R I L 191,2 • CHEM ICAL & M ETA LLUR GICAL E N G IN E E R IN G
CHEM ICAL & M ETALLURGICAL EN G IN EER IN G • A P R I L 10!,2 • 1 ,-7 0 is dum ped into a bin and hot air,
obtained by passing a ir over a steam coil, is passed through the pow der for a sufficient length o f tim e to b rin g the m oisture content down to an aver
age value to be expected under no r
mal conditions of tem p eratu re and hum idity. The pow der is now finished as f a r as the actual m an ufacturing processes are concerned.
Blending is next in order, and blending' lowers w ith drop hoppers a re provided fo r this purpose. W hen the tra p door of a filled h o p p er is pulled, the pow der drops onto an in verted um brella-shaped baffle, is scat
tered, and collected in another hop
per. This procedure is carried out u n til a good blend is obtained. The pow der is then sent to the packing houses, weighed into containers, which are then sealed, air-tested, stenciled, and routed to the shipping and storage houses.
Rifle pow der m anufacture differs in th a t the pow der is coated with v arious ingredients in order to con
trol the ra te o f burning. A graphite coat com pletes the series o f steps in the operation.
A description o f the acid and organic areas is now in order. N itric acid is made in the acid area by the direct oxidation of ammonia. The am m onia is received in liquid form in tank ears and stored. I t is first volatilized in a vaporizer equipped w ith steam coils and then mixed with hot. air. This m ixture is passed into a catalytic converter in which the fundam ental chemical reaction occurs.
The resulting nitrogen oxide gases a re cooled in a heat exchanger and p a rtia lly condensed in a bank of con
densers. The vapors are eventually p u t through an absorption tower and the condensate leaving the condenser as dilute n itric acid is also sent to the abso rp tio n tower. C ounter-current scrubbing o f the rising vapors results in 60 to Cl percent n itric acid.
Gases from the top o f the absorp
tion tow er are passed through a p o r
tion o f the h eat exchanger, through which the hot converted gases are sent, rem oving laten t heat from the converted gas while being themselves heated. A fte r accom plishing this cooling, the warmed gases are ex
hausted to the atm osphere through secondary com pressors which pum p 40-45 percent of the air npeded fo r the oxidation process.
I f it is to be used fo r nitrocel
lulose GO percent acid m ust be con
centrated to approxim ately 92 p e r cent strength. Therefore, it is mixed w ith 92 to 96 percent sulphuric acid and concentrated. F irs t, the m ixture
of nitric and sulphuric acids is p re heated by steam coils and then sent into the top o f a dehydrating column packed with chemical ware. F rom here it goes into a series o f steam- heated boiler tubes and the heat drives the nitric acid gases'back into the bottom of the dehydrating column.
The n itric gases rise in the column and dilute nitric acid falls down, thus producing a strip p in g action.
The sulphuric acid, since it is not volatile and is combined with water, is concentrated fo r reuse. The nitric acid vapors are then passed through a bleaching column, also packed with chemical ware, and thence to a eon- denser where the n itric acid is con
densed out. I t is now 92 to 95 percent nitric acid.
The organic area is divided into
several sections. In the first, benzene is reacted with n itric and sulphuric acids to form nitro-benzene. The nitrobenzene is reduced to produce aniline, which is then either reacted catalytically under p ressure with heat to form diphcnylam ine, o r is allowed to rea ct with m ethyl alcohol and sulphuric acid to obtain dim ethylani- line.
Smokeless powder is employed almost entirely as a pro p ellan t, and when finished is either stored or shipped out to n ea rb y p la n ts fo r bag or shell loading, as the ease m ay be.
i f it is to be incorporated in the com
plete round, it is loaded in to the cartrid g e shell cases. If, on the other hand, it is to be used in large guns as sep arate charges, it is loaded into cloth bags.
Graining presses extrude the powder through screens followed by a perforated die. Strings are then sent to the cutters
Powder is put through screens in a macaroni press in order to remove lumps and impurities. This powder is blocked once more
P rod u cin g a Rubber-Like Synthetic
EDITORIAL STAFF ARTICLE
R
e s i s t a n t to a high degree againstre frig e ra n t gases and organic solvent m aterials including petroleum products, chlorinated, arom atic and alip h atic hydrocarbons, an d ketones, the rubber-like synthetic known as Resistoflex P V A is finding a p p lica
tion in num erous types o f use ra n g ing from w ork gloves and aprons, to fuel, lubricant, hydraulic and vacuum hose f o r land and a ir tran sp o rta tio n equipm ent. V ersatility in m ethods o f fabrication is one fa c to r accounting fo r the diversity o f applications. The m aterial m ay be extruded as tubing, molded into sheets fo r gaskets, washers and diaphragm s, cast, lam i
nated and dipped. M olded sheets may, if desired, be re-molded f o r the production of various types o f molded m echanical goods.
A nother fa c to r co ntributing to versatility is the fa c t th a t by vary in g the com pounding, both physical and chemical pro p erties can be altered considerably so as to a d a p t the p ro d uct to widely - varying requirem ents.
F o f example, although Resistoflex
P Y A com pounds generally tend to shrink slightly in the presence of m ost solvents, this characteristic can be modified so as to produce a slight swelling action u nder the same use conditions. The m aterial has ex
trem ely high (ensile strength, elonga
tion, recovery and toughness, and these p ro p ertie s are only very slightly aiieeted by exposure ti> most solvents.
Polyvinyl alcohol is the base m a
terial which is modified in the com
pounding and processing so as to produce distinctive properties. The com pounding is carried out by R e
sistoflex Corp. a t the com pany’s Belle
ville, X. J ., p la n t. The p relim inary m ixture is produced in a sim ple r ib bon ty p e m ixer and the batch, which a t this stage is neither coherent nor plastic, is then p u t through a heated roller mill, em erging as a thin, co-
herent sheet somewhat resem bling crepe rubber. This step, in which roll tem p eratu re and the thickness of the sheet produced are both carefully controlled, results in incipient fusion of the com pounded particles, and a
“sin terin g ” together o f ad jacen t particles.
FORMING OPERATIONS The com pounded sheet is the sta rtin g p o in t fo r the subsequent op erations which m ay be either ex tru sion o r molding. The first m ethod is used fo r tub in g and the second fo r sheet m aterial which can be cut into gaskets o r washers, or can be re molded fo r the production of mechan
ical goods. In either event, the p res
sure and h eat to which the incom plete
ly fused sheet is subjected results in com pleting the fusion o f the particles and ad ju stin g the final solvent con
te n t w ithin accurately held lim its. The m aterial so produced is a tough, tenr-
(1) Alter the compound is mixed, it is milled on heated rolls to produce a sheet of care
fully controlled thickness and solvent content. (2) The milled sheet is fed in continuous lengths to an extruder from which it em erges as tubing. (3) Tubing lea v e s the extruder die and is carried to the wind-up by a canvas-belt conveyor for cooling. (4) Tubing is reinforced by one or more layers of fabric, using special high-speed braiders. Wire
covers are applied on some constructions by similar equipment.
resistan t plastie, having an am or
phous stru ctu re which is best de
scribed as a solidified colloidal solu
tion.
Although resins of this type have been known fo r nearly 20 years, they have l)ecn seriously considered only in the la st ten. Some five years ago the A m erican and C anadian p atents on the processing o f this class of m aterials were purchased by Resisto- flcx Corp. which then set about the developm ent o f methods fo r large- scale commercial production. E x trusion had already been practiced but one o f the first problem s of the com pany was perfection o f this p ro cess. I t was found to be p articu la rly difficult to assure accurate dim en
sional control, but the problem was solved with a heated die and the ad a p ta tio n o f existing autom atic con
trol equipm ent which was modified on the basis o f extensive experim ent.
Control o f the tension in the extruded tube, produced by the belt which con
veys the tube from the die, was also a difficult task which was finally solved by a sensitive electric control which senses the tube tension, m ain
taining it a t the desired value by con
trol o f a variable speed transm ission driving the belt.
T ubing can be extruded in a v ari
ety o f diam eters ran g in g from about Ys to 1 in. Leaving the die, it is carried by a canvas cooling belt some 40 or 50 ft. to the p o in t where it is wound on a large m etal reel, to aw ait fu rth e r processing. D epending on the requirem ents of each construc
tion, the hose produced is reinforced by a num ber of layers- of cotton or m etal braid, applied by high-speed braiders of special design. An outer coating is provided of rubber, syn
thetic rubber, wire o r lacquer, as re quired.
INFRA-RED DRYING
The hose lacquering operation is especially interesting. A drying tower has been developed, the inner surface of which is lined with brightly p o l i s h e d chrom e-plated sheets. A battery of in fra -re d drying lam ps is used, d rying the lacquer a t rates up to 4,000 ft. p e r hour. As m any as 12 passes o f hose can be threaded through the tower, to allow
as m any coats o f lacquer to be a p plied. The coatings, incidently, are appled by Resistoflex P V A w ipers which a re said to give much longer life in this service th a n other m ate
rials th a t have been tried.
A considerable p a r t o f the com
p a n y ’s o u tp u t o f hose an d tub in g is in the form of finished hose assem blies, cut to length and supplied with a variety o f coupling designs sp u n or pressed on to the hose ends.
Resistoflex P V A sheets are p ro duced by the sim ple process of mold
ing the crude milled sheet between heated platens in a hydraulic press.
I f desired fo r added strength, fab ric backing or inserts can be fused to the stock a t this stage. The m aterial can then either be delivered to the user in sheet form , or die-cut to desired final dimensions.
F o r d ip p in g operations, as in the production of gloves, Resistoflex P V A is dissolved in a suitable m ix
tu re of solvents to form a viscous solution in which the porcelain form s arc dipped, much as in the p roduc
tion of dipped ru b b er goods. A prons and sim ilar products are made by coating fab ric with such a solution.
F o r perm ission to inspect the p lant, and fo r assistance with the m anu
script, Chem. & Met. is indebted to E. S. P eierls, president o f Resisto- flex Corp.
(5) This coating and drying tower can apply a s many as 12 lacquer coats to braid- covered tubing at speeds up to 4,000 It. per hour. (6) Looking downward inside the lacquer-drying tower; the infra-red drying lamps are clearly visible. (7) Here finished and semi-finished tubing is stored on metal reels. (8) One of the tests for finished hose is to subject it simultaneously, on this machine, to temperature, pressure, flexing, vibra
tion and torsion. (9) Flat sheets are molded by pressing between heated platens.
P sychrom etry of C oolin g Tow ers
EDWARD SIMONS
Engineer, Redwood Manufacturers Co., San Francisco, Calif.Chem . & M e t I N T E R P R E T A T I O N
Three y e a r s a g o C hem . & Met. p u b lish ed a group of articles on the fu n d am en tals of w ater co o lin g tow er d esig n . P ractical inform ation w a s g iv e n to a ssist in a ctu a l d esig n . S in ce their a p p ea r a n c e , there h a v e b e e n a num ber of d ev e lo p m e n ts in both theory a n d practice.
A n e w series, prep ared b y the sa m e author, brin gs the subject up- to-date. The introductory article, p resen ted here, is a quick r ev iew of fu n d a m en ta ls a n d a tie-in w ith the p rev io u s series.— E d ito rs .
P
SYCHROJviETRY is the branch of physics th a t tre a ts o f the measurem ent o f the degree o f m oisture, especially the m oisture mixed w ith the air. The basic tools o f this science are the gas laws, the principles of heat exchange, and the principles of m olecular diffusion. I t is often neces
sary fo r the engineer to use psyehro- metric form ulas, even though he has lost the intim ate im pression o f the fundam ental actions. This article is a review o f some of the basic p rin ciples and a projectio n o f the p rin ciples into the field of cooling tower design and operation.
A w ater cooling tow er m ay be de
fined as an a p p a ra tu s in which the tem p eratu re o f circulated w ater a p proaches the wet-bulb tem p eratu re of circulated a ir d u rin g the h eat in te r
section th a t occurs between the a ir and the w ater.1 D u rin g the evapora
tion which occurs with the heat ex
change, the w ater which is evaporated changes from a liquid to a vapor.
Therefore, the m aterials involved in the tow er process are liquid water, w ater vapor, and gaseous air.
A closed container which is p a r tially filled w ith w ater is illustrated in F ig . l a ; the container and its con
tents are m aintained a t a constant tem perature. The portio n of the con
ta in er space which is above the s u r
face o f the w ater is originally evac
uated. The molecules in the w ater are considered to be in a state of ra p id motion w ith a mean velocity depend
ing on the tem p eratu re of the water.
Some molecules a t the su rface are able to escape from the liquid because th e ir velocities are sufficiently high to p ro je c t them into the vacuum. As this molecular- escape continues, some o f the vaporized molecules strik e the
surface o f the liquid from which they em anate, and again become p a r t of the liquid. W hen the num ber of molecules re-entering the su rface is ju s t equal to the num ber o f molecules leaving it, a balance is established be
tween the two phases, and the molecules which finally occupy the space o f the original vacuum exert a p ressu re on the walls o f the con
tainer. This p ressu re is called the pressure o f the sa tu ra te d v ap o r or sa tu ra tio n pressure. This p ressu re depends upon the n a tu re o f the liquid and upon the tem perature.
A sim ilar container in which the space above th e w ater level is origi
nally occupied by a ir is shown in F ig.
l b ; the container and its contents are held a t the sam e tem p eratu re as the container o f F ig . la . I f the p ressure in th e space above the w ater does not m aterially exceed one atm osphere, the tendency o f th e w ate r molecules to escape is the same as in the ease of the container o f F ig . l a , since the voids between the a ir p articles are sufficiently large and num erous to enable the sa tu ra tio n process to proceed. However, the vaporized molecules do not distribute them selves so ra p id ly throughout the ves
sel, since collisions w ith the a ir molecules ac t to re ta rd the v ap o riz a
tion. Consequently, the w ater evapo
ra te s m ore slowly into a ir th a n into a vacuum, b u t eventually the sa tu ra tio n p ressu re o f the w ater v apor is built u p to the same in ten sity th a t it would develop if the a ir w ere n o t present.
The p a rtia l p ressu re o f th e w ater v ap o r is independent o f th e gas (a ir) which is also p rese n t in the container.
D alton’s Law states th a t in a m ix
tu re of gases the p ressu re of each constituent gas is independent o f the
presence of the others, and each gas exerts a p a rtia l p ressu re th a t is equal to the pressure which it would exert if it occupied the entire volume o f the m ixture a t the tem p eratu re o f the m ixture. F urtherm ore, it states th a t the p a rtia l pressures o f the constit
uents are additive. Therefore, the total p ressu re o f a m ixture is the sum o f all of the p a rtia l pressures o f the constituents. D alton’s Law m ay be ap p lied to m ixtures o f dry air and w ater w ithout the introduction o f significant error. The total pressure o f a m ixture of a ir and w ater v ap o r is commonly the barom etric pressure and is equal to the sum o f the p a r tial pressures o f dry a ir and w ater vapor.
The p e rfe c t gas equation m ay be w ritten
P V , = 1,543wTr/ M „ (1) where
P is the total absolute pressure in lb.
per sq. ft. V, is the total volume in cu. ft., w is the weight of the gas in lb. in volume V„ Tr is absolute temperature in deg. R. { Tr = deg. F. + 460) and is the molec
ular weight of the gas.2“
. M oisture-free a ir has the following average analysis :!b
L b . in P c rc c n t M o le - 1 m olal C o m p o n en t b y c u la r volum e V olum e W e ig h t of a ir O xygen ( O j ) ... 2 0 .9 5 3 2 .0 0 0 .7 0 N itro g e n ( N t ) ... 7 8 .OS 2 8 .0 2 2 1 .8 8 C arb o n dioxide (CO2) . 0 .0 3 4 4 .0 0 0 .0 1 A r g o n ,e t c ... 0 .9 4 4 0 . 0 .3 8
T o ta l w eig h t of 1 m ol of a ir i s ... 2 8 .9 7 Ibt
Sim ilarly, f o r w ater v a p o r :
A tom ic L b . in 1 m olal C o m p o n e n t W eig ht volum e of v a p o r H y d ro g e n (H2) ... 1 .0 0 8 2 .0 1 0 O xygen ( O ) ... 1 6 .0 0 1 6 .0 0 T o ta l w eig h t o f o n e m ol o f w a te r v a p o r .. . . I S . 02 lb.
The weight o f a column of m ercury one sq. ft. in area and one in. deep is 70.73 lb. Therefore, w here a column of m ercury is used as a p res
sure indicator, a v ariation o f one in.
in the indicating column represents a v ariation in the in ten sity o f p res
sure of 70.73 lb. p e r sq. ft. (0.4912 lb.
p e r sq. in.) I f P a is equal to th e pressu re o f a gas in in. H g,
P = 70.73P a (2)
The volume occupied by one lb. of dry, m oisture-free a ir is selected fo r use in E q. ( 1 ) ; accordingly, iv is
82— 4 • A P R I L 19/,2 • CHEM ICAL & M ETA LLUR GICAL E N G IN E E R IN G
equal to one lb. The w eight o f w ater v ap o r associated w ith one lb. o f dry a ir has been variously ca lle d : mixing ratio , p ro p o rtio n ate hum idity, mass or density ratio, absolute hum idity and specific hum idity. In this article, this q u an tity is given the symbol H ; and, since the lb. o f dry a ir is used as a basic un it, I I is defined as the hum idity o f the a ir fo r the purposes o f this article. Eq. (1) is used as follo w s:
For air, 70.73 (B - M V„
= 1,543 X 1 X n / 2 8 . 9 7 (3) For water, 70.73p« V ,, =
1,543// T „ / 18.02 (4) Eq. (4) divided by Eq, (3) yields
p . / ( B - p.) = 28.97///18.02 (5) or
H = 0.6220p . / ( B - p.) (6) I n the preceding equations, P „ is equal to the p a rtia l p ressure o f w ater v a p o r in the air, and B is equal to the barom etric pressure, both are ex
pressed in inches of m ercury.
The value of P„ m ust be known in o rder th a t Eq. (6) m ay be solved. I f the w ater in the container of Eig. lb were m aintained a t a constant tem
p e ra tu re d u ring the saturation process, the a ir in the u p p e r p ortion o f the container would become sa tu ra te d a t the tem p eratu re o f the water, and the te m p eratu re o f the a ir would be the tem p eratu re o f adiabatic satu
ratio n . On th e other hand, if it were possible to expose the portio n of the container above the w ater to a moving stream o f a ir of infinite quantity, the w ater in the lower p a r t o f the con
ta in e r would ultim ately assume the tem perature o f adiabatic saturation o f the a ir supply. The wet-bulb tem p e ra tu re of the a ir determ ined by a p ro p e r psychrom etric technique may be used as th e te m p eratu re of adia
batic satu ratio n . C arrier’s equa
tion 3‘ m ay then be used in the follow
ing fo rm :
Pa = \Pu> (B Pit;) (l tw) ]
/(2,800 - LSI.) (7)
F ig . l a
Vacuum
Wafer molecules Safurafe space a f A
p r e s s u r e p i \ XXX XXX XXX -Cons fa r t f ----
tem pera fure F ig . ' b
+ + + +> 'Air molecules + + + + + + + +* af pressure -+ + + -f -*-X X X + + + +
Wafer / X X X
+ + + + molecu/es + + 4- 4
— --- Tofal pressure. _____________
B,;(B-pa )+pa C o n s ł a n ł
NOMENCLATURE B = Barometric pressure, in. Hg.
C , = Volume of air per minute passing through a given tower cross section, cu. ft.
per min.
G = Bate of air flow through tower, lb. bone dry air per min.
H = Air humidity, lb. of water vapor per lb. bone dry air.
H, = Saturated humidity, at 1'», lb. water vapor per lb. dry air.
L = Water rate through cooling tower, lb. per min.
M . = Molecular weight of a gas, general case.
p„ = Partial pressure of water vapor in the main air stream, in. Ifg.
p* = Saturated pressure of water vapor at the wet bulb temperature, in. Hg.
P = Absolute pressure, lb. per sq. ft.
l ’a = Total absolute pressure, atm.
P o = Pressure of a gas, in. Hg.
r„ = Latent heat of vaporization of water vapor at t„, B.t.u. per lb.
t = Temperature of the air-water mixture, or dry-bulb temperature, deg. F.
t«. = Wet-bulb temperature.
T = Bulk temperature of the water, deg. F.
T* = Absolute temperature of a gas, deg. Rankine.
Vo = Total volume of a gas, cu. ft.
Vh = Humid volume of air, cu. ft. moist air containing 1 lb. dry air.
w = Weight of a gas, lb.
- = The Sigma Function, in main air stream, B.t.u. per lb. dry air.
= = Denotes sensible equivalence.
S U B S C R I P T S
T = Refers to conditions at water temperature, T.
w = Refers to the wet-bulb condition.
1 = Refers to the conditions at the air entrance and water- exit of a counter-flow tower.
2 = Refers to the conditions at the water entrance and air exit of a counter-flow tower.
where
p. = actual partial pressure of water vapor in the air, in. Hg.; p„ = saturation pressure at wet-bulb temperature, in. Hg. (Table I gives values of the saturation pres
sures at intervals of 0.1 deg. F.);
B = barometric pressure, in. Hg.;
I = dry-bulb (air) temperature, deg.
F.; i«, = wet-bulb temperature, deg.
F.
The volume which is occupied by one lb. of d ry a ir and its associated w ater vapor is known as the humid volume of the air-w ater m ixture. I f Fh is used to designate the humid volume, Eq. (3) may be rew ritten as follow s:
70.73 (B - p.) V„ = 1543 J V 2 8 .9 7 (8a) Vh = 0.7531 T * /( B - p.) (8b)
o f Fig. I a
Thus, if the cubic feet p e r m inute o f air-w ater m ixture passing through a given cross section o f an a p p a ra tu s are designated by Cv, and if pounds p e r m inute o f d ry air p assin g through this a p p a ra tu s are designated by G,
C. = GVa (9a)
or
G = C./V „ (9b)
The weight o f m oisture p e r lb. of dry air in a m ixture o f a ir and w ater v ap o r depends on the dew poin t tem p era tu re alone. As long as there is no condensation of moisture, the dew poin t tem perature rem ains constant.
L et P , equal the saturated v apor p res
sure a t Tn, and let H . equal the cor
responding satu rated hum idity a t T B.
Then, fo r a given unchanged space (as one cu. f t.) , and with constant tem perature,
p./p. = Relative humidity (10) F o r satu ratio n conditions, Eq. (0) becomes
II, = 0.6220p./(-B - p.) (11) Eq. (6) divided by E q. (11) gives
II/ I I . = p . {B - p . ) / p. (B - p.) (12) The percent hum idity is 10011/I I , ; it is the hum idity o f a ir a t a given tem p eratu re expressed as a percent
age o f the hum idity of sa tu ra te d a ir a t the same tem perature. R elative hum idity is based upon fixed volume;
percent hum idity is based upon fixed w eight of bone d ry air. E q. (12) in dicates th a t percent relative hum idity equals percent hum idity only a t sa tu ration.
I f an air-w ater m ixture is cooled w ithout change of barom etric p res
sure, the p a rtia l p ressure o f the w ater v ap o r will n o t change during the cooling, since the ratio p J ( H —p ,) o f Eq. (6) rem ains constant w ith con
sta n t hum idity. U nder these condi
tions the p a rtia l pressures o f a ir and w ater v ap o r will rem ain constant.
W hen, therefore, the tem p eratu re is decreased un til the a ir becomes sa tu rated, the p a rtia l p ressu re o f the w ater v ap o r becomes a sa tu ra te d p res
sure, the te m p eratu re is the dew- p o in t tem perature, and th e percent hum idity equals the p erc en t relative hum idity. Consequently, the hum idity a t any tem p eratu re is equal to the hum idity a t the dew -point tem p era
ture, and the p a rtia l p ressu re of w ater v apor is equal to the saturated pressure a t the dew-point.
The Sigm a F unction of W . H . C ar
CHEM ICAL & M ETALLURGICAL E N G IN E E R IN G • A P R I L 19Ą2 !,— 83
