R eported b y C. L. Parker. Solicitor of Chemical Pateh ts, McGill Building, 908 G S t., W ashington, D . C.
980,813. Process of L iquefyin g A ir and Separating Out Oxygen.
T h is invention is a process of liqu efyin g a ir and separating gases w ith a p artial recovery of the energ y consum ed b y the com pression. I t differs from older processes v e r y materially in its respect, th at, for th e purpose of reducing the pressure behind the expansion cham ber in th e e xh au st p ort of the ex
pansion engines (piston engines, L a v a l or P arson s’ turbines or the like) the expan ded gases are n ot sucked off b y the com
pressor, bu t b y a special device (suction pum p or the like), thus producing a p artial vacuum in order n o t to le t cold ex
panded gases reenter the com pressor, bu t to drive them out in to the open a ir a fte r u sin g them as far as p ossib le'as cooling m edium for the process itself, in order to ob tain in this w ay a m ixtu re of fluids rich in oxygen . T h is is g rea tly facilitated b y n ot sending back the exp an ded gases in to th e circuit, but by d rivin g them o u t a fte r a m ore perfect exchan ge of h eat has taken place. T he new technical effects gained in th is way o v e r other processes for liq u efy in g air in w h ich the expanded gases, a fte r h a v in g done their w ork, are led off und er atmos
pheric pressure, consist in the first place, in consequence of the greater low ering of the pressure, the fallin g of the temperature is correspondingly greater, th a t secon dly the engine is not stopped as is th e case w ith Siem ens and other sim ilar d evices by a grea t low ering of the tem perature, and th ird ly, th a t the lique
fied gases, w hich are p a rtly evap orated again in the process itself, are evap orated a t a su ita b ly reduced pressure of less than one atm osphere, and in qu an tities corresponding w ith th e vapor tensions of the com ponent parts of the m ixtu re of fluids. For instance, as experim en ts b y D ew ar, E streicher, B aile, Olsze- w iski h a v e sh ow n 1 nitrogen has a t — 19 5 0 C. a vap o r tension of 740 m m ., o x y g en a tension of 142 mm . B y p roducing a re- 1 Cf. Zeitschrift. fur K em prim ierte uiui Fltisstge Case, 2nd year, No.
12, p . 180.
R E C E N T I N V E N T I O N S . 201
duced pressure above a fluid the tem perature is a t once lowered, if sufficient heat is n ot ad m itted for the evap oratio n of the quantities of fluids sucked off. I t is e vid en t th at— as in the present process the tem perature, b y producin g a reduced pres
sure by means of a suction pum p, can easily be low ered dow n to
— 200° or still farther, and as a t these tem peratures, the pro
portion of the vapors of b o th fluid p arts is greater than 740/142, therefore greater than 5— it is necessary to eva p o rate o ver five times as much nitrogen as oxygen . T h is proportion becom es greater with the low ering of the tem perature and is accordin g to Olszewski a t — 2 14 0 60/3.8, or 16. B y p roducing a vacuum of 60 mm., which is tech n ically easy, 16 tim es as m uch nitrogen
as oxygen w ill be evap orated, therefore leavin g n ea rly pure oxygen. T he process is therefore suited for sep aratin g ou t directly alm ost pure liquid oxygen , and b y its distillation correspondingly pure gaseous oxygen .
The accom panying illu stration show s a p lan t for th e liqu e
faction of air accordin g to this process.
The inventor is R u d o lf M ewes, of Berlin, G erm any.
980,940. Electric Induction F urnace.
It has been observed in the operation of induction furnaces that the upper surface of the m eltin g b a th is inclined, in conse
quence of the electro dyn am ic effect exerted betw een the p rim ary winding and the m eltin g bath . F o r exam ple, when the p rim ary winding, or a portion thereof, is arran ged concentric w ith the melting bath, repulsion takes p lace betw een the p rim ary w in d ing and the m eltin g b a th because the curren t induced in the latter flows in the direction co n tra ry to th a t in w hich the prim ary current flows. C on seq uen tly the up per surface of the m eltin g bath assumes such a position th a t th e ou ter edge of the m eltin g bath or th at ly in g .re m o te from the p rim ary w in d in g is higher than the inner edge. T h is exposure has disad van tageo us conse
quences in that, on the one hand, ow ing to the accum ulation
of the electrica lly indifferent slag a t the low places, the higher ly in g places are su bjected to the oxid izin g influences of the atm osphere, w hile on the other hand, practice has shown th at the accum ulation of the slag at the low er ly in g portions causes a rapid destruction of the w alls of the furnace. A ttem p ts h a v e
a lre ad y been m ade to overcom e these difficulties b y superposing, over the p rim ary w inding, a short-circuited a u x ilia ry w inding in w hich a curren t is induced, d u rin g the operation of the furnace, in a direction opposite to th a t of the p rim ary curren t and there
fore cou n teracts the repulsion exerted upon the m eltin g bath b y the p rim ary w inding. B u t this arran gem en t results in a grea t loss of energ y since the a u x ilia ry w in d in g m u st possess a v e ry g rea t resistance in order th a t the curren t induced in it w ill n o t be too strong.
T h e present in ven tion has for its purpose to avo id the dis
a d va n ta g e s recited and a tta in s this purpose b y p ro vid in g means, w h ich electrica lly opposes and restricts the current, w hich is induced in th e a u x ilia ry w in d in g superposed o ver the p rim ary w inding, w hich m eans is so located in relation to the m eltin g batli th a t it has no appreciable influence upon the equilibrium of the m eltin g bath .
T h e accom p an yin g illu stration show s a preferred em bodi
m ent of th e su b ject m a tter of the invention.
T h e in ven tor is C arl G runw ald, of B redeney, G erm any.
. 982,288. Preparation of Nitrogen Compounds.
T h is in ven tion has reference to the m an ufactu re of nitrogen com pounds, such for instance, as lim e nitrogen, etc.
M ore p articu larly, th e in ven tion relates to a process for the preparation of lim e nitrogen w ith o u t free carbon.
In preparing calcium carbid in the electric furnace, calcium oxid is treated w ith an excess of carbon, to form calcium carbid w ith the evo lution of carbon m onoxid. In order to prepare lim e nitrogen, the p atentees ta k e calcium carbid and trea t it in the presence of a flu x and h eat w ith nitrogen togeth er w ith carbon dioxid, to form a resu ltan t p rod u ct con tainin g a p p ro xim ately 35 per cent, of nitrogen. In the accom p an yin g illu stration 1 represents an electric furnace, w herein calcium carbid is produced b y the action of an excess of carbon ate of lim e, or free calcium b y reduction of calcium oxid b y carbon, in the electric arc. In order to ob tain lim e m ixed w ith the d e
sired proportion of carbon, a lim estone reto rt 2 is provided in w h ich lim estone m ixed w ith coal in the desired proportion, accord in g a s calcium carb id or calcium is to be prepared, and burned to lim e and carbon b y heat from gas burners 3. T h e gas used is a m ixtu re of carbon m onoxid from the carbid furnace w ith air, air and ace ty le n e or other su itable gas, so th a t a com p lete com bustion of the gas is ob tained in the re to rt 2, together
202 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y . Mar., i 9n
w ith the hydrocarbons which m ay be contained in the coal itself. From the reto rt 2 the lim e and carbon are discharged in to the electric furnace 1, eith er for producing calcium carbid or for producing pure calcium , accordin g to the proportion of carbon used. T h e gaseous products of the com bustion of the g as a t the burners 3 and volatile con stituen ts of the coal con sistin g of nitrogen, carbon dioxid and w ater, are conducted b y a pipe, 4, through a drier, 5, to rem ove the w ater of com bustion and thence to a tank, 6, con tainin g lime w ater or some other m eans for sep aratin g carbon d ioxid so as to leave pure nitrogen. T he drier 5 rem oves the w ater, and the lim e w ater tan k 6 rem oves the carbon dioxid, so the rem aining gas will consist of pure nitrogen, w hich passes from the tan k 6, through a pipe, 7, con tainin g regu latin g v alve 8.
16 represents an ordin ary lim estone furnace, w h ich m a y be heated b y burners 17 for form ing carbon dioxid, w hich w ill pass through a regu latin g v alve, 18, and thence b y pipe 10 to the furn ace 12. T h e calcium carbid is charged in to the furnace through a suitable chargin g door as 15, and the furnace is heated b y burners 13. A lso, a flu x of calcium fluorid or cryolite
or both is provided, and m eans for th orou ghly m ixin g the gases, w ith the m elted carbid and flux. T h e flu x does n ot react w ith the carbid, b u t has the fun ction of prom otin g and assistin g the reaction. W ith o u t the flu x the nitrogen com bines w ith the carbid, if a t all, on ly on the outside of the particles, leavin g the inside unchanged. T h e carbid is, so to say, indifferent to the com b ination w ith the nitrogen w ith o u t the flu x even though the tem perature be raised as high a s 1200-1500°.
T h e in ven tors are E in ar H onoratu s M eyer and Job M orten A u g u st Stillesen, of N iagara F alls Centre, O ntario,. Canada.
982,945. Process of M an ufacturin g Cem ent.
T h is in ven tion relates to the process of m an ufactu rin g cem ent from furnace slag in w hich the slag receives an adm ixtu re of lim e w hich is incorporated therew ith, the m ixtu re being subse
q u e n tly disin tegrated so as to form a h igh ly cem entitious gran u lated m aterial w hich can be used as cem ent when properly ground.
T h e accom p an yin g illustration show s ap p aratu s w hich m ay be used in carry in g o u t this process.
G round lim e is added to the liquid furnace slag in the proper qu an tities and thereafter the tw o m aterials are preferab ly in tim a te ly m ingled and k e p t a t a su itable tem perature to cause the thorough incorporation of the various ingredients. T his m a y be done in a su itable cham ber or ro ta ry kiln, the m aterial bein g m aintained in a fluid condition throughout the m ixin g process. T h e m ixed m aterial is then disin tegrated in a uni
form m anner so as to form gran ulated m aterial or cem ent clin k er h a v in g h ighly cem entitious properties.
In c arry in g o u t this process, a m ixin g furnace in the form of a horizon tal or slig h tly inclined ro ta tin g cylind er or drum , 1, m a y be used, p referab ly h a v in g a suitable lining, 2, of fire- resisting m aterial, and w:hich m a y be arranged to be heated b y
in tern al or extern al heatin g m eans. T h e m olten furnace slag is run into this m ixin g furnace, as b y the spout, 4, filling it up to the desired height, one-third of its heigh t for instance. The proper am ou n t of ground lime for form ing the cem ent is also
introduced in to the furnace b y a screw con veyer, 3, or other d istribu tin g means, the furnace being rotated, of course, in the usual w a y . In order to m aintain the proper tem perature of the m ixtu re during the rotation of the m ixin g furnace a supply of heated air from a burner or blast nozzle, as 5, m a y be provided w h 'cli m a y be either forced in to or conducted o ver the mixture in the furnace. In this w ay, an ed d yin g m otion m a y be set up in the m ixtu re w hich w ill secure its hom ogeneity and also assist in d esulfurizing it. Instead of air, o x y g e n or other gas or a m ixtu re of gases m a y of course be em ployed for this purpose.
T h e ingredients are th orou ghly incorporated and combined in this w a y and their hom ogeneous condition secured by the rotation of the furnace, since b y this m eans th e m aterial is carried up abou t h a lf w a y on the ascending side of the furnace and then is throw n or falls back again ; so th a t a fte r treating the m aterial in this w a y for the desired length of tim e during which it is k e p t in a m olten condition to secure the b etter union of the various ingredients, the hom ogeneous liquid m ixtu re m ay be discharged from the rev o lv in g furnace for fu rth er treatm ent.
F o r the purpose of disin tegratin g the m aterial a fte r having thus treated and m ade it hom ogeneous, the fluid m ass may eith er im m ed iately on leavin g the furnace or a t a n y subsequent period be gran ulated, as is w ell know n in this a r t and a steam in jecto r or other disin tegratin g m eans m ay be used for this purpose. A n arran gem en t adap ted to this end and form ing a con ven ien t supplem ent or a tta ch m e n t to the rest of the ap
paratu s m a y com prise a je t tu be or set of je t tubes, 6, ar
ranged a t the o u tle t chute 7, w hich join s the m ixin g furnace at the low er end and con veys the m ixtu re in fusion in to a rotating cylinder, 8, or the like, so as to enable one or a num ber of steam je ts to be sent in to the m ixtu re running o u t of the furnace, such je t o r je ts h avin g p ra ctica lly the sam e direction as the current of liqu id m ixtu re w hich b y such m eans w ill becom e uniformly disin tegrated or granulated. T h e g ran ulated m aterial thus ob tained is a cem ent clinker h a v in g h ig h ly cem entitious prop
erties and form ing cem ent when properly ground.
T h e in ven tor is C arl von Forell, of H am burg, G erm any.
983,199. C atalytic Synthesis of M ethane.
T h is in ven tion relates to a process for the c a ta ly tic synthesis of m ethane or a m ixtu re of m ethane w ith other gases.
T h e o b je c t of this invention is to provid e a process b y which the sulfur im purities m a y be effectu ally rem oved and a t the sam e tim e the cheap est of the com m ercial gases of the typ e of M ond gas and D uff gas and the like m a y be com m ercially treated for the production of m ethane, w ith o u t there being a n y need to m o d ify their process of m anufacture. In ca rry in g ou t this process the m ixtu re of gases (w hich should be first freed from carbon dioxid) is cooled to the degree necessary in order to get the su lfur im purities in to a solid form h a v in g little or no vapor tension the hydrogen passing off as a gas and being collected w hile the carbon m onoxid, nitrogen, and m ethane w ill be liquid or solid. On allow in g this la tte r m ixtu re to eva p o rate carbon m onoxid and nitrogen d istil off first and are effectu ally separated
E IG H T H I N T E R N A T I O N A L C O N G R E S S O F A P P L I E D C H E M I S T R Y . 203
from the sulfur im purities. A fter this distillation process a certain quan tity of the carbon m onoxid obtained is m ixed
with the hydrogen so th at the hyd rogen and carbon m onoxide are
in the required proportions. T h is m ixtu re is passed o ver nickel in the know n m anner. T here should a lw a y s be an e x cess of hydrogen o ver the th eoretical q u a n tity in order to pre
ven t local h eatin g of the m etal. T h e am ou n t of this excess depends on various circum stances, such as th e speed a t w hich the gaseous m ixtu re is passed over the m etal, and if nitrogen is present this a cts as a diluent and assists in p reven tin g local heating, and a sm aller excess of hyd rogen m a y be used than w ould otherw ise be necessary.
T h e accom p an yin g illustration show s a form of ap p aratu s for c arry in g o u t the process.
T h e in ven tors are F red B ed ford and C harles E . W illiams, of
Sleaford, En glan d. /