638
INDUSTRIAL -4ND EiYGILVEERING CHEMISTRY
precipitates. HoFever, for the purpose in hand the method was satisfactory. Discussion of Results
Tables I and I1 give some of the experimental data. In the first the nitric acid was kept a t room temperature and in the second a t approximately 40" C. A maximum conversion of approximately 5.5 per cent of the benzene taken was possible under different conditions, but the extent to which the benzene was attacked varied considerably. This was not determined in the first series, although it is evident that whenever a fair amount of phenol was produced oxidation went too far, judging from the dark color of the condensates and from the production of carbon dioxide and formaldehyde. This excessive oxidation was largely eliminated in the second series of experiments by running the gases more rapidly through the furnace, the time of heating being in the neighborhood of 0.2 to 0.5 second, whereas much higher values obtained in the experiments shown in Table I. (In calculating these time values it was assumed that the gases immediately reach the furnace temperature; obviously this is not the case so the calculated values are low.) Thus the best yield of phenol on the basis of the benzene attackedviz., 52.4 per cent-was obtained in Expt. 41, in which the yield calculated on the basis of the benzene taken was only 3.5 per cent. The extent of oxidation was closely related to the concentration of nitric acid in the vapor phase. When lower concentra-
T'ol. 21, s o . 7
tions were obtained through the use of diluted acids-viz., 50 and 60 per cent-the amount of phenol produced was only a trace (Expts. 50 and 51), and when higher concentrations were obtained by keeping the acid a t 60-62", 70-72 ", and 80-81 " C., instead of 40-42" C., the yields were 47, 48, and 30 per cent, respectively (Expts. 44, 45, 47), instead of 52 per cent (Expt. 41). In Expt. 41 the concentration of the nitric acid in the vapor phase a t 25" C., assuming the benzene t o be gaseous, was 0.0010 gram or 0.35 ml. per liter of mixed gas, and for each mol of acid vaporized 6 mols of phenol were produced. In Expt. 53, 9.7 mols were produced per mol of acid vaporized. The variable factors, rate of flow, ratio of air to benzene, temperature of furnace, and concentration of catalyst require proper adjustment for optimum conditions. Literature Cited in Part IT (1) Bibb, U . S. Patents 1,392,886 (1922); Reissue 15,789 (1924); 1,547,725 (1926). (2) Blair and Wheeler, J. SOC.Chem. I n d . , 41, 303T (1922); 42, 415T (1923). (3) Bone and Stockings, J . Chem. SOL.,86, 693 (1934). (4) Bone and Wheeler, I b i d . , 86, 1637 (1934). (5) Conover and Gibbs, J. I r a ENG.CHEM.,14, 120 (1922). (6) Downs, J . SOC.Chem. I n d . , 46, 188T (1926). (7) Fichter, Trans. Am. Elecivochem. SOL., 46 (preprint) (1924); J . chim. phys., 23, 481 (1926). (8) Fichter and Stocker, Ber., 47, 2003 (1914). (9) Gibbs, J. I s m ENG.CHEM., 11, 1031 (1919). (10) Stevens, J . A m . Chem. Soc., 48, 1824 (1926); SO, 2523 (1928). { I l ) Terry and Milas, I f i z d . , 48, 2647 (1926). (12) M'eiss and Downs, J. I N D . E s G . CHEM.,12, 228 (1920).
Machine-Blown Bottles at 300 Tons a Day' Everett P. Partridge 1440
EASTP A R K
PLACE, ANN ARBOR,MICH.
ROM the beginning of recorded history until the comparatively recent date of 1906, glass bottles, like other glassware, were blown only by hand. In 1906 the first successful vacuum-feed type of machine for the automatic blowing of bottles was developed. The perfection of this mechanical equipment was the first step in a remarkable revolution of the bottle industry in this country, a revolution which was greatly hastened by the heavy demands during the World War, and the accompanying shortage of sodium nitrate from Chile, spar from Greenland, and manganese dioxide from Russia. The Illinois Glass Company was one of the large concerns which early realized the significance of bottle blowing by machinery. This company had begun operation a t Alton, Ill., in 1873. In 1910, four years after the successful development of the vacuum-feed type machine, the introduction of automatic machinery was commenced a t the Alton plant. A gradual transition from complete hand operation to complete machine operation was made. This change not only involved the unavoidable troubles of replacing skilled labor by machinery, but it necessitated also the complete rebuilding of the furnaces and a radical change in plant routine. It was successfully accomplished, however, and in 1920 a second type of automatic bottle-blowing machine, known as the gob-feed type, was added to the equipment. At present the Alton plant of the Illinois Glass Company contains thirty machines of the two types, including a vacuum-feed machine which is the largest in the world. Bottles of all sizes and shapes are produced, over 3200 models being listed a t the present time, ranging in capacity from '/8 ounce t o 5 gallons. * Received March 11, 1029.
F
The Alton plant includes, in addition to the bottle-manufacturing plant proper, the wood-box and corrugated-fiber divisions of the Illinois Glass Company. The company also owns and operates bottle plants a t Gas City, Ind.; Chicago Heights, Ill.; and Bridgeton, N. J.; a chemical glassware plant a t Vineland, N. J.; and carton and label, cork, and bottling machinery plants a t Chicago. This article will be restricted, however, to a description of the bottle-manufacturing process alone, as worked out in the Alton plant. It begins with the handling of the raw materials in the batch plant, and continues with the passage of the mixed batch to the furnaces, the melting and refining of the batch, the blowing of the bottles, and their delivery through continuous annealing lehrs to the packing room. Some notes on the research program of the company and on the economic factors involved in bottle design and handling are included. The Batch Plant
The batch plant is separated somewhat from the main plant. Raw materials are delivered here by rail, are weighed and mixed in batches, and are delivered by cars on a doubletrack, narrow-gage elevated railroad to the furnace hoppers in the main plant. The unloading of raw materials a t the batch p'ant is accomplished by bucket elevators discharging to large storage bins, arranged in two rows of five bins each. Each row contains bins for the main constituents of glasssand, soda ash, lime, and cullet. Between the rows is located a small room from which are dispensed special materials used for different types of glass. Under each row of bins is a track on which runs an electrically operated batch-collecting and check-weighing car. Beneath the gate of each bin is
INDUSTRIAL A N D ENGINEERING CHEMIfiTRY
July, 1929
639
GLAh
A-Vaeuvm within blank mold cause9 B-Chill blow laims finish of bottle and sets C-After transfer to finishing mold, finish blow shapes bottle te contour of mold melted 6 1 ~ to s ~rise and fill mold enamel on outride surface of piass Figure S-Sfr~~ea in Boftle-BlovIn& Cycle of Vacuum-Feed Machlne
naces either mechanically or by hand. Other cars operating on the same elevated track supply the gas producers with coal. The fire-brick linings of the furnaces have a satisfactory operatiiig life of from 12 to 15 months of continuous service. If run much beyond this period. they produce poor glass with rraulting blisters and "stones" in the finished bottles. Before the furnace lining as a whole must he repaired, it is frequently necessary to repair the bridge wall. Erosion of the throat by the flow of melted @ass generally enlarges the opening until, after 8 or 10 months' operation, i t reaches tlie level of tho melted glass and no longer prevents the pa,ssage of slag into tlie refiner. When this occurs, it is now possible to reduce the heat on the fiirnace and reliuild the bridge wall, instead of taking the furnace out of service as was formerly neccssary. When complete relmilding of the furnace is necesThe Glass Furnaces sary, it takes from 21 to 23 days of gradual heating to bring The furnaces are of the customary Siemens regenerative the new fimiace up to the normal operating temperature oE type arid are coristruct,ed with a bridge wall separatiiig the 1370~-1480"C. (25fl0-2700" P.) in order to allow interns1 melting arid refining sections. A submerged throat through adjust,ment oE the expansion stresses. Recmse of the cost of this bridge wall allo\vs t.he passage of clean rnelted glass to rebuilding a furnace, economic considerations demand that the refiner from the melter, whilo preventirig the passage of the loss due to offware from a furnace nearing tho end of its floating impurities. The furnaces are fired with gas from useful life he balanced against the cost of relining and bringing C h a p m a n semi-autoback iiito operation. While producer gas is matic p r o d u c e r s loused for heating the cated below the furnace floor and in a line paralmelting tanks, the forelel to and in front of hearths, which supply the line of f u r n a c e s . the yoh-feed type maEach producer has an chines, and the revolvindividual average coning pots, which supply sumption of 19 tons of tlie vacuum-feed t,ype coal per day, with an machines, are licated avera.ge production of 2 with refiirery gas piped million cubic feet of gas in from three oil refinerper 24 hours. ies i n the ncarby town Thc m i x e d bat.ch of Wood River. This brought to t,lie furnaces gas is desulfurized after is droppcd f r o m t h e removal iron: the oil c a r s o n t h e elevated st,ills and before piping narrou.-gage track into to the g l a s s p l a n t . the feed hopper of tlie Forehcarths, furnaces, particular Surna.ce for and revolving pots are whicli it is int,ended. also equipped t o burn From the Iiopper it. is Sue1 oil as a standby in fed as necessary t.o the case of interrupt,ion of Figure 2-Typical Vacuum-Feed B o t t l e - B l o w i n g Machine " d o g - h o u s e " and is tiieir ~egularfuel supS o t e head r t right of picture with Gnirhing mold lowered to deliver bottles to chute p u s h e d into the furleadinz Lo cooveyoi. ply.
suspended a weighing hopper, into which the exact weight of the material desired is weighed before delivery to the batchcollecting ca.r. The operator of this car also receives special materials from the chemist of the batch plant, and then checkweighs the complete batch both by a scale on the car and by running the loaded car onto a track scale at the end of its run. The batch is then discharged to a rotary mixer. From the mixer it is again elevatcd by bucket elevators to a storage hopper, from which it is drawn int,o cars on tlie elevatcd narrow-gage track which convey it to the furnaces. Ratches of material for amber glass are handled on one side of the bstch plant, while batches for either clear Aint or green glass are handled in the other lint? of equipment. Approximately 125,000 tons of mnterinl are passed through the hatch plant in the course of a year.
640
IA'DUSTRIAL A N D ENGINEERING CHEXISTRY A u t o m a t i c Bottle-Blowing Processes
The batch of mixed raw material pushed into the furnace melts, passes into the refiner, and then flows through troughs to the feed mechanisms of the bottle-blowing machines. In the case of the vacuum-feed type of equipment the machine itself picks up melted glass from a wide, shallow, revolving pot, while in the case of the gob-feed type of equipment the melted glass flows through a measuring orifice which automatically passes a slug of definite size through a chute to the mold of the machine. In many respects the two types of machines operate similarly once they have received their charge of melted glass. VACUUM-FEED Tym-This type of machine is built with ten mold-carrying heads. The machine rotates continuously a t a rate determined chiefly by the characteristics of the ware being made upon it. Practically all of the mechanism is actuated by cams which are adjustable to give the requisite movements of the molds for different types of ware, several thousand cam combinations being possible. The main drive of the machine is from an electric motor, and the blowing of the glass is performed by compressed air a t a gage pressure of 26 pounds per square inch. Air is also blown on the molds during each cycle t o prevent overheating of the metal. Each head of the vacuum-feed type of machine carries a blank mold, which measures the amount of glass required for a bottle and chills its external surface slightly while giving it its initial shape, and a finishing mold in which the glass is blown to its final shape. The movements are as follows: (1) The blank mold closes into position around the neck ring, the plunger is lowered into position within the neck ring, and then lowers to dip the nose of the blank mold into the melted glass in the revolving pot. The vacuum valve opens to the interior of the mold, and atmospheric pressure forces melted glass up into the mold, completely filling it. This process is shown diagrammatically in A of Figure 1.
Vol. 21,
9 0 .7
comes into position around the glass slug, called the parison, and the finish blow shapes the parison to the contour of the mold and chills the glass sufficiently for delivery without danger of collapse. In C of Figure 1 the finish blow is shown nearing completion. (4) The neck mold opens, releasing the finish of the bottle, and the whole finishing mold, carrying the bottle, drops to clear the revolving pot which it is approaching as it reaches the end of the cycle. The blank mold on the same head is now starting the series of movements described under (l), while the finishing mold is releasing the completed bottle, which is removed either manually or automatically to a conveyor leading to the annealing lehrs.
A photograph of a typical vacuum-feed bottle-blowing machine in the Alton plant is shown in Figure 2, which gives a good idea of the complexity of the mechanism. GOB-FEEDTYPE-This type of machine is built with six heads, each carrying a blank mold and a finishing mold, as in the vacuum-type machine. The two molds on each head of the gob-feed machine are set, however, so that they successively swing into position by inversion of the whole head, and the machine does not rotate continuously as does the vacuum-type machine, but instead moves in jumps of 60 degrees each. This motion is necessitated by the manner of feed, since the mold must be stationary while the slug of melted glass is dropped into it from the feeder. This feeder, located a t the end of a forehearth, through which glass flows to it from the furnace, is a bowl with a round opening in the bottom, through which a needle pushes a slug of glass a t every jump of the machine. This slug is cut off by a pair of thin-blade shears closing across the opening, and falls through a system of inclined troughs into a blank mold of the gobfeed machine. The whole machine is motor-driven and camoperated similarly t o the vacuum-type machine, but takes blowing air a t 45 pounds per square inch pressure. A typical cycle is as follows:
N
A-Feeder delivers slug of melted glass t o inverted blank mold
B-After head inverts, glass is shaped to blank mold and chilled slightly by preliminary blow
Figure 3-Stages
C-After transfer to finishing mold, finish blow shapes bottle to contour of mold
i n Bottle-Blowing Cycle of Gob-Feed Machine
(2) y t h the machine continuously rotating, the head lifts out of dip, and a knife cuts off the melted glass hanging from the nose of the blank mold. The plunger is withdrawn, and the blowslide comes into place above the neck ring for the subsequent blowing operations. The first blow, called the chill, shapes the glass to the blank mold and sets the enamel on the outer surface of the glass to produce uniform distribution during the rest of the blowing. This stage is shown in B of Figure 1. (3) The knife drops and swings out from beneath the blank mold, the mold opens, and the blow is started by a puff which forms the neck and shoulder of the bottle. The finishing mold
(1) A gob of glass is delivered by the feeder to a blank mold, which a t this point is in a n inverted position. A plunger rises into the neck ring, as in A of Figure 3, and a shutter slides over the opening of the mold through which the slug of glass entered. A slight blow forms the finish, or top, of the bottle, the plunger is withdrawn, and the machine moves forward 60 degrees while the head inverts. A second blow shapes the slug to the walls of the blank mold, as in B of Figure 3, and forms the enamel on the outer surface of the glass. (2) The bottom shutter is removed, the neck ring opens, and the transfer tongs close around the finish of the bottle.
July, 1929
INDUSTRIAL AND ENGINEERING CUEMISTRY
641
moving a completed bottle from a mold, is built with six arms and rotates at a rate of one revolution per minute. The rotating mechanism is electrically driven, while the mechanisms for the movements of the blowing cycle are operated by compressed air at 80 pounds per square inch pressure. The pressure of the air used in the actual blowing is, however, 26 pounds, as in other vacuum-feed machines, and the blowing cycle is typical of this class. The machine stands 20 feet high and weighs somewhat over 120 tons. When blowing 5-gallon carboys it handles more than 55 tons of glass, and produces an average of 8500 completed bottles per 24 hours. Annealing S y s t e m s
Figure 4-Typical Gob-Feed Bottle-Biowlnp Machine der rt top center of pictwe drops gliss ~lirgsthrough chutes, i o blank molds of hottle-hiowing michme. Note soda bottler lehaing machine on conveyor at right, and "fiie pdirhing" rack Suning t h e finish of the boifles io m a k e them perf~ctlysmooth.
The blank mold opens, leaving the parison suspended by the transfer tongs, and the head inverts again and brings the finishing mold into position around the parison. As the finishing mold doses the transfer tongs release. (3) The blow bell is brought into position, and the final blow shapes the bottle to the finishing mold and chills it sufficiently far delivery. The completion of the blow is shown in C of Figure 3. During the blow the head advances two moic positions in the cycle. At the fifth jump the air is mt off,and the bottie remains in the mold through the sixth and seventh jumps. The glass has now traveled 420 degrees, and a fresh slug i s starting the cydc in the blank mold on the same head. At the seventh jump (the first jump for the new slog) the head inverts, bringing the completed bottle in the finishing mold upside down. (4) At the eighth jump the tongs of th? take-out mechanism close around the neck of the bottle, the finishing mold opens, and the t a k e o u t arm swings in a vertical arc of 180 degrees, setting the bottle down, right side up, on a conveyor leading to the annealing lehrs.
Up until 1927 oil-fired lehrs were used exclusively lor anneding the ware removed from the hottlr-hlowing machines. At present., however, the vacuum-feed machines deliver to electrically heated lehrs, while the output of t.he gohfeed machines is handled in highly efficient gas-fired unit lehrs. The electric lehrs already inst,allcd have demonstrated their superiority very decidedly. One electric lehr replaces t,wo of t,he more bulky oil-fired type, alloming valuable economy in floor space. Control is automatic and constsnt within close limits, the maximum variation in any zone being 5" C. (9. F.). Furthermore, the annealing t&nperature'- curve may be varied with extreme ea,se to handle types of ware requiring different trcatments. Recause of t.he close control it has been fomrd possihle t,o reduce the time of annealing required inti1 electric lehrs t,o one-half of that formerly re!quired wit,h the oil-fired type. In general, the savings in heat reniiirements and floor snace and the increase in efficiency h,ave m;ch more t.han offset't,lie increased initial cost of the equipment and the increased cost of electricity over oil per
h typical gob-feed machine making soda-water bottles a t tho Alton plant is shown in Figure 4. The bottles ma,y he seen leaving on a conveyor a t the right of the picture. This conveyor carries them below small flame jets, which fuse the finish on each hottle t.o give a perfectly sinootli surfaee for the benefit of t,hose who drink thcir "pop" from the original container. The ducts for supplying cooling air, which is blown on the molds to prevent overheating, also appear prominently in Figure 4. lloth tho gob-feed and vacuumfeed machines are air-cooled in this manner. Sulfur is also swahhed on the inside of each mold at intervals to prevent, heating, and graphite is similarly applied to prevent sticking of the glass t.o the mold. Largest Bottle-Blowing M a c h i n e in t h e World
In the Alton plant is the largest bottle-blowing machine in the world, one of the vacuum-feed type, which may be fitted with molds for blowing either 4- or 5-gallon bottles. This machine, which is shown in Figure 5 witti a laborer just re-
FiBure S-Largesf
Bottle-Illowine Machine in the World
A %head vacuum~ieedmnehine standing 20 fcut hixh and weighing over 120 tons. Note j ~ g a l i o ncarboy just token froin finishing mold 1'7 attendant. who is about to place it 00 a cooveyor leading t o the annealing lehr. Revolving pot of melted girss appeirs iurt io left of attendant, w i t h one head oi machine jiirt about to lower blank mold into dip.
642
IKDUSTRIAL A X D ENGINEERING CHEMISTRY
unit of heat value. Figure 6 shows the general appearance of one of the electrically h e a t d lehrs viewed from the feed end. Electrically heated lehrs prove economical for extremely small sizes of ware in spite of the relatively large amount of
Figure 6-Feed End of Elecfrieally Heated Annealins Lehr Bottiee fium blowins machine entering iehi heated by Ctobar units. This lebr requires onlY half the Boor space 01 old-style oil-tired lehrs, and accurate temper*tiire control riIows the annealing period Lo b e cut apixoximatdy half that pre~musly required with the older
Vol. 21, No. 7
trol and research on the manufacture of glass. Although a part of the work of this laboratory is the routine necessary t o plant operat,ion, the major portion has been fundamental esperiniental work. I n the research laboratory there is a collection of instrunients not frequently found in an industrial laboratory. Among them is a specially constructed precision iiiterferometer which is used in detecting siibmicroscopic cracks in glass. An AbM-Fizeau interferometer, rehwlarly applied to the determination of the coefficient of expansion of glass, has been Bpecially modified to adapt i t to the determination of tlie softening point and heat conductivity of glass in addition to its regular function. The study of the structure of complex silicates is aided by ineaiis of an x-ray reflection apparatus, with which important work is k i n g done a t the present time. A precision Ruprecht balance with a capacity of 1 kg. and sensitive to 0.01 mg. is used to determine slight losses in weight due to the solubility of glass, whole bottles being used in the experiments. Of the current developments of the research laboratory, trvo stand out as psrticularly important. One is a fundamental high-temperature, high-pressurc research on complex silicate systems, while the other is the establishment of a compl&e experimental glass furnace and bottle-blowing unit. This unit, with a capacity of 15 to 20 tons of glass per day, will be used exclusively for experimental purposes in the development of optimum conditions for plant production of various types of ware.
equipmeat.
heat required as compared with that necessary for the annealing of larger sizes. T i e amount of heat which must be supplied to the lehrs is an inverse function of the weight of glass passing through the lehr per unit of time, since the bottles themselves, which enter the lehr a t approximately 590' C . (lloOo F.), carry sensible heat proportional to their weight, and the heat losses from the lehr are independent of the siae of ware being annealed. Theamount of heat required for annealing 5-gallon carboys is very small, while the heat requirements increase as the bott.le size decreases. The electric lchrs are heated by Globar units, and teinperatures in tlie various zones are indicated on pyrometers. An additional periodic check on the annealing curve is obtained by means of a Leeds a.nd Nortiirup temperature recorder, the thermo-element of which is coniiected by long leads arid is attached t o a bottle entering the lehr. As it passes through the lehr i t gives a continuous record of the temperatures encountered. Figure 7 shows a typical annealing curve obtained in this way.
Economic Considerations in Automatic Bottle Manufacture
Modern advertising, with its unceasing search for novel and eye-catching designs, frequently conflicts with the properties of simplicity aiid strength desired in bottles from the cost and utilization viewpoints. Certain features in bottlessuch as "finish" or top of neck t.oo light or too heavy, neck too long, too short or too small, short radius curves, Hat shoulders, sharp corners, extremc tapers, deep panels, wide flat sides, and
Testing of Annealed Ware
The arinealing lehrs deliver ware to the storage and packing rooms a t slightly above room temperabure. Here, at regular intervals during escli shift, samples are taken and subjected to a polariscope test to determine whether all internal striains have been removed during the antiealiag. This test is so delicate tlmt the strailis set. u p by holding it lighted mntcli under a bottle for a few sficonds are r e d l y disecriiihle. Sample bottles are IikeTvise test,ed by temuerature shock and by impact shock. Research Facilities and Projects
In addition to a mccliariieal research depmtment, which has done much valuable work along the lines of burner desigii, tho development of macliines for handling, piliiig, arid testing bottles, and iurnaoe feeding devices, tliere is a large and extremely well equipped chemical aiid physical laboratory under the direction oi A. I,. Duvd d'Adrian, engaged in coli-
I
M
Fieure 7-TypLcal
D
I
10
I
30'
TlnE IN LFHR-W.
I
M
I
m
I
I
ao
XI
Time-Temperature Curve for Electric Lehr
Curve plotted from actual data of curve-drawing py:omctei temperature distribution in iehr.
used
t~
check
depressed designs or lettering-are especially objectionable, either because tfrcy render the maiiuiacture of bottles by sutomatic machinery unsatisfactory or because they introduce the element of increased cost in mold making. The making of molds for all exoept the siinplest shapes must necessarily remain a process dependent to a lrirgo degree on skilled hand labor. When it is realized that t o produce an order oi bot,tles on a 10-arm vacuum-type mrichino twentytwo blank molds and thirteen blow molds, together with plungers, neck molds, and bott,om plates, must be made in the shop, the great capacity and uniformity of operation of aut,omatic blowing machines is seen t,o he partially offset by
July, 1929
TSDCSTRIAL A S D ESGI-VEEHSG CHEMISTRY
the very complexity of the mechanism. Gobfeed machines with six heads require nine separate pieces of mold equipment for each head and additional parts for replacement of those worn in service. Just as many mold parts must be made for a n ounce bottle as for a 5-gallon carboy, and the design of the small bottle may require more labor in mold manufacture than that of an extremely large one. The trend of commercial packaging is, however, distinctly toward smaller containers. One feature of this trend is the demand for small bottles for jams, preserves, perfumes, and toilet articles dispensed in stores of the 5-10-25-cent claks. From a broad economic standpoint the trend ton-ard smaller packages costs the coiisumer more, since he must pay a higher per cent of his purchase money for the container when it is small and fancy than when it is large and plain. This trend, coupled with the desire for diversified styles of bottles, also helps to stock the mold storage rooms of the bottle manufacturer with tons of equipment used perhaps for only one run, the cost of which must ultimately be passed on t o the consumer, ~1.110buys his tomato catsup or his laxative pills in a newer and more striking container than he used to. While automatic equipment has revolutionized the bottle industry, and has carried that industry far on the road toivard completely mechanical operation, there is still a balance between hand labor and machinery in mold manufacture and
643
in two operations in the plant. The first of these operations is the removal of finished bottles from the blowing machines t o the conveyors leading to the annealing lehrs, and the second is the removal of the annealed bottles from the cool ends of the lehrs in the storage and packing rooms. I n the first case, only bottles that are standard and are manufactured almost continuously are transferred from the finishing mold to the conveyor by means of take-out tongs; some sturdy shapes of small bottles are allowed t o fall from the mold onto the conveyor; and the remaining bottles, comprising special shapes and large sizes, are removed manually, because the operation can be carried out more cheaply in this way than by providing the multiplicity of transfer equipment which would be necessary to handle all ware mechanically. I n the second case, in the storage and packing room another factor enters into consideration, that of the visual inspection of the ware which is possible with hand packing. Until photoelectric devices become human enough to inspect bottles, the packing of bottles from the cool ends of the annealing lehrs will probably continue t o be done by hand. Acknowledgment
The writer is indebted to the officials of the Illinois Glass Company, and particularly to C. 11. Marsh, vice president, and t o J. W.Romig, plant engineer, for information and assistance in the preparation of this article.
Some Aspects of Cracking' A. E. Dunstan and R. Pitkethly ANGLO-PERSIAN OIL COMPANY, L O S n O N ,
I
K THE short span of tiventy years gasoline has become
a world-wide necessity. Many mho are still actively engaged in the petroleum industry can remember when the disposal of this fraction was a problem. Most of it was burned under steam boilers or stills, but today such a waste of valuable materi,d is unthinkable. Not only has the supply of gasoline obtainable directly from crude been completely absorbed, but the demand for motor fuel much in excess of that quantity has resulted in a n enormous production of synthetic and natural gasoline. The latter has been obtained from natural gas by absorption or compression methods, but the former, by far the largest contribution towards requirements, has bflen produced by cracking. Modern Cracking Processes and Their Limitations Liquid-phase or pressure distillation processes, employing comparatively moderate pressures, have been responsible for the eiiormous production of cracked gasoline in recent years and their development has given rise to the modern cracking plant. It is remarkable that the few processes which have becomc commercially successful haye all developed on similar lines-namely, the provision of a tubular heating section and a large vessel wherein the reaction is completed and coke deposited. All rely on heat treatment alone for the decomposition of the larger oil molecules. The modern cracking processes can process almost any crude or residual oil for the production of motor spirit. It would appear, therefore, that motor fuel requirements can be satisfied for a n indefinite time simply by increasing cracking equipment. But there are limitations, as the requirements of lubricating Presented at a meeting of the Philadelphia Section of the American Chemical Society, Kovember 15, 1928
ENGLAND
oils, wax, pitch, kerosene, and heavy distillates must be provided. IYotwithstaiiding the success of modern liquid-phase processes, the ideal cracking process has not yet been invented. By heat treatment alone hydrocarbons of high molecular weight are decompoPed into compounds of lower molecular n-eight and lower boiling range, but it is practically and theoretically impossible t o do this without also producing coke or compounds of high carbon and low hydrogen content. All commercially successful processes are hindered in their application more or less by this effect. Patents innumerable have been filed which claim to eliminate carbon formation, but to date none of them have developed into profit-earning propositions. By combining hydrogen with the oil while under cracking conditions the deficiency in this element may be made up, but commercially satisfactory means for achieving this combination have yet to be invented. Bergius and the I. G. have attempted to satisfy the conditions, but after many years' work the world's markets are unperturbed and no flood of synthetic gasoline has been produced t o compete with the natural material. The amount of coke produced in liquid-phase cracking may be only a small percentage of the raw oil processed, but last year over a million tons of this material mere produced in the United States alone. Besides actual coke a large quantity of fuel residue is also produced, but the loss in oil represented by the coke alone can be calculated in millions of dollars annually. KO doubt the cracking process of today has been of immense economic value. It has assisted in the rapid development of motor transport and has been the most effective step taken towards the conservation of
