Progress in Chemical Equipment Accomplishments in Chemical Engineering Equipment since 1923. Reported through the Chemical Equipment Association by I t s Members
I
NUUSTHY’S advances selilon~occur with the siiilderiness of inspiration. ‘ t h y do not, like Minerva, “spring hill-armed from tlie brain of Jove.” Itat,lier they are tlic es of slow growth aiid pairifiil d e v e l o p inent of multitudes of inspirations. Friar I3iioon, pmderiiig centuries ago io a monastery iii rnedieval I~:urojx:, conri?ived of ships propelled without oars, arid of inadiines by which men iniglit Ay like birds. IIe might very well have given the world tlrese modern eonvenienccs. had lie only been provided with tlrr nreclranied LX~CBIIJto clothe liis iricas. Yet thme pl~ilo~o~iliic drearxis did not hecoine realitiw iriibil lhlton, 1)aokod 1iy the discoverirs and inspirations of ceni.uries of iiivest,igirt,ors, launche,l the Clertiioiit, rind t,lle Wrights, sitniliirly fortified by tire labors of eount,icss st,udeiits of mer:lranics, flew in their first havier-tlian-air flying machines. Advances of civilization depend upon accutnulated iahility for acri~mplislitnetitto iio less a degree than upon brilliant ilqiiration. Thus one tilay profitably liirrk upoil the inijir~ivcnieiits made in the tools of at1 industry as n more or less definite index of t,lie direction which its further progress may trike and of the extent to which it nay be reasonably expected to go forw,rd. We of tlie clieinioal industry, particularly, can survey with profit the actiritios of the ina,nufaeturersof the tools of our are cornplc4elg depmdent iipiin tlicin for 11 ee in putting our ideas t r j wiiik. We sliall find inuch thiat is entirely riew i n sorb it survey, ave IICPIIhr~itiglri.about more by thc improvement of t,lie inirrutiae of plant equipment than pping arid repliiremeiit of usrii,le ap tinctly iiew and better forms. It is true that liave had to he revised i:oinplctcly nnd new sccornmodate tire ttlberat,ims. kitit, this litis hem tlie cxr:eptiotr rather tlim the role iii t,lic industry. ‘e\ find cqiiipincnt manrrf:Lctwers hosying theinselves moat IwrRely with the prodiictiotl of more e6cicnt fittiiigs and npp:mtris ti, meet the needs of their clients in the face of highly crrinj,et,iti.i-enra.rkct,s for chemical products, arid in this a few new forms IMR beeri introilucrd. Tu general, t,oo, the prolkm of the erjriipinerit Inanufrxtnrer Tias heen imie of sopplying replacetrierits for worri-out a n d inc?ffirGnt parts rather than of R I)itilrling of nr’rv indust.rics. Front s u i h a point of view, the of tlie past two years or so sbow stetdy acix~or~~lialii~~cirts n d v a n w i n the industry, nod point the way to cootinucd progrrs~
Complex Stoneware lnafallafion for Hydrochlnric Acid Manufacture Built by the General Geramlcs Company
4
October, 1925
INDUSTRIAL A N D ENGINEERING CHEMISTRY Catalytic Gas Reactions
The rapid development abroad of catalytic gas reactions has been keenly felt in this country, notably in the synthesis of ammonia and of hydrocarbon compounds from water gas. Efforts to put these and similar reactions to work in this country are being made in many directions. Indeed, the synthesis of ammonia by the Haber and other processes has been in operation in this country for a number of years and the development of the Claude process here is expected soon to result in commercial production. Just what form the synthesis of methanol and related compounds from water gas will take is difficult to determine a t the present stage of things, but the methods used in ammonia synthesis will undoubtedly be modified to meet the conditions of these reactions. However, such processes, on account of the great expense of installations for handling gases a t high temperatures and pressures, cannot be of suficiently wide application, in the near future at least, to justify equipment manufacturers in standardizing the special apparatus required. Perhaps the next few years will lead to such developments, but they are still below the horizon. It is of particular interest to note in this connection that wood distillers have already been supplied with a new process which bids fair to compete with the synthetic processes that have been progressively invading their field. They have long been working under the handicap of being compelled to use wood in the form of logs rather than the miscellaneous wastes of lumbering. This has forced the industry to cpmPete to some extent with other users of timber for its raw material and, coupled with the fact that even this wood has had to be kept a number of years for seasoning, has been a great burden of expense to its operations. The difficulty in using waste wood has been largely one of retort capacity and heat transfer and has been overcome by the development of a continuous process which utilizes the heat given off by the exothermic reaction of carbonization. The success which this process has already met leads one to hope that by thus using an actual waste product of nuisance value the industry of wood distillation may be able to survive, in a modified form perhaps, the competition of the progressive development of synthetic processes. Acid Resistant Materials
The problem of corrosion resistance is met in every branch of the chemical industry and its solution is of first magnitude in the operation of chemical plants. Stoneware, glass, metals resistant to corrosion, and coatings of various kinds play important parts in every kind of chemical activity. I n each of these fields advances have been made during the period under consideration. Large Stoneware Tanks
Increasing use of stoneware has led to demands for larger and larger tanks until a point has been reached where it is no longer possible or economical to manufacture them in a single piece. Such one-piece vessels are available up to 4600 liters capacity (1200 gallons), but even these fail to meet the demands for larger sizes. To meet this situation, built-up tanks consisting of an outer retaining wall of reenforced concrete, common building brick, steel, lead, or other convenient material lined throughout with acid-proof brick laid in acidproof cement are being largely used. The service to be expected from these tanks depends primarily upon the properties of the brick lining and of the cement with which it is held together. Cements developed for use with acid-proof stoneware brick have shown remarkable resistance to the most corrosive solutions. A notable instance of the excellence of this construction is found in a pickling tank installed by
1003
Maurice A. Knight in the works of the International Nickel Company, at Huntington, W. Va. The pickle solution employed there for pickling monel metal, itself an acid resistant, consists of concentrated sulfuric acid, concentrated nitric acid, and a salt in combination a t or near the boiling point. Even under these most severe conditions after more than a year of service the acid-proof brick and cement tank has been completely satisfactory. Many other installations of a similar nature are equally efficient in service. Chemical stoneware laboratory sinks, drains, and vent lines are becoming increasingly popular. The one-piece sinks which may be fabricated of stoneware afford complete insurance against leakage and the permanence of stoneware drains and vent lines recommends their use. Lubricated Stoneware Valves
One of the constant worries of the plant operator has been the tendency of valves of all kinds to freeze tight in service so that ordinary efforts to free them with hammers and wrenches became dangerous. This has been particularly true of plug valves made of stoneware. The Knight-Merco lubricated plug valve, the principle of which has been used
Knight-Merco Lubricated Plug Cock
in valves of other materials but which is made in chemicaI stoneware by Maurice A. Knight, eliminates this danger. The underlying patented principle of this valve is the combination in an ordinary plug cock of lubricating ducts in the plug and a lubricant chamber at its base. The lubricating chamber and ducts are so located that when the lubricant control screw in the top of the plug is screwed down the plug is lifted from its seat in much the same manner as the plunger of a hydraulic press. At the same time that the plug is lifted, lubricant is forced through the ducts t o the valve’s seating surfaces to be distributed evenly when it is turned. S o matter how badly the plug may be frozen, this method will free it easily without danger of breakage. Porous Carboy Stoppers
The development of a porous stoneware stopper for carboys is an improvement to the credit of stoneware manufacturers. Carboys have ordinarily been closed by glazed, vitrified, or semivitrified earthenware or glass stoppers, impenetrable to gases or liquids. Frequent breakage in transit or in storage, resulting from the development of pressure within them for one reason or another, causes much needless damage and has now led t o the perfection of a porous stoneware stopper through which any generated pressure may vent itself without harm. The stoppers are tough, strong, and acid-proof, yet sufficiently porous to vent any gas that might be generated and at the same time prevent loss of liquid. Proper standards for these stoppers have been set by the Bureau of Explosives.
a004
I N D U S T R I A L A N D ENGINEERING CHEMISTRY Pressure Cast Stoneware
To meet the requirements of some users of stoneware, the General Ceramics Company, whose specialty has been rather the design and erection of plants than the manufacture of material on a quantity basis, has developed and is now using a new process for the manufacture of very close grained ware. This process consists of casting the suspension of clay in water-more of a suspension than a plastic mud-in molds under pressure. By this means it is possible to get a very close grained ware, free from air holes, and resembling porcelain in texture. The accuracy of dimension and shape of the finished piece is easily controlled in ware made by this process. After casting, the ware goes through the series of -aging, curing, drying, and burning operations as ordinarily practiced. Special clay bodies are used by this company for special purposes, permitting a wide variation in the properties of the ware and allowing emphasis to be placed upon any desired property, such as plasticity, tensile strength, elasticity, and so on. By so selecting clays it is possible to build tanks of capacities up to some 4500 liters (1200 gallons) capacity in a single piece, pipe joints as long as 4.27 meters (14 feet), and square tanks with a maximum dimension of 3.65 meters (12 feet). I n addition to the special pieces which this firm makes, a new acid-proof white glaze of its development has made possible the manufacture of satisfactory special pots for use by jewelers and others for the evaporation of very corrosive, and at the same time very valuable, solutions. The white glaze makes possible complete recovery of slight traces of solution or valuable sediment and the excellent heat-resistant properties of the ware largely prevent breakage in use. Furthermore, it adds to ease of complete cleaning where sanitation is important. White glaze, which has not before been practicable on chemical stoneware, can now be applied to it wherever desirable. Glass as a Plant Construction Material
Pyrex glass, developed originally by the Corning Glass Works to meet the need for better lenses in railroad signal systems and later widely used as a laboratory and household glassware, possesses many properties which recommend it as a material for plant construction. Following its early use in condenser tubes for Hart nitric acid equipment, it has been gradually working its way into all parts of plants. Pyrex evaporating dishes up to 61 cm. (24 inches) diameter, drying trays up to 30 cm. X 45 cm. (12 X 18 inches), retorts of 72 liters (19 gallons) capacity, and a wide variety of pots up to 45 liters (12 gallons) capacity are in everyday use in industry. Glass lends itself readily to tube fabrication by drawing for small sizes and by molding for the larger sizes generally classed as pipe. Pyrex tubes with socket ends find extensive application in acid-pumping lines, thousands of meters being in use in nitric and hydrochloric acid plants. Recently pulsometers (montejus) have been produced of it, thus making available complete pumping systems of this one material. I n the larger molded sizes Pyrex pipe is used for tower assemblies, still columns, gas mains, etc., the joints usually being made with a flexible cement resistant to the substances handled. Tubing in small sizes is used to a considerable extent in short lengths as a tower packing. Tubular evaporators and condensers have also been built with Pyrex as a tube material, and some interesting developments are foreshadowed in this particular field. It does not conduct heat so readily as the majority of metals, but the over-all heat transfer values are sufficiently high for com-
Vol. 17, No. 10
mercial work as the perfection of the glass surfaces and the retention of these under corrosive conditions tend to offset the lower conductivity value. The smooth, hard surface of the glass has led to its use in molded rollers used in artificial silk manufacture, textile dyeing machines, and various coating devices such as stamp gummers. Small one-piece bearings have given excellent service on experimental machines, and it is believed that further development of manufacturing processes will make it a valuable material for this purpose. Its transparency, coupled with its low thermal expansion, has led to wide use for sight glasses for evaporators, reaction kettles, columns, pipe lines, and oil refinery “look-boxes.” Its electrical insulating properties are opening up other new fields of use. Corrosion-Resistant Coatings
The idea of protecting a strong but easily corroded material by a less strong but more resistant one is not new, but its development continues to produce new and better forms of equipment to meet the diversified needs of a growing chemical industry. Glass and various related enamels have been applied to the protection of ferrous metal vessels of various kinds. Plating and more or less definite welding of resistant metals or other materials on others less so offer other types of corrosion-resistant ware. Each kind of ware has definite advantages of its own for particular purposes and all may be used in the same plant for different parts even of the same operation. In each progress has been made during the period under discussion. Glass-Enameled Ware
Improve men t s in enamel composition, in methods of fabricating shapes, in the design of furnaces, and in equipment for m e c h a n i c a l handling of ware i n p r o c e s s have made possible the production of enameled ware of increasingly better quality and a t much lower costs. The application to a steel base of a highly r e s i s t a n t enamel, which had formerly been applied only to cast iron, has made possible much greater flexibility of design and has e l i m i n a t e d to a g- r e a t extent the necessity Of Con- Cast Combination of Glass-Enameled Steel and Iron Standard Parte with Stoneware in forming to the Same Piece ard patterns. The welding torch makes feasible the manufacture of great varieties of shapes from steel, including complicated jacketed pieces, and combinations of cast iron and steel, coated with the same resistant enamel, make possible a range of design hitherto impracticable. The recognition of fusion welding as a proper
is equipped, as are the smalle ea, with a stufliiig-i,m guide bearing, which eliminates impeller whip and thus greatly increases the service of stuffing-box packing. An acid-proof ventilating fan for the delivery oi seve of air per minute agaiust a frictional or so of water has been added to the h r i r o n line. I t is part i d a r l y satisfactory for use i n i:ouncrtion with riit.ric acid recowry towers and sliows a distiriet saving compared with steam jets w l d i have liccri itscd Iicrctofore.
Acetylene Weldin)? of Cas? Iron Pot
Vesign of Apparatus
Tlie special conditions to be met in all kirids of chemical manufacturing operations have given this iridustry a greater variety of equipment made to fit into systems of the ut.most complexity and operated under more widely different circumstanees than any other. The necessity for meeting exactly the requirements of new processes has made oxyacetylene cutting and welding tools particularly valuable in this field. The acetylene torch is most useful for minor or major alterations or repairs of equipment already in plaee and for tlie iabrication of special forms 110thfor experimental and operatirig purposes. Careful arid continuous study of acetylene and the torches in which it is burned and of the problems presented in their use has resulted in the development of many new and useful forms of apparatus and methods of working. The ease with which leak-proof joints may he made, the readiness with which odd shapes and sizes may be built up, and the permanence of the finished job, except when atbacked by the cutting torch, arppe strongly in favor of the wider use of acetyleiie welding in chemical plants as a regular part of the maintenance department. Almost any metal may be worked into practically any form by the proper use of the acetylene torch. Cast and wrought iron, steel, aluminium, copper, brass, monel metal, nickel, and lead are readily handled by it. Pipe lines, jacketed or bare; intricate heating and cooling coils, jacketed or bare; kettles; stilk of every description; and, perhaps more important than all, the pilot plant apparatus for testing out processes on a semicommercial scale-usually drawn from the plant’s cast-offs and subject to frequent alterations to meet unexpected conditions--all of these are readily constructed by the acetylene welder to meet the most exacting engineering requirement.s. Sheet metal can be easily handled, but the possibilities which exist for the welder in an ample stock of various pipe sizes are almost limitless from a chemical plant point of view. No difficulty is offered in the coustruction of every conceivable pipe fitting from the pipe itself. Such things as T’s, Y’s, U’s, L’s, and manifolds, which may be quickly required, are child’s play for the good welder.
I’rc~greess in this fidd Ira.; Iar r iimii i n tlii: wider introAiotion of these tools iiito chei 1 plants as a result OS the rtssistariee rendered tlrrough tlie service crrgiueeriug st,affs of sucli firms as the Linde Air I’rodiiets Company, wha offer every assistanct: to the nelder in the solot.ion of knotty problems as they arise.
Special Electric Motor Designs blatiy of the uew developincuts in t,he fabricativti of cliemical equipment have been in the adaptation and iniprovnment of exisbiiig forms ratlirr than ill the introduction of entirely new formii. Soinc of the equipment of cherriical plant,^ is in the general industrid use, but Ircquently special adriptary to incet special coiitions of ttrc usual designs arc nee ditions. I’articitiilrly is this true powcr equipment. A s in o t l m industries, tlie iilca of individual motor drive arid e1ectrii:al power traiismission is gaining gmuiid in tlie ctiemir~nlh i d . In roost cases it is quite safe niid cc.oiiomii~al to use stnurlard motor eqiiipinent for iodivirhlal drives hut in others speai:il precautions are necessary to prevent 11 from cxplosi~eor corrosive dust or gases. In diist,y loentioiis tire difioult,y witli beariiigs is largely offset by sperial construction of t,tie liearing housings, and i n sonic of the more recent standard indueti~mmotors tlin coils are completely incased ill a baked-on insulation whicli gives a smooth, easily cleaned surface highly resistant to various corrosirc vaIwrs arid abrasive dusts. In especially corrosive atniospheres IL ricw type of coustruetion, developed by the General Electric Company, consisting of a eompletely inclosed, seli-ventilated iriductiori motor is valuable. Clean air for cooling is piped to the motor, drawn through it by its own fan action, and finally vented from the side without permitting the corrosive atmosphere to gain aecess to the motor parts. The whole arrangement is very effective in preventing troubles from fumes or vapors which might attack motor windings, slip rings, and so on. Often it is possible to use sucli a motor or even an ordinary squirrel cage induction motor in flammable atmospheres, but even t.hese types may he daugerous under extreme conditions. To provide the utmost safety in extremely flammable surroundings, t.his company has developed a nrotor so completely isolated in its case that it is irnpossihle for an explosiou originating within it to be transmitted to even the most
A B A -General Electric Specially Venfilnfrd Motor for lhrrostve
Afmosvherea. @-General EIecfrlc Nonventilatcd M ~ f mfor Flamnishle Afrnospheres
dangerous atmosphere. This motor is built in all the popular ratings for both a. e. and d. c. operation and is inclosed in a strong case with wide machine fitted joints. The design is sucli as to permit necessary cooling through the metal case without requiring ventilation. Severe and exhaustive tests have proved the safety of this construction. A new design of single-phase, variable-speed repulsion motor for direct connection to slow-speed exhaust fans has re-
Octobcr, l!WJ
l . V I ~ i . ~ ~ ~ Y I, T f'2N1) < l A E-VGI
tiic SLULIOS to secure t i w desircd iiimiess. The removal of cxtrcniely litre material from tlia miput of a mill by means omes uneconomical bcyoiid it c:ertain fineness md so it is often practice to use sttdi itii air separator to siipplemiiiit screens for tile removal of "floats." l n ordw bo iiicrease the capacity of its corrii:al niills and at the siiine time assure proper unifonnity of its product, the Hardingc Company tias developed two new rotary classifiors operating on the principle of rcvcrsed air currents atid spccifically f i r use with its invn mills. The rotary classifier is designed to give a pridnct from 98 per cent passing a 48 iucsii to 80 per i:cnt p iiig 200 inesh. Where greater fineness is required, the rotary aud stilierfine classifier is used. Tiio equipment is very simple, all auxiliary apparatus having le smne volnrrie of air is used throisgh, separat,ionboing effected by regulation of velocity in various parts of the classifier. The current first enters t,he inill, stirs tip the material, and hastens discharge of fines. As the material enters the classifier, the same current varrics the fines directly to the finishcd product bin, and, rcturning at a great.er velocity, blows the oversizes hack to the grinding zoiie, where the same operation begins over again. This prompt reinoval of fines greatly increases the capacity of the mill, and hence it9 efficiency, because its grinding action is not expended on material already of tlie required fineness. The air circulation is secured by a fan in the circuit.. These classifiers can be had in capacities ranging from 180kg. (400 pounds) to 43 metric tons (35 tons) per hour for the rodarv and from 135 ke. (300 nounds) to 25 metric tons (23 tons) per hour for thesupcr8ne rot.&. The differences i e h e e n the two types are only such as are made necessary by t,he difference in finenefis of output. They are finding exteiiaive use i i i connection with the Hardinge inill for grinding snd dassifying ceramic materials, limestone, shale, coal, and so on.
ti ni:tcliitie which will uperate niecilaoically 10 lo 2-1 liours per day withotit iinduc wear of the vibrating nrechaniam or of tlie ilc1ii:ate screen clothing, and which will at tlie same t,irnc proiliu:e large tonnages without blinding, i u frrr from siinple. The discard of iiicfiicient screens will sliow a hiindred Sailtires to one success. liowevcr, the successcs have dearly stiowii the principle to be practicable and so great nil advance ovcr former methods as t o assure pcrni:tircnt:y. The Sturtevant Mil1 Co~iipmyiias been a leadcr in this ilevclnpinent. ijf
'Typical lrlstnlIefio.l"l St"rle"a"l \it,ratin* screen
vibration is necessary whi(:li will keep (lie ma.tcrial active slid yetnot cause the l,artielcs to jomp toofar, *kipping over the screeti surface withoritproper oplJortunityto pass throug$ the meshes, and which at the same time is evenly distributed over the wire to prevent blinding and is destnictive neither to clothing nor meclianiain. Unit construction and accessildity, which allow quick repairs and the interchange of screen fr:itiit:s, with no parts too heavy and cumbersome to be Iiniidied easily, and a feeding device wliieh spreads the matei.ial evenly over the entire clothing, are noteworthy fcat,iirt:s of latest and most successful sercens. Spray Drying
I l a r d i n ~ cKofary Sepuracer 1nutallt.d with i l a r d i r i ~ cMill
Mechanical Separation I'ati,iit Olhce records sliow mi uriitsiml n u n i i m of inv(ntioiis
iiiiig devices since tlic first developiiioiit of tlie inc1iiir.d vilirating type, which has sliown sucli radical intpro\-amoiit ovcr the older rcvolviiig, huniping, and gravity ineclinliisins of a deearle ago. The superiority of the inclined vibrating type has led inany to devise iiiodifieations and i n provemenis, but few of these have ticen successful. Screening to the uninitiated seeins an easy proposition. lor by simply placing a screen at an angle of 45 degrees arid xhipping its surface wit.h a siiiall stick even the most difficult material may be made to pass through fine meshes. Thus far the problem and its solution are simple. But the design
Spray drying is becoming iiisrcasingly puptiliir for iiandlisig niiitwids OS a delict& iiature wliioli innst be complctely dried. The lirause disk spray process, controlled by the Cliemicai many advantages for this of a chamber in the middle revolved at verv hieh meeds ( X O O i.o 24,000 r. p. m.) on to which the solut.i& t.obe.dried is dropped from aliove. At the high speed of revolution of the disk, tlie Iiquid--which may or may not be put through a preliminary pa,rtial ovaporatioo-is tlirown violently in a \-cry fine spray into a stream of hot, air eiitcriiig from below. Tlic liquid is eompleiely evapornted, leaving the solid matter in a fine state of sishdivision to lie collected in a dust-collectstein. The advantage of t.liis process is in the fiiieness porsioti of the liquid being dricd and hence the rapidity ,ing and tlic short length of time that, tlie finished mais i n contact with tho hot air. The product of sisch an operation is uiichanged from the form in wliicii it existed in the solution except for the complete and almost instantaneous reinoval of the liquid phasc. Air Conditioning and Drying
The well-known principle of Carrier air-conditioning equipment has been recently applied to driers. This follows the
Octiiber, I!?Z
f2VI)C'~YTXIAI, AiVD ENGINEBRING CHEMlSTRY
1011
Wood Distillation sulS:ttc ai111 sudium carbonate monolydmto, ordinary ewpoIn tllc lield uf destrnctive distillat,ion a process and lleces- rators lose their efficiency on account of the building up of sitry eqitipniont Sor tho cconotni~~al retortilib. of finely divided ClYsttd layers on the heating surfaces, and thus tnatcrially wood, sawdust, chips, and other siniilar waste cellulose ma- reducing heat flow. To offset this difficulty, the Swenson terials has loiig been sought. wit11 lit,tIe su( until the work Company lias devised and pateiited an external circulating :~ndliquor supcrlteating system, which greatly increases the of 0. I?. Stafford, of tlrc Universit,jr of (I, developed cflicierrcy of its vertical tube, basket type evaporator and a process which lias rcceritly been put into operat,ion by E:. 13. Badger & Sons Company. The first comtiicrcial insta~]atiorl makes it satisfactory for this use. The system consists of of this process was made about two years ago and upon tile eontinoously withdrawing a sinall portion of the liquor froin pumping this through an external beater, atid success of this the Ford Motor Company decided ~ ~ a p the o evapomtor, ~ ~ plant using it for tlie recovery of by-products fronl its n;ist,c. retnrnitkg it again througli distributing nozzles located This large plant is now in operation at Iron &nutsill, >Iich. hmeath tho steam basket in the body of the cvapor:itor. The process inakes use of the heat liberated by the e x ( ~ t l , e ~ m iThis ~ iiqiior, whicii is at a much higlier terripcrat,ure tliati that decornpasition of cellulose at carbonizing temperatures and i n the evaporator, causes a violent flashing u p of steam lienee ohviates the difficulties of heat transfer from scmrces I his dclays saltiiig out on the heating surfaces su{fi(!iently outside tlie retort. By prodrying :md preiieating the finely to pc!nnit eoinmercially economical operation by increasiiig divided wood and by introducing it into tile ret,& >Tit11 nta- cir(~1lht~i with little power expcnditure, by distributing terial already undergoing carbonization, the heat generated Seed w. ils through the liquor-xvhich promotes crystal by the decomposition is sufficient to keep the ractiorl going fonllntiirit as opposed to salting out-and by the scouring continuously, It arjoids t.he necessity for complex agitat,ing aetiott of thcse growing crystals as they are violently driven devires to insure complete carbonization 2nd obviates the loss through tho tubes. The use of this system increases the of heat which is inherent in it,s introduction through so goo'] capacit,y of evaporators working on such solutions to about an insulator as wood chips. To rr,;tke the process silccessful 300 per miit of that attained without it, and it further permits driers the use of multiplc-effect irlsta.llations on t h e extrrincly on a large scale it has been necessary to develop for chips, special coolers for handling the finely divided char- troithlcsme salts. coal as produced, and special briqoetting inaclrines to make Continuous Cr:rystsllizer this into a commercial nroduct. MecBaiiicnI improvements liave greatly increased rhe eAiEvaporators ciency of the Sxvenson-Walker continuous crystallizer during Bmong tlie other developments of the Badger Company is tlie past two years. The crystallizer involves a series of a horizontal film evaporator which is particularly adapted jacketed troughs provided with agitators and arranged iit for handling comparatively small amounts of sensitive or cascade. The crystab and mother liquor orerRow from one corrosive materials. The apparatus is automatic and con- unit to the next and cooling water is rut1 throi~ghthe jackets tinuobs in operation and occupies small space. It is particularly successfulin replacing opeti pan evaporators handling such solutions as those of zinc chloride, sodium perchlorate, ammonium chloride, sodium acebate, sodium sulfate, and glue. Glass Evaporator Tubes In discussing the industrial uses of Pyrex glass, mention was made of an evaporator in whieh this glass is used as the tube material. The evaporator is of the Yaryan type built by the Swenson Evaporator Ctitnpany and is particularly adapted for use with very corrosive liquids, such as nitric acid, ferric chloride, or for very delicate solutions, such as fruit juices, which are injured by contact with metal duriitg evaporation. It operates on the film evaporation pririciple so that heating of the liquid is reduced to a minirnmn-mntact of the liquid with tlie heating surface is ordinarily less that) a minute. The vapor headers, vapor piping, cat& Swenson-Kipper Drier ShowinO COnStruffion ails, and thick liquor receivers are built of cliernical stonc\
