Carbon and Graphite Company. Inc., Clevdrtnrl. Ohio
T
HE most, draiiiaLic aiid
\\ iticlg pub1icizt.d applii~i I iliii ( i i manufactured graphite was announced in .\ugust 1945 wit11 release of the Smyth report (98) revealing the use of graphite as the moderator in the plutonium piles a t the University of Chicago and Hanford, Wash. This epoch-marking developiiit~nt was, hoviever, only one of the many significant industrial uses f o i . carbon and graphite achieved under the p r e s j u i ~of wartime (k,mands. Although carbon and graphite have been rniployid a i materials of construction in the chemical proce.s industries f o l ' many years, the serious and diverse corrosion problems created ti? tlie arniament program gave greatly accelrrated imp broader application of these niat'erialr. The impervious fornir IJf carhoii and graphite, marketed as Karbate hare lirerally "gron 11 up" since 1940. A rnmplete published description of the miiriufact uriiig 1 ) i w tbsses, physical and chemical propertips, and industrial applicutions of carbon and graphite is offerd by hlantell ( q j . Ollinpvr (I/?),iu R much more condensed form, discusm r w ~ i clevt~lopi~ inentp in carbon and graphite chemical equipment. One receiii paper (16) dealing specifically with carbon and graphite as UJYrosion-resistant materials of construction considers industrial HI)plications under the three following basic classificatioris, (a)t t w i ~ g u l n or r permeable forms, ( b j the highly porous and highly i)(trrniy~hlrforms, and (c) the impervious forms. This division swiii4 t n lend clarity t,o the discussion and nil1 be folloncd in this revirw.
REGULAR FORMS
Ikraa1-Jeof their permeabilitv, the regular f u r ~ i i *UI ( M ti011 i ~ i i i l graphite are usually employed under coiidit ion, n liere permc-
ability is not a consideration or where slight seepage is not significant. They are also used in combination with impervious memtranes or backing materials. As a structural material they may range in size from tiny rods to large 1)locks n-cighing mnrh as 7000 pounds. Expanded refinery proresses, especially thr production of aviation alkylate (HFj and the scrubbing of hydrocarbons w i t h a l k l i n e solu1 ions, intensified interest in carbon kaschig rings for tower packing. A typical application is described by C h e n i c e k a n d coirorkers (10) for the countercurrrnt scrubbing of isobutane Rith dilute caustic. '1'11e conrcntration and recovery of sulturic acid from nitrat ion processes miployed in the manufacture of high exploaive.; and propellant 5
wquirtd t l ~ use r of electrostatic precipitators, and the applicatioii of cartwn to their construction as described by Vosburgh (32)was increased many fold. Berger and Gloster ( 6 ) ,in their discussion of ;irecipitat'or corrosion, point out that wartime experience revealed iittlt. corrosion of parts other than exposed lead work in carbontube precipitators. Burke and Mantius (8) report the use of cartion liriirigs in Mantius concentrators handling impure acids which cause spalling and disintegration of the regular grades of acid brick. They also discuss the advantages of carbon linings for pipe, steam injectors, and barometric condensers used as auxiliary equipment \\.ith sulfuric acid concentrators for high acid concentrations. Incwased product,ion of st,ainless steels continued to show cart i u n brick as the only suitable lining for nitric-hydrofluoric acid pickling tanks. Tucker and Wprking (50) have reviewed the -teps leading t o the demand for carbon brick linings for digesters in sulfate paper mills. Typical of flue and stack construction of (wlmii is the repoitcd ( 5 ) use of carbon exhaust flues to prc.v,.ni Lwrrosive action by laboratory gases containing hydrogen flufxide, hydrogen chloride, nitric and sulfuric acids, chlorine, and ammonia. Vosburgh iszj describes the use of carbon hold-dov-n rolls in continuous alternating current pickling machines, and as clrohri and corrosion resistant baffles in fly ash removal equiprucnt . Of possiblr w o n d a r y interest t o tlie chemical industry, but too >ignificant not t,o mention in this review, is t,he acceptance by the stwl industry of carbon linings inr blast furnace crucibles. Although its use has been corninon practice in Europe for many !.ears, the first carbon lining in the United States was not installed until 1945. Nolaii ( 2 5 ) report,s that, as of February 1947, over IO?; of all United St 5 blast, furnaces either have installed cartion crucible linings or have thcm on order. Typical of large graphite block construction are the phospliorus burner t'owern developed b y the Tennessee Valley Auilinrit?- ( 2 6 ) . Gas coo1~1.~ for the resulting PlOs are graphite slat) construction and have horizontal graphite cooling tubes niounted iri graphite tube sheets. These burners and coolers employed with rarbon hydrator towers and precipitator6 permit the prod u c t i o n of h i g h p u r i t y acid. T h c phosphoric acid industry is watching t h e i r pcrforinance with much interest, and several papers are expected on the subject soon. The interest in the cathodicprotectionof metallic structures against electrolytic corrosioIi h a s been very noticeable in th(c
October 1947
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
1203
iJsidat,ion to H2SOaby aerat,ion with porous carbon diffusers in the presence of a catalyst. In the production of certain chlorinated hydrocarbons in n-hich the chlorine is difficult t o react, porous carhijn diffuwrs have been employed t(1 advantage. Ronilla ( 7 ) comments on the availability of porous carbon and graphite tubes for use in prensure filters. Various fornts of vacuum-operated leaf-type filters are also in service. The use of porous graphite tubes for the filtration of molten - a h solved a particularly vexatious wartime problem and has led to further studies on the filtration of the lighter metals. The filtration of ~(4urouscaustic solutions without the objectiouahlr contamination of silicious materials from tilter aids and metallic impurities from screens tins been a decided contribution of porous carbon. Hatfield (18) offers information of academic iiiterest on the corrr'lation of fluid flow through porous carbon by means of the Reynolds' criterion :ind the torresponding friction factors. Electrodes of porous carbon and porous graphitr open up new fields in electrolytic oxidation and rtduction procrkws. Systems described by Heise (ZO), Janes (21),andfinslow (34)permit increased viirrent effic+ncirs and lower overvoltages. ~~
Porous (hrhoii DiBuser Elements
IMPERVIOUS FORMS
p)stwar period, atid ,dgtiificaiir i I i i i , ~ ~ , \ - t ~ l i i~l l~ ~t hI ti st ~appliratioti principles of carbon and graphite giound anode9 have been mad('. Dorcas (12) comments on installation methods, and discu. relative rates of consumption and economics of carbon anodes with respect to other materials. Suitable back-fill materials h a i i been developed which are expected to decrease materially the already low rate of elccttolytic decomposition of carbon and graphit(. anodes. Tn the mo6t recent reports on carboil resistor furnaces, (;artIuiid ( 1 7 ) describes the details of construction of a practical, electrically heated carbon tube furnace. Kroll, Schlechten, and Yerkes (28)discuss the operation of a furnace employing a slotted graphite tube as the resistor element. Poland ( 2 7 ) reports the use of T-shaped graphite rc'sistor hyating element. in a high temperature furnace for distilling and refining metals. The furnace hearth, side wall, and roof are of carbon block construction. POROUS CARBO3
The inherent porosir#yof carbon and graphite is ubed to good advantage in the manufacture (2.4) of Carbocell porous carbon and Graphicell porous graphit e, controlled permeability materials having a porosit,y about twice that, of the regular forms of carbon and graphite. These materials find extensive application in the dispersion of gases in licluids and in filtration. Aeration equipment for aerobic fermentations was of special interest during the war. Porous carbon diffuser elements were employed in the production of penicillin, alcohol from wood sugars, etc. D e Becze and Liebmann (11) discuss the performante of aerating systems used in a n attempt to obtain optimum >-eastcell yields with reduced amounts of air. Stark, Kolachov, and Wilkie ( B ) ,reporting on factors affecting yeast propagation, demonstrate the importance of using the finer grades of porous carbori :ind the significance of the depth of submergence on aeration efficiency. Unger and co-workers (31) discuss the performance of porous carbon diffusers in an aeration process for the continuous production of distiller's yeast, and recommend aeration rates and general diffuser arrangement for indu,strial plants. Walthall, Miller, and Striplin (33),in their paper on the development of a sulfuric acid process for the production of alumina, present data o n the absorption of 80, in n-cak suIfiiri(, acid and the subsequent,
kaf,tJateiriiperviciuo carbori and graphite are the regular form+ )1' carboil and graphite made nonpermeable t o fluids under pressure by impregnation with thermal setting, synthetic resins. Hatfield and Ford (19) review ttir improvemmts made in the: properties of thrse materials and the advancemcnts in equipment design from 1939 t o 1946. Experience gained from wartime servivr has permitted standardization in the design of Iiartmtch vquipnirnt, such a$ hcat ilxc:h:ingrw, pipe and fittings, va,lvw. pumps, and t o w m . Two recent articles ( I . $ , 1,5) preseiit a ten-year engineering rcv i m of inipervious graphite's record as a material for the coilstruction of heat exchangers, and oger the general principles of design n i t h rspecific examples of performance. Another publication (1 ) describes the use of iniperrious graphite shell and tube reboilers and condensers in the distillation of 14% hydrochloric acid. and provides operating data on shrll and tube elect,rolyte heaters. In a discusion of evaporator dwigii, Badger (6) states that, in tlir field of special materials, the most important innovatmion has beeti the use of Iiarbate tubes for the handling of acid liquors. Burke, and Mantius ( 8 ) recommended the use of Karbate, tubes in vertical heating elements for weak acid concentrators, and stress t h r nrgligible corrosion, low fouling factor, and consequent good, coilsistent rates of heat transfer. I n the postwar period particular interest has been shown in the noncontaminating propert,ies of Karbate heat transfer and conveying equipment for the handling of acid and alkaline plating solutions, rayon processing solutiorin. Food products, pigments, etc. The demand for large quantities of hydrogen chloride, in s u t ~ ,stantially pure form, for the production of plastics, alkyl chlorides. synthetic rubber, etc., has been one of the more important stimuli to the developnient of Karbate equipment. Absorption ail(I stripping units, heat interchangers, and conveying equipment I , ( impervious graphite construction probably produced more hydrochloric acid and hydrogen chloride during the war years than ariy other single material of construc.tion. Lippman (23) offers coniparative performance dat,a for heat exchange equipment in cooling hydrochloric acid, and att,ributes to Karbate equipment n higher rate of heat transfer, greater strength, and resistance to corrorion. .I paper soon to be puhlished presents experimental ( h t a for t h r absorption of liydrogc~nchloride in cooled Karbate
1
,
1204
INDUSTRIAL AND ENGINEERING CHEMISTRY
towers and shows the operating Luriditions for units producing commercial acids u p to 35 weight 70hydrochloric acid. The call for hydrofluoric acid and fluoride salts created by the increased production of Freon, aviation gasoline, an aluminum for war purposes was also instrumental in establishing broader applications for impervious graphite. Callaham (9) reports the use of Karbate coolers and pumps in the manufacture of hydrofluoric acid, and presents a corrosion table showing that carbon and graphite materials have excellent resistance to the action of hydrofluoric acid of less than 65% concentration, soluble acid fluorides, hydrofluosilicic acid, and soluble silicofluorides. The new fluoborate plating solutions are a postwar application for Karbate equipment. With the petroleum industry moving into the field of chemical> production, corrosion problems have assumed serious importance in many refineries. Operators of a sulfuric acid plant in conjunction with a large oil refinery report (13) that impervious graphite piping was selected and installed after a variety of materials had been tested for over two years. The use of impervious graphite bayonet heaters in a new acid sludge circulating and heating plant at Union Oil Company is described in a recent article (4). Plate $ewers employed in certain refinery by-product processes are subject to annoying corrosion, Trays and bubble caps of both regu>!ar and impervious graphite appear to be a satisfactory solution. A recent publication (2) describes the use of impervious graphite ‘LO resist the corrosive and erosive conditions found in chemical tindustry ejectors. The suction chamber, steam nozzle, and diffuser are fabricated from impervious graphite and mounted in a Nuitable metal assembly. Similar examples of mechanical applications of interest to the chemical industry are bearings, mechanical pump seals, bushings, guide rolls, meter parts, etc., made of either the regular or impervious forms of carbon and graphite LITERATURE CITED
(1) Anonymous, Heat Eng., 20,No.3,188 (1945) (2) Anonymous, Ibid., 21. No. 8. 151 (19461.
-C. L. BULOW.
Vol. 39, No. 10
13) Anonymous, Iron Steel Engr., 21, No. 12, iU5 (1944). (4) Anonymous, Petroleum Refiner, 26,No. 3,138 (1947) (5) Badger, W.L.. Chem. Ind.. 57. No. 5. 858 (1945). ‘6) Be&, J. H., and Gloster,’A. J., Chem. Eng. Progress, 43, No. 5 , 226 (1947). (7) Bonilla, C . P., Chem. Inds., 57,No.5,857 (1945). (8) Burke, J. F.,and Mantius, E., Chem. Eng. Progresa, 43, No. 6, 237 (1947). (9) Callaham, J. R.,Chem. & Met. Eng., 52,No.3, 94 (1945). :.lo)Chenicek, J. A, Iverson, J. O., Sutherland, R. E., and Weinert, P. C,., Chem. Eng. Progress, 43, No.5,210 (1947). 111) De Becze, G..and Liebmann, A. J., IND. ENG.CHEM.,36, 882 (1944). ..12)Dorcas, M . J., Gas, 21, No. 6,38 (1945). (13) Fetter, E. C.,Chem. & Met. Eng., 52,No.4, 171 (19451 (14) Ford, C. E.,Chem. Eng., 54,No. 1, 92 (1947). (15) Ford, C. E., Ibid., 54,No. 2, 132 (1947). (16) Ford, C.E.,Corrosion, 2,No.4,219 (1946). (17) Gartland, J. W., Trans. A m . EEectrochem. SOC.,88, 121 (1945). (18) Hatfield, >I. R., IND.Ex+.CHEM.,31, 1419 (1939). (191 Hatfield, M.R., and Ford, C. E., Trans. B m . Inst. Chem. Engre.. 42, No. 1, 121 (1946). (90) Heise, G. W., Trans. Am. Electrochem. Soc., 74, 365 (1938). (21) Janes, M., Ibid., 75,147 (1940). (22) Kroll, W. J., Schlechten, -4.W., and Y’erkes, L. A., Ibid., Preprint 89-2 (1946). (23) Lippman, A,, Chem. & Met. Eng., 52, No.3, 112 (1945). (241 Mantell, C. L., “Industrial Carbon,” 2nd ed., New York. D. Van Nostrand Co., 1946. (25) Solan, V. J., Blast Furnace Steel Plant, 35,So. 4,454 (1947). (26) Ollinger, C.G., Chem. Inds., 54, No.5,683 (1944). (27) Poland, F. F., Muterials & Methods, 23, No.3,710 (1946). ‘28) Smyth, H.D., “Atomic Energy for Military Purposes,” Prinrrton, Princeton University Press, 1945,. ,29)Stark, W. H.,Kolachov, P. J., and Wilkie, H. F., ,4772. SOC. Brewing Chemists, Proc. of 4th annual Meeting, 1941,49. ,.30)Tucker, E. F.,and Werking, L. C., Paper Ind. and Paper World. 28, No. 1, 60 (1946). :31) Unger, E. D.,Stark, TV. H., Scalf, R. E.. and Kolachov, P. J.. IND.ENG.CHEM.,34, 1402 (1942). ,32) Vosburgh, F.J., Steel, 109, No. 11, 66 (1941:. :33) Walthall, J. H., Miller, P., and Striplin. M . M., Trans. Am. Inst. Chem. Engrs., 41, 53 (1945). 141 Winslow, N.M.. Trans. A m . Electrochey. Snc.. 80, 121 (1941)
Wrought Copper and Copper Base Alloys
-
Bridgeport
Brass Company. Bridgeport, Conn
S
INCE pure copper i 3 relatively soft and weak, it is seldom used for its mechanical properties in the construction of chemical equipment. For this purpose stronger yet corrosionresisting copper-base alloys are used. Copper and copper alloys are utilized in the chemical industry primarily because of their ( a ) corrosion resistance, ( b ) ductility and ease of fabrication, ( c ) heat conductivity ( d ) electrical conductivity. and ( e ) mechanical properties. The corrosion resistance of copper and copper alloys to fresh water, sea water, numerous liquids and gases, and the atmosphere accounts for its rapidly increasing utilization in the form of pipe lines, tanks, heat exchangers, etc. The wide use of copper and copper alloys is influenced by their moderate cost and great ease of fabrication into desired shapes. These alloys are supplied in a variety of commercial shapes such as sheet, rod, wire, and tubing, which are generally ductile and are well suited for applications requiring extensive cold or hot working, such as stamping, deep drawing, cupping, spinning, bending, forming, etc. Their high
heat conductivity is of particular iniportttiice, and accounts for the wide use of copper and copper alloys in applications dealing with rapid heat transfer, such as is required in heat exchangers, condensers, water heaters, radiators, and refrigerating and air conditioning equipment. The electrical conductivity of copper and certain copper alloys is of prime importance in electrical a p plications. MECHANICAL PROPERTIES
Bpproxiniately ten copper alloy systems are in commercial U Y today (Table I). Years ago Campbell (12) described hundreds of modifications or variations of these alloys. Many of the modifications in Campbell’s list render them unsuitable for cold working but result in excellent castings with high tensile strength. The present paper is concerned only with wrought copper-base alloys. Table I1 gives the nominal compositions, specifications, and typicaI uses of a fairly representative cross section of commercial wrought copper-base alloys of particular int’erestt o the chemi-
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