[1]Patented Sept. 25, 1928. UNITED STATES PATENT OFFICE. ALPHONS 0. JAE, GER, OF PITTSBURGH, PEXNSYLVANIA, ASSIGNOR TO THE SELIDEN COMMANY, OF PITTEBURSH, PENNSYLVANIA, A CORPOF.ATIOlq OF Dr@,LAWAr.Y,. CATALYTIC- APPAPATUS. Ap'plieation illecl October 27, 1926. Serial l@To. 144,496. T.his invention r@lates to catalytic apparatus and particulirly to cat-alytic apparatus for use in exothermic vapor phase, catalytic rentions. The problern of cooling the catilyst in converters is a qerious one when the reaction carriedoutisstrouglyexotherinic. Ttibularconverters in which the catalyst is p@laced in sinall tubes hove proved to be satisfactory foi- many Io exothermic react-ions. However, this type of converter is open to a. number of disadvantages froih the standpoint, 6f strtict-ure and operation@. Thus, for example, it is fi-eque'ntly difficult to adjust the resistance, of the va15 rio-as tubes and uneven gas flows and other undesirable actions result. Trty or layer con.verters siieh as for exaniple the Grillo sulfuric acid converter and others in which the catalyst is present in relttively large layers, 20 present many advantages from the standpoint of even gas flow and cheapness of con.,truction. It is, however, very difficult to cool the cat-alyst in such converters e-venly and uniformly when the apparatils is used 25 in'exothermic reactions. Ilorizontal layei@s .of catalvst are comparatively easily cooled at their' criphei-y, but teiad to become hot in p the central zones. . It has beeii'proposed to operate a modified 'O tubular converter in wliieh the catalyst is not in the tubes, but surrounds them, and cooling liquids or coolino, gases,,tre cireiilated throu-h the tubes. Il@ i@ possible b@V this method @'to re,taih many of the advantages of a layer type ?,5 converter and at the saiiie time to bring abcut sufficiedt cooling. It is, however, not possible in the ordinarv construcfion witli tinifoi-m tube placement.. io effect uniform cooling, since t,he- peripheral zones which are coole(I 40 jiot on@y bv the eirculitin(v ttibes, but also by the converter shell itself ,Ire over-cooled if the cooling is sufficient to keep the centi-al portion from overheating and, on the contrary, if the cooling is adjus to be correct for the 45 periphera-I zones;'i,lie, -tl zones are undercooled. In many cat tic reactions, it is itist as important to pr t under-cooling as over-cooling and the aiin shotild always b.e to bring abo,ut a uniform temperature. This 50 is particularly t-rue in reversible, reactions in whie,h t-he equilibriun-i depends very l@rgely on the t6mperattire and is also@ true in t-he ea-se, of 'reactions which tend to produce undesired siae reactions when the optimum tem55 perature, range is either exceeded (Dr irot reached. This colidition frequentlv arises ila the oxidation of organic con@pounas such as, for example, arom,@ltic compo-unds wliere undesired by-prodiicts are frequently produced. when the r(,,action teiiiperatures are not main- 00 tai@-ned unifoi-m throughout the catalyst mass. In the co-pending application of Jaeger and Bertsch, Serial No. 100,818, filed April 9, 1926, and niy prior I api.)Iic,,tt.ion, Serial No. 124@@69@ filed July 24, 1926, I have described 65 converters hoving modified shapes of eoo-ling tubes. These converters show a rernarkably increased efficiency of cooling, but are, open to the saine objection of non-uniformity of cooling unless the 6ooling elements are ar- 70 ringecl as described in the present invention. I liave found that a. perfectly uniform cooling of catalysts ca-n be e:ffected with any suita,61e type of cooling tubes oi- with any combinati on of types of cooling tube@ by propo@r- 75 tioning either the, nurnber of the tubes, their p eril)lie,ries, the gas veloeities passing theretl irouah or the gas temperatures, so that the c entr&LI zones of the catalyst are cooled more st ron,@ly than the peril)heral zones. This re8 0 s ults in a unifori-n te-mperature throughout t he catalyst, mass since the peripheral zones, is has been pointed otit above, receive, additi onal cooling from the external converter s hell. 8 5 The provision of increased cooling effect in t he center of the ea-talyst which is the object of t he present invention does not depend primari ly upon any definite heat conductivity of the c at,,tlyst it@self. In general, catalysts are poor g o li eat conductors partly because the substonces u sed are themselves poor con etors of heat a nd largely because the catalyst o f granules which touch only a The eictent to which it is nece 9 5 t he cooling of the central port-ions of t cattI vsts will depend, of cotirse, on the heat transf er cliaracteristies of the cttalyst and it may b e desir,,tble to intersperse rnetallic bodies with the catalysts eit,her in the form of gron1 00 u les, meta.] shavings, chips, wire mesh or otlier f orms in orde@ to increase the heat conducti vity of the ea-talyst layer as a whole. It s hould be clearly uiiderstood that the use of s uch aids is not in itself new %nd is clairned 1 05 i n the p,rese.Dt inyention only in combinatioil - ,Arith the cooling element arr,%ngement whi6h forms the stibject matter 6f the present inv -ention. IncidentaHy, it may be pointed out that the addition of bodies of high heat eon- ilo
[2]1,685,672 ductivit.y to the cat-,tlyst layer is a palliative only since the metallic, granules, meshes, or qtber bodies do not touch. each other over ,-reat surfaces and accordingly are subjected 5 to the same I)-cat transfer disadvantaaes which n are present in the catalyst la.),er itself. The structural arrangernent and design of the cooling elements may be varied'and anv suitable arradgernent may be used. In tl@(-@ drawings, a fe@v illust'r@iive examples will. @be used but it is to be understood that the inventioll is in no sense to be limited tliereto. Similarly, only,a few of the modifications of coolilig element design described in the prior applicationg to myself and of Jaeger iiid Bertsch referred to above are sbown biit ,tny of the modifications which are described and claimed in these applications may be utilized in conjunction of the elemerit arrangenient of 20 the present inventiod. The invention will be illustrated in greater detail in con'nection with the drawings in which a few typical modifications of the presend invention are shown. The drawinos are 25 purely diagramm:itic in nature and are reduced to the essentials of the converter structure. In any given installation, of course. the various accessories and struettiral detail,,which. are well,known to convei-ter engineers .10 may be used but since they form no pai-t <)f the present invention spocific st,ructural features arp- for the most part omitted from the. drawings, in which Figure I is a sectiofi throiigh a tube-cooled converter provided with plain tubes; Figure 2 is a section throu(,rh a converter having double travel cooling elements; Figure 3 is a vertical gection through a strai,o,,ht tube convefter provided with tubes N,i @n_ 40 ha_ varying gas velocities; Flgllres 4 end 5 are sections through dotibl(, travel tubular converters having simila'r me,,ins for varyino@ the gas speed through zn the cooling iubes 45, Figures 6 and 7 illustrate layer or tray tvpe converters with horizontal coolino, tubes, Pl'gure 6 show' -uniformly s ing noin. paceil plaiii tiibes and Figifre 7 sbowing unif@rmly arran(yed tubes for varying gas velocities; and r .10 Fi(rures 8 and 9 are sectioris through tubular converters provided with series g,,Is flow throu,gh the cooling elements and accessory spray cooling. In Fig.ure 1, the converter is shown as r,5 formed of a cylindrical shell 1, a top piece 2 and bottom plate 3. A partition 4 extends @or the f ull widtb of the converter at the upper end'of the cylindrical shell and a perforated partition 5 is arran-ed at a lower C-0 portion of the shell. Straight cooling tubes 6 p,,tss thi-ough both partitions and are I surroiinded witt catalyst as shown at 7. Reaciion gases eiiter the top piece at 8, are di,,@tributed bl:, -means of baffles 9 and pass do-wn(i5 wardly tl7@ough the cooling elements 6 into a space 10 formed by the bottoiyi plate 3, the shell 1 and the pelforated partition 5. From tllis space the Lyases pass upnvardly tbrough the perforate(I @artition,,tnd throu&,,Ii the catal st into a space-11 which is formed 70 y betweeii the upper surfaoes of the c-.ttalyst and tlle upper partition 4. Tlle i-eacted (ri,s(,s then 13ass out throu(rh an openin,-'12'in the shell 1. It will be noted that the cooling tubes are 75 ai-i-an(,ed much closer to(retber at t@e center than at the peripbery and the tliiekness of the - slices of the catalyst between the coolina tubes increases rapid ly from the center toward the periphery. The placeiiient inust, of course, 80 be ebosen to effect uniform cooling for any particular reaction and in general will viry with different reactions which evolve differeiit quantities of heat and whiell necessit,,ite catalysts of varyinu conductivities. 85 It will be apparent that the cold reaction gases are lieated by passin(r throucrh the coolin- eleriients to a substani7lally uniforin temperatui-e and at the same time the catalyst is uniforrnly cooled, resultiiig in the constant maintenance of an optimum temperatiire throug@bout the whole of the, catalyst layer. A pltirality of reacting crases may be introduced instea,d of one reacting gas and if desired, dilrepent reacting gases may pass througli differ(@nt tubes. In general, throu(rliout the fig'ures, only a single reaction (Yas or mixture of reaction gases are shown biit it sliould be understood that a plurality of reaction gases. may be introduced at tlie, saine 10( or diff ereiit portions of the converter. In Figure 2 a converter of the type illustrated in the application of Jae(rer and Bertsch above referred to is shonvn. The are Ai o--iire 1 but I 0 1r) rang ment is siinilar to tbit iii F tD instead of single tubes 6 passing froin the upper partition 4 throiigli the lower ]3.'Lrtition 5, dotible tube elements are provided consisting in closed tubes 13 embedded in the c,.ttalyst and open tubes 14 extendin(T downw.Ird- II(, t, ly from the partition 4. The cr,,tses passill(T in tbrough tl-ie opening 8 and being iuixe(I 1) )T the baffles 9 pass doivn throuo;li ttic tiil)es 14 to the bottom of the ttibes 13, tlience upwirdly throtigh the anniilar space between tile I tubes 13 and 14 and downnvtrdly tliroti-ii the catalyst into cliainber 10 tnd otit the exit pil@e 12. i b.nee the coolinu tubes in the cejiti,al I)ortion bf the catalyst are ,,ri-an(,ed (-Iosei- to- 12(@ g-ethet- tl-ian in the peripheril 1)01@tio]IS, tlie, cooling effect decreises froiii the conter toward the periphei-y and AN-beii the sl):iciii,, li:is been adequately adjusted for the pai-ticiilar reaction which is to be cii@ried out a pei-fect- 12.1) ly uniform cooling is effected. ' The converters shown in Fi--iii,es 1 an(I 2 o erate very satisfactorily ivllen the sl),I(.in(, oy the eleraents is properl@ arran(yed -,vith respect to the heat transf-er capacit@ of the cat1.1(
[3]alyst to the nature of the rea'ction taking place and also to the. speed of flow of the gases tbrough the converter whieb in turn deter.n,iines the amount of heat evolved and also' attects to a certain extent@the heat distribution, since an increased gas flow within the limits of 'Complete reaction results in a, corresi)ondinz increase in the heat evolved wh'ch, however, is partially Deutrrlized, as lo far as the tubes go, by a stibstantially equal increase in the - ,tmotint of coolin (rases pass9 - hroual-i theiii. There is no c4ange in the "l@itat i'a iofi froin the converter sl ell and iccordingly the relative effect of the converter 15 shell cooling is di:fferent at bich gas velocities fron-i that at low gas velocities. There is also a difference in'the cooling effect in the tubes since at higher gas velocities the aas may not be heated up to quite as hio-li -,t tempera20 ture. 0-nee biiilt therefore converters 8uch as th'ose illustratec-I in FigLii'es I and 2 and similarly conve'rters siich as are shown iinFigLire 6 which will be descri@ed later on ire designed for full efficiency o@ly with a definite catalyst and with a definite reaction speed. It is possible to obtain satisfaotory regulation and at increased flexibility by varying the proportion of g,,ises flo%ving throtigli the different cooling elements even though the latter are uniformly placed. This is illustrated in Figures 3, 4 aiid 5 in, wliich the ttibes 6 and inner tubes 14 respectively a,i-e pi-ovided .%vith plugs 15 and 1,6 of different opening sizes whereas no plugs are used on the central tube. Iii the case of Figure 5'only one size ?f plug is used but an additional compens@Lting effect is provided as will be described. In Figui-es 3 and 4, therefore, a gteater ainount of gas flows througli the central tubes ,11@ 6 and 14 than through the interi-nediate tubes ,which, in turn, have a greater flow than the peripheral tubes. Ob-viously, 6f course, more than t@vo sizes.of plug openings will be used as in the brdinary converter there are usually a larger number of cooling eleinents than shown in the diao-ra-mmatic drawings wliieh, for the sake of siwplicity have been restricted to a relatively swall nuriaber of cooling elet-herefoi,-,, ments. The central elements are, t,o cooled much more intensely than are the peripheral elements and when the relative gas flow has been properly a-djusted a perfectly uniform coolino, results. This method of controlling coolino,, has the advantac,,e that it can be adapted to varying gas flows and varyin-a reactions by using aifferent sized plugs wrthout rebuilding the cbnvei-ter. In Fio-ure 5, gn addition to the provision of plugs 15 and 16 in the tubes 14, these latter are of varyused, but is not as desirable as. a sudden line of demarcation between the cooled and uncooled portions of the tiibes 13 is thereby produced - which is unclesirable iii @ inost cases. The perforations perform the same function 70 of reducing the effective leng@li of the tubes btit sonie Lyas is Dermitted to flow down to the bottom o@ the tubes 13 so that there is no sharp lineof den-iareation betllveen the cooled and - Lincooled portions. 75 Figu res 6 and 7 illustrite converters with horizo ntal tubes and separate cooling gases. The converters consist of shell 17 top, piece 18, bottom piece 19, biffle 2Q, peilforated partition 21 and catalyst layer 22. Horizontal 80 coolin o, tubes 23 pass through the catalyst and th@e coiivei-ter shell and connect cooling g,,ts mains 24 and 25. Reaction gases enter throug h an openiiig 25 in the top piece IS and after passing through the catalyst pass otit 9 through an opening 21 in the bottorn pieco. 19. In Figtire 6 the cool inlr tubes are arrangpd asymme trically, that is to say, they are more closely spaced in the upper portion of the catalyst layer than in the lower portion with the result that ii-i the upper portion which comes in contact with the fresh reaction gase . s and accordingly produces the most violent reaction with the evolution . of the greatest amount of heat, the cooling is at a maximuin. The converter sbell can be rectangu'-ar or eylindric al -and the distribution of tube@9 sbould be such as to provide for a uniform cooling in each zone of the catalyst. Inst ead of spacing the ttibes asymmetrically the amoi-int and velocity of gases passing, through the tubes rnay be varied. This'construction is shown in Figure 7 where'plugs 27 and 28 are provided in the lower tubes in @order to restrict the ainount of cooling gases 105 which pass through these tubes. Of course, a combination of spacing and varying gas velocitie s may also be used and in many cases may prove desirablo. 'the cooling gas used in Figures 6 and 7 may be air or any other available gas or the reaction gases may first be 'passed through the cooli-.ng tubes and then into the converter, tlfus effecting cooling simultaneously with the warming up of the reactioii gases. Liquids and vapors inay also be used. Combinations of there two methods m,ay also be utilized. Cooling gas may also,,be passecl in' series through the,various tubes first through those in the hottest -zone. This has th,e ad- 121, vantfiae tliat the lower portions of the catalyst zone in which the reaction proceeds 'very slowly by reason of the fact that the reacti6n gase@ are diluted -with the ieaction prodlict, ing effective len,--ths. A illusttated in tWe - require little or.n-o 6oolinLr and may in some 1'2,'D tn dre, v@ing the length variation is elfected by cases actually Tequire hq@@ating. I:6stead of pprforating the lower portions of the tubes @14 straigh@ tubes, spiral tubes ifiay be used, in to di:fferent pipes which brings about the tb.e various zones and other modifications of: same result as if the tubes were shortened. placeinent of cooliiig tubes in order to bring co The la.tter expedient can, of, c(bursej a@so be about unif6rm coolinguaa'y bs utilized. 130
