Document xjZ7xD8xagK3q27db3ajzw820

Subject To____ From___ DEPARi MENTAL CORRESPONDENCE Date August 29, 1968 ISOBUTYLENE CRACKING PROCESS PATENT SEARCH, AUGUST 28, 1968______________ Harry A. Brown Dept President - Petrochemical Lange.. Hoffman Dep-t Legal - Houston I am forwarding herewith a copy of Jeff Giller's letter concerning the subject patent search, along with a copy of his letter to Messrs. Cushman, Darby & Cushman. Jeff Giller states that in his opinion there will be no infringement of any United States Patent issued prior to August 15, 1968 in the operation of the plant described in his letter of July 26, 1968 to Cushman, et al. Giller does not, however, render any opinion with respect to the use of the molecular sieve since as of this date he has not received the requisite report from his searchers. LH:ph Attachment -317 CED0006962 Fulbright, Crooker, Freeman, Bates & Jaworski ATTORNEYS AT LAW BANK OF THE SOUTHWEST BUILDING HOUSTON, TEXAS 77003 JEFFERSON D. GILLER PARTNER August 28, 1968 Re: D-3088 - Production of Isobutylene Coastal States Petrochemical Company 6th Floor, Lincoln Liberty Life Building 777 Polk Avenue Houston, Texas 77002 Attention: Mr. Lange Hoffman Gentlemen: You have asked for our opinion as to whether the operation of the isobutylene plant which you propose to build will infringe any United States patents. In order to render our opinion, we have had a collection search made of United States patents by Messrs. Cushman, Darby & Cushman, Washington, D. C. who are our regular searchers and upon whom we believe we can rely. Their search and our opinion is upon the plant des cribed in our letter of July 26, 1968 to Cushman, Darby & Cushman, a copy of which letter is attached. Based upon an examination of the patents collected in that search and a conference held with Mr. George Adams and your Mr. John Brown, we are of the opinion there will be no infringement of any United States Patent issued prior to August 15, 1968 in the operation of the plant described in the attached letter of July 26, 1968 down to the processing of material through the molecular sieve unit. We have not yet received a report from our searchers with respect to the use of a molecular sieve in this process and so are not presently in position to render an opinion with respect to its use. No search was made nor is any opinion here given with respect to the individual pieces of equipment themselves as we understand they, with the possible exception of the molecular sieve unit, are all conventional. If you care to have the patents developed on this search, we will be happy to forward them to you. * JDG:eg Enel. ry trul\ X D. Giller the Firm CED0006963 July 26 19 CO Ho: D-3QC6 - tlioJ of Producing Isobutylene Infringement Search Josarc - Curb- -.or*, ba.rby U Cuohoun A:r-aricnn Jccurity .-ui.'lJ.ing 720 rift^c-nth Street;, ktV*. Washington, i C,, 2 JO OS Gont.voiiieu; A client of ours is proposing to build ft. plant for tho jyroaacLioii of isobutylene fror;; a stroan of liquid Ivutaua containing at least 85%. isobutene. l/ould you please uskc a collection tie arch of United States patents in order that we nay oxasyine than and do to rad.no tho probabilities of patent inf rinsecant by the pro cosy do scribed below. do coarch need bo ntftdo with re.epc'ct to the equipment itself --- only with respect to 'die process. 'do believe that, if there are infringe r.i^n.t prooierAG, they v7i.ll be with the crac.bing process dint tabes place ir. the pyrolysis furnace C, 3 a ter described, or v/ifch respect to tho pur.1 ficafcion of the C4 hydrocarbons after the C4 hydrocarbons have been separated from tho other hydrocarbons. Bo forring now to the attached drawing, a stream of liquid butane containing at leant 35% ioobutane is fad to tho pump 3 which pressurizes this stream to 250-400 psig and forcer, it through a pyrolysis furnaco G. This is a conventional hydrocarbon pyrolysis furnace iutvi.ng a convection section 4 and a creating 20no 7. In the convection section 4, the liquid butane is veggorisod and combined with diluent stoma added at a pressure of 250-400 pxig free the line- 5 in a ratio of between or.o-fourth to one pound of cfcoeu: per pound of butane. T;ie crabinuct sr.car.i and butane streams passes through the cracking sons in apuroriKiutsly 0.1 to 10.0 seconds and has mi outlet pressure from the pyrolysis furnace of 150-250 paig and on outlet tem perature of 1200-1400 P. Tho products of the reaction in the cracking sens include Cy and heavier hydrocarbons, isobutylene, CED0006964 Cuslus&h, Darby Cu.dunan July 26, IPCO Paso 2 unrelated isobu'eana, carbons. hydrocarbons, and end lighter hydro- These. reaction pi-aducts leave the pyrolysis furnace G by a line C and a re immediately cooled to stop the cracking resetion. inis ceding r.;:-.y to done by any of covoral way j ouch as by quenching with a water spray at 10 to ayproidxiafcely 1000 v*. After tills coolin';;, the reaction products are further cooled in a heat exchanger 12 by indirect heat exchange with watar to produce soiv.6 of tlio diluent steam and then further cooled in a vator-coolod leant exchanger 14 to the proper tempera" turn to reduce the. amotlnt of products in the vapor state and improve recovery of liquids in a gravity-typo separator 1G* Of course, if desired, all this cooling can bo done in less or rr.oro than three steps. Water is- withdrawn from the bottom of. the gravity separator 15 through the line 10 and the liquid hydrocarbons passed through the line 20 and the gaseous hydrocarbons through the line 21 to the absorber-stripper 22. foe al>3orl>sr-stripper 22 is of the tray type avid receives the gaseous effluent from the line 21 in its absorber section and the liquid reaction pro ducts from the line 20 in its stripper section. It is operated at 150-330 ;;>yiy and a bottom temperature of 200-300 1*. Under these conditions, the overhead gas .leaving the* absorbar-stripper 22 from the lino 24 is principally Cp.and lighter hydrocarbons. Sciuo liquid, from the absorber section is recirculated tilrough the line 20a back to the lino 8 irv.icdiatoly upstream of the gravity separator 15 raid seam gas from the otripper suction is recirculated through the line 20b also to the lino. G immedia tely upstream of the gravity separator 15. Thu bottoms* from the absorber-:;tripper 22 pas?; through the lino 25 to a tray-type fractionating tower 20. The tower 23 is operated at. 100-200 pr.ig and a bottom temperature of 400-350 F. Under- those conditions, the bull; of the Cg and CP, reaction products are separated from the Crj and heavier material with the Cg and C,j leaving; the tower 2 3 as overhead through the lino 30. The Crj raid heavier hydrocarbons are. removed as bottoms through the line 31. T\ portion of these bottoms arc returned to the CED0006965 Cushman, Darby & Cuuhran. July 2>, 1950 Pay-2 3 ab&orfoer-s tripper 22 as Iccu>. oil through the line 32 and cooler 32a with makeup lean oil added at 34 u, which >j niceup lean oil is Cg and nvuviar tuck as cjasol? no, naptha, or kerosene. 'The over]ioo.il free.; the frccfcionatlng tower 28 passes to fch.e t.rny~t.yn\j frectic.ynfl'-'o fwny 3d,- vb.icii tower 3f is ope rated uc 25t-25t esig eaiu a kottcuTi tcrparcaturo cf 3.75-275& F. Under those ec-ndirJ ons , there in a .separation, of thes Oj from tlva C,< hydrocarbons, The C3 hycirocarboas leave as overhead through line 38 and the C.j hydroearl>o:is .leave as battor.13 through the line 40. The C3 hydrocarbons in line 33 are treated to separata tits propylene from other C3 riydracarbans by a tray-typo frac tion a ting toner 42 v.with propylone leaving the upper section of the fractionating' tower 42 by the line 40 and the regaining C3 hydrocarbons leaving fro;a the lover portion by the lino 41. The bottoms in the lino 4'J from, the fractionating tower 36 are principal3.y ino'ontyior.d arsu unre.acted isebutuee. This material is fed into the tray-type fractionating tower 40 operating at 100-290 psig and a bofcio.n temperature or 200-300 F. At a point approximately nidvay between the center and the top outlet of the toner 40, a stream of furfural (a solvent) is introduced by the lino di) .in a ratio cf approximately 10 raolo cf furfural peer reel of hydrocarbon food to the toner. The original supply and the makeup furfural areplaced in the line 49 by the line 51. Under these conditions, vest of the un reacted isobutene is separated and passed as a liquid overhead through the lino 50 to the feed line, 2 at a point ir-.re.diatoly upstream of the x>utsp 3 for recycle. Tha bottom*fro;,1 the fractionation column 43 are with drawn by the line 52 and pass to the tray-type fractionating tower 54 which is eperated at100-200 psig with a botf.cn tteaporature of 400-500 F. Under these, conditions, the hydrocarbons contained in the bottom from the tower 48 arc stripped from the furfuraland withdrawn, from the top of the tower 54 by the line 58. Thefurfural is withdrawn from tower 54 by the line 49 and recycled to tower 48. The material leaving tewer 54 as overhead by line 58 is principally inobutylena. CED0006966 Cushman, Darby Cushman July 26, 15 GO Pag.;i 4 Ahe furfural vrhieh ir? introduced into the fractiona tion tovar 48 is a. sale stive Delve-, it arid :l:; chosen bsceuse it has the. property of increasing tho difference ir: volatility between isobuteno and isobutylene and tiro property of a lover volatility than either ioohutono or isobutylene. '.-.'ho material it; lino SO pas tea; through tho jaolocular sieve unit C0-v;hieh is a type uanufa.-;turn;'; for the: absorption cf straight chain hydrocarbon molecules and passage of branch chain hydrocarbon nolcculcs. bo-.-o butene-*!., butcno-2 and normal butarn -will prebobiy bo included in the reaction products and be In tho line 58 loading to tho^isoleculnr sieve GO together with the isobutylene. The uolecular sieve GO will rerauve this buter.o-I, butene-2 and normal butane by absorption. Yours very' truly. JPG:eg Attachment cc: Mr. Go orgo F. Adams Mr. John Brown Mr. Lange Hoffman Jaf S :. ;:on b. Gil7s,or for tho Id ?.vi CED0006967 0,+tJ lighter \ \ i .) v' o CED0006968