Патент USA US2108636код для вставки
‘Feb. 15, 1938. 7 H, \(_ ATwELL ’ 2,108,636 PROPANE TREATING IN CRACKING SYSTEMS‘ Filed Feb. 16, 1934 ' 5% .34 ?bsor'e 65 5$5 8.3‘ 60. 61 Pr'elim; 7Fl&a1s"h, 4 J CTlaera’n_ INVENTOR [go/1446(5 ATTORNEY atented Feb. 1, I13’ namia v. Atwell, White Plains, n. y, a .to Standard Oil Company, Chicahh, a cor I pcration of Indiana Application February 16, 1934', Serial at. that"! ' 4 Claims. (cl. 196-13) This invention relates to the use of propane in cracking systems and it pertains more particu larly to an improved low temperature method of ?ltering pressure tar and of recovering and ,uti 5 lizing valuable products resulting from cracking the naphtha or gasoline being withdrawn‘ for use, and the dry gas being scrubbed with and partially absorbed by the tar which has been previously cooled, preferably by heat exchange with incoming stock. The absorption of these 6 gases in the cooled pressure tar accomplishes at least three important ‘results: (1) it reduces oils or other carbonaceous materials are heated to the viscosity of the cooled tar so that the tar about rI50" F. to 1250° F. at pressures ranging‘ may be readily handled and ?ltered at ordinary 10 room temperatures through simple canvas ?lter 10 from atmospheric to 1000 pounds per square inch, and the reaction products are usually maintained elements in conventional closed ?lters; (2) it ,under pressure at é‘elevated temperatures for a. facilitates a sharp separation between valuable suf?cient period of ltime to allow the conversion tarry and asphaltic compounds and lime, coke of the oils or carbonaceous materials into light and ‘objectionable carbonaceous solids whereby 15 increased yields of by-products are obtained and hydrocarbons such vas gasoline, heavy hydrocar bons generally called “pressure tar,” and gases decreased yields of obnoxious, dimcultly dis-' posable ‘residues are obtained; and (3) it pro containing - appreciable ‘amounts of propane, “vides a means for utilizing lime (which would ethane, propylene, ethylene, etc. It is conven be wasted) for sweetening the cracked tional practice to use lime or equivalent materialv otherwise gases and removing objectionable sulfur com 20 inv the cracking stock for preventing corrosion, 120 for preventing carbon depositiontor for other pounds therefrom, the sweetened gases being re covered in the auto-tar distillation process. In purposes. This lime or other solid material ac cident to the above accomplishments are in cumulates in the pressuretarv and it is conven creased yields of valuable products, increased tlonal practice to ?lter the pressure tar at temperatures of about‘ 350-500° F. (above the ?ash ?ltration rates, decreased’ labor and equipment point of the oil) to remove the lime, together -“ requirements and decreased load- on the treat units. Other advantagesi will be apparent with coke particles or other solids. The high ing from the following detailed description. temperature is necessary because of the‘extreme In the accompanying drawing which forms a ly high viscosity of the tar at lower-temperatures. part of ‘this speci?cation, l’. have shown a dia 30 However high temperature pressure-tar ?lters 30 require the use of special ?lter elements which grarrm'iatic layout of my improved system. ‘ " operations. In'the production of cracked gasoline, mineral The feed stock, which may be a petroleum gas ' oil, for example 3ll—35° A. P. I. midcontinent gas An object of my invention is to provide a meth od and means of ?ltering pressure tar at low oil or any other carbonaceous material which commonly consist largely of‘ asbestos. can be converted into lighter or more valuable temperatures. ' ' ' A further object of my invention is to utilize the I pressure tar as an absorbing oil for removing products by cracking or polymerization, is vin» troduced through line it, re?ux coil l2 and ear changer it to pipe still it in which it is heated ' propane and other normally gaseous hydrocar bons from the gaseous products resulting from v to cracking orvpolymerization‘temperatures. The hot miirture is then'introduced throughline it ‘ 40 the cracking operation-from the so-called to soaking ,drum it which may be. an enlarged A further object is to provide an improved‘ reaction vessel'or which may be merely an elon cruising system which includes .‘the recovery gated conduit of small cross sectional area con to a hash chamber for separating tars and utilizationoi propane and ‘other normally nected from vapors and gases. The vapors and, gases “high line gases” or even the so-called “wet gas." gaseous hydrocarbons.v ' . Other objects will be apparent as the detailed are conveyed by pipe ll to a lower or interme-' charging'stock by subjecting it to elevated tem“ diate point of fractionatlng column 58, the “bot toms" fromv this column being recycled through line lg to the cracking or polymerization heater. If. desired, I may introduce the feed stock through paratus. The low-boilingproducts, including cy it into the heater with the cycle stools in line 09. description of my invention proceeds. _ in practicing ,the invention I may crack car bonaceous materials such as gas oil or other peratures and pressures in any conventional ap- - ‘ valved line it directly into line ill and introduce cle stock,‘ light and heavy naphtha, condensables and fixed gases, are fractionated, the cycle stock 55 being returned to the heater oi the cracking unit, Vaporized naphtha and normally gaseous. hy drocarbons are moved from the top of column l8 through line 2| and are passed through con 55. 2 2,108,636 denser 22 to separating chamber 23. The tem perature and pressure conditions in the separat ing chamber may vary throughout a relatively wide range, it being designed to remove normally liquid products such as pentane, hexane, etc. from normally gaseous products suchas propane, ethane, butane, propylene, ethylene, etc. The liquids from separator 23 are introduced through line 24 to a stabilizer 25 which is provided with 10 a suitable heater 28 and with re?ux means 21. Gasoline is withdrawn through line 28 and the propane and normally gaseous products removed from'the gasoline are withdrawn through line 29 to storage tank 30 thence to lines 3|, or 32,‘ 15 which will be hereinafter described. - The dry gas from the top of separator 23 is led through pipe 33 to a lower or intermediate point of absorption tower 34 wherein it is scrubbed by tar which has been withdrawn from 20 soaking drum I 6‘ through hot tar line 35, cooled in cooler 36, and led to the top of the absorption tower by pipe 31 which should be short and of large cross sectional area. Methane and unab sorbed gases may be vented from the top of the 25 absorber through pipe 38 which may lead into the conventional re?nery dry gas line or high line. Likewise gas from the top of storage 30 may be vented through pipe 33a and propane from line 3| may be introduced into the tar scrubber 30 with gases from line 33. The absorber is prefer ably operated under a pressure of from 250 to 400 pounds and at ordinary atmospheric tem peratures of approximately 60° to 100° F. Under these conditions ‘a suflicient amount of propane 35 is absorbed by the pressure tar to cause a strlkf ing decrease in viscosity and to effect a thorough washing of the lime particles. These lime parti cles are thereby rendered accessible for chemical action on the undesirable sulfur compounds which are present in the gases and the propane introduced through pipes 3| and 33 and the gases which are introduced through these pipes are ,_ thereby‘ sweetened to a material extent. The amount of liquefied gases which are absorbed 45 by the pressure tar is usually less than 10% of the volume of the tar and under these condi tions there is no appreciable phase separation of asphaltic compounds from propane. .However, the reduction of viscosity is so great that ?ltra 50 tion may be readily effected through ordinary canvas ?lter leaves either in batch ?lters or in continuous rotary ?lters. The lime, coke and carbonaceous particles separate readily from the diluted tar to'give a cake which may be easily 55 discharged and which may be disposed of much more readily than hot ?lter cakes heretofore ob tained. Thus it will be seen that I have elimi nated the necessity of using asbestos ?lter ele ments andwof operating at temperatures of from 60 400° to 500° F. and'at the same time I have made it possible to obtain very rapid ?lter rates and to obtain almost quantitative separation of valu able by-products. _v p The relatively cool diluted pressure tar may " that suitable heat exchangers may be employed to supply the heat necessary for removing the propane, naphtha and cycle stock from the ?ash drum residue which may be used as a fuel oil or as a road oil. Flash drum 46 corresponds to the conventional auto-tar plant. Settled material from settler 42 may be with drawn by pipe 41 and ?ltered material from filter 40 may be withdrawn through conduit 48, and in each case the residue may be flashed in cham ber v49 to recover propane and valuable oils through line 50. Unevaporated liquids may be drawn from flash drum 49 by line 49a. Fuel oil, road oil or tar is withdrawn from ?ash drum 46 through pipe 5| and the propane, together with naphtha vapors and heavier auto-tar distillates are removed through pipe 52. Propane may be passed by line 53 or compressed by pump 54 and then passed to condenser 55. Liquids are collected in tank 56, gases being withdrawn through vent 51 to a gas fuel line and sweetened propane and heavier liquids being withdrawn through line 58. Instead of cooling the entire volume of pressure tar before absorbing propane vapors, I may ?ash the tar by introducing it through line 59 into auto-tar still 60 which may be supplied with steam heater 6| if the heat of the tar is not sufficient to effect the desired vaporization. Auto tar distillate may be removed through line 62, 30 condenser 63, receiver 64, etc., and the residue may be passed by line 65 to line 35 or line 31. While I have described in detail the preferred embodiment of my invention, it should be'under stood that I do not limit myself to the speci?c arrangement hereinabove set forth or to any of the details hereinabove described except as de ?ned by the following claims which should be construed as broadly as the prior art will permit. I claim: 40 1. In a process wherein hydrocarbon oil is sub lected ‘to conversion conditions of temperature and pressure to produce motor fuel, and a rela tively viscous pressure tar which is characterized by‘having asphalt in solution and by having sus 45 pended contaminating insoluble solid matter therein which renders saidtar diiiicultto ?lterthe improvement in refining said pressure tar to make it suitable for fuel purposes which comprises cool ing said tar, conducting said cooled tar into an 50 absorption chamber, conducting normally gaseous hydrocarbons which are substantially free from gasoline to said chamber, intimately contacting said cooled tar and said normally gaseous hydro carbons and dissolving not more than about one 55 liquid volume of said normally gaseous hydro carbons in each ten liquid volumes of said tar, thus decreasing the viscosity of said tar without precipitating any substantial amount of asphalt therefrom, separating undissolved gaseous hydro carbons from the viscosity-reduced tar, passing 60 the said tar and dissolved normally gaseous hydrocarbons into a separating zone and separating said contaminating insoluble solid matter from be passed by line 39 to ?lter 40 or it may be - the said viscosity-reduced tar, and thereafter - passed to linev 4| and settler 42 or it may be removing the dissolved gaseous , hydrocarbons 65. passed'?rst to settler 42 and the decanted liq from the tar. uids passed through pipe 43 to the ?lter. Tar in 2. In a process wherein hydrocarbon oil is sub line 39 may be further diluted with propane from jected'to conversion conditions of temperature 70 pipe 32. and pressure to produce motor fuel, normally The ?ltered or settled dilute pressure tar from gaseous hydrocarbons substantially free from which all solid matters have been removed is in gasoline, and a relatively viscous pressure tar troduced by pipes 44 or 45 to ?ash drum 46, it which is characterized by having asphalt in solu-,' being understood that a suitable collector and. tion and by having suspended contaminating in-I 75 feed pump maybe interposed in this line and soluble solid matter therein which renders said 75 2,108,636 tar dimcult to ?lter, the improvement in refining 3 which is characterized by having asphalt in solu tion and by having suspended contaminating iii-. , said pressure tar to make it suitable ‘for fuel pur poses whichcomprises cooling said tar, conduct- ' soluble solid matter therein which renders said said chamber, intimately contacting said cooled tar dif?cult to ?lter, the improvement .in re?ning said pressure tar to make it suitable for fuel pur poses which comprises cooling said tar, conducts tar and said normally gaseous Hydrocarbons and in'g said cooled tar-into an absorption chamber, a ing said cooled tar into an absorption chamber, conducting said normally gaseous hydrocarbons to ‘dissolving about one liquid volume of said nor mally gaseous hydrocarbons in each ten liquid ~10 volumes of said tar, thus decreasing the viscosity conducting said normally gaseous hydrocarbons to said chamber, intimately contacting said cooled tar and said normally gaseous hydrocarbons and of said tar without precipitating any substantial dissolving about one liquid volume of said normal- - amount of asphalt ‘therefrom, separatingundis solved gaseous hydrocarbons from the viscosity 1y gaseous hydrocarbons in each ten liquid vol umes of said tar, thus decreasing the viscosity of reduced tar, passing the said tar and dissolved said tar without precipitating any substantial 15 normally gaseous hydrocarbons into a separat amount of asphalt therefrom, separating undis ing zone and separating said contaminating in soluble solid matter from the said viscosity reduced tar, and thereafter removing the .dis solved gaseous hydrocarbons from the tar. 3. The process of claim 2 which comprises sub 20 solved gaseous hydrocarbons from the viscosity reduced tar, passing the said tar and dissolved normally gaseous hydrocarbons into a separating jecting said pressure tar to a ?ash distillation and removing a distillate fraction therefrom prior to the steps of cooling and separating said tar. 4. In a process wherein hydrocarbon oil is sub 25 jected to conversion conditions of temperature and pressure to produce motor fuel, normally gaseous hydrocarbons substantially free from gasoline,'and a relatively ‘viscous Pressure tar zone and ?ltering the said viscosity-reduced ta'r. vto remove contaminating insoluble solid inatter therefrom without removing any substantial amount of asphalt from the tar, and thereafter removing the dissolved gaseous hydrocarbons from" the tar whereby the-tar is converted into afuel relatively rich .in asphalt and relatively free from suspended insoluble, and non-combustible matter. 2 HAROLD V'. ATWELL.