US2249461A - Manufacture of antiknock gasoline - Google Patents

Description

July 15, 1941.

I F. F. DiwoKY .2,249,451

MNUFACTURE QF ANTIKNOCK GASOLINE F11e 1 Aug. 17, 1937 s sheets-sheet 1y FIG. 1.

ATTORNEY F. F. DlwoKY MANUFCTURE OF ANTKNOCK GASOLINE July 15, 1941.

s sheets-sheet, 2

Filed Aug. 17. 1937 July 15, 1941.

. F. F. DlwoKY MANUFACTURE OF ANTIKNOCK `GASOLINE Filed Aug. 17, 1937 Y25 vSheets-.511661. 3

ATTORNEY Patented Juy 15, 1941 MANUFACTURE F ANTIKNOCK GASOLINE Fred F. Diwoky, Chicago, lll., assignor to S'tandard Oil Company, Chicago, lll., a corporation of Indiana Application August 17, 1937, Serial No. 159,473

4 Claims. (Cl. 196-50) This invention relates to the manufacture of motor fuel of superior quality, particularly as regards anti-knock characteristics.

The invention contemplates a process in which a gasoline or naphtha stock is closely fractionated to form a plurality of relatively narrow boiling range cuts and the cuts of relatively lower anti-knock values collected and subjected to reforming to increase the anti-knock value of such cuts. In accordance with the invention a gasoline-containing stock is subjected to a. suiilciently close fractionation as to at least approximate an analytical fractionation of the stock with reference to its hydrocarbon content. In other words, the stock is fractionated to such a degree as to concentrate individual hydrocarbons whose anti-knock value is an irregular function of boiling point. Thus when the fractionation is carried out to a sufficient degree the antiknock value curve will exhibit marked irregularities and the cuts or fractions representing the valleys of the curve may be collected for reforming while the cuts or fractions representing the peaks of the curve may be collected to constitute a high anti-knock product, or used for f blending with the gasoline product or fractions thereof produced inthe reforming operation.

The invention also contemplates that the products produced in the reforming operation may be subjected to a high degree of fractionation to `segregate constituents which have not been sufor solvent-capable of selectively removing olefinic constituents. By treating the stock with a polymerizing agent topolymerize the oleflnsA or by treating the stock with a solvent, such as liquid sulphur dioxide, the oleiins may be removed so that a sharper separation between' re1- atively high and lowanti-knock constituents may be accomplished by subsequent fractionation. Highly cracked stock will ordinarily contain, in addition to olens, proportions of aromatlcs and naphthenes. hydrocarbons will have boiling points approximating theV boiling points of certain of the straight-chain paramn hydrocarbons. In the practice of the invention the stock containing oleilns, aromatics and naphthenes as well as parains is treated with -a solvent, such as sulphur. dioxide. kcapable of removing the bulk of the oleiins and to a greater or lessextent aromatics and naphthenes, thus concentrating the branched chain or iso-paraihns in 'the raihnate with the straight-chain paramns and facilitating the separation, by subsequent fractionation of the raf` iinate, of the low anti-knock constituents from the high anti-knock constituents. The branched chain or iso-parailins possessl maximum antiknock qualities and by removing from the gasoline stock oleiins as well as aromatics and naphthenes and concentrating the iso-parafdns in `the raillnate, -the subsequent fractionation operates to separate the iso-paraiiins from the straight-chain paraillns. It is advantageous to use solvents such as liquid sulphur dioxide from which the absorbed high anti-knock constituents may be recovered, thus accomplishing a maximum yield of highI anti-knock constituents.

'Ihe invention may lwell be described as applied to the treatment of a gasoline stock for the production of a high gradegasoline suitable for aviation service. 'I'hus in an example of the invention, a, light naphtha obtained by the distillation of a Mid-Continent crude petroleum is subjected to fractionation with a. reflux ratio of 301-1 into some seventy closely cut fractions. 'Ihe following table gives the temperatures at which Ithe several cuts are made, the octane number of the vcuts (by the Cooperative Fuel Research Motor method) and the volumes of thel several cuts. The iirst eleven cuts, being of very light character, are not ined and hence the data in reference to these cuts are omitted from the table. The cuts are shown assembled in two groups, the one group including the cuts having an octane number above 68 and the other group containing the cuts having an octane number below' 68.

Many of these high anti-knock Max Cuts above 50 o. N. c. F. RM. cuts below 00 o. N. 0.1. n.14.

Ct Te Vlumesac. Ct Tm., Vi N. @-N- M0 1. 10%. ew? -N- Lif" 12 04 00.5 1,011 1a as? 00.0 051 14 00.0 001 15 04 -04 0 152 10 04 01.0 540 11 04 -50.5 515 1s 04 02.5 040 10 00 -10.0 051 100 -10.0 450 21 02.0 014 22 131 10.0 000 zz 15s 11.0 100 24 100 14.0 251 25 '0&5 551 20 140 05.0) 02a 21 140 '50.0 011 2s 141 51.0 00a 20 14s -44.0 000 a0 141 43.0 040 a1 150 00.0 015 a2 155 22.5 015 as 150 01.5 015 34 150 50.0 025 35 155 45.0 002 a0 151 51.5 005 .a1 510 *00.0 020 5s 10.5 015 00 '00.0 000 110 10.5 015 41 1&0 s45 42 105 -15.0 000 4a' 104 11.5 024 44 11.0. 000 45 104 10.5 001 45 10s *10.0 041 41 100 10.0 520 4s 100 00.0 sas 40 200 00.0 040 202 -50.0 001 51 202 43.0 011 52 200 52.5 050 50 200 -200 001 54 214 -a0.0 a02 55 214 :42.0 1.010 50 215 '31.5 052 51 215 41.0 120 5s 215. 52.0 021 1 50 215 025 000 00 211 *10.0 041 01 224 10.5 024 02 200 150 100 0a 240 14.5 01a 04 241 -54.0 000 05 24s 4&5 045 00 250 4s.0 115 01 25a -4a0 052 0s 250 41.5 051 00 251 *40.0 ss5j 10 250 14.0 205 T0051 21.101 'rom 21.210

. 'Octane number estimated.

Rsum of fractionation A rportion of this charging stock is subjected c. c. to reforming in one run at a temperature of 1005 Light end discard -0 9,478 F. under 300 lbs. pressure and another portion is Above 68 octane number 23.103 subjected toreforming in a second run. at a Below 68 octane number 27,219 temperature of 1007 F. under 300 lbs. pressure. Bottoms. -2 4.700 to produce reformed gasoline products testing as follows: Total 64,500 Charged 64,070 Pmucc 01 Pguotof nl!! tu!! The cuts having octane numbers below 68 made up a composite charge for the reforming unit 714 ,0 5 having an A. P. I. gravity of 70.5, an octane 500 020 number of 45.5, and an Engler distillation test as E 5F follows: a 04 02 '1* 51 0; Initial 1m Isl 10% 166 101 iss 20% 114 3i 30% 180 21a 214 40% 104 240 50% 192 550 5:44 60% 200 '10% 208 Referring to the accompanying drawings: `80% y 218 Fig. 1 is a curve showing the octane values of 90% 42228 a typical gasoline stock which'has been highly 266 fractionated in accordance with the invention,

Fig. 2 is a flow diagram illustrating apparatus adapted for practicing the invention.

Fig. 3 is a ow diagram of a modied type of fractionating apparatus adapted for practicing the invention.

Fig. 1 illustrates results obtained by close fractionation under batch distillation with a reflux ratio of 37:1 of a '72 A. P.-I. gravity Mid-Continent light naphtha, which it was desired to use for the'production of an aviation gasoline. The temperatures taken at the top of the fractionating tower are plotted as ordinates and the mean volumes in proportions distilled off are plotted as `abscissa. An additional scale as ordinates is indicated for the octane values (Cooperative Fuel Research Motor method) of the several cuts or fractions. Curve A represents the top temperature of the fractionator and shows the temperatures at which the several fractions are distilled. Curve B presents marked irregularities and is in the nature of an irregular or discontinuous function with respect to the boiling points of the fract ons.

In practicing the invention' with the apparatus illustrated in Fig. 2, the gasoline or naphtha stock to betreated is contained in charging stock tank I0. The stock is a highly paraiiinic stock or gasoline stock of low anti-knock quality. The charging stock is drawn from the tank lli by pump |I and directed to a still I2 equipped with a fractionating tower I3. The still is heated. by suitable means (not shown) and reflux is supplied from a suitable source as by means ofthe pipe I4. The fractionating tower is designed to eect a highly eicient fractionation and accordingly is equipped with a large number of plates or the equivalent thereof such, for example, as 30 to 50 plates and the tower and still areV adapted for sustaining high reflux rates such as `-5021. 'Ihe vapors from the tower I3 arecondensed in condenser coil I5 having an, outlet I6 extending to a manifold I1 provided with branch lines, as |141, |1b, I1c, Hd, IIe. and I1f, extending to a desired number of receiving drums, as |8a, |81),-

respectively. During Vthe distillation as the temperature in the vapor line from the fractionating tower rises,vthe distillate passing through the--condenser Itnutlet I6 is diverted to the several tanks |3a, I 8b, etc., in

order to collect the particular fractions desired.

The distillate `receivers are provided with drawoi lines I 9a, |9b, |90, |9d, |9e and |9f, respecucts subjected to distillation in the still 28, the separated vapors being passed through condenser 29 and the resultant distillate collected in receiving tank 30. The distillation is preferably so conducted as to collect a gasoline or naphtha distillate in 30 which is passed to the reformed naphtha tank 3|. A line 3|a is provided for introducing additional stock, such 'as cracked gasoline into the tank 3 I.

The reformed gasoline ornaphtha stock which collects in tank 3|, or the mixture of reformed stock and cracked gasoline, is withdrawn by a pump 32 having a discharge line 33 maifolded with branches 33a, 33h and 33e. Branch line o 33a extends to fractionating apparatus consisting of a still 36 having a fractionating tower 35. Branch line 33h extends to treating apparatus for removing olens which is described hereinafter and branch line 33o extends to the stock tank I0.

The still 34 is provided with suitable heating means (not shown) and with means 36 for introducing reflux and is, like still I2 and fractionating tower I3, adapted for accomplishing a very high degree of fractionation of the gasoline or naphtha stock introduced thereto. The overhead vapors from lthe tower 35 pass through condenser coil 31 from which the distillate is withdrawn through the outlet 38. The outlet 38 is manifolded with branch lines as 38a, 38h, 38e, 38d, 38e and 381, which lead to a desired number of receivers, as 33a, 391)., 39e, 39d, 39e and 39j, respectively.

During the distillation as the temperature in the vapor line from the fractionating tower 35 etc. in order to collect the particular fractions desired. The distillate receiving drums are provided with drawoff lines 40a, 40h, 40e, 40d, 40e and' duf, respectively, leading to manifold line 4I and with branch lines, 40a', 40h', 40e', 40d', 40e', and 4Ilf', respectively, leading to another manifold line 42. The distillates of insufficiently high anti-knock value and which it may be desirable to subject 'to additional reforming are directed n through a manifold line 4| to a tank 43, and the tively. leading to a manifold line 20 and with leading to another manifold line 22. The distillates of insufliciently high anti-knock value and which it is desired to reform, are directed through manifold line 20 to the low anti-knock tank 2|. The distillates of suiliciently high antiknock value which it is not desired to subject to reformingare drawn through manifold line 22 into the high anti-knock tank 23.

Low anti-knock gasoline thus collected in tank 2|, to which may be added low anti-knock gasoline from an extraneous source charged into tank 2| through line 24, is drawn by pump 25 and passed to a reforming coil 2S which is provided with suitable heating means (not shown) for raising the gasoline constituents to temperatures upwards of 850 F. to effect reformation into constituents of increased anti-knockl value. The reforming operation is preferably carried on in a continuous manner. The hot products from the reforming coil 26 may be quenched with a cooling stock introduced through line 21 and the poddistillates of sufficiently high anti-knock value which may not require additional reforming, are drawn through manifold line 42 into a tank 44. The distillate collecting in tanky 43, which is of relatively low anti-knock value as compared with the distillate in tank 44, is subjected to further reforming and in accordance withl the invention, distillate may be withdrawn from tank `43 by A*pump 45 and directed to the reforming coil 26.

, uct tank 41 and distillate collected ,in tank 44 may be withdrawn by pump 48 and also directed into the product tank 41. Thus the high antiknock constituents segregated by the initial fractionating operation in still I2 and tower I3, may, in accordancel with the invention, be blended with the high anti-knock constituents of the reformed products which are segregated by means of the fractionation in the still 34 and tower 35 in the proportions desired to produce a final gasoline product of desired boiling range and high antiknock quality.

In some cases it is not necessary to subject the products of the reforming operation to the high degree of fractionation as is accomplished in tower 35 and a single gasoline distillate of desired boiling range may be recovered from the reformed products and may be blended with the high anti-knock constituents withdrawn from the tank 23 to form a gasoline product of desired boiling range and anti-knock quality. L

In a modification of the invention, reformed gasoline or naphtha stock collecting in the tank 3| may be withdrawn by means of a pump 32 and directed through the branch line 33e into the stock tank Il or passed directly to the fractionating still I2. In this method of operation thereformed gasoline or naphtha constituents are fractionated in the still I2 and tower I3 together with the naphtha charging stock, the fractions separated out from the composite stock which are of insuillciently high anti-knock value being collected in tank 2| and directed to the reforming coil 25 while the fractions of suillciently high anti-knock quality are directed into the tank 23 to constitute the desired gasoline product of Fig. 2. 'I'he continuous fractionating equipment thus illustrated includes a battery of continuous' column stills, as 50a, "b, llc. llld and 53e. The stills are provided with heating means tia, IIb, 5|c, lld and Cle, respectively, and with refluxing means 52a, 52h, 52e, 52d and 52e, respectively. Each of the towers "a, 50h, etc. is designed to effect a highly efficient fractionation and each is accordingly yequipped with a large number of plates or the equivalent thereof, such for example as -50 plates and each is adapted for sustaining high reflux rates such as 20-50z1. Condenser coils 53a, 53h, 63e, 53d and 53e and receiving drums 54a, 44h, 54e, 44d and 44e are line or naphtha stock which collects in tank 3|, y

or the mixed reformed stock and cracked gasoline in tank 3|, for the removal of oleiins, the stock is directed by pump 32 through branch line 33h into a mixer 49 for treatment with an agent adapted for selectively removing oleflnic constituents. Ak line is shown for admitting liquid sulphur dioxide into the mixer. 'I'he commingled liquid sulphur dioxide and hydrocarbons pass into a settling tank5l in which the ramnate is separated from the extract. The raflinate, comprising largely straight-chain parafiins as well as branched-chain parailins, is drawn off to a still 52 and subjected to distillation to distill of! any sulphur dioxide contained in the raiiinate and the hydrocarbon material thus freed of sulphur dioxide is directed into a tank 53. 'I'he extract in tank 5| is drawn off to a still 54 and subjected to distillation to remove the sulphur dioxide and the hydrocarbon material thus freed of sulphur dioxide and having a high concentration of olefinic constituents as well as aromatic and naphthenic constituents, is drawn oif to a l tank 55. 'I'he highly paraiiinic hydrocarbon material collecting in tank 53 is withdrawn by a pump 56, having a discharge line 51 with a branch line 51a leading to the still 34 and a branch line 51h leading to the still I2, and the material is subjected to fractionation in the still 34 and tower 35, or in the still I2 and tower I3, in the manner that has been previously described herein. The removal of olenic constituents prior to this frac.- tionation facilitates a better separation as b etween high and low anti-knock constituents.

The highly olefinic product collecting in tank 55 is withdrawn by a pump 58 and conducted through line 59 to the final product tank 41 for blending 'with the distillate from either or both of the tanks 23 and 44, or `the highly olefinic fractionating equipment adapted for continuousoperation, which may be employed in accordance with the invention in lieu of either or both' of the batch operations conducted in stills I 2 and 34 75 provided for the respective towers. Drawoff lines 55a,5b,55c,65dand5eextend, respectively, from the several receiving drums 54a, 34h, etc. to a manifold line 56. Branch lines 81a, C'Ib, llc, 41d and 61e extend respectively, from the several lines a, 85h, etc. to a manifold line 53. .y

In practicing the invention with the fractionating apparatus illustrated in Fig. 3, the stock to be fractionated, such as that withdrawn from the stock tank Il, or the reformed naphtha tank 3| or the ramnate tank 53 (shown in Fig. 2) is introduced by pump 59 to the fractionating tower 50a, being preferably introduced at an intermediate point of the tower. Liquid is withdrawn from tower 60a and directed by pump 'Ila to tower 50h; liquid is withdrawn from tower b and directed by pump 1lb to tower 50c; liquid is withdrawn from tower c and directed by pump 'Ilc to tower 60d; and liquid is withdrawn from tower 60d by pump 'Ilid and directed to tower 33e. I'iiquid from tower e is withdrawn through line e. The fractionating operation in the towers "a, 50h, etc. is carried on in a continuous manner with continuous charging to tower a by means of pump 63 and continuous passage of liquid to theother towers in succession. Constant temperature conditions are maintained in the several towers so as to take oi! from each tower the particular fraction desired and collect in the several receivers 54a, 54h, etc. distillates of desired boiling range. When usingthe continuous fractionating apparatus for the treatment of stock withdrawn from tank I0 the distillates collected in receivers 64a, 54D. etc., which are of insufficiently high anti-knock value, are directed through manifold line 65 to the low anti-knock tank 2| and to the reforming coil 25, and distillates of sufficiently high anti-knock value are directed through manifoldline 63 to the high anti-knock tank 23. When using the continuous operation for fractionating the products from the reformed naptha tank 3| .or from the raffinate tank 53, the distillates that are of insufciently high anti-knock value are directed through manifold line 86 to the reformed low anti-knock tank 43 for cycling to the reforming coil and the distillates of sumciently high antiknock' value are directed through manifold line 63 to the reformed high anti-knock tank 44.

In a specific 'example of the invention a stock such, for example, as the l2 A. P. I. gravity Mid- Continent light naphtha hereinbefore mentioned, is analyzed by close fractionation and shows the distillation and octane curves of Fig. 1 of the drawings. Thepeak and valleys in the octane curve indicate the several points at which the cuts should be made in the stock in order to segregate the high anti-knock fractions from the lowanti-knock fractions. In this particular stock it may be seen that the naphtha may in a practical operation be fractionated into six cuts ,which will serve to divide the stock into desiredhigh anti-knock and low anti-knock fractions. In employing the apparatus illustrated in Fig. 2,

the naphtha may be charged to still I2 and ve of the fractions taken o as overheadcuts being collected in receivers Isa, I8b, etc. while the still bottoms at the end of the run may constitute the sixth cut. An advantgeous operation is to include in the charging stock some heavier material which will serve as still bottoms` in the still I2 in which case all of the six cuts may be collected as overhead cuts.

Describing in detail the latter method f operation, the mixed stock is charged to the still I2 and heat is applied while supplying the necessary reflux. The temperature at the top of the tower is progressively raised during the run and the several cuts taken oi at the temperatures determined upon. The following tabulation shows the temperatures at which the several cuts are taken off the tower, with the tower under approximately atmospheric pressure, and gives the approximate volumes recovered, expressed as percentages of the naphtha charge (excluding the added heavier stock) and indicates the receiving drums in which the dierent fractions are collected:

Top temperature Cut Volume colgfted About 16% liquid recovcry'due to gas loss.

Cuts 1, 3 and 5, which represent the peaks of the octane curve, are directed into the high antiknock tank 23 and cuts 2, 4 and 6, which represent the valleys of the octane curve, are directed into the low octane tank 2|. The naphtha collected in tank 2l is directed to the reforming coil 26 andv subjected to reforming temperature and the reformed naphiha fractionated in still 34 orcycled back to the stock tank I0, as has been described hereinbefore.

In case it is desired to fractionate this naphtha stock in a continuous operation as by means of the apparatus in Fig. 3, the stock, preferably after being preheated, is introduced into the tower still 60a and the operation carried on as has been explained for this continuous apparatus. In making cuts similar to those made inthe batch operation, with the tower stills under approximately atmospheric pressure, the toptemperatures of the towers may be held as follows:

Tower Temperature In this way cuts 1, 2, 3, 4 and 5 are collected in receivers 64a, 64b, 64e, 64d and 65e respectively, and cut 6 is drawn oif through line lle. Cuts 1, 3 and 5 are directed into the high anti-knock tank 23 and cuts -2, 4 and 6 are directed into the low octane tank 2| for reforming.

tion'the thermal treatment may be aided with catalysts, such as oxides of the metals of the sixth group of the periodic system, activated carbon or mixtures of activated carbon and alloys of chromium and nickel or oxides ofthe metals of the sixth group of the periodic system, bauxite impregnated with oxides of zinc or nickel, silica gel impregnated with activated carbon, selenium, alloys of chromium, nickel and aluminum, or the improvement in anti-knock quality may be accomplished with an isomer-ization agent, such as aluminum chlorid.

While I have described a particular embodiment of my invention for the 'purposes of illustration, it should be understood that various modifie cations and adaptations thereof which will be obvious to one 'skilled in the art, may be made within the spirit of the invention as set forth in the appended claims.

f 1. In the manufacture ofy high anti-knock gasoline, the process that comprises primarily subjecting a gasoline stock to` fractionation to separate it into a plurality of fractions of different boiling points, collecting from said fractions those fractions having relatively lower anti-knock values, subjecting the fractions thus collected to reforming conditions to effect transformation into products of increased anti-knock value including olefinic constituents, treating resultant liquid products of the reforming to separate out liquid olefinic constituents, subjecting the lremaining products to fractionation to form a plurality of fractions of such narrow boiling ranges that each fraction possesses substantially only relatively high or low anti-knock values which, when plotted in relation to boiling points, exhibit an irregular or discontinuous curvilinear function, and collecting resultant fractions of higher antiknock values and blending the same with higher anti-knock value fractions separated out in the primary fractionation to form a composite gasoline of high anti-knock value.

2. In the manufacture of high anti-knock gasoline, the process that comprises primarily subjecting a gasoline stock to fractionation to separate it into a plurality of fractions of different l boiling points, collecting from said fractions those fractions having relatively lower anti-knock values, subjecting the fractions thus collected to reforming conditions to eect transformation into products of increased anti-knock value including olenicconstituents, treating resultant anti-knock value.

In carrying on the reforming step of my inven- 3. In the manufacture of high anti-knock gasoline, the process that comprises subjecting a gasoline stock to reforming in a reforming zone under conditions to effect transformation into products of increased anti-knock value including liquid oleflnic constituents, treating resultant products of the reforming to remove liquid olenic constituents therefrom, subjecting products remaining, 'after said removal of liquid olenic which, when plotted in relation to boiling points,

exhibit an irregular or discontinuous curvilinear function, separately collecting resultant fractions of relatively higher and lower anti-knock values and directing lower anti-knock fractions thus collected to the reforming' zone.

oline, the process that comprises subjecting a gasoline stock to reforming in a reforming zone underconditionsto effect transformation into products of increased anti-mock value including liquid olefinic constituents, treating resultant 10 4. In the manufacture of high anti-knock gasproducts of the reforming to remove liquid oleflnic constituents therefrom, subjecting products remaining, after said removal of liquid oleflnic constituents. to fractionation to form a plurality of gasoline fractions of such narrowl boiling' ranges that each fractionl l substantially only relatively high or low lanti-knock values which, when plotted in relation to boiling points. exhibit an irregular or discontinuous curvilinear function, separately collecting resultant fractions of relativelyrhigher and lower anti-knock values and subjecting lower anti-knock fractions thus collected to reforming conditions to effect transformation into products of increased anti-knock 15 value.

man F. nrwoxv.

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