US2107714A - Apparatus for refining mineral oils - Google Patents

Description

Feb. 8,'1938. H R, ROWLAND ET ALl 2,107,714

APPARATUS FOR REFINING MINERAL OILS Original Filed Deo. 10, 1928 l2 Sheets-Sheet 1 Feb 8, 1938. H. R. RowLAND ET A1.

APPARATUS FOR REFINING MINERAL OILS Original Filed Deo. lO, 1928 2 Sheets-Sheet 2 fn M0175 ro' Pou/Quad;

Srlmwgs Patented Feb.`8, 1938 UNITED STATES' APPARATUS Fon nEFmING MINERAL oms Herbert R. Rowland, deceased, late of Kansas City, Mo., by Mary U. Rowland, administratrix, Basking Ridge, N. J., and Eugene Jerome Smith, Ponca City, Okla.; said Herbert R. Rowland and Eugene Jerome Smith, assignors to Corona Conversion Corporation, Kansas City, Mo., a

corporation of Arizona Original application December 10, 1928, Serial No. 324,923. Divided and this application .lune 27,

1935, Serial No. 28,758

1o claims'.

'Ihis invention relates to apparatus for refining mineral oils; and in particular it has to do with apparatus adapted for use in treating mineral oils of various kinds in order to purify and stabilize 5 the same. The apparatus of the invention is disclosed in prior copending application Serial No.

J324,923, filed December l0, 1928, of which` the present application is a division. The apparatus is especially` useful in connection with the treatment of oil products of widely varying characteristics, including oils of the motor fuel type, such as gasoline, especially gasoline derived from cracking processes, and also kerosenes, lubricating oils, and other oil products. In the description hereinafter, however,reference will be made more particularly to use of the apparatus in treating crude motor fuels or motor fuel distillates of the gasoline type, since at the present time this is considered the most important field of application of the invention.

Crude motor fuels of the gasoline type, especially crude gasolines derived from cracking processes, commonly contain a substantial proportion of gums or gum-forming constituents of unsaturated character, such as certain diolens,

which are highly objectionable for various reasons. lThese crude motor fuel distillates also often contain substantial quantities of other iml purities,notably sulphur, the proportions of which varyvconsiderably depending upon the source of K the crude oil from which the distillates are de-fl rived. l The sulphur is largely present in the form of more or less complex combinations with the hydrocarbons. of ,the gasoline, and its presence .35 causespoor color, disagreeable odor, and other' y objectionable characteristics. Its removal from gasoline, together with the removal of gum-form- "ingl constituents, constitutes, one of the Amost troublesome problems ofthe rener. Such imopurities 'must nevertheless be eliminated or re- Aduced below certain specied maximum limits in lorder to comply with standard speciilcations for A the finished product.

The refining methods heretofore customarily 45 employed have been the well known Aacid treatment, principally for elimination of undesirable gum-forming unsaturates, and treatment with alkaline reagents, such as sodium plumbite (doc torl solution), for removal of sulphur. These so methods are complicated, laborious, and very expensive. The usual acid treatment with concentrated sulphuric acid lis very drastic and results in removing from the oil a 'large proportion of desirableunsaturates in addition to those whichvare 55 harmfuhso that the refining losses in this treatment are excessive especially when employing it for refining cracked motor fuel distillates,

s One of the principal objects of the present invention is to provide apparatus that will enable mineral oil products generally, and particularly crude motor fuels such as cracked distillates, to be refined in a comparatively simple and economical manner to meet the standard specifications for the respective finished products. Although useful employment of the novel apparatus is not to be understood as confined to practice of the oil-refining process disclosed in saidA prior application Serial No. 324,923, or of any other specified process, the use of the apparatus in carrying out the process of said prior application willbe described by way of illustrative example as an aid to gaining an understanding of the underlying principles involved in the apparatus and its mode of operation in a typical instance. lIn general, the process of said prior application primarily involves subjecting the oil' to be refined, to a systematic and thorough-,going treatment with chlorine, but in vsuch manner as to el'e'c't the desired elimination of impurities or objectionable constituents without' such drastic actionjupon the ollja'sa'l Whole that it is fundamentallyjaltered or its general 'identifying characteristics'are estro'yedj; ils-oto say, theoil undergoing 4eat-- mentjis vnotFc'ox'iverted into an 'entirelylijfierent class of oduct but merely becomes a morehiglfily frenedproduct'plof the samegeneral class.. '-'lhe. chlorine, ofrwhich only a relatively very small-f'prof-v portion-isemployedis most@ desirablyintroduced 4. -intothefoil' as freev chlorine; but the '.inv'ertionis not limited in this respect, and' a' is feasible (to employ instead a compound.-yieldingchlorine in f 1 available form under proper operating'l'cnditions.

. The chlorine acts upon the,l in the -oil in `a manner not entirely` understood., There are some indications that it acts to some extent bothy as anl oxidizingagent anda polymerizing agent,

l perhaps catalytically. But whatevergmay bethe precise nature of this action, the practical result is that if the chlorine is employed under proper conditions, there results a very large reduction in the sulphur content of the oil. Furthermore there results also an Vaction of somev kind upon the gum-forming constituents such-that upon subsequent distillation of the oil undergoing treatl`merit itis possible to reduce the content of these to within the tolerance limit if certain conditions to be referred to presently are observed in carrying out the distillation.

An important feature of the chlorine tneatment consists in allowing a relatively long period uentscarried by sai`d vapors.

tion of chlorine into the oil to be refined. A digestion period of at least twelve hours is desirably allowed after introduction of the chlorine intov the oil, and a period of twenty-four hours is still better and is to be generally recommended in practice. If the oil stands quietly during this digestion period, there results considerable settlement of what appear to be complex sulphurchlorine-hydrocarbon compounds which can be drawn oif as a sludge from the settling tank.

This chlorine digestion treatment, although relatively mild, accomplishes a very substantial reduction in the sulphur content of a. crude motor fuel distillate or other oil product to which it is applied. In and of itself, however, it does notbring about at this stage -a sumciently extensive removal of gum-forming constituents by precipitation and settlement. A materially better result in this respect canbe obtained by a light (or incomplete) acid treatment of the oil to be refined, preceding the chlorine digestion. By incomplete treatment is here meant that materially less acid is used than would be required in the customary acid' refining process. The combination of the two treatments is found to be very effective in greatly reducing both the gum content andthe sulphur content. This preliminary light acid treatment involves not merely the usual refining action characteristic of acid treatment, but it appears also to so modify the oil that the succeeding steps of treating the oil with chlorine and then distilling are both rendered more effective than they otherwise would be in removing undesirable constituents. Accordingly, although the preliminary acid treatment is not indispensable in the broader aspects of the invention, it is regarded as highly advantag'eous in many cases, especially where the oil to be refined is high in contaminating impurities. Furthermore, the preliminary treatment with a relatively small quantity of strong Ysulphuric acid aids in eliminating' moisture that may be present in the crude distillate, and it is of great advantage to avoid the presence of moisture as far as possible. But it is feasible in some cases even to defer the light acid treatment until after the chlorine digestion.

After the chlorine digestion, eitherI with or without the preliminary light acid treatment, the partially refined oil is most desirably separated from the sludge or settlings and is run into a still. yThe charge is now distilled off, and the distillation vapors are vcaused to pass through a permeable mass of contact material having the power to arrest and remove, probably by a polymerizing action, gums or gum-forming constit- Zinc in granular or fragmentary form has been found to act most effectively .in this capacity but other metals including cadmium, lead, aluminum, tin and iron, for example, act to some extent in a similar way although` some of these metals act far less effectively. Alloys of two or more of these metals are also useful, notably alloys of zinc with cadmium and lead. In addition to passing the distillation vapors through contact material, it is highly desirable that the liquid oil inl the still .also be subjected to the action of such contact material. Therefore, in the best mode of practicing the invention provision is made for this. The action of the contact 'materiaL .both upon the liquid oil in the still and upon the oil vapors, is of vital importance. Besides assisting in removal of sulphur and gums, it appears also to aid in eliminating from the oil such chlorine as may have combined with some of the oil hydrocarbons, and in this sense to exercise a dechlorinating function. It is not intended to imply, however, that there is necessarily any chemical combination formed by the vmetal or other contact material with chlorine in the present process. In fact, there is some available evidence to the contrary and it is therefore believed that the action of the contact material in assisting in removal of chlorine from the oil, or in so acting upon it as to render easy its removal in a subsequent step, is more that of a catalyst. But whatever the true explanation may be regarding the function of the contact material in favoring removalof the several impurities referred to, the employment of such material, more particularly metallic zinc, in connection with the distillation which follows the chlorine digestion treatment has been found very important in obtaining best results in practic- Y' l ing the new process. Y

In conjunction-with this polymerizing treatment, the vapors are most desirably subjected to fractionation or rectification, the two operations going on together continuously as a combined treatment of greater efficiency.4 This procedure, which will be described in greater detail hereinafter, is believed to be broadly new in oil refining, especially in refining cracked motor fuel distillates, irrespective of whether or not the oil has received special treatment with chlorine or other reagent before distillation.

The distillation vapors after receiving the combined polymerizing and fractionating treatment, are led to a condenser and the resultant motor fuel condensate is then given an alkaline Wash by which remaining traces of chlorine are removed, giving a finished product of good color and stability and otherwise meeting the usual requirements for marketability. In some cases filtration of the condensate through fuller's earth is desirable in order to improve the color but this is frequently unnecessary.

, In order to further explain the principles underlying the invention, a specific example of its application in the refining. of a cracked motor fuel distillate will now be given. In the accompanying drawings, which illustrate a practical embodiment of the invention,

Fig. 1 is a general view in side elevation, partly broken away and in section, of a distillate plant embodying features of the invention;

Fig. 2 is a transverse section of thestillon the line 2-2 of Fig. l; and

Fig. 3 is a vertical section of the combined tower'and fractionating column inpart, on a larger scale. v

In this specific example, it is assumed that the oil to be refined is a cracked motor fuel distillate obtained from'a crude oil characterized by very high sulphur content. This distillate contains, say, 0.5% of sulphur and a large percentage of unsaturates including a substantial proportion of gum-forming constituents 'such as dioleflns. The refining methods formerly considered necessary to use in handling this type of disumana included, first, an acid treatment at the 'rate of 10 pounds of concentrated 'sulphuric acid per barrel of 42 gallons, then treatment with doctor solution, then steam distillation, and finally another treatment with doctor solution. Such treatment is so complicated and expensive,

both as to procedure and reni'ng losses, as hard- 7;

' treated gasoline is then allowed to stand quietly in the treating tank for about 24 hours, during which time a sludge settles out which is characterized by a substantial content of sulphur and chlorine, evidently largely combined with hydrocarbons. This sludge is separated from the clear liquid in any suitable manner.

'I'he apparatus employed -up to this stage is of such simple and usual character as to require no illustration here.

The treated gasoline separated from the sludge is now run into the still I in the lower part of which are vertically -arranged a number of metal plates II, zinc plates in this instance. As here shown, these plates are provided on opposite vertical edges with lugs I2 by which the plates are carried on vsupporting bars I3 extending longitudinally within the still. For convenience in inserting or removing the zinc plates I I, an opening I4 having a suitable closure I5 is provided at one end of the still, and `by inserting appropriate lifting means through the apertured lugs I6 with which the zinc plates are provided at their upper ends, these plates can be readily lifted and removed from the opening and replaced by others whenever necessary.

The charge of treated crude gasoline in the still is distilled oil in the usual manner, leaving a residue containing some gums and sulphur. The distillation vapors pass oiT through the vapor line I1 into the base of. a combined tower and fractionating column I8, the detailed construction oi' which is best shown in Fig. 3. As will be seen, this combined tower and column comprises two diiierent types of sections, namely, liquid-vapor contact or fractionating sections A, and other sections B which may conveniently be termed dephlegmating sections. The fractionating sections A may take any of the various forms commonly employed in fractionating or rectifying columns. In this instance they are so-called bubbler-cap sections, each comprising a plate I9 carrying a. plurality o1' bubbler-cap devices having vapor up-tlow tubes and cooperating inverted cups or bells 2l, all of well-known construction and arrangement. The dephlegmating sections are, iny general, sections containing permeable contact material through which the vapors are compelledto pass. In the present example they take the form of hopper-shaped plates 22 each carrying a mass 23 of granulated zinc, and provided with central vapor upilow tube 24 and cooperatingl inverted bell or cup 25 whose lower edges depend into the mass of granulated zinc. -Suitably covered hand-holes 26 permit easy access to the contact material y when replacement or adjustment isnecessary.

It will be noted that in the lower part of. this combined tower and fractionating column the two types of sections are disposed in alternating arrangement which is particularly advantageous as will presently appear. In the upper part of the column only the bubble sections are em-` ployed.

The distillation vapors entering the base of the combined tower and column pass upwardly through the devices 20, 2I of the rst bubblercap section and in so doing travel through the liquid on that plate, the level of this liquid being determined by the height of the intake end of the liquid downow pipe or run-back 21. The vapors pass thence through the vapor upow pipe 24 of the first dephlegmating section and are compelled by the inverted bell to travel throughthe vmass of contact material, granulated zinc in this case, in said section. Thence the vapors pass upwardly through the bubbler devices of the second bubblersection and through the liquid standing thereon, the depth of which is determined by the height of the overflow or run-back pipe 28 which carries the overflow from this plate down to the first bubbler plate through the intervening section B, a kind of stuiiing box device 29, 30, being provided where the run-back passes through the plate 22 and the contact material carried thereby, such that any vapors tending to pass upwardly through the plate 22 at this point rather thanthrough the central vapor pipe will likewise be compelled to pass through the granulated zinc carried by the plate.

'Ihe upward travel of the vapors through the remainder of. the combined tower and fractionating column is similar to that already described, exceptthat in the upper part of the column the vapors pass only through bubbler-cap sections, it being ordinarily unnecessary to provide dephlegmator sections in alternation with the bubbler-cap sections throughout the entire height of the tower-column structure.

In the top oi the tower-column structure is provided a temperature-control section 3i in which is disposed a cooling coil 32 through which cooling water may be passed in greater or less quantity according to the degree of cooling desired. The vaporspass through this'cooling coil bubbler plate to bubbler plate in the manner customarily characterizing a fractionating column, removing at each plate some of the higher-boiling constituents of the upwardly flowing vapors,

and being itself relieved of relatively low-boiling constituents by the heat of said vapors which, of course, become cooler as they ascend through the successive sections. Relatively high-boiling constituents of the vapors are discharged as liquid from the lowest bubbler-cap section through overilow or runback 21 and are reuxed through I1 to the still I0.

In passing through the several bodies of vper-- meable rcontact or catalytic material carried by the'plates 22, the oil vapors are relieved almost entirely'of their gum-forming constituents, owing apparently to a polymerizing reaction favored by the contact material; and in the bubbler-cap section through which the vapors pass upon leaving each dephlegmating section, the vapors are thoroughly washed and in this way made to drop gummy polymers which may have been condensed in thedephlegmating sections but mechanically carried over by the vapors. This action is in addition to the normal fractionating cr rectifying action 'i' the bubbler-cap section.

'I'he gummy polymers removed in the dephlegmating sections remain in liquid condition at the temperatures prevailing in the lower part of the 75 are merely illustrative or good practice, and that tower-column, draining down through the catalytic material into the annular trough or launder 34 surrounding the central vapor pipe and thence flowing through trapped line 35 into header 36, which carries them either to a suitable collecting tank (not shown), or, byv way of connection Illa, ba'ck into still I0 for re-distillation. There is also shown tar line lb leading as a discharge from the lower part of still l0. Screen 3l serves to prevent the granular contact material from dropping down into the trough or launder 34.

Returning now to the vapors leavingthe top of the tower-column, these are conducted by vapor line 33 to a condenser 3B from which liquid condensate passes through look-box 33 and line 4B to a suitable receiving tank (not shown), while xed gases are vented through pipe 4i. This condensate is now given a thorough washing with an alkaline agent in order to remove any remaining chlorine. For this purpose a saturated water solution of sodium carbonate is efective and is to be recommended, but other suitable 4alkaline washes may be used.

The refined gasoline thus obtained is of excellent quality and meets all the requirements of standard motor fuel specifications. Notv only is a. nished product of good color and stability obtained by the foregoing procedure, but equally important is the fact that such color is stabilized, there being no appreciable change in the color of products produced by this process even after prolonged or unusual exposure to light. Considering the high sulphur and gum content of the crude motor fuel distillate to which the process was applied in the speciiic example hereinabove.

given, this is obviously a remarkable achievement and indicates the great eiiectiveness of the treatment. In general, the described process and apparatus are particularly well adapted to treatment of crude motor fuel distiilates and other,y oil products which are refinable with only the greatest dimculty, if at all, by prior methods to a finished product meeting standard specications; but they are of course aso applicable to reilning of oil products generally. The quantity of chlorine necessary to use in a given instance depends, of course, upon the particular distillate -or other oil product to be refined, but it seldom exceeds 2 pounds per barrel and commonly is much less.

Instead of employing granulated zinc in the tower-column, mos'sy zinc may be used to good advantage. Also, trays of mossy or granulatedthe vapors leaving the bubbler devices to pass through such contact material on their wayto the next section above. o

The herein described process and apparatus -are applicable not only to the rening of mineral oils such as crude motor fuel distillates and similar petroleum products. but also to other hydrocarbon materials, such as benzol and toluol, for

example, containing sulphur or other impurity which it is desired to remove.

- It is to be understood that the speciiic details hereinabove given with respect to fthe invention the invention is inl no sense restricted thereto. Thus, it is feasible to use a material such as fullcrs earth, for example, in some or all of the dearoavm. i

phlegmating sections of the tower-column in place of or in conjunction with the metallic contact material referred to in the specific `example given, and the invention in its broader aspects comprehends such use; but the use of a metallic 4contact material, especially zinc, oifers important advantages.

What is claimed is:

1. In an apparatus of the character described, a shell, a partition dividing said shell into two compartments, a passage connecting said compartments, means in one compartment for supporting solid adsorptive material for free drainage, a vapor inlet for said last mentioned compartment, a fractionating column contained within said other compartment, and a vapor outlet from said last compartment.

2. In an apparatus of the character described,

a shell, a partition dividing said shell into two compartments, a passage connecting said compartments, means in one compartment for supporting solid adsorptive material for free drainage, a vapor inlet for said last mentionedcompartment, a fractionating column contained within said other compartment, a vapor outlet from said last compartment, .and means for draining liquid from said compartments.

3. In anapparatus of the character described,

a shell, a partition dividing said shell into two compartments, a passage connecting said com-A partments, means in one of-said compartments for supporting solid adsorptive material for free drainage, a vapor inlet for said compartment, a`

fractionating column contained within the other compartment, a vapor outlet vfrom said last compartment, and means for supplying reux liquid to the upper portion of said fractionating column. 4. In combination, an upright shell, a horizontal partition div ding said shell into upper and lower ompartmen means in one compartment for supporting scflid adsorptive material for free drainage, a vapor inlet for said compartment, a fractionating/ column contained within the other compartment, a passage leading from said irst compartment to the 'lower portion of the second compartment, and a vapor outlet from said second compartment. l

5. In combination, an upright shell, a horizontal partition dividing said shell into upper and lower compartments, means in one compartment for supporting solid adsorptive material for free drainage, a vapor inlet for said compartment, a fractionating column contained within the other compartment, a passage leading from said iirst compartment to the lower portion of the second compartment, a vapor outlet from said. second compartment, and means for supplying reflux liquid to the -upper portion of said second compartment. n

6. In .an apparatus of the character described, an upright shell, a horizontal partition dividing vsaid shell into upperand lowercompartments, means within one of said compartments for supporting solid adsorptive material therein for free drainage, a vaporinlet for said compartment, bubble trays contained within the other compartment, a vapor passage connecting said 'ilrst compartment with/the lower portion of said sec-- ond compartment, a vapor outlet from said second compartment, and means for supplying reflux liquid to the upper portion of said second compartment.

7. In an apparatus of the character described, an upright shell, a horizontal partition dividing said shell into upper and lwerl compartments,

means within one of said compartments for supi porting solid adsorptive material therein for free drainage, a vapor inlet for said compartment, b ubble trays contained within the other compartment, a vapor passage connecting said first compartment with the lower portion of said secondA compartment, a vapor outlet from said second compartment, means for supplying reiiux liquid to the upper portion of said second compartment, and means for draining liquid from said compartments.

` 8. In an apparatus of the character described, an upright shell, a partition dividing said shell intoupper and lower compartments, means in one of said compartments for supporting solid adsorptive material for free drainage, means for passing vapors upwardly through a body of solid adsorptive material supported by said means, a

fractionating column insaid second compartment, a passage leading from saidrst to said second compartment, and a vapor outlet from said second compartment.

9. In an apparatus of the character described, an upright shell, a horizontal partition dividing said shell into upper and lower compartments,

means within the lower compartment for supporting a body of solid adsorptive material for free drainage, a fractionating column contained Within the upper compartment, a passage leading from the lower compartment tothe lower portion of the upper compartment, a vapor inlet for said lower compartment, and a vapor outlet for said upper compartment.

10. In an apparatus of the character described, an upright shell, a partition dividing said shell into upper and lower compartments, means in one of .said compartments for supporting solid adsorptive material for free drainage, means for passing vapors upwardly through such body of such solid adsorptiveV material, a fractionating column in said second compartment, a passage leading from the upper portion of said irst compartment to the lower portion of said second compartment, and a vapor outlet from said second compartment. v

MARY U. ROWLAND, Administratria: of the Estate of Herbert R. Rowland, Deceased.

EUGENE JEROME SMITH.

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