US2056978A - Polymerization of hydrocarbon oils - Google Patents

Description

Oct. 13,` 1936. R. c. osTERsTRoM POLYMERZATION OF HYDROCARBON OILS Filed.ApIil 26, 1950 2 Sheets-Sheet 1 ,um mama: QU 4 m im@ wend@ v #S @NQS gwumtoo Rufio/plzv C 0s ersrom fr@ fm,

Oct'. 13, 1936.

R. c. osTERsTRoM POLYMERIZATION.OF HYDROCARBON OILS Filed pri1 2e, 1930 2 sheets-sheet 2 S2 e Sw R h qui@ Rudolph C. Oszerszrom aum/nui Patented Oct. 13, 1936 UNITED STATES 2,056,978 l PoLYMEmzATroN or maocAnBoN oms Rudolph C. Osterstrom, Chicago, Ill., assigner to The Pure Oil Company, Chicago, Ill., a corporation of Ohio Application April 26, 1930, Serial No. 447,532

Claims. (Cl. 19E-147) 'I'his invention relates to the art of removing gum-forming and color-imparting bodies from cracked petroleum distillates. Petroleum distillates obtained particularly from high tempera- 5 ture or vapor phase cracking systems, contain unsaturated compounds in the form of undesirable dioleines which, if permitted to remain in the distillates, promote or result in the formation of the gumand color compounds when the distillates lo are stored and exposed to either air or light. Such compounds are highly undesirable in motor fuels particularly and the removal thereof is necessary to permit the distillates to be used commercially. These gums likewise form in cracked distillates produced by other rening systems than the vapor phase system and the present invention is directed to the treatment of cracked petroleum distillates or other similar hydrocarbon oils to remove therefrom in an effective manner the objectionable hydrocarbons which produce resinous compounds through oxidation and which tend to impair the desired commercial color thereof. f I

For a further understanding of the invention reference is to be had to the following description and the accompanying drawings wherein:

Figure 1 discloses diagrammatically apparatus used in carrying the invention into operation, and

Figure 2 is a modification thereof.

Referring more particularly to the accompanying drawings, the numeral l designates a tank in which is contained the freshly cracked distillate which is to be treated in accordance with the present invention. This distillate consists ordi- 5 narily of hydrocarbon oils produced by crackingA processes and which have the boiling range of ordinary gasoline. These distillates, particularly distillates obtained by vapor phase cracking, contain highly reactive compounds in the form .of

diolefines or other similar types of unsaturated hydrocarbons which are readily attacked by air and light and form high boiling hydrocarbons of a resinous character which are ordinarily known as gums. These gums possess a highly complex molecular formation and are thought to be produced in cracked gasolines by the union of certain types of unsaturated compounds with oxygen. These gums or polymers, however, are readily recognized by their high boiling range which is considerably above that which the distillates possessed when originally produced or stored. This indicates that the gums are formed in stored cracked distillates and effective removal thereof is required to render such distillates suitable for use as motor fuels, since the presence of such gums or polymers in a motor fuel oil produce a highly objectionable condition in the commercial utilization of such oils in internal combustion engines. Itis thereforev to an effective and substantially complete removal of these objectionable 5 compounds from cracked distillates that the present invention is directed.

Leading from the tank l is a pipe line 2 which enters the suction side of a high pressure pump 3. A pipe 4 leads from the discharge side of the 10 pump 3 to a pipe still 5 in which is.located a coil 6. The pipe still comprises the usual wall structure in which is located a bridge 'l and one or more burners 8.- The oil or distillate to be treated is forced by the pump or pumps 3 through 15 the pipe line 4 to the coil 6 which is located within the still and is subjected to the relatively high temperatures therein prevailing. While in the coil 6 in a preferred method of operation the dis-` tillate under treatment is maintained under suo per-atmospheric pressures varying between 600 pounds and 1000 pounds per square inch and during the passage of the distillate through the coil 6 the temperature of the still is so Iregulated that 1 the distillate will attain a treating temperature 25 varying between 500 F. and 600 F. The rate of iow of the distillate through the coil 6 is subject to variation, depending upon the nature and degree of treatment required on the part of the distillates so handled. For example, a vapor 30 phase cracked distillate, which possesses a larger amount of objectionable unsaturated compounds than a liquid phase cracked distillate, is maintained in the polymerization zone, produced by the coil 6, for a greater period of time than said liquid phase cracked distillate which, as previously stated, does not require the same degree of treatment as the vapor phase product since it contains smaller percentages of the gum-forming compounds. Therefore, the oils or distillates so treated may be maintained in the polymerization zone for'periods of time varying between a few seconds-and fifteen or more minutes. In the polymerization zone the distillates are kept in the liquid phase, since the pressures utilized are 45 ordinarily more than suicient to overcome vaporization of the oils comprising said distillates at the temperature specified. By thus subjecting the distillates to the specified conditions of pressure, temperature and time, usually without the 50 employment of a catalyst, complete. and effective polymerization of the objectionablegum producing compounds takes place so that the oils will contain high boiling compounds which possess boiling points materially higher than the oils ordinarily introduced into the polymerizing zone by thev pump 3.

From the coil 6 the oils pass directly while in the liquid phaseand under pressure into a container 9 which contains in the base thereof a bed I0 of fullers earth or its equivalent. 'I'he `oils are forced through this bed of fullers earth for the purpose of removing therefrom compounds which possess an undesired color. In this manner the systemj provides for removing from the distillates or oils treated not only the gum-forming compounds but also those compounds which tend to discolor the same. During their passage through the fullers earth bed maintained in the container 9 the oils are held substantially in the liquid phase by the employment of super-atmospheric pressures.

After passing through the bed of fullers earth,

the oils leave the container 9 by way of the pipe line II and thence through an orifice meter or pressure reducing valve I2 which is situated immediately adjacent to a standard fractionating tower I3. By reason of the treatment above described there is formed in the oils as high boiling compounds the objectionable gums or color-producing substances. By ordinary careful fractionation in the tower I3, these high boiling compounds are collected in the bottom of said tower and removed by way of the valved outlet line I4. The desired oils of proper boiling range pass overhead as vapors from the tower I3 by way of the outlet line I5. These vaporized oils are condensed in the condenser I6 and are collected as finished motor fuel oils in the tank I'I. By removing the polymerized compounds from these oils the latter may be kept indefinitely under usual condi- 'tained from the tank I.

when xed gases produced by pyrogenesis fromtions of storage and handling without liability of any appreciable further gum formation therein. If desired, a valved gas inlet line I8 may be connected with the pipe line 2 for the purpose of introducing regulated quantities ci so-called fixed gas obtained from oil cracking systems into the polymerizing zone together with the distillates ob- It has been found that high boiling oils, are subjected to the conditions of temperature, pressure and time prevailing in the treating coil 6 such gases polymerize to form additive compounds of higher molecular weights and which may be subsequently recovered in high percentages as motor fuel distillate. 'I'his fixed or permanent gas may or may not be introduced into the system and does not effect the general operation above described.

I have found that substantially the full desired degumming effect is obtained by virtue of .the high pressures and `high temperatures employed with the proper time factor, and that While no material decolorization is obtainable in the coil 6, the clay bed I0, when disposed as specified, produces the desired decolorizing effect.

In the form of the invention disclosed in Figure 2, the polymer-containing vapors are passed from the polymerizing zone 6 of the still 5 directly into a fractionating tower I3a, pressure being relieved by means of the valve I2a. In the tower I3a the light vaporized oils of desired boiling point pass overhead by way of the line I5, the condenser I6 and into the storage tank I1. The oils which pass through the line I5 are of desired color and require no treatment for decolorization purposes. 'I'he polymerized oils of high boiling point are removed through the line I4. In the tower I3a, however, I remove near the bottom thereof, a con.- densate which, while possessing aboiling point ure 1, the decolorization of this cut is secured by means of the fullers earth bed I 0, but in the form of the invention shown in Figure 2, the oils are fractionally condensed to segregate fraction which contains the color producing compounds and hence it is that fraction particularly which requires special decolorizing treatment. If desired, this fraction could also be passed through a bed of fullers earth but I have found it advisable to use small quantities of sulphuric acid.`

This acid is withdrawn from the tank I9 and mixed with the condensate flowing through the line I8, a complete mixing of the acid with the oils taking place in the continuous treater tanks 20. The acid is finally neutralized with caustic and the decolorized oils are transmitted to a storage tank 2 I.

It will be noted that in the operation of the tower 9 the oils under treatment are in the liquid phase, and these oils exercise a solvent action on the gums or polymers which adhere to the fullers earth particles contained in the bed I0, thus washing the polymers from the fullers earth and providing for sustained use of the earth without replenishment or substitution.

'Ihe system has the advantage of being far more economical than other polymerization systems heretofore employed for this purpose. This is accomplished by the use of but a limited consumption of clay and the manner of handling of the polymers. Gum polymerization takes place in the coil 6 without the aid of a catalyst such as fullers earth and the only fullers earth utilized is that which is contained in the bed I0, and this is subject to a slow rate of deterioration for the reason that the principal reactions are effective in the tube still without the aid of clay. Moreover, the fractionation step provided by the tower I3 provides for the eifective removal oi' the treated gasoline fraction from the polymerized compounds, permitting such latter undesirable compounds to be withdrawn from the bottom of the tower free from gasoline fractions, hence re-running of the polymer fraction is eliminated. Further, the system has the advantage of operating without mechanical difficulties which occur when fullers earth is forced with the oils to be treated through a tube still. In such van operation the fullers earth tends to produce erosion oi' the metal parts with which it contacts sharply with the result that there is considerable replacement of worn parts in such systemsand which will not be present in the apparatus above described.

What is claimed is:

1. The method of removing gum-forming and der pressures varying between 600 pounds and.

1000 pounds per square inch to prevent the vaporization of said oils while the latter are in said heating zone, removing the oils from the heating zone after a desired period o! retention therein and passing said oils while in the liquid phase into deolorizing contact with fullers earth, relieving the pressure on the oils following contact .rith the fullers earth to permit of the substantial vaporization of the oils, and tractionating the vaporized oils to remove therefrom the objectionable high boiling polymerized compounds.

2. The lmethod of polymerizing hydrocarbon products obtained from cracking operations, which comprises heating a mixture consisting of a cracked motor fuel distillate and xed hydrocargon gas to a temperature varying between 500 F. and 600 F. while said mixture is maintained under super-atmospheric pressures varying between 600 pounds and 1,000 pounds per square inch, then removing the mixture from said zone after a desired period of retention therein and passing said mixture in a substantially liquid state through a bed of fullers earth, removing the pressure on said mixture to reduce the latter to a substantially vaporous state, and then fractionating the vaporized oils to remove therefrom the undesired high boiling polymerized compounds.

3. The method of accelerating the polymerizing of gum-forming and color-imparting bodies in low-boiling cracked petroleum oils, which comprises continually passing such oils admixed with xed gas in an elongated stream of restricted cross-sectional area through a heating zone wherein said oils and gases are heated to a temperature of the order of approximately 600 F., maintaining the oils and gases while passing through said zone under pressures varying between 600 pounds and 1000 pounds per square inch, maintaining the oils and gases in said heating zone for a sullicient period of time to eiect the desired polymerization thereof, removing the heated products from said heating zone and, without releasing pressure, bringing the same into direct contact with a decolorlzing adsorbent earth, relieving the pressure on said products following contact with the decoll orizing material, and fractionating said products to separate the same into high boilingand low boiling compounds.

4. The method of removing gum-forming and color-imparting bodies from cracked gasolinecontaining distillate which comprises heating such a distillate in the absence of catalysts and of added hydrogen to a temperature considerably in excess of the normal vaporizing temperature but below a temperature sufliciently high to recrack such distillate, while maintaining said distillate under pressures varying between 600 and 1000 pounds per square inch, removing the distillate from the heating zone after the desired period of retention therein and, without substantial pressure reduction and while the distillate is essentially in the liquid phase, passing said distillate before separation of vapors through a bed of decolorizing adsorbent earth, relieving the pressure on the distillate following contact with said adsorbent to reduce the distillate to a substantially vaporous state, fractionating the vaporized distillate to remove therefrom the undesired high-boiling polymerized compounds, and condensing and recovering the treated distillate.

5. 'Ihe method of removing gum-forming and color imparting bodies from cracked gasolinecontaining distillate which comprises heating such a distillate in the absence of catalysts and of added hydrogen to a temperature in excess of 500 F. but below a temperature suiciently high to recrack such distillate, while maintaining said distillate under pressures varying between 600 and 1000 pounds per square inch, removing the distillate from the heating zone after the desired period of retention therein and, without substantial pressure reduction and While the distillate is essentially in the liquid phase, passing said distillate before separation of vaporsl through a bed of decolorizing adsorbent earth, relieving the pressure on the distillate following contant with said adsorbent to reduce the dis- -tillate to a substantially vaporous state, frac- 'RUDOLPH C. OSTERSTROM.

Images