US2009879A - Process of treating cracked hydrocarbon vapors - Google Patents

Description

July 30, 1935. G. EGLOFF 2,009,879

PROCESS OF TREATING CRACKED HYDROCARBON VAPORS Filed March 22, 1930 /4 A9 0 y 6 /Z 7 HTTOR/V J Patented July 3Q W35 UNETE srr s aware arr FFEQE PEEQCESS (PF TREATHNG CRAQKIED HYDRCARBN VURS tion of South Dakota Application March 22, 1930, Serial No. 437,975

' 6 Claims. (Cl. 196-36) This invention relates to a process of treating cracked hydrocarbon vapors and pertains in its specific embodiment to the treatment of cracked hydrocarbon vapors, subjecting them to the action of zinc chloride preferably in aqueous solution and preferably with the use of activated or atomic hydrogen for the purpose of producing stable, water-white, sweet motor fuel having low sulphur and gum content.

It is among the objects of my invention. to bring about the desulphurization of the cracked hydrocarbon product so that subsequent refining for sulphur reduction and sweetening, together with the expense and losses involved, are re- 31 duced to a minimum or are entirely eliminated.

Desulphurization of the product causes a reduction or minimizing of corrosion in the plant equipment and in the automotive equipment where the motor fuel is consumed.

Frequently when finished gasolines are stored, especially cracked gasolines, chemical changes occur which affect the color, gum content and anti-knock properties. These properties are affected particularly by light and the oxygen of the air which promote the undesirable reactions which bring about the above changes. Although the chemistry of these changes is not thoroughly understood, it is evident that the presence of.

certain highly reactive hydrocarbons, for example, those related to diolefine's, terpenes, etc., are involved in the undesired reactions. It is one of the chief objects of my invention to hydrogenate these unsaturated hydrocarbons, converting them to stable motor fuel hydrocarbons and avoiding a decreased yield of the motor fuel product. It is not thepurpose in carrying out the process of the invention to completely saturate all the unsaturated hydrocarbons present in the cracked low boiling product for olefine lay- 40 drocarbons in general are very stable and possess good anti-knock properties. The purpose is rather to add hydrogen in regulated amounts to the highly unsaturated hydrocarbons referred to above for the purpose of improving the antiknock properties of motor fuel hydrocarbons 45 present in the cracked product, reducing and min imizing subsequent refining such as sulphuric.

acid treatment, and the stabilization of the final .motor fuel product.

The practice of my invention in addition to producing a hydrocarbonproduct of good color and low gum content brings about the stabilization of this product so that it will not readilygo off color. The formation of color in gaso- 55 lines is not only undesirable from a marketing viewpoint (a colorless gasoline can be more readily dispensed than a yellowish gasoline when using visible bowls), but is usually also an index of the formation of gum-like, polymerized material which affects the operation of the motor as is evidenced by the clogging of feed lines, in-' terference with the proper operation of the carburetor and the sticking of the valves in the motor.

The anti-knock property of a motor fuel is one of its most important and valuable characteristics. The higher the anti-knock value or knock rating of a motor fuel, the greater is its efficiency. A change in this value during storage is, therefore, a disturbing factor since a desirable motor fuel may change to such an extent that it will require some form of treatment to restore it to its original market value. The addition of anti-knock materials, the use of inhibiting agents, blending with exceptionally high anti-knock motor fuel stocks, or repetition of previous treatment are methods used to prevent reduction of anti-knock value of motor fuel oil in storage or to restore the antiknock value if it has fallen off. The use of my process minimizes or eliminates the use of these preventative and restoration methods and eliminates all of the uncertainties involved.

In the practice of my invention, I use zinc chloride to promote in part the results that I have referred to above. Although I may use the zinc chloride in solid form or may distribute the zinc chloride on a distributing agency so as to allow a large reaction surface, I preferably use an aqueous solution which may be maintained at any given strength during the process by addition of this salt or by the addition of water. The zinc chloride solution reacts with the deleterious colorforming substances, including some of the sulride. Activated hydrogen may be used as such or in the form of activated hydrogen-containing gases such as coal gas, oil gas, water gas, producer gas, natural gaacracked gas, etc. The activated hydrogen or hydrogen-containing gases are preferably introduced into the zinc chloride solution and together with the zinc chloride solution brings about the results above enumerated.

In carrying out the process of my invention, I do not wish to limit myself to the apparatus in which it is used since the invention can very well be carried out as a step within the cracking process comprising heating and reaction zones with provisions for returning partially converted products for retreatment, together with condensing, cooling and collecting means as well as in separate equipment which would involve vaporizing, processing, condensing, cooling and collecting means. Preferably, however, the process is carried out as a step in the cracking process, treating the cracked hydrocarbon vapors after leaving the dcphlegmator, as will be hereinafter described.

The accompanying drawing, given only for the purpose of more clearly illustrating my invention, is a diagrammatic view, not drawn to scale, of one of the forms of apparatus in which my invention may be practiced.

Referring to the drawing, cracked vapors, preferably coming directly from the dephlegmator of a cracking plant, may be introduced through line I and valve 2 into treater tank 3.

A solution of zinc chloride in water may be supplied through line 4 and valve 5 to pump 6 and thence fed into the treater tank 3 through line I, valve 3 and line I. Additional water may also be fed into tank 3 and is supplied, in this case, through line l0 and valve II to pump I2 which feeds it through line l3 and valve l4 into tank 3. A solution of zinc chloride in water may be maintained within tank 3, the level of the solution in the tank being maintained fairly constant. This liquid level may be indicated in a gauge glass 9 attached to the tank. The introduction of zinc chloride and water into tank 3 may be continuous or intermittent and may be in such proportions that the strength of the solution within tank 3 is maintained substantially uniform.

The cracked vapors are intimately contacted with the solution of zinc chloride in tank 3. being introduced below the liquid level within the tank and bubbling up through the solution to the vapor space above the liquid.

Activated or atomic hydrogen may also be introduced into the zinc chloride solution in tank 3. The hydrogen is, in this case, supplied through line l5 and valve IE to pump I? and fed therefrom into tank 3 through line 18 and valve Hi. The introduction of activated or atomic hydrogen may be simultaneous with the introduction of cracked vapors.

That portion of the cracked vapors which is condensed in tank 3 may be collected upon the surface of the aqueous solution of zinc chloride therein and may be withdrawn through line 20 and valve 2| to tower 22 which may be any suitable form of flash distilling and fractionating device such as a tower containing perforated pans, packing, bubble trays or the like.

Tower 22 is preferably maintained under a lower pressure than that employed in treating tank'3, and the latent heat liberated by the reduction in the pressure imposed upon the liquid may serve to vaporize substantially all of this liquid introduced into tower 22. That portion of the liquid introduced into tower 22 which remains unvaporized, together with condensate from vapors which are condensed in tower 22, may be removed through line 23 controlled by valve 24.

Vapors from tower 22 may pass through line 25 and valve 26 into line 21. Vapors from treater tank 3 may also pass through line 21 and valve 23 and, together with the vapors introduced into line 21 from tower 22, may pass through valve 23 to be subjected to condensation and cooling in condenser 30, thereafter passing through line 3| and valve 32 into receiver 33.

Uncondensed gas may be released from receiver 33 through line 34 controlled by valve 35, and the distillate collected in receiver 33 may be withdrawn through line 36 and valve 31.

Treater tank 3 is preferably operated at superatmospheric pressure, which pressure may be the same or may be substantially higher or substantially lower than the pressure employed in the cracking unit in conjunction with which the treating process may be operated. Substantially atmospheric or sub-atmospheric pressures may, however, be employed, if desired, in treater tank 3. Preferably a pressure substantially reduced below the pressure employed in treater tank 3 is maintained in fractionating tower 22 as well as the condensing and receiving equipment.- The process may, however, be operated with substantially equalized pressure throughout.

As an illustration of the application of the invention and the results obtained when processing the cracked vapors boiling below 495 F. and originating from a Mexican gas oil, the cracked vapors are directed to the chamber 3 containing an solution of zinc chloride. The temperature of these vapors as they enter the chamber is approximately 510 F., and the pressure approximately 220 pounds per square inch. The vapors are intimately mixed with the activated hydrogen introduced as they bubble through the zinc chloride solution and are condensed in part as they are reacted upon by the zinc chloride solution. Approximately 40% remain uncondensed and pass over to the condenser and receiver, the pressure being released from approximately 215 pounds to 30 pounds pressure by means of valve 28. The oil layer formed on top of the zinc chloride solution in chamber 3 is withdrawn through line 20 where the pressure is released by valve 2| to approximately 40 pounds and the oil flash distilled by its self-contained heat in the tower 22. Approximately 15% of the total vapors introduced .into the process are withdrawn as condensate through line 23, the fractionated vapors passing overhead to the condenser and receiver and mix ing with the product from chamber 3. The motor fuel withdrawn from the receiver 33 has an endpoint of approinmately 420 F., is stable and water-white, the sulphur content being approximately .12%.

I claim as my invention:

1. A process of treating cracked hydrocarbon vapors, which comprises passing the vapors while still hot into contact with a water solution of zinc chloride in the presence of added hydrogen while under super-atmospheric pressure adequate to effect substantial separation of unsaturates contained in the cracked vapors, separately drawing of! the condensate and the uncondensed vapors after said treatment, subjecting the condensate to further distillation at reduced pressures, and collecting the vapors from said last mentioned distillation.

2. A method of refining mineral oils which consists in cracking the oil to form a cracked vapor, adding hydrogen to the vapor, naming the heated vapor and added hydrogen through or in contact with a maintained aqueous solution of zinc chloride under temperature and pressure conditions adequate to effect substantial saturation of unsaturates contained in the cracked vapor, and then condensing the vapors.

3. A method for refining cracked gasoline 7i vapors containing olefin hydrocarbons and highly reactive unsaturates such as diolefins and terpenes, said method comprising reacting the vapors with added hydrogen in the presence of an aqueous solution of zinc chloride under temperature and pressure conditions adequate to hydrogenate said unsaturates' without'substantially saturating said olefin hydrocarbons.

4. A method for refining cracked gasoline vapors containing olefin hydrocarbons and highly reactive unsaturates such as diolefins and terpenes, said method comprising reacting the vapors with added hydrogen in the presence of a maintained. aqueous solution of zinc chloride under temperature and pressure conditions adequate to hydrogenate said unsaturates without substantially saturating said olefin hydrocarbons.

5. A process for refining cracked hydrocarbon vapors which comprises adding hydrogen to the vapors and subjecting the resultant mixture in the presence of an aqueous solution of a zinc salt to temperature and pressure conditions adequate to effect substantial saturation of unsaturated hydrocarbons contained in the cracked vapors.

6. A process for refining cracked hydrocarbon I vapors which comprises adding hydrogen to the vapors and subjecting the resultant mixture in the presence of an aqueous solution of zinc chloride to temperature and pressure conditions adequate to efiect substantial saturation of unsaturated hydrocarbons contained in the cracked g vapors.

I GUSTAV EGLOFF.

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