US2080701A - Treatment of hydrocarbon oils - Google Patents

Description

May 18,

R. B. DAY

TREATMENT OF HYDROCARBON OILS Original Filed June 15, 1931 @mA w.

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Patented May 18, 1937 UNITED sTATEs PATENT OFFICE TREATMENT or maocAanoN ons Application June 15, 1931, Serial No. 544,372 Renewed February 4, 1936 This invention relatesv to the treatment of hydrocarbon oils and refers more particularly to the treatment of low boiling distillates produced in cracking operations although similar. distil- 5 lates from the non-cracking or primary distillation of crude petroleums may be treated.

More specifically, the invention has reference to an improved process for the treatment of such low boiling hydrocarbon distillates to reduce their content of highly unsaturated or gumforming hydrocarbons and change the form of combination of the sulphur and to some extent reduce its percentage.

vLower boilingv petroleum distillates, more specically those produced from the cracking of the heavier portions of crude petroleums and containing material amounts of components boiling within the range of commercial gasoline commonly contain undesirable amounts of highly unsaturated hydrocarbon derivatives of the straight-chain, cyclic and mixed type which tend to polymerize to form gums and resins upon standing and also contain representatives of well known groups of sulphur derivatives such as the mercaptans, sulphides or sulphur ethers, thiophenes, thiophanes, etc., and it is the purpose of all commercially used methods of treatment to reduce the content of these classes of compounds in the distillates to a point meeting commercial requirements. The method of treatment of longest standing consists generally in treatment with sulphuric acid of commercial grade after a preliminary washing with caustic soda solution to remove hydrogen sulphide and to some extent the mercaptans. This type of treatment, however, possesses numerous well recognized disadvantages in the cost of the reagents employed, and the lack of selectivity in the action of the reagents, particularly sulphuric acid, the latter 40 not only forming addition compounds with oleflnes, but also inducing polymerization and condensation reactions to form tarry sludges due toy its powerful oxidizing and dehydrating action, these sludges being diilicult to treat for the re- 45 covery of the acid without large losses thereof by reduction. Furthermore a redistillation of the treated oil is practically always necessary owing to thepresence in solution of a certain amount of high boiling polymers. The present inven- 50 tion is concerned with a more emcient method of treating cracked distillates in a manner and by means better adaptedl to selectively and controllably remove the necessary amounts of gumforming componentsand at the same time effect 55 a sweeting action on the distillate to produce odorless organic disulphides from the foulsmelling mercaptans. Other objects and advantages will more fully appear from the following detailed description.

In one specific embodiment the invention com- 5 prises treating petroleum distillates with hydrochloric acid, preferably at elevated temperatures, removing immiscible reaction products, vaporizing the treated distillates, passing the vapors through solid contact and/or catalytic me- 10 tallic materials, and fractionating the treated vapors to produce fractions of desired boiling point range which are cooled, condensed and collected.

In co-pending applications covering the treat- 15 ment of distillates, I disclosed a process for the treatment of such distillates in the vapor phase with hydrochloric acid and various contact and 1 catalytic materials such as, for example, metals particularly copper, zinc and mercury which I have shown exert a catalytic effect upon the polymerizing and condensing reactions induced by hydrochloric acid. In my previous disclosures I have shown means for introducing hydrochloric acid into the oil vapors to be treated either as a 25 gas or as an aqueous solution. I have now further discovered that equally good results are obtainable if the distillates are treated with hydrochloric acid and .then revaporized and passed through the solid contact masses without further addition of hydrochloric acid. While the exact nature of the chemical reactions involved iis not entirely clear, it is apparent that in addition .toy the solution of a certain amount of hydrochloric acid in the oil that certain chlorine and hydrochloric acid addition compounds are formed whichsexert a similar inuence on the course of the reactions of polymerization to that exerted by hydrochloric acid added after the oils have been vaporized.

To assist in describing a particular mode ot operation among the many comprised within the scope of the invention, the attached drawing is provided which. shows diagrammatically in side elevation one arrangement of equipment which may be employed in conducting the process. Referring to the drawing, there is shown a liquid phase treater 8 wherein the oils may be treated with hydrochloric acid, a furnace 2l wherein the treated oils may be heated to a point necessary to insure their vaporization, a vapor phase treater 26 anda fractionator 66 followed by the usual condensing and collecting equipment. Liquid phase treater 8 is .assumed at the start of the operation of the process tov contain a body of distillate 8 Hydrochloric acid either as a gas or in aqueous solution may be introduced to a pump 3 from a line I containing a regulating Valve 2 and circulated throughout the body of oil until the desired degree of treatment or saturation of the oil has been obtained. When vapors of hydrochloric acid are employed they may be pumped through line 4 with control valve 5 closed and diverted into line 6 containing valve 1 and ending in a spray 1 which eiectually distributes the acid vapors throughout the body of oil in a ne state of subdivision.- For the most effective utilization of the acid the unused vapors may enter a spray 5 in the vapor space above the body of oil and be drawn back to the pump through a line 9 containing therein a regulating` valve I0. Aqueous solutions of hydrochloric acid may be used to treat the oil in a reverse manner by discharging them through line 4 with valve 5 open and valves 1 andA II) closed so that the acid solution is sprayed downwardly through the oil body'from the distributing means 5'. The full utilization of the strength of the acid may be assured by provision of a lower liquid draw line II containing control valves I2 and I2', a branch line I3 containing a control valve I4 leading back to the suction side of pump 3 to enable the circulation of the acid solution through the oil until its strength is spent. Valve I2' may be utilized to reject spent solutions or immiscible sludges from the treater.

Assuming that the oil has absorbed either chemically or in solution a suflicient amount of hydrochloric acid, it may then be distilled and subjected to the succeeding vapor phase contact treatment. To that end a line I5 containing a control valve I6 leads from a point above the sludge level in liquid phase treater 8 to a suitable pump I1 which discharges through a line I8 containing a regulating valve I9 through a tubular element 20 disposed to receive heat from a furnace 2|. During passage of the preliminarily treated oils through the heating element sumcient heat may be added to insure substantially complete vaporization through vaporization in the heating element itself may be kept down by throttling the discharge to maintain a certain degree of back pressure on the coil. The temperatures to which the oils are heated during passage through the heating element depend upon the boiling point range and the pressure to which they are subjected and in some cases it may be found advantageous to superheat the vapors above their normal boiling pgintbto obtain more extended treating effects in the succeeding vapor phase treater. The heated products may be discharged into a transfer line 22 containing a control valve 23 and having a branch line 24 containing a control valvey 25. Line 22 leads to upper vapor space 28 in treater 28, the vapors being admitted to this space when it is desired to pass them downwardly through the contact mass 21 and depend to a great extent upon subsequent fractionation to produce the boiling point range desired in the nnished product. When the vapors are diverted through line 24 they may enter a lower vapor space 29 below the perforated false bottom 21' upon which is supported the contact mass and pass upwardly through the same mass to `undergo a. certain degree of fractionation during the treatment. In the event that upward 4iiow is selected the treated vapors may leave through a line 32 containing a control valve 33 and pass directly into line 40 containing a con-i trol valvejl and leading to the condenser, or if further fractionation than that effected in the contact mass is found to be necessary, they may be passed through a line 36 containing a control valve 31 and join with line 34 to enter the bottom of the fractionator 66.`

In the event that downward ilow is selected for any reason treated vapors and condensed liquids of a polymerized and high boiling character may pass into lower vapor space 29 wherein a preliminary separation is'effected, the vapors passing out through'line 34 containing av control valve 35 and entering a fractionator 66. The vapors of desired boiling point range may leave fractionator 66 through a line 38 containing a control valve 39 and pass through line 40 containing control valve 4I to condenser 42 which cools and partially liqueiles the components of the vapor so that cooled liquids and gases pass through line 43 containing valve 44 to a receiver 45. In this receiver separation of xed gases and liquids is effected to a degree dependent upon the temperature and pressure and the time allowed for attaining equilibrium conditions, nxed gases being removed through Aa. line 46 and a valve 41 at a rate consistent with the maintenance of.

desired back pressure on the preceding portions of the equipment. Finished gasoline not needed for recirculation may be withdrawn to storage through a line 48 containing control valve 49,

such portions as are 'necessary for. assisting in f trol valve 54.

Liquid accumulations consisting of high boiling polymers and a certain amount of chlorinated reaction products, both organic and inorganic, may

be withdrawn from the bottom of the vapor .phase treater and the fractionator and disposed of in any proper manner depending upon their composition. Those accumulating in the bottom of the vapngr phase treater 26 may be withdrawn through a line 55 containing a control valve 56 to the intermediate accumulator 51 and those accumulating in the bottom of fractionator 66 to the same accumulator through a line 53 containing a control valve 59, eitherintermittently or continuously. The accumulator may have a vapor space connecting line 60 leading to the bottom of the vapor phase treater to prevent accumulations of gas and impede the ilow of liquids through line 55, the gases being returned and being ultimately released from the nal receiver 45. A pump 63 may be provided for the disposal of the polymers and other reaction products, this pumpbeing connected to the accumulator through a line 6I containing a control valve 62 and discharging through a line 64 containing a control valve 65 to any suitable point of disposal, in some cases back to the liquid phase treater, in other cases to distiliing or cracking equipment and sometimes to waste.

The preceding description with reference to the drawing has given a general outline of operations which may be conducted within the scope of the invention but it is not to be assumed that the l desired with a corresponding pressure development or such treatments may be conducted in a continuous treating plant comprising entirely different elements than the simple batch treater indicated at 8.

Similarly pressures and temperatures may vary over a wide range in both`the vapor phase treater and the fractionator, the former being either substantially equalized throughout the vapor phase treating and fractionating equipment with differences arising merely from fluid friction or the treater may be maintained at considerably highe temperature than the fractionator.

An an example of the results obtainable by the operation of the process, cracked distillates made from a heavy Mid-Continent gas oil" may be assumed to be treated in a layout generally similar to that shown in the drawing. By spraying a 10% aqueous solution of hydrochloric acid through the distillate until an amount is absorbed equal to approximately 2 pounds per barrel, the spent solution may be removed and the heated oil pumped through a heating element under approximately 150 pounds back pressure until a temperature of 350 to 400 F. is obtained, after which it is passed downwardly through a contact mass consisting of brass turnings, the vapors being separated from the polymers inthe bottom part-of the treater and in the subsequent fractionator.

, The properties of the distillate treated may be as follows:

Gravity A. P. I 52 Color Straw yellow to light brown Reaction with doctor solution Positive Sulphur content 0.3%

The simple rerunning of this distillate to produce a 400 F. end point gasoline may yield only a product of 15 to 20 color with a gum content by the copper,` dish method of 200 to 250 mgs. per

100 ccs. lThe reaction with the doctor solution being still positive.

By processing the distillate according to the present invention, the gasoline produced may be approximately 3 0 color on the Saybolt scale and have a gum content of approximately 25 mgs. the

, reaction with doctor solution being negative. The

sulphur content may be found to be slightly reduced over the content of a gasoline of similar boiling point produced by the redistillation of the untreated distillate, being 0.1% as compared with 0.15%.

I claim as my invention:

1. A process for refining hydrocarbon oil which comprises treating the oil in liquid condition with aqueous hydrogen chloride, then vaporizing the oil, and contacting the vapors with brass.

2. A process for refining hydrocarbon oil which comprises treating the oil in liquid condition with aqueous hydrogen chloride, then vaporizing the oil, and subjecting the vapors to the action of a contact material containing zinc and copper.

3. A process for refining hydrocarbon oil which comprises treating the oil in liquid condition with aqueous hydrogen chloride, then vaporizing the oil, and contacting the vapors with zinc.

4,. A process for refining hydrocarbon oil which comprises treating the oil in liquid condition with aqueous hydrogen chloride, then vaporizing the oil, and contacting the vapors with copper.

5. A process for rening hydrocarbon oil which comprises treating the oil in liquid condition with hydrochloric acid and absorbing a substantial portion of the acid in the oil, subjecting the oil with its absorbed acid to vaporization, and con-v tacting the resultant vapors with zinc.

ROLAND B. DAY.

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