US2371298A - Treatment of hydrocarbon oils - Google Patents

Description

March 13, 1945. T. B; HUDSON ET AL' 2,371,298

TREATMENT OF HYDROCARBON OILS Filed Dec. 10, 1940 2 Sheets-Sheet 1 UOLVHVdBS INVENTOR T. B. HUDSON J. O. TURNER I BY maria a March 13, 1945. T. B. HUDSON ETAL TREATMENT OF HYDROCARBON OILS Filed Dec. 10, 1940 2 sheets-Sheet 2 HQLVHVdI-IS BOLVNHQOHQAHEIO UOLVN OI LOVELI Patented Mar. 13, 1945 UNITED STATES PATENT OFFICE TREATMENT OFiiiliZOGARBON OILS Thomas 13. Hudson and James 6. Turner, Battlesville, kla., assignors to Phillips Petroleum Company, a corporation of Delaware Application December 10, 1940, Serial No. 369;470

This invention relates to the treatment of hydrocarbon oils and particularly to the treatment or etroieu'm dis'tillates.

This invention is particularly concerned with the treating of hydrocarbons to produce an improved motor fuel. Hydrocarbon distillates, naphthas, gasoline, kerosene, and gas oils may be desulfurized in accordance with this invention. The desulfurization of the hydrocarbons in the manner disclosed herein results in improved octa'ne number and lead susceptibility, characteristics which are particularly desirable in motor fuels.

It is well known that a hydrocarbonoil mixture may be treated as a whole by dehydrogenation or desulfurization to improve the quality of the oil and increase its market value. Catalytic delay Sulfur impurities are effectively removed from drogenation', widely used today, improves the octane number of the hydrocarbon oil and reduces its sulfur content. Catalytic desulfurization serves to remove undesirable sulfur compounds from hydrocarbons and may be carried out at much lower temperatures than those required for catalytic dehydrogenation. Caustic washing and clay treating are well known means of removing undesirable impurities from the hydrocarbons.

The Sulfur content Ofthe etroleum distillat'es varies with the boiling point of the material. The total Sulfur content in the distillates from most crudes and in most gasolines is generally higher in the higher boiling fractions than in the lower boiling fractions. Hydrogen Sulfide and other very volatile sulfur compounds present in the distillateswill, because of their volatility, be included in the low boiling hydrocarbons but these are readily removed by stabilization or by caustic wash and present no serious problem to the refiner. Other sulfur compounds in the petroleum are usually distributed in accordance with the boiling point, being present in greater amounts in the higher boiling fractions.

Due to the wide variations in the crude oils from which the petroleum distillates are obtained, it is almost impossible to state rules that will be valid in every instance. Generally, however, the

vdi'stillathes from a given crude oil, comprising the gasolines, kerosenes, naphthas, g'as oils, etc., if broken down into the different boiling range fractions Will yield low octane heavier fractions and higher octane lighter fractions. All of the distlllate obtained from the topping of acrude oil may be subjected to catalytic desulfurization or catalytic dehydrogenation as known in the art. Catalytic dehydrogenation using bauxite catalyst removes the sulfur impurities and improves the hydrocarbon oils by catalytic desulfurization but, aside from an improvement in the lead susceptibility, very little if any improvement is made in the octane number of the oil. While the operating conditions for catalytic desul'furization are not as severe as the operating conditions for cat alytic dehydrogenation; some damage to the octane numbers of the lighter fractions may be experienced.

The present'proc'ess provides a method of and apparatus for treatmentof the hydrocarbons to obtain the optimum improvement in desirable characteristics of the hydrocarbons with a minimum amount of treatment. This is accomplished by separating the distillate into fractions having different boiling ranges and treating each fraction in the manner which will result in maximum improvement in the charge stock. The low oc-'- tane, high sulfur, high boiling fractions, are subjected to catalytic dehydrogenation to remove the sulfur and increase their octane numbers. Intermediate fractions containing sulfur are subjected to catalytic desulfurization to remove sulhydrogen; hydrogen sulfide, methane, and the like are separated from the liquid hydrocarbons. The treated hydrocarbons after separation from the gas may be further treated in any conventional mannerthat may be desirable.

An object of this invention is to provide an improved method and apparatus for treating liydrocarbon oils.

Another object of this invention is to utilize waste heat contained in the eflluent of one reaction to supply the necessary heat for carrying out another reaction.

Still another object of this invention is to provide a process for treating a hydrocarbon mixture wherein the mixture is separated into a plurality of fractions and each fraction so treated that the maximum improvements in octane number, lead susceptibility, and sulfur content of the treated hydrocarbon mixture, result.

A further object of this invention is to provide novel apparatus for carrying out catalytic dehydrogenation and catalytic desulfurization.

Figures 1 and 2 are diagrammatic elevation views of two specific embodiments of the present invention.

With reference to Figure 1, the numeral 4 designates a conventional fractionator. The hydro carbon oil to be treated, for example, a, naphtha of low octane number and high sulfur content enters the fractionator through the pipe 5, and is cut into at least three fractions of different boiling points. A- fraction having an end point of about 300 F. is taken from the top of the fractionator as a vapor through the pipe 6. This fraction has a relatively high octane number and contains some sulfur. A higher boiling fraction, having an end point of about 450 F. is taken olf the fractionator as a liquid sidestream through the pipe 7. The 450 F. end point fraction contains a higher percentage of sulfur than the overhead product and has a low octane number. The remainder of the original naphtha is withdrawn from the base of the fractionator through thepipe 8, from which it may be passed to other refinery processes for further treatment. The relatively high sulfur, low octane, 450 F. end point fraction, is passed through the pipe I to the furnace 9 where it is vaporized and heated to a temperature in the range 900-1050 F. The heated vapors are passed at this temperature and at a pressure less than 150 pounds per square inch through the pipe. l and over the bauxite catalyst in the dehydrogenator H. The dehydrogenation step accomplishes reforming of some of the hydrocarbons into others of higher octane number andremoval of sulfur. A small amount of cracking may accompany the desulfurization reaction. The eilluent of the dehydrogenation is passed through the pipe l2, the heat exchanger l3 and the pipe 14 to the cooler 5.

The relatively high octane, 300 F. end point fraction taken from the top of fractionator 4 is passed through the pipe 6 to the heat exchanger I3. In the heat exchanger the temperature of this fraction is raised to the range of GOO-800 F. by indirect heat exchange with eflluent from the dehydrogenator. From the heat exchanger, the heated vapors pass through the pipe l6 to the desulfurizer H where it is passed over a bauxite catalyst. The desulfurization is carried out at less than 150 pounds per square inch pressure and removes the sulfur withoutmhanging the structure of the hydrocarbons to any appreciable extent. Efiiuent from the desulfurizer is mixed with eiiiuent from the dehydrogenator .in pipe Hi and passed to the cooler l5. The cooled mixture from the cooler flows through the valve 18 and pipe [9 into theseparator 20. Hydrogen, hydrogen sulfide, and other gases pass off the top of theseparator 20 through thepipe 2!. The treated liquid hydrocarbons from the separator flow through the pipe 22 to any desirable conventional refining processes or to storage.

With reference to Figure 2, the hydrocarbons to be treated flow through the pipe 25 into thefractionator 26. From the top of the fractionator a low boiling, low sulfur content, high octane fraction in vapor form is passed through thepipe 27 to acondenser 28. Condensate and unconclensed gases passing the condenser flow to therun tank 29. The gases separated from the liquid in the run tank pass out through thevalve 30 and pipe 3!. Condensate is withdrawn from the run tank through thevalve 32 from which it may be passed through the pipe 33 to storage or to any desirable treating process, for example, the condensate may be given a caustic wash, such processes being well known in the art and forming no part of the present invention.

The high boiling heavy ends are withdrawn from the base of the fractionator through the pipe 34 containing the control valve 35, to be disposed of in any suitable manner. At points intermediate the top and bottom of the fractionator are drawn off fractions of different boiling ranges through thepipes 36 and 31. The fraction drawn off through thepipe 31 is low octane, high sulfur, high boiling fraction suitable for dehydrogenation. This fraction is passed to the furnace 33 where it is raised to dehydrogenation temperature and from which it passed through thepipe 39 to thedehydrogenator 40. Thedehydrogenator 40 is a catalyst chamber containing a suitable dehydrogenation catalyst. Eflluent from the dehydrogenator flows through the pipe 4| from which it may be passed through thevalve 42 to the cooler 43 or through thepipe 44 and valve 45 to thedesulfurizer 46.

The fraction withdrawn from th fractionator through thepipe 36 has a good octane number and an intermediate sulfur content. The boiling range is between that of the fraction drawn off through thepipe 31 and that of the fraction passing overhead through thepipe 27. The fraction fiows through thepipe 36 to the desulfurizer where it is admitted through the control valve 41.: A quantity of hot efiluent from the dehydrogenator, sufilcient to raise the temperature of the intermediate sulfur content fraction to the desulfurization temperature, is admitted to the desulfurizer through the control valve 45. Thedesulfurizer 46 is a catalyst chamber filled with a suitable desulfurization catalyst. Eflluent from the desulfurizer is passed to the-cooler 43 where it is cooled and mixed with that portion of the dehydrogenation effluent passing thevalve 42.

From the cooler 43 the treated hydrocarbons are passed through thepipe 48 into theseparator 49. Hydrogen and other gases leave the top of the separator through thepipe 50 containing a control valve 51. Treated liquid is drawn from theseparator 49 through thecontrol valve 52 into the pipe 53 from which it may be passed to storage or further refining.

The specific embodiments described herein are given by way of illustration only and are not to be construed as limiting the present invention. While a bauxite catalyst is described, itis evident that other dehydrogenation and. desulfurization 1 catalysts, either natural or synthetic materials, may be used in the process of the present invention. The temperatures and pressures cited are those which are considered good practice at the present time for use with bauxite catalysts. If other catalysts are used, the temperatures and pressures used will be those at which the best results are obtained.

We claim:

The method of treating hydrocarbon distillates comprising separating the hydrocarbonsinto a v contacting a high-boiling fraction with bauxite at a temperature in the range of 900-1050" F. to

improve the octane number and reduce the sulfur content of the same, blending thehydrocarbon fractions, and stabilizing the treated hydrocarbons to obtain improved motor fuel.

THOMAS B. HUDSON. JAMES O. TURNER.

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