US2176655A - Continuous method of cracking hydrocarbon oil - Google Patents

Description

- 7, 1939. w. B. D. PENNIMAN 2,173,655

CONTINUOUS METHOD OF 'cH c iNG- HYDROCARBON OIL- Original Filed, Jan. 5, 1922 Whoa G r ie M 3 2,176,655 PATENT" OFFICE CONTINUOUS METHOD OF CRACKIN HYDROCARBON OIL William B. D. Penniman, Baltimore, Md., assignor to Ellis-Foster Company, a corporation of New Jersey Application January 3, 1922, Serial No. 526,707

Renewed February 25, 1927 19 Claims. (Cl. 196-65) My invention relates to the production from heavier hydrocarbons of lighter hydrocarbons, as well as of oxidized derivatives of these hydrocarbons. As starting material, I may use, crude petroleum oils, or heavy hydrocarbons such as kerosene, gas oil, fuel oil, etc. The products obtained will depend upon the conditions of treatment, but the invention will be described as it is carried out for the production of motor spirit (gasoline) from fuel oil. The method consists in continuously cracking the liquid oil maintained at the cracking temperature best adapted for the production from the particular oil under treatment of the products desired, the cracking being effected under a relatively high maintained pressure due to the presence, not only of the generated hydrocarbon vapors, but also to the presence of a pressure gas, additional to such hydrocarbon vapors. As such pressure gas, I prefer to use, deoxy nated air, the deoxygenation being effected by passing air under pressure through the liquid oil after the oil has been heated to such a temperature, that the oxygen of the air will combine with combustible ingredients of the oil with the resultant generation of sufiicient heat to vaporize and crack the oil.

The resultant products are hydrocarbons lighter than the original oil, as well as oxygenated hydrocarbons which may be separately recovered from the condenser, as will be hereinafter more specifically pointed out.

The apparatus used is shown in the accompanying drawing in which Fig. 1 is adiagrammatic sectional and V Fig 2 is a modified form of air-nozzle.

Referring to Fig. 1, the apparatus consists of an-upright still or drum having heavy walls adequate to sustain a pressure of 300-1bs. or more per sq. in. The still is preferably made in two sections A and B, secured together by companion flanges 3, 4, and suitable bolts. The still is mounted above a gas-fired furnace of any suitable construction. Oil is introduced into the still by a pressure-pump 5, from which leads a delivery pipe 6, having, within the still head, a coil 1, and a depending delivery pipe 8. Air is forced into elevation the still from a pump 9, through pipe l8, having a.

pressure gage l I, coil I2 (within the still), and depending pipe l3, provided at its lower end, which is near the bottom of the still, with an upwardly directed delivery nozzle 86. Blow-cocks l5, enable the level of the oil in the still to be ascertained. it is a blow-ofi line through which residualmaterial is removed. ii, it are thermometer Wells. 2t is a vapor line leading to condenser-coil which is connected to collecting tank 26, provided with a pressure-gage 2t and safety valve 28. The liquid collected in tank 26, is delivered through pipe 29, and the uncondensed vapors and gases pass off through pipe 30, suitable storage or collecting vessels are, of course, connected to pipes 29 and 30.

Only one air delivery pipe has been shown but as many more as are necessary, are used in stills of larger diameter thanthat shown. A modified form of air nozzle is shown in Fig. 2, in which, to the end of the airpipe l3, are'secured a number of radiating pipes I4 provided with apertures .in their upper surfaces.

The process is carried out as follows:

Oil is introduced into the still, either already at a temperature of about 400 F., or is raised to that temperature by the application of heat from the furnace below the still. Air under pressure isthen blown into the still throu h the nozzle i4, and the heatgenerated during the passage of the air upward through the deep body of oil, by oxidation of constituents of the-hydrocarbon, is thereafter sufficient to raise the temperature to the desired cracking point, say 750 F., and to maintain such temperature, the further application of external heat being'discontinued. The preheating of the air and oil in the still head coils 1 and I2, not only saves heat, but these coils condense high-boiling fractions, which run back into the still.

The desired pressure is preferably controlled by providing that the pressure indicated by the gage ll shall be about 25-lbs. higher than that indicated by gage 21 on the receiving tank 26. The order of the pressures used will be indicated by our practice, which as applied to Pennsylvania fuel-oil, required a pressure from 300 to 325-lbs. The total pressures exerted on the surface of the oil is, therefore, due both to the partial pressure of the oil-vapors and to that of the deoxygenated air. The quantity of air introduced is regulated so that practically the entire oxygen content thereof goes into combination,steam, carbon dioxid, carbon monoxid and hydrocarbons containing oxygen, being formed. Some air may pass through the oil unchanged, but its quantity is small, and is never suificient to cause trouble. A constant volume of oil is maintained in the still and the air and oil are continuously delivered to the still at such rate that the temperature and pressure therein are maintained at the desired points for the production of the desired product.

A suflicient depth of hot oil must be maintained in the still, to insure the practically complete deoxidation of the air. In practice, three or four feet has been found to be sufficient. The air flows through the nozzle 54? at high velocity,

and produces a rapid circulation or agitation of The amount of oil consumed by oxidation is small, varying from 540% of the total amount used.

The pressure employed is not an arbitrary constant but is determined by the material being treated. Thus a higher pressure is necessary in treating oils like kerosene than heavier oils, such as fuel oils. My work indicates the limits of preferable pressures as between 50 and 500 lbs., though lower pressures may possibly be used, and it may be advantageous to use higher pressures. So also my invention is not limited to any specific temperatures, as these will vary with the material operated upon. The temperatures to which the liquid oil must be raised for efiective cracking are either within the knowledge- 25% of the constant volume of oil kept in the still, were introduced per hour; and there was obtained a motor-spirit condensate having an initial boiling point of 127 F.; 20% of which boiled at 224 F.; 50% at 318 F.; 80% at 395 F.; and 95% at 532 F.

When properly refined, this gasoline distillate has an aromatic odor widely difierent from the pungent odor of straight-run gasoline and from the unpleasant odor of cracked gasoline; it is water-white; shows no. signs of discoloration after prolonged exposure to light; and fulfills all the other conditions required for commercial gaso line. The carbon formed in the still is in a soft, finely divided condition resembling lamp-black, and is readily blown off with the heavy residue through pipe 16.

The condensate collected in the receiving tank 26, consists of two distinct portions, one consisting principally of hydrocarbons and the oth- 1 er, underlying the first portion, consisting of a water layer or solution.

I have discovered that from these condensates a great variety of materials can be recovered by proper methods of purification and refining. Such a method may be as follows:

The hydrocarbon portion of the condensate, separated by deca'ntation or otherwise from the water solution, is-Washed with water and the washings added to the water solution. The washed hydrocarbon is then agitated with about of dilute alkali, caustic soda or carbonate of soda, and the resulting alkaline soap solution is separated, concentrated, filtered, if necessary, and the soaps formed, separated either by salting out or acidifying and obtaining the fatty or soap acids.

Strong alkali (up to 60%) is then added to the hydrocarbon and agitated for some time. The lye solution is allowed to separate and after treatment with acid is distilled to separate the phenols, etc., dissolved by the strong alkali.

After this alkaline. treatment, the hydrocarbon, after washing free from alkali, is treated with strong sulfuric acid, washed free from acid, neutralized with soda, washed and distilled. The distiilates are Motor fluid (56.4 B. at 60 F.), Turpentine substitute, and burning oil. The

residue in the still can be used as fuel oil or returned to the cracking still. Each distillate may, of course, be retreated and redistilled in the ordinary way to bring it to the necessary commercial grade.

The water solution, together with the washings from the hydrocarbon condensate, may be treated to recover the valuable materials present therein either (1) by distillation; (2) by salting out; or (3) by freezing out.

The first method is preferable, and may be practiced as follows:

The water solution and washingsare filtered, if necessary. This solution contains acetic acid and other acids, and is distilled in a still having an efficient dephlegmator, and the distillate separated into parts according to the boiling points. In this Way I have recovered acetaldehyde, ether, acetone, methyl alcohol, ethyl alcohol, and oxidized intermediate products. When the temperature of the exit vapor pipe has reached 85 C., the distillation is stopped, and. the solution neutralized with a slight excess of alkali, thereby forming salts of the acids present. The organic residue, which to a large extent floats on the water solution, consists largely of phenols and phenoloid bodies, and may be worked up separately orwith the lye solution obtained in the purification of the hydrocarbon distillate.

The uncondensed gases and vapors, which comprise nitrogen, carbon dioxid, carbon monoxid, ethylene and similar hydrocarbons, and oxgencontaining hydrocarbons, are first passed through a suitable absorption apparatus, containing a silica gel, activated carbon, or straw oil absorber, the latter being preferred as it will absorb more of the light oxygen-containing hydrocarbons and new form of motor spirit, as well as other easily removable valuable by-products. The conditions of operation are under ready control, since the pressure exerted on the liquid oil is due both to the vapor pressure corresponding to the temperature to which the oil is heated, and to the pressure gas, other than such oil-vapor, and this gas, viz.air, is first used to furnish the oxygen necessary for the internal combustion which heats the liquid oil to the necessary temperature. The pressure employed may therefore be only that due to the vapor pressure or it may be increased to the desired extent, by added gas pressure.

While I have given a specific example of the conditions under which the process has been applied to a particular oil it will be understood that the conditions of temperature and pressure may be widely varied in their application to different oils.

This application is a continuation in part of my prior application Serial No. 299,213, filed May 23, 1919.

I claim: I

1. The method of treating liquid hydro-carbons to obtain more volatile hydrocarbons which arrears comprises bringing the liquid to a temperature at which it will combine with the oxygen in the air with suflicient rapidity so that the heat given off by the combination is sufficient to increase the temperature of the liquid, maintaining the liquid under pressure and passing air into the liquid causing oxidation with generation of heat within the body'of the liquid and regulating the combination by regulating the quantity of air to produce and maintain cracking temperatures such as to form lighter hydrocarbonsin substantial proportions and leading the gases and vapors of the lightr hydro-carbons away from the liquid and condensing them.

2. The method of treating liquid hydrocarbons,

as fuel oil and kerosene and the like, to obtain more volatile hydrocarbons, which consists in bringing the liquid to a temperature at which it is rendered capable of combining with the oxygen in the air with suflicient rapidity to bring the liquid to and keep it at cracking temperatures,

maintaining the liquid under pressure, passing air into the liquid whereby the air is deoxidized combining with a portion of the hydrocarbons and thetemperaturepf the liquid is raised to and maintained at cracking temperatures giving off volatile hydrocarbons in vaporized condition, leading the vapors from the liquid and cooling them. I

3. The method of treating liquid hydrocarbons in cracking under pressure to obtain more volatile hydrocarbons which consists in bringing the liquid to a temperature at which it is rendered capable of combining with the oxygen in the air with sufficient rapidity to cause the liquid to attain and maintain cracking temperatures, passing air into the body of the liquid and thus maintaining slow combustion within the body of the liquid and regulating the combustion to produce and maintain cracking temperatures, causing the volatile constituents of the liquid to assume a vaporous or gaseous condition, leading the vapors and gases away from the liquid and condensing them, said treatment being carried on under pressure in excess of atmospheric pressure.

4. The method as claimedin claim 3 in which the pressure is controlled by regulating the pressure of the air passed through the oil.

5. The method of cracking heavy hydrocarbon oils which consists in passing air under pressure through liquid oil hot enough to combine with the oxygen of the air, the air being passed through at such rate that the heat of oxidation wiii raise the body of the oil to and maintain it at a cracking temperature, thereby cracking the oil and forming oxygen-derivatives of the hydrocarbons, maintaining the entire system under pressure, condensing the vapors cooled from the oil, and recovering the lighter hydrocarbons and oxygen derivatives from the condensate.

6. The method as claimed in claim 5 in which the system is maintained under a pressure higher than that due to the vapor pressure at the temperature used, by introducing air under the requisite pressure. p

l. The method as claimed in claim 5 in which the lighter hydrocarbons are separated from the remainder of the condensate, and each portion is separately treated to recover the desired products therefrom.

8. The method of cracking heavy hydrocarbon oils which consists in passing air under pressure through liquid oil hot enough to combine with the oxygen of the air, the air being passed through at such rate that the heat of oxidation will raise the body of oil to and maintain it at a cracking temperature, thereby cracking the oil,

and maintaining the entire system under a pressure higher than that due to the vapor pressure at the temperature used, by introducing the .air' under the requisite pressure.

9. The method as claimed in claim 1 in which the oil is preheated by heat interchange with the hot vapors within the still in which the reaction takes place.

10. The method as claimed in claim 1 in which air and oil are preheated by heat interchange with the hot vapors within the still in which the reaction takes place.

11. The process of making fatty acids from hydrocarbons, said process consisting in acting on the hydrocarbons in the liquid phase withan oxidizing agent and distilling oflthe fatty acids immediately upon their production.

12. The process of making fatty acids from hydrocarbons, said process consisting in acting on the hydrocarbons in the liquid phase with a gaseous oxidizing agent and distilling ofi the fatty acids immediately upon their production.

13. The process of making fatty acids from hydrocarbons, said process consisting in acting on the hydrocarbons in the liquid phase with oxygen and distilling off the fatty acids imme-- diately upon their production. 7

14. The process of making fatty acids'from hydrocarbons, said process consisting in acting on the hydrocarbons in the liquid phase with oxygen and after the said oxidizing action has started continuously distilling off the fatty acids immediately upon their production.

15. The process of preparing hydrocarbon products which comprises feeding liquid hydrocarbon and air to a passage heated to a-temperature of between 400 and 750 F., refluxing the vaporous products, then removing the vapors and condensing the same, and treatingthe resultant condensate with alkali to remove a portion of the constituents therefrom.

16. The process of making fatty acids from hydrocarbons, said process consisting in acting on the hydrocarbons in the liquid phase with an. oxidizing agent at a temperature-of above 160 C. and distilling off the fatty acids immediately upon their production.

17. The process of making fatty acids from hydrocarbons, said process consisting in acting on the hydrocarbons in the liquid phase with an oxidizing agent at a temperature of above 160 C. and introducing a distilling agent causing the fatty acids to distill off immediately upon their production.

18. Process which comprises agitating a normally liquid hydrocarbon containing an aliphatic chain, in liquid phase, in contact with an oxidizing gas at a temperature of at least about 400 F. and at a pressure of from about 100 pounds to about 320 pounds per square inch. I

19. In the treatment of a partial oxidation product having hydrocarbons which already contain artificially-introduced chemically-combined oxygen to different degrees of oxidation, and which contain like bodies of different molecular weights, the steps consisting of fractionating the same into liquid fractions of different average molecular weights and subjecting the lighter fraction to further chemical treatment.

WILLIAM B. D.

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