US1408698A - Process for the continuous production of low-boiling-point hydrocarbons from petroleum oils - Google Patents

Description

R. W. HANNA.

PROCESS FOR THE CONTINUOUS PRODUCTION OF LOW BOILING POINT HYDROCARBONS FROIVI PETROLEUM OILS.

APPLICATION FILED DEC.22, I919. RENEWED OCT. 22.192].

Patented Mar. 7, 1922.

WITNESS INVENTOR fi/[HA #17 w. A A/V/VA A TTORNE Y of car UNITED STATES PATENT ornca.

RICHARD W. HANNA, O! RICHMOND, CALIFORNIA, ASSIGNOB TO STANDARD OIL COIPANY OF CALIFORNIA, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OI CALIIORNIA. I

IPROCESS I'OIB THE CONTINUOUS PRODUCTION OF LOW-BOILING-POINT HYDRDCAR BOMB raou rn'rnonriuu oILs.

Specification of Letters Patent.

Patented Mar. 7, 1922.

Application died December 22, 1 919, Serial No. 346,820, Renewed October 22, 1921. Serial Io. 509,527.

To all whom it may concern:

Be it known that I, RICHARD W. HANNA, a citizen of the United States, residing at Richmond, in the county of Contra Costa and State of California, have invented a new and useful Process for the Continuous Production of Low-Boiling-Point Hydrocarbons from Petroleum Oils, of which the following is a specification.

My invention relates to the art of produc ing low-boiling point hydrocarbons from hi her boiling point petroleum oils .or distil ates.

This invention provides a process whereby a substantially uniform low boiling int hydrocarbon oil' is continuously pr uced ration, without the deposit us, so id hydrocarbons or tarry residues in the heating element. I

This invention also provides a process whereby all of the solid hydrocarbons of tarry residues resulting from the cracking are kept in solution or suspension by a solvent oil and finally discharged from th apparatus. i r

have discovered that in the cracking of hydrocarbon oils to produce low-boiling point oils carbon is produced in successive steps, primaril in the ,form of tarry bodies, and later by tile furtherreduction of these tarry bodies carbon in the more concentrated forms is produced. I have found that if the or fraction produce formation of, these tarr bodies or the further reduction thereo towards carbon can becontrolled and the resultant relatively high boilin ,point fractions held substantially in SOfiltlOll, the cracking may be carried on substantially continuously, without the deposition of carbon.

By maintaining in the apparatus or system such a To ortion of solvent oil in connection wit t e oil to be cracked that immediately upon the primary reduction of the oil to be cracked to relatively low boilingv int oil, this solvent oil immediately hol s in solution the relativel high boiling point oil by such cracking, so that'it may be discharged from the apparatus without de sition therein.

Following is a etailed description of my preferred embodiment of the invention:

In its preferred form of embodiment, my

sition of the oil therein, b

process consists inmaintaining in the appa ratus during the operation a substantially constant volume of the oil to be treated, continuously withdrawing the low-boiling point fraction as roduced, substantially continu- -ously with rawing the residual oil which contalns the solid hydrocarbons or tarrytem.- The deposition and accumulation of these substances upon heated surfaces retard the conduction of heat through the metal which not only results in the loss of heat, but also in a slow destruction of the metal dueto an over heated condition which in time results in the destruction of the apparatus. Also such an apparatus cannot be operated continuously as it must be shut down atintervals to clean out this accumulation, with the resultant loss of time, ca pacity, and efliciency.

In common practice, the oil undergoing cracking is either contained in a still, capable of withstanding a predetermined pressure, and towhich the heat is directly applied or it is circulated from a reservoir through an auxiliary heating element. In either case the process is not continuous and is always accompanied by the deposition of solid hydrocarbons which must be removed at the end of each run, and the apparatus renewed after a certain period of time.

\In the preferred embodiment of my invention, I overcome these ,difiiculties by substantially continuously removing from the heating element the solid hydrocarbons and tarry residues, resulting from the decompothe COIltlIlllOllS introduction of a solvent oi which dissolves and keeps in solutionsaid solid hydrocarbon and itarry residues thus reventing a deposition on. the metallic sur aces of the system.

The rimary feature of my method is the con inuous removal of all the solid-hydrocarbons and tarry residues from the heating element by the employment, conjointly with the oil to be cracked of a continuously circulating medium relatlvely'non-crackable.

.' cracking are held in suspension or solution on its suction side, wit

without being allowed to de it.

In practice this solvent oil which I have termed non-crackable may be any hydrocarbon oil which is stable to the heat and pressure employed in the process. To illustrate my invention such a stable oil may,

for example, be a distillate from the socalled refractory California crude oil which is an oil of relativelp low boiling points containin an unusal y high percentage of napht one and aromatic hydrocarbons, or it may be any lower boiling int fraction of the same, or any other oi, which will be substantially unafiected at the pressure and temperature employed in the cracking of the particular oil operated upon.

It is also to be understood that my method is not confined to the use of any particular non-crackable or solvent oil' either produced in the s stem or added from any outside source, t e herein mentioned oils being given merely as an example of a circulating medium relatively unaffected by the pressure and temperature required to crack the oil to be treated.

With the foregoing preliminary explana tion the preferred embodiment of my method will now be more fully described, by reference to the accompanymgdrawing showing an apparatus in which it may be carried out. 7

In the drawing isshown a general diagrammatic view of such an apparatus, in which 1 represents a storage vessel for the solvent oil. 2 is a pump for handlin this stock and 3 is a pipe connecting throng a valve 4 with a vessel 5 I term an evaporator. 6 is a circulatin pump connecting, a pipe 7 from the evaporator 5 and on its discharge side with a pi e 8 leading to the heating element, whic is here shown as a coil 9 in a furnace 10, said coil 9 leading through a pipe 11, back to the evaporator. 12 is a reservoir for the oil to be cracked. 13 is a pump connected by a pipe 14 with the reservoir 12 and by a pipe 15 with the solvent oil pipe 3. 16 is the vapor line from the evaporator 5. 17 is a dephlegmator in said line 16. 18 is a condenser connected with said dephlegmator. 19 is a receiver connected with the condenser and 20 is a valve where pressure is released and the. condensate delivered for storage. 21 is a discharge pipe from the evaporator 5. 22 is a cooler to which pipe 21 leads. 23 is a discharge valve from the cooler, and 24 is a reservoir.- 25 is a receiving pan connected to a pipe 26. 27 is a T with an open end into evaporator 5 and connected throu h the end of evaporator 5 to the pipe 7 t e suction side of circulating pump 6. referably the fresh stock-to-be-cracked and solvent oil dro into the pan 25 and are conducted by t e pipe 26 through the T 27 and then mix with the suction from the evaporator 5 in the suction pipe 7 of the pump. The pipe 26 is connected with one end of the T and the suction pipe 7 with another openin leaving the third opening open into t e liquid in the evaporator 5. Obviously, the vapor s ace can never extend below the openin o the T into the evaporator 5. Preferaby the vapor space of the evaporator is approximately ODE? third; the liquid two-thirds filling the evaporator to ensure positive suction to the pump at all times.

My method may be carried out in this ap aratus as follows:

referably in startin the operation the evaporator 5 may be c arged to a predetermined level, leavingsultable vaporization space, from the stora e vessel 1, by the pump 2, through the pipe 3, with the solvent 01], which in practice is a relatively.

non-crackable oil, by which is meant an oil not subject to cracking under the pressure and temperature r uired for cracking the oil to be treated, rom which latter re atively low boiling point fraction is to he obtained b distillation. When the evaporator 5 has be oil a aforesaid, the circulating pump 6 is started causing said solvent oil to circulate from t e evaporator 5, through the T 27, pipe 7, pump 6, pipe 8, heating element coil 9, and pipe 11 back to the evaporator 5.

Heat is then applied to the coil 9, and the total charge of solvent oil is heated and during this period, a certain amount of the oil to be cracked is fed from the reservoir 12, by the pump 1-3 and pipes 14, 15 and 3, into the evaporator 5, and a pressure of vapor suflicient to permit the oil to be raised to the required temperature for cracking is develo d.

From t e reservoir 12 the oil to be cracked is pumped by means of pump 13 through line 15 into line 3 where t meets and is mixed with the solvent oil supplied to theline 3, from reservoir 1 b means of pump 2. With the ap aratus, as indicated in this drawin from line 3 the oil to be cracked mixed wit the solvent oil passes through valve 4 into vapor line 16 where it serves as a scrubber oil for the upcoming oil vapors from eva orator 5 and partly condenses the relative y higher boiling point portions of the vapors and which t en mixed together fall into pan 25 and flow through pi e 26 into pipe the suction line of circu ating pump 6,

en charged with the solvent which discharges into line and heating coil 9, where t e mixture is brought to the desired temperature to crack the crackable oil into the desired relatively lower and higher boiling point oils. Upon the cracking of the crac a high and low boilin point fractions the so vent oil immediate y takes into solution and holds such higher boiling point fractions, thus reventlng their further reduction, while t e lower boiling point fractions pass off. From coil 9 the oil roducts are discharged into evaporator 5, w ere the low boiling point oil vaporizes and passes into vapor line 16. The vaporized OllS passing up through line ,16 are scrubbed as hard tofore described and pass into de legmator 17, which is maintained at such a temperature that the solvent non-crackable oils produced by the destructive distillation and which were not condensed in the scrubbing are now condensed and fall back into pan 25. The desired low boiling products pass from dephlegmator 17 into condenser 18 where they are condensed and flow into receiver 19. F

From the evaporator 5 the solid hydro carbons and tarry residues'in the solvent oil are discharged through the valve. 21 and cooler 22, valve 23 and into receiver 24, at

such rate as to keep the saturatidn of thee solvent oil with the avy hydrocarbons and tarry residues below such a degree of concentration that upon further circulation and heating such solvent oil may take into solution the further high boiling point fractions produced from the crackable oil without permitting the heavy hydrocarbons to become too concentrated in the apparatus. If the solvent oil is permitted to become over charged with such heavy hydrocarbons deposition takes place as these heavy hydrocarbons take the brunt of the heat and unless held in solution by the solvent oil become further reduced to carbon. The degree of concentration, (of the solvent oil and high boiling paint fractions produced by the era ing sit the crackable oil,) which may be p mitted in the system without danger ofelepesiti-on will, of course, depend upon the oils charged into the system. as for example, the carbon residue test should not exceed ten times that in the charged oils.- This is merely an example and will vary with the oils.

In the cracking of certainv petroleum distillates there may be produced from the operation suflicient solvent or non-crackahle oil of unsaturated form to keep the solid hydrocarhons and tarry residues in solution so that no deposit will form on the metal surface of the heating element, in which case it is unnecessary to add asolvent or non-crackalole. oil from an outside source.

= vent or non-crackable oil tobe introduced ble oilinto such relatively.

plained.

l, therefore, do not limit myself to the use of a solfrom an outside source, since suflicient may be .produced in the operation when certain petroleum oils are used.

A certain amount of non-crackable or solvent oil pames oil with the solid hydrocarbons and tarry residues in solution, which is replaced from the storage as needed.

As an example of the proportion of oil to be treated with the solvent oil, I add one volume of the former to as much as three or five volumes of the latter in the a stem at any moment; and as an example 0 a desirable cracking pressure and temperature for" the oil to be cracked, I give 105 to 120 'pounds absolute and 7 45800 F. but it is to be understood that these proportions and the 7 boiling point oil may be used as the solvent oil provlded it is substantially unaffected at tion. a

By constantly feeding into the apparatus or system such a quantity of solvent oil and oil to be cracked as will maintaiii a substantially constant volume in the apparatus and maintain continuous cracking at substantially the determined pressure and temperature afsubstantially uniform fraction is continually produced during the operation of the ap aratus.

Wh' e I have thus referred and do hereafter refer in the claims to the solvent oil and the oil to be cracked as'two oils it will be understood that I do not limit my invention to the use of two distinct oils, but include as within my rocess and invention the crackin 'of any. oil which contains fractions, one 0 which will be cracked at a given pressure and temperature and another fraction which will be substantially unaffected by such pressure and temperature and which will act as a solvent oil as heretofore ex- It also is to be understood that my method is'not confined to the use of any particular solvent oil, the distillate from refractory California crude mentioned being given merely as anexample of a solvent oil relatively unaii'ected by the pressule and temperature required to crack the oil to be treated.

Finally, it is to be understood that my method isnot confined to its accomplishment the pressure and temperature of the operapoint fraction of aetroleum oil from a relatively higher boi ing point oil, which consists 1n continuously circulating through a closed system, conjointly with the oil to be cracke a solvent oil of lower boiling point thanthe oil to be'cracked and which solvent oil is practically unafi'ected at the tem rature and pressure required to crack sai first-mentioned oil, maintaining in said system a pressure and temperature required to crack said oil, continuously passing out of the system the low boilin point vapor from the cracked oil, where y the heavy derivatives from said cracked oil are taken into solution by said solvent oil, and discharging said solvent oilsolution as required to prevent deposition of carbonaceous matter in the system.

2. The improvement in cracking petroleum oils which consists in continuously circulatingthrough a closed system, conjointly with the oil to be cracked, a solvent oil of lower boiling oint than the oil to be cracked and which so vent oil is practically unaffooted at the temperature and pressure requlred to crack said first-mentioned, oil,

maintaining in said system a pressure and P temperature required to? crack said firstmentioned oil, continuously passing out of the system the low boiling pomt vapor from said cracked oil, and continuously removing from said system the resultant solvent 011 solution.

3. In the method of cracking petroleum oils, that step which consists in continuously circulating, conjointl with the oil to be cracked, a: solvent 0i ,under conditions of pressure and temperature adapted to crack only the first named oil, whereby the relatively high boiling point derivatives of crackin are carried in solution by said solvent oi said solvent oil being a lower boiling point oil than the oil to be cracked.

4. The process of producing a low boiling point fraction from a petroleum oil from a relatively higher boiling point fraction, which consists in continuously circulating through a closed system an oil under asubstantially uniform pressure and temperature adapted to crack a relatively high boiling point fraction of such oil but insufiicient to crack a lower boiling point fraction of such oil, utilizing such lower boiling'point fraction as a solvent in volume sufiiclent to dilute the higher boiling cracking to substantia y prevent further reduction thereof ultimately to carbon, continuously. withdrawing the resultant low boiling point vapor produced, maintaining a substantiall constant volume of oil in the system, an keeping the resultant solution by dilution and discharge from becoming sufiiciently concentrated tocause deposition in the system. 5. The roces's of producing a substantially uni orm low boiling point fraction from petroleum oil, which consists in rapidly continuously circulating an oil in a closed system, maintainin a substantially constant volume of oil in t e system, maintaining a substantially constant pressure and tem erature in the system, whereby a hi h boi ing oint fraction of such oil is, crac ed and a ower boiling point fraction of the ori 'nal oil is used as a 'solvent for the resu tant high boiling point derivatives of cracking produced from such first-named high boiling point fraction, continuously withdrawing the resultant low boiling point vapor, and keeping the resultant solution by dilution and discharge from becoming sufiiciently concentrated to cause deposition in the system.

6. The process of producing a low boiling oint fraction from a petroleum oil from a relatively higher boiling point oil, which oint derivatives of consists in continuously circulating throng):

a closed system, conjointly with the oil to cracked, a solvent oil of lower boiling point than the oil to be cracked and which solvent oil is practically unaffected at the temperature and pressure required to crack said first mentioned oil, maintaining in said system a pressure and temperature required to crack said oil, continuously passing out of the system the low boiling oint vapor from the cracked oil, whereby t e heavy derivatives from said cracked oil are taken into solution by said solvent oil, and keeping the resultant solution by dilution .with said solvent oil and by dlscharge of solution from becoming sufiiciently concentrated to cause the reduction to carbon of such heavy derivatives.

Signed at of December, 1919.

RICHARD W. HANNA. Witnesses:

Eusm, W. D. MASON.

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