US1923271A - Process and apparatus for fractionating petroleum - Google Patents

Description

Aug. 22, 1933.. w, w, LowE Er AL PRocEss AND APPARATUS Fon FRACTIONATING PETROLEUM Filed May 21, 1924 Patented Aug. 22, 1933 `PROCESS AND 4APPARATUS FOR FRACTION- ATING PETROLEUM William W. Lowe, Westfield, N. J., and Henry N. Lyons, Okmulgee, Okla., assignors to Doherty Research Company, New York, N. Y., a Corporation of Delaware Application May 21, 1924. Serial No. 714,7 95

11 Claims.

This invention relates to the production of merchantable products from crude petroleum.

It is well known that at present a common method of treating crude petroleum oils com- 5 prises fractionating the crude by passing .it

through a battery of stills in series, each successive still in the series being kept at a higher temperature than the preceding one. This fractionating process yields gasoline, kerosene, gas

oil, lubricating oils and fuel oil. However, the gas oil is now commonly crackedfor gasoline, and the lubricating distillate is commonly rerun and sometimes cracked. Moreover, the gasoline obtained from cracking the gas oil, commonly needs to be rerun. The rerunning of the gasoline and lubricating distillates is expensive in both fuel and labor while the first cost as well as interest and upkeep charges are also all high.

It is the primary object of the presentV invention to device a process for distilling crude petroleum and an apparatus for practising the samev whereby thecrude shall be converted into marketable products at better commercial advantage than is now the case. v 4 A second object of the invention is to greatly reduce the amount of fuel required in the complete process of making marketable products from a given crude oil. Y

It is one of the advantages of the'present in vention that it produces severalV products including gasoline without the necessity of rerunning either.

Further objects and advantages of the present invention will be apparent to those skilled in the l'35 art from the following detailed description taken in connection with the accompanyingl drawing, in which The gure is an illustration partly diagrammatic in character of an apparatus according to the invention and adapted for carrying out the process of the invention.

. Inthe drawing 10 is a pipe through which cold crude is introduced into the system.. Pipe V10 connects withY a heat interchanger 12 through which the crude passesand in which the crude is heated by thermal heat units derived from hotl fuel oil being discharged from the system. The preheated crude from heat interchanger 12 passes through pipe 14, pump 16 and pipe 18 to topping tower 20 within which the crude is intimately mixed with liquids, vapors, and gasesv from a pressure cracking operation constituting a subsequent step Aof the process. The heat obtained by the crude from heat interchanger 12 .5 addedto that delivered to the crude in topping tower 20 by the pressure distillate drives off the light gasoline from tower 20 through pipe 22 to condenser 24. Topped crude and heavy ends of pressure distillate pass ofi at the'bottom of tower 20 through pipe 26, trap 28, pipe 30 and 60 tank 32 to pump 34:. Pump 34 forces the topped oil and heavy ends through pipe 36 to pipe still 38. Still 38 is heated by furnace 40 preferably ofv the oil burning type. In still 38, the oil is heated to the temperature necessary to vaporize the gas oil fraction of the crude. This temperature is of course, sufficient to vaporize also heavy gasoline and kerosene. .The oil and vapors from still 38v pass through pipe 42 into separator 44 Where the fuel oil separates from the vapors of heavy gasoline, kerosene and gas oil. The vapors in separator 44 pass orf at the top thereof through pipe 46 while the liquid fuel oil passes ofi at the bottom through pipe 48 to heat exchanger 12 whence it passes to storage through pipe 50.

Vapors from separator 44 pass through pipe 46 to fractionating tower or bubble Vcap column 52 where the heavy gasoline is separated from the gas oil and kerosene. Vapors of heavy gasoline from tower52 pass out at the top of this tower 80 through pipe 54 to condenser 55; Liquid gas oil and kerosene leave tower 52 at the bottom of the tower and pass through pipe 58, trap 60, pipe 62 and tank 64 to pump 66. Pump 66 forces the gas oil and kerosene through pipe still 68 85 and pipe '70 to fractionating tower or bubble cap column 72. In passing through still 68 the oil is heated to the temperature necessary to vaporize the kerosene fraction butV as little as possible of the gas oil traction. The kerosene vapors pass out at the top o1" tower 72 through pipe '74 to condenser 76. Vapors of gas oil are thrown back into tower 72 and pass out oi the bottom y of tower '72 in liquid form and then through pipe 78, trap 79, pipe 8O to tank S2. Fromtank 82 95 gas oil is forced by pump Sli through pipe 86 to a pipe still 88, heated by furnace 89. In still S8 the gas oil is heated under pressure to cracking temperature but the oil is forced through the coils of the still at a rate preventing any substantial cracking in the still. The oil passes from still 88 through pipe 9G to a cracking and separating chamber 92 under the same pressure as still 88 and Within which cracking occurs forming vapors of pressure distillate, gases and heavy liquid bottoms. Vaporsand gases from chamber 92 pass out at the topof this chamber through pipe Qlto the topping tower 29. In pipe 9/1 is a pressure reducing Valve 96 for maintainingthe desired pressure on chamber 92 and still 88. A 7-10 also low and the investmentis moderate.

by-pass 97 is provided between pipes 94 and 22 and three hand valves 98, 98, 98 are so placed that vapors from chamber 92 may be sent directly to condenser 24 if desired.

Furnace 89 for still 88, as well as furnace 40 of still 38, are preferably fired with fuel oil, at least in great measure. Uncondensable gases passing through condensers 24, 56 and '76 may also be used in furnaces 40 and 89 insofar as they are not more valuable for the manufacture of by-products than for fuel. Still 68 is not separately fired but is heated by gases delivered to it from stills 38 and 88 through flues 100 and 102 respectively. After passing through still 68 the iiue gases pass off through stack 104.

'Ihe operation of the apparatus according to the invention will be apparent to those skilled in the art from the foregoing description. For convenience of reference, the method of operation is summarized as follows:

Incoming cold crude petroleum is preheated by heat interchange with outgoing hot fuel oil. The preheated crude then goes to a topping tower where it is mingled with highly heated vapors of pressure benzine derived from a subsequent step in the process. In the topping tower, light gasoline is vaporized and driven off to a condenser. Material not vaporizing in the topping tower is heated in a still to a temperature high enough to vaporize gas oil and lighter fractions. The vapors mixed with unvaporized fuel oil pass from the first still to a separator where the fuel oil isthrown out of the vapors and passes to the heat interchanger for preheating the incoming crude. Vapors from the separator pass to the first fractioning tower from which vapors of heavy gasoline pass over to a condenser. Vapors of gas oil and kerosene, however, are thrown back in the first fractionating tower and the mixed liquid from the bottom of the first fractionating tower is collected and pumped through a second pipe stillwhere the kerosene is vapori'zed. From the second pipe still, the vapors pass to a second fractionating tower in which the gas oil is thrown back, the kerosene vapors passing over into a condenser. Liquid gas oil from the bottom of the second fractionating tower passes through a third pipe still in which it is heated to cracking temperature while under pressure. From the third pipe still vapors under pressure pass to a cracking and separating 'chamber where the cracking occurs and heavy bottoms are separated from the gases and vapors of the cracking step. These gases and vapors then pass through a reducing valve into the topping tower where their contained heat is chiefy instrumental in driving oif the light gasoline from the preheated crude which has been preheated in a heat interchanger by heat from the fuelv oil. VVVapors from the topping tower pass to a .condenser for light gasoline.

The second still encountered by the oil is heated by the flue gases from the first and third stills, thus economizing fuel.

By the method and apparatus previously described, it is possible to distil vand crack a given crude petroleum with a minimum expenditure for fuel. When using only fuel oil in addition to the waste gases from the process, the number of barrels of fuel oil required including fuel for pumping and so forth, is approximately five per cent of the number of barrels of crude introduced into the system. The labor costs in treating crude petroleum according to the present invention are Furthermore, the products formed yield the highest return from a given quantity of oil such as Kansas crude in the usual state of the market for rened petroleum products.

The present invention is not in general limited toparticular forms or types of apparatus for performing the functions set out herein. In particular, it is not limited to both cracking the oil from the third still and separating out heavy bottoms in a single cylinder or tower.

Having now described our invention and in what manner the same is to be performed, We

claim- A l. The process of refining crude oils, which comprises topping the oil to be treated to remove lightl gasoline, passing the topped oil through a heating zone to vaporize heavy gasoline, kerosene yand gas oil constituents therefrom, fractionally condensing the resulting vapors whereby said heavy gasoline is recovered separately from a kerosene-gas oil condensate, heating the condensate containing kerosene and gas oil to vaporize said kerosene and separately recover the same, cracking said gas oil under superatmospheric pressure to produce lighter oils therefrom and passing the vapors formed in said cracking through said crude oil to carry out said topping.

2. The process of refining crude petroleum which comprises cracking a gas oil under superatmospheric pressure and high temperature to produce lower boiling vapors therefrom, preheating crude petroleum then topping the same by contacting it with'said vapors, heating the resulting topped petroleum to vaporize heavy gasoline, kerosene and gas oil therefrom, separately recovering said heavy gasoline by condensing out said kerosene and gas oil constituents from the mixture of vapors resulting from said heating, vaporizing the kerosene from the resulting mixture of kerosene and gas oil condensate and using the gas oil from the mixture in the said cracking.

3. The process of fractionally distilling crude mineral oils, which comprises passing a gas oil under superatmospheric pressure through a heating Zone and into a cracking zone, heating the said gas oil to a high temperature and maintaining the same under a superatmospheric pressure in said Zones, passing vapors formed in said cracking Zone into Contact with crude oil to be distilled whereby the light gasoline content of said crude oil is removed and the heavier fractions of said vapors are condensed, heating the resulting mixture of topped crude oil and said heavier fractions of crackedoil to a temperature sufficient 'to vaporize gas oil and lighter oils contained therein, separating the gas oil from said lighter oils and passing it into said heating zone.

4. The process of fractionating crude petroleum oils, which comprises preheating the crude oil to be fractionated, vaporizing light gasoline therefrom, heating the topped crude oil to a temperature sufficient to distil off all remaining fractions lighter than the fuel oil fraction whereby said fuel oil is separated from the distilled fractions, passing said fuel oil While hot into heat exchange relation with said crude oil to perform said preheating, fractionally condensing said distilled fractions into heavy gasoline and a mixture of kerosene and gas oil fractions, separating the gas oil from the kerosene in said mixture, cracking the gas oil fraction under superatmospheric pressure at a high temperature, and passing the vapors therefrom into contact with said preheated crude oil to vaporize said light gasoline.

5. The process of fractionating crude petroleum oils, which comprises passing the oil to be treated in heat exchange relation with vapors from a cracking chamber whereby a mixture of reflux condensate and topped crude oil is produced passing said mixture through a heating zone and into a vaporizing zone where a liquid fuel oil residue separates, withdrawing vapors from said vaporizing Zone, separating a gas oilV fraction therefrom, heating said fraction to a cracking temperature under superatmospheric pressure and passing it chamber.

6. An apparatus for treating cils, comprising a closed series of units,each unit of the series comprising an oil heater, a vapor fractionating tower and a final condenser, means for passing oil from the fractionating tower of each unit into the oil heater of the next succeeding unit, and means for introducing oil to be treated into the fractionating tower of one of said units.

'7. In the process of fractionally distilling crude petroleum oils in which the crude oil to be distilled is topped by being passed in direct contact with hot cracked vapors in a dephlegmating zone and from which a mixture of topped crude oil and reflux condensate is withdrawn, the improvement which comprises, further heating said mixture while hot by passing it through a conned heating zone in which the mixture is heated to a temperature adapted to vaporize substantial portions thereof, discharging the thus heated mixture into a vapor-liquid separating zone, withdrawing unvaporized residue oil from said separating zone, cracking a portion of the constituents vaporized from said mixture by heating the same to a high temperature while conducting the same through a conned heating zone, and contacting the hot cracked vapors resulting from said cracking with said crude oil in said dephlegmating zone.

8. The combined process of fractionating and cracking petroleum oils, which comprises heating crude oil containing gasoline and introducing it into a tower in contact with hot cracked vapors containing gasoline constituents, conducting the gasoline vapors from said tower for condensation, passing unvaporized oil and condensate from said tower through a heating zone and theninto an enlarged chamber wherein portions of said mixture are vaporized, passing vapors from said chamber into a second fractionating tower wherein a reflux condensate is produced, heating and cracking condensate from said second tower to produce hot cracked vapors therefrom, and passing the resulting cracked vapors into said first tower to be contacted with said crude oil.

into said crackingr 9. The process of treating petroleum, which comprises distilling crude oil containing gasoline in a zone of relatively low pressure, drawing off the lighter components of said oil in the form of vapor from said zone, pumping the heavier liquid components of said oil from said zone and forcing the same in a restricted stream through a heating zone and then into a second vaporizing zone, heating the said liquid components to a temperature sufilcient to effect vaporization of only the lighter constitutents of said liquid upon being discharged into said second zone, removing vapors from said second zone to produce distillates therefrom, forcing distillate formed from said vapors under superatmospheric pressure through a cracking still and then into an enlarged chamber, conducting relatively light vapors from said chamber into the rst mentioned zone, and passing them therein countercurrent to said crude oil.

l0. The process of treating oils, which comprises cracking a petroleum distillate by heating it to a high temperature under superatmospheric pressure in a cracking zone, passing cracked products from said zone into a zone of lower pressure wherein said cracked products are mixed and intimately contacted with crude oil containing gasoline, thereby to cool said products and vaporize the lower boiling constituentsV of said crude oil, subjecting the combined vapors to refluxing and final condensation, fractionating the mixture of topped crude oil and high boiling point cracked products from said low pressure zone into fuel oil bottoms and a plurality of distillates having different boiling points, and using one of said distillates for cracking in said cracking Zone.

l1. The process of refining crude petroleum, which comprises cracking a gas oil to produce lower boiling point vapors therefrom, topping crude petroleum by contacting the same with said vapors, heating the resulting topped petroleum to vaporize heavy gasoline, kerosene and gas oil therefrom, separately recovering Ysaid heavy gasoline by condensing out said kerosene and said gas oil constituents from the mixturesV Lib

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