US1922528A - Process for treating petroleum hydrocarbons - Google Patents

Description

was.

Aug- 15, 1933- A. G. DAvls I 1,922,528

PROCESS FORTREATING PETROLEUM HYDROCARBONS Filed Dec. Y 1o 1925 Patented Aug. 15, 1933 PROCESS Fon TREATING.

HYDRocARBoN PETROLEUM S V Albert G. Davis, Elizabeth, N. J., assigner, by

mesne assignments,

to Gasoline Products Company, Inc., Wilmington, Del., a Corporation of Delaware Application December I, 1925 Serial No. 74,507

4 Claims.

This invention relates to improvements in processes for treating petroleum hydrocarbons, and refers more particularly to processes for the production of products having the characteristics of gasoline and the like.. The system consistS primarily of a-double stage process, the cracking or conversion of the oil taking place in one portion of the system, While the distillation of the cracked products is effected in separate Stages directly connected to the cracking stages and separated therefrom by a pressure reduction means.'

The novelty in the invention lies primarily in the return of the incondensible gases withdrawn from the nal stage of separation, which gases are injected back into the fractionating stage to promote redistillation of the condensate and absorption of the lighter fractions of the oil from the reuxed material.

The single .figure is a diagrammatic side elevational view of the apparatus with parts in section and parts broken away.

Referring to the drawing, at 1 is shown a furnace in which are mounted the heating coils 2 connected by means of a transfer line 3 to a.

heavily insulated forged steel reaction chamber 4. The reaction chamber, in turn, is connected by a transferA line 5 in which is interposed a pressure reduction valve 6 to an evaporator 7. 'At 8 is shown a fractionating tower in the form of a bubble tower connected by a vapor line 9 to the top of the evaporator and having a vapor line 10 leading ofi:` from the-top thereof to a condenser coil 11 positioned in the condenser box 12. The discharge line from the condenser coil terminates in a pipe 13, directing the oil to a gas Separator 14. The gas separator is equipped with a liquid draw oif line 15 regulated by a valve 16 and a gas line 17 controlled by a valve I8. The gas line 17 is divided by T connection forming the line 18a controlled by a valve 19 which directs the gas from the system and a line 2O regulated by a valve 21 which is connected to the suction side of the pump 22 bymeans of. which the gas is discharged through the line 23 either directly back into the bottom of the bubble tower or it is circulated through a heater 24 by closing the valve 25 whereby the gas is heated to the desired temperature before its introduction or injectioninto the fractionating tower. The

evaporator 7 is equipped with a liquid levelv draw off line 26 controlled by a valve 27 through an automatic liquid level regulating device 28. The liquid withdrawn is passed through a cooling coil 29 `and thence vto storage through the lating device.

line`30. In a like manner, the liqid withdrawn from the fractionating tower through the line 31 is directed through the cooling coil 32 and thence i through the line 33 to a recharging stock tank or to storage.- Instead of cooling the condensate Withdrawnfrom the fractionating tower, it may be recharged directly to the heating coils for retreatment in the system. These connections have been eliminated for simplicityV but are easily made with the charging line.

In operation, the cracking stock is introduced from any convenient source through the line 34 and is charged by means of the pump 35 into the top of the fractionating tower, being circulated therethrough in a closed coil 36. The oil passes thence through the line '37 into the heating coils Where it is raised to a cracking temperature. The velocity of the oil through the heating coils is so regulated that the oil receives suflicient'heat therein to produce the desired 75 amount of conversion in the subsequent reaction stage but is not overheated to the extent that there is any substantial deposition of carbon in the coils. The highly heated oil is directedY thence through the transfer line 3 to the reaction' 30 chamber where the major tion takes place. l

Temperatures of from 550 to 1,000 F. are

maintained in the heating and reaction stages,

portion of the reacwln'le pressures are imposed suicient to pre- 35 ventany substantial vaporization ranging from 450 to 1500 pounds per square inch. The con` verted products are directed from the reaction stage into the evaporating tower through the line 5, pressure being reduced to substantially 9o atmospheric conditions at the valve 6.`

In the evaporating stage the lighter fractions will distill off, the unvaporized portions being automatically withdrawn by the liquid level reguprimarily of the heavier oils, such as fuel oil, which are cooled and directed to storage through the line 30. The overhead material passes off in vapor form through the line 9 and is introduced into the bottom of the fractionating tower tionation in the tower, the vapors pass overhead through the line 10 and are subjected to a final condensing action, being cooled as liquid distillate in the gas separator 14. The bottoms accumulating in the fractionating tower are automatically discharged either into the cooler and preheated 70 These drawn oi liquids consist 95 cooling,

2 to a recharging stock storage tank, or, without directly back into the heatingl coil. The incondensible gas taken off from the gas separator through the line 17 may be removed from! the system or portions thereof may be removed While the remaining gas is recirculated through the pipe 20 and pump '22 through the line 23 into the bottom of the fractionating tower where it is injected into the pool of oil accumulated therein. Under certain conditions it may prove to'be advantageous to preheat the gas priorto its injection into, the fractionating tower. For this'purpose, there is interposed in the line 23, a heating coil 23a positioned in a heater 24. This heater serves to raise the temperature of the recycled gases promoting re- -siderable "quantities of distillation of the lighter fractions densate on injection of the heated gases back into the tower.

It is a well known practice to inject incondensible gases, steam, hydrogen, oxygen or inert gas such as carbonic acid gas, into the vaporizing or reaction stage of the cracking system and heretofore steam has been injected intolthe fractionating stage of both a cracking Asystem and atmospheric distillation system to promote redistillation of the'low boiling point fractions. It is thought novel, however, to return the incondensible gases to the fractionatingstage and there inject them into the fractionating tower where they are combined With the vapors rising Furthermore, this practice. has given considerable satisfaction lboth vvhere through the tower.

the gases are heated and where they. are unheated, as they absorb from the condensate conthe lighter fractions which are separated out during the -fractionating of the vapors.

I claim as my invention: l. A process of converting petroleum hydrocarbons, comprising the steps of subjecting the oil to cracking temperatures and pressures, distilling off the lighter products, removing and fractionating the vapors, subjecting the still unfrom the con" condensed vapors to a final condensing action and separating the distillate from the uncondensible gas, returning said gas directly to the `fractionating stage and percolating it lthrough a pool of the condensate collected in the bottom of the fractionating stage. 2. A process vfor coverting petroleum hydrocarbons, comprising the steps of subjecting the oil to cracking temperatures and pressures, reducing the pressure on the oil and distilling off the lighter products and subjecting the evaporated products to fractionation, passing uncondensed vapors to a condensing stage, separating the distillate from the uncondensable gases, passing the gas to a heating stage and thereafter returning it directly to the fractionating stage.

3. A process of converting petroleum hydrocarbons comprising the stepsl of subjecting oil to cracking temperatures and pressures, reducing the pressure on the treated oil and distilling off the lighter products, fractionating the evolved vapors in a fractionating stage, condensing the condensible components of said vapors and returning the incondensble components into a .pool of condensate in th'efractionatin'g stage.l

4. A process for cracking hydrocarbon oil comprisingmaintaining the hydrocarbon constituents under cracking conditions of temperature and pressure in a still, removing vaporous constituents from the still, subjecting the vaporous constituents to dephlegmation in a zone apart from the still, subjecting the dephlegmated vapors to condensation, collecting the resulting condensate and uncondensable gases, raising the temperature of portions of the uncondensable'gases produced in the processvto.

above the temperature of the vapors entering the dephlegmating zone and returning the same directly to the dephlegmating zone to facilitate the release ofrgasoline-like fractions from the condensate separated from the vapors in the dephlegmating zone.

ALBERT G. DAVIS.

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