US1799530A - Process for cracking oil - Google Patents

Description

April 7, 1931- R. T. POLLOCK v 1,799,530

PROCESS FOR CRACKING OIL Original Filed Nov. 24, 1920 Far lace Patented Apr. 7, 1931 ROBERT T. POLLIOOK, OF NEW YORK, N. Y.,

PATENT OFFICE ASSIGNOR TO UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA lPROCESS FOR CRACKING OIL Application filed November 24, 1920, Serial No. 426,313. Renewed March 24, 1927.

This invention relates to improvements in a process for cracking oil and refers more particularly to a continuous process in which the raw oil and reflux condensate are introduced as charging stock into the heating zone.

The object of the invention is to provide a process and apparatus in which the charging stock consists of regulated proportions of reflux condensate and raw oil, the proportion being regulated through an orifice valve. In this process, the charging stock is at all times kept out of contact with the carbon in the expansion or vapor chamber. The temerature of the dephlegmator is regulated y water or other fluid while the raw oil is preheated and acts as the cooling medium in the final condenser. The reason for this is that more raw oil is required to control the temperature of the dephlegmator than is used in the system. Less cooling medium is required in the final condenser and moreover, the vapors which reach the final condenser are at a lower temperature than in the dephlegmator.

As a feature of the invention the oil is subjected to diflerentialpressures in various parts of the system. The reflux condensate and raw oil are thereby positively delivered 80 by pump pressure to the heating coil.

In the drawing, the single figure shows a view, partly in side elevation and partly in vertical section, of my improved apparatus; the view being somewhat diagrammatic.

Referring in detail to the drawing, 1 des- "ignates the furnace, provided with the stack- 2, and burner 3. In this furnace is mounted the heating coil 4, which in the present instance takes the form of a closed coil, as for example, 4" pipe, although the form of this heating coil may be varied. The outlet side of the coil 4 is connected by transfer line 5 having reducing valve 6 to the upper portion of an expansion or vapor chamber 7 This expansion or vapor chamber 7 may take the form of a large vertical drum or cylinder. It is provided with a liquid residue drawoflt' pipe 8 controlled by throttle valve 9; both the coil and expansion chamber are equipped with pressure gauges 10 and 11. The expansion chamber is provided with the vapor outlet pipe 12 controlled by throttle valve 13 and leading to the lower end of dephlegmator 14, which dephlegmator is provided with a spiral baflle member 15. This dephlegmator 14 is provided with a trap 16, the bottom of which is connected to the reflux condensate pipe 17 having throttle valve 18 leading back to the main feed line 19. The lower end of the pipe 17 is connected to the pipe 19 through a manually adjustable orifice valve 20, the arrangement being such that the orifice can be adjusted so as to feed only a regulated quantity of reflux condensate to the feed line 19. The pipe 17 is of sufficient capacity to take care of any excess reflux condensate. The upper part of the dephlegmator is provided with a vapor outlet pipe 21 having throttle valve 22 connected to the upper part of the final condenser 23.

Referring back to the dephlegmator 14, the oil chamber is formed by the partitions 24 and 25 forming the upper and lower water chambers 26 and 27 connected to each other by a series of water tubes or ipes 28. Water is fed through-these pipes y means of the pump 29,.delivery line 30, return line 31,

Water cooler 32 and line 33 leading to the M inlet side of the pump. A water leg 34 may also be provided as shown. The water circu lating system is provided with the throttlevalves 35, 36, 37 and 38. The arrangement is such that the temperature of the dephlegmator may be maintained at any desired temperature by the water circulating system, thus insuring of close control of the reflux condensate and making the dephlegmator independent of' changes in weather conditions,

due to drops or rises in temperature, rain 01" change in wind velocity, all of which afiect dephlegmation and thus the entire system.

Continuing the description of the appae ratus, thus final condenser 23 is provided with the partition members 39 and 40, forming the upper vapor chamber 41 and oil chamber 42 connected by means of the series of tubes 43. The lower chamber 42 is connected by pipe 44 having throttle valve 45 to receiver 46. This receiver 46 'has pressure gauge 47, liquid level gauge 48, drawofi pipe 49 having throttle valve 50 and as outlet pipe 51 having throttle valve 52. pressure gauge 53 is provided for the dephlegmator and a pressure gauge 54 for the vapor chamber of the condenser. In the compartment formed between the two partition members of the condenser is mounted a spirally formed bafiie 55. Raw oil is introduced into this chamber through the feed line 56 having a throttle valve 57 by any suitable pump, not

shown, and is caused to pass down the baflies and the preheated oil is drawn ofi through the line 58 having throttle valve 59 connected to the main feed line 19. A pump 60 may be interposed in the line 17 if desired.

In view of the fact that the system is operated under difierent pressures, a pump 61 is interposed in the feed line so as to be able to force the charging stock composed of the reflux condensate and raw oil into the heating coil.

The process is operated as follows: Raw oil, as for example, fuel oil or heavy Mexican or California crudes is continuously fed through the raw oil line and thence through the condenser where after the system is operating, it is preheated. From the lower part of the condenser, the raw oil passes into the main feed line where it meets and is mixed with the reflux condensate. The raw oil, preferably in liquid phase and heated to a temperature of say, 650 degs. to 750 degs. F. is delivered to the expansion chamber, where vaporization takes place. The residue containing the precipitated carbon is drawn oflI' continuously out of the system. The vapors pass through the dephlegmator which -is maintained through the water circulating system at any predetermined temperature, say 420 dogs. F.; all the vapors which will condense a ove this temperature are drawn ofi as reflux condensate and fed back through the system. Vapors having a lower boiling point than this pass to the final condenser where'they are collected in the receiver. The raw oil going in serves to condense the final vapors and the vapors also act as a preheater for the raw oil.

It is to be particularly noted that by regulating the orifice valve in the reflux condensate return line, regulated quantities of reflux relative to the amount of raw oil can at all times be fed throu h the system. For

example, the orifice may e so regulated that the percentage of reflux will be for example, say, four parts of reflux to one part of raw oil; this rcentage, of course, can be varied both with the character of the oil and the end point product desired. By means of the present process, from 35% to 40% of the entire raw oil may be converted into .420 degs. end point gasoline, which end point, of course, may be varied if desired.

The entire system may be operated under a differential pressure, which may be accomand the dephlegmator and condenser and receiver at atmospheric pressure or at a reduced pressure of say, pounds.

I claim as my invention:

1. A process for cracking oils, consisting in passing the oil through a heating zone and thence to an expansion chamber, taking the vapors fromthe expansion chamber and sub-' jecting them to a reflux condensation in a dephlegmator, in cooling the vapors in the dephlegmator by a regulatable supply of cool liquid, in leading vapors from the ephlegmator to a condenser, in supplying raw oil to the condenser to condense the vapors and preheat the raw oil, and in mixing the preheated raw oil with the reflux condensate from the dephlegmator and leading the mixture free from unvaporized residue under pump pressure to the heating zone, main-. taining a pressure substantially above atmospheric on the heating zone and substantially less pressure on the expansion chamber, dephlegmator and condenser.

2. A process for cracking oils consisting in passing the oil through a heating zone, and thence to an expansion chamber, taking off the vapors from the expansion chamber preheated raw oil with {a predeterminedquantity of reflux condensate, and in forc ng the mixed oils free from unvaporized residue under pressure through the heating zone,

maintaining a pressure substantially above atmospheric on the heating zone and materially reducing said pressure so as to maintain the expansion chamber, dephlegmator and condenser under a less pressure.

3. A process for cracking oils comprising passing the oil through a heating zone and thence to an expansion chamber, taking vapors from the expansion chamber and subjecting them to reflux condensation in a dephlegmator, cooling the vapors in said dephlegmator by a regulatable supply of cool liquid, leading vapors from the dephlegmator to the condenser, supplying raw oil to the condenser to condense the vapors and preheat the raw oil,- mixing the perheated raw oil with the reflux condensate from the dephlegmator, supplying the mixture under a pump pressure directly to the heating zone without prior admission to said expansion chamber and maintaining a regulated pressure above atmospheric on the oil undergoing treatment in the rocess.

ROB RT T. POLLOCK.

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