US1646543A - Oil-cracking process and apparatus - Google Patents

Description

1927' w. c. KlRKPATRICK OIL CRACKING PROCESS AND APPARATUS Filed Alix. 27, 1925 2 Sheets-Sheet 1 l W a Oct. 25, 1927;

w. c. KIRKPATRICK OIL CRACKING PROCESS AND APPARATUS Filed Aug. 2'r,' 1925 2 Sheets -Sheet 2 35 drawings, in which Patented Oct. 25, 1927. I

"UNITED STATES WILLIAM C. KIRKPATRICK,

PATENT orFicE.

OF ALHAMBRA, CALIFORNIA, .ASSIGNOR TO NATIONAL TION OF NEVADA.

OIL-CRACKING PROCESS AND APPARATUS.

Application filed August This invention hasto 4 apparatus for cracking hydro-carbon oils, and without the purposes of the invention being limited thereto, its chief object may be stated to include the provision of oil cracking apparatus and a process or method of cracking-therein whereby the apparatus will continuously function, without interruptions, to produce a high quality of low boiling point hydrocarbons, and without the production of any large proportion of fixed gases. I

Several 1 different processes hydro-carbons to low boiling point hydrocarbons have been previously known in the art; but one of their outstanding short-comings has been the production of carbonaceous deposits in such large quantity or in such physical form as to make difficult the discharge of such deposits from the cracking still, usually necessitating temporary shut down of the still for cleaning. It is one of the objects "of this invention to provide such form of apparatus and process as to give a comparatively finely divided and dry carbonaceous deposit, and to provide easy means for removal of the depositwhile the still is continually operated.

How these and other objects are accomplished will be best understood from the f lowing detailed description of preferred forms of apparatus and of the process carried on in such apparatus, reference for that purpose being had to the accompanying of cracking Fi 1 is a verticle longitudinal section showing one form of my still and its accompanying apparatus; 1

Fig. 2 is a somewhat enlarged vertical longitudinal section of the stillitself.

Fig. 3 is a vertical longitudinal section of another form of still and its accompanying furnace.

Fig. 4 is an enlarged longitudinal section of the still of Fig. 3; and

Fig. 5 is a diagram in the nature of a flow-sheet illustrating the complete apparatus for carrying out my process.

' I refer first to Fi-g. 5 in order to give a general description of the process as a whole.

do with process and 27,1925. Serial No. 52,749.

It will be noted that the original hydrocarbon oil is fed through pipe 10 to a heat exchange 11, the relationshipof which to the cracking still Will be hereinafter explained. From this heat exchange the warmed oils 6 pass through pipe 12 to a low pressure pump 13, by which they are pumped through pipe 18 throughheater 14 under a pressure-substan tially just enough to cause them to flow at sufiicient speed. Such a heater as illustrated at 14 is usually composed of a number of tubes connected at least partly in parallel relation so that the resistanceto flow through the heater is comparatively small; and,the oil having been preliminarily warmed in heat exchange 11 no great pressure is necessary to flow the oil through heater 14. From heater 14 the heated oil goes through pipe 15 to a high pressure pump-16 and thence through pipe 17 to the cracking still '18. The gases and vapors generated in the cracking still pass out of it through wt or outlet pipe 19 to the heat exchange 11, rst spoken of, Where the vapors and gases give up a part of their heat to the original oils. From the heat exchange the vapors and gases flow through pipe 20 to a condenser 21 whence the condensate is taken on at 22 and the separated gas goes to a. gas container 23. p This gas, or any other suitable fuel, may be 80 used at the burner 24 for firing the furnace of the cracking still.

In the form of cracking still shown in Figs. 1 and 2 the still proper is composed of a vertically arranged cylindrical shell 25, standing in a furnace chamber 26, which is provided with a partition wall 27 of some Y suitable heat resistant material, of which the furnace walls are also composed. This central partition 27 forces the heated products of combustion from combustion chamber 28 to pass first downwardly in contact with one-half, or substantially one-half, of the cylindrical still, then to pass under the lower end of the partition and upwardly in direct contact with the other part of the cylindrical still. The gases of combustion pass out finally through opening 29 and pass directly into the heater 14, and thence out of the apparatus through stack 30. Heater 14 may 1 be a heat exchange of a well-known ty embodying a plurahty of cross tubes 31, t rough which the oil flows.

The furnace structure in which still 18 is set has an offset combustion chamber 28, into which burner 24 throws its fuel either in admixture with airQor air is admitted in any ordinary waV. Combustion taking place in chamber 28. the products of combustion pass through the brick checker-work 35. wherein by intimate intermingling' any unburned fuel is burned and all the products of combustion are made uniform in temperature. The heated products of combustion that then pass over wall 36 into the furnace chamber 26 are as nearly uniform in temperature as may be. These provisions make it possible to heat the cracking still uniformly to a high temperature without anv danger of burning or otherwise deteriorating the still either by too high heating in spots jected to oxidizing or reducing gasesfat too high a temperature. The high temperature thus maintained uniformly in the still is one of the things that enables me to obtain the uniform and eflicient cracking action within it. However, when I refer to uniform temperatures within the still, I the interior of the still, as a whole is .at the same temperature throughout; but that there are no irregularities of temperature between different places in the still. As a matter of fact, the upper end of that side of the still, shown at the right hand in Fig. 1,

will usually be somewhat hotter than the op-- posite side of the still, although there may not be much difierence in temperature. This difference in temperature may be due to the fact that the hot gases of combustion come first into contact with the right hand side of the still and that the incoming oils are injected into the left hand side of the still. Thus the incoming oils in passin from the left hand to the right hand side 0% the still, as will may pass into zones of somewhat increasing temperature; but the temperature maintained at the point of injection of the oils isalways high enough to accomplish the operations hereinafter described. v

The cylindrical still also has in its interior a partition wall 40 extending from its upper end to a point near its lower end. and there it is preferablv formed in such a manner as to leave a relativelv restricted opening 41 between its lower end and the wall of the still for vapors and gases to pass into the space at the right of wall 40. In the form shown in Fig. 2 this interior partition 40 is spaced so as to make a larger than at its right: but this is not necessarily the ease. At the upper end of the right hand chamber of the still the vapor and gas outlet pipe 19 leads ofi' while the oil pressure pipe 17 leads to a small orifice nozzle or by being Sub:

do not mean that b be hereinafter explained,

chamber at its lefttively dry particles.

, which in turn lead to two carbon pots or receptacles 48. which have valve-controlled outlets at 49. It is, of course, obvious how either one of the valves at 47 a may be opened while the other is closed, so that the carbonaceous depositsmay be drained into onecar b'on pot..while the other is being drained through its drain valve 49.

In applying: my process to. an average hydro-carbon oil or petroleum derivative of whatever nature, I find that it is-advantageous to heatthe oils in heater 14 toabout 500 or 600 F., while they are still under low pressure-a pressure that may be called substantially atmospheric. Such temperature of heating varies with the oil being treated, but in any case it is preferably a temperature that is as near as may be, in practical operation, to cracking temperature,

ut still not sulficient to crack the oils. I Having thus been heated to this relatively high but non-cracking temperature, the oils are then taken by high-pressure pump 16 and put under a pressure of from 600 to 700 pounds per' square inch, so that the oil deivered 'to spray nozzle 42 is at a high pressure and also at the high temperature stated. The still and its furnace are operated so as to maintain the still uniformly at a temperature of approximately 780 F., or more, the

temperature between the point where the oil mtroduced'and the point where the is first vapor emerges is comparatively smal1a difference of a few degrees. The oils upon being introduced through the small orifice nozzle 42 under the high pressure maintained by h gh pressure pump 16 are sprayed and atomized into a very fine mist; so that they almost instantaneously come into very finely divided and intimate contact with the body of vapors in the still, which vapors are maintained at the temperature stated. The result of this intimate and practically instantaneous sub ection to a higher and cracking temperature, pressure'upon the oils, causes an almost instantaneous cracking transformation andv causes a carbonaceous deposit to be dropped out of the oils in finely divided and compara- This finely divided carbonsdrops to the bottom of the still where and the simultaneous release of I P oduce the particular desired re ne ates it easily passes out into one or the other of the carbon pots. After the practically instantaneous cracking action that takes place upon introduction of the oil, the resultant vapors are, of course, further subjected to the temperature and pressure conditions within the still during the time that they flow down through the left hand compartment of the still and up through its right hand compartment. to the outlet pipe 19. The valve 19 on this outlet pipe may' be a valve of any suitable type, operated in any suitable manner, and it is regulated so as to maintain constantly within the still a pres sure of from 150 to 200 pounds per square inch-a comparatively low pressure as cracking operations go. Maintaining thus a given ressure within the still, the time element involved in cracking operations withm thestill depends upon the quantity of oil put through the still in unit time; and this may be regulated by regulation of the high pressure pump and other parts of the circulating the point of injection.

' of injection,

7 conditions will have apparatus, and corresponding regulation of the outlet valve on the still to maintain the The vapors during their treatment in passing heat and pressure be subjected to fun through the still ma ther reactions; but t e major crackmg reaction takes place practically instantaneously upon introduction of the oils to the still.

In the form of still apparatus shown in Figs. .3 and 4, the still proper 18 is arranged horizontally; and in order to carry the carbo'naceous deposit to the end of the still, away from the oil injection end, I provide a spiralscraper 50 mounted upon a shaft 51 (a spring spiral mounted at its ends on the shaft and expanding into contact with the still wall) and rotating to carry the carbonaceous deposit to the outlet 46*. The oil pressure pipe 17 leads to the small orihce nozzle 42 at one end of the still, and the coneshaped spreader 43-may be carried by the end of shaft 51. The vapor outlet 15 at 19. It will be seen that in either form of still the oils are injected at one end, the carbonaceous deposit is taken out at the lower part of the still at a distance from the point and the vapors are taken out of the upper partof the still at a distance from For the horizontal still, the furnace arrangement is modified merely to-suit the position of the still, the oflset combust on chamber 28 and brick checker-work 35 being used, and the furnace chamber immediately surroundin the still being divided longitudinally of t e still-into two compartments by thelongitudinal partition 27, as before ex plained. a

It will be appar nt to those skilled in the, art that various modifications of operat ng to be made in carry ng out my process upon differing types of oils;

eluding carbons are forced at the other end of the chamber.

' jecting them under and, therefore, stood that the temperatures and pressures here given are indicative only and not necessarily specifically limitative. Likewise various modifications in the apparatus will suggest themselves to and I, therefore, do not limit my invention except as expressly so limited in the following claims.

I claim: A

l. The process of cracking high boiling point hydro-carbons to lower boiling point hydro-carbons, that includes heating the hydro-carbons to a temperature of about 500 to 600 F., under a low pressure, then placmg the heated hydro-carbons under a pressure of about 600 to 700 pounds per square inch, delivering the hydro-carbons at that pressure to a still in which the pressure is maintained at about 150 to 200 pounds per square inch and in which a temperature of about 780 F., or more is maintained, atomizing the hydro-carbons at their point of delivery and pressure release intothestill, and taking off from the still the resultant carbonaceous deposit and the vapors and gases evolved.

2. Hydro-carbon cracking comprising an expansion cracking chamber, means for heating hydro-carbons and injecting them under high pressure to the expansion chamber, the injecting means inan atomizing nozzle with'a small orifice through which the hydro-carbons are forced under high pressure into the expansion chamber, means to maintain her at cracking temperature, means to maintain in the chamber a pressure substantially lower than that under which the hydrointo the chamber, a longitudinal partition extending within the chamber from one end to a point near the other, the hydro-carbon injecting nozzle being at one side of the partition at the first mentioned end, a valve controlled gas and vapor outlet at that same end at the other side of the partition, and abarbon outlet 3. Hydro-carbon cracking -ap aratus, comprising an expansion cracking c amber, means for heating hydro-carbons and inhigh pressure to the expansion chamber, the injecting means including an atomizing nozzle with a small orifice through which the hydro-carbons are forced under high pressure into the expansion chamber, means to maintain the chamber at cracking temperature, means to maintain in the chamber a pressure substantially lower than that under which the hydro-carapparatus,

those skilled in the art the chamv bons-are forced into the chamber, a longitudinal partition extending within the chamber from one end to a point near the other. the hydro-carbon injecting nozzle being at one side of the partition at the first 4: memes v mentioned end, a valve controlled gas and first into direct contact with that half of the 1 vapor outlet at that same end at the other expansion chamber that is at the outlet side side of the partition, and a carbon outlet of the partition therein, and then into diat the other end of the chamber, a furnace rect contact with the other half of the exenclosing the chamber, a combustion champansion chamber.

her communicating with the furnace and In Witness that I claim the foregoing I 15 means for burning fuel in the combustion have hereunto subscribed my name this 21st chamber, the furnace being arranged so that day of August 1925 the products of combustion are conducted WILLIAM C. KIRKPATRICK.

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