US1900174A - Hydrocarbon oil conversion - Google Patents

Description

O, H, FAlRCHlLD HYDROCARBON OIL CONVERSION Mamn F?, 19.33%@

Original Filed May 16,

@fear/ ZUG@ zz 655 s through theV initial heating coil. '35

Patented Mar. 7, 1933 UNITED STATESA OSCAR H. FAIRCHILD, OF CHICAGO, ILLINOIS, ASSIGNOR TO UNIVERSAL OIL PRODUCTS PATENT OFFICE COMPANY, OF CHICAGO, ILLINOIS,A CORPORATION OF SOUTH DAKOTA I nrnnoonmso N1oITi-k CONVERSION Continuation of application Serial No. 191,676, :filed May 16, 1927. This application led April 24,`

This application isk a Continuation' of my former application, Serial No. 191,676, filed May 16,1927.

The present improvements relate to hy? drocarbon oil conversion, and more particularly to the cracking of hydrocarbon oil under heat and superatmospheric pressure to produce desirable yields ofL commercialproducts therefrom.

In some of the commercial processes for cracking hydrocarbon oils under heat and superatmospheric pressure as practiced today,

it is found to be advantageous to permit/oil v which has been-heated to a conversion temperature while passing through aA suitable heatingcoil mounted in va heating zone to be subjected to a soaking or digesting treatment for a suiiioient length of time to prolong the period during which the oil is maintained under the conditions of conversion temperature under superatmospheric pressure.

One of the methods proposed for accom-` plishing this digesting treatment comprises a tubular structure preferably externally unheated but insulated to prevent loss ofheat by radiation through which the oil subsequent to attaining ythe l desired temperature is passed. That is vto say, the temperatureV of the oil while passing through what may be termed the soaking instrumentalitymay be raised slightly, or the temperature may be maintained at or about the temperaturetoVV whichV the oil was subjected while passing In any event, thev oil passing through the soaking instrumentality will not be subjected to as drastic a heating as the initial heating coil.

The principal object of the present invention is to prevent the precipitation of undesirable solid or semi-solid particles in the soaking instrumentality and at the same time maintain a desired velocity of the oil passing therethrough by recirculating regulated portions of the oil which has passed through the soaking instrumentality whereby the velocity of said oil is maintained so as to prevent precipitation. As an incidental advantage to the accomplishment of this object, it willbe found that the temperature will be more nearly uniform from inlet to outlet of the digesting instrumentality than where no induced circulation takes place.

Another objectofithe present inventionvis the passage of oil through the soaking instru-N mentality; The `single figure/in the drawing is a diagrammatic lelevational view yof apparatus equipped to accomplish the objects of rthe present invention.`

Referring more in detail to the drawing, 1 designates a charging stock inlet line in which may be interposed a valve 2 injecting said charging stock into the upper kend of a conventional type dephlegmator 3. While descending through the dephlegmator 3, as is well known, the lighter fractions of said charging stock will vaporize under the pressures employed, while the bulk after acting as a cooling medium passes through the reflux leo' 4 and vinto the line 5. This line 5 communicates with return line 6 adapted to inject said charging stock and reflux condensate y intothe heating coil 7, which may be mounted in a heating zone 8. Means' are provided for returning the reflux and charging stock either under an induced pressure by closing valve 9 in by-pass line 10 and opening valves 11 in the line 12, in which is interposed a pump 13.

Orwhere it is not desired to impose a me-r chanically applied pressure on the returning oil, the valves 11 may be closed and the valve 9 opened. Regulated portions of the return ing liquid may be withdrawn through the line 111, controlled by the valve 15. If it is not desired to 'feed the chargingstock directly to the dephlegmator, it may be fed to the charging line 6 through the line 16, controlled by valve 17. Or, the feed may be split, part of the charge going to the dephlegmator and the rest being charged'directly to the line 6.

The oil passing through the heating coil 7 which may ycomprise unvaporized portions of the charging stock and reflux condensate will be raised to a conversion temperature, for instance, depending on the character of charging stock and types of products desired, which may range from 750O to 3750 F., more or less, while a superatmospheric pressure of from three to several hundred pounds, more or less, may be maintained thereon. The heated oil may discharge through transfer line 18, in whichr may be interposed a valve 19, into a tubular structure 2O mounted in a suitable container 21. This structure may comprise connected lengths of tubing or a single tube or may take the forni of a shell, and may, for convenience, be referred to as the .soaking or digesting instrumentality.

rlhe container 21 may be filled with any suitable form of insulating material, such as insulating powder 22, if desired. lt is the purpose of the soaking instrumentality 2O 205 to prolong the period of time during which the oil is subjected to reaction temperature. Therefore, it is of importance that the oil be maintained substantially at or above the desired reaction temperature during its passage through the: soaking instrumentality 20, that is, substantially at or above the temperaturey at which it was introduced thereto. Therefore, it is te be noted that the purpose of the insulating material is to prevent excessive loss of heat by radiation. Some means may be employed to maintain the temperature or even for raising the teinperature slightly above the temperature at which the oil enters, but in any event said 35' heat is relatively mild, and it is desirable that the element be not subjected to as drastic a heating as the coil 'i' was subjected.

The oil after passing through the soaking Velement 2O discharges into a relatively nar- 40 row, vertically disposed combination separater and pump chamber 23 wherein is disposed a recirculating instrumentality 24 which may take the form of a propeller mounted on the shaft 25 and driven by a motor illustrated diagrainmatically at 26. lt is to be understood, of course, that while l have shown a propeller as an instrumentality for inducing the recirculation that any other mechanical means for accomplishing thispurpose can be utilized within the scope of the invention. The instrumentality 24 is so arrange-d as to operate at variable speeds, the speed of rotation thereof regulates the velocity of the oil being recirculated and consequently regulates the volume or quantity of recirculated oil relative to non-recirculated or fresh incoming oil through line 18.

The proper speed at which to operate the instrumentality 24 can be determined by preliminary runs on a similar charging stock wherein the minimum speed at which it would be practical to operate the instrumentality would be a speed slightly above that at which carbon precipitation might take place. rlhis minimum speed which can be determined by experimentation is the optimum speed at which it is desired to recirculate. The recirculated oil passes through a circulating line 27 in which is interposed the valve 23, merging with the transfer line 18, as illustratedl".

The excess fluid passes through transfer line 29, controlled by valve 29', being introduced into a conventional type reaction drum 30, which reaction drum may be provided with the cleaning manholes 31, and residue draw-offs 32, controlled by valves 33. Separation of vapors from non-vaporous residual products of reaction takes place in the drum 30, which vapors may be withdrawn through the vapor outlet pipe 34, controlled by valve 35, discharging into the lower end of the dephlegmator 3 wherein the vapors are subjected to the usual dephlegmation.

It may be desirable to maintain a low liquid level of non-vaporous residual products of reaction in the drum 30, and for thisr purpose it may be desirable to subject the residue to a mild agitation so that the bodyv of residue is kept in movement and the solid or semi-solid particles maintained in suspension and prevented from agglomerating and solidifying. To this end, l may provide a suitable stirrer, illustrated diagrammatically at 36.

Vapors remaining uncondensed after passage through the dephlegmator may be withdrawn through the vapor outlet pipe 37 in which may be interposed a valve 33, condensed in condenser coil 39 and collected as liquid distallate in the receiver 40. The latter may be provided with the gas relief line 41, controlled by valve 42, and with the liquid draw-off line 43, controlled by valve 44.

For the purpose of assisting in the dephlegmation of vapors in the dephlegmator 3, regulated portions of the condensed liquid collecting in receiver 40 may be returned through the line 45, controlled by valves 46, under the influence of the pump 47 interposed therein.

The operation of the process and apparatus should be apparent from the foregoing description. rlhe speed at which the instrumentality 24 is operated regulates the proportion of fluid hydrocarbons which are recirculated, while the pump 13 regulates the amount of fresh charging stock being introduced to the heating coil, this pump 13 also controlling the amount of oil and vapors passing from the chamber 23 through the transfer line 29 to the drinn 30.

One effective method of heating the soaking element 20 in the event it should be desired to maintain or slightly raise the temperature therein is to subject the element to the action of gases of combustion passing downwardly countercurrent to the upward flow of oil therethrough, thus maintaining more uniform conditions of temperature therein. rllhe recirculation itself will assist in the mainte-a nance of more uniform temperature conditions on the oil passing through the soaking element 20.

It is obvious, of course, that any desirable temperature and pressure conditions may be maintained throughout the system, the most desirable conditions being within the purview of those skilled in this particular art, depending principally upon the character of the charging stock and the types of products desired. It is to be understood, of course, that I do not wish to limit myself in any way to the apparatus shown, as radical changes may be made therein without eifectingthe scope of the invention.

I claim as my invention:

A hydrocarbon oil cracking process which comprises flowing the oil in an elongated stream of restricted cross-sectional area through a heating zone and heating the same therein to cracking temperature under pressure, thence circulating the thus heated oil, substantially without further application of heat thereto, through a soaking zone in a heat insulated stream of restricted cross-sectional area at a temperature near that at which the heated oil left the heating zone, effecting substantial conversion of the oil during such circulation thereof through the soaking zone, then removing the converted oil from the soaking zone and splitting the same into two sections, injecting one of said sections into the hot oil stream passing from the heating zone to the soaking zone in the direction of iiow of the heated oil and under suflicient velocity to substantially prevent carbon precipitation from the oil while circulating through the soaking Zone, introducing the other of said sections of converted oil into a separating zone and separating the same therein into vapors and residue, and dephlegmating and condensing the separated vapors.

In testimony whereof I affix my signature.

OSCAR I-I. FAIRCI-IILD.

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