US1916319A - Apparatus for high temperature distillation - Google Patents

Description

July 4-, 19330 L g, HUFF 1 9116 319 APPARATUS FOR HIGH TEMPERATURE DISTILLATI ON Filed Aug. 11, 1950 FIG 2 INVENTOR LYMAN C. HUF F ATTORNEY fatentecl July 4, 1933 V UNITED STATES PATNT OFFICE LYMAN C. HUFF, OF CHICAGO, ILLINOIS, ASSIGNOR TO- UNIVERSAL OIL PRODUCTS COMZPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA APPARATUS FOR HIGH TEMPERATURE DISTILLATION Application filed August 11, 1930. Serial No. 474,478.

This invention relates to apparatus for high temperature distillation and pertains more particularly to an apparatus for the distillation of hydrocarbon oils under ele vated temperatures.

The apparatus is of general practical application to distillation processes of various descriptions, and finds a specific adaptation to the reduction of relatively heavy hydrocarbons to heavy residue with the formation of vapors therefrom. The invention embodies in its most specific aspect the reduction of heavy hydrocarbons from residual oil to substantially dry coke.

To describe the invention, by way of illustration, with relation to the coking of heavy hydrocarbon oils, the reduction of oil residues resulting from the distillation of crude petroleum and from cracking processes to coke is a practice old in the refining art. In the carrying out of coking processes of this nature, there are ordinarily employed horizontal or vertical stills heated at the bottom by direct firing. The stills, which generally are of steel or similar metallic material, quite rapidly deteriorate and are destroyed due to the insulating action of the coke deposited on their inner surfaces, the deposits of coke preventing the transfer of heat from the outer surface of the still into the liquid under treatment and likewise interfering with the dissipation of the heat by radiation. Still bottoms in this type of equipment require frequent replacement with the attendant expense, and the dissuse of equipment during repairs.

I have devised a novel type of still for the reduction of .hydrocarbons to substantially dry coke. The apparatus comprises a still or chamber vertically disposed within a furnace employing both radiant and convection heat. The furnace construction is such that shielded radiant heat is utilized to heat the lower portion of the still. This arrangement serves the two-fold purpose of providing a means whereby the lower portion, or that portion of the still most susceptible to the deposition of coke, is supplied with a mild form of radiant heat and provides means of partially cooling the combustion gases before they are introduced into direct contact with the upper portion ofv the still. By this method the entire outer shell of the still is more uniformly heated than would be otherwise possible, instead of supplying intense heat to the still surfaces upon which the major portion of the coke is deposited and little or no heat to other portions of the still, as is the case with the old direct firing methods employed either with vertical or horizontal stills.

I also provide a means of pre-heating the combustion air supplied to the furnace, thus afiording better combustion and fuel economy than is otherwise possible.

The attached drawing illustrates diagrammatically and not to scale one specific form which my improved apparatus may assume. Figure l is a longitudinal cross-section through the furnace showing the vertical stillin-full and two of the radiant combustion zones in section. Figure 2 is a horizontal section, or sectional plan view, of the apparatus taken along line 22 in Fig. l.

eferring now to the drawing, the vertical coking still 1 preferably has manholes or clean-out ports 2 at its top and bottom ends which are accessible for cleaning purposes. Draw-off lines, vapor lines, charging lines, etc., may be located at any desired points. Such connections are well known in the art and are not here illustrated. The outer walls 3 of the furnace setting, here shown as substantially square in horizontal cross-section, although they may form a circle or any other desirable shape, may be built up of any suitable refractory material, such as firebrick, and rest upon any suitable form of support or foundation 4. Combustion chambers 5 are provided within the furnace at the four vertical corners. Their inner walls 7 are built up of suitable refractory material such as carborundum brick, preferably having the property of assuming some degree of incandescence upon heating, so that they will radiate heat to the lower portion of still 1. The outer walls 6 of the combustion zones may be constructed of'the same type of material as used in the walls 7 or may be ordinary firebrick or a metallic alloy which does not deteriorate at the high temperatures. Air spaces 8 are provided between the outer walls 6 of the combustion zone andthat portion 3a of the outer furnace wall surrounding the combustion zones.

Air for combustion is supplied to the furnace through ports 9 and in passing down through the air spaces 8 is pro-heated by heat from walls 6 and enters the combustion zones 5 through ports 10. Fuel such as oil or gas is supplied through burners 11 and, particularly if oil is used, air or steam for the atomization of the fuel may be supplied through these same burners. The additional air required for proper combustion and auxiliary air, if desired, being supplied after preheating as already described.

The sizes of the elements of the furnace are so proportioned that substantially all of the combustion takes place in the combustion zones 5 as in this manner no portion of the still is subjected to direct firing and no flame impinges upon the still shell.

The combustion products pass from combustion zones 5 into the upper portion of the furnace 12 surrounding the upper ortion of still 1 which is thereby heate by convection. A portion of the combustion gases may pass down around the lower portion of still 1 through zone 13 which lies between the lower portion of the still and the combustion zones 5. These gases, impelled by the upward draft through zones 5, may enter said zones through ports 14 to be recirculated through said combustion zones 5.

Dampers, not shown, may be provided to regulate the openings through ports 14 or to completely close these ports when desired and thus to regulate the quantity of combustion gases recirculated. It is thus evident that the lower portion of still 1 may be heated entirely by shielded radiant heat or by a combination of radiant and convection heat and the upper portion of still 1 may be heated substantially by convection heat augmented to a minor degree by radiant heat from the furnace walls 3. It will be understood that not all of the radiant heat supplied to the lower portion of still 1 comes dlrectly from the incandescent walls 7 of the combustion zones 5 but that a substantial proportion of the heat radiated from walls 7 is transmitted to still 1 by reflection from the furnace walls 3 both above the combustion zones 5 and more particularly, from that portion of the furnace walls 3 between adjacent combustion zones.

The combustion productsfinally leave zone 12 through any number of a plurality of ports 15 distributed around the outer walls of the furnace. Ports 15 all lead into a common header or flue passageway 16 which surrounds the furnace and are finally discharged to a stack, not shown, through flue 17 U. S. Patent No. 1,548,004 as well as various pending applications by the present inventor, disclose methods and means of removing coke or carbonaceous material deposited within a chamber by removing a flexible metallic member previously suspended within said chamber. It should be understood in connection with the present application that the various methods previously disclosed by the present inventor may be utilized for removing the coke or carbonaceous material deposited within chamber or coking still 1.

Any desired temperatures may be employed within the furnace and within the reaction chamber or coking still 1. The reduction of hydrocarbon material to substantially dry coke may be accomplished in my apparatus under partial vacuum, substantially atmospheric pressure, or super-atmospheric pressures in the coking still and it is understood that the still may be used as a part of an independently operated refining process or may be used in conjunction with a cracking system and particularly as either the reaction chamber or the flash distilling chamber of a cracking system. Any of the well known methods of assisting distillation, such as injecting steam, or gas into the oil, may be utilized in connection with my apparatus.

As a specific example of the operation of my apparatus and operating conditions which may be obtained by its use: An apparatus such as above described is fired with fuel oil, sufiicient air for the atomization of the oil being supplied through the burners and the additional air required for combustion together with a substantial quantity of excess air is supplied to the combustion zones after being pro-heated, as already described, by heat radiated from the outer walls of the combustion zones. Substantially all-of the combustion takes place in zones 5. About 20% of the combustion products are recirculated around the lower portion of the coking still back into the combustion zones. The lower portion of the still is thereby heated primarily by shielded radiant heat from walls 7 and 3 and in part by convection heat from the recirculated combustion products while the upper portion of the coking still is heated primarily by convection heat from the combustion products from zones 5 and in part by heat radiated from the furnace walls 3. In this manner a substantially uniform temperature is maintained throughout the entire length or that portion of still 1, which is within the heating zone. For example, when it is desirable to operate the coking still with a nominal furnace temperature of say 1000 F., the skin temperature of the metal comprising the shell of the coking still may vary only about 50 F. from the skin temperature taken at any other point on the shell of the still within the heating zone. Furthermore by mild heating as employed in my apparatus the life of the coking still may be extended to several times that of a similar still directly fired by old methods.

It will be .understood that the description of the apparatus and the correlated process of heating as appliedto the coking of hydrocarbons is merely illustrative. While the invention is particularly adaptable to coking,

it may be similarly applied to distillation processes in general where the problems encountered are co-extensive or similar to those arfsing in the high temperature distillations necessary in coking processes.

What I claim as my invention is:

1. Apparatus suitable for use in hi h temperature distillation processes whic comprises a shell still disposed in a suitable furnace setting, a combustion chamber formed Within the furnace setting at the lower portion thereof, an air flue between said chamer and setting, means forming a part of the combustion chamber and ada ted to shield the lower portion of the still rom direct contact with the flame generated during combustion, said means being composed of refractory material which imparts to the lower portion of the still radiant heat from the combustion chamber, means cooperating with the combustion chamber whereby additional heat is imparted to the other portion of the still from the combustion gases by convection, means for admitting combustible material to the combustion chamber,and means for introducing air into the combustion chamber through said air flue thereby effecting a heat interchange between the entering air and the products of combustion.

2. Apparatus suitable for use in high temperature distillation processes which comprises a shell still disposed vertically in a suitable furnace setting, a vertical combustion chamber formed within the furnace setting and at the lower portion thereof adapted to supply heat to the still, a portion of the combustion chamber being spaced from the lower part of the still and serving as a shield to prevent direct contact of the lower portion of the still with the flame generated during combustion, said portion being constructed of refractory material which imparts heat from the combustion chamber to the lower portion of the still by radiation, the combustion chamber opening into the in- .terior of the furnace setting whereby to impart heat by convection to the upper portion of the still, said portion of the combustion chamber having an opening near its lower end whereby combustion products may be recirculated from the upper portion of the furnace through the space between said portion of the combustion chamber and the lower portion of the still and then back into the combustion zone, and means associated with the combustion chamber for the introduction of combustible material and a combustion supporting agent.

3. Apparatus suitable for use in high temperature distillation processes which comprises a shell still vertically disposed in a suitable furnace setting, a plurality of combustion chambers disposed in spaced relationship around the inner surface of the furnace setting and at the lower portion thereof, the inner walls of the combustion chambers being vertically disposed sufliciently to prevent direct contact of the flame generated during combustion with the lower portion of the still, said walls being formed of refractory material which imparts to the lower portion of the still radiant heat from the combustion chamber, the combustion chambers opening into the interior of the furnace setting whereby the upper portion of the still is heated by convection, and means associated with the combustion chambers for introducing a combustible material and a combustion supporting agent.

4. Apparatus suitable for use in high temperature distillation processes which comprises a shell still vertically disposed in a suitable furnace setting, a plurality of combustion chambers disposed in spaced relationship around the inner surface of the furnace setting and at the lower portion thereof, the inner walls of the combustion chambers being vertically disposed sufficiently to prevent direct contact of the flame generated during combustion with the lower'portion of the still, said walls being formed of refractory material which imparts to the lower portion of the still radiant heat from the combustion chamber, the combustion chambers opening into the interior of the furnace setting whereby the upper portion of the still is heated by convection, and means associated with the combustion chambers for introducing a combustible material, and a combustion supporting agent, the inner walls of the combustion chambers being formed with openings at the lower portion thereof whereby to effect a recycling of a portion of the combustion products from the upper portion of the furnace downwardly around the lower portion of the still and back into the combustion zone.

5. Distillation apparatus comprising a shell still vertically disposed within a furnace setting, a vertical heat-radiating wall in the furnace setting opposite the lower portion of the still and spaced from the latter, means for generating combustion gases between said walland the furnace setting to thereby heat theglower portion of the still by radiation, means for passing the combustion gases around the upper portion of the still to heat the same by convection, and means for passing combustion gases from around the upper portion of the still through the space between said wall and the lower portion of the still.

6. Distillation apparatus comprising a the lower portion of the still by radiation;

means for passing the combustion gases around the upper portion of the still to heat the same by convection, and means for recirculating combustion gases from around the upper portion of the still through the space between the lower portion of the still and said Wall to the space between the wall and the furnace setting where the combustion gases are being generated.

In testimony whereof I aflix m signature.

LYMAN HUFF.

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