US1931594A - Continuous coking still - Google Patents

Description

00%, 24, v.1933. l B WEAVER 1,931,594

CONTINUOUS COKING STILL Filed April 29, 1931 3 Sheets-Sheet 1 if? j I Qmmrw am we 1 @ci. 24, 1933. J. B. WEAVER 399319594 CONTINUOUS COKING STILL Filed April 29, 1931 3 Sheeis-Sheet 2 J. B. WEAVER I 1,931,594

oou'rmuous COKING STILL Filed April 29. 1951 s Sheets-Shec s Fatented .Gct. 24, 1933 eoN'rINUoUs some s'ru:

Joseph B. Weaver, New York, N. Y.

Application April 29, 1931. Serial No. 533,5 86 7 Claims. (or. 202-106),

This invention relates to an improved coking still primarily adapted for use in handling heavy petroleum residuesof, for example, the residual oils discharged from oil cracking systems, and

5 wherein the construction of the still is such as to provide for the positive advance of such residues through the heating elements or retorts of the still while the residues are being subjected to suificie'nt heat to effect the removal as vapors of the volatile constituents thereof, the vapors being removed from the upper portions of said retorts contiguous to the point of introduction of the residual oils into said retorts, while the volatile-freed coke is continuously removed from the lower portions of said retorts.

In the operation ofcoking stills, considerable difliculty has been encountered in the matter of preventing the thick viscous coke from adhereing to the walls of a retort and choking or clogging the retort against the proper movement of the petroleum residues therethrough. The coke has a tendency when subjected to the proper degree of heat necessary to deprive the same of its volatile matter, to harden and build up tenaciously cling ing deposits or incrustations on the heating retort walls-and these deposits interfere with proper heat transfer between the heating medium, such as furnace gases, and the petroleum residues undergoing such-heat treatment in the retort. To

provide for continuous or sustained operation for extended periods of time of such a retort, it is,

therefore, important that provision be made for insuring the desired progressive advance of the petroleum residues through the heating chamber or retort, whereby as the residual oils are continuously introduced into one portion of the retort, the substantially solid petroleum coke may be likewise continuously removed from another portion of the retort and wherein, at the i0 same time, provision be made for constantly scraping or otherwise mechanically removing the heated mass of petroleum in the retort from not only the walls of the retort but also from the walls of the agitating or scraping means, whereby the full length of the retort or coking chamber may be kept in an open condition permitting of the desired passage of the volatiles in a direction countercurrent to the passage of the residues or coke through the retort and the retort also kept open to provide for the sustained advance of the pitchy tarry mass from which the coke is formed.

In attaining these ends, I have provided a coking still which is formed to comprise a furnace having arranged in the 'path of furnace gas travel a longitudinally extending retort disposed at an acute angle with respect to the vertical and wherein each retort, since there may be a plu rality of them disposed within the furnace, is

formed to comprise a pair of adjoin'ed tubes which i are in open communication along their adjacent so? sides, ;each of the tubes being equipped with a longitudinally extending rotor mounted to re-= volve about the longitudinal axis of each tube, the said rotors being provided with interengaging blades and a drive mechanism is provided, which 5 is arranged exteriorly of the furnace, for imparting intermittently and alternately rotary mo= tion to said rotors, whereby movement is, im== parted to. one of said rotors to cause the latter to engage and scrape coke from the side walls 7 of its chamber or tube and the adjacent surfaces 0f the adjoining complemental rotor. The drive mechanism is such that following this operation, the first rotor is brought to a stand still and the second complemental rotor operated so that it 1 may be moved to scrape coke from the walls of its tube and the adjoining surfaces of the first of said rotors.

The construction'and operation of the rotors is therefore such as to' provide fortheir self- 0 cleaning as well as the cleaning of the'longitudi= nally extending apertures formed between the blades of the rotors and the inner walls of the rotor.

The coking still further provides for a gas 35 sealed outlet through which the coke formed in the rotor is discharged; the provision of a nozzle structure for introducing petroleum residues into the upper portion of the retort and wherein the nozzle is equipped with means by which its aperture may be cleaned of coke deposits; the provision of means for utilizing economically the heat of the furnace and the heat of the products discharged from the retort for the development of steam and in other ancillary capacities and, also, the provision of a coke still of simple mechanical construction and of efficient operation.

With these and other objects in view, which will appear as the description proceeds, the inven- 4 tion consists in the novel features of construc- 1 0 tion, combination of elements and arrangements of parts hereinafter fully described and pointed out in the'appended claims. In the accompanying drawings:

Fig. 1 is a vertical sectional view taken through a continuous coking still constructed in accordance with the present invention;

Fig. 2 is a horizontal sectional view taken through the vapor outlet of the still on the plane indicated by the line 2-.-2 of Fig. 1; 11o

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Fig. 3 is a horizontal sectional view taken through one of the double tube retorts of the still and disclosing the formation of the scraping rotors mounted therein, the plane of the section being disclosed by the line 3-3 of Fig. i;

Fig. 4 is a vertical sectional view disclosing the drive mechanism for the rotors, as indicated by the line 4i l of Fig. 1;

Fig. 5 is a horizontal sectional view on the plane indicated by the line 5-5 of Fig. l;

Fig. 6 is a similar view on the line 6-6 of Fig. 4. and disclosing more particularly the interrupted gears for effecting the rotation of the scraping rotors;

Fig. 7 is a vertical sectional view taken through the coke outlet of the retort on the line 'l--'? of Fig. l;

Fig. 8 is a vertical sectional view on the line 8-8 of Fig. 7;

Fig. 9 is a detail vertical sectional view on the line 9-9 of Fig. 1;

Fig. 10 is a diagrammatic View disclosing the operation of the coking still and associated condensing and heat exchange apparatus;

Fig. 11 is a similar view showing a slightly modified form of the invention. Referring more particularly to the drawing the numeral 1 designates the coking still comprising the present invention in its entirety. This still is formed to embody a furnace formed from suitable heat retaining walls, including in this instance a vertical front wall 2, an inclined rear wall 3, top and bottom walls t and 5 respectively, disposed substantially perpendicularly to the plane of the rear wall 3, and vertical side walls 6. Also arranged in the furnace is an inclined bridge wall 7 which extends substantially parallel to and spaced from the rear wall 3. Between the bridge wall 7 and the front wall 2, the furnace includes a combustion chamber 8 and desired furnace temperatures may be obtainedwithin this chamber by the provision of combustion producing burners or other equivalent apertures 9. The gases-of combustion pass upwardly through the chamber 8 and thence downwardly through a retort chamber 10 formed between the bridge wall 7 and the rear wall 3 and aftertraversing the chamber 10, the gases are delivered to a vertical outlet stack or flue 11. it will be understood that the walls of the furnace may be of any desired construction customary in the building of furnaces of this character and therefore a further explanation relative to the design or structural characteristics will be omitted The burner 9 may be of the oil or gas type or mechanism may be substituted therefor adapted for the burning of solid fuels and it will be appreciated that these are details which may be varied depending upon the particular conditions of economy which prevail when the stills are to be operated. v

Extending longitudinally through the retort chamber 10 between the bridge wall 7 and the rear wall 3 and also through the space establishing communication between the upper portions of the chambers 8 and 10 is a retort 12. While but one retort has been illustrated in the accompanying drawings, it is to be understood that the furnace may containas many of these retorts as may be needed to secure a certain desired working capacity on the part of the still. However, since such additional retorts will constitute but a mere duplication of the one depicted, a detailed description of such retort will sufice for all.

In its preferred form, the retort 12 comprises oarser a plurality of longitudinally aligned double tube sections 13 which are secured together by fastening devices passing through the flanged meeting ends 14 thereof. The double tube sections are each of integralv formation and the said sections are in open communication along their adjoining. sides, as disclosed in Figs. 2, 3 and 5. The upper section of the retort is loosely received in the top wall l, whereas the lower of said sections passes through the bottom wall 5 and is directly secured to a rigid bed casting 15 which is mounted upon the furnace foundation 16. This construction permits the retort to expand and contract in response to fluctuating temperature conditions, without detrimentally effecting the eihciency of the furnace structure. Preferably, the'retort 12 is arranged at an angle of approximately with respect to the vertical. This angle is such as to provide for maximum length of the retort within the furnace and to control more effectively the desired gravitational feed of the coking material through the retort in order that it may be subjected to the temperatures of the furnace for the necessary period of time. Also the angle of the retort serves to minimize clogging or choking of the passages of the retort with the coke or coke forming materials during the operation of the retort.

Steam jacketed residual oil inlets 17 are. pro-= vided in connection with the upper end of the retort 12, there being an inlet for each of the tubes of the retort. Heavy petroleum residues, such as the residual oils of cracking systems, as

will be hereinafter specified, pass into the inlets 17 by way of suitable valve controlled pipes 18 l and thence downwardly through restricted passages 15) wherein the "oils enter the upper portion of the retort. The passages 19 may be cleaned of coke or other obstructing matter by means of screw threaded plungers 20 which are movable 1 into and through the passages 19 to scrape accumulated matter from the walls thereof, thus keeping the passages 19 free and allowing for unrestricted oil flow into the retort 12. @By steam jacketing the passages 19, coke formation therein 1 is minimized as th oil passing through the pastravel through the retort, where they are taken off at the upper end of the retort through an outlet 21. As the oils or residues pass downwardly through the retort and thetemperatures thereof 1 increased and the vaporizable compounds removed, such residues become increasingly heavy,

. thick and viscous, possessing a tarry consistency which. renders the same extremely difficult to handle even in large size tubes. This slow. moving tarry mass tends upon contact with the heated walls of the retort to coke and produce a hardened deposit which, if not removed, would soon' obstruct and arrest the operation of the still.

Therefore,.it is important that means he provided 1 for positively effecting the progressive travel of the coke or tar through the retort and to prevent the same from accumulating on the walls of the retort. The best means I have found for attaining this result consists in the provision of a pair 1 approximately 660 152, at substantially which temperature they are introduced into the upper end of the coking retort. The volatiles discharged from the vapor outlet 21 possess an approximate temperature of 800 F. and, commingled with superheated steam, pass through the heat exthe oil is separated from the condensed steam and both water and oil independently drawn off through the lines 49 and 50 respectively.

The residues, during the process of evaporation in the retort pass generally downwardly, the coke falling into the conveyor 43, at which point, in order to utilize efiicientlythe heat contained in the coke, since the latter possesses a temperature of aproximately 850 F., water will be introduced by way of the line 51' to generate steamand to cool the coke down to a temperature of approximately 300 F. Water is also introduced into the coil 46 in the steam generator 45 and passes from said coil by way of a line 52 into a superheater 53, disposed in the stack or waste gas fiue ll of the furnace. In this superheater, the temperature of the steam is raised to approximately 1000 F., and the superheated steam passes from the superheater into the lower end of the retort by way of the pipe line 54. In

the modification of the invention disclosed in Fig. 11, water is directly introduced in fine jets into the vapor outlet 21. In this arrangement,

the water is introduced in a very fine spray in suflicient quantities to condense only the oil vapors, allowing the steam to escape at sufficiently low pressures inorder not to in any way disturb the pressure balances in the retort. This operation avoids the use of the heat exchange apparatus 44, 45 and 47 disclosed in Fig. 10.

The residue introduced into the coking still may be handled in its retort. These residues are typical of reduced Seminole crude oil.

Gravity 12 A. P. i. Volatiles i 79% by volume Weight, per U. S. gallon 8.2 lbs. Heat of Vaporization 90 B. t. u. per lb. of oil Specific heat .70 at 700 Weight of coke 2.55 lbs. per gallon.

The overhead distillate will be approximately, as follows:

"Weight per gallon 7.163 lbs. Heat of vaporization 90 B. t. u, per lb. of oil Specific heat .90 at 800 Gravity "l. r 33 A. P. I.

.79 gallons produced per gallon of residue charged.

and mechanisms may be utilized without departing from the invention. The dry coke graduallyfinds its way to the bottom of the retort where it is passed out through the two small rotors 4.0,

which act as gas-tight valves, the coke being finally delivered to a screw conveyor 43. There I are two injection nozzles 19 at the top of the rotor, each nozzle introducing the residues over the center line of each rotor. Each injection nozzle is provided with a plunger 20 which may be forced down through the nozzle to clear out any coke which may be formed at the entrance to the rotor. The nozzle is provided with a steam jacket, for the purpose of keeping the interior sufficiently cool to prevent excessivecoke formation.

Attention is drawn to the design of the rotor which takes care of, in a simple way, the expansion and contraction which will occur. The double retort tubes are rigidly held at the bottom and allowed to expand in a general vertical direction allowing for ample clearance to take care of the internal, as well as the external, expansion in a longitudinal direction; and, as a complete coking still requires a multiplicity of these retort tubes, such tubes will be separated a sufficient distance apart so that they may expand and contract laterally inside of the furnace, being rigidly held at the lower end by suitable connections to the bed plate or foundation.

Any suitable pressure may be carried on the material passing through the retorts 12 or if desired, the retort may operate with sub-atmospheric pressures. Any suitable charging stock may be supplied to the retorts, includingnot only high boiling petroleum oils, but crude oils, coal tar products, shale oils and other oleiferous materials. It is not necessary that the residues from the operation of the retorts should be carried down to coke or other form of solid residues. In certain operations, it may be desirable to remove the residues as a heavy liquid or as semisolids.

What is claimed is:

l. A continuous coking still comprising a furnace, a retort disposed in said furnace at an acute angle to'the vertical, said retort being provided with a pair of parallel longitudinally extending chambers in open communication with each other along their adjoining sides, a pair of rotors mounted in said chambers to extend longitudinally thereof, said rotors being provided with inter-engaging blades having arcuate surfaces, the orbits of said rotors being disposed in overlapping relation, power driven means for inter mittently and alternately imparting rotary movement to said rotors, means for introducing a heavy petroleum oil into the upper portion or said retort, an outlet for discharging coke from the lower portion of said retort, and an outlet for the ,release of volatile consituents of said oil provided in the upper portions of said retort contiguous to the point of introduction of said residual oils.

2. A coking still comprising a furnace, a double.

locking a rotor during active movement of the v complemental rotor, means for introducing a heavy petroleum coke forming oil into the upper v portion of said retort, a coke outlet provided in the lower portion of said retort, and a vapor outlet provided in the upper portion of said retort.

3. Acontinuous coking still comprising a furnace, formed to include a setting, said setting being formed internally ,to provide a combustion chamber and a retort chamber, a bridge wall separating said chambers, communication be-' tween said chambers being established over the upper portion of said bridge wall, combustion developing means disposed in said combustion chamber and a waste gas outlet communicating with the lower portion of said retort chamber, a tubular retort mounted in said retort chamber and extending longitudinally therethrough and through the upper and lower walls of the setting, a base member to which the lower portion of said retort is rigidly connected externally of said setting, said retort passing freely through the walls of said setting to expand and contract freely with respect thereto, means for introducing a petroleum residue into the upper portion of said retort, self-cleaning agitating means arranged in said retort for effecting the positive advance of said residue therethrough, a coke outlet communicating with the bottom of the retort, and a vapor outlet connected with the upper portion of said retort.

4. In a coking still, a furnace including heat retaining walls and combustion producing means, a tubular retort disposed in said furnace and operatively arranged at an angle of substantially 30 degrees with respect to the vertical, the lower portion of said retort being arranged to project through and below an opening in one of the lower of the walls of said furnace, rotatable cutters for removing coke from the inner surfaces of said retort and the surfaces of the cutters themselves, a base member mounted independently and extraneously of the furnace walls and to which thelower end of said retort is secured, said base member serving to effect the support and sustain the weight of the retort substantially independently of the furnace walls, and motion transmitting means carried by said base member for driving said cutters.

5. A coking still comprising a furnace formed to include heat confining walls and combustion producing means, a tubular retort arranged in said furnace and disposed in acute angular relationship with respect to the vertical, the ends of said retort passing freely through openings formed in the upper and lower walls of said furnace, a base member arranged exteriorly of the walls of said furnace and directly connected with the lower end of said retort to support substantially the weight of the latter when in its operative position within the furnace whereby to ab-- sorb the longitudinal thrust of the retort, rotors revolubly mounted in said retort, means carried by the base member for imparting movement to said rotors, an oil inlet communicating with the upper part of said retort, a vapor outlet in the upper part of said retort, and a coke outlet formed in connection with said base support and in communication with the lower end of said retort.

6. Heating apparatus for reducing heavy hydrocarbon oils to coke and vaporizable oils comprising a furnace formed to include heat confining walls and combustion developing means, a tubular retort projecting through the walls of said furnace in acute angular relationship with respect to the vertical, a base member connected with the lower end of said retort for supporting the latter in its operative position within said furnace independently of the walls of the latter, means for introducing oils to be heated into the upper region of said retort, means for removing vapors of said oils from the upper portion of said retort, a coke outlet communicating with the bottom of said retort, rotatable means disposed in said retort for removing coke from its inner surfaces and eifecting the positive discharge of said coke through said outlet, and means for utilizing 100 the heat remaining in the furnace gases following the passage of the latter over said retort to directly heat the products within said retort prior to their discharge from the vapor and coke out lets.

7. Heating apparatus for reducing heavy hydrocarbon oils to coke and vaporizable oils comprising a furnace formed to include heat confining walls and combustion developing means, a tubular retort projecting through the walls of 110 said furnace in acute angular relationship with respect to the vertical, a base member connected withthe lower end of said retort for supporting the latter in its operative position within said furnace independently of the walls of the latter,

means for introducing oils to be heated into the upper region of said retort, means for removing vapors of said oils from the upper portion of said retort, a coke outlet communicating with the bottom of said retort, rotatable means disposed in said retort for removing coke from its inner JOSEPH B. WEAVER.

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