US2533492A - Radiantly heated rotary carrier for destructive distillation - Google Patents

Description

Dec. l2, 1950 2,533,492

L. A. MEKLER RADIANTLY HEATED ROTARY CARRIER lFOR DESTRUCTIVE DISTILLATION Filed Marh 19, 1947 5 Sheets-Sheet l Dec. l2, 1950 L. A. MEKLER 2,533,492

RADIANTLY HEATED ROTARY CARRIER FOR DESTRUCTIVE DISTILLATION Filed March 19, 194'? 3 Sheets-Sheet 2 Dec. l2, 1950 L. A. MEKLER 2,533,492

RADIANTLY HRATED ROTARY CARRIER RoR DESTRUCTIVE DISTILLATION Filed March 19, 1947 5 Sheets-Sheet 3 Paume D. 12, leso UNITED s'rArEs yPATENT orrlcE RDIANTLY HEATED ROTARY CARRIER FOB DESTBUCTIVE DISTILLATIOIF Lev A. Mekler, Chicago, Ill., assigner to Institute of Gas Technology, Chicago, lll., a corporation of Illinois sneeuw man 1a. im, serial No. 135,111

,such as coal, lignin, oil shale; vegetable matter and the like.

In some of the hightemperature coking processes presently employed for thel coking of heavy oils, a pool of oil is poured on the floor of a chamber heated from below by the combustion of fuel in subjacent nues, the heat required for carbonization being conducted upwardly through said iloor. After a nrst pool of oil has been coked, a second pool of oil is poured onto the coke formed from the nrst pool. I'he heat required for carbonization of the second pool is supplied to the pool through the iioor of the earbonization chamber and through the iirst layer of coke formed from the ilrst pool. This process is repeated until a layer of coke of suitable thickness has been formed on the floor of the chamber. With each successive layer of coke formed, the temperature inside the tlues is progressively raised so that each layer of coke below the uppermost layer is subjected to increasingly higher temperatures for increasingly longer periods of time. As av result,

Vthe various layers of coke formed on the bottom of the chamber are distinguished by widely variant characteristics, as are also the gaseous products obtained in the coking of the various pools of oil. I

In this connection, it should be understood that heavy oils and the like are coked by subjecting the oils to an elevated .temperature for a suflicient time to decompose'the oils into gas,

light, intermediate and heavy distillates, an'd coke temperatures are normally a mixture of parai'iins: and/or oleiins with very small amounts of aro` matics. When petroleum still residues are coked at temperatures above 1200" F. and particularly at temperatures'between 1400 F. and l800 F., the yield of distillates is considerably lreduced. the amount of gas produced and the mount o! 4 Claims. (Cl. 1R02- 117) aromatica in the gases and in the distillate is increased while the volatile matter in the coke is reduced to as little as 0.5%. particularly if sutilcient time is allowed to dry the coke and tn crack the constituents of the volatile matter. It

is therefore clear that, while time and temperature can be varied inversely to some extent so that overall quantitative results can be obtained at lower temperatures maintained for a relatively long time or higher temperatures maintained for a shorter time. yet the quality of the gases, the distillates and the coke produced are determined by the specic temperature and the time during which this temperature is applied to the material undergoing treatment.

Hence, to produce carbonaceous material of uniform quality consistently, it is necessary to subject all the material being treated to approximately the same temperature for the same period of time. As explained hereinabove, this result cannot be achieved when the heat for the destructive distillation is supplied through the iloor of the distillation chamber and several layers of oil are successively coked on the oor and the resulting layers of coke are not removed but are allowed to accumulate.

It has therefore been proposed to eil'ect transmission of heat to a layer of oil or the like to be carbonized by downward radiation from a source of heat arranged at or near the top of the distillation chamber. However, with such an arrangement, the gases generated during destructive distillation rise and contact said source of heat, being cracked or carbonized with resultant deposition of carbon on the source of heat. In the destructive distillation of heavy oils or the like involving transmission of heat by radiation from above, the removal of carbon deposits from the source of radiant heat has therefore presented a difllcult problem.

I have now provided an improved apparatus and method for destructive distillation involving the transmission of heat to the material being distilled from above by radiation from hollow bodies supplied with air and fuel for internal combustion in said bodies; The latter are constructed of material characterized by a relatively high coemcient of expansion, so that when coke or carbon has been deposited on said bodies by the cracking of gaseous products oi distillation, internal combustion in said bodies can be terminated and the bodies allowed to cool (as by continued blowing of air alone through said bodies) with resultant contraction of said bodies and shearing or cracking of carbon adhering thereto.

It is. therefore, an important object of the present invention to provide method and apparatus for destructive distillation involving the transmission of heat by radiation from above to the material being distilled, the source of heat being an internally fired body exposed to contact with the gases generated during distillation and characterized by a relatively high coeillcient of expansion so that carbon deposited thereon due to contact therewith of said gases can be cracked or sheared off from said body by cooling thereof.

A specific object of the invention is to provide an apparatus of the nature indicated capable of continuous operation.

Other and lfurther objects and features of the present invention will become apparent from the following description and the accompanying drawings showing, diagrammatically and by way of example, three types of apparatus according to the present invention taken in conjunction with the appended claims. More particularly, in the drawings:

Figure 1 is a transverse cross sectional view, with parts shown in elevation, of a furnace according to the present invention;

Figure 2 is a fragmentary longitudinal vertical cross sectional view taken along the line II-II of Figure 1;

Figure 3 is a fragmentary transverse cross sectional view, with parts shown in elevation, of a furnace generally similar to that shown in Fig. 1 but including combustion tubes mounted in a different manner;

Figure 4 is a plan View, with parts shown in horizontal section, of another furnace according to the present invention;

Figure 5 is a vertical cross sectional view taken along the line VV of Fig. 4, with parts shown in elevation and other parts broken away; and

Figure 6 is a vertical cross sectional view taken along the line VI--VI of Fig. 4, with parts broken away and other parts shown in elevation.

In Figures 1 and 2, the reference numeral I0 indicates generally a distillation furnace according to the present invention of generally rectangular vertical cross section formed with an internal coking chamber II dened by a coking floor I2. vertical side walls I3 and a roof I4, all preferably made of relatively non-porous refractory material of relatively low he'at conductivity. The refractory material is insulated on the outside with suitable insulating material I6, to conserve heat and to maintain the coking chamber at substantially uniform temperature. The coking chamber is maintained at the desired temperature by means of heat radiating burner tubes I1 piercing the side walls and suspended near the roof Il by means of a plurality oi' metal bars I8 extending longitudinally within the coking chamber and suspended by other bars I9 depending from the roof. Oil to be cokedv is injected into the coking chamber through nozzles 20 extending through the side walls.

The tubes I1 are made of material charac@ terized by high heat conductivity and a relatively high coefficient of expansion, such as suitable ceramic material or, preferably, stainless steel, or other austenitic iron alloys, to reduce to a minimum the temperature difference between the inside of the tube and the temperature in the coking chamber and to bring about maximum expansion of the tube on heating followed by maximum contraction on subsequent cooling. A uid fuel is supplied to one end of the tube I1 (outside of furnace I0) through a valved conduit 2| and air under pressure through a valved conduit 22 joining the conduit 2| before the latter enters the end of the tube I1. The other end of the tube I1 discharges combustion gases into a flue or header 23.

In operation of the furnace I0 shown in Figs. 1 and 2, a thin layer of granular or finely divided coke of the type obtained by the operation of said furnace is initially spread over the oor I2 of the chamber II to form a zone of cleavage between the coke subsequently produced in the furnace and the floor of the furnace, whereby the removal of the coke from the chamber at the end of the operating cycle is facilitated. The chamber II is next raised to the desired temperature (above 1200" F. and preferably from 1400 to 1800 F. in the coking of petroleum still residues) by combustion of the required amount of uid and air in the combustion tubes l1. A predetermined amount of tar or petroleum still residue or the like is next introduced into the chamber Il through the nozzles 20 to form -a relatively shallow pool on the floor I2 of the chamber where the material remains until coked by the heat radiated from the combustion tubes I1. When the first charge has been coked to form a layer of coke from 1A inch to 1 inch thick, a second charge of substantially the same quantity as the first charge is admitted to the chamber II to form a second pool on top of the coke formed from the first charge. This operation is repeated with as-many subsequent charges of material as is necessary to form a slab of coke of desired thickness, say, from 1 to 6 inches. In this slab of coke, each layer is formed under substantially identical temperature conditions maintained for substantially the same length of time. The slab is therefore of uniform quality throughout.

As each pool of residue or tar or the like is being coked, the gases and vapors then generated rise from the pool towards the roof I4 of the chamber II, come in contact with the surfaces of the tubes I1 heated by internal combustion and are cracked on these surfaces to form a layer of coke on the tube surfaces. This layer of coke, if permitted to remain on the tubes, would act as an insulator with the result that the temperature of the chamber would be lowered if the temperature is maintained constant within the combustion tubes, or the internal combustion temperatures would have to be raised to maintain a constant chamber temperature. In order to maintain a uniform coking temperature without any necessity for raising the internal combustion tube temperature, the coke is periodically cracked off from the combustion tubes I1 by periodically interrupting the flow of fuel to the interior of the tubes without interrupting the air supply to the interior of the tubes. Thus, the tubes I 1 are suddenly chilled from time to time. The contraction of the tubes on such chilling cracks oif the carbon deposited on the tubes, surface to reestablish the desired relationship between the tube ternperature and the chamber temperature. When fuel is again admitted to the tubes, the expansion of the tubes on being heated will serve to crack off whatever coke may remain on the tubes at' the end of the contraction of the tubes. The coke cracked off from the tubes I1 falls on top of the layer being coked and is incorporated in the final slab of coke by the coking of a. subsequent charge of oil or the like.

Some oils .tend to foam when coked. This foaming can be materially reduced by introducassassin ing relatively small amounts, up to of the coke being produced, of granulated coke over the flow and over the tops of the coke bedsbefore introducing each charge of oil. Said introduction of coke also serves to increase the density of the coke produced, which sometimes is desirable, par. ticularly if the amount of the coke cracked on the tubes I'I is not sumcient to serve this purpose.

The frequency of chilling and reheating of the tubes Il to keep these tubes clean enough for elllcient operation is determined by the rate of formation of gases and vapors contacting the tubes and on the coke forming characteristics of these gases and vapors. The chilling and reheating cycle can be started automatically by thermostatic means (not shown) controlled by the temperature of the metal of the tubes, by the temperature of the gases discharged from the tubes into the exhaust header 23, or by any other suitable means. so that the desired chamber temperature is automatically maintained during the whole coking operation.

In Fig. 3 I have shown another furnace l0 according to the present invention generally similar to that shown in Figs. 1 and 2, the same reference numerals being employed to show identical parts. The only difference between the furnace Il of Fig. 3 and the furnace III of Figs. l and 2 lies in the fact4 that in the furnace n the end portions of the tubes I1 are fixed in the side walls and are not supported between the side walls. More particularly, collars are attached to the outside of the burner tubes Il immediately inside the side walls Il. It will be noted that (similar to the construction shown in Figs. l and 2) the burner tubes Il are formed with an expanded portion 'y or beads lla fitting the flaring outer, terminal portion of the -aperture through the vertical side wall receiving the burner tubes I1. Thus, the tube portions of the burner tubes I1 buried in the side walls of the furnace are locked therein and held against movement. Therefore, on expansion of these portions of the combustion tubes I1 within the coking chamber, said portions are bowed y transversely, as shown in dotted lines in Fig. 3. On subsequent cooling, these portions of the burner tubes i1 within the coking chamber are straightened out and assume the other position shown in Fig. 3 in full lines. This bowing and subsequent straightening of the tubes l1 laids in .the cracking off of adherent coke therefrom.

In Figs. 4, 5, and 6, reference numeral 40 indicates generally another furnace according to the present invention, this furnace being particularly adapted for continuous operation. The furnace 40 is generally annular in shape and includes pairs of radially spaced steel columns 4I eoncentrically erected with respect to a central point, the tops of each pair being joined by radial steel beams 42 from which are suspended two pairs of concentric spaced channel shaped circular steel beams I3. From each pair of steel beams 43 are suspended two spaced circular concentric blocks 44 constructed of suitable refractory material and bil including an upper section supported by the flanges of the beams 43 and an intermediate constricted portion of generally tapering or wedge shaped cross section Joined to a, lower section formed with rabbeted -upper edges for supporting three generally circular, spaced concentric blocks 45 of refractory material having flanges along their upper edges fitting the rabbets of the blocks 44. The blocks M and 45 may be cemented together and jointly form the roof of an annular coking chamber the sides of which are formed by spaced vertical walls il having upper inner beams 4I.

edges twice rabbeted to receive and support the undersides of the outer two blocks as well as the flanges of said two blocks not supported by the blocks 44. Further, the roof formed by the blocks Il and l5 as well as the side walls il are suitably covered by an inner layer 52 and an outer layer Il of insulating material.

The bottom of the coking chamber 5l is formed by a circular rotatable hearth t5 made of suitable refractory material supported by wheels Ii running on a circular track 51 and suspended from the underside of the hearth bymeans described in detail` hereinbelow. It will be noted that the side walls 5I are formed with inward radial projections lila at the bottom thereof while the lower part of the hearth 55 is correspondingly recessed, as at 55a, the hearth it being everywhere spaced from the side walls 5I for permitting rotation of said hearth. Further, the side walls 5I terminate downwardly flush with the bottom of the hearth I5 and have their undersides supported by radially extending steel beams Il, having their inner ends resting on vertical steel beams 59 and their outer ends connected to the The recessed inside of the hearth l5 is covered by a steel sheet B0 projecting below the bottom of the hearth, while the outside of the hearth is covered by a steel sheet 8| also projecting below the bottom of the hearth and having an upper margin Bla extending radially from the top of the hearth in the plane of the upper surface of the hearth into a groove Ma in the inner side wall Si. The downwardly projecting portions of the sheets and 6I Vare pierced by spaced apertures 80a and Bib, and have their lower edges bent toward each other and attached to a circular steel' sheet 02v extending below the hearth with its margins below the projecting side wall portions Sla folded upwardly, as at 62a, to define with angle rims 63 depending from the inner lower edges of the sidewalls 5I, two concentric sand traps for sealing off the space beside and below the hearth.

The wheels 5B are supported from the underside of the sheet 62 in suitable brackets 6I carrying journals for the Wheel axles.

Steam can be supplied to the sealed-off space vbelow and beside the hearth 55 through pipes 65 piercing the outer side wall Il. The apertures Sib and 60a permit flow of steam into the whole space in question.

The top of the hearth 55 slopes slightly outwardly and is subdivided into a number of equal sections by radial partition walls 66 rising to a height slightly greater than the desired over-all thickness of the layer of coke to be formed on the hearth 55. For discharge of said coke, said sections, on rotation of the hearth 55, are successively brought in radial alignment with a pusher member 61 supported on steel beams 88 inside the innermost side wall 5I of the hearth and adapted to push the contents of the section aligned therewith out through a radial aperture B9 in the outer side wall 5I discharging into a radially extending hopper 10 having sloping side walls H at the mouth of the aperture il and adapted to be closed by a vertically operating gate 12. From the hopper l0, the coke is moved by a conveyor 13 into a quenching pit 1I.

For each hearth section between the partition walls 68. except that aligned with the pusher 61, there is provided a tube 'l5 extending transversely across the upper part of the coking chamber 50 and adapted to have a fluid fuel and air blown therethrough for internal heating by combustion assaa to transmit heat to oil or the like on the hearth 55 by radiation. The tubes 15 are constructed of stainless steel or other material characterized by relatively high heat conductivity and relatively high coemcient of expansion, for removal of deposited adherent carbon by cooling and subsequent reheating, as described hereinabove.

A plurality of nozzles 16 pierce the inner side walls of the furnace 40 and are so located as to make possible the deposition of oil or the like to be coked in each section or compartment of the hearth 55 'not aligned radially with the pusher 61. Further, a plurality of conduits 11 through the inner side wall of the furnace are similarly arranged for charging granulated coke or the like into each of said compartments.

The roof of the furnace 40 slopes from a high point where a gas outlet 19 is provided for collecting and withdrawing the gases generated during the coking process.

In the operation of the furnace illustrated in Figs. 4, 5, and 6, the hearth 55 is intermittently rotated (by means not shown) in a counterclockwise direction to align each hearth compartment successively with the pusher 61. When the aligned compartment has been cleared by the pusher 61, and the next, compartment has been aligned with the pusher, granulated or powdered coke is admitted through conduit 11 and spread over-the floor of the cleared compartment to act as a cleavage plane between the floor and the coke subsequently formed, Next, the rst charge of oil or the like to the coke is introduced through conduit 16, and the charge is coked for a predetermined time in this position by heat supplied from the stationary burner tubes 15 located near the roof of the coking chamber. These tubes are operated in the same manner as the tubes I1 of the furnace of Figs. 1 and 2. The vapors and gases generated travel along the roof of the furnace toward the take-up conduit 19 through which they are withdrawn from the coking chamber. The compartment is then moved to the next position, where additional coke is added and another charge of oil is added on top of the layer of added coke and that formed from the'flrst charge. This process is continued until the compartment arrives at a position of alignment with the pusher 61 when the coke is pushed oi from the hearth by the pusher or scraper A61 into the hopper to be moved by the conveyor 13 into the quenching pit 14.

Each section or compartment of the hearth operates in the same manner so that coke and gaseous solids of uniform quality are produced continuously.

If desired, it is possible to omit the addition of further charges while the hearth section or compartment travels through the last portion of the furnace while continuing ring in the tubes I1 of said furnace portion to carry the destructive distillation further and to subject the gases and vapors generated to more intensive cracking.

The oil, still residue, tar or the like charged into the furnace for coking is ordinarily suiilciently viscous, and is at once exposed to a coking temperature, so that the oil, still residue or tar ordinarily does not have time to now oil the lower edge of the hearth top before being coked sufficiently to prevent such ow. Further, should such flow off the lower edge of the hearth top tend to occur, such flow is resisted by the steam admitted into the interspace between the hearth 55 and side walls 5I through pipes 6l.

It should be understood that many details of construction and operation may be varied within a wide range without departing from the principles of this invention and without sacrificing the advantages mentioned hereinabove and it is therefore not my purpose to limit the patent granted on this invention otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. Apparatus for coking organic material comprising means defining a coking chamber adapted to have a, layer of organic material spread over its iloor, and a tube extending through the upper part of said chamber adapted to have fuel burned therein to generate heat to be radiated ontosaid layer of material for coking the same, said tube being constructed of austenitic ferrous material characterized by a higher co-efllcient of expansion than carbonaceous material deposited there- ,on on cracking of gaseous products of the coking process on contact with said tube, said tube having its ends anchored in the walls of said coking chamber whereby said tube will be bowed when expanded at an elevated temperature so that carbonaceous deposits on said tube are sheared oil when the temperature of said tube is changed.

2. Apparatus for continuously coking organic material comprising spaced concentric circular side walls, a roof and an annular rotatable hearth between said side walls dening in cooperation with said side walls and said roof an annular coking chamber, radial partition walls on said hearth sub-dividing the same into a plurality of sectors, means for intermittently rotating said hearth, pusher means adapted to remove coke formed in said sectors as said sectors are successively and intermittently aligned with said pusher means, and tube means extending through the upper part of said coking chamber adapted to have fuel burned therein to generate heat to be radiated onto organic material deposited on said hearth for coking said material. said tube means being constructed of material characterized bya higher coeilcient of expansion than carbonaceous material deposited thereon on cracking of gaseous products of the coking process on contact with said tube means.

V3. Apparatus for coking organic material comprising spaced concentric circular side walls, a roof, an annular hearth rotatable between said side walls, means for rotating said hearth intermittently, radial partition walls subdividing said hearth into a plurality of sectors, pusher means adapted to remove coke from said sectors as each sector is successively aligned with said pusher means, conduit means for depositing liquid material to be -coked on the iloor of each of said sectors except that sector aligned with said pusher means, means for depositing coke on the floor of each of said sectors except that sector aligned with said pusher means, and tube means extending through the upper part of said coking chamber adapted to have fuel burned therein to generate heat to be radiated onto material deposited in said sectors except that sector aligned with said pusher means, said tube means being constructed of material characterized by a higher coefilcient of expansion than carbonaceous material deposited thereon on cracking of gaseous products of the coking process on contact with said tube means.

duit for gaseous products at said high point, an annular hearth between said side walls in spaced relationship thereto and rotatable therebetween, said hearth sloping outwardly and being subdivided by a plurality of radial partition walls into a plurality of sectors, means for intermittently rotating said hearth, a pusher member adapted to remove coke successively from each of said sectors as said sectors successively are aligned with said pusher member on intermittent rotation of said hearth, the side wall opposed to said pusher member being pierced by a discharge aperture through which coke pushed out by said pusher member can be discharged, a plurality of conduits for distributing liquid organic material to be coked in compartments not aligned with said pusher member, a plurality of conduits for distributing coke in compartments not aligned with said pusher member, sealing means for sealing oi the interspaces between said side walls and said hearth at the bottom of said hearth, means for admitting steam into the interspaces between said side walls and said hearth, a radial flange projecting inwardly from said hearth, the inner side wall being formed with a groove receiving the margin of said ange in spaced relationship thereto, and a plurality of tubes of austenitic ferrous material within said coking chamber above said hearth for radiating heat generated by internal combustion in said tubes onto material in said sectors not aligned 10 with said pusher member whereby combustion in said tubes may be interrupted periodically and air blown therethrough for contracting the heated tubes to cause shearing off of carbon deposited on said tubes due to cracking of gaseous products of distillation coming in contact with said tubes.

LEV A. MEKLER.

REFERENCES CITED The following references are of record in the le oi this patent:

UNITED STATES PATENTS Number Name Date 1,460,024 Lowenstein June 26, 1923 1,480,045 Bowie Jan. 8, 1924 1,551,180 Thornhill Aug. 25, 1925 1,717,884 Knowles June 18, 1929 1,782,956 Danch Nov. 25, 1930 1,906,864 Knowles May 2, 1933 2,112,401 Hardy et al. Mar. 29, 1938 2,274,066 Jacocks Feb. 24, 1942 2,364,492 Tuttle Dec. 5, 1944 FOREIGN PATENTS Number Country Date 450,240 Great Britain July 9, 1936 515,389 Great Britain Dec. 4, 1939 875,866 France June 5, 1941

Images