US2084491A - Distillation of carbonaceous material - Google Patents

Description

June 22, 1937. H. .1. HOLFORD DISTILLATION OF CARBONACEOUS MATERIAL 2 Sheets-Sheet 1 Filed Dec. 26, 1954 June 22, 1937.

H. J. HOLFORD DISTILLATION OF CARBONACEOUS MATERIAL Filed Dec. 26, 1934 2 Sheets-Sheet 2 Patented June 22, 1937 DISTILLATION or CARBONACEOUS MATERIAL Hastings John Holford, Southampton, England Application December 26, 1934, Serial No. 759,254 In Great Britain January 5, 1934 2 Claims. (01. 202104) This invention relates to retorts for the distillation of carbonaceous material of the type comprising two concentric cylinders having an annular distillation space between them, the outer rality of separately regulatable steam inlet nozzles arranged spaced apart one from another at various heights" on the fixed cylinder, and a plurality of bodies of heat-resisting material of 5 cylinder being fixed and the inner mounted for considerable heat-absorbing capacity are ar- 5 rotation about an upright axis, a plurality of ranged in the inner cylinder in contact thereperforated annular shelves carried by the inner with at a plurality of situations spaced apart cylinder in said distillation space, means for coninthe direction of its length. As compared with tinuously supplying solid material to be distilled known apparatus of the type described, the imdownwards in a thin stream over said shelves, proved construction enables carbonaceous mate 10 and means for heating the interior of the inner rial of widely different character, such as soft, cylinder. highly bituminous coal or cannel. coal, to be Various constructions of retort of the type treated in the same apparatus owing to admittingdescribed have been proposed heretofore which the superheated Steam at us heights atdifwere provided as usual with take-off means for ferent places in the retort, and regulating the 15 conveying vaporized and gaseous distillation quantity of steam admitted at each height. As products from the distillation space, and with the carbonaceous material descends in thin layers means for discharging residues from the retort or in a thin stream, and its total quantity in at its lower end. In these proposed retorts, howthe apparatus at any time is relatively low, the

ever, no provision was made for supplying supertotal heat capacity of the carbonaceous mateheated steam as a distilling medium to the anrial under treatment is Sma a fluctuations nular distillation space or for obviating temin the rate of flow of the carbonaceous material perature fluctuations due to variations in the through the apparatus are liable to give rise to supply of the steam when using the retort for considerable fluctuations in the temperature'of 5 the distillation of carbonaceous materials of varitreatment, and such variations would interfere ous kinds. with the uniformity and efficiency of the process,

In a proposed construction of retort for the dry for which reason the body of refractory material distillation of carbonaceous fuel of a type difof large heat capacity is provided for preventing ferent from that to which the present invention considerable fluctuations in the temperature of relates, in that no steam was employed as a source the treatment by the superheated steam which 30 of heat for the carbonaceous material, a body of might otherwise occur, owing to the employment refractory material of large heat capacity arof such steam as the heating medium, whereof ranged in the inner cylinder was maintained in the specific heat is low. The heat radiator of a hot condition by hot gases from aburner, but large heat capacity is maintained at an elevated that refractory body did not fill the inner cylemp S to act as a reservoir of heat, 35

inder and was spaced away from its walls so that is situated close to the shelves, heats the latter no heat passed by conduction to the shelves over directly by conduction, and thus stabilizes the which the carbonaceous material passed. heating conditions. V

The present invention has for its object to One embodiment of the invention will now be 40 enable carbonaceous material of widely different described by way of example with reference to 40 kinds, such as bituminous coal, peat, lignite, torthe accompanying drawings, in which:- banite, shale, cannel coal and the like, to be disigu s 1 and 1w Show diagrammatically a tilled in apparatus of the type described in such plete distillation apparatu and comprise p manner that the heating conditions in various tively views of the upper and lower halves of the parts of the distillation space can be readilyconapparatus seen partly in elevation and partly as 4.5 trolled according to the kind of material that is a section taken through the Central vertical eXiS undergoing treatment, and be kept substantially thereof. constant, thereby ensuring efficientoperation and Figure 2 is a, horizontal section taken on the line a maximum through-put capacity upon a given 22 in Figure 1, showing one of the shelves in 5 ground space. i plan.

According to the invention, a retort for the Referring to the drawings, in Figure 1 the apdistillation of carbonaceous material of the type paratus comprises a fixed upright cylindrical described above is characterized in that steamcasing 94, within which rotates about an upright supply means for supplying superheated steam axis a heating unit or inner chamber 42 having a to the annular distillation space comprises a pluflue M at the top. The casing 94 and associated parts are supported by an iron framework comprising uprights |25-i2ll and cross members I2, I24, 525, while a set of concrete base members 54 take the weight of the rotating inner chamber 42. A hopper It is supported by the cross member I2 above the casing 94 around the flue l4, and has a sloping floor l3. The flue l4 carries at its upper end a collar l5 supporting rollers i5 mounted upon stub axles between flanges l1 and 18 at a spaced intervals around its periphery. Supported within the upper portion of the hopper are four distributors I9 arranged at right angles (one pair only being visible in the drawings). The distributors is are held together by an annulus 20 of angle section provided with a rack 2| on the under side. A further annulus 22 secures together the inner sides of the'distributors l9 andcarries a track which runs on the rollers [6.

A circular flange 23 is supported by the flue l4 and provides another track upon which run rollers 24 carried in brackets 25 attached to the dis-- trib utors it so as to support their weight. The distributors are thus rotatably mounted in the hopper. They are driven by a motor 25 mounted pon the cross member I2 through an interme- Cdiate shaft 2'5, a chain drive 28, and a pinion 25.

' and thence to the atmosphere;

The hopper l 1 comprises afalse bottom composed of a wire mesh screen 23, the mesh aperture of which may be adjusted by suitable means. Two pairs of rake arms 35 are mounted for rotation above the screen 29 and form part of an assembly of four such arms, the other pair being mounted at right angles to those shown. The rake arms 34 are each united to a ring 3! which carries an inwardly "facing rack meshing with a pinion 32 carried by an axle 33 supported in a bracket 34 united to the flue i4. Mounted upon the axle 33' rotation of the distributors is adjusted to ensure that a distributor is passing beneath the chute 38 when carbonaceous material is issuing therefrom and the rotary movement of rakes 35 is correlated to that of the distributors to bring about maximum distribution of the carbonaceous material upon the surface of the screen 29.

The material passing through screen 29' falls down the inclined bottom I3 of the hopper and passesthrough an annular opening 45 beneath which are located a plurality of outlet valves 4! which may rotate under the weight of the material delivered to them to allow it to pass whilst maintaining a substantially gas-tight seal between the hopper and the casing 94 below. The

upper end of the inner chamber 42 has a hemispherical roof 43, beneath the inlet valves 4 l, and the roof 43 terminates in a central vertical junction pipe 44 which enters the fluev I 4. The pipe 44 communicates with the interior of chamber 42 and serves to conduct waste gases or vapour from the interior of the heating chamber 42 to flue M The chamber 42 isrotatably mounted. A, gland 45 is provided between the flue and pipe 44;

Referring to Figure la it will be seen that chamber 42 is composed of three superposed open-ended circular sections 42, I42, 242 which are united together and also united to 'a bottom central aperture 48.

' only of the said blocks appearing in the figure.

The rollers run upon an annular The base plate lfl is also provided with an outwardly facing flange 55 carrying a rack 56 on its underside which engages with driving pinions 51' and 58 on either side of the apparatus. The pinions 5'! and 58 are mounted upon axles 59 and" 65 which are supported for rotary movement in suitable bearings which in turn are mounted upon I-sectionangle irons. Fast and loose pulleys BI, 62 and 63, 54 are respectively mounted on shafts 59 and 65 for driving'the pinions 5'! and 5B,. In".

order to equalize the thrusts upon the chamber 42 two freely rotatable pinions similar to pinions 51 and 58 are arranged to engage with the rack 55 on. a line at right angles to the shafts 59 and "Gil.

and are disposed pairs of abutments 65 upon' Below, but out of contact with pinions 51 each side ofthe' pinions. Should the chamber depart from its vertical alignment the abutments serve to jam the pinions and to restrict rotation of the inner chamber.

The inner' chamber 42carries firebrick ele-- ments 66, 61, 6B- and.69 supported within it by flanges'lfl, H, 12 and "i3 integral therewith.

The refractory elements are each formed with a central aperture through which passes a rod 14 carrying dampers 15, 15 and 11 for controlling the flow of the heating medium through the elements to the flue.' Cross members 18 recessed in the refractory elements slidably engagerod 14 so that it may be moved in a vertical direction but is restricted from sideways movement. At the lower end of the "inner chamber, rod 14 passes through a gland 19 carried by a circular plate which works in a gland B I, for example packed with asbestos supported within a channelgcan ried by the base-plate. The lower end .of the rod :14 terminates in a rack 82 which engages with a pinion 83 carried at one end of a shaft 84 which is mounted for rotation in suitable brackets via'a worm gearing 85 which may be actuated from a hand wheel 86. Upon rotation of the hand wheel the rod 14 may be raised or lowered, to bring the dampers 15, "I6, and I1 into or out of engagement with the lower ends;

are fully open and the heating medium will follow a tortuous path and will pass around the outside of the upper refractory elements and through their cross passages 87 before escaping to the.

flue; asa rule, however,-when the retort is in full-operation, the dampers will be raised onlyslightly from their seats to permit the heating medium to -flow inpart around the refractory elements and also through their central spaces.

The inner chamber is heated from a group of three nozzles 88 which pass through plate 80. and are united at their lower ends to a junction box 89 connected to a steam or gas line 90 and a compressed air line 9|. When steam is used this:-

is supplied to line from a superheater and the superheated steam from nozzles 88 passes upwardly in contact with the refractory elements and raises them to a high temperature. The chamber 42 containing the highly heated refractory elements thus serves as a heat reservoir. When it is desired to supply combustible gas to the nozzles 89 line 90 is connected to a gas supply by means not shown and compressed air is introduced at the same time via conduit 9 I.

Upon the outside of chamber 42 are mounted a plurality of superposed circular shelves 92, each of which may be built up of three arcuate sections, as shown in Figure 2-, and is provided with an opening 93, say over an arc of 10 around the shelf plan, as shown in Figure 2. The shelves are so positioned that the openings in adjacent shelves are displaced circumferentially; preferably the displacement is such that the openings form a helix. The inner chamber 42 is surrounded by a fixed casing 94 which forms be tween itself and chamber 42 a distillation chamber. A plurality of scraper or rabbling arms 95 are carried by casing 94 and project inwardlytowards shelves 92 and terminate just out of contact therewith. The finely divided carbonaceous material issuing from outlet valves 4i drops upon the hemispherical roof 43 and is distributed therefrom upon the top shelf. Upon rotation of chamber 42 the material is agitated and turned over by the upper rabbling arms and eventually drops through the first opening 93 on to the second shelf whence it proceeds from shelf to shelf down the distillation chamber. During its passage downwardly the carbonaceous material is subjected to heat conducted through the shelves and radiated from the heat reservoir constituted by the firebrick elements contained within the inner chamber 42. Simultaneously superheated steam is introduced in contact with the carbonaceous material from nozzles 96, I96, 296, 396 and 496 arranged in four vertically disposed banks (two banks only appearing in the drawings) which are each connected via steam conduits 91, I91, 291, 391 and 49'! with vertical steam pipes I98. The steam pipes I98 are in turn connected by pipes I99 and 299 to annular steam headers ZIlI and 292 serving to conduct superheated steam to each bank from a superheater. Each pipe I99 and 209 is provided with a cut-off valve 293, 294, respectively, which may be operated to enable steam to be delivered simultaneously to both ends of the vertical pipes I98 or at either end alone. In addition, steam conduits 91 to- 49'! each carry a cut-off valve so that the quantity of steam and points of steam introduction may be varied thus affording control over the temperature conditions obtaining at different zones in the distillation chamber. The products of distillation pass via an annular opening 98 at the top of the distillation chamber into a condenser 99 provided with a sump I99.

The casing 94 is surrounded by an outer casing IilI which opens at the top into the condenser 99. This is cooled by radiation into the atmosphere and also by water circulated through appropriate coils of pipe or around a jacket as may be found convenient. In addition, casing 94 is pierced with a number of apertures I92 through which volatile distillation products may escape from the distillation chamber into the outer casing IDI and thence to the condenser 99. Gas pipes I03 open out of the outer casing NH and are united via branches I94, the flow of gas there- Vided adjacent the main control valves. The gas through being controlled by valves I95, I96 and Sampling cocks I99, I99, and H9 are propipes lead into a tank I I I in which an extension of a pipe H2 dips under water or other fluid sealing medium. A conduit H3 opens into tank IH above the liquid surface and is connected to a suction pump which distributes the gas coming from the distillation chamber to washers and scrubbers in the usual manner. Ihe bottom of the chamber formed between the outer casing I9I and casing 9-3 is drained by a pipe IE4 opening into tank II I, the flow of condensate therethrough being controlled by a suitable valve.

. At the base of the distillation chamber is located an annular box I l5 covered by a grating I I9 over which sweep a plurality of rakes i I? carried by the inner chamber 49. The rakesserve to agitate the fully carbonized material dropping upon the grating from the last shelf and to advance it to an opening I I9 in the grating below, in which is mounted a screw conveyor I i9 suitably driven. Whilst the carbonized material is advanced towards the conveyor it is also drained of any condensed volatiles (tar, etc.) which pass through 1 the grating into box I I5 and thence by a valved pipe I29 below the liquid in tank I I I. The material issuing from the screw conveyor is periodically released through a trap IZI and may be cooled by a water quench 22I located above the- 1 trap.

In order to secure a gas-tight seal at the lower end of the inner chamber 42 there is provided a downwardly-extending web I22 of V T-shaped cross-section which dips below the surface of 3 water or sand contained in an annular trough I23 and which rotates together with the inner cham- -er.

In the operation of the apparatus finely divided carbonaceous material is fed from chute 39 into the rotating distributors I9 'and'passs 'through the mesh screen 29 and thence via outlet valves M on to the dome 43 of the rotating inner chamber 42. The curved surface of the hemispherical dome 43 acts to distribute the falling material,

evenly upon the surface of the uppermost shelf. The spread material is continuously agitated and turned over under the action of therabbling arms 95 which eventually sweep the material through the aperture 93 in the top shelf so that it falls by gravity upon the second shelf. This action is repeated throughout the series of shelves down the length of the distillation chamber and the progressing material is submitted during its passage downwardsto the action of steam (superheated to for example 500 C.) which issues from nozzles 99. This admitted steam itself supplies part of the heat required. At the same time heat is radiated from the inner chamber and serves to maintain and stabilize the temperature conditions prevailing in the distillation chamber. The car-' bonaceous material undergoes distillation under the combined action of the heat and the steam mostatically operated. The condensation occurring in the condenser '99 ensures a continuous flow of vapours to the condensing chamber, most of the condensible vapours passing out by wayof opening 98. "The non-condensible gases from-the just the temperature conditions according to the carbonaceous material which is to be employed.

' The following ExamplesI to IV set forth temperatures observed from fourteen equally spaced pyrometers arranged in the casing 94 and extending from the top of the inner chamber to the outlet end thereof. The temperatures were varied for different carbonaceous material by adjusting the cut-off valves in the steam conduits.

Example I Example II Material used:

Bituminous coal ground to pass a screen having 50 mesh to the lineal inch.

Material used:

Industrial coal ground to pass a screen having 50 mesh to the lineal inch.

95 110 160 (Gas) 200 240 280 (Gas) 220 320 280 360 320 400 380 (Maximum (Maximum 420 production production of of gas and gas and tar) tar) 380 400 320 370 290 320 250 210 Example III Example IV Material used: Material used:

Low volatile coal ground to pass a screen having 50 mesh to the lineal inch.

Cannel coal ground to pass a screen having 50 mesh to the lineal inch.

Approximate temperatures in G. Approximate tgmperatures In Example I it was found that non-condensible gas started to be evolved at approximately 220 C. whilst the maximum production of gas and tar took place near the pyrometer which indicated a temperature of 400 C. Corresponding points for the beginning of gas evolution and the maximum production of gas and tar are shown in the Examples II, III and IV.

In order to take samples of the gases issuing into. the gas chamber between casing 94 and the outer casing IN the test cocks I08, I09 and IIO may be used in conjunction with valves I05, I06 and I01. Thus by closing valves I05 and I06 and pening cock IIO a quantity of gas can be extracted through the test cock and analyzed. If cock I I0 is then closed and valve I06 opened and a further quantity of gas withdrawn from cock IE9, a second analysis may be obtained. If thisoperation is repeated in respect of gas collected from test cock I08 a rough estimation of the constitution of the gases leaving the gas chamber at the three levels through pipes I03 may be obtained.

It will be understood that the speed of rotation of the inner chamber 43 may be regulated along with the rate of introduction of the carbov naceous material via the hopper II. It is thus possible to secure conditions which will enable an optimum. yield of desired volatile products to be obtained having regard also .to the possibility of varying the temperature of inner chamber 43 and the degree of superheating imparted to the steam. In an alternative construction the annular shelves 92 may be replaced by a continuous helix along which the material may be moved gradually from the top to the exit end of the distillation chamber. When a helical shelf formatlon is employed it is of course necessary to modify the mounting of the rabbling arms by providing for them to have freedom of vertical movement so that the inner chamber may rotate without jamming.

I claim: I

1. A retort for the distillation of carbonaceous inaterial'comprising a fixed casing, a heat radiator of large heat storage capacity'within the casing and mounted for rotation about an upright axis, a plurality of shelves in tiers encircling and attached to the heat radiator, means for continuously supplying solid material to be distilled'in a finely divided state to the top shelf and for distributing it evenly thereupon as a thin layer, each shelf having an opening to permit the passage of material from shelf to shelf, stationary inward projections carried by the casing for working the materialon the shelves and downwardsthrough said openings, means for heating said heat radia tor, a plurality of steam inlets that open at situations spaced apart at different heights into the.

distillation space occupied by the shelves, separate regulating means for each steam inlet, takeoi'f means for: conveying vaporized and. gaseous distillation products from the said distillation space, means for discharging residuesffromthe "a plurality of valve-controlled.outlet pipes for volatiles connected at different heights to said collecting space.

2. A retort for the distillation of carbonaceous material, comprising two concentric cylinders having an annular distillation space between them, the outer cylinder beingfixed and the innermounted for rotation about an upright axis,.a plurality of perforated annular shelves carried by the inner cylinder in said distillation space, means for continuously supplying solid material to be distilled downwards ,in a thin stream over said shelves, means for heating the interior of the inner cylinder, steam-supply means for supplying superheated steam to the distillation space comprising a plurality of separately regulatable steam-inlet nozzles arranged spacedapart one from another at various heights on the fixed cylinder, a plurality of bodies of, heat-resisting material of considerable heat-absorbing capacity arranged in the inner cylinder in contact therewith at a plurality of situations spaced apart in the direction of its length, take-01f means for conveying vaporized and gaseous distillation products from the said distillation space, and means for discharging residues from the retort at its lower end.

HASTINGS JOHN HOLFORD.

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