US1781871A - Method and apparatus for distilling solid carbonaceous material - Google Patents

Description

H. L. D QHERTY METHOD APPARATUS FOR-DISTILLING SOLID CARBONACEOUS MATERIAL Nov.\18, 1930.

Filed May *8, 1925 2 Sheets-Sheet 1- MATERIAL I Nov. 18, 1930. H. 1 DOHERTY METHOD AND APPARATUS FOR 'DISTILLING SOLID CARBONACEOUS 2 Sheets-Sheet 2 Filed May 8, 1925 wbemtoz HENRY L. QOHERTT Patented Nov. 18, 1930 HENRY L. DOHERTY, OF NEW YORK, N. Y.-

METHOD arm arram'rus FOR DISTILLING somn cannonaonoos lineman [Application filed m a, 1925. Serial m. 28,866.

- his invention relates to the control of fuel distillation and more articularly to a methupper wall.

0d of and apparatus or controlling the distillation of fuel by direct heat transfer with hot non-combustion-supporting gases.

In operating gas ing units of the sha t type'wherein. raw fuel is introduced into the top of the shaft and is gradually distilledor carbonized during its downward passage through the upper part of the shaft by an upwardly flowing current of culty is often encountered in securing a uniform distillation and/or. asification of the fuel during-its passage t rough the shaft.

.- One of the principal causes of this non-uniof the fuel is that the heatform distillation ing gas. seeks out and follows paths of least resistance in its upward passage through the shaft, and often develops channels through the fuel bed. 1 Once a channel is formed 'more and more of the gas will enter it because the fuel in the channel. will be more rapidly and completely carbonized by the larger volume of gas passing thercthrou'gh, and the coke or carbonized fuel in the channel will thereafter ofier' much less resistance to the passage of the "as than the raw and partially carbonized or plastic fu'elfialong the walls f of the channel." This channeling of the fuel bed by the hot gas distllling medlum occurs most frequently along the inner-walls of the shell. Usually when channels aredeveloped the capacity of the furnace is lowered and some of the fuel passes through the shaft without undergoing complete distillation and/orcombustion.

The shaft retort or generators commonly used forfuel distillation by hot gases are generally equipped with a single fuel charging inlet at the top of the shaft and a single gas outlet leading off from one side of t e In a retort of this type the channeling? tendency of the hot gas distilling medium is usually very marked. The gas naturally seeksout the eas1est path toward the gas off-take, and after it has once opened a channel through-the fuel bed of such a retort, it is almost impossible to block'the channel or to force any of the gas t are most often-(level generators and carbonizaim:

through that portion of thefuel bed which lies outside the channel. Moreover, inshaft retorts, of this type, especially when the gas is removed under a vacuum, the channels ed through the fuel along that portion of t e wall which lies immediately below the single gas offtake, where the suction created by-the outgoing gas is strongest and where raw fuel to chokethe channel can be introduced"only-"with the greatest difiiculty from the centrally located charging inlet. c 1 i p The primary object of ,the resentinven-' tion is to prov1de a method an apparatus by I which sohd volatileacontaining carbonaceous fuel may be distilledfll'ifqrmlyby direct heat transfer with a current of hot non-combustion-supportinggas;

With this obje'Tct 'in' view one 'featureol. the invention ,-contemfpla distributing, a

rmly through p ngthrou h a shaft retort andf'passin ais in uni orln or variable concentrations ountercurrently throughout the whole up i the fuel bed. I j .i V

Another ob ect of 'the inve'ntion isto provide a method of and apparatus forcontrol;

ling thedistillation of saidflvolatile-containing carbonaceous fuelflin operations where hot non-combustion-supporting gas is-used as the distilling medium. 3 To accomplth this object anotherfe'ature of the invention contempl'ates'distilling a bed of said fuel in a shaft retort by a current of hot gas passed upwardly throughthe fuel and removed selectively from'all or. any portion of the upper cross section of the fuel bed.

Another feature of the invention contemplates adding said.volirtilecontaining carbonaceous fuel jperiodically to substantially the whole or any ip'ortion'of the upper. cross section of a. bedof said fuel undergoing dis tillation by direct heat transfer with a current of.hot non-combustion-supporting gas.

With these and other objects'and features I in view, the inventionconsists essentially in the method of and apparatus for controlling distillation of solid volatile-co1'1:t1 1ining carwe s section ol. 7 5 I I bona'ceous fuel hereinafter described and particularly defined 111 the claims.

The various features of the invention are illustrated in the accompanying drawings, in which Fig. 1 is a view in sectional elevation of the upperpart of a shaft retort equipped with a multiple gas otftakc and fuel chargingdevice' section taken on the line 22 of Fig. 1; and

Fig. 3 is a vertical cross section through a shaft generator equipped with a modified form of the multiple gasofl'take and fuel charging device shown in Figs. 1 and 2 and also equipped with a fuel discharge mechanism.

The method of controlling distillation of solid volatile-containing carbonaceous fuel constituting the preferred form of the present invention as carried out in the apparatus illustrated in the drawings consists in introducing said fuel, such for example as wood, lignite or bituminous coal, oil shale, etc preferably in admixture with a small proportion of coke or other non-volatile-containing heat and abrasion resistant refractory material, periodically from a hopper 1O into'the top of a shaft retort or generator 12 through any one or more or all of a number of charging gates l i'and necks 16, and through a plurality of depending ducts or chambers 18 which open into the shaft at their lower ends.

Each of the chambers 18 preferably has the same cross sectional area as each of the others, and the chambers are preferably arranged in rows to form a partitioned charging box which occupies sustantially'the whole upper cross section of the shaft. The volatile-containing fuel is supported in and gradually passed downwardly through the shaft in a column and as it advances through the upper portion 19 it is gradually heated and distilled by a current of hot gases rising upwardly through the shaft toward a number of gas ofi'takcs 20. \Vhen the shaft is being used as a gas generator, the hot gas for distilling or carhonizing the fuel may be generated by introducing combustion supporting gases through a conduit 22 and a blast nostril 24 into that portion of the fuel bed lying immediately adjacent rack back or circumferential arch 26. When the shaft being used solely as a distilling or carbonizing chamber the hot gases required for distilling. or carbonizing the fuel may be introduced into the shaft from some outside source through 110stril 24. in any case a sufliciently large volume of gas must be passed through the upper zone of the fuelbed and the gas must have a temperature sufficiently high so that all the fuel will be distilled to the desired degree by sensible heat given up by the gas during its passage upwardly through the shaft.

-To counterbalance the tendency of the completely closed in order to force the up-.

Wardly flowing gas to leave the channel and pass through those sections of the fuel bed which have been-deprived of the necessary volume of gas to complete distillation during the period inwhich the channel was developing. Thus when one or more,chanrnels is formed along theinner walls of the shaft, the large proportions of the gas which are passing off through those offtakes leading from the peripheral section of the shaft at points immediately above these channels may soon be detected by means of meters or other indicating devices which are preferably connected to each ofl'take (not shown).

By closing or partially closing the valves in these particular oiftakes some or all of'this gas will be forced to travel transversely through the fuel bed toward the axially located olftake and toward the other peripheral offtakes. In general when the combustion supporting gases or the heating gases are introduced through an inlet in the periphery of the shell, as through conduit 22 in the design illustrated in the drawings, a uniform distillation of the fuel may be best secured by keeping the valves of the offtakes leading from the upper peripheral section of the shaft partly closed, and by allowing the greatest proportion of the gas t'o pass out through the axially located oiftakes, so as to counterbalance the tendency of the gas todevelop channels ,along the inner wall of the shaft between the peripheral gas inlet and the peripheral as offtakes.

All of the gas 0 takes 20 are connected'to extension 30, equipped with valves 32, of a common manifold 34, and the mixture of heating gas and volatile. products of fuel distillation which is removed from the top of the shaft through the several ofl'takcs passes through the manifold into-a foul gas main 36, and is thence'preferably conducted through condensing scrubbing and purifying equipment (not'shown) to a storage holdin which the distillation takes place more.-

slowly, and also the fuel in the peripheral sections of the column may be more rapidlyv advanced through the shaft to counterlrtlance the preferential distilling tendencies of the heating gases. Thus in Fi 3 ofthe accompanying drawings there is sdiown a shaft having ducts 18 arranged in an annular concen. tric form over its entire upper surface. to allow for the separate and selective charging and distillation treatment of two or more distinct types of solid volatile-containing carbonaceous fuel, if so desired. There is also shown in Fig. 3 one type of fuel-supporting and discharging mechanismfi-lS designed to serve as a positive support for a column of fuel in the. shaft and operable to advance fuel at a controlled rate through the axial and peripheral sections of the shaft in the manner above referred to. Essentially the discharge mechanism 38 illustrated in Fig. 3 comprises three distinct stationary and movable elements mounted in the lower portion of the. shaft in such a way as tocompletely fillthe lower cross section of the shaft and thereby afford a positive support for a column of fuel therein. The'first element of the discharge mechanism 38 illustrated comprises an upright stationary -.one-shaped member 40 mounted in the axial portion of the shaft at a vertically spaced distance, above the second element which in turn comprises a movable annular ring or plough member 4-2 supported by and arranged to oscillate back and forth across the surface of an annular stationary plate 44 comprising the. lower and third element of the mechanism 38. The cone 40 and the plate 44 together serve as a positive support for a charge of fuel in the shaft, and the oscillating movement of the ring 42 serves to discharge fuel from the surface of plate 44 through a central opening 46 lying bencath the cone 4-0 opening 48 lying between the peri )hery of .the plate 44 and the inner walls of t e shaft.

The rate atwhich ring 42 is oscillated is governed in accordance with the rate at which it is desired to advance fuel downwardly through the axial and peripheral portions of the shaft. Means, illustrated as hydraulic reci irocating engines 50 mounted outside the she t-and. connected by connecting rods 52 to the ring 42, serve to impart an oscillatory mot-ion to the ring 42 and to control the rate ripheral portions and path of travel of the ring in accordance with the rate at which it is desired to advance fuel downwardly through the axial and peofthe column of fuel supto my Patent 1,426,159, dated August 15,

and through an annular.

ported in the shaft. For a more'complete'itie scription of the fuel supporting and discharging mechanism 38 reference is "hereby made 1922. i l

''l he val-res .52 in each of the xtensiou or i, 7 r Y \vitlnlrawal pipes oOol the ma .oldall prov de additlonal means for governing the selective removal of gas from any three or more of the larger portions of the cross see.-

tion of the shaft. Thus in addition to n'oviding for a selective removal of gas through each one or more of the chambers 18 and the outlet conduits-20 by valves 28, the valves 32 provide a separate control for the selective removal of gas through each row or series of chambers 18 and conduits 20.

The provisions for selective gas removal from the shaft andfor preferential control of the volume of solid volatile-containing carbonaceous fuel added to each section of the shaft makes the method and apparatus of the present invention particularly suitable for the distillation treatment of two'or more distinct kinds of said fuelsimultaneously in one shaft unit. Thus,-one'kind of fuel may be chargedthrough one row of charging necks and distilled during its downward passage. through the section of the shaft lying immediately beneath these charging necks by an upwardly flowing current of hot gases, the gases evolved therefrom being removed through the row of outletconduitswhich lead off from the topof the shaft adjacent the corresponding chargingnecks, While an other row of charging necks, another section of the shaft, and another row of gas outlets may be used simultaneously in respectively charging, distilling and removing gas distilled from another kind of fuel. Likewise, alternate charging necksand chambers 18 may be used for introducing two or more distinct kinds of fuel into the top of the shaft in alternate vertical layers. For example coal and coke may be. introduced into the shaft throu h alternate charging doors and chambers, fieing thus directed through the shaft in alternate vertical layers, such for instance as a central core of coke surromnled by annular cylinders or coal and coke of an ever increasing diameter. When such a procedur, 2 is contemplated the fuel hopper 10 must ofcourse be .m1t.itione(l into separate com pa rtthe outlet'of the channel.

over substantially the full top area of the shaft is that with this arrangen'ient there is substantially no preferential suction created by the gaspassing outthrough any one outlet and the hot gas distilling medium will be,

drawn through each section of the fuel bed at substantially the'same rate as through each .ofthe others and-therefore-will not be so apt to open-and develop channels through any one section .of the bed as it would if there were only one oiftake Another advantage of this arrangement is that if channels do form, they may be quickly choked up or obliterated by a preferential charging of the fuel into the top of the bed above the outlet of the channel, and by a selective removal of the gas distilling medium through, other outlets than those leading off directly'above Another ad vantage is that if for instance, fuel falls more rapidly through the outer zones or peripheral sections 'ofthe shaft, it is possible to charge fuel more'rapidly into those zones, and if any particular zone of .the fuel charge gives up one kind 'of gas as distinguished .from another kind of gas, these differentforms of gas can be removed separately from the top of the shaft. 1

It is not intended that the invention be limited to the particular arrangement of apparatus illustrated in the drawings. The combination fuel charging and gas removal chambers 18, a plurality of which make up the charging box at the top of the shaft, may

have a rectangular, circular or elliptical cross section, and they may be arranged within the partition and charging box in concentric circles,squares or other shaped divisions. In the preferred arrangement, however, each chamber 18 is equipped with one or more in-.

'dividual gas ofi'takeconduits having individual valves and one or more individual fuel charging necks having individual charging gates so that the chamber can be used simultaneously as an outlet for the gas evolved in the shaft and as an inlet for the fuel to be distilled. By this arrangement the sensible heat of the hot gas distilling medium and of the volatile products distilled from the fuel can be most effectively utilized in preheating raw fuel.

The term solid volatile-containing carbonaceous is used in the claims as a broad generic term to cover combustiblecarbonaceous or bituminous material such as wood, lignite or bituminous coal, oilshale, peat, and like solid carbonaceous materials having volatile constituents separable therefrom by distillation at an elevated temperature,

In order to secure large yields of products ofhigh quality from the fuel carbonization, the heating gas employed is preferably combustible gas, he, one containing little or no uncombined oxygen or air. Accordingly in the specification and claims this heating gas has been described as a non-combustion sup umn to distil the fuel by heat transfer therewith, and removing the mixture of gas distilling medium and volatile products evolved from any portion of the fuel selectively from "the top of the fuel column so as to force the gas distilling medium to'distribute itself in uniform concentrations through eachcross section of the fuel column during its upward passage therethrough.

2. A method of controlling distillation of solid, volatile containing carbonaceous fuel,

which comprises separately adding portions of said solid fuel periodically and selectively to the various parts of the upper cross section of acolumn of fuel passing downwardly through a shaft retort and adding said fuel to each of said various parts at such a rate that the fuel in the column will be distilled to a uniform degree, during its passage through the shaft by direct heat transfer ,with an upwardly flowing current of hot non-combusflop-supporting gas. a

solid volatile-containing carbonaceous fuel which comprises introducing said fuel periodically through each one of a plurality of charging gates into the top of a shaft retort, passing the'fuel down-wardly in a column through the shaft, introducing a hot noncombustionsupporting gas into the lower portion of the column, passing the hot gas upwardlythrough the column in direct heat transferring relationship with the fuel to distil the fuel and drive off its volatile components, removing the mixture of gas distilling medium and volatile components of the fuel selectively through one or more of a plurality of gas offtakes at the top of the shaft, and controlling the addition of said fuel to and the removal of said gas from each portion of the upper cross section of the shaft to distil the fuel in each crosssection of the column to a uniform degree during its passage through the shaft.

4. A method of controlling distillation of o. A method of controlling distillation of solid volatile-containing .carbonaceous fuel whichcomprises adding said fuel in admixture with coke to any portion ofthe upper cross section of a column of the mixture advancing downwardly througha shaft retort, distilling said fuel by passing a hot non-combustion-supporting gas upwardly through the column in direct heat transferring relationship therewith, and removing the gas and volatile products distilled from any portion; of the fuel selectively from the top of the shaft so as to force the gas to distribute itself substantially uniformly throughout each cross section ofthe column during its upward passage therethrough.

5. A method of controlling distillation of solid volatile containing carbonaceous fuel, which comprises adding two or more kinds of said solid fuel simultaneously to separate portions of the upper cross section of a shaft retort, directing the fuel downwardly in separate vertical columns through the shaft and distilling them by direct heat transfer with upwardly flowing currents of hot non-com bustion-supporting gas, and removing the volatile products evolved from each fuel sep;

arately and selectively from the upper portion of the shaft.

6. A method of controlling distillation of solid volatile-containing carbonaceous fuel which comprises adding two or more kinds of solid fuels simultaneously to separate portions of the upper part of a fuel bed in a shaft retort having a gas outlet near its top, directing the fuels downwardly in vertical col-- umns through the shaft, distilling the volatile-containing fuels by direct heat transfer with an upwardly flowing current of hot non-. combustion-supporting gas and causing the gases passing upwardly throughthe fuel -bed to pass transversely of the vertical layers in flowing to said gas outlet near the top of the shaft.

, 7. A method of controlling distillation of solid volatile-containing carbonaceous fuel which comprises passing a current of hot gases upwardly through a column of the fuel advancing downwardly through a shaft retort and distilling the fuel by heat exchange with said gases, passing the fuel in some portions 'of the column through the shaft at a faster controlled rate than that in others and adding more fuel to certain portions of the upper cross section ofthe column than to others.

8. An apparatus for controlling the distillation of solid volatile-containing carbonaceous fuel distilled by direct heat transfer with hot gases, the said apparatus comprising an upright shaft retort, a fuel hopper superimposed thereon having a plurality of charging necks leading from its base into the top of the shaft over substantially the entire upper cross section thereof, a gate in each charging neck for controlling the admission of fuel through each neck into the top of the shaft, a plurality of vertical chambers each having an open bottom and being suspended in the top of the shaft beneath but in communicationwith a respective charging neck for directing thefuel in vertical columns in its downward passage through the upper portion of the shaft, and means for flowing distillation vapors at a controlled rate selectively through one or; more of the said vertical chambers in a direction countercurrent to the fuel flow therethrough.

9. An apparatus for controlling distillation of solid volatile-containing carbonaceous fuel distilled by direct heat transfer with hot gases comprising an upright shaft retort having a multiple compartment fuel charging box suspended in its top and filling substantially the whole of its upper cross section, a gas ofltake conduit leading off from the shaft through each compartment of the charging box, and a valve in each conduit for controlling the volume of gas removed from the shaft through each compartment of the charging box. v

10. An apparatus for controlling distillation of solid volatile-containing carbonaceous fueldistilled by direct heat transfer with hot gases comprising an upright shaft retort, a number of chambers of substantially uniform cross section suspended at regular intervals within the top of the shaft and opening into the shaft over substantially its entire upper 1 HENRY L. DOHE TY.

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