This inventiontrelates" to the drying of eral aggregate or like material under variable heat conditions, and a process therefor, which will be more efficient .and less costly to operate than those heretofore proposed. g Referring to, the accompanying drawings forminga part of thisspecification and in which like partsare designated-by like numerals+ Fig. 11s a vertical longitudinal sectionalview .of an apparatus made in accordance with this invention; I Fig. 2 15 a transverse sectional view taken as on the line 2-2.of Fig. 1 and looking in the direction of the arrows;
Fig. 3 is atransverse sectional view takerras onthe line 3-3 of Fig. l and looking lathe direction of the arrows; 1 A
' Fig. 4 is a transverse "sectional view taken-as on the line 3 & of Fig. 1 and .looking in the direction, of the arrows; and v as well asan exhaust means for the gases utilized. v This invention constitutes an improvement over that disclosed in 11.8. Letters Patent No. 1,641,108 granted August 30, 1927, to Lawrence B.',West and entitled Apparatus for drying and heating material, and No. 1,871,934 granted August 16, 1932, toLawrenceB. West and Marion P. Wallentitled Process of and apparatusfor drying material, both patents disclosingtherein a double-shell drier. r Intheart of. drying mineral aggregates for asphalt paving and other purposes, it is a well known fact .that somecharacters of aggregate material, especially those having a large clay content, will dry better in a single-shelldrier, whereas other materials willdry more readily,
and especially more economically, in a double 'shell drier. Therefore, a combination of a double-shell and a single-shell drier in accordance with this disclosure will meet all of the requirements in the drying of all kinds of mineral aggregate, thereby lowering the initialiand operating costs.
Further, this combinationfoi driers will pea niitithe feeding of onekind or grade oilaesra ,eatifnaterialin 'onneend ft el'arn r m a another-kind orgracle into the opposite end oi theiapparatus, the two kinds ,oi a gregate.
being conveycd'in streams of opposite directional I flow within the app one kind wiir-j mixture of the" two" an area where the iiih'er kind, the ereaiterbeing con! veyed, in a stream disposed within one of the first mentioned streams, to the discharge end the material, hot gases and/or cooling air iar 5 passed over the materialto'obtainthe desired results, this invention'thereby lending itself admirably to either the production of hot-mixed or cold-mixed asphalt. f
It is also ade'cided advantagefin drying" min- 1 eral aggregates, in the operation of an asphalt plant, to'beable to operate economically" at a lower capacity. and also to operate at anextremely high capacity. When a low'capacity is desired the materialis fed only into one end of the apparatus, but by feeding the material intoboth'en the apparatus will be operating at 100% capacity, I v g I Y Referring to the 'drawings' a stationary iur nace '2 is indicatedattached to the breeching 3 I gay. andprovidedwitlia source of heat such as an Fig. 5 is a diagrammatic representation of a feeding means for the material being treated,
cylindrical casing orfdrum fij'secured thereto as by the obl que partitions "l, as was the case distclosed in said patentsf'ljheouter drum 5 posed between thebreeching 3 and a, similar brefeching fiat opposite ends of the'drum, sealing rings such as 9 being providedffor preventing any material loss ofhot'gas'esto the atmosphere, the sealing rings cooperating with-annular rings or collars such as I!) carried by the breaching and providing means for'the passage of material and gases betweenthe breeching and said The inner end'jof'the 'innerdrum o is disposed at approximately the middle of the outer drum, but, the "opposite 'erido f 't'he inner drum extends beyond the end of the outer druinand through the breechingfi. The extending end of the inner i0 drum carries external'screws' such as it bymeans of whioh material is. forcedfrom the lower region of said breaching into ,the I compartments j l2 termed by, the partitions l between the inner and outer drums, such material being ied in'to the breeching through-the aperture iii therein by any suitarile meanssuch as a conveyor it.
, 'Inclined'fiightssuch as km the'partitions 'i' move the materialprogrejssivelytoward the inner end or the izmer drum, and flights su'chas' it so within each compartment" cause" the material'to Ice-cascaded orshowered across the compartments so as to come into more intimateconta'ct I with the'liot drying gases; during the rotation oithe apparatus. when the material reaches Blithe. inner end of said compartments it drops of the apparatus. During such conveyance. of
through valves or openings formedin the wall of the inner'drum and is. started by the inclined flights l8 in a reverse directional movement within the inner drum toward the discharge chute IS, a great plurality of buckets'.or cups 20 attached to the inner surface of the-inner dmm assisting in this reverse movement and causing a cross-shower of the material within the inner drum as clearly indicated in Fig. 2. Therefore it will be understood from the description so far that material fed into the breeching 3 is caused to move to the right as seen in Fig. 1 within the compartments l2 by the flights l5, but after reaching the valves I! of the inner drum, the
7 material passes through said valves and is caused by the buckets 20"to be moved within the inner drum to the leftas seen in said Fig. 1.
, Hot gases created by the burner 4 are caused by a suitable exhaust fan to travel from the furnace 2 through the inner drum to the extreme inner end thereof, and thence in the opposite direction through the compartments |2, between the inner and outer drums, to the breeching 3 and out through the flue 2| to a dust} collector or classifier 22, and thence to atmosphere through the exhaust fan, any dust particles carried by the gas flow being caught or trapped'in g the collector-22 and'rec'overed from the discharge 23 thereof, a suitable valve 24 beingprovided in the flue 2| to regulate the amount of airand gas passing through the device.
Up to this point the apparatus is substantially a duplicate of that disclosed in said patents.
The end of the outer drum adjacent the breeching 8, carries a cone such as 3|! axially thereof, which cone is so directed as to positively impel material into the drum, saidcone secured to the drum as by the spacing plates 3| for rotation with the drum. The wall of the breeching at the juncture with the drum-is suitablycut away in order that the material admitted through the opening 32- (as bya duplicate of the conveyor 4) may reach the interior of said drum where the material is picked up by the plurality of buckets or cups suchflas 33 and moved to theleft as seen in Fig. 1, tol'meet-the material travelling in the reverse'j'direction through the compartments l2. v
'wall of the breeching 8 is cut away in substan- The opposite tial registry with the end of the bone 33, and covering this cut-away portion of said wall is a seebreeching} .(and a substantial duplicate of flue 2|) and by providing the damper 39 therein, the
entire apparatus is made adaptable for various uses. In other words either or both of the-furnaces may be used to generate the hot gas. For example, with burner 36 lighted and valve 3! closed, the current of hot gas will flow from furnace 34 through the drier to and through the flue 2| thereby heatingthe material in either.
or both the compartments 31 and i2, in which case it may be found desirable to open unlighted furnace 2 so that cooling air may be drawn therethrough and through the inner drum 3 to mix with the hot gases in compartments II. On the other hand the burner 4 may be used alone for the source of hot gas which is extracted through flue 2| and/ or 33 as-desired. Still further burner 4 may be utilized as the source of hot gas, and unlighted furnace 34 opened and valve 33' closed, whereby cooling air will be drawnthrough. the furnace 34 and chamber 31 to mix with the hot gas escaping'from the apparatus through compartments l2 and flue 2|.
From the foregoing description it will be seen that by this invention there is provided a combination single-shell and double-shell drier which meetsall the conditions and requirements that may be encountered in drying mineral aggregates,- especially for asphalt road-building purposes, and which combines the advantages of both types of drier into a dual drier at a saving in initial and operating costs. Most materials dry more economically in the doubleshell drier (5 and G) such as stone, gravel, and reasonably clean sand. Other materials, such as sand with a high clay content, are difficult to process through the economical double-shell 1 drier, and therefore this apparatus has been. devised which will'process both classes of materials either singly or together, to the best advantage.
This apparatus is provided with dual means of feeding and conveying. The dimcult material, with the .clay content, should be processed through the single-shell drier from breech-lg 3,
and the other materials should be processed through the double-shell drier from breeching 3,, both classes of materials ultimately entering the inner drum 3 and reaching the discharge l3, and when both classes of materials are being processed simultaneouslyv they may be-controlled 0nd cone 34 substantially axial with the cone 30,
the smaller end of the cone (furnace) 34 communicating with a housing 35 containing a source .of.heat suchas the oil burner-33.
ing 3, and flue2|, thereby drying said material as wellas, if desired, any material admitted chamber by the buckets 33, and escape from the apparatus through the compartments l2, breechthrough breeching 3 and passing through: said compartments |2 as heretofore described. The
material from breeching 3 ultimately reaches the compartments I2 but, due-to the flights Ii therein