US2878584A - Rotary drier, especially for granular substances - Google Patents

Description

March 24, 1959 A. BIANCHI 2,878,584

ROTARY DRIER, ESPECIALLY FOR GRANULAR SUBSTANCES Filed Oct. 5, 1955 3 Sheets-Sheet 1 INVENTOR. 6 41a 5/6 64- March 24, 1959 A. BlAN CHl 2,878,584

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United States Patent ROTARY DRIER, ESPECIALLY FOR SUBSTANCES The present invention relates to-a rotary drier,-'par-.

ticularly for granular substances like corn, rice, wheat and the like.

The object'of .the inventionis substantially. characterized by the fact of comprising ,two cylindrical elements, or an outer cylindrical element and'aco'nical inner elementor vice-versa, co-axial and foraminous, revolving around; their axes, the material being contained in the interspace between the two elements, where it moves in the' direction of the axis along a helicoidal diaphragm anal esia the said internalspace, the' drying gasbeing in'fdern "Theiiive'ntion will be described with reference to the annexed schematic drawing, given only by way indicative, not limitative example of the reach of the invention.

Figs. 1 and 2 respectively show in elevation and plan a preferred form of embodiment of the drier;

Fig. 3 is a section taken in correspondence with the loading apparatus;

Fig. 4 schematically represents the direction of the passage of the drying gas;

Fig. 5 is a medial cross section of the rotating element;

Fig. 6 is a cross section of the rotating element according to a constructional variant;

Figs. 7 and 8 are respectively a longitudinal section and a side elevation of a variant of the means for the introduction of the drying gases.

Referring now to Figs. 1 to 5, the numeral 1 indicates the outer cylindrical. rotating element, 2 indicates the coaxial inner element, the said two parts being made of foraminous metal sheets or of wire netting with a supporting frame.

In the illustrated example the elements 1 and 2 have two axial end journals carried on supports 5 and 6 anchored to the frame of a chariot or directly to the floor when the installation is stationary.

The rotational axis can either be horizontal or on a slant.

The material to be dried is placed in a tank 7 interiorly embracing one of the ends of cylinder 1 and provided with a loading funnel 8. At the said end the cylinder carries one or more openings with a scoop 9 (two of these, diametrally opposite are shown) so oriented that during the rotation of the cylinder 1 in the direction of arrow X they pick up some of the material to be dried contained in the tank 7. To each scoop 9 corresponds an opening in cylinder 1 protected by oscillating valves 10 opening to the inside (as shown in Fig. 3) so as to permit of introducing the material when the scoop 9 is at the top, i.e., in the position where there is no material, because a portion of the dried material is periodically discharged. When the scoop is in its lowest position, the material contained in cylinder 1 causes the valves 10 to close, so as to prevent the material from falling out. The humid material passes then into the interspace comprised between elements 1 and 2 in fed incountercurrent through one end of the inner cylice whichv a helicoidal diaphragm 11 causes the material to gradually travel towards the end opposite the loading end. The material entirely occupying the space between elements 1 and'2 is displaced in the direction indicated by the arrow X, following the travel of the helicoidal diaphragm. The dried material is automatically dis- I the material occupying 'the space between the cylinders '1 and'2'to correspondingly advance so as to leave an equal empty-space in the 'coil at the beginningof the helicoidal diaphragm 11, infront of the charging scoop 9. It results' from what has been described that the directionof the winding of the helix is such should it operate like an ordinary cochlea conveyor, that it would carry the material in a direction opposite the above mentioned one. For this reason the space between the elements 1 and 2 is practically all occupied byth'e materialtobe'dried- Therefore each scoop '9 cannot carry 'but the same quantity of material as discharged from theopening '12." Any excessrn'aterial will fall' again into 5'1 1. .Z: H l J.

The ends of the rotary elements 1 and 2 are closed, with the exception of the drying gas inlet 15 at one end of the inner cylinder 2, on the side of the discharge of the material.

The hot air is produced with the products of combustion of a furnace 16 (Fig. 2); fan 17 sends the hot gases through conduit 18 into the drier.

The same motor driving the fans drives also, through reducing gear 19 the drying cylinder.

The hot drying air entering the cylinder (or cone) 2 in a direction opposite the advancement of the material by its own dynamic thrust assisted by the suitable dimensioning of the apparatus, is rationally distributed in a greater quantity where the material is cold (at its entrance) and in a lesser quantity where the material is approaching the dry condition.

The air traverses the elements 1 and 2 in a radial direction, as shown by the arrows in Fig. 4.

In order to assist the mixing and regularity of the advancement of the material there are provided, in the interspace between the cylinders 1 and 2, diaphragms or septa 20 or double ones 21 (Fig. 5) which are set at an angle with the radius of the cylinder. In the same interspace between the elements 1' and 2 rotary radial vane mixers 22 (Fig. 6) can be inserted, which are driven when they are in the top position illustrated in the drawing, i.e., in the position where the material can most readily be mixed.

In Figs. 7 and 8 in which parts corresponding to those already described are counter-distinguished by the same reference numerals provided with quotation marks, a constructional variant is illustrated consisting of introducing by means of an auxiliary fan 23 (feeding the annular chamber 24) cold air in the last portion of the cylinder for obtaining cold material at the outlet.

It is also possible to send hotter air to the zone wherefrom the material is introduced, where the latter is cold and wet and can stand higher temperatures; by this solution the thermic etliciency of the apparatus can be increased.

In practice the constructional particulars of the drier can vary from those illustrated without stepping outside of the ambit of the invention and consequently of the Letters Patent. Particularly, the cylinder may roll over circ lar rails instead .of on the ,end journals.

I claim:

1. In a dryer apparatus, in combination, a pair of inner and outer tubular gas-permeable members defining a tubular space :between themselves; conveyor screw means arranged ,in said space "for moving therethrough in axialrdiliection ;a substance to be dried, said conveyor screw means extending axially throughout substantially the entire length of said space and extending radially from said inner member to said outer member; a conduit connected to said ,inner tubular gas-permeable member; and means for introducing into said conduit a gaseous medium so that the same is conducted directly intotthe interior of said inner gas-permeable member from where it moves into said tubular space where it is constrained to move radially outwardly between consecutive turns of aidc yc sc e rmc n d y ng t e con eyed substance du s chmcvem ut n radial d ection.

.2- n a d y V pna a ns, in om inat on, a pa of inner an oute tu u sa -pe m emem s defini a tubular space between themselves; conveyor screw means aran ed in sa d spa or m v ng h oug naxial direction from one end of said tubular space to the other end thereof a substance to be dried, said conveyor screw means extending axially throughout substantially the entire length of said space and extending radially from said inner member to said outer member; a conduit connected to said inner tubular gas-permeable member adjacent said other end of said tubular space; and means for introducing into said conduit a gaseous medium so that the same i c nduct d ec y into e in e o of sa inne a permeable member from where it moves into said tubular space where it is constrained to move radially outwardly between consecutive turns of said conveyor screw means, drying the conveyed substance during such movement in radial direction.

3. The combination defined in claim 2 wherein said outer member is rotatable about a generally horizontally axis, and means for introducing into said space the substance to be dried, the last-mentioned means including at least one scoop secured to said outer member in the region of that end thereof at which the substance is to be introduced into said space, said scoop being rotatable with said outer member and adapted, during rotation of said outer member, to scoop up the substance whenever said scoop is in itslowermost position and to deposit the scooped-up substance into said space Whenever said scoop is in its uppermost position.

4. The combination defined in claim 3, and means for discharging a predetermined quantity of the substance in the reg on of that end of said space toward which the substance is moved.

References Cited inthe file of this patent UNITED STATES PATENTS

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