US1539649A - Drier - Google Patents

Description

L. R. CHRISTIE DRIER May 26, 1925.

Filed July 5, 1923 4 Sheets-Sh et 1 INVENTOR May-26, 1925.

I L. R. CHRISTIE Filed July 3; 1923 4 Sheets-Sheet 2 May 26, 1925.

L. R. CHRISTIE DRIER Filed July 5, 1923 4 Sheets-Sheet 3 i it; 46

4 Sheets-Sheet 4 INVE NTOR 42. 4;

May 26, 1925' L. R. CHRISTIE DRIER Filed July 1923 Patented Nlay 26, 1 925.

UNITED STATES LINDSAY R. CHRISTIE, OP PITTSBURGH, PENNSYLVANIA, ABSIGNOB TO DUFF PATENTS COMPANY, INCORPORATED, OF PITTSBURGH,

PORATION OF PENNSYLVANIA.

PENNSYLVANIA, A COR- DRIER.

Application filed July 8,

To all whom it may concern:

Be it known that I, LINDSAY R. Cnars'rin, a citizen of the United States, residin at Pittsburgh, county of Allegheny, and tate 5 of Pennsylvania, have invented a new and useful Improvement in Driers, of which the following is a full, clear, and exact description.

The present invention relates to driers, and more particularly to indirect heat driers for use in drying powdered and granular or clazyey material. I n object of the present invention is the provision of .a drier of the general type disclosed in my Patent No. 1,318,133 of October 7, 1919, but embodying means insuring a substantially dustless operation of the drier. To that end, a feature of the invention is the provision of a drier comprising a rotary drum for receiving the material to be dried, means for withdrawing evaporated moisture from said drum, and means associated with the intake and discharge openings of the drum for substantially preventingv the ingress of air through said openings, whereby said moisture is removed from said drum substantially free of dust.

It has heretofore been proposed in the art to which this invention relates to provide a cylindrical drum having heat ducts passing transversely therethrough and opening through the cylindrical outer shell of the drum. said ducts dividing the drum into a plurality of dryingcompartments extending longitudinally thereof, and the cylindrical shell into a plurality of separate parts, the construction being somewhat similar to a bundle of parallel tubes connected at their I ends to headers. An objection to a structure of this kind is that, due to the division of the outer shell of the drum into a plurality of separate parts, the capacity of the drum to withstand the torsional strains set up therein in driving the same is greatly impaired. By the present invention, I have avoided this objectionable feature in a drier of this general type by forming the cylindrical shell continuous and imperforate around at least a substantial'longitudinal 59 section of the drum, preferably a centrally located section thereof.

Another object of the present invention is to provide a rotary drum having a plurality of drying compartments separated by a plu- 1923. Serial in. 849,206.

, rality of heat ducts, the drum being so constructed that substantially all portions of the walls thereof exposed to the direct action of the hot gases are protected by the material being dried, thereby avoiding danger of burning the plates.

Whereas it has heretofore been proposed to divide the rotary drum into four longitudinally extending tubes or compartments of substantially equal cross-sectional areas and radiating from the center of the drum, it is sometimes desirable to increase the number of such compartments in order to obtain a greater heating surface and a better heat penetration of the material being dried. By dividing the drum into more than four compartments, however, all radiating from the center of the drum, an acute angle is formed between the radial sides of at least some of the compartments, which is objectionable on account of the tendency of the material to stick to the sides of the compartments in such angles. A further object of the present invention, therefore, is to provide a drum which may embody any desired number of compartments, each having every angle between its walls substantially a right angle or greater than a right angle.

Still another object of the invention is to so design the compartments into which the drum may be divided, irrespective of the number and varying sizes of such compartments, that the lengths of the arcs which the a various compartments subtend on the outer shell of the drum shall be proportional'to the total amounts of heating surfaces of such compartments.

In the accompanying drawings, there is shown, for purposes of illustration only, one embodiment of the present invention, it being understood that the drawings do not define the limits of the invention, as changes may be made in the construction and operation therein disclosed without departing from the spirit of the invention or scope of my broader claims.

In the drawings:

Figure 1 is a central vertical longitudinal sectional view through a drier constructed in accordance with my invention, and showing the rotary drum partly in section and partly in elevation;

Figure 2 is a transverse vertical sectional view on the line II-'II of Figure 1:

' drier comprises a rotary drum A enclosed in a suitable housing B which may be connected with a furnace C for supplying hot gases.

The drum A is supported adjacent its opposite ends for rotation upon rollers 2 engaging tracks 3 on the drum, and is rotated by any suitable means, such as a pimon 4 engaging a gear 5 on the drum A, the pinion 4 being mounted u on a shaft 6 which carries a belt pulley Referring to- Figure 1, it will be seen that the drum A comprises a cylindrical section 8 at the intake end and a cylindrical section 9 at the discharge end thereof. The main body portion of the drum, intermediate the end sections 8 and 9, as shown in Figures 2, 3 and 5, is divided into four drying compartments or tubes 10 by radial heat ducts 11. The tubes or compartments 10 extend longitudinally of the said body portion of the drum and open at their opposite ends into the cylindrical sections 8 and 9. The heat ducts 11 alsgextend longitudinally of said body portion, but are closed at their opposite ends by artition plates 12 between the ends of the ody portion of the drum and the end sections 8 and 9. The radial arms of these partition plates are channelshaped in cross section for a purpose to be brought out hereinafter.

The body portion of the drum is preferably divided longitudinally into three sections of. substantially equal lengths. The radial heat ducts 11 open through the outer cylindrical shell 13 of the body portion in the end sections thereof, as shown in Figure 5, thereby providing for the passage of the hot gases transversely through said end sections, but in the middle section of said body portion, these radial ducts are closed at their radial outer ends, and the shell 13 is continuous and imperforate around this middle section of the drum. This construction enables the drum to better withstand the torsional strains set up in the same when it is rotated, than if the radial ducts 11 opened through the outer shell 13 throughout the length of the body portion of the drum, and thus divided said outer shell into a plurality of parts separated from each other throughout the length of the body portion.

Referringto Figure 3, it will be seen that the outer radial ends of the heat ducts 11in the middle section of the body portion of the drum are closed by bending inwardly the outer radial edge portion of one side wall of each duct to engage the other side wall thereof, and riveting these walls together. By reason of this construction, the wet material in the tubes 10 is enabled to contact with substantially the entire inner surface of the outer shell 13 of the drum, and thereby protect the same from being burned out by the hot gases, whereas if both side walls of each radial duct 11 were extended straight out to the outer shell 13 and riveted thereto in the middle section of the body portion, in the same manner as in the end sections of said body portion, portions of the outer shell 13 would be subjected to the action of the hot gases both on the inner and outer surfaces thereof, and would be liable to be burned out. Communication between the radial ducts 11 of the end sections of the drum and the compartments 10 is prevented at the middle section of the drum by plates 31 shown in Figures 2 and 5.

It will be noted that the manner of clos-- ing the outer radial ends of the ducts 11, as illustrated in Fi ure 3, provides a space or pocket between t e outer closed end of each duct and the cylindrical shell for the wet material to lodge in. The purpose of the channel formation of the channel plates 12 is to enable these plates to maintain a layer of wet material in the channels thereof to protect said plates from being burned out by the hot gases passing through the ducts 11. a

The material to be dried is introduced into the end compartment 8 through a tube 14 extending through an intak opening 15 in the end wall of the drum. ositioned in the tube 14 is a feed screw 16 which carries on its outer end a belt pulley 17-, whereby the screw may be driven from any suitable source of power. into the end compartment 8 is conveyed by helical flights 18 therein to the several drying compartments 10. The material in the compartment 8 being divided at the en. trance to the compartments 10, does not mix again until it has passed through the heat zone, when it falls into the discharge end compartment 9 land is tumbled about and mixed again by cascading flights 19 in said end compartment. Secured to the discharge end Wall of the drum are a plurality of buckets 20 arranged to receive the material and having inclined flanges 21 extending. through a discharge opening 22 in said end wall. The discharge 0 ening 22 is in communication with a ischarge chute 23. Arranged in said discharge chute is a rotary gate valve 24 having associated therewith a belt pulley 25, whereby said valve may be rotated. In order to produce a desirable cascading effect within the compartments 10,

The material introduced I any given temperature.

suitable studs 26 may be provided, said studs projecting from the walls of said compartments.

The evaporated moisture is withdrawn from the drum by a'small fan 27 located at the feed end thereof, and communicating with the intake opening 15 by a pipe 28. This fan is designed to have over capacity tor the moisture evaporated, thereby creating a partial vacuum within the drying drum.

The provision of the feed screw for feeding the material through the intake opening and the gate valve associated with the discharge opening, substantially prevents ingressoi air into the drum, so that the moisture is withdrawn substantially free of dust. The vacuum maintained in the drum is very sli ht, and the velocity of the evaporated moisture is not great enough to carry out any dust. This vacuum is very desir able, as the rate of evaporation increases with each pressure decrease, and thereby insures more rapid drying of the material at Moreover, the greatest volume of steam produced is at the intake end where the material is not dusty, and tapers off to substantially nothing at the discharge end. \Vhile I have disclosed a feed screw and a rotary valve associated with the intake and discharge openings for preventing the ingress of air into the drum, it will be understood that any other equivalent means may be utilized for this purpose, and I therefore do not limit myself to the use of the particular means disclosed.

In Figures 1, 2, 3 and 5, I have shown a drum divided into four drying compart ments separated by four radial heat ducts, audit will be noted that in this construction every angle between sidewalls of the various drying compartments is substantially a right angle. It is sometimes desirable to divide the interior of the drum into more than four drying compartments, but if all such compartments radiated from the center of the drum, the angle formed between the" radial side walls of each compartment would be an acute an le, which would be objectionable because 0 the tendencyof the material to cling to such walls in the angle therebetween. In Figure 7 I have shown a modified construction in which the interior of the drum is divided into eight drying compartments 10' separated by radial heat ducts 11', and it will be noted that every angle between side walls of every stantially equal drying, so that when the 1 material has passed through these compartments and again is mixed together in the discharge compartment, the entire mass will be uniformly dried.

The operation of my improved drier is substantially as follows: Hot gases generated in the furnace C pass from the furnace around the entire length of the outer shell of the body portion of the drum A, and also through the heat ducts which extend transversely through the end sections and longitudinally of the middle section of said body portion. These gases, after having given up the greater part of their heat, are exhausted by means of a fan 29 located adjacent the discharge end of the drum and communicating withthe housing B through an opening 30 therein. The material to be dried is fed into the intake end compartment 8 by the feed screw 16 and is conveyed by the cascading flights 18 into the several compartments 10, through which it passes and is finally discharged into the discharge end compartment 9, from which 'is passes through the opening 22- into the discharge chute 23 and past the gate valve 24. The drying is done entirely by the indirect ap plication of heat, and the evaporated moisture is withdrawn in a substantially dustless condition by the fan 27 It will be obvious that, if desired, inert gases may be introduced into the drum, the sealing of the drum retaining these gases and preventing their contamination.

An important advantage of the present invention arises from the provision of :1 drier of the indirect heat type having means for withdrawing the evaporated moisture in a substantially dustless condition.

Another advantage of the invention arises from the provision of a rotary drum so constructed that substantially all portions of the walls thereof which are subjected to the direct action of the heating medium are protected against burning by the material being dried.

A further advantage of the invention arises from the provision of a rotary drum having a plurality of drying compartments separated from each other by a plurality of heat ducts, and in which the outer shell of the drum is continuous and imperforate throughout a substantial longitudinal middle section'of the drum.

A still furtherv advantage of the invention arises from the provision of a. drum having a novel arrangement of drying compartments and heat ducts, whereby the interior ment having inta of said housing, and means associated with of the drum may be divided into any desired number of such compartments, and all of the angles between the walls of the several compartments maintained at least as great as a right angle.

I claim: 1. In a drier, a rotatable drum having a compartment for receiving material to be dried, a housing surroun ing said drum, means for rotating said drum, said compartze and discharge openings therein and an outlet for, thewithdrawal of evaporated moisture but being otherwise closed to the ingress of outside air, means for withdrawing evaporated moisture from said drum through said outlet, means for supplying a heating medium to the interior said openings for substantially preventing the ingress of air therethrough, whereby said moisture is removed from said drum substantially free of dust, substantially as described.

2. In a drier, a rotatable drum having a compartment for receiving material to be dried, a housing surrounding said drum, means for rotating said drum, said compartment having intake and discharge openings therein and an outlet for the withdrawal of evaporated moisture but being otherwise closed to the ingress of outside air, means for withdrawing evaporatedmoisture from said drum through said outlet, means associated with said openings for substantially preventing the ingress of air therethrough, whereby said moisture is removed from said drum substantially free of dust, said drum having heat ducts therein, and means for supplying a heating medium to the interior of said housing, substantially as described.

3. In a drier, a rotatable drum for receiving material to be dried, the outer shell of said drum being continuous and imperiorate throughout a substantial longitudinal section of said drum, and a heat duct extending through said section, said shell having openings therein adjacent the opposite ends of such imperforate portion with which said duct communicates, substantially as described.

' 4. In a drier, a rotatable drum for receiving material to be dried, the outer shell of said drumibeing continuous and imperforate throughout a substantial longitudinal middle section of said drum, and a heat duct extending through said'section, said shell having openings therein adjacent the opposite ends of such imperforate portion with which said duct communicates, substantially as described.

5. In a drier, a rotatable drum for receiving material to be dried, said. drum having its interior throughout the greater portion of its length divided into a plurality of drying compartments extending longitudinally of the drum and separated from each other by a plurality of heat ducts openin through the outer shell of the drum, said s ell being continuous and imperforate throu hout a substantial longitudinal section of sai drum s aced a substantial distance from both ends t ereof, substantially as described.

6. In a drier, a rotatable drum forv receiving material to be dried, said drum comprising a single'compartment at each end therethrough the outer shell of the latter, sub-- stantially as described.

7. In a drier, a rotatable drum for receiv-' ing material to be dried, said drum comprising a single com artment at each end thereof, and a plurality of drying com artments extending longitudinally of the drum and communicating at their 0 posite ends with said end compartments, said drying compartments beingseparated from each other by a plurality of heat ducts extending transversely through the drum and opening through the outer shell of the latter, said outer shell being continuous and imper'forate throughout a substantial longitudinal section of the drumspaced a .substantial distance from both ends of the latter, substantially as described.

8. In a drier, a rotatable drum for receiving material to be dried, said drum comprising a single compartment at each end thereof, and a plurality of drying compartments extending longitudinally of the drum and communicating at their opposite ends with said end compartments, said drying compartments being separated from each other by a plurality of heat ducts substantially coextensive in length with said drying compartments and extending transversely through the drum and opening through the outer shell of the latter, substantially as described.

9. In a drier, a rotatable drum for receiving material to be dried, said drum comprisy a plurality of heat ducts substantially coextensive in length with said drying com partments and extending transversely through the drum and opening through the outer'shell of the latter, said outer shell bepartments being separated from each other ing continuous and imperforate throughout I a substantial longitudinal middle section thereof. substantially as described.

10. In a drier, a rotatable drum for receiving material to be dried, said drum having a plurality of radial heat ducts opening through the outer shell thereof permitting1 hot gases to pass transversely through sai drum, and a plurality of heat ducts branching off from said radial ducts and also opening through said outer shell said ducts dividing the interior of said drum into a plurality of drying compartments, the construction being such that the angles formed between the walls of the several compartments are all at least substantially as great as a right angle, substantially as described.

11. In a drier, a rotatable drum for receiving material to be dried, said drum having its interior divided into a plurality of drying compartments radiating from the center thereof and separated from each other by radial heat ducts,and a plurality of compartments interposed between said radial compartments and separated therefrom by radial heat ducts, each of said compartments having one of its walls formed by a portion of the outer shell of the drum, the lengths of the arcs on the circumference of the outer shell subtended by the several compartments being proportional to the total heating surfaces of said compartments, substantially as described.

In testimony whereof Ihave hereunto set my hand.

LINDSAY R. CHRISTIE.

Images