US2280704A - Air circulating system for driers - Google Patents

Description

April 21, 1942. A. o. HURXTHAL. 2,280,704

AIR CIRCULATING SYSTEM FOR DHIERS I Filed SDM. l2, 1939 2 Sheets-Sheet l April 21, 1942.

A. O. HURXTHAL AIR GIRCULATING SYSTEM FOR DRIERS Filed Sept. l2, 1959 2 Sheets-Sheet 2 Patented Apr. 2l, 1942 2,280,704 A1B CIRCULATING SYSTEM FOR DBIEBS Alpheus 0.

Proctor vpllia, Pa.,

Hurxthal. Wyncote; Pa.. Schwartz, Incorporated. Philadela corporation of Pennsylvania assignor to Application September 12, 1939, Serial No. 294,526

1 Claim.

This invention relates to air circulating systems for driers. The object of the present invention is to provide a special type oi' air circulation in connection with a drier where `there must be no recirculation of the air over the heating coils but at the same time there must be recirculation of the air through the material being dried.

In the present instance, the invention as disclosed as being applied to that type of drier wherein the material undergoing treatment is transported through a suitable drying chamber containing conditioned lair in circulation, i. e. air of regulated temperature and/or humidity.

In the prior art driers of the above noted type, the drying air is normally circulated Within the drying chamber, transversely thereof, in a manner to make repeated contacts with the material being advanced through the drying chamber, and through a circulating compartment at one side of the drying chamber wherein the air passes and makes contact with suitable temperature regulating and/or humidifying units in its course of circulation, between its successive contacts with the material in the drying chamber.

In some instances, contact of the circulating air with the conditioning units after initial contact oi the air with the material being treated is undesirable because of dust or gaseous matters given oil? by some materials becoming entrained in the drying air. and because such gases or solid matters should not be permitted to come into contact with the heating or other conditioning units in the drier. Itis the object of the present invention to provide an eiilcient apparatus of simple compact construction for creating and maintaining an improved type of air circulation to satisfy the above noted requirements.

ln the accompanying drawings:

Fig. 1 is a diagrammatic plan view of a multisection drier Iembodying the novel features of the present invention;

Fig. 2 is a transverse sectional elevation taken on the line 2-2, Fig. l; and

Fig, 3 is an enlarged longitudinal sectional view of one of the air circulating devices employed for producing and maintaining th'e improved circulation in accordance with the principles of the presmt invention.

As shown in Fig. 1, the apparatus includes a drying chamber A which preferably is composed of a plurality of sections A1, A, A3, A4, A5, for example. Each lsection extends transversely of the drier as a whole between the side walls i and 2 thereof, the roof I, and a sub-floor 4 which is spaced above and parallel to the bottom 5 of thedrier.

Adapted to travel longitudinally through the drying chamber A, successively through the adjacently disposed sections thereof, is a conveyer of a horizontal endless belt type, the carrying run 8 of which is disposed in a plane intermediate the roof 2 and sub-flooring 4, while the return run 1 travels through the space 8 formed between the ooring 4 and the bottom li. The various sections of the drying chamber A are separated by transversely extending partitions i in which are formed openings Il .for passage of the conveyer run 8.

At one side of and spaced laterally from each cr any predetermined number of the sections A1,

A2. etc. is an air conditioning chamber I2, in which is mounted a suitable heating and/or humidifying unit i3. Admission oi' air to the upper end of each conditioning chamber i2 is controlled by an adjustable damper i4, whereby predetermined quantities of extraneous air may pass into the conditioning chamber from the outside atmosphere and through the conditioning unit I3 for initial regulation of temperature and/or humidity for subsequent entrance into the drying chamber A.

In a compartment i5 disposed intermediate the drying chamber A and the air conditioning chamber l2, for each of the sections A1, A, etc. thereof respectively, is an air impeller i6. As shown in Fig. 3, each impeller i6 comprises a rotor I1 composed of a pair of axially spaced concentric frusto-conical annular end plates i8,

Abetween which impeller blades i9, i9 extend in a general axial direction.

Intermediate the opposite end plates i8, i8 of each rotor i'i, the impeller i6 is provided with a transversely extending disc 20 which divides the impeller blades i9 into relatively short and long sections i9* and i8b respectively., The disc 20 is supported by a suitable hub 2| in which one end of a supporting and driving shaft for the rotor il is suitably secured.

'I'he shaft 22 oi' each rotor Il, as shown in Fig. 2, extends completely through the conditioning chamber i2 to and through the outside wall 9 of the conditioning chamber i2 to a driving motor 24 which is secured to the wall 9, outside the drier. If desired, a bearing 25 may be provided for the shaft 22 adjacent the inner wall 26 oiV the conditioning chamber I2.

Secured to the wail 26, and affording communication between the conditioning chamber As each impeller. I1 is rotated by its motor 24,

air is simultaneously drawn from the conditioning chamber l2, through the duct 21 by the blades I3, and from the lower portion 29 of the drying chamber A, through the duct 23 by the blades I9, and is delivered radially outward into a casing 30 which surrounds the rotor I1, within the intermediate compartment I5. The drawn air is conducted from the casing 30 to an opening 32 in the upper portion of the'drying chamber A by a duct 3l, in which the fresh extraneous air from the conditioning chamber I2 is' thoroughly mixed with the air simultaneously drawn from the drying chamber A the air passing through the inlet opening 32 being suitably deected, to pass downwardly in the drying chamber A, by suitable louvers 33.

As indicated by the arrows in Fig. 2, the air initially enters the drying chamber A, through the regulating damper I4 in the upper end of the conditioning chamber I2, under the impetus of the impeller I6, by which the air is drawn downwardly through the conditioning chamber I2 and then moved upwardly into the upper portion f the drying chamber A, the air being: suitably conditioned enroute through the chamber I2 before it enters the drying chamber A.

The air is also circulated transversely of the drying chamber A by the rotor I1, by being drawn into the axial inlet 28 of the impeller I6 from the lower portion 29 of the drying chamber A, and driven outwardly from the peripheral discharge of the rotor I1 of the impeller into the impeller casing 3|).l from which the air passes through the duct 3i and opening 32 into the upper portion of the drying chamber A, solely.

The drying air, afterits initial conditioning in the chamber I2, and after its initial contact with the material supported by the conveyer run 6, never again makes contact with the conditioning unit I3.

As freshly conditioned air is continuously supplied through the regulating damper I4, and' mixed, in the casing 30 and duct 3| with the air in circulation within the drier, a suitable quantity of moist air is exhausted from said circulation, through an exhaust duct 34 communicating with the lower portion 29 of the drying chamber A, under the impetus of a suitable exhaust ian 35 which is driven by an independent motor 36, or equivalent means. If desired, there may be an exhaust fan 35 for each of the various sections of the drying chamber. However, under normal conditions, a single fan 35 may be operated eiiciently to exhaust a suii'icient quantity of moist air from the drying chamber A as a Whole.

As shown in Fig. l, the'sections Al and A2 are provided with individual dampers I4 and i4 respectively. The sections A39 A, and A5, however, are supplied with fresh extraneous air from a single damper I4c which communicates with a l single elongated conditioning chamber I2EL comdevices of any of the types commonly known to the art, such, for example, as wet and dry bulbs,

whereby the units I3 may be automatically controlled as well as the dampers I4. I4", and l4 which regulate the quantities of air admitted to the respective conditioning chambers.

In some instances, it may be desirable to pass the air in circulation from one section to another, with or without adding fresh extraneous air thereto, in which case the dampers I4", I4b and I4 may be selectively closed or opened and each or any desired number of the partitions I0, between the various sections, may be provided with an adjustable gate 31 which is hingedly mounted at one oi' its ends to the partition I0 in an opening 33 formedin said partition, said gate 31 normally lying in the plane of the partition I0 and being adapted to be swung to either side thereof at an angle thereto, as shown in broken lines in Fig. l, for controlling the passage of air from one section to the next, through an opening 38 formed in the partition I0 between the carrying run 6 of the conveyer and the sub-ilooring 4 of the drier.

From the above it will be clear that in a device constructed and operatedas described, each secticn of the drier may have its own independent properly proportioned heating unit andl control, by which similar or differential temperatures best suited to the speciilc drying problem at hand may be obtained and maintained throughout the length of the drier. Likewise the dampers for the extraneous air admitted to the conditioningv of the drier by any suitable means such as a ianof suitable capacity having a construction similar to the exhaust fan 35, or an equivalent structure. Under such conditions, obviously, the section of the drying chamber nearest the discharge end for the material would be of the highest temperature and of the lowest moisture content.

I claim:

A drier comprising a drying chamber devoid of any air conditioning means, means for circulating air solely within said drying chamber in a course transversely thereof, a second chamber provided with air conditioning means, means for moving unconditioned air from outside said drier into said second chamber for initial conditioning and for moving the initially conditioned air from said second chamber into the circulation of air in said drying chamber, an air-intercepting gate in said drying chamber for selectively diverting the'air circulating solely therein and transversely thereof in either direction longitudinally of said chamber from one portion of said transverse course of circulation in'to an adjacent portion of said transverse course of circulation solely within said drying chamber, and means for discharging said circulating air to waste outside said drier.

V ALPHEus o. HURx'rHAL.

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