US1432270A - walsh - Google Patents

Description

J. H. WALSH.

DRIER.

APPLICATION ElLED MAY 27, 1921.

Patented oct. 17, 192'2.

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APPLICATION msn MAY2L1921.

Patented oef. 17,1922.

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' screening the educt air in such a way as to Patented Oct. 17, 1922.

A UNITED :STATI-:s rATENToFFIcE.

JOSEPH H. WALSH, or READING, MASSACHUSETTS, `AssrcfNon "ro roHNs-MANVILLE rNcoRroRATED, or NEW Yonx, N. Y., A oonroHA'rroN or NEW YORK.

DRIER.

To all cohom-c't'-1nag/ concer/rt."

vBe it known that I, JOSEPH IIWALSH, a citizen of the UnitedStates of America, and resident ofiReading, 'in the county ofMiddleseX and State'of 'Massachusett s, have invented new and useful Improvements in Driers, of which the following is a specification.

l Machines heretofore provided for drying materialsy vcontinuously passed through a drying 'chamber have been ineflicient and unsatisfactory in many ways. Usually the air tated or churned, to `the exclusion of Veiiicient circulation of the heated fresh airv within the drying chamber and timely withdrawal ofthe eXhausted'or saturated air. Especially in the case 4of driers for bulk material, such'as fibrous stock, grain, rags, wool shoddy, and like materials, the contact of the air with the material has been hap-l hazard and ineffective, particularly in regard to maintaining a sufiicient circulation without blowing away the light material. Fumes, steam, odors and dust arising from the material 'have not usually been prevented from escape into the air of the room where these machines are installed.'

One of the objects of this invention it to provide a drier of improved efficiency both as regardsdistributionof air and conservation of'heat, and whichV will vnot be Subject to the objections mentioned.

A further object is to provide an improved drier for loose material, in which moisture is rapidly removed with a minimum eX- penditure of heat, and without scattering light materials.

Further objects are to providea circulat` ing system for driers in which currents of heated air are positively delivered to points Where they ywill be mostefl'e'ctive in carrying away the moisture;v to provide' for avoid loss of fibrous materials,'andipermit collection ofthe screenings during the constant operation of the drier; to provide a drier which effectively functions without depending upon convection currents caused by heating units; to avoid heating means in Application ined May 27,1921. seriaiNo. 473,201.

the drying chamber ofthe drier, and to provide a drying system having these advantages which may be conveniently applied to installations already in use; and in general to improve the construction and operation,

and especially the heat and mechanical efiiciency, of machines of the class referred-to.

I shall now explain the invention in connection with one embodiment illustrated in the accompanying" drawings, for oneinstance only of a construction comprising the n invention, in whic`h,` in the drying chamber has been merely agi- Fig. l is a front elevation showing a drier of the agitating-table type having mechanicallyaided' air circulation, the insulating casing being in part removed, the paths followed by the air in the circulating system being indicated by .the arrows in the several figures;

Fig. 2 is an end elevation showing the general arrangement of various parts of the drier, and

Fig. 3 is a top plan view of the machine, showing parts in horizontal section.

The invention is applicable to drying machines (by which I refer to the means for circulating or suspending the material to be dried in a'drying chamber, and means'for confining a quantity of heated or dried air in contact with the material) of many different types, but I have chosen to show herein, for illustration of one specific appli cation, a drier of the agitating-table `type substantially corresponding to the Letters Patent to Mathew F. Kelvin, No. 1,249,771, dated Dec. i1, 1917.

The machine `of said patent comprises feeding means, a metallic casing B divided by partition b into a heater chamber and a drying chamber, agitating and conveying means in the drying chamber, and a number of blast fans for blowing air from the heater into the drying chamber, through openings in the upper part of wall b.

In general, the drier herein shown utilizes the heating chamber l2 and drying chamber 6 of the prior device, but economically conserves heat and mechanical energy by-pro' viding means for causing the entering air to be heated by the educt air, by causing positive circulation and distribution of heated air throughout the drier, by preventing radiation and convection losses of heat, and by applying the dry, hot air to the work in a new and better way, and by simplifying the circulatingmeans. j l

The drier as a whole is enclosed by a heatinsulating casing A, Fig. 3, which may comprise suitable supports or standards 1 and asbestos-wood sheet panels 2 secured to opposite sides thereof, and covering the top of the machine, Fig. 1. If desired, the space between the sheets 2 may contain suitable additional heat insulating material, such for example as the corrugated or air-cell asbestos material 3, or other efhcient heat insulating packing. The asbestos-wood surfaces are not subject to deterioration by acid fumes or gases destructive of metals. The metal parts may be covered with any suitable fume-resisting coating when the material to bel worked upon gives ofi" corrosive fumes. The exterior casing A may be relied upon to prevent seepage of dust or fumecontaminated air into the work-room, land greatly to conserve the reduced amount of heat employed in chamber 12. In some cases the metallic casing B may be dispensed with, the machine parts being erected directly on the walls of the insulating casing A and a suitable partition of similar lconstruction replacing the metal partition b.

The drying machine when employed for drying loose material such as wool, tanbark, shavings, jute, cotton, rags, or other such materials, is provided with means for feeding, agitating, spreading and advancing the material in'a stream through the drying chamber, for example the means shown in saidflbatent No. 1,249,171, which may be consulted for details of construction. In general, this machine comprises an automatic hopper feeder 'F and a plurality of tables arranged lone above the other, each table comprising a reciprocating member 16, 17 and 18, Fig. 1, which members carry angular-ly arranged, preferably perforated shelves 19, which shelves cooperate with other ang'ularly varranged stationary shelves 20, whereby the material, fed to one end 21 of the upper table through the hopper 22 byr means of a suitable feed-lattice 23 and feed roller 2-1, is progressively moved throughout the length of the upper table, after which it `is delivered to one end of the middle table 17 which moves the material in a directionopposite to the upper table, and delivers to the bottom table 18, and out of the machine toward the'right, Figs. 1 and 3.

Whatever the construction of the mechanical parts by which the material ,is moved .through the drying chamber, such as 6,v the improved machine includes improved means for delivering upon and circulating through the material air heated in the heater chamber 12. The chamber 12 is preferably put under a positive air-pressure for this purpose, and passages leading from this chamber are contrived to deliver dry, fresh air adjacent to all parts of the stream of material traveling through the drier. In the preferred arrangement, provision is made for common ascent in chamber 6 of the introduced dry air and the flow of currents of moisture-laden, and therefore lighter, contained air, in opposition to motion of the material downward from level to level of the tables 16, 17, 18 within the chamber 6.

A series of elongated conical tubes 25 communicating with chamber 12 through holes in partitions b and having delivery orifices along their upper sides, is arranged below and adjacent to each of the reciprocating tables, so that the heated air may be conducted from chamber 12 to points adjacent the under sides of the tables 16, 17, 18 andthe material to be dried. The heated air may be emitted from the tubes through any suitable openings, but preferably, the orifices are slots provided in the upper side of the tube for this purpose, the width of each slot varying inversely 'to the corresponding pressure throughout the ylength of the tube. r1`he material throughout its path in chamber 6will thus be subjected to uniform streams of dry air from the heater 12 flowing upwardly in the same `direction as the flotation currents in the dead air in chamber 6. f

The lowermost series of tubes 25 will deliver air, in a 'current regulated by blast means presently referred to, upwardly through and upon the lower stream of material on table-18. This part of the material has been primarily subjected to the similar impingement of dry warm air from the upper tubes, taking place in anl atmosphere of the more humid air which Ahas absorbed the moisture from the lower, upper land intermediate tables of the machine.

The drying is thus progressively effected by air having a larger capacity for absorption'as the: material moves through the machine. But this is effected without creating anywhere in the drying chamber a current having high velocity or great volume, which might carry with it flocculent or light parts of the material, or any current sweeping the planes of the tables and parallel with them, which would be peculiarly adapted to pick up loose particles. So far 'as the material is blown upon by the air jets, these act upwardly, and through the interstices and fperforations of the agitating tables.

lBy these arrangements, the material may be brought into contact'with a great volume of air in a minimum. of time, without blowing the material f about or causing to be taken out of the drier any substantial borne by the educt current.

1t is desirable to provide means for preventing the small amount of the loose material inevitably borne by the air from being carried off through the educt air channels. For this purpose, there is provided a screen 7 arranged accessibly for replacement across the intake end of the educt passage 30 `from chamber 6 into a pre-heater chamber 8 presently referred to. When the screen becomes coated or clogged, the screen may readily be removed and replaced by a cleaned screen through a door 31 in casing A without causing interruption of the operation of the machine.

The heat supplied to the system, by the steam coil 13 in the chamber 12 is largely conserved by the prevention of radiation losses and the complete enclosure of the drying chamber, but a large quantity of heat remains in the educt moist air from the drying chamber 6. Driers corresponding to the invention cannot be operated so that the supply of heated and dry air is exactly proportioned to the moisture to be evaporated. Excess of heat is often required, or the charge flowing through the machine may vary in quantity or in proportion of contained moisture.

This invention utilizes the heat heretofore wasted remaining at the educt from the drying chamber to pre-heat the entering air and thus lessens the amount of heat required to be radiated by coil 13, which may be correspondingly reduced in size and consumption of steam avoided. The incoming and outgoing air-currents are so arranged as to permit by conduction through confining walls separating them. and radiation therefrom, an interchange of heat without mixture of the currents of air or interchange of the contained moisture of the educt current. For this purpose, the entering and leaving air-currents are taken through a pre-heater or regenerating unit 8 comprising a chamber of the casing A preferably placed on top of the drying chamber 6. f

The pre-heater or regenerating unit may comprise a plurality of passages, shown as tubes 35, having metallic or other conducting walls adapted for radiation, each having one end communicating with an outlet or exhaust passage 36, and its other end opening into educt passage 30 of the drying chamber 6. The heated airl from the drying chamber passes through the tubes 85 and into the exhaust or outlet passage 36, and during this passage gives up most of its heat to air entering the system. The preheater tubes are contained within chamber '8, which maybe provided with baflies the system leading into repeated Contact with the tubes 35. Air enters through an inlet pipe 10 leading into the top of casing A and into chamber 8, at one end of said sinuous path, the other end of the path marked off by the baflies communicating through a pipe 38 with a suitable fan 11 adapted to force the pre-heated air into the heater chamber 12 containing the heater coils 13. v

lWhat I claim is:

1. A drier having therein, in combination, heating means and a drying chamber communicating therewith, an induct passage for air and a plurality of educt passa-ges leading from the drying chamber separated by walls adapted to radiate to the entering air heat acquired from the educt air, and means` for maintaining a positive air pressure in said heating means to circulate air through said chambers and passages.

2. A drier having therein, in combination, a heat-insulating enclosure, heating means, and a drying chamber communicating therewith within said enclosure, an induct passage for air and a plurality of educt passages leading from the drying chamber separated by walls adapted to radiate to the entering air heat acquired from the educt air, and means for maintaining a positive air pressure in said heating means to circulate air through said chambers and passages.

3. A drier for materials in bulk having therein a drying chamber and means for moving the material through the chamber in a stream,A means for delivering into contact with the material at a plurality of points along said stream blasts of heated dry air, and means whereby air rendered moist by contact with the material is caused to flow from the drying chamber.

1i. A drier for materials in bulk having therein a drying chamber and means for moving the material through the chamber in a stream, means for agitating the material during'its progress, means for delivering into contact with the material at a plurality of points along said stream blasts of heated dry air, and means whereby airy rendered moist by contact with the material is caused to flow from the drying chamber at a point near the entering run of the stream of material.

5. A drier for materials in bulk having therein a drying chamber and means for moving the material through said chamber in a stream, a heating chamber, and means for maintaining a circula-tion of air through said chambers comprising means for delivering from the heating chamber to the drying chamber a number of upwardly directed substantially uniform blasts of heated dry air.

6. A drier for materials Ain bulkhaving therein a drying chamber and means for moving the material through said chamber in a stream, a heating chamber, means for maintaining a circulation ot air through said chambers comprising means for delivering from the heating chamber to the drying chamber a number of upwardly directed substantially uniform blasts of heated dry air, and means for permitting iioiv of air from the drying chamber at a point above the stream of material. l

7. A drier for materials in bull( having therein a drying chamber andmeans tor moving the material through said chamber in a stream moving from height to height within said chamber, the material entering said chamber at the upper run of said stream, a heating chamber, and means tor maintaining a circulation of air through said chambers comprising means for delivering irom the heating chamber to the drying chamber at points distributed throughout the length ot said stream, a number of upwardly directed substantially uniform blasts of heated dry air.

S. In a drier ot the agitating-table type, in combination, with the means for agitating and advancing' the material in a closed chamber, means tor delivering against the underside ot t-he stream oil material a number of relatively uniform blasts of air, comprising a plenum chamber, and a number ot air-delivering tubes having upwardly directed orifices and extending from the plenum chamber into the spaces under the agitating tables.

i). A drier having therein, in combination, a drying chamber and air educt means therefor, means for moving material to be dried through the drying chamber, a heating chamber and vair induct means therefor communicating passages between said chambers, a heat interchange pre-heater including said. educt and induct means, and means between' said pre-heater and said heating chamber for maintaining a positive air-pressure in said heating chamber'.

10. A drier having therein in combination,` a drying .chamber having air inlet 'tubes arranged at different levels therein and an outlet at the top thereof, and means for carrying the material to be dried successively above the respective air inlet tubes, the means tor carrying the material causing it to travel .trom the top towards the bottoni-ot the chamber, whereby the material is successively subjected to independent` air currents trom said tubes acting in an atmosphere progressively increasing in absorbent capacity. y

11. 1n a drier, in combination With an airheating and a drying chamber, a heat regenerator arranged above the drying chamber, said regenerator having passages communicating With an outlet :trom the drying chamber vfresh air induct means providing a passage in contact With Walls of the heat regenerator outlet passages for pre-heating lthe 'fresh air entered, connections between said fresh air passages of the regenerator and the heating chamber, and means for causing a positive circulation of air through the said chambers, passages and connections.

i2. In a drier, in combination with an air-heating and a drying chamber, a heat ref-generator arranged above the drying chamber, said regenerator having passages communicating With an outlet from the drying chamber, a removable screen arranged between the drying chamber and the heat reoenerator, fresh air induct means providing a passage in contact with Walls of the heat regenerator outlet passages :tor prebeating the fresh air entered, connections between said fresh air passages of the regencrator and the heating chamber, and means 'tor causing a positive circulation of air through the said chambers, passages and connections.

135A drier ot the agitating-table type tor drying loose material, comprising, in combination, a drying chamber, agitating tables therein, a heat regenerator communieating therewith, a' removable screen arranged between the drying chamber and the regenerator, and means for removing air from the drying chamber through said screen and regenerator.

14. In a drier, in combination with a heat insulating casing, chambers Within the Casing respectively for means Jfor moving the material to. be dried into, through, and out o'l contact with dry air. said chamber having an air educt passage; Jfor means for heating the air, said chamber having an air-inlet passage and for a radiating surface separating the air-educt passage from the drying chamber and the air-inlet passage.

i5. ln a drier, in combination with a heat insulating casing, chambers side by side within the casing respectively for means for moving the material to be dried into, through, and out of contact With dry air, and tor means for heating the air; and a chamber above one of said chambers and Within said casing having therein a radiating` sui-tace separating an air-educt passage trom the drying chamber, and an air-inlet tor the heating chamber.

16. In a heat-interchange pre-heater for driers, the combination with an insulating casing of a number of exhaust-air outlet tubes in parallel relation, baiiles supporting the tubes and providing a sinuous passage about them, inlet and outlet opening at each end of said sinuous passage and said exhaustair tubes respectively, and suitable connections therefrom respectively tothe educt and induct air passage of the drier.

17. Inra drier, incombination with a drying chamber and means for feeding a stream of light material from level to level Jherein, means for moving the contained air of said chamber and withdrawing the Saturated or exhausted air comprising means for causing the incoming air and outgoing air to flow through the planes of said levels, whereby to avoid currents along or across said levels and prevent substantial air-borne portage of the material.

Signed by me at Boston, Massachusetts, this twenty-fourth day of May, 1921.

JOSEPH H. WALSH.

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