US1680013A

US1680013A - Dry kiln and the art of kiln drying

Info

Publication number: US1680013A
Application number: US135891A
Authority: US
Inventors: Cobb J Forrest
Original assignee: Moore Dry Kiln Co
Current assignee: Moore Dry Kiln Co
Priority date: 1926-09-16
Filing date: 1926-09-16
Publication date: 1928-08-07
Anticipated expiration: 1945-08-07

Description

Aug. 7, 1928.

J. F. COBB DRY KILN AND THE ART OF KILN DRYING Filed Sept. 16, 1926 2 Sheets-Sheet J. For/esf- 0,62).

Aug. 7, 192s. 1.680.013

J. F. COBB DRY KILN AND THE ART OF KILN DRYING Filed Sept. 16, 1926 2 Sheets-Sheet 2 J lib/wwf Cobb- Patented Aug. 7, 1928.4

UNITED STATES 1,680,013 PATENT OFFICE.

J. FoRaEsT CORR, OF PORTLAND, OREGON, AssIoNOR To MOORE DRY xiLN COMPANY, JACKSONVILLE, FLORIDA, A CORPORATION OR FLORLOA.

DRY KILN AND THE ART QF XILN DBYING.

Applicaties ined sepmber is, 192e. semi No. 135,891.

My invention relates to the art of kiln drying and to dry kilns of the type in which circulation of the atmosphere of a kiln is effected by the rotation of a series of powerdriven rotary fans operably mounted within the kiln.

The main Object of my invention is-to provide a circulation within a kiln of the entire volume of the gaseous contents of the kiln,

l0 as a whole, wherein the volume of gas on one side ofthe drying stock is drawn through the interstices in the stock'to the other side thereof, and thence back again to the side lirst named in constant circulation.

In the said course of circulation the gas is kept properly humidified and raritied to effect the best dryin results. A

' Another object o my invention is to provide in a kiln novel means for operatively mounting the fans aforesaid, wherein the result of an exceedingl stable and durable kiln structure is arrived7 at, with due regard to economy, and whereb the functional efficienc of the kiln, both in regard to the uniy formity of the drying operation, its reo'ulation and control, is materially enhanced? What constitutes my invention will be hereinafter specified in detail and succinctly defined in the appended claims..

In the accompanying drawings, -wherein my invention is illustrated in present preferred form of embodiment, i

vFigure I is a partial round planof one of my kilns taken in al ane above, the lioor w ich forms the top o the fan-duct thereof, the middle portion of the kiln being broken away in order to accommodate the desired scale of the drawing, andthe floor aforesaid being broken away at its opposite ends in order to expose to view the heatingv coils that I are disposed'below it.

Figure II is a' longitudinal vertical section of the subject matter of.Figui-e I as shown therein, and showing also the details, including the superstructure, of the kiln.

i Figure III is a transverse vertical section taken on the line III--III of Figure II.

Referring to the numerals on the drawings, l'indicate's the bottom, 2 and 3 the opposite side walls, and 4f the roof of a l {i1n which is made, preferably throughout, of concrete construction, the bottom bein made suiciently heavy and of a properdistribution of its thickness to support the distribu- 55 tion of the weight it has l2? arry.

.walls 9 The roof 4 is provided at suitable intervals with damper-controlled ventilators 5, disposed in two series along the opposite sides of the roof. The opposite end openings in the kiln chamber located above the end walls 6 and 7 of the base of the kiln are closed, during the operation of the'kiln, b respective doors 8, which may be, in' eac instance, of any preferred type that is suitable for the purpose.

A distinctive feature of my present invention is to be found in the fan-duct of the apparatus which comprises a continuous vertical wall extending substantially from end to end of the kiln, and preferably in the lower part of the kiln, in a zigzag direction, substantially as shown in plan view in Figure I. The zigzag effect of said wall is achieved by dividing the length of the kiln into medial compartments, of substantially uniform and preferred dimensions, by a series of alternately disposed substantially parallel artition walls 9 and 10, each of the eing solid, and each of the walls 10 being provided with an aperture of suitable dimensions to accommodate within it one of a series of rotary fans 11. Each air of next adjacent walls 9 and 10 is unite on one side b a solidvertica'l wall 12, constituting in e ect a closure on one side for the compartment to which it is appropriated, the side of the'compartment opposite each wall 12 being open.

The walls 12 are disposed, res ectivel in succession on alternate sides of t e fanuct, so as to divide the series of compartments into units Of which each alternate one is open on one side and closed on the other side. The result of the disposition just described of the several walls 9, 10 and 12,is.to impart, in their assemblage,to the length of the entire Vwall so constitutedthe `zigzag diiiction already designated.

The angle at which the walls 9`-and 1() meet the walls 12, res ctively, is shown in the drawings as a rig t angle; and that is at present deemed to be the preferable angle, but it is obvious that the angle may be varied if desired,4 as in some instanceslit may be.

Each of the walls last named is planted firml on theV bottom 1 of the kiln, with whic in the concrete construction preferred, it is incorporated. The faii-duct is coin leted by a floor 14 which is laid, with airtight closure, 0n the top 0f tbe'wells 9, 10 and 12,.

The door 14 is preferably rovided on opposite sides with upstan ing lateral flanges 15, which, when made of concrete, is incorporated with the said floor and walls in a unitary concrete construction. The floor 14 is reinforced and supfported at required intervals by cross gir ers 16, preferably I beams, whose opposite ends are let into and supported by the side walls 2 and 3, respectively, of the kiln.

The floor 14 carries track rails 17, and is for that reason preferably but not necessarily, particularly if but one end door is used, inclined slightly towards the outlet door 8 of the kiln, in order to utilize the force of gravity to facilitate propulsion along the track `to the point of exit of trucks 18, when they are loaded with stock to be dried in the kiln. The height and width of the two corridors 19 and 20 that are defined on the outside of the 4fan-duct by the side walls 2 and 3 and the floor 14, respectively, should be sufficient to accommodate workmen within them -with space for freedom of actionA as occasion may re uire, it being taken into account that sai corridors are provided, respectively, with substantially longitudinally coextensive fresh air ducts 21 and 22 through lateral apertures 23 in which rovision' is made for admission in reguated quantity, of a su ply of fresh, atmospheric air as often as esired, the said fresh air ducts being supplied with outside air through terminal, door-controlled, air intake openin 24.

Below the level of the bottom of the floor 14, in the respective corridors 19 and 20, are disposed heating means, preferably coils of

pipe

25 and 26, arranged in any suitable and preferred system'for distribution of heat, preferably steam heat that may be derived from any preferred source of steam supply, not illustrated.

A variety of steam and other heating systems being well known,in the art, it is deemed unnecessary to specify more in detail the particular'systern illustrated,.inas much as it constitutes, in itself, no part of my present invention.

The complement of fans 11 is driven preferably by a single shaft 27 carried in suitable aligned bearings in upright 'supports 28 'erected on theV bottom 1' of the kiln. The shaft 27extends' through the succession of walls 9 and 10 and preferably to the outside of the end wall 6, where it 'is operatively connected, as byY a flexible coupling 29, to a motor, for example an electric motor 30, preferably located, with other incidental elements unnecessary to specify, in a housing chamber 31.

The shaft 2( may be driven in'one direction only, or if provided, as it may be, with suitable reversible fans, its direction of rotation may be reversed at will, with the cffect, in reversal, of the direction of circulation of the atmosphere of the kiln.

I prefer to provide each one of the series of compartments, defined, respectively, by the zigzag wall above described, with a sidewing detlecting baffle 32 (compare Figures I and III), whereby uniform direction is imparted to the currents of the circulatory medium in the kiln.

The baiiles 32 are preferably located substantially in the middle of each compart- -ment, and are, respectively, of a length equal to one half of the width of the compartmeiit. Bytheir disposition, the baille is caused, in effect, to split, with increase of its efficiency, the currentof the circulatory medium as discharged from each compartment. The outside wing 33 of each baille 32 is, in effect, hinged to the baille for control of the direction of movement, preferably by a permanent flexure, whereby the angle of each wing may be conveniently adjusted if required by application of force sufficient to bend the metal of which it issconstituted.

The stock 34 to be dried in the kiln, when of lumber, is loaded in a stack or stacks upon such number of trucks 18 as may be requisite, and the method of stack piling may be of the horizontal order or of any other that may be referred.- In the drawings the stock is il ustrated as horizontally pi ed, and in such case a fin 35, depending towards the stock pile from the middle of the roof 4 may be employed to advantage for compelling the kiln'atmosphere under pressure to circulate through the horizontal spaces between the stock in the pile instead of over the top ,of the stack.

It is proper to add, that it is deemed unnecessary to specify all details of the heating system, besides means common in the art for automatically humidifying and ventilating the atmosphere of the kiln, but that variation of said details at will are contemlated as coming within the scope of my invention.

At intervals within the kiln, Iprefer to provide spray pipes 36, which may be made at will to discharge a spray as of steam, air, or even water into the atmosphplie of the kiln for the pur se offproper y' uniidifying it. lA hu'mi ity-control box 37, of any well known or suitable type preferred,

located in the housing chamber 31, may be used if desired.

Each of the two series of ventilators is' o ened at a time on one side only. of the kiln, their purpose being to lead off spent or used drying medium as it accumulates in the operation of the Discharge from the open ventilators of a'series is made from the side of the kiln which is opposite tothe discharge side of the fan-duct.

Fresh air through the ducts 21 or 22 is introduced only on the suction side of the fan system, which, it should be observed is, in view of the potential reversibility of the direction of rotation of the fans, a tcrm of dual significance.

A description of the operation of my kiln, including specification of certain features of my invention, in so far as it pertains to the art of kiln drying, follows in immediate sequence.

Assuming a kiln to be built along lines in substantial conformity to those illustrated in the drawings and to be equipped with opera: tive mechanism substantially equivalent to that illustrated, if it be assumed that the kiln is supplied with material to be dried. represented by the truck load 34, that the doors (or door) 8 are closed.- and that the

coils

25 and 26 are heated, the drying operation is ready to start.

Thereupon the motor 30 is set in motion which is communicated to the fans 11 as by aid of the shaft 27.

Each fan, as has been specified, operates upon the gaseous contents of two contiguous compartments, upon one compartment with suction effect and upon the other with pressure effect. v

Bearing in mind that the direction or rotation of the fans is reversible, and that consequently one compartment may be at one time the suction side of.the fan. and that upon reversal of movement of the fan, it will be converted to the pressure side thereof, it will be understood that all the fans operate in unison to effect a substantial uniformity of suction on one side of the interior of the kiln, and to exert a correspondingr pneumatic pressure on the other side of the kiln.

Wherefore, one side of the kiln while in operation is denominated the suction side. and the opposite side the pressure side of the kiln. The applicability of the names just indicated depends, as has just been pointed out, upon the direction of rotation of the complement of fans. The pneumatic pressure generated bv the fans may be by the baffle wings 33, directed towardsl one end or both ends of the kiln -with the effect of producing circulation of the atmosphere of the kiln`both longitudinally and transversely in respect to the interior of the kiln, in order to satisfy the demands of the kiln conditions.

By reason of the presence of the depending fn 35 above the stock load and of the lateral flanges 15 of the floor 14 below the same on the outside of the wheels of the trucks 18, the result of the coacting suction and pressure forces s.lby their push and pull coaction, forcibly to drive the circulatory medium with quick, powerful and uniform drying effect through the interstices provided for circulation through the pile of stock 34.

An important feature of my invention is the method by which each fan unit is provided with one inlet and one outlet of circulatory medium for each fan in whichever direction the fan revolves. It is by multiplication of said fan units that the result in kiln ldrying is achieved of utilizing a unified drying current, with material increase in efficiency form a volume of air standpoint.

In regard to operation of the ventilators in two series, it should be considered that in the operation of any drying kiln the circula-A tory medium soon becomes heavily charged with the liquid constituents of the drying material. The excess moisture so derived must be properly drawn oft' in order to maintain the efficiency of the apparatus. By providing two series of ventilators 5 and operating only one series at a time, the excess of moisture aforesaid may be kept properly drawn off. The fresh air ducts 21 and 22 contribute to the same end by substituting for the spent atmosphere of the. kiln that is drawn off, fresh outside air of superior drying quality. The correctness of the rinciple upon which the ventilators and resh air ducts operate, respectively; is well recognized in the art. but the successful application of that principle is promoted by my invention, whereby provision is made on one'side ofthe kiln for drawing off the spent atmosphere immediately after it has passed throughthe drying stock and becomes thereby sureharged with moisture, and then supplying fresh air from the fresh air duct which is located on the same side of the kiln as the active series of ventilators is located, it being understood, of course, that when the fresh air duct 21 is open, the duct 22 is closed, and contrariwise. When the duct 21 is open, the series. of v'entilators on the same side of the kiln as the duct 2l is open and the ventilators of the series' on that side on which the duct 22 is located are closed as well as the duct.

Provision of two fresh air ducts and two corresponding series of ventilators is made in order to effect the practical reversibility of the fans, already specified.

In the operations which have been descrbed of drawing off the spent atmosphere of the kiln and the introduction of fresh air in place of it, it is impracticable to measure those operations with' any degree of exactitude. For that reason` in part, I employ the spray pipes 36 whose function is to provide means for maintaining the humidity of the kiln atmosphere substantially at normal.

Another resultant advantage of method of circulation accomplished by my invention is that the vcirulatory medium in each complete circuit is, in descending and in ascending currents, respectively, twice passed through the two heatingcoils that are disposed, respectively, on opposite sides of the kiln.

The advantage afforded by my lnyention the circulation in the kiln is contributory, and

under some conditions may be necessary.

What I claim is: A

1. A dry kiln compri-sing within it a`fanduct defined, in part, by a continuous substantially vertical wall extending substantially the full length of the kiln in a zigzag direction.

2. A dry kiln comprising within it a fanduct defined, in part, by a continuous substantially vertical wall extending .substantially the full length of the kiln in a zigzag direction, said wall including aseries of alternately disposed partition walls', of which each alternate one is solid and each alternate one is providedwith an aperture for accoinmodationwithin it of a fan.

3. A dry kiln comprisinv a bottom, avertical fan-duct defining wall, and a floor laid` on said wall, all being ofvunitary concrete. construction, saidA wall being composed of alternately disposed solid and a ertured v partitions united on one side thereo respectively, to solid walls disposed successively on opposite sides of the duct, whereby a zig-v zag direction is `imparted to the. fan-duct defining wall as a whole.

4. The combi-nation with the outside walls of a kiln of a zigzag fan-duct defining a wall extendingV substantially the full length of the kiln and'comprising alternately disposed solid and apertured partition walls, respectively of rotating fans operatively mounted in the apertiired partition walls, respectively,

` and driving means in operative communication with the respective fans. A

5. A dry kiln comprzsingwithin it a fanduct defined, in part, by a continuousl submuy the wall extending substanf-ull length of the kiln in a zigzag said wall including a. sei-ies of alternately disposed partition walls, -of which each alternateone is solid and each alternate one isv provided with an aperture for accommodation within it of a. fan, said fan-duct being located in the lower art of the kiln, 4a floor above the fan-duct, eating means locatedon opposite sides of a respectively, adjacent to the `said floor, whereby circulatiomof the circulatory mestantially vertic direction,

kiln, j

dium of the kiln produced by rotation of the fans is caused, in passing from one side to the other of the kiln, to pass twice through said respective heating means.

6. In a dry kiln, asubstantially vertical wall extending longitudinally of said kiln and having a pluralit of substantially transverse partition wals, alternate partition walls having an opening, a common drive shaft extending longitudinally through allof said partition walls, and apliirality of fans mounted upon said shaft and disposed in the openings of alternate partition walls.

7. The combination with a'dry kiln, of a fan unit consisting of a vertical wall extending substantially longitudinally of the kiln, substantially transverse walls associatedtherewith and providing a pair ofcommunieating compartments opening toward opposite sides of the kiln, and means inducing circulation of air from one compartment to the other, one of said compartments constituting an inlet on one side of said means and thc other compartment constituting an outlet on the other side of said means.

8. The combination with a dry kiln, a 90 yertical wa'll arranged centrally and extend-1 ing substant: ally longitudinally of the kiln," transverse partition walls extended from o posite sides of said vertical wall to provi e a pair of compartments opening toward oppos'te sides of the kiln, means o communica.-l tion between said compartments, and reversible means associated with said means ef communication for inducing circulation of` air fromv one compartment to the other. 1"

9. The combination with a dry kiln, of a "fan unit consisting of a vertical wall extending substantially'longitudinally of the kiln, su stantially transverse walls associated therewith and providing a pairof communieating compartments opening toward opposite sides 'of the kiln, and means inducing circulation of air from one compartment to the other, one ofsaid compartments constituting an inlet on one side of said means and the other compartment constituting an out-A let on the other'side of said means, and a vertical baille arranged substantially transversely in eaicli compartment and terminating adjacent the middle thereof. n

10. The combination with a dry kilrg" of a fan unit consisting of .communicating compartments and an intermediate rotary fan, one of said compartments 4constituting an inlet on one side of the fan andthe other compartment an outlet on the other s'zde of' the fan, and a baille arranged intermediate each com the midd e thereof.

In testimony whereof, I have hereunto set my hand.

J. FORREST COBB.

artment and terminating adjacent Y