US1543344A - Reversible-circulation internal-fan kiln - Google Patents

Description

June 23, 1925.

lllsil 3 Sheets-Sheet l R. THELEN Original Filed April 19, 1924,

INVENTOR. Wk? HELEN ATTORNEYS.

Fiq i REVERSIBLE CIRCULATION INTERNAL FAN KILN M J.\ M

-' 5;; a R. THELEN REVERSIBLE CIRCULATION INTERNAL FAN KILN Original Filed April 19, 1924 3 Sheets-Shed 2 INVENTOR. 01. HELEN BY 412M ,I. a .W a; a. ATTORNEYS;

R. THELEN REVERSIBLE CIRCULATION INTERNAL FAN KILN Original Fiied April 1.9, 1,924 3 Sheets-sheaf 31 INVENTOR.

N ROL,F' THTEIEN A TTORNEYS.

Patented June 23, 1925.

UNITED STATES PATENT oF-ricE.

; ass THELEN, or MADISON, WISCONSIN,

THE PEOPLE or THE UNITED STATES.

REVERSIBLE-CIRCULATION INTERNAL-FAN KILN.

or nal application filed April 19,1924, Serial No.708,323. Divided and this application filed llarch 7,1925. Seria1,No.14.424.

nnnzonrnn, BY MESNE ASSIGNMENTS (GRANTED UNDER THE ACT OF MARCH 3, 1883; 22 STAT. L. 625.)

1, To allwhom it may concern:

Be it known that I, Rom Tureen, a citi zen of the United States of America, and an employee of the Department of Agricul- 5,=t iire, residin -in Madison, \Visconsin (whose )ost-ofiice address is Forest Products Laboia atory, Madison, Wisconsin), have invented ;.& new and Improved Reversibio-Circulation :Ii iternal-Fan Kiln.

0,, This application is a division of an appli- ;.f.Lf3itl0D.: filed April 19, 1924, which bears Serial Number 708,323.

e This application is made under the act o :E of March 3,1883, chapter 143 (22 Stat. 625), Land; the invention herein described and ,-;i. c laimed.may be used by the Government of .thejUnited States, its ofiicers and employees, .spndiby :any person in the United States B Yi thout the, payment to me of any royalty iereon. --I hereby dedicate the same t'o-the, il-cc {use of the Government and the people of the United States.

eggdtlyinvention consists in an improvement linthe design of forced circulation kilns or 25 chambers for drying and conditioning lumber. or similar material. However, its use is not limited to wood. or wood products. It consists in the adaptation of fans of the disk type, or similar types, to the. production of' .a unique internal circulation of air and the vapor in the kiln combined with the p reductionsand regulation of the heat and the humidit within the kiln.

. This invention is illustrated in Figures 1 to 3. Figure 1 represents a horizontal section taken .on diiicrcnt horizontal planes principally at about the rail height. Figure'2 represents a cross-sectional elevation. Figure 3 represents a longitudinal elevation 40 .ofa portion of tlie'air circulating and distributing system.

The principal feature which 1 claim as novel and an improvement over existing kilns is the use and arrangement of the fans and the air distributing system. This arrangement is such that a very fast and uniform circulation of air and vapor through the piles of lumber may be securedand it.

permits. the periodicl evensal )fth'. direc- 0 tion-of the air movement by simply reversingthe direction of rotation of the fans. The air distributing system provides a very uniform fiow'of air throughout the length and breadth of the kiln and eliminates the non-uniformity of drying, which is one of the commonest troubles experienced in the ordinary kiln. The arrangement of the fans upon a shaft extendingthroughout the length of'the kiln provides a simple means of producing a brisk circulation; and the elimination of comparatively small ducts such as those used in external blower kilns reduces very materially the work required to produce a given circulation; The difierences in air pressure required in the opera: tion of this kilnare much smaller than those ordinarily required in kilns employing centrifugal blowers, and the disk fans operate very efficiently at these low' ressures. Measurements recently made indicate that the static pressures necessary for the suc cessful operation of this system are materially less than one-eighth of an inch of water pressure. It is possible, therefore, by the use of this invention to produce a very great and uniform cireulationof air and vapor within the kiln with a very small expenditure of power.

While it is obvious that there are many thickness and length being in horizontal directions. Any well-known means of heating the air and .the vapor in the kiln may be used in conjunction with this invention. When steam pipes are used they-may be arranged beneath the lumber piles at the sides of the kiln or in any other convenient manner. Any convenient form and arrangement of heaters may be used.

The drawings show and the specification describes steam jet pipes for increasing the humidity, and air inlet fines and air outlet flucs with suitable dampers for decreasing the humidity. m

While thedrawings show and the specification describes specific means for heating the air and the vaporin the kiln "and for regulating the humiditfof the'air in the of the fans.

make use of any other well-known and suitable means for accomplishing the same purrails, trucks, and track supports illustratedin the drawings and described in the speclfication.

Referring to Figures 1, 2, and 3, which are correspondingly lettered: BB are theifans producing the circulation. Straight-bladed .disk fans are preferable. Any type of fan, however, in which the reversal of the direction of. rotation of the fan produces a reversal in the direction of the flow of the air current passing through the fan can be used. C is the shaft upon which the fans are mounted. Provision is made to take care of the expansion. and contraction of this shaft with changes in the temperature in the kiln and to take care of the thrust This provision consists in equipping one of the bearings II with suitable thrust rings or collars and equipping all of the other bearings II with any wellknown means for longitudinal motion. Plain bearings and roller bearings require no special provision of thiskind. Certain types of ballbearings require housings which permit the entire hearings to slide longitudinally within them. DD are air inlet dampers used to regulate and control the amount of air entering the kiln from the outside. EE are the heating coils. These may be of the return bend type or other convenient type. F is the steam jet pipe used to increase the humidity of the air in the kiln. Suitable openings are provided to permit the escape of the steam throughout the length of the kiln. Various other common and well-known arrangements may be used. GG are the lumber-supporting trucks. II arebearings for the shaft U. JJ are the tracks upon which the lumbersupporting trucks run. KK are the side walls of the kiln. LL is the lumber to be dried. hfM are the track supports. 'N is the shaft pulley. 00 are air outlet dampers for controlling the amount of air being exhausted from the -kiln. P is a belt passing over the pulleys N and Q. Q, is the motor'pulley. R is the motor which furnishes the power to drive the fans. S is the switch for controlling the speed a d rotation of the motor armature. While t e drawings show and the specification describes an electric motor, any other suitable driving means may be used. -TT are air inlet lines in which the dampers DD are tied. UU are the air outlet fluesin which I the da apers 00 are fitted. WW are the side air passages between the piles of lumber and the side walls of the kiln. XX are the main air distributors. YY are the second difi'users. ZZ are the first diffusers. The plenum chambers between the second diffusers and the first difiusers' are the secondary plenum chambers 126 are the fan houslugs and partitions. f are bafiies. While the drawings show an the specification describes certain specific arrangement of the fans and shaft, this invention is not limited to this particular arrangement, since it is obvious that its functions can be performed in an equivalent manner with other arrangements of the fans.

The operation of the kiln is briefi follows: The lumber is placed in the kiln, the doors and all of the dampers are closed and the kiln is started. Steam is turned I into the coils and the steam jets are turned on. Suitable regulating devices are provided to control and regulate the supply of steam to the heating coils and the supply of the steam to the steam jets. If it is found impossible to reduce the humidity to the desired point with the steam em all turned off, the dampers DD and (l opened to allow :Eresh'airv to enter and moist air to escape. adjusted so that a humidity below that desired will besecured. The steam jets may then supply a suflicient amount of steam to bring the humidity up to the desired point. Assuming that the direction of ro- O are v These dampers should be tation of the fans is such that the air and Y slight vacuum. When the direction of the circulation is reversed the upper chambers are under vacuum and the lower ones under pressure. The velocity of the air movement through these chambers is comparatively slow. The use of these plenum chambers and the various sets of diffusers in the manner indicated produces a very uniform flow of air through the length of the kiln. It is obvious that the kiln would work reasonably well with single sets of diffusers for elach main air distributor and that still furt ier and upward through uniformity in air distribution mi ht-be secured by adding a third or even a ourth set of difiusers. The principle, of course, remains the same and practical expediency will determine the balance between increased uniformity of air distribution secured by I the addition lei-{mere sets of distributors- '-.-.b gween he slats running the full lengthand-the loss in e'fiiciency which they cause.

; isalso obvious that any well-known form of distributor may be used.- The invention is-not restricted to the form illustrated in which-the-openings consist simply of spaces ioi with a great many different types of forced circulatmnin dry 'kilns that it is not 1105- Isibl'e l to. secure" uniformity of distribution of th se; and vapor if they be handled at "high"- velcities order to produce uniform: satisfactory; circu1ation, it is essential that the. air aridvapo'r be moved at low' ve-fv 'locitieslandithapsf ecial means be'provided forthe 'uniform distribution of the air and fv vapo1fthrough the kiln. '-'.The use of internal -f an"s"-'-and large plenum chambers produces f-thi's result; since. the velocity of the .air and 'vapor-' throulghfthe fans themselves is coniparatively. ow. and; theivelocity, in .i the plenum chambers; is so small that the yefloc'pity head can not-be measured with manonr eters and sim ilar=. instruments usually. used fortheipiirpose.

i culation: of theairzirid theivapor inkthe vk1l1i-f.is -continiiously inone' direction, that portion"- o f;:tho1pile at which the air enters win 1d fmorerapidly thanthe '-,s in ce t ejair. in'its Jpassaget rough the l-umber picks up. moisture and thus reduces its ,ca acity. The reversal of-the direction of t e air-circulation overcomes this defect -since that edge of each lumber pile-which was the entering aired e before reversa1 .becomes'the leaving air e ge-after reversal, Those'portions oi the piles which driedt fastest before reversal dry most "slowl after reversal. The reversal ofthe fcircu ation-will in; practice he done periodically every two or three days or oftcner,

'the'exact period being determined by the- .of air and vapor through the lumber to be dried, and any detailed arrangement which will accomplish this result will be satisfac to'ry-if at the 'same time it does not consume' an excessive amount ofpower.

Ha'vihgfullydescribed the principles j housing and ofiposite side original:

In doubleiwek newt-agar can be embodied in 'a drykiln, I claim as v e. .1 for'edge stacking: a series of fans mounted between the-two rows'of lumber-pilesga shaft on which the fans are mounted forf'i i I rotation;=mea ns for rotating" saidjshaft-iin- I It has been found through experience,

either direction to cause reversal-of the-cirmain air distributors, and two of insets for each main air-distribution- 12. Ina double trackdry'kfln arranged for edge stacking: a series ofzfansmo'unted he tween the two rows oflurnber' piles a shaft on which the fans are mountedfor rotation;

means for rotating said shaft'fin either-(ii? rection to causereversalof the circulation air inlet flues -'anddamperedair outlet fines;

and an. air distributingsystein'comprising fan housing and 'pa'rtition for each fan, two

main air distributors; v and two sets of 'dif-' fusers for each-main air distributor. T

ofa'ir and vapor in said kilu.;:dampered 3. In a double track dry kiln arranged comprising fan housing and partition for each fan, two main air distributors;- and two sets of diffusers, for tributmz 3 e. In a double track dry kiln arranged'for each main air disiedge'istackingi a: "series,ofiansqmounted between jthe two-rows of lumber piles; a "shaft-on which the fans are mounted for rotation; meansv for rotating saidishait in o the kiln and edgestacking: a series of fans mounted between the two rows of lumber piles; a shaft on which the fans are mounted for-rotation;- means-for rotating said shaft in either di- 'rection to cause reversalof-the circulation of air and vapor insaid kiln; dampcred air inlet fines and dampered air outlet-fines; means for heating the kiln and its contents; and an air distr butingsystem comprising fan housing and partition for each fan, two main air distributors, and two sets of diffusers for each main air-distributor.

February 1%), 1925.

fioo

as ,culation of .air and vapor in'said and. an aindistributin'gsystem compnsingnfan artitionfor each ifan, two

Images