US1268180A - Dry-kiln. - Google Patents

Description

H. l). TIEMANN.

DRY KILN.

APPLICATION FILED FEB. 20. I9I'7.

lartented June 4, 1918.

2 SHEETSSHEET 2- IWT /l /l/l IINI HARRY DONLD TIEMANN, OF MADISON, WISCQNSIN.

nav-Kinn.

'Specication of Letters Patent.

Patenten aan@ a, raie.

Application led February 20, 1917. Serial No. 149.972.

To all whom t may concern:

Be it known that I, HARRY DONALD Tm- MANN, a citizen of the United States of America', and an employee of the Department of Agriculture of the said United States, residing at Madison, in the county of Dane, State of Wisconsin, (whose postoliice address is Madison, Wisconsin,) have invented a new and useful Improvement in Dry-Kilns.

This application is made under the act of March 3, 1883,@11. 143 (22 Stat., 625), and

the invention herein described and claimed,

may be used by the Government ofv the United States, or any of itsoiicers or employees, in the prosecution of work for the Government or any person in the United States, without payment to me of any royalty thereon.

My invention relates to kilns for drying lumber or other articles.

The object ofmy invention is to provide an improvement in a kiln for drying flat piled lumber by means of superheated steaml at atmospheric pressure.

The features of my invention are:

(l) An arrangement of parts so that the principle of a high circulation of steam through the lumber at a low degree of suerheat may be utilized with flat piled lumer, thus doing away with the necessity' of special forms of truck necessary for edged stackin as have been used heretofore.

.(2) n arrangement for reversing the direction of the circulation current by simply closing and openin valves, and

(3) Means where y the superheat of the steam as it passes through the lumber isl pre` vented from Vdroppin to the saturation point, said means conslsting of a reheating coil of pipes placed between the piles and lumber.

The object, characteristic features, and scope of my invention will be more readily understood from the following description taken in connection with the accompanying drawings wherein:

Fi re lis a vertical sectional view across the kiln showing two fiat piles of lumber.

Fig.- 2 is a vertical section through the kiln longitudinally in the plane, M N,

Fig. 1.

eferring to the drawings, the drying chamber is designated, a, containing two flat piles of lumber, as shown at A, the boards (DEDICATED T0 THE PUBLIC.)

running in a direction perpendicular to the plane of the paper. The lumber is piled in the ordinary manner upon simple bunks, b, which run upon rails, K.' Immediately beneath the rails, K, isa solid horizontally placed shield, D, with vertically projecting ends, E. Suspended from the roof of the chamber a, is'a similar shield, B, having vertically projecting ends, C. These shields, B and D, form two narrow fiues, G and J, within the kiln chamber, a, in which are placed the steam jets, for forcing the circulation. These jets are formed by erforating Va high pressure steam pipe with small holes about 33E to it, of an inch in diameter and spaced every 12 or 18 inches. The steam jet pipes are shown in four pairs placed at F, F', F and F Each pair consists of two separate pipes,P d and d', with their respective perforations facing in opposite directions in a horizontal plane. The pipes d and d are controlled by independent valves c and e', so that the direction of the steam jets may be directed either to the right or to the left at will by closing and opening the respective valves, e and e thus reversing the direction of the circulation. While I have shown two pairs of steam pipes in each of the passageways, G and J, a single pair may sometimes answer the purpose or more than two ma be used, the plurality of these pipes not a ecting the principle of my invention. H represents high pressure steam pipes placed near either side wall of the kiln for the purpose of superheatin the steam. H is a coil of steam pipes place between the two loads of lumer for the purpose of reheating the steam during its passage owing to its rapid loss of heat by4 contact with the lumber. The direction of the currents of vapor is indicated by the arrows, asproduced by one set of steam jets, d. When the other set of jets, d',

is brought into operation, and the first set, d, is turned oil", the circulation will be in the opposite direction. The end projections, C and E, of the two shields, B and D, respectively', are for the purpose of preventing eddy currents'and directing the vapor uniforml throu h all layers of the pile of lumber. It has baiiles, C and E, a swirling or vortex motion of the vapor occurs near the two ends of the pile which may cause the motion through the lumber to be reversed at these een found that wlthout these points. Lris a tight fitting door closing the 'front of the kiln and, P, is a vent to the outer atmosphere with` a 'through the piles check valve, h, opening outwardly, for the escape of excess vapor. In practising my invention, the cold wet lumber is first run into the kiln and the doors, L, are tightly closed.

The steam jets, d, for example, facing one way are then turned on full with steam pressure of 2O to 6() pounds gage which causes a rapid circulation of saturated steam e cut down until aconstant temperature is se-v gi'ns to pass oif rapidly cured. ,As the temperature of the wet lumber gradually rises to 212, the water vbeby. boiling, and at this point the excess pressure produced by the steam from the steam jets, d, and the vapor from the lumber, forces the excess out through the vent, P, or through any leakages in the kiln. When this operation has continued until that portion of the piles nearest the pinging vapor has become sufficiently d the length of time, depending upon the kind, thickness,` and moisture condition of the lumber, the first steam jets, d, are turned oif and the jets, d', facing the opposite way are turned on, thus reversing the entire circulation, and bringing about a rapid drying of the opposite sides of the piles. This condition is held until the lumber has reached the desired degree of dryness, or the circulatior may be reversed a number of times during the drying. The reversal of the circulation enables considerably wider piles to be used than is possible where the circ lation is all in the one direction.

The evaporating capacity of superheated steam is proportional to the product of the weight of steam coming in contact with the lumber times the number of degrees -it is heated above the boiling point. Therefore, by greatly increasin l the velocity of the steam passing throng the lumber, its temperature may be correspondingly reduced without losing any of its drying capacity. One objection to the use of superheated steam for drying lumber is the rapidity with which it parts with its heat and is reduced to the saturated condition where it can produce no more drying. With slow circulaas shown by the arrows.` very rapidly and wets y `rection, heating pipes 'the-.boiling point, and a vent 'the iioor and near the ceiling of tion` this 'causes the portion of the piles lof* lumber with which the steam first comes in contact to dry very rapidly while the far side of the piles dries very little or not 'at all. Byforcing a rapid circulation, keeping the piles very narrow, not over four feet in width, and reheating the vapor as it passes from one pile to the next and, by reversing the circulation during the drying operations so that the damp sides of the piles may in turn receive the direct heat from the impinging steam, the difficultypractically disappears.

The use of superheated steam has been found practicable with many softwoods or conifers, but is not applicable to most of the hardwoods owing to the injurious effect of the high temperature in many of the latter species.

From the foregoing, it is thought that the construction, operation and many advantages of the herein described invention will be apparent to those skilled in the art, without further description, and it will be understood that various changes in the size, shape, proportion, and minor details of construction may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention. Y

Having thus described my-finvention, f claim:

1. In a dry kiln for receiving piles of fiat piled lumber, shields above and below the piles forming passageways, steam jets in these passageways for forcing the circulation, heating pipes near the side walls of the kiln, heating pipes between the piles of lumber, and a vent for escape of excess vapor. v

2. In a dry kiln for receiving piles of flat piled lumber; shields above and below the piles forming passageways, steam jets in these passageways for forcing the circulation in one direction; other steam jets in the same passageways for forcing the circulation in the opposite direction, heating pipes placed near the side walls, and a vent for the escape of excess vapor.

3. In a dry kiln, shields placed near the ceiling and near the floor forming passageways, steam jets in these passageways for forcing the circulation in one direction, other steam jets in said passageways for forcing the circulation in the opposite diplaced'in the current of vapor for superheati'- g the same above for the escape of excess va or.

4. In a c amber for drying lumber or other moisture bearing material, shields near said chamber forming passageways, steam jets in these passageways for forcing the circulation in one direction, other steam jets in said passageways -for forcing the 'circulation in lthe opposite direction, heating pipes in the current of vapor for superheating the same above the boiling point, and a vent for the escape of excess vapor.

5L In a dry kiln for receiving piles of Hat piled lumber in said kiln, trucks to hold said piles of lumber, rails upon which the trucks are rolled, a movable door in the front of the kiln, a shield beneath the piles of lumber forming a passageway between the shield and the floor, another shield above the piles of lumber forming a passageway between the shield and the roof, bame plates attached to the ends of the shields, steam jets in said passageways for forcing the circulation in one direction and other steam jets in said passageways for forcing the circulationv in the reverse direction, heating pipes near the side walls of the kiln in the current of vapor, heating pipes between the piles of lumber, and a vent for the escape of excess vapor. l

In testimony whereof, I alix my signature in the presence of two subscribing witnesses.

HARRY DONALD TIEMANN.

Witnesses:

ALFRED W. DoHR, CHAs. P. JUCKEM.

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