US1662807A - Dry kiln - Google Patents

Description

March 13, 1928.

F M. CREIGHTON ET AL DRY KILN Patented Mar. 13, 1928.

UNITED STATES 1,662,807 PATENT OFFICE.-

FRANK'M. GREIGHTON, OF AMERICUS, GEORGIA, AND WILLIAM E. GRAY, OF MEMPHIS,

TENNESSEE, ASSIGNORS TO MOORE DRY KILN COMPANY, OF JACKSONVILLE, FLOR- IDA, A CORPORATION or FLORIDA.

' DRY KILN.

Application filed April 13, 1926. Serial No. 101,761.

Our invention relates to an improvement in dry kilns and this particular invention pertains to a kiln of so-called progressive t The fundamental object is to provide a kiln in which advantage is taken of the natural circulatory course'of the air currents, and in this connection to provide means calculated to accelerate this natural motion of the air through the kiln.

This particular invention includes a heating system, humidifying means, arranged to suit the requirements, means for reheating and re-conditioning the air on its return to the drying chamber, from which means it is discharged into the kiln at any desired prearranged point, in an upward direction through the drying chamber, together with auxiliary means for accelerating the natural passage and course OfclICllliltlOIl of the air.

More specifically speaking, this invention consists'in -a drying chamber with suitable heating means andme-ans for humidifying the air, in combination with air intakes andv return conduits extending inwardly from the intakes and discharging upwardly into the drying chamber, in a direction suited to the natural course of the air currents from what is termed the dry end of the kiln, in the direction of the green end where there is more moisture in the material being treated and a greater amount of humidity in the air, mechanical means being employed at the dry end to accelerate this natural course or cycle of air currents.

In the accompanying drawings:

Figure 1 isa vertical longitudinal section through an illustrative form of my invention, and

' Figure 2-is a horizontal section.

A represents the drying chamber of the kiln and the numerals 1 represent some approved formof roof ventilators.

A heating system 2 extends long1tud1- nally of the bottom of the kiln and preferably below the rails.3., Various forms of pipin for the heating system may be employs although it is desirable to have an excessive heat at the dry or. right-hand end of the kiln as! indicated by the three leads of pipes at that end. 7

Doors 4 are provided. at opposite ends and therails 3 usually slope-downwardly from the wet end toward the dry end of the kiln,

they being supported on pillars 5, or other suitable foundation.

An air intake 6 is located at some point in the bottom of the kiln at or near the greenend, preferably just inside the door. This is usually covered over by a screen 7 to exclude large particles.

A conduit 8 extends horizontally from the intake 6 toward the opposite end of the kiln, agreater or less distance, according to requirements. 'While the conduit illustrated is perhaps two-thirds the lengthof the kiln, obviously it might be much shorter or even longer.

The heated air within the kiln naturally rises from the heating system and moves toward the green end where there is less heat and more moisture, as indicated by the arrows. This air is sucked through the intake 6 and on beingre-heated and re-conditioned, issues from the open end iofthe conduit-and rises through the heating system into the drying room A above. Its passage through the conduit is usually facilitated and accelerated by some artificial means such as is illustrated by jets 9 and 10, of steam or compressed air or ventilating fans (not shown) might be employed When jets are employed they are usually located at some distance apart and the location within the conduit is, of course, subject to change so I to suit the conditions. These jets are supplied from a pipe 11 "which has a valve 12. for controlling the two or any, number of jets simultaneously and valves'l3 and 14 are provided as'a means for cutting out any one of. these jets, or if there should be a large number of them, several of them. The.

for humidizing and conditioning the air as it is drawn into the intake. The steam supply to this pipe 18 is controlled by a valve.

19 which may be operated by hand or mechanically controlled.

hand valve 22 controls the supply A jet 20 for compressed air or steam is located in the outer end of each of these conduits 16 for creating a suction or partial vacuum in the air intake 15 to cause the air from the extreme dry end of the kiln to flow downwardly into the intake, after whichit is discharged through the perforations 17 after being re-conditioned, upwardly into the kiln above as shown by the arrows at the right-hand end of the kiln in Figure 1. A pipe 21 supplies these nozzles and a for the nozzles 20. e The foregoing mechanism serves as an accelerator for the circulating air at the dry end of the kiln and after re-conditioning it keeps it moving upwardly through the material and. onward toward the greenend in the natural course of circulation;

Humidity spray pipes 23 may be employed wherever most needed. We have illustrated two ofthese only, One at the top of the gi'eenend andthe other at the bottom of the dry end. These may be arranged in any way to assist in giving a universal humidity condition and they. may be regulated by hand control or control regulators. Thus a. constant and substantially uniform agitation of air is in progress throughout the operation of the kiln and this in the natural course of movement of the air, with the result that we attain uniformity of temperatures and humidity throughout the entire'interior of the kiln, but at the same time with the ability to add to or subtract from,

and otherwise control, the heat, humidity and circulation by the proper manipulation of the various valves. In other words, we attain perfect control of all of these ele' ments or factors.

It will be observed that in the operation of this kiln no fresh air is admitted from the outside, the present invention being a means or system of circulation confined to the circulation and re-circulation and conditioning of air wholly inside of the kiln.

In the progressive action of this kiln, advantage is taken of existing natural conditions, and first among these it might be mentioned that the lumber or material being treated is progressively being denuded of its moisture content by the very natureof things. That is to say, the green lumber is placed in the wet end of the kiln, and the last preceding load is moved on into the QneXt zone or area in a slightly dry condition, and the one preceding it is moved forward in a still drier condition, as with the other loads ahead, as the completelycured load is removed at the dry end. Each load occupies a zone of its own, as it were. The air from the more highly heated or dry end, where the curing isapproaching completion or is completed, naturally flows in a direction opposite from the progressive movement of the various loadsof lumber or. material being treated, toward the denser or less highly heated green end of the kiln, and to facilitate this natural movement of the air, the heated air is accelerated or boosted in the direction of its natural course by the V discharge of heated and reconditioned air fromthe conduits at the bottom of the dry end. And, as fast as the air reaches the green end, it is sucked down and around the larger conduit and reheated and conditioned, and returned. Thus, due to the differential in moisture content at the two ends of, the

From the foregoing it'will be seen that we get a natural air turn-over in a progressiv-e kiln due to the difference in moisture" content at the opposite endsof the kiln, to-

gether with the heating system, thus pro viding a self-regiilatingmeans of control ing the humidity throughout the kiln as long asnioist steam is liberated at any one point. This natural air turn-over tends to give a constant point of precipitation which is the desideratum in any progressive operation.

This condition is facilitated by a gradient of heat between the two ends of the,

kiln. This gives a differential in density.

With these various conditions wedirect and control, re-condition, re-circulate, and. 'ac

celerate the movement of the air currentsin their natural cycles of movement through.

the kilns,thus attaining a high-degree of uniformity ofheat and humidity throughout, with the result that the curing opera tion is facilitated and the product treated is uniformly cured.

We claim:

1. A kiln of the character described' including a drying chamber, a heating system,

humidizers, air intakes at opposite ends, a. return conduit leading from one air intake and discharging Well into the interiorfof the kiln, a plurality'of air conduits extend ing inwardly from the intake at the opposite end of the kiln and discharging upwardly into the kiln, and means located within the several conduits for creating a suction of air from the kiln into the. air intakes, and for causing its discharge therefrom, into the kiln, and valve mechanism for regulating and controlling the passage of airthrough;

these conduits.

2. A kiln of the characterdescribed in cluding a. drying chamber, a heating system,

humidizers, air intakes at opposite ends, a return conduit leading from onea r intake and discharging well into theinterior ofthe kiln, a plurality of air conduits extending inwardly from the intake at the opposite end of the kiln and discharging upwardly into the kiln, means located within the several conduits for creating a suction of air from the kiln into the air intakes, and for causing its discharge therefrom, into the kiln, valve mechanism for regulating and controlling the passage of air through these conduits, and humidizing means located at the intake which supplies the return conduits at the dry end of the kiln.

3. A kiln of the character described including a drying chamber, air conditioning means for said drying chamber, and means for withdrawing air from the green end of the chamber and directing said air toward the dry end of the chamber, discharging the air in the region of the dry end for natural recirculation toward the green end in a direction opposite to the movement of the material being treated, and means for causing an auxiliary circulation of air at the dry end.

4. A kiln of thecharacter described ineluding a drying chamber, an air intake extending across the kiln at the green end thereof, and a return conduit leading from said air intake to the region of the dry end for Withdrawing air from the green end through the conduit and discharging the air into the dry end of the chamber for natural recirculation back through the kiln in a direction opposite to the. movement of the material therethrough.

5. A kiln of the character described including a drying chamber, means for conditioning air therein, air intakes approximately at the opposite ends of the kiln, a return conduit leading from one .air intake and discharging in the region of the dry end, and a relatively short conduit extending inwardly from the other air intake for creating an auxiliary circulation of air at the dry end. I

In testimony whereof We affix our signatures. I

FRANK CREIGHTON. WILLIAM E. GRAY;

Images