US1230282A - Drying apparatus. - Google Patents

Description

C. H. CURRI'ER.

DRYING APPARATUS, APPLICATION FILED SEPT. 15, 1916.

2 SHEETS-SHEET 2.

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DRYING APPARATUS.

To all whom z'tmay concern:

Be it known that I, CHARLEs H. CU'RBIER, a citizen of the United States, residing at Newark, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Drying Apparatus, of which the following is a specification.

My invention relates broadly to dryingovens or kilns, which are widely used for drying coats of varnish, stain or filler on.

. wood and metal, and for similar purposes,

' gree of moisture or humidity. It is also useand also relates to improvements in apparatus designed to supply such ovens or kilns with dustless air which is of the proper tem perature andwhich contains the proper deful for drying gluedveneers and stock.

For drying purposes and particularly in connection with oods which are coated with varnish, it is deslrable .and ractically essential to produce what may e called a perfeet drying day, in other words, air conditions which are proper both from the standpoint of the temperature of the air and of its humidity, as well as its freedom from dust. The drying of varnish, for instance, requires heat, moisture and a large supply of oxygen, since the operation is not purely a drying action, but involves also a chemical oxidation of certain of the ingredients of the varnish.

Consequently perfect drying-of the coat can-- not be obtained unless the operation is carried on in a current of air' which is warm enough to ralse the temperature of the varnish so as to accelerate the rate of evaporation of certain of its volatile content, and which is moist enough to prevent the varnish from case-hardening or surface-drying, since thevarnish should properly dry from the i '40 base outwardly to the surface. Furthermore,

there must be sufiicient oxygen supplied to oxidize the linseed oil and to react on certain of the other components of the varnish. It

, is also desirable that the current of air thus supplied not only have the characteristics just described, but also be freefrom dust which otherwise would'mar the finish of the varnish. Y

- In order to accomplish the perfect drying of such articles as have. been specified, it iscustomary to place them in specially constructed rooms, ovens or kilns-1n which the conditions of air supply may. be accurately controlled. At the same time, it is. necessary that conditions throughout the kiln be as uniform as possible in order to prevent air Specification of Letters latent. I Patented J 1111 19 1917, Application filed September 15, me. Serial No. 120,225. Y i

in one stratum having substantially different I properties from that 1n another stratum. My invention consequently relates both to the design 'ofthe kiln for attaining as nearly uniform conditions therein as may beffeasi- 'ble and also the construction and arrangement of the apparatus associated 'with the kiln for'supplyingito it the conditioned air to approximate the perfect drying day.

In the accompanying drawings, which form a part of this specification, "Figure *1 is a plan view of one'type of kiln'and its v associated apparatus. constructed in accord--- ance with my invention. Fig. 2 is a trans-- verse sectional view through the kiln. Fig;

3 is a view similar to Fig. 2 showing a slightly modified form of constructiom Fig. 4 is a plan viewon an enlarged scale'ofthe apparatus shown at the left of- Fig. '1', which suppliesthe air to the kiln. Fig. '5 is'a side i elevation of the device of Fig. 4,.and Fig. 6 is a longitudinal sectional view through a kiln having the modified form of duct 0on This isto provide ample airsupply for a plurality of vertical downwardly extending supply ducts 6 which terminate. at their lower. ends in openings 7, which are controlled by dampers 8. Along the ceilingat the opposite side of the room extends an outlet or vent duct 9, which is providedwith downwardly. extending'vent ducts 10, which I i are, similar to the ducts 6 and whose open.

ends 11 may be controlled by the'da mpers12. The outlet duct 9 is likewise graduated. or

stepped in size asshown in Fig. 1,.the p art 7 of largest dimension being near the center of v the kiln and 'adjacentto the vent pipe 13, 105.

which leads to the outer atmosphere.

I have found thatin order to obtain eflicient drying, it is highly desirable that a system of cross-ventilation beset up, such as that. produced by the construction shown in no Figs. 1 and 2, in which the supply or inlet ducts and the vent ducts are substantially similarly arranged transversely of the kiln.

This prevents any dead spaces and also insures a pure cross-ventilation without eddy currents which might act to prevent the uniform circulation of the heated air through the kiln. I also prefer to use a system in which the air enters under a slight pressure, for example, 600 feet per minute velocity, since it will then of its own accord displace the air already in the kiln and force it out of the vent ducts, at the same time preventing any outside air from entering the kiln through any accidental opening therein and thus overcoming the possibility of dust being brought into the kiln.

In Fig. 3, I have shown a modified form of construction in which the main supply duct 14: lies along one side of the kiln near the floor and is provided with a plurality of spaced apertures 15 opening toward the floor. Each of these apertures may be controlled by a suitable damper 16. I may also use a vent duct of somewhat similar construction in which the orifice 17 is adjacent to the floor, the duct 18 leading outward fromthe kiln and being controlled by a damper 19. Both ducts will, of course, be suitably graduated in size as before.

It will be appreciated that while theoretically, it may be desirable to position the inlet and outlet ducts in pairs directl opposite each other, this is in practice oftenimpossible owing to the occurrence of doors, columns, or other obstructions, and in fact, is not essential so long as an approximately symmetrical arrangement isprovided without dead spaces.

Figs. 4 and 5 illustrate on an enlarged scale the device which I prefer to use for supplying the air approximating the conditions of a perfect drying day. In the apparatus 20 is the fresh air intake through which atmospheric air gs drawn in by suction. The air first passes through the air washer and humidifier. 21. In this journey the air travels through a mist or spray formed by water forced through the nozzles 22. These nozzles are connected to a supply pipe 23, which is fed from any suitable source, as the centrifugal pump 24, which may be driven by means of the electric motor 25 through the belt 26. This pump preferably has its intake 27 connected-through a strainer 28 to a water well 29, which forms the bottom of the air washer and humidifier well is controlled by means of suitable heaters 29 fed from the steam pipe 30. After the air passes through the spray or mist in the washer and humidifier, it continues through the eliminators 31, which are merely angularly-disposed baffle plates, and then ,passes through the heating chamber 33,

where it may be heated to any desired de- 'gree by means of steam heaters supplied from the main 34, the steam leaving the The temperature of the water in this heaters through the return pipe 35. From the heater the air is drawn by suction into the intake 36 of a centrifugal fan 37, which may be driven in any suitable manner, as by being belted to the electric motor 38. This fan delivers the air under pressure through its outlet 39 into the main inlet or supply duct 3 already described.

As has been above pointed out, it is necessary to control three characteristics of the air; first, the dust content; second, its humidity or moisture content; and third, its temperature. All of these conditions are governed by the apparatus shown in Figs. at and 5. The dust is readily eliminated by the passage of the air through the mist or spray fromthe nozzles 22, this intermingling of the air with the spray mechanically washing the air, and all dust or dirt held in suspension in the air falling to the bottom of the tank 29. The process of governing the humidity of the air about to enter the kiln is somewhat more complicated and is accomplished by first bringing the air toa known point of humidity and then heating it to the required temperature. The most easily attained starting point is that of practically complete saturation; that is a condition of 100 per cent. humidity, and as the air passes through the mist or spray emanating from the nozzles 22, it automatically takes up sufficient moisture to saturate it completely at the temperature of the water forming the mist or spray. This temperature is easily controlled by governing the amount of steam admitted to the pipe 30 through the dia phragm valve 40, which in turn is controlled by a thermostatic device 41, preferably situated just back of the eliminators. The particular construction of the diaphragm valve and its thermostatic control forms no part of my present invention, since such valves and controlling means are well known in the art, and they will not be described here in detail. It is simply necessary to set the ther mostatic control 41 at the desired temperature. This control then acts on the diaphragm valve 40 either to admit steam to the pipe 30 or to shut it off, as the case may be, in order to maintain the desired temperature of the air passing through the eliminators and striking the control. By this means, I produce a current of air passing through the eliminators which is in a condition of nearly complete saturation or 100 per cent. humidity at the temperature for which the thermostat 4:1 is set. The only function of the eliminators is to take from the air any particles of moisture which may be carried along in the form of mist and not as true water vapor. As the air passes through the eventually drips into the tank 29. The loss of water from the tank 29 due to the moisture taken up by the air is made good from time to time from any suitable outside supply.

Now, if the air upon passing through the ballle plates is completely saturated with moisture and is, for example, at a temperature of 87, it will contain 13.12 grains of water vapor per cubic foot. Suppose the air in the kiln is desired to be at a temperature of 112 with a relative humidity of 47 per cent; this humidity at a 112 temperature represents 13.12 grains of water vapor per cubic foot, and consequently it is only necessary to supply sufficient steam through the main 31 to the heaters 33 to raise the temperature of the air to 112,

since it already contains the 13.12 grains of water vapor per cubic foot required to give the 17 per cent. humidity at 112. In other words, merely by adjusting the temperature of the water sprayed through the nozzles 22, so as to obtain saturated air containing the desired number of grains of water vapor, and then subsequently raising the temperature of this saturated air in the heater 33, I may obtain any desired temperature of the air entering the kiln and likewise any desired humidity. The inlet of steam to the main 3t and consequently the heater 33 is.

controlled by a diaphragm valve 42, which may be similar in its construction to the valve 40 and this valve is in turn governed by a thermostatic control 43 preferably located on the exhaust or vent side of the kiln. It will be appreciated that in the example given above, for instance, the air passing through the heater 33 will actually be raised to a temperature much greater than 112, say 152, in order to compensate for radiation losses in the ducts and kiln.

\Vhile I have illustrated and described only certain preferred embodiments of my invention, I realize that it is susceptible of wide adaptation and I do not desire to be limitedto the precise construction shown and described.

lIaving thus described my invention, I claim:

1. In apparatus of the class described, a kiln, inlet and outlet air ducts therefor located on opposite sides thereof, both sets of ducts opening downwardly toward the floor of the kiln, and means for supplying conditioned air under pressure to the inlet ducts.

2. In apparatus of the class described, a kiln and inlet and outlet air ducts therefor located on opposite sides thereof and arranged transversely of the kiln, said ducts pplening downwardly toward the floor of the 3. In apparatus of the class described, a kiln, inlet and outlet air ducts therefor located on opposite sides thereof, said ducts opening downwardly toward the floor of the kiln and within a short distance the eof, and means for supplying conditioned air under pressure to the inlet ducts.

4. In apparatus of the class described, a kiln and means for producing cross-ventilation thereof, including a plurality of air inlets and a plurality of air outlets substantially symmetrically arranged transversely of the kiln, said inlet ducts opening downwardly.

5. In apparatus of the class described, a kiln and means for producing cross-ventilation thereof, including a plurality ofair inletsand a plurality of air outlets disposed at intervals along opposite sides of the kiln and near the floor, said inlets and outlets being substantially symmetrically arranged transversely of the kiln, and means for supplying air under pressure to the air inlets.

CHARLES H. CURRIER.

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