US1004468A - Method of drying air. - Google Patents

Description

I. H. REYNOLDS & F. E. NORTON.

METHOD OF DRYING AIR. APPLIOATION FILED DBO. 4, 1909.

1,004,468. Patented Sept. 26, 1911'.

2 SHEETS-SHEET 1 C l/ Hail: 0726a I. H. REYNOLDS & F. E. NORTON. METHOD OF DRYING AIR.

APPLICATION FILED 11110.4, 1009.

1,004,468. Patented Sept.126, 1911.

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IRVING H. REYNOLDS AND FRED E. NORTON, OF YOUNGSTOWN, OHIO.

METHOD OF DRYING AIR.

Specification of Letters Patent.

Patented Sept. 26, 1911.

Original applicationf filed January 21, 1907, Serial No. 353,358. Divided and this application filed December 4, 1909.- Serial No. 531,425.

. being especially applicable for supplying air in large quantities to metallurgical furnaces, or the like, wherein air free from moisture 18 required to properly carryout the process bein undertaken. The method is such that the ormation of ice or snow in the apparatus is all but prevented, doing away with the use of or necessity for snow or ice boxes, which are employed in many systems and which, of course, require constant attention to insure a proper supply of dry air.

For use 1n last furnaces, it has been found desirable to reduce the moisture in the air supplied thereto to a low and constant amount,say, one to two grains per cubic foot of free air. The present method enables us to supply air to such furnaces at a predetermined humidity with absolute uniformity, and this without the use of any extraordinary apparatus or materials, such as am monia. compressors and brine cooling mediums.

The invention -may be best understood u on reference to the annexed drawings, wherein? Figure 1 is-a diagrammatic view of one v arrangement of an apparatus wherein the method may be carried-out; and Fig.2 a

'similar view,'.showing a slightly modified form of apparatus.

The mai object of the invention is to provide a process by which the greater part of the moisture .will be extracted from the compressed 'air by the .use of watenat natural temperatures, as for instance, 1'1V6I" water, and to thereafter employ such air in the production of useful work; for example, permitting it toexpand and causing such expansion to-act within a cylinder to assist in actuatin a compressor, or doing other useful wor whereby a further quantity of ",moisture will be extracted from the air.

f" A further object of the invention is to employ 8.,PIOC8SS or method in which the air passes through the apparatus in a direction counter to the flow of the fluid used to cool forms of apparatus in which-the method may be carried out, but it is to be understood that the construction and arrangement essential features are retained.

Referring first to the apparatus shown in Fig. 1: 1 represents the motor cylinder of an air-compressing machine; 2 the compressor cylinder, and 3 the expanding cylinder. These cylinders are shown as all coninected to a common crankshaft 8, having three cranks 4, 5, 6, the shaft being sup-v ported or resting in suitablebearings 7, 7",

'7", 7, as is usual in machines of this class.

The air enters the compressor cylinder at 9 and after being compressed to a suitable degree is conveyed by a pipe 10 to a compound drier, comprising a lower drying chamber 24 and an upper drying chamber '24, the upper portion of the, former being connected to the lower portion of the latter by a. pipe 11. The air leaving the compressor through the pipe 10 passes around and about tubes 19 in the lower drying chamber 24, bafile-v plates 22 therein causin it to pass back and forth from one side to the other of the drier before it enters the pipe 11. A baffle-plate 22, located in the upper drying chamber 24", causes the air to pass around the tubes 20 of said upper drying chamber before it enters pipe 12. .The air is under constant compression during its passage through the ' driers 24 and 24. p

The pipe 12 conveys the air to the cylinder 3, in which it is expanded to a suitable of theparts may be modified so long as the p pressure or degree, and the work done by it 1S transmitted, through the piston mounted in the cylinder, to the crank 6 and shaft 8,

and as a consequence to crank 5 and thence to cylinder 2, where the greater part of the force is usefully exerted to. aid in compressing air entering at 9 and leaving through P e 'Theair leaving the cylinder 3 will be considerably cooled, and passes by pipe 13 to the cooler 26 and around tubes 21 mounted therein, the bathe-plates 23 in saidcooler 26 causing the air to take a circuitous route or passage therethrough. The airis in a constantly compressed state during its passage through the cooler 26, though the pressure is lower than in the driers 24: and 24c.

In theform of'cooler shown, water supplied from any suitable source enters by pipe 15 and flows through the tubes 21 in a direction from 27 to 27", While the air outside of the tubes circulates in the opposite direction, or from the lower to the upper portion of the cooler. As a consequence, the

temperature of the water leaving the cooler at the lower portion thereof by the pipe .16

may be reduced to within a fewdegrees of thetemperature of the air at the lower portion of the cooler 26, and in practice this may be as near the freezing-point as is practicable to avoid freezing of the water.

The temperature of-the water in the pipe 16 as it passes from the lower end of the cooler. 26 to the upper portion of the drier 24?, or the chamber 25 in the'upper part thereof, may be made to approximate as nearly as desired the temperature of the air in the lower portion of the cooler 26 by regulating thejquantity of water passing into said cooler throu h the pipe 15, which regulation may be efl ected in any desired manner. As before noted, .the water passes from the pipe16 into t-he'chamber 25. It then flowsth rough the tubes 20 and into a space 25", thence through tubes '19 to a space 25, from which it is discharged by a pipe 18 to any convenient point of waste. Additional water maybe introduced into the space 25 through a pipe 17.

, The purpose of the invention may be best illustrated by a concrete example. 30,000

cubic feet of atmospheric air per minute,

saturated at 82 F. are required to be compressed to 15 lbs. gage-pressure and delivered with a moisture-content of less than one grain per cubic foot of original volume. 'At atmospheric pressure'of 14.7 lbs. per square inch and 82 F. the air will contain 12.6 grains of moisture per cubic foot, or 30,000 cubic feet will contain 54 lbs. of moisture. In order to obtain the proper cooling effect by expansion in cylinder 3, the air should be compressed ire-cylinder 2 to 42 lbs. absolute pressure per square inch, or, say, 27 lbs. age-pressure. The work of compression is 2280 H. P. and the air will leave the cylinder 2 at a temperature of 270 F. The

92 F. The cooling water passing through the pipe 16 may be reduced to 42 F. without danger of freezing, and consequently the air in pipe 12 may conveniently be reduced to 52 F. On expanding in cylinder 3 the pressure is reduced to 15 lbs. per square inch gage-pressure, and the; temperature falls to 6 F. The air entering the cooler through pipe 13 may thus be reduced to 6 F. or 26 below freezing, and may be heated in passing around the tubes 21 to 72 F., at-which temperature it' is available for any use. In passing through the cooler 26 it, of course, absorbs the heat from thewater flowing through the tubes therein, and thus reduces the temperature of 'the water, by the time the latter reaches the lower end of the cooler 26, to approximately 42F.

The moisture-contents of the air at the various points will be as follows: Entering pipe 9, 12.6 grains per cubic foot free air in pipe 11 6.2 grains; in pipe 12 1.4 grains; in pipe 13 the moisture will be reduced to one-fourth of one grain per cubic foot of free air. The air becomes heated in passing about tubes 21, but being dry no moisture is gained or lost. The work done in' cylinder 3 is equal to 530 H. P., which taken from 2280 H. P. required for compression in cylinder 2, leaves but 17 50H. P. to be exerted by the motor cylinder 1. If the air had been directly compressed at atmospheric pressure and 82 F. to 15 lbs. gage-pressure, the

horse-power would have been 1530 H. 1

so that by the expenditure of 220 H. P. the air may be reduced to almost absolute dryness.

As above noted, one of the main RdVRH' tages of the present invention resides in the fact that three sets of cooling surfaces,

namely, the tubes or pipes 21, 20 and 19 (in the construction shown), are arranged in such manner that the air circulates around them in series in the order of'19, 20, 21, while the cooling water'passes in. the order of 21, 20', 19, with an additional cooling water. supply between 19 and 20 if so desired. This arrangement of the apparatus results in the consumption of a minimum amount of power. The cooling surfaces may be small and the cost thereof low, since even in the extreme case noted above the surfaces need not be greater than those commonly utilized for air and gas coolers. v

With the apparatus herein set forth nearly all ofthe moisture is removed from the air before it enters the expansion cylinder 3, thus 'enliibling us to employ a temperature lower t an has heretofore been possible on account of the difficulty experienced from the clogging of the exhaust ports and passages leading from the expansion cylinder. The apparatus also provides for the complete removal of the moisture in the formnf tion of ice or snow in any portion of the apparatus which, as will be readily appreciated, would clog the same.

water, without the possibility of the forma It will-"be noted that the tubes 20 are maintained at a low temperature by the cool waterfiowing through them, but this never reaches the freezing-point. The tubes 21. in the cooler 26 would similarly be above freezing-point, and any snow tending to collect upon them would be melted and drawn away vthrough suitable drains, such as32, 33, 34

and 35. In a similar manner, the moisture would be removed from the tubes 19 and 20 by the drains 30 and 31. r

Fig. 1 shows the arrangement of the compound drier 24, 24}, but it is evident that the apparatus is subject to modification, and in Fig. 2 is shown a. system in which separate driers 24? and 24 are employed, so far as the cooling medium which passes through the same is concerned. In said figure it will be noted that pipe 16, which passes from the lower portion of the cooler 26* discharges into the upper portion of the drier 21. The water passes from the lower portion of said drier into a pipe 36 which leads to a pumpchambcr 37. Said chamber discharges through a pipe 38 into the upper portion 39 of the cooler 26. In this way the water is passed continuously through this portion of the system, while the initial drier 24 is sup plied through a separate pipe 40 from any suitable source. By this arrangement the water passing through the cooler 2.6 and drier 2+1 is used over and over again. The temperature at the lower portion of the cooler 26 may be still further reduced if a strong solution of brine is-=used instead of pure water. A In the drawings one form of air-com pressing mechanism is shown, but it is evident that any of the common forum of such machines may be employed, and the invention is, therefore, not to be limited to any particular type of apparatus. It is also evident that instead of using tubes to convey the cooling medium, the latter may be passed .around the tubes and the air circulate through the same. In fact, the cooling chambers may be constructed in any suitable way known to the art, or in other words, the drawings are to be considered as merely diagrammatic and illustrative of the principles involved in the invention.

\Vhile throughout the specification the members 24 and 24 have been referred to as driers, and 26 as a cooler, it is to be noted that the former, to-wit, 24, 24, actboth as driers and. coolers. The member 26, however, acts only as a cooler and will be thus referred to in the claims.

One of the prime objects of our process is that the heat of compression is mainly removed by a natural water supply and the chillin of the cooling liquid is satisfactorily secure by the expanded air. We have found that the efliclency of the process depends upon the removal of as much of. the

heat as possible, while the 'gas is under high pressure, and through the agency of a natural water supply. It is necessary to remove the latent heat of vaporization of the steam mixed with air, and this is best accomplished by cooling under high pressure and by water at natural temperatures. A The desired dryness may then be realized by cooling the partially cooled air.

It is important that the process be carried out in the manner described, so as to present, in the drier, the warmest air, or that which has just been compressed, to :the warmest water, and the cooler air, or that which 'is partially expanded, to the coldest water,

or that which is flowing into the upper portion of the tdrier. It is also necessary that the air be as highly chilled as possible before expansion, and owing to the removal. of much of the moisture this can be safely and efliciently done. i g

No claim is made herein to the apparatus set forth, as that formsthe subject-matter of our copending application, Serial No. 353,358, filed January 21, 1907, (now atent No. 946,069, dated January 11, 1910 the present case being a division thereof.

Having thus described our invention, what we claim is: y

1. The method of extracting moisture from air, which consists in compressing the air; bringing the same while in its compressed state into contact with a surface the temperature of which is materially lower than that-of the air and thereby causing the contained moisture to condense; permitting the dried air. to expand and by reason of its expansion to lower its temperature; and finally employing the cold air thus obtained to lower the temperature of the medium employed to cool the aforesaid cooling surface.

2. The method of extracting moisture from air, which consists in initially compressing the same; bringing the air while thus compressed into contact with a cold surface; thereafter permitting the air to expand and thereby to become cold; and finally bringing the cold air into contact with the conduit through which the cooling medium, employed to lower the temperature of the cold surface, is passed.

3. The method of drying air, which consists in initially compressing the same; bringing the warm, moisture-laden air while thuscompressed into contact with a condensing surface; passing the air from such surface toa motor and permittingit to expand therein and to actuate the same, the air being thereby materially reduced in temperature; and finally discharging the air thus cooled into contact with the con- 4. The method of drying gaseous fluids,

- or. (sam consisting in compressing the fluid to a a higher pressure than that of utilization utilization in such manner as to artificially cool the circulating liquid.

5. The method of drying gaseous fluids, which consists in compressing the fluid to a cooling. and drying it while so compressed by a natural. water supply; passing the air so dried into contact with a surface cooled by a liquid circulating in a counter current to the same ;v expanding and chilling the fluid thus treated; and carrying the expandedand chilled fluid into contact with a surface with the opposite side of which the circulating liquid is in contact, said liquid flowing in a direction the opposite of that in which the fluid passes whereby the highly compressed and heated air will come into contact with the surface which is cooled by the coolest liquid and the warmest-por: tion of the liquid will come into contact with the surface against which the coolest air is discharged.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses. I IRVING H. REYNOLDS.

FRED E. NORTON.

Witnesses:

H. J. STAMBAUGH, k REGINALD P. DRYER.

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