Патент USA US2403800код для вставки
July 9, 1943- ‘ ‘n ‘ c. N. HoYLER I 2,403,300 - ‘METHQD OF‘AND APPARATUS FOR DRYING‘? MOISTURE ‘IZJIADEN ARTICLES I w Filed Deaf-31, 1941‘ s She'ets-Sheét 1 arm/6 CMT/A/UEO I o ,5 2'0 504M060 wavy/MIN?» I rm: 0v Mill/7E5 ‘3mm. ' July 9, 1946. Q N, HQYLER I 2,403,800 METHOD OF AND APPARATUS FOR DRYING MOISTURE LADEN ARTICLES Filed Dec. 51, 1941 3 Sheets-Sheet 2 JL .5 ~, / 1/ 2/ I g 1 , = r g : l 2a - ‘a I 4,4 . J 5 a ’-’ .’ a 11W 37 a Z f’ 49 I I 7 ,/ 1W 37‘ 45 Al/YTPlM/T 0 I I I l0 20 a0 I 10 ?/Vf/"f/IVUTE I I w 60 - 3nvento; July 9, 1946. c_ N, HOYLER 2,403,800 METHOD OF AND APPARATUS FOR DRYING MOISTURE LADEN ARTICLES Filed Dec. 31, 1941 I ' ' 1 3 Sheets-Sheet 3 ' ' 3mientoi: Cyril N'HOyZer - Patented July 9, 1946 2,403,800 UNITED STATES PATENT OFFICE 2,403,800 METHOD OF AND APPARATUS FOR DRYING MOISTURE LADEN ARTICLES Cyril N. Hoyler, Audubon, N. J., assignor to Radio Corporation of America, a corporation of Dela ware ’ ‘Application December 31, 1941, Serial No. 425,170 18 Claims. (Cl. 34-1‘) 1 2 , identified copending application of Bierwirth. According to Bierwirth’s method, the rayon is placed in a‘ radio frequency fieldand advantage This invention relates to a method of and ap paratus for expelling moisture irom moisture-la den articles and has special reference to the dry is taken of the impedance of the moist cakes to radio frequency energy to effect heating and dry ing of water-laden rayon “cakes,” the present in vention being an improvement upon that dis closed and claimed in thecopending application ing thereof. The heating takes place in a vac uum so that the moisture-can be expelled at a of Rudolph A, Bierwirth, Serial No. 407,619, ?led August 20, 1941, now Patent No. 2,325,652, and assigned to Radio Corporation of America. In the manufacture of rayon, after the thread has been formed, it is wound up into what is known as “cakes” and placed in cloth containers, after which the cakes are thoroughly washed in temperature far below 140° F. Moreover, the cakes are heated uniformly throughout and therefore a thread of higher quality is obtained. Added to these is the very important advantage that the cakes can be dried by the Blerwirth method in about an hour, as compared with 60 to 100 hours required by the previously practiced water to remove the sulphuric acid or other chem ical employed in coagulating the viscose mate 15 method. Now it has been found that, in vacuum drying rial. One of the problems encountered in the of the rayon cakes by radio frequency energy as manufacture of rayon is the drying of the yarn suggested by Bierwirth, the power demands on or thread after it has been through a washing the oscillation generator change considerably. or dyeing process, the rayon absorbing about twice its own weight of water after it is washed. 20 For example, in one arrangement wherein one cake was placed between a pair of electrodes in an evacuated chamber, an input of considerably ations can be carried out. over 1200 watts was required during the first In accordance with the prior art practice, it This water must be removed before further oper thirty minutes or so, while during the last thirty has been customary to pass the cakes through large drying ovens in which they are subjectedto 25 minutes of drying the input dropped to rather low values. Thus, a generator is required which is a stream of heated, dry air. This method pre capable of delivering much more power than is sents several dif?culties. For example, the time actually used during the major portion of the required to dry a cake ranges from about 60 to drying cycle. . 100 hours, and with ovens having a capacity of The primary object of my present invention is even as great as 1000 cakes per hour, it is obvious 30 to provide an improved method of and appara that a great many ovens are required -to handle tus for dryinglmoisture-laden articles, such as the rayon output, which is in the neighborhood rayon cakes, employing the teachings of Bier of over 20,000 lbs. (each dry cake weighing a pound) per hour.‘ Another difficulty which is wirth but utilizing the output of the radio fre quency generator much more ef?ciently, encountered is that considerable care must be ex ercised to prevent the rayon from reaching a More particularly, it is an object of my present temperature in excess of 140° F. since, above that invention to provide an improved method and temperature, the qualities of the thread are im apparatus as aforesaid in which the drying will paired and further manufacturing We sses can- ' take place in a plurality of stages‘ and wherein not be carried out successfully. Still another 40 new or fresh, moisture-laden cakes may be loaded difliculty which is encountered resides in the fact into the apparatus while at the same‘ time un that not only do the outside layers of the cakes loading the dried cakes, thereby making the proc dry ?rst with some attendant shrinking and con sequent tensioning of the threads at the outer layers, but the inner layers of the thread fre quently buckle up and wrinkle as a result of the ess a continuous one. ‘ Another object of my present invention is to '. provide an improved method of and apparatus for drying moisture-laden articles as above set pressure exerted by the tense, outer thread layers, and an increased possibility of tangling of the thread results. Furthermore, in each strand of forth in which the drying may be effected rap idly and in great quantities. In accordance with my present invention, and thread, a skin shrinkage occurs by reason of the 50 in order to provide more uniform loading to the outer surface thereof drying before the, inner portion thereof dries with resultant nonuniform appearance in the strand. The foregoing and other similar di?lculties are overcome by the method disclosed in the above 55 oscillator, I provide an arrangement which in cludes a plurality of operating stations at least one of which is a loading and unloading station, a second of which is an evacuating station, and one or more other ones of which ,are drying sta A 2,408,800 3 tions. These stations are arranged in endless fashion and the cakes loaded at the loading sta tion are carried around through the various sta tions and eventually returned to the first station for unloading the dried cake and loading a new. moisture-laden cake. Suitable means are pro vided for evacuating. at the evacuating stations, the chambers in which the ‘cakes have been de— posited and for thereafter maintaining the vac uum at the successive drying stations.’ As each cake becomes drier, its impedance in creases and it becomes more difficult to get power into the cake. This is equivalent to saying that 4 vacuum pump (not shown) coupled to the charm her through a conduit i3. A cooling coil i5 "within the enclosure I may be connected to a suitable source of cooling ?uid for condensing the mois ture which is expelled from the cakes, the con ~ densed moisture being "withdrawn in any suitable manner, as through the vacuum line ii. The primary electrodes 5 and ‘I are preferably constituted by circular plates, the lower electrode 1 being supported on an insulator i‘l. One or more rayon cakes i8 may be placed between the electrodes 5 and ‘l and a high frequency electric field applied thereto by the oscillator. A pair of the voltage across each cake must be increased secondary electrodes, such as the guard rings II as the moisture is expelled therefrom. For this 15 and 23, are preferably arranged around the pri purpose, I arrange the drying stations so that mary electrodes 5 and 1 external to the container each of the cakes therein constitutes an imped i and are connected in shunt relation with ‘the ance element in one of a plurality of parallel primary electrodes, the secondary electrodes serv related lad circuits which are connected in series ing to help make the field through the cake or with the oscillator, each of the load circuits also 20 cakes i9, as the case may be, more uniform by including a capacitor and each of the capacitors confining the end effects between the primary having a different value such that the appropriate electrodes ii and ‘I to a region well outside of the voltage is applied to each of the cakes at the re cake IS, with a consequent improvement in the spective drying stations. By introducing, at in uniformity of drying. , tervals, a fresh cake of maximum moisture con~ 25 After the vacuum in the enclosure i has reached tent to the load while a dried cake is being re a value of about 28 or 29 inches of mercury, the moved. it is obvious that, as the input require ments to one cake drop, another cake demanding high input is added to the oscillator load. Thus, _ output of the oscillator is connected across the primary electrodes ii and ‘I through the series ca pacitor ii. At a vacuum of about 29 inches of the variation in load on the oscillator can be 30 mercury, the boiling point of water is in the maintained within relatively narrow, predeter neighborhood of 80° F. During the early stages mined limits, and the output thereof used most of drying, the cake i9 will accept considerable ei'liciently. power. As the cake I! becomes drier, its imped The novel features that I consider characteristic ance increases and it becomes more difficult to of my invention are set forth with particularity get power into it. Thus, it is necessary to in in the appended claims. The invention itself, crease the voltage across the cake. This may be however, both as to its organization and method done by tuning the capacitor II as frequently as of operation, together with additional objects and may be found necessary, current through the load advantages thereof, will best be understood from being maintained at a suitable level. , the following description of several embodiments Referring, now, to Figure 3, the curve of which thereof, when read in connection with the accom represents the average of the power input to the panying drawings, in which oscillator taken at various times during the dry Figure 1 is a diagrammatic view of an improved ing process of several individual cakes, it will be arrangement in accordance with one form of my noted that the total energy used wec approxi 45 mately 1.2 kilowatt hours. This includes plate present invention, Figure 2 is a central sectional view of one of grid and other oscillator losses. The curve also the drying chambers formed according to my shows that during the ?rst thirty minutes or so present invention, of drying, the input was considerably above 1200 Figure 3 is a curve showing the oscillator input watts, but during the last thirty minutes of drying 50 for drying a single rayon cake, the input dropped to rather low values. If, now. Figure 4 is a set of curves showing the oscillator fresh cakes could be introduced in the load input requirements per cake for a number of such at the same time that dried cakes were removed cakes, and the total input to the oscillator when at various intervals, so that, as the input require a fresh cake is added at suitably spaced intervals, ments to one cake dropped, another cake de Figure 5 is a central sectional view of a mod 55 manding high input would be added to the oscil i?ed form of drying chamber. lator load, the latter would be kept much more Figure 6 is a fragmentary, sectional view of one constant. The arrangement shown in Figure l form of apparatus which may be employed for is one way of accomplishing this result. maintaining a vacuum in the drying chambers In the system shown in Figure 1, there is pro and for supplying cooling fluid to the condenser 60 vided a rotatable platform or turntable 25 adapted coils therein, and , Figure 7 is a somewhat enlarged, sectional view taken on the plane of the line VII-VII of Fig ure 6. Referring more particularly to the drawings, wherein similar reference characters designate corresponding parts throughout, and‘ more par ticularly, first, to Figure 2, I have shown a suit able enclosure I of dielectric material supported on a base or platform 3 and providing a chamber within which are a pair of spaced, primary elec trodes 5 and 1 connected to the tuned circuit 9 of a suitable oscillator through a variable capacitor i i in series with the tuned circuit 9. The interior of the enclosure i may be evacuated by a. suitable to be rotated by any suitable means, such as a motor 21, in a manner such that any point on the turntable will successively pass a plurality of sta tions I to VI, inclusive, arranged in an endless path. At each of the stations may be located an enclosure i and associated parts, as described above in connection with Figure 2. Let it be assumed that station I represents the loading and unloading station from which a fresh, moisture laden cake is started on its path in the drying cycle, and to which it is subsequently returned when dry, stations II and III constitute evacuat ing stations at which the respective enclosures or chambers l are evacuated, and stations IV, V and VI constitute successive drying stations at which 5 2,403,800 the drying operations take place, in turn. The wet cakes at stations IV, V and VI constitute impedance elements connected in series with their respectively associated capacitors Ila, Nb and I I0, these three series circuits constituting chamber I may be evacuated in a manner shortly to be set forth. The pipes I2 and I4 extend above the closure I 8, as can be seen from Figure 6, and the pipe load circuits for the oscillator and being ar oI.’ closely spaced ports I 2a extending' circum ranged in parallel relation to each other, although each is serially connected to the tuned circuit 9 of the oscillator. In the form of the invention under consideration, each 01' the enclosures I may have united therewith one plate or electrode I2 is formed near its upper end with a plurality i'erentially around it. A sleeve valve 26 which is formed with the same number of internally threaded bosses 28 as there are bosses 24 surrounds the ports I2a and is rotatably mounted on the pipe I2. Each of the bosses 28 is connected to the inlet of a separate one of the condenser coils I5 by a coupling tube 20, the outlet of each coil I5 A1 to Avr, inclusive, of the capacitor H, the plates Ar-Avr moving in unison with their respectively associated enclosures I. The capacitor II may, in being brought outto the top 01' the pipe I4 by a each case, be completed by a cooperating elec 15 tube 22. ‘-trode Brv, Bv, Bvr in each or the load circuits ‘Assuming that one ormore wet cakes I! have 28a, 29b and 290, respectively,'the electrodes BIV, been loaded into one of the chambers I at the By, Bv: being stationary. As the turntable 25 is loading station I, then, as the platform or tum rotated step-by-step at suitable intervals, it is table 25 rotates in the direction of the arrow in .obvious that each chamber I, after being suit 20 Figure 1, the sleeve valves" and 26 will rotate ably‘ evacuated at stations II and III, will ?rst with it in the same direction and the newly loaded reach station IV at which its electrode A will co chamber will soon reach a position where its con operate with the electrode Brv o1’ capacitor I Ia duit I3 will be in communication with the vacuum to apply a predetermined voltage to the cake or line III through the port I Ila. Evacuation'oi' the cakes contained therein. Subsequently, when the 25 air in the chamber will therefore begin and will particular chamber under consideration is moved continue past the stations II and III until the to station V, its electrode A will cooperate with end Y 01' the port Ina will have been reached. the capacitor plate Bv and a higher voltage will At about this time, the condenser plate asso be applied to the cake or cakes therein. Finally, ciated with the particular chamber under con when the same chamber is moved to station VI, 30 sideration (for example, the electrode A!) will 'I ~ its capacitorelectrode A will cooperate with the have come into cooperative relation with the con electrode BVI to cause a still greater voltage to be denser electrode Biv whereby the wet cakes will applied to the cake. Since, however, a fresh become coupled to the oscillator and drying will cake is introduced to station IV from station III begin. Meanwhile, since the condenser coil I5 each time the turntable 25 is advanced one step 35 is coupled to the water inlet pipe I2 through the and the cake or cakes previously at station IV ports I2a. cooling water will flow continuously are advanced to station V, and so on, it is appar therethrough and the water vapor driven out of ent that the load on the oscillator will be main the cakes being dried will be condensed to liquid tained well within certain predetermined limits form and will collect at the bottom of the cham which have been found expedient. 420 ber. As the turntable continues to rotate, the For producing and maintaining a suitable port IUb is eventually reached. This connects the vacuum in each of the chambers I and for supply- - ing cooling fluid to the several coils I5 as the plat form 25 is rotated to carry the several chambers chamber to the vacuum line again for a short pe riod to withdraw the water which has been con densed in the chamber, and this step is repeated 45 around the endless path. a system such as shown at the ports I00 and Illd. Shortly after the cham in Figures 6 and 7 may be employed. This may ber being considered has passed the port IUd, its consist of three concentric, stationary pipes l0. conduit I3 is brought into communication with I2 and ll of which the pipes Ill and I2 are closed the opening or port We and the air inlet pipe 20. at their upper ends by ?uid-tight closures I6 and Air from the atmosphere then rushes into thev I8, respectively, and the pipe I4 is open at its 60 chamber to break the vacuum therein just before upper end. The pipe III is connected to any suit the station I is reached. When the latter station able vacuum pump and is formed, near its upper is reached, the dried cakes are removed and are end, with a plurality of ports IOa, I01), I Do and replaced by wet cakes, and the above described I cycle is repeated. I?d. The port Illa is preferably elongated and may extend from a point X between the stations Instead of rotating the turntable 25 in a coun I and II to a point Y shortly in advance of the terclockwise direction, as shown by the appended arrow in Figure l, the same effect may be pro station IV. The port I?b may be relatively short duced by making the platform 25 stationary and and is located between the stations IV and V. Similarly, the ports IDc and Illd are short and 00 rotating the capacitor electrodes BIV, Bv, and Bvr as a unit in a clockwise direction. This arrange~ are located, respectively, between the stations ment may be preferable wheresuitable couplings V and VI and between the stations VI and I. cannot be made at the various stations (1) to Between the port "id and the station I, the pipe effect and maintain the desired vacuum in each‘ I0 is formed with an opening We in which a tube or pipe 20 is secured with a ?uid-tight connection. 65 of the chambers, and (2) to effect circulation of the water or other cooling medium through the the pipe 20 being brought out to the atmosphere condenser coils I5. In a system wherein the con in any suitable manner. denser plates BIV, Bv and Bvi are rotated, it is ob~ Surrounding the ports IUa to I02 and rotatable vious that each of the stations will become, succes on the pipe I0 is a sleeve valve 22 having a plu rality of internally threaded bosses 24 thereon 70 sively, ?rst a loading and unloading station, then the ?rst evacuating station, then the second evac corresponding in number to the number of sta uating station, and then each of the successive tions I to VI and spaced circumferentially from drying stations in turn, before again becoming a each other on the same angles as are the several loading and unloading station. However, the stations I to VI. Each conduit I3 is connected to overall effect is the same in either case. a separate one of the bosses 24 whereby each 75 The curves C of Figure 4 show the loading re quirements of each individual cake for a plurality of cakes (assuming only one cake is placed in each of the chambers i at one time). It will be noted that each of the individual curves is similar to the curve shown in Figure 3. It will also be noted to cooperate with a separate one of said stations during a predetermined drying interval, and means for bringing each of said elements succes sively into cooperative relation with each of said stations for successive drying intervals. 3. In apparatus for drying moisture-laden arti cles, the combination of a plurality of enclosures The curve D of Figure 4 shows the loading re constituting a plurality of drying chambers each quirements in a system such as that illustrated in adapted to receive at least one article to be Figure l on the basis of a new cake of maximum 10 dried, means for maintaining a vacuum in each moisture content added every twenty minutes. of said chambers, means for simultaneously sup From the curve D, it will be noted that the ratio plying heating energy in at least certain of said of maximum to minimum oscillator input is ap chambers for drying the articles therein, a plu proximately 6 to 5. It follows, therefore, that with rality of control elements for controlling the en a system such as that shown in Figure 1, the oscil 15 ergy supplied to said stations by said second lator may be employed much more emciently than named means, said elements being each adapted when a single cake is dried at one time, and at to cooperate with a separate one of said cham the same time the output of dried cakes can be bers during a predetermined drying interval, and very greatly increased. 0f course, any number means for successively bringing each of said ele of‘ evacuating and drying stations may be em 20 ments into cooperative relation with each of said ployed, the number shown in Figure 1 being used chambers for successive drying intervals. merely for the purpose of illustration. 4. In apparatus for drying moisture-laden arti In Figure 5. I have shown a somewhat different cles and including a loading station, an evacuat form of drying chamber which may be used on ing station and a drying station, the combina the turntable 25 instead of the One shown in Fig 25 tion of means providing a closed chamber adapt ure 2. In the form shown in Figure 5, the enclo~ ed to receive at least one of said articles at said sure may be constituted by a metal base 3i and loading station, means for successively advanc a metal cover 33 fitted together with a cylindrical ing the loaded chamber to said evacuating and glass drum or spacer 35. Two or more gaskets drying stations, means for creating a vacuum I1 may be employed for providing airtight con 30 in said chamber at said evacuating station and nections between the plates 3| and 33 on the one for maintaining the vacuum in said chamber hand, and the drum or cylinder 35 on the other. while said chamber is subsequently at said dry The advantages oifered by this form of chamber ing station, and means for supplying heating en are (1) that a relatively small volume of air would ergy to said chamber at said drying station for have to be evacuated, (2) that each cake would 35 drying said article. be dried under uniform ideal conditions, and (3) 5. In apparatus for drying moisture laden arti that high electrica1 efficiency would be obtained cles and including a loading station, at least one because of the insulation afforded by the glass evacuating station, and a plurality of drying sta cylinder 36. tions, the combination of means providing a 40 Although I have shown and described several closed chamber adapted to receive at least one of forms of my invention, it will be apparent to I said articles at said loading station, means for those skilled in the art that many other mod successively advancing the loaded chamber ?rst iiications thereof, as well as changes in those de to said evacuating station and then to each of scribed, are possible, For example, instead of said drying stations in turn, means for creating providing a, turntable 25, the chambers I may be a vacuum in said chamber at said evacuating sta mounted on an endless conveyor of other suitable tion and for maintaining the vacuum in said form, it being advisable, however, in the interest chamber while said chamber is subsequently at of proper continuity and e?iciency, although not each of said drying stations, means for supplying absolutely necessary, of course, that the various ' heating energy to said chamber at each of said chambers return to their original loading stations drying stations for drying said article, and at the end of the drying operation. Many other means located at each of said drying stations for similar changes will, no doubt, readily suggest controlling the amount of energy delivered by themselves to those skilled in the art. I therefore said last named means at the respective drying desire that my invention shall not be limited ex stations. cept insofar as is made necessary by the spirit 6. The invention set forth in claim 5 charac of the appended claims. terized in that said loading, evacuating and dry I claim as my invention: ing stations are arranged in endless formation 1. In apparatus for drying moisture-laden ar whereby said chamber is returned to said loading ticles, the combination of means providing a plu station from the last of said drying stations for rality of drying stations, means for supplying unloading of the dried article and loading of an heating energy to each of said stations for dry other moisture-laden article. ing the articles, variably effective means for con 7. In apparatus for drying moisture-laden arti trolling the energy supplied to said stations by said cles and including a loading station, at least one second named means, and means for bringing said evacuating station and a plurality of drying sta variably effective means successively into cooper 65 tions all arranged in endless formation, the com ative relation with each of said stations whereby bination of means providing a closed chamber to control the energy delivered at said stations. at each of said stations, means for advancing said 2. In apparatus for drying moisture-laden ar chambers in an endless path past said stations ticles, the combination of means providing a plu whereby each of said chambers is broug- t, in rality of drying stations, means for simultaneously 70 succession, first from said loading station to said supplying heating energy to each of said stations evacuating station, then from said evacuating for drying the articles, a plurality of variably ef station to each of said drying stations in turn. fective control elements for controlling the en and ?nally from the last oi.’ said drying stations ergy supplied to said stations by said second back to said loading station, said chambers each named means, said elements being each adapted TI being adapted to have a dried article therein ex that, for drying a single cake, the ratio of maxi mum to minimum oscillator input is about 3 to 1. 2,408,000 changed for a moisture-laden article when at said loading station, means for creating a vacu 10 the value of the reactance device connected to any one of said chambers at any particular time. um in each of said chambers while at said evacu 12. In electrical apparatus for drying mois ating station and for thereafter maintaining the ture-laden articles, the combination with a high frequency oscillation generator including a tuned circuit of a plurality of parallel-related, movable load circuits selectively coupled in series with said tuned circuit, each of said load circuits in cluding a reactance element and being adapted vacuum therein while said chambers are subse quently at each of said drying stations, means for simultaneously supplying heating energy to all the chambers at said drying stations for heat ing the respective articles therein, and means lo cated at each of said drying stations for con 10 . to receive in series with its reactance element a trolling the amount of energy delivered by said variable impedance element having a different last named means at the respective drying sta impedance than the impedance of any other of tions. said load circuits, said impedance elements each 8. The invention set forth in claim 7 charac consisting of at least one of the articles being terized in that the effectiveness of said control 15 dried, and said reactance elements being of dif means is different at each of said drying sta ferent values to couple predetermined high fre tions. quency power to each of said impedance ele 9. In electrical drying apparatus for drying ments in accordance with the relative positions moisture-laden articles, said apparatus including of said articles. ' a loading station, at least one evacuating station 20 13. The invention'set forth in claim 12 char and a plurality of drying stations, the combina acterized in that the articles adapted to be re tion of means providing a chamber adapted to ceived in and constituting the impedance ele receive at least one of said articles at said load ments of each of said load circuits have different ing station, a pair of cooperative electrodes in ‘moisture contents than the articles of any other said chamber between which said article is adapt 2.5 of said load circuits, the values of said reactance ed to be disposed, means for successively ad elements corresponding to the moisture content vancing the loaded chamber ?rst to said evacuat of their respectively associated articles. ing station and then to each of said drying sta 14. In electrical apparatus for drying mois tions in turn, means for creating a vacuum in ture-laden articles, the combination with a high said chamber at said evacuating station and for 30 frequency oscillation generator including a tuned ' maintaining the vacuum in said chamber while circuit of a plurality of parallel-related, movable said chamber is subsequently at each of said dry load circuits selectively coupled in series with ing stations, a source of high frequency electrical said tuned circuit, each of said load circuits be energy, and means for coupling said source to‘ ing adapted to receive therein atleast one of said ' said electrodes at each of said drying stations, articles in a different state of dryness than an said means including a plurality of reactance ele article of another of said load circuits and in ments in circuit with said source, each of said cluding a serially connected variable reactance reactance elements being of different value and element, and means for transferring each of said each being effective to couple said source to said articles successively from one of said load cir electrodes at a separate one of said drying sta 40 cuits to another, each of said reactance elements tions. having a different value whereby to couple differ 10. The invention set forth in claim 9 char ent predetermined high frequency power to each acterized in that said reactance elements are con of said articles in accordance with the relative stituted by capacitors, and characterized further positions thereof. in that each of said capacitors has a different 45 15. In electrical apparatus for drying mois value corresponding to the moisture content of ture-laden articles, the combination with a high the article being dried when it reaches the re frequency oscillation generator including a tuned spectively associated drying station of each of circuit of a plurality of parallel-related load cir said capacitors. 50 cuits connected in series with said tuned circuit, 11. In electrical drying apparatus for drying moisture-laden articles, said apparatus including said load circuits each being adapted to receive therein at least one of said articles in a different a, plurality of drying stations, the combination state of dryness than an article of any other of or means providing a plurality of chambers, one said load circuits, and means including variable at each of said drying stations, and each adapted 55 reactance elements for altering the voltages ap to contain at least one article to be dried, a pair plied by said generator across each of said arti of cooperative electrodes in each of said cham cles in correspondence with the moisture con bers between which the respective articles are tent therein. adapted to be disposed, means for maintaining a 16. In electrical apparatus for drying mois vacuum in each of said chambers at each of said 60 ture-laden articles, the combination of a high ‘frequency oscillation generator, a plurality of drying stations, 9. source of high frequency elec~ trical energy, a plurality of coupling circuits each parallel load circuits coupled in series with said including a reactance device and each coupling generator and each adapted to receive therein at least one of said articles in a different state of said source to a separate pair of said electrodes, said reactance devices each including a pair of 65 dryness than an article of any other of said load relatively movable elements one of which is unit circuits, and means for periodically varying the coupling between said generotor and said load ed with its associated chamber and the other of circuits in accordance with the moisture contents which is connected to said source, and said re actance devices being of different value whereby of said articles at predetermined times whereby the energy supplied to said respective articles is 70 to maintain the power load on said generator, dependent upon the particular reactance device within certain predetermined limits. coupled thereto, and means for effecting relative 17.111 electrical apparatus for drying mois movement between said chambers and said ture-laden articles, the combination of a pair of primary electrodes disposed in spacedv relation source whereby to effect relative movement be tween said respective elements and thereby alter 75 to each other and adapted to receive at least one 2,4os,soo 11 of said articles therebetween, a pair of second ary electrodes surrounding said primary elec trodes and connected in shunt relation to said primary electrodes, and means for coupling both said pairs of electrodes to a source of alternat ing electrical energy, the dielectric losses in said article resulting from the electric field set up by said source between said primary electrodes serv ing to heat said article su?iciently to.expel the moisture therefrom, and said secondary elec trodes serving to provide a substantially uniiorm electric iield between said primary electrodes. 18. In the method 0! drying moisture-laden articles by subjecting said articles to an electric field of high frequency, the steps which comprise simultaneously subjecting a plurality of said ar ticles, each with a di?erent moisture content, to, said electric ?eld, each at a different station and at a di?erent voltage, the article with the great- ' 12 est moisture content being subjected to the low ‘ est voltage at the ?rst of said stations, the ar ticle with the lowest moisture content being sub Jected to the highest voltage at the last of said stations, and the articles oi progressively decreas ing moisture between said first named article and said last named article being subjected, respec tively. to progressively increasing voltages at successive stations intermediate said ?rst named station and said second named station, periodi cally removing said second named article from said second named station when said latter ar ticle is dry, simultaneously advancing each of the remaining articles to stations or successively higher voltages, and simultaneously introducing to said first named station a fresh article of max imum moisture content. » CYRIL N. HOYLER.