US1781286A - Mercury-vapor rectifier - Google Patents

Description

Nov. 11, 1930. J. KUBLER ET AL MERCURY VAPOR RECTIFIER Filed Febv 16. 1929 Fig. 7.

Fig. 2.

Inventor's Johannes Kubler Ernst Kobe! Patented Nov. 11,1930

JOHANNES KUIBLER, or BADEiN, AND Emvsr ascent, or statesmen, swrrznarinnn MER URY-Verde iinc'irrrinia Application filed February 16, 19 29, Serial No. in setting January 30,

This invention relates to improvements in metallic vapor electric current rectifiers and,

it particularly, to the cathode constriiction thereof and to means for preventing 5 the formation o'fexcessi've amounts of vapor therein. I

It wellkno'wn that occurrence'of the condition commonly called short circuiti ng, which results iromcurrent flowing be tween seja eaesmodes ot' an electric current rectifying structure 'rhther than between an anode and the cathode thereof may be caused by the formation of excessive quantities of metallic vapor which condense on the anode to produce a spot having the characteristics of the cathode. It is, therefore, desirable that the formation of excessive quantities of metallic vapor, i. e., amounts greater than necessary to conduct an electric are between the electrodes be prevented to avoid short circuiting or so'called backfiring Within the rectifier. One of the causes leading to the formation of excessive amounts of metallic vapor is the action of the electric are which travels over the surface of the cathode with cmisiderable rapidity thereby heating the entire surface of the cathode above the vaporization point of the material used. Various attempts have been made to prevent such rapid movement of the arc with the attendant heating of the cathode by providing means for fixing the are at some particular point on the cathode. Among the means proposed has been the provision of structures formed from materials having an especially high melting point and arranged Within or adjacent to the cathode material, which means, in themselves, are not satisfactory. Gontinuous researchinto the causes and the means for preventing short circuiting, above referred to, have shown that the amount of metallic vapor produced may be reduced in a very large degree without fixing the arc.

It is, therefore, among the ob ects of the present invention to provide means for preventingthe formation of an excessive amount I of metallic vapor within an electric current rectifier without the provision of any means for fixing the arc.

Another object of the inventlon 1s to proll'ieajns for cooling the surface of the catl'iode material so that tormation of the metallic vapor from the free cathode surfaces, with the exception of the point of at tachment of the are, is so far prevented that the cathode snrta'ce serves as a condenser for the vaperaliead prdduced.

Objects and advantages, other than those above set foith, will be readily apparent from the description and the drawings in which Figure 1 is a partial cross-sectional View of a metallic vapor electric current rectifier en'ibodyir'ig the present inventioii, and

Fig; 2 is a View similar to that shown in Fig.1 but illustrating a modified form of the invention. a a 3 more particularly to the drawby cliarztct'ers of reference, cathode 5 connitohly eenipnsin mercury is retained within a cbn'tainer form'ed by instilating porai ab ont an aperture in the teaoinptrcion 7 of a rectifier tank and depending therefrom. The space iiiclosed by the insulating wallsh is shnt' on by a bottom plate :8 which, according to the present inve ues, is t cirmed to provide a chamber therein. A condiiit 9 meaning through the bhttom plate 8 id coiinected with a coil of tubihg" 10 is connected to a schrceof supply for a cooling flii'id' (not shown) which' is circulated through @1 It) and returned to the cl iamber within pl'a by a connection 11 hr which chamber the cobling fluid is dis gen by a distlmg'e coiiduit 12. To obchar V tain aiid uiiitorm' heat transfer from the cathode mercnryfithe coil 10 is preferably fornx dbof material having a high heat con- ;luct1v1 ty coetficih-nt such as copper, which may be coated with a non-amalgamable material subs chromium. In order, further, to pi ote'ct the coilltl from contact therewith or attachment: thereon the electric are, a shielding plate 13 is arranged to rest upon tl'iejcooling coil 10 ,which thereforelocates 9r plate 13 just below the surface of the cathode mercury. The shield 13 fully protects the coil 10 from occasional or accidental penetration of the electric arc tllIOllgll the cathode mercury 5 and ispreferably formed of some difiicultly fusible material which does not form an amalgam with mercury. Instead of forming the cooling means, as

I. above described, as of a coil of tubing arranged within the cathode, the coil of tubing may be omitted, thereby decreasing the amountof mercury requiredfor the cathode, as is shown in Fig. 2. When the cooling coil 10 is omitted, it isdesirable that the protecting shield 13 be arranged immediately about I the'upper surface ofthe closure'member e p a ninlet 9.

dispensed with if the bottom plate 8 is made which is supplied with cooling fluids through The shield member 13 may be of some material having a high melting point. If desired, the bottom plate be made of 7 some material having a relatively low melt- 1 ing point such as iron,.provided with pro-v jecti ons' ofsome difiicultly fusible material extending into themercury to furnish points to which the are may become attached but in any event the portion thereof in contact wlth the cathode material shouldbe of material havinga high rate ofheat conductivity.

the center of the cathode are cooled.

Itwill usually be found that water is .adequate for coolingpurposes but in case a more intensive cooling of the cathode is desired, it will be understood that other cooling orrefrigerating means may be supplied to the chamber within plate 8 and to the cooling coil in such manner that the surface of the mercury is cooled far below the vaporization point thereof and is thereby adapted to operate as a condenser for those portions of the mercury vaporcoming into contact therewith.

metallic vapor type, a liquid metallic cathode,

a cooling device arranged within said cathode to provide a path for the circulation of a cooling medium therethrough said cooling device'being composed of a material having high heat conductivity, and a shielding plate of dilficultly fusible material arranged intermediate the upper surface of 'said cathode and said cooling means to prevent attachment" ofthe electric arc thereon.

metallic vapor type, a liquid metallic cathode,

. V I '75 Y 4. In an electric current rectlfier of the a coil of tubing composed of a material hav- 1 mg. hlgh heat conductlvlty and arranged Within said cathode to provide a path for the circulation of the cooling medium therethrough, and a shielding plate of difficultly fusible material arranged intermediate the upper surface of said cathode and said coolmg means to prevent attachment of the electric arc thereon.

In testimony whereof we have hereunto subscribed our namesthis 8th dayof Januarmanieaa JOHANNES KUBLERJ,

. enusrnoenn:

to provide path for the circulation of a V cooling mediumtherethrough, and a shieldmg plate of .difiicultly fusible material arranged intermediate the upper surface of said cathode and said cooling means to pre vent attachment of the electric arc thereon.

2. In an electric current rectifier of the V metallicvapor type, a liquid metallic cathode,

a cooling device'arranged within saidcathode to provide a path'for the circulation-of a cooling medium therethrough, and a shieldingplate of difficultly fusible material an ranged intermediate'the upper surface of said cathode and said cooling device to prevent attachment of the electric arc thereon.

3. In an electr1c current rectlfier of the

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