US1118380A - Vapor electric device. - Google Patents

Description

W. B. STORY, JR.

VAPOR ELECTRIC DEVICE.

APPLICATION FILED MAY 10,1913.

1,1 18,380, Patented Nov. 24, 1914.

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UNITED? STATES PATENT OFFICE.

WILLIAM STORY, JR, OF SCHENECTADY, NEW YORK, ASSIGNOR '10 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

VAPOR, ELECTRIC DEVICE.

Specification of Letters Patent.

Application filed May 10, 1913. Serial No. 766,751.

, To all whom, it may concern:

Be it known that I, WILLIAM E. STORY, Jr., a citizen of the United States, residin at Schenectady, count of Schenectady, tate of New York, have invented certain new and useful Improvements in Vapor Electric Devices, of which the following is a specification.

The present invention relates to vapor electric devices, and is particularly applicable to mercury arc rectifiers provided with metal containers which carry loads of hundreds of kilowatts. I

One of the difiiculties encountered in devices of this kind is reverse arcin in other words, deleterious electrical disc ar es between electrodes normally used as ano es. Another difliculty is leakage of air into the evacuated container at the seals, particularly when starting the device. Deterioration of the vacuum increases the tendency of discharges between anodes and tends to cause the insulation to become coated with a dirty conductive film; I have discovered that these difliculties maybe overcome by maintaining the anodes and adjacent parts continuously and uniformly heated, preferably to the boiling point of mercury at atmospheric pressure.

My invention comprises'a novel anode con struction which includes a novel vacuum seal and means for heating the anode independently of the operation of an arc in the device.

The novel features of my invention will be pointed out with greater particularityin the appended claims.

In the accompanying drawings, Figure 1 is an elevation of an iron rectifier, Fig. 2 is a sectional detail view of the anode construc-' been shown in detail except in'so far as it involves myinvention. It comprises in the main, a cathode chamber 1, containing a' body of mercury, side chamber '2, 3 contaln 'ing-cooperating anodes consistmg-of iron,

tungsten or other suitable solid conducting,

material, one of which is shown at 11 in Fig. 2, and a cooling chamber 4 which serves to condense and return vaporized mercury to the cathode. The condensing chamber may be preferably provided with an external cooling device, such as a water spray 5, and supply tube 6, which constantly furnishes a film of water flowing over the exterior of the f chamber. The anode chambers are provided with mechanical seals 7 and 7', the construction of which is shown in detail in Fig. 2. The cathode chamber is similarly provided with a seal 8 of the same eneral nature as the anode seal. As shown 1n section in-Fig. 2 metal- walled condensing chambers 9, 9

are provided above the anodes in order toreturn vaporized material to the anodes and p to maintain their temperature at a predetermined value, as will be hereinafter more fully ex lained. The device is supported by standar s 10. The mercury arcs are started as usual by means of an auxiliary side branch are which has not been shown as its construction and operation is now well understood.

Referring to Fig. 2 it will be noted that the anode 11 consisting'of iron, tungsten or other suitable metal is made hollow, and the space within the same communicates with thecondensing chamber 9 by means of a tube 12. This space is nearly filled with a high boiling point liquid 13, which preferably is mercury. Immersed in this liquid is Patented Nov.24, 1914. a i

an electrical heater 14 consisting, for example, of a suitably insulated wire 15 provided with a protective metallic sheath 16. The resistor 15 and its sheath 16 are indicated at the terminals. The heater is so proportioned in cross section that the heat is generated at its lower end, in contact with v the mercury, so as to maintain it at the boiling oint. The condensing chamber 9 preferab y' communicates with the atmosphere by means of a tube 17, which should be loosely stoppered as indicated at 18, to permit of an'equalization of gaseous pressure causedby the intermittent puifs of mercury vapor coming from the anode and at the same time prevent the escape of mercury. The parts of the condensing chamber may be made:detachable by screw-threading as indicated at 19 in'the drawing.

The insulating anode seal is adapted to withstand fairly high temperatures without givingoflgas and-is constructed so asto adapt itself to changes of temperature without admitting air into the evacuated interior of'the rectifier. It comprises an insulating ring, or section, 20 located between the projecting flange 21 of the anode and the flange 22 of the body wall of the rectifier. This section ofinsulation consists of some suit- 26 are provided between the mineral insulation and the pressure distributing rings on the one hand and between the rings and the adjoining .parts ofthe rectifier on the other hand, and the. rings are given a surface configuration adapted to confine some of the metal of the washer when pressure is applied upon the seal. As shown in Fig. 3 the surface adjoining the insulating section is provided with parallel ridges 27, 28, which enter the surface of the metal washer when pressure is applied. The ridges 27, 28 are rounded to localize the pressure and give a narrow gasket'surface on the metal when pressure is first applied upon assembly of the device. It also prevents the, cracking of the porcelain which is experienced with sharp-cornered ridges. The opposite side of the ring 23 is provided with a depression,

the bottom of which is also ridged. When the projecting ridge 29 of the anode enters this depression and pressure is applied, the

metallic washer flows but is confined in the depression so as to maintain the seal vacuumtight. p

In some cases liquid metal, such as mercury 30, may'replace the metal of the washer between the, confining ridges to rendenthe seal vacuum-tight, as shown in Fig. 4. In this case-a considerable cavity has been provided between the projecting ridges on the ring 23 and this cavity communicates by means of a tube 31 with a small funnel 32, through which mercury, or the like may be introduced. x

Upon thetop of the anode'flange 21 are provided insulatingwashers 33 consisting of some suitable tough, inert material to wlthstand the temperature of the anode as for example, asbestos. Upon these washers bears a metal ring .34, connected to the flange 22 by means of bolts 35. Pressure is applied by tightening nuts 36. This pressure is made continuously acting by springs 37 so as to maintain the seal tight in spite of temperature variations.

The mercury in contact with the anode is heated before the load is'thro on the rectifier and is maintained at its boiling point at atmospheric pressure of about 360 C. by means of the electric heater 14 and thus a uniform high temperature is maintained at the anode and the seal even during no-load conditions when no arc is running from the anode. In other words, the temperature is maintained substantially uniform even when the load is temporarily interrupted. This has the effect of preventing the condensation of mercury on the anode surface, as the boiling point of the mercury is very much lower in the vacuum, and also minimizes the expansion and contraction of the seals due to temperature variations particularly at starting when the device is cold. In this manner it obviates two things chiefly responsible for reverse arcing, namely, depression of vacuum and condensation of mercury onthe anode. As all the space above the anode tip is maintained in this manner above the condensation temperature of the mercury vapor no condensed mercury can fall on the anode,

and cause arcing.

While the described invention has been illustrated in connection with a highpowered, metal-walled mercury rectifier, suitable for railway, or industrial'service, it is of general utility in vapor electric devices subject to reverse arcing.

What I claim as new and desire to secure by Letters Patent of the United States, is I a 1. In a vapor electric device, a vaporizable cathode, an anode of solid material and means for maintaining said anode at a uniform temperature at which mercury will not condense on the anode during intervals when the device is idle.

2. In a vapor electric device, an evacuated envelop, a mercury cathode, a solid anode and means for continuously maintaining said anode at a temperature above the boiling point of mercury in a vacuum.

. 3. In a vapor electric device, a mercury cathode, a solid anode, a body of mercury open to'the atmosphere in contact with said 5. An insulating vacuum seal adapted to withstand heating comprising a section of mineral insulation, a metal layer in contact therewith, and a flexible metallic ring'bearing upon said metal and having projections adapted to confine between the same some of said metal under pressure.

6. An insulating vacuum tight seal comprlsing an annular section of insulation,

flexible, separable pressure distributing plates located on opposite sides of said in sulation and having concentric ridges, soft metal washers interposed between said insulation and said plates and means for exerting sufiicient pressure to cause the washers to flow and make a vacuum tight sea 7. An insulating vacuum-tight seal comprising a section of imperViousmineraI insulation, a section of metal in contact therewith containing' a centrally located depression, a body of mercury in said depression,

and metal washers located between said mineral and metal sections for confining the mercury, and means for exerting continuously acting pressure upon said sections.

8. In a high-powered metal walled vapor electric device, an insulating electrode seal comprising a section of vacuum-ti ht mineral insulation, yielding pressure istributing metal plates bearing upon each side of said insulation, aluminum washers between said plates and the mineral insulation and means for exerting continuouslyacting pressure to make a vacuumtight seal.

9. In a high-powered, rectifier, the combination of a flanged solid anode, a metal container wall, a section of gas-impervious mineral insulation between said anode flange and the container wall,means for distributing pressure located between the flange and container wall, soft metal wash ers between said respective parts, and means for exerting pressure to make a vacuumtight seal.

10. A vapor the combination of electric" device comprising a metal-walled container, a solid anode, means for heating said anode independently of the are running 'from said anode, mineral insulation impervious to gas interposed between the anode and said container, and means for confining a metal under pressure in contact with said insulation to make a vacuum-tight seal.

11. In a vapor electric device, an evacuated envelop, a mercury cathode, an anode, a substance in contact with said anode boiling at a temperature so high that mercury cannot condense on the anode, and means independent of an arc between said electrodes for boiling said liquid.

12. Ina vapor electric device, a hollow anode consisting of solid conducting material, a body of mercury in contact with the internal surface of said anode, and means independent of an arc in said device for heating said mercury.

13. An insulating vacuum-tight seal comprising a section of gas impervious nonconducting material, a pressure distributing plate adjacent to said section of insulation, said plate having a plurality of projections, a soft metal gasket, and means for compressin said gasket between said parts.

14. In a igh poweredrectifier, the combination of an anode of solid conducting material having a projecting flange, a metal container wall, a section or gas-impervious insulation between said anode flange and the container wall, flexible pressure distributing rings located between the flange and container wall, soft metal washers between said rings and the section of insulation, means for exerting pressure to make a vacuumtight seal between said parts.

In witness whereof, I have hereunto set my hand this 9th daIy of May, 1913.

' WILL AM E. STORY, JR.

Witnesses:

BENJAMIN B. HULL, Hanan Onrono.

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