US1686027A - Inert-gas protective chamber for hydrogen-cooled machines - Google Patents

Description

Oct. 2, 1928. 1 F. D. NEWBURY INERT GAS PROTECTIVE CHAMBER FOR HYDROGEN COOLED MACHINES Filed July 23, 1925 WITNESSES:

AT ORNEY Patented Oct. 2, 192.8.I

UNITED-STATES PATENT OFFICE.

yFRANK DAVIRS NEWBURY, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC HANUFACTURIN G COMPANY, A CORPORATION OF PENN SYL- VANIAl I HEBT-GAB PROTECTIVE CHAMBER FOR HYDROGEN-COOLED MACHINES.

Application iled July 23, 1925. Serial No. 45,488.

My invention relates to the cooling or Ventilation of dynamo-electric machines and it has particular relation to such machines having a closed Ventilating system utilizing hydrogen or other gases which, if mixed with air in suitable proportions, would form an explosive mixture. i

The utilization of hydrogen has obvious advantages as a cooling medium for comvpletely enclosed generators equipped' wlth a closed Ventilating system, but, while its use has been discussed for the past several years, no practical a plication thereof has been made, princi a ly because of the danger' of explosion an fire.

In carrying out my present invention, I

' completely surround the generator, together Iwith its ducts and the cooler, with a chamber in which can be maintained an inert gas, such as carbon dioxide or nitrogen, which is preferably maintained under a pressure somewhat above that of the atmosphere. With such an arrangement,`any gas leaking into the machine will be an inert gas which cannot form an explosive mixture with the hydrogen that is utilized in theclosed Ventilating system of the machine.

In a modification of my invention, the inert gas chamber is limited to the immediate neighborhood of thegenerator shaft, which is the only place where a gas-tight'joint is impossible.

Another object of my invention is to provide means for conserving or preventing the loss of the hydrogen, and to this end I maintain the pressure of the gas in the inert-gas chambers higher than the pressure of the hydrogen in the closed Ventilating system, whereby any leakage will take place from the inert-gas chambers to the hydrogen chamber, ratherthan vice versa. A

A further object of my invention is to provide means for continuouslypurifying the hydrogen, and to this 4end I provide, within the closed Ventilating system of the machine,

. a quantity of lime or other substance which has the property of absorbing the carbon dioxide or other gas which surrounds the machine, This phase of my invention is not necessarily limited to the utilization of .an

inert-gas chamber, as the gas-absorbing substance may be such as to absorb the oxygen or other constituents of the air, in case the machine is surrounded by'A air, orin case any material quantity of air is present in the surrounding enclosure. The gas-absorbing substance or mixture may also be such as to absorb the product of combustion of hydrogen and a1r, as it is believed 'that a continuous process of combustion takes place, at a slow rate, in an atmosphere of hydrogen which contains very small quantities of oxygen, in the presence of sparking, such as obtains in the dynamo-electric machine. For this reason, a small quantity of lime inside of the Ventilating system will have a very beneficial effect in keeping the machine dr With the foregoing and other obJects in View, my invention consists in the elements and combinations hereinafter described and claimed, reference being had to the accompanying drawing, wherein Figs. 1 and 2 are longitudinal sectional Views showing a turbo-generator embodying my invention in slightly modified forms.

In the embodiment of my invention illustrated in Fig. 1, I utilize a turbo-generator l having anV enclosing casing 2, within which is disposed a closed Ventilating system of any desired type. In the illustrated embodiment,

the closed Ventilating system comprises cham bers 3 and 4, at the two ends of the rotor member 5, from which thegaseous cooling medium is sucked by means of fans 6 and- 7, whence it is discharged into end bells or chambers 8 and 9 at the two ends of the stator member 10.

A part of the air from the two end bells 8 and 9 is led to an annular intake chamber 11, surrounding the central portion of the stator member 10, and a part of the air from the end bells discharges directly into the ends ofthe air gap 12. The stator member is provided with radial intake ducts 18, which communicate with the annular intake chamber 11, and radial discharge ducts 14, which communicate with two annular discharge chambersv 15 and 16 surrounding the end portionsof the stator member. The paths of the air currents are clearly indicated by the arrows in Fig. 1.

rlhe two annular discharge ducts 15 and 16 discharge into a common discharge pipe 17 which communicates with the two chambers 3 and 4 at the ends of the rotor member,

whence the Ventilating medium is againforced through the machine by the fans. Disposed within the discharge pipe 17is a cooling device 18, which may comprise pipes carrying water or other cooling medium.

I preferably utilize hydrogen as the cooling medium which is circulated by the closed Ventilating system within the machine, on account of the fact that many kilowatts of energy may be saved, in a large machine, when hydrogen is circulated therethrough instead of the denser air which is commonly used for such purposes. v

Surrounding the main casing of the machine is a second enclosure 19, which is preferably spaced from the main casing at all points and isfilled with a suitable inert gas., preferably carbon dioxide. I preferably maintain the inert-gas pressure hlgher than the pressure of the hydrogen in the closed Ventilating system of the machine, in order to conserve the hydrogen by preventing its loss or escape from the machine, and also to guard against the possibility of the accumulation of hydrogen in the engine room where it would be likely to explode or ignite.

I also preferably maintain the inert-gas chamber at a pressure higher than that of the atmosphere for the purpose of preventing the infiltration of air into the inert-gas chamber and thence into the machine. It will-be obvious that. any suitable means may be utilized for supplymg quantities of the inert gas, either continuously or at periodic intervals, for the purpose of maintaining its pressure, in accordance with the above-described method of operation.

An important feature of my invention is the utilization of means whereby 'the costly hydrogen is conserved, and whereby any leakage that takes place is from the outer gases into the interior of the machine, rather than vice-versa. A

In carrying out the last-mentioned phase of my invention, I preferably utilize means for automatically and continuously purifying the hydrogen gas within the machine, and to this end, I place a quantity of a suitable chemical reagent 21 or absorbing material in the bottom of the vent pipe 17 of the closed ventilating system. When the gaseous medium surrounding the machine is carbon dioxide, a suitable material for the purifying substance is lime, which has the quality of absorbing not only carbon dioxide but also any water vapor which may be formed bv thel slow combination of hydrogen with such small quantities of air as may enter the machine with the .carbon dioxide. lime may also be added a substance which will absorb the oxygen, or other ingredients ofthe air, directly, rather than in combina tion with the hydrogen, as in the case of the water Vapor just referred to.

' The principal source 0f gas leakage 1s at the junction of the casing and the shaft 22, and for this reason an efficient type of seal should be utilized, such, for example as the gaskets shown at 23 and 24, for both the main generator casing 2 and the outer enclosure 19. Such seals may be of the mechanical type, or they may be steam or water seals such as have been developed in connection with steam turbines.

As the principalv source of gas-leakage is in the neighborhood of the generator shaft, I may limit my inert-gas chamber thereto, as indicated in Fig. 2, wherein exterior inertgas chambers 25 and 26 are disposed only around the ends of the machine, adjacent to the shaft. The other parts of the apparatus shown in Fig. 2 are the same as in Fig. 1.

While I have shown my invention in two embodiments and have illustrated, in each case, a certain type of a closed Ventilating system utilizing shaft fans, it is obvious that a separate motor-driven fan, or other means, may be utilized for circulating the hydrogen, and other types of Ventilating ducts within the machine may be employed, as will be obvious to those skilled in the art. I desire, therefore, that the following claims shall not be limited to the exact construction shown except as may be required by the specific language of the claims or the disclosures of the prior art. v

I claim as my invention:

, 1.' The combination with an electric machine having a tightly closed Ventilating system utilizing a gas consisting, in whole or in part, of hydrogen, of an'en'closure providing a chamber or chambers surrounding at least such portions of said machine as may admit of material gas leakage, a gas, in said enclosure, which is substantially inert to hydrogen but not altogether chemically inert, and a substance or substances disposed within said Ventilating system for chemically selectively absorbing any of such inert gas as may enter said system.

2. A dynamo-electric machine having a gas-tight, hydrogen-filled casing entirely' surrounding the same, a rotatable shaft extending through said casing, a seal for preventing the passage of a gas between s aid rotatable shaft and said casing, an external chamber surrounding said shaft on the outer side of said seal, and a filling of inert gas in said external chamber at a pressure higher than atmospheric for maintaining said external chamber substantially free of oxygen.

3. A dynamo-electric machine having a Mixed with the lll) lll

gas-tight, 'hydrogen-filled Acasing entirely 'surrounding the same, a rotatable shaft extending through said casing, a seal for preventingthe passage of al gas between said 5 rotatable shaft and said casing, and' an external, gas-tight casing substantially surrounding said rst-mentioned easing and having a seal surrounding said shaft, the space between said Casin s bein filled with a gaseous medium whic is 'su stantially free of 10 oxygen.

In testimony whereof, I have hereunto subscribed m name this 11th day of July, 1925.

RANK DAVIES NEWBURY.

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