Dynamo-electric machine provided with gas purity maintainer

According to one embodiment, a dynamo-electric machine includes a rotor, a stator, a frame, a shaft sealing device, and a gas purity maintainer. The gas purity maintainer includes an expansion tank, a first mist collecting section, a valve unit, a drain pot, and an instrument panel. The first mist collecting section is provided in the middle of a scavenging pipe extending from the expansion tank to discharge a coolant gas from the expansion tank. A downstream in the first mist collecting section is higher than an upstream.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2011-199275, filed Sep. 13, 2011, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a dynamo-electric machine provided with a device that maintains purity of a coolant gas sealed in a frame.

BACKGROUND

A dynamo-electric machine includes a rotor, a stator, a bearing, and a frame, and hydrogen gas is sealed as a coolant gas in the dynamo-electric machine. A shaft sealing device is provided at the bearing such that the coolant gas does not leak from the bearing. Sealing oil having a pressure higher than internal pressure of the dynamo-electric machine is supplied to the shaft sealing device through a sealing oil supply line. The sealing oil discharged from the shaft sealing device is collected and returned to the sealing oil supply line. The sealing oil, which flows and is discharged onto an air side of the bearing from the shaft sealing device, contains Gases, such as air. When the collected oil is circulated to the sealing oil supply line, the gases are dissolved from the sealing oil to gradually degrade purity of the hydrogen gas in the frame.

There are well known two systems that are provided in the sealing oil supply line in order to maintain the purity of the hydrogen gas. One of the systems is a vacuum treatment system in which the sealing oil supplied to the shaft sealing device is degassed with a vacuum treatment apparatus, and the other is a continuous scavenging system in which not the vacuum treatment apparatus but equipment is provided in order to maintain the purity of the hydrogen gas in the dynamo-electric machine.

For the gas purity maintainer in which the continuous scavenging system is adopted, the purity of the hydrogen gas in the dynamo-electric machine is gradually degraded because the sealing oil to which a vacuum treatment is not performed is supplied to the shaft seal device. Therefore, the purity of the gas is maintained by automatically supplying the new hydrogen gas having the high purity while a given amount of gas is continuously scavenged.

When the coolant gas is scavenged from a sealing oil treatment system by the continuous scavenging system in order to maintain the purity of the hydrogen gas that is of the coolant gas in the dynamo-electric machine, part of the sealing oil becomes mist having a fine particle size, and is mixed in the scavenged coolant gas. When the mist of the sealing oil is mixed in the scavenged coolant gas, the mist of the sealing oil adheres in the middle of the piping which transports the coolant gas, and returns to a liquid. The liquid of the sealing oil is accumulated in the piping. A needle valve that controls a scavenging flow rate and the pressure and an instrument panel in which gauges, such as a flowmeter and a purity meter, are placed are connected in the middle of the coolant gas scavenging piping. The flowmeter measures the scavenging flow rate, and the purity meter measures the purity of the hydrogen gas that is of the scavenged gas.

Particularly, when the mist invades in the needle valve and the gauges of the instrument panel, the liquid sealing oil is easily accumulated due to structures of the needle valve and the gauges. As a result, an error is generated in the flow rate controlled by the needle valve, or errors are generated in displays of the gauges. When the error is generated in the flow rate controlled by the needle valve, the scavenging flow rate of the coolant gas is decreases to degrade the purity of the hydrogen gas that is of the coolant gas. When the errors are included in the displays of the gauges, continuous scavenging operation cannot properly be performed because normal monitoring is not performed.

DETAILED DESCRIPTION

A dynamo-electric machine according to an embodiment prevents mist of sealing oil from being carries onto a downstream along piping through which scavenged coolant gas is transported. The dynamo-electric machine includes a rotor, a stator, a frame, a shaft sealing device, and a gas purity maintainer. The frame accommodates the rotor and the stator therein, and an inside of the frame is filled with the coolant gas. The shaft sealing device is attached to an outer circumference of a shaft of the rotor, and the sealing oil having a pressure higher than a pressure of the coolant gas is supplied to the shaft sealing device. The gas purity maintainer is connected to a sealing oil supplying line which circulates the sealing oil discharged from the shaft seal device to the shaft seal device, and maintains purity of the coolant gas at a given value or more. The gas purity maintainer includes an expansion tank, a first mist collecting section, a valve unit, a drain pot, and an instrument panel. The expansion tank collects part of the coolant gas together with the sealing oil flowing out to a hydrogen filled side of the frame from the shaft sealing device, and the expansion tank separates and extracts the coolant gas mixed in the sealing oil. The first mist collecting section is provided in a middle of a scavenging pipe, which extends from the expansion tank, in order to exhaust the coolant gas in the expansion tank, and a downstream in the first mist collecting section is higher than an upstream. The valve unit is disposed on the downstream of the first mist collecting section to control a flow rate of the coolant gas. The drain pot is disposed on the downstream of the valve unit. The instrument panel is disposed on the downstream of the drain pot and comprises a flowmeter and a purity meter for the coolant gas.

A dynamo-electric machine1according to a first embodiment will be described with reference toFIG. 1. The dynamo-electric machine1shown inFIG. 1includes a rotor11, a stator12, a frame13, a bearing14, and a gas purity maintainer15. The rotor11and the stator12are accommodated in the frame13. An inside of the frame13is filled with hydrogen gas used as a coolant gas G. The bearing14supports a shaft111of rotor11and includes a shaft sealing device141which is attached to an outer circumference of the shaft111to seal the coolant gas G.

The shaft sealing device141A is supplied sealing oil L from a sealing oil supplying line2with a pressure higher than that of the coolant gas G. The shaft seal device141seals a gap between the shaft111of the rotor11and the frame13such that the sealing oil L is caused to flow out to both of an inside and an outside of the frame13along an outer surface of the shaft111of the rotor11.

The gas purity maintainer15includes an expansion tank21, a first mist collecting section31, a valve unit32, a drain pot33, and an instrument panel34. The gas purity maintainer15is connected to the sealing oil supplying line2which circulates the sealing oil L discharged from the shaft sealing device141to the shaft sealing device141, and maintains purity of the coolant gas G at a given value or more.

The expansion tank21is placed at a level lower than the shaft sealing device141, and includes an inflow port211at a level higher than a liquid level in the tank. The oil drain pipe22is connected to the inflow port211. The expansion tank21collects the sealing oil L, which flows onto a hydrogen side of the bearing14from the shaft seal device141, through the oil drain pipe22. In the expansion tank21, the part of coolant gas G mixed in the sealing oil L is separated and extracted. The expansion tank21and the oil drain pipe22constitute a route through which the sealing oil L is collected while the coolant gas G is partially scavenged as a scavenging gas.

The expansion tank21includes an exhaust port212in an upper portion far from the inflow port211. A scavenging pipe3is connected to the exhaust port212. The scavenging pipe3connects to the instrument panel34through the first mist collecting section31, the valve unit32, and the drain pot33. The first mist collecting section31is connected to downstream of a bellows valve301that is attached to the scavenging pipe3extending upwardly vertically from the exhaust port212of the expansion tank21. The first mist collecting section31is placed such that the downstream of the first mist collecting section31is higher than the upstream. In the first embodiment, the first mist collecting section31is sloped pipe that is placed with an up-grade such that a relative position becomes higher toward the downstream.

The valve unit32is disposed on the downstream of the first mist collecting section31, and controls a scavenging flow rate of the coolant gas G. The valve unit32includes a needle valve321for controlling a flow rate and seal valves322and323placed on the upstream and downstream of the needle valve321respectively. In the first embodiment, bellows valves are used as the seal valves322and323. The drain pot33is disposed on the downstream of the valve unit32, and removes a mist and vapor of the sealing oil L in the coolant gas G. The coolant gas G passing through the drain pot33is sent to the instrument panel34.

The instrument panel34includes a flowmeter341that measures the flow rate of the coolant gas G passing through the scavenging pipe3and a purity meter342that measures the purity of hydrogen gas of the coolant gas G being scavenged. The dynamo-electric machine1includes a management device for the coolant gas G, monitors the purity of the hydrogen gas as the coolant gas G in the frame13from a value of the purity meter342based on the flow rate and purity, which are measured in the instrument panel34, and controls the flow rate of the coolant gas G for scavenging and the flow rate of the high-purity hydrogen gas supplied to the frame13.

The coolant gas G passing through the instrument panel34is released from an atmospheric release pipe35. The dynamo-electric machine1further includes a drain route41that is branched from a position, in which the atmospheric release pipe35and the instrument panel34are connected, to extend downward. The drain route41is connected in the middle of a drain route332of the drain pot33, which leads to a drain reservoir331.

According to the shaft sealing devices141, the dynamo-electric machine1may include routes from the expansion tank21to the instrument panel34in order to scavenge the coolant gas G, or the routes may merge on the way.

In the dynamo-electric machine1including the above components, even if the mist of the sealing oil L that is mixed in the coolant gas G scavenged from the expansion tank21adheres to an inner wall of the first mist collecting section31and becomes a drip, the mist flows toward the upstream of the first mist collecting section31and returns to the expansion tank21. Accordingly, the dynamo-electric machine1can prevent the mist of the sealing oil L from being carried to the valve unit32or the instrument panel34, which prevents a malfunction caused by the sealing oil L accumulated in the needle valve321used as the flow rate control valve placed in the valve unit32or the flowmeter341and purity meter342of the instrument panel34.

Dynamo-electric machine1according to second to ninth embodiments will be described below with reference to drawings. In each of the drawing, the component having the same function as the dynamo-electric machine1of the first embodiment is designated by the same numeral as the dynamo-electric machine1of the first embodiment, and the description refers the appropriate portion of the first embodiment. It is assumed that the component that is not described or illustrated in each embodiment or drawing is identical to that of the first embodiment, andFIG. 1and the description is referred in each embodiment.

A dynamo-electric machine1according to a second embodiment will be described with reference toFIG. 2. As illustrated inFIG. 2, the dynamo-electric machine1of the second embodiment differs from that of the first embodiment in a shape of a first mist collecting section31. The first mist collecting section31is ascending piping that vertically connects an upstream of scavenging pipe3extending upward from an expansion tank21and a downstream of scavenging pipe3leading to a valve unit32.

Similarly to the first embodiment, even if the mist of the sealing oil L flowing out from the expansion tank21adheres to the inner wall of the first mist collecting section31and becomes the drip, the sealing oil L does not flow toward the valve unit32which is in the downstream of the first mist collecting section31, but return to the expansion tank21. An upstream end of the first mist collecting section31is vertically connected to the scavenging pipe3. An orientation of the flow of the coolant gas G is bent at a substantially right angle in the connection portion. Therefore, the mist of the sealing oil L in the coolant gas G collides with a wall surface to facilitate the collecting.

A dynamo-electric machine1according to a third embodiment will be described with reference toFIG. 3. A first mist collecting section31in the dynamo-electric machine1of the third embodiment as shown inFIG. 3is identical to that of the first embodiment. Two valve units32are provided in parallel. At least three valve units32may be provided in parallel depending on conditions, such as the flow rate of the coolant gas G being scavenged.

In the valve unit32of the dynamo-electric machine1, a needle valve321can separately be detached by closing seal valves322and323disposed on the upstream and downstream. In the third embodiment, the two valve units32are provided in parallel, so that one of the valve units32can be detached for the purpose of maintenance or cleaning even if the dynamo-electric machine1is running. That is, it is not necessary to stop the dynamo-electric machine1.

A dynamo-electric machine1according to a fourth embodiment will be described with reference toFIG. 4. A gas purity maintainer15in the dynamo-electric machine1of the fourth embodiment, as shown inFIG. 4, further includes blow piping42that is branched from a point between the downstream of a first mist collecting section31and a valve unit32to extend downward. The blow piping42includes a sight glass421and a seal valve422. The downstream of the blow piping42is connected in the middle of a drain route332of a drain pot33like a drain route41. A bellows valve is applied for the seal valve422. Similarly to the third embodiment, the two valve units32are provided in parallel.

Since the mist of the sealing oil L in the coolant gas G passing through the first mist collecting section31adheres to an inner surface of a scavenging pipe3extending downward from the first mist collecting section31and turns to the drip, the sealing oil L is accumulated in the blow piping42that is downwardly extended. As the blow piping42includes the sight glass421, it can be checked that how much the sealing oil L is accumulated and it is easy to understand the time when the sealing oil L accumulated in the blow piping42must be discharged.

When the cleaning blow for periodically removing the sealing oil L accumulated in the blow piping42will be performed, the upstream seal valve322of the valve unit32is closed, and the seal valve422of the blow piping42is repeatedly opened and closed several times. The sealing oil L adhering to the inner surfaces of the scavenging pipe3and blow piping42, which are located on the downstream of the first mist collecting section31, is also blows by the coolant gas G scavenged from the inside of a frame13.

The dynamo-electric machine1of the fourth embodiment includes the blow piping42, so that how much the mist of the sealing oil L flows downward can be checked by the sight glass421. Accordingly, in addition to the periodical maintenance in which the accumulated sealing oil L is blown, the time for blowing the accumulated sealing oil L is easily determined depending on the situation. Therefore, the malfunction of the valve unit32or indication failures of the flowmeter341and purity meter342of the instrument panel34can previously be prevented.

A dynamo-electric machine1according to a fifth embodiment will be described with reference toFIG. 5. A gas purity maintainer15in the dynamo-electric machine1of the fifth embodiment, as illustrated inFIG. 5, includes a second mist collecting section36that is located between a position in which blow piping42is branched and a valve unit32. The second mist collecting section36is provided such that the downstream of the second mist collecting section36is higher than the upstream in a relative position. The second mist collecting section36of the fifth embodiment is the sloped pipe that becomes the up-grade toward the downstream. Similarly to the third embodiment, the two valve units32are provided in parallel.

The mist of the sealing oil L adhering to the inner wall of the second mist collecting section36flows in and is accumulated in the blow piping42. The sealing oil L accumulated in the blow piping42is discharged similarly to the fourth embodiment. Since the gas purity maintainer15includes the second mist collecting section36, the sealing oil L, which adheres to the inner walls of the scavenging pipe3from the branched point of the blow piping42to the valve unit32and turns to the drip, can effectively be collected and discharged.

A dynamo-electric machined according to a sixth embodiment will be described with reference toFIG. 6. The dynamo-electric machine1of the sixth embodiment as shown inFIG. 6differs from the dynamo-electric machine1of the fifth embodiment in that a second mist collecting section36is the ascending piping that vertically connects the upstream scavenging pipe3and the downstream scavenging pipe3. A first mist collecting section31may be the ascending piping as the second embodiment instead of the sloped pipe inFIG. 6.

The dynamo-electric machine1of the sixth embodiment includes the second mist collecting section36. Therefore, the sealing oil L, which adheres to the inner wall of the scavenging pipe3from the branched point of the blow piping42to the valve unit32and turns to the drip, can effectively be collected similarly to the fifth embodiment.

A dynamo-electric machine1according to a seventh embodiment will be described with reference toFIG. 7. A gas purity maintainer15in the dynamo-electric machine1of the seventh embodiment as shown inFIG. 7includes a mist trap37that is located between a point where the blow piping42is branched and a second mist collecting section36. The mist trap37includes a container371in which an oil370having the same component as the sealing oil L is reserved, an inflow port372that is connected to an upstream of the scavenging pipe3and inserted in the oil370, and an outflow port373that is connected to the downstream of the scavenging pipe3from above the liquid level of the oil370.

A sealing valve374is also placed between the position where the blow piping42is branched and the mist trap37. A bellows valve is applied for the sealing valve374. When the sealing oil L accumulated in the blow piping42is discharged, the sealing valve374located on the upstream of the mist trap37is closed, and the seal valve422on the blow piping42is opened.

Since the gas purity maintainer15includes the mist trap37, the mist of the sealing oil L included in the coolant gas G passed through the first mist collecting section31can be separated by the mist trap37. The mist trap37is placed on the upstreams of the valve unit32, drain pot33, and instrument panel34. Therefore the mist of the sealing oil L can be prevented from being carried to these instruments. An amount of oil mist passing through the valve unit32or the drain pot33is reduced. Hence, the number of maintenance or cleaning times of the valve unit32or the drain pot33can be reduced. Additionally, a probability of generating indication failures of measurement instruments, such as a flowmeter341and a purity meter342, is significantly reduced by the reduction of the amount of oil mist reaching an instrument panel34.

A dynamo-electric machine1according to an eighth embodiment will be described with reference toFIG. 8. In a gas purity maintainer15of the dynamo-electric machine1of the eighth embodiment as shown inFIG. 8, a mist trap37that is identical to the mist trap37in the gas purity maintainer15of the seventh embodiment is placed in a scavenging pipe3between a drain pot33and an instrument panel34. A sealing valve375is placed on the upstream of the mist trap37. The sealing valve375is closed, during the maintenance, to prevent oil370in the mist trap37from reversely flowing into the scavenging pipe3.

The amount of mist of the sealing oil L reaching the instrument panel34is significantly reduced by placing the mist trap37between the drain pot33and the instrument panel34.

A dynamo-electric machine1according to a ninth embodiment will be described with reference toFIGS. 9 and 10. An internal structure of an expansion tank21of a gas purity maintainer15in the dynamo-electric machine1of the ninth embodiment, as shown inFIGS. 9 and 10, differs from that of the expansion tank21of the first to eighth embodiments. The expansion tank21as shown inFIG. 9includes a mist collector213that partitions an upper-side portion from at least an oil level, namely, a portion filled with the coolant gas G between an inflow port211and an exhaust port212.

Specifically, a lower edge213aof the mist collector213extends to a position lower than an opening231of an oil-collecting path23. The oil collecting path23returns the sealing oil L accumulated in the expansion tank21to a sealing oil supply line20. Therefore the lower edge213ais submerged in the sealing oil L. The mist collector213includes an aeration filter214in a position higher than the oil level.

When a mesh of the aeration filter214is excessively fine, the aeration filter214becomes an aeration resistance of the coolant gas G, and the aeration filter214is clogged with the sealing oil L or generates new mist on the downstream by piping the clogged sealing oil L. Accordingly, the aeration filter214having an enough roughness for the mesh, which is not easily closed by a surface tension of the sealing oil L, is adopted.

The aeration filter214collects an oil drop, which jumps when the sealing oil L flows into the expansion tank21, or the mist of the sealing oil L having a rage particle size included in the coolant gas G, and causes the coolant gas G to pass therethrough. The sealing oil L collected by the aeration filter214is accumulated in the expansion tank21along the mist collector213. As the mist collector213is placed in the expansion tank21and collects the mist having the large particle size, it is reduces an absolute amount of the mist of the sealing oil L flowing onto the downstream of the expansion tank21.

A mist collector, in which a flow channel as a labyrinth is formed by a vane instead of the aeration filter214and in which the coolant gas G including the mist of the sealing oil L is caused to pass through the flow channel to be collected the mist, may be adopted. Alternatively, a mist collector in which an electric field is generated by static electricity to attract the mist like an electric dust collector may be available when the sealing oil L has an electrical insulating property. A cyclone-system mist collector that generates a swirling flow to centrifuge the mist from the coolant gas G may be placed in front of the exhaust port212.