JP2021027693A - Electric rotary machine and method for controlling concentration of ozone and nitric acid in housing thereof - Google Patents

Abstract

To suppress more effectively the concentration of ozone and nitric acid in a fully closed electric rotary machine.SOLUTION: There is provided a fully closed electric rotary machine 1 in which a stator 12 and a rotor 11 are housed in a housing 10. A fluid pumping unit that pumps a fluid composed of dry air or an inert gas into the housing 10 is provided.SELECTED DRAWING: Figure 1

Description

The present invention is a technique relating to a fully closed type electric rotary machine, particularly a fully closed type electric rotary machine using a gas flowing in a housing such as air as a primary refrigerant. The present invention is a technique for effectively suppressing the concentrations of ozone and nitric acid generated by internal partial discharge, in particular, in a large (large capacity) fully enclosed electric rotary machine having an input voltage of 6600 V or more.

In an air-cooled electric rotary machine, for example, by supplying outside air to the air passage in the machine, the outside air is used as a primary refrigerant to cool internal parts such as a stator and a rotor. In addition, in this air-cooled electric rotary machine, in order to prevent the ingress of solid foreign matter and water and contact with the human body, a fully closed outer fan type, a fully closed internal cold type, or other fully closed outer cover structure is applied as a protection method. In many cases, a fully closed electric rotary machine is used.

Furthermore, in the past, the hydrogen cooling method was adopted as the cooling method for large-capacity fully enclosed electric rotary machines, but in recent years, due to advances in materials and cooling technology, air inside the housing is circulated and used as the primary refrigerant. A cooling system has been adopted, and the size and voltage of air-cooled fully closed electric rotary machines are increasing. Further, a fully closed electric rotary machine is also adopted, which is provided with an air-cooled heat exchanger or a water-cooled heat exchanger and has a function of cooling and circulating the air of the primary refrigerant.

The stator of an air-cooled electric rotary machine is usually composed of an iron core and a winding wound around the iron core, on which measures are taken to prevent partial discharge. However, partial discharge may occur due to winding insulation or deterioration of the partial discharge inhibitor over time. In particular, in a large-capacity electric rotary machine, partial discharge is likely to occur due to a high electric field. When a partial discharge occurs in the electric rotating machine, ozone (O3), nitrogen oxides (NOx), nitric acid and the like are generated in the housing, and these are spread in the electric rotating machine with the flow of cooling air. When ozone or the like diffuses in the electric rotary machine, ozone or the like causes corrosion of metal members in the housing and deterioration of organic materials. Therefore, it is an issue to reduce the concentration of gases such as ozone, nitrogen oxides, and nitric acid in the housing. This problem is a particularly important problem in an air-cooled fully closed electric rotary machine having an input voltage of 6600 V or more and a large size and a high voltage.

Here, Patent Document 1 describes that a filter device having a removing agent layer for removing nitric acid gas is provided in the middle of the circulating air passage of the cooling air circulated by the fan. Thereby, in Patent Document 1, the nitric acid gas generated in the rotary electric machine due to the ozone generated by the discharge of the stator winding or the like is removed, and the corrosion of the metal structural member in the rotary electric machine is prevented.
Further, in Patent Document 2, by arranging an ozone decomposition unit containing an ozone decomposition catalyst in the circulating air passage, ozone is decomposed and nitric acid production is suppressed. As a result, Patent Document 2 describes that the concentrations of ozone and nitric acid generated in the cooling air flowing in the circulating air passage of the rotary electric machine can be reduced for a long period of time while suppressing the pressure loss.

Japanese Unexamined Patent Publication No. 2003-111356 International Publication No. 2011/155375

However, in the method of Patent Document 1, since nitric acid gas is removed by activated carbon or a chemical adsorbent, it is necessary to dispose a large amount of activated carbon or a chemical adsorbent in the circulating air duct. Therefore, in the method of Patent Document 1, the pressure loss in the circulating air passage increases, so that the amount of circulating cooling air decreases, and the desired cooling performance may not be obtained. Further, in the method of Patent Document 1, it is necessary to stop the electric rotary machine when exchanging or regenerating the activated carbon or the chemical adsorbent in the housing, and it is unavoidable that the operating rate of the apparatus is lowered.

In the method of Patent Document 2, although the pressure loss in the circulating air passage is reduced, air moist as much as the outside air is once introduced into the machine. Therefore, in the method of Patent Document 2, ozone and nitric acid are still generated due to the partial discharge in the electric rotary machine. In particular, when the ozone decomposition unit is installed on the downstream side of the heat exchanger, the problems of corrosion of metal parts inside the electric rotary machine and deterioration of organic materials, such as corrosion of the heat exchanger, are completely solved. I didn't.
The present invention has been made focusing on the above points, and an object of the present invention is to more effectively suppress the concentration of ozone and nitric acid in a fully closed electric rotary machine.

In order to solve the problem, one aspect of the present invention is a fully closed electric rotor in which a stator and a rotor are housed in a housing, and a fluid composed of dry air or an inert gas is introduced into the housing. The gist is to provide a fluid pumping unit for pumping.
Another aspect of the present invention is a method of suppressing the concentration of ozone and nitric acid in the housing in a fully closed electric rotary machine in which a stator and a rotor are housed in the housing. The gist is that the gas pressure inside the housing is maintained at a positive pressure rather than the atmospheric pressure outside the housing by pumping a fluid made of dry air or an inert gas into the housing from the fluid inlet formed in the above. And.

According to the aspect of the present invention, the atmosphere inside the housing becomes an atmosphere state composed of dry air or an inert gas, so that the concentration of ozone and nitric acid in the machine can be more effectively suppressed to zero or close to zero. You can. As a result, according to the aspect of the present invention, it is possible to suppress corrosion of the metal member in the electric rotary machine and deterioration of the organic material.
Aspects of the present invention are particularly effective for a fully enclosed electric rotary machine using the gas flowing in the housing as the primary refrigerant.

It is sectional drawing explaining the fully closed type electric rotary machine which uses the gas flowing in the housing as a primary refrigerant which concerns on embodiment based on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Here, the drawings are schematic, and the relationship between the thickness of each part and the plane dimension, the ratio of each part, and the like are different from the actual ones. Further, the embodiments shown below exemplify a configuration for embodying the technical idea of the present invention, and the technical idea of the present invention has the following shapes, structures, etc. of components. Not specific. The technical idea of the present invention may be modified in various ways within the technical scope specified by the claims stated in the claims.
In the present embodiment, a fully enclosed electric rotary machine 1 using the gas flowing in the housing as the primary refrigerant as shown in FIG. 1 will be described as an example. This embodiment is applicable as long as it is a fully closed electric rotary machine 1.

(Constitution)
As shown in FIG. 1, the electric rotary machine 1 of the present embodiment includes a rotor 11, a stator 12, a fan 13, and a heat exchanger 14 in a fully closed housing 10.
The rotating shaft 11a of the rotor 11 is rotatably supported by the housing 10 by a bearing 15. The stator 12 is arranged radially outward of the rotor 11 via a predetermined gap with the rotor 11, and the heat exchanger 14 is arranged radially outward of the stator 12. The heat exchanger 14 constitutes a cooler that cools the gas circulating in the housing 10.

The fan 13 is attached to the rotating shaft 11a of the rotor 11. The fan 13 rotates by the rotation of the rotor 11 to suck the gas on the axially outer side of the rotor 11 toward the center side in the axial direction, and the sucked gas is put into the gap between the rotor 11 and the stator 12. send. The gas sent to the gap between the rotor 11 and the stator 12 subsequently moves outward in the radial direction of the rotor 11, circulates in the order of the stator 12 and the heat exchanger 14, and flows to the fan 13 side again. .. In FIG. 1, the gas flow (circulation air passage) due to the rotation of the fan 13 is indicated by a thick arrow.
Here, the component of reference numeral 19 guides the gas in the housing 10 from the radial outer side to the radial inward side of the rotor 11 on the axially outer side of the rotor 11 and further directs the gas to the fan 13. It is a guide plate that guides you. As a result, while the electric rotary machine 1 is being driven, the cooled gas circulates in the housing 10 in the circulation air passage as shown by the thick arrow in FIG.

Further, the electric rotary machine 1 of the present embodiment includes a fluid pumping unit that pumps a fluid (gas) made of dry air or an inert gas into the housing 10. In the present embodiment, the fluid introduction port 10A for fluid pumping is formed in the housing 10. The discharge port of the pump 21 is connected to the fluid introduction port 10A via the pressure pipe 20. A gas supply source 22 of dry air or an inert gas is connected to the suction port of the pump 21. As a result, by driving the pump 21, a fluid composed of dry air or an inert gas can be pumped into the housing 10. The fluid pumping section of this example includes a pump 21 and a gas supply source 22. The fluid pumping unit may be configured to install an air compressor and supply dry air via an air dryer. Further, the gas supply source 22 does not have to be a single tank, and even if the equipment for purifying the inert gas (not shown) supplies the inert gas to the tank constituting the gas supply source 22. Good. The inert gas is, for example, a nitrogen gas or an argon gas. The installation position and configuration of the fluid pumping unit are not particularly limited as long as the dry air or the inert gas can be continuously or intermittently supplied into the housing 10, and the installation location and environment of the electric rotary machine 1 and its environment, and It may be appropriately determined in consideration of the ease of gas supply and the like.

The blowing of the dry air or the inert gas into the housing 10 is carried out, for example, by adjusting the flow rate so that the pressure of the gas in the housing 10 is maintained at a positive pressure of 7 kPa or more and 100 kPa or less with respect to the atmospheric pressure of the outside air. It is preferable to adjust. The flow rate of the dry air or the inert gas varies depending on the size of the housing 10 and the degree of airtightness, and is not unconditionally determined. For example, 0.15 [m ³ / min] or more and 1.5 [m] ^{A range of 3} / min] or less is desirable. Atmospheric pressure may be measured in the gas in the housing 10 with a pressure gauge 30, and dry air or an inert gas may be blown into the housing 10 based on the measured values, or the gas in the housing 10 may be blown. The blowing flow rate may be adjusted so that the flow rate is obtained in advance by an experiment or the like without measuring the atmospheric pressure.

The position for introducing the dry air or the inert gas into the housing 10 (the position where the fluid introduction port 10A is provided) is not particularly limited as long as the dry air or the inert gas can be pumped into the housing 10.
However, the fluid introduction direction 40 from the fluid introduction port 10A is preferably the circulation direction of the gas circulated by the fan 13, that is, the direction along the circulation air passage. The direction along the circulation air passage is a direction that does not go against the direction of the circulation air passage, and does not have to completely match the circulation direction of the circulation air passage, and is circulated by the fluid introduction direction 40 and the fan 13. It suffices if the circulation direction of the gas is the same. For example, the fluid introduction direction 40 is set so as to face the circulation direction rather than the direction orthogonal to the circulation direction of the circulation air passage. For example, the direction is inclined by 15 degrees or more and 165 degrees or less in the circulation direction from the direction orthogonal to the circulation direction of the circulation air passage.

In the present embodiment, the fluid introduction port 10A is set at a position closer to the rotor 11 side than the outer peripheral side of the stator 12 on the surface of the housing 10 provided with the bearing 15, and the fluid introduction direction 40 is set. It was set to go to fan 13.
Reference numeral 25 is an on-off valve such as a flow rate valve provided in the pressure pipe 20.
Further, the present embodiment is a pressure gauge 30 for measuring the pressure inside the housing 10 and a gas concentration meter 31 for measuring the concentration of ozone or nitric acid in the housing 10. The pressure gauge 30 and the gas concentration gauge 31 supply the detected detection signal to the fluid controller 32. Based on the supplied detection signal, the controller 32 controls the on-off valve 25 or the pump 21 so that the pressure in the housing 10 is within the predetermined pressure threshold range and the ozone or nitric acid concentration is equal to or lower than the predetermined concentration threshold value.

The predetermined pressure threshold range is, for example, a value that is a positive pressure of 7 kPa or more and 100 kPa or less of the atmospheric pressure in the housing 10.
The predetermined concentration threshold value is, for example, 10 ppm, preferably 1 ppm.
When the dry gas is pumped as a fluid, the amount of water in the housing 10 is adjusted to 1.0 wt% or less.
However, the pressure gauge 30, the gas concentration gauge 31, and the fluid controller 32 may not be provided. It suffices if the fluid can be pumped into the housing 10 so as to reach the above threshold value.

(Operation and others)
In the electric rotary machine 1 of the present embodiment, a fluid composed of dry air or an inert gas is pumped to introduce the fluid into the machine, and the fluid is rotationally driven by the power of the rotor 11 and the rotor 11 and the rotor 13. It is attracted to the stator 12, cooled by the heat exchanger 14, and then returned to the fan 13 side.
The circulating air passage in the housing 10 is closed from the outside, but the gas in the air passage is gradually dissipated to the outside air through the clearance of the bearing 15 and the like. Therefore, the gas in the housing 10 circulates in the electric rotary machine 1 while being replaced by the newly supplied fluid. Therefore, after the lapse of a predetermined time, the gas in the housing 10 becomes a fluid composed of almost completely or completely dry air or an inert gas.
Further, by continuously or intermittently pumping the fluid, the housing 10 becomes a positive pressure with respect to the outside air, and the atmosphere outside the housing 10 is prevented from entering the housing 10.

Conventionally, when a partial discharge occurs in the stator 12, ozone is generated, and the ozone reacts with nitrogen in the air to generate nitrogen oxides. Further, the generated nitrogen oxide reacts with the water in the machine to generate nitric acid. When the amount of ozone is large, it leads to deterioration of organic materials such as packing, and the generation of nitric acid causes stress cracking and dielectric breakdown due to nitric acid corrosion of metal members.
That is, these discharge products spread in the electric rotary machine 1 with the circulation of the gas in the housing 10, but if the gas contains water or the water adheres to the surface of the member, These waters react with nitrogen oxides to produce nitric acid. Since nitric acid significantly corrodes metal members even at a low concentration, it is the most effective means for suppressing corrosion and deterioration of the members in the electric rotary machine 1 not to generate nitric acid.

On the other hand, in the fully closed electric rotary machine 1 of the present embodiment, the gas pressure inside the housing 10 is maintained higher than the gas pressure outside the housing 10, so that moist air is released from the outside air to the housing. It is prevented from being introduced into the 10 and the dry gas circulates in the machine. Therefore, the nitrogen oxides generated by the partial discharge do not react with the water to generate nitric acid, and as a result, it is possible to suppress the corrosion and deterioration of the members in the electric rotary machine 1.

Further, by creating a dry air or an inert gas atmosphere inside the housing 10, even if a partial discharge occurs due to deterioration of the stator 12, the generation of ozone is suppressed as compared with the conventional case. In particular, when the inside of the housing 10 has an inert gas atmosphere, oxygen in the housing, which is a source of ozone, is reduced, so that the effect is greater. From this as well, as a result of suppressing the production of nitrogen oxides, the production of nitric acid is further suppressed.
Even if nitric acid is generated in the housing 10, the concentration of the generated nitric acid becomes lower than before as a result of the continuous or intermittent pumping of the dry air or the inert gas.
Here, it has been confirmed that when the water content of the dry air or the inert gas is 1.0 wt% or less, the production of ozone and nitric acid can be reliably suppressed (see the examples below).

Further, if the gas pressure inside the housing 10 is maintained at a positive pressure of 7 kPa or more with respect to the gas pressure outside the housing 10, the inflow of outside air unexpectedly generated due to a change in the state inside the machine or the like is surely prevented. As a result, the inflow of water into the aircraft can be prevented. However, if the degree of positive pressure is too large, the door attached to the housing 10 may open violently, or gas may blow out from the gap of the housing 10 at a high flow velocity. It is desirable that the difference in gas pressure between the inside and outside of the housing 1 is a positive pressure of 100 Pa or less, because there may be a problem in the safety of the operator involved in the above.
Further, the present invention is highly effective when applied to a large-capacity electric rotary machine 1 having an input voltage of 6600 V or more and a partial discharge easily occurring due to a high electric field.

(effect)
As described above, the present embodiment has the following effects.
(1) The present embodiment is a fully closed electric rotary machine 1 in which a stator 12 and a rotor 11 are housed in a housing 10, and a fluid composed of dry air or an inert gas is introduced into the housing 10. It is provided with a fluid pumping unit for pumping.
According to this configuration, a fully closed electric rotary machine 1 capable of creating an atmosphere of dry air or an inert gas inside the housing 10 and further creating a positive pressure with respect to the outside air inside the housing 10 is provided. Is possible.

(2) The present embodiment is a method of suppressing the concentrations of ozone and nitric acid in the housing 10 in the fully closed electric rotary machine 1 in which the stator 12 and the rotor 11 are housed in the housing 10. By pumping a fluid made of dry air or an inert gas from the fluid inlet 10A formed in the housing 10 into the housing 10, the gas pressure inside the housing 10 is increased from the atmospheric pressure outside the housing 10. Also keeps positive pressure.
According to this configuration, the intrusion of moisture from the outside air into the housing 10 is prevented, and the inside of the housing 10 is in an atmosphere state of dry air or an inert gas. As a result, even if a partial discharge occurs due to the deterioration of the stator 12, the generation of ozone and nitric acid can be suppressed, and the deterioration of the organic member in the electric rotary machine 1 and the corrosion of the metal material can be effectively suppressed.
Before the stator 12 deteriorates, the inside of the housing 10 may be in an atmosphere of dry air or an inert gas, but even if the stator 12 deteriorates and partial discharge occurs, ozone or nitric acid may occur. Can be suppressed to almost 0%.

(3) In the present embodiment, the fluid introduction direction 40 from the fluid introduction port 10A is set in a direction along the gas circulation direction.
According to this configuration, even if the above fluid is pumped into the housing 10, it is possible to prevent the circulation of the gas generated by the power of the fan 13 from being obstructed. Further, the pumping of the fluid promotes the circulation of gas, and has the effect of reducing the driving force of the fan 13 by that amount.

(4) The electric rotary machine 1 of the present embodiment has an input voltage of 6600 V or more.
By applying the present invention to a large electric rotary machine 1 having an input voltage of 6600 V or more, even a large-capacity electric rotary machine 1 in which partial discharge is likely to occur due to a high electric field can be effectively inside the electric rotary machine 1. It is possible to suppress the corrosion and deterioration of the members.
Here, in order to confirm the effect, the following experiment was carried out.
That is, targeting a fully closed synchronous motor having a capacity of 15700 kW and an input voltage of 11000 V, as shown in FIG. 1, the pressure is 7 kPa higher than the atmospheric pressure of the outside air so as to be from the outside in the substantially axial direction toward the inside and toward the fan 13. is to be maintained at a high state, the dry air was continuously pumped to a blowing housing 10 in a range from the velocity 0.3 m ³ / min of 1.2 m ³ / min. The water content of the dry air was 1.0 wt% or less.

Then, the ozone concentration and the nitric acid concentration in the housing 10 were measured over time from before the above-mentioned dry air was pumped to after the above-mentioned dry air was pumped.
The pumping of dry air was started after the ozone concentration and the nitric acid concentration in the housing 10 had increased.
As a result of the observation, the changes in ozone concentration and nitric acid concentration were such that the ozone concentration first increased and then the nitric acid concentration increased later. Then, when it was confirmed that the ozone concentration exceeded 30 ppm and the nitric acid concentration exceeded 20 ppm, continuous pumping of dry air was started, and the ozone concentration became 0 ppm in a short period of one week or less. At the same time, it was confirmed that the nitric acid concentration was 0 ppm.
After that, when the dry air was continuously pumped for half a year, it was confirmed that the ozone concentration and the nitric acid concentration could be maintained at almost 0 ppm.

As described above, by continuously pumping dry air into the housing 10, the ozone concentration and the nitric acid concentration can be maintained at almost 0 ppm. Therefore, by applying the present invention, dynamic rotation can be performed over a long period of time. It was found that corrosion and deterioration of the members inside the machine can be prevented.

1 Electric rotary machine 10 Housing 10A Fluid introduction port 11 Rotor 12 Stator 13 Fan 14 Heat exchanger 15 Bearing 20 Pressure piping (fluid pumping section)
21 Pump (fluid pumping unit)
22 Gas supply source (fluid pumping unit)
40 Introduction direction

Claims (6)

It is a fully closed electric rotary machine in which a stator and a rotor are housed in a housing.
An electric rotary machine including a fluid pumping unit that pumps a fluid composed of dry air or an inert gas into the housing. A fully closed electric rotor having a fan provided on the rotor and circulating gas in the housing as the rotor rotates, and using the gas flowing in the housing as the primary refrigerant.
The fluid is introduced from the fluid inlet formed in the housing,
The electric rotary machine according to claim 1, wherein the introduction direction of the fluid from the fluid introduction port is set in a direction along the circulation direction of the gas. The electric rotary machine according to claim 1 or 2, wherein the input voltage is 6600 V or more. A method of suppressing the concentrations of ozone and nitric acid in the housing in a fully closed electric rotary machine in which a stator and a rotor are housed in the housing.
By pumping a fluid made of dry air or an inert gas into the housing from the fluid inlet formed in the housing, the gas pressure inside the housing is maintained at a positive pressure rather than the atmospheric pressure outside the housing. A method for suppressing the concentration of ozone and nitric acid in an electric rotating machine housing. The electric rotary machine is a fully closed type electric rotary machine provided in the rotor and having a fan that circulates gas in the housing as the rotor rotates, and uses the gas flowing in the housing as a primary refrigerant. ,
The method for suppressing the concentrations of ozone and nitric acid in an electric rotary machine housing according to claim 4, wherein the introduction direction of the fluid from the fluid introduction port is a direction along the circulation direction of the gas. The method for suppressing the concentration of ozone and nitric acid in the electric rotating machine housing according to claim 4 or 5, wherein the input voltage of the electric rotating machine is 6600 V or more.

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