Power generation apparatus including lubricant separation member

A power generation apparatus of the present invention includes: a separation member that separates a lubricant from a fluid mixture flowing into an expander casing; an expander rotor that is rotationally driven by an expansion force applied from steam of a working medium from which the lubricant is separated; a power generator rotor that rotates with the rotation of the expander rotor; a first bearing holding portion that accommodates a first bearing supporting a first rotation shaft of the expander rotor; a second bearing holding portion that accommodates a second bearing supporting a second rotation shaft of the expander rotor; and a lubricant supply path which connects a lubricant accumulation position inside the expander casing to both inner spaces of the first bearing holding portion and the second bearing holding portion of which the pressures are lower than the pressure of the lubricant accumulation position inside the expander casing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a power generation apparatus and a power generation system.

2. Description of the Related Art

Hitherto, as a power generation system that recovers power from low-temperature waste heat, a binary-cycle power generation system is known in which a working medium (cooling medium) having a low boiling temperature is evaporated by waste heat, an expander rotor is rotationally driven by steam of the working medium, and a power generator is driven by the rotation of the expander rotor. Japanese Patent Application Laid-Open No. 60-56104 discloses an example of the power generation system.

The power generation system of the related art includes an expander, a power generator, a condenser, a cooling medium supply pump, an evaporator, a separation tank, a lubricant supply pump, and a lubricant heating heat exchanger.

The expander includes a casing and a pair of expander rotors (screw rotors) accommodated in the casing. The steam of the cooling medium produced by the evaporator is suctioned into the casing, and the suctioned steam rotationally drives the pair of expander rotors by the expansion force thereof. In accordance with the rotation of the expander rotor, the power generator connected to the expander rotor is driven to generate power. Further, a lubricant is supplied into the casing so as to lubricate a bearing supporting a rotation shaft of the expander rotor or to seal respective portions inside the casing.

Since the lubricant supplied into the casing is discharged from the inside of the casing along with the steam of the cooling medium having been used to rotationally drive the expander rotor, a fluid mixture formed by mixing the lubricant and the steam of the cooling medium discharged from the inside of the casing is separated into the lubricant and the steam of the cooling medium in the separation tank. The steam of the cooling medium separated by the separation tank is discharged from the separation tank and is cooled and condensed by the condenser so as to become a liquid cooling medium. Then, the liquid cooling medium is sent to the evaporator by the cooling medium supply pump and is heated by the waste heat in the evaporator so as to produce steam of the cooling medium. The steam of the cooling medium produced by the evaporator is supplied into the casing of the expander. In this way, the cooling medium is circulated. Meanwhile, the lubricant which is separated by the separation tank is discharged from the separation tank and is sent to the casing of the expander through the heat exchanger by the lubricant supply pump.

SUMMARY OF THE INVENTION

In the power generation system of the related art, since the separation tank is provided so as to separate the fluid mixture discharged from the casing of the expander into the lubricant and the steam of the cooling medium and the lubricant supply pump is provided so as to return the lubricant separated by the separation tank to the casing of the expander, there are problems in which the configuration becomes complex, the size of the power generation system is increased, and the manufacturing cost increases.

The present invention is made to solve the above-described problems, and it is an object of the present invention to provide a power generation apparatus and a power generation system capable of realizing a simple configuration and a compact size thereof and reducing manufacturing cost thereof.

In order to attain the above-described object, a power generation apparatus according to the present invention includes: a casing into which a fluid mixture formed by mixing a liquid lubricant and steam of a working medium flows; a separator which is provided inside the casing so as to separate the lubricant from the fluid mixture flowing into the casing; an expander rotor which is provided inside the casing and is rotationally driven by an expansion force applied from the steam of the working medium in the fluid mixture from which the lubricant is separated by the separator; a power generator which includes a power generator rotor connected to the expander rotor and rotating with the rotation of the expander rotor and which generates power by the rotation of the power generator rotor; a bearing which is provided inside the casing and supports a rotation shaft of the expander rotor so that the expander rotor and the power generator rotor are rotatable about the axes thereof; a bearing holding portion which is provided inside the casing and accommodates the bearing therein while holding the bearing; and a lubricant supply path which connects a position for accumulating the lubricant separated by the separator in a space inside the casing to an inner space of the bearing holding portion accommodating the bearing, wherein the bearing holding portion is provided at a position in which a pressure of the inner space of the bearing holding portion becomes lower than a pressure of the position for accumulating the lubricant inside the casing.

In the power generation apparatus, the lubricant is separated from the fluid mixture flowing into the casing by the separator and the separated lubricant is accumulated in the casing. That is, since the lubricant may be separated inside the casing of the power generation apparatus, there is no need to separately provide the lubricant separation tank at the outside. For this reason, it is possible to realize a simple configuration and a compact size of the power generation apparatus and reduce the manufacturing cost thereof compared to the power generation apparatus of the related art with the lubricant separation tank. Further, in the power generation apparatus, since the lubricant accumulation position inside the casing may be connected to the inner space accommodating the bearing of the bearing holding portion by the lubricant supply path and the pressure of the inner space of the bearing holding portion is lower than the pressure of the lubricant accumulation position inside the casing, the lubricant which is separated by the separator inside the casing flows to the inner space of the bearing holding portion through the lubricant supply path so as to be supplied to the bearing by a difference in pressure between the lubricant accumulation position inside the casing and the inner space of the bearing holding portion. For this reason, there is no need to separately provide the pump that pressure-feeds the separated lubricant like the power generation apparatus of the related art. Even for this reason, in the power generation apparatus, the simple configuration and the compact size of the power generation apparatus may be realized and the manufacturing cost thereof may be reduced.

In the power generation apparatus, the casing may include an inlet through which the fluid mixture flows into the casing, and the separator may be formed by a separation member that is disposed to face the inlet so that the fluid mixture flowing into the casing through the inlet runs into the separation member.

In this configuration, the fluid mixture flowing into the casing through the inlet runs into the separation member and hence the lubricant falls downward in a flowing state by the own weight while the movement of the lubricant in the fluid mixture in the inflow direction is prohibited by the separation member. For this reason, it is possible to promote the separation of the lubricant in the fluid mixture flowing into the casing. Thus, according to this configuration, it is possible to specifically form the separator for separating the lubricant from the fluid mixture flowing into the casing.

In the configuration in which the separator is formed by the separation member, the separation member may include a demister which captures the lubricant in the fluid mixture flowing into the casing and running into the separation member.

Since the demister is formed in a mesh shape and exhibits a high capturing effect with respect to a droplet-shaped or mist-shaped liquid in an air stream, when the separation member includes the demister like this configuration, it is possible to satisfactorily capture the lubricant in the fluid mixture colliding with the demister of the separation member. For this reason, it is possible to improve the efficiency of separating the lubricant from the fluid mixture flowing into the casing.

In the configuration in which the separator is formed by the separation member, the separation member may include a facing surface which is disposed to face the inlet so that the fluid mixture flowing into the casing through the inlet runs into the facing surface, and the facing surface may be inclined with respect to the inflow direction of the fluid mixture flowing into the casing through the inlet.

In this configuration, since the facing surface of the separation member disposed to face the inlet of the casing is inclined with respect to the inflow direction of the fluid mixture, the fluid mixture flowing into the casing through the inlet runs into the facing surface of the separation member and forms the swirl flow while changing the direction along the inclination of the facing surface. As a result, the separation of the lubricant from the fluid mixture is promoted. For this reason, it is possible to improve the efficiency of separating the lubricant from the fluid mixture flowing into the casing.

In the power generation apparatus, a pair of the expander rotors may be provided inside the casing and an expansion chamber may be formed between the pair of expander rotors so that the steam of the working medium rotationally driving the expander rotor flows into the expansion chamber. Then, an upper portion inside the casing may be provided with a steam inlet that is used to introduce the steam of the working medium from which the lubricant is separated inside the casing into the expansion chamber.

In this configuration, since the steam inlet which is used to introduce the steam of the working medium into the expansion chamber is provided at the upper portion inside the casing, the lubricant which is separated by the separator inside the casing and falls in a flowing state may be prohibited from being mixed with the steam of the working medium which is separated from the lubricant and is supplied to the steam inlet.

The power generation apparatus may further include a lubricant discharge path that directly or indirectly connects the inner space of the bearing holding portion to a steam outlet through which the steam of the working medium is discharged from the expansion chamber.

Further, a power generation system according to the present invention is a power generation system with any of the power generation apparatuses, wherein the casing of the power generation apparatus may include an outlet through which the fluid mixture formed by mixing the steam of the working medium having been used to rotationally drive the expander rotor and the lubricant having been used to lubricate the bearing is discharged from the inside of the casing, and wherein the power generation system includes: a circulation flow passage which connects the outlet to the inlet; a condenser which is provided in the circulation flow passage and condenses the steam of the working medium in the fluid mixture discharged from the outlet so as to produce a liquid working medium; a circulation pump which is provided at a position on the downstream side of the condenser in the circulation flow passage and pressure-feeds the fluid mixture containing the liquid working medium produced by the condenser; and an evaporator which is provided at a position on the downstream side of the circulation pump in the circulation flow passage and evaporates the liquid working medium in the fluid mixture pressure-fed by the circulation pump so as to produce a fluid mixture containing the steam of the working medium supplied to the inlet.

In the power generation system, since the power generation apparatus is provided, it is possible to obtain the same effect as that of the power generation apparatus capable of realizing a simple configuration and a compact size thereof and reducing the manufacturing cost thereof.

In the power generation system, a weight ratio of the lubricant with respect to a total amount of the working medium and the lubricant introduced into the power generation system may be equal to or larger than 5 wt % and equal to or smaller than 20 wt %.

According to this configuration, it is possible to obtain the steam of the working medium by the amount enough to rotationally drive the expander rotor while ensuring the lubricant amount necessary for reliably supplying the lubricant to the bearing accommodated in the inner space of the bearing holding portion. Specifically, in this configuration, since the weight ratio of the lubricant with respect to the total amount of the working medium and the lubricant introduced into the power generation system is equal to or larger than 5 wt %, it is possible to ensure the lubricant amount in which the lubricant may be reliably supplied to the bearing. Meanwhile, in the evaporator, the steam of the working medium is produced by evaporating the liquid working medium in the fluid mixture, but in a case where the content of the lubricant in the fluid mixture is large and the content of the working medium therein is small, the transfer of heat to the liquid working medium in the fluid mixture is disturbed by the lubricant in the fluid mixture, so that a sufficient amount of the working medium may not be evaporated by the evaporator. On the contrary, when the weight ratio of the lubricant with respect to the total amount of the working medium and the lubricant introduced into the power generation system is equal to or smaller than 20 wt % as in the configuration, it is possible to produce the steam of the working medium by a sufficient amount necessary for rotationally driving the expander rotor even when the transfer of heat with respect to the working medium in the fluid mixture by the evaporator is slightly disturbed by the lubricant in the fluid mixture.

As described above, according to the present invention, it is possible to provide the power generation apparatus and the power generation system capable of realizing a simple configuration and a compact size thereof and reducing manufacturing cost thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will be described by referring to the drawings.

First Embodiment

First, the configurations of a power generation apparatus2according to a first embodiment of the present invention and a power generation system using the same will be described by referring toFIGS. 1 to 4.

The power generation system according to the first embodiment is a power generation system that uses a Rankine cycle and is a binary-cycle power generation system that recovers power from low-temperature waste heat by using a working medium having a low boiling temperature. As the working medium, for example, a cooling medium such as R245fa (1,1,1,3,3-pentafluoropropane) is used.

Then, as illustrated inFIG. 1, the power generation system according to the first embodiment includes the power generation apparatus2, a circulation flow passage4, a condenser6, a circulation pump8, and an evaporator10.

The power generation apparatus2is used to generate power by using the steam of the working medium supplied to the power generation apparatus2. Although the power generation apparatus2will be described later, the power generation apparatus2includes a screw type expander14(hereinafter, simply referred to as an expander14) and a power generator16. Here, an expander rotor32to be described later of the expander14is rotationally driven by the expansion force of the steam of the working medium, and a power generator rotor38to be described later of the power generator16rotates with the rotation of the expander rotor32to thereby generate power. The steam of the working medium which is used to generate power in the power generation apparatus2is discharged from a fluid mixture outlet30eto be described later to the circulation flow passage4.

The circulation flow passage4causes an inlet30dand the outlet30efor a fluid mixture to be described later of the power generation apparatus2to be connected to each other (to communicate with each other). As will be described later, the lubricant and the steam of the working medium having been used to generate power are discharged from the fluid mixture outlet30eof the power generation apparatus2. The circulation flow passage4is a flow passage which circulates the fluid mixture so that the fluid mixture formed by mixing the steam of the working medium and the lubricant returns to the inlet30d.

The condenser6is provided in the circulation flow passage4. The condenser6condenses the steam of the working medium in the fluid mixture by cooling the fluid mixture discharged from the fluid mixture outlet30eof the power generation apparatus2to the circulation flow passage4and flowing into the condenser6. Accordingly, the steam is liquefied to produce a liquid working medium. The condenser6cools the fluid mixture by exchanging heat between the low-temperature cooling water and the fluid mixture. Since the steam of the working medium in the fluid mixture is liquefied, the fluid mixture discharged from the condenser6is obtained by mixing the liquid working medium with the liquid lubricant.

The circulation pump8is provided at a position on the downstream side of the condenser6in the circulation direction of the fluid mixture flowing through the circulation flow passage4in the circulation flow passage4. The circulation pump8is used to pressure-feed the fluid mixture containing the liquid working medium produced by the condenser6to the downstream side.

The evaporator10is provided at a position on the downstream side of the circulation pump8in the working medium circulation direction of the circulation flow passage4. The evaporator10is used to produce the steam of the working medium supplied to the inlet30dof the power generation apparatus2by evaporating the liquid working medium in the fluid mixture pressure-fed by the circulation pump8using the waste heat. Specifically, a fluid such as hot water or steam, heated by the exhaust heat from a factory or the like to a temperature higher than the boiling temperature of the working medium, is supplied from the outside to the evaporator10, and the fluid supplied from the outside exchanges heat with the fluid mixture inside the evaporator10, so that the fluid mixture is heated and hence the liquid working medium in the fluid mixture is evaporated. Accordingly, the fluid mixture discharged from the evaporator10and supplied to the inlet30dof the power generation apparatus2is obtained by mixing the steam of the working medium with the liquid lubricant.

With the above-described configuration, in the power generation system according to the first embodiment, a circulation circuit is formed in which the working medium is supplied from the evaporator10to the power generation apparatus2through the circulation flow passage4, the working medium discharged from the power generation apparatus2to the circulation flow passage4is supplied to the condenser6, and the working medium supplied to the condenser6returns to the evaporator10through the circulation pump8. Then, when the working medium circulates in the circulation circuit, electric energy is generated from the waste heat. In the power generation system, the working medium and the lubricant are introduced thereinto as described above, but the weight ratio of the lubricant with respect to the total amount of the working medium and the lubricant introduced into the power generation system is set to be equal to or larger than 5 wt % and equal to or smaller than 20 wt %.

Next, the configuration of the power generation apparatus2in the power generation system according to the first embodiment will be described in detail.

The power generation apparatus2includes a casing12, an expander14, a power generator16, plural first bearings18, plural second bearings20, a first bearing holding portion22, a second bearing holding portion24, a separation member26, a lubricant supply path28, and a lubricant discharge path29.

The casing12forms the outer surface of the power generation apparatus2, and is provided so as to extend in the horizontal direction. The casing12accommodates the expander14and the power generator16in the inner space thereof. Specifically, the casing12includes an expander casing30which accommodates the expander14therein and a power generator casing31which accommodates the power generator16therein. The expander casing30and the power generator casing31are fastened to each other so as to form the casing12.

The expander casing30includes an expander casing body30awhich is fastened to the power generator casing31and accommodates the expander rotor32to be described later of the expander14therein and an expander casing lid portion30bwhich is disposed on the opposite side to the power generator casing31with respect to the expander casing body30aand is fastened to the expander casing body30a.

The expander casing lid portion30bis substantially formed in a bottomed cylindrical shape and is disposed so that the axial direction thereof matches the extension direction (the horizontal direction) of the casing12. The expander casing lid portion30bincludes an end wall30cwhich forms one end of the casing12in the extension direction, and the center portion of the end wall30cis provided with the inlet30dwhich extends in the axial direction of the expander casing lid portion30band penetrates the end wall30c. The inlet30dcauses the fluid mixture formed by mixing the lubricant and the steam of the working medium to flow into the expander casing30. Specifically, one end of the circulation flow passage4is connected to the inlet30d. Then, as described above, the fluid mixture formed by mixing the liquid lubricant and the steam of the working medium produced by the evaporator10is supplied from the circulation flow passage4into the inlet, and the fluid mixture flows into the expander casing30through the inlet30d.

The expander casing body30ais provided with the fluid mixture outlet30ewhich is opened downward. The fluid mixture outlet30eis used to discharge the steam of the working medium having been used to rotationally drive the expander rotor32to be described later of the expander14and the lubricant having been supplied to the first bearing18and the second bearing20to lubricate the bearings18and20to the outside of the expander casing30.

Specifically, the steam of the working medium discharged from the expansion chamber through a steam outlet36bto be described later and the lubricant discharged to the steam outlet36bfrom the lubricant discharge path29as will be described later are discharged from the fluid mixture outlet30eto the outside. Further, a partition wall30gis provided inside the expander casing body30aso as to be located between the fluid mixture outlet30eand the space near the power generator16, and a communication port30his formed in the partition wall30gso as to cause the inside of the fluid mixture outlet30eto communicate with the space near the power generator16. As will be described later, the lubricant having been used to lubricate the second bearing20flows to the space near the power generator16and flows in the fluid mixture outlet30ethrough the communication port30hso as to be discharged to the outside. The opposite end to the end connected to the inlet30din the circulation flow passage4is connected to the fluid mixture outlet30e. Accordingly, the fluid mixture formed by mixing the liquid lubricant and the steam of the working medium is discharged from the inside of the expander casing30to the circulation flow passage4through the fluid mixture outlet30e. Further, the lower portion of the expander casing body30ais provided with a lubricant outlet30f(seeFIG. 3) which is used to discharge the lubricant accumulated in the lower space inside the expander casing30. The lubricant outlet30fis provided at a position near the inlet30dof the fluid mixture outlet30ein the expander casing body30a, and communicates with the space S in which the lubricant is accumulated inside the expander casing30.

The expander14includes a pair of expander rotors32(seeFIG. 3) each of which rotates about its axis32A in an engagement state. These expander rotors32are screw rotors. Each expander rotor32is provided with a first rotation shaft34awhich extends from the expander rotor32toward one side of the axial direction and a second rotation shaft34bwhich extends from the expander rotor32to the other side of the axial direction. The first rotation shaft34a, the second rotation shaft34b, and the expander rotors32are formed so as to have the same axial position. The pair of expander rotors32is provided inside the expander casing30, and is disposed so that the axial directions thereof match the extension direction of the casing12and the expander rotors are arranged in parallel in the right and left direction when viewed from the inlet30d.

Each expander rotor32has spiral teeth formed along the outer peripheral surface thereof, and the teeth of the pair of expander rotors32engage with each other so that an expansion chamber33is formed therebetween. The upper portion of the space inside the expander casing body30a, that is, the region located at the upper side of the pair of expander rotors32in the space inside the expander casing body30aand located in the vicinity of the ends of both expander rotors32near the inlet30dis provided with a steam inlet36awhich is used to introduce the steam of the working medium, into the expansion chamber. The steam inlet36acommunicates with the space inside the expander casing lid portion30b. Further, the region located at the lower side of the pair of expander rotors32inside the expander casing body30aand located from the vicinity of the ends opposite to (near the power generator16) the inlet30din both expander rotors32to the intermediate portions of both expander rotors32in the axial direction is provided with a steam outlet36bthrough which the steam of the working medium is discharged from the expansion chamber. The steam outlet36bcommunicates with the fluid mixture outlet30e. In the fluid mixture that flows into the expander casing30through the inlet30d, the steam of the working medium passes through the steam inlet36aso as to be introduced into the expansion chamber, and both expander rotors32are rotated about the axes thereof so as to expand the expansion chamber by the expansion force of the steam. In accordance with the rotation of both expander rotors32, the expansion chamber moves toward the power generator16, and communicates with the steam outlet36bso as to discharge the steam of the working medium inside the expansion chamber to the fluid mixture outlet30ethrough the steam outlet36b.

The power generator16includes the power generator rotor38which is connected to one of the expander rotor32and a stator40which is disposed at the outside of the power generator rotor38in the rotation radial direction so as to surround the power generator rotor38. The power generator rotor38is disposed so as to be coaxial with one expander rotor32and is connected to one expander rotor32. Specifically, the power generator rotor38is connected to one expander rotor32through the second rotation shaft34b. With this configuration, the power generator rotor38rotates along with the expander rotor32in accordance with the rotation of one expander rotor32. Then, when the power generator rotor38rotates, power is generated between the power generator rotor38and the stator40.

Plural first bearings18are disposed in a space inside the expander casing lid portion30b, and plural second bearings20are disposed in a space inside the expander casing body30a. The first bearings18are used to axially support the first rotation shaft34a, and the second bearings20are used to axially support the second rotation shaft34b. Specifically, as illustrated inFIG. 2, in the plural first bearings18, the first bearing18which axially supports the first rotation shaft34aof one expander rotor32supports the first rotation shaft34aso that one expander rotor32and the power generator rotor38are rotatable about the axes thereof. In the plural first bearings18, the first bearing18which axially supports the first rotation shaft34aof the other expander rotor32supports the first rotation shaft34aso that the other expander rotor32is rotatable about the axis thereof. Further, in the plural second bearings20, the second bearing20which axially supports the second rotation shaft34bof one expander rotor32supports the second rotation shaft34bso that one expander rotor32and the power generator rotor38are rotatable about the axes thereof. In the plural second bearings20, the second bearing20which axially supports the second rotation shaft34bof the other expander rotor32supports the second rotation shaft34bso that the other expander rotor32is rotatable about the axis thereof.

The first bearing holding portion22accommodates the plural first bearings18therein so as to hold the first bearings18. Specifically, the first bearing holding portion22is disposed in a space inside the expander casing lid portion30b, and extends to the inside of the expander casing body30aso as to be fastened and fixed to the portion facing the expander casing lid portion30b. The first bearing holding portion22has an inner space22A which accommodates the first bearing18supporting the first rotation shaft34aof one expander rotor32and the first bearing18supporting the first rotation shaft34aof the other expander rotor32while the first bearings are equally arranged and both ends thereof are opened. Into the inner space of the first bearing holding portion22, the pair of first rotation shafts34aof the pair of expander rotors32is inserted while being supported by the respectively corresponding first bearings18.

The second bearing holding portion24accommodates the plural second bearings20therein and supports the second bearings20. Specifically, the second bearing holding portion24is disposed in a space inside the expander casing body30a, and is coupled to the expander casing body30a. The second bearing holding portion24has an inner space24A which accommodates the second bearing20supporting the second rotation shaft34bof one expander rotor32and the second bearing20supporting the second rotation shaft34bof the other expander rotor32while the second bearings are equally arranged and both ends thereof are opened. Into the inner space of the second bearing holding portion24, the pair of second rotation shafts34bof the pair of expander rotors32is inserted while being supported by the respectively corresponding second bearings20. Further, in the inner space of the second bearing holding portion24, a second shaft sealing chamber24ais formed between the second bearing20and the end of the expander rotor32near the power generator16. The second shaft sealing chamber24ais provided so as to prevent the leakage of the steam from the expansion chamber to the power generator16.

The separation member26is disposed in a space inside the expander casing lid portion30b. The separation member26is used to separate the lubricant from the fluid mixture which flows into the expander casing30(into the expander casing lid portion30b). Specifically, the separation member26is a plate-shaped member that is disposed to face the inlet30dso that the fluid mixture flowing into the expander casing30through the inlet30druns into the plate-shaped member. The separation member26is attached to the end of the first bearing holding portion22near the inlet30dso as to block the opening.

The separation member26includes a facing surface26awhich is disposed to face the inlet30dso that the fluid mixture flowing into the expander casing30through the inlet30druns into the facing surface. The facing surface26ais disposed so as to be perpendicular to the inflow direction of the steam of the fluid mixture flowing into the expander casing30through the inlet30d, that is, the extension direction of the axis of the inlet30d. The fluid mixture flowing into the expander casing30through the inlet30dcollides with the facing surface26aof the separation member26, and hence the lubricant in the fluid mixture falls along the facing surface26adue to the own weight thereof. The lubricant which falls in a flowing state is accumulated in the lower space of the inner space in the expander casing30. Further, the fluid mixture from which the lubricant is separated, that is, the steam of the working medium passes through the upper space of the first bearing holding portion22in the space inside the expander casing30(the expander casing lid portion30b), flows to the steam inlet36a, and is introduced into the expansion chamber from the steam inlet36a.

The lubricant supply path28is used for the connection (communication) of the lower space in which the lubricant is accumulated in the space inside the expander casing30, the inner space of the first bearing holding portion22, and the second shaft sealing chamber24ainside the second bearing holding portion24. The lubricant supply path28is used to circulate the lubricant so that the lubricant accumulated in the lower space inside the expander casing30is supplied to the inner space of the first bearing holding portion22and the second shaft sealing chamber24ainside the second bearing holding portion24.

The external pipe28ais a pipe which is provided at the outside of the casing12. One end of the external pipe28ais connected to the lubricant outlet30fprovided in the expander casing body30aand the other end of the external pipe28ais connected to the inner flow passage28b.

The inner flow passage28bincludes an introduction path28cand a first supply path28dand a second supply path28ewhich are branched from the introduction path28c. The other end of the external pipe28ais connected to the opening end of the introduction path28c. Furthermore, the introduction path28cand a part of the first supply path28dand the second supply path28emay be provided inside the wall portion of the expander casing30. The first supply path28dis connected to a first shaft sealing chamber22aadjacent to the first bearing18in the inner space of the first bearing holding portion22. Further, the second supply path28eis connected to the second shaft sealing chamber24a.

The lubricant discharge path29is provided inside the expander casing30so as to cause the inner space of the first bearing holding portion22to be connected to (communicate with) the portion (specifically, the portion deviated to the first bearing holding portion22by one tooth in the expander rotor32in relation to the portion facing the steam outlet36bin the expander rotor32) near the steam outlet36bin the expansion chamber. The lubricant discharge path29causes the lubricant to flow from the inner space of the first bearing holding portion22to the steam outlet36b. Specifically, one end of the lubricant discharge path29is connected to a position opposite to the expander rotor32with respect to the portion accommodating the first bearing18in the inner space of the first bearing holding portion22, and the other end of the lubricant discharge path29is connected to the expansion chamber near the steam outlet36b. The lubricant discharge path29causes the lubricant, having been supplied to the first bearing18to lubricate the first bearing18, to flow to the steam outlet36b.

Further, the pressure of the inner space of the first bearing holding portion22and the pressure of the inner space of the second bearing holding portion24are set to be lower than the pressure of the lower space where the lubricant is accumulated inside the expander casing30.

Specifically, since the lower space in which the lubricant is accumulated inside the expander casing30is a part of the inner space of the expander casing30into which the fluid mixture containing the steam of the working medium flows, the pressure of the space is equal to the pressure of the inner space of the expander casing30and is a comparatively high pressure.

Meanwhile, the first bearing holding portion22is set to a pressure close to the pressure inside the expansion chamber in the vicinity of the steam inlet36a. Specifically, since the pressure inside the expansion chamber decreases as the steam of the working medium expands from the steam inlet36atoward the steam outlet36b, the pressure inside the expansion chamber in the vicinity of the steam inlet36ais higher than the pressure inside the expansion chamber in the vicinity of the steam outlet36b. However, since the inner space of the first bearing holding portion22is adjacent to the expansion chamber at the side of the steam inlet36aand communicates with the steam outlet36bthrough the lubricant discharge path29, the pressure of the inner space of the first bearing holding portion22becomes an intermediate pressure between the pressure inside the expansion chamber in the vicinity of the steam inlet36aand the pressure in the steam outlet36blower than the above-described pressure. Thus, the pressure of the inner space of the first bearing holding portion22becomes the pressure of the steam of the working medium introduced into the steam inlet36a, that is, the pressure is lower than the pressure of the inner space of the expander casing30. Furthermore, the pressure of the portion in the vicinity of the steam outlet36bconnected with the lubricant discharge path29is lower than the pressure of the inner space of the first bearing holding portion22and is slightly higher than the pressure of the steam outlet36b.

Further, the pressure of the second bearing holding portion24becomes the pressure close to the pressure inside the expansion chamber in the vicinity of the steam outlet36b. Specifically, since the inner space of the second bearing holding portion24is adjacent to the expansion chamber at the side of the steam outlet36band communicates with the fluid mixture outlet30ethrough the space near the power generator16and the communication port30h, the pressure of the inner space of the second bearing holding portion24becomes an intermediate pressure between the pressure inside the expansion chamber in the vicinity of the steam outlet36band the pressure of the fluid mixture outlet30elower than the above-described pressure. Thus, the pressure of the inner space of the second bearing holding portion24becomes the pressure of the steam of the working medium introduced into the steam inlet36a, that is, the pressure fairly lower than the pressure of the inner space of the expander casing30.

From the description above, each of the pressures of the inner spaces of the first and second bearing holding portions22and24becomes a pressure lower than the pressure of the lower space in which the lubricant is accumulated inside the expander casing30, and a difference in pressure occurs between the lower space in which the lubricant is accumulated inside the expander casing30and the inner spaces of the first and second bearing holding portions22and24. By the difference in pressure, the lubricant accumulated in the lower space inside the expander casing30is discharged through the lubricant outlet30f, flows into the introduction path28cof the inner flow passage28bthrough the external pipe28aof the lubricant supply path28, passes from the introduction path28cto the first supply path28dso as to flow into the inner space of the first bearing holding portion22, and also passes from the introduction path28cto the second supply path28eso as to flow into the second shaft sealing chamber24ainside the second bearing holding portion24. The lubricant which flows into the inner space of the first bearing holding portion22is supplied to the first bearing18while moving inside the inner space toward the side opposite to the expander rotor32by the difference in pressure inside the inner space and lubricates the first bearing18. Further, the lubricant which flows into the second shaft sealing chamber24aseals the periphery of the second rotation shaft34binside the second shaft sealing chamber24aand suppresses the leakage of the steam of the working medium from the expansion chamber toward the power generator16. Since the pressure of the power generator16is lower than that of the second shaft sealing chamber24a, the lubricant is supplied from the second shaft sealing chamber24ato the second bearing20so as to lubricate the second bearing20.

Then, since the pressure inside the steam outlet36bis lower than the pressure of the inner space of the first bearing holding portion22, the lubricant having been used to lubricate the first bearing18passes from the inner space of the first bearing holding portion22to the lubricant discharge path29by the difference in pressure so as to be directed to the portion in the vicinity of the steam outlet36bof the expansion chamber. At this time, since the pressure of the lubricant is slightly higher than the pressure of the steam outlet36b, the driving of the expander rotor32is assisted. Accordingly, the power generation efficiency may be further improved. Then, the lubricant is discharged from the expansion chamber to the steam outlet36band is discharged from the steam outlet36bto the fluid mixture outlet30e. Further, since the pressure of the inner space of the power generator casing31is lower than the pressure of the inner space of the second bearing holding portion24and the pressure inside the fluid mixture outlet30eis fairly lower than the pressure of the inner space of the power generator casing31, the lubricant having been used to lubricate the second bearing20flows from the inner space of the second bearing holding portion24to the inner space of the power generator casing31and is discharged from the inner space of the power generator casing31to the fluid mixture outlet30ethrough the communication port30h. Then, the lubricant which is discharged to the fluid mixture outlet30eforms the fluid mixture along with the steam of the working medium discharged from the expansion chamber to the fluid mixture outlet30ethrough the steam outlet36b, and is discharged to the circulation flow passage4.

As described above, in the first embodiment, the lubricant is separated from the fluid mixture flowing into the expander casing30by the separation member26and the separated lubricant is accumulated in the lower space inside the expander casing30. That is, in the first embodiment, since the lubricant may be separated inside the expander casing30, there is no need to separately provide a lubricant separation tank at the outside. For this reason, in the first embodiment, the power generation apparatus2and the power generation system may have a simple configuration and a compact size and the manufacturing cost of the power generation apparatus2and the power generation system may be reduced compared to the power generation apparatus and the power generation system of the related art with the lubricant separation tank.

Further, in the first embodiment, as described above, the lubricant which is separated from the fluid mixture inside the expander casing30and is accumulated in the lower space inside the expander casing30automatically flows to the inner space of the first bearing holding portion22through the lubricant supply path28so as to be supplied to the first bearing18by a difference in pressure between the space and the inner space of the first bearing holding portion22. Also, the lubricant automatically flows to the inner space of the second bearing holding portion24(the second shaft sealing chamber24a) through the lubricant supply path28so as to be supplied to the second bearing20by a difference in pressure between the above-described space and the inner space of the second bearing holding portion24. For this reason, in the power generation apparatus2and the power generation system according to the first embodiment, there is no need to separately provide the pump for pressure-feeding the separated lubricant as in the power generation apparatus and the power generation system of the related art. Even for this reason, in the first embodiment, the power generation apparatus2and the power generation system may have a simple configuration and a compact size and the manufacturing cost of the power generation apparatus2and the power generation system may be reduced.

Further, in the first embodiment, since the steam inlet36awhich introduces the steam of the working medium into the expansion chamber is provided at the upper portion inside the expander casing30, it is possible to prohibit the lubricant separated by the separation member26and falling in a flowing state in the space inside the expander casing30from being mixed with the steam of the working medium separated from the lubricant and supplied to the steam inlet36a.

Further, in the first embodiment, since the weight ratio of the lubricant with respect to the total amount of the lubricant and the working medium introduced into the power generation system is equal to or larger than 5 wt % and equal to or smaller than 20 wt %, it is possible to obtain the steam of the working medium by the amount enough to rotationally drive the expander rotor32while ensuring the lubricant amount necessary to reliably supply the lubricant to the first bearing18and the second bearing20.

Specifically, in the first embodiment, since the weight ratio of the lubricant with respect to the total amount of the lubricant and the working medium introduced into the power generation system is equal to or larger than 5 wt %, it is possible to ensure the lubricant amount enough to reliably supply the lubricant to the first bearing18and the second bearing20. Meanwhile, in the evaporator10, the steam of the working medium is produced by evaporating the liquid working medium in the fluid mixture, but in a case where the content of the lubricant in the fluid mixture is large and the content of the working medium is small, the transfer of heat to the liquid working medium in the fluid mixture is disturbed by the lubricant in the fluid mixture, so that a sufficient amount of the working medium may not be evaporated by the evaporator10. On the contrary, when the weight ratio of the lubricant with respect to the total amount of the lubricant and the working medium introduced into the power generation system is equal to or smaller than 20 wt % as in the first embodiment, it is possible to produce the steam of the working medium by a sufficient amount necessary to rotationally drive the expander rotor32even when the transfer of heat with respect to the working medium in the fluid mixture in the evaporator10is slightly disturbed by the lubricant in the fluid mixture. Furthermore, the weight ratio (equal to or larger than 5 wt % and equal to or smaller than 20 wt %) of the lubricant with respect to the total amount of the working medium and the lubricant is a value which is set by verifying the above-described effect in terms of the experiments repeated by the present inventor.

Second Embodiment

Next, referring toFIG. 5, the configurations of a power generation apparatus and a power generation system according to a second embodiment of the present invention will be described.

In the second embodiment, a separation member42provided inside the expander casing30is formed by a demister. Specifically, the demister is formed by overlapping plural mesh members such as metallic meshes, and has a function of capturing a mist-shaped liquid contained in the air stream. In the second embodiment, the separation member42that is formed by the demister is attached to a surface near the inlet30din an end plate44that blocks the opening of the end near the inlet30din the first bearing holding portion22. Furthermore, the configuration of the end plate44is the same as the configuration of the separation member26of the first embodiment.

In the second embodiment, the fluid mixture flowing into the expander casing30through the inlet30druns into the separation member42formed by the demister, so that a droplet-shaped or a mist-shaped lubricant contained in the fluid mixture is captured by the separation member42. Accordingly, the lubricant is separated from the fluid mixture flowing into the expander casing30. The lubricant captured by the separation member42falls while flowing downward and is accumulated in the lower space inside the expander casing30.

The configurations other than the above-described configurations of the power generation apparatus and the power generation system according to the second embodiment are the same as the configurations of the power generation apparatus2and the power generation system according to the first embodiment.

In the second embodiment, since the separation member42is formed by the demister, the lubricant in the fluid mixture flowing into the expander casing30and colliding with the separation member42may be satisfactorily captured by the separation member42. For this reason, it is possible to improve the efficiency of separating the lubricant from the fluid mixture flowing into the expander casing30.

The effects other than the above-described effect obtained by the power generation apparatus and the power generation system of the second embodiment are the same as those of the power generation apparatus2and the power generation system of the first embodiment.

Third Embodiment

Next, referring toFIGS. 6 and 7, the configurations of a power generation apparatus and a power generation system according to a third embodiment of the present invention will be described.

In the third embodiment, the separation member26provided inside the expander casing30is a plate-shaped member, and the facing surface26aof the separation member26with respect to the inlet30dis formed as an inclined surface which forms a swirl flow in the fluid mixture flowing into the expander casing30.

Specifically, in the third embodiment, the separation member26is commonly used as the end plate that blocks the opening of the end near the inlet30din the first bearing holding portion22as in the case of the first embodiment. As illustrated inFIG. 7, the facing surface26awhich is disposed to face the inlet30din the separation member26is inclined in a direction moving away from the inlet30d(toward the expander14) as it goes from the left side to the right side in the facing surface26a. With this configuration, the fluid mixture flowing into the expander casing30through the inlet30dcollides with the facing surface26aof the separation member26and forms the swirl flow about the vertical axis while changing a direction along the inclination of the facing surface26a.

The configurations other than the above-described configurations of the power generation apparatus and the power generation system according to the third embodiment are the same as the configurations of the power generation apparatus2and the power generation system according to the first embodiment.

In the third embodiment, since the fluid mixture flowing into the expander casing30forms the swirl flow as described above, the separation of the lubricant from the fluid mixture is promoted. For this reason, it is possible to improve the efficiency of separating the lubricant from the fluid mixture flowing into the expander casing30.

The effects other than the above-described effect obtained by the power generation apparatus and the power generation system of the third embodiment are the same as those of the power generation apparatus2and the power generation system of the first embodiment.

Furthermore, it should be considered that the embodiments disclosed herein are merely examples and do not limit the present invention. The scope of the present invention is illustrated by the scope of claims instead of the description of the above-described embodiments and includes the meaning equivalent to the scope of claims and all modifications within the scope.

For example, in the second embodiment, the entire separation member42is formed by the demister, but only a part of the separation member may be formed by the demister.

Further, in the third embodiment, the facing surface26aof the separation member26is inclined in a direction moving away from the inlet30das it goes from the left side to the right side in the facing surface26a, but the inclination direction of the facing surface26aof the separation member26is not limited to the direction. For example, as in a modified example of the third embodiment illustrated inFIG. 8, the facing surface26aof the separation member26may be inclined in a direction moving away from the inlet30das it goes from the upside to the downside. According to the modified example, the fluid mixture flowing into the expander casing30through the inlet30dcollides with the facing surface26aof the separation member26so that the direction is changed to the downside and the fluid mixture is guided to the lower space inside the expander casing30. Accordingly, the lubricant in the fluid mixture guided to the lower space is accumulated in the lower space, and the steam of the working medium in the fluid mixture flows to the upper space of the first bearing holding portion22through both left and right spaces of the first bearing holding portion22inside the expander casing30so as to be supplied to the steam inlet36a. Even in the configuration of the modified example, it is possible to improve the efficiency of separating the lubricant from the fluid mixture flowing into the expander casing30. In the above-described embodiments, the lubricant discharge path29may be directly connected to the steam outlet30e.