JP4286062B2 - Power generation apparatus and power generation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power generation apparatus and a power generation method for recovering relatively low-temperature exhaust heat and the like and converting the heat energy into electric power, and more particularly to cooling using a working medium of a turbine generator or its peripheral equipment.
[0002]
[Prior art]
Attempts have been made to effectively recover relatively low-temperature waste heat such as exhaust gas at about 200 to 400 ° C. or exhaust water at 100 to 150 ° C. as generated power. Such low-temperature waste heat recovery can be realized as a power generator for a closed system using a so-called Rankine cycle. For the compactness of the device, the working medium is not water but a low boiling point working medium. Is used (for example, refer to Patent Document 1).
[0003]
In such small-scale applications, that is, facilities with a power generation output of about 10 kW or less, a turbine generator having a higher speed and a smaller size is required from the viewpoint of reducing the installation space and shortening the recovery period of the introduction cost. Yes. Patent document 2 is disclosing the steam turbine generator which provided the generator in the same axis | shaft as an axial flow type multistage steam turbine.
[0004]
[Patent Document 1]
JP 2000-110514 A [Patent Document 2]
JP-T-2001-525512 Publication
[Problems to be solved by the invention]
In such a closed system power generator, when the turbine generator is rotated at a high speed of, for example, several tens of thousands of revolutions per minute, it is very small and compact. And although a heat generating part is generally cooled by coolant, such as air or water, from the generator outer surface, there exists a problem that a surface area will reduce if it becomes too compact, and cooling will become difficult. The lubricating oil supplied to the turbine generator bearing also generates heat when the bearing is lubricated and cooled, and the temperature rises. Therefore, cooling is necessary. The cooler used for cooling the lubricating oil also uses air or water as a cooling medium, but there is a problem that it is difficult to secure the passage.
[0006]
The present invention has been made in view of the above-described circumstances, and can efficiently cool a heat generating portion of a small-sized and compact turbine generator and its peripheral devices, thereby reducing the size and compactness of the entire system. It is an object of the present invention to provide a power generation apparatus and a power generation method that can be achieved.
[0007]
[Means for Solving the Problems]
The power generation device of the present invention includes a steam generator that recovers exhaust heat and generates high-pressure steam as a working medium, an expander that drives the generator by expanding the high-pressure steam, and after driving the expander In the power generation apparatus comprising: a condenser that cools the steam of the working medium with a cooling medium; and a pump that pressurizes the condensate of the working medium condensed by the condenser and sends the condensed liquid to the steam generator. A part of the generator is guided to a cooler of the generator, and the generator is directly cooled by utilizing the latent heat of vaporization of the working medium, and then the working medium is returned to the condenser. It is a feature.
[0008]
According to the present invention described above, by using a working medium having a boiling point lower than that of water as a cooling medium, the piping system of the system can be made small in diameter, and the heat generating portion can be cooled with high cooling efficiency. For this reason, the compactness of the whole apparatus or the whole system can be achieved.
[0009]
That is, for example, a turbine generator has a high rotational speed of several tens of thousands of revolutions per minute and a compact and compact structure can be obtained, but the external dimensions of the turbine generator become small and cooling of air etc. is almost impossible. . However, the condensate of the working medium is guided to a generator cooler provided on the outer surface of the turbine generator, and cooled using the sensible heat or latent heat of evaporation of the working medium, so that the density of the working medium is higher than that of air. Since it is several orders of magnitude larger, efficient cooling becomes possible. Further, when latent heat is used, the amount can be reduced.
[0010]
Also, for example, the lubricating oil that lubricates the bearings of each part of the turbine generator is not cooled by air or cooling water, but is cooled by condensate of the working medium, so that the density of the working medium is several orders of magnitude greater than that of air. Therefore, efficient cooling becomes possible. Similarly, when using latent heat, the amount can be reduced. The working medium whose temperature has risen or the working medium which has evaporated can be led to a condenser and can be easily cooled and condensed.
[0011]
Further, when the load on the bearing of the turbine generator is small, lubrication and cooling may be performed by directly using the condensate of the working medium instead of special oil such as lubricating oil. In this case, the working medium used for cooling the bearing can also be used for cooling the turbine generator and the lubricating oil. However, since the bearing is preferably lubricated in a condensed liquid state, the bearing is preferably lubricated and cooled first, and then the turbine generator cooler and the like are preferably cooled.
[0012]
When cooling water is used in a turbine generator cooler or a lubricating oil circulation system cooler, there is a problem that scale is attached and maintenance is required. However, using the working medium as the cooling medium as described above eliminates the problem of scale adhesion.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in each figure, the same code | symbol is attached | subjected to the member or element which has the same function, and the duplicate description is abbreviate | omitted. In this embodiment, an example in which a turbine is used as an expander will be described. However, the present invention can be similarly applied to other types of expanders such as a screw expander and a scroll expander.
[0014]
FIG. 1 shows an outline of a power generator of the present invention. The power generation apparatus of this closed system is a power generation apparatus using a so-called Rankine cycle, a steam generator 11 that recovers waste heat and generates high-pressure steam as a working medium, and a generator 22 by expanding the high-pressure steam. A turbine generator 13 for driving the turbine connected to the condenser, a condenser 14 for cooling the low-pressure steam after driving the turbine with a cooling medium to form a condensate, and a working medium condensed by the condenser And a liquid feed pump 15 for pressurizing the condensate and feeding it to the steam generator 11.
[0015]
Here, as the working medium, HFC123 or trifluoroethanol (CF ₃ CH ₂ OH) having a boiling point of around 40 ° C. is used. By using a relatively low temperature heat source such as a relatively low temperature exhaust gas of about 200 to 400 ° C. or exhaust water having a temperature of 100 to 150 ° C., the thermal energy is first converted into high pressure steam as a working medium. The turbine generator 13 rotates the turbine directly connected to the generator to generate power.
[0016]
In this power generator, the working medium is fed into the steam generator 11 by the liquid feed pump 15. The working medium receives heat energy such as exhaust heat from the steam generator 11 and evaporates at a boiling point to become high-pressure steam. This steam is sent to a turbine generator 13 in which the turbine and the generator are directly connected. Here, the turbine is driven by the expansion of the high-pressure steam to rotate the generator to generate power. The discharged low-pressure steam is cooled by the condenser 14 with a cooling medium such as cooling water, condensed, further subcooled by the subcooler as necessary, and sucked by the liquid feed pump 15 to make a round of the closed system. To do.
[0017]
In this power generation system, a working medium is used for cooling the stator portion of the generator 22. That is, a part of the condensate of the working medium pressurized by the liquid feed pump 15 is introduced into the cooling jacket of the generator 22 (see reference numeral 38 in FIG. 2), and the stator portion of the generator is directly cooled by the working medium. The cooled working medium is returned to the condenser 14, cooled by the cooling medium, and returned to the condensate. Here, since the density of the working medium is several orders of magnitude higher than that of air, efficient cooling of the stator section that generates heat at high density is possible by cooling using the sensible heat or latent heat of evaporation of the working medium. become.
[0018]
A part of the condensate pressurized by the liquid feed pump 15 is used for cooling the lubricating oil in the lubricating oil tank 18. In the turbine generator 13, the main shaft is supported by bearings 35, 36, and 37. Then, the lubricating oil stored in the lubricating oil tank 18 is pressurized and supplied to each bearing by the lubricating oil supply pump 17. The lubricating oil that has lubricated and cooled the bearings 35, 36, and 37 is returned to the tank 18 while being heated and heated. The lubricating oil tank 18 includes a cooler 18a, and the lubricating oil whose temperature has been raised is cooled by supplying a working medium to the cooler. Also here, since the working medium has a density several orders of magnitude higher than that of air, efficient cooling is possible by utilizing the sensible heat or latent heat of vaporization of the working medium. The working medium having cooled the lubricating oil by the cooler 18 a is returned to the condenser 14, cooled and condensed again to become a condensed liquid, and circulated through the closed loop again by the liquid feed pump 15.
[0019]
In a bearing with a light load, the condensate of the working medium can be used directly for lubrication and cooling. Therefore, the condensate pressurized by the condensate feed pump 15 can be introduced directly into the bearing 36 having a light load. In such a case, the working medium that has lubricated and cooled the bearing 36 is expanded together with the high-pressure steam of the working medium to drive the turbine, contributes to power generation, and then returns to the condenser 14 as low-pressure steam. By directly lubricating and cooling the bearing with the working medium in this way, the burden on the lubricating oil supply pump 17 can be reduced, and the system as a whole can be made efficient.
[0020]
The cooling using the working medium may be performed by cooling the stator section where the heat generated by the turbine generator is large and the lubricating oil cooler in parallel. Both may be cooled.
[0021]
FIG. 2 shows a configuration example of a gas turbine generator according to an embodiment of the present invention, which is suitable for generating power by effectively recovering and using low-temperature waste heat energy. In this gas turbine generator, the turbine 21 is rotationally driven by expanding high-pressure steam, and the generator 22 directly connected to the turbine is rotationally driven to generate electric power. That is, the turbine generator includes an axial flow turbine 21 and a DC brushless generator 22, and the turbine rotor 23 and the generator rotor 24 are integrally fixed to a single shaft main shaft 25. This turbine generator is installed vertically, and the turbine rotor 23 is fixed to the upper part of the main shaft 25, and the generator rotor 24 is fixed to the lower part of the main shaft 25. However, it goes without saying that this turbine generator may be used as a horizontal installation.
[0022]
A plurality of rotor blades 27 are arranged and fixed in the axial direction on the turbine rotor 23, and a turbine casing 29 including a plurality of stationary blades 28 is disposed outside the rotor blades 27. Further, an outer cylinder 31 is provided outside the turbine casing 29, and a flow path 33b is formed between the turbine casing 29 and the outer cylinder 31 through which low-pressure steam of a working medium after the turbine is rotationally driven. A suction pipe 32 is arranged on the suction side of the turbine, and constitutes a gas flow path 33a of a working medium made of high-pressure steam connected to the suction side of the turbine. That is, the suction pipe 32 is accommodated in the turbine outer cylinder 31 or the turbine discharge pipe 34 connected to the outer cylinder, and the turbine suction pipe 32 and the turbine discharge pipe 34 form a double pipe structure. . Therefore, the high-pressure steam of the working medium that has flowed into the turbine 21 from the turbine suction pipe 32 inside the double pipe rotates the turbine rotor 23, and the steam of the working medium that has become low pressure is the outer periphery of the double pipe. It flows out through the flow path 33 b inside the discharge pipe 34.
[0023]
The generator rotor 24 is constituted by a permanent magnet type rotor in which permanent magnets are alternately arranged along the circumferential surface thereof, and a generator stator 26 is arranged around the generator rotor 24 through a slight clearance. Yes. In addition, a cooling jacket 38 is provided on the outer peripheral portion of the generator stator 26, and a working medium is supplied as a coolant to efficiently cool the generator that generates heat, particularly the generator stator 26. By using the working medium as the cooling liquid, it is possible to prevent the problem of adhesion of scale such as cooling water.
[0024]
The generator 22 is a DC brushless type AC generator, and the generated output is taken out from a winding portion provided in the generator stator 26 via a power line 40. The power line 40 is connected to a frequency converter (not shown) via a connector 43, and the power generation output of the AC generator 22 is converted into a predetermined frequency / voltage (for example, 60 Hz / 200V) by the frequency converter, and power is supplied to the load device. Supplied.
[0025]
A sensor 41 for detecting the rotational speed is provided at the end of the main shaft on the counter-turbine side of the generator rotor 24, and the rotational speed of the main shaft 25 is detected. The output of the sensor 41 is transmitted to the outside through the connector 43 by the signal line 42. The rotational speed of the turbine generator can be adjusted by adjusting the supply amount or supply pressure of the high-pressure steam of the working medium supplied to the turbine. That is, in the range below the allowable rotational speed at which the turbine generator can be operated safely, when the amount of power generation is increased, the amount of high-pressure steam of the working medium to be supplied is increased, and when the amount of power generation is decreased, the high-pressure steam of the working medium is decreased. The amount of power generation can be controlled by reducing the amount. At this time, the above adjustment is possible by detecting the rotation speed by the rotation speed sensor 41 and controlling the supply amount or supply pressure of the high-pressure steam to the turbine by the electric valve 16 (see FIG. 1) or the like. The supply amount of the working medium can also be performed by controlling the speed of the working medium feeding pump 15 (see FIG. 1).
[0026]
The main shaft 25 is supported by a main bearing 35 at a substantially central portion between the turbine 21 and the generator 22. The main bearing 35 is formed by arranging angular ball bearings 35 a and 35 b in parallel, and is arranged at a substantially center of gravity position of the entire rotating body including the turbine rotor 23 and the generator rotor 24. A turbine side auxiliary bearing 36 formed of a single row angular ball bearing is provided on the main shaft end portion of the turbine rotor 23 on the counter-generator side, that is, on the high pressure side of the turbine 21. Similarly, a generator side auxiliary bearing 37 composed of a single row angular ball bearing is disposed at the end of the main shaft on the counter turbine side of the generator rotor 24.
[0027]
Thus, in this turbine generator, the main shaft 25 is supported by the central main bearing 35 and auxiliary bearings 36 and 37 provided at the turbine side shaft end and the generator side shaft end, respectively. That is, in this turbine generator, the main bearing 35 is arranged near the center of gravity of the entire rotating body, and the main load as a bearing is shared by this, and small-diameter auxiliary bearings 36 and 37 are supplementarily provided at both ends of the main shaft. It is arranged for the purpose of steadying. Therefore, only one high-speed and large-load main bearing can be provided, and a small-sized auxiliary bearing for swinging can be employed. For this reason, this turbine generator can be manufactured more compactly and at low cost while ensuring the reliability of the generator. Further, the auxiliary bearing 36 provided at the turbine shaft end must be disposed on the inner peripheral side of the high-pressure steam passage 33a of the working medium, but this can be directly cooled using the condensate of the working medium. it can.
[0028]
Lubricating oil is supplied to the main bearing 35, the turbine side auxiliary bearing 36, and the generator side auxiliary bearing 37 for lubrication and cooling. The lubricating oil discharged from the lubricating oil supply pump 17 (see FIG. 1) flows to the main bearing 35 and the auxiliary bearing 36 via the lubricating oil supply pipes 46a and 47a and is supplied in parallel to recover the lubricating oil. It returns to the lubricating oil supply pump via the pipes 46b and 47b. Lubricating oil is also supplied to the auxiliary bearing 37 sequentially or in parallel. At this time, an oil cooler and a dust filter are provided in each part as necessary. The lubricating oil heated by lubricating and cooling these bearings is returned to the tank 18 (see FIG. 1) and cooled by the working medium.
[0029]
In addition, a part of the lubricating oil supplied to each bearing is mixed in the working medium of the turbine, and a part of the lubricating oil also enters the generator, so that an oil separation device (not shown) that separates the lubricating oil from the working medium Is provided separately. The separated lubricating oil is returned to the lubricating oil circulation pump, and the separated working medium is condensed and returned to the working medium feed pump. Since the turbine generator has a vertical axis configuration in which the turbine 21 is at the top and the generator 22 is at the bottom, the preferred mounting position of the oil separator for separating the oil collected by natural flow is the power generation. This is the lower end of the machine 22.
[0030]
In addition, the said embodiment described the one aspect | mode of the Example of this invention, Of course, a various deformation | transformation Example is possible, without deviating from the meaning of this invention.
[0031]
【The invention's effect】
In the closed system power generation device, the turbine generator and peripheral equipment are cooled using the condensate of the working medium condensed in the condenser, so it is efficient to use the large latent heat of vaporization of the working medium. Can cool. In addition, scale adhesion in the case of cooling water is prevented, and cooling with good maintainability can be performed.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a power generator according to an embodiment of the present invention.
2 is a cross-sectional view showing a configuration example of the turbine generator of FIG. 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Steam generator 13 Turbine generator 14 Condenser 15 Liquid supply pump 16 of working medium Electric valve 17 Lubricating oil supply pump 18 Lubricating oil tank 18a Cooler 22 DC brushless generator 23 Turbine rotor 24 Generator rotor 25 Main shaft 26 Generator Stator 27 Rotor blade 28 Stator blade 29 Turbine casing 31 Outer trunk 32 Turbine suction pipe 33 Gas flow path 34 Turbine discharge pipe 35 Main bearing 36 Turbine side auxiliary bearing 37 Generator side auxiliary bearing 38 Cooling jacket 40 Power line 41 Rotational speed sensor 42 Signal line 43 Connector 46a, 46b, 47a, 47b Lubricating oil piping

Claims (4)

A steam generator that recovers exhaust heat and generates high-pressure steam as a working medium, an expander that drives a generator by expanding the high-pressure steam, and a steam after driving the expander in a cooling medium In a power generator comprising: a condenser to be cooled; and a pump that pressurizes the condensate of the working medium condensed in the condenser and feeds it to the steam generator.
A part of the condensate of the working medium is led to a cooler of the generator, and the cooler directly cools the generator using the latent heat of vaporization of the working medium, and then the working medium is transferred to the condenser. A power generator characterized by being returned. A steam generator that recovers exhaust heat and generates high-pressure steam as a working medium, an expander that drives a generator by expanding the high-pressure steam, and a steam after driving the expander in a cooling medium In a power generator comprising: a condenser to be cooled; and a pump that pressurizes the condensate of the working medium condensed in the condenser and feeds it to the steam generator.
A part of the condensate of the working medium is guided to a bearing of a part of the power generation apparatus, directly lubricated and cooled using the condensate of the working medium, and then led to a cooler of the generator. The power generator is configured to return the working medium to the condenser after directly cooling the generator using the latent heat of vaporization of the working medium. After recovering exhaust heat, etc., generating high-pressure steam of the working medium, expanding the high-pressure steam, driving the expander, generating power with a generator directly connected to the expander, and driving the expander In the power generation method of the closed system in which the vapor of the working medium is condensed by cooling with a cooling medium in a condenser, and the condensate of the working medium is pressurized with a pump and sent to the steam generator.
The working medium condensed in the condenser, pressurized at pump, a part of the condensate of a pressurized the working medium guided to the generator, the generator by utilizing the latent heat of vaporization of the working medium Is directly cooled, and the working medium after cooling is returned to the condenser for condensation. Power generation method according to claim 3, characterized in that said by condensate pressurized working medium, to cool the lubricating oil of the bearings.

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