JP2007006684A - Power-generating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power-generating apparatus that can acquire high power generation efficiency, even if the environmental conditions and operating state are changed. <P>SOLUTION: The power generating apparatus 1 is provided with a steam generator 10 for vaporizing a working medium M by a heat exchange between a heating medium H, an expander 20 for expanding the working medium M vaporized in the steam generator 10 and acquiring mechanical force via moving blades, a condenser 40 for condensing the working medium M expanded in the expander 20 by heat exchange between a cooling medium C, a power generator 30 driven by the mechanical force acquired in the expander 20 and generating power, and a controller 60 for controlling the rotational speed of the moving blades so as to maintain a predetermined ratio of a circumferential speed of the moving blades to the theoretical speed found from a thermal drop of the working medium M in the expander 20. Since the expander will track the environmental condition, even if the condition fluctuates and it can be operated at a high-efficiency operating point, the high power generation efficiency can be acquired. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power generation device, and more particularly to a power generation device capable of obtaining high power generation efficiency even when the surrounding environmental conditions change and the operating state changes.

  Today, the effective use of energy is an urgent issue. As a device that can make effective use of unused energy, a closed system that uses the Rankine cycle uses a waste heat to evaporate the working medium, and the working medium vapor There is known a waste heat power generation apparatus that supplies electric power to a steam turbine and obtains electric power by driving a generator (see, for example, Patent Document 1). The power generator is often used in a grid connection with a commercial power source for convenience. At this time, the generator of the power generator operates so as to keep the rotation speed of the steam turbine rotor blade constant in order to synchronize the frequency of the generated power with the frequency of the system power.

On the other hand, the amount of power generated in such a power generation device can vary depending on the ambient environmental temperature. In other words, when the ambient temperature drops (rises), the amount of heat supplied to the steam turbine and converted into mechanical work increases (decreases), and the amount of power generated fluctuates because the drive power of the generator increases (decreases). There is. Thus, even if the surrounding environmental conditions fluctuate, in order to synchronize the frequency of the generated power with the frequency of the system power, it has been necessary to operate the steam turbine rotor blade at a constant rotation speed.
Japanese Unexamined Patent Publication No. 2000-110514 (2nd page, FIG. 1)

  However, since the power generation efficiency of the power generation device depends on the operation efficiency of the steam turbine, if the operation is performed so that the rotation speed of the steam turbine rotor blade is constant, the steam turbine must be operated at the point where the efficiency of the steam turbine is poor. In connection with this, it had to accept the deterioration of the power generation efficiency of a power generator.

  In view of the above-described problems, an object of the present invention is to provide a power generation apparatus that can obtain high power generation efficiency even when the ambient environmental conditions change and the operating state changes.

  In order to achieve the above object, a power generator according to a first aspect of the present invention includes a steam generator 10 that evaporates the working medium M by heat exchange with the heating medium H, for example, as shown in FIG. An expander 20 that expands the working medium M evaporated in the generator 10 and obtains mechanical power through the moving blades; and a condenser that condenses the working medium M expanded in the expander 20 by heat exchange with the cooling medium C 40; a generator 30 driven by the mechanical power obtained by the expander 20 to generate electric power; a ratio of the peripheral speed of the moving blade to a theoretical speed obtained from a heat drop in the expander 20 of the working medium M is predetermined. And a control device 60 for controlling the rotational speed of the moving blade so that Here, the predetermined value is typically a value that maximizes the operating efficiency of the expander 20, and may have a width.

  With this configuration, the rotational speed of the moving blade is controlled so that the ratio of the peripheral speed of the moving blade to the theoretical speed obtained from the heat drop in the expander of the working medium becomes a predetermined value. Even if it fluctuates, it becomes possible to operate the expander at a high-efficiency operating point following this, and high power generation efficiency can be obtained.

  Further, as shown in FIG. 1, for example, in the power generator according to claim 1, the power generated by the power generator according to claim 1 is AC power Ea, and the AC power Ea is converted to DC power. A rectifier 61 for converting to Ed; an inverter 62 for converting DC power Ed to AC power Pg; an enthalpy of the working medium M evaporated into the expander 20 and an enthalpy of the working medium M condensed in the condenser 40 Enthalpy difference detecting means 85, 91, 92 for detecting the enthalpy difference; speed detecting means 84 for detecting the rotational speed of the moving blade; and a DC voltage detector 88 for detecting the voltage of the DC power Ed; 60 calculates the theoretical speed from the enthalpy difference detected by the enthalpy difference detecting means 85, 91, 92, and adjusts the voltage Ed detected by the DC voltage detector 88 to a predetermined voltage. And by being configured to control the rotational speed of the rotor blade to be detected by the speed detection means 84.

  With this configuration, the theoretical speed is calculated from the enthalpy difference detected by the enthalpy difference detecting means, and the rotation of the moving blade detected by the speed detecting means is adjusted by adjusting the voltage detected by the DC voltage detector to a predetermined voltage. Since the speed is controlled, it is possible to calculate the theoretical speed with respect to fluctuations in the surrounding environmental conditions, and to follow this to operate the expander at a high-efficiency operating point, thereby obtaining high power generation efficiency. In addition, since it includes a rectifier that converts the generated AC power into DC power and an inverter that converts DC power into AC power, the frequency of the power generated by the generator can be tuned by the frequency of the system power and the inverter. It is possible to connect the grid power to the grid power without maintaining a constant rotation speed of the rotor blades of the expander.

  Further, for example, as shown in FIG. 1, the power generator according to the invention described in claim 3 is a steam generator 10 that evaporates the working medium M by heat exchange with the heating medium H; An expander 20 that expands the working medium M and obtains mechanical power through the moving blades; a condenser 40 that condenses the working medium M expanded in the expander 20 by heat exchange with the cooling medium C; and the expander 20 A generator 30 that is driven by the mechanical power obtained in step 1 and generates AC power Ea; a rectifier 61 that converts the generated AC power Ea into DC power Ed; and an inverter 62 that converts DC power Ed into AC power Pg Temperature difference detecting means 85 and 91 for detecting a temperature difference between the saturation temperature of the evaporated working medium M introduced into the expander 20 and the condensation temperature of the working medium M condensed by the condenser 40; Detect rotation speed A DC voltage detector 88 for detecting the voltage of the DC power Ed; a predetermined value of the moving blade corresponding to the temperature difference associated in advance from the temperature difference detected by the temperature difference detection means 85, 91; And the voltage detected by the DC voltage detector 88 is adjusted to a predetermined voltage, so that the rotational speed of the moving blade detected by the speed detecting means 84 is controlled to be the predetermined rotational speed. And a control device 60.

  With this configuration, the predetermined rotational speed of the moving blade corresponding to the temperature difference associated in advance is determined from the temperature difference detected by the temperature difference detecting means, and the voltage detected by the DC voltage detector is set to the predetermined voltage. By adjusting, the rotational speed of the moving blade detected by the speed detecting means is controlled to be a predetermined rotational speed. Therefore, the moving blade of the moving blade corresponding to the temperature difference associated in advance with fluctuations in the surrounding environmental conditions is controlled. The expander can be operated at a high-efficiency operating point at a predetermined rotational speed, and high power generation efficiency can be obtained. In addition, since it includes a rectifier that converts the generated AC power into DC power and an inverter that converts DC power into AC power, the frequency of the power generated by the generator can be tuned by the frequency of the system power and the inverter. It is possible to connect the grid power to the grid power without maintaining a constant rotation speed of the rotor blades of the expander.

  According to the present invention, the rotational speed of the moving blade is controlled so that the ratio of the peripheral speed of the moving blade to the theoretical speed obtained from the heat drop in the expander of the working medium becomes a predetermined value. Even if it fluctuates, it becomes possible to operate the expander at a high-efficiency operating point following this, and high power generation efficiency can be obtained. In addition, when a rectifier that converts generated AC power into DC power and an inverter that converts DC power into AC power are provided, the frequency of the power generated by the generator can be tuned by the frequency of the system power and the inverter. It is possible to connect to the grid power without maintaining the rotation speed of the rotor blades of the expander constant.

  Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same or corresponding devices are denoted by the same or similar reference numerals, and redundant description is omitted.

With reference to FIG. 1, the structure of the electric power generating apparatus which concerns on the 1st Embodiment of this invention is demonstrated. FIG. 1 is a block diagram illustrating the configuration of the power generation device 1.
The power generation apparatus 1 includes a steam generator 10 that evaporates the working medium M by exchanging heat with the heating medium H, an expander 20 that expands the evaporated working medium M to obtain mechanical power, and the expander 20 and the shaft. Are connected to each other through a generator 30 that is driven by mechanical power from the expander 20 to generate AC power Ea, and a condenser 40 that condenses the expanded working medium M by exchanging heat with the cooling medium C, and Cooling medium introducing means 41 for introducing the cooling medium C into the condenser 40, a control device 60, a rectifier 61 for converting AC power Ea generated by the generator 30 into DC power Ed, and DC power Ed converted by the rectifier 61 Is converted to AC power Pg.

Here, when dichlorotrifluoroethane HCFC123 having a boiling point of around 40 ° C. or trifluoroethanol CF ₃ CH ₂ OH or the like is used as the working medium, exhaust gas of about 200 to 400 ° C. or exhaust hot water of 100 to 150 ° C. is comparatively used. Using a low-temperature heat source, these heat energies are first converted into high-pressure steam of the working medium M, thereby rotating the turbine (not shown) directly connected to the generator 30 by the expander 20 to generate electricity. be able to. Further, since the pressure is increased, the expander 20 and the like can be made compact. However, the working medium M is not limited to these, and may be other chlorofluorocarbons such as pentafluoropropane R245fa, propane, butane, pentane, hexane, alcohol, or the like, or water. Moreover, the heating medium H should just have the heat which evaporates the working medium M, such as exhaust gas of an incinerator, exhaust hot water, and engine jacket warm water. The power generation apparatus 1 includes a heating medium transporter 16 that pumps the heating medium H to the steam generator 10, and the heating medium transporter 16 is configured to be operated by electric power generated by the generator 30 or commercial power. ing. The cooling medium C will be described later.

  The steam generator 10 and the expander 20 are connected by a pipe 53 that is a flow path of the evaporated working medium M. The piping 53 is provided with a gate valve 51 that can block the flow of the evaporated working medium M and adjust the flow rate by adjusting the opening degree. The expander 20 and the condenser 40 are connected by a pipe 54 that is a flow path of the expanded working medium M. The condenser 40 and the steam generator 10 are connected by a pipe 55 that is a flow path of the condensed working medium M. A working medium pump 50 that pumps the condensed working medium M toward the steam generator 10 is disposed in the pipe 55. The pipe 53 between the steam generator 10 and the gate valve 51 and the condenser 40 are connected by a bypass pipe 56 that bypasses the expander 20 and introduces the working medium M evaporated to the condenser 40. . The bypass piping 56 is provided with a bypass gate valve 52 that can control the flow rate by blocking the flow of the evaporated working medium M and adjusting the opening degree.

  The generator 30 is connected to the rectifier 61 via an electric cable. The rectifier 61 is connected to the inverter 62 via an electric cable. Further, the inverter 62 is grid-connected to a commercial power supply that supplies grid power via an electric cable. The generator 30 is connected to an oil pipe 34 that circulates lubricating oil to be sent to the bearing, and the oil pipe 34 is provided with an oil pump 32 that circulates oil. An oil cooler 33 for cooling the oil is disposed in the oil pipe 34. The oil cooler 33 is connected to an oil cooling pipe 35 through which an oil cooling medium M1 for cooling the oil flows. In the present embodiment, as the oil cooling medium M1, a part of the working medium M condensed by the condenser 40 is divided and used. The oil cooling pipe 35 is connected to the secondary pipe 55 and the condenser 40 of the working medium pump 50.

  The power generation apparatus 1 includes a cooling medium introduction unit 41 that introduces the cooling medium C into the condenser 40. In the present embodiment, the cooling medium introduction unit 41 includes a cooling water pump 43 that pumps the cooling water C as a cooling medium to the condenser 40 and a cooling tower 42 that cools the cooling water C. . The fan 42f and the cooling water pump 43 of the cooling tower 42 are each connected to the inverter 62 via an electric cable (not shown), and are configured to operate by receiving electric power generated by the generator 30 or commercial electric power. ing. As described above, the cooling medium introducing means 41 adjusts the cooling medium C so as to hold the amount of cold heat necessary for condensing the working medium M in the condenser 40 and introduces it into the condenser 40. is there.

  The power generation device 1 includes a steam temperature detector 91 that detects the temperature of the steam of the working medium M, a steam pressure detector 92 that detects the pressure of the steam of the working medium M, and the pressure of the working medium M condensed by the condenser 40. Is detected from the temperature of the saturated liquid of the working medium M. The steam temperature detector 91 and the steam pressure detector 92 may be configured integrally. For simplicity, it may be configured to detect either the temperature or the pressure of the working medium M. Further, a condensing pressure detector 95 may be provided instead of the condensing temperature detector 85 to directly obtain the condensing pressure of the working medium M. Further, the temperature of the heating medium H may be detected by the heat source temperature detector 94 instead of the steam temperature detector 91, and the temperature of the steam of the working medium M may be calculated therefrom. The steam temperature detector 91 and the condensation temperature detector 85 can detect the temperature difference between the working medium M before and after the expander 20, and these constitute the temperature difference detecting means.

  The power generator 1 is converted by the speed detector 84 that detects the rotational speed N of the rotor of the generator 30, the current detector 81 that detects the intensity of the current generated by the generator 30, and the rectifier 61. And a DC voltage detector 88 for detecting the magnitude of the DC voltage. Since the rotor (not shown) of the generator 30 and the moving blade (not shown) of the expander 20 are connected via a shaft, the rotating speed n of the moving blade can be detected from the rotating speed N of the rotor. . When the generator 30 and the expander 20 are connected via a speed increaser or a speed reducer, the rotational speed N of the rotor of the generator 30 and the rotational speed n of the moving blades of the expander 20 are not equal. There is a correlation, and when both are directly connected, the rotational speed N of the rotor and the rotational speed n of the rotor blade are equal. Therefore, the speed detector 84 is one of speed detecting means. Further, since there is a correlation between the frequency of the power generated by the generator 30 and the rotational speed N of the rotor, in order to grasp the rotational speed n of the rotor blades of the expander 20, instead of detecting the rotational speed N of the rotor You may detect the frequency of generated electric power with a frequency detector (not shown). A frequency detector is also one of speed detection means. The speed detection means can also monitor the prevention of overspeed of the generator 30. The power generation apparatus 1 may include a power detector 82 that detects the magnitude of the power generated by the generator 30.

  Further, instead of the current detector 81 and the power detector 82, or together with these detectors, a coil temperature detector 83 for detecting the temperature of the stator coil of the generator 30 and a cooling medium introduced into the condenser 40. A cooling medium temperature detector 86 for detecting the temperature of C may be provided. With these detectors, it is possible to grasp the state of the device so that the rotation speed of the expander 20 and the generator 30 or the generated power of the generator 30 does not exceed a predetermined value.

  Understanding the rotation speed of the expander 20 and the generator 30 or the state of the device so that the generated power of the generator 30 does not exceed a predetermined value means that the generator 30 is heated by excessive current or excessive rotation speed. It is an index for taking measures to prevent damage such as burnout of bearings due to rust. The current detector 81 can directly detect whether or not there is an overcurrent. The power detector 82 can detect the amount of electrical energy generated by the generator 30. The power value may be calculated from the current value and the voltage value. Moreover, since the coil temperature detector 83 can directly detect the temperature of the generator 30, it is easy to prevent overheating. The cooling medium temperature detector 86 can detect the approximate condensation temperature of the working medium M by a simple means. When heat exchange is performed between the cooling medium C and the outside air, the temperature of the cooling medium C may be obtained from the outside air temperature detected by the outside air temperature detector 93.

  The control device 60 typically includes a rectifier 61, an inverter 62, a current detector 81, and a DC voltage detector 88. In addition, the steam temperature detector 91, the steam pressure detector 92, and the condensation temperature detector 85 are connected to each other by a signal cable (not shown) so that the values detected by the detectors 85, 91, and 92 can be taken in. It is configured. The detectors 82 to 86 and 93 to 95 are also connected by a signal cable (not shown), and are configured so that values detected by the detectors 82 to 86 and 93 to 95 can be taken in. The control device 60 can perform various calculations based on the values taken from the detectors 82 to 86 and 91 to 95, and based on the calculated values and the values taken from the detectors 82 to 86 and 91 to 95. The power generation unit 30 is configured to be able to adjust the generated power, adjust the output power from the power generator 1, increase or decrease the rotational speed of the fan 42 f and the cooling water pump 43, and the like. Moreover, it connects with each of the gate valve 51 and the bypass gate valve 52 by the signal cable not shown, and it is comprised so that it can open / close by transmitting an opening / closing signal to these.

  Moreover, the control apparatus 60 is comprised so that various information can be recorded. In the present embodiment, information related to the working medium M is recorded in the control device 60 in advance. Therefore, the enthalpy h3 and entropy s3 of the steam of the working medium M can be obtained from the temperature detected by the steam temperature detector 91 and the pressure detected by the steam pressure detector 92. Further, since the expansion of the working medium M in the expander 20 is adiabatic expansion, the entropy s4 of the expanded working medium M is stored (s4 = s3), and is calculated based on this and the temperature detected by the condensation temperature detector 85. The enthalpy h4 of the working medium M condensed from the condensation pressure can be obtained. Note that the condensation pressure can be directly detected from the condensation pressure detector 95 as described above. From these, the enthalpy difference (h3-h4) before and after the expander 20 can be obtained from the steam temperature detector 91, the steam pressure detector 92, and the condensation temperature detector 85 (condensation pressure detector 95), and this is the enthalpy difference detection. Means.

Next, with reference to FIG.1 and FIG.2, the effect | action of the electric power generating apparatus 1 is demonstrated.
FIG. 2 is a Ph diagram (the pressure P is taken on the vertical axis and the enthalpy h is taken on the horizontal axis) for explaining changes in the state of the working medium M. Also, the curve in FIG. 2 connects the state points of the working medium M with a degree of excitement of 0 and degree of excitement of 1. In the following description, it is assumed that the expander 20 includes a turbine (not shown) and that the heating medium H is engine jacket hot water.
The steam generator 10, the expander 20, the condenser 40 and the pipes 53, 54, and 55 that connect them constitute a closed system of the working medium M, and the power generator 1 performs the Rankine cycle and is obtained by the expander 20. Electric power is generated by the generator 30 driven by the generated mechanical driving force.

  The liquid working medium M is pumped to the steam generator 10 by the working medium pump 50 (state 1 → state 2). The working medium M that has flowed into the steam generator 10 is exchanged with the jacket warm water H to become saturated steam or superheated steam (state 2 → state 3). The working medium M that has become steam flows into the expander 20. Here, during steady operation, the gate valve 51 is open and the bypass gate valve 52 is closed. Accordingly, all of the working medium vapor M flows into the expander 20. The working medium vapor | steam M which flowed into the expander 20 carries out adiabatic expansion through a turbine (state 3-> state 4). At this time, the moving blades of the turbine are rotated by the working medium M to obtain mechanical power (conversion from thermal energy to mechanical energy). The generator 30 connected to the expander 20 is driven by the obtained mechanical power, and the generator 30 generates power (conversion from mechanical energy to electrical energy). The mechanical power obtained by the expander 20 varies depending on the difference in enthalpy of the working medium M before and after the expander 20 (h3-h4: heat drop). When the enthalpy difference is large, a large mechanical power can be obtained, and when the enthalpy difference is small, the obtained mechanical power is also small. The working medium M expanded by the expander 20 flows into the condenser 40, exchanges heat with the cooling water C, condenses, and becomes a liquid working medium M (state 4 → state 1). The working medium M returned to the liquid is pumped again to the steam generator 10 by the working medium pump 50, and the same cycle is performed thereafter.

  The AC power Ea generated by the generator 30 is sent to the rectifier 61 and converted to DC power Ed, and then sent to the inverter 62 to be converted to AC power Pg and linked to the system power. The grid-connected AC power Pg is transmitted to the fan 42f, the cooling water pump 43, and a power load (not shown). The fan 42f and the cooling water pump 43 operate by receiving power supply from a commercial power source when there is no power generation by the generator 30. Strictly speaking, it is not possible to distinguish whether the AC power after grid connection is generated by the generator 30 or supplied from a commercial power source, but as a concept, it is generated from the power generated by the generator 30. The remaining power obtained by subtracting the power consumed in the device 1 is the effective power that can be taken out from the power generation device 1 and can be used by the power load outside the power generation device 1. The electric power consumed in the power generator 1 may be supplied directly or via an inverter for cooling medium introduction means (not shown).

  The jacket hot water H whose temperature has been lowered by exchanging heat with the working medium M in the steam generator 10 is guided to an engine (not shown) and used for cooling the engine. After the temperature has risen, steam is again used as a heat source for the power generator 1. Introduced into the generator 10. Further, the cooling water C whose temperature has increased by exchanging heat with the working medium M in the condenser 40 is discharged to the atmosphere by the cooling tower 42 and the temperature is lowered. Pumped. Here, since the temperature of the jacket warm water H is almost constant with almost no fluctuation, the evaporation temperature of the working medium M in the steam generator 10 is substantially constant. On the other hand, the temperature of the cooling water C changes due to changes in ambient environmental conditions such as the outside air temperature.

  When the outside air temperature decreases, the temperature of the cooling water C pumped to the condenser 40 decreases, and the condensing temperature of the working medium M in the condenser 40 decreases accordingly. In FIG. 2, the state 4 has moved to the state 4 ′ where the pressure is lower than the state 4 and the enthalpy is small. As apparent from FIG. 2, when the condensation temperature in the condenser 40 decreases as the outside air temperature decreases, and the cycle of the working medium M shifts from the state 4 to the state 4 ′, the enthalpy difference, that is, mechanical power is increased. The thermal energy converted is increased. When the thermal energy increases, the rotational speed n of the turbine blade increases and the rotational speed N of the rotor of the generator 30 increases and the frequency of the generated power increases, but the power generator 1 includes the rectifier 61 and the inverter 62. Therefore, there is no need to limit the rotational speed n of the turbine rotor blade to match the system power frequency. Therefore, the control device 60 performs the following control so that the power generation efficiency (output power / input energy) in the power generation device 1 is the best, that is, the turbine efficiency is the best. It is known that the efficiency of the turbine has a predetermined relationship with the ratio (U / Co) of “the peripheral speed of the turbine blade” to “theoretical speed of the steam of the working medium M”.

FIG. 3 shows the ratio (U / Co) of “circumferential speed of turbine blade” to “theoretical speed of steam of working medium M” and turbine efficiency η in the turbine (single-stage radial turbine) of the present embodiment. It is a graph which shows a relationship. Here, the circumferential speed U of the turbine blade (hereinafter simply referred to as “circumferential speed U”) is expressed by the product (U = πnD) of the circumferential ratio π, the rotational speed n of the blade, and the diameter D of the blade. Is done. On the other hand, the theoretical velocity Co of the working medium M (hereinafter simply referred to as “theoretical velocity Co”) is a square root twice as large as the enthalpy difference (h3−h4) (Co = (2 (h3−h4)) ^1/2 ). It is known that In the example of the single-stage radial turbine in the present embodiment shown in FIG. 3, it is most efficient to operate so that the ratio (U / Co) is about 0.7. The value with the best ratio (U / Co) is a “predetermined value”, and the predetermined value may have an allowable range. As described above, since the enthalpy difference (h3−h4) varies with changes in environmental conditions, the theoretical speed Co also varies with changes in environmental conditions. On the other hand, since the diameter D of the turbine blade does not change during operation, the turbine speed is changed so that the rotational speed n is changed following the change in the theoretical speed Co so that the ratio (U / Co) becomes about 0.7. To drive.

The control device 60 obtains the enthalpy h3 of the steam of the working medium M from the temperature detected by the steam temperature detector 91 and the pressure detected by the steam pressure detector 92, while based on the temperature detected by the condensation temperature detector 85. The enthalpy h4 is obtained from the calculated pressure, and the theoretical speed Co is calculated. Next, the control device 60 calculates the rotation speed n _t such that the ratio (U / Co) is 0.7 (n _t = 0.7 × Co / (πD)). Further, the control device 60 detects the actual rotational speed n of the moving blade by the speed detector 84 and calculates a deviation from the intended rotational speed n _t . Then, the rotational speed n of the moving blade is controlled so that the deviation becomes small, and this is performed by controlling the voltage by the inverter 62. Hereinafter, voltage control by the inverter 62 will be described.

  FIG. 4 is a diagram showing the relationship between the output power Pg of the power generator 1 and the rotor rotational speed N of the generator 30 with the DC voltage Vd as a parameter. According to FIG. 4, when the DC voltage Vd and the output power Pg are given, the rotor rotational speed N is determined. In the present embodiment, since the rotor of the generator 30 is directly connected to the turbine blade through the shaft, when the rotor rotation speed N is determined, the rotation speed n of the turbine blade is determined. In the case of the control in which the DC voltage Vd is constant, if the turbine work of the power generation device 1 increases, the balance between the increase of the output power Pg to the system and the increase of the rotational speed N of the rotor, and conversely, when the turbine work decreases, A balance is achieved by a decrease in the output power Pg and a decrease in the rotational speed N of the rotor.

The control device 60 controls the inverter 62, adjusts the alternating current output to the system power while monitoring the direct current voltage Vd detected by the direct current voltage detector 88, and adjusts the direct current voltage Vd to a predetermined voltage. As a result, the rotational speed N of the rotor, and hence the rotational speed n of the rotor blades can be controlled. More specifically, the control device 60 reduces the deviation between the actual rotational speed n of the moving blade and the target rotational speed n _t (n _t = 0.7 × Co / (πD)). The direct-current voltage detector 88 detects the direct-current voltage Vd, and adjusts the direct-current voltage so that the target voltage indicated by the thick line in FIG. Thus, by adjusting the DC voltage to a predetermined voltage, the rotational speed n of the moving blade can be controlled to an efficient point.

  Here, since the power generator 1 is grid-connected, the output voltage must be equal to or higher than the voltage on the grid side. Although the minimum required voltage Vd of the DC power Ed is determined from the voltage on the system side, for example, in order to connect to 220V, the DC voltage Vd needs to be at least 365 to 370V. Therefore, this voltage value becomes a lower limit when adjusting the DC voltage Vd to a predetermined voltage. In this embodiment, the lower limit of the predetermined voltage is 370V.

  On the other hand, the generator 30 is not generally designed to withstand the maximum work load that can be assumed by the power generation device 1. If the specification can withstand the maximum work load that can be assumed by the power generation device 1, it is uneconomical to produce a generator at a great cost due to a rare occurrence. When the mechanical work exceeding the allowable amount is given to the generator 30, heat is generated due to excessive current and the temperature rises, resulting in inoperability, or the torque between the rotor and the stator of the generator is insufficient, resulting in a high speed rotor. Rotation may result in bearing burnout due to overspeed. Even if economy is taken into consideration, it is necessary to avoid such damage to the generator 30. Accordingly, the upper limit of the rotational speed N is determined from the viewpoint of preventing the excessive rotational speed, and accordingly, the upper limit for adjusting the DC voltage to a predetermined voltage is determined. In the present embodiment, as shown in FIG. 4, with the upper limit of the rotational speed N being set to 108, 430 V is the upper limit of the DC voltage value. In FIG. 4, it is conceivable that when the output power is increased at the upper limit of the rotational speed N, the DC voltage gradually decreases and reaches the lower limit value. It will be.

In the above description, the theoretical speed Co is obtained from the enthalpy difference, and the rotational speed n of the moving blade is led to an efficient point. However, as a simple calculation means, the temperature difference of the working medium M before and after the expander 20 is calculated. You may lead from. Depending on the type of the working medium M, there is no practical problem even if the high efficiency point of the rotational speed n of the moving blade is derived from the temperature difference.
5, in the case where the working medium M and R245fa, a graph showing the relationship between the degree of superheat Ts and the theoretical speed Co of the working medium M, (a) the temperature of the saturated steam condensation temperature T _C as a constant graph of T _G as a parameter, (b) is a graph as a parameter the condensation temperature T _C at a constant temperature T _G of the saturated vapor. It can be seen from the graph that in any case, the theoretical speed Co hardly changes even if the superheat degree Ts changes. This is because even when the degree of superheat increases in R245fa, the difference in enthalpy before and after expansion when the state expands from the state to the condensation pressure by adiabatic change is hardly changed. Therefore, when calculating the simple, not harm practically ignore the degree of superheat Ts of the vapor of the working medium M, obtaining the theoretical speed Co and a saturation temperature T _G of the vapor of the working medium M and the condensing temperature T _C be able to.

FIG. 6 shows the relationship between the temperature difference (T _G −T _C ) between the saturation temperature _TG of the steam of the working medium M and the condensation temperature T _C and the theoretical speed Co when the working medium M is R245fa. It is a graph.
The Figure 7 shows the case where the working medium M and R245fa, temperature difference between the saturation temperature _{T G} of the vapor of the working medium M and the condensing temperature _{T C} and _(T G -T _C), the turbine blades target is a graph showing the relationship between the rotational speed n _t.
In the working medium M effect of the change in the degree of superheat of the theoretical velocity Co is small as described above, the temperature difference between the saturation temperature T _G of the vapor of the working medium M and the condensing temperature T _C and (T G _{-T C),} the theoretical The speed Co and the predetermined rotational speed n _t of the moving blade are stored in the control device 60 in advance in association with each other as shown in FIGS. 6 and 7, and the temperature detected by the steam temperature detector 91 and the condensation temperature detector 85. by adjusting the DC voltage Vd to a predetermined voltage based on the difference, it may control the rotational speed n of the rotor blade to a predetermined rotational speed n _t.

Moreover, association Other Other physical quantity associated with enthalpy also (e.g. saturation pressure, condensing pressure, ambient temperature, coolant temperature, the heat source temperature, etc.) and a predetermined rotational speed n _t theory speed Co and blades in advance Alternatively, the rotational speed n of the moving blade may be controlled by detecting the substituted physical quantity and storing it in the control device 60.

Next, with reference to FIG. 8, the electric power generating apparatus 2 which concerns on the 2nd Embodiment of this invention is demonstrated. FIG. 8 is a block diagram illustrating the configuration of the power generation device 2. Hereinafter, differences between the power generation device 1 and the power generation device 2 will be mainly described, and descriptions of common parts will be omitted.
The power generator 2 is configured such that the condenser 40 is air-cooled. Therefore, the cooling medium C becomes air. The cooling medium introducing means 41 is constituted by an air cooling fan 45. Other configurations are the same as those of the power generation apparatus 1.

Since the condensing temperature in the condenser 40 is greatly affected by the outside air temperature, the control device 60 calculates the condensing temperature based on the outside air temperature detected by the outside air temperature detector 93, and stores the condensing temperature in advance. by applying a has been has 6 or a value calculated from the outside temperature to the conditions shown in FIG. 7, by adjusting the DC voltage Vd to a predetermined voltage, and controls the rotational speed n of the rotor blade to a predetermined rotational speed n _t May be.

  In the above description, the power generated by the generator 30 is alternating current, but may be direct current. In this case, the rectifier 61 can be omitted, and the power generated by the generator 30 can be converted by the inverter 62 and linked to the system power.

  In the above description, it is described that the operation is performed so that the ratio (U / Co) is about 0.7. However, since this value varies depending on the type and the number of stages of the turbine, the efficiency of the turbine to be used is increased, and the power generator 1 The power generation efficiency may be set as appropriate.

It is a block diagram which shows the structure of the electric power generating apparatus which concerns on the 1st Embodiment of this invention. 6 is a Ph diagram illustrating a change in the state of the working medium M. FIG. It is a graph which shows the relationship between the ratio with respect to the theoretical speed with respect to the theoretical speed, and efficiency in the expander of this Embodiment. It is a figure which shows the relationship between the electric power generation output which used DC voltage as a parameter, and rotor rotational speed. It is the graph which showed the relationship between the superheat degree at the time of using R245fa as a working medium, and theoretical speed. (A) is a graph in which the condensation temperature is constant and the saturation temperature is a parameter, and (b) is a graph in which the saturation temperature is constant and the condensation temperature is a parameter. It is the graph which showed the relationship between the temperature difference of the vapor | steam of a working medium, and theoretical speed. It is the graph which showed the relationship between the temperature difference of the vapor | steam of a working medium, and the rotational speed of a moving blade. It is a block diagram which shows the structure of the electric power generating apparatus which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power generator 10 Steam generator 20 Expander 30 Generator 40 Condenser 41 Cooling medium introduction means 56 Bypass flow path 60 Controller 61 Rectifier 62 Inverter 81 Current detector 82 Power detector 83 Coil temperature detector 84 Speed detector 85 Condensation temperature detector 86 Cooling medium temperature detector 88 DC voltage detector 91 Steam temperature detector 92 Steam pressure detector C Cooling medium H Heating medium M Working medium Ea, Pg AC power Ed DC power

Claims (3)

A steam generator for evaporating the working medium by heat exchange with the heating medium;
An expander that expands the working medium evaporated by the steam generator and obtains mechanical power via a moving blade;
A condenser that condenses the working medium expanded in the expander by heat exchange with the cooling medium;
A generator that generates power by being driven by mechanical power obtained by the expander;
A control device for controlling the rotational speed of the moving blade so that a ratio of a peripheral speed of the moving blade to a theoretical speed obtained from a heat drop of the working medium in the expander becomes a predetermined value;
Power generation device. The generated power is AC power, and a rectifier that converts the AC power into DC power;
An inverter that converts the DC power into AC power;
An enthalpy difference detection means for detecting an enthalpy difference between the enthalpy of the evaporated working medium introduced into the expander and the enthalpy of the working medium condensed by the condenser;
Speed detecting means for detecting the rotational speed of the moving blade;
A DC voltage detector for detecting the voltage of the DC power;
The control device calculates the theoretical speed from the enthalpy difference detected by the enthalpy difference detection means, and adjusts the voltage detected by the DC voltage detector to a predetermined voltage, thereby detecting the speed detection means. Configured to control the rotational speed of the blade;
The power generation device according to claim 1. A steam generator for evaporating the working medium by heat exchange with the heating medium;
An expander that expands the working medium evaporated by the steam generator and obtains mechanical power via a moving blade;
A condenser that condenses the working medium expanded in the expander by heat exchange with the cooling medium;
A generator driven by the mechanical power obtained by the expander to generate AC power;
A rectifier for converting the generated AC power into DC power;
An inverter that converts the DC power into AC power;
A temperature difference detection means for detecting a temperature difference between a saturation temperature of the evaporated working medium introduced into the expander and a condensation temperature of the working medium condensed in the condenser;
Speed detecting means for detecting the rotational speed of the moving blade;
A DC voltage detector for detecting the voltage of the DC power;
A predetermined rotational speed of the moving blade corresponding to the temperature difference associated in advance is determined from the temperature difference detected by the temperature difference detection means, and a voltage detected by the DC voltage detector is adjusted to a predetermined voltage. A control device that controls the rotational speed of the moving blade detected by the speed detection means to be the predetermined rotational speed;
Power generation device.

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