JP5918117B2 - Power generator - Google Patents

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JP5918117B2
JP5918117B2 JP2012275673A JP2012275673A JP5918117B2 JP 5918117 B2 JP5918117 B2 JP 5918117B2 JP 2012275673 A JP2012275673 A JP 2012275673A JP 2012275673 A JP2012275673 A JP 2012275673A JP 5918117 B2 JP5918117 B2 JP 5918117B2
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expander
working medium
upper limit
value
detection means
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JP2014118908A (en
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昇 壷井
昇 壷井
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株式会社神戸製鋼所
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00Combustion technologies with mitigation potential
    • Y02E20/10Combined combustion
    • Y02E20/14Combined heat and power generation [CHP]

Description

  The present invention relates to a power generator using a Rankine cycle.

  2. Description of the Related Art Conventionally, a power generation apparatus that recovers exhaust heat from various facilities such as a factory and generates power using the energy of the recovered exhaust heat is known. Among such power generation apparatuses, Patent Document 1 discloses a binary power generation apparatus, that is, a power generation apparatus using a Rankine cycle that circulates a low-boiling working medium for driving an expander. The power generation device includes an evaporator that evaporates the working medium, an expander that includes a rotor that is rotationally driven by the expansion energy of the working medium evaporated by the evaporator, and a condenser that condenses the working medium discharged from the expander. A circulation pump for sending the working medium condensed in the condenser to the evaporator, and a generator driven by the working medium expanding in the expander.

  In a power generation device using Rankine cycle, the energy that can be extracted by the expander is theoretically the difference between the enthalpy of the working medium on the outlet side of the evaporator and the enthalpy of the working medium on the inlet side of the condenser. A value obtained by multiplying the difference by the flow rate of the working medium is a power generation amount generated by the generator.

JP 60-144594 A

  By the way, in the generator of a power generator as described in Patent Document 1, the temperature of the heat source in the evaporator or condenser (hereinafter referred to as “ambient temperature”) changes, and the enthalpy of the working medium flowing into the expander. When the difference between the enthalpy of the working medium flowing out from the expander becomes small, the amount of power generation is reduced. Also, if the ambient temperature fluctuates, when the required power of the equipment connected to the generator changes, the amount of power generated by the generator cannot follow this change.

  The objective of this invention is providing the electric power generating apparatus which can suppress the fluctuation | variation of the electric power generation amount resulting from the change of ambient temperature.

  In order to solve the above problem, it is considered to increase the rotation speed of the expander with an increase in the required power of the device, and to decrease the rotation speed of the expander with a decrease in the required power of the device. It is done. Here, in general, the expander has a maximum value of the allowable number of rotations (maximum value of the number of rotations that can avoid the shortening of the bearing life and the occurrence of resonance). In order to improve stability as compared with the case where the motor is driven steadily, it is desirable to set an upper limit value which is a rotational speed smaller than the maximum value and to change the rotational speed within the upper limit value.

  In addition, when the temperature around the power generator changes due to seasonal changes, etc., and accordingly the temperature of the heating medium of the evaporator (the pressure of the working medium on the suction side of the expander) decreases, Also when the temperature of the cooling medium of the vessel (the pressure of the working medium on the discharge side of the expander) increases, the amount of power generated by the generator changes. Specifically, when the temperature of the heating medium of the evaporator (pressure of the working medium on the suction side of the expander) decreases, the enthalpy of the working medium on the outlet side of the evaporator (suction side of the expander) Therefore, the difference between the enthalpy of the working medium on the outlet side of the evaporator and the enthalpy of the working medium on the inlet side of the condenser is reduced, and the amount of power generated by the generator is reduced. When the temperature of the cooling medium of the condenser (the pressure of the working medium on the discharge side of the expander) rises, the enthalpy of the working medium on the inlet side of the condenser (discharge side of the expander) increases. The difference between the enthalpy of the working medium on the outlet side of the evaporator and the enthalpy of the working medium on the inlet side of the condenser is reduced, and the amount of power generated by the generator is reduced.

  Therefore, a power generator capable of flexibly changing the amount of power generation in accordance with a change in the ambient temperature of the power generator in addition to the change in the required power is desired.

  Accordingly, the present invention condenses an evaporator that evaporates the working medium, an expander that includes a rotor that is rotationally driven by the expansion energy of the working medium evaporated by the evaporator, and the working medium discharged from the expander. A condenser, a circulation pump for sending the working medium condensed in the condenser to the evaporator, a generator driven by the working medium expanding in the expander, and a working medium flowing into the expander A suction side detection means capable of detecting a value used for calculating the state quantity, and a rotation speed lower than a maximum value of the rotation speed of the rotor and within a range equal to or lower than an upper limit value which is a preset rotation speed, And the value detected by the control part which controls the rotation speed of the said expander according to the request | requirement electric power requested | required from the apparatus with which the electric power produced | generated by the said generator is supplied, and the value detected by the said suction side detection means reduce. According to , To provide a power generator and a maximum value correcting unit for correcting the upper limit to raise in a range of less than the maximum value.

  According to the present invention, when the ambient temperature that affects the enthalpy of the working medium decreases, the enthalpy of the working medium flowing into the expander decreases accordingly, and the power generation amount also decreases. As the value detected by the suction side detection means decreases, the upper limit value is raised in a range less than the maximum value, so that the range in which the control unit can increase the rotational speed of the expander is expanded. This makes it possible to compensate for the shortage of the power generation amount due to the decrease in the ambient temperature, that is, to suppress the fluctuation of the power generation amount due to the change in the ambient temperature. Therefore, power is stably supplied to the device. Here, since the upper limit value is less than the maximum value, a stable driving state of the expander is ensured. Since the control unit changes the rotation speed of the expander in accordance with the required power of the device, it is possible to generate power that follows the change in the required power in the generator. As a result, it is possible to achieve both the generation of power following the change in the required power of the device and the suppression of fluctuations in the amount of power generated due to the change in ambient temperature.

  In the present invention, there is provided discharge side detection means capable of detecting a value used for calculating the state quantity of the working medium discharged from the expander, and the upper limit correction unit is detected by the discharge side detection means. You may correct | amend so that the said upper limit may be raised in the range below the said maximum value as a value rises. Even in this case, the same effects as described above can be obtained.

  Alternatively, in the present invention, both the suction side detection means and the discharge side detection means are provided, and the upper limit correction unit is a value detected by the suction side detection means and a value detected by the discharge side detection means. The upper limit value is changed in a range less than the maximum value based on the difference between the upper limit value and the ratio of the value detected by the suction side detection means to the value detected by the discharge side detection means. It may be corrected. Even in this case, the same effects as described above can be obtained.

  Further, in the present invention, coil temperature detecting means for detecting the coil temperature of the generator is further provided, and the control unit has a value detected by the coil temperature detecting means equal to or higher than a preset upper limit value of the coil temperature. In some cases, it is preferable to reduce the rotational speed of the expander. In this way, while avoiding damage to the coil of the generator, it is possible to achieve both the generation of power that follows the change in the required power of the device and the suppression of fluctuations in the amount of power generated due to changes in the ambient temperature. It becomes possible.

  Further, in the present invention, it further comprises a current value detection means for detecting a value of the current generated by the generator, and the control unit has a preset current value detected by the current value detection means. It is preferable to reduce the rotational speed of the expander when it is equal to or higher than the upper limit value. In this way, while avoiding damage to the generator, it is possible to achieve both the generation of electric power that follows changes in the required power of the equipment and the suppression of fluctuations in the amount of power generated due to changes in the ambient temperature. Become.

  Further, in the present invention, it further comprises oil discharge temperature detection means for detecting oil discharge temperature discharged from the expander bearing, and the control unit is preset with a value detected by the oil discharge temperature detection means. It is preferable to reduce the rotational speed of the expander when the oil discharge temperature is equal to or higher than the upper limit value. In this way, while avoiding damage to the expander, it is possible to achieve both the generation of electric power that follows changes in the required power of the equipment and the suppression of fluctuations in the amount of power generated due to changes in the ambient temperature. Become.

  Moreover, in this invention, it is preferable that the said control part increases / decreases the rotation speed of the said circulation pump according to increase / decrease in the rotation speed of the said expander. In this way, the amount of working medium corresponding to the number of rotations circulates in accordance with the increase or decrease of the number of rotations of the expander, so that the rotation drive of the rotor of the expander becomes smooth.

  As described above, according to the present invention, it is possible to suppress fluctuations in the amount of power generated due to changes in ambient temperature.

It is a figure which shows the outline of a structure of the electric power generating apparatus of 1st embodiment of this invention. It is a Mollier diagram which shows the state change of the working medium in the electric power generating apparatus of FIG. It is a flowchart for demonstrating the control content of the electric power generating apparatus shown in FIG. It is a flowchart explaining the control content of an upper limit correction | amendment part. (A) It is a figure which shows the relationship between the suction pressure of a working medium, and an upper limit. (B) It is a figure which shows the modification of (a). (C) It is a figure which shows the modification of (a). It is a figure which shows the outline of a structure of the electric power generating apparatus of 2nd embodiment of this invention. It is a Mollier diagram which shows the state change of the working medium in the electric power generating apparatus of FIG. It is a figure which shows the outline of a structure of the electric power generating apparatus of 3rd embodiment of this invention. (A) It is a figure which shows the relationship between the discharge pressure of a working medium, and an upper limit. (B) It is a figure which shows the modification of (a). (C) It is a figure which shows the modification of (a). It is a figure which shows the outline of a structure of the electric power generating apparatus of 3rd embodiment of this invention. (A) It is a figure which shows the relationship between the difference of the suction pressure and discharge pressure of a working medium, and an upper limit. (B) It is a figure which shows the modification of (a). (C) It is a figure which shows the modification of (a).

(First embodiment)
A power generator according to a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, this power generation apparatus is configured to have an evaporator 11 that heats and evaporates a working medium, an expander 12 that is driven by the working medium discharged from the evaporator 11, and an exhaust that is discharged from the expander 12. The working medium circulates by connecting the condenser 13 that cools and condenses the working medium, the circulation pump 14 that sends the working medium discharged from the condenser 13 to the evaporator 11, and the devices 11 to 14. A circulation channel 15 that forms a closed circuit, a generator 16 that generates power by obtaining power from the expander 12, and a suction that can detect a value used to calculate the state quantity (enthalpy) of the working medium flowing into the expander 12 The side detection means 21 and 22 and the control means 30 which controls the rotation speed etc. of the expander 12 are provided. Note that a working medium having a boiling point lower than that of water, such as HFC245fa, is used for this power generator.

  The evaporator 11 evaporates the liquid working medium into saturated steam or superheated steam. The evaporator 11 has a working medium flow path 11a through which a liquid working medium flows, and a heating medium flow path 11b through which a heating medium supplied from an external heat source flows. The working medium flowing through the working medium flow path 11a evaporates by exchanging heat with the heating medium flowing through the heating medium flow path 11b. Examples of the heating medium supplied to the heating medium flow path 11b include steam and hot water. The heating medium flow path 11 b is connected to a supply flow path 17 for supplying a heating medium from an external heat source to the evaporator 11.

  The expander 12 includes a rotor that is rotationally driven by the expansion energy of the working medium discharged from the evaporator 11, and is provided on the downstream side of the evaporator 11 in the circulation flow path 15. Specifically, the expander 12 includes a casing in which a rotor chamber is formed, and a pair of male and female screw rotors (rotors) rotatably supported in the rotor chamber. In the present embodiment, the screw rotor is rotationally driven by the expansion energy of the working medium supplied to the rotor chamber from the air inlet formed in the casing. Then, the working medium whose pressure has been reduced by expanding in the rotor chamber is discharged from a discharge port formed in the casing. Further, the expander 12 can be driven at an arbitrary number of rotations within a range not more than the maximum value described later.

  The condenser 13 condenses the gaseous working medium into a liquid working medium, and is provided on the downstream side of the expander 12 in the circulation flow path 15. The condenser 13 has a working medium flow path 13a through which a gaseous working medium flows and a cooling medium flow path 13b through which a cooling medium supplied from the outside flows. The working medium flowing through the working medium flow path 13a is condensed by exchanging heat with the cooling medium flowing through the cooling medium flow path 13b. Examples of the cooling medium flowing in the cooling medium flow path 13b include cooling water and air. The cooling medium flow path 13 b is connected to a supply flow path 18 for supplying a cooling medium from the outside to the condenser 13.

  The circulation pump 14 is provided on the downstream side of the condenser 13 (between the evaporator 11 and the condenser 13) in the circulation channel 15 and circulates the working medium in the circulation channel 15. . The circulation pump 14 pressurizes the liquid working medium condensed by the condenser 13 to a predetermined pressure and sends it to the evaporator 11. As the circulation pump 14, a centrifugal pump having an impeller as a rotor, a gear pump having a rotor composed of a pair of gears, or the like is used. The circulation pump 14 can be driven at an arbitrary rotational speed.

  The generator 16 is connected to the expander 12, and is driven when the working medium expands in the expander 12 and the screw rotor is rotationally driven. Specifically, the generator 16 has a rotating shaft connected to one of the pair of screw rotors of the expander 12, and the rotating shaft rotates with the rotation of the screw rotor. To generate power.

  The suction side detection means is a sensor capable of detecting a value used for calculating the state quantity (enthalpy) of the working medium flowing into the expander 12. The power generation device of the present embodiment is provided between the evaporator 11 and the expander 12 in the circulation flow path 15 and detects the pressure of the working medium flowing into the expander 12, and the supply flow An evaporator side temperature sensor 22 that is provided in the path 17 and detects the temperature of the heating medium supplied to the evaporator 11 is provided, and at least one of these sensors constitutes a suction side detection means. That is, based on the suction pressure detected by the suction-side pressure sensor 21 (pressure on the suction side of the expander 12) or the temperature of the heating medium detected by the evaporator-side temperature sensor 22, the suction side of the expander 12 The enthalpy (hereinafter referred to as “suction side enthalpy”) of the working medium is calculated. As will be described later, as the suction side enthalpy decreases, the amount of power generated by the generator 16 decreases. Instead of the suction side pressure sensor 21, a suction side temperature sensor that detects the temperature of the working medium flowing into the expander 12 may be used.

  The power generator includes a coil temperature detecting means 36 for detecting the coil temperature of the generator 16, a current value detecting means 37 for detecting the value of the current generated by the generator 16, and exhaust discharged from the bearing of the expander 12. Oil exhaust temperature detecting means 38 for detecting the oil temperature is further provided. The coil temperature detecting means 36 and the current value detecting means 37 are respectively provided in the generator 16, and the oil discharge temperature detecting means 38 is provided in the expander 12. However, in FIG. Is shown in the vicinity of the control unit 30.

  The control unit 30 includes a control unit 31 that controls the rotation speed of the expander 12 and the rotation speed of the circulation pump 14, and an upper limit correction unit 35 that corrects the upper limit value of the rotation speed of the expander 12.

  The control unit 31 controls the rotational speed of the expander 12 and the rotational speed of the circulation pump 14 in accordance with required power required from a predetermined device 40 (power required for driving the device 40). The device 40 is electrically connected to the generator 16, and power generated by the generator 16 is supplied to the device 40. Specifically, the control unit 31 controls the rotation speed of the expander 12 via the inverter 32 and similarly controls the rotation speed of the circulation pump 14 via the inverter 33.

  The control unit 31 controls the inverter 32 to lower the maximum value of the rotation speed of the rotor of the expander (maximum value in the rotation speed range in which the life of the bearing can be shortened and the occurrence of resonance can be avoided). Control is performed so that the expander 12 is driven within a range equal to or lower than an upper limit value that is a rotational speed that is a preset rotational speed. In the present embodiment, an amount of working medium that enables rotation at the upper limit value of the rotor circulates in the circulation flow path 15, and the control unit 31 receives the power generated by the generator 16 as the request. Control is performed so as to limit the number of rotations of the rotor so that the amount corresponds to the electric power. Details of the control contents of the control unit 31 will be described later. Further, the control unit 31 controls the inverter 32 to increase / decrease the rotational speed of the circulation pump 14 in accordance with the increase / decrease of the rotational speed of the expander 12.

  Here, the rotation speed of the expander 12 according to the required power is calculated by the control unit 31 as follows. That is, the control unit 31 determines the difference between the suction side enthalpy calculated based on the values detected by the suction side detection means 21 and 22 and the enthalpy (discharge side enthalpy) of the discharge side working medium of the expander 12 and Based on the required power, the target rotational speed of the expander 12 (the rotational speed at which an amount of power corresponding to the required power is generated from the generator 16) is calculated.

  If the value detected by the suction side detection means 21 and 22 decreases, the suction side enthalpy decreases and the amount of power generated by the generator 16 decreases. Therefore, the upper limit correction unit 35 includes the suction side detection means 21 and 22. As the value detected in (1) decreases, the upper limit value is corrected to increase. As a result, the range in which the control unit 31 can increase the rotational speed of the expander 12 is widened, so that the control unit 31 increases the rotational speed of the expander 12, thereby reducing the suction side enthalpy. The reduction in the amount of power generated is suppressed.

  Here, the reason why the power generation amount in the generator 16 is reduced due to the reduction in the suction side enthalpy will be described with reference to FIG. 2 (Mollier diagram showing the state change of the working medium).

  A point A in FIG. 2 indicates the state of the working medium flowing into the expander 12, that is, the state of the working medium before being expanded by the expander 12, and a point B is the working medium after being expanded by the expander 12, that is, The state of the working medium discharged | emitted from the expander 12 is shown. Point C indicates the state of the working medium discharged from the condenser 13, and point D indicates the state of the working medium flowing into the evaporator 11. Theoretically, the energy that can be extracted by the expander 12 is the difference Δh between the specific enthalpy at the point A and the specific enthalpy at the point B, and depends on the value obtained by multiplying the difference Δh by the flow rate of the working medium. Thus, the amount of power generated by the generator 16 is determined. The control unit 31 controls the rotational speed of the expander 12 so that the flow rate of the working medium in the expander 12 becomes the flow rate of the working medium calculated from the required power and the difference Δh.

  Further, FIG. 2 shows a change in the state of the working medium when the evaporation temperature in the evaporator 11 is lowered from 80 ° C. to 70 ° C., that is, when the suction side enthalpy is lowered. When the evaporation temperature in the evaporator 11 is 70 ° C., points corresponding to the points A, B and D are indicated as points A ′, B ′ and D ′, respectively. The energy that can be extracted by the expander 12 in this state is the difference Δh ′ between the specific enthalpy at the point A ′ and the specific enthalpy at the point B ′, and this difference Δh ′ is smaller than the difference Δh. . Therefore, the power generation amount generated by the generator 16 when the evaporation temperature in the evaporator 11 is 70 ° C. is reduced as compared with that when the evaporation temperature in the evaporator 11 is 80 ° C.

  Next, the control content of the control part 31 is demonstrated, referring FIG.

  The control part 31 compares the electric power generation amount produced | generated with the generator 16, and the request | requirement electric power from the apparatus 40 after receiving the starting instruction | indication of an electric power generating apparatus (step ST11).

  As a result, when the power generation amount is excessive, that is, when the power generation amount is larger than the required power, the control unit 31 calculates the target rotational speed of the expander 12 (step ST12), and the rotational speed of the expander 12 The rotational speed is decreased until becomes the target rotational speed (step ST13). As a result, the amount of power generated by the generator 16 decreases until it reaches the required power. At this time, the control unit 31 also decreases the rotational speed of the circulation pump 14 so that the amount of the working medium flowing into the expander 12 decreases. On the other hand, if the power generation amount is appropriate as a result of the comparison in step ST11, that is, if the power generation amount matches the required power, the control unit 31 does not change the current rotation speed of the expander 12. And as a result of the comparison in step ST11, when the power generation amount is too small, that is, when the power generation amount is smaller than the required power, the control unit 31 is preset with the value detected by the coil temperature detection means. It is determined whether the coil temperature is less than the upper limit value (step ST14).

  If the value detected by the coil temperature detecting means is equal to or greater than the upper limit value of the coil temperature, the rotational speed of the expander 12 is reduced and the coil temperature is reduced (step ST15). On the other hand, if the value detected by the coil temperature detecting means is less than the upper limit value of the coil temperature, the controller 31 determines that the value detected by the current value detecting means is less than the preset upper limit value of the current value. It is determined whether or not there is (step ST16).

  If the value detected by the current value detection means is equal to or greater than the upper limit value of the current value, the current value is reduced by reducing the rotational speed of the expander 12 as necessary (step ST17). If the value detected by the current value detection means is less than the upper limit value of the current value, the control unit 31 determines that the value detected by the oil discharge temperature value detection means is less than the preset upper limit value of the oil discharge temperature. Is determined (step ST18).

  If the value detected by the oil discharge temperature detecting means is equal to or higher than the upper limit value of the oil discharge temperature, the oil discharge temperature of the bearing is reduced by reducing the rotational speed of the expander 12 as necessary (step ST19). ). If the value detected by the exhaust oil temperature detecting means is less than the upper limit value of the exhaust oil temperature, the control unit 31 calculates the target rotational speed of the expander 12 (step ST20).

  Note that step ST14, step ST16, and step ST18 may be executed in any order. Further, any one or two or all of these steps ST14, ST16 and ST18 may be omitted. In this case, step ST15, step ST17, and step ST19 are also omitted.

  Subsequently, the control unit 31 compares the rotational speed with the target rotational speed (step ST21), and determines whether the target rotational speed is less than the upper limit value (step ST22).

  If the target rotational speed is less than the upper limit value, the rotational speed is set to the target rotational speed (step ST23). On the other hand, if the target rotational speed is equal to or higher than the upper limit value, the rotational speed is set to the upper limit value (step ST24). As a result, the amount of power generated by the generator 16 increases until it reaches the required power or approaches the required power. At this time, the control unit 31 also increases the rotation speed of the circulation pump 14 so that the amount of the working medium flowing into the expander 12 increases.

  Next, the control content of the upper limit correction unit 35 will be described with reference to FIG.

  The upper limit correction unit 35 determines whether or not to change the upper limit based on the suction pressure detection result of the suction side pressure sensor 21 (step ST31) (step ST32). If it is determined that the upper limit value is to be changed, it is determined whether the upper limit value is less than the maximum value (step ST33). If the upper limit value is less than the maximum value, the upper limit value is changed (step ST34). Of course, if the upper limit value is the maximum value, the upper limit value is maintained at the maximum value. In the power generation device, by changing the upper limit value, when the required power is constant and the value detected by the suction side pressure sensor 21 decreases in a state where the rotation speed of the expander 12 is the upper limit value, the required power In order to satisfy the condition, the flow rate of the working medium flowing into the expander 12 (the rotation speed of the expander 12) can be increased. Note that the operation of changing the upper limit value by the upper limit correction unit 35 may be performed at regular intervals or continuously.

  Next, the relationship between the suction pressure and the upper limit value will be described with reference to FIG. As shown in FIGS. 5A to 5C, the upper limit value gradually increases to the maximum value as the suction pressure decreases.

  4 and 5 show an example in which the upper limit correction unit 35 changes the upper limit based on the value detected by the suction-side pressure sensor 21, but the upper limit correction unit 35 has an evaporator side temperature. The upper limit value may be changed based on the value detected by the sensor 22. In this case, similarly to the relationship shown in FIGS. 5A to 5C, the upper limit value gradually increases to the maximum value as the temperature of the heating medium supplied to the evaporator 11 decreases.

  As described above, in the conventional binary power generation device, the ambient temperature such as the temperature of the heating medium and the temperature of the cooling medium is decreased, and the enthalpy of the working medium flowing into the expander 12 and the working medium flowing out into the expander 12 are reduced. When the difference from enthalpy is reduced, the amount of power generation is reduced. On the other hand, in the power generator according to this embodiment, the upper limit correction unit 35 is provided, so that the upper limit increases within a range less than the maximum value as the values detected by the suction side detection units 21 and 22 decrease. Therefore, the range in which the control unit 31 can increase the rotation speed of the expander 12 is widened, thereby compensating for the shortage of the power generation amount due to the decrease in the ambient temperature, that is, the variation in the power generation amount due to the change in the ambient temperature. Can be suppressed. Therefore, power is stably supplied to the device 40. Here, since the upper limit value is a rotational speed less than the maximum value, a stable driving state of the expander 12 is ensured. Moreover, in the power generator of this embodiment, since the rotation speed of the expander 12 is changed by the control unit 31 according to the required power of the device 40, the generator 16 generates power that follows the change in the required power. Is possible. As a result, it is possible to achieve both the generation of power following the change in the required power of the device 40 and the suppression of fluctuations in the amount of power generated due to the change in the ambient temperature.

  In addition, the power generation apparatus of the present embodiment includes a coil temperature detection unit, and the control unit 31 has a coil temperature in which the value detected by the coil temperature detection unit is set in advance even when the required power is increased. Since the rotation speed of the expander 12 is not increased when it is not less than the upper limit value, the generation of power following the change in required power of the device 40 and the change in ambient temperature are avoided while avoiding damage to the coil of the generator 16. Both suppression of fluctuations in power generation due to this are achieved.

  Furthermore, the power generation apparatus of the present embodiment further includes a current value detection unit, and the control unit 31 has a current detected in advance by the value detected by the current value detection unit even when the required power is increased. Since the rotation speed of the expander 12 is not increased when the value is not less than the upper limit value, damage to the generator 16 is avoided, and power generation following the change in the required power of the device 40 and the change in the ambient temperature are caused. Both suppression of fluctuations in the amount of power generated is achieved.

  In addition, the power generation device of this embodiment includes an oil discharge temperature detection unit, and the control unit 31 is preset with a value detected by the oil discharge temperature detection unit even when the required power increases. When the exhaust oil temperature is not less than the upper limit value, the rotation speed of the expander 12 is not increased, so that damage to the expander 12 is avoided and generation of power following the change in required power of the device 40 and the ambient temperature Both suppression of fluctuations in the amount of power generated due to the change is achieved.

  Moreover, since the control part 31 of this embodiment increases / decreases the rotation speed of the circulation pump 14 according to increase / decrease in the rotation speed of the expander 12, it matched with the said rotation speed according to increase / decrease in the rotation speed of the expander 12. An amount of working medium circulates in the circulation channel 15. Therefore, the rotational drive of the rotor of the expander 12 becomes smooth.

(Second embodiment)
A second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, only the parts different from the first embodiment will be described, and the description of the same structure, operation, and effect as in the first embodiment will be omitted.

  The power generation device of this embodiment includes a discharge side pressure sensor 23 and a condenser side temperature sensor 24 instead of the suction side pressure sensor 21 and the evaporator side temperature sensor 22 of the first embodiment.

  The discharge side pressure sensor 23 is provided between the expander 12 and the condenser 13 in the circulation channel 15 and detects the pressure of the working medium discharged from the expander 12. The condenser-side temperature sensor 24 is provided in the supply flow path 18 and detects the temperature of the cooling medium supplied to the condenser 13. Based on the discharge pressure (pressure on the discharge side of the expander 12) detected by the discharge side pressure sensor 23 or the temperature of the cooling medium detected by the condenser side temperature sensor 24, the operation on the discharge side of the expander 12 is performed. The discharge enthalpy of the medium is calculated. That is, at least one of the discharge side pressure sensor 23 and the condenser side temperature sensor 24 constitutes a discharge side detection means. Instead of the discharge side pressure sensor 23, a discharge side temperature sensor that detects the temperature of the working medium discharged from the expander 12 may be used.

  In the present embodiment, the upper limit correction unit 35 corrects the upper limit according to the values detected by the discharge side detection means 23 and 24. For example, the upper limit correction unit 35 corrects the upper limit value so as to increase in a range less than the maximum value as the values detected by the discharge side detection means 23 and 24 increase.

  Here, the amount of power generated by the generator 16 decreases due to the increase in the discharge side enthalpy, and the reason will be described with reference to FIG. 7 (Mollier diagram showing the state change of the working medium).

  A point A in FIG. 7 indicates a working medium flowing into the expander 12, that is, a working medium before being expanded by the expander 12, and a point B is a working medium after being expanded by the expander 12, that is, expansion. The working medium discharged | emitted from the machine 12 is shown. Point C indicates the working medium discharged from the condenser 13, and point D indicates the working medium that flows into the evaporator 11. Therefore, theoretically, the energy that can be extracted by the expander 12 is the difference Δh between the specific enthalpy at the point A and the specific enthalpy at the point B, and a value obtained by multiplying the difference Δh by the flow rate of the working medium is a generator. 16 is the amount of power generated.

  Further, FIG. 7 shows the state change of the working medium when the condensation temperature in the evaporator 11 increases from 30 ° C. to 40 ° C., that is, when the discharge side enthalpy increases. When the condensation temperature in the condenser 13 is 40 ° C., points corresponding to point B, point C and point D are indicated as point B ′, point C ′ and point D ′, respectively. The energy that can be extracted by the expander 12 in this state is the difference Δh ′ between the specific enthalpy at the point A ′ and the specific enthalpy at the point B ′, and this difference Δh ′ is smaller than the difference Δh. . Therefore, the amount of power generated by the generator 16 when the condensation temperature in the condenser 13 is 40 ° C. is reduced as compared with that when the condensation temperature in the condenser 13 is 30 ° C.

  In addition, the control content of the control part 31 is the same as that of 1st embodiment. The control content of the upper limit correction unit 35 is the same as that of the first embodiment except that the upper limit correction unit 35 corrects the upper limit based on the values detected by the discharge side detection means 23 and 24. Since there is, explanation is omitted.

  Next, the relationship between the discharge pressure and the upper limit value will be described with reference to FIG. As shown in FIGS. 8A to 8C, the upper limit value gradually increases to the maximum value as the discharge pressure increases.

  In the second embodiment, an example is shown in which the upper limit correction unit 35 changes the upper limit based on the value detected by the discharge-side pressure sensor 23. However, the upper limit correction unit 35 includes a condenser side temperature sensor. The upper limit value may be changed based on the value detected at 24. In this case, similarly to the relationships shown in FIGS. 8A to 8C, the upper limit value gradually increases to the maximum value as the temperature of the cooling medium supplied to the condenser 13 increases.

  Thus, in the power generation device of the present embodiment, the upper limit correction unit 35 increases the upper limit in a range less than the maximum value as the values detected by the discharge side detection means 23 and 24 increase. The same effect as that of the embodiment can be obtained.

(Third embodiment)
A second embodiment of the present invention will be described with reference to FIGS. In addition, also about this 3rd embodiment, only a different part from 1st embodiment is demonstrated, and description of the same structure, an effect | action, and an effect as 1st embodiment is abbreviate | omitted.

  The power generation device of the present embodiment includes a discharge side pressure sensor 23 and a condenser side temperature sensor 24 in addition to the suction side pressure sensor 21 and the evaporator side temperature sensor 22 of the first embodiment. The discharge side pressure sensor 23 and the condenser side temperature sensor 24 are the same as those described in the second embodiment.

  In the present embodiment, the upper limit correction unit 35 corrects the upper limit based on both the values detected by the suction side detection means 21 and 22 and the values detected by the discharge side detection means 23 and 24. Specifically, the upper limit correction unit 35 is a difference obtained by subtracting the value detected by the discharge side detection means 23, 24 from the value detected by the suction side detection means 21, 22 (or the absolute value of the difference). Alternatively, as the ratio of the value detected by the suction side detection means 21, 22 to the value detected by the discharge side detection means 23, 24 decreases, the upper limit value is raised within the range below the maximum value. to correct.

  Note that the amount of power generated by the generator 16 is reduced due to a decrease in the suction-side enthalpy or an increase in the discharge-side enthalpy, and the reason is as described in the above embodiments.

  Moreover, the control content of the control part 31 is the same as that of 1st embodiment. The control content of the upper limit correction unit 35 is the difference obtained by subtracting the value detected by the discharge side detection means 23, 24 from the value detected by the suction side detection means 21, 22 (or the upper limit correction unit 35). The absolute value of the difference (the same applies hereinafter) or except that the upper limit value is corrected based on the ratio of the value detected by the suction side detection means 21, 22 to the value detected by the discharge side detection means 23, 24. Since it is the same as that of 1st embodiment, the description is abbreviate | omitted.

  Here, as an example, the relationship between the difference between the suction pressure and the discharge pressure and the upper limit value will be described with reference to FIG. As shown in FIGS. 10A to 10C, the upper limit value gradually increases to the maximum value as the difference between the suction pressure and the discharge pressure decreases.

  FIG. 10 shows an example in which the upper limit correction unit 35 changes the upper limit based on the difference between the value detected by the suction side pressure sensor 21 and the value detected by the discharge side pressure sensor 23. The upper limit correction unit 35 may change the upper limit based on the ratio of the value detected by the suction side pressure sensor 21 to the value detected by the discharge side pressure sensor 23, or the evaporator side temperature sensor 22. The upper limit value may be changed based on the difference between the detected value and the value detected by the condenser-side temperature sensor 24. Furthermore, the evaporator-side value relative to the value detected by the condenser-side temperature sensor 24 may be changed. The upper limit value may be changed based on the ratio of the values detected by the temperature sensor 22. In these cases, similarly to the relationship shown in FIGS. 10A to 10C, the upper limit value gradually increases to the maximum value as the difference or the ratio decreases.

  Thus, in the power generation device of the present embodiment, the upper limit correction unit 35 has a difference between the value detected by the suction side detection means 21 and 22 and the value detected by the discharge side detection means 23 and 24, or As the ratio of the value detected by the suction side detection means 21 and 22 to the value detected by the discharge side detection means 23 and 24 decreases, the upper limit value is raised within the range below the maximum value. The same effect as the form can be obtained.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent. In the third embodiment, the ratio of the value detected by the discharge side detection means 23, 24 to the value detected by the suction side detection means 21, 22 is obtained, and the upper limit of the rotational speed of the expander 12 increases as the ratio increases. The value may be gradually increased to the maximum value. Further, a difference obtained by subtracting the value detected by the suction side detection means 21, 22 from the value detected by the discharge side detection means 23, 24 is obtained, and the upper limit value is gradually increased to the maximum value as the difference increases. Also good.

  In the above embodiment, when a cooler such as a cooling jacket or a cooling fan for cooling the generator with the coolant is provided, the coil temperature is reduced by increasing the cooling capacity of the cooler in step ST15. Also good. Similarly, when a cooler that cools the oil discharge temperature is provided, the oil discharge temperature may be reduced by increasing the cooling capacity of the cooler in step ST19. Thus, methods other than the method of reducing the rotation speed of the expander 12 may be used in the step of reducing the coil temperature and the step of reducing the oil discharge temperature. In step ST17, the operation for reducing the current value may be performed electrically.

DESCRIPTION OF SYMBOLS 11 Evaporator 12 Expander 13 Condenser 14 Circulation pump 15 Circulation flow path 16 Generator 17 Supply flow path 18 Supply flow path 21 Suction side pressure sensor 22 Evaporator side temperature sensor 23 Discharge side pressure sensor 24 Condenser side temperature sensor 30 Control means 31 Control unit 35 Upper limit correction unit 40 Device

Claims (7)

  1. An evaporator for evaporating the working medium;
    An expander including a rotor that is rotationally driven by the expansion energy of the working medium evaporated in the evaporator;
    A condenser for condensing the working medium discharged from the expander;
    A circulation pump for sending the working medium condensed in the condenser to the evaporator;
    A generator driven by expansion of the working medium in the expander;
    A suction side detection means capable of detecting a value used for calculating a state quantity of the working medium flowing into the expander;
    Requested by a device that is lower than the maximum value of the number of rotations of the rotor and within a range equal to or less than an upper limit value that is a preset number of rotations and that is supplied with power generated by the generator. A control unit for controlling the rotational speed of the expander according to the required power
    A power generator comprising: an upper limit correction unit configured to correct the upper limit so as to increase within a range less than the maximum as the value detected by the suction side detection unit decreases.
  2. An evaporator for evaporating the working medium;
    An expander including a rotor that is rotationally driven by the expansion energy of the working medium evaporated in the evaporator;
    A condenser for condensing the working medium discharged from the expander;
    A circulation pump for sending the working medium condensed in the condenser to the evaporator;
    A generator driven by expansion of the working medium in the expander;
    Discharge side detection means capable of detecting a value used for calculating the state quantity of the working medium discharged from the expander;
    Requested by a device that is lower than the maximum value of the number of rotations of the rotor and within a range equal to or less than an upper limit value that is a preset number of rotations and that is supplied with power generated by the generator. A control unit for controlling the rotational speed of the expander according to the required power
    A power generator comprising: an upper limit correction unit configured to correct the upper limit so as to increase within a range less than the maximum as the value detected by the discharge side detection unit increases.
  3. An evaporator for evaporating the working medium;
    An expander including a rotor that is rotationally driven by the expansion energy of the working medium evaporated in the evaporator;
    A condenser for condensing the working medium discharged from the expander;
    A circulation pump for sending the working medium condensed in the condenser to the evaporator;
    A generator driven by expansion of the working medium in the expander;
    A suction side detection means capable of detecting a value used for calculating a state quantity of the working medium flowing into the expander;
    Discharge side detection means capable of detecting a value used for calculating the state quantity of the working medium discharged from the expander;
    Requested by a device that is lower than the maximum value of the number of rotations of the rotor and within a range equal to or less than an upper limit value that is a preset number of rotations and that is supplied with power generated by the generator. A control unit for controlling the rotational speed of the expander according to the required power
    The difference between the value detected by the suction side detection means and the value detected by the discharge side detection means, or the ratio of the value detected by the suction side detection means to the value detected by the discharge side detection means A power generator comprising: an upper limit correction unit configured to correct the upper limit to be changed in a range less than the maximum value based on the change in the value.
  4. The power generator according to any one of claims 1 to 3,
    Coil temperature detecting means for detecting the coil temperature of the generator is further provided,
    The said control part is an electric power generating apparatus which reduces the rotation speed of the said expander, when the value detected by the said coil temperature detection means is more than the upper limit of the preset coil temperature.
  5. The power generator according to any one of claims 1 to 4,
    A current value detection means for detecting a value of the current generated by the generator;
    The said control part is a power generator which reduces the rotation speed of the said expander, when the value detected by the said current value detection means is more than the upper limit of the preset current value.
  6. The power generator according to any one of claims 1 to 5,
    An oil temperature detecting means for detecting an oil temperature discharged from the expander bearing;
    The said control part is an electric power generating apparatus which reduces the rotation speed of the said expander, when the value detected by the said waste oil temperature detection means is more than the upper limit value of the preset waste oil temperature.
  7. The power generator according to any one of claims 1 to 6,
    The said control part is an electric power generating apparatus which increases / decreases the rotation speed of the said circulation pump according to increase / decrease in the rotation speed of the said expander.
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US6981377B2 (en) * 2002-02-25 2006-01-03 Outfitter Energy Inc System and method for generation of electricity and power from waste heat and solar sources
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