JP2012202374A - Power generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power generation device inhibiting the generation of cavitation in a pump circulating a working medium while avoiding complication of the construction.SOLUTION: The power generation device includes: a pressure sensor 11 provided in a flow passage between a condenser 3 and the pump 4 in a circulation flow passage 6 and detecting pressure of the working medium on an inlet side of the pump 4; a temperature sensor 12 provided in the flow passage between the condenser 3 and the pump 4 in the circulation flow passage 6 and detecting temperature of the working medium on the inlet side of the pump 4; a derivation means 21 deriving the saturated steam pressure of the working medium on the inlet side of the pump 4 from the detected value of the temperature sensor 12; and a regulation and control means 23 regulating a circulation amount of the working medium according to a differential pressure between the saturated steam pressure derived by the derivation means 21 and the pressure of the working medium detected by the pressure sensor 11.

Description

  The present invention relates to a power generator.

  In recent years, from the viewpoint of energy saving, there is an increasing need for a power generation apparatus that recovers so-called “waste heat” from various facilities such as factories and generates power using the recovered “waste heat” energy. .

  As such a power generation device, for example, an exhaust heat power generation device as disclosed in Patent Document 1 is known. The exhaust heat power generation apparatus disclosed in Patent Document 1 circulates a working fluid evaporator, a turbine for causing the working fluid vapor to perform expansion work, a condenser for condensing the working fluid vapor, and the working fluid. A closed-loop circulation flow path connected in series with a circulation pump for generating the flow. In this circulation channel, a heat cycle is performed when the working fluid circulates, while the generator is driven by the turbine. In particular, among the exhaust heat power generation apparatus, a binary power generation system using a Rankine cycle in which a turbine or an expander (expander) is driven by a low-boiling working medium is known.

  An exhaust heat power generation apparatus disclosed in Patent Document 1 includes a steam generator that recovers exhaust heat to generate high-pressure working medium steam as a working medium, a turbine that expands the high-pressure working medium steam, and a low pressure from the turbine. A condenser for condensing the steam and a working medium circulation pump for circulating the working medium are provided. These devices are connected by a working medium circuit, and a gas-liquid separator is disposed between the steam generator and the turbine. In this gas-liquid separator, the working medium vapor separated from the working medium liquid is introduced into the turbine.

  In the exhaust heat power generation apparatus described above, it is necessary to dispose a circulation pump in order to circulate the working medium in the circulation flow path, and this circulation pump is located upstream of the circulation pump. The working medium condensed and liquefied by the condenser is sucked. The circulation pump is responsible for delivering the liquefied working medium to a steam generator located downstream.

  Circulation pumps require measures to prevent cavitation from occurring. Cavitation is a phenomenon in a fluid machine where the pressure of a medium (liquid) flowing inside the fluid machine locally reaches a saturated vapor pressure, causing the medium to boil and generating small bubbles. When the bubbles are crushed, so-called erosion occurs in the components of the fluid machine due to the impact pressure. For example, if the fluid machine is a turbo type fluid machine, the impeller (impeller) which is a main part thereof is damaged. When cavitation occurs in the circulation pump, it is forced to stop the operation of the entire system of the power generation apparatus for maintenance of the circulation pump. Therefore, a measure for preventing the occurrence of cavitation of the circulation pump is important.

  In addition to the above-described configuration, the exhaust heat power generator disclosed in Patent Document 1 includes a circulation amount control means for controlling a circulation amount for circulating the working medium from the condenser to the steam generator, and separation in the gas-liquid separator. A liquid level detector for detecting the liquid level is provided. The separation liquid (working medium) separated by the gas-liquid separator is guided to the condenser via the flow rate control means, and the separation liquid level in the gas-liquid separator detected by the liquid level detector is at a predetermined level. Thus, the circulation amount control means controls the circulation amount of the working medium.

  The exhaust heat power generator is provided with a heat recovery device. The heat recovery unit is provided in a path for guiding the separated liquid from the gas-liquid separator to the condenser, and performs heat exchange between the separated liquid and the working medium sent from the condenser to the steam generator.

Japanese Patent No. 4557793

  In the exhaust heat power generator disclosed in Patent Document 1, since measures for preventing the cavitation of the circulation pump are not taken, cavitation may occur in the circulation pump. In addition, the exhaust heat power generation apparatus includes a gas-liquid separator disposed between the steam generator and the turbine, and a liquid level detector that detects the separated liquid level in the gas-liquid separator. The configuration of the exhaust heat power generator is complicated.

  Therefore, the present invention has been made in view of the above prior art, and an object of the present invention is to suppress the occurrence of cavitation in a pump that circulates a working medium while avoiding a complicated configuration. It is to provide a power generating device to obtain.

  To achieve the above object, the present invention provides a steam generating means for evaporating the working medium liquid, an expander for expanding the working medium steam, a condensing means for condensing the working medium steam, and a pump for circulating the working medium. , Comprising a closed loop circulation channel connected in series and driving a generator with the expander, provided in a channel between the condensing means and the pump in the circulation channel A working medium pressure detecting means for detecting the pressure of the working medium on the inlet side of the pump, and an operation on the inlet side of the pump provided in a flow path between the condensing means and the pump in the circulation flow path. A working medium temperature detecting means for detecting the temperature of the medium; a deriving means for deriving a saturated vapor pressure of the working medium on the inlet side of the pump from a detection value of the working medium temperature detecting means; and The amount of circulation of the working medium or the amount of cooling medium supplied to the condensing means is determined according to the differential pressure between the saturated vapor pressure derived in this way and the pressure of the working medium detected by the working medium pressure detecting means. And an adjustment control means for adjusting.

  In the present invention, in accordance with the differential pressure between the saturated vapor pressure derived from the temperature of the working medium on the pump inlet side and the pressure of the working medium on the pump inlet side detected by the working medium pressure detection means, Since the amount of circulating refrigerant or the amount of cooling medium supplied to the condensing means is adjusted, the pressure of the working medium on the pump inlet side can be maintained higher than the saturated vapor pressure, and temporarily out of that state. Even if there is, it is possible to return to that state in a short time. For this reason, it becomes possible to prevent the occurrence of cavitation in the pump or to suppress the occurrence of cavitation. In addition, since it is not necessary to detect the liquid level in the gas-liquid separator, the gas-liquid separator and the liquid level detector are not required, and the configuration can be prevented from becoming complicated.

  Here, the adjustment control means may adjust the circulation amount of the working medium by adjusting a delivery flow rate of the working medium by the pump.

  On the other hand, a return flow path may be connected to the circulation flow path so as to bypass the pump, and a return adjustment valve may be provided in the return flow path. In this case, the adjustment control may be performed. The means may adjust the circulation amount of the working medium by controlling the reflux adjusting valve.

  Further, the adjustment control means may adjust the supply amount of the cooling medium supplied to the condensing means by controlling a flow rate adjusting valve disposed in a cooling flow path to which the cooling medium communicates.

  Further, in the case where it has a discharge pressure detection means that is provided at a position downstream of the pump in the circulation flow path and detects the pressure of the working medium sent from the pump to the steam generation means, the adjustment control means Is a differential pressure between the saturated vapor pressure derived by the working medium pressure detected by the discharge pressure detecting means or by the derivation means and the pressure of the working medium detected by the working medium pressure detecting means. According to the above, the circulation amount of the working medium may be adjusted.

  The present invention provides a closed loop in which a steam generating means for evaporating a working medium liquid, an expander for expanding the working medium steam, a condensing means for condensing the working medium steam, and a pump for circulating the working medium are connected in series. A power generation device that includes a circular circulation channel and drives a generator with the expander, provided at a position downstream of the pump in the circulation channel, and sent from the pump to the steam generation means A discharge pressure detecting means for detecting the pressure of the working medium; and an adjustment control means for adjusting a circulation amount of the working medium according to the pressure of the working medium detected by the discharge pressure detecting means. is there.

  In the present invention, the pressure of the working medium sent from the pump to the steam generating means is detected by the discharge pressure detecting means, and the adjustment control means adjusts the circulation amount of the working medium in accordance with the detected pressure. For this reason, even if cavitation occurs, it is possible to quickly escape from that state. For this reason, it becomes possible to suppress the occurrence of cavitation in the pump. In addition, since it is not necessary to detect the liquid level in the gas-liquid separator, the gas-liquid separator and the liquid level detector are not required, and the configuration can be prevented from becoming complicated.

  As described above, according to the present invention, it is possible to suppress the occurrence of cavitation in the pump that circulates the working medium while avoiding the complicated configuration.

It is a figure showing roughly the composition of the power generator concerning a 1st embodiment of the present invention. It is a flowchart for demonstrating control operation | movement when adjusting the output of a pump in the said electric power generating apparatus. It is a flowchart for demonstrating control operation | movement when adjusting the output of a pump in the modification of the said electric power generating apparatus. It is a figure which shows schematically the structure of the electric power generating apparatus which concerns on 2nd Embodiment of this invention. It is a flowchart for demonstrating control operation when adjusting the output of a pump in the electric power generating apparatus which concerns on 2nd Embodiment. It is a figure which shows schematically the structure of the electric power generating apparatus which concerns on 3rd Embodiment of this invention. It is a flowchart for demonstrating control operation when adjusting the output of a pump in the electric power generating apparatus which concerns on 3rd Embodiment. It is a figure which shows schematically the structure of the electric power generating apparatus which concerns on 4th Embodiment of this invention. It is a flowchart for demonstrating control operation | movement when adjusting the output of a pump in the electric power generating apparatus which concerns on 4th Embodiment. It is a figure for demonstrating the fluctuation state of the discharge pressure of a pump. It is a flowchart for demonstrating control operation | movement when adjusting the output of a pump in the electric power generating apparatus which concerns on 5th Embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 shows a configuration of a power generation apparatus 100 according to the first embodiment of the present invention. The power generation apparatus 100 is composed of one power generation cycle 50. The power generation cycle 50 includes a closed loop circulation channel 6 provided with an expander 1, a condenser (condensing means) 3, a pump 4, and an evaporator (steam generator, steam generating means) 5. Yes. The circulation channel 6 is filled with a fluorocarbon heat medium (for example, R245fa) as a working medium. A heat medium having a boiling point lower than that of water is used as the working medium, and the power generation apparatus 100 according to the present embodiment is configured as a binary power generation apparatus.

  The expander 1 is disposed on the downstream side of the evaporator 5 in the circulation channel 6, and extracts the kinetic energy from the working medium by expanding the working medium (vapor) evaporated in the evaporator 5. The expander 1 is configured by, for example, a screw expander. The screw expander has a configuration in which a pair of male and female screw rotors (not shown) are accommodated in a rotor chamber (not shown) formed in the expander casing, and is supplied from the intake port 1s through the circulation passage 6. The screw rotor is rotated by the expansion force of the working medium. Then, the working medium that has expanded in the rotor chamber and has a reduced pressure is exhausted from the discharge port 1 d to the circulation flow path 6.

  A power generator 2 is connected to the expander 1, and the power generator 2 is driven by the expander 1. The generator 2 has a configuration in which a stator (not shown) and a rotor (not shown) are accommodated in an internal space (not shown) of the generator casing. The rotor is integrally formed with the screw rotor of the expander 1, and rotates with the rotation of the screw rotor to generate electric power in the stator windings. The expander 1 and the generator 2 constitute power generation means.

  The condenser 3 is disposed on the downstream side of the expander 1 in the circulation channel 6, and the working medium discharged from the discharge port 1 d of the expander 1 to the circulation channel 6 is introduced into the condenser 3. In the condenser 3, the working medium is condensed into a liquid by heat exchange with cooling water (cooling medium) flowing through a circuit (cooling medium flow path 8) different from the circulation flow path 6. That is, the condenser 3 has a passage through which the cooling medium flows and a passage through which the working medium flows, and exchanges heat between the cooling medium and the working medium.

  The working medium that has become liquid is pressurized to a predetermined pressure by the pump 4 and sent to the evaporator 5. The evaporator 5 is for generating vapor by evaporating the working medium (liquid) flowing through the circulation flow path 6. For example, the heat medium flowing through the heat medium flow path 7 different from the circulation flow path 6. The working medium is heated by (for example, low pressure steam). That is, the evaporator 5 has a passage through which a working medium flows and a passage through which a heat medium supplied from an external heat source flows, and performs heat exchange between the heat medium and the working medium. The working medium vaporized by exchanging heat with the heat medium in the evaporator 5 becomes saturated steam (or superheated steam) and is re-supplied to the expander 1.

  The heat medium (heating medium) supplied to the evaporator 5 via the heat medium flow path 7 includes steam collected from a well (steam well), surplus steam discharged from a factory, etc., as well as solar heat. As a heat source, steam generated from a condenser, a boiler using biomass or fossil fuel as a heat source, or other equipment is assumed. On the other hand, the cooling medium supplied to the condenser 3 via the cooling medium flow path 8 is assumed to be cooling water produced by a cooling tower.

  The pump 4 is provided to circulate the working medium in the circulation flow path 6, and is disposed on the downstream side of the condenser 3 in the circulation flow path 6. That is, the pump 4 is provided in a pipe connecting the condenser 3 and the evaporator 5 in the circulation channel 6, sucks the working medium (liquid) on the condenser 3 side, and discharges it to the evaporator 5 side. To do. As the pump 4, 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 preferably used.

  The power generation device 100 includes a control device 10. The control device 10 includes input / display means (not shown) such as a touch panel.

  In the circulation flow path 6 between the condenser 3 and the pump 4, a pressure sensor 11 as an example of working medium pressure detecting means for detecting the pressure Ps of the working medium on the inlet side of the pump 4, and the inlet side of the pump 4 There is provided a temperature sensor 12 as an example of a working medium temperature detecting means for detecting the temperature Ts of the working medium. Signals corresponding to the detected pressure Ps and temperature Ts of the working medium are input to the control device 10.

  The control device 10 includes a ROM, a RAM, a CPU, and the like, and exhibits a predetermined function by executing a program stored in the ROM. The functions of the control device 10 include a derivation unit 21, an adjustment control unit 23, and the like.

  The deriving means 21 derives the saturated vapor pressure of the working medium at the inlet of the pump 4 from the detected value of the temperature sensor 12. That is, the control device 10 stores an information table that correlates the temperature of the working medium and the saturated steam pressure, and a function expression described later, and the derivation means 21 uses this table and the function expression to saturate the working medium. Derived steam pressure.

  The adjustment control unit 23 calculates a difference (differential pressure) between the saturated vapor pressure derived by the deriving unit 21 and the pressure of the working medium detected by the pressure sensor 11, and according to the derived differential pressure. The output of the pump 4 is adjusted. The pump 4 receives the control signal from the control device 10, changes the rotational speed of the rotor of the pump 4, and adjusts the delivery flow rate of the working medium delivered from the pump 4.

  Here, the control operation of the power generator 100 when adjusting the output (rotation speed) of the pump 4 will be described with reference to FIG. The main power generation cycle operation of the power generation apparatus 100 is already controlled in the initial state, that is, step ST1, by another control flow, and the rotation speed of the rotor of the pump 4 is also the target rotation in the other control flow. It is assumed that the number has been adjusted.

  In step ST1, the variable i held in the control device 10 is set to an initial value 0, and the rotation speed adjustment amount Δr is set to an initial value Δr0.

  Then, the pressure sensor 11 detects the pressure Ps of the working medium on the inlet side of the pump 4, and the temperature sensor 12 detects the temperature Ts of the working medium on the inlet side of the pump 4 (step ST2).

Next, in step ST3, the control device 10 derives the saturated vapor pressure Pth (Ts) from the temperature Ts detected by the temperature sensor 12. A functional equation is recorded in advance in the control device 10, and the control device 10 derives a saturated vapor pressure Pth (Ts) from the functional equation and the detected temperature Ts. In general, the saturated vapor pressure is uniquely determined based on the saturated vapor pressure curve and the temperature specified for each working medium. Here, the saturated vapor pressure is derived from a functional expression with respect to the temperature Ts. To do. A functional equation for deriving the saturated vapor pressure Pth (Ts) is, for example, as follows.
Pth (Ts) = 6.21 × 10 ⁻⁷ Ts ³
+ 3.13 × 10 ⁻⁵ Ts ²
+ 2.73 × 10 ⁻³ Ts
+ 1.54 × 10 ⁻¹

  Next, in step ST4, it is determined whether Ps−Pth> α. That is, from the viewpoint of preventing cavitation, “NPSH” (Net Positive Suction Head), which is a characteristic of the pump 4, that is, “NPSH-A” (effective suction head, Net Positive Suction Head Available) and “NPSH-R”. ”(Necessary effective suction head, Net Positive Suction Head Required), based on the difference“ NPSH-A ”−“ NPSH-R ”, a predetermined value α of 0 (zero) or more is set in advance, and in step ST4 It is determined whether or not the detected pressure Ps detected by the pressure sensor 11 is greater than the derived saturated vapor pressure Pth + the predetermined value α.

  If the determination in step ST4 is YES, the process proceeds to step ST5, in which the variable i held in the control device 10 is set to the initial value 0, and the rotation speed adjustment amount Δr is set to the initial value Δr0. Then, the process returns to step ST2.

  On the other hand, if the determination in step ST4 is NO, the process proceeds to step ST6. In step ST6, it is determined whether or not a value obtained by subtracting a predetermined rotational speed Δr from the current rotational speed r of the pump 4 is greater than zero. That is, it is determined whether or not the pump 4 can continue to rotate even if the rotational speed of the pump 4 is lowered by a predetermined rotational speed Δr.

  If YES is determined in step ST6, the process proceeds to step ST7 to determine whether or not the variable i is the initial value 0. If the determination in step ST7 is yes, the process proceeds to step ST8. In step ST8, the rotational speed r of the pump 4 is decreased from the current value by a predetermined rotational speed Δr. That is, if the pressure difference between the pressure Ps detected by the pressure sensor 11 and the derived saturated vapor pressure Pth (Ts) is equal to or less than the predetermined value α, control is performed to reduce the rotational speed of the pump 4 by the predetermined rotational speed. The Thereby, the pump output is reduced and the circulation amount of the working medium delivered from the pump 4 is reduced. When the circulating amount of the working medium decreases, the pressure Ps of the working medium on the inlet side of the pump 4 is usually lower than the current level, while the rate of heat being taken away from the working medium in the condenser 3 increases. In this case, the temperature Ts of the working medium becomes lower than the current state. Along with this, the derived saturated vapor pressure Pth (Ts) also decreases. In general, the degree of decrease in the saturated vapor pressure Pth (Ts) is greater than the degree of decrease in the pressure Ps of the working medium. For this reason, it is expected that the execution of step ST8 returns to the state of Ps−Pth> α (the determination in step ST4 is changed from NO to YES). After execution of step ST8, the variable i is incremented (i is increased by 1) in step ST9, and the process returns to step ST2.

  Even if the circulating amount of the working medium sent out by the pump 4 is reduced in step ST8, a certain amount of time is required for the effect to be exhibited. Therefore, after step ST8 is executed once, step ST7 and step ST9 described above, and step ST10 and step ST11 described later are provided so that step ST8 is not executed again immediately.

  That is, if NO is determined in step ST7 (that is, step ST9 is executed before that, i means that it is 1 or more, and thus step ST8 is executed once). Then, the variable i is compared with the constant n to determine whether i <n. If the determination in step ST10 is YES (i <n), the variable i is again incremented (i is increased by 1) in step ST9, and the process returns to step ST2.

  If the determination in step ST10 is NO (ie, i ≧ n), the process proceeds to step ST11, i is set to the initial value 0, and the process returns to step ST2. From this state, if NO in step ST4 (that is, Ps−Pth ≦ α) and YES in step ST6 (that is, pump speed r−Δr> minimum speed), i remains at the initial value 0. In step ST7, the determination is YES, the process proceeds to step ST8, and the rotational speed r of the pump 4 is again lowered from the current value by a predetermined rotational speed Δr.

  If it is determined NO in step ST6, the pump 4 cannot continue to rotate when the pump 4 is subsequently rotated at a predetermined rotational speed Δr. Therefore, if NO is determined in step ST6, the process proceeds to step ST13, and an alarm indicating that is transmitted by an input / display means (not shown) such as a touch panel provided in the control device 10. Alternatively, the operation of the power generation apparatus 100 itself is stopped.

  In the power generation device 100 having the above-described configuration, even if the pressure Ps of the working medium on the pump inlet side deviates from a state higher than the saturated vapor pressure Pth of the working medium on the pump inlet side by a predetermined value α or more, it is short. It becomes possible to return to that state in time. This increases the possibility of returning to the state of Ps−Pth> α (determination in step ST4 is changed from NO to YES), thereby preventing the cavitation from occurring in the pump 4 or cavitation. The effect which suppresses generation | occurrence | production of can be heightened. In other words, the state of Ps−Pth> α can be easily maintained, and the occurrence of cavitation can be suppressed. In addition, since it is not necessary to detect the liquid level in the gas-liquid separator, the gas-liquid separator and the liquid level detector are not required, and the configuration can be prevented from becoming complicated.

  Here, the control flow of the modification of the electric power generating apparatus 100 which concerns on 1st Embodiment is shown in FIG. Note that most of the control flow shown in FIG. 3 is in common with the control flow shown in FIG. 2, and therefore only the different parts will be described here.

  In the control flow shown in FIG. 3, step ST13 is added after step ST11. In step ST13, Δr itself is increased by Δr1 for the reduction amount when the pump rotational speed r is reduced in step ST8. Thereby, it is possible to gradually increase the degree of decrease in the rotational speed of the pump 4. As a result, the possibility of returning to the state of Ps−Pth> α (the determination in step ST4 is changed from NO to YES) can be further increased. Therefore, the effect of preventing the occurrence of cavitation in the pump 4 or suppressing the occurrence of cavitation can be further enhanced.

(Second Embodiment)
FIG. 4 shows the configuration of the power generation apparatus 101 according to the second embodiment of the present invention. The power generator 101 according to the second embodiment shown in FIG. 4 has substantially the same configuration as that of the power generator 100 according to the first embodiment of the present invention shown in FIG. To do.

  The power generation device 100 according to the second embodiment is provided with a reflux channel 13 and a reflux control valve 14 disposed in the reflux channel 13 in addition to the configuration of the power generation device 100 illustrated in FIG. 1.

  The reflux channel 13 connects the circulation channel 6 on the upstream side of the pump 4 and the circulation channel 6 on the downstream side of the pump 4. That is, the reflux channel 13 is connected to the circulation channel 6 so as to bypass the pump 4.

  The reflux adjustment valve 14 is an adjustment valve whose opening degree can be arbitrarily adjusted, and the opening degree is adjusted by a control signal output from the control device 10.

  The adjustment control unit 23 calculates a difference (differential pressure) between the saturated vapor pressure derived by the deriving unit 21 and the pressure of the working medium detected by the pressure sensor 11, and according to the derived differential pressure. The control device 10 outputs the control signal.

  FIG. 5 shows control related to adjustment of the working medium pressure on the pump inlet side in the control flow of the power generation apparatus 101 according to the second embodiment. Since the control flow shown in FIG. 5 is substantially the same as the control flow shown in FIG. 2, only the parts different from the control flow shown in FIG. 2 will be described below.

  In the control flow shown in FIG. 5, step ST1, step ST5, step ST6, and step ST8 in the control flow shown in FIG. 2 are different. Instead of these steps, step ST1a, step ST5a, step ST6a, and step ST8a is provided.

  In step ST1a, the variable i held in the control device 10 is set to the initial value 0, the adjustment amount Δg of the opening g of the reflux adjusting valve 14 is set to the initial value Δg0, and the opening g is set to the initial value g0. Here, it is assumed that the initial value g0 of the opening degree g is 0 (zero), and the reflux adjustment valve 14 is closed in step ST1a. Step ST5a is the same as step ST1a.

  In step ST6a, it is determined whether or not a value obtained by increasing the current opening degree g of the reflux adjustment valve 14 by a predetermined opening degree adjustment amount Δg is smaller than the maximum opening degree in the specification of the reflux adjustment valve 14. That is, in step ST6a, it is next determined whether or not the opening degree of the reflux adjusting valve 14 can be increased by a predetermined opening degree Δg.

  In step ST8a, the opening degree g of the reflux adjusting valve 14 is increased from the current value by a predetermined opening degree Δg. Thereby, a part of the working medium sent out from the discharge side of the pump 4 is returned to the suction side of the pump 4, and as a result, the circulation amount of the working medium in the circulation flow path 6 is reduced. This control is also expected to return to the state of Ps−Pth> α (the determination in step ST4 is changed from NO to YES).

  Note that step ST13a may be added after step ST11 as indicated by a dotted line in FIG. In step ST13a, the opening adjustment amount Δg itself for the increase when the opening g of the reflux adjustment valve 14 is increased in step ST8a is increased by Δg1. Thereby, it is possible to gradually increase the degree of increase in the opening degree g of the reflux adjustment valve 14.

  Therefore, also in the second embodiment, as in the first embodiment, the pressure Ps of the working medium on the pump inlet side deviates from a state higher than the saturated vapor pressure Pth of the working medium on the pump inlet side by a predetermined value α or more. Even if there is a case, it is possible to return to the state in a short time. This increases the possibility of returning to the state of Ps−Pth> α (determination in step ST4 is changed from NO to YES), thereby preventing the cavitation from occurring in the pump 4 or cavitation. The effect which suppresses generation | occurrence | production of can be heightened.

  Other configurations, functions, and effects are the same as those in the first embodiment, although explanations thereof are omitted.

(Third embodiment)
FIG. 6 shows a power generator 102 according to the third embodiment of the present invention. Since the power generation apparatus 102 according to the third embodiment has substantially the same configuration as that of the power generation apparatus 100 according to the first embodiment shown in FIG. 1, only different points will be described here.

  The power generation apparatus 102 according to the third embodiment includes a cooling medium flow rate adjustment valve 15 in addition to the configuration of the power generation apparatus 100 according to the first embodiment shown in FIG. The cooling medium flow rate adjustment valve 15 is for adjusting the flow rate of the cooling medium supplied to the condenser 3, and is disposed upstream of the condenser 3 in the cooling medium flow path 8. The cooling medium flow rate adjustment valve 15 is an adjustment valve whose opening degree can be adjusted by a control signal output from the control device 10.

  The adjustment control means 23 calculates the difference (differential pressure) between the saturated vapor pressure derived by the derivation means 21 and the pressure of the working medium detected by the pressure sensor 11, and the control device 10 derives this difference. The control signal is output according to the differential pressure.

  FIG. 7 shows control related to adjustment of the working medium pressure on the pump inlet side in the control flow of the power generator 102 according to the third embodiment. Since the control flow shown in FIG. 7 is almost the same as the control flow shown in FIG. 2 or the control flow shown in FIG. 5, only the parts different from the control flow shown in FIG. 2 will be described below.

  The control flow shown in FIG. 7 is different from the control flow shown in FIG. 2 in step ST1, step ST5, step ST6, and step ST8. Instead of these steps, step ST1b, step ST5b, step ST6b, and step ST8b is provided.

  In step ST1b, the variable i held in the control device 10 is set to the initial value 0, the adjustment amount Δh of the opening h of the cooling medium flow rate adjustment valve 15 is set to the initial value Δh0, and the cooling medium flow rate adjustment valve 15 is opened. Degree h is an initial value h0. Step ST5b is the same as step ST1b.

  In step ST6b, it is determined whether or not the value obtained by increasing the predetermined opening Δh from the current opening h of the cooling medium flow rate adjustment valve 15 is smaller than the maximum opening on the specification of the cooling medium flow rate adjustment valve 15. The That is, in step ST6b, it is next determined whether or not the opening degree h of the coolant flow rate adjustment valve 15 can be increased by a predetermined opening degree Δh.

  In step ST8b, the opening h of the coolant flow rate adjustment valve 15 is increased from the current value by a predetermined opening Δh. Thereby, the flow rate of the cooling medium supplied to the condenser 3 through the cooling medium flow path 8 is increased, and heat exchange between the working medium and the cooling medium in the condenser 3 is promoted. Therefore, the temperature Ts of the working medium on the outlet side of the condenser 3, that is, on the suction side of the pump 4, is lowered. As a result, the saturated vapor pressure Pth (Ts) of the working medium on the suction side of the pump 4 also decreases. For this reason, this control is also expected to return to the state of Ps−Pth> α (the determination in step ST4 is changed from NO to YES).

  Note that step ST13b may be added after step ST11 as indicated by a dotted line in FIG. In step ST13b, the opening adjustment amount Δh itself for the increase when the opening h of the coolant flow rate adjustment valve 15 is increased in step ST8b is increased by Δh1. Thereby, it is possible to gradually increase the degree of increase in the opening degree h of the coolant flow rate adjustment valve 15.

  Accordingly, also in the third embodiment, as in the first embodiment, the pressure Ps of the working medium on the pump inlet side deviates from a state higher than the saturated vapor pressure Pth of the working medium on the pump inlet side by a predetermined value α or more. Even if there is a case, it is possible to return to the state in a short time. This increases the possibility of returning to the state of Ps−Pth> α (determination in step ST4 is changed from NO to YES), thereby preventing the cavitation from occurring in the pump 4 or cavitation. The effect which suppresses generation | occurrence | production of can be heightened.

  Other configurations, functions, and effects are the same as those in the first embodiment, although explanations thereof are omitted.

(Fourth embodiment)
FIG. 8 shows a configuration of a power generation apparatus 103 according to the fourth embodiment of the present invention. Since the power generation device 103 according to the fourth embodiment has substantially the same configuration as the power generation device 100 according to the first embodiment shown in FIG. 1, only different points will be described here.

  The power generation apparatus 103 according to the fourth embodiment has a configuration in which the discharge pressure detection means 16 is added to the configuration of the power generation apparatus 100 according to the first embodiment shown in FIG. The discharge pressure detecting means 16 is disposed downstream of the pump 4 in the cooling medium flow path 8, that is, on the discharge side of the pump 4. The discharge pressure detection means 16 detects the pressure of the working medium sent from the pump 4 to the evaporator 5 (discharge pressure Pd of the pump 4).

  The adjustment control means 23 calculates the difference (differential pressure) between the saturated vapor pressure derived by the derivation means 21 and the pressure of the working medium detected by the pressure sensor 11, and the control device 10 derives this difference. A control signal is output according to the differential pressure. Further, the adjustment control unit 23 outputs a control signal according to the fluctuation range of the detected pressure by the discharge pressure detection unit 16 (depending on whether or not the fluctuation range is less than the threshold value). The pump 4 receives the control signal from the control device 10, changes the rotational speed of the rotor of the pump 4, and adjusts the delivery flow rate of the working medium delivered from the pump 4.

  In the control flow shown in FIG. 9, step ST14 and step ST15 are added before step ST2 in the control flow shown in FIG. These steps 14 and ST15 are steps for adjusting the working medium pressure on the pump inlet side using the discharge pressure Pd of the pump 4 detected by the discharge pressure detecting means 16. In step ST14, the discharge pressure detecting means 16 detects the discharge pressure Pd of the pump 4, and in step ST15, whether or not the fluctuation width ΔPd of the pump 4 within a preset time is less than a predetermined threshold value ΔPdth. Is judged. Then, when the determination in step ST15 is NO (when the fluctuation range ΔPd is greater than or equal to the threshold value ΔPdth), the process proceeds to step ST6.

  As shown in FIG. 10, when cavitation occurs, the fluctuation range of the discharge pressure Pd of the pump 4 increases. The fluctuation range at this time is twice or more the normal fluctuation range. When the control device 10 determines that the pressure fluctuation is equal to or greater than a predetermined threshold value ΔPdth, the control device 10 regards that cavitation is actually occurring, and in step ST8, in step ST8, determines the rotational speed r of the pump 4. Is executed to reduce the current value from the current value by a predetermined rotational speed Δr. That is, when a pressure fluctuation equal to or greater than a preset threshold value is detected, the output of the pump 4 is reduced to reduce the circulation amount of the working medium that circulates in the circulation flow path 6, whereby the pump 4 inlet side is reduced. The pressure Ps and the temperature Ts can be kept low, thereby suppressing the occurrence of cavitation.

  In addition, since the fourth embodiment includes step ST4 for determining whether Ps−Pth> α, the pressure on the inlet side of the pump 4 when the fluctuation range of the discharge pressure Pd is equal to or larger than the threshold value ΔPdth. When Ps is equal to or lower than the saturated vapor pressure Pth + α, control for reducing the rotational speed r of the pump 4 can be executed. Therefore, the effect of suppressing the occurrence of cavitation can be further enhanced.

  Other configurations, functions, and effects are the same as those in the first embodiment, although explanations thereof are omitted.

(Fifth embodiment)
FIG. 11 shows a control flow of the power generator according to the fifth embodiment of the present invention. Here, only differences from the control flow shown in FIG. 9 will be described. In the control flow shown in FIG. 11, steps ST2 to ST4 of the control flow shown in FIG. 9 are omitted. Therefore, in the fifth embodiment, unlike the fourth embodiment, control for reducing the rotational speed r of the pump 4 is executed only based on the fluctuation range of the discharge pressure Pd of the pump 4. In the fifth embodiment, the pressure sensor 11 and the temperature sensor 12 can be omitted.

  Other configurations, operations, and effects are the same as those in the fourth embodiment, although explanations thereof are omitted.

DESCRIPTION OF SYMBOLS 1 Expander 1d Discharge port 1s Intake port 2 Generator 3 Condenser 4 Pump 5 Evaporator 6 Circulation channel 7 Heat medium channel 8 Cooling medium channel 10 Controller 11 Pressure sensor 12 Temperature sensor 13 Reflux channel 14 Reflux adjustment Valve 15 Cooling medium flow rate adjustment valve 16 Discharge pressure detection means 21 Derivation means 23 Adjustment control means 50 Power generation cycle 100 Power generation apparatus 101 Power generation apparatus 102 Power generation apparatus 103 Power generation apparatus

Claims (6)

A closed loop circulating flow in which a steam generating means for evaporating the working medium liquid, an expander for expanding the working medium steam, a condensing means for condensing the working medium vapor, and a pump for circulating the working medium are connected in series. A power generator comprising a path and driving a generator with the expander,
A working medium pressure detecting means provided in a flow path between the condensing means and the pump in the circulation flow path for detecting the pressure of the working medium on the inlet side of the pump;
A working medium temperature detecting means which is provided in a flow path between the condensing means and the pump in the circulation flow path and detects the temperature of the working medium on the inlet side of the pump;
Deriving means for deriving the saturated vapor pressure of the working medium on the inlet side of the pump from the detection value of the working medium temperature detecting means;
Depending on the differential pressure between the saturated vapor pressure derived by the deriving means and the pressure of the working medium detected by the working medium pressure detecting means, the circulating amount of the working medium or the cooling medium supplied to the condensing means And an adjustment control means for adjusting the supply amount.   The power generation device according to claim 1, wherein the adjustment control unit adjusts a circulation amount of the working medium by adjusting a delivery flow rate of the working medium by the pump. A reflux flow path is connected to the circulation flow path so as to bypass the pump,
A reflux control valve is disposed in the reflux channel,
The power generation device according to claim 1, wherein the adjustment control unit adjusts a circulation amount of the working medium by controlling the reflux adjustment valve.   2. The power generation device according to claim 1, wherein the adjustment control unit adjusts a supply amount of the cooling medium supplied to the condensing unit by controlling a flow rate adjusting valve disposed in a cooling flow path that communicates with the cooling medium. . A discharge pressure detecting means that is provided at a position downstream of the pump in the circulation flow path and detects the pressure of the working medium sent from the pump to the steam generating means;
The adjustment control unit is configured to adjust the saturated vapor pressure derived by the working medium pressure detected by the discharge pressure detecting unit or by the deriving unit and the pressure of the working medium detected by the working medium pressure detecting unit. The power generation device according to any one of claims 1 to 4, wherein a circulation amount of the working medium is adjusted according to a pressure difference between the working medium and the working medium. A closed loop circulating flow in which a steam generating means for evaporating the working medium liquid, an expander for expanding the working medium steam, a condensing means for condensing the working medium vapor, and a pump for circulating the working medium are connected in series. A power generator comprising a path and driving a generator with the expander,
A discharge pressure detecting means provided at a position downstream of the pump in the circulation flow path for detecting the pressure of the working medium sent from the pump to the steam generating means;
And an adjustment control unit that adjusts a circulation amount of the working medium according to the pressure of the working medium detected by the discharge pressure detecting unit.

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