JP2021017822A - Binary electric power generation system - Google Patents

Abstract

To provide a binary electric power generation system capable of recovering much electric power (net electric power) while suppressing evaporation of a cooling fluid and occurrence of clogging in a condenser.SOLUTION: A binary electric power generation system comprises: a binary electric power generation device that generates electric power utilizing a Rankine cycle using a working medium; a dry cooler having a heat transfer tube for flowing of a cooling fluid flowing out from a condenser of the binary electric power generation device, and a fan that forms an air flow for cooling the cooling fluid flowing in the heat transfer tube; a cooling fluid pump that circulates the cooling fluid between the condenser and the heat transfer tube; and a control unit that controls the frequency of the fan in such a manner that net electric power increases, which is calculated by subtracting the electric power required for driving the cooling fluid pump and the electric power required for driving the fan from the electric power generated by the binary electric power generation device.SELECTED DRAWING: Figure 1

Description

The present invention relates to a binary power generation system.

Conventionally, a binary power generation system including a binary power generation device that generates electric power by recovering exhaust heat of various facilities such as a factory is known (see Patent Document 1). The binary power generator has a circulation pipe connected to the suction port and the discharge port of the circulation pump, an evaporator, an expander and a condenser provided in the circulation pipe, and a generator connected to the expander. ing. The evaporator, expander and condenser are arranged so that the working medium delivered by the circulation pump passes through them in sequence.

The binary power generation system further has a cooling tower for cooling the cooling water for condensing the working medium in the condenser, a cooling water pipe through which the cooling water flows, and a cooling water pump for supplying the cooling water to the condenser. There is. The cooling water pipe connects the condenser and the cooling tower so that the cooling water circulates between the condenser and the cooling tower. The cooling water pump is provided in the cooling water pipe.

The evaporator evaporates the working medium. The evaporated working medium flows into the expander and expands in the expander. As a result of the expansion of the working medium, the expander and the generator connected to the expander are driven to generate electric power. The working medium that worked in the inflator flows into the condenser. The condenser condenses the inflowing working medium under heat exchange with cooling water. The circulation pump sends the working medium flowing out of the condenser to the evaporator.

The cooling water used to condense the working medium is cooled in the cooling tower. The cooling water circulates between the cooling tower and the condenser under the operation of the cooling water pump.

Japanese Unexamined Patent Publication No. 2014-163608

In a binary power generation system as described in Patent Document 1, since the cooling water evaporates in the cooling tower, it is necessary to replenish the cooling water on a regular basis. In addition, if dust or the like enters the cooling tower, the condenser may be clogged.

In order to cool the cooling fluid (cooling water, etc.) flowing out of the condenser, it is conceivable to use a dry cooler that cools the cooling fluid flowing through the heat transfer tube with an air flow. The dry cooler has a fan that forms an air flow for air-cooling the cooling fluid flowing in the heat transfer tube. The cooling fluid is circulated between the heat transfer tube and the condenser by the cooling fluid pump. Since the circulation flow path through which the cooling fluid flows is configured to be separated from the outside, problems such as evaporation of the cooling fluid to the outside and contamination of foreign matter into the cooling fluid are unlikely to occur. However, when a dry cooler is used, power is required to drive not only the cooling fluid pump but also the fan.

An object of the present invention is to provide a binary power generation system capable of recovering a large amount of electric power (net electric power) while suppressing evaporation of a cooling fluid and occurrence of clogging in a condenser.

The binary power generation system according to one aspect of the present invention includes an evaporator that evaporates the working medium, an expander that is driven under the expansion of the evaporated working medium, a generator connected to the expander, and the above. A condenser that condenses the working medium by cooling the working medium that has flowed out of the expander with a cooling fluid, a working medium pump that sends the working medium that has flowed out of the condenser to the evaporator, and the evaporator. A binary power generator including the expander, the condenser, and a working medium circulation flow path connecting the working medium pump in this order, and a heat transfer tube for flowing the cooling fluid flowing out of the condenser. A dry cooler having a fan for forming an air flow for air-cooling the cooling fluid flowing in the heat transfer tube, and a cooling fluid pump for circulating the cooling fluid between the condenser and the heat transfer tube. And a control unit that controls the frequency of the fan so that the net power calculated by subtracting the power required to drive the cooling fluid pump and the fan from the power generated by the binary power generation device is increased. I have.

According to the above configuration, since the dry cooler is used to cool the cooling fluid flowing out of the condenser, evaporation of the cooling fluid and occurrence of clogging in the condenser are suppressed. In addition, a dry cooler is used because the fan is controlled so that the net power calculated by subtracting the power required to drive the cooling fluid pump and fan from the power generated by the binary power generation device is increased. The output as is increased.

With respect to the above configuration, the control unit may control the frequency of the fan so that the net power increases based on the change in the amount of heat exchange between the cooling fluid and the airflow.

According to the above configuration, when the amount of heat exchange between the cooling fluid and the airflow changes, the amount of heat exchange in the condenser (and thus the electric power generated by the binary power generator) also changes. In this case, the frequency of the fan that can obtain high net power may have changed. The control unit controls the frequency of the fan so that the net power increases based on the change in the amount of heat exchange between the cooling fluid and the air flow. As a result, the binary power generation system can achieve high net power even if there is heat exchange between the cooling fluid and the airflow.

With respect to the above configuration, the fan may take in air around the binary power generation system to generate the airflow. The control unit may calculate the heat exchange amount based on the ambient temperature around the binary power generation system.

According to the above configuration, the fan takes in the air around the binary power generation system to generate airflow, so the amount of heat exchange between the cooling fluid and the airflow in the dry cooler is the ambient temperature around the binary power generation system. Affected by. Since the control unit calculates the heat exchange amount based on the ambient temperature, it is possible to obtain information on the change in the heat exchange amount.

With respect to the above configuration, the control unit includes a change unit configured to change and set the frequency of the fan, and a power calculation unit that calculates the net power before and after the change of the frequency of the fan. You may. The change unit may set the higher of the net power calculated by the power calculation unit to the frequency of the fan.

According to the above configuration, the power calculation unit calculates the net power before and after the change of the fan frequency, so that it can be known whether or not the net power has increased as a result of the change of the fan frequency. Since the changing unit sets the larger of the net power calculated by the power calculation unit to the frequency of the fan, the binary power generation system can achieve a high net power.

With respect to the above configuration, the control unit may include a heat quantity calculation unit that calculates the amount of heat exchange between the cooling fluid and the air flow based on the ambient temperature around the binary power generation system. The changing unit adjusts the frequency of the fan so that the net power increases based on the change in the heat exchange amount calculated by the heat quantity calculating unit after the frequency of the fan is changed by the changing unit. You may set it again.

According to the above configuration, if the heat exchange amount calculated by the calorific value calculation unit changes while the fan is operating at the frequency at which the increased net power is calculated, the change unit causes the net power to increase. By changing the frequency of the fan again, the binary power generation system can achieve high net power even after a change in the amount of heat exchange between the cooling fluid and the airflow.

With respect to the above configuration, the control unit may control the frequency of the cooling fluid pump toward a predetermined value.

According to the above configuration, since the frequency of the cooling fluid pump is controlled toward a predetermined value, the electric power required to drive the cooling fluid pump may be treated as a constant value. The net power is calculated without taking into account the fluctuations in power required by the cooling fluid pump, simplifying tuning control over the fan frequency.

The above-mentioned binary power generation system can suppress the evaporation of the cooling fluid and the occurrence of clogging in the condenser, and can recover a large amount of electric power (net electric power).

It is a schematic diagram of a binary power generation system. It is a block diagram which shows the schematic functional structure of the control part of a binary power generation system. It is a flowchart which outlines the 1st control executed at the time of starting up a binary power generation system. It is a flowchart which roughly shows the 2nd control executed at the time of the steady operation of a binary power generation system. It is a graph which shows the change of the net power with respect to the fan of a binary power generation system roughly. It is a flowchart which shows the other 2nd control roughly. It is a flowchart which shows the other 1st control roughly. It is a schematic diagram of another binary power generation system.

FIG. 1 is a schematic view of the binary power generation system 1. The binary power generation system 1 will be described with reference to FIG.

The binary power generation system 1 includes a binary power generation device 100, a dry cooler 200, a cooling fluid circulation flow path 300, and a cooling fluid pump 400.

The binary power generator 100 is configured to generate electric power by utilizing the Rankine cycle using an actuating medium. The binary power generation device 100 has an operating medium pump 150 that discharges an operating medium, and an operating medium circulation flow path 160 that is connected to a suction port and a discharge port of the operating medium pump 150. The binary power generation device 100 further includes an evaporator 110, an expander 120, and a condenser 140 provided in the working medium circulation flow path 160. The evaporator 110, the expander 120, and the condenser 140 are arranged so that the working medium discharged by the working medium pump 150 passes through them in order. The binary generator 100 further includes a generator 130 connected to the internal rotor of the expander 120.

The evaporator 110 is configured to evaporate the working medium by exchanging heat between the working medium and the heating medium (for example, hot water). The evaporated working medium is used to drive the expander 120.

The expander 120 has an internal rotor driven under the expansion of the working medium. As a result of the rotation of the internal rotor, the generator 130 connected to the internal rotor is also driven to generate electric power. As the expander 120, a positive displacement screw expander having a rotor that is rotationally driven by the expansion energy of the working medium of the gas phase is used.

The condenser 140 is configured to heat exchange the working medium flowing out of the expander 120 with a cooling fluid having a temperature lower than that of the working medium. The working medium is cooled by the cooling fluid in the condenser 140 and condensed. On the other hand, the cooling fluid is heated by the working medium to raise the temperature. As the cooling fluid, it is preferable to use an antifreeze solution such as water or an aqueous ethylene glycol solution.

The working medium pump 150 is provided in the working medium circulation flow path 160 so as to send the working medium of the liquid phase flowing out of the condenser 140 to the evaporator 110.

The dry cooler 200 is configured to cool the cooling fluid flowing out of the condenser 140. The dry cooler 200 sucks in the heat transfer tube 210 for flowing the cooling fluid flowing out from the condenser 140, the housing 220 in which the heat transfer tube 210 is housed, and the air outside the housing 220, and causes an air flow inside the housing 220. Has a plurality of fans 230 and the like. These fans 230 are provided in the housing 220. The airflow generated by the fan 230 is used for heat exchange with the cooling fluid flowing through the heat transfer tube 210. In order to obtain efficient heat exchange, the heat transfer tube 210 is provided with a plurality of fins (not shown).

The cooling fluid circulation flow path 300 connects the condenser 140 and the heat transfer tube 210 so that the cooling fluid circulates between the condenser 140 and the heat transfer tube 210. The cooling fluid flow path formed by the cooling fluid circulation flow path 300, the condenser 140, and the heat transfer tube 210 is separated from the outside so as to suppress the entry of foreign matter into the cooling fluid and the evaporation of the cooling fluid to the outside. ing.

The cooling fluid pump 400 is provided in the cooling fluid circulation flow path 300 so as to circulate the cooling fluid between the condenser 140 and the heat transfer tube 210.

The binary power generation system 1 further has control-related parts that control the fan 230 and the cooling fluid pump 400. Control-related sites will be described with reference to FIGS. 1 and 2.

The control-related parts include two temperature sensors 601, 604, a flow rate sensor 605, and a control unit 500. An exemplary functional configuration of the control unit 500 is shown in FIG.

The temperature sensor 601 is attached to the cooling fluid circulation flow path 300 so as to detect the temperature of the cooling fluid flowing from the heat transfer tube 210 toward the condenser 140. The temperature sensor 604 is attached to the cooling fluid circulation flow path 300 so as to detect the temperature of the cooling fluid flowing from the condenser 140 toward the heat transfer tube 210. These temperature sensors 601, 604 are configured to generate a detection signal representing the detected temperature.

The flow rate sensor 605 is attached to the cooling fluid circulation flow path 300 so as to detect the flow rate of the cooling fluid circulating between the condenser 140 and the heat transfer tube 210. The flow rate sensor 605 is configured to generate a detection signal representing the detected flow rate. The detection signals of the flow rate sensors 605 and the temperature sensors 601, 604 are used to calculate the amount of heat exchange between the airflow generated by the fan 230 and the cooling fluid.

The control unit 500 is used to control the fan 230 and the cooling fluid pump 400. The control unit 500 is configured to control the cooling fluid pump 400 so that the frequency (rotational speed) of the cooling fluid pump 400 becomes a predetermined value, while adjusting the frequency (rotational speed) of the fan 230. .. The frequency adjustment of the fan 230 is performed to obtain a high value for the net output (hereinafter referred to as net power W) of the binary power generation system 1.

Regarding the adjustment of the frequency of the fan 230, the control unit 500 adjusts the frequency of the fan 230 at the time of starting up the binary power generation system 1 and performs the first control of finding the frequency of the fan 230 in order to obtain a high net power W. It is configured as follows. During steady operation of the binary power generation system 1, the control unit 500 performs a second control for adjusting the frequency of the fan 230 according to a change in the amount of heat exchange between the air flow and the cooling fluid in the dry cooler 200. It is configured in.

The above-mentioned net power W is a value obtained by subtracting the powers Wp and Wf required for driving the cooling fluid pump 400 and the fan 230 from the power We generated by the binary power generation device 100 (see the following formula). The electric power We generated by the binary power generation device 100 is a value obtained by subtracting the electric power required in the binary power generation device 100 (the electric power required to drive the operating medium pump 150, etc.) from the electric power generated by the generator 130.

The power Wf required by the fan 230 can be expressed as an increasing function of the frequency of the fan 230. As the frequency of the fan 230 increases, the temperature of the cooling fluid decreases, the amount of heat exchange in the condenser 140 increases, and the pressure of the working medium in the condenser 140 decreases. As a result, the electric power We generated by the binary power generator also increases. Therefore, the power We generated by the binary power generator can also be expressed as an increasing function of the frequency of the fan 230. The net power W increases or decreases as the fan frequency increases, depending on the magnitude of the increase in the power Wf and We as the frequency of the fan 230 increases.

The control unit 500 is connected to the temperature sensors 601, 604 and the flow rate sensor 605 by wire or wirelessly so as to receive the detection signals. In addition, the control unit 500 receives the electric power generated by the binary power generation device 100 and the electric power information representing the electric power consumed in the binary power generation device 100 for the electric power generation from the binary power generation device 100 so that the binary power generation device 100 receives the electric power. It is connected to the. The control unit 500 is configured to adjust the frequency of the fan 230 based on the detection signals of the temperature sensors 601, 604 and the flow rate sensor 605 and the power information from the binary power generation device 100.

The control unit 500 may be a circuit having a storage element such as a memory and generating a drive signal for driving the cooling fluid pump 400 and the fan 230 under the execution of a predetermined program. When the control unit 500 executes the program, the power calculation unit 510, the first storage unit 520, the second storage unit 530, the change unit 540, the calorific value calculation unit 550, the third storage unit 560, the fourth storage unit 570, and the pump control Functions such as the unit 580 and the drive unit 590 are exhibited (see FIG. 2).

The power calculation unit 510 has a calculation function of calculating the net power W of the binary power generation system 1 based on the frequencies of the fan 230 and the cooling fluid pump 400 and the power information from the binary power generation device 100.

Regarding the calculation of the net electric power W, in detail, the electric power calculation unit 510 receives electric power information such as the electric power generated by the generator 130 and the electric power consumed by the motor driving the operating medium pump 150 from the binary power generator 100, and the electric power information. The power We is calculated based on. The power calculation unit 510 calculates the power Wf based on the frequency of the fan 230. Regarding the electric power Wp required to drive the cooling fluid pump 400, since the cooling fluid pump 400 is controlled toward a predetermined value as described above, the electric power Wp required to drive the cooling fluid pump 400 is It is almost constant. Therefore, the power calculation unit 510 may treat the power Wp as a constant. The power calculation unit 510 subtracts the powers Wf and Wp from the power We to calculate the net power W (see equation (1)).

The first storage unit 520 and the second storage unit 530 are used for arithmetic processing performed by the power calculation unit 510. The first storage unit 520 and the second storage unit 530 are configured to temporarily store the result of the calculation of the net power W executed by the power calculation unit 510.

The heat amount calculation unit 550 exchanges heat in the dry cooler 200 (that is, heat exchange between the cooling fluid and the airflow generated by the fan 230) based on the detection signals from the temperature sensors 601, 604 and the flow rate sensor 605. It has a calculation function to calculate the quantity). When the amount of heat exchanged in the dry cooler 200 changes, the amount of heat exchanged in the condenser 140 (and by extension, the electric power We generated by the binary power generation device 100) also changes. The heat amount calculation unit 550 is configured to perform a predetermined arithmetic process for detecting a change in the heat exchange amount in the condenser 140.

The third storage unit 560 and the fourth storage unit 570 are used for arithmetic processing performed by the heat quantity calculation unit 550. The third storage unit 560 and the fourth storage unit 570 are configured to temporarily store the result of the calculation of the heat exchange amount executed by the heat quantity calculation unit 550.

The change unit 540 is provided to change and set the frequency of the fan 230 based on the results of arithmetic processing from the power calculation unit 510 and the heat amount calculation unit 550. The change unit 540 is configured to output information regarding the changed or set frequency of the fan 230 to the drive unit 590.

The drive unit 590 is provided to generate a drive signal for driving the fan 230. The drive unit 590 is configured to drive the fan 230 at the changed or set frequency when it receives information about the changed or set frequency of the fan 230 from the changed unit 540.

The pump control unit 580 is configured to control the cooling fluid pump 400. The frequency of the cooling fluid pump 400 is maintained at a substantially constant value under the control of the pump control unit 580.

The operation of the binary power generation system 1 will be described below.

With respect to the operation of the binary power generator 100, the working medium pump 150 discharges the working medium to the evaporator 110. In the evaporator 110, the working medium exchanges heat with the heating medium and evaporates. On the other hand, the temperature of the heating medium drops. The evaporated working medium flows into the expander 120 and expands in the expander 120. As a result of the expansion of the working medium, the internal rotor of the expander 120 rotates, driving the generator 130 connected to the internal rotor. As a result, the generator 130 generates electric power. The working medium that has worked in the inflator 120 flows into the condenser 140. The working medium exchanges heat with the cooling fluid and condenses in the condenser 140. On the other hand, the temperature of the cooling fluid rises. The condensed working medium is sucked into the working medium pump 150 and sent out to the evaporator 110 again.

Regarding the operation of the dry cooler 200, the cooling fluid heated by the condenser 140 is sent to the heat transfer tube 210 by the cooling fluid pump 400. The cooling fluid flowing through the heat transfer tube 210 exchanges heat with the air flow generated under the drive of the fan 230, and the temperature of the cooling fluid drops. On the other hand, the temperature of the airflow rises. The cooling fluid cooled by the air flow flows into the condenser 140, where the condenser 140 exchanges heat again with the working medium.

The first control performed by the control unit 500 to determine the frequency of the fan 230 that achieves a high net power W at startup of the binary power generation system 1 will be described with reference to FIG. FIG. 3 is a schematic flowchart of the first control. In the first control, the frequency of the fan 230 is determined based on the net power W.

The drive unit 590 drives the fan 230 at a predetermined frequency (default value). At this time, the power calculation unit 510 calculates the net power W under the default frequency used for driving the fan 230 (step S110). Specifically, the power calculation unit 510 uses the power We obtained from the power information received from the binary power generation device 100 to obtain the power Wf and the cooling fluid pump 400 required when the fan 230 is driven at the above frequency. Subtract the power Wp required to drive the (see equation (1)). Since the frequency of the cooling fluid pump 400 is kept substantially constant under the control of the pump control unit 580 as described above, the power calculation unit 510 may use a predetermined constant for the power Wp. The calculated net power W is written to the first storage unit 520 (step S120). After that, a reduction adjustment process (step S200) for reducing the frequency of the fan 230 and an increase adjustment process (step S300) for increasing the frequency of the fan 230 are performed.

When the reduction adjustment process is started, the change unit 540 determines whether or not the reduction adjustment process can be continued (step S210). Specifically, the changing unit 540 determines whether or not the frequency does not fall below the predetermined lower limit frequency when the frequency of the fan 230 is reduced by a predetermined decrement value. The lower limit frequency may be the frequency at which the fan 230 stops (that is, 0 Hz), or the lowest frequency at which the fan 230 is guaranteed to operate stably. If it is determined that the frequency of the fan 230 is lower than the lower limit frequency (step S210: No), the control for the fan 230 shifts from the reduction adjustment process to the second control for steady operation (step S400). In other cases (step S210: Yes), the changing unit 540 lowers the frequency of the fan 230 by a predetermined decrement value, and the driving unit 590 drives at the reduced frequency (step S220). In order to wait for the operation of the binary power generation system 1 to stabilize, the driving of the fan 230 at the reduced frequency is continued for a predetermined period of time (step S230).

After the driving of the fan 230 at the reduced frequency is continued for a predetermined period of time, the power calculation unit 510 calculates the net power W under the driving of the fan 230 at the reduced frequency (step S240). After that, the power calculation unit 510 writes the calculated value of the net power W in the second storage unit 530 (step S250). The power calculation unit 510 reads data representing the net power W from each of the first storage unit 520 and the second storage unit 530, and compares the values of the read net power W (step S260).

The fact that the value of the net power W read from the second storage unit 530 does not exceed the value of the net power W read from the first storage unit 520 means that the high net power W is increased by reducing the frequency of the fan 230. It means that you cannot get it. In this case, the control for the fan 230 shifts from the reduction adjustment process to the increase adjustment process (step S260: No). In other cases (that is, when the net power W is increasing) (step S260: Yes), the power calculation unit 510 writes the data read from the second storage unit 530 to the first storage unit 520. (Step S270). As a result, the data in the first storage unit 520 is updated to a value of net power W higher than that before the update. After that, step S210 is executed again (that is, the reduction adjustment process is repeated).

As long as the determination result that the reduction adjustment process can be continued is obtained in step S210, the value of the net power W read from the second storage unit 530 in the reduction adjustment process is the first storage unit 520 in step S260. This is continued until a determination result is obtained that the value is equal to or less than the value of the net power W read from. When it is determined in step S260 that the value of the net power W read from the second storage unit 530 is equal to or less than the value of the net power W read from the first storage unit 520, the value is reduced. The transition from the adjustment process to the increase adjustment process is made.

The net power W stored in the first storage unit 520 when the control for the fan 230 shifts to the increase adjustment process or the second control is the maximum achieved in the increase adjustment process or the process before the second control. The value. The frequency that achieves the net power W stored in the first storage unit 520 is used as the frequency of the fan 230 at the start of the increase adjustment process or the second control. That is, when the control for the fan 230 shifts from the reduction adjustment process to the second control as a result of the first determination process (step S210) of whether or not the reduction adjustment process can be continued, the default value frequency (step S120) becomes the second control. It is used as the frequency of the fan 230 at the start of. When the control for the fan 230 shifts from the reduction adjustment process to the second control based on the result of the second and subsequent determination processes (step S210) regarding whether or not the reduction adjustment process can be continued, the control is read from the second storage unit 530. , The frequency at which the net power W (step S270) written in the first storage unit 520 is achieved is used as the frequency at the start of the second control. When the increase adjustment process is executed after the determination process (step S260) based on the magnitude relationship of the net power W is repeatedly performed, the net read from the second storage unit 530 and written to the first storage unit 520. The frequency at which the power W (step S270) is achieved is used as the frequency at the start of the increase adjustment process. As a result of the first determination process (step S260) based on the magnitude relationship of the net power W, when the control for the fan 230 shifts from the decrease adjustment process to the increase adjustment process, the frequency reduced by a predetermined decrement value from the default value is , Used as the frequency of the fan 230 at the start of the increase adjustment process.

When the increase adjustment process is started, the change unit 540 determines whether or not the increase adjustment process can be continued (step S310). Specifically, when the frequency of the fan 230 is increased by a predetermined increment value from the frequency at which the net power W stored in the first storage unit 520 is obtained, the change unit 540 sets the frequency of the fan 230 to a predetermined upper limit frequency. Judge whether or not it exceeds. The upper limit frequency may be the maximum allowable frequency of the fan 230. If it is determined that the frequency of the fan 230 exceeds the upper limit frequency (step S310: No), the control for the fan 230 shifts from the increase adjustment process to the second control for steady operation (step S400). In other cases (step S310: Yes), the changing unit 540 increases the frequency of the fan 230 by a predetermined increment, and the driving unit 590 drives the fan 230 at the increased frequency (step S320). In order to wait for the operation of the binary power generation system 1 to stabilize, the driving of the fan 230 at the increased frequency is continued for a predetermined period of time (step S330).

After the driving of the fan 230 at the increased frequency is continued for a predetermined period of time, the power calculation unit 510 calculates the net power W under the driving of the fan 230 at the increased frequency (step S340). After that, the power calculation unit 510 writes the calculated value of the net power W in the second storage unit 530 (step S350). The power calculation unit 510 reads data representing the net power W from each of the first storage unit 520 and the second storage unit 530, and compares the values of the read net power W (step S360).

The fact that the value of the net power W read from the second storage unit 530 does not exceed the value of the net power W read from the first storage unit 520 means that the high net power W increases as the frequency of the fan 230 increases. It means that you cannot get it. In this case, the control for the fan 230 shifts from the increase adjustment process to the second control for steady operation (step S360: No). In other cases (that is, when the net power W is increasing) (step S360: Yes), the power calculation unit 510 writes the data read from the second storage unit 530 to the first storage unit 520. (Step S370). As a result, the data in the first storage unit 520 is updated to a relatively high value of net power W. After that, step S310 is executed again (that is, the increase adjustment process is repeated).

As long as the determination result that the increase adjustment process can be continued is obtained in step S310, the value of the net power W read from the second storage unit 530 in the increase adjustment process is the first storage unit 520 in step S360. This is continued until a determination result is obtained that the value is equal to or less than the value of the net power W read from. When it is determined in step S360 that the value of the net power W read from the second storage unit 530 is equal to or less than the value of the net power W read from the first storage unit 520, it is steady. The second control for operation is executed (step S400).

The net power W stored in the first storage unit 520 when the control for the fan 230 shifts from the increase adjustment process to the second control is the maximum value achieved in the increase adjustment process. The frequency at which the net power W stored in the first storage unit 520 is achieved is used as the frequency of the fan 230 at the start of the second control. That is, when the control for the fan 230 shifts from the increase adjustment process to the second control as a result of the first determination process (step S310) of whether or not the increase adjustment process can be continued, the frequency at the start of the increase adjustment process is the second control. It is also used as the frequency of the fan 230 at the start of. When the increase adjustment process is shifted to the second control based on the result of the second and subsequent determination processes (step 310) regarding whether or not the increase adjustment process can be continued, the increase adjustment process is read from the second storage unit 530 and the first storage unit 520. The frequency at which the net power W (step S370) written in is achieved is used as the frequency at the start of the second control. As a result of the first determination process (step S360) based on the magnitude relationship of the net power W, when the second control is executed, the frequency increased by a predetermined increment value from the frequency at the start of the increase adjustment process is the second frequency. It is used as the frequency of the fan 230 at the start of control. When the second control is executed after the determination process (step S360) based on the magnitude relationship of the net power W is repeatedly performed, the net read from the second storage unit 530 and written to the first storage unit 520. The frequency at which the power W (step S370) is achieved is used as the frequency of the fan 230 at the start of the second control.

The second control is executed in consideration of the change in the net electric power W accompanying the change in the heat exchange amount (heat exchange amount between the cooling fluid and the air flow) in the dry cooler 200. When the amount of heat exchanged in the dry cooler 200 changes, the amount of heat exchanged in the condenser 140 (and by extension, the electric power We generated by the binary power generation device 100) also changes. As a result of the change in the power We generated by the binary power generator 100, the frequency value of the fan 230 that obtains a high net power W may have changed from the value set under the first control described above. .. The second control is performed to achieve a high net power W even after a change in the amount of heat exchange. The schematic process of the second control is shown in the flowchart of FIG.

When the second control for steady operation is started, the change unit 540 fan to the frequency at which the maximum net power W (that is, the net power W stored in the first storage unit 520) is achieved in the first control. The frequency of 230 is set (step S410). While the drive unit 590 is driving the fan 230 at this frequency, the heat quantity calculation unit 550 calculates the amount of heat exchange between the airflow and the cooling fluid based on the detection signals of the temperature sensors 601, 604 and the flow rate sensor 605. Calculate (step S420). The heat amount calculation unit 550 writes the calculated value of the heat exchange amount in the third storage unit 560 (step S430). The driving of the fan 230 at the frequency set in step S410 is continued for a predetermined period even after the calculation of the heat exchange amount (step S440).

In order to detect the change in the heat exchange amount, the heat amount calculation unit 550 recalculates the heat exchange amount after the elapse of a predetermined period (step S450). The heat amount calculation unit 550 writes the calculated value of the heat exchange amount in the fourth storage unit 570 (step S460). The heat amount calculation unit 550 reads data representing the heat exchange amount from each of the third storage unit 560 and the fourth storage unit 570, and compares the read values of the heat exchange amount (step S470).

If the value of the heat exchange amount read from the fourth storage unit 570 exceeds the value of the heat exchange amount read from the third storage unit 560 (step S470: Yes), the inside of the dry cooler 200. The amount of heat exchange is increasing. As a result of the increase in the amount of heat exchange in the dry cooler 200, the temperature of the cooling fluid decreases, so that the amount of heat exchange in the condenser 140 increases, and the electric power We generated by the binary power generation device 100 increases. In this case, if the frequency of the fan 230 is reduced, the difference between the powers We and Wf becomes large, and there is a possibility that a larger net power W can be obtained.

Therefore, when the determination result that the heat exchange amount is increasing is obtained (step S470: Yes), the reduction adjustment process (step S200) is executed. When the determination result that the reduction adjustment processing cannot be continued is obtained in step S210 of the reduction adjustment processing (step S210: No), the second control is executed again. When the control for the fan 230 returns to the second control based on the first determination result in step S210, the frequency of the fan 230 is maintained. When the control for the fan 230 returns to the second control based on the second and subsequent determination results in step S210, the frequency of the fan 230 that achieves the maximum net power W found in the reduction adjustment process is determined. It is used as the frequency of the fan 230 in the second control (step S410). When the determination result that the value of the net power W in the second storage unit 530 is lower than the value of the net power W in the first storage unit 520 is obtained in the reduction adjustment process (step S260: No). , Increase adjustment processing is performed. In this case, the frequency of the fan 230 that achieves the maximum net power found in the increase adjustment process is used as the frequency of the fan 230 in the second control.

If the value of the heat exchange amount read from the fourth storage unit 570 does not exceed the value of the heat exchange amount read from the third storage unit 560 (step S470: No), the inside of the dry cooler 200. The amount of heat exchange may have decreased. When the amount of heat exchange in the dry cooler 200 is decreasing, the temperature of the cooling fluid is increasing, so that the amount of heat exchange in the condenser 140 is reduced, and the power We generated by the binary power generation device 100 is reduced. .. As a result of the decrease in power We, the net power W also decreases. If the net power W is reduced as a result of the decrease in power We, the net power W may be restored to a high value by increasing the frequency of the fan 230.

Therefore, if the value of the heat exchange amount read from the fourth storage unit 570 is equal to or less than the value of the heat exchange amount read from the third storage unit 560, the increase adjustment process (step S300) is executed. .. When the frequency of the fan 230 that achieves the maximum net power W is found in the augmentation process, step S410 is executed again. In step S410 again, the frequency at which the maximum net power W is achieved in the increase adjustment process is used as the frequency of the fan 230.

A conceptual graph showing the relationship between the net power W with respect to the fan 230, the power We generated by the binary power generator 100, and the power Wf consumed by the fan 230 is shown in FIG. The graph of FIG. 5 is created under the condition that the temperature of the heating medium and the frequencies of the working medium pump 150 and the cooling fluid pump 400 are constant.

The electric power We generated by the binary power generation device 100 and the electric power Wf consumed by the fan 230 have an increasing function with respect to the frequency of the fan 230. As the frequency of the fan 230 rises, the power Wf consumed by the fan 230 increases, but the flow rate of the air flow generated by the fan 230 in the housing 220 increases. As a result, the temperature of the cooling fluid flowing in the heat transfer tube 210 also drops significantly. As the temperature of the cooling fluid decreases, the amount of heat exchange in the condenser 140 (and thus the amount of heat exchange in the evaporator 110) increases, and the electric power We generated by the binary power generation device 100 also increases.

With respect to the graph of FIG. 5, when the frequency of the fan 230 is relatively low, the rate of increase of the electric power We generated by the binary power generator 100 with the increase of the frequency of the fan 230 exceeds the rate of increase of the electric power Wf consumed by the fan 230. ing. In this case, the net power W increases as the frequency of the fan 230 increases. On the other hand, when the frequency of the fan 230 is relatively high, the rate of increase of the electric power We generated by the binary power generator 100 decreases as the frequency of the fan 230 increases, while the rate of increase of the electric power Wf consumed by the fan 230 increases. It increases as the frequency of the fan 230 increases. In this case, the net power W decreases as the frequency of the fan 230 increases. Therefore, the net power W takes a peak value when the frequency of the fan 230 is a predetermined value, as shown in FIG.

The control unit 500 changes the frequency of the fan 230 and searches for the peak value of the net power W through the above-mentioned reduction adjustment processing and / or increase adjustment processing. Therefore, the binary power generation system 1 can achieve a large net power W.

The flow path of the cooling fluid circulating between the heat transfer tube 210 of the dry cooler 200 and the condenser 140 of the binary power generation device 100 is separated from the outside. Therefore, it is unlikely that foreign matter is mixed into the cooling fluid (and thus, the flow path is clogged due to the foreign matter) or that the cooling fluid is evaporated to the outside.

The pump control unit 580 keeps the frequency of the cooling fluid pump 400 substantially constant. Therefore, the power calculation unit 510 treats the power consumption of the cooling fluid pump 400 as a constant value, and can easily calculate the net power W.

Regarding the second control in the steady operation of the above-described embodiment, the determination process of whether to perform the reduction adjustment process or the increase adjustment process is the heat exchange amount stored in the third storage unit 560 and the fourth storage unit 570. It may be determined based on the difference in values. As shown in FIG. 6, after writing the heat exchange amount data to the fourth storage unit 570 (step S460), the heat amount calculation unit 550 is written to the third storage unit 560 and the fourth storage unit 570. The magnitude relation of the value of the heat exchange amount may be determined (step S471). If the value of the heat exchange amount written in the fourth storage unit 570 exceeds the value of the heat exchange amount written in the third storage unit 560 by a predetermined value or more (step S471: Yes), the change unit 540 , The reduction adjustment process is executed (step S200).

If the value of the heat exchange amount in the fourth storage unit 570 does not exceed the value of the heat exchange amount in the third storage unit 560 by a predetermined value or more (step S471: No), the heat amount calculation unit 550 is referred to as step S471. The reverse judgment process is performed. That is, the heat amount calculation unit 550 determines whether or not the value of the heat exchange amount in the fourth storage unit 570 is less than a predetermined value or more than the value of the heat exchange amount in the third storage unit 560 (step S472). .. If the value of the heat exchange amount written in the fourth storage unit 570 is less than a predetermined value or more than the value of the heat exchange amount written in the third storage unit 560 (step S472: Yes), the change unit 540 , The increase adjustment process is executed (step S300). In another case (step S472: No), the calorific value calculation unit 550 waits for the elapse of a predetermined period from the determination process of step S472 (step S440). After that, the heat amount calculation unit 550 recalculates the heat exchange amount in a state where the frequency at which the net power W written in the third storage unit 560 was obtained in step S430 is maintained (step S450). The heat amount calculation unit 550 writes the recalculated heat exchange amount to the fourth storage unit 570 (step S460), and then re-executes the determination process of step S471.

Under the control shown in FIG. 6, if the amount of change in the amount of heat exchange is less than a predetermined value, the frequency of the fan 230 is maintained, so that the frequency of changing the frequency of the fan 230 is reduced. Therefore, the stable operation of the binary power generation system 1 can be obtained.

With respect to the first control at the time of startup of the above-described embodiment, the reduction adjustment process is performed before the increase adjustment process. However, the increase adjustment process may be performed prior to the decrease adjustment process (see FIG. 7). In this case, after the net power W calculated under the default frequency is written to the first storage unit 520 (step S120), the change unit 540 determines whether or not the increase adjustment process can be continued (step S120). Step S310). When the determination result that the increase adjustment process cannot be continued is obtained (step S310: No), the control for the fan 230 shifts to the second control for steady operation (step S400).

When the determination result that the increase adjustment process can be continued is obtained (step S310: Yes), the control unit 500 executes a series of control operations (steps S320 to S370) in the increase adjustment process. The increase adjustment process is executed until the value of the net power W written in the second storage unit 530 becomes equal to or less than the value of the net power W written in the first storage unit 520. When the value of the net power W written in the second storage unit 530 becomes equal to or less than the value of the net power W written in the first storage unit 520 (step S360: No), the control for the fan 230 is increased adjustment processing (step). The process proceeds from S300) to the reduction adjustment process (step S200).

When the reduction adjustment process is started, the change unit 540 determines whether or not the reduction adjustment process can be continued (step S210). When the determination result that the reduction adjustment process cannot be continued is obtained (step S210: No), the control for the fan 230 shifts to the second control for steady operation (step S400).

When the determination result that the reduction adjustment processing can be continued is obtained (step S210: Yes), the control unit 500 executes a series of control operations (steps S220 to S270) in the reduction adjustment processing. The reduction adjustment process is executed until the value of the net power W written in the second storage unit 530 becomes equal to or less than the value of the net power W written in the first storage unit 520. When the value of the net power W in the second storage unit 530 becomes equal to or less than the value of the net power W in the first storage unit 520 (step S260: No), the control for the fan 230 is steady from the reduction adjustment process (step S200). The second control for operation (step S400) is started.

Even if the increase adjustment process is performed before the decrease adjustment process, the binary power generation system 1 can achieve a high net power W.

Regarding the above-described embodiment, the detection signals from the temperature sensors 601 and 604 are used to detect the change in the amount of heat exchange. Instead of the temperature sensors 601, 604, a temperature sensor 607 that detects the ambient temperature (hereinafter referred to as ambient temperature) of the binary power generation system 1 may be used (see FIG. 8). The temperature sensor 607 is arranged so as to detect the ambient temperature around the binary power generation system 1. The temperature sensor 607 is configured to generate a detection signal representing the detected temperature.

The detection signal from the temperature sensor 607 is used for detecting a change in the amount of heat exchange (step S450 in FIG. 4). In step S450, the heat amount calculation unit 550 of the control unit 500 calculates the heat exchange amount based on the detection signal from the temperature sensor 607.

Since the fan 230 takes in the air around the binary power generation system 1 and creates an air flow in the housing 220, the amount of heat exchange in the dry cooler 200 is affected by the ambient temperature around the binary power generation system 1. To. While the binary power generation system 1 is in steady operation, the control unit 500 receives the detection signal from the temperature sensor 607.

When the ambient temperature drops, the temperature of the airflow created by the fan 230 drops, and the amount of heat exchange in the dry cooler 200 increases. In this case, by lowering the frequency of the fan 230, the net power W may be able to take a higher value. The control unit 500 executes the reduction adjustment process, and the binary power generation system 1 searches for the frequency of the fan 230 that achieves a higher net power W. In the first step S210 (see FIG. 3) of the reduction adjustment process, when it is determined that the reduction adjustment process cannot be continued, the frequency of the fan 230 is maintained. When it is determined in the second and subsequent steps S210 that the reduction adjustment process cannot be continued, the fan 230 is driven at the frequency found in the reduction adjustment process. As long as the determination result that the reduction adjustment processing can be continued is obtained in step S210, the value of the net power W stored in the second storage unit 530 in the reduction adjustment processing in step S260 is the value of the first storage unit. It is continued until the value of the net power W stored in 520 is exceeded. After that, the increase adjustment process is executed. As a result, a frequency that achieves a high net power W after a change in the amount of heat exchange is found through the reduction adjustment process and the increase adjustment process.

When the ambient temperature rises, the temperature of the airflow created by the fan 230 rises, and the amount of heat exchange in the dry cooler 200 (and by extension, the electric power We generated by the binary power generation device 100) decreases. As the power We decreases, the value of the net power W may be lower than the value achieved under the first control. When the amount of heat exchange in the dry cooler 200 decreases, the control unit 500 executes an increase adjustment process and searches for the frequency of the fan 230 that achieves a high net power W. When a new frequency that achieves a high net power W is found through the increment adjustment process, the fan 230 is driven at the new frequency. If, as a result of the increase adjustment process, no frequency is found that achieves a high net power W, the fan 230 is driven at the frequency before the increase adjustment process.

Even if the temperature sensor 607 that detects the ambient temperature is used, the change in the heat exchange amount can be detected. Therefore, the control unit 500 newly sets the frequency of the fan 230 after the change in the heat exchange amount and raises the frequency. A net power W can be achieved.

Regarding the above-described embodiment, the flow rate of the cooling fluid represented by the detection signal from the flow rate sensor 605 is used to calculate the heat exchange amount. However, the flow rate of the cooling fluid may be calculated based on the difference between the pressure of the cooling fluid flowing into the condenser 140 and the pressure of the cooling fluid flowing out of the condenser 140. In this case, instead of the flow rate sensor 605, a pressure sensor for detecting these pressures is attached to the cooling fluid circulation flow path 300.

1 ... Binary power generation system 100 ... Binary power generation device 110 ... Evaporator 120 ... Expander 130 ... Generator 140 ... Condenser 150 ... Operating medium pump 160 ... -Operating medium circulation flow path 200 ... Dry cooler 210 ... Heat transfer tube 230 ... Fan 400 ... Cooling fluid pump 500 ... Control unit 510 ... Power calculation unit 540 ... Change unit 550・ ・ ・ Calorie calculation unit

Claims (6)

An evaporator that evaporates the working medium, an expander that is driven under the expansion of the evaporated working medium, a generator connected to the expander, and the working medium that flows out of the expander are cooled by a cooling fluid. A condenser for condensing the working medium, a working medium pump for sending the working medium flowing out of the condenser to the evaporator, and the evaporator, the expander, the condenser, and the working medium pump. A binary power generator including a working medium circulation flow path connected in this order, and
A dry cooler having a heat transfer tube for flowing the cooling fluid flowing out of the condenser and a fan forming an air flow for air-cooling the cooling fluid flowing in the heat transfer tube.
A cooling fluid pump that circulates the cooling fluid between the condenser and the heat transfer tube,
A control unit that controls the frequency of the fan is provided so that the net power calculated by subtracting the power required to drive the cooling fluid pump and the fan from the power generated by the binary power generator is increased. Binary power generation system. In the binary power generation system according to claim 1,
The control unit is a binary power generation system that controls the frequency of the fan so that the net power is increased based on the change in the amount of heat exchange between the cooling fluid and the air flow. In the binary power generation system according to claim 2.
The fan takes in the air around the binary power generation system to generate the airflow.
The control unit is a binary power generation system that calculates the heat exchange amount based on the ambient temperature around the binary power generation system. In the binary power generation system according to claim 1 or 3.
The control unit includes a change unit configured to change and set the frequency of the fan, and a power calculation unit for calculating the net power before and after the change of the frequency of the fan.
The change unit is a binary power generation system that sets the larger of the net power calculated by the power calculation unit to the frequency of the fan. In the binary power generation system according to claim 4.
The control unit includes a heat quantity calculation unit that calculates a heat exchange amount between the cooling fluid and the air flow based on the ambient temperature around the binary power generation system.
The change unit adjusts the frequency of the fan so that the net power increases based on the change in the heat exchange amount calculated by the heat amount calculation unit after the frequency of the fan is changed by the change unit. Binary power generation system to be reconfigured. In the binary power generation system according to any one of claims 1 to 5.
The control unit is a binary power generation system that controls the frequency of the cooling fluid pump toward a predetermined value.

Images