JP5639515B2 - Binary power generator and control method thereof - Google Patents

Description

  The present invention relates to a binary power generation apparatus and a control method thereof.

  Conventionally, as disclosed in Patent Document 1 below, a binary power generation apparatus is known in which a generator is driven by a turbine provided in a circulation circuit in which a working medium circulates. In the binary power generation apparatus disclosed in Patent Document 1, a liquid level gauge is provided in each of the evaporator and the condenser, and there is a room for raising the working fluid liquid level measured by the liquid level gauge. In addition, by adjusting the output of the circulation pump so that the working fluid liquid level increases, the output of the turbine is adjusted so as not to decrease by increasing the evaporation pressure.

Japanese Patent Laid-Open No. 10-103030

  However, the binary power generation device disclosed in Patent Document 1 has a configuration in which the liquid level of the evaporator and the condenser is measured with a liquid level gauge, and thus there is a problem that stable liquid level control cannot be performed. is there. That is, since the working medium flows in a gas-liquid two-phase state in the evaporator and the condenser, it is difficult to measure the interface between the gas and the liquid with a liquid level gauge. For this reason, stable liquid level control cannot be performed. In particular, when a plate heat exchanger is used, it is difficult to determine the interface between the gas and the liquid because the working medium that has become a gas-liquid two-phase flow flows in a narrow space.

  Therefore, the present invention has been made in view of the above prior art, and its object is to change the amount of working fluid in a condenser without directly measuring the liquid level in a binary power generation device. It is to be able to suppress.

  To achieve the above object, the present invention provides an evaporator for evaporating the working medium, an expander for expanding the working medium vapor, a condenser for condensing the working medium vapor, a circulation pump for circulating the working medium, Is a binary power generation device having a circulation circuit connected in series and driving a generator with the expander, and detecting outlet temperature detecting means for detecting outlet temperature of the condenser and detecting outlet pressure of the condenser Outlet pressure detection means, derivation means for deriving the saturated vapor pressure of the working medium at the outlet of the condenser from the detection value of the outlet temperature detection means, outlet pressure detected by the outlet pressure detection means, and derivation by the derivation means Adjustment control means for performing control to adjust the circulation amount of the working medium or the cooling water amount of the condenser according to the differential pressure with respect to the saturated steam pressure. .

  In the present invention, the differential pressure between the outlet pressure of the condenser detected by the outlet pressure detecting means and the saturated vapor pressure of the working medium at the outlet of the condenser derived from the detected outlet temperature of the condenser is obtained. Control is performed to adjust the circulating amount of the working medium or the cooling water amount of the condenser according to the pressure. That is, the differential pressure between the actually detected outlet pressure and the derived saturated vapor pressure can be regarded as a pressure corresponding to the liquid level in the condenser. By adjusting the amount of circulation or the amount of cooling water in the condenser, fluctuations in the amount of liquid in the condenser can be suppressed. Therefore, the liquid level can be stabilized in a pseudo manner.

  Here, the adjustment control means may perform control to adjust the circulating amount of the working medium or the cooling water amount of the condenser so that the liquid level calculated from the differential pressure is within a predetermined range. In this embodiment, the liquid level height in the condenser is determined from the differential pressure between the detected outlet pressure of the condenser and the saturated vapor pressure of the working medium at the outlet of the condenser derived from the detected outlet temperature of the condenser. And the circulating amount of the working medium or the cooling water amount of the condenser is adjusted so that the calculated liquid level is within a predetermined range. Therefore, the calculated liquid level can be stabilized.

  The adjustment control means may perform control to adjust the circulating amount of the working medium or the cooling water amount of the condenser so that the differential pressure is within a predetermined range. Since the differential pressure can be regarded as a pressure corresponding to the liquid level in the condenser, the pseudo liquid level in the condenser can be controlled stably in this aspect as well.

  The present invention relates to a circulation circuit in which an evaporator for evaporating the working medium, an expander for expanding the working medium vapor, a condenser for condensing the working medium vapor, and a circulation pump for circulating the working medium are connected in series. And a method of controlling a binary power generator that drives a generator with the expander, wherein the outlet temperature detecting step detects the outlet temperature of the condenser, and the outlet pressure detection step detects the outlet pressure of the condenser. A derivation step for deriving a saturated vapor pressure of the working medium at the outlet of the condenser from the temperature detection value detected in the outlet temperature detection step, an outlet pressure detected in the outlet pressure detection step, and a derivation step. An adjustment control step for performing control to adjust the circulating amount of the working medium or the cooling water amount of the condenser according to the differential pressure with the saturated steam pressure. A control method of Lee generator.

  In the adjustment control step, control may be performed to adjust the circulating amount of the working medium or the cooling water amount of the condenser so that the liquid level calculated from the differential pressure is within a predetermined range.

  In the adjustment control step, control may be performed to adjust the circulating amount of the working medium or the cooling water amount of the condenser so that the differential pressure is within a predetermined range.

  As described above, according to the present invention, in the binary power generation apparatus, it is possible to suppress fluctuations in the amount of working fluid in the condenser without directly measuring the liquid level.

It is a figure which shows the structure of the binary electric power generating apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the correlation with the temperature of the working medium memorize | stored in the controller, and saturated vapor pressure. It is a figure for demonstrating the state of the working medium at the time of the driving | running operation | movement of the said binary electric power generating apparatus. It is a figure for demonstrating the control action regarding the liquid level height adjustment at the time of the driving | running operation | movement of the said binary power generator. It is a figure which shows the structure of the binary electric power generating apparatus which concerns on 2nd Embodiment of this invention. It is a figure for demonstrating the control action regarding the liquid level height adjustment at the time of the driving | running operation | movement of the said binary power generator.

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

(First embodiment)
As shown in FIG. 1, the binary power generation apparatus 10 according to the first embodiment includes a circulation circuit 12 that circulates a working medium. The circulation circuit 12 includes an evaporator 14, an expander 16, and a condenser. The vessel 18 and the circulation pump 20 are connected in series in this order. As the working medium, for example, a low-boiling organic medium (such as chlorofluorocarbon) having a lower boiling point than water such as R245fa can be used.

  The evaporator 14 is for evaporating the working medium (liquid) flowing through the circulation circuit 12, and is configured to heat the working medium with hot water flowing through a circuit 21 different from the circulation circuit 12, for example. . That is, the evaporator 14 has a passage through which the working medium flows and a passage through which the hot water flows, and exchanges heat between the hot water and the working medium.

  The expander 16 is disposed on the downstream side of the evaporator 14 in the circulation circuit 12 and extracts the kinetic energy from the working medium by expanding the working medium (vapor) evaporated in the evaporator 14. A generator 24 is connected to the drive shaft of the expander 16. Electric power can be generated by the generator 24 as the drive shaft of the expander 16 rotates. The expander 16 can be configured by, for example, a screw expander, a rotary expander, a scroll expander, a turbo expander, a reciprocal expander, a turbine, or the like.

  The condenser 18 is disposed on the downstream side of the expander 16 in the circulation circuit 12 and condenses the working medium (steam) expanded (depressurized) by the expander 16. For example, the condenser 18 cools and condenses the working medium with cooling water flowing through a circuit (cooling water circuit) 22 of a system different from the circulation circuit 12. That is, the condenser 18 has a passage through which the cooling water flows and a passage through which the working medium flows, and exchanges heat between the cooling water and the working medium.

  The circulation pump 20 is provided for circulating the working medium in the circulation circuit 12, and is disposed on the downstream side of the condenser 18 in the circulation circuit 12. That is, the circulation pump 20 is provided in a pipe connecting the condenser 18 and the evaporator 14 in the circulation circuit 12, sucks the working medium (liquid) on the condenser 18 side, and discharges it to the evaporator 14 side. To do. As the circulation pump 20, a centrifugal pump having an impeller as a rotor, a gear pump in which the rotor is composed of a pair of gears, and the like are preferably used.

  A bypass passage 26 is connected to the circulation circuit 12 so as to bypass the circulation pump 20. A control valve 28 is provided in the bypass passage 26. The control valve 28 may be a flow rate control valve whose opening degree can be adjusted, or may be an on-off valve that can only be opened and closed.

  The circulation circuit 12 is provided with a temperature sensor 31 as an example of means for detecting the outlet temperature of the condenser 18 and a pressure sensor 33 as an example of means for detecting the outlet pressure of the condenser 18. The temperature sensor 31 and the pressure sensor 33 are provided on the outlet side of the condenser 18, that is, between the condenser 18 and the circulation pump 20 in the circulation circuit 12.

  The temperature sensor 31 and the pressure sensor 33 are electrically connected to the controller 35. The controller 35 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 controller 35 include derivation means 37, adjustment control means 39, and the like.

  The deriving unit 37 derives the saturated vapor pressure of the working medium at the outlet of the condenser 18 from the detection value of the temperature sensor 31. That is, the controller 35 stores an information table that correlates the temperature of the working medium and the saturated steam pressure, and the deriving means 37 derives the saturated steam pressure of the working medium using this table and relational expressions. This table or relational expression shows the correlation between temperature and saturated steam pressure, as shown in FIG. 2, for example.

  The adjustment control means 39 calculates a difference (differential pressure) between the outlet pressure detected by the pressure sensor 33 and the saturated vapor pressure derived by the deriving means 37, and the circulation is performed according to the derived differential pressure. The output of the pump 20 is adjusted. This point will be specifically described below.

  The differential pressure (P−E) [MPa] between the outlet pressure P [MPa] detected by the pressure sensor 33 and the saturated vapor pressure E [MPa] is a pressure corresponding to the liquid level in the condenser 18. . That is, when the specific gravity of the working medium is ρ, the liquid level height H [m] can be expressed as follows. Therefore, the pseudo liquid level can be determined by calculating the differential pressure (P−E).

H = (P−E) × 100 / ρ
Next, the operation of the binary power generator 10 according to the first embodiment will be described with reference to FIGS. 1 and 3. The state of the working medium corresponding to the positions (1), (2), (3), and (4) in FIG. 1 is also shown in FIG.

  When the circulation pump 20 is driven, the working medium circulates in the circulation circuit 12. The working medium sent out from the circulation pump 20 flows into the evaporator 14, heat exchanges with warm water in the evaporator 14 and evaporates to become a gaseous working medium (state (1) in FIG. 3). The gaseous working medium expands in the expander 16 (state (2) in FIG. 3). At this time, the drive shaft of the expander 16 is driven. As a result, the generator 24 is driven to generate power. The working medium is cooled and condensed by the cooling water in the condenser 18 (state (3) in FIG. 3). The pressure (outlet pressure) of the working medium on the outlet side of the condenser 18 is P [MPa], which is higher than the saturated vapor pressure E obtained from the outlet temperature. Then, the working medium condensed by the condenser 18 is sent from the circulation pump 20 to the state (4) in FIG. In the circulation circuit 12, this circulation is repeated.

  In the binary power generation apparatus 10, during this operation, the temperature and pressure of the working medium on the outlet side of the condenser 18 are detected (outlet temperature detection step, outlet pressure detection step). Then, the control operation shown in FIG. 4 is executed.

  That is, the controller 35 derives the saturated vapor pressure E of the working medium at the outlet of the condenser 18 from the detection value of the temperature sensor 31 (derivation step), and the outlet detected by the derived saturated vapor pressure and the pressure sensor 33. From the pressure P, the differential pressure (P-E) between them is calculated. Then, the controller 35 derives the liquid level height of the working medium in the condenser 18 corresponding to the differential pressure (PE), and the derived liquid level height is higher than the first predetermined value a. It is determined whether or not it is larger (step ST1). The first predetermined value a is a value set in advance as an upper limit value. When the liquid level is larger than the predetermined value a, control for increasing the circulating amount of the working medium is executed (step ST2). That is, when the liquid level in the condenser 18 becomes high, the condensation capacity is sufficient with respect to the circulation amount of the working medium. Therefore, the condensation capacity is lowered or the working medium in the circulation circuit 12 is reduced. It is effective to increase the amount of circulation. The control in step ST2 may be a control for increasing the output of the circulation pump 20, a control for closing the control valve 28, or a control for reducing the opening of the control valve 28. Good. By increasing the circulation amount of the working medium in the circulation circuit 12, the amount of the liquid working medium stored in the condenser 18 is reduced, so that the liquid level can be reduced.

  On the other hand, if the derived liquid level is equal to or less than the first predetermined value a, the process proceeds to step ST3. In step ST3, it is determined whether or not the derived liquid level is smaller than a second predetermined value b. The second predetermined value b is a value preset as a lower limit value, and is a value smaller than the first predetermined value a. If the liquid level is equal to or higher than the second predetermined value b, the process returns. On the other hand, when the liquid level is smaller than the second predetermined value b, control for reducing the circulation amount of the working medium is executed (step ST4). This control may be control for reducing the output of the circulation pump 20, control for opening the control valve 28, or control for increasing the opening degree of the control valve 28. Since the amount of the working medium circulated in the circulation circuit 12 is reduced, the amount of the liquid working medium stored in the condenser 18 is increased, so that the liquid level can be increased. Steps ST <b> 1 to ST <b> 4 are adjustment control steps for performing control to adjust the circulation amount of the working medium according to the differential pressure (P−E) between the outlet pressure P and the saturated steam pressure E.

  As described above, in the binary power generation device 10 according to the first embodiment, the working medium at the outlet of the condenser 18 derived from the detected outlet pressure P of the condenser 18 and the detected outlet temperature of the condenser 18. Then, a differential pressure (PE) from the saturated steam pressure E is obtained, and control is performed to adjust the circulation amount of the working medium in accordance with the differential pressure (PE). That is, the differential pressure (P−E) between the actually detected outlet pressure P and the saturated vapor pressure E derived by calculation can be regarded as a pressure corresponding to the liquid level in the condenser 18. Therefore, by adjusting the circulation amount of the working medium according to the differential pressure (P−E), the fluctuation of the liquid amount in the condenser 18 can be suppressed. Therefore, the liquid level can be stabilized in a pseudo manner.

  Moreover, in this embodiment, the differential pressure (P−) between the detected outlet pressure P of the condenser 18 and the saturated vapor pressure E of the working medium at the outlet of the condenser 18 derived from the detected outlet temperature of the condenser 18. E), the liquid level in the condenser 18 is calculated, and the circulating amount of the working medium is adjusted so that the calculated liquid level falls within a predetermined range. Therefore, the calculated liquid level can be stabilized.

  In the present embodiment, the form in which the bypass passage 26 is provided has been described. However, the present invention is not limited to this, and the control valve 28 of the bypass passage 26 is omitted, and according to the derived liquid level height. The output of the circulation pump 20 may be adjusted.

(Second Embodiment)
FIG. 5 shows a second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same component as 1st Embodiment here, and the detailed description is abbreviate | omitted.

  In the first embodiment, the liquid level in the condenser 18 is controlled by controlling the output of the circulation pump 20 or controlling the opening and closing of the control valve 28. However, in the second embodiment, the cooling water circuit 22 is controlled. The liquid level in the condenser 18 is controlled by controlling the cooling capacity of the condenser 18 by the cooling water flowing through the condenser 18.

  The cooling water circuit 22 is provided with a control valve 42, and the cooling water circuit 22 (particularly, the cooling water passage in the condenser 18 in the cooling water circuit 22) is controlled by opening / closing or opening degree control of the control valve 42. The amount of cooling water flowing can be adjusted. As shown in FIG. 5, the control valve 42 is provided in the branch passage 43 provided in the cooling water circuit 22. However, the control valve 42 is provided directly in the piping of the cooling water circuit 22 without providing the branch passage 43. Also good. However, in this case, the open / close control of the control valve 42 is reversed.

  The adjustment control means 39 of the controller 35 calculates the difference (differential pressure) between the saturated vapor pressure E derived by the deriving means 37 and the outlet pressure P detected by the pressure sensor 33, and this derived differential pressure is calculated. The control valve 42 of the cooling water circuit 22 is controlled according to (PE). That is, the controller 35 detects the liquid level of the working medium in the condenser 18 corresponding to the differential pressure (P−E) between the outlet pressure P detected by the pressure sensor 33 and the saturated vapor pressure E derived by the deriving means 37. The height is derived, and as shown in FIG. 6, it is determined whether or not the derived liquid level height exceeds a preset threshold value (step ST11). Then, when the liquid surface height exceeds the threshold value, control is performed to reduce the amount of cooling water flowing into the condenser 18 (step ST12). That is, the control valve 42 provided in the branch passage 43 of the cooling water circuit 22 is opened (or the opening degree is increased). Thereby, since the cooling capacity of the condenser 18 can be suppressed, the amount of the liquid working medium stored in the condenser 18 can be reduced, and the liquid level can be reduced.

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

  In the second embodiment, the cooling water amount is adjusted only when the liquid surface height exceeds the threshold value. However, the present invention is not limited to this. Similarly to the first embodiment, an upper limit value and a lower limit value of the liquid level height may be set, and the cooling water amount may be increased or decreased so that the liquid level height falls within this range.

  In the second embodiment, the cooling water amount may be adjusted and the output of the circulation pump 20 may be adjusted together.

  In the second embodiment, the configuration in which the bypass passage 26 of the circulation circuit 12 is omitted has been described. However, a bypass passage 26 having a control valve 28 may be provided as in the first embodiment. In this case, the amount of cooling water is adjusted by controlling the control valve 42, and the circulation amount of the working medium is adjusted by controlling the control valve 28 of the bypass passage 26.

  In the first and second embodiments, control is performed to adjust the circulating amount of the working medium or the cooling water amount of the condenser 18 so that the liquid level derived from the differential pressure (PE) falls within a predetermined range. However, instead of this, the adjustment control means 39 does not circulate the working medium or cools the condenser 18 so that the differential pressure (P-E) between the outlet pressure P and the saturated steam pressure E is within a predetermined range. You may make it perform control which adjusts the amount of water.

DESCRIPTION OF SYMBOLS 10 Binary power generator 12 Circulation circuit 14 Evaporator 16 Expander 18 Condenser 20 Circulation pump 21 Circuit 22 Cooling water circuit 24 Generator 26 Bypass passage 28 Control valve 31 Temperature sensor 33 Pressure sensor 35 Controller 37 Derivation means 39 Adjustment control means 42 Control valve 43 Branch passage

Claims (4)

An evaporator that evaporates the working medium; an expander that expands the working medium vapor; a condenser that condenses the working medium vapor; and a circulation pump that circulates the working medium. A binary power generator that drives a generator with an expander,
Outlet temperature detecting means for detecting the outlet temperature of the condenser;
Outlet pressure detection means for detecting the outlet pressure of the condenser;
Derivation means for deriving the saturated vapor pressure of the working medium at the outlet of the condenser from the detection value of the outlet temperature detection means;
Adjustment control for performing control to adjust the circulation amount of the working medium or the cooling water amount of the condenser in accordance with the differential pressure between the outlet pressure detected by the outlet pressure detection means and the saturated steam pressure derived by the derivation means. and it means, possess,
The adjustment control means derives the liquid level height in the condenser based on the differential pressure , and circulates the working medium or the condensation so that the derived liquid level height falls within a predetermined range. Binary power generator that controls the amount of cooling water in the unit. A bypass passage connected to the circulation circuit and bypassing the expander;
A control valve provided in the bypass passage,
The binary power generation device according to claim 1, wherein the adjustment control unit performs control for adjusting a circulation amount of the working medium by adjusting an opening / closing or opening degree of the control valve . An evaporator that evaporates the working medium; an expander that expands the working medium vapor; a condenser that condenses the working medium vapor; and a circulation pump that circulates the working medium. A control method of a binary power generation device that drives a generator with an expander,
An outlet temperature detecting step for detecting an outlet temperature of the condenser;
An outlet pressure detecting step for detecting an outlet pressure of the condenser;
A derivation step of deriving a saturated vapor pressure of the working medium at the outlet of the condenser from the temperature detection value detected in the outlet temperature detection step;
Adjustment control for performing control to adjust the circulating amount of the working medium or the cooling water amount of the condenser according to the differential pressure between the outlet pressure detected in the outlet pressure detecting step and the saturated steam pressure derived in the deriving step step and are included,
In the adjustment control step, the liquid level height in the condenser is derived based on the differential pressure, and the circulating amount of the working medium or the condensation is set so that the derived liquid level height falls within a predetermined range. A control method for a binary power generation device that performs control to adjust the amount of cooling water in the generator. The binary power generator further includes a bypass passage connected to the circulation circuit and bypassing the expander, and a control valve provided in the bypass passage,
4. The control method for a binary power generation device according to claim 3, wherein in the adjustment control step, control is performed to adjust a circulation amount of the working medium by adjusting opening / closing or opening of the control valve.

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