JP6170487B2 - Thermal energy recovery device - Google Patents

Description

  The present invention relates to a thermal energy recovery device.

  2. Description of the Related Art Conventionally, a thermal energy recovery apparatus that recovers power from steam (gas phase heating medium) such as exhaust gas discharged from various facilities in a factory is known. For example, in Patent Document 1, an evaporator that heats a working medium by a gas phase heating medium supplied from an external heat source, and a working medium that has not yet flowed into the evaporator are heated by a heating medium that has flowed out of the evaporator. A preheater, a screw expander that expands the working medium flowing out of the evaporator, a generator connected to the screw expander, a condenser that condenses the working medium flowing out of the screw expander, and a condenser And a pump for feeding the working medium to the preheater, a power generation device (thermal energy recovery device) is disclosed. Each of the preheater and the evaporator has a working medium flow path through which the working medium flows and a heating medium flow path through which the heating medium flows.

JP 2012-211591 A

  In the thermal energy recovery apparatus described in Patent Document 1, the heating medium flowing out from the evaporator flows into the preheater in any state of a gas phase, a liquid phase, or a gas-liquid two phase. In this case, it is known that a so-called water hammer phenomenon may occur in the preheater. This water hammer phenomenon is presumed to occur mainly by the following principle.

  When a gas phase heating medium (steam or high-temperature gas) flows into the heating medium flow path of the preheater, the heating medium is condensed by being cooled to a liquid (drain or mist) in the heating medium flow path. The volume suddenly decreases. As a result, a relatively low pressure region is generated in the heating medium flow path. As a result, the liquid in the heating medium flow path moves toward the relatively low pressure region, so that the liquid collides with the inner surface of the heating medium flow path.

  The objective of this invention is providing the thermal energy recovery apparatus which can suppress generation | occurrence | production of the water hammer phenomenon in a preheater.

  As means for solving the above-mentioned problems, the present invention provides an evaporator that evaporates the working medium by exchanging heat between the gas-phase heating medium supplied from the outside and the working medium, and the heating medium that flows out of the evaporator And a preheater for heating the working medium by exchanging heat with the working medium before flowing into the evaporator, and recovering the expansion energy of the working medium flowing out from the evaporator and supplying the working medium to the preheater When the supercooling degree of the energy recovery unit to be sent and the heating medium flowing into the preheater is not larger than 0 degrees, the heating medium is prohibited from flowing into the preheater and the heating medium flows into the preheater There is provided a thermal energy recovery device comprising: a control unit that performs an operation of causing the heating medium to flow into the preheater when the degree of supercooling of the medium is greater than 0 degrees.

  In the present thermal energy recovery apparatus, it is possible to suppress the occurrence of the water hammer phenomenon in the preheater while recovering the thermal energy obtained by the working medium in the preheater and the evaporator by the energy recovery unit. Specifically, when the degree of supercooling of the heating medium flowing into the preheater is not greater than 0 degrees (when a gas phase heating medium may exist), the heating medium is prohibited from flowing into the preheater, When the degree of cooling is greater than 0 degrees, the heating medium flows into the preheater. That is, the liquid phase heating medium flows into the preheater. Therefore, the occurrence of the water hammer phenomenon in the preheater is suppressed. More specifically, the occurrence of a water hammer phenomenon caused by condensation of the gas phase heating medium in the preheater after flowing into the preheater is suppressed.

  In this case, the control unit has a degree of supercooling of the heating medium flowing into the preheater larger than 0 degree, and a degree of supercooling of the heating medium flowing out of the evaporator is a specific lower limit value or more. The heating medium is allowed to flow into the preheater while the supercooling degree of the heating medium flowing into the preheater is not greater than 0 degrees, or even if the supercooling degree is greater than 0 degrees, the evaporator When the degree of supercooling of the heating medium flowing out of the heating medium is less than the lower limit value, it is preferable to perform an operation of prohibiting the heating medium from entering the preheater.

  In this way, in addition to suppressing the occurrence of the water hammer phenomenon in the preheater, the occurrence of the water hammer phenomenon in the evaporator is also suppressed. Specifically, when the degree of supercooling of the heating medium flowing out of the evaporator is less than the lower limit value, the heating medium may be in a gas-liquid two-phase state, for example. In this case, when the heating medium flows into the preheater, pressure loss occurs in the preheater, so that the heating medium is difficult to pass through the preheater. For this reason, the heat exchange efficiency in the preheater is reduced, and further, the pressure loss is a cause (resistance), and the liquid heating medium (drain) is less likely to flow out of the evaporator. When a vapor phase heating medium flows into the evaporator in this state, the vapor phase heating medium is rapidly cooled by the drain, so that its volume is suddenly reduced. . On the other hand, in this energy recovery device, when the degree of supercooling of the heating medium flowing out from the evaporator is less than the lower limit value, the heating medium is prohibited from flowing into the preheater, thereby improving the heat exchange efficiency in the preheater. As a result, a state in which the liquid phase heating medium (drain) is less likely to flow out of the evaporator due to the pressure loss is avoided (outflow of the liquid phase heating medium is promoted). The occurrence of the water hammer phenomenon in the evaporator is suppressed.

  Further, in the present invention, the control unit has a degree of supercooling of the heating medium flowing into the preheater greater than 0 degrees, and a degree of supercooling of the heating medium flowing out of the evaporator is a specific upper limit value or less. In the case where the heating medium is allowed to flow into the preheater, the supercooling degree of the heating medium flowing into the preheater is not greater than 0 degree, or even if the supercooling degree is greater than 0 degree. When the degree of supercooling of the heating medium flowing out from the evaporator is larger than the upper limit value, it is preferable to perform an operation of discharging the heating medium to the outside without flowing into the preheater.

  In this way, in addition to suppressing the occurrence of the water hammer phenomenon in the preheater, the outflow of the liquid phase heating medium (drain) from the evaporator is promoted, so the water hammer phenomenon in the evaporator Is suppressed. Specifically, when the degree of supercooling of the heating medium flowing out of the evaporator is larger (too high) than the upper limit value, a liquid-phase heating medium corresponding to a considerable amount in the vicinity of the outlet of the flow path through which the heating medium flows in the evaporator (Drain) is accumulated. When a vapor phase heating medium flows into the evaporator in this state, the vapor phase heating medium is rapidly cooled by the drain, so that its volume is suddenly reduced. . On the other hand, when the liquid-phase heating medium flows into the preheater in that state, it takes time for the liquid-phase heating medium to pass through the preheater. It becomes difficult to leak. On the other hand, in this energy recovery apparatus, when the degree of supercooling of the heating medium flowing out from the evaporator is larger than the upper limit value (not only the latent heat of the heating medium but also the sensible heat is sufficiently recovered by the working medium in the evaporator). When the heating medium is discharged to the outside without flowing into the preheater, the time required for the liquid phase heating medium to be discharged from the evaporator is shortened. The drain outflow is promoted. Therefore, the occurrence of the water hammer phenomenon in the evaporator is suppressed.

  In the present invention, the control unit has a degree of supercooling of the heating medium flowing into the preheater larger than 0 degree and a degree of supercooling of the working medium flowing into the evaporator is larger than 0 degree. The heating medium is allowed to flow into the preheater while the supercooling degree of the heating medium flowing into the preheater is not greater than 0 degrees, or even if the supercooling degree is greater than 0 degrees, the evaporator It is preferable to perform an operation of prohibiting the heating medium from flowing into the preheater when the degree of supercooling of the working medium flowing into the heating medium is not greater than 0 degrees.

  In this way, in addition to suppressing the occurrence of the water hammer phenomenon in the preheater, the drift of the working medium in the evaporator is suppressed, so the heat exchange efficiency in the evaporator, that is, energy recovery. The energy recovery efficiency of the part is improved. For example, when a gas-liquid two-phase working medium flows into the evaporator, the specific gravity of the gas-phase working medium and the specific gravity of the liquid-phase working medium are different from each other. And a region through which the liquid-phase working medium passes are formed. For this reason, there is a concern that uniform heat exchange between the working medium and the heating medium is not performed in the evaporator (decrease in heat exchange efficiency). On the other hand, in this energy recovery device, when the degree of supercooling of the working medium flowing into the evaporator is not greater than 0 degrees (when a gaseous working medium may exist), the heating medium is supplied to the preheater. Since the inflow is prohibited, that is, the heating of the working medium by the heating medium in the preheater is stopped, it is suppressed that the working medium flowing out from the preheater contains a gas phase working medium. Therefore, the drift of the working medium in the evaporator is suppressed.

  In the present invention, it is preferable that the control unit performs an operation of discharging the heating medium to the outside without causing the heating medium to flow into the preheater when a predetermined stop condition is satisfied.

  By doing so, the outflow of the liquid phase heating medium (drain) from the evaporator is promoted at the time of stopping, so that the occurrence of the water hammer phenomenon in the evaporator at the start of the thermal energy recovery device is suppressed. . Specifically, when the stop condition is satisfied (when the apparatus is stopped), the heating medium is discharged outside without flowing into the preheater, so that no pressure loss occurs in the preheater. The drain of the drain is promoted. Therefore, the occurrence of the water hammer phenomenon in the evaporator at the start-up of the apparatus is suppressed.

  Moreover, in this invention, it is preferable to further provide the connection flow path which connects the said preheater and the said evaporator, and it is preferable that the said connection flow path has a shape extended on a straight line.

  In this way, the pressure loss generated in the connection flow path is reduced, so that when the working medium contains oil, the oil is prevented from staying in the connection flow path. As a result, an appropriate amount of oil flows into the energy recovery unit.

  As described above, according to the present invention, it is possible to provide a thermal energy recovery device capable of suppressing the occurrence of the water hammer phenomenon in the preheater.

It is a figure which shows the outline of a structure of the thermal energy recovery apparatus of one Embodiment of this invention. It is a flowchart which shows the control content of the control part at the time of starting and a steady operation. It is a flowchart which shows the control content of the control part at the time of a stop.

  A thermal energy recovery apparatus according to an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the thermal energy recovery apparatus includes an evaporator 10, a preheater 12, an energy recovery unit 20, a heating medium supply channel 30, and a control unit 40.

  The evaporator 10 evaporates the working medium by exchanging heat between a gas-phase heating medium (such as factory exhaust gas) supplied from the outside and the working medium (HFC245fa and the like). The evaporator 10 has a working medium flow path 10a through which the working medium flows and a heating medium flow path 10b through which the heating medium flows. In the present embodiment, a plate-type heat exchanger is used as the evaporator 10. However, as the evaporator 10, a so-called shell and tube heat exchanger may be used.

  The preheater 12 heats the working medium by exchanging heat between the heating medium flowing out of the evaporator 10 and the working medium before flowing into the evaporator 10. The preheater 12 has a working medium flow path 12a through which the working medium flows and a heating medium flow path 12b through which the heating medium flows. In the present embodiment, a plate-type heat exchanger is also used as the preheater 12. However, as in the case of the evaporator 10, a so-called shell and tube heat exchanger may be used as the preheater 12. The height position of the upstream end of the heating medium flow path 12b of the preheater 12 is the same as or lower than the height position of the downstream end of the heating medium flow path 10b of the evaporator 10. Is set. The height position of the downstream end of the working medium flow path 12a of the preheater 12 is set to be the same as the height position of the upstream end of the working medium flow path 10a of the evaporator 10. . The downstream end of the working medium flow path 12 a of the preheater 12 and the upstream end of the working medium flow path 10 a of the evaporator 10 are connected by a connection flow path 29. In the present embodiment, the connection channel 29 has a shape that extends in a straight line without having a bent portion.

  The energy recovery unit 20 includes an expander 22, a power recovery machine 23, a condenser 24, a pump 26, and a recovery flow path 28.

  The recovery flow path 28 is between the evaporator 10 and the expander 22, between the expander 22 and the condenser 24, between the condenser 24 and the pump 26, and between the pump 26 and the preheater 12. Connected. That is, a closed circuit (circulation circuit in which the working medium circulates so as to pass through the evaporator 10, the expander 22, the condenser 24, the pump 26, and the preheater 12 in this order) by the recovery flow path 28 and the connection flow path 29. Is formed. In this embodiment, oil circulates in the closed circuit together with the working medium.

  The expander 22 is provided at a site downstream of the evaporator 10 in the recovery flow path 28. The expander 22 expands the gas phase working medium that has flowed out of the evaporator 10. In the present embodiment, a positive displacement screw expander having a rotor that is rotationally driven by the expansion energy of the vapor-phase working medium that has flowed out of the evaporator 10 is used as the expander 22. Specifically, the expander 22 has a pair of male and female screw rotors.

  The power recovery machine 23 is connected to the expander 22. In the present embodiment, a power generator is used as the power recovery machine 23. The power recovery machine 23 has a rotating shaft connected to one of the pair of screw rotors of the expander 22. The power recovery machine 23 generates electric power when the rotating shaft rotates with the rotation of the screw rotor. In addition, as the power recovery machine 23, a compressor or the like may be used in addition to the generator.

  The condenser 24 is provided at a site on the downstream side of the expander 22 in the recovery flow path 28. The condenser 24 condenses (liquefies) the working medium flowing out from the expander 22 by cooling with a cooling medium (cooling water or the like) supplied from the outside.

  The pump 26 is provided at a site on the downstream side of the condenser 24 in the recovery flow path 28. The pump 26 pressurizes the liquid-phase working medium to a predetermined pressure and sends it to the preheater 12. As the pump 26, a centrifugal pump having an impeller as a rotor, a gear pump having a rotor composed of a pair of gears, a screw pump, a trochoid pump, or the like is used.

  The heating medium supply flow path 30 is a flow path for supplying the heating medium in this order from the external heat source that generates the gas phase heating medium to the evaporator 10 and the preheater 12. The heating medium supply channel 30 is configured to be connectable to the heating medium channel 10 b of the evaporator 10, and is configured to be connectable to the heating medium channel 12 b of the preheater 12.

  In the present embodiment, a drain tank 32 and a steam trap 34 are provided in a portion of the heating medium supply flow path 30 between the evaporator 10 and the preheater 12. The drain tank 32 stores a liquid phase heating medium out of the heating medium flowing out of the evaporator 10. The steam trap 34 prohibits passage of the gas phase heating medium out of the heating medium flowing out from the drain tank 32 and allows passage of the liquid phase heating medium.

  A bypass flow path 36 that bypasses the preheater 12 is connected to the heating medium supply flow path 30. Specifically, the upstream end of the bypass flow path 36 is connected to a portion of the heating medium supply flow path 30 between the steam trap 34 and the preheater 12, and is located downstream of the bypass flow path 36. The end is connected to a part of the heating medium supply flow path 30 that is downstream of the preheater 12.

  A first discharge channel 38 and a second discharge channel 39 are connected to the heating medium supply channel 30. The first discharge channel 38 is a channel for discharging the heating medium flowing out from the drain tank 32 to the outside, and is connected to a portion of the heating medium supply channel 30 between the drain tank 32 and the steam trap 34. Has been. The second discharge channel 39 is a channel for discharging the heating medium before flowing into the evaporator 10 to the outside, and is connected to a portion of the heating medium supply channel 30 upstream of the evaporator 10. Yes.

  The bypass channel 36 is provided with a first on-off valve V1. Of the heating medium supply flow path 30, a second downstream of the connection portion between the heating medium supply flow path 30 and the upstream end of the bypass flow path 36 and upstream of the preheater 12 is provided in the second position. An on-off valve V2 is provided. A third portion of the heating medium supply flow path 30 is located downstream of the preheater 12 and upstream of the connection portion between the heating medium supply flow path 30 and the downstream end of the bypass flow path 36. An on-off valve V3 is provided. The first discharge channel 38 is provided with a fourth on-off valve V4. The second discharge channel 39 is provided with a fifth on-off valve V5. A sixth on-off valve V6 is provided in a portion of the heating medium supply channel 30 upstream of the connection portion between the heating medium supply channel 30 and the second discharge channel 39. In the present embodiment, electromagnetic valves capable of switching between an open state and a closed state are used as the on-off valves V1 to V6.

  The control unit 40 performs a switching operation for switching opening / closing of the on-off valves V1 to V6 according to a predetermined condition. The condition is that the degree of supercooling α1 of the heating medium flowing into the preheater 12 is greater than 0 degree or not, and whether the degree of supercooling α2 of the heating medium flowing out of the evaporator 10 is within a certain range. Or whether the supercooling degree β of the working medium flowing out of the preheater 12 is greater than 0 degree, and whether the pressure P of the gas phase heating medium flowing into the evaporator 10 is less than a predetermined value P0, It is. The degree of supercooling α1 is a temperature sensor 41 and a pressure sensor 42 provided in a portion upstream of the preheater 12 in the heating medium supply flow path 30 (a portion between the preheater 12 and the second on-off valve V2). It derives based on each detected value. The degree of supercooling α2 is determined by each of the temperature sensor 43 and the pressure sensor 44 provided in a part downstream of the evaporator 10 (part between the evaporator 10 and the drain tank 32) in the heating medium supply channel 30. Derived from the detected value. The degree of supercooling β is derived from the detected values of the temperature sensor 45 and the pressure sensor 46 provided in the connection flow path 29. Here, the degree of supercooling refers to a temperature drop from the saturation temperature (condensation temperature). Specifically, it is calculated by “degree of supercooling = saturation temperature (condensation temperature) −temperature of heating medium or working medium”. That is, “the degree of supercooling is 0 degree” means that the temperature of the heating medium or the working medium is equal to the saturation temperature (condensation temperature). The pressure P is a pressure sensor provided in a portion of the heating medium supply channel 30 upstream of the evaporator 10 (a portion between the evaporator 10 and the upstream end of the second discharge channel 39). 47. The control unit 40 performs the switching operation while performing an operation of adjusting the rotational speed of the pump 26 so that the degree of superheat of the working medium flowing out of the evaporator 10 falls within a predetermined range.

  Next, specific control contents of the control unit 40 at the time of startup and normal operation will be described with reference to FIG. Before the start of operation of the energy recovery device (before starting), the first on-off valve V1 is in an open state, the second on-off valve V2 and the third on-off valve V3 are in a closed state, and the fourth on-off valve V4 and the fifth on-off valve are open. The valve V5 is in an open state, and the sixth open / close valve V6 is in a closed state.

  When the operation of the apparatus is started (step S10), the control unit 40 opens the first on-off valve V1, closes the second on-off valve V2 and the third on-off valve V3, and sets the fourth on-off valve V4 and the second on-off valve V4. The 5 on-off valve V5 is closed and the sixth on-off valve V6 is opened (step S11). As a result, the heating medium passes through the evaporator 10 and is discharged outside through the bypass channel 36 without flowing into the preheater 12. Moreover, supply of the cooling medium to the condenser 24 and driving of the pump 26 are also started by the start of operation. As a result, the working medium circulates in the closed circuit, so that power (in this embodiment, power) is recovered by the power recovery machine 23.

  Next, the control unit 40 determines whether or not the degree of supercooling α2 of the heating medium flowing out of the evaporator 10 is not less than a specific lower limit value a and not more than a specific upper limit value b (step S12). As a result, when the degree of supercooling α2 is less than the lower limit value a or greater than the upper limit value b (NO in step S12), the control unit 40 returns to step S12, that is, the heating medium flowing out of the evaporator 10 A state of discharging to the outside via the bypass channel 36 (hereinafter referred to as “bypass state”) is maintained.

  The reason for maintaining the bypass state when the degree of supercooling α2 is larger (too high) than the upper limit value b is to suppress the occurrence of the water hammer phenomenon in the evaporator 10. Specifically, when the apparatus is started, the temperature of the evaporator 10 is lower than that during steady operation, so that the heating medium flowing into the evaporator 10 is likely to condense, and thus the liquid in the heating medium flow path 10b. The phase heating medium (drain) is in a state where it tends to accumulate. When the drain accumulates in the heating medium flow path 10b, the degree of supercooling α2 flowing out from the heating medium flow path 10b increases. In other words, when the degree of supercooling α2 is high (when it is larger than the upper limit value b), it is considered that a considerable amount of drain is accumulated in the heating medium flow path 10b. If a vapor phase heating medium flows into the evaporator 10 in this state, the vapor phase heating medium is rapidly cooled by the drain, so that its volume is rapidly reduced. There is. On the other hand, when the liquid phase heating medium flows into the preheater 12 in this state, it takes time for the liquid phase heating medium to pass through the heating medium flow path 12b of the preheater 12, and therefore, from the inside of the evaporator 10. The liquid phase heating medium (drain) is less likely to flow out. Therefore, by maintaining the bypass state when the degree of supercooling α2 is larger than the upper limit b, the time required for the liquid-phase heating medium to be discharged from the evaporator 10 is shortened. The drain outflow from the vessel 10 is facilitated. Therefore, the occurrence of the water hammer phenomenon in the evaporator 10 is suppressed.

  Conversely, the reason for maintaining the bypass state when the degree of supercooling α2 is less than the lower limit value a is mainly to suppress a decrease in heat exchange efficiency in the preheater 12 and a water hammer in the evaporator 10. It is to suppress the occurrence of the phenomenon. Specifically, when the degree of supercooling α2 is less than the lower limit value a, the heating medium may be in a gas-liquid two-phase state, for example. In this case, when the heating medium flows into the preheater 12, pressure loss occurs in the preheater 12, so that the heating medium is difficult to pass through the preheater 12. For this reason, the heat exchange efficiency in the preheater 12 falls. Furthermore, the pressure loss is the cause (resistance), and the liquid heating medium (drain) is less likely to flow out of the evaporator 10. Therefore, the heat exchange efficiency in the preheater 12 is reduced by maintaining the bypass state when the degree of supercooling α2 is less than the lower limit value a, that is, prohibiting the flow of the heating medium into the preheater 12. Further, a state in which the liquid phase heating medium (drain) hardly flows out from the evaporator 10 due to the pressure loss is avoided (the outflow of the liquid phase heating medium is promoted). The occurrence of the water hammer phenomenon in the evaporator 10 is suppressed.

  At this time, since heat recovery by the working medium in the preheater 12 is not performed, the working medium having a lower temperature flows out of the preheater 12 and flows into the evaporator 10 as compared with the case where the heating medium flows into the preheater 12. To do. Thereby, the heating medium is sufficiently cooled by the working medium in the evaporator 10. And since the inflow of the heating medium to the preheater 12 is prohibited until the degree of supercooling α2 of the heating medium flowing out of the evaporator 10 becomes the lower limit value a or more, the heat exchange efficiency in the evaporator 10 is low. This situation is avoided.

  When the degree of supercooling α2 is not less than the lower limit value a and not more than the upper limit value b (YES in step S12), the control unit 40 has the degree of supercooling β of the working medium flowing into the evaporator 10 greater than 0 degrees. Whether or not (step S13). As a result, when the degree of supercooling β is not greater than 0 degrees (NO in step S13), the control unit 40 returns to step S12 again, that is, maintains the bypass state.

  The reason for maintaining the bypass state when the degree of supercooling β is not greater than 0 degrees is to improve the heat exchange efficiency in the evaporator 10, that is, the energy recovery efficiency of the energy recovery unit 20. For example, when a gas-liquid two-phase working medium flows into the evaporator 10, the specific gravity of the gas-phase working medium and the specific gravity of the liquid-phase working medium are different from each other. A region where a gas phase working medium passes and a region where a liquid phase working medium passes are formed. For this reason, there is a concern that the evaporator 10 may not perform uniform heat exchange between the working medium and the heating medium (decrease in heat exchange efficiency). Therefore, when the degree of supercooling β is not greater than 0 degrees (when a gas phase working medium may be present), the bypass state is maintained, that is, the flow of the heating medium into the preheater 12 is prohibited. Thereby, since heating of the working medium by the heating medium in the preheater 12 is stopped, the working medium flowing out from the preheater 12 is suppressed from being included in the gas phase working medium. Therefore, the drift of the working medium in the evaporator 10 is suppressed, and the heat exchange efficiency in the evaporator 10 is improved.

  When the degree of supercooling β is greater than 0 degrees (YES in step S13), the control unit 40 closes the first on-off valve V1, opens the second on-off valve V2, and the third on-off valve V3, The fourth on-off valve V4 and the fifth on-off valve V5 are closed, and the sixth on-off valve V6 is opened (step S14). As a result, the heating medium passes through the evaporator 10 and then passes through the preheater 12 before being discharged to the outside. That is, this thermal energy recovery device is in a normal operation state.

  Subsequently, the control unit 40 determines whether or not the degree of supercooling α1 of the heating medium flowing into the preheater 12 is greater than 0 degrees (step S15). As a result, when the degree of supercooling α1 is not greater than 0 degrees (NO in step S15), the control unit 40 returns to step S11 and returns to the bypass state.

  The reason for setting the bypass state when the degree of supercooling α1 is not greater than 0 degrees is to suppress the occurrence of the water hammer phenomenon in the preheater 12. Specifically, when the degree of supercooling α1 is not greater than 0 degrees (when a gas phase heating medium may exist), when the heating medium flows into the preheater 12, the gas phase heating medium flows into the preheater 12. After that, the water hammer phenomenon may occur due to condensation in the preheater 12. Therefore, when the degree of supercooling α1 is not greater than 0 degrees, the bypass state is maintained, that is, the flow of the heating medium into the preheater 12 is prohibited. Thereby, generation | occurrence | production of the water hammer phenomenon in the preheater 12 is suppressed.

  On the other hand, when the degree of supercooling α1 is greater than 0 degrees (YES in step S15), the control unit 40 determines whether or not the degree of supercooling α2 is greater than or equal to the lower limit value a and less than or equal to the upper limit value b (step S16). ). As a result, when the degree of supercooling α2 is less than the lower limit value a or larger than the upper limit value b (NO in step S16), the control unit 40 returns to step S11 and returns to the bypass state. The reason for this is as described above. Further, when the degree of supercooling α2 is less than the lower limit value a, returning to the bypass state avoids a state in which the heat exchange efficiency in the evaporator 10 becomes low, and in addition, the current state of the water hammer in the preheater 12 Is also suppressed.

  When the degree of supercooling α2 is not less than the lower limit value a and not more than the upper limit value b (YES in step S16), the control unit 40 has a degree of supercooling β of the working medium flowing into the evaporator 10 greater than 0 degrees. Whether or not (step S17). As a result, when the degree of supercooling β is not greater than 0 degrees (NO in step S17), the control unit 40 returns to step S11 and returns to the bypass state. The reason for this is as described above.

  On the other hand, when the degree of supercooling β is greater than 0 degrees (YES in step S17), the control unit 40 returns to step S15, that is, continues the normal operation state.

  Next, specific control contents of the control unit 40 at the time of stop will be described with reference to FIG.

  When receiving the stop signal (step S20), the control unit 40 stops the supply of the heating medium to the evaporator 10 and the preheater 12 and sets the first on-off valve V1 in the open state in order to make the bypass state. The second on-off valve V2 and the third on-off valve V3 are closed, the fourth on-off valve V4 and the fifth on-off valve V5 are closed, and the sixth on-off valve V6 is closed (step S21).

  Thereafter, the control unit 40 stops the pump 26 (step S22). Note that the supply of the cooling medium to the condenser 24 is also stopped simultaneously with or before or after the pump 26 is stopped.

  Subsequently, the control unit 40 determines whether or not the pressure P of the gas phase heating medium flowing into the evaporator 10 is less than a predetermined value P0 (step S23). In the present embodiment, this condition is referred to as a “stop condition”.

  If the pressure P is equal to or higher than the predetermined value P0 (NO in step S23), that is, if the stop condition is not satisfied, the control unit 40 returns to step S23.

  On the other hand, if the pressure P is less than the predetermined value P0 (YES in step S23), the control unit 40 opens the first on-off valve V1, closes the second on-off valve V2, and the third on-off valve V3, The fourth on-off valve V4 and the fifth on-off valve V5 are opened, and the sixth on-off valve V6 is closed (step S24). The reason for this is to promote the discharge of the heating medium in the heating medium flow path 10b of the evaporator 10 to the outside. Specifically, since the inside of the heating medium supply channel 30 is opened to the outside by opening the fourth on-off valve V4 and the fifth on-off valve V5, the heating in the heating medium channel 10b of the evaporator 10 is heated. The medium is discharged to the outside by gravity.

  As described above, in the present thermal energy recovery device, the heat energy obtained by the working medium in the evaporator 10 and the preheater 12 is recovered by the energy recovery unit 20 while the water hammer phenomenon occurs in the preheater 12. Can be suppressed. Specifically, when the degree of supercooling α1 of the heating medium flowing into the preheater 12 is not greater than 0 degrees (when a gas phase heating medium may exist), the heating medium is prohibited from flowing into the preheater 12. When the degree of supercooling α1 is greater than 0 degrees, the heating medium is allowed to flow into the preheater 12. That is, a liquid phase heating medium flows into the preheater 12. Therefore, the occurrence of the water hammer phenomenon in the preheater 12 is suppressed. More specifically, the occurrence of a water hammer phenomenon caused by condensation of the gas phase heating medium in the preheater 12 after flowing into the preheater 12 is suppressed.

  Moreover, in this embodiment, since all the latent heat of a heating medium is collect | recovered by the working medium in the evaporator 10, the heat exchange efficiency in the evaporator 10, ie, the energy recovery efficiency of the energy recovery part 20, improves. Specifically, in this energy recovery apparatus, when the degree of supercooling α2 of the heating medium flowing out from the evaporator 10 is less than the lower limit value a, the heating medium is prohibited from flowing into the preheater 12. As a result, heat recovery by the working medium in the preheater 12 is not performed, so that a lower temperature working medium flows out of the preheater 12 and flows into the evaporator 10 as compared with the case where the heating medium flows into the preheater 12. . For this reason, the heating medium is sufficiently cooled by the working medium in the evaporator 10. Then, since the inflow of the heating medium into the preheater 12 is prohibited until the degree of supercooling α2 of the heating medium flowing out from the evaporator 10 becomes the lower limit value a or more, the occurrence of the water hammer phenomenon in the preheater 12 occurs. Both the suppression of the temperature and the state where the heat exchange efficiency in the evaporator 10 is reduced are avoided. Furthermore, a state in which the liquid phase heating medium (drain) does not easily flow out of the evaporator 10 due to pressure loss when the heating medium passes through the preheater 12 is avoided. The occurrence of the hammer phenomenon is also suppressed.

  In addition, in this embodiment, since the outflow of the liquid phase heating medium (drain) from the evaporator 10 is promoted at the time of starting and normal operation of the thermal energy recovery device, the water hammer phenomenon in the evaporator 10 is promoted. Is further suppressed. Specifically, in the present energy recovery apparatus, when the degree of supercooling α2 of the heating medium flowing out from the evaporator 10 is larger than the upper limit b (not only the latent heat of the heating medium but also the sensible heat by the working medium in the evaporator 10) The heating medium is discharged outside without flowing into the preheater 12. As a result, the time required for the liquid-phase heating medium to be discharged from the evaporator 10 to the outside is shortened, so that the drain outflow from the evaporator 10 is promoted. Therefore, the occurrence of the water hammer phenomenon in the evaporator 10 during startup and normal operation is suppressed.

  Furthermore, in the present embodiment, an operation that promotes the outflow of the liquid heating medium from the evaporator 10 when the thermal energy recovery apparatus is stopped (an operation that discharges the heating medium to the outside without flowing into the preheater 12). ) Is performed, the occurrence of the water hammer phenomenon in the evaporator 10 at the start-up of the apparatus is further suppressed.

  Moreover, in this embodiment, since the drift of the working medium in the evaporator 10 is suppressed, the heat exchange efficiency in the evaporator 10 is further improved. Specifically, in the present energy recovery apparatus, when the degree of supercooling β of the working medium flowing into the evaporator 10 is not larger than 0 degree (when there can be a gaseous working medium), the heating medium preheater 12 is prohibited, that is, heating of the working medium by the heating medium in the preheater 12 is stopped, so that the working medium flowing out of the preheater 12 is prevented from containing a gas phase working medium. Is done. Therefore, the drift of the working medium in the evaporator 10 is suppressed, and the heat exchange efficiency in the evaporator 10 is improved.

  Moreover, since the connection flow path 29 has a shape extending in a straight line, the pressure loss generated in the connection flow path 29 is reduced. For this reason, the retention in the connection flow path 29 of the oil contained in the working medium is suppressed. Accordingly, an appropriate amount of oil flows into the expander 22 of the energy recovery unit 20.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, when the degree of supercooling α2 of the heating medium flowing out of the evaporator 10 is larger than the upper limit value b, the control unit 40 may open the fourth on-off valve V4. In this case, the liquid-phase heating medium passes through the first discharge flow path 38 as compared with the case where the liquid-phase heating medium passes through the steam trap 34 and is discharged to the outside via the bypass flow path 36. More smoothly discharged to the outside. Accordingly, since the discharge of the liquid heating medium (drain) from the heating medium flow path 10b of the evaporator 10 is promoted, the occurrence of the water hammer phenomenon in the evaporator 10 is further suppressed.

DESCRIPTION OF SYMBOLS 10 Evaporator 12 Preheater 20 Energy recovery part 29 Connection flow path 30 Heating medium supply flow path 32 Drain tank 34 Steam trap 36 Bypass flow path 38 1st discharge flow path 39 2nd discharge flow path 40 Control part V1 1st on-off valve V2 2nd on-off valve V3 3rd on-off valve V4 4th on-off valve V5 5th on-off valve V6 6th on-off valve

Claims (6)

An evaporator for evaporating the working medium by exchanging heat between the heating medium and the working medium in a gas phase supplied from the outside;
A preheater that heats the working medium by exchanging heat between the heating medium flowing out of the evaporator and the working medium before flowing into the evaporator;
An energy recovery unit that recovers expansion energy of the working medium flowing out of the evaporator and sends the working medium to the preheater;
When the degree of supercooling of the heating medium flowing into the preheater is not greater than 0 degrees, the heating medium is prohibited from flowing into the preheater, and the degree of supercooling of the heating medium flowing into the preheater is A heat energy recovery apparatus comprising: a control unit that performs an operation of causing the heating medium to flow into the preheater when the temperature is greater than 0 degrees. The thermal energy recovery device according to claim 1,
The control unit is configured such that when the degree of supercooling of the heating medium flowing into the preheater is greater than 0 degrees and the degree of supercooling of the heating medium flowing out of the evaporator is equal to or greater than a specific lower limit value, To the preheater, while the degree of supercooling of the heating medium flowing into the preheater is not greater than 0 degrees, or the heat that has flowed out of the evaporator even if the degree of supercooling is greater than 0 degrees. A thermal energy recovery apparatus that performs an operation of prohibiting the flow of a heating medium into the preheater when the degree of supercooling of the medium is less than the lower limit. In the thermal energy recovery device according to claim 1 or 2,
When the degree of supercooling of the heating medium flowing into the preheater is greater than 0 degrees and the degree of supercooling of the heating medium flowing out of the evaporator is equal to or less than a specific upper limit value, the control unit To the preheater, while the degree of supercooling of the heating medium flowing into the preheater is not greater than 0 degrees, or even if the degree of supercooling is greater than 0 degrees, the heating that has flowed out of the evaporator A thermal energy recovery device that performs an operation of discharging the heating medium to the outside without flowing into the preheater when the degree of supercooling of the medium is larger than the upper limit value. In the thermal energy recovery device according to any one of claims 1 to 3,
The controller controls the heating medium when the degree of supercooling of the heating medium flowing into the preheater is greater than 0 degrees and the degree of supercooling of the working medium flowing into the evaporator is greater than 0 degrees. While flowing into the preheater, the degree of supercooling of the heating medium flowing into the preheater is not greater than 0 degrees, or even if the degree of supercooling is greater than 0 degrees, the working medium flowing into the evaporator A thermal energy recovery apparatus that performs an operation of prohibiting the flow of a heating medium into the preheater when the degree of supercooling is not greater than 0 degrees. In the thermal energy recovery device according to any one of claims 1 to 4,
The said control part is a thermal energy recovery apparatus which performs operation which discharges | emits a heating medium outside, without flowing in into the said preheater, when predetermined stop conditions are satisfied. In the thermal energy recovery device according to any one of claims 1 to 5,
It further comprises a connection flow path connecting the preheater and the evaporator,
The said connection flow path is a thermal energy recovery apparatus which has a shape extended on a straight line.

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