JP2018127897A - Thermal energy recovery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal energy recovery system capable of suppressing occurrence of insufficient lubrication of a bearing during operation of an expander.SOLUTION: A thermal energy recovery system includes: an evaporator (10); an expander (20); a power recovery machine (30); a condenser (40); a pump (50); a circulation flow passage (60); a cooling flow passage (70) for supplying a part of a liquid-phase working medium flowing out from the pump (50) to the power recovery machine (30); an on-off valve (V1) provided in the cooling flow passage (70); and a control section (80). The expander (20) includes a rotor (21), a bearing (22) and a main casing (23). The power recovery machine (30) includes a power recovery section (31) and an auxiliary casing (35). The control section (80) closes the on-off valve (V1) when receiving a stop signal for stopping recovery of power in the power recovery machine (30).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermal energy recovery device.

  2. Description of the Related Art Conventionally, a thermal energy recovery device that recovers power from exhaust heat of various facilities such as factories is known. For example, Patent Document 1 includes an evaporator, a sealed generator, a condenser, a fluid supply pump, a circulation channel that connects the evaporator, the sealed generator, the condenser, and the fluid supply pump in this order. A power generation system (thermal energy recovery device) including a cooling pipe is disclosed. The evaporator evaporates the working medium. The hermetic generator extracts electric power from the expansion energy of the working medium flowing out of the evaporator. Specifically, the sealed generator includes a screw turbine that expands a working medium, a generator connected to the screw turbine via an output shaft, and a storage container that houses the screw turbine, the output shaft, and the generator. Have. The condenser condenses the working medium flowing out from the hermetic generator. The fluid supply pump delivers the working medium flowing out of the condenser to the evaporator. The cooling pipe connects the part of the circulation channel downstream of the fluid supply pump and the storage container so that a part of the liquid-phase working medium discharged from the fluid supply pump is supplied into the storage container. doing.

  In this thermal energy recovery device, a part of the liquid-phase working medium discharged from the fluid supply pump during operation of the device is supplied into the storage container through the cooling pipe. Effectively cooled.

JP 2012-97725 A

  In the thermal energy recovery apparatus as described in Patent Document 1, there is a concern that the lubrication of the bearings of the screw turbine is insufficient when the apparatus is restarted after being stopped. Specifically, when the operation of the thermal energy recovery device enters a stop operation, the rotational speed of the pump starts to decrease. In this state, if the liquid-phase working medium continues to be supplied into the expander through the cooling pipe, for example, the liquid-phase working medium present in the evaporator expands after being evaporated by receiving heat from the heating medium. The working medium that has flowed into the machine is condensed by being cooled by the liquid-phase working medium supplied through the cooling pipe, whereby the liquid-phase working medium may accumulate in the expander. When the screw turbine bearing is immersed in the liquid phase working medium due to the accumulation of the liquid phase working medium, there is a concern that the bearing may be insufficiently lubricated when the apparatus is restarted (when the screw turbine is driven). is there.

  An object of the present invention is to provide a thermal energy recovery device capable of suppressing the occurrence of insufficient lubrication of a bearing during driving of an expander.

  In order to achieve the above object, the present invention provides an evaporator that evaporates the working medium by exchanging heat between the heating medium and the working medium, an expander that expands the working medium flowing out of the evaporator, A power recovery machine connected to the expander, a condenser for condensing the working medium flowing out from the expander, a pump for sending the working medium flowing out from the condenser to the evaporator, the evaporator, and the expander A circulation passage for connecting the condenser and the pump in this order, a cooling passage for supplying a part of the liquid-phase working medium flowing out from the pump to the power recovery machine, and the cooling passage. The expander includes a rotor that is rotationally driven by the expansion energy of the working medium, a bearing that receives the rotor so that the rotor can rotate, the rotor and A main casing for housing a bearing, and the power recovery machine is connected to the rotor and recovers power by rotating together with the rotor; A thermal energy recovery device that closes the on-off valve when the control unit receives a stop signal for stopping recovery of power in the power recovery machine. I will provide a.

  In this thermal energy recovery apparatus, when the control unit receives a stop signal for stopping the recovery of power in the power recovery machine (when the necessity for cooling of the power recovery unit becomes low), the on-off valve provided in the cooling flow path Therefore, accumulation of the liquid-phase working medium in the sub casing and the main casing is suppressed. Therefore, it is suppressed that the bearing of the expander is immersed in the liquid-phase working medium, thereby suppressing the occurrence of insufficient lubrication of the bearing when the thermal energy recovery device is restarted.

  In this case, the sub-casing may have an introduction portion that can be connected to the cooling flow path and can introduce a liquid-phase working medium supplied from the cooling flow path into the sub-casing.

  In this aspect, the power recovery unit is effectively cooled by the liquid-phase working medium supplied from the cooling flow path into the sub casing.

  Alternatively, the power recovery machine further includes a jacket that is provided in the sub casing and forms a cooling space that allows a liquid-phase working medium to flow between the jacket and the sub casing. The jacket may have an introduction portion that can be connected to the cooling flow path and can introduce a liquid-phase working medium supplied from the cooling flow path into the cooling space.

  In this aspect, the power recovery unit is effectively cooled via the sub casing by the liquid-phase working medium supplied from the cooling flow path to the cooling space.

  In addition, the present invention is connected to the evaporator that evaporates the working medium by exchanging heat between the heating medium and the working medium, the expander that expands the working medium that has flowed out of the evaporator, and the expander. A power recovery machine, a condenser for condensing the working medium flowing out from the expander, a pump for sending the working medium flowing out from the condenser to the evaporator, the evaporator, the expander, the condenser, and the A circulation flow path connecting the pumps in this order, a cooling flow path for cooling the power recovery machine by supplying a cooling medium different from the working medium to the power recovery machine, and an opening / closing provided in the cooling flow path A valve, a control unit, and the expander includes a rotor that is rotationally driven by the expansion energy of the working medium, a bearing that receives the rotor so that the rotor can rotate, And a main casing that accommodates the bearing, and the power recovery machine is connected to the rotor and recovers power by rotating together with the rotor, and houses the power recovery part. A sub-casing having a shape communicating with the inside of the main casing, and the control unit closes the on-off valve when receiving a stop signal for stopping the recovery of power in the power recovery machine. Providing the device.

  Also in this thermal energy recovery device, the occurrence of insufficient lubrication of the expander bearing when the device is driven (at the start of operation) is suppressed.

  The thermal energy recovery device preferably further includes a liquid drainage channel that returns the liquid-phase working medium in the main casing or the sub-casing to the downstream side of the expander and the upstream side of the pump. .

  By doing so, the liquid-phase working medium in the main casing or the sub-casing is effectively discharged from the main casing or the sub-casing through the liquid drainage channel, so that the bearing is immersed in the liquid-phase working medium. Is more reliably suppressed.

  In this case, a liquid drain valve provided in the liquid drain flow path, a bypass flow path that bypasses the expander, a bypass valve provided in the bypass flow path, and the circulation flow among the circulation flow paths. A shutoff valve provided at a site between the passage and the upstream end of the bypass flow path, and the expander, and the control unit is a power recovery machine When receiving a stop signal for stopping the recovery of power, the pump reduces the rotational speed of the pump, closes the shut-off valve and opens the bypass valve, and closes the open / close valve. It is preferable to open the liquid drain valve after stopping.

  In this way, the liquid-phase working medium in the main casing or sub-casing is effectively discharged from the casing, and the inflow of the working medium into the main casing until the pump stops is suppressed. Is done. Specifically, when the drain valve is opened before the pump stops, the working medium that has been discharged from the pump and reaches the downstream side of the expander via the bypass flow path is circulated from the downstream side of the expander. By flowing backward in the path, there is a risk of flowing into the main casing of the expander and liquefying in the main casing. On the other hand, in this thermal energy recovery device, the control unit opens the drain valve after the pump is stopped, so that the occurrence of the above-described problems is suppressed.

  As described above, according to the present invention, it is possible to provide a thermal energy recovery device capable of suppressing the occurrence of insufficient lubrication of a bearing during driving of an expander.

It is a figure showing roughly the composition of the thermal energy recovery device of a 1st embodiment of the present invention. It is a flowchart which shows the control content of a control part. It is a figure which shows schematically the structure of the thermal energy recovery apparatus of 2nd Embodiment of this invention. It is a figure which shows schematically the structure of the thermal energy recovery apparatus of 3rd Embodiment of this invention.

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

(First embodiment)
FIG. 1 shows the configuration of the thermal energy recovery apparatus according to the first embodiment of the present invention. This thermal energy recovery device connects the evaporator 10, the expander 20, the power recovery machine 30, the condenser 40, the pump 50, the evaporator 10, the expander 20, the condenser 40, and the pump 50 in this order. The circulation channel 60, the cooling channel 70, and the control unit 80 are provided.

  The evaporator 10 evaporates the working medium by exchanging heat between the working medium and the heating medium.

  The expander 20 is provided in a portion of the circulation channel 60 on the downstream side of the evaporator 10. The expander 20 expands the gas phase working medium flowing out of the evaporator 10. In this embodiment, a positive displacement screw expander having a rotor that is rotationally driven by the expansion energy of a gas phase working medium is used as the expander 20. Specifically, the expander 20 includes a pair of male and female screw rotors (rotors) 21 that are rotationally driven by the expansion energy of the working medium, a bearing 22 that receives the screw rotor 21 so that the screw rotor 21 can be rotated, and a pair. And a main casing 23 that collectively accommodates the screw rotor 21 and the bearing 22. The main casing 23 includes a suction port 23a for sucking the working medium flowing out from the evaporator 10, and a discharge port 23b for discharging the working medium after expansion (after the pair of screw rotors 21 are driven to rotate) to the circulation channel 60. ,have. In the present embodiment, the main casing 23 is installed with the discharge port 23b facing horizontally. The bearing 22 is held by the main casing 23.

  The power recovery machine 30 is connected to the expander 20. Specifically, the power recovery machine 30 includes a power recovery unit 31 and a sub casing 35.

  The power recovery machine 30 is connected to one screw rotor 21 of the pair of screw rotors 21 and recovers power by rotating together with the screw rotor 21. In the present embodiment, a power generator is used as the power recovery machine 30. That is, the power recovery unit 31 includes a rotating shaft 32 connected to one screw rotor 21 of the pair of screw rotors 21, a rotor 33 fixed to the rotating shaft 32, and a stator 34 disposed around the rotor 33. Have. Note that a compressor or the like may be used as the power recovery machine 30.

  The sub casing 35 accommodates the power recovery unit 31. The sub casing 35 is fixed to the main casing 23. The inside of the sub casing 35 communicates with the inside of the main casing 23. For this reason, a part of the working medium expanded in the main casing 23 reaches the sub casing 35.

  The condenser 40 is provided in a portion of the circulation channel 60 on the downstream side of the expander 20. The condenser 40 condenses the working medium by exchanging heat between the working medium flowing out from the expander 20 and a cooling medium (cooling water or the like).

  In the present embodiment, a storage part (receiver) 45 that stores a liquid-phase working medium is provided in a portion of the circulation channel 60 on the downstream side of the condenser 40. However, the storage unit 45 may be configured by a part of the circulation channel 60 or may be omitted.

  The pump 50 is provided at a site downstream of the condenser 40 in the circulation channel 60 (a site between the condenser 40 and the evaporator 10). The pump 50 sends the liquid-phase working medium flowing out of the condenser 40 to the evaporator 10 at a predetermined pressure.

  The cooling flow path 70 supplies a part of the liquid-phase working medium that has flowed out of the pump 50 to the power recovery machine 30. In the present embodiment, the cooling flow path 70 connects a portion of the circulation flow path 60 between the pump 50 and the evaporator 10 and the sub casing 35. Specifically, the sub casing 35 has an introduction portion 35a capable of introducing a liquid-phase working medium into the sub casing 35, and the downstream end of the cooling flow path 70 is connected to the introduction portion 35a. Has been. For this reason, a part of the liquid-phase working medium discharged from the pump 50 is supplied into the auxiliary casing 35 via the cooling flow path 70. Thereby, the power recovery unit 31 is effectively cooled.

  The thermal energy recovery device of this embodiment further includes a liquid drainage channel 71. The liquid drainage flow channel 71 is a region where the liquid-phase working medium R in the main casing 23 or the sub-casing 35 exists on the downstream side of the expander 20 and the upstream side of the pump 50, that is, the working medium exists in the liquid phase. Return to. Specifically, the liquid drainage channel 71 connects the lead-out part 23 c formed in the main casing 23 and a part of the circulation channel 60 between the storage part 45 and the pump 50. The lead-out portion 23 c is provided on the bottom portion 25 located on the lowermost side of the main casing 23. Note that the downstream end of the liquid drainage channel 71 may be connected to a portion of the circulation channel 60 between the expander 20 and the condenser 40, the condenser 40, or the storage unit 45. .

  The thermal energy recovery device of the present embodiment includes a bypass flow path 62 that bypasses the expander 20, an on-off valve V1 provided in the cooling flow path 70, a shutoff valve V2 provided in the circulation flow path 60, and a bypass flow. A bypass valve V3 provided in the passage 62 and a liquid drain valve V4 provided in the liquid drain passage 71 are further provided. Each valve V1-V4 is comprised so that opening and closing is possible.

  An upstream end of the bypass flow path 62 is connected to a portion of the circulation flow path 60 between the evaporator 10 and the expander 20. The downstream end of the bypass channel 62 is connected to a portion of the circulation channel 60 between the expander 20 and the condenser 40.

  The shutoff valve V <b> 2 is provided in a portion between the expansion channel 20 and the connection between the circulation channel 60 and the upstream end of the bypass channel 62 in the circulation channel 60.

  The control unit 80 collects power in the power recovery machine 30 during recovery of power (electric power in this embodiment) in the power recovery machine 30 (while the expander 20, the power recovery machine 30, and the pump 50 are being driven). When the stop signal to be stopped is received, the cooling of the power recovery unit 31, that is, the supply to the power recovery machine 30 through a part of the cooling flow path 70 of the liquid phase working medium discharged from the pump 50 is stopped. Hereinafter, the control content of the control unit 80 will be described with reference to FIG. During the operation of this apparatus, the on-off valve V1 and the shutoff valve V2 are opened, and the bypass valve V3 and the liquid drain valve V4 are closed.

  When the control unit 80 receives the stop signal, the controller 80 decreases the rotational speeds of the pump 50, the expander 20, and the power recovery machine 30, closes the shutoff valve V2, and opens the bypass valve V3 (step S11). Thereby, the gas phase working medium flowing out of the evaporator 10 is directed to the condenser 40 via the bypass flow path 62 (bypassing the expander 20).

  Since the necessity for cooling of the power recovery unit 31 is reduced due to the decrease in the rotation speed of the expander 20 and the power recovery unit 30, the control unit 80 closes the on-off valve V1 (step S12). As a result, the supply of the liquid-phase working medium into the sub casing 35 through the cooling channel 70 is stopped. Therefore, the power recovery unit 31 is excessively cooled, in other words, accumulation of the liquid-phase working medium R in the sub casing 35 and the main casing 23 is suppressed.

  Thereafter, the controller 80 opens the liquid drain valve V4 after the pump 50 is stopped (step S13). As a result, the liquid-phase working medium R in the main casing 23 or the sub-casing 35 is effectively discharged from the casings 23 and 35.

  As described above, in the present thermal energy recovery apparatus, when the control unit 80 receives the stop signal (when the necessity of cooling the power recovery unit 31 becomes low), the control unit 80 of the liquid-phase working medium discharged from the pump 50 Supply to the power recovery machine 30 through some cooling flow paths 70 is stopped. Specifically, when receiving the stop signal, the controller 80 closes the on-off valve V1 provided in the cooling flow path 70. For this reason, accumulation of the liquid-phase working medium in the sub casing 35 and the main casing 23 is suppressed. Therefore, it is suppressed that the bearing 22 of the expander 20 is immersed in the liquid-phase working medium R, thereby suppressing the occurrence of insufficient lubrication of the bearing 22 when the thermal energy recovery device is restarted.

  In step S13, the control unit 80 opens the liquid drain valve V4 after the pump 50 is stopped, so that the liquid-phase working medium R in the main casing 23 or the sub-casing 35 is effective from the casings 23 and 35. Further, the inflow of the working medium into the main casing 23 until the pump 50 is stopped is suppressed. Specifically, when the drain valve V4 is opened before the pump 50 is stopped, the working medium that has been discharged from the pump 50 and then reaches the downstream side of the expander 20 via the bypass flow path 62 becomes the expander 20. By flowing backward through the circulation flow path 60 from the downstream side, the air flows into the main casing 23 of the expander 20 and may be liquefied in the main casing 23. On the other hand, in this embodiment, since the control part 80 opens the drain valve V4 after the pump 50 stops, generation | occurrence | production of the above malfunctions is suppressed.

(Second Embodiment)
Next, a thermal energy recovery device according to a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, only parts different from the first embodiment will be described, and the description of the same structure, operation, and effect as in the first embodiment will be omitted.

  In the present embodiment, the power recovery machine 30 has a jacket 36, and the downstream end of the cooling flow path 70 is connected to the jacket 36.

  The jacket 36 is provided in the sub casing 35 so as to form a cooling space S that allows the liquid-phase working medium to flow between the jacket 36 and the sub casing 35. The jacket 36 is disposed outside the outer peripheral surface of the sub casing 35. That is, the cooling space S is formed between the outer peripheral surface of the sub casing 35 and the inner peripheral surface of the jacket 36. The jacket 36 has an introduction portion 36 a that can be connected to the downstream end of the cooling flow path 70 and can introduce the liquid-phase working medium supplied from the cooling flow path 70 into the cooling space S. .

  In addition, the cooling medium that has cooled the power recovery unit 31 through the sub casing 35 by passing through the cooling space S flows into the circulation channel 60 through the discharge channel 72. An upstream end portion of the discharge flow path 72 is connected to a discharge portion 36 b formed in the jacket 36, and a downstream end portion of the discharge flow path 72 is condensed with the expander 20 in the circulation flow path 60. It is connected to the part between the container 40.

  As described above, also in the present embodiment, the bearing 22 of the expander 20 is suppressed from being immersed in the liquid-phase working medium R, thereby causing insufficient lubrication of the bearing 22 when the thermal energy recovery device is restarted. Is suppressed.

(Third embodiment)
Next, a thermal energy recovery device according to a third embodiment of the present invention will be described with reference to FIG. In the third embodiment, only parts different from the first embodiment will be described, and the description of the same structure, operation, and effect as in the first embodiment will be omitted.

  In the present embodiment, the power recovery machine 30 has the jacket 36 in common with the second embodiment, but a cooling medium (cooling water or the like) different from the working medium is supplied to the cooling space S. Is done.

  The jacket 36 is connected to a cooling flow path 73 branched from a cooling medium supply line L1 for supplying a cooling medium. For this reason, in this embodiment, the power recovery unit 31 is cooled via the sub casing 35 by the cooling medium passing through the cooling space S. The cooling medium that has passed through the cooling space S is returned to the cooling medium discharge line L <b> 2 that discharges the cooling medium through the cooling medium recovery passage 74 connected to the jacket 36.

  As described above, also in this embodiment, the same effects as those in the above embodiments can be obtained.

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

  For example, the sub casing 35 and the jacket 36 that form the cooling space S may be separate members, or may be members integrally formed by casting.

DESCRIPTION OF SYMBOLS 10 Evaporator 20 Expander 21 Rotor (screw rotor)
DESCRIPTION OF SYMBOLS 22 Bearing 23 Main casing 30 Power recovery machine 31 Power recovery part 35 Subcasing 36 Jacket 40 Condenser 50 Pump 60 Circulation flow path 62 Bypass flow path 70 Cooling flow path 71 Drain flow path 73 Cooling flow path 80 Control part S Cooling space V1 On-off valve V2 Shut-off valve V3 Bypass valve V4 Liquid drain valve

Claims (6)

An evaporator that evaporates the working medium by exchanging heat between the heating medium and the working medium;
An expander that expands the working medium flowing out of the evaporator;
A power recovery machine connected to the expander;
A condenser for condensing the working medium flowing out of the expander;
A pump for sending the working medium flowing out of the condenser to the evaporator;
A circulation flow path connecting the evaporator, the expander, the condenser and the pump in this order;
A cooling flow path for supplying a part of the liquid-phase working medium flowing out of the pump to the power recovery machine;
An on-off valve provided in the cooling flow path;
A control unit,
The expander is
A rotor that is rotationally driven by the expansion energy of the working medium;
A bearing for receiving the rotor such that the rotor is rotatable;
A main casing that houses the rotor and the bearing,
The power recovery machine is
A power recovery unit connected to the rotor and recovering power by rotating together with the rotor;
A secondary casing having a shape that accommodates the power recovery unit and communicates with the inside of the main casing;
The said control part is a thermal energy recovery apparatus which closes the said on-off valve, if the stop signal which stops the collection | recovery of the motive power in the said power recovery machine is received. The thermal energy recovery device according to claim 1,
The sub-casing is a thermal energy recovery device having an introduction part that can be connected to the cooling flow path and can introduce a liquid-phase working medium supplied from the cooling flow path into the sub-casing. The thermal energy recovery device according to claim 1,
The power recovery machine further includes a jacket provided in the sub casing and forming a cooling space that allows a liquid-phase working medium to flow between the jacket and the sub casing.
The thermal energy recovery apparatus, wherein the jacket has an introduction portion that can be connected to the cooling flow path and can introduce a liquid-phase working medium supplied from the cooling flow path into the cooling space. An evaporator that evaporates the working medium by exchanging heat between the heating medium and the working medium;
An expander that expands the working medium flowing out of the evaporator;
A power recovery machine connected to the expander;
A condenser for condensing the working medium flowing out of the expander;
A pump for sending the working medium flowing out of the condenser to the evaporator;
A circulation flow path connecting the evaporator, the expander, the condenser and the pump in this order;
A cooling flow path for cooling the power recovery machine by supplying a cooling medium different from the working medium to the power recovery machine;
An on-off valve provided in the cooling flow path;
A control unit,
The expander is
A rotor that is rotationally driven by the expansion energy of the working medium;
A bearing for receiving the rotor such that the rotor is rotatable;
A main casing that houses the rotor and the bearing,
The power recovery machine is
A power recovery unit connected to the rotor and recovering power by rotating together with the rotor;
A secondary casing having a shape that accommodates the power recovery unit and communicates with the inside of the main casing;
The said control part is a thermal energy recovery apparatus which closes the said on-off valve, if the stop signal which stops the collection | recovery of the motive power in the said power recovery machine is received. In the thermal energy recovery device according to any one of claims 1 to 4,
A thermal energy recovery device further comprising a liquid drainage passage for returning a liquid-phase working medium in the main casing or the sub-casing to the downstream side of the expander and the upstream side of the pump. In the thermal energy recovery device according to claim 5,
A liquid drain valve provided in the liquid drain passage;
A bypass flow path for bypassing the expander;
A bypass valve provided in the bypass channel;
Of the circulation flow path, further comprising a shutoff valve provided at a portion between the circulation flow path and the upstream end of the bypass flow path, and the expander,
When the control unit receives a stop signal for stopping the recovery of power in the power recovery machine, the control unit decreases the rotation speed of the pump, closes the shut-off valve and opens the bypass valve, A thermal energy recovery device that closes the valve and opens the drain valve after the pump stops.

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