Organic Rankine cycle system

Abstract

The utility model provides an organic Rankine cycle system which comprises a vortex expansion machine, the vortex expansion machine comprises a shell, an expansion mechanism, a main bearing seat used for supporting the expansion mechanism, a rotating shaft driven by the expansion mechanism and a motor connected with the rotating shaft, and a balance block is installed on the rotating shaft. The inner space enclosed by the shell is divided into a high-pressure area and a low-pressure area; the external fluid circulation path comprises a first fluid pipe, a second fluid pipe and a third fluid pipe capable of communicating fluid in the high-pressure area with fluid in the low-pressure area; and the control system is constructed to control the flow in the third fluid pipe according to the rotating speed of the motor, the control system comprises a proximity switch used for detecting the rotating speed of the motor, and the proximity switch is arranged in the vortex expansion machine and is arranged to enable the sensing surface of the proximity switch to be close to the balance block. According to the organic Rankine cycle system, faults caused by overspeed of the motor in the operation process can be avoided.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of organic rankine cycle system, more particularly, an organic rankine cycle system comprising a control system for monitoring the motor speed of an expander during system operation. BACKGROUND

[0002] The content of this section only provides background information related to the utility model, which may not constitute the prior art.

[0003] An organic rankine cycle system is a rankine cycle system using a low-boiling organic working fluid as the circulating working fluid instead of water, which mainly comprises an evaporator, an expander, a condenser, a working fluid pump and other main equipment. When the organic rankine cycle system is operating normally, the waste heat discharged from the production process heats the low-boiling organic working fluid into saturated steam or superheated steam in the evaporator. These high-pressure steam is sent to the expander to drive the expander to rotate and do work, thereby driving the generator to rotate to generate electric energy or driving other power machines to output mechanical energy. The low-temperature gas after expansion then enters the condenser, where it is cooled into a liquid. Subsequently, under the action of the working fluid pump, the liquid is sent to the evaporator to be heated and evaporated again, thereby completing the cycle of "heat absorption - work - condensation - pressure increase", and realizing the conversion of waste heat resources from low-grade heat sources to high-grade electric energy.

[0004] In the organic rankine cycle system, a common expander is a scroll expander. The operation of the scroll expander has a speed limit, and once it exceeds the rated speed, it will cause mechanical structure damage. In particular, when the external load, such as the grid load, fails during system operation, the motor rotor will rotate at high speed under the action of high-pressure gas, exceeding the rated speed of the bearing system, causing bearing system wear, and during rotation, it is easy to generate large reverse current and reverse voltage, leading to motor damage and even causing the whole machine to be unable to operate normally. This phenomenon is called "flywheel" phenomenon.

[0005] Therefore, the utility model aims to provide a protection device for monitoring the operating speed of the scroll expander, especially the rotational speed of the motor, so as to prevent the "flywheel" phenomenon during the operation of the organic rankine cycle and improve the reliability of the system. UTILITY MODEL CONTENT

[0006] An object of the utility model is to provide an organic rankine cycle system, which uses a proximity switch as a sensing device for detecting the rotational speed of the motor of the scroll expander. Not only can the rotational speed of the motor be effectively monitored during system operation to improve the reliability of the system, but also the sensing device itself has a simple structure and low cost.

[0007] The utility model discloses another purpose is to provide a kind of organic rankine cycle system, the organic rankine cycle system includes proximity switch installed in the main bearing seat of scroll expander, not only can effectively detect the motor speed of scroll expander, and need not be additionally set up structural member to install and fix proximity switch, to make the structure of system simple, space compact, facilitate installation.

[0008] Another purpose of the utility model is to provide a kind of organic rankine cycle system, the organic rankine cycle system includes scroll expander, external fluid circulation path and control system, the control system can be in the start-up phase of scroll expander, normal operation phase and in the motor overspeed operating condition of scroll expander respectively to each valve in external fluid circulation path different control operation, to ensure the reliability of system in each stage and operating condition.

[0009] According to an aspect of the utility model, provide a kind of organic rankine cycle system, including: scroll expander, scroll expander includes the casing of internal space being enclosed, internal space is divided into high-pressure area and low-pressure area, scroll expander further includes expansion mechanism, the main bearing seat for supporting expansion mechanism, the rotating shaft driven by expansion mechanism and the motor being connected with rotating shaft, balance weight is installed on rotating shaft;External fluid circulation path, external fluid circulation path includes the first fluid pipe being connected with the air inlet fitting of scroll expander, the second fluid pipe being connected with the exhaust fitting of scroll expander and the third fluid pipe capable of the high-pressure area and low-pressure area fluid communication;And control system, control system is configured to the flow in the third fluid pipe according to the speed of motor control, wherein, control system includes the proximity switch for detecting the speed of motor, proximity switch is arranged in scroll expander and is arranged so that the sensing surface of proximity switch is close to balance weight.

[0010] Optionally, the proximity switch is installed on the main bearing seat of the scroll expander.

[0011] Optionally, the main bearing seat includes a substantially cylindrical body portion defining a recess, the balance weight is arranged in the recess, the body portion is provided with a mounting hole capable of communicating the recess with the outside of the main bearing seat, the proximity switch is inserted in the mounting hole, so that the sensing surface of the proximity switch is located in the recess.

[0012] Optionally, the balance weight includes a mounting portion for mounting the balance weight to the rotating shaft and a counterweight portion located radially outward of the mounting portion, the proximity switch obtains the speed of the motor by detecting the number of times that the counterweight portion rotates past the sensing surface of the proximity switch per minute.

[0013] Optionally, the third fluid pipe is provided with a bypass valve, and the control system is configured to close the bypass valve when the proximity switch detects that the rotational speed of the motor does not exceed the predetermined threshold, and the control system is configured to open the bypass valve when the proximity switch detects that the rotational speed of the motor exceeds the predetermined threshold.

[0014] Optionally, the third fluid pipe has a first port and a second port opposite to each other, the first port is connected to and communicates with the first fluid pipe, and the second port is connected to and communicates with the second fluid pipe, the first fluid pipe is provided with a supply valve, the third fluid pipe is provided with a bypass valve, and the connection point of the first port and the first fluid pipe is located upstream of the supply valve.

[0015] Optionally, the control system further comprises a controller electrically connected with the proximity switch, the supply valve and the bypass valve.

[0016] Optionally, the control system is configured to completely open the supply valve and completely close the bypass valve when the proximity switch detects that the rotational speed of the motor does not exceed the predetermined threshold, and the control system is configured to completely close the supply valve and completely open the bypass valve or reduce the opening degree of the supply valve and increase the opening degree of the bypass valve when the proximity switch detects that the rotational speed of the motor exceeds the predetermined threshold.

[0017] Optionally, the control system is further configured to completely close the supply valve and completely open the bypass valve during the starting stage of the scroll expander.

[0018] Optionally, the control system is further configured to avoid completely closing the supply valve and the bypass valve at the same time and avoid completely opening the supply valve and the bypass valve at the same time during the operation of the scroll expander.

[0019] According to another aspect of the present application, an organic Rankine cycle system is provided, comprising: a scroll expander; an external fluid circulation path, the external fluid circulation path comprising a first fluid pipe connected with an air inlet fitting of the scroll expander, a second fluid pipe connected with an air outlet fitting of the scroll expander, and a third fluid pipe communicating with the first fluid pipe and the second fluid pipe, wherein the first fluid pipe is provided with a supply valve, and the third fluid pipe is provided with a bypass valve; and a control system, the control system comprising a sensing device arranged in the scroll expander for detecting the rotational speed of a motor of the scroll expander, wherein the control system is configured to: during the starting stage of the scroll expander, the control system closes the supply valve and opens the bypass valve to establish a predetermined pressure difference in the scroll expander; during the normal operation stage of the scroll expander, the control system opens the supply valve and closes the bypass valve; when the sensing device detects that the rotational speed of the motor of the scroll expander exceeds a predetermined threshold, the control system closes the supply valve and opens the bypass valve, or the control system controls the opening degree of the supply valve to decrease and controls the opening degree of the bypass valve to increase.

[0020] Optionally, the sensing device is configured as a proximity switch.

[0021] Optionally, the proximity switch is mounted on a main bearing seat of the scroll expander.

[0022] Optionally, the main bearing seat comprises a substantially cylindrical body portion defining a concave cavity in which a balance block connected with a rotating shaft of the scroll expander is arranged, and the proximity switch generates a signal each time the balance block approaches the proximity switch to detect the rotating speed of the motor.

[0023] Optionally, the control system further comprises a controller electrically connected with the sensing device, the supply valve and the bypass valve.

[0024] In general, the organic Rankine cycle system according to the present application can at least bring one of the following beneficial effects: the organic Rankine cycle system uses a proximity switch as a sensing device for detecting the rotating speed of the motor of the scroll expander, which not only improves the system operation reliability, but also simplifies the device structure and reduces the cost; the proximity switch can be directly mounted on the main bearing seat of the scroll expander without the need of additional mounting structural members, which not only makes the installation operation more convenient, but also simplifies the structure of the expander and saves space; in addition, the control system comprising the proximity switch can not only ensure that a normal pressure difference is established in the scroll expander before the scroll expander is started to realize the normal operation of the scroll expander and the organic Rankine cycle system, but also can avoid the damage or failure of the device caused by the overspeed of the motor during the operation of the scroll expander and the organic Rankine cycle system, thereby improving the reliability of the system. BRIEF DESCRIPTION OF DRAWINGS

[0025] The features and advantages of one or more embodiments of the present application will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings. The drawings provided herein are for illustrative purposes only and are not intended to limit the scope of the application in any way. The drawings are not drawn to scale and some features can be exaggerated to show details of particular components. In the drawings:

[0026] Figure 1 is a schematic view of an organic Rankine cycle system according to an embodiment of the present application;

[0027] Figure 2 is a longitudinal sectional view of a scroll expander according to an embodiment of the present application;

[0028] Figure 3 is a detail enlarged view according to part A in Figure 2 ; and

[0029] Figure 4 is a perspective schematic view of a main bearing seat and related parts in a scroll expander according to an embodiment of the present application. Detailed Implementation

[0030] The preferred embodiments of the present invention will now be described with reference to the accompanying drawings. This description is merely exemplary and does not constitute a limitation on the present invention or its applications.

[0031] Figure 1 An organic Rankine cycle system ES according to one embodiment of the present invention is shown. Figure 1 As shown, the organic Rankine cycle system ES mainly includes an expander (vortex expander) 100 and an external fluid circulation path L. The external fluid circulation path L includes a condenser 101, a working fluid pump 102, an evaporator 103, and a pipeline that sequentially connects the condenser 101, the working fluid pump 102, and the evaporator 103 and connects them to the vortex expander 100. Specifically, the external fluid circulation path L (the piping) includes: a first fluid pipe L1 connected to the inlet fitting 17 of the scroll expander 100, which supplies high-pressure fluid from the evaporator 103 to the scroll expander 100 via the inlet fitting 17; a supply valve V1 is provided on the first fluid pipe L1 to control the flow rate of the fluid supplied to the scroll expander 100; a second fluid pipe L2 connected to the exhaust fitting 18 of the scroll expander 100, which supplies low-pressure fluid discharged from the scroll expander 100 to the condenser 101; and a pumping line that supplies fluid from the condenser 101 to the evaporator 103 using a working fluid pump 102. Furthermore, the external fluid circulation path L also includes a high-pressure zone P1 of the scroll expander 100 (see...) Figure 2 ) and low-pressure area P2 (see Figure 2 A third fluid pipe L3 is connected to the first fluid pipe L1. In one embodiment of the present invention, the third fluid pipe L3 includes a first port L31 and a second port L32 opposite to each other. The first port L31 is connected to and communicates with the first fluid pipe L1, and the second port L32 is connected to and communicates with the second fluid pipe L2. Since the first fluid pipe L1 is connected to the high-pressure zone P1 of the scroll expander 100 via the intake fitting 17, and the second fluid pipe L2 is connected to the low-pressure zone P2 of the scroll expander 100 via the exhaust fitting 18, the first port L31 and the second port L32 of the third fluid pipe L3 are indirectly connected to the high-pressure zone P1 and the low-pressure zone P2 of the scroll expander 100, respectively. A bypass valve V2 is provided on the third fluid pipe L3 to control the fluid flow rate in the third fluid pipe L3.

[0032] Specifically, the connection point 171 between the third fluid pipe L3 and the first fluid pipe L1 is located upstream of the supply valve V1, and more specifically, between the evaporator 103 and the supply valve V1, to facilitate independent control of the flow rates in the first fluid pipe L1 and the third fluid pipe L3. In other words, the third fluid pipe L3 branches off from the first fluid pipe L1 between the supply valve V1 and the evaporator 103 and flows fluidly to the second fluid pipe L2.

[0033] Figure 2 A vortex expander 100 in an organic Rankine cycle system ES according to one embodiment of the present invention is shown. Figure 2 As shown, the scroll expander 100 includes a housing 10, an expansion mechanism 20 disposed within the internal space enclosed by the housing 10, a main shaft bearing housing 30 for supporting the expansion mechanism 20, a rotating shaft 40 driven by the expansion mechanism 20, and a motor 50 connected to the rotating shaft 40. The housing 10 may be composed of a generally cylindrical body portion 12, a top cover 14 disposed at one end of the body portion 12, and a bottom cover 18 disposed at the other end of the body portion 12. The housing 10 also includes a partition plate 16 disposed between the top cover 14 and the body portion 12 to divide the internal space of the scroll expander 100 enclosed by the housing 10 into a high-pressure zone P1 and a low-pressure zone P2, wherein the space between the partition plate 16 and the top cover 14 constitutes the high-pressure zone P1, and the space between the partition plate 16, the body portion 12, and the bottom cover constitutes the low-pressure zone P2. Sealing isolation between the high-pressure zone P1 and the low-pressure zone P2 can be achieved by a floating seal S disposed at the partition plate 16. An air intake fitting 17 connected to the first fluid pipe L1 (see...) Figure 1 A top cover 14 can be provided for introducing high-pressure fluid from outside the scroll expander 100 into the high-pressure zone P1. An exhaust fitting 18 connected to the second fluid pipe L2 (see...) Figure 1 It can be installed on the main body 12 for discharging the low-pressure fluid in the low-pressure zone P2 after it has been expanded by the expansion mechanism 20 from the vortex expander 100.

[0034] The expansion mechanism 20 includes a fixed scroll 22 and a moving scroll 24. The moving scroll 24 is capable of translational rotation relative to the fixed scroll 22 under the expansion action of the working fluid (i.e., the central axis of the moving scroll 24 revolves around the central axis of the fixed scroll 22, but the moving scroll 24 itself does not rotate around its own central axis). The fixed scroll 22 includes a fixed scroll end plate and helical fixed scroll blades formed on one side of the fixed scroll end plate. The moving scroll 24 may include a moving scroll end plate, helical moving scroll blades formed on a first side of the moving scroll end plate, and a hub 241 formed on a second side of the moving scroll end plate opposite to the first side. The fixed scroll blades and the moving scroll blades can mesh with each other to form a series of fluid cavities (e.g., a central intake cavity, an intermediate expansion cavity, and an exhaust cavity) with gradually increasing volume between the fixed scroll blades and the moving scroll blades.

[0035] The second side of the orbiting scroll end plate of the orbiting scroll 24 is supported by the main bearing housing 30. Specifically, as shown in Figure 2 、 Figure 3 and Figure 4 , the main bearing housing 30 includes a generally cylindrical or bowl-shaped body portion 32 and a thrust portion 34 above the body portion 32 for contacting the second side of the orbiting scroll end plate to form a thrust surface. The thrust portion 34 can be mounted on the body portion 32 or formed integrally with the body portion 32. The body portion 32 defines a concave cavity C. A through hole is formed in the bottom central portion of the body portion 32 for the rotating shaft 40 to pass through. A main bearing is provided in the through hole for supporting the rotating shaft 40. One end of the rotating shaft 40 is provided with an eccentric crank pin 42 which can pass through the through hole of the body portion 32 of the main bearing housing 30 and insert into the hub portion 241 of the orbiting scroll 24 through the concave cavity C. An unloading bushing is also provided between the eccentric crank pin 42 and the hub portion 241 of the orbiting scroll 24. The other end of the rotating shaft 40 opposite to the eccentric crank pin 42 is connected with the motor 50, in particular, the rotor 52 of the motor 50.

[0036] When the scroll expander 100 is in operation, high pressure fluid provided by the first fluid pipe L1 enters the high pressure zone P1 within the scroll expander 100 via the inlet fitting 17 and then enters the expansion mechanism 20 via the central inlet of the fixed scroll 22. The high pressure fluid entering the expansion mechanism 20 is expanded and becomes low pressure fluid as it flows through a series of fluid chambers with increasing volume. The low pressure fluid expanded by the expansion mechanism 20 is discharged to the low pressure zone P2 outside the expansion mechanism 20 and then discharged to the outside of the scroll expander 100 via the outlet fitting 18. The driving torque is generated during the expansion of the fluid by the expansion mechanism 20 to rotate the rotating shaft 40 and thus rotate the motor 50 (or the rotor 52 of the motor 50). In the present embodiment, the motor 50 is configured as a generator and can be electrically connected to the wiring fitting 60 provided on the main body portion 12 of the housing 10, which can be electrically connected to an external load. For example, the wiring fitting 60 can be electrically connected to an electrical grid to output electrical power. It is appreciated by those skilled in the art that in other embodiments, the scroll expander can directly output mechanical power.

[0037] During the operation of the scroll expander 100, the centrifugal force or centrifugal torque generated by the eccentric component (e.g. the eccentric crank pin) can cause vibration of the expander. Generally, a counterbalance mass can be provided on the rotating component (e.g. the rotating shaft) to provide a counterbalancing centrifugal force or centrifugal torque to balance the unbalance amount generated by the eccentric component. In the present embodiment, the counterbalance mass 80 is mounted on the rotating shaft 40, but it is appreciated by those skilled in the art that the counterbalance mass 80 can also be mounted on or formed integrally with the unloading bushing. AsFigure 3 and Figure 4 As shown, the balance block 80 includes a mounting portion 82 for mounting the balance block 80 to the rotating shaft 40 and a counterweight portion 84 disposed radially outside the mounting portion 82 (it can be understood that "radial" here refers to the radial direction of the scroll expander 100). The mounting portion 82 is generally annular, while the counterweight portion 84 is generally arc-shaped. The counterweight portion 84 may extend beyond the mounting portion 82 in the axial direction. In this embodiment, the balance block 80 is disposed in the cavity C defined by the main body portion 32 of the main bearing housing 30. However, those skilled in the art will understand that the balance block 80 may also be disposed in other locations, for example, at a position between the main bearing housing 30 and the motor 50 in the axial direction of the scroll expander 100, or at a position below the motor 50 in the axial direction of the scroll expander 100.

[0038] To monitor the rotational speed of the vortex expander 100 during operation and prevent mechanical damage such as bearing system wear and electromagnetic damage to the motor caused by the motor speed exceeding the rated speed, the organic Rankine cycle system according to this invention also includes a control system CS (in... Figure 1 (as shown in the image).

[0039] Specifically, such as Figure 3 and Figure 4 As shown, the control system CS includes a proximity switch 90 for detecting the rotational speed of the motor 50. The proximity switch 90 is disposed within the scroll expander 100 and arranged such that its sensing surface 92 is close to the counterweight 80. During the operation of the scroll expander 100, the counterweight 80 rotates with the rotating shaft 40. Each time the counterweight 80 (specifically, the counterweight 84 of the counterweight 80) rotates past the sensing surface 92 of the proximity switch 90, the proximity switch 90 generates a signal. By detecting the number of times the counterweight 80 rotates past the proximity opening 90 (sensing surface 92) per minute, the rotational speed of the rotating shaft 40 or the motor 50 can be indirectly obtained. In other words, in this invention, the control system CS uses a proximity switch as a sensing device and indirectly obtains the motor speed by detecting the number of times the counterweight 80 rotates past the proximity switch per minute. Compared with sensors that directly detect motor speed, such as encoders mounted on the shaft of a servo motor, this method is more cost-effective and particularly suitable for applications that do not require precise control of the motor position.

[0040] Preferably, in one embodiment of the present invention, the proximity switch 90 is mounted on the main bearing housing 30 of the scroll expander 100, so that the scroll expander 100 is compact and easy to install and operate. More preferably, as Figure 3As shown, the main bearing seat 30 is provided with a mounting hole 33 extending through the main body portion 32 along the radial direction of the scroll expander 100, the mounting hole 33 being capable of communicating the cavity C with the outside of the main bearing seat 30, the proximity switch 90 being arranged to pass through the mounting hole 33 so that the sensing surface 92 of the proximity switch 90 is located within the cavity C. That is, the proximity switch 90 can be inserted into the mounting hole 33, so that no additional mounting or fixing structure is needed to support the proximity switch, i.e. the proximity switch 90 can be mounted within the scroll expander 100, thus making the structure of the scroll expander 100 simpler.

[0041] Further, one end of the sensing surface 92 of the proximity switch 90 is located within the cavity C so as to detect the rotational speed of the motor in cooperation with the balance block 80, and the other end of the proximity switch 90 opposite to the one end of the sensing surface 92 can be located outside the main bearing seat 30 so as to be electrically connected with the control output port 70 (see Fig. 1) provided on the main body portion 12 of the housing 10. In addition to the proximity switch, the control system CS further comprises a controller, which can be arranged separately from the scroll expander 100 or mounted on the scroll expander 100. The control output port 70 can be electrically connected to the controller of the control system CS, so that the rotational speed signal detected by the proximity switch 90 can be output to the controller of the control system CS via the control output port 70, so as to control the operation of the controller for the control of the organic Rankine cycle system 100. Figure 2

[0042] The specific configuration of the control system CS and the control operation mode of the control system CS for the organic Rankine cycle system 100 will be described below. The controller of the control system CS is configured to be electrically connected with the supply valve V1 and the bypass valve V2, so as to control the flow of the first fluid pipe L1 and the third fluid pipe L3 according to different working conditions, to ensure that the scroll expander 100 operates efficiently and safely. Specifically, in the starting stage of the scroll expander 100, the control system CS controls the supply valve V1 to be closed (completely closed) and the bypass valve V2 to be opened (completely opened), so as to establish a predetermined pressure difference in the scroll expander 100. That is, before the working fluid is supplied to the scroll expander 100, the working fluid pump 102 is first started to circulate the working fluid in the external fluid circulation path L, i.e. the working fluid circulates through the condenser 101, the working fluid pump 102, the evaporator 103 and the third fluid pipe L3. When the fluid in the external fluid circulation path L reaches a certain pressure, the fluid pressure in the first fluid pipe L1 is higher than that in the second fluid pipe L2 by a predetermined pressure difference, so as to establish a predetermined pressure difference in the scroll expander 100 (i.e. between the high-pressure area P2 and the low-pressure area P2). Due to the establishment of the predetermined pressure difference, the floating seal S in the scroll expander 100 can normally float, so as to ensure the normal sealing of the scroll expander 100 and the normal operation of the scroll expander 100. ​

[0043] After the predetermined pressure difference is established in the scroll expander 100, the scroll expander 100 is started and enters a normal operation stage. In the normal operation stage of the scroll expander 100, the control system CS controls the supply valve V1 to open (fully open) and the bypass valve V2 to close (fully close). The high pressure fluid is supplied to the high pressure area P1 of the scroll expander 100, and then enters the expansion mechanism 20 and is expanded step by step with the pressure decreasing, and finally is discharged to the low pressure area P2. At the same time, the orbiting scroll 24 of the expansion mechanism 20 rotates and drives the rotating shaft 40 to rotate, thereby driving the motor 50 to rotate and outputting electric power.

[0044] During the operation of the scroll expander 100, when the sensor device (i.e., the proximity switch 90) detects that the rotating speed of the motor 50 of the scroll expander 100 exceeds a predetermined threshold value, the control system CS controls the supply valve V1 to close (fully close) and controls the bypass valve V2 to open (fully open). This can particularly prevent the mechanical damage of the scroll expander caused by the motor rotor stalling. For example, during the operation of the organic Rankine cycle system, if the power grid load fails, the high pressure gas still continuously drives the scroll mechanism to operate, and the rotor of the motor can rotate at a high speed under the action of the high pressure gas, exceeding the rated speed of the bearing, thereby causing the wear of the bearing system, or the motor generates a large reverse current and reverse voltage during rotation, causing damage to the motor, and ultimately causing the scroll expander to be unable to operate normally. In the present application, since the control system CS can monitor the speed during the operation of the scroll expander 100, when the proximity switch 90 detects that the rotating speed of the motor 50 exceeds the predetermined threshold value, the supply valve V1 is closed, thereby stopping the supply of high pressure fluid to the scroll expander 100, effectively avoiding the mechanical damage of the scroll expander 100. In addition, since the control system CS simultaneously opens the bypass valve V2, the organic Rankine cycle system ES can still circulate through the third fluid pipe L3, without stopping the operation of the entire circulating system, thereby reducing the energy loss.

[0045] Preferably, the control system CS is configured to control the supply valve V1 and the bypass valve V2 to alternately open (fully open) or close (fully close) during the operation of the organic Rankine cycle system ES, and cannot be closed (fully open) or opened (fully open) at the same time, thereby ensuring the fluid circulation of the organic Rankine cycle system, reducing energy loss and avoiding failure.

[0046] Alternatively or additionally, when the sensing device (i.e., the proximity switch 90) detects that the rotation speed of the motor 50 of the scroll expander 100 exceeds the predetermined threshold, the control system CS can control the opening degree of the supply valve V1 to decrease and control the opening degree of the bypass valve V2 to increase. When the opening degree of the supply valve V1 decreases, the flow rate of the high-pressure fluid supplied to the scroll expander 100 via the first fluid pipe L1 decreases, and the operating speed of the scroll expander will correspondingly decrease, thus effectively avoiding mechanical damage caused by overspeed, especially suitable for application scenarios where the scroll expander 100 cannot be immediately stopped.

[0047] Those skilled in the art can understand that the control system CS preferably performs control operations for the three stages and situations of the start-up stage of the scroll expander, the normal operation stage of the scroll expander, and the situation where the scroll expander is detected to be overspeed, thereby providing comprehensive monitoring and protection for the operation of the organic Rankine cycle system. However, the control system CS can also perform control operations for one or more of the start-up stage of the scroll expander, the normal operation stage of the scroll expander, and the situation where the scroll expander is detected to be overspeed.

[0048] For example, the control system CS can be configured to mainly perform control operations for the situation where the scroll expander is detected to be overspeed. Specifically, although in the above-mentioned embodiments, the control system CS controls the opening degree of the supply valve V1 to decrease and controls the opening degree of the bypass valve V2 to increase when the proximity switch 90 detects that the rotation speed of the motor 50 exceeds the predetermined threshold, the control system CS can also control the opening degree of the supply valve V1 to decrease and control the opening degree of the bypass valve V2 to increase when the proximity switch 90 detects that the rotation speed of the motor 50 is less than the predetermined threshold. Figure 1 In the illustrated embodiments, the two ports of the third fluid pipe L3 are connected to the first fluid pipe L1 and the second fluid pipe L2, respectively, but those skilled in the art can understand that the two ports of the third fluid pipe L3 can also be connected to the housing 10 of the scroll expander 100, for example, to the top cover 14 and the main body 12 of the scroll expander 100, respectively, thereby directly communicating with the high-pressure area P1 and the low-pressure area P2, respectively. In this case, the control system CS is configured to close the bypass valve V2 when the proximity switch 90 detects that the rotation speed of the motor 50 does not exceed the predetermined threshold, and to open the bypass valve V2 when the proximity switch 90 detects that the rotation speed of the motor 50 exceeds the predetermined threshold. Thus, when the scroll expander is detected to be overspeed, the high-pressure area P2 and the low-pressure area P2 of the scroll expander 100 are communicated via the third fluid pipe L3, at this time even if the high-pressure gas is still supplied to the scroll expander 100, the scroll expander 100 cannot operate normally, thus ensuring that the scroll expander 100 will not rotate at high speed in the state of entering high-pressure gas.

[0049] In addition, although in the embodiments of the present application, the third fluid pipe is designed as a pipe outside the scroll expander, those skilled in the art can understand that the third fluid pipe can also be designed inside the scroll expander, or even formed as an internal fluid path of the scroll expander, without the need to adopt a separate pipe, as long as the third fluid pipe can communicate the high-pressure area and the low-pressure area of the scroll expander.

[0050] The organic Rankine cycle system according to the preferred embodiment of the present application is described above in conjunction with the specific embodiments. It can be understood that the above description is only exemplary but not restrictive, and various modifications and changes can be conceived by those skilled in the art with reference to the above description without departing from the scope of the present application. The modifications and changes are also included in the protection scope of the present application.

Claims

1. An organic Rankine cycle system (ES) comprising: a scroll expander (100) comprising a casing (10) enclosing an internal space, which is divided into a high-pressure zone (PI) and a low-pressure zone (P2), the scroll expander further comprising an expander mechanism (20), a main bearing block (30) for supporting the expander mechanism, a rotating shaft (40) driven by the expander mechanism, and a motor (50) connected to the rotating shaft, the rotating shaft having a balance weight (80) mounted thereon; an external fluid circulation path (L) comprising a first fluid pipe (LI) connected to an intake fitting (17) of the scroll expander, a second fluid pipe (L2) connected to an exhaust fitting (18) of the scroll expander, and a third fluid pipe (L3) capable of fluidly connecting the high-pressure zone and the low-pressure zone; and a control system (CS) configured to control a flow rate in the third fluid pipe in accordance with a rotational speed of the motor, characterized in that the control system comprises a proximity switch (90) for detecting the rotational speed of the motor, the proximity switch being disposed within the scroll expander and arranged such that a sensing face (92) of the proximity switch is in proximity to the balance weight (80).

2. Organic Rankine cycle system (ES) according to claim 1, characterized in that The proximity switch is mounted to the main bearing block of the scroll expander.

3. Organic Rankine cycle system (ES) according to claim 1, characterized in that The main bearing block comprises a substantially cylindrical main body portion (32) defining a concave cavity (C) in which the balance weight is arranged, the main body portion is provided with a mounting hole (93) capable of communicating the concave cavity with an outside of the main bearing block, the proximity switch being interposed in the mounting hole such that the sensing face of the proximity switch is located in the concave cavity.

4. The organic Rankine cycle system (ES) according to claim 1, characterized in that The balance weight comprises a mounting portion (82) for mounting the balance weight to the rotating shaft, and a counterweight portion (84) located radially outward of the mounting portion, the proximity switch obtaining the rotational speed of the motor by detecting a number of times per minute that the counterweight portion rotates past the sensing face of the proximity switch.

5. Organic Rankine cycle system (ES) according to any one of claims 1 to 4, characterized in that The third fluid pipe is provided with a bypass valve (V2), the control system being configured to close the bypass valve in the event that the proximity switch detects that the rotational speed of the motor does not exceed a predetermined threshold, and the control system being configured to open the bypass valve in the event that the proximity switch detects that the rotational speed of the motor exceeds a predetermined threshold.

6. Organic Rankine cycle system (ES) according to any one of claims 1 to 4, characterized in that The third fluid pipe has a first port (L31) and a second port (L32) opposite each other, the first port being connected to and in communication with the first fluid pipe, the second port being connected to and in communication with the second fluid pipe, the first fluid pipe is provided with a supply valve (VI), the third fluid pipe is provided with a bypass valve (V2), and the first port is located upstream of the supply valve with respect to a connection point (171) of the first port to the first fluid pipe.

7. Organic Rankine cycle system (ES) according to claim 6, characterized in that The control system further comprises a controller electrically connected to the proximity switch, the supply valve, and the bypass valve.

8. Organic Rankine cycle system (ES) according to claim 6, characterized in that said control system being configured to fully open said supply valve and fully close said bypass valve in case said proximity switch detects that the rotational speed of said electric motor does not exceed a predetermined threshold, and said control system being configured to fully close said supply valve and fully open said bypass valve or to decrease the opening degree of said supply valve and to increase the opening degree of said bypass valve in case said proximity switch detects that the rotational speed of said electric motor exceeds a predetermined threshold.

9. Organic Rankine cycle system (ES) according to claim 6, characterized in that said control system being further configured to fully close said supply valve and fully open said bypass valve during a start-up phase of said scroll expander.

10. The organic Rankine cycle system (ES) according to claim 6, characterized in that said control system being further configured to avoid simultaneously fully closing said supply valve and fully opening said bypass valve and to avoid simultaneously fully opening said supply valve and fully closing said bypass valve during a normal operation of said scroll expander.

11. An organic Rankine cycle system (ES) comprising: a scroll expander (100); an external fluid circulation path (L) comprising a first fluid pipe (LI) connected to an intake fitting (17) of said scroll expander, a second fluid pipe (L2) connected to an exhaust fitting (18) of said scroll expander and a third fluid pipe (L3) communicating with said first fluid pipe and said second fluid pipe, wherein said first fluid pipe is provided with a supply valve (VI) and said third fluid pipe is provided with a bypass valve (V2); and a control system (CS) comprising a sensing device provided inside said scroll expander for detecting the rotational speed of an electric motor of said scroll expander, characterized in that said control system is configured to close said supply valve and to open said bypass valve to establish a predetermined pressure difference inside said scroll expander during a start-up phase of said scroll expander, to open said supply valve and to close said bypass valve during a normal operation of said scroll expander, and to close said supply valve and to open said bypass valve or to control a decrease of the opening degree of said supply valve and to control an increase of the opening degree of said bypass valve when said sensing device detects that the rotational speed of said electric motor exceeds a predetermined threshold.

12. Organic Rankine cycle system (ES) according to claim 11, characterized in that said sensing device is configured as a proximity switch (90).

13. Organic Rankine cycle system (ES) according to claim 12, characterized in that said proximity switch is mounted to a main bearing seat (30) of said scroll expander.

14. Organic Rankine cycle system (ES) according to claim 13, characterized in that said main bearing seat comprises a substantially cylindrical body portion (32) defining a concave cavity (C) in which a counterweight (80) connected to a rotating shaft (40) of said scroll expander is arranged, said proximity switch generating a signal each time said counterweight approaches said proximity switch to detect the rotational speed of said electric motor.

15. Organic Rankine cycle system (ES) according to any of claims 11 to 14, characterized in that said control system (CS) further comprises a controller electrically connected to said sensing device, said supply valve and said bypass valve.

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