Organic Rankine cycle cooling system and cooling method

Abstract

The organic Rankine cycle cooling system comprises a working medium pump, an expansion machine, a motor, an evaporator and a condenser, and further comprises a regulating valve and a temperature control element, and the expansion machine, the working medium pump and the motor are coaxially connected; the regulating valve is electrically connected with the temperature control element and is connected with the motor through a pipeline; the temperature control element is connected with the motor; the working medium pump comprises a working medium pump impeller sealing structure; the working medium pump impeller sealing structure is arranged in a gap between the working medium pump and the motor; a cooling channel is arranged at an outlet gap of the working medium pump impeller; a plurality of cooling bypass inlets are formed in a shell of the motor; the invention further comprises a cooling method. According to the invention, the influence of sealing leakage in the rotary fluid machinery is solved, and meanwhile, an external cooling component is not needed to cool a rotary power component, so that the operation efficiency of the system is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor sealing and cooling, and particularly relates to an organic Rankine cycle cooling system and a cooling method. Background Art

[0002] In an organic working fluid circulation system, an expander and a working fluid pump can be coaxially connected. One input end of the generator is the expander, and the other output end is the working fluid pump. When the circulation system operates, the inside of the working fluid pump is a liquid working fluid, and there is a risk of liquid leakage at the outlet. Without corresponding sealing treatment, it is easy for the liquid working fluid to leak to the motor bearing and rotor. The existing sealing structures adopted by liquid working fluid pumps are relatively complex, troublesome to replace, and there may be a situation of easily worn bearings. At the same time, corresponding sealing measures also need to be taken at the expander end to reduce gas leakage and improve the operating efficiency of the unit. Moreover, when the direct drive system operates, the temperature of the generator rises rapidly, generating a large amount of heat. And the higher the temperature, the relatively lower its operating efficiency. When the motor operates at a relatively high temperature, its service life is shorter.

[0003] Generally, mechanical seals or packing seals are used for liquid pumps. Mechanical seals have the problems of relatively complex structures, troublesome maintenance and replacement. Using such seals also increases the corresponding costs, and there is also a risk of leakage. In motor cooling, air cooling or liquid cooling is generally used to cool the motor. Both of these methods require adding an external air cooling or liquid cooling power source, which will increase the volume of the system and increase energy consumption.

[0004] A patent with the publication number of CN106996315A in the prior art, an ORC expander-driven generator and liquid pump energy-saving unit, includes an expander, a generator, an evaporator, a liquid pump, and a condenser. The condenser, the liquid pump, the evaporator, and the expander are connected in sequence to form a cycle. The input end of the generator is connected to the expander and the output end of the generator is connected to the liquid pump, so that the expander directly drives the liquid pump. This invention achieves the dual purposes of energy saving and reducing the main equipment components of the ORC system. However, this invention does not perform sealing and cooling treatment on the working fluid pump and the expander. When the system operates, the liquid working fluid is likely to leak, resulting in motor damage. Summary of the Invention

[0005] The present invention mainly aims at the problems in the prior art that mechanical seals or packing seals are used for liquid pumps in an organic working fluid circulation system. Mechanical seals have relatively complex structures, troublesome maintenance and replacement. Using such seals also increases the corresponding costs, and there is also a risk of leakage. In motor cooling, air cooling or liquid cooling is generally used to cool the motor. For both of these methods, an external air cooling or liquid cooling power source needs to be added, which will increase the volume of the system and increase energy consumption, and proposes an organic Rankine cycle cooling system.

[0006] In view of the above technical problems, the technical solution of the present invention is as follows:

[0007] An organic Rankine cycle cooling system includes a working fluid pump, an expander, a motor, an evaporator, and a condenser, and further includes a regulating valve and a temperature control element. The expander, the working fluid pump, and the motor are coaxially connected. The regulating valve is electrically connected to the temperature control element, and the regulating valve is connected to the motor through a pipeline. The temperature control element is connected to the motor. The working fluid pump includes a working fluid pump impeller sealing structure, and the working fluid pump impeller sealing structure is arranged in the gap between the working fluid pump impeller and the motor. A cooling channel is provided at the outlet gap of the working fluid pump impeller, and the gaseous working fluid flowing into the motor from the cooling channel seals the outside of the expander impeller. A plurality of cooling bypass inlets are provided on the housing of the motor.

[0008] Further, the expander, the condenser, the working fluid pump, and the evaporator are sequentially connected through pipelines.

[0009] Further, the working fluid pump impeller sealing structure is arranged near the axis center of the impeller disc, and the working fluid pump impeller sealing structure is a toothed structure.

[0010] Further, the cooling channel introduces into the housing of the motor.

[0011] Further, the leakage liquid at the outlet of the impeller of the working fluid pump all flows into the cooling channel.

[0012] Further, there are two regulating valves, including a first regulating valve and a second regulating valve. The input end and the output end of the first regulating valve are respectively connected to the motor and the inlet end of the condenser through pipelines.

[0013] Further, a bypass branch is provided between the working fluid pump and the evaporator, and the second regulating valve is arranged on the bypass branch. The second regulating valve is used to adjust the flow rate of the liquid working fluid entering the cooling channel.

[0014] Further, the first regulating valve and the second regulating valve are electric regulating valves, pneumatic regulating valves, or hydraulic regulating valves.

[0015] Further, the temperature control element detects the evaporation temperature of the working fluid in the cooling channel.

[0016] An organic Rankine cycle cooling method is applied to the above cooling system and includes the following steps:

[0017] S1. The working fluid pump pressurizes the liquid working fluid in the system to form a high-pressure and low-temperature liquid working fluid;

[0018] S2. Part of the high-pressure and low-temperature liquid working medium at the outlet of the working medium pump is introduced into the housing cooling channel of the generator through the leakage cooling channel of the gap at the outlet of the working medium pump impeller, and the other part is introduced through the bypass branch at the outlet of the working medium pump. The liquid working medium exchanges heat with the generator in the cooling channel and evaporates into gaseous working medium after absorbing heat.

[0019] S3. The gaseous working medium in step S2 flows out of the cooling channel and then enters the air gap of the generator rotor to cool components such as the rotor; the gaseous working medium after cooling the generator flows out of the generator housing and forms a gas sealing layer outside the expander impeller to reduce gas leakage on the expander side.

[0020] S4. The sealed gaseous working medium is connected to the condenser through a pipeline and converges with the main circulating working medium of the system to continue circulating.

[0021] S5. The evaporation temperature of the working medium in the cooling channel in the generator is monitored in real time through a temperature control element. When the evaporation temperature is lower than the preset threshold, the opening of the regulating valve on the bypass branch is feedback-regulated to increase the flow rate of the liquid working medium entering the cooling channel, so that the liquid working medium is completely evaporated in the cooling channel and prevent unevaporated liquid working medium from entering the motor interior.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. The organic working medium circulation cooling system of the present invention includes a working medium pump, an expander, a motor, an evaporator, and a condenser, and also includes a regulating valve and a temperature control element. The expander, the working medium pump, and the motor are coaxially connected; the regulating valve is electrically connected to the temperature control element, and the regulating valve is connected to the motor through a pipeline; the temperature control element is connected to the motor; the working medium pump includes a working medium pump impeller sealing structure, and the working medium pump impeller sealing structure is arranged in the gap between the working medium pump and the motor; a cooling channel is provided at the gap at the outlet of the working medium pump impeller; multiple cooling bypass inlets are provided on the housing of the motor; when the system operates, the working medium pump pressurizes and does work on the working medium, and part of the working medium leaks from the gap at the outlet of the working medium pump impeller. A small part of the leaked working medium can be used for cooling the generator. The high-pressure and low-temperature liquid working medium leaked from the working medium pump flows into the motor cooling tank through the back of the impeller and the channels designed in the motor to cool the motor, solving the influence of seal leakage in rotary fluid machinery, and at the same time, there is no need to add external cooling components to cool the rotary power components.

[0024] 2. The gaseous working medium in the cooling system flows out of the cooling tank and then flows into the air gap of the motor rotor for cooling. After the internal circulation of the motor is completed, this part of the gaseous working medium finally flows out of the other end housing and enters the inlet pipeline of the condenser. At the same time, this part of the gaseous working medium can be used on the expander side for gas sealing on one side of the expander, reducing the complexity of the system, saving costs, and improving the operating efficiency of the system. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of an organic Rankine cycle cooling system;

[0026] Figure 2 It is a schematic diagram of the internal structure of the motor of an organic Rankine cycle cooling system.

[0027] In the above figures, 1. expander; 2. working fluid pump; 3. motor; 4. evaporator; 5. condenser; 6. first regulating valve; 7. second regulating valve; 8. temperature control element; 9. expander impeller; 10. rotor; 11. stator; 12. housing; 13. working fluid pump impeller; 14. working fluid pump impeller seal structure; 15. cooling channel; 16. working fluid pump leakage inlet; 17. cooling bypass inlet. Detailed implementation manners

[0028] To clearly illustrate the technical features of the solution of this invention application, the present invention will be elaborated in detail below through specific implementation manners and in combination with its accompanying drawings.

[0029] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0030] In addition, in the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality" means two or more unless otherwise specifically defined.

[0031] In the present invention, unless otherwise clearly specified and defined, terms such as "installed", "connected", "joined", "fixed", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, or a communication connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description of reference terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0033] Embodiment 1

[0034] As Figure 1 shown in Figure 2 FIG., an organic Rankine cycle cooling system includes a working fluid pump 2, an expander 1, a motor 3, an evaporator 4, and a condenser 5, and further includes a regulating valve and a temperature control element 8. Among them, the expander 1, the working fluid pump 2, and the motor 3 are coaxially connected; the regulating valve is electrically connected to the temperature control element 8, and the regulating valve is connected to the motor 3 through a pipeline; the temperature control element 8 is connected to the motor 3; the working fluid pump 2 includes a working fluid pump impeller sealing structure 14, and the working fluid pump impeller sealing structure 14 is arranged in the gap between the working fluid pump impeller 13 and the motor 3; a cooling channel 15 is provided at the outlet gap of the working fluid pump impeller 13, and the gaseous working fluid flowing into the interior of the motor 3 from the cooling channel 15 seals the outside of the expander impeller 9; a plurality of cooling bypass inlets 17 are provided on the housing 12 of the motor 3.

[0035] As Figure 1 shown in FIG., in this embodiment, the outlet end of the expander 1 is connected to the inlet end of the condenser 5, the outlet end of the condenser 5 is connected to the inlet end of the working fluid pump 2, the outlet end of the working fluid pump 2 is connected to the inlet end of the evaporator 4, and the outlet end of the evaporator 4 is connected to the inlet end of the expander 1; the driving end of the expander 1 is connected to one end of the motor 3, and the driving end of the motor 3 is connected to the working fluid pump 2; when starting up, the motor 3 drives the working fluid pump 2; when the organic working fluid vapor in the evaporator 4 enters the expander 1, the expander 1 drives the motor 3 to generate electric energy.

[0036] Figure 1 The motor 3 in it acts as an electric motor, driving the expanders 1 and the working fluid pump 2 at both ends of the same axis to rotate. The working fluid pump 2 pressurizes the liquid working fluid in the system, and high-pressure and low-temperature liquid working fluid is obtained from the outlet of the working fluid pump 2. This part of the liquid working fluid then flows into the evaporator 4, and the external waste heat heats this part of the high-pressure liquid working fluid, vaporizing it. High-pressure and high-temperature gas working fluid is obtained from the outlet of the evaporator 4. This part of the high-temperature and high-pressure gas working fluid flows into the expander 1. When this part of the liquid working fluid reaches the required working pressure and temperature, the liquid working fluid does work on the expander 1, driving the motor 3 to rotate by the expander 1. At this time, the motor 1 is converted into a generator, and at the same time drives the coaxial working fluid pump 2 to continue to rotate and work.

[0037] As Figure 1 and Figure 2 shown, when the system is running, since both the working fluid pump 2 and the expander 1 in the rotary fluid machinery are coaxially connected to the motor 3, there will be a certain gap when they are assembled with the motor 3. Therefore, there is a gap between the rotor and the stator, and a part of leakage will occur. Among them, the working fluid pump 2 does work on the liquid working fluid, and it is necessary to ensure that this part of the leaked liquid does not enter the motor bearing and the rotor 10. Therefore, a certain sealing structure is designed for the rear side of the working fluid pump impeller 13. A toothed sealing structure is arranged at the disk of the working fluid pump impeller 13 near the shaft center to prevent the leaked liquid generated during the operation of the working fluid pump 2 from entering the shaft end. At the outlet gap of the working fluid pump impeller 13, that is, at the working fluid leakage inlet 16, a cooling channel 15 is designed, and this cooling channel 15 is introduced into the casing 12. Due to the guiding effect of the cooling channel 15, and the working fluid pump sealing structure 14 can ensure that the leaked liquid at the outlet of the working fluid pump impeller 13 all flows into the cooling channel 15, cooling the inside of the motor 3 and improving the operating efficiency of the system.

[0038] This embodiment provides a cooling method applied to an organic Rankine cycle cooling system, including the following steps:

[0039] S1. The working fluid pump pressurizes the liquid working fluid in the system to form high-pressure and low-temperature liquid working fluid;

[0040] S2. Part of the high-pressure and low-temperature liquid working fluid at the outlet of the working fluid pump is introduced into the casing cooling channel of the generator through the leakage cooling channel at the outlet gap of the working fluid pump impeller, and the other part is introduced through the bypass branch at the outlet of the working fluid pump. The liquid working fluid exchanges heat with the generator in the cooling channel, absorbs heat and evaporates into gas working fluid;

[0041] S3. The gas working fluid in step S2 flows out of the cooling channel and then enters the generator rotor air gap to cool the rotor and other components; the gas working fluid after cooling the generator flows out of the generator casing and forms a gas sealing layer outside the expander impeller to reduce the gas leakage on the expander side;

[0042] S4. The sealed gaseous working medium is connected to the condenser through a pipeline, and converges with the main circulating working medium of the system to continue circulating;

[0043] S5. The evaporation temperature of the working medium in the cooling channel inside the generator is monitored in real time through a temperature control element. When the evaporation temperature is lower than a preset threshold, the opening degree of the regulating valve on the bypass branch is feedback-regulated to increase the flow rate of the liquid working medium entering the cooling channel, so that the liquid working medium is completely evaporated in the cooling channel, and the unevaporated liquid working medium is prevented from entering the motor interior.

[0044] The present invention only uses one kind of insulating cooling working medium to circulate and cool the cooling system. By directly using the gas cooled by the motor for the seal outside the expander impeller, a closed-loop cooling design of "leakage utilization - cooling - seal" is formed, solving the seal leakage problem in rotary fluid machinery. At the same time, no external cooling components need to be added, reducing the system complexity, saving costs, and improving the system operation efficiency.

[0045] Embodiment 2

[0046] As Figure 1 shown in Figure 2 shown in

[0047] A kind of organic Rankine cycle cooling system, including a working medium pump 2, an expander 1, a motor 3, an evaporator 4 and a condenser 5, further including a regulating valve and a temperature control element 8. Among them, the expander 1, the working medium pump 2 and the motor 3 are coaxially connected; the regulating valve is electrically connected to the temperature control element 8, and the regulating valve is connected to the motor 3 through a pipeline; the temperature control element 8 is connected to the motor 3; the working medium pump 2 includes a working medium pump impeller seal structure 14, and the working medium pump impeller seal structure 14 is arranged in the gap between the working medium pump impeller 13 and the motor 3; a cooling channel 15 is arranged at the outlet gap of the working medium pump impeller 13, and the gas working medium flowing into the interior of the motor 3 from the cooling channel 15 seals the outside of the expander impeller 9; a plurality of cooling bypass inlets 17 are arranged on the casing 12 of the motor 3.

[0048] In this embodiment, the first regulating valve 6 and the second regulating valve 7 can adopt hydraulic regulating valves.

[0049] Embodiment 3

[0050] like Figure 1 and Figure 2 As shown, in this embodiment, the liquid working fluid evaporates into a gaseous state in the cooling channel 15 of the motor 3 and then circulates for cooling in the motor 3. The pressure of this part of the gas working fluid flowing out of the cooling channel 15 is at a relatively high value, which can be used for gas sealing treatment on the expander 1 side to reduce gas leakage on the expander 1 side. Therefore, there is no need to add mechanical seals or other types of seals at the expander impeller 9 to control gas leakage, which improves the stability of the system and reduces the complexity of the structure.

[0051] The organic working fluid circulation cooling system can be applied to other waste heat recovery and utilization systems and various medium circulation systems, and can also achieve the circulation cooling effect to improve the working efficiency and service life of the motor.

[0052] Obviously, the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. An organic Rankine cycle cooling system, comprising a working fluid pump, an expander, a motor, an evaporator and a condenser, characterized in that: It also includes a regulating valve and a temperature control element, the expander, the working fluid pump and the motor are coaxially connected; the regulating valve is electrically connected to the temperature control element, and the regulating valve is connected to the motor through a pipeline; the temperature control element is connected to the motor; the working fluid pump includes a working fluid pump impeller sealing structure, and the working fluid pump impeller sealing structure is arranged in the gap between the working fluid pump impeller and the motor; a cooling channel is provided at the outlet gap of the working fluid pump impeller, and the gas working fluid flowing into the motor from the cooling channel seals the outer side of the expander impeller; a plurality of cooling bypass inlets are provided on the casing of the motor.

2. The organic Rankine cycle cooling system according to claim 1, characterized in that: The expander, condenser, working fluid pump and evaporator are connected in sequence through pipelines.

3. The organic Rankine cycle cooling system according to claim 1, characterized in that: The impeller sealing structure of the working fluid pump is arranged at the impeller wheel disc close to the center of the shaft, and the impeller sealing structure of the working fluid pump is a toothed structure.

4. The organic Rankine cycle cooling system according to claim 1, characterized in that: The cooling channel leads into the housing of the electric machine.

5. The organic Rankine cycle cooling system according to claim 4, characterized in that: The leaked liquid at the impeller outlet of the working fluid pump flows into the cooling channel.

6. The organic Rankine cycle cooling system according to claim 1, characterized in that: The regulating valves are provided with two, including a first regulating valve and a second regulating valve, and the input end and the output end of the first regulating valve are respectively connected to the inlet end of the motor and the condenser through pipelines.

7. The organic Rankine cycle cooling system according to claim 6, characterized in that: A bypass branch is provided between the working medium pump and the evaporator, the second regulating valve is provided on the bypass branch, and the second regulating valve is used to regulate the flow rate of the liquid working medium entering the cooling channel.

8. The organic Rankine cycle cooling system according to claim 6, characterized in that: The first regulating valve and the second regulating valve are electric regulating valves, pneumatic regulating valves or hydraulic regulating valves.

9. The organic Rankine cycle cooling system according to claim 1, characterized in that: The temperature control element detects the evaporation temperature of the working medium in the cooling channel.

10. An organic Rankine cycle cooling method, characterized in that: The cooling system according to any one of claims 1 to 9 comprises the following steps: S1, the working fluid pump pressurizes the liquid working fluid in the system to form a high-pressure and low-temperature liquid working fluid; S2, introducing a part of the high-pressure and low-temperature liquid working fluid at the outlet of the working fluid pump into the casing cooling channel of the generator through the leakage cooling channel of the outlet gap of the working fluid pump impeller, and another part through the bypass branch of the working fluid pump outlet, wherein the liquid working fluid exchanges heat with the generator in the cooling channel, and evaporates into gaseous working fluid after absorbing heat; S3, the gaseous working medium in step S2 flows out of the cooling channel and enters the air gap of the generator rotor to cool the rotor and other components; the gaseous working medium after cooling the generator flows out of the generator casing and forms a gas sealing layer on the outside of the expander impeller to reduce gas leakage on the expander side; S4, the sealed gaseous working medium is connected to the condenser through the pipeline, and merges with the main circulating working medium of the system to continue circulating; S5. The evaporation temperature of the working medium in the cooling channel of the generator is monitored in real time through the temperature control element. When the evaporation temperature is lower than the preset threshold, the opening of the regulating valve on the bypass branch is adjusted to increase the flow rate of the liquid working medium entering the cooling channel, so that the liquid working medium can be completely evaporated in the cooling channel, thereby preventing the unevaporated liquid working medium from entering the motor.

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