A cold energy power generation system, a heat exchange assembly and a power generation method

Abstract

The application discloses a cold energy power generation system, a heat exchange assembly and a power generation method, and belongs to the technical field of cold energy power generation. The cold energy power generation system comprises a working medium assembly, a power generation assembly, a lubricating oil assembly and a heat exchange assembly. The working medium assembly comprises a working medium pump, an evaporator, an expander and a condenser connected in series. The condenser is connected with the working medium pump and forms a working medium circuit. The power generation assembly is connected with the expander. The expander can drive the power generation assembly to generate power. The lubricating oil assembly is connected with the expander and the power generation assembly and forms a lubricating oil circuit, which is used for cooling the expander and the power generation assembly. The heat exchange assembly comprises a working medium pipe and a lubricating oil pipe arranged adjacently. The working medium pipe is communicated with the working medium circuit, and the lubricating oil pipe is communicated with the lubricating oil circuit. The heat exchange assembly is used for transferring heat in the lubricating oil to the working medium. Through the heat recovery of the lubricating oil and the provision of the working medium, the power generation capacity and the power generation efficiency are improved, and the lubricating oil is cooled.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cold energy power generation, and particularly relates to a cold energy power generation system, a heat exchange assembly and a power generation method. BACKGROUND

[0002] With the rapid development of the LNG (liquid natural gas) industry and the air separation industry, the cold energy utilization of LNG receiving stations and air separation devices has attracted more and more attention, and cold energy power generation is a relatively suitable utilization mode. Meanwhile, there are a large number of mechanical rotating devices in the production processes of LNG receiving stations, LNG filling stations, LNG satellite stations and air separation enterprises, and most of the mechanical rotating devices are lubricated and cooled by using a lubricating oil system.

[0003] However, the temperature rise caused by the lubricating oil cooling cannot be effectively utilized, and the lubricating oil cooling needs additional equipment and cooling cost, and the energy saving and emission reduction effect is poor, and the energy utilization rate is low. SUMMARY

[0004] The application aims to overcome the technical problem that the current cooling mode of lubricating oil does not meet the energy saving and emission reduction requirements.

[0005] The application provides a cold energy power generation system, which comprises:

[0006] A working medium assembly comprising a working medium pump, an evaporator, an expander and a condenser connected in series, wherein the condenser is connected with the working medium pump and forms a working medium loop;

[0007] A power generation assembly connected with the expander, wherein the expander can drive the power generation assembly to generate power;

[0008] A lubricating oil assembly connected with the expander and the power generation assembly and forming a lubricating oil loop, which is used for cooling the expander and the power generation assembly;

[0009] A heat exchange assembly comprising a working medium pipe and a lubricating oil pipe arranged adjacently, wherein the working medium pipe is connected in series on the working medium loop between the working medium pump and the expander, the lubricating oil pipe is in communication with the lubricating oil loop, and the heat exchange assembly is used for transferring heat in the lubricating oil to the working medium.

[0010] In some embodiments, the working medium pipe is connected in series with the working medium loop.

[0011] The working medium pipe is located on a pipeline between the evaporator and the expander, or the working medium pipe is located between the working medium pump and the evaporator.

[0012] In some embodiments, the power generation assembly comprises a generator, the expander is directly connected to the generator, and the lubricating oil assembly is connected to the expander and the generator respectively and forms a lubricating oil loop.

[0013] Alternatively, the power generation assembly comprises a gearbox and a generator, the gearbox is connected to the expander and the generator respectively, and the lubricating oil assembly is connected to the expander, the gearbox and the generator respectively and forms a lubricating oil loop.

[0014] In some embodiments, the lubricating oil assembly comprises a lubricating oil tank and a lubricating oil pump connected in series, the lubricating oil pump is connected to the expander, and the lubricating oil tank is connected to the power generation assembly.

[0015] The lubricating oil pipe is connected in series with the lubricating oil loop, and the lubricating oil pipe is located on the pipeline between the lubricating oil pump and the expander.

[0016] In some embodiments, the lubricating oil pipe is a spiral winding structure, and the working medium pipe is sleeved outside the lubricating oil pipe.

[0017] In some embodiments, the working medium pipe has a working medium inlet and a working medium outlet, the lubricating oil pipe has a lubricating oil inlet and a lubricating oil outlet, the lubricating oil inlet and the working medium outlet are located on the same side, and the working medium inlet and the lubricating oil outlet are located on the same side.

[0018] And / or, the flow direction of the working medium in the working medium pipe is opposite to the flow direction of the lubricating oil in the lubricating oil pipe.

[0019] In some embodiments, the condenser is used to convert working medium waste gas into liquid working medium, and the condenser is any one of a tube-shell heat exchanger, a plate-fin heat exchanger, and a spiral pipe heat exchanger.

[0020] In some embodiments, the expander is any one of an axial flow turbine expander, a radial turbine expander, a centrifugal turbine expander, a screw expander, or a scroll expander.

[0021] In some embodiments, the lubricating oil loop is externally connected to other equipment cooled by lubricating oil.

[0022] In some embodiments, the condenser has a plurality of condensers connected in parallel between the expander and the working medium pump, and the cold source of the condenser comprises one or more of liquid natural gas, liquid nitrogen, liquid oxygen, liquid helium, liquid argon, liquid air, liquid methane, and liquid hydrogen.

[0023] The application further discloses a heat exchange assembly, comprising adjacent working medium pipes and lubricating oil pipes, the working medium pipes being in communication with a working medium loop of a working medium assembly, the lubricating oil pipes being in communication with a lubricating oil loop of a lubricating oil assembly, and the heat exchange assembly being used for transferring heat in lubricating oil to working medium.

[0024] The application further discloses a cold energy power generation method based on the cold energy power generation system in the above embodiment, and the method comprises the following steps.

[0025] obtaining heat generation Q1 of a power generation assembly;

[0026] increasing the obtained heat generation Q1 of the power generation assembly to input heat Q of the cold energy power generation system 输 , establishing a heat balance, and obtaining heat generation Q2 of the power generation assembly;

[0027] increasing the obtained heat generation Q2 of the power generation assembly to input heat Q of the cold energy power generation system 输 , establishing a heat balance again, and obtaining heat generation Q3 of the power generation assembly;

[0028] repeating the above steps until heat generation Q n , Q n+1 of the power generation assembly is obtained, and satisfies |(Q n -Q n+1 ) / Q n |≤0.001;

[0029] calculating power generation and power generation efficiency of the cold energy power generation system.

[0030] Beneficial effects: the cold energy power generation system in the embodiment of the application comprises a working medium assembly, a power generation assembly, a lubricating oil assembly and a heat exchange assembly; the working medium assembly comprises a working medium pump, an evaporator, an expander and a condenser connected in series, the condenser is connected with the working medium pump and forms a working medium loop; the power generation assembly is connected with the expander, and the expander can drive the power generation assembly to generate power; the lubricating oil assembly is connected with the expander and the power generation assembly and forms a lubricating oil loop, and is used for cooling the expander and the power generation assembly; the heat exchange assembly comprises adjacent working medium pipes and lubricating oil pipes, the working medium pipes are in communication with the working medium loop, the lubricating oil pipes are in communication with the lubricating oil loop, and the heat exchange assembly is used for transferring heat in lubricating oil to working medium. Heat in lubricating oil is recovered and provided to working medium, so that power generation and power generation efficiency are improved, and lubricating oil is cooled. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and all other drawings obtained by those skilled in the art without creative effort based on the embodiments in the present application shall fall within the scope of the present application.

[0032] Figure 1 FIG. 1 is a structural schematic diagram of a cold energy power generation system according to an embodiment of the present application;

[0033] Figure 2 FIG. 2 is a schematic diagram of the connection relationship between a working medium assembly and a working medium circuit in the cold energy power generation system according to the embodiment of the present application, and a heat exchange assembly is shown in the diagram;

[0034] Figure 3 FIG. 3 is a schematic diagram of the connection relationship between a lubricating oil assembly and a lubricating oil circuit in the cold energy power generation system according to the embodiment of the present application, and a heat exchange assembly is shown in the diagram;

[0035] Figure 4 FIG. 4 is a structural schematic diagram of a cold energy power generation system according to another embodiment of the present application;

[0036] Figure 5 FIG. 5 is a structural schematic diagram of a heat exchange assembly in the cold energy power generation system according to the embodiment of the present application;

[0037] In the drawings: 1, working medium assembly; 2, power generation assembly; 3, lubricating oil assembly; 4, heat exchange assembly; 11, working medium pump; 12, evaporator; 13, expander; 14, condenser; 10, working medium circuit; 30, lubricating oil circuit; 41, working medium pipe; 42, lubricating oil pipe; 21, gear box; 22, generator; 31, lubricating oil tank; 32, lubricating oil pump; 411, working medium inlet; 412, working medium outlet; 421, lubricating oil inlet; 422, lubricating oil outlet; 121, heat source inlet; 122, heat source outlet; 141, cold source inlet; 142, cold source outlet. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort shall fall within the scope of the present application.

[0039] In the description of the present application, it should be understood that the terms "upper", "lower", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or component referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In the description of the present application, the meaning of "a plurality of" is two or more, at least one of which can be one, two or more, unless otherwise explicitly specified. The terms "first", "second", "third", and the like are only for the convenience of description and naming of parts or embodiments by numbering, and do not imply an important order between the parts or between the embodiments.

[0040] As a preamble of the embodiments of the present application, with the rapid development of LNG (liquefied natural gas) industry and air separation industry, the utilization of cold energy of LNG receiving stations and air separation devices has attracted more and more attention, and cold energy power generation is a relatively suitable utilization mode. At the same time, there are a large number of mechanical rotating equipment in the production process of LNG receiving stations, LNG filling stations, LNG satellite stations, air separation and other enterprises, which mostly use lubricating oil systems to achieve lubrication and cooling. Since LNG receiving stations, LNG filling stations, LNG satellite stations, air separation and other enterprises lack circulating cooling water, lubricating oil cooling mostly uses air coolers for cooling, and the fans of the air coolers also often use air coolers for cooling, which consumes additional electric energy, thereby increasing the self-use electric load and noise in the plant, and if a circulating cooling water system is newly built, it will bring a substantial increase in equipment and investment. In addition, many LNG receiving stations plan to generate power with cold energy, but due to the initial focus on the gasification function of LNG, the requirement for the superheat degree at the inlet side of the cold energy power generation expander under the power generation mode is not considered, which may cause insufficient heat load or liquid carry-over at the inlet of the expander, thereby affecting the service life and power generation efficiency of the system.

[0041] Therefore, the present application provides a cold energy power generation system and a heat exchange assembly to solve at least one of the above technical problems.

[0042] Please refer to Figures 1 to 4As shown, the cold energy power generation system in the embodiment of the present application comprises: a working medium assembly 1, a power generation assembly 2, a lubricating oil assembly 3 and a heat exchange assembly 4; wherein the working medium assembly 1 comprises a working medium pump 11, an evaporator 12, an expander 13 and a condenser 14 connected in series, the condenser 14 is connected with the working medium pump 11 and constitutes a working medium circuit 10; the power generation assembly 2 is connected with the expander 13, and the expander 13 can drive the power generation assembly 2 to generate power; the lubricating oil assembly 3 is connected with the expander 13 and the power generation assembly 2 and constitutes a lubricating oil circuit 30, which is used for cooling the expander 13 and the power generation assembly 2; the heat exchange assembly 4 comprises a working medium pipe 41 and a lubricating oil pipe 42 arranged adjacently, the working medium pipe 41 is connected in series on the working medium circuit 10 between the working medium pump 11 and the expander 13, the lubricating oil pipe 42 is communicated with the lubricating oil circuit 30, and the heat exchange assembly 4 is used for transferring heat in the lubricating oil to the working medium.

[0043] It should be understood that the evaporator 12 has a heat source inlet 121 and a heat source outlet 122, and the condenser 14 has a cold source inlet 141 and a cold source outlet (as shown). Figure 1 The heat source of the evaporator 12 can adopt various process fluids with waste heat such as hot water, steam, flue gas and the like in industrial production process, or natural resources such as solar energy, seawater, air and the like. The cold source of the condenser 14 can be one or more of LNG, liquid nitrogen, liquid oxygen, liquid helium, liquid argon, liquid air, liquid methane, liquid hydrogen and the like, if it is multiple, the condenser 14 corresponds to multiple. The working medium in the working medium circuit 10 can be single-component working medium such as methane, ethane, propane, ethylene, propylene and the like, or a mixture of multiple components.

[0044] Working principle: the heat source enters the evaporator 12 through the heat source inlet 121 and exchanges heat with the working medium in the working medium circuit 10, the working medium is heated into high-temperature and high-pressure gas and then enters the expander 13, which drives the expander 13 to rotate and further drives the power generation assembly 2 to generate power, the working medium after work becomes exhaust gas and enters the condenser 14 to exchange heat with the cold source, and is condensed into working medium liquid, which is pressurized by the working medium pump 11 and then enters the evaporator 12 again to exchange heat with the heat source in the evaporator 12, and the cycle is repeated. The lubricating oil in the lubricating oil circuit 30 can flow through the expander 13 and the power generation assembly 2 to cool the expander 13 and the power generation assembly 2, and the present application provides heat absorbed by the lubricating oil to the working medium, which can cool the lubricating oil on the one hand, and does not need to add additional cooling equipment for lubricating oil cooling, and on the other hand, the heat energy in the lubricating oil is utilized for power generation, which improves the power generation capacity and power generation efficiency of the cold energy power generation system.

[0045] The working fluid pipe 41 and the lubricating oil pipe 42 are arranged adjacent to each other. Specifically, they can be arranged as inner and outer pipes, with the lubricating oil pipe 42 passing through the working fluid pipe 41; or the working fluid pipe 41 and the lubricating oil pipe 42 are arranged in parallel, and heat transfer is carried out by direct contact between the pipes or by heat conduction through an intermediate medium.

[0046] Please see Figure 1 As shown, in some embodiments, the working fluid pipe 41 is connected in series with the working fluid circuit 10, and the working fluid pipe 41 is located in the pipeline between the evaporator 12 and the expander 13. It should be understood that after the working fluid is heated to a high-temperature, high-pressure gas, and before entering the expander 13, the heated working fluid gas enters the working fluid pipe 41 and is heated by lubricating oil before entering the expander 13. This increases the superheat of the working fluid, prevents liquid carryover at the inlet side of the expander 13, reduces the heat load on the evaporator 12, and extends the service life of the equipment. Please refer to... Figure 4 As shown, in some other embodiments, the working fluid pipe 41 is connected in series with the working fluid circuit 10, and the working fluid pipe 41 is located between the working fluid pump 11 and the evaporator 12. It should be understood that before the working fluid is condensed into a working fluid liquid and pressurized by the working fluid pump 11 into the evaporator 12, it can enter the working fluid pipe 41 to utilize the heat carried by the lubricating oil in the lubricating oil pipe 42 to heat the working fluid in the working fluid pipe 41, thereby preheating the working fluid, improving the working efficiency of the evaporator 12, and increasing energy utilization.

[0047] In some embodiments, the working fluid tube 41 is connected in series with the evaporator 12; or, the working fluid tube 41 is connected in parallel with the evaporator 12. It should be understood that the series connection allows the heat absorbed by the working fluid from the lubricating oil to be directly transferred to the working fluid in the evaporator 12, thereby increasing the superheat of the working fluid. The parallel connection facilitates maintenance of the heat exchange assembly 4.

[0048] In some embodiments, the power generation assembly 2 includes a generator 22, an expander 13 is directly connected to the generator 22, and a lubricating oil assembly 3 is connected to the expander 13 and the generator 22 respectively to form a lubricating oil circuit 30. Please refer to [link to previous text]. Figure 1 and Figure 3 As shown, in some embodiments, the power generation assembly 2 includes a gearbox 21 and a generator 22. The gearbox 21 is connected to the expander 13 and the generator 22 respectively. The lubricating oil assembly 3 connects the expander 13, the gearbox 21, and the generator 22 to form a lubricating oil circuit 30. Specifically, the lubricating oil flows simultaneously into the bearings and seals of the expander 13, the bearings of the gearbox 21, the bearings of the generator 22, and the cooler to remove heat from the aforementioned power generation or cooling equipment before flowing into the heat exchange assembly 4 to transfer the heat of the lubricating oil to the working fluid, causing the working fluid to overheat while the temperature of the lubricating oil decreases.

[0049] Please see Figure 1 ,Figure 3 and Figure 4 As shown, in some embodiments, the lubricating oil assembly 3 includes a connected lubricating oil tank 31 and a lubricating oil pump 32. The lubricating oil pump 32 is connected to the expander 13, and the lubricating oil tank 31 is connected to the power generation assembly 2. The lubricating oil pipe 42 is connected in series with the lubricating oil circuit 30, and the lubricating oil pipe 42 is located on the pipeline between the lubricating oil pump 32 and the expander 13. After the lubricating oil cools the expander 13 and the power generation assembly 2, it flows into the lubricating oil tank 31, and is then pressurized by the lubricating oil pump 32 and enters the heat exchange assembly 4 for heat exchange and cooling. When the heat is transferred to the working fluid, the lubricating oil, after cooling, re-enters the expander 13 to achieve cyclic cooling.

[0050] Please see Figure 5 As shown, in some embodiments, the lubricating oil pipe 42 has a spiral coiled structure, and the working fluid pipe 41 is sleeved outside the lubricating oil pipe 42. It should be understood that the spiral coiled structure of the lubricating oil pipe 42 can achieve a larger heat exchange area in a smaller space, thus saving space and avoiding excessive length of the lubricating oil pipe 42. At the same time, the portion of the lubricating oil pipe 42 arranged inside the working fluid pipe 41 achieves heat exchange, which can further reduce the heat dissipation in the lubricating oil, thereby further improving the heat exchange efficiency and ensuring that the heat in the lubricating oil can be absorbed and utilized by the working fluid, ultimately improving the power generation efficiency.

[0051] Please see Figure 5 As shown, in some embodiments, the working fluid pipe 41 has a working fluid inlet 411 and a working fluid outlet 412, and the lubricating oil pipe 42 has a lubricating oil inlet 421 and a lubricating oil outlet 422. The lubricating oil inlet 421 and the working fluid outlet 412 are located on the same side; and / or, the flow direction of the working fluid in the working fluid pipe 41 is opposite to the flow direction of the lubricating oil in the lubricating oil pipe 42. It should be understood that when the lubricating oil inlet and the working fluid outlet 412 are located on the same side, the working fluid temperature near the working fluid outlet 412 can be further increased. The opposite flow direction of the lubricating oil and the working fluid makes the temperature at the working fluid outlet end in the working fluid pipe 41 slightly higher than the temperature at the working fluid inlet end, ensuring the linear uniformity of the working fluid temperature in the working fluid pipe 41, so as to better utilize the heat absorbed by the lubricating oil for power generation.

[0052] In some embodiments, the condenser 14 is used to convert the working fluid exhaust gas into a liquid working fluid, and the condenser 14 is any one of a shell-and-tube heat exchanger, a plate-fin heat exchanger, or a coiled tube heat exchanger.

[0053] In some embodiments, the expander 13 is any one of an axial flow turbine expander 13, a centrifugal turbine expander 13, a screw expander 13, or a scroll expander 13.

[0054] In some embodiments, the lubricating oil circuit 30 is connected with other equipment cooled by the lubricating oil, such as compressors, expanders and the like from other equipment in the plant.

[0055] In some embodiments, the condenser 14 has multiple, and is connected in parallel between the expander 13 and the working medium pump 11, and the cold source of the condenser 14 includes one or more of liquid natural gas, liquid nitrogen, liquid oxygen, liquid helium, liquid argon, liquid air, liquid methane, and liquid hydrogen.

[0056] The application also discloses a heat exchange assembly 4, comprising working medium pipes 41 and lubricating oil pipes 42 arranged adjacently, the working medium pipes 41 being in communication with the working medium circuit 10 of the working medium assembly 1, and the lubricating oil pipes 42 being in communication with the lubricating oil circuit 30 of the lubricating oil assembly 3, the heat exchange assembly 4 being used for transferring heat in the lubricating oil to the working medium. In the above embodiments, the description of each embodiment is focused on, and the part not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0057] The application also discloses a cold energy power generation method based on the cold energy power generation system described in the above embodiments, the method comprising: obtaining the heat generation Q1 of the power generation assembly; increasing the input heat Q 输 of the cold energy power generation system based on the obtained heat generation Q1 of the power generation assembly; establishing a heat balance again, obtaining the heat generation Q2 of the power generation assembly; increasing the input heat Q 输 of the cold energy power generation system based on the obtained heat generation Q2 of the power generation assembly; establishing a heat balance again, obtaining the heat generation Q3 of the power generation assembly; repeating the above steps until the heat generation Q n , Q n+1 of the power generation assembly is obtained, and the following condition is met: |(Q n -Q n+1 ) / Q n |≤0.001; and calculating the power generation power and the power generation efficiency of the cold energy power generation system. It needs to be understood that the heat balance formula is as follows:

[0058] Q 输入 =Q 热源 +W 工质泵 ;

[0059] Q 输出 =Q LNG +W 发电组件 +Q 发电组件发热量 ;

[0060] Q 热源 +W 工质泵 =Q LNG +W 发电组件 +Q 发电组件发热量 ;

[0061] Wherein, Q 热源Q1 refers to the heat of the heat source, unit kW; W 工质泵 Q2 refers to the electric power of the working medium pump, unit kW; Q LNG Q3 refers to the heat of the cold source, unit kW; W 发电组件 Q4 refers to the electric power of the power generation assembly.

[0062] Q1 = Q 膨胀机发热1 + Q2 发电机发热1 + Q3 齿轮箱发热1 ;

[0063] Q1 is increased to Q 输入 , and the heat balance of the self-coupling LNG cold energy power generation system is established:

[0064] Q1 = Q 输入 + Q2 * + Q3 输出 * ;

[0065] Q1 = Q 热源 + Q2 工质泵 + Q3 LNG + Q4 发电组件2 , and Q4 is calculated;

[0066] The above steps are repeated, and the heat balance formula: Q 热源 + Q2 工质泵 + Q3 n = Q LNG + Q2 发电组件n+1 + Q3 n+1 is obtained to obtain the heat Q n and Q n+1 of the power generation assembly, and when it satisfies |(Q n -Q n+1 ) / Q n |≤0.001, the power generation power and the power generation efficiency of the cold energy power generation system are calculated; if not, Q 发电组件发热量 is continuously calculated until the above formula is satisfied. The power generation method of the application recovers the heat of the power generation assembly through the lubricating oil, and transmits the heat to the working medium through the heat transfer between the lubricating oil and the working medium for power generation, reduces the energy consumption, and improves the power generation efficiency and the power generation power of the cold energy power generation system.

[0067] The cold energy power generation system and the heat exchange assembly provided by the embodiments of the application are described in detail above, and specific examples are applied to explain the principles and implementation modes of the application. The above embodiment is only used to help understand the technical solutions and core ideas of the application; those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A method of generating electricity from cold energy, characterized by, The application is applied to a cold energy power generation system, and the cold energy power generation system comprises: A working medium assembly (1) comprising a working medium pump (11), an evaporator (12), an expander (13) and a condenser (14) connected in series, wherein the condenser (14) is connected with the working medium pump (11) and forms a working medium circuit (10); the evaporator (12) has a heat source inlet (121); A power generation assembly (2) connected with the expander (13), wherein the expander (13) can drive the power generation assembly (2) to generate power; A lubricating oil assembly (3) connected with the expander (13) and the power generation assembly (2) and forming a lubricating oil circuit (30) for cooling the expander (13) and the power generation assembly (2); A heat exchange assembly (4) comprising a working medium pipe (41) and a lubricating oil pipe (42) arranged adjacently, wherein the working medium pipe (41) is connected in series in the working medium circuit (10) between the working medium pump (11) and the expander (13), the lubricating oil pipe (42) is communicated with the lubricating oil circuit (30), and the heat exchange assembly (4) is used for transferring heat in the lubricating oil to the working medium; wherein the heat source enters the evaporator (12) through the heat source inlet (121) and exchanges heat with the working medium in the working medium circuit (10), the working medium is heated into high-temperature and high-pressure gas and then enters the expander (13), drives the expander (13) to rotate, and then drives the power generation assembly (2) to generate power, the working medium after work becomes exhaust gas and then enters the condenser (14) to exchange heat with a cold source, is condensed into working medium liquid, is pressurized by the working medium pump (11) again, enters the evaporator (12) again, exchanges heat with the heat source in the evaporator (12), and the cycle is repeated; The cold energy power generation method comprises: Obtaining heat Q1 generated by the power generation assembly (2); Based on the obtained heat generation amount Q1 of the power generation assembly (2) increasing to the input heat Q of the cold energy power generation system 输 In the process, a heat balance is established to obtain the heat generation amount Q2 of the power generation assembly (2); Based on the obtained heat generation amount Q2 of the power generation assembly (2) increasing to the input heat Q of the cold energy power generation system 输 In the middle, the heat balance is established again, and the heat generation amount Q3 of the power generation assembly (2) is obtained; The above steps are repeated until the heat quantity Q of the power generation assembly (2) is obtained n , n+1 , satisfies |(Q n -Q n+1 ) / Q n |≤0.001; Calculating power generation power and power generation efficiency of the cold energy power generation system.

2. The method of claim 1, wherein, The working medium pipe (41) is connected in series with the working medium circuit (10); The working medium pipe (41) is located on a pipeline between the evaporator (12) and the expander (13); or the working medium pipe (41) is located between the working medium pump (11) and the evaporator (12).

3. The method of claim 1, wherein, The power generation assembly (2) comprises a generator (22), the expander (13) is directly connected with the generator (22), and the lubricating oil assembly (3) is connected with the expander (13) and the generator (22) respectively and forms the lubricating oil circuit (30); Or, the power generation assembly (2) comprises a gear box (21) and a generator (22), the gear box (21) is connected with the expander (13) and the generator (22) respectively, and the lubricating oil assembly (3) is connected with the expander (13), the gear box (21) and the generator (22) respectively and forms the lubricating oil circuit (30).

4. The method of claim 1, wherein, The lubricating oil assembly (3) comprises a lubricating oil tank (31) and a lubricating oil pump (32) connected with each other, the lubricating oil pump (32) is connected with the expander (13), and the lubricating oil tank (31) is connected with the power generation assembly (2). The lubricating oil pipe (42) is in series with the lubricating oil circuit (30), and the lubricating oil pipe (42) is located on the pipeline between the lubricating oil pump (32) and the expander (13).

5. The method of claim 1, wherein, The lubricating oil pipe (42) is a spiral winding structure, and the working medium pipe (41) is sleeved outside the lubricating oil pipe (42).

6. The method of claim 5, wherein, The working medium pipe (41) has a working medium inlet (411) and a working medium outlet (412), the lubricating oil pipe (42) has a lubricating oil inlet (421) and a lubricating oil outlet (422), the lubricating oil inlet (421) and the working medium outlet (412) are located on the same side, and the working medium inlet (411) and the lubricating oil outlet (422) are located on the same side. And / or, the working medium flow direction in the working medium pipe (41) is opposite to the lubricating oil flow direction in the lubricating oil pipe (42).

7. The method of claim 1, wherein, The condenser (14) is used for converting working medium waste gas into liquid working medium, and the condenser (14) is any one of a tube-shell heat exchanger, a plate-fin heat exchanger, and a wound tube heat exchanger.

8. The method of claim 1, wherein, The expander (13) is any one of an axial flow turbine expander (13), a radial flow turbine expander (13), a centrifugal turbine expander (13), a screw expander (13), or a scroll expander (13).

9. The method of claim 1, wherein, The lubricating oil circuit (30) is externally connected with other equipment cooled by lubricating oil.

10. The method of claim 1, wherein, The condenser (14) has a plurality of condensers, and the plurality of condensers are connected in parallel between the expander (13) and the working medium pump (11), and the cold source of the condenser (14) includes one or more of liquid natural gas, liquid nitrogen, liquid oxygen, liquid helium, liquid argon, liquid air, liquid methane, and liquid hydrogen.

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