A mixed hydrocarbon working fluid single-stage Rankine cycle system platform

Abstract

The present invention relates to a mixed hydrocarbon working fluid single-stage Rankine cycle system platform, belonging to the technical field of LNG cold energy utilization. The circulation system platform is composed of a mixed working fluid proportioning unit (A), a mixed water heat exchange unit (B), a reheat exchange unit (C), and a cold mixed heat exchange unit (D). The present invention comprehensively arranges various working conditions such as a mixed working fluid conveying component for low-pressure liquid phase mixed working fluid pressurization, a mixed working fluid-water-heat exchange component, a water-mixed working fluid-heat exchange component, a mixed working fluid decompression component to decompress the high-pressure gas phase mixed working fluid, and a cold medium-mixed working fluid-heat exchange component to condense the low-pressure gas phase mixed working fluid into a low-pressure liquid phase mixed working fluid. Through appropriate switching and regulation, the cold energy utilization of the mixed working fluid and the circulation process of different types of heat exchangers can be simulated, thereby effectively monitoring the flow data of each heat exchanger structure and each connected pipeline in the system, and then analyzing the heat transfer performance of various working conditions based on the single-stage Rankine cycle system of mixed hydrocarbon working fluid.

Description

Technical Field

[0001] The invention relates to a low-temperature Rankine cycle system, in particular to a mixed hydrocarbon working fluid single-stage Rankine cycle system platform, belonging to the technical field of LNG cold energy utilization. Background Art

[0002] In the utilization of LNG cold energy, the cold energy power generation system can effectively recover most of the cold energy of the temperature gradient, and is not easily disturbed by external factors and is widely used. However, due to the large differences in the heat sources used in the low-temperature Rankine cycle of the LNG cold energy power generation system, a single working fluid cannot guarantee the optimal cold energy transfer during the LNG gasification process. The use of a mixed refrigerant cycle (MRC) can match the condensation curve of the circulating working fluid with the LNG evaporation curve, thereby narrowing the heat transfer temperature difference between the cold and hot media, reducing exergy losses, and improving the cycle efficiency. Thermodynamic analysis found that the efficiency of the LNG cold energy power generation system can increase by 1% -1.2% for every 1K reduction in the heat transfer temperature difference. However, under low temperature conditions, the phase change behavior of the mixed hydrocarbon working fluid is complex, and different phase change behaviors will seriously affect the heat transfer and flow performance of the heat exchanger.

[0003] So far, the research on the application of mixed working fluids and the cold energy utilization of different types of heat exchangers has mostly focused on separate theoretical calculations and has just started, lacking reliable experimental data and engineering data. There is a great need for a mixed hydrocarbon circulating working fluid cold energy utilization system platform with comprehensive experimental performance.

[0004] The technical solutions disclosed in the existing Chinese patent documents CN107138025A and CN1124841A for the application of circulating working fluid refrigerants are not suitable for the overall circulating working fluid cold energy utilization system; and the technical solutions disclosed in the Chinese patents CN103969073A and CN202675730U are limited in the type of heat exchangers and cannot build a mixed hydrocarbon circulating working fluid cold energy utilization system platform. Summary of the invention

[0005] The purpose of the present invention is to provide a mixed hydrocarbon working fluid single-stage Rankine cycle system platform that can simulate the cold energy utilization of mixed working fluids and the circulation process of different types of heat exchangers, thereby effectively monitoring the flow data of each heat exchanger structure and each connected pipeline in the system, thereby facilitating the study of mixed working fluid application and cold energy utilization of different types of heat exchangers.

[0006] In order to achieve the above-mentioned object, the basic technical scheme of the mixed hydrocarbon working fluid single-stage Rankine cycle system platform of the present invention is as follows: it includes a mixed working fluid proportioning unit (A), a mixed water heat exchange unit (B), a reheat exchange unit (C), and a cold mixing heat exchange unit (D);

[0007] The mixed working medium proportioning unit (A) comprises at least two storage tanks connected to the mixed working medium tank (4) through respective flow regulating valves and flow meters; the outlet and inlet of the mixed working medium tank serve as the output end and input end of the mixed working medium proportioning unit respectively;

[0008] The mixed water heat exchange unit (B) comprises a first heat exchange tube (5) and a second heat exchange tube (6) located in an intermediate medium housing (7); the output end of the mixed working medium proportioning unit is connected to the inlet of the first heat exchange tube via a pump (53), a first pressure transmitter (54), a fourth flow regulating valve (55), a fourth flow meter (56), and then via a first temperature transmitter (57); the outlet of the first heat exchange tube is connected to the working medium output end of the mixed water heat exchange unit via a second temperature transmitter (58); the circulating water output end is connected to the inlet of the second heat exchange tube via a third temperature transmitter (59); the outlet of the second heat exchange tube is discharged via a fourth temperature transmitter (60);

[0009] The reheat exchange unit (C) comprises a reboiler (8) and a first microchannel heat exchanger 9. The working medium output end of the mixed water heat exchange unit branches out a mixed working medium bypass (26) provided with a ninth on-off valve (72), which is further divided into a first branch (21) of a second mixed working medium inlet pipeline provided with a third on-off valve (66) and a second branch (23) of a second mixed working medium inlet pipeline provided with a fourth on-off valve (67), which are then respectively connected to the mixed working medium input ports of the reboiler and the first microchannel heat exchanger. The mixed working medium output ports of the reboiler and the first microchannel heat exchanger are respectively connected to the first branch (22) of the second mixed working medium outlet pipeline provided with a seventh on-off valve (70) and the second branch (24) of the second mixed working medium outlet pipeline provided with an eighth on-off valve (71) to the second mixed working medium outlet pipeline (25), and then connected to the mixed working medium bypass (26). The water source passes through a sixth temperature transmitter (73) as a mixed working medium output end of the reheat exchange unit; and after passing through a fifth flow regulating valve (61), a fifth temperature transmitter (63), and a fifth flow meter (62), the water source branches into a first branch (34) of a first inlet pipeline of circulating water provided with a first on-off valve (64) and a second branch (36) of a first inlet pipeline of circulating water provided with a second on-off valve (65), which are respectively connected to the circulating water inlets of the reboiler and the first microchannel heat exchanger; the circulating water outlets of the reboiler and the first microchannel heat exchanger respectively pass through a first branch (35) of a first outlet pipeline of circulating water provided with a fifth on-off valve (68) and a second branch (37) of a first outlet pipeline of circulating water provided with a sixth on-off valve (69), and are connected to form a circulating water output end of the reheat exchange unit, which is connected to the circulating water input end of the mixed water heat exchange unit (B);

[0010] The cold mixed heat exchange unit (D) comprises a condenser (11) and a second microchannel heat exchanger (12); the mixed working fluid output end of the reheat exchange unit branches into a first branch (28) of a third mixed working fluid inlet pipeline provided with a tenth on-off valve (77) and a second branch (30) of a third mixed working fluid inlet pipeline provided with an eleventh on-off valve (78), which are respectively connected to the mixed working fluid input ports of the condenser and the second microchannel heat exchanger; the mixed working fluid output ports of the condenser and the second microchannel heat exchanger are respectively connected through a first branch (29) of a third mixed working fluid outlet pipeline provided with a twelfth on-off valve (79) and a second branch (31) of a third mixed working fluid outlet pipeline provided with a thirteenth on-off valve (80), and are paralleled into a third mixed working fluid outlet pipeline (32) provided with the twelfth on-off valve (79) and a sampling point (92) as the mixed working fluid output end of the cold mixed heat exchange unit. The cold medium tank (10) is connected to the input end of the mixed working medium proportioning unit; and the cold medium inlet pipeline (41) provided with a third pressure transmitter (81), a sixth flow regulating valve (82), an eighth temperature transmitter (83) and a sixth flow meter (84) is branched into a first branch of the cold medium inlet pipeline (42) provided with a fourteenth on-off valve (85) and a second branch of the cold medium inlet pipeline (44) provided with a fifteenth on-off valve (86), which are respectively connected to the cold medium inlets of the condenser and the second microchannel heat exchanger; the cold medium outlets of the condenser and the second microchannel heat exchanger are respectively connected to the second branch of the cold medium outlet pipeline (45) provided with a seventeenth on-off valve (88) and the first branch of the cold medium outlet pipeline (43) provided with a sixteenth on-off valve (87), and after merging, are connected to the cold medium outlet end through a fourth pressure transmitter (89) and a ninth temperature transmitter (90).

[0011] A further improvement of the present invention is that the mixed working medium output end of the reheat exchange unit is connected to the mixed working medium input end of the cold mixing heat exchange unit through a pressure reducing valve (74), a second pressure transmitter (75) and a seventh temperature transmitter (76).

[0012] A further improvement of the present invention is that there are three storage tanks, the first storage tank is filled with methane, the second storage tank is filled with propane, and the third storage tank is filled with ethylene.

[0013] A further improvement of the present invention is that the intermediate medium shell is a closed circular cavity, with the first heat exchange tube and the second heat exchange tube respectively inserted and fixed at both ends, and liquid propane is filled in the cavity to immerse the second heat exchange tube. After the liquid propane exchanges heat with the circulating water in the second heat exchange tube, it evaporates into a gas phase and contacts the outside of the first heat exchange tube.

[0014] A further improvement of the present invention is that both ends of the cylindrical tank body of the reboiler are respectively provided with a hot medium inlet and a hot medium outlet connected through a group of heat exchange tubes in the tank body, and both sides of the tank body are respectively provided with a cold medium inlet and a cold medium outlet connected to the tank cavity.

[0015] A further improvement of the present invention is that the microchannel heat exchanger is composed of a group of microchannel flat tubes respectively connecting the hot medium inlet, the hot medium outlet and the cold medium inlet, the cold medium outlet.

[0016] A further improvement of the present invention is that both ends of the cylindrical tank body of the condenser are respectively provided with a hot medium inlet and a hot medium outlet connected through a group of heat exchange tubes in the tank body, and both sides of the tank body are respectively provided with a cold medium inlet and a cold medium outlet connected to the tank cavity.

[0017] The present invention comprehensively arranges various working conditions such as a mixed working fluid conveying component for pressurizing a low-pressure liquid-phase mixed working fluid, a mixed working fluid-water-heat exchange component, a water-mixed working fluid-heat exchange component, a mixed working fluid decompression component to decompress a high-pressure gas-phase mixed working fluid, and a cold medium-mixed working fluid-heat exchange component to condense a low-pressure gas-phase mixed working fluid into a low-pressure liquid-phase mixed working fluid. By appropriately switching and regulating, the cold energy utilization of the mixed working fluid and the circulation process of different types of heat exchangers can be simulated, thereby effectively monitoring the flow data of each heat exchanger structure and each connected pipeline in the system, and then analyzing the heat transfer performance of various working conditions based on a single-stage Rankine cycle system of a mixed hydrocarbon working fluid, and studying the influence of changes in the flow channel caused by different heat exchanger structures on the deviation of the mixed working fluid components. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of an embodiment of the present invention.

[0019] Figure 2 for Figure 1 Schematic diagram of the reboiler structure in the embodiment.

[0020] Figure 3 for Figure 1 Schematic diagram of the structure of the microchannel heat exchanger in the embodiment.

[0021] Figure 4 for Figure 1 Schematic diagram of the condenser structure in the embodiment.

[0022] Figure 1In: 1-first storage tank, 2-second storage tank, 3-third storage tank, 4-mixed working medium tank, 5-first heat exchange tube, 6-second heat exchange tube, 7-intermediate medium shell, 8-reboiler, 9-first microchannel heat exchanger, 10-cold medium tank, 11-condenser, 12-second microchannel heat exchanger, 13-first proportioning pipeline, 14-second proportioning pipeline, 15-third proportioning pipeline, 16-pipeline before pump, 17-pipeline after pump, 18-first inlet pipeline of mixed working medium, 19-first outlet pipeline of mixed working medium, 20-second inlet pipeline of mixed working medium, 21-first branch of second inlet pipeline of mixed working medium, 22-first branch of second outlet pipeline of mixed working medium, 23-second inlet pipeline of mixed working medium, 24-mixed working medium The second branch of the second outlet pipeline of the working medium, 25-the second outlet pipeline of the mixed working medium, 26-the bypass of the mixed working medium, 27-the third inlet pipeline of the mixed working medium, 28-the first branch of the third inlet pipeline of the mixed working medium, 29-the first branch of the third outlet pipeline of the mixed working medium, 30-the second branch of the third inlet pipeline of the mixed working medium, 31-the second branch of the third outlet pipeline of the mixed working medium, 32-the third outlet pipeline of the mixed working medium, 33-the first inlet pipeline of the circulating water, 34-the first branch of the first inlet pipeline of the circulating water, 35-the first branch of the first outlet pipeline of the circulating water, 36-the second branch of the first inlet pipeline of the circulating water, 37-the second branch of the first outlet pipeline of the circulating water, 38-the second inlet pipeline of the circulating water, 39-the second outlet pipeline of the circulating water, 40-the cold water Pipeline after the medium tank, 41-cold medium inlet pipeline, 42-first branch of the cold medium inlet pipeline, 43-first branch of the cold medium outlet pipeline, 44-second branch of the cold medium inlet pipeline, 45-second branch of the cold medium outlet pipeline, 46-cold medium outlet pipeline, 47-first flow regulating valve, 48-second flow regulating valve, 49-third flow regulating valve, 50-first flow meter, 51-second flow meter, 52-third flow meter, 53-pump, 54-first pressure transmitter, 55-fourth flow regulating valve, 56-fourth flow meter, 57-first temperature transmitter, 58-second temperature transmitter, 59-third temperature transmitter, 60-fourth temperature transmitter, 61-fifth flow regulating valve, 62-fifth flow meter , 63-fifth temperature transmitter, 64-first hand valve, 65-second hand valve, 66-third hand valve, 67-fourth hand valve, 68-fifth hand valve, 69-sixth hand valve, 70-seventh hand valve, 71-eighth hand valve, 72-ninth hand valve, 73-sixth temperature transmitter, 74-pressure reducing valve, 75-second pressure transmitter, 76-seventh temperature transmitter, 77-tenth hand valve, 78-eleventh hand valve, 79-twelfth hand valve, 80-thirteenth hand valve, 81-third pressure transmitter, 82-sixth flow regulating valve, 83-eighth temperature transmitter, 84-sixth flow meter, 85-fourteenth hand valve, 86-fifteenth hand valve, 87-sixteenth hand valve, 88-seventeenth hand valve, 89-fourth pressure transmitter,90-9th temperature transmitter, 91-10th temperature transmitter, 92-sampling point. DETAILED DESCRIPTION

[0023] The mixed hydrocarbon working medium single-stage Rankine cycle system platform of this embodiment is as follows Figure 1 As shown, it includes a mixed working fluid proportioning unit A, a mixed water heat exchange unit B, a reheat exchange unit C, and a cold mixing heat exchange unit D.

[0024] The composition of each unit is:

[0025] The mixed working medium proportioning unit A includes a first storage tank 1, a second storage tank 2, and a third storage tank 3 leading to the mixed working medium tank 4 through the first flow regulating valve 47 and the first flow meter 50 in the first proportioning pipeline 13, the second flow regulating valve 48 and the second flow meter 51 in the second proportioning pipeline 14, and the third flow regulating valve 49 and the third flow meter 52 in the third proportioning pipeline 15. The first storage tank 1 is filled with methane, the second storage tank 2 is filled with propane, and the third storage tank 3 is filled with ethylene. Therefore, the quantitative proportion of the three media can be regulated by each flow regulating valve and flow meter, respectively, to achieve a mixed working medium with a predetermined composition proportion in the mixed working medium tank 4. The outlet of the mixed working medium tank 4 is used as the output end of the mixed working medium proportioning unit A through the pre-pump pipeline 16, and the inlet of the mixed working medium tank 4 is used as the input end of the mixed working medium proportioning unit A.

[0026] The mixed water heat exchange unit B includes a first heat exchange tube 5 and a second heat exchange tube 6 located in the intermediate medium shell 7. The first mixed working medium inlet pipeline 18 serving as the working medium input end of the mixed water heat exchange unit is connected to the inlet of the first heat exchange tube 5 via the first temperature transmitter 57, so that the mixed working medium flows into the tube of the first heat exchange tube 5; the outlet of the first heat exchange tube 5 is connected to the first mixed working medium outlet pipeline 19 via the second temperature transmitter 58 as the working medium output end of the mixed water heat exchange unit; the second circulating water inlet pipeline 38 serves as the water input end of the mixed water heat exchange unit, is connected to the inlet of the second heat exchange tube 6 via the third temperature transmitter 59, and the outlet of the second heat exchange tube 6 is discharged from the second circulating water outlet pipeline 39 via the fourth temperature transmitter 60. More specifically, the intermediate medium shell 7 is a closed circular cavity (its specific structure can be found in the Chinese patent document with application number 202010098715.0), with the first heat exchange tube 5 and the second heat exchange tube 6 inserted and fixed at both ends respectively, and the cavity is filled with liquid propane to immerse the second heat exchange tube 6. After the liquid propane exchanges heat with the circulating water in the heat exchange tube 6, it evaporates into a gas phase and contacts the outside of the first heat exchange tube 5. Since the first heat exchange tube 5 contains a low-temperature mixed working fluid, the gaseous propane will be re-condensed into a liquid phase and return to the bottom of the intermediate medium shell 7 cavity, realizing indirect heat exchange between the circulating water and the mixed working fluid, heating the low-temperature mixed working fluid to a specified temperature, and avoiding the situation where the circulating water freezes and cannot exchange heat due to direct heat exchange between the circulating water and the mixed working fluid.

[0027] The reheat exchange unit C includes a reboiler 8 and a first microchannel heat exchanger 9. The mixed working medium second inlet pipeline 20 as the mixed working medium input end of the reheat exchange unit C branches out a mixed working medium bypass 26 provided with a ninth hand valve 72, which is further divided into a first branch 21 of the mixed working medium second inlet pipeline provided with a third hand valve 66 and a second branch 23 of the mixed working medium second inlet pipeline provided with a fourth hand valve 67, which are respectively connected to the mixed working medium input ports of the reboiler 8 and the first microchannel heat exchanger 9. The mixed working medium output ports of the reboiler 8 and the first microchannel heat exchanger 9 are respectively connected to the first branch 22 of the mixed working medium second outlet pipeline provided with a seventh hand valve 70 and the second branch 24 of the mixed working medium second outlet pipeline provided with an eighth hand valve 71, and then connected to the mixed working medium second outlet pipeline 25, and then connected to the mixed working medium. The working medium bypass 26 is connected to the mixed working medium output end of the reheat exchange unit C through the sixth temperature transmitter 73; in addition, the water source is branched into the first branch 34 of the first inlet pipeline of circulating water with a first hand valve 64 and the second branch 36 of the first inlet pipeline of circulating water with a second hand valve 65 after passing through the fifth flow regulating valve 61, the fifth temperature transmitter 63 and the fifth flow meter 62 of the first inlet pipeline of circulating water 33, respectively connected to the circulating water inlet of the reboiler 8 and the first microchannel heat exchanger 9, and the circulating water outlets of the reboiler 8 and the first microchannel heat exchanger 9 are connected to the first branch 35 of the first outlet pipeline of circulating water with a fifth hand valve 68 and the second branch 37 of the first outlet pipeline of circulating water with a sixth hand valve 69, respectively, and connected to the circulating water output end of the reheat exchange unit C. The reheat exchange unit C can realize the heat exchange between the low-temperature mixed working medium and water, and reheat the mixed working medium through conventional circulating water to completely evaporate the mixed working medium into gas phase.

[0028] The structure of the reboiler 8 in this embodiment is as follows Figure 2 As shown, the two ends of the cylindrical tank body are respectively provided with a hot medium inlet Hi and a hot medium outlet Ho connected through a group of heat exchange tubes 8-1 in the tank body, and the two sides of the tank body are respectively provided with a cold medium inlet Ci and a cold medium outlet Co connected to the tank cavity 8-2. The structure of the first microchannel heat exchanger 9 is as shown in FIG. Figure 3 As shown, it is composed of a group of microchannel flat tubes 9-1 respectively connecting the hot medium inlet Hi, the hot medium outlet Ho and the cold medium inlet Ci, and the cold medium outlet Co.

[0029] The cold mixing heat exchange unit D comprises a condenser 11 and a second microchannel heat exchanger 12 (whose structure is the same as 9). The mixed working medium third inlet pipeline 27 as the mixed working medium input end of the cold mixing heat exchange unit D is branched into a first branch 28 of the mixed working medium third inlet pipeline provided with a tenth hand valve 77 and a second branch 30 of the mixed working medium third inlet pipeline provided with an eleventh hand valve 78, which are respectively connected to the mixed working medium input ports of the condenser 11 and the second microchannel heat exchanger 12. The mixed working medium output ports of the condenser 11 and the second microchannel heat exchanger 12 are respectively connected through a first branch 29 of the mixed working medium third outlet pipeline provided with a tenth hand valve 79 and a second branch 31 of the mixed working medium third outlet pipeline provided with a thirteenth hand valve 80, and are connected to form a mixed working medium third outlet pipeline 32 provided with a tenth hand valve 79 and a sampling point 92 as the mixed working medium output end of the cold mixing heat exchange unit D; and the cold medium tank 10 is provided with The pipeline 40 after the cold medium tank having the third pressure transmitter 81, the sixth flow regulating valve 82, the eighth temperature transmitter 83 and the sixth flow meter 84 is connected to the cold medium inlet pipeline 41 as the cold medium input end of the cold mixing heat exchange unit D, and then the cold medium inlet pipeline 41 is branched into a first branch 42 of the cold medium inlet pipeline provided with a fourteenth manual valve 85 and a second branch 44 of the cold medium inlet pipeline provided with a fifteenth manual valve 86, which are respectively connected to the cold medium inlets of the condenser 11 and the second microchannel heat exchanger 12. The cold medium outlets of the condenser 11 and the second microchannel heat exchanger 12 are respectively connected through the second branch 45 of the cold medium outlet pipeline provided with a seventeenth manual valve 88 and the first branch 43 of the cold medium outlet pipeline provided with a sixteenth manual valve 87, and after merging, they are connected to the cold medium outlet end through the cold medium outlet pipeline 46 provided with a fourth pressure transmitter 89 and a ninth temperature transmitter 90, so that the cold medium after heat exchange is discharged. The cold-mix heat exchange unit D can realize heat exchange between the mixed working fluid and the cold medium, and condense the mixed working fluid from the gas phase to the liquid phase through the cold medium.

[0030] The structure of the condenser 11 in this embodiment is as follows Figure 4 As shown, the two ends of the cylindrical tank body are respectively provided with a hot medium inlet Hi and a hot medium outlet Ho connected through a group of heat exchange tubes 11-1 in the tank body, and the two sides of the tank body are respectively provided with a cold medium inlet Ci and a cold medium outlet Co connected to the tank cavity 11-2.

[0031] The connection relationship between each unit is:

[0032] The pump front pipeline 16, which serves as the output end of the mixed working medium proportioning unit A, is connected to the working medium input end of the mixed water heat exchange unit B through the pump 53 and the first pressure transmitter 54, the fourth flow regulating valve 55, and the fourth flow meter 56 of the pump rear pipeline 17, so that the mixed working medium that has been proportioned in the mixed working medium tank 4 is pressurized and circulated quantitatively. The pump 53 provides fluid conveying power for the mixed working medium to ensure that the displayed pressure of the fluid after the pump on the first pressure transmitter 54 reaches the design pressure. The fourth flow regulating valve 55 and the fourth flow meter 56 serve as flow control elements to realize the flow control of the mixed working medium.

[0033] The first outlet pipeline 19 of the mixed working medium at the working medium output end of the mixed water heat exchange unit B is connected to the second inlet pipeline 20 of the mixed working medium at the mixed working medium input end of the reheat exchange unit C; the second inlet pipeline 38 of the circulating water at the water input end of the mixed water heat exchange unit B is connected to the circulating water output end of the reheat exchange unit C.

[0034] The mixed working medium output end of the reheat exchange unit C is connected to the mixed working medium third inlet pipeline 27 serving as the mixed working medium input end of the cold mixing heat exchange unit D through a pressure reducing valve 74, a second pressure transmitter 75 and a seventh temperature transmitter 76.

[0035] The mixed medium third outlet pipeline 32 as the mixed medium output end of the cold mixing heat exchange unit D is connected to the inlet of the mixed medium tank 4 as the input end of the mixed medium proportioning unit A, so that the mixed medium condensed into liquid phase returns to the mixed medium proportioning tank 4.

[0036] The mixed working fluid proportioning unit A, the mixed water heat exchange unit B, the reheat exchange unit C, and the cold mixed heat exchange unit D constitute a circulation system. When working, first confirm that all manual valves and flow control valves in the system are closed, and confirm that all equipment, pipes, and instruments in the system have no leakage. The specific work flow is as follows:

[0037] 1. Mixed working fluid proportioning: achieved through the operation of the mixed working fluid proportioning component: 1) filling sufficient amounts of three liquid hydrocarbon media, namely methane, propane and ethylene, into the storage tanks 1 / 2 / 3 in sequence; 2) simultaneously filling the mixed working fluid proportioning tank 4 with specified amounts of methane, propane and ethylene by adjusting the flow regulating valves 47 / 48 / 49, so that the total weight of the mixed working fluid in the mixed working fluid proportioning tank 4 is 200 kg;

[0038] 2. Filling the intermediate medium: Fill the intermediate medium shell 7 with propane, and make the propane liquid level higher than the height of the second type heat exchange tube 6 to be qualified;

[0039] 3. Cold source filling: fill the cold medium tank 10 with sufficient liquid nitrogen;

[0040] 4. Confirm the specific heat exchanger types in the reheat exchange unit C and the cold mixed heat exchange unit D. If the reheat exchange unit is to use water-mixed working fluid-reboiler, open manual valves 64 / 66 / 68 / 70 in sequence; if the cold mixed heat exchange unit D is to use cold medium-mixed working fluid-condenser, open manual valves 65 / 67 / 69 / 71 in sequence;

[0041] 5. Circulating water is introduced, and the circulating water reaches the specified flow rate through the flow regulating valve 61 and the flow meter 62. The circulating water passes through the pipes 34 / 35 / 38 / 39, flows through the reboiler 8 and the second heat exchange pipe 6 in sequence, and is discharged out of the boundary through the pipeline 39;

[0042] 6. Liquid nitrogen is introduced as a cold medium, and the liquid nitrogen reaches a specified flow rate through the flow regulating valve 82 and the flow meter 84. The liquid nitrogen passes through the pipes 41 / / 42 / 43 / 44 / 45, flows through the condenser 11 and is discharged out of the boundary through the pipeline 46;

[0043] 7. Start the pump 53 and make the mixed working medium reach the specified flow rate through the flow regulating valve 55 and the flow meter 56;

[0044] 8. Record system test data after achieving stability;

[0045] 9. Sampling the mixed working fluid at sampling point 92, and performing component analysis on the sample;

[0046] 10. Repeat test steps 6 to 10 after switching the heat exchange unit or adjusting the mixed working fluid ratio.

[0047] Compared with the prior art, this embodiment has the following significant features and beneficial effects:

[0048] 1) It is capable of performing dynamic system performance analysis on a single-stage Rankine cycle system based on mixed hydrocarbon working fluids - a mixed working fluid proportioning component is set in the circulation process to provide the required mixed working fluid for the circulation system, a mixed working fluid delivery component is set to pressurize the low-pressure liquid phase mixed working fluid, a mixed working fluid-water-heat exchange component and a water-mixed working fluid-heat exchange component are set to evaporate the mixed working fluid from the high-pressure liquid phase to the high-pressure gas phase, a mixed working fluid decompression component is set to decompress the high-pressure gas phase mixed working fluid, and a cold medium-mixed working fluid-heat exchange component is set to condense the low-pressure gas phase mixed working fluid into a low-pressure liquid phase mixed working fluid, forming a multifunctional circulation system;

[0049] 2) A two-stage evaporation of a mixed working medium-water-heat exchange component and a water-mixed working medium-reboiler component is set. The mixed working medium-water-heat exchange component as the first-stage evaporation unit adopts an intermediate medium type heat exchange structure, so that the normal temperature circulating water heats the low-temperature mixed medium below -100°C without freezing. The water-mixed working medium-reboiler component as the second-stage evaporation unit completely evaporates and gasifies the mixed working medium. The two-stage evaporation makes the single-stage circulation of the mixed working medium possible;

[0050] 3) The heat exchanger type can be switched, so that the influence of the change of the flow channel caused by different heat exchanger structures on the deviation of the mixed working fluid components can be studied. The mixed working fluid-water-heat exchange component includes the mixed working fluid-water-reboiler component and the mixed working fluid-water-microchannel heat exchanger component, which can be switched and used as needed; the cold medium-mixed working fluid-heat exchange component includes the cold medium-mixed working fluid-condenser component and the cold medium-mixed working fluid-microchannel heat exchanger component, which can also be switched and used as needed;

[0051] 4) The measurement unit, flow control unit and valve switching unit involved in the mixed hydrocarbon working fluid single-stage Rankine cycle system platform can effectively monitor and control the state parameters of the circulating working fluid in the whole process and each sub-process in real time, can realize the switching of different types of heat exchange units, and can also realize real-time control and subsequent measurement of the cold energy utilization unit, and effectively judge the cold energy utilization effect in the subsequent process.

[0052] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A mixed hydrocarbon working fluid single-stage Rankine cycle system platform, characterized by: It includes a mixed working fluid proportioning unit (A), a mixed water heat exchange unit (B), a reheat exchange unit (C), and a cold mixed heat exchange unit (D); The mixed working medium proportioning unit (A) comprises at least two storage tanks connected to the mixed working medium tank (4) through respective flow regulating valves and flow meters; the outlet and inlet of the mixed working medium tank serve as the output end and input end of the mixed working medium proportioning unit respectively; The mixed water heat exchange unit (B) comprises a first heat exchange tube (5) and a second heat exchange tube (6) located in an intermediate medium housing (7); the output end of the mixed working medium proportioning unit is connected to the inlet of the first heat exchange tube via a first temperature transmitter (57), and the outlet of the first heat exchange tube is connected to the working medium output end of the mixed water heat exchange unit via a second temperature transmitter (58); the circulating water output end is connected to the inlet of the second heat exchange tube via a third temperature transmitter (59), and the outlet of the second heat exchange tube is discharged via a fourth temperature transmitter (60); The reheat exchange unit (C) comprises a reboiler (8) and a first microchannel heat exchanger (9); a mixed working medium bypass (26) provided with a ninth on-off valve (72) is branched from the working medium output end of the mixed water heat exchange unit, which is further divided into a first branch (21) of a second mixed working medium inlet pipeline provided with a third on-off valve (66) and a second branch (23) of a second mixed working medium inlet pipeline provided with a fourth on-off valve (67), which are then respectively connected to the mixed working medium input ports of the reboiler and the first microchannel heat exchanger; the mixed working medium output ports of the reboiler and the first microchannel heat exchanger are respectively connected to the first branch (22) of the second mixed working medium outlet pipeline provided with a seventh on-off valve (70) and the second branch (24) of the second mixed working medium outlet pipeline provided with an eighth on-off valve (71) to the second mixed working medium outlet pipeline (25), and then connected to the mixed working medium outlet pipeline (25) of the first microchannel heat exchanger. The mixed working medium bypass (26) is connected to a mixed working medium output end of the reheat exchange unit through a sixth temperature transmitter (73); and the water source is branched into a first branch (34) of a first inlet pipeline of circulating water provided with a first on-off valve (64) and a second branch (36) of a first inlet pipeline of circulating water provided with a second on-off valve (65) after passing through a fifth flow regulating valve (61), a fifth temperature transmitter (63) and a fifth flow meter (62), which are respectively connected to the circulating water inlets of the reboiler and the first microchannel heat exchanger; the circulating water outlets of the reboiler and the first microchannel heat exchanger are respectively connected to a first branch (35) of a first outlet pipeline of circulating water provided with a fifth on-off valve (68) and a second branch (37) of a first outlet pipeline of circulating water provided with a sixth on-off valve (69), and connected to form a circulating water output end of the reheat exchange unit; The cold mixed heat exchange unit (D) comprises a condenser (11) and a second microchannel heat exchanger (12); the mixed working fluid output end of the reheat exchange unit branches into a first branch (28) of a third mixed working fluid inlet pipeline provided with a tenth on-off valve (77) and a second branch (30) of a third mixed working fluid inlet pipeline provided with an eleventh on-off valve (78), which are respectively connected to the mixed working fluid input ports of the condenser and the second microchannel heat exchanger; the mixed working fluid output ports of the condenser and the second microchannel heat exchanger are respectively connected through a first branch (29) of a third mixed working fluid outlet pipeline provided with a twelfth on-off valve (79) and a second branch (31) of a third mixed working fluid outlet pipeline provided with a thirteenth on-off valve (80), and are paralleled into a third mixed working fluid outlet pipeline (32) provided with the twelfth on-off valve (79) and a sampling point (92) as the mixed working fluid output end of the cold mixed heat exchange unit. The cold medium tank (10) is connected to the input end of the mixed working medium proportioning unit; and the cold medium inlet pipeline (41) provided with a third pressure transmitter (81), a sixth flow regulating valve (82), an eighth temperature transmitter (83) and a sixth flow meter (84) is branched into a first branch of the cold medium inlet pipeline (42) provided with a fourteenth on-off valve (85) and a second branch of the cold medium inlet pipeline (44) provided with a fifteenth on-off valve (86), which are respectively connected to the cold medium inlets of the condenser and the second microchannel heat exchanger; the cold medium outlets of the condenser and the second microchannel heat exchanger are respectively connected to the second branch of the cold medium outlet pipeline (45) provided with a seventeenth on-off valve (88) and the first branch of the cold medium outlet pipeline (43) provided with a sixteenth on-off valve (87), and after merging, are connected to the cold medium outlet end through a fourth pressure transmitter (89) and a ninth temperature transmitter (90).

2. The mixed hydrocarbon working fluid single-stage Rankine cycle system platform according to claim 1, characterized in that: The mixed working medium output end of the reheat exchange unit is connected to the mixed working medium input end of the cold mixing heat exchange unit via a pressure reducing valve (74), a second pressure transmitter (75) and a seventh temperature transmitter (76).

3. The mixed hydrocarbon working fluid single-stage Rankine cycle system platform according to claim 1, characterized in that: There are three storage tanks, the first storage tank is filled with methane, the second storage tank is filled with propane, and the third storage tank is filled with ethylene.

4. The mixed hydrocarbon working fluid single-stage Rankine cycle system platform according to claim 1, characterized in that: The intermediate medium shell is a closed circular cavity, with the first heat exchange tube and the second heat exchange tube respectively inserted and fixed at both ends. Liquid propane is filled in the cavity to immerse the second heat exchange tube. The liquid propane exchanges heat with the circulating water in the second heat exchange tube and then evaporates into a gas phase to contact the outside of the first heat exchange tube.

5. The mixed hydrocarbon working fluid single-stage Rankine cycle system platform according to claim 1, characterized in that: The two ends of the cylindrical tank body of the reboiler are respectively provided with a hot medium inlet and a hot medium outlet connected through a group of heat exchange tubes in the tank body, and the two sides of the tank body are respectively provided with a cold medium inlet and a cold medium outlet connected to the tank cavity.

6. The mixed hydrocarbon working fluid single-stage Rankine cycle system platform according to claim 1, characterized in that: The first and second microchannel heat exchangers are composed of a group of microchannel flat tubes respectively connecting the hot medium inlet, the hot medium outlet and the cold medium inlet, the cold medium outlet.

7. The mixed hydrocarbon working fluid single-stage Rankine cycle system platform according to claim 1, characterized in that: The two ends of the cylindrical tank body of the condenser are respectively provided with a hot medium inlet and a hot medium outlet connected through a group of heat exchange pipes in the tank body, and the two sides of the tank body are respectively provided with a cold medium inlet and a cold medium outlet connected with the tank cavity.

Images