Waste heat utilization system and method for deep sea spiral axial flow type oil-gas multiphase pump motor

Abstract

The invention provides a deep sea spiral axial flow type oil-gas mixed transportation pump motor waste heat utilization system and method, and aims to solve the double challenges of motor heat dissipation and pipeline hydrate flow guarantee in the deep sea oil-gas mixed transportation process. The system comprises a tubular spiral homogenizer, a heat exchanger, a pressure compensator, a liquid film thickness measurer, a spiral axial flow type oil-gas multiphase pump body, a gas-liquid separator, a bypass pipe and a controller. The heat of the motor cooling liquid is transferred to the low-temperature fluid in the mixed transportation pipeline through the heat exchanger, and the dual effects of motor cooling and fluid heating are achieved. The controller dynamically adjusts the working mode of the heat exchanger according to the inflow condition, the motor temperature and the outflow condition, and the heat exchange efficiency is optimized. When the heating is sufficient, the use of a hydrate thermodynamic inhibitor can be obviously reduced or eliminated, and the cost is saved. According to the system, efficient recycling of the waste heat of the motor is achieved, the hydrate generation risk is reduced, and the economical efficiency and safety of the deep sea oil-gas mixed transportation system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat utilization, and in particular to a system and method for utilizing the waste heat of a motor of a deep-sea screw axial oil-gas mixed transportation pump. Background Technique

[0002] China's ability to explore and develop deep-sea oil and gas resources has been continuously improving. A stable subsea oil-gas mixed transportation system is an important part of the deep-sea oil-gas underwater production system, facing multiple challenges such as pressurization and hydrate flow assurance. In the middle and late stages of deep-sea oil and gas production, the reservoir faces the problem of insufficient energy. The oil and gas in the mixed transportation pipeline need to rely on a deep-sea screw axial oil-gas mixed transportation pump for pressurization before they can be transported to an offshore platform. The deep-sea screw axial oil-gas mixed transportation pump consists of a pump body and a motor. The hydraulic and thermal coupling conditions between the mixed transportation pump and the mixed transportation pipeline determine whether multiple challenges such as pressurization and hydrate flow assurance can be effectively addressed.

[0003] To achieve the hydraulic coupling regulation between the pump body of the deep-sea screw axial oil-gas mixed transportation pump and the mixed transportation pipeline, Chinese Patent No. CN 118031116A discloses a transportation system and method for a deep-sea screw axial oil-gas mixed transportation pump. In this patent, a pre-pump homogenizer is invented to homogenize the incoming gas-liquid. The higher the pressure and the lower the temperature, the easier it is for hydrates to form. Therefore, the pressurization of the mixed transportation fluid by the deep-sea screw axial oil-gas mixed transportation pump leads to an increase in the pressure of the oil-gas-water multiphase flow system in the narrow flow channels inside the pump and the downstream mixed transportation pipeline, and the risk of hydrate flow assurance faced increases sharply. Currently, the mainstream solution to reduce the risk of hydrate flow assurance is to inject a certain concentration of hydrate thermodynamic inhibitor, so as to increase the pressure required for hydrate formation to inhibit the formation of hydrates. The required concentration of the hydrate thermodynamic inhibitor increases with the increase in the pump pressurization degree, resulting in an increase in the economic cost of hydrate prevention.

[0004] For the motor, the greater the water depth of deep-sea oil and gas, the higher the requirement for the pressurization ability of the mixed transportation pump, which leads to a significant increase in the power of the motor used in the mixed transportation pump, often in the megawatt level. During the continuous operation of the deep-sea screw axial oil-gas mixed transportation pump, when the current passes through the winding and the iron core, resistance loss and magnetoresistance loss are inevitably generated, resulting in a certain proportion of electrical energy loss and generating a large amount of heat. To ensure the stable and normal operation of the motor, a reliable cooling system must be equipped to ensure that the motor temperature is maintained within a reasonable and stable range. Currently, the motor exchanges heat with seawater through coils wound around the outside of the motor. The heat transfer method is motor - coolant - cooling coil - seawater, resulting in heat loss.

[0005] The deep-sea screw axial-flow oil-gas multiphase pump simultaneously faces problems such as high risks in ensuring the flow of hydrates in the complex flow channels inside the pump and in the pipeline downstream of the pump, and large heat dissipation of megawatt-level high-power motors. In the existing technical solutions, the solutions to these two types of problems are designed separately, lacking an effective way to transfer heat from the motor to the multiphase system in the flow channel, thus failing to meet the requirements of heating the oil and gas to prevent hydrates and cooling the motor to lower the temperature in a coordinated manner.

[0006] Therefore, on the premise of ensuring sufficient cooling of the motor of the deep-sea screw axial-flow oil-gas multiphase pump, how to recycle the waste heat of the motor to increase the temperature of the oil and gas, achieve the thermal coupling between the motor and the multiphase pipeline of the deep-sea screw axial-flow oil-gas multiphase pump, and ensure the economic and efficient operation of the deep-sea screw axial-flow oil-gas multiphase pump is a difficult problem to be solved in this industry currently. Summary of the Invention

[0007] In view of the above technical deficiencies, the purpose of the present invention is to provide a system and method for utilizing the waste heat of the motor of a deep-sea screw axial-flow oil-gas multiphase pump, which can cool the motor while increasing the temperature of the fluid inside the multiphase pipeline, thereby reducing the risk of hydrate flow assurance.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A system for utilizing the waste heat of the motor of a deep-sea screw axial-flow oil-gas multiphase pump includes:

[0010] A tubular screw homogenizer, configured with a first inlet, a second inlet, and a first outlet; the first inlet is connected to the upstream equipment;

[0011] A heat exchanger, configured with a cold fluid inlet, a cold fluid outlet, a first hot fluid outlet, a second hot fluid outlet, a first hot fluid inlet, and a second hot fluid inlet; the first hot fluid outlet is connected to the second hot fluid inlet; the cold fluid outlet is connected between the upstream equipment and the first inlet of the tubular screw homogenizer;

[0012] A pressure compensator, one end of which is connected to the first hot fluid inlet;

[0013] A liquid film thickness measurer, connected to the tubular screw homogenizer;

[0014] A screw axial-flow oil-gas multiphase pump, including a screw axial-flow oil-gas multiphase pump body and a screw axial-flow oil-gas multiphase pump motor connected in transmission; the screw axial-flow oil-gas multiphase pump body is configured with a first input port and a first output port; the screw axial-flow oil-gas multiphase pump motor is configured with a coolant inlet and a coolant outlet; the first input port is connected to the first outlet of the tubular screw homogenizer; the coolant inlet is connected to the second hot fluid outlet and the first hot fluid outlet; the coolant outlet is connected to the other end of the pressure compensator;

[0015] A gas-liquid separator is configured with a first input end, a first output end, and a second output end; the first input end is connected to the first output port of the screw axial-flow oil-gas mixed transportation pump body; the first output end is connected to the cold fluid inlet and the second inlet of the tubular screw homogenizer; the second output end is connected to an offshore platform;

[0016] A first bypass pipe has one end connected to the pipeline between the upstream device and the tubular screw homogenizer, and the other end connected to the pipeline between the gas-liquid separator and the offshore platform;

[0017] A second bypass pipe has one end connected to the pipeline between the upstream device and the tubular screw homogenizer, and the other end connected to the pipeline between the tubular screw homogenizer and the screw axial-flow oil-gas mixed transportation pump body;

[0018] A controller is used to control the operation of the system; the liquid film thickness measurer is electrically connected to the controller.

[0019] Preferably, a motor temperature sensor is provided on the motor of the screw axial-flow oil-gas mixed transportation pump; a first pressure and temperature sensor is provided on the pipeline between the tubular screw homogenizer and the screw axial-flow oil-gas mixed transportation pump body; a second pressure and temperature sensor is provided on the pipeline between the screw axial-flow oil-gas mixed transportation pump body and the gas-liquid separator; the motor temperature sensor, the first pressure and temperature sensor, and the second pressure and temperature sensor are respectively electrically connected to the controller.

[0020] Preferably, a check valve is provided on the pipeline between the first output port of the screw axial-flow oil-gas mixed transportation pump body and the first input end of the gas-liquid separator. The input end of the check valve is connected to the screw axial-flow oil-gas mixed transportation pump body, and the output end is connected to the gas-liquid separator.

[0021] Preferably, a first valve and a fourth valve are installed on the pipeline between the upstream device and the tubular screw homogenizer; the first bypass pipe and the second bypass pipe are connected to the pipeline between the first valve and the fourth valve; the cold fluid outlet is connected to the pipeline between the first bypass pipe and the second bypass pipe; in the pipeline direction from the upstream device to the tubular screw homogenizer, there are in sequence the first valve, the first bypass pipe, the cold fluid outlet, the second bypass pipe, and the fourth valve; a second valve is installed on the first bypass pipe; a third valve is installed on the second bypass pipe; a fifth valve is installed on the first outlet of the tubular screw homogenizer; the fifth valve is located on the pipeline between the first outlet of the tubular screw homogenizer and the second bypass pipe; the third valve and the fourth valve are respectively electrically connected to the controller.

[0022] Preferably, a tenth valve is installed on the cold fluid outlet, a ninth valve is installed on the cold fluid inlet, a thirteenth valve is installed on the second hot fluid inlet, a fourteenth valve is installed on the second hot fluid outlet, and a twelfth valve is installed on the pipeline between the first hot fluid outlet and the coolant inlet of the screw axial flow oil-gas mixed transportation pump motor; the twelfth valve and the thirteenth valve are arranged in parallel; the twelfth valve and the fourteenth valve are arranged in parallel; the ninth valve, the twelfth valve, the thirteenth valve, and the fourteenth valve are respectively electrically connected to the controller.

[0023] Preferably, an eleventh valve is installed on the pipeline between the coolant outlet of the screw axial flow oil-gas mixed transportation pump motor and the pressure compensator.

[0024] Preferably, a seventh valve and an eighth valve are installed on the pipeline between the first output end of the gas-liquid separator and the second inlet of the tubular screw homogenizer; the seventh valve is closer to the gas-liquid separator, and the eighth valve is closer to the tubular screw homogenizer; the ninth valve is connected to the pipeline between the seventh valve and the eighth valve; the seventh valve and the eighth valve are respectively electrically connected to the controller.

[0025] Preferably, a sixth valve is installed on the second output end of the gas-liquid separator; the offshore platform is electrically connected to the controller; the first bypass pipe is connected to the pipeline between the sixth valve and the offshore platform.

[0026] Preferably, the heat exchanger includes a shell, tube sheets, heat transfer tubes, baffle plates, and coiled pipes; the first hot fluid inlet, the first hot fluid outlet, the cold fluid inlet, and the cold fluid outlet are connected to the shell; the coiled pipe is sleeved outside the shell; the second hot fluid outlet and the second hot fluid inlet are connected to the coiled pipe; the tube sheets, heat transfer tubes, and baffle plates are arranged inside the shell; there are multiple heat transfer tubes, which are arranged in parallel at intervals; there are two tube sheets, symmetrically fixed at both ends of the heat transfer tubes and fixedly connected to the shell; the first hot fluid inlet and the first hot fluid outlet are communicated through the heat transfer tubes; there are multiple baffle plates, which are arranged in parallel at intervals between the two tube sheets and fixedly connected to the shell; two adjacent baffle plates are arranged in a staggered up-and-down manner; the baffle plates are arranged parallel to the tube sheets; the cold fluid inlet and the cold fluid outlet are connected between the two tube sheets.

[0027] A working method of a waste heat utilization system for a deep-sea screw axial flow oil-gas mixed transportation pump motor includes the following steps:

[0028] S1: Obtain the incoming flow conditions of the screw axial flow oil-gas mixed transportation pump body and the state parameters of the screw axial flow oil-gas mixed transportation pump motor through the controller;

[0029] S2: Control the working mode of the heat exchanger through the controller;

[0030] S3: Obtain the outflow conditions of the pump body of the screw axial flow oil-gas multiphase pump through the controller;

[0031] S4: Determine the hydrate flow assurance risk and the required concentration of hydrate thermodynamic inhibitor; wherein, the inflow conditions of the pump body of the screw axial flow oil-gas multiphase pump are liquid phase flow rate and gas phase flow rate; the controller determines the reflux liquid phase flow rate according to the inflow conditions and compares it with the maximum allowable cold fluid flow rate of the heat exchanger; if the reflux liquid phase flow rate is greater than the maximum allowable cold fluid flow rate of the heat exchanger, the controller controls the heat exchanger to operate in the maximum cold fluid flow rate working mode; if the reflux liquid phase flow rate is not greater than the maximum allowable cold fluid flow rate of the heat exchanger, the controller controls the heat exchanger to operate in the reflux liquid phase flow rate working mode.

[0032] The state parameter of the motor of the screw axial flow oil-gas multiphase pump is the actual temperature of the motor; the controller compares the actual temperature of the motor with the stable operating temperature of the motor. If the actual temperature of the motor is higher than the stable operating temperature of the motor, the controller controls the heat exchanger to operate in the series working mode of the heat transfer tube - coil, and the hot fluid coolant first exchanges heat with the cold fluid flowing through the shell side in the heat exchanger, and then exchanges heat with the seawater outside the coil; if the actual temperature of the motor of the screw axial flow oil-gas multiphase pump is not higher than the stable operating temperature of the motor, the controller controls the heat exchanger to operate in the single working mode of the heat transfer tube, and the hot fluid coolant only exchanges heat with the cold fluid flowing through the shell side in the heat exchanger.

[0033] The outflow conditions of the pump body of the screw axial flow oil-gas multiphase pump are the temperature and pressure at the outlet of the pump body of the screw axial flow oil-gas multiphase pump. By comparing the outflow conditions of the pump body of the screw axial flow oil-gas multiphase pump with the hydrate phase equilibrium curve under different concentrations of hydrate thermodynamic inhibitors, the heating effect of the waste heat of the motor of the screw axial flow oil-gas multiphase pump on the fluid in the multiphase pipeline is evaluated, and the hydrate flow assurance risk and the required concentration of hydrate thermodynamic inhibitors in the fluid in the multiphase pipeline after heating are determined. Different degrees of heating result in different degrees of reduction in the required concentration of hydrate thermodynamic inhibitors. Without the heating of the heat exchanger, the fluid at the inlet of the pump body of the screw axial flow oil-gas multiphase pump, after being pressurized by the pump body of the screw axial flow oil-gas multiphase pump, has an unchanged temperature and an increased pressure at the outlet of the pump body of the screw axial flow oil-gas multiphase pump. When the temperature and pressure state of the fluid changes and it is in the hydrate risk area, to prevent the formation of hydrates, a hydrate thermodynamic inhibitor with a first concentration is injected. If the heating of the heat exchanger is insufficient, the fluid at the inlet of the pump body of the screw axial flow oil-gas multiphase pump first mixes with the heated fluid from the heat exchanger, the temperature increases, and then it is pressurized by the pump body of the screw axial flow oil-gas multiphase pump. When the temperature and pressure state of the fluid changes and it is in the hydrate risk area, a hydrate thermodynamic inhibitor with a second concentration is injected under this working condition. If the heating of the heat exchanger is sufficient, the fluid at the inlet of the pump body of the screw axial flow oil-gas multiphase pump first mixes with the heated fluid from the heat exchanger, the temperature increases, and then it is pressurized by the pump body of the screw axial flow oil-gas multiphase pump. At this time, there is no risk of hydrate formation, and the required concentration of hydrate thermodynamic inhibitor to be injected under this working condition is zero.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] The system provided by the present invention provides a way for the heat transfer of the high-temperature coolant of the motor to the low-temperature fluid in the multiphase pipeline, realizing the thermal coupling regulation between the motor of the deep-sea screw axial flow oil-gas multiphase pump and the multiphase pipeline. The method provided by the present invention, on the premise of ensuring sufficient cooling of the motor of the deep-sea screw axial flow oil-gas multiphase pump, recovers and utilizes the waste heat of the motor to increase the fluid temperature and reduce the hydrate flow assurance risk in the multiphase pump and the downstream pipeline. The present invention further ensures the economic, efficient and safe operation of the deep-sea screw axial flow oil-gas multiphase pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic structural diagram of the present invention;

[0037] Figure 2 is a schematic structural diagram of the heat exchanger in the present invention;

[0038] Figure 3 is a flowchart of the working method of the present invention;

[0039] Figure 4Schematic diagram of the effects of the present invention. Among them, curve 1 is the hydrate phase equilibrium curve under the action of a hydrate thermodynamic inhibitor at a first concentration, curve 2 is the hydrate phase equilibrium curve under the action of a hydrate thermodynamic inhibitor at a second concentration, curve 3 is the hydrate phase equilibrium curve without a hydrate thermodynamic inhibitor, and the first concentration is higher than the second concentration; points A, B, C, D, and E are the pressure-temperature state points of the fluid at designated positions of the hybrid pump.

[0040] Wherein:

[0041] 1. Upstream equipment; 2. Upstream pipeline; 3. First valve; 4. First bypass pipe; 5. Second valve; 6. Second bypass pipe; 7. Third valve; 8. Fourth valve; 9. First inlet; 10. Second inlet; 11. Tube-type spiral homogenizer; 12. Liquid film thickness measurer; 13. First outlet; 14. Fifth valve; 15. First pressure-temperature sensor; 16. First input port; 17. Pump body of the screw axial-flow oil-gas hybrid pump; 18. First output port; 19. Second pressure-temperature sensor; 20. Check valve; 21. First input end; 22. Gas-liquid separator; 23. First output end; 24. Second output end; 25. Sixth valve; 26. Downstream pipeline; 27. Offshore platform; 28. Seventh valve; 29. Eighth valve; 30. Liquid return pipeline; 31. Ninth valve; 32. Cold fluid inlet; 33. Heat exchanger; 34. Cold fluid outlet; 35. Tenth valve; 36. Motor of the screw axial-flow oil-gas hybrid pump; 37. Coolant outlet; 38. Eleventh valve; 39. Pressure compensator; 40. First hot fluid inlet; 41. First hot fluid outlet; 42. Twelfth valve; 43. Coolant inlet; 44. Thirteenth valve; 45. Second hot fluid inlet; 46. Second hot fluid outlet; 47. Fourteenth valve; 48. Motor temperature sensor; 49. Controller; 331. Shell; 332. Tube sheet; 333. Heat transfer tube; 334. Baffle plate; 335. Coiled pipe. Detailed implementation manners

[0042] The present invention will be further described below with reference to the accompanying drawings.

[0043] As Figures 1 to 3 shown, a system for utilizing the waste heat of a motor of a deep-sea screw axial-flow oil-gas hybrid pump includes:

[0044] A tube-type spiral homogenizer 11, configured with a first inlet 9, a second inlet 10, and a first outlet 13; the first inlet 9 is connected to the upstream equipment 1;

[0045] The heat exchanger 33 is configured with a cold fluid inlet 32, a cold fluid outlet 34, a first hot fluid outlet 41, a second hot fluid outlet 46, a first hot fluid inlet 40, and a second hot fluid inlet 45; the first hot fluid outlet 41 is connected to the second hot fluid inlet 45; the cold fluid outlet 34 is connected between the upstream device 1 and the first inlet 9 of the tubular screw homogenizer 11;

[0046] The pressure compensator 39 has one end connected to the first hot fluid inlet 40;

[0047] The liquid film thickness measuring device 12 is connected to the tubular screw homogenizer 11;

[0048] The screw axial flow oil-gas mixed transportation pump includes a screw axial flow oil-gas mixed transportation pump body 17 and a screw axial flow oil-gas mixed transportation pump motor 36 that are drivingly connected; the screw axial flow oil-gas mixed transportation pump body 17 is configured with a first input port 16 and a first output port 18; the screw axial flow oil-gas mixed transportation pump motor 36 is configured with a coolant inlet 43 and a coolant outlet 37; the first input port 16 is connected to the first outlet 13 of the tubular screw homogenizer 11; the coolant inlet 43 is connected to the second hot fluid outlet 46 and the first hot fluid outlet 41; the coolant outlet 37 is connected to the other end of the pressure compensator 39;

[0049] The gas-liquid separator 22 is configured with a first input end 21, a first output end 23, and a second output end 24; the first input end 21 is connected to the first output port 18 of the screw axial flow oil-gas mixed transportation pump body 17; the first output end 23 is connected to the cold fluid inlet 32 and the second inlet 10 of the tubular screw homogenizer 11; the second output end 24 is connected to the offshore platform 27;

[0050] The first bypass pipe 4 has one end connected to the pipeline between the upstream device 1 and the tubular screw homogenizer 11, and the other end connected to the pipeline between the gas-liquid separator 22 and the offshore platform 27;

[0051] The second bypass pipe 6 has one end connected to the pipeline between the upstream device 1 and the tubular screw homogenizer 11, and the other end connected to the pipeline between the tubular screw homogenizer 11 and the screw axial flow oil-gas mixed transportation pump body 17;

[0052] The controller 49 is used to control the operation of the system; the liquid film thickness measuring device 12 is electrically connected to the controller 49.

[0053] In this embodiment, a motor temperature sensor 48 is provided on the motor 36 of the screw axial flow oil-gas mixed transportation pump; a first pressure and temperature sensor 15 is provided on the pipeline between the tubular screw homogenizer 11 and the pump body 17 of the screw axial flow oil-gas mixed transportation pump; a second pressure and temperature sensor 19 is provided on the pipeline between the pump body 17 of the screw axial flow oil-gas mixed transportation pump and the gas-liquid separator 22; the motor temperature sensor 48, the first pressure and temperature sensor 15, and the second pressure and temperature sensor 19 are respectively electrically connected to the controller 49.

[0054] In this embodiment, a check valve 20 is provided on the pipeline between the first output port 18 of the pump body 17 of the screw axial flow oil-gas mixed transportation pump and the first input end 21 of the gas-liquid separator 22. The input end of the check valve 20 is connected to the pump body 17 of the screw axial flow oil-gas mixed transportation pump, and the output end is connected to the gas-liquid separator 22.

[0055] In this embodiment, a first valve 3 and a fourth valve 8 are installed on the pipeline between the upstream device 1 and the tubular screw homogenizer 11; a first bypass pipe 4 and a second bypass pipe 6 are connected to the pipeline between the first valve 3 and the fourth valve 8; a cold fluid outlet 34 is connected to the pipeline between the first bypass pipe 4 and the second bypass pipe 6; in the pipeline direction from the upstream device 1 to the tubular screw homogenizer 11, there are successively the first valve 3, the first bypass pipe 4, the cold fluid outlet 34, the second bypass pipe 6, and the fourth valve 8; a second valve 5 is installed on the first bypass pipe 4; a third valve 7 is installed on the second bypass pipe 6; a fifth valve 14 is installed on the first outlet 13 of the tubular screw homogenizer 11; the fifth valve 14 is located on the pipeline between the first outlet 13 of the tubular screw homogenizer 11 and the second bypass pipe 6; the third valve 7 and the fourth valve 8 are respectively electrically connected to the controller 49.

[0056] In this embodiment, a tenth valve 35 is installed on the cold fluid outlet 34, a ninth valve 31 is installed on the cold fluid inlet 32, a thirteenth valve 44 is installed on the second hot fluid inlet 45, a fourteenth valve 47 is installed on the second hot fluid outlet 46, and a twelfth valve 42 is installed on the pipeline between the first hot fluid outlet 41 and the coolant inlet 43 of the motor 36 of the screw axial flow oil-gas mixed transportation pump; the twelfth valve 42 and the thirteenth valve 44 are arranged in parallel; the twelfth valve 42 and the fourteenth valve 47 are arranged in parallel; the ninth valve 31, the twelfth valve 42, the thirteenth valve 44, and the fourteenth valve 47 are respectively electrically connected to the controller 49.

[0057] In this embodiment, an eleventh valve 38 is installed on the pipeline between the coolant outlet 37 of the motor 36 of the screw axial flow oil-gas mixed transportation pump and the pressure compensator 39.

[0058] In this embodiment, a seventh valve 28 and an eighth valve 29 are installed on the pipeline between the first output end 23 of the gas-liquid separator 22 and the second inlet 10 of the tubular spiral homogenizer 11; the seventh valve 28 is closer to the gas-liquid separator 22, and the eighth valve 29 is closer to the tubular spiral homogenizer 11; a ninth valve 31 is connected to the pipeline between the seventh valve 28 and the eighth valve 29; the seventh valve 28 and the eighth valve 29 are respectively electrically connected to the controller 49.

[0059] In this embodiment, a sixth valve 25 is installed on the second output end 24 of the gas-liquid separator 22; the offshore platform 27 is electrically connected to the controller 49; a first bypass pipe 4 is connected to the pipeline between the sixth valve 25 and the offshore platform 27.

[0060] The gas-liquid mixture from the upstream device 1 is transported to the tubular spiral homogenizer 11 for evolution treatment, then enters the spiral axial flow oil-gas mixed transportation pump body 17 for pressurization, and then enters the gas-liquid separator 22. A part of the separated liquid enters the heat exchanger 33 and the liquid return pipeline 30, and the remaining liquid and gas are transported to the offshore platform 27 through the downstream pipeline.

[0061] In this embodiment, the heat exchanger 33 includes a shell 331, a tube sheet 332, heat transfer tubes 333, baffle plates 334 and a coil 335; a first hot fluid inlet 40, a first hot fluid outlet 41, a cold fluid inlet 32 and a cold fluid outlet 34 are connected to the shell 331; the coil 335 is sleeved outside the shell 331; a second hot fluid outlet 46 and a second hot fluid inlet 45 are connected to the coil 335; the tube sheet 332, the heat transfer tubes 333 and the baffle plates 334 are arranged inside the shell 331; a plurality of heat transfer tubes 333 are arranged in parallel at intervals; two tube sheets 332 are arranged symmetrically and fixed at both ends of the heat transfer tubes 333 and fixedly connected to the shell 331; the first hot fluid inlet 40 and the first hot fluid outlet 41 are communicated through the heat transfer tubes 333; a plurality of baffle plates 334 are arranged in parallel at intervals between the two tube sheets 332 and fixedly connected to the shell 331; two adjacent baffle plates 334 are arranged vertically and staggered; the baffle plates 334 are arranged parallel to the tube sheets 332; the cold fluid inlet 32 and the cold fluid outlet 34 are connected between the two tube sheets 332.

[0062] The liquid separated by the gas-liquid separator 22 is cold fluid, which enters the shell side formed by the shell 331 and the heat transfer tubes 333 through the cold fluid inlet 32; the coolant of the screw axial flow oil-gas mixed transportation pump motor 36 is hot fluid, which flows to the pressure compensator 39 through the first outlet 37, and then enters the heat transfer tubes 333 in the heat exchanger 33; the heat of the high-temperature coolant is transferred to the low-temperature liquid through the tube wall of the heat transfer tubes 333, the temperature of the coolant decreases, and the temperature of the liquid increases; the heated liquid flows to the upstream pipeline 2 through the cold fluid outlet 26 and mixes with the gas-liquid mixture from the upstream equipment 1, so as to increase the temperature of the gas-liquid mixture; the cooled coolant enters the first hot fluid outlet 41;

[0063] According to the requirements of the stable operation of the screw axial flow oil-gas mixed transportation pump motor 36 for the coolant temperature and the actually measured coolant temperature by the motor temperature sensor 48, the controller 49 controls the opening and closing of the twelfth valve 42, the thirteenth valve 44 and the fourteenth valve 47 to regulate the flow path of the coolant; when the temperature of the cooled coolant meets the requirements, the controller 49 opens the twelfth valve 42 and closes the thirteenth valve 44 and the fourteenth valve 47, and the coolant in the pipeline of the first hot fluid outlet 41 of the heat exchanger 33 enters the screw axial flow oil-gas mixed transportation pump motor 36 through the pipeline of the coolant inlet 43 to take away the heat generated by the screw axial flow oil-gas mixed transportation pump motor 36; when the temperature of the cooled coolant does not meet the requirements, the controller 49 closes the twelfth valve 42 and opens the thirteenth valve 44 and the fourteenth valve 47, and the coolant in the pipeline of the first hot fluid outlet 41 of the heat exchanger 33 enters the coil 335 through the second hot fluid inlet 45; the coil 335 is exposed to the low-temperature seawater, and the heat of the coolant is transferred to the low-temperature seawater through the tube wall of the coil 335, and the temperature of the coolant further decreases; the coolant reaches the coolant inlet 43 of the screw axial flow oil-gas mixed transportation pump motor 36 through the pipeline of the second hot fluid outlet 46, and thus enters the screw axial flow oil-gas mixed transportation pump motor 36 to take away the heat generated by the screw axial flow oil-gas mixed transportation pump motor 36.

[0064] Based on the waste heat utilization system of the deep-sea screw axial flow oil-gas mixed transportation pump motor 36 in the above embodiments, the second aspect embodiments of the present invention propose a working method of the waste heat utilization system of the deep-sea screw axial flow oil-gas mixed transportation pump motor 36.

[0065] A working method of a waste heat utilization system of a deep-sea screw axial flow oil-gas mixed transportation pump motor includes the following steps:

[0066] S1: Obtain the incoming flow conditions of the screw axial flow oil-gas mixed transportation pump body 17 and the state parameters of the screw axial flow oil-gas mixed transportation pump motor 36 through the controller 49;

[0067] S2: Control the working mode of the heat exchanger 33 through the controller 49;

[0068] S3: Obtain the outflow conditions of the pump body 17 of the screw axial flow oil-gas multiphase pump through the controller 49;

[0069] S4: Determine the hydrate flow assurance risk and the required concentration of hydrate thermodynamic inhibitor;

[0070] Among them, the inflow conditions of the pump body 17 of the screw axial flow oil-gas multiphase pump are the liquid phase flow rate and the gas phase flow rate; the controller 49 determines the reflux liquid phase flow rate according to the inflow conditions and compares it with the maximum allowable cold fluid flow rate of the heat exchanger 33; if the reflux liquid phase flow rate is greater than the maximum allowable cold fluid flow rate of the heat exchanger 33, the controller 49 controls the heat exchanger 33 to be in the maximum cold fluid flow rate working mode; if the reflux liquid phase flow rate is not greater than the maximum allowable cold fluid flow rate of the heat exchanger 33, the controller 49 controls the heat exchanger 33 to be in the reflux liquid phase flow rate working mode;

[0071] The state parameter of the motor 36 of the screw axial flow oil-gas multiphase pump is the actual temperature of the motor; the controller 49 compares the actual temperature of the motor with the stable operating temperature of the motor. If the actual temperature of the motor is higher than the stable operating temperature of the motor, the controller 49 controls the heat exchanger 33 to be in the series working mode of the heat transfer tube 333 - coil 335, and the hot fluid coolant first exchanges heat with the cold fluid flowing in the shell side of the heat exchanger 33, and then exchanges heat with the seawater outside the coil 335; if the actual temperature of the motor 36 of the screw axial flow oil-gas multiphase pump is not higher than the stable operating temperature of the motor, the controller 49 controls the heat exchanger 33 to be in the single working mode of the heat transfer tube 333, and the hot fluid coolant only exchanges heat with the cold fluid flowing in the shell side of the heat exchanger 33;

[0072] The outflow conditions of the pump body 17 of the screw axial flow oil-gas multiphase pump are the temperature and pressure at the outlet of the pump body 17 of the screw axial flow oil-gas multiphase pump; compare the outflow conditions of the pump body 17 of the screw axial flow oil-gas multiphase pump with the hydrate phase equilibrium curve under different concentrations of hydrate thermodynamic inhibitors, evaluate the heating effect of the waste heat of the motor 36 of the screw axial flow oil-gas multiphase pump on the fluid in the multiphase transportation pipeline, and determine the hydrate flow assurance risk and the required concentration of hydrate thermodynamic inhibitor in the fluid in the multiphase transportation pipeline after heating; the heating degree is different, such as Figure 4As shown, the degree of reduction in the required concentration of the hydrate thermodynamic inhibitor varies. Without the heating of the heat exchanger 33, for the fluid at the inlet of the spiral axial flow oil-gas multiphase pump body 17, after being pressurized by the spiral axial flow oil-gas multiphase pump body 17, the temperature of the fluid at the outlet of the spiral axial flow oil-gas multiphase pump body 17 remains unchanged while the pressure increases, and the temperature-pressure state of the fluid changes from point A to point B. When in the hydrate risk area, to prevent the formation of hydrates, the required concentration of the hydrate thermodynamic inhibitor to be injected is the high concentration corresponding to the hydrate phase equilibrium curve 1 under the action of the hydrate thermodynamic inhibitor concentration of the first concentration; if the heating of the heat exchanger 33 is insufficient, the fluid at the inlet of the spiral axial flow oil-gas multiphase pump body 17 first mixes with the heating fluid from the heat exchanger 33, the temperature increases, and then is pressurized by the spiral axial flow oil-gas multiphase pump body 17. The temperature-pressure state of the fluid first changes from point A to point C and then to point D. When in the hydrate risk area, the required concentration of the hydrate thermodynamic inhibitor to be injected under this condition is the low concentration of the hydrate phase equilibrium curve 2 under the action of the hydrate thermodynamic inhibitor concentration of the second concentration; if the heating of the heat exchanger 33 is sufficient, the fluid at the inlet of the spiral axial flow oil-gas multiphase pump body 17 first mixes with the heating fluid from the heat exchanger 33, the temperature increases, and then is pressurized by the spiral axial flow oil-gas multiphase pump body 17. The temperature-pressure state of the fluid first changes from point A to point E and then to point F, which is below the hydrate phase equilibrium curve 3 without inhibitor, and there is no risk of hydrate formation. The required concentration of the hydrate thermodynamic inhibitor to be injected under this condition is zero.

[0073] The above embodiments are only used to illustrate the present invention. Among them, the connection methods of various components and the like are all subject to changes. In the present invention, the first, second, etc. used are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Any changes and transformations made on the basis of the technical solution of the present invention are not excluded from the protection scope of the present invention.

Claims

1. A system for utilizing the waste heat of a motor of a deep - sea screw - axial oil - gas multiphase pump, characterized in that, Comprising: A tubular spiral homogenizer (11) configured with a first inlet (9), a second inlet (10) and a first outlet (13); the first inlet (9) is connected to an upstream device (1); A heat exchanger (33) configured with a cold fluid inlet (32), a cold fluid outlet (34), a first hot fluid outlet (41), a second hot fluid outlet (46), a first hot fluid inlet (40), a second hot fluid inlet (45); the first hot fluid outlet (41) is connected to the second hot fluid inlet (45); the cold fluid outlet (34) is connected between the upstream device (1) and the first inlet (9) of the tubular spiral homogenizer (11); A pressure compensator (39) with one end connected to the first hot fluid inlet (40); A liquid film thickness measurer (12) connected to the tubular spiral homogenizer (11); A screw axial flow oil-gas mixed transportation pump, including a screw axial flow oil-gas mixed transportation pump body (17) and a screw axial flow oil-gas mixed transportation pump motor (36) which are drivingly connected; the screw axial flow oil-gas mixed transportation pump body (17) is configured with a first input port (16) and a first output port (18); the screw axial flow oil-gas mixed transportation pump motor (36) is configured with a coolant inlet (43) and a coolant outlet (37); the first input port (16) is connected to the first outlet (13) of the tubular spiral homogenizer (11); the coolant inlet (43) is connected to the second hot fluid outlet (46) and the first hot fluid outlet (41); the coolant outlet (37) is connected to the other end of the pressure compensator (39); A gas-liquid separator (22) configured with a first input end (21), a first output end (23) and a second output end (24); the first input end (21) is connected to the first output port (18) of the screw axial flow oil-gas mixed transportation pump body (17); the first output end (23) is connected to the cold fluid inlet (32) and the second inlet (10) of the tubular spiral homogenizer (11); the second output end (24) is connected to an offshore platform (27); A first bypass pipe (4) with one end connected to the pipeline between the upstream device (1) and the tubular spiral homogenizer (11), and the other end connected to the pipeline between the gas-liquid separator (22) and the offshore platform (27); A second bypass pipe (6) with one end connected to the pipeline between the upstream device (1) and the tubular spiral homogenizer (11), and the other end connected to the pipeline between the tubular spiral homogenizer (11) and the screw axial flow oil-gas mixed transportation pump body (17); A controller (49) for controlling the operation of the system; the liquid film thickness measurer (12) is electrically connected to the controller (49).

2. The waste heat utilization system of the motor of a deep-sea screw axial flow oil-gas mixed transportation pump according to claim 1, wherein A motor temperature sensor (48) is provided on the motor (36) of the screw axial flow oil-gas mixed transportation pump; a first pressure and temperature sensor (15) is provided on the pipeline between the tubular screw homogenizer (11) and the pump body (17) of the screw axial flow oil-gas mixed transportation pump; a second pressure and temperature sensor (19) is provided on the pipeline between the pump body (17) of the screw axial flow oil-gas mixed transportation pump and the gas-liquid separator (22); the motor temperature sensor (48), the first pressure and temperature sensor (15), and the second pressure and temperature sensor (19) are respectively electrically connected to the controller (49).

3. The waste heat utilization system of the motor of a deep-sea screw axial flow oil-gas mixed transportation pump according to claim 1, wherein, A check valve (20) is provided on the pipeline between the first output port (18) of the pump body (17) of the screw axial flow oil-gas mixed transportation pump and the first input end (21) of the gas-liquid separator (22). The input end of the check valve (20) is connected to the pump body (17) of the screw axial flow oil-gas mixed transportation pump, and the output end is connected to the gas-liquid separator (22).

4. A waste heat utilization system for a motor of a deep - sea screw axial - flow oil - gas mixed - transportation pump according to claim 1, wherein, A first valve (3) and a fourth valve (8) are installed on the pipeline between the upstream device (1) and the tubular screw homogenizer (11); the first bypass pipe (4) and the second bypass pipe (6) are connected to the pipeline between the first valve (3) and the fourth valve (8); the cold fluid outlet (34) is connected to the pipeline between the first bypass pipe (4) and the second bypass pipe (6); in the pipeline direction from the upstream device (1) to the tubular screw homogenizer (11), there are successively the first valve (3), the first bypass pipe (4), the cold fluid outlet (34), the second bypass pipe (6), and the fourth valve (8); a second valve (5) is installed on the first bypass pipe (4); a third valve (7) is installed on the second bypass pipe (6); a fifth valve (14) is installed on the first outlet (13) of the tubular screw homogenizer (11); the fifth valve (14) is located on the pipeline between the first outlet (13) of the tubular screw homogenizer (11) and the second bypass pipe (6); the third valve (7) and the fourth valve (8) are respectively electrically connected to the controller (49).

5. The waste heat utilization system of the motor of a deep-sea screw axial-flow oil-gas mixed transportation pump as described in claim 1, characterized in that, A tenth valve (35) is installed on the cold fluid outlet (34), a ninth valve (31) is installed on the cold fluid inlet (32), a thirteenth valve (44) is installed on the second hot fluid inlet (45), a fourteenth valve (47) is installed on the second hot fluid outlet (46), and a twelfth valve (42) is installed on the pipeline between the first hot fluid outlet (41) and the coolant inlet (43) of the motor (36) of the screw axial flow oil-gas mixed transportation pump; the twelfth valve (42) and the thirteenth valve (44) are arranged in parallel; the twelfth valve (42) and the fourteenth valve (47) are arranged in parallel; the ninth valve (31), the twelfth valve (42), the thirteenth valve (44), and the fourteenth valve (47) are respectively electrically connected to the controller (49).

6. The waste heat utilization system of the motor of a deep-sea screw axial flow oil-gas mixed transportation pump according to claim 1, characterized in that, An eleventh valve (38) is installed on the pipeline between the coolant outlet (37) of the motor (36) of the screw axial flow oil-gas mixed transportation pump and the pressure compensator (39).

7. The waste heat utilization system of the motor of a deep-sea screw axial flow oil-gas mixed transportation pump according to claim 5, characterized in that A seventh valve (28) and an eighth valve (29) are installed on the pipeline between the first output end (23) of the gas-liquid separator (22) and the second inlet (10) of the tubular spiral homogenizer (11); the seventh valve (28) is closer to the gas-liquid separator (22), and the eighth valve (29) is closer to the tubular spiral homogenizer (11); the ninth valve (31) is connected to the pipeline between the seventh valve (28) and the eighth valve (29); the seventh valve (28) and the eighth valve (29) are respectively electrically connected to the controller (49).

8. The waste heat utilization system of the motor of a deep-sea screw axial-flow oil-gas mixed transportation pump as described in claim 1, wherein, A sixth valve (25) is installed on the second output end (24) of the gas-liquid separator (22); the offshore platform (27) is electrically connected to the controller (49); the first bypass pipe (4) is connected to the pipeline between the sixth valve (25) and the offshore platform (27).

9. A waste heat utilization system for a deep-sea screw axial flow oil-gas mixed transportation pump motor according to any one of claims 1 to 8, characterized in that, The heat exchanger (33) includes a shell (331), tube sheets (332), heat transfer tubes (333), baffle plates (334) and coiled pipes (335); the first hot fluid inlet (40), the first hot fluid outlet (41), the cold fluid inlet (32), and the cold fluid outlet (34) are connected to the shell (331); the coiled pipe (335) is sleeved outside the shell (331); the second hot fluid outlet (46) and the second hot fluid inlet (45) are connected to the coiled pipe (335); the tube sheets (332), the heat transfer tubes (333), and the baffle plates (334) are arranged inside the shell (331); a plurality of heat transfer tubes (333) are arranged in parallel at intervals; two tube sheets (332) are arranged symmetrically and fixed at both ends of the heat transfer tubes (333) and fixedly connected to the shell (331); the first hot fluid inlet (40) and the first hot fluid outlet (41) are communicated through the heat transfer tubes (333); a plurality of baffle plates (334) are arranged in parallel at intervals between the two tube sheets (332) and fixedly connected to the shell (331); two adjacent baffle plates (334) are arranged vertically and staggeredly; the baffle plates (334) are arranged parallel to the tube sheets (332); the cold fluid inlet (32) and the cold fluid outlet (34) are connected between the two tube sheets (332).

10. A working method of a waste heat utilization system for a motor of a deep-sea screw axial flow oil-gas mixed transportation pump, characterized in that, It includes the following steps: S1: Obtain the incoming flow conditions of the screw axial flow oil-gas multiphase pump body (17) and the state parameters of the screw axial flow oil-gas multiphase pump motor (36) through the controller (49). S2: Control the working mode of the heat exchanger (33) through the controller (49). S3: Obtain the outgoing flow conditions of the screw axial flow oil-gas multiphase pump body (17) through the controller (49). S4: Determine the hydrate flow assurance risk and the required concentration of hydrate thermodynamic inhibitor. Among them, the incoming flow conditions of the spiral axial flow oil-gas mixed transportation pump body (17) are liquid phase flow rate and gas phase flow rate; the controller (49) determines the reflux liquid phase flow rate according to the incoming flow conditions and compares it with the maximum cold fluid flow rate allowed by the heat exchanger (33); if the reflux liquid phase flow rate is greater than the maximum cold fluid flow rate allowed by the heat exchanger (33), the controller (49) controls the heat exchanger (33) to be in the maximum cold fluid flow rate working mode; if the reflux liquid phase flow rate is not greater than the maximum cold fluid flow rate allowed by the heat exchanger (33), the controller (49) controls the heat exchanger (33) to be in the reflux liquid phase flow rate working mode; The state parameter of the spiral axial flow oil-gas mixed transportation pump motor (36) is the actual temperature of the motor; the controller (49) compares the actual temperature of the motor with the stable operating temperature of the motor. If the actual temperature of the motor is higher than the stable operating temperature of the motor, the controller (49) controls the heat exchanger (36) to be in the series working mode of the heat transfer tube (333) - coil pipe (335), and the hot fluid coolant first exchanges heat with the cold fluid flowing in the shell side of the heat exchanger (33), and then exchanges heat with the seawater outside the coil pipe (335); if the actual temperature of the spiral axial flow oil-gas mixed transportation pump motor (36) is not higher than the stable operating temperature of the motor, the controller (49) controls the heat exchanger (33) to be in the single working mode of the heat transfer tube (333), and the hot fluid coolant only exchanges heat with the cold fluid flowing in the shell side of the heat exchanger (33); The outflow conditions of the pump body (17) of the screw axial flow oil-gas multiphase pump are the temperature and pressure at the outlet of the pump body (17) of the screw axial flow oil-gas multiphase pump. By comparing the outflow conditions of the pump body (17) of the screw axial flow oil-gas multiphase pump with the hydrate phase equilibrium curves at different concentrations of hydrate thermodynamic inhibitors, evaluate the heating effect of the waste heat of the motor (36) of the screw axial flow oil-gas multiphase pump on the fluid in the multiphase pipeline, and determine the hydrate flow assurance risk and the required concentration of hydrate thermodynamic inhibitors in the fluid in the multiphase pipeline after heating. Different degrees of heating result in different degrees of reduction in the required concentration of hydrate thermodynamic inhibitors. Without the heating of the heat exchanger (33), for the fluid at the inlet of the pump body (17) of the screw axial flow oil-gas multiphase pump, after being pressurized by the pump body (17) of the screw axial flow oil-gas multiphase pump, the temperature of the fluid at the outlet of the pump body (17) of the screw axial flow oil-gas multiphase pump remains unchanged while the pressure increases, and the temperature and pressure state of the fluid changes. When in the hydrate risk area, to prevent hydrate formation, a hydrate thermodynamic inhibitor with a first concentration is injected. If the heating of the heat exchanger (33) is insufficient, the fluid at the inlet of the pump body (17) of the screw axial flow oil-gas multiphase pump first mixes with the heated fluid from the heat exchanger (33) and the temperature increases, and then is pressurized by the pump body (17) of the screw axial flow oil-gas multiphase pump. When the temperature and pressure state of the fluid changes and it is in the hydrate risk area, a hydrate thermodynamic inhibitor with a second concentration is injected under this condition. If the heating of the heat exchanger (33) is sufficient, the fluid at the inlet of the pump body (17) of the screw axial flow oil-gas multiphase pump first mixes with the heated fluid from the heat exchanger (33) and the temperature increases, and then is pressurized by the pump body (17) of the screw axial flow oil-gas multiphase pump. At this time, there is no risk of hydrate formation, and the required concentration of the hydrate thermodynamic inhibitor to be injected under this condition is zero.

Images