A method and system for testing a cryogenic reciprocating pump with multiple working fluids and a wide flow range

Abstract

The present invention provides a cryogenic reciprocating pump testing method and system for multiple working fluids with a wide flow range, which relates to the field of new energy. The method connects the discharge port of the cryogenic reciprocating pump to a venting pipeline in the direction of liquid discharge, in turn, through a rewarming coil with a pressure sensor on the top, a cryogenic one-way valve, a vaporizer, a back pressure regulating unit, and a mass flow meter; a back pressure valve, a first throttling device with a maximum flow coefficient smaller than the back pressure valve and selectively connected in series with the back pressure valve, and a second throttling device with a maximum flow coefficient larger than the back pressure valve and selectively connected in parallel with the back pressure valve are arranged in the back pressure regulating unit. The present invention uses a flexible combination of the back pressure valve and the throttling device, so that the same cryogenic reciprocating pump testing system can be simultaneously applicable to multiple cryogenic working fluids and a wide flow range, thereby greatly improving the testing efficiency of the cryogenic reciprocating pump and the utilization rate of the testing system, and reducing the testing cost.

Description

Technical Field

[0001] The present invention belongs to the field of new energy technology, and in particular relates to a method and system for testing a cryogenic reciprocating pump with multiple working fluids and a wide flow range. Background Art

[0002] Cryogenic reciprocating pumps are widely used in various gas filling, liquefied natural gas filling stations, oil pressurization secondary mining and other occasions. In recent years, with the rapid development of hydrogen energy, cryogenic reciprocating pumps are used for pressurized filling of liquid hydrogen and transfer from liquid hydrogen tank trucks to low-pressure liquid hydrogen storage tanks. Compared with the gas hydrogen filling scheme based on compressors, the liquid hydrogen filling scheme based on cryogenic reciprocating pumps can effectively utilize the cost advantage of long-distance transportation of liquid hydrogen and the energy efficiency advantage of liquid hydrogen pressurization. Due to the important application value of cryogenic reciprocating pumps, it is particularly important to carry out comprehensive performance testing before they are put into use. However, for the existing cryogenic reciprocating pump test method and system composition, the same set of test systems is only applicable to a single working fluid or a few working fluids with similar molecular weights, as well as a narrow flow range, which greatly reduces the test efficiency and test system utilization of the cryogenic reciprocating pump, resulting in a significant increase in the test cost. In order to overcome the above problems, it is urgent to provide a cryogenic reciprocating pump test method and system for a wide flow range of multiple working fluids, so that the same set of cryogenic reciprocating pump test system can be simultaneously applicable to multiple cryogenic working fluids and a wide flow range. Summary of the invention

[0003] In view of the defects of the prior art, the present invention provides a cryogenic reciprocating pump testing method and system for multiple working fluids with a wide flow range, so that the same cryogenic reciprocating pump testing system can simultaneously meet the testing of multiple cryogenic working fluids and a wide flow range.

[0004] The technical solution adopted by the present invention is as follows:

[0005] The present invention provides a low-temperature reciprocating pump testing method for multiple working fluids and a wide flow range, comprising:

[0006] Step S101, connecting the discharge port of the cryogenic reciprocating pump to the discharge pipeline in the liquid discharge direction through the rewarming coil with a pressure sensor on the top, the cryogenic one-way valve, the vaporizer, the back pressure regulating unit, and the mass flow meter in sequence;

[0007] Step S102, in the back pressure regulating unit, a back pressure valve, a first throttling device having a maximum flow coefficient smaller than that of the back pressure valve and selectively connected in series with the back pressure valve, a second throttling device having a maximum flow coefficient larger than that of the back pressure valve and selectively connected in parallel with the back pressure valve, a first stop valve for controlling whether the first throttling device is connected in series with the back pressure valve, and a second stop valve for controlling whether the second throttling device is connected in parallel with the back pressure valve are provided;

[0008] Step S103, determining the pipeline parameters and heat exchange area of ​​the gasifier according to the medium compatibility, heat exchange and pressure drop requirements for all possible test working media and test working conditions;

[0009] Step S104, determining a volume flow rate variation range according to the theoretical volume flow rate range and the expected minimum volume efficiency of all cryogenic reciprocating pumps to be tested;

[0010] Step S105, for all possible test working fluids and test working conditions, calculate and save the pressure drop of the gasifier designed in step S103 under different working fluids, volume flow rates and drainage back pressures, obtain the pressure drop range of the gasifier, and determine the expected inlet pressure range of the back pressure regulating unit in combination with the expected variation range of the drainage back pressure;

[0011] Step S106, when designing the back pressure regulating unit, according to all possible test working fluids, the volume flow rate variation range, the expected inlet pressure range of the back pressure regulating unit, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, the flow formula of the valve is used to determine the value range of the flow coefficient of the back pressure regulating unit, and the maximum flow coefficient of the back pressure valve, the first throttling device and the second throttling device is determined accordingly;

[0012] Step S107, before the test, according to the current working fluid to be tested, the expected drainage back pressure and the theoretical volume flow rate, the pressure drop range of the gasifier in the current test is estimated by interpolation based on the gasifier pressure drop data saved in step S105, and the expected inlet pressure range of the back pressure regulating unit in the current test is determined accordingly;

[0013] Step S108, before the test, according to the current working fluid to be tested, the theoretical volume flow rate, the expected inlet pressure range of the back pressure regulating unit obtained in step S107, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, determine the optimal flow coefficient interval of the back pressure regulating unit in the current test, and then determine the connectivity and optimal setting of the first throttling device and the second throttling device, and perform pre-control before the test accordingly;

[0014] Step S109, during the test, the back pressure valve is adjusted according to the expected inlet pressure range of the back pressure regulating unit in the current test and the measured back pressure of the drain line from the pressure sensor at the top of the rewarming coil, so as to control the back pressure of the drain line within the desired range.

[0015] Optionally, step S103 is specifically:

[0016] The material of the vaporizer shall be determined according to the principle of meeting the medium compatibility requirements under all working fluids to be tested;

[0017] The required heat exchange area of ​​the vaporizer is determined according to the maximum value of the product of the inlet-outlet specific enthalpy difference of the vaporizer and the discharge mass flow rate;

[0018] According to the principle that the maximum pressure drop value under all test working fluids and test conditions is less than the allowable pressure drop and the actual heat exchange area is larger than the required heat exchange area, the series and parallel connection mode, diameter, total length and heat exchange area of ​​the internal pipeline of the vaporizer are determined to determine the pipeline parameters and heat exchange area of ​​the vaporizer.

[0019] Optionally, in step S108, the optimal flow coefficient interval of the back pressure regulating unit in the current test is determined, specifically:

[0020] Before the test, the upper limit of the optimal flow coefficient range of the back pressure regulating unit in the current test is determined according to the expected lower limit of the inlet pressure of the back pressure regulating unit in the current test and the theoretical volume flow of the cryogenic reciprocating pump to be tested;

[0021] The lower limit of the optimal flow coefficient range of the back pressure regulating unit in the current test is determined based on the expected inlet pressure upper limit of the back pressure regulating unit in the current test, the product of the theoretical volume flow of the cryogenic reciprocating pump to be tested and the expected minimum volumetric efficiency.

[0022] Optionally, in step S108, the connectivity and optimal settings of the first throttling device and the second throttling device are determined, and pre-control before the test is performed accordingly, specifically:

[0023] When and only when the minimum flow coefficient within the adjustable range of the back pressure valve is greater than the lower limit of the optimal flow coefficient interval of the back pressure regulating unit, the first throttling device having a maximum flow coefficient smaller than the back pressure valve is connected in series with the back pressure valve;

[0024] When and only when the maximum flow coefficient of the back pressure valve is less than the upper limit of the optimal flow coefficient interval of the back pressure regulating unit, a second throttling device having a maximum flow coefficient greater than that of the back pressure valve is connected in parallel with the back pressure valve;

[0025] After determining the connectivity of the first throttling device and the second throttling device according to the above principle, determine the best settings of the first throttling device and the second throttling device in the current test according to the calculation method of the equivalent flow coefficient after the gas valves are connected in series and parallel;

[0026] On this basis, according to the determined connectivity and optimal settings of the first throttling device and the second throttling device, the first throttling device and the second throttling device are pre-controlled before testing.

[0027] The present invention also provides a cryogenic reciprocating pump testing system for multiple working fluids and a wide flow range, comprising:

[0028] A module is provided for connecting the discharge port of the cryogenic reciprocating pump to the discharge pipeline in the liquid discharge direction through a rewarming coil with a pressure sensor on the top, a cryogenic one-way valve, a vaporizer, a back pressure regulating unit, and a mass flow meter in sequence;

[0029] A back pressure regulating module is used to realize back pressure control of a discharge pipeline under a multi-media and wide flow range by using a back pressure valve, a first throttling device having a maximum flow coefficient smaller than that of the back pressure valve and selectively connected in series with the back pressure valve, a second throttling device having a maximum flow coefficient larger than that of the back pressure valve and selectively connected in parallel with the back pressure valve, a first stop valve for controlling whether the first throttling device is connected in series with the back pressure valve, and a second stop valve for controlling whether the second throttling device is connected in parallel with the back pressure valve;

[0030] The vaporizer design module is used to determine the vaporizer piping parameters and heat exchange area according to the principle of meeting the medium compatibility, heat exchange and pressure drop requirements under all test working fluids and test conditions;

[0031] A back pressure regulating unit design module is used to determine the flow coefficient value range of the back pressure regulating unit according to all possible test working fluids, volume flow rates and expected discharge back pressure ranges, as well as the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, and further determine the maximum flow coefficients of the back pressure valve, the first throttling device and the second throttling device;

[0032] The expected inlet pressure estimation module of the back pressure regulating unit is used to determine the expected inlet pressure range of the back pressure regulating unit in the current test according to the current working fluid to be tested, the theoretical volume flow rate and the expected discharge back pressure before the test;

[0033] The back pressure regulating unit presetting module is used to determine the optimal flow coefficient interval of the back pressure regulating unit in the current test according to the current working fluid to be tested, the theoretical volume flow, the expected inlet pressure range of the back pressure regulating unit, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit before the test, and then determine the connectivity and optimal setting of the first throttling device and the second throttling device;

[0034] The control module is used to pre-control the first throttling device and the second throttling device according to the connectivity and optimal settings determined by the pre-setting module of the back pressure regulating unit before the test, and to adjust the back pressure valve according to the expected inlet pressure range of the back pressure regulating unit in the current test during the test, so as to achieve accurate control of the back pressure of the discharge pipeline.

[0035] The present invention provides a method and system for testing a cryogenic reciprocating pump with multiple working fluids and a wide flow range, which has the following advantages:

[0036] The present invention provides a method and system for testing a cryogenic reciprocating pump with a wide flow range for multiple working fluids, which relates to the field of new energy. The method connects the discharge port of the cryogenic reciprocating pump to a venting pipeline in the direction of liquid discharge through a rewarming coil with a pressure sensor on the top, a cryogenic one-way valve, a vaporizer, a back pressure regulating unit and a mass flow meter in sequence; the back pressure regulating unit is provided with a back pressure valve, a throttling device with a maximum flow coefficient smaller than the back pressure valve and selectively connected in series with the back pressure valve, and a throttling device with a maximum flow coefficient larger than the back pressure valve and selectively connected in parallel with the back pressure valve; the control system before the test determines the connectivity and optimal settings of each throttling device in the current test according to the parameters such as the working fluid of the cryogenic reciprocating pump to be tested, the theoretical volume flow rate and the expected discharge back pressure, and performs pre-control; the discharge back pressure is controlled by adjusting the back pressure valve during the test. The present invention uses a flexible combination of the back pressure valve and the throttling device, so that the same cryogenic reciprocating pump test system can be simultaneously applicable to multiple cryogenic working fluids and a wide flow range, thereby greatly improving the test efficiency and test system utilization of the cryogenic reciprocating pump and reducing the test cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A schematic flow chart of a method for testing a cryogenic reciprocating pump with multiple working fluids and a wide flow range provided by the present invention;

[0039] Figure 2 A schematic structural diagram corresponding to a method for testing a cryogenic reciprocating pump with a wide flow range and multiple working fluids provided by the present invention;

[0040] The accompanying drawings are marked as follows:

[0041] 1. Liquid inlet hose of cryogenic reciprocating pump; 2. Hydraulic end of cryogenic reciprocating pump; 3. Steam return hose of cryogenic reciprocating pump; 4. Transmission end of cryogenic reciprocating pump; 5. Reciprocating frequency measuring element; 6. Liquid discharge port of cryogenic reciprocating pump; 7. First cryogenic pipeline; 8. Second cryogenic pipeline; 9. Cryogenic stop valve; 10. Reheating coil; 11. First pressure sensor; 12. First normal temperature pipeline; 13. Safety valve; 14. Second normal temperature pipeline; 15. First pressure reducing valve; 16. First normal temperature low pressure pipeline; 17. Third cryogenic pipeline; 18. Low 1. Temperature check valve; 2. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79. 80. 81. 82. 83. 84. 85. 86. 87. 88. 89. 90. 91. 92. 93. 94. 95. 96. 97. 98. 99. Low-pressure relief pipeline; 35, low-pressure relief port; 36, back-pressure valve inlet pipeline; 37, pneumatic back-pressure regulating valve; 38, back-pressure valve outlet pipeline; 39, third normal-temperature pipeline; 40, first opening adjustable throttle valve; 41, fourth normal-temperature pipeline; 42, fifth normal-temperature pipeline; 43, first pneumatic stop valve; 44, sixth normal-temperature pipeline; 45, seventh normal-temperature pipeline; 46, second pneumatic stop valve; 47, eighth normal-temperature pipeline; 48, second opening adjustable throttle valve; 49, ninth normal-temperature pipeline; 50, drive Gas source; 51. first driving gas pipeline; 52. second driving gas pipeline; 53. programmable pressure controller; 54. electrical signal input terminal of pressure controller; 55. third driving gas pipeline; 56. back pressure valve driving gas input terminal; 57. fourth driving gas pipeline; 58. fifth driving gas pipeline; 59. first solenoid valve; 60. first stop valve driving gas input pipeline; 61. sixth driving gas pipeline; 62. second solenoid valve; 63. second stop valve driving gas input pipeline; 64. control system. DETAILED DESCRIPTION

[0042] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] The purpose of the present invention is to provide a cryogenic reciprocating pump testing method and system for multiple working fluids and a wide flow range, which can enable the same cryogenic reciprocating pump testing system to be simultaneously applicable to multiple cryogenic working fluids and a very wide flow range, greatly improving the testing efficiency and testing system utilization of the cryogenic reciprocating pump and reducing the testing cost.

[0045] The present invention provides a low-temperature reciprocating pump testing method for multiple working fluids and a wide flow range, comprising:

[0046] Step S101, connecting the discharge port of the cryogenic reciprocating pump to the discharge pipeline in the liquid discharge direction through the rewarming coil with a pressure sensor on the top, the cryogenic one-way valve, the vaporizer, the back pressure regulating unit, and the mass flow meter in sequence;

[0047] Step S102, in the back pressure regulating unit, a back pressure valve, a first throttling device having a maximum flow coefficient smaller than that of the back pressure valve and selectively connected in series with the back pressure valve, a second throttling device having a maximum flow coefficient larger than that of the back pressure valve and selectively connected in parallel with the back pressure valve, a first stop valve for controlling whether the first throttling device is connected in series with the back pressure valve, and a second stop valve for controlling whether the second throttling device is connected in parallel with the back pressure valve are provided;

[0048] Among them, the back pressure valve is a pneumatic back pressure regulating valve, which controls its back pressure by controlling its driving air pressure using a pressure control device.

[0049] As one approach, the first throttling device is a fixed-opening throttling valve whose maximum flow coefficient is smaller than that of the back pressure valve; the second throttling device is a fixed-opening throttling valve whose maximum flow coefficient is larger than that of the back pressure valve.

[0050] As a second method, the first throttling device and the second throttling device are respectively composed of a number of throttling valves with fixed openings connected in parallel, and an automatic stop valve with a flow coefficient much larger than the above-mentioned throttling valve is provided on each parallel branch to achieve intermittent adjustment of the flow coefficient of the first throttling device and the second throttling device.

[0051] As another method, the first throttling device is an adjustable throttle valve with a maximum flow coefficient less than the back pressure valve, and the second throttling device is an adjustable throttle valve with a maximum flow coefficient greater than the back pressure valve. The adjustable throttle valve is pneumatic, electric or electromagnetic.

[0052] Step S103, determining the pipeline parameters and heat exchange area of ​​the gasifier according to the medium compatibility, heat exchange and pressure drop requirements for all possible test working media and test working conditions;

[0053] Step S103 is specifically as follows:

[0054] The material of the vaporizer shall be determined according to the principle of meeting the medium compatibility requirements under all working fluids to be tested;

[0055] The required heat exchange area of ​​the vaporizer is determined according to the maximum value of the product of the inlet-outlet specific enthalpy difference of the vaporizer and the discharge mass flow rate;

[0056] According to the principle that the maximum pressure drop value under all test working fluids and test conditions is less than the allowable pressure drop and the actual heat exchange area is larger than the required heat exchange area, the series and parallel connection mode, diameter, total length and heat exchange area of ​​the internal pipeline of the vaporizer are determined to determine the pipeline parameters and heat exchange area of ​​the vaporizer.

[0057] Step S104, determining a volume flow rate variation range according to the theoretical volume flow rate range and the expected minimum volume efficiency of all cryogenic reciprocating pumps to be tested;

[0058] Step S105, for all possible test working fluids and test working conditions, calculate and save the pressure drop of the gasifier designed in step S103 under different working fluids, volume flow rates and drainage back pressures, obtain the pressure drop range of the gasifier, and determine the expected inlet pressure range of the back pressure regulating unit in combination with the expected variation range of the drainage back pressure;

[0059] Step S106, when designing the back pressure regulating unit, according to all possible test working fluids, the volume flow rate variation range, the expected inlet pressure range of the back pressure regulating unit, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, the flow formula of the valve is used to determine the value range of the flow coefficient of the back pressure regulating unit, and the maximum flow coefficient of the back pressure valve, the first throttling device and the second throttling device is determined accordingly;

[0060] Step S107, before the test, according to the current working fluid to be tested, the expected drainage back pressure and the theoretical volume flow rate, the pressure drop range of the gasifier in the current test is estimated by interpolation based on the gasifier pressure drop data saved in step S105, and the expected inlet pressure range of the back pressure regulating unit in the current test is determined accordingly;

[0061] Step S108, before the test, according to the current working fluid to be tested, the theoretical volume flow rate, the expected inlet pressure range of the back pressure regulating unit obtained in step S107, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, determine the optimal flow coefficient interval of the back pressure regulating unit designed in the current test, and then determine the connectivity and optimal setting of the first throttling device and the second throttling device, and perform pre-control before the test accordingly;

[0062] In step S108, the optimal flow coefficient range of the back pressure regulating unit in the current test is determined, specifically:

[0063] Before the test, the upper limit of the optimal flow coefficient range of the back pressure regulating unit in the current test is determined according to the expected lower limit of the inlet pressure of the back pressure regulating unit in the current test and the theoretical volume flow of the cryogenic reciprocating pump to be tested;

[0064] The lower limit of the optimal flow coefficient range of the back pressure regulating unit in the current test is determined based on the expected inlet pressure upper limit of the back pressure regulating unit in the current test, the product of the theoretical volume flow of the cryogenic reciprocating pump to be tested and the expected minimum volumetric efficiency.

[0065] In step S108, the connectivity and optimal settings of the first throttling device and the second throttling device are determined, and pre-control before the test is performed accordingly, specifically:

[0066] When and only when the minimum flow coefficient within the adjustable range of the back pressure valve is greater than the lower limit of the optimal flow coefficient interval of the back pressure regulating unit, the first throttling device having a maximum flow coefficient smaller than the back pressure valve is connected in series with the back pressure valve;

[0067] When and only when the maximum flow coefficient of the back pressure valve is less than the upper limit of the optimal flow coefficient interval of the back pressure regulating unit, a second throttling device having a maximum flow coefficient greater than that of the back pressure valve is connected in parallel with the back pressure valve;

[0068] After determining the connectivity of the first throttling device and the second throttling device according to the above principle, determine the best settings of the first throttling device and the second throttling device in the current test according to the calculation method of the equivalent flow coefficient after the gas valves are connected in series and parallel;

[0069] On this basis, the first throttling device and the second throttling device are pre-controlled before testing according to the determined connectivity and optimal settings of the first throttling device and the second throttling device.

[0070] In this step, the optimal settings of the first throttling device and the second throttling device are determined based on the current working fluid to be measured, the theoretical volume flow, the expected inlet pressure range of the back pressure regulating unit, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, including the optimal flow coefficient and valve opening.

[0071] Step S109, during the test, the back pressure valve is adjusted according to the expected inlet pressure range of the back pressure regulating unit in the current test and the measured back pressure of the drain line from the pressure sensor at the top of the rewarming coil, so as to control the back pressure of the drain line within the desired range.

[0072] Specifically, the control system performs preliminary adjustments to the driving air pressure control device of the back pressure valve according to the expected inlet pressure range of the back pressure regulating unit in the current test and the functional relationship between the back pressure valve driving air pressure and the back pressure. On this basis, the driving air pressure control device is negatively feedback controlled according to the deviation between the expected value and the measured value of the back pressure in the discharge pipeline, thereby adjusting the back pressure valve and controlling the back pressure in the discharge pipeline within the desired range.

[0073] A pressure sensor is provided between the vaporizer and the back pressure regulating unit. During the test, the driving air pressure control device of the back pressure valve is feedforward controlled according to the difference between the pressure sensor reading at the top of the rewarming coil and the pressure sensor reading, so as to control the discharge back pressure of the cryogenic reciprocating pump more quickly and accurately.

[0074] A pressure reducing device is provided between the back pressure regulating unit and the mass flow meter to reduce the pressure requirements on the downstream pipes, valves, and instruments of the back pressure regulating unit, and the pressure reducing device can meet the pressure reducing requirements under all working fluids to be measured, expected discharge back pressures, and volume flow rates of cryogenic reciprocating pumps;

[0075] A pressure sensor is provided between the back pressure regulating unit and the pressure reducing device. During the test, the optimal flow coefficient range of the back pressure regulating unit in the current test, the opening of the first throttling device and the second throttling device are corrected according to the test working fluid, the mass flow meter reading, and the difference between the expected value or the measured value of the inlet pressure of the back pressure regulating unit and the pressure sensor reading, so as to ensure that the existence of the pressure reducing device does not affect the normal control of the back pressure of the discharge pipeline.

[0076] The present invention also provides a cryogenic reciprocating pump testing system for multiple working fluids and a wide flow range, comprising:

[0077] A module is provided for connecting the discharge port of the cryogenic reciprocating pump to the discharge pipeline in the liquid discharge direction through a rewarming coil with a pressure sensor on the top, a cryogenic one-way valve, a vaporizer, a back pressure regulating unit, and a mass flow meter in sequence;

[0078] A back pressure regulating module is used to realize back pressure control of a discharge pipeline under a multi-working medium and wide flow range by using a back pressure valve, a first throttling device having a maximum flow coefficient smaller than that of the back pressure valve and selectively connected in series with the back pressure valve, a second throttling device having a maximum flow coefficient larger than that of the back pressure valve and selectively connected in parallel with the back pressure valve, a first stop valve for controlling whether the first throttling device is connected in series with the back pressure valve, and a second stop valve for controlling whether the second throttling device is connected in parallel with the back pressure valve;

[0079] The vaporizer design module is used to determine the vaporizer pipeline parameters and heat exchange area in accordance with the principle of meeting the medium compatibility, heat exchange and pressure drop requirements under all test working fluids and test conditions, including: determining the vaporizer material, and the series and parallel connection mode, diameter, total length and heat exchange area of ​​its internal pipelines;

[0080] A back pressure regulating unit design module is used to determine the flow coefficient value range of the back pressure regulating unit according to all possible test working fluids, volume flow rates and expected discharge back pressure ranges, as well as the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, and further determine the maximum flow coefficients of the back pressure valve, the first throttling device and the second throttling device;

[0081] The expected inlet pressure estimation module of the back pressure regulating unit is used to determine the expected inlet pressure range of the back pressure regulating unit in the current test according to the current working fluid to be tested, the theoretical volume flow rate and the expected discharge back pressure before the test;

[0082] The back pressure regulating unit presetting module is used to determine the optimal flow coefficient interval of the back pressure regulating unit in the current test according to the current working fluid to be tested, the theoretical volume flow, the expected inlet pressure range of the back pressure regulating unit, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit before the test, and then determine the connectivity and optimal setting of the first throttling device and the second throttling device;

[0083] The control module is used to pre-control the first throttling device and the second throttling device according to the connectivity and optimal settings determined by the pre-setting module of the back pressure regulating unit before the test, and to adjust the back pressure valve according to the expected inlet pressure range of the back pressure regulating unit in the current test during the test, so as to achieve accurate control of the back pressure of the discharge pipeline.

[0084] Optionally, a pressure reducing device is provided between the back pressure regulating unit and the mass flow meter to reduce the pressure requirement on the downstream pipe section of the back pressure regulating unit.

[0085] Optionally, a pressure sensor is provided between the back pressure regulating unit and the pressure reducing device to measure the outlet pressure of the back pressure regulating unit during the test, and to correct the connectivity and setting of the throttling devices 1 and 2 according to the pressure to ensure that the presence of the pressure reducing device does not affect the control of the back pressure of the discharge pipeline.

[0086] The present invention flexibly combines the back pressure valve and the throttling device so that the same cryogenic reciprocating pump test system can be simultaneously applicable to a variety of cryogenic working fluids and a wide flow range, thereby greatly improving the test efficiency and test system utilization of the cryogenic reciprocating pump and reducing the test cost.

[0087] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0088] like Figure 1 As shown, the present invention provides a method for testing a cryogenic reciprocating pump with a wide flow range and multiple working fluids, comprising:

[0089] S101, connect the discharge port of the cryogenic reciprocating pump in the liquid discharge direction through the rewarming coil with a pressure sensor on the top, the cryogenic one-way valve, the vaporizer, the back pressure regulating unit, and the mass flow meter to the venting pipeline.

[0090] S102, a back pressure valve, a throttling device having a maximum flow coefficient greater than that of the back pressure valve and which can be selectively connected in parallel with the back pressure valve, a throttling device having a maximum flow coefficient less than that of the back pressure valve and which can be selectively connected in series with the back pressure valve, and a plurality of stop valves are arranged in the back pressure regulating unit.

[0091] S103, for all possible test working fluids and test working conditions, determine the pipeline parameters and heat exchange area of ​​the vaporizer according to the medium compatibility, heat exchange and pressure drop requirements.

[0092] S104, determining a possible variation range of the volume flow rate according to the theoretical volume flow rate range and the expected minimum volume efficiency of all the cryogenic reciprocating pumps to be tested.

[0093] S105, for all possible test working fluids and working conditions, calculate and save the pressure drop of the designed gasifier, determine its pressure drop range, and determine the expected inlet pressure range of the back pressure regulating unit in combination with the expected range of change of the drainage back pressure.

[0094] S106, when designing the back pressure regulating unit, the flow coefficient value range of the back pressure regulating unit is determined using the flow formula of the valve based on all possible test working fluids, volume flow range, expected inlet pressure range of the back pressure regulating unit, and equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, and the maximum flow coefficient of the back pressure valve and each throttling device is determined accordingly.

[0095] S107, before the test, according to the current working fluid to be tested, the expected discharge back pressure and the theoretical volume flow, the pressure drop range of the gasifier in the current test is estimated by interpolation based on the stored gasifier pressure drop data, and the expected inlet pressure range of the back pressure regulating unit in the current test is determined accordingly.

[0096] S108, before the test, the optimal flow coefficient range of the back pressure regulating unit in the current test is determined based on the current working fluid to be tested, the theoretical volume flow, the expected inlet pressure range of the back pressure regulating unit, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, and then the connectivity and optimal setting of each throttling device are determined, and pre-control is performed before the test based on this.

[0097] S109, during the test, the back pressure valve is adjusted according to the expected inlet pressure range of the back pressure regulating unit in the current test and the measured drain line back pressure from the pressure sensor at the top of the rewarming coil, so as to control the drain line back pressure within the desired range.

[0098] Combine the following Figure 2 , and each step is described in detail:

[0099] Step S101, connect the discharge port of the cryogenic reciprocating pump to the discharge pipeline in the liquid discharge direction through the rewarming coil with a pressure sensor on the top, the cryogenic one-way valve, the vaporizer, the back pressure regulating unit, and the mass flow meter in sequence, and the specific structure is:

[0100] like Figure 2 As shown, the cryogenic liquid from the cryogenic reciprocating pump inlet pipeline enters the cryogenic reciprocating pump hydraulic end 2 through the cryogenic reciprocating pump inlet hose 1 and is pressurized in the cryogenic reciprocating pump hydraulic end 2. The cryogenic steam generated by vaporization in the cryogenic reciprocating pump inlet chamber or pump pool is led to the cryogenic reciprocating pump return steam pipeline through the cryogenic reciprocating pump return steam hose 3; the cryogenic reciprocating pump hydraulic end 2 is powered by the cryogenic reciprocating pump transmission end 4, and its reciprocating frequency is measured by the reciprocating frequency measuring element 5. The cryogenic liquid pressurized by the hydraulic end 2 of the cryogenic reciprocating pump is discharged from the discharge port 6 of the cryogenic reciprocating pump to the discharge pipeline, and is divided into two paths after passing through the first cryogenic pipeline 7: one path is connected to the first low-pressure release pipeline 30 through the second cryogenic pipeline 8, the cryogenic stop valve 9, the retemperature coil 10, the first normal temperature pipeline 12, the safety valve 13, the second normal temperature pipeline 14, the first pressure reducing valve 15 and the first normal temperature low-pressure pipeline 16 in sequence, wherein the top of the retemperature coil 10 is provided with a first pressure sensor 11 for measuring the discharge back pressure of the cryogenic reciprocating pump; the other path is connected to the first low-pressure release pipeline 30 through the third cryogenic pipeline 17, the cryogenic check valve 18, the fourth cryogenic pipeline 19, the vaporizer 2 0 is heated to a normal temperature fluid, and is connected to the first low-pressure release pipeline 30 through the vaporizer outlet normal temperature pipeline 21, the second pressure sensor 22, the back pressure regulating unit inlet pipeline 23, the back pressure regulating unit 24, the back pressure regulating unit outlet pipeline 25, the third pressure sensor 26, the second pressure reducing valve 27, the second normal temperature low pressure pipeline 28, and the mass flow meter 29; the first low pressure release pipeline 30 is connected to the low pressure release port 35 in the direction of fluid flow through the normal temperature low pressure check valve 31, the second low pressure release pipeline 32, the normal temperature low pressure flame arrester 33, and the third low pressure release pipeline 34, and is discharged into the atmosphere through the low pressure release port 35. Among them, the second pressure sensor 22 and the third pressure sensor 26 are used to measure the inlet and outlet pressures of the back pressure regulating unit 24 respectively, and the first pressure reducing valve 15 and the second pressure reducing valve 27 are used to reduce the pressure requirements of the downstream pipelines, valves and instruments of the back pressure regulating unit 24.

[0101] S102, a back pressure valve, a throttling device having a maximum flow coefficient smaller than that of the back pressure valve and selectively connected in series with the back pressure valve, a throttling device having a maximum flow coefficient larger than that of the back pressure valve and selectively connected in parallel with the back pressure valve, and several stop valves are provided in the back pressure regulating unit, specifically:

[0102] For the back pressure regulating unit 24, the fluid is divided into two primary branches after entering it: the first primary branch is divided into two secondary branches after passing through the back pressure valve inlet pipeline 36, the pneumatic back pressure regulating valve 37 and the back pressure valve outlet pipeline 38 in sequence, one of which is connected to the back pressure regulating unit outlet pipeline 25 after passing through the third normal temperature pipeline 39, the first adjustable opening throttle valve 40 with a maximum flow coefficient smaller than that of the pneumatic back pressure regulating valve 37, and the fourth normal temperature pipeline 41 in sequence, and the other secondary branch is connected to the back pressure regulating unit outlet pipeline 25 after passing through the fifth normal temperature pipeline 4 2. The first pneumatic stop valve 43 with a flow coefficient much larger than that of the pneumatic back pressure regulating valve 37 and the sixth normal temperature pipeline 44 are connected to the back pressure regulating unit outlet pipeline 25; the second primary branch is connected to the back pressure regulating unit outlet pipeline 25 through the seventh normal temperature pipeline 45, the second pneumatic stop valve 46 with a flow coefficient much larger than that of the second adjustable opening throttle valve 48, the eighth normal temperature pipeline 47, the second adjustable opening throttle valve 48 with a maximum flow coefficient larger than that of the pneumatic back pressure regulating valve 37, and the ninth normal temperature pipeline 49. In the above-mentioned back pressure regulating unit 24, whether the pneumatic back pressure regulating valve 37 is connected in series with the first adjustable opening throttle valve 40 is determined by the opening and closing of the first pneumatic stop valve 43, and whether the pneumatic back pressure regulating valve 37 is connected in parallel with the second adjustable opening throttle valve 48 is determined by the opening and closing of the second pneumatic stop valve 46.

[0103] The standard volume flow rate through the back pressure regulating unit 24 can be calculated according to the following formula (1) and formula (2):

[0104]

[0105]

[0106] In formula (1)-(2): Q g is the volume flow of the back pressure regulating unit converted to the standard state, that is, the standard volume flow; N is a constant; C v,bu is the total flow coefficient of the back pressure regulating unit 24; p1 is the inlet pressure of the back pressure regulating unit 24; p2 is the actual outlet pressure of the back pressure regulating unit 24; S g is the molecular weight ratio of the test fluid to the air; T1 is the inlet temperature of the back pressure regulating unit 24; p b is the outlet back pressure of the back pressure regulating unit 24. According to formula (2), when p1<2p b When the back pressure regulating unit does not reach the critical state, p2 takes the outlet back pressure p b , and when p1 ≥ 2p b When the back pressure regulating unit is in a critical state, p2 takes the critical outlet pressure is the average compression factor when the working fluid flows through the back pressure regulating unit 24, yes and function of T1.

[0107] The volume flow rate of the back pressure regulating unit 24 converted to the low temperature reciprocating pump inlet density is:

[0108]

[0109] In formula (3): Q L is the volume flow rate of the back pressure regulating unit 24 converted to the density of the low temperature reciprocating pump inlet liquid; ρ g is the density of the test fluid under standard conditions; ρ L is the density of the test fluid in the low-temperature reciprocating pump inlet state; ρ air is the air density under standard conditions; is the density of liquid nitrogen at 0.1 MPa absolute pressure and 77K temperature; S L To test the ratio of the density of the working fluid in the low temperature reciprocating pump in the liquid state to the density of liquid nitrogen at an absolute pressure of 0.1MPa and a temperature of 77K,

[0110] From formula (3), we can see that for the volume flow rate Q L The same or similar low temperature reciprocating pump, when the working fluid to be tested When the total flow coefficient C is large (such as hydrogen), it is necessary to reduce the total flow coefficient C v,bu ; When the working fluid to be tested When the total flow coefficient C is small (such as argon), it is necessary to increase the total flow coefficient C v,bu In addition, for a specific test fluid (i.e. Basically unchanged), when the volume flow rate of the cryogenic reciprocating pump to be measured is Q L When it is larger, the total flow coefficient C needs to be increased. v,bu ; When the volume flow rate of the cryogenic reciprocating pump to be measured is Q L When it is smaller, the total flow coefficient C needs to be reduced. v,bu .

[0111] From the above analysis, it can be seen that by connecting the first adjustable opening throttle valve 40 in series with the pneumatic back pressure regulating valve 37 and adjusting the opening of the first adjustable opening throttle valve 40, the lower limit of the flow coefficient of the back pressure regulating unit 24 can be quantitatively reduced, so that it can adapt to a smaller volume flow rate and By connecting the second adjustable opening throttle valve 48 in parallel with the pneumatic back pressure regulating valve 37 and adjusting the opening of the second adjustable opening throttle valve 48, the upper limit of the flow coefficient of the back pressure regulating unit 24 can be quantitatively increased, so that it can adapt to a larger volume flow and Therefore, through the flexible series and parallel combination of the pneumatic back pressure regulating valve 37, the first opening adjustable throttle valve 40 and the second opening adjustable throttle valve 48, the volume flow range and the types of working fluids applicable to the same set of low temperature reciprocating pump test system can be greatly broadened.

[0112] For the first pneumatic stop valve 43, when it is disconnected, the pneumatic back pressure regulating valve 37 is connected in series with the first adjustable opening throttle valve 40; when it is closed, the pneumatic back pressure regulating valve 37 and the first adjustable opening throttle valve 40 are short-circuited. For the second pneumatic stop valve 46, when it is disconnected, the pneumatic back pressure regulating valve 37 and the second adjustable opening throttle valve 48 are disconnected; when it is closed, the pneumatic back pressure regulating valve 37 and the second adjustable opening throttle valve 48 are connected in parallel. There is a certain functional relationship between the inlet pressure of the back pressure regulating unit 24 (i.e., the inlet pressure of the pneumatic back pressure regulating valve 37) and the pressure of the back pressure valve driving gas input end 56 (the ratio of the two pressures is usually a constant). By using the programmable pressure controller 53 to adjust the pressure of the back pressure valve driving gas input end 56, the inlet pressure of the back pressure regulating unit 24 and the back pressure of the discharge pipeline can be effectively controlled. The driving gas required by the pneumatic back pressure regulating valve 37 , the first pneumatic stop valve 43 and the second pneumatic stop valve 46 comes from a driving gas source 50 . The driving gas from the driving gas source 50 is divided into two primary branches after passing through the first driving gas pipeline 51: the first primary branch is connected to the back pressure valve driving gas input end 56 through the second driving gas pipeline 52, the programmable pressure controller 53, and the third driving gas pipeline 55 in sequence, and provides driving gas for the pneumatic back pressure regulating valve 37, wherein the output pressure of the programmable pressure controller 53 is controlled by adjusting the input electric signal size of its electric signal input end 54; the second primary branch is divided into two secondary branches after passing through the fourth driving gas pipeline 57, wherein one of the secondary branches is sequentially connected to the first pneumatic stop valve 43 through the fifth driving gas pipeline 58, the first solenoid valve 59 and the first stop valve driving gas input pipeline 60, and the other secondary branch is sequentially connected to the second pneumatic stop valve 46 through the sixth driving gas pipeline 61, the second solenoid valve 62 and the second stop valve driving gas input pipeline 63.

[0113] Step S103, for all possible test working fluids and test working conditions, determine the pipeline parameters and heat exchange area of ​​the gasifier according to the medium compatibility, heat exchange and pressure drop requirements, specifically:

[0114] For the vaporizer 20, the material of the vaporizer is determined according to the principle of satisfying the medium compatibility requirements under all working fluids to be tested, the required heat exchange area of ​​the vaporizer is determined according to the maximum value of the product of the inlet-outlet specific enthalpy difference of the vaporizer and the discharge mass flow rate, and the series and parallel connection mode, diameter, total length and heat exchange area of ​​the internal pipeline of the vaporizer are determined according to the principle that the maximum pressure drop value in all tests is less than the allowable pressure drop and the actual heat exchange area is greater than the required heat exchange area.

[0115] In step S104, the possible variation range of the volume flow rate is determined according to the theoretical volume flow rate range and the expected minimum volume efficiency of all the cryogenic reciprocating pumps to be tested, specifically:

[0116] For a cryogenic reciprocating pump, the following formulas (4) and (5) are used to determine the range of its volume flow rate according to the range of values ​​of its parameters such as stroke volume, reciprocating frequency, number of cylinders, single / double-acting conditions, and the minimum volumetric efficiency of the cryogenic reciprocating pump:

[0117] Q Lp,ideal =N1·N2·(n / 60)·V (4)

[0118]

[0119] In formula (4)-(5): Q Lp,ideal is the theoretical volume flow of the cryogenic reciprocating pump; N1 represents the single / double-acting condition of the cryogenic reciprocating pump, N1=1 represents single-acting, N1=2 represents double-acting; N2 is the number of cylinders; n is the reciprocating frequency, r / min; V is the stroke volume; Q Lp,min and Q Lp,max Respectively represent the minimum and maximum volume flow of the cryogenic reciprocating pump; the functions max and min represent the maximum and minimum values ​​of all tests respectively; η min is the expected minimum volumetric efficiency of a cryogenic reciprocating pump.

[0120] Step S105, for all possible test working fluids and working conditions, calculate and save the pressure drop of the designed gasifier, determine its pressure drop range, and determine the expected inlet pressure range of the back pressure regulating unit in combination with the expected range of change of the drainage back pressure, specifically:

[0121] For the vaporizer 20 designed in the manner described in step S103, for all possible test working fluids and test conditions, the pressure drop values ​​under different working fluids, volume flow rates and discharge back pressures are calculated using an estimation method or a numerical method and saved; on this basis, the pressure drop range of the vaporizer 20 is determined, and combined with the expected discharge back pressure range of the cryogenic reciprocating pump, the expected inlet pressure range of the back pressure regulating unit 24 is determined.

[0122] Step S106, when designing the back pressure regulating unit, according to all possible test working fluids, volume flow range, expected inlet pressure range of the back pressure regulating unit, and equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, the flow formula of the valve is used to determine the value range of the flow coefficient of the back pressure regulating unit, and the maximum flow coefficient of the back pressure valve and each throttling device is determined accordingly, specifically:

[0123] For the back pressure regulating unit 24, according to the volume flow rate Q of the cryogenic reciprocating pump Lp and the possible variation range of the expected inlet pressure p1 of the back pressure regulating unit, and the equivalent flow coefficient C of the downstream pipe section (element 25-35) of the back pressure regulating unit 24 vd , respectively, by solving equations (6)-(8) and (9)-(11) to determine the upper limit C of the flow coefficient of the back pressure regulating unit v,bu,max and the lower limit C v,bu,min :

[0124]

[0125]

[0126]

[0127] In formula (6)-(8): C v,bu,max represents the upper limit of the flow coefficient of the back pressure regulating unit 24; p 1,min Indicates the minimum value of the inlet pressure of the back pressure regulating unit; Indicates that among all the tested working fluids The minimum value of C vd is the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit 24; p atm is the local atmospheric pressure; p 2a 、p oa C v,bu,max The corresponding outlet pressure of the back pressure regulating unit 24 and the actual pressure at the outlet section of the vent 35; and are the average compression factor of the fluid when it flows through the back pressure regulating unit 24 and the average compression factor of the fluid when it flows through the downstream pipe section (element 25-35) of the back pressure regulating unit. When solving equations (6)-(8), first combine equations (7) and (8) to find p 2a and p oa , and then p 2a Substituting back into equation (6) to obtain C v,bu,max .

[0128]

[0129]

[0130]

[0131] In formula (9)-(11): C v,bu,min represents the lower limit of the flow coefficient of the back pressure regulating unit 24; p 1,max Indicates the maximum value of the inlet pressure of the back pressure regulating unit; Indicates that among all the tested working fluids The maximum value of p 2b 、p ob C v,bu,min The corresponding outlet pressure of the back pressure regulating unit 24 and the actual pressure at the outlet section of the vent 35; and are the average compression factor of the fluid when it flows through the back pressure regulating unit 24 and the average compression factor of the fluid when it flows through the downstream pipe section (element 25-35) of the back pressure regulating unit. When solving equations (9)-(11), first combine equations (10) and (11) to obtain p 2b and p ob , and then p 2b Substituting back into equation (9) to obtain C v,bu,min .

[0132] In determining the flow coefficient value range of the back pressure regulating unit 24 [C v,bu,min ,C v,bu,max ], combined with the flow coefficient value ranges of the actually optional pneumatic back pressure regulating valve and the adjustable opening throttle valve, the following formulas (12)-(14) are used to determine the maximum flow coefficients of the pneumatic back pressure regulating valve 37, the first adjustable opening throttle valve 40, and the second adjustable opening throttle valve 48:

[0133]

[0134]

[0135] C v,bu,max =C bv,max +C tv2,max (14)

[0136] In formula (12)-(14): C bv,max is the maximum flow coefficient of the pneumatic back pressure regulating valve 37; C tv1,max and C tv2,max are the maximum flow coefficients of the first adjustable opening throttle valve 40 and the second adjustable opening throttle valve 48 respectively; ψ bv is the ratio of the minimum flow coefficient to the maximum flow coefficient that can be effectively regulated by the pneumatic back pressure regulating valve 37; ψ tv1 is the ratio of the minimum flow coefficient to the maximum flow coefficient that can be effectively regulated by the first adjustable opening throttle valve 40; p bv,tv1is the outlet pressure of the pneumatic back pressure regulating valve 37; and They are respectively the average compression factors of the working medium when it flows through the pneumatic back pressure regulating valve 37 and the first opening adjustable throttle valve 40.

[0137] Step S107, before the test, according to the current working fluid to be tested, the expected drainage back pressure and the theoretical volume flow, the pressure drop range in the current test is estimated based on the stored gasifier pressure drop data interpolation, and the expected inlet pressure range of the back pressure regulating unit in the current test is determined accordingly, specifically:

[0138] Before the test, the volume flow rate variation range in the current test is determined according to the theoretical volume flow rate and the expected minimum volume efficiency of the cryogenic reciprocating pump to be tested. Then, according to the working fluid, the expected discharge back pressure, and the volume flow rate variation range of the current test, the pressure drop range [Δp vap,min ,Δp vap,max ]; on this basis, combined with the expected discharge back pressure range [p′ op,exp，min ,p′ op,exp，max ] and its maximum allowable error |Δp′ err |, the expected inlet pressure range of the back pressure regulating unit 24 in the current test is determined using the following formula (15):

[0139]

[0140] In formula (15): Δp vap,max and Δp vap,min are the maximum and minimum pressure drops of the gasifier in the current test; Δp vap is the vaporizer pressure drop; P′ op is the back pressure of the discharge pipeline; p' op,exp，max and p′ op,exp，min are the maximum and minimum values ​​of the expected discharge back pressure in the current test, respectively. When the test is expected to be carried out under a constant discharge back pressure, p′ op,exp，max =p′ op,exp，min ; |Δp′ err | is the maximum allowable error of the discharge back pressure of the cryogenic reciprocating pump; Q′ Lp , Q′ Lp,ideal ,η′ min They are respectively the actual volume flow, theoretical volume flow and estimated minimum volume efficiency of the cryogenic reciprocating pump to be tested; Indicates the discharge back pressure P′ op =p′ op,exp，max +|Δp′ err |, Volume flow rate Q′ Lp =η′ min Q′Lp,ideal The pressure drop of the gasifier 20 calculated by interpolation under the condition of Indicates the discharge back pressure P′ op =p′ op,exp，min -|Δp′ err |, volume flow rate Q′ Lp =Q′ Lp,ideal The pressure drop of the gasifier 20 calculated by interpolation under the condition of 1,exp,max and p′ 1,exp,min They are respectively the expected maximum and minimum inlet pressures of the back pressure regulating unit 24 in the current test.

[0141] S108, before the test, the optimal flow coefficient range of the back pressure regulating unit in the current test is determined according to the current working fluid to be tested, the theoretical volume flow, the expected inlet pressure range of the back pressure regulating unit, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, and then the connectivity and optimal setting of each throttling device are determined, and pre-control before the test is performed accordingly, specifically:

[0142] On this basis, for the designed back pressure regulating unit 24, according to the working fluid, volume flow range, expected inlet pressure range of the back pressure regulating unit, and the equivalent flow coefficient of the downstream pipe section (elements 25-35) of the back pressure regulating unit 24, the upper limit of the optimal flow coefficient interval of the back pressure regulating unit in the current test is calculated using equations (16)-(18), and the lower limit of the optimal flow coefficient interval of the back pressure regulating unit in the current test is calculated using equations (19)-(21):

[0143]

[0144]

[0145]

[0146] In formula (16)-(18): C v ' ,bu,max Indicates the upper limit of the optimal flow coefficient range of the back pressure regulating unit 24 in the current test; S′ g and S L ′ respectively represent the S of the working fluid to be tested g and S L ; p′ 2a Indicates that the current test is C v ' ,bu,max The corresponding outlet pressure of the back pressure regulating unit 24; p o ' a Indicates that the current test is C v ' ,bu,max The corresponding pressure at the outlet section of the low-pressure relief port 35; Indicates that the current test is C v ' ,bu,max The average compression factor of the corresponding fluid when it flows through the back pressure regulating unit 24; Indicates that the current test is C v ' ,bu,max The average compression factor of the corresponding fluid when it flows through the downstream pipe section (elements 25-35) of the back pressure regulating unit 24.

[0147]

[0148]

[0149]

[0150] In formula (19)-(21): C' v,bu,min represents the lower limit of the optimal flow coefficient range of the back pressure regulating unit 24 in the current test; p′ 2b Indicates C′ in the current test v,bu,min The corresponding outlet pressure of the back pressure regulating unit 24; p' ob Indicates C′ in the current test v,bu,min The corresponding pressure at the outlet section of the low-pressure relief port 35; Indicates C′ in the current test v,bu,min The average compression factor of the corresponding fluid when it flows through the back pressure regulating unit 24; Indicates C′ in the current test v,bu,min The average compression factor of the corresponding fluid when it flows through the downstream pipe section (elements 25-35) of the back pressure regulating unit 24.

[0151] For the current test, the optimal flow coefficient interval [C′ v,bu,min ,C′ v,bu,max ], the connectivity of the first opening adjustable throttle valve 40 and the second opening adjustable throttle valve 48 in the current test is determined in the following manner:

[0152] 1) When the maximum flow coefficient of the pneumatic back pressure regulating valve 37 is greater than the upper limit of the optimal flow coefficient interval of the current test, and the adjustable minimum flow coefficient of the pneumatic back pressure regulating valve 37 is less than the lower limit of the optimal flow coefficient interval of the current test, that is, C bv,max ≥C′ v,bu,max , ψ bv ·C bv,max ≤C′ v,bu,min, the requirement of the current test on the flow coefficient can be met by relying solely on the pneumatic back pressure regulating valve 37, without using the first adjustable opening throttle valve 40 and the second adjustable opening throttle valve 48. At this time, the first pneumatic stop valve 43 is opened to short-circuit the first adjustable opening throttle valve 40, and the second pneumatic stop valve 46 is closed at the same time to disconnect the branch where the second adjustable opening throttle valve 48 is located;

[0153] 2) When the maximum flow coefficient and the adjustable minimum flow coefficient of the pneumatic back pressure regulating valve 37 are respectively greater than the upper limit and lower limit of the optimal flow coefficient range of the current test, that is, C bv,max ≥C′ v,bu,max , ψ bv ·C bv,max >C′ v,bu,min , relying solely on the pneumatic back pressure regulating valve 37 can reach the upper limit of the optimal flow coefficient interval in the current test, but cannot reach the lower limit of the optimal flow coefficient interval in the current test. At this time, it is necessary to close the first pneumatic stop valve 43, so that the pneumatic back pressure regulating valve 37 is connected in series with the first adjustable opening throttle valve 40, and at the same time close the second pneumatic stop valve 46, so that the branch where the second adjustable opening throttle valve 48 is located is disconnected;

[0154] 3) When the maximum flow coefficient and the adjustable minimum flow coefficient of the pneumatic back pressure regulating valve 37 are respectively less than the upper limit and the lower limit of the optimal flow coefficient range of the current test, that is, C bv,max <C′ v,bu,max , ψ bv ·C bv,max ≤C′ v,bu,min , relying solely on the pneumatic back pressure regulating valve 37 can reach the lower limit of the optimal flow coefficient interval in the current test, but cannot reach the upper limit of the optimal flow coefficient interval in the current test. At this time, it is necessary to open the first pneumatic stop valve 43 to short-circuit the first adjustable throttle valve 40, and at the same time open the second pneumatic stop valve 46 to connect the pneumatic back pressure regulating valve 37 in parallel with the second adjustable throttle valve 48;

[0155] 4) When the maximum flow coefficient of the pneumatic back pressure regulating valve 37 is less than the upper limit of the optimal flow coefficient interval of the current test, and its adjustable minimum flow coefficient is greater than the lower limit of the optimal flow coefficient interval of the current test, that is, C bv,max <C′ v,bu,max , ψ bv ·C bv,max >C′ v,bu,min , relying solely on the pneumatic back pressure regulating valve 37 can neither reach the upper limit nor the lower limit of the optimal flow coefficient range. At this time, it is necessary to close the first pneumatic stop valve 43 and open the second pneumatic stop valve 46 at the same time, so that the pneumatic back pressure regulating valve 37 is connected in series with the first adjustable opening throttle valve 40 and in parallel with the second adjustable opening throttle valve 48.

[0156] On this basis, according to the optimal flow coefficient range [C′] of the back pressure regulating unit 24 in the current test determined above, v,bu,min ,C′ v,bu,max ], and the connectivity of the first adjustable opening throttle valves 40 and 48, by solving valve series / parallel flow equations similar to equations (12)-(14), the optimal flow coefficient and the optimal opening of the first adjustable opening throttle valves 40 and 48 in the current test can be finally determined. Before the test begins, the control system 64 performs pre-control according to the connectivity and the optimal opening of the first adjustable opening throttle valves 40 and 48.

[0157] Step S109, during the test, according to the expected inlet pressure range of the back pressure regulating unit in the current test and the measured back pressure of the drain line from the pressure sensor at the top of the rewarming coil, the back pressure valve is adjusted to control the back pressure of the drain line within the desired range, specifically:

[0158] During the test, the control system 64 performs preliminary control on the input current of the electrical signal input terminal 54 of the pressure controller according to the expected inlet pressure range of the back pressure regulating unit 24 in the current test and the proportional relationship between the inlet pressure of the pneumatic back pressure regulating valve 37 and the driving air pressure; on this basis, the drainage pipeline back pressure actually measured by the first pressure sensor 11 at the top of the rewarming coil 10 is compared with the expected drainage back pressure, and the input current of the electrical signal input terminal 54 of the pressure controller is accurately feedback controlled, so as to control the drainage pipeline back pressure within the desired range.

[0159] The present invention uses a flexible series-parallel combination between the back pressure regulating valve and the throttling device, so that the same low-temperature reciprocating pump test system can be simultaneously applicable to a variety of working fluids and a wide flow range, greatly improving the test efficiency and test system utilization of the low-temperature reciprocating pump and reducing the test cost.

[0160] In order to execute the methods corresponding to the above embodiments and achieve corresponding functions and technical effects, the present invention also provides a cryogenic reciprocating pump measurement system for multiple working fluids and a wide flow range, comprising:

[0161] A module is provided for connecting the discharge port of the cryogenic reciprocating pump in the liquid discharge direction through a rewarming coil with a pressure sensor on the top, a one-way valve, a vaporizer, a back pressure regulating unit, a mass flow meter and a venting pipeline in sequence;

[0162] A back pressure regulating module is used to realize back pressure control of a discharge pipeline under a multi-media and wide flow range by using a back pressure valve, a throttling device having a maximum flow coefficient smaller than the back pressure valve and selectively connected in series with the back pressure valve, a throttling device having a maximum flow coefficient larger than the back pressure valve and selectively connected in parallel with the back pressure valve, and several automatic stop valves;

[0163] The vaporizer design module is used to determine the vaporizer material, the series and parallel connection mode, diameter, total length and heat exchange area of ​​the internal pipelines in accordance with the principle of meeting the medium compatibility, heat exchange and pressure drop requirements under all test working fluids and test conditions;

[0164] The back pressure regulating unit design module is used to determine the flow coefficient value range of the back pressure regulating unit according to all possible test working fluids, volume flow rates and expected discharge back pressure ranges, as well as the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, and further determine the maximum flow coefficients of the back pressure valve and each throttling device therein;

[0165] The expected inlet pressure estimation module of the back pressure regulating unit is used to determine the expected inlet pressure range of the back pressure regulating unit in the current test according to the current working fluid to be tested, the theoretical volume flow rate and the expected discharge back pressure before the test;

[0166] The back pressure regulating unit presetting module is used to determine the connectivity and optimal settings of each throttling device in the current test according to the current working fluid to be tested, the theoretical volume flow, the expected inlet pressure range of the back pressure regulating unit, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit before the test;

[0167] The control module is used to pre-control the connectivity and optimal settings of each throttling device determined by the pre-setting module of the back pressure regulating unit before the test, and to adjust the back pressure valve according to the expected inlet pressure range of the back pressure regulating unit in the current test during the test, so as to achieve accurate control of the back pressure of the discharge pipeline.

[0168] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0169] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for testing a cryogenic reciprocating pump with multiple working fluids and a wide flow range, characterized in that: include: Step S101, connecting the discharge port of the cryogenic reciprocating pump to the discharge pipeline in the liquid discharge direction through the rewarming coil with a pressure sensor on the top, the cryogenic one-way valve, the vaporizer, the back pressure regulating unit, and the mass flow meter in sequence; Step S102, in the back pressure regulating unit, a back pressure valve, a first throttling device having a maximum flow coefficient smaller than that of the back pressure valve and selectively connected in series with the back pressure valve, a second throttling device having a maximum flow coefficient larger than that of the back pressure valve and selectively connected in parallel with the back pressure valve, a first stop valve for controlling whether the first throttling device is connected in series with the back pressure valve, and a second stop valve for controlling whether the second throttling device is connected in parallel with the back pressure valve are provided; Step S103, determining the pipeline parameters and heat exchange area of ​​the gasifier according to the medium compatibility, heat exchange and pressure drop requirements for all possible test working media and test working conditions; Step S104, determining a volume flow rate variation range according to the theoretical volume flow rate range and the expected minimum volume efficiency of all cryogenic reciprocating pumps to be tested; Step S105, for all possible test working fluids and test working conditions, calculate and save the pressure drop of the gasifier designed in step S103 under different working fluids, volume flow rates and drainage back pressures, obtain the pressure drop range of the gasifier, and determine the expected inlet pressure range of the back pressure regulating unit in combination with the expected variation range of the drainage back pressure; Step S106, when designing the back pressure regulating unit, according to all possible test working fluids, the volume flow rate variation range, the expected inlet pressure range of the back pressure regulating unit, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, the flow formula of the valve is used to determine the value range of the flow coefficient of the back pressure regulating unit, and the maximum flow coefficient of the back pressure valve, the first throttling device and the second throttling device is determined accordingly; Step S107, before the test, according to the current working fluid to be tested, the expected drainage back pressure and the theoretical volume flow rate, the pressure drop range of the gasifier in the current test is estimated by interpolation based on the gasifier pressure drop data saved in step S105, and the expected inlet pressure range of the back pressure regulating unit in the current test is determined accordingly; Step S108, before the test, according to the current working fluid to be tested, the theoretical volume flow, the expected inlet pressure range of the back pressure regulating unit obtained in step S107, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, determine the optimal flow coefficient range of the back pressure regulating unit in the current test, and then determine the connectivity and optimal settings of the first throttling device and the second throttling device, and perform pre-control before the test accordingly; wherein the optimal settings include the optimal flow coefficient and valve opening; Step S109, during the test, the back pressure valve is adjusted according to the expected inlet pressure range of the back pressure regulating unit in the current test and the measured back pressure of the drain line from the pressure sensor at the top of the rewarming coil, so as to control the back pressure of the drain line within the desired range.

2. A method for testing a cryogenic reciprocating pump with multiple working fluids and a wide flow range according to claim 1, characterized in that: Step S103 is specifically as follows: The material of the vaporizer shall be determined according to the principle of meeting the medium compatibility requirements under all working fluids to be tested; The required heat exchange area of ​​the vaporizer is determined according to the maximum value of the product of the inlet-outlet specific enthalpy difference of the vaporizer and the discharge mass flow rate; According to the principle that the maximum pressure drop value under all test working fluids and test conditions is less than the allowable pressure drop and the actual heat exchange area is larger than the required heat exchange area, the series and parallel connection mode, diameter, total length and heat exchange area of ​​the internal pipeline of the vaporizer are determined to determine the pipeline parameters and heat exchange area of ​​the vaporizer.

3. A method for testing a cryogenic reciprocating pump with multiple working fluids and a wide flow range according to claim 1, characterized in that: In step S108, the optimal flow coefficient range of the back pressure regulating unit in the current test is determined, specifically: Before the test, the upper limit of the optimal flow coefficient range of the back pressure regulating unit in the current test is determined according to the expected lower limit of the inlet pressure of the back pressure regulating unit in the current test and the theoretical volume flow of the cryogenic reciprocating pump to be tested; The lower limit of the optimal flow coefficient range of the back pressure regulating unit in the current test is determined based on the expected inlet pressure upper limit of the back pressure regulating unit in the current test, the product of the theoretical volume flow of the cryogenic reciprocating pump to be tested and the expected minimum volumetric efficiency.

4. A method for testing a cryogenic reciprocating pump with multiple working fluids and a wide flow range according to claim 1, characterized in that: In step S108, the connectivity and optimal settings of the first throttling device and the second throttling device are determined, and pre-control before the test is performed accordingly, specifically: When and only when the minimum flow coefficient within the adjustable range of the back pressure valve is greater than the lower limit of the optimal flow coefficient interval of the back pressure regulating unit, the first throttling device having a maximum flow coefficient smaller than the back pressure valve is connected in series with the back pressure valve; When and only when the maximum flow coefficient of the back pressure valve is less than the upper limit of the optimal flow coefficient interval of the back pressure regulating unit, a second throttling device having a maximum flow coefficient greater than that of the back pressure valve is connected in parallel with the back pressure valve; After determining the connectivity of the first throttling device and the second throttling device according to the above principle, determine the best settings of the first throttling device and the second throttling device in the current test according to the calculation method of the equivalent flow coefficient after the gas valves are connected in series and parallel; On this basis, the first throttling device and the second throttling device are pre-controlled before testing according to the determined connectivity and optimal settings of the first throttling device and the second throttling device.

5. A cryogenic reciprocating pump test system for multiple working fluids and a wide flow range, characterized in that: include: A module is provided for connecting the discharge port of the cryogenic reciprocating pump to the discharge pipeline in the liquid discharge direction through a rewarming coil with a pressure sensor on the top, a cryogenic one-way valve, a vaporizer, a back pressure regulating unit, and a mass flow meter in sequence; A back pressure regulating module is used to realize back pressure control of a discharge pipeline under a multi-media and wide flow range by using a back pressure valve, a first throttling device having a maximum flow coefficient smaller than that of the back pressure valve and selectively connected in series with the back pressure valve, a second throttling device having a maximum flow coefficient larger than that of the back pressure valve and selectively connected in parallel with the back pressure valve, a first stop valve for controlling whether the first throttling device is connected in series with the back pressure valve, and a second stop valve for controlling whether the second throttling device is connected in parallel with the back pressure valve; The vaporizer design module is used to determine the vaporizer piping parameters and heat exchange area according to the principle of meeting the medium compatibility, heat exchange and pressure drop requirements under all test working fluids and test conditions; A back pressure regulating unit design module is used to determine the flow coefficient value range of the back pressure regulating unit according to all possible test working fluids, volume flow rates and expected discharge back pressure ranges, as well as the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit, and further determine the maximum flow coefficients of the back pressure valve, the first throttling device and the second throttling device; The expected inlet pressure estimation module of the back pressure regulating unit is used to determine the expected inlet pressure range of the back pressure regulating unit in the current test according to the current working fluid to be tested, the theoretical volume flow rate and the expected discharge back pressure before the test; The back pressure regulating unit presetting module is used to determine the optimal flow coefficient interval of the back pressure regulating unit in the current test according to the current working fluid to be tested, the theoretical volume flow, the expected inlet pressure range of the back pressure regulating unit, and the equivalent flow coefficient of the downstream pipe section of the back pressure regulating unit before the test, and then determine the connectivity and optimal setting of the first throttling device and the second throttling device; wherein the optimal setting includes the optimal flow coefficient and valve opening; The control module is used to pre-control the first throttling device and the second throttling device according to the connectivity and optimal settings determined by the pre-setting module of the back pressure regulating unit before the test, and to adjust the back pressure valve according to the expected inlet pressure range of the back pressure regulating unit in the current test during the test to achieve control of the back pressure of the discharge pipeline.

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