Gamma ray density measurement device and method for high-temperature and high-pressure hydrocarbon fuel

Abstract

The present invention discloses a gamma-ray density measurement device and method for high-temperature and high-pressure hydrocarbon fuels, which includes fixing a gamma-ray density measurement experimental section pipeline, a gamma-ray radiation source and a shielding cover, and a radiation detector on a fixed platform. A lead collimator and a heat insulation plate are arranged coaxially between the gamma-ray density measurement experimental section pipeline and the gamma-ray radiation source and shielding cover and the radiation detection receiver; pressure transmitters and thermocouples are installed at the inlet and outlet of the gamma-ray density measurement experimental section pipeline; the inlet pipeline of the gamma-ray density measurement experimental section pipeline is connected to the preheating and heating section of the fluid to be measured in the high-temperature and high-pressure liquid generation and control system, and the outlet pipeline is connected to the cooling and treatment section in the high-temperature and high-pressure liquid generation and control system. The present invention can not only eliminate the influence of temperature on the experimental section pipeline and realize the on-line measurement of the fluid density under high temperature and high pressure, but also pre-obtain the mass absorption rate of the measured substance by the ray method.

Description

Technical Field

[0001] The present invention relates to the technical fields of fluid thermal property measurement and regenerative cooling technology for liquid rocket engines, and particularly relates to a gamma-ray density measurement device and method for high-temperature and high-pressure hydrocarbon fuels. Background Art

[0002] Fluid thermal property measurement technologies are widely used in industrial production processes such as petroleum, chemical industry, nuclear energy, refrigeration, and metallurgy. As an important physical property parameter of fluids, density is an important indicator for evaluating the regenerative cooling performance of hydrocarbon fuels. Especially in the research on flow and heat transfer characteristics under high-temperature, high-pressure, and large-flow conditions, combined with the continuous change of the state of hydrocarbon fuels along the engine cooling channels and the continuous change of chemical reaction components at high temperatures, experimental methods have become the main choice for obtaining the thermophysical properties of hydrocarbon fuels under harsh conditions, and at the same time, the experimental methods must also meet the requirements of on-line measurement. Therefore, density measurement technology is the focus of fluid thermal property measurement technology.

[0003] Density measurement methods are classified into two categories according to the measurement method: one is the direct measurement method that directly contacts the fluid to be measured, including the static weighing method, density bottle method, suspension method, hydrometer method, etc.; the other is the indirect measurement method that does not directly contact the fluid to be measured, and common ones include the vibration method, ray method, acoustic method, optical method, electrical method, chromatography method, etc. In the field of regenerative cooling technology for liquid rocket engines, the density measurement of fluids is also accompanied by harsh conditions such as high temperature, high pressure, and the change of chemical reaction components at high temperatures.

[0004] Under high-temperature and high-pressure conditions, an indirect measurement method needs to be used to obtain the density of the fluid. The vibrating tube method is the most commonly used high-temperature and high-pressure density measurement method at present. The working principle of the vibrating tube density measurement method is based on the relationship between the vibration frequency of a substance and the vibrating mass. During the vibration process, the total mass changes, causing the natural frequency of the entire system to change, and the density value of the measured liquid is obtained by calculation. It has the advantages of fast measurement speed, high accuracy, and convenient operation; disadvantages: the resistance of the liquid inside the vibrating tube is large, the pressure loss is high, and it is also greatly affected by the ambient temperature. It cannot measure the density of the fluid to be measured when the temperature exceeds 200 °C, and it also cannot measure when the temperature of the fluid to be measured is below 0 °C due to ice formation outside the vibrating tube.

[0005] The ray method can be applied to a wide temperature range and ultra-high pressure. The ray method density measurement device is non-contact, and the density measurement is not affected by temperature and pressure. The ray method is one of the commonly used methods for measuring liquid density. The principle is that during the decay of radioactive isotopes, the outward radiated rays pass through the medium. The ray intensity will change according to the change of liquid density. It is a measurement method that measures the fluid density through the relationship between the ray attenuation intensity and the fluid density. According to the different types of rays emitted by the ray source, they mainly include gamma rays, X-rays, neutron rays, etc. The ray method is a non-contact measurement method. Since the ray attenuation is not affected by external conditions, it has high stability; Disadvantages: In terms of operability, certain protection against ray radiation is required to ensure personnel safety; The high temperature of the experimental section pipeline will cause errors in the measurement results; For unknown fluids to be measured, it is necessary to obtain their mass absorption rate in advance to compare with standard fluids.

[0006] The high-temperature and high-pressure density measurement of hydrocarbon fuels has the characteristics of ultra-high pressure, complex composition and chemical reactions. At present, there are few public reports on the density measurement devices and methods of hydrocarbon fuels under ultra-high pressure and high temperature conditions, especially the fluid density data under complex conditions accompanied by chemical reactions is difficult to obtain. Summary of the invention

[0007] In order to overcome the above technical problems, the present invention proposes a gamma-ray density measurement device and method for high-temperature and high-pressure hydrocarbon fuels, which can not only eliminate the influence of temperature on the experimental section pipeline and realize online measurement of fluid density under high temperature and high pressure; but also obtain the mass absorption rate of the measured substance in advance through the ray method, which can be used for the density measurement of hydrocarbon substances with unknown composition.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A gamma-ray density measuring device for high-temperature and high-pressure hydrocarbon fuels comprises a fixed platform 1, on which an experimental section pipeline 2, a gamma-ray radiation source and a shielding cover 3, and a radiation detector 4 are fixed through a supporting column, and a lead block collimator 5 and a heat shield 6 are coaxially arranged between the experimental section pipeline 2, the gamma-ray radiation source and the shielding cover 3, and the radiation detector 4;

[0010] The experimental section pipeline 2 includes three parts: the inlet pipeline, the gamma ray penetration pipeline and the outlet pipeline;

[0011] Pressure transmitters 7 and thermocouples 8 are installed at the inlet and outlet of the experimental section pipeline 2, and thermal insulation cotton 12 and mica heating sheets 13 are arranged outside the experimental section pipeline 2;

[0012] The radiation detector 4 includes a CsI scintillation base 9, a signal amplifier 10, and a data processing and output device 11. The data processing and output device 11 is connected to the input end of the data acquisition device 14; the inlet pipeline of the experimental section pipeline 2 is connected to the preheating and heating section of the fluid to be measured in the high-temperature and high-pressure liquid generation and control system, and the outlet pipeline is connected to the cooling and treatment section in the high-temperature and high-pressure liquid generation and control system.

[0013] The high-temperature and high-pressure liquid generation and control system includes a storage tank 15 for storing the fluid to be measured. The lower end outlet is connected to the inlet of a filter 16. The outlet of the filter 16 is connected to the inlet of a high-pressure constant flow pump 17. The outlet of the high-pressure constant flow pump 17 is connected to the inlet of a mass flowmeter 18. The outlet of the mass flowmeter 18 is connected to the inlet of an insulating joint 19. The inlet of the insulating joint 19 is connected to the inlet of a preheating section pipeline 20. The outlet of the preheating section pipeline 20 is connected to a gamma-ray density measuring device 22; the gamma-ray density measuring device 22 is connected to the pipeline after measurement in the experimental section. The outlet of the gamma-ray density measuring device 22 is connected to the inlet of a high-temperature filter 16. The outlet of the high-temperature filter 16 is connected to the inlet of a shell-and-tube heat exchanger 23. The outlet of the shell-and-tube heat exchanger 23 is connected to the inlet of the insulating joint 19. The outlet of the insulating joint 19 is connected to the inlet of a back pressure valve 25. The outlet of the back pressure valve 25 is connected to the inlet of a tail gas separation and treatment device 26. The outlet of the tail gas separation and treatment device 26 returns to the waste liquid tank 27.

[0014] The inlet of the preheating section pipeline 20 is connected to one end output of an AC constant current power supply 21, and the outlet of the preheating section pipeline 20 is connected to one end output of the AC constant current power supply 21; the heating voltage U and heating current I at both ends of the preheating section pipeline 20 are obtained by the voltage sensor and current sensor carried by the AC constant current power supply 21, and the heating power P is calculated by multiplying the heating voltage and heating current. Insulating joints 19 are connected before the preheating section pipeline 20 and after the shell-and-tube heat exchanger 23 to prevent the heating current from conducting to other positions outside the experimental pipeline.

[0015] The shell side outlet of the shell-and-tube heat exchanger 23 is connected to the inlet of an industrial air-cooled chiller 24, and the outlet of the industrial air-cooled chiller 24 is connected to the shell side inlet of the shell-and-tube heat exchanger 23.

[0016] A mass flowmeter 18 is provided between the high-pressure constant flow pump 17 and the insulating joint 19. Thermocouples 8 are provided at the inlet and outlet of the preheating section pipeline 20, and thermocouples 8 are provided at the inlet and outlet of the experimental section pipeline 2. A pressure transmitter 7 is provided between the outlet of the preheating section pipeline 20 and the inlet of the experimental section pipeline 2; the signals of the mass flowmeter 18, pressure transmitter 7, and thermocouple 8 are output to a data acquisition board 28.

[0017] The data outputs of the data acquisition device 14 and the data acquisition board 28 are connected to an industrial control computer 29, and the thermal parameters and counting rate are displayed through the industrial control computer 29.

[0018] A method for installing a gamma-ray density measuring device for high-temperature and high-pressure hydrocarbon fuels, comprising the following steps:

[0019] Step 1: Adjust the fixed platform 1 so that it is tightly connected to the ground, and use a horizontal bubble level meter to make the fixed platform 1 within a 1° range of horizontality, to ensure that the rays emitted by the ray source can horizontally pass through the experimental section pipe 2 without leaking out;

[0020] Step 2: Install the experimental section pipe 2 in the middle of the fixed platform 1, closely arrange mica heating sheets 13 on the upper and lower surfaces of the experimental section pipe 2, and wrap 5-10 mm insulation cotton 12 around the mica heating sheets 13 to reduce heat dissipation and reduce the inlet and outlet temperature difference;

[0021] Step 3: Arrange a gamma ray radiation source with a shielding lead tank and a shielding cover 3 on one side of the fixed platform 1, and a radiation detector 4 on the other side, so that the ray emission and receiving directions are on the same horizontal line;

[0022] Step 4: Select a lead block collimator 5 and a heat shield 6 of the same diameter according to the diameter of the experimental section pipeline 2, and place them at the outlet of the gamma ray radiation source and shielding cover 3 and the front end of the radiation detector 4 respectively;

[0023] Step 5: Select a suitable standard density fluid (such as n-decane, toluene or cyclohexane, etc.) with similar physical properties to the fluid to be measured to calibrate the gamma ray density measuring device 22 in terms of counting rate; by controlling the generation and control system of high-temperature and high-pressure liquid, select a temperature range of 25°C to 400°C at room temperature to eliminate the influence of temperature on gamma ray density measurement;

[0024] Step 6: By comparing the count rate difference between the standard density fluid and the fluid to be measured in the gamma ray density measuring device 22, combined with the density measurement of the fluid to be measured at normal temperature and pressure, the mass absorption rate of the measured substance can be obtained in advance;

[0025] Step 7: Adjust the back pressure valve 25 at the outlet of the system pipeline to make the system pressure reach the preset value; start the AC constant current power supply 21, heat the preheating section pipeline 20 until the inlet and outlet temperature thermocouple 8 of the experimental section reaches the predetermined measurement value; turn on the gamma ray radiation source and the shielding cover 3 and the radiation detector 4, and measure the density of the fluid to be measured at the working point to be measured.

[0026] A method for measuring the gamma ray density of a high-temperature and high-pressure hydrocarbon fuel comprises: (1) eliminating the influence of temperature on the gamma ray density measuring device; (2) using the mass absorption coefficient ratio of the fluid to be measured and the standard density fluid to correct the density calculation of the fluid to be measured;

[0027] (1) Eliminate the influence of temperature on the gamma ray density measurement device:

[0028] When the temperature of the fluid to be measured is at a high temperature, considering the influence of the expansion and deformation of the lead collimator 5 and the heat insulation plate 6 of the gamma-ray density measurement device at high temperature on the experimental measurement, it is necessary to eliminate the influence of the fluid to be measured at high temperature on the gamma-ray density measurement device. It is necessary to verify the dimensionless count rate characteristics of the density measurement test section affected by temperature for standard density fluids with different densities at high temperature:

[0029]

[0030] Among them: Φ—dimensionless count rate; Φ m —count rate of the fluid to be measured; Φ H —count rate of the high-density standard fluid; Φ L —count rate of the low-density standard fluid. The dimensionless count rate characterizes the magnitude relationship between the count rate of the fluid to be measured and the count rates of the high-density standard fluid and the low-density standard fluid. Through experimental verification, using a high-temperature fluid as the low-density standard fluid can eliminate the influence of temperature on the count rate characteristics of the density measurement device. Therefore, the ray count rate of the low-density standard fluid simultaneously includes the radiation intensity absorbed by the fluid and the radiation intensity that changes due to the influence of temperature on the ray device, thereby offsetting the influence of temperature on the count rate of the density measurement device;

[0031] (2) Calculate the density of the fluid to be measured by correcting with the mass absorption coefficient:

[0032] The radiation intensity measured by the gamma-ray radiation source and the shielding cover 3 and the radiation detector 4 is I m , and the average number of particles collected by the radiation detector 4 in 1 minute is recorded as the count rate Φ m of the fluid to be measured. By calculating with the density ρ c of the standard fluid, the density ρ m of the fluid to be measured can be obtained. The calculation formula of ρ m is obtained through the following steps:

[0033] By comparing the different ray intensities of the fluid to be measured with the high-density standard fluid and the low-density standard fluid, the density ρ m0 at normal temperature and pressure is obtained:

[0034]

[0035] Among them: ρ m0 —density value measured by the ray method at normal temperature and pressure; ρ H —density of the high-density standard fluid; ρ L —density of the low-density standard fluid; I m —intensity of the ray passing through the fluid to be measured; I H —intensity of the ray passing through the high-density fluid; I L—The intensity of the ray passing through the low-density fluid;

[0036] Then, after measuring by a float densitometer and obtaining the true density of rocket kerosene at normal temperature and pressure, the ratio of the mass absorption coefficient of rocket kerosene to that of the standard density fluid can be obtained:

[0037]

[0038] Where: μ c —The mass absorption coefficients of the high-density and low-density standard fluids; μ m —The mass absorption coefficient of the fluid to be measured; ρ ms —The true density of the fluid to be measured at normal temperature and pressure; ρ m0 —The density value measured by the ray method at normal temperature and pressure.

[0039] During the measurement process, the counting mode is adopted to replace the measurement of the ray intensity. The counting rate is the number of received particles per unit time and is proportional to the intensity of the ray in the receiving area. Therefore, the ratio of the counting rates recorded by the scintillation counter for 1 min is selected instead of the ratio of the ray intensities in the calculation. Then the calculation formula for ρ m is as follows:

[0040]

[0041] Where: ρ—the corrected value of the density measurement of the fluid to be measured; Φ m —The counting rate of the fluid to be measured; Φ H —The counting rate of the high-density standard fluid; Φ L —The counting rate of the low-density standard fluid. Kerosene-based hydrocarbon fuels have complex compositions with hundreds or thousands of components. It is difficult to obtain their precise molecular formulas through conventional methods. For fluids to be measured with different compositions, by measuring the true density at normal temperature and pressure and the density value measured by the ray method at normal temperature and pressure, the mass absorption rates of different types of hydrocarbon fuels can be quickly corrected.

[0042] A gamma-ray density measurement method for high-temperature and high-pressure hydrocarbon fuels, and its specific measurement steps are as follows:

[0043] 1) Select appropriate standard density fluids to be measured (such as n-dodecane, n-decane, cyclohexane, or toluene, etc.) according to the physical properties of the fluid to be measured. First, measure the counting rates of the standard fluids and eliminate the influence of temperature on the gamma-ray density measurement device in the above way; use high-temperature fluids as low-density standard fluids and use normal-temperature and high-pressure fluids as high-density standard fluids; record the counting rate when the gamma-ray radiation source and the shielding cover 3 are not opened as the environmental background counting rate;

[0044] 2) Turn on the high-pressure constant-current pump 17, fill the gamma-ray density measurement system with a standard density fluid, and measure the temperature and pressure inside the experimental section pipeline 2 through the pressure transmitter 7 and the thermocouple 8; control the temperature of the experimental section pipeline 2 by changing the heating power of the alternating current constant-current power supply 21, and control the pressure of the experimental section pipeline 2 in the gamma-ray density measurement device 22 by changing the tightness of the back-pressure valve 25; change different working conditions, repeat the measurement enough times, and conduct calibration tests on the high-density standard fluid density and the low-density standard fluid density respectively;

[0045] 3) After measuring the true density of the fluid to be measured at normal temperature and pressure through the float density meter, and then measuring the gamma-ray method density measurement value of the fluid to be measured at normal temperature and pressure through the gamma-ray density measurement device 22, the mass absorption rate ratio of the fluid to be measured and the standard fluid can be calculated;

[0046] 4) Through the mass flow meter 18, adjust the flow rate and pressure of the high-pressure constant-current pump 17 to the preset values, open the insulation joint 19 of the high-temperature and high-pressure liquid supply system, turn on the industrial air-cooled chiller 24 and the heat exchanger 23 for cooling the high-temperature and high-pressure liquid, set the alternating current constant-current power supply 21 before the experimental device to rise to a specific power, and heat the fluid to be measured flowing through the preheating section pipeline 20; when heated to the preset temperature value, use the data acquisition board 28 to measure the mass flow rate, temperature and pressure of the signal outputs of the mass flow meter 18, the pressure transmitter 7 and the thermocouple 8, turn on the gamma-ray radiation source and the shielding cover 3, and use the data acquisition device 14 to collect the counting rate of the fluid to be measured. After repeating the collection for enough groups, turn off the gamma-ray radiation source and the shielding cover 3, the data acquisition device 14 and the data acquisition board 28;

[0047] 5) Adjust the heating power of the alternating current constant-current power supply 21 to measure the next temperature point, and repeat the above step 4) until the industrial control computer 29 completes the collection of the counting rates of the fluid to be measured at different temperatures;

[0048] 6) Gradually reduce the heating power of the alternating current constant-current power supply 21. After the fluid in the gamma-ray density measurement device 22 cools down to normal temperature, adjust the tightness of the back-pressure valve 25 until the system pressure drops to normal pressure, turn off the high-pressure constant-current pump 17, stop the operation of the experimental system, move the gamma-ray radiation source and the shielding cover 3 to the source library for storage according to the usage and operating procedures of the radiation source, and make relevant records of the experiment.

[0049] The said device and method are used for the gamma-ray density measurement of high-temperature and high-pressure hydrocarbon fuels at the 70 MPa level.

[0050] The beneficial effects of the present invention:

[0051] The present invention eliminates the influence of temperature on the counting rate of the radiographic density measuring device, obtains the mass absorption coefficient of the unknown component hydrocarbon material by radiographic method, thereby completing the density measurement of the hydrocarbon material, and can be used to measure the density of a fluid different from a standard fluid.

[0052] When using gamma-ray density measurement, firstly, the influence of temperature on the counting rate of the structure itself under high temperature and high pressure can be eliminated by selecting a low-density standard fluid; secondly, when the mass absorption coefficient of the standard density fluid is known, the real density of the fluid to be measured at room temperature and pressure and the measured density of the fluid to be measured by the gamma-ray density meter can be measured by a float densitometer, and the mass absorption coefficient ratio of different fluids to be measured relative to the standard density fluid can be obtained, thereby eliminating the influence of different radiation absorption rates between different substances on the density measurement results.

[0053] Therefore, the mass absorption coefficient and density of the fluid to be measured can be obtained in one measurement. The mass absorption rate of the measured substance can be obtained in advance by the ray method, which can be used to measure the density of hydrocarbon substances with unknown composition. The measured rocket kerosene density result is as follows: Figure 3 shown. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a structural schematic diagram of the gamma ray density measuring device of the present invention.

[0055] Figure 2 This is a schematic diagram of the high-temperature and high-pressure fluid generation and control system of the present invention.

[0056] Figure 3 Schematic diagram of the rocket kerosene density obtained from the measurement results. DETAILED DESCRIPTION

[0057] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0058] Reference Figure 1 , Figure 2 As shown, it includes a fixed platform 1, an experimental section pipeline 2 fixed on the fixed platform 1 by a supporting column, a gamma-ray radiation source and a shielding cover 3 on the fixed platform 1, a radiation detector 4 on the fixed platform 1, a lead block collimator 5 and a heat insulation board 6 are arranged between the experimental section pipeline 2 and the gamma-ray radiation source and the shielding cover 3 and the radiation detector 4; a pressure transmitter 7 and a thermocouple 8 are installed at the inlet and outlet of the experimental section pipeline 2, and a heat insulation cotton 12 and a mica heating plate 13 are arranged outside the experimental section pipeline 2; the radiation detector 4 includes a CsI-scintillation base counter 9, a signal amplifier 10 and a data processing output device 11, and the data processing output device 11 is connected to the input end of the data acquisition device 14; the front and rear ends of the experimental section pipeline 2 are connected to the generation and control system of high-temperature and high-pressure liquid.

[0059] ReferenceFigure 2 The generating and control system for the high-temperature and high-pressure liquid as described above includes a storage tank 15 for storing the fluid to be measured. The lower end outlet of the storage tank 15 is connected to the inlet of a filter 16. The outlet of the filter 16 is connected to the inlet of a high-pressure constant flow pump 17. The outlet of the high-pressure constant flow pump 17 is connected to the inlet of a mass flow meter 18. The outlet of the mass flow meter 18 is connected to the inlet of an insulating joint 19. The inlet of the insulating joint 19 is connected to the inlet of a preheating section pipeline 20. The outlet of the preheating section pipeline 20 is connected to a gamma-ray density measuring device 22; the gamma-ray density measuring device 22 is connected to the pipeline after measurement in the experimental section. The outlet of the gamma-ray density measuring device 22 is connected to the inlet of a high-temperature filter 16. The outlet of the high-temperature filter 16 is connected to the inlet of a shell-and-tube heat exchanger 23. The outlet of the shell-and-tube heat exchanger 23 is connected to the inlet of the insulating joint 19. The outlet of the insulating joint 19 is connected to the inlet of a back pressure valve 25. The outlet of the back pressure valve 25 is connected to the inlet of a tail gas separation and treatment device 26. The outlet of the tail gas separation and treatment device 26 returns to a waste liquid tank 27.

[0060] The inlet of the preheating section pipeline 20 is connected to one end output of an AC constant current power supply 21, and the outlet of the preheating section pipeline 20 is connected to one end output of the AC constant current power supply 21; the heating power is calculated by a voltage and current sensor carried by the AC constant current power supply 21. Insulating joints 19 are connected before the preheating section pipeline 20 and after the shell-and-tube heat exchanger 23 to prevent the leakage of heating current.

[0061] The shell side outlet of the shell-and-tube heat exchanger 23 is connected to the inlet of an industrial air-cooled chiller 24. The outlet of the industrial air-cooled chiller 24 is connected to the shell side inlet of the shell-and-tube heat exchanger 23. A mass flow meter 18 is arranged between the high-pressure constant flow pump 17 and the insulating joint 19. Thermocouples 8 are arranged at the inlet and outlet of the preheating section pipeline 20, and thermocouples 8 are arranged at the inlet and outlet of the experimental section pipeline 2. A pressure transmitter 7 is arranged between the outlet of the preheating section pipeline 20 and the inlet of the experimental section pipeline 2; the signals of the mass flow meter 18, the pressure transmitter 7 and the thermocouple 8 are output to a data acquisition board 28.

[0062] The data output of the data acquisition device 14 and the data acquisition board 28 is connected to an industrial control computer 29, and the thermal parameters and counting rate are displayed through the industrial control computer 29.

[0063] An installation and measurement method for a gamma-ray density measuring device of a high-temperature and high-pressure liquid, the steps of which are as follows:

[0064] Step 1: Adjust the fixed platform 1 so that the fixed platform 1 is closely connected to the ground, and make the level of the fixed platform 1 within a certain range through a horizontal bubble level.

[0065] Step 2: Install an experimental section pipeline 2 in the middle of the fixed platform 1, place a mica heating sheet 13 at a suitable position of the experimental section pipeline 2, and wrap sufficient thickness of thermal insulation cotton 12 around the mica heating sheet 13.

[0066] Step 3: Arrange a gamma-ray radiation source with a shielding lead can and a shielding cover 3 on one side of the fixed platform 1, and arrange a radiation detector 4 on the other side, so that the ray emission and reception directions are on the same horizontal line;

[0067] Step 4: Select lead collimators 5 with the same pipe diameter according to the pipe diameter of the experimental section pipe 2 and place them at the outlet of the gamma-ray radiation source and the shielding cover 3 and the front end of the radiation detector 4 respectively;

[0068] Step 5: Select a suitable standard density fluid to calibrate the counting rate of the gamma-ray density measuring device 22; by controlling the generation and control system of high-temperature and high-pressure liquid, select the temperature range from normal temperature to high temperature to eliminate the influence of temperature on gamma-ray density measurement.

[0069] Step 6: By comparing the counting rate differences between the standard density fluid and the fluid to be measured in the gamma-ray density measuring device 22, and combining the density measurement of the fluid to be measured under normal temperature and pressure, the mass absorption rate of the measured substance can be obtained in advance;

[0070] Step 7: Adjust the back pressure valve 25 at the outlet of the system pipeline to make the system pressure reach the preset value; start the AC constant current power supply 21, heat the preheating section pipeline 20 until the temperature thermocouple 8 at the inlet and outlet of the experimental section reaches the predetermined measurement value; turn on the gamma-ray radiation source and the shielding cover 3 and the radiation detector 4 to measure the density of the fluid to be measured under the working condition to be measured.

[0071] A measurement method for a gamma-ray density measuring device of a high-temperature and high-pressure hydrocarbon fuel includes: (1) eliminating the influence of temperature on the gamma-ray density measuring device; (2) correcting the density calculation of the fluid to be measured by using the ratio of the mass absorption coefficients of the fluid to be measured and the standard density fluid.

[0072] (1) Eliminating the influence of temperature on the gamma-ray density measuring device:

[0073] When the temperature of the fluid to be measured is at a high temperature, considering the influence of the expansion and deformation of the lead collimator 5 and the heat insulation plate 6 of the gamma-ray density measuring device at high temperature on the experimental measurement, it is necessary to eliminate the influence of the fluid to be measured at high temperature on the gamma-ray density measuring device. It is necessary to verify the dimensionless counting rate characteristics of the density measurement test section affected by temperature for standard density fluids with different densities at high temperature:

[0074]

[0075] Where: Φ—dimensionless counting rate; Φ m —counting rate of the fluid to be measured; Φ H —counting rate of the high-density standard fluid; Φ L—Counting rate of the low-density standard fluid. The dimensionless counting rate characterizes the magnitude relationship between the counting rate of the fluid to be measured and the counting rates of the high-density standard fluid and the low-density standard fluid. Through experimental verification, using a high-temperature fluid as the low-density standard fluid can eliminate the influence of temperature on the counting rate characteristics of the density measurement device. Therefore, the ray counting rate of the low-density standard fluid simultaneously includes the radiation intensity absorbed by the fluid and the radiation intensity that changes due to the influence of temperature on the ray device, thus offsetting the influence of temperature on the counting rate of the density measurement device.

[0076] (2) Calculate the density of the fluid to be measured by correcting with the mass absorption coefficient:

[0077] The radiation intensity of the gamma-ray radiation source and the shielding cover 3 and the radiation detector 4 is I m , and the average number of particles collected by the radiation detector 4 in 1 minute is recorded as the counting rate Φ of the fluid to be measured m , and through calculation with the density ρ c of the standard fluid, the density ρ m of the fluid to be measured can be obtained. The calculation formula for ρ m is obtained through the following steps:

[0078] By comparing the different ray intensities of the fluid to be measured with the high-density standard fluid and the low-density standard fluid, the density at normal temperature and pressure is ρ m0 :

[0079]

[0080] where: ρ m0 —Density value measured by the ray method at normal temperature and pressure; ρ H —Density of the high-density standard fluid; ρ L —Density of the low-density standard fluid; I m —Intensity of the ray passing through the fluid to be measured; I H —Intensity of the ray passing through the high-density fluid; I L —Intensity of the ray passing through the low-density fluid.

[0081] Then, after measuring with a float densitometer to obtain the true density of rocket kerosene at normal temperature and pressure, the ratio of the mass absorption coefficient of rocket kerosene to the standard density fluid can be obtained:

[0082]

[0083] where: μ c —Mass absorption coefficients of the high-density and low-density standard fluids; μ m —Mass absorption coefficient of the fluid to be measured; ρ ms —True density of the fluid to be measured at normal temperature and pressure; ρ m0 —Density value measured by the ray method at normal temperature and pressure.

[0084] During the measurement process, the counting mode is adopted instead of measuring the ray intensity. The counting rate is the number of received particles per unit time, which is proportional to the intensity of the rays in the receiving area. Therefore, in the calculation, the ratio of the counting rates recorded by the scintillation counter in 1 minute is selected to replace the ratio of the ray intensities. Then ρ m The calculation formula is as follows:

[0085]

[0086] Where: ρ—the corrected value of the measured density of the fluid to be measured; Φ m —the counting rate of the fluid to be measured; Φ H —the counting rate of the high-density standard fluid; Φ L —the counting rate of the low-density standard fluid. Kerosene-based hydrocarbon fuels have complex compositions with hundreds or thousands of components. It is difficult to obtain their exact molecular formulas through conventional methods. For fluids to be measured with different compositions, by measuring the true density at normal temperature and pressure and the density value measured by the ray method at normal temperature and pressure, the mass absorption rate of different types of hydrocarbon fuels can be quickly corrected.

[0087] A gamma-ray density measurement method for high-temperature and high-pressure hydrocarbon fuels, and its specific measurement steps are as follows:

[0088] 1) Select a suitable standard density fluid to be measured according to the physical properties of the fluid to be measured (such as n-dodecane, n-decane or cyclohexane). First, measure the counting rate of the standard fluid, and eliminate the influence of temperature on the gamma-ray density measurement device in the above way; use a high-temperature fluid as the low-density standard fluid and a normal-temperature and high-pressure fluid as the high-density standard fluid; record the counting rate when the gamma-ray radiation source and the shielding cover 3 are not opened as the environmental background counting rate;

[0089] 2) Open the high-pressure constant-current pump 17, and fill the gamma-ray density measurement system with the standard density fluid. Test the temperature and pressure in the experimental section pipeline 2 through the pressure transmitter 7 and the thermocouple 8; control the temperature of the experimental section pipeline 2 by changing the heating power of the alternating current constant-current power supply 21, and control the pressure of the experimental pipeline 2 in the gamma-ray density measurement device 22 by changing the tightness of the back-pressure valve 25; change different working conditions, repeat the measurement enough times, and calibrate and test the high-density standard fluid density and the low-density standard fluid density respectively.

[0090] 3) After measuring the true density of the fluid to be measured at normal temperature and pressure through the float density meter, and then measuring the density value of the fluid to be measured by the ray method at normal temperature and pressure through the gamma-ray density measurement device 22, the ratio of the mass absorption rates of the fluid to be measured and the standard fluid can be calculated.

[0091] 4) Adjust the flow rate and pressure of the high-pressure constant-current pump 17 to the preset values through the mass flowmeter 18. Open the insulating joint 19 of the high-temperature and high-pressure liquid supply system, turn on the industrial air-cooled chiller 24 and the heat exchanger 23 for cooling the high-temperature and high-pressure liquid, and set the AC constant-current power supply 21 before the experimental device to a specific power to heat the fluid to be measured flowing through the preheating section pipe 20. When heated to the preset temperature value, use the data acquisition board 28 to measure the mass flow rate, temperature, and pressure of the signal outputs of the mass flowmeter 18, the pressure transmitter 7, and the thermocouple 8. Open the gamma-ray radiation source and the shielding cover 3, and use the data acquisition device 14 to collect the counting rate of the fluid to be measured. After repeating the collection for a sufficient number of groups, turn off the gamma-ray radiation source and the shielding cover 3, the data acquisition device 14, and the data acquisition board 28;

[0092] 5) Adjust the heating power of the AC constant-current power supply 21 to measure the next temperature point, and repeat the above step 4) until the industrial control computer 29 completes the collection of the counting rates of the fluid to be measured at different temperatures;

[0093] 6) Gradually reduce the heating power of the AC constant-current power supply 21. After the fluid in the gamma-ray density measurement device 22 cools down to room temperature, adjust the tightness of the back pressure valve 25 until the system pressure drops to atmospheric pressure, turn off the high-pressure constant-current pump 17, and stop the operation of the experimental system. Move the gamma-ray radiation source and the shielding cover 3 to the source library for storage in accordance with the usage and operating procedures of the radiation source, and make relevant records of the experiment.

Claims

1. A gamma-ray density measurement device for high-temperature and high-pressure hydrocarbon fuels, characterized in that, It includes a fixed platform (1). On the fixed platform (1), an experimental section pipeline (2), a gamma-ray radiation source and a shielding cover (3), and a radiation detector (4) are fixed through support columns. A lead collimator (5) and a heat insulation plate (6) are arranged coaxially between the gamma-ray density measurement experimental section pipeline (2), the gamma-ray radiation source and the shielding cover (3), and the radiation detector (4). The experimental section pipeline (2) includes three parts: an inlet pipeline, a pipeline through which gamma rays pass, and an outlet pipeline, which are welded together. Pressure transmitters (7) and thermocouples (8) are installed at the inlet and outlet of the gamma-ray density measurement experimental section pipeline (2). Heat insulation cotton (12) and mica heating sheets (13) are arranged outside the gamma-ray density measurement experimental section pipeline (2). The radiation detector (4) includes a CsI-scintillation counter (9), a signal amplifier (10), and a data processing and output device (11). The data processing and output device (11) is connected to the input end of a data acquisition device (14). The inlet pipeline of the gamma-ray density measurement experimental section pipeline (2) is connected to the preheating and heating section of the fluid to be measured in the high-temperature and high-pressure liquid generation and control system, and the outlet pipeline is connected to the cooling and treatment section in the high-temperature and high-pressure liquid generation and control system.

2. The gamma-ray density measurement device for high-temperature and high-pressure hydrocarbon fuel according to claim 1, characterized in that, The high-temperature and high-pressure liquid generation and control system includes a storage tank (15) for storing the fluid to be measured. The lower outlet of the storage tank (15) is connected to the inlet of a filter (16). The outlet of the filter (16) is connected to the inlet of a high-pressure constant flow pump (17). The outlet of the high-pressure constant flow pump (17) is connected to the inlet of a mass flow meter (18). The outlet of the mass flow meter (18) is connected to the inlet of an insulating joint (19). The inlet of the insulating joint (19) is connected to the inlet of a preheating section pipeline (20). The outlet of the preheating section pipeline (20) is connected to a gamma-ray density measurement device (22). The gamma-ray density measurement device (22) is connected to the pipeline after the experimental section measurement. The outlet of the gamma-ray density measurement device (22) is connected to the inlet of a high-temperature filter (16). The outlet of the high-temperature filter (16) is connected to the inlet of a shell-and-tube heat exchanger (23). The outlet of the shell-and-tube heat exchanger (23) is connected to the inlet of an insulating joint (19). The outlet of the insulating joint (19) is connected to the inlet of a back pressure valve (25). The outlet of the back pressure valve (25) is connected to the inlet of a tail gas separation and treatment device (26). The outlet of the tail gas separation and treatment device (26) returns to a waste liquid tank (27).

3. The gamma-ray density measurement device for high-temperature and high-pressure hydrocarbon fuel according to claim 2, wherein The inlet of the preheating section pipeline (20) is connected to one end output of an AC constant current power supply (21), and the outlet of the preheating section pipeline (20) is connected to one end output of the AC constant current power supply (21). The heating voltage U and heating current I at both ends of the preheating section pipeline (20) are obtained by voltage sensors and current sensors carried by the AC constant current power supply (21). The heating power P is calculated by multiplying the heating voltage and the heating current. Insulating joints (19) are connected before the preheating section pipeline (20) and after the shell-and-tube heat exchanger (23) to prevent the heating current from conducting to other positions outside the experimental pipeline.

4. The gamma ray density measurement device for high-temperature and high-pressure hydrocarbon fuel according to claim 3, characterized in that, The shell side outlet of the shell-and-tube heat exchanger (23) is connected to the inlet of the industrial air-cooled chiller (24), and the outlet of the industrial air-cooled chiller (24) is connected to the shell side inlet of the shell-and-tube heat exchanger (23).

5. The gamma-ray density measurement device for high-temperature and high-pressure hydrocarbon fuel according to claim 2, wherein, A mass flowmeter (18) is arranged between the high-pressure constant-current pump (17) and the insulating joint (19). Thermocouples (8) are arranged at the inlet and outlet of the preheating section pipeline (20), and thermocouples (8) are arranged at the inlet and outlet of the gamma-ray density measurement experimental section pipeline (2). A pressure transmitter (7) is arranged between the outlet of the preheating section pipeline (20) and the inlet of the gamma-ray density measurement experimental section pipeline (2); the signals of the mass flowmeter (18), the pressure transmitter (7) and the thermocouple (8) are output to the data acquisition board (28).

6. The gamma-ray density measurement device for high-temperature and high-pressure hydrocarbon fuel according to claim 2, characterized in that, The data outputs of the data acquisition device (14) and the data acquisition board (28) are connected to the industrial control computer (29), and the thermal parameters and count rate are displayed through the industrial control computer (29).

7. The installation method of a gamma-ray density measurement device for high-temperature and high-pressure hydrocarbon fuel according to any one of claims 1-6, the steps are as follows: Step 1: Adjust the fixed platform (1) so that the fixed platform (1) is closely connected to the ground, and make the level of the fixed platform (1) within 1° through a horizontal bubble level, ensuring that the rays emitted by the radiation source can horizontally pass through the gamma-ray density measurement experimental section pipeline (2) without leakage to the outside; Step 2: Install the experimental section pipeline (2) in the middle of the fixed platform (1), closely arrange mica heating sheets (13) on the upper and lower surfaces of the experimental section pipeline (2), and wrap 5-10 mm of heat insulation cotton (12) around the mica heating sheets (13) to reduce heat dissipation and reduce the temperature difference between the inlet and outlet; Step 3: Arrange the gamma-ray radiation source and shield (3) with a shielding lead can on one side of the fixed platform (1) and the radiation detector (4) on the other side, so that the ray emission and reception directions are on the same horizontal line; Step 4: Select lead block collimators (5) and heat insulation plates (6) with the same pipe diameter according to the pipe diameter of the gamma-ray density measurement experimental section pipeline (2), and place them at the outlet of the gamma-ray radiation source and shield (3) and the front end of the receiving device respectively; Step 5: Select a suitable standard density fluid (such as n-decane, toluene or cyclohexane, etc.) similar to the physical properties of the fluid to be measured to calibrate the count rate of the gamma-ray density measurement device (22); through the control system for generating and controlling high-temperature and high-pressure liquids, select the temperature range from normal temperature of 25°C to 400°C to eliminate the influence of temperature on gamma-ray density measurement; Step 6: By comparing the count rate differences between the standard density fluid and the fluid to be measured in the gamma-ray density measurement device (22), and combining the density measurement of the fluid to be measured under normal temperature and pressure, the mass absorption rate of the measured substance can be obtained in advance; Step 7: Adjust the back-pressure valve (25) at the outlet of the system pipeline to make the system pressure reach the preset value; start the AC constant-current power supply (21), and heat the preheating section pipeline (20) until the inlet and outlet temperature thermocouples (8) of the experimental section reach the predetermined measurement value; open the gamma-ray radiation source and shield (3) and the radiation detector (4) to measure the density of the fluid to be measured under the working conditions to be measured.

8. The measurement method of a gamma-ray density measurement device for high-temperature and high-pressure hydrocarbon fuels according to any one of claims 1-6, comprising: (1) eliminating the influence of temperature on the gamma-ray density measurement device; (2) correcting the calculation of the density of the fluid to be measured by using the ratio of the mass absorption coefficients of the fluid to be measured and the standard density fluid. (1) Eliminating the influence of temperature on the gamma-ray density measurement device: When the temperature of the fluid to be measured is at a high temperature, considering the influence of the expansion and deformation of the lead collimator (5) and the heat insulation plate (6) of the gamma-ray density measurement device at high temperature on the experimental measurement, it is necessary to eliminate the influence of the fluid to be measured at high temperature on the gamma-ray density measurement device. It is necessary to verify the dimensionless counting rate characteristics affected by temperature of the density measurement test section for standard density fluids with different densities at high temperature: Wherein: Φ—Dimensionless count rate; Φ m —Count rate of the fluid to be measured; Φ H —Count rate of the high-density standard fluid; Φ L — Counting rate of the low-density standard fluid. The dimensionless counting rate characterizes the magnitude relationship between the counting rate of the fluid to be measured and the counting rates of the high-density standard fluid and the low-density standard fluid. Through experimental verification, using a high-temperature fluid as the low-density standard fluid can eliminate the influence of temperature on the counting rate characteristics of the density measurement device. Therefore, the radiation counting rate of the low-density standard fluid simultaneously includes the radiation intensity absorbed by the fluid and the radiation intensity that changes due to the influence of temperature on the radiation device, thereby offsetting the influence of temperature on the counting rate of the density measurement device; (2) Correcting the calculation of the density of the fluid to be measured by using the mass absorption coefficient: The gamma ray radiation source, the shielding cover (3), and the radiation detector (4) measure the ray radiation intensity as I m , and the average number of particles collected by the radiation detector (4) in 1 minute is recorded as the counting rate Φ of the fluid to be measured m , and through calculation with the standard fluid density ρ c , the density ρ of the fluid to be measured can be obtained m , ρ m , the calculation formula of ρ is obtained by the following steps: By comparing the ray intensities of the fluid to be measured with those of a high-density standard fluid and a low-density standard fluid, a density ρ at normal temperature and pressure is obtained m0 : Where: ρ m0 — The density value measured by the ray method under normal temperature and pressure; ρ H — The density of the high-density standard fluid; ρ L — The density of the low-density standard fluid; I m — The intensity of the ray passing through the fluid to be measured; I H — The intensity of the ray passing through the high-density fluid; I L — The intensity of the ray passing through the low-density fluid; Then, after measuring the true density of rocket kerosene at normal temperature and pressure through a float densitometer, the ratio of the mass absorption coefficients of rocket kerosene and the standard density fluid can be obtained: Where: μ c — Mass absorption coefficient of high- and low-density standard fluids; μ m — Mass absorption coefficient of the fluid to be measured; ρ ms — True density of the fluid to be measured at normal temperature and pressure; ρ m0 — Density value measured by the ray method at normal temperature and pressure; During the measurement process, the counting mode is adopted instead of the measurement of the ray intensity. The counting rate is the number of received particles per unit time and is proportional to the intensity of the rays within the receiving area. Therefore, in the calculation, the ratio of the counting rates recorded by the scintillation counter in 1 minute is selected to replace the ratio of the ray intensities; then ρ m The calculation formula of is: Where: ρ—the measurement correction value of the density of the fluid to be measured; Φ m —the counting rate of the fluid to be measured; Φ H —the counting rate of the high-density standard fluid; Φ L —the counting rate of the low-density standard fluid; Kerosene-based hydrocarbon fuels have complex compositions with hundreds or thousands of components. It is very difficult to obtain their exact molecular formulas through conventional methods. For different components of the fluid to be measured, by measuring the true density at normal temperature and pressure and the density value measured by the ray method at normal temperature and pressure, the mass absorption rates of different types of hydrocarbon fuels can be quickly corrected.

9. The measurement method according to claim 8, characterized in that, The specific measurement steps are as follows: 1) Select a suitable standard density fluid to be measured according to the physical properties of the fluid to be measured. First, measure the counting rate of the standard fluid, and eliminate the influence of temperature on the gamma-ray density measurement device in the above manner; use a high-temperature fluid as the low-density standard fluid, and use a normal-temperature and high-pressure fluid as the high-density standard fluid; Record the counting rate when the gamma-ray radiation source and shield (3) are not opened as the environmental background counting rate; 2) Open the high-pressure constant-current pump (17), fill the gamma-ray density measurement system with the standard density fluid, and test the temperature and pressure in the pipeline (2) of the gamma-ray density measurement experimental section through the pressure transmitter (7) and the thermocouple (8); control the temperature of the pipeline (2) in the experimental section of the gamma-ray density measurement device by changing the heating power of the AC constant-current power supply (21), and control the pressure of the pipeline (2) in the gamma-ray density measurement experimental section of the gamma-ray density measurement device (22) by changing the tightness of the back-pressure valve (25); change different working conditions, repeat the measurement enough times, and calibrate and test the high-density standard fluid density and the low-density standard fluid density respectively; 3) After measuring the true density of the fluid to be measured at normal temperature and pressure through a float densitometer, and then measuring the ray method density measurement value of the fluid to be measured at normal temperature and pressure through the gamma-ray density measurement device (22), the ratio of the mass absorption rates of the fluid to be measured and the standard fluid can be calculated; 4) Adjust the flow rate and pressure of the high-pressure constant-current pump (17) to the preset values through the mass flowmeter (18). Open the insulating joint (19) of the high-temperature and high-pressure liquid supply system. Turn on the industrial air-cooled chiller (24) and the heat exchanger (23) for cooling the high-temperature and high-pressure liquid. Set the AC constant-current power supply (21) before the experimental device to a specific power to heat the fluid to be measured flowing through the preheating section pipeline (20). When heated to the preset temperature value, use the data acquisition board (28) to measure the mass flow rate, temperature, and pressure of the signal outputs of the mass flowmeter (18), the pressure transmitter (7), and the thermocouple (8). Open the gamma-ray radiation source and the shielding cover (3), and use the data acquisition device (14) to collect the counting rate of the fluid to be measured. After repeating the collection for a sufficient number of groups, close the gamma-ray radiation source and the shielding cover (3), the data acquisition device (14), and the data acquisition board (28). 5) Adjust the heating power of the AC constant-current power supply (21) to measure the next temperature point, and repeat the above step 4) until the industrial control computer (29) completes the collection of the counting rates of the fluid to be measured at different temperatures. 6) Gradually reduce the heating power of the AC constant-current power supply (21). Wait for the fluid in the gamma-ray density measurement device (22) to cool to room temperature. Adjust the tightness of the back pressure valve (25) until the system pressure drops to atmospheric pressure. Turn off the high-pressure constant-current pump (17) to stop the operation of the experimental system. Move the gamma-ray radiation source and the shielding cover (3) to the source library for storage in accordance with the usage and operating procedures of the radiation source, and make relevant records of the experiment.

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