A capacitance probe system suitable for supercritical water fluidized bed and its use method

Abstract

The present invention provides a capacitance probe system suitable for a supercritical water fluidized bed and a method for using the same, comprising a capacitance probe sensor and a sealing device; the sealing device sequentially comprises a top cover, a double cone ferrule, a middle connection section of a base, a ring top sleeve, a conical cylindrical gasket and a lower connection section of a base from one end to the other end; the measuring end of the capacitance probe sensor sequentially passes through the top cover, the double cone ferrule, the middle connection section of the base, the ring top sleeve, the conical cylindrical gasket and the lower connection section of the base; the top cover is fixedly connected to the middle connection section of the base, and the two are sealed by the double cone ferrule; the middle connection section of the base is fixedly connected to the lower connection section of the base, and the two are sealed by the ring top sleeve and the conical cylindrical gasket. The sealing device designed by the present invention can meet the high-strength fixed sealing requirements of the capacitance probe sensor used in the supercritical water fluidized bed, and ensure that the capacitance probe sensor works safely and stably in the supercritical water fluidized bed.

Description

Technical Field

[0001] The present invention relates to a multiphase flow testing technology, in particular to a capacitance probe testing system and a use method thereof, and specifically to a capacitance probe system suitable for a supercritical water fluidized bed and a use method thereof. Background Art

[0002] Supercritical water gasification technology is a very promising technology for clean and efficient utilization of organic resources such as coal / biomass developed in recent years. It has high reaction efficiency and zero pollutant emissions. As a new type of coal / biomass gasification reactor, the supercritical water fluidized bed realizes the continuous gasification of coal / biomass in supercritical water, rapid temperature rise of the reaction materials, enhanced heat and mass transfer, and easy slag discharge. However, up to now, there is still a lack of understanding of the microscopic two-phase flow characteristics inside the supercritical water fluidized bed reactor, mainly due to the limitations of the measurement method technology.

[0003] The capacitance probe method is a traditional two-phase flow characteristics testing technology. The relevant patents use it to obtain the microscopic flow characteristics in the reactor, but the use environment of the traditional capacitance probe is relatively mild, and it is difficult to apply it to the supercritical water fluidized bed with very high pressure and temperature. The extreme operating conditions put forward new and higher insulation, sealing, and fixing strength requirements for the capacitance probe sensor. The supercritical water fluidized bed is a high temperature and high pressure working condition, and there is also supercritical water with strong solubility. The traditional capacitance probe sensor fixing and sealing method cannot meet the requirements for use in the supercritical water fluidized bed. If the fixing and sealing conditions of the capacitance probe cannot meet the requirements of the supercritical water working condition, it will not only cause measurement failure, but also may lead to serious safety accidents such as leakage and spraying of high-temperature and high-pressure materials in the bed.

[0004] In summary, due to the extreme working conditions of high temperature and high pressure in supercritical water fluidized beds, traditional capacitance probe testing systems cannot be applied to supercritical water fluidized beds, and there are currently no reports on capacitance probes suitable for supercritical water fluidized beds. Summary of the invention

[0005] In order to solve the problem that traditional capacitance probe systems are difficult to use under extreme working conditions of high temperature, high pressure and supercritical water, the present invention provides a capacitance probe system suitable for a supercritical water fluidized bed and a method of using the same, thereby solving the problems of fixing and sealing traditional capacitance probe sensors when used under extreme working conditions of high temperature, high pressure and supercritical water.

[0006] The present invention is achieved through the following technical solutions:

[0007] A capacitance probe system suitable for a supercritical water fluidized bed, comprising a capacitance probe sensor and a sealing device;

[0008] The sealing device includes a top cover, a double-cone ferrule, a middle connection section of the base, a ring top sleeve, a conical cylindrical gasket and a lower connection section of the base in sequence from one end to the other end; the measuring end of the capacitance probe sensor passes through the top cover, the double-cone ferrule, the middle connection section of the base, the ring top sleeve, the conical cylindrical gasket and the lower connection section of the base in sequence;

[0009] The top cover is fixedly connected to the middle connecting section of the base, and the two are sealed by a double-cone ferrule; the middle connecting section of the base is fixedly connected to the lower connecting section of the base, and the two are sealed by a ring-top sleeve and a conical cylindrical gasket.

[0010] Preferably, the capacitive probe sensor is divided into a front high temperature section, a middle low temperature section and a rear low temperature section from the measuring end to the connecting end; the capacitive probe sensor comprises three coaxially arranged metal electrodes and a coaxial cable connector, which are respectively a central sensing electrode, an active shielding electrode and a shell ground electrode from the inside to the outside, and the three metal electrodes extend from the front high temperature section to the rear low temperature section;

[0011] In the front high-temperature section, an insulating layer is arranged between two adjacent metal electrodes; the tail of the insulating layer extends to the middle low-temperature section; the cavity part in the middle low-temperature section is filled with a structural adhesive cured layer; in the tail low-temperature section, a structural adhesive cured layer is filled between two adjacent metal electrodes, and the central sensing electrode and the active shielding electrode are both connected to the coaxial cable connector.

[0012] Furthermore, the middle low-temperature section is divided into two parts: a front half of the middle low-temperature section connected to the front high-temperature section and a rear half of the middle low-temperature section connected to the rear low-temperature section; the rear part of the insulating layer in the front high-temperature section extends to the end of the front half of the middle low-temperature section, and in the front half of the middle low-temperature section, a structural adhesive cured layer is filled between the insulating layer and the metal electrode; in the rear half of the middle low-temperature section, a structural adhesive cured layer is filled between two adjacent metal electrodes.

[0013] Furthermore, in the front high-temperature section, the gap between the metal electrode and the insulating layer is greater than 0.02 mm.

[0014] Furthermore, the material of the structural adhesive curing layer is epoxy resin.

[0015] Furthermore, in the tail low-temperature section, a coaxial terminal is provided between two adjacent metal electrodes, and a structural adhesive curing layer is provided between the metal electrode and the coaxial terminal.

[0016] Preferably, it also includes a capacitance measurement amplifier, a data acquisition card and a data processing module; the measurement signal of the capacitance probe sensor is amplified by the capacitance measurement amplifier and then transmitted to the data processing module via the data acquisition card, and the data processing module obtains the characteristic parameters of the material in the supercritical water fluidized bed according to the received signal processing.

[0017] Preferably, the top cover is connected to the middle connecting section of the base via threads, and the middle connecting section of the base is connected to the lower connecting section of the base via threads.

[0018] Preferably, the double-cone ferrule is made of brass, and the conical cylindrical gasket is made of polytetrafluoroethylene.

[0019] The method for using the capacitance probe system suitable for a supercritical water fluidized bed is to install and fix the capacitance probe sensor on the supercritical water fluidized bed through a sealing device, turn on the capacitance probe sensor for measurement, obtain the output signal U of the capacitance probe sensor, and calculate the local void ratio ε of the material particles in the supercritical water fluidized bed by the following formula:

[0020]

[0021] Among them, ε fb is the void ratio of the material particles in the natural stacking state, U 0 is the output signal of the capacitance probe sensor in supercritical water fluid without material particles, U fb It is the output signal of the capacitive probe sensor when the material particles are naturally accumulated.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The sealing device of the present invention adopts a method of combining a double-cone ferrule with a conical cylindrical gasket to meet the fixing strength and sealing requirements. The double-cone ferrule is inserted between the top cover and the middle connecting section of the base, and the top cover is connected to the middle connecting section of the base, radially compressing the double-cone ferrule to achieve deformation and tightening of the double-cone ferrule and radial compression of the capacitance probe sensor, thereby achieving the strength requirements of the capacitance probe sensor used in a supercritical water fluidized bed. An annular top sleeve and a conical cylindrical gasket are arranged between the middle connecting section of the base and the lower connecting section of the base, and the middle connecting section of the base is connected to the lower connecting section of the base through the middle connecting section of the base. The middle connecting section of the base will compress the conical cylindrical gasket by compressing the annular top sleeve. Since the contact surface between the conical cylindrical gasket and the lower connecting section of the base is conical, the conical cylindrical gasket will be compressed and deformed during the contact and compression process between the two, and will contract centripetally to compress the capacitance probe sensor, thereby achieving the sealing effect of the capacitance probe sensor in the supercritical water fluidized bed. The sealing device designed by the present invention can meet the high-strength fixed sealing requirements of the capacitance probe sensor used in the supercritical water fluidized bed, and ensure that the capacitance probe sensor works safely and stably in the supercritical water fluidized bed.

[0024] Furthermore, the present invention divides the structure of the capacitance probe sensor into sections according to the working temperature conditions of different parts of the capacitance probe sensor and the working pressure requirements of the capacitance probe sensor, so that different sections play corresponding fixing and sealing roles. The front high-temperature section is designed to be composed of a metal electrode and an insulating layer. No fixing and sealing materials are applied between the two, and only good insulation conditions between different electrodes are required; in the middle low-temperature section, the solidified layer between the metal electrodes can meet the strength and sealing requirements of the capacitance probe sensor in a supercritical water fluidized bed, and at the same time needs to have good insulation performance; the tail low-temperature section realizes the connection function. By reasonably arranging the combination and fixing methods of the electrodes and insulating layers at different sections of the capacitance probe sensor, the different sections of the capacitance probe sensor can cooperate with each other, so as to achieve the purpose of safe and stable use of the capacitance probe sensor in a supercritical water fluidized bed.

[0025] Furthermore, the purpose of the front half of the middle low-temperature section is to keep the position of the metal electrode and the insulating layer of the sensor fixed, and to prevent high-pressure water from reaching the end of the quartz glass tube to connect to the metal electrode and destroy the insulation between the metal electrodes. The main purpose of the rear half of the middle low-temperature section is to meet the insulation requirements of the metal electrode while making the capacitive probe sensor achieve extremely high axial shear strength to meet the strength requirements for safe and stable operation in a supercritical water fluidized bed.

[0026] Furthermore, the gap between the metal electrode and the insulating layer is maintained above 0.02 mm to satisfy free thermal expansion at high temperatures.

[0027] Furthermore, a high-strength, waterproof, and excellent insulating epoxy resin structural adhesive is used to fill between the metal electrodes. After being fully cured, the bond has high shear strength, good waterproofness, and good insulating properties.

[0028] Furthermore, a coaxial terminal is provided between two adjacent metal electrodes to ensure that the metal electrodes at the rear of the sensor do not contact each other.

[0029] Furthermore, the capacitance measurement amplifier is provided with a gain knob with an adjustable measurement range, so as to achieve measurement amplification of the target capacitance of the capacitance probe sensor developed by the present invention.

[0030] The method of the present invention uses the above-mentioned capacitance probe system to measure the local porosity inside the supercritical water fluidized bed, solving the problem of measuring the local porosity inside the supercritical water fluidized bed. It provides a method for measuring the internal information of the supercritical water fluidized bed and other reactors operating under extreme conditions of high temperature and high pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural diagram of the capacitance probe system suitable for a supercritical water fluidized bed according to the present invention.

[0032] Figure 2 It is a schematic diagram of a sealing device in a capacitance probe system suitable for a supercritical water fluidized bed according to the present invention;

[0033] Figure 3 is the capacitive probe sensor and seal assembly diagram;

[0034] Among them: front high temperature section 1, middle low temperature section 2, tail low temperature section 3, capacitance probe sensor 4, capacitance measurement amplifier 5, data acquisition card 6, data processing module 7, DC power supply 8, AC power supply 9, central sensing electrode 10, active shielding electrode 11, shell ground electrode 12, structural adhesive curing layer 13, coaxial terminal 14, BNC connector 15, BNC core electrode 16, BNC shielding layer 17, top cover 18, double cone ferrule 19, middle connecting section of base 20, ring top sleeve 21, conical cylindrical gasket 22, lower connecting section of base 23, stainless steel connecting pipe 24, insulating layer 25. DETAILED DESCRIPTION

[0035] In order to further understand the present invention, the present invention is described below in conjunction with embodiments. These descriptions are only to further explain the features and advantages of the present invention and are not intended to limit the claims of the present invention.

[0036] In order to solve the application problem of the capacitance probe system in a supercritical water fluidized bed reactor, the present invention optimizes the design and improves the traditional capacitance probe system, and develops a capacitance probe system and method suitable for a supercritical water fluidized bed, which can obtain detailed information such as the local porosity in the supercritical water fluidized bed.

[0037] The present invention is applicable to a capacitance probe system for a supercritical water fluidized bed, comprising a capacitance probe sensor 4, a sealing device, a capacitance measurement amplifier 5, a data acquisition card 6, a DC power supply 8, an AC power supply 9 and a data processing module 7, wherein:

[0038] The capacitive probe sensor 4 includes three coaxially arranged metal electrodes, which are respectively a central sensing electrode 10, an active shielding electrode 11 and a shell ground electrode 12 from the inside to the outside. Figure 1 An insulating layer 25 is arranged between two adjacent metal electrodes, specifically: an inner insulating layer is arranged between the central sensing electrode 10 and the active shielding electrode 11, and an outer insulating layer is arranged between the active shielding electrode 11 and the shell grounding electrode.

[0039] The material of the metal electrode is 316 stainless steel, and the material of the insulating layer 25 is high-purity quartz glass. The diameter of the central sensing electrode 10 is 0.6mm. At the head end of the capacitive probe sensor 4, the central sensing electrode 10 protrudes 5mm relative to the end faces of the active shielding electrode 11 and the shell grounding electrode. The outer diameter of the active shielding electrode 11 is 2.2mm and the thickness is 0.1mm. The outer diameter of the shell grounding electrode is 4.0mm and the thickness is 0.4mm. The active shielding electrode 11 and the shell grounding electrode remain flush at the head end of the capacitive probe sensor 4. At the head end of the capacitive probe sensor 4, the conical area formed by the protruding part of the central sensing electrode 10 and the shell grounding electrode 12 is the measurement area of ​​the capacitive probe sensor 4.

[0040] The end of the capacitive probe sensor 4 is a standard coaxial cable connector, which is connected to the customized capacitance measurement amplifier 5 through a low-noise coaxial cable. The connection between the capacitive probe sensor 4 and the coaxial cable is that the central sensing electrode 10 is connected to the BNC core electrode 16 of the coaxial cable, and the active shielding electrode 11 is connected to the BNC shielding layer 17 of the coaxial cable. The outer shell ground electrode 12 of the capacitive probe sensor 4 is connected to the ground terminal of the capacitance measurement amplifier 5 through a pure copper cable.

[0041] The capacitance probe sensor 4 of the present invention adopts a three-stage design. Figure 1 As shown, from the head to the tail of the capacitance probe sensor 4, there are the front high temperature section 1, the middle low temperature section 2, and the tail low temperature section 3. The design concept is to segment the needle structure of the capacitance probe sensor 4 according to the working temperature of different parts of the capacitance probe sensor 4 and the working pressure requirements of the capacitance probe sensor 4, so that different sections play corresponding fixing and sealing roles. By reasonably arranging the combination and fixing method of the electrodes and the insulating layer 25 at different sections of the capacitance probe sensor 4, the different sections of the capacitance probe sensor 4 cooperate with each other, so as to achieve the purpose of safe and stable use of the capacitance probe sensor 4 in the supercritical water fluidized bed.

[0042] The front high temperature section 1 includes a portion extending about 40 cm from the head end surface of the capacitance probe sensor 4 to the tail direction, such as Figure 1As shown. During the experiment, the working environment of the front of the capacitive probe sensor 4 is supercritical water or high-temperature and high-pressure water conditions. Since this segment has high working temperature and pressure and is in a supercritical water environment with solubility, the current various fixing methods are difficult to meet the strength and sealing requirements between the electrode and the insulating material under such extreme conditions. The present invention does not impose fixing strength and sealing requirements on the sensor of this segment, but only requires good insulation conditions between different electrodes. Therefore, the present invention designs the front high-temperature section 1 to be composed of a metal electrode and an insulating layer 25, and no fixing and sealing materials are applied between the two. The gap between the metal electrode and the insulating layer 25 should be kept above 0.02mm to meet the free thermal expansion under high temperature.

[0043] The middle low temperature section 2 includes a length of about 20 cm extending from the tail of the front high temperature section 1 to the tail of the capacitive probe sensor 4. Figure 1 As shown. The operating temperature of the sensor in this segment is relatively low. Its design purpose is to meet the strength and sealing requirements of the capacitive probe sensor 4 in the supercritical water fluidized bed, and it also needs to have good insulation performance. The fixing layer between the metal electrodes needs to achieve sealing in a high-pressure water environment, while ensuring high strength and good insulation conditions. This paper uses a special epoxy resin structural adhesive with high strength, good waterproof performance and excellent insulation performance to fill between each metal electrode to form a structural adhesive curing layer 13 to achieve this. After sufficient investigation and repeated debugging, this paper finally uses the German Ergo brand structural adhesive with a shear strength of up to 13MPa to achieve the fixation between the different layers of this segment. The German Ergo 7211 structural adhesive has an operating temperature range of -40 to 100°C and an operating time of 100 minutes, which provides sufficient operating time for the production of the capacitive probe sensor 4, and is conducive to improving the production quality of the capacitive probe sensor 4. The fully cured bond has high shear strength, good waterproofness, and good insulation performance.

[0044] The middle low-temperature section 2 of the capacitance probe sensor 4 can be further subdivided into two parts, the front half of the middle low-temperature section 2 and the back half of the middle low-temperature section 2, according to the different bonding structures. The front half of the middle low-temperature section 2 is about 10 cm long, and the tail ends of the inner insulating layer and the outer insulating layer extend to the end of the front half of the middle low-temperature section 2. This part is the tail end of the metal electrode and the quartz glass bonded and fixed, and the structural adhesive curing layer 13 is filled between the metal electrode and the insulating layer 25. The purpose is to keep the position of the metal electrode and the insulating layer 25 of the sensor fixed, and at the same time prevent high-pressure water from reaching the end of the quartz glass tube to connect to the metal electrode and destroy the insulation between the metal electrodes. The length of the back half of the middle low-temperature section 2 is about 10 cm, and the gaps between the metal electrodes are all composed of the structural adhesive curing layer 13. The main purpose of this part is to meet the insulation requirements of the metal electrode while enabling the capacitance probe sensor 4 to achieve extremely high axial shear strength and meet the strength requirements for safe and stable operation in a supercritical water fluidized bed.

[0045] The gaps between the metal electrodes in the middle low-temperature section 2 are all cured by pouring epoxy resin structural glue into the gaps between the metal electrodes to ensure the integrity of the cured layer and achieve the required shear strength. Since the viscosity of the epoxy resin structural glue is very high and the part that needs to be filled is a thin and deep annular area, it is very difficult to apply glue between the metal electrodes. This study used a special glue gun and an ultra-fine glue mixing head combined with a syringe needle to force the high-viscosity structural glue into the area between the metal electrodes to ensure the integrity of the cured layer.

[0046] The tail low temperature section 3 includes the portion from the tail of the middle low temperature section 2 to the tail of the capacitive probe sensor 4, and has a length of about 10 cm. Figure 1 As shown. The end of the tail low-temperature section 3 is a standard coaxial cable connector to ensure stable signal transmission. A coaxial terminal 14 is arranged in front of the BNC connector 15, that is, a coaxial terminal 14 is arranged between two adjacent metal electrodes, and a structural adhesive cured layer 13 is between the metal electrode and the coaxial terminal 14. The coaxial terminal 14 is used to ensure that the metal electrodes at the rear of the sensor do not contact each other. The protruding length of the tail of the central sensing electrode 10 relative to the tail of the active shielding electrode 11 is 1 cm, and the protruding length of the tail of the active shielding electrode 11 relative to the tail of the shell grounding electrode is 2 cm. The protruding part of the tail of the central sensing electrode 10 is connected to the BNC core pole 16 of the standard BNC connector 15, and the active shielding electrode 11 is connected to the BNC shielding layer 17 of the standard BNC connector 15, to ensure that the capacitance probe signal can be transmitted to the measurement amplifier without interference.

[0047] The sealing device is a fixing and sealing device used when assembling the capacitance probe sensor 4 in the supercritical water fluidized bed. The sealing device designed by the present invention adopts a method of combining a double-conical ferrule 19 with a polytetrafluoroethylene gasket to meet the fixing strength and sealing requirements of the capacitance probe sensor 4 in the high-pressure environment of the supercritical water fluidized bed.

[0048] Sealing device structure Figure 2 As shown, from one end to the other end, it includes a top cover 18, a double cone ferrule 19, a middle connection section of the base 20, a ring top sleeve 21, a conical cylindrical gasket 22, a lower connection section of the base 23 and a stainless steel connecting pipe 24. The head of the capacitance probe sensor 4 passes through the top cover 18, the double cone ferrule 19, the middle connection section of the base 20, the ring top sleeve 21, the conical cylindrical gasket 22, the lower connection section of the base 23 and the stainless steel connecting pipe 24 in sequence. Among them, the double cone ferrule 19 is made of brass, the conical cylindrical gasket 22 is made of polytetrafluoroethylene, and the other components are all 316 stainless steel.

[0049] The double cone ferrule 19 is inserted between the top cover 18 and the middle connecting section 20 of the base and sealed. One end of the top cover 18 is connected to one end of the middle connecting section 20 of the base through a thread, and the double cone ferrule 19 is radially pressed to achieve deformation and tightening of the ferrule and radial compression of the capacitance probe sensor 4, thereby achieving the strength requirements of the capacitance probe sensor 4 used in the supercritical water fluidized bed. A ring top sleeve 21 and a conical cylindrical gasket 22 are arranged between the middle connecting section 20 of the base and the lower connecting section 23 of the base. Through the threaded engagement of the middle connecting section 20 of the base and the lower connecting section 23 of the base, the middle connecting section 20 of the base will compress the conical cylindrical gasket 22 by pressing the ring top sleeve 21. Since the contact surface of the conical cylindrical gasket 22 and the lower connecting section 23 of the base is conical, the conical cylindrical gasket 22 will be compressed and deformed during the contact and compression process between the two, and the conical cylindrical gasket 22 will contract centripetally to compress the capacitance probe sensor 4, thereby achieving the sealing effect of the capacitance probe in the supercritical water fluidized bed. The end of the lower connecting section 23 of the base is provided with a positioning hole connected to the stainless steel connecting tube 24, the purpose is to maintain precise coaxiality with the stainless steel connecting tube 24, so that the capacitance probe sensor 4 can smoothly pass through the stainless steel connecting tube 24 and penetrate into the reactor. The stainless steel connecting tube 24 is 50 cm long, with an inner diameter of 5 mm and an outer diameter of 10 mm. One end is fixed to the lower connecting section 23 of the base by welding, and the other end is fixed to the supercritical water fluidized bed by welding. Figure 3 The assembly diagram of the capacitance probe sensor 4 and the sealing structure designed by the present invention is shown. After experimental verification, the sealing device designed by the present invention can meet the high-strength fixed sealing requirements of the capacitance probe sensor 4 used in the supercritical water fluidized bed, ensuring that the capacitance probe sensor 4 works safely and stably in the supercritical water fluidized bed.

[0050] Since the capacitance probe measurement system is not a commercial device, there is no measurement amplifier specially adapted for the capacitance probe sensor 4 in the world. Generally, the target capacitance of the capacitance probe sensor 4 is very weak, often reaching the 10-2pf level, and the target capacitance value of the self-made capacitance probe sensor 4 cannot be obtained by theoretical calculation, which causes great difficulties in measuring the target capacitance signal of the capacitance probe in the supercritical water fluidized bed. In addition, the capacitance probe sensor 4 is different from ordinary two-pole capacitors, and is a three-electrode capacitor, and the complex structure increases the signal measurement difficulty of the capacitance probe sensor 4. For this reason, the capacitance measurement amplifier 5 of the present invention is modified based on the standard measurement system of the capacitance distance micrometer, and the Accumeare 9000 / 2SP model customized by MTI Company of the United States is adopted, and a gain knob with adjustable measurement range is configured, which can realize the measurement amplification of the target capacitance of the capacitance probe sensor 4 developed by the present invention, and the outer shell ground electrode 12 of the capacitance probe sensor 4 is connected to the ground terminal of the capacitance measurement amplifier 5 by a pure copper cable, and the output signal of the capacitance measurement amplifier 5 can be collected by the data acquisition card 6 to the data processing module 7 for post-processing. The capacitance measurement amplifier 5 applies a high-frequency AC current source to the central sensing electrode 10 of the capacitance probe sensor 4 through a low-noise cable, so that a weak current path is formed between the central sensing electrode 10 and the shell grounding electrode through the measurement area. A potential difference is formed between the central sensing electrode 10 and the shell grounding electrode due to the capacitance impedance of the measurement area, and the electric field line distribution between the two is the electric field line of the measurement area. The size of the capacitance impedance will affect the strength of the loop current, thereby reflecting the microscopic characteristics of the measurement area. The measured capacitance probe signal can be used to obtain the local void ratio through linear conversion.

[0051] The measured voltage signal can be converted into the local void fraction by linear transformation, as shown in the formula

[0052]

[0053] Where ε is the measured local void fraction, ε fb is the porosity of particles in natural stacking state, U is the output signal of capacitance probe sensor 4 in supercritical water fluidized bed, and U 0 is the output signal of the capacitance probe sensor 4 in the supercritical water fluid without particles, U fb It is the output signal of the capacitance probe sensor 4 when the particles are naturally accumulated.

[0054] The above examples are only for illustration of the present invention and are not intended to limit the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A capacitance probe system suitable for a supercritical water fluidized bed, characterized in that: It includes a capacitive probe sensor (4) and a sealing device; The sealing device comprises, from one end to the other end, a top cover (18), a double-cone ferrule (19), a base middle connecting section (20), a ring top sleeve (21), a conical cylindrical gasket (22) and a base lower connecting section (23); the measuring end of the capacitance probe sensor (4) passes through the top cover (18), the double-cone ferrule (19), the base middle connecting section (20), the ring top sleeve (21), the conical cylindrical gasket (22) and the base lower connecting section (23) in sequence; The top cover (18) is fixedly connected to the middle connecting section (20) of the base, and the two are sealed by a double-cone ferrule (19); the middle connecting section (20) of the base is fixedly connected to the lower connecting section (23) of the base, and the two are sealed by a ring-top sleeve (21) and a conical cylindrical gasket (22); The capacitive probe sensor (4) is divided into a front high temperature section (1), a middle low temperature section (2) and a rear low temperature section (3) from the measuring end to the connecting end; the capacitive probe sensor (4) comprises three coaxially arranged metal electrodes and a coaxial cable connector, which are respectively a central sensing electrode (10), an active shielding electrode (11) and a shell ground electrode (12) from the inside to the outside, and the three metal electrodes extend from the front high temperature section (1) to the rear low temperature section (3); In the front high-temperature section (1), an insulating layer (25) is provided between two adjacent metal electrodes; the rear end of the insulating layer (25) extends into the middle low-temperature section (2); the cavity portion in the middle low-temperature section (2) is filled with a structural adhesive solidified layer (13); in the rear low-temperature section (3), a structural adhesive solidified layer (13) is filled between two adjacent metal electrodes, and the central sensing electrode (10) and the active shielding electrode (11) are both connected to a coaxial cable connector.

2. The capacitance probe system suitable for a supercritical water fluidized bed according to claim 1, characterized in that: The middle low-temperature section (2) is divided into two parts: a front half of the middle low-temperature section (2) connected to the front high-temperature section (1) and a rear half of the middle low-temperature section (2) connected to the rear low-temperature section (3); the rear end of the insulating layer (25) in the front high-temperature section (1) extends to the end of the front half of the middle low-temperature section (2); in the front half of the middle low-temperature section (2), a structural adhesive cured layer (13) is filled between the insulating layer (25) and the metal electrode; in the rear half of the middle low-temperature section (2), a structural adhesive cured layer (13) is filled between two adjacent metal electrodes.

3. The capacitance probe system suitable for a supercritical water fluidized bed according to claim 1, characterized in that: In the front high temperature section (1), the gap between the metal electrode and the insulating layer (25) is greater than 0.02 mm.

4. The capacitance probe system suitable for a supercritical water fluidized bed according to claim 1 or 2, characterized in that: The structural adhesive curing layer (13) is made of epoxy resin.

5. The capacitance probe system suitable for a supercritical water fluidized bed according to claim 1, characterized in that: In the tail low-temperature section (3), a coaxial terminal (14) is provided between two adjacent metal electrodes, and a structural adhesive curing layer (13) is provided between the metal electrode and the coaxial terminal (14).

6. The capacitance probe system suitable for a supercritical water fluidized bed according to claim 1, characterized in that: It also comprises a capacitance measurement amplifier (5), a data acquisition card (6) and a data processing module (7); the measurement signal of the capacitance probe sensor (4) is amplified by the capacitance measurement amplifier (5), and then transmitted to the data processing module (7) via the data acquisition card (6); the data processing module (7) processes the received signal to obtain characteristic parameters of the material in the supercritical water fluidized bed.

7. The capacitance probe system suitable for a supercritical water fluidized bed according to claim 1, characterized in that: The top cover (18) is connected to the middle connecting section (20) of the base via threads, and the middle connecting section (20) of the base is connected to the lower connecting section (23) of the base via threads.

8. The capacitance probe system suitable for a supercritical water fluidized bed according to claim 1, characterized in that: The double-cone ferrule (19) is made of brass, and the conical cylindrical gasket (22) is made of polytetrafluoroethylene.

9. The method for using the capacitance probe system suitable for a supercritical water fluidized bed according to claim 1, characterized in that: The capacitance probe sensor (4) is fixed on the supercritical water fluidized bed through a sealing device, and the capacitance probe sensor (4) is turned on for measurement to obtain an output signal of the capacitance probe sensor (4). U The local porosity of the material particles in the supercritical water fluidized bed is calculated by the following formula: ε : (1) in, ε fb It is the porosity of the material particles in the natural stacking state. U 0 is the output signal of the capacitance probe sensor (4) in the supercritical water fluid without material particles, U fb It is the output signal of the capacitance probe sensor (4) when the material particles are naturally accumulated.

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