CN114916101A - A heating rod and heating rod bundle device - Google Patents

Abstract

The heating rod and the heating rod bundle device of the invention solve the technical problem that the critical heat flux density in the rod bundle channel of the fluid under low pressure and low flow conditions cannot be studied in the prior art. The invention discloses a heating rod, comprising a heating tube, an upper conductive electrode and a lower conductive electrode; the heating tube comprises a heating tube shell and a hollow ceramic fixing tube arranged in the heating tube shell along the axial direction, and the outer side of the ceramic fixing tube is along the axis A plurality of temperature measuring rings are arranged at intervals, and each temperature measuring ring is provided with a plurality of grooves, and each groove is provided with a thermocouple, and the connecting wires of each thermocouple converge in the heating tube along the outer wall of the ceramic fixed tube , which protrudes axially from the inside of the upper conductive electrode. The invention also discloses a heating rod bundle device, comprising a heating rod bundle composed of a plurality of heating rods, a positive electrode assembly, a negative electrode assembly, a current shunt, a positive electrode conductive connection device, a DC power supply and a negative electrode conductive connection device.

Description

A heating rod and heating rod bundle device

technical field

The invention belongs to the field of reactor thermal hydraulic experiment research, in particular to a heating rod and a heating rod bundle device.

Background technique

The critical heat flux density is a key factor limiting heat transfer, and it is very important to the safety of the reactor. When the heat flux density on the surface of the fuel element exceeds a certain limit value, it will cause the surface temperature of the fuel element to rise sharply, and in severe cases it may lead to the fuel element. breakage, leakage of radioactive material, so predicting the magnitude of the critical heat flux is critical to the safety of the reactor.

In the research of reactor thermal safety, it is common to use the experimental method to study the critical heat flux. Since the nuclear fuel in the nuclear fuel rod is radioactive, in the actual experiment, the nuclear fuel element cannot be directly used for thermal and hydraulic experimental research, but the electric heating rod is used instead of the nuclear fuel element for the experiment. Carry out corresponding experimental studies.

Different reactors have different arrangements of fuel elements and different gaps between fuel rods. Pulse reactor is a research reactor with low pressure natural circulation heat exchange, and the arrangement of fuel elements is different from that of conventional pressurized water reactor. At present, there are many literatures on the experimental research on the critical heat flux density under the high pressure condition of the circular tube and annular structure, but there are few studies on the critical heat flux density of the rod bundle channel. There is a large error in the density prediction, so it is necessary to conduct a corresponding experimental study on the critical heat flux density in the low-pressure rod bundle channel.

SUMMARY OF THE INVENTION

In order to solve the technical problem that the prior art cannot study the critical heat flux density in the rod bundle channel of the fluid under low pressure and low flow conditions, the present invention provides a heating rod and a heating rod bundle device, and the specific technical scheme is as follows:

A heating rod, which is special in that it comprises: a heating tube, an upper conductive electrode and a lower conductive electrode respectively arranged at both ends of the heating tube in the axial direction; A hollow ceramic fixing tube in the tube shell, a plurality of temperature measuring rings are arranged on the outer side of the ceramic fixing tube at intervals along the axial direction, each of the temperature measuring rings is provided with a plurality of grooves, and each of the grooves is provided with a plurality of grooves. Thermocouples are installed, and the connecting wires of each thermocouple converge along the outer wall of the ceramic fixed tube in the heating tube, and extend axially from the interior of the upper conductive electrode; the lower end of the ceramic fixed tube is connected to the lower conductive electrode.

Further, the temperature measurement ring has a C-shaped structure, so as to realize multi-point temperature measurement at different positions; the probe of the thermocouple and the temperature measurement ring are welded by silver brazing, thereby improving the temperature measurement accuracy of the device.

Further, an insulating heat-conducting sleeve is arranged between each of the temperature measuring rings and the heating tube shell, and the insulating heat-conducting sleeve is made of boron nitride, which has good heat-conducting performance and insulation, which can prevent the temperature-measuring probe from conducting electricity, thereby affecting the thermal conductivity. The thermocouple is functioning normally.

Further, the upper conductive electrode is provided with a hollow ceramic tube, the upper end of the ceramic tube and the upper end of the upper conductive electrode are connected by an insulating locking nut, and there is a gap between the lower end and the ceramic fixing tube.

Further, the length of the heating tube and the thickness of the heating tube shell can be adjusted, so as to realize different heating power according to the actual application scenario.

Further, silver brazing is used between the upper conductive electrode, the heating tube and the lower conductive electrode, so as to improve the machining accuracy of the device.

The invention also provides a heating rod bundle device, comprising a heating rod bundle composed of a plurality of heating rods, a positive electrode assembly and a negative electrode assembly respectively sleeved on both ends of the heating rod bundle, and a current shunt arranged in sequence along the circuit return direction , a positive electrode conductive connection device, a DC power supply and a negative electrode conductive connection device; and a voltage transmitter arranged between the positive electrode assembly and the negative electrode assembly.

Further, the positive electrode assembly and the negative electrode assembly are respectively composed of a plurality of electrode clips, and the plurality of electrode clips are composed of a plurality of middle electrode clips and two end electrode clips, and a power interface is provided on the radial outer side of the end electrode clips. , the inner side is provided with a plurality of first grooves of the same size along the axial direction; the radial sides of the middle electrode clip are respectively provided with a plurality of second grooves of the same size along the axial direction, the first groove and the second groove are respectively provided with the same size along the axial direction. The size of the two grooves is also the same; the position between the first groove and the second groove adjacent to the first groove, and the adjacent middle electrode is sandwiched between the second grooves on the adjacent side They correspond to each other, and are respectively surrounded by a plurality of first through holes, the plurality of first through holes correspond to the arrangement of the heating rods, and the inner diameter of the first through holes is the same as the outer diameter of the heating rods; The heating rods are clamped and fixed in the corresponding first through holes through bolts respectively.

Further, an insulating sheath can be added in the first through hole to realize the independent heating function of the heating rod, thereby improving the applicability of the device.

Further, the DC power supply adopts a low-voltage and high-current power supply mode, the maximum voltage is 25V, and the maximum current is 20000A, which is more suitable for testing under low-voltage conditions compared with the prior art, and is more in line with the requirements of electricity safety. .

The beneficial effects of the present invention are:

1. The heating rod of the present invention includes a heating tube, an upper conductive electrode and a lower conductive electrode. A plurality of temperature measurement rings are arranged in the heating tube, and a plurality of thermocouples are arranged on the temperature measurement ring to realize multi-point temperature measurement. The measurement can accurately obtain the temperature of the fluid.

2. The present invention realizes the adjustable output power of the heating rod by rationally designing the thickness of the heating pipe and using the corresponding voltage and current to realize the power input, thereby improving its applicability.

3. The present invention adopts the structural design of brazing the thermocouple silver in the temperature measuring ring, which can flexibly arrange multiple temperature measuring points according to the requirements, and can obtain accurate measuring results.

4. The arrangement of the heating rod bundle structure of the present invention is the same as the arrangement of the fuel elements of the pulse reactor, which can satisfy the experimental study of the critical heat flux density under the low pressure working condition of the pulse reactor.

5. The heating rod bundle device of the present invention can realize the independent control of each heating rod by adding an insulating sleeve between the heating rod and the electrode assembly, especially for the operating conditions where the temperature of the middle channel is high and the temperature of the surrounding channel is low. Experimental Study.

6. The materials of the positive electrode assembly, the negative electrode assembly, the temperature measuring ring, the upper conductive electrode and the lower conductive electrode of the present invention are all T2 oxygen-free red copper, which has good conductivity and low cost.

7. The material of the heating tube is Inconel 625, which has good oxidation resistance and strong acid and alkali corrosion resistance, which can not only provide accurate data support for the test results, but also improve the overall service life of the device.

Description of drawings

FIG. 1 is an axial cross-sectional view of a heating rod structure according to an embodiment of the present invention.

2 is a cross-sectional view of a temperature measuring ring structure in a heating rod structure according to an embodiment of the present invention.

3 is a top view of a temperature measuring ring in a heating rod structure according to an embodiment of the present invention.

FIG. 4 is a reference diagram for the arrangement of a plurality of temperature measuring rings in a heating rod structure according to an embodiment of the present invention.

FIG. 5 is a schematic structural diagram of a heating rod bundle device according to an embodiment of the present invention.

6 is a radial cross-sectional view of a positive electrode assembly or a negative electrode assembly in a heating rod bundle device structure according to an embodiment of the present invention.

The reference numbers are as follows:

1- Heating rod bundle, 2- Positive electrode assembly, 3- Negative electrode assembly, 4- DC power supply, 5- Current shunt, 6- Voltage transmitter, 7- Positive electrode conductive connection device, 8- Negative electrode conductive connection device, 9- Heating rod, 10-heating tube, 11-connecting wire, 12-insulation lock nut, 13-ceramic tube, 14-upper conductive electrode, 15-insulated heat-conducting sleeve, 16-temperature measuring ring, 17-ceramic fixing tube , 18-heating tube shell, 19-lower conductive electrode, 20-thermocouple, 21-electrode clip, 22-power interface, 23-first through hole, 24-bolt, 25-middle electrode clip, 26-end Electrode clip, 27-first groove, 28-second groove.

Detailed ways

In order to make the purpose, advantages and features of the present invention clearer, a heating rod and a heating rod bundle device proposed by the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will be clearer according to the following specific embodiments. It should be noted that the accompanying drawings are in simplified form and use inaccurate scales, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention. In the present invention, the terms "upper end", "upper", "upper", etc. refer to one end close to the positive electrode assembly 2, "lower end", "bottom", "lower", etc. refer to the end close to the negative electrode assembly 3, and the terms "first", "second", etc. only Used for descriptive purposes and should not be construed as indicating or implying relative importance.

The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

As shown in FIG. 1 , this embodiment provides a heating rod, which includes a heating tube 10 , an upper conductive electrode 14 and a lower conductive electrode 19 respectively disposed at both ends of the heating tube 10 in the axial direction, the upper conductive electrode 14 , the heating tube 10 and the lower conductive electrode 19 . Silver brazing is used between the conductive electrodes 19, and the materials of the upper conductive electrodes 14 and the lower conductive electrodes 19 are T2 oxygen-free red copper. The heating tube 10 includes a heating tube housing 18 and a hollow ceramic fixing tube 17 arranged in the heating tube housing 18 along the axial direction. The length of the heating tube 10 and the thickness of the heating tube housing 18 can be adjusted. The material of the heating pipe 10 is Inconel 625, which has good oxidation resistance, strong acid and alkali corrosion resistance, and can prolong the service life.

1 and 2, the lower end of the ceramic fixing tube 17 is connected to the lower conductive electrode 19; the outer side of the ceramic fixing tube 17 is provided with a plurality of temperature measuring rings 16 at intervals along the axial direction. Good electrical conductivity and good oxidation resistance. An insulating heat-conducting sleeve 15 is arranged between each temperature measuring ring 16 and the heating tube shell 18. The insulating heat-conducting sleeve 15 is made of boron nitride material, which is resistant to high temperature, has a high melting point, has good thermal conductivity and is insulated, and can avoid The temperature probe conducts electricity, which affects the normal operation of the thermocouple and improves the accuracy of the measurement results.

1, 2 and 3, the temperature measuring ring 16 has a C-shaped structure, each temperature measuring ring 16 is provided with a plurality of grooves, and each groove is provided with a thermocouple 20 and a probe of the thermocouple 20. It is welded with the temperature measuring ring 16 by silver brazing, and the thermocouple 20 is an armored thermocouple, which is resistant to high temperature and has a fast thermal response time, which can improve the efficiency and accuracy of measurement. The connecting wires 11 of each thermocouple 20 converge along the outer wall of the ceramic fixing tube 17 in the heating tube 10 , and extend axially from the interior of the upper conductive electrode 14 . A plurality of thermocouples 20 for temperature measurement are arranged in the temperature measurement ring 16 to avoid the problem that when the temperature of the inner wall surface of the heating tube shell 18 rises, the local area is not at the arranged temperature measurement point, resulting in inaccurate measurement results. Multi-point settings can improve the accuracy of measurement results.

As shown in FIG. 1 , a hollow ceramic tube 13 is provided inside the upper conductive electrode 14 , the upper end of the ceramic tube 13 is connected with the upper end of the upper conductive electrode 14 by an insulating locking nut 12 , and there is a gap between the lower end of the ceramic tube 13 and the ceramic fixing tube 17 , so that the connecting wires 11 of the plurality of thermocouples 20 converge and extend into the upper conductive electrode 14 through the gap, and then the heating rod 9 is extended, and is connected with an external device (not shown in the figure) to measure the relevant parameters and read.

As shown in FIG. 4 , the position of the temperature measuring ring 16 is set according to the length of the heating tube 10 and the actual demand. The temperature measuring ring 16 is arranged on the inner wall of the heating tube shell 18 from top to bottom in the axial direction, generally from the top to the bottom. The distance between the adjacent temperature measuring rings 16 from top to bottom increases in turn. Due to the critical heat flux density experiment, the area where the local wall temperature increases is generally in the upper part of the heating section. Generally, the distance between the multiple temperature measuring rings 16 in the upper part is 20-30mm, and the distance between the plurality of temperature measuring rings 16 in the lower part can be 40-80mm, so as to improve the accuracy of the measurement results.

As shown in FIG. 5 , the present invention also provides a heating rod bundle device, comprising a heating rod bundle 1 composed of a plurality of heating rods 9, a positive electrode assembly 2 and a negative electrode assembly 3 respectively sleeved on both ends of the heating rod bundle 1, And the current shunt 5, the positive electrode conductive connection device 7, the DC power supply 4 and the negative electrode conductive connection device 8 arranged in sequence along the circuit return direction, the DC power supply 4 adopts the power supply mode of low voltage and high current, the maximum voltage is 25V, and the maximum current is 20000A , the maximum power can reach 500kW, which can simulate the pulse reactor reaction realistically and provide strong support for the acquisition of relevant parameters. The heating rod bundle device also includes a voltage transmitter 6 disposed between the positive electrode assembly 2 and the negative electrode assembly 3 .

As shown in FIG. 6, the positive electrode assembly 2 and the negative electrode assembly 3 are respectively composed of a plurality of electrode clips 21, and the plurality of electrode clips 21 are composed of a plurality of middle electrode clips 25 and two end electrode clips 26, and the end electrode clips 26 diameter A power interface 22 is provided on the outside for connecting an external power source, and a plurality of first grooves 27 with the same size are provided on the inside along the axial direction; For the second groove 28, the dimensions of the first groove 27 and the second groove 28 are also the same; between the first groove 27 and the second groove 28 adjacent to the first groove 27, two adjacent The positions between the second grooves 28 on the adjacent side of the middle electrode clip 25 correspond to each other, and respectively enclose a plurality of first through holes 23 , and the plurality of first through holes 23 correspond to the arrangement of the heating rods 9 , and The inner diameter of the first through hole 23 is the same as the outer diameter of the heating rod 9 ; the heating rod 9 is clamped and fixed in the corresponding first through hole 23 by bolts 24 between the electrode clips 21 respectively.

As a preferred solution of the present invention, when installing the heating rod bundle device, one or several heating rods can be realized by adding a corresponding number of insulating sheaths in the first through hole 23 of the positive electrode assembly 2 or the negative electrode assembly 3 The specific installation method is as follows: when installing, first set the insulating sheath on the heating rod (at the position corresponding to the first through hole 23), and then fasten each electrode clip 21 by the bolt 24. This method The real situation of different core arrangements in the pulsed reactor can be simulated realistically.

Through the technical scheme of the present invention, the critical heat flux density in the rod bundle channel of the fluid under low pressure and low flow conditions can be studied, which fills the gap in the industry and provides strong theoretical and data support for the study of the real pulse reactor reaction process. .

The above content is only used to illustrate the present invention, and it cannot be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, as long as the changes to the above embodiments are within the spirit and scope of the present invention and modifications should be considered within the scope of the claims of the present invention.

Claims (10)

1. A heating rod, characterized in that, comprising: a heating pipe (10), an upper conductive electrode (14) and a lower conductive electrode (19) respectively arranged at both ends of the heating pipe (10) in the axial direction; The heating tube (10) comprises a heating tube housing (18), and a hollow ceramic fixing tube (17) arranged in the heating tube housing (18) in the axial direction, and the outer side of the ceramic fixing tube (17) is along the axis A plurality of temperature measurement rings (16) are arranged at intervals, each of the temperature measurement rings (16) is provided with a plurality of grooves, and each of the grooves is provided with a thermocouple (20), and each thermoelectric The connecting wires (11) of the couple (20) converge along the outer wall of the ceramic fixing tube (17) in the heating tube (10), and extend axially from the interior of the upper conductive electrode (14); the ceramic fixing tube (17) The lower end is connected to the lower conductive electrode (19). 2. a kind of heating rod according to claim 1 is characterized in that: The temperature measuring ring (16) has a C-shaped structure, and the probe of the thermocouple (20) and the temperature measuring ring (16) are welded by silver brazing. 3. a kind of heating rod according to claim 2 is characterized in that: An insulating heat-conducting sleeve (15) is arranged between each of the temperature measuring rings (16) and the heating tube casing (18). 4. a kind of heating rod according to claim 3 is characterized in that: A hollow ceramic tube (13) is arranged inside the upper conductive electrode (14), the upper end of the ceramic tube (13) is connected with the upper end of the upper conductive electrode (14) through an insulating locking nut (12), and the lower end is fixed with the ceramic There is a gap between the tubes (17). 5. a kind of heating rod according to claim 4 is characterized in that: The length of the heating tube (10) and the thickness of the heating tube shell (18) can be adjusted. 6. a kind of heating rod according to claim 5 is characterized in that: Silver brazing is used between the upper conductive electrode (14), the heating tube (10) and the lower conductive electrode (19). 7. A heating rod bundle device, characterized in that: comprising a heating rod bundle (1) consisting of a plurality of heating rods (9), a positive electrode assembly (2) and a negative electrode respectively sleeved on both ends of the heating rod bundle (1) The component (3), and the current shunt (5), the positive electrode conductive connection device (7), the DC power supply (4), and the negative electrode conductive connection device (8) arranged in sequence along the circuit return direction; also include a positive electrode assembly (2) ) and the voltage transmitter (6) between the negative assembly (3). 8. A heating rod bundle device according to claim 7, characterized in that: The positive electrode assembly (2) and the negative electrode assembly (3) are respectively composed of a plurality of electrode clips (21), and the plurality of electrode clips (21) are composed of a plurality of middle electrode clips (25) and two end electrode clips (26) The end electrode clip (26) is provided with a power interface (22) on the radial outer side, and a plurality of first grooves (27) with the same size are arranged on the inner side along the axial direction; the middle electrode clip (25) has a diameter of A plurality of second grooves (28) with the same size are respectively provided on both sides in the axial direction, and the first grooves (27) and the second grooves (28) are also of the same size; the first grooves The position between (27) and the second groove (28) adjacent to the first groove (27), and between the second groove (28) on the adjacent side of the adjacent middle electrode clip (25) They correspond to each other and are respectively surrounded by a plurality of first through holes (23), the plurality of first through holes (23) correspond to the arrangement of the heating rods (9), and the inner diameter of the first through holes (23) is the same as that of the heating rods (9). The outer diameters of the heating rods (9) are the same; the heating rods (9) are clamped and fixed in the corresponding first through holes (23) by bolts (24) between the electrode clamps (21). 9. A heating rod bundle device according to claim 8, wherein: An insulating sheath can be added to the first through hole (23) to realize the independent heating function of the heating rod (9). 10. A heating rod bundle device according to claim 9, characterized in that: The DC power supply (4) adopts the power supply mode of low voltage and high current, the maximum voltage is 25V, and the maximum current is 20000A.

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