Continuous high-temperature sintering furnace for nuclear fuel pellets

Abstract

The utility model discloses a nuclear fuel pellet continuous high-temperature sintering furnace which comprises a first boat pushing mechanism, a feeding chamber, a hydrogen burning opening, a furnace body, a cooling mechanism, a discharging chamber and a second boat pushing mechanism which are sequentially arranged, the furnace body is divided into a low-temperature area, a high-temperature area and a slow cooling area, and the high-temperature area is located between the low-temperature area and the slow cooling area. Muffles are arranged in the low-temperature area and the high-temperature area, molybdenum heating bodies are arranged outside the Muffles in the furnace body, and an air inlet pipe for conveying dry hydrogen is arranged on the furnace body and used for enabling the air pressure outside the Muffles to be larger than the air pressure in the Muffles. Compared with the prior art, the nuclear fuel pellet continuous high-temperature sintering furnace has the advantages that the common temperature can be kept at 1750 DEG C, and the highest furnace temperature is 1800 DEG C. Heating is conducted in the low-temperature area and the high-temperature area in the mode that the muffle and the molybdenum heating body are combined, so that enough furnace temperature can be obtained, meanwhile, the muffle is matched with the air inlet pipe, water vapor in the muffle can run out of the muffle to erode the molybdenum heating body as little as possible, and therefore the service life of the molybdenum heating body is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of sintering furnaces, in particular to a continuous high-temperature sintering furnace for nuclear fuel pellets. Background Art

[0002] High temperature sintering furnace is the key equipment for the production of nuclear fuel pellets, and its performance directly affects the ceramic transformation process of pellet sintering.

[0003] High temperature sintering furnaces must not only meet the nuclear fuel pellet sintering process requirements for temperature, atmosphere, sealing and other performance indicators, but also ensure that the equipment is absolutely safe and reliable. Continuous high temperature sintering furnaces have the advantages of high output, low energy consumption and good product consistency, but the traditional continuous high temperature sintering furnace has a maximum furnace temperature of 1700℃, which cannot meet the process requirements of nuclear fuel pellet sintering, and the equipment has problems such as short heating element life, short furnace brick life, hydrogen leakage at the furnace mouth, and water leakage in the cooling section. Utility Model Content

[0004] The utility model provides a continuous high-temperature sintering furnace for nuclear fuel pellets, which is used to solve at least one of the above technical problems.

[0005] The utility model provides a continuous high-temperature sintering furnace for nuclear fuel pellets, comprising a first boat-pushing mechanism, a feeding chamber, a hydrogen burning port, a furnace body, a cooling mechanism, a discharging chamber and a first boat-pushing mechanism which are arranged in sequence, wherein the furnace body is divided into a low-temperature zone, a high-temperature zone and a slow cooling zone, wherein the high-temperature zone is located between the low-temperature zone and the slow cooling zone, and muffles are arranged in both the low-temperature zone and the high-temperature zone, a molybdenum heating element is arranged outside the muffle in the furnace body, and an air inlet pipe for conveying dry hydrogen is arranged on the furnace body, so as to make the air pressure outside the muffle greater than the air pressure inside the muffle.

[0006] Preferably, the feed chamber and the discharge chamber are both provided with a furnace door and an isolation door, and the feed chamber and the discharge chamber are also provided with a vacuum extraction system and a nitrogen supply mechanism. When the furnace door and the isolation door are closed, the feed chamber and the discharge chamber are filled with nitrogen through the nitrogen supply mechanism.

[0007] Preferably, the furnace door and the isolation door are both connected with a sealing device, and the sealing device includes: a bracket, a guide wedge, a guide wheel, a guide rail, a sealing ring, a hydraulic cylinder and a lifting rod. The sealing ring is respectively arranged between the furnace door and the door frame and between the isolation door and the door frame. The guide wheel fixed on the bracket rolls up and down along the guide rail. The guide wedge is respectively fixed on the furnace door and the isolation door. The hydraulic cylinder is fixedly connected to the bracket. One end of the lifting rod is fixed on the bracket, and the other end slides in the guide groove of the guide wedge to drive the furnace door to compress the sealing ring or the isolation door to compress the sealing ring.

[0008] Preferably, the sealing device comprises two travel switches, one of which is used to detect the position of the piston rod of the hydraulic cylinder, and the other of which is used to detect the positions of the furnace door and the isolation door.

[0009] Preferably, a sealing layer is provided on the outer side of the furnace body, and the furnace chamber of the furnace body includes a furnace bottom, a furnace top and a furnace wall. Track bricks and support bricks are provided on the furnace bottom, and the track bricks are laid flat on the support bricks. A gap is reserved between two adjacent track bricks, and a snap-on structure is provided between the track bricks and the support bricks. Side wall bricks are provided on the inner side of the furnace wall, and the side wall bricks are stacked from bottom to top, and the protrusion of the lower side wall brick is inserted into the limiting groove of the upper side wall brick. A V-shaped groove is provided on the upper end of the furnace wall, and refractory bricks, hollow ball bricks and insulation bricks are provided in sequence in the V-shaped groove from bottom to top.

[0010] Preferably, a dry hydrogen curtain generating device is provided at one end of the low temperature zone away from the high temperature zone and at one end of the slow cooling zone away from the high temperature zone.

[0011] Preferably, a waste discharge pipe is provided between the low temperature zone and the high temperature zone, and a hydrogen combustion device is provided at the top of the waste discharge pipe.

[0012] Preferably, the feed chamber and the discharge chamber are also provided with a vacuum gauge and a pressure sensor.

[0013] Preferably, the molybdenum heating element includes a plurality of vertically arranged straight segments, and the straight segments are connected by curved segments.

[0014] Preferably, the cooling mechanism comprises: a cooling chamber, a top cooling jacket, a side cooling jacket and a bottom cooling jacket, the top cooling jacket and the bottom cooling jacket are respectively arranged above and below the cooling chamber, the two side cooling jackets are respectively arranged on both sides of the cooling chamber, and a sealing shell is provided on the outside of the cooling chamber.

[0015] Preferably, heat-conducting mud is provided on the outer side of the sealing shell.

[0016] Preferably, the supporting bricks are embedded between the corundum bricks, and the track bricks are provided with guide slopes, which extend downward from the track surface of the track bricks.

[0017] Preferably, the track bricks are formed with baffles on both sides of the track surface, and the guide slopes are provided with guide slopes connected to the baffles on both sides, and the distance between the two guide slopes close to one end of the baffle is smaller than the distance between the other ends.

[0018] Compared with the prior art, the conventional temperature of the nuclear fuel pellet continuous high temperature sintering furnace of the utility model can be maintained at 1750°C and the highest furnace temperature is 1800°C. In the low temperature zone and the high temperature zone, heating is performed by combining the muffle and the molybdenum heating element so as to obtain a sufficient furnace temperature. At the same time, the muffle cooperates with the air inlet pipe so that the water vapor in the muffle can run to the outside of the muffle as little as possible to corrode the molybdenum heating element, thereby extending the service life of the molybdenum heating element. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the structure of the utility model;

[0021] Figure 2 The utility model is a cross-sectional view Figure 1 ;

[0022] Figure 3 The utility model is a cross-sectional view Figure 2 ;

[0023] Figure 4 It is a structural schematic diagram of the feed chamber of the utility model;

[0024] Figure 5 It is a structural schematic diagram of the boat entering the feed chamber of the utility model;

[0025] Figure 6 It is a structural schematic diagram of the boat feeding chamber of the utility model;

[0026] Figure 7 It is a structural schematic diagram of the furnace body of the utility model;

[0027] Figure 8 It is a cross-sectional schematic diagram of the low temperature zone of the utility model;

[0028] Fig. 9 It is a cross-sectional schematic diagram of the furnace body of the utility model;

[0029] Fig.10 It is a structural schematic diagram of the sealing device of the utility model;

[0030] Fig.11 It is a structural schematic diagram of the guide wedge of the utility model;

[0031] Fig.12It is a structural schematic diagram of the track brick of the utility model;

[0032] Fig.13 for Fig. 9 A magnified schematic diagram of the structure at C in the middle;

[0033] Fig.14 It is a schematic diagram of the structure of the cooling mechanism of the utility model;

[0034] Fig.15 It is a structural schematic diagram of the molybdenum heating element of the utility model.

[0035] Reference numerals:

[0036] 1. First boat pushing mechanism, 2. Feeding chamber, 3. Hydrogen burning port, 4. Furnace body, 5. Cooling mechanism, 6. Discharging chamber, 100. Low temperature zone, 200. High temperature zone, 300. Slow cooling zone, 7. Muffle, 8. Molybdenum heating element, 9. Inlet pipe, 010. Furnace door, 011. Isolation door, 012. Vacuum pumping system, 013. Nitrogen supply mechanism, 014. Dry hydrogen curtain generating device, 015. Waste discharge pipe, 016. Vacuum gauge, 017. Pressure sensor, 019. Boat, 41. Furnace bottom, 42. Furnace top, 43. Furnace wall, 411. Track brick, 412. Support brick, 413. Buckle joint Structure, 414. Corundum brick, 4111. Track surface, 4112. Guide slope, 4113. Baffle, 4114. Guide slope, 4131. Block, 4132. Slot, 431. Side wall brick, 400. V-groove, 421. Refractory brick, 422. Hollow ball brick, 423. Insulation brick, 51. Cooling cavity, 52. Top cooling jacket, 53. Side cooling jacket, 54. Bottom cooling jacket, 81. Straight section, 82. Curved section, 020. Bracket, 021. Guide wedge, 0211. Guide groove, 022. Guide wheel, 023. Guide rail, 024. Lifting rod, 025. Hydraulic cylinder. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be described clearly and completely in conjunction with the drawings in the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0038] Refer to the attached Figure 1 The utility model provides a continuous high-temperature sintering furnace for nuclear fuel pellets, comprising a first boat-pushing mechanism 1, a feeding chamber 2, a hydrogen burning port 3, a furnace body 4, a cooling mechanism 5, a discharging chamber 6 and a first boat-pushing mechanism 1, which are arranged in sequence. Figure 1In the figure, A is the feed port and B is the discharge port. Figure 7 The furnace body 4 is divided into a low temperature zone 100, a high temperature zone 200 and a slow cooling zone 300. The low temperature zone 100 is used to preheat the product to be sintered, and the high temperature zone 200 is located between the low temperature zone 100 and the slow cooling zone 300. Figure 8 The low temperature zone 100 and the high temperature zone 200 are both provided with a muffle 7, a molybdenum heating element 8 is provided outside the muffle 7 in the furnace body 4, and an air inlet pipe 9 for conveying dry hydrogen is provided on the furnace body 4, so as to make the air pressure outside the muffle 7 greater than the air pressure inside the muffle 7. The continuous high temperature sintering furnace for nuclear fuel pellets designed by the utility model can maintain a common temperature of 1750°C and a maximum furnace temperature of 1800°C. In the low temperature zone 100 and the high temperature zone 200, heating is performed by combining the muffle 7 and the molybdenum heating element 8 so as to obtain a sufficient furnace temperature. At the same time, the muffle 7 cooperates with the air inlet pipe 9 so that the water vapor in the muffle 7 can run to the outside of the muffle 7 as little as possible to corrode the molybdenum heating element 8, thereby extending the service life of the molybdenum heating element 8.

[0039] Refer to the attached Figure 4-6 The feeding chamber 2 and the discharging chamber 6 are both provided with a furnace door 010 and an isolation door 011. The feeding chamber 2 and the discharging chamber 6 are also provided with a vacuum system 012 and a nitrogen supply mechanism 013. When the furnace door 010 and the isolation door 011 are closed, the feeding chamber 2 and the discharging chamber 6 are filled with nitrogen through the nitrogen supply mechanism 013. By adopting the double sealing door structure of the furnace door 010 and the isolation door 011, it is ensured that there is always a sealed door closed during the feeding and discharging process, and then the vacuum system 012 and the nitrogen supply mechanism 013 are cooperated to reduce the risk of hydrogen leakage or air entering the furnace, and at the same time, the furnace pressure can be maintained stable, so as to obtain a stable furnace temperature.

[0040] Refer to the attached Figure 2-3A sealing layer is provided on the outside of the furnace body 4, and the furnace chamber of the furnace body 4 includes a furnace bottom 41, a furnace top 42 and a furnace wall 43. Track bricks 411 and support bricks 412 are provided on the furnace bottom 41. The track bricks 411 are laid flat on the support bricks 412, and a gap is reserved between two adjacent track bricks 411. A snap-fit ​​structure 413 is provided between the track bricks 411 and the support bricks 412. Side wall bricks 431 are provided on the inner side of the furnace wall 43. The side wall bricks 431 are stacked from bottom to top, and the protrusions of the lower side wall bricks 431 are inserted into the limiting grooves of the upper side wall bricks 431. A V-shaped groove 400 is provided on the upper end of the furnace wall 43. Refractory bricks 421, hollow ball bricks 422 and insulation bricks 423 are provided in the V-shaped groove 400 from bottom to top. The furnace bottom 41, furnace wall 43 and furnace roof 42 of the furnace chamber adopt dry-masonry and mortise and tenon structures. The track bricks 411 and support bricks 412 of the furnace bottom 41 are fixed by a snap-fit ​​structure 413, and the side wall bricks 431 of the furnace wall 43 are fixed by snap-fitting, thereby avoiding the high-temperature refractory clay burning phenomenon of the traditional furnace body 4 and improving the stability of the furnace structure. Then, the outer side of the furnace body 4 is sealed by a sealing layer, so that a more stable and higher furnace temperature can be obtained.

[0041] The working process of feeding the boat 019 at the feeding chamber 2 is as follows:

[0042] Refer to the attached Figure 4 When the isolation door 011 is closed, the furnace door 010 is opened and the boat 019 is pushed into the feeding chamber 2.

[0043] One-time replacement process: refer to the attached Figure 5 , close the furnace door 010, open the vacuum system 012, extract the air in the feed chamber 2, then open the nitrogen supply mechanism 013 to start filling with nitrogen, and stop filling with nitrogen when the air pressure in the feed chamber 2 is consistent with that in the furnace.

[0044] Furnace feeding process: refer to the attached Figure 6 When the furnace door 010 is closed, the isolation door 011 is opened and the boat 019 is pushed from the feed chamber 2 into the furnace.

[0045] Secondary replacement process: close the isolation door 011, start the vacuum system 012, pump out the air in the feed chamber 2, and then start the nitrogen supply mechanism 013 to start filling nitrogen. Stop filling nitrogen when the air pressure in the feed chamber 2 is consistent with that in the furnace. This setting can effectively prevent the air outside the furnace door 010 from entering the feed chamber 2 and then entering the furnace from the feed chamber 2. Secondly, it can also maintain the furnace pressure stable and prevent hydrogen leakage in the furnace.

[0046] As another embodiment of the present invention: Figure 10-11The furnace door 010 and the isolation door 011 are both connected with a sealing device, which includes: a bracket 020, a guide wedge block 021, a guide wheel 022, a guide rail 023, a sealing ring, a hydraulic cylinder 025 and a lifting rod 024. The sealing rings are respectively arranged between the furnace door 010 and the door frame and between the isolation door 011 and the door frame. The guide wheel 022 fixed on the bracket 020 rolls up and down along the guide rail 023. The guide wedge block 021 is respectively fixed on the furnace door 010 and the isolation door 011. The hydraulic cylinder 025 is fixedly connected to the bracket 020. One end of the lifting rod 024 is fixed on the bracket 020, and the other end slides in the guide groove 0211 of the guide wedge block 021 to drive the sealing door to press the sealing ring. The furnace door 010 and the isolation door 011 are both sealed doors. The guide groove 0211 is inclined. When the hydraulic cylinder 025 drives the bracket 020 to move up and down, the bracket 020 will drive the lifting rod 024 to move up and down. During the movement of the lifting rod 024, when the lifting rod 024 is not moving in the guide groove 0211, it will drive the guide wedge 021 to move up and down. When the lifting rod 024 moves in the guide groove 0211, it will drive the sealing door to approach the door frame or move away from the door frame. Take the furnace door 010 as an example for analysis. The piston rod of the hydraulic cylinder 025 is fixed to the bracket 020. The guide wheel 022 on the bracket 020 rolls up and down along the guide rail 023. When the piston rod of the hydraulic cylinder 025 extends downward, the lifting rod 024 drives the furnace door 010 to descend through the guide wedge 021. After the furnace door 010 descends to the limit position, the lifting rod 024 moves to the bottom of the guide groove 0211, driving the furnace door 010 to approach the door frame, so that the sealing ring between the door frame and the furnace door 010 is compressed to improve the sealing effect. When the piston rod of the hydraulic cylinder 025 retracts, the lifting rod 024 moves to the top of the guide groove 0211, and the furnace door 010 moves away from the door frame to release the sealing effect. At the same time, the furnace door 010 also moves upward. By setting a sealing device, the sealing door can move up and down while also moving horizontally, thereby improving the sealing effect of the furnace door 010 and facilitating the stability of the pressure in the furnace. The entire sealing device has a simple structure, few faults, and can better adapt to the requirements of harsh environments.

[0047] Specifically, there are two travel switches for detecting the closing state of the sealing door. One travel switch is used to detect the position of the piston rod of the hydraulic cylinder 025, and the other travel switch is used to detect the position of the sealing door. Double protection is provided to improve the safety of the sealing device.

[0048] As another embodiment of the present invention: a vacuum gauge 016 and a pressure sensor 017 are also provided on the feed chamber 2 and the discharge chamber 6. By referring to the vacuum value on the vacuum gauge 016, it is convenient for the vacuum pumping system 012 to accurately evacuate the feed chamber 2 or the discharge chamber 6, and by referring to the pressure value on the pressure sensor 017, it is convenient for the nitrogen supply mechanism 013 to accurately fill the feed chamber 2 or the discharge chamber 6 with nitrogen.

[0049] As another embodiment of the present invention: a dry hydrogen gas curtain generating device 014 is provided at one end of the low-temperature zone 100 away from the high-temperature zone 200 and at one end of the slow cooling zone 300 away from the high-temperature zone 200. The dry hydrogen gas curtain generating device 014 is provided to form a dry hydrogen gas curtain. The dry hydrogen flows toward the middle of the furnace to block the wet hydrogen from entering the cold end, thereby effectively reducing the generation of condensed water at the feed end and the discharge end.

[0050] Specifically, a stopcock and a glass rotor flowmeter are provided on the air inlet pipe 9, so as to facilitate controlling the flow rate of the hydrogen inlet point when adjusting the stopcock.

[0051] As another embodiment of the present utility model: an exhaust pipe 015 is arranged between the low-temperature zone 100 and the high-temperature zone 200, and a hydrogen combustion device is arranged at the top of the exhaust pipe 015. Hydrogen and by-products are transported to the hydrogen combustion device through the exhaust pipe 015. The hydrogen combustion device fully burns the combustible components in the exhaust gas, and also produces a chimney effect, which promotes the airflow in the furnace to flow in a directional manner from the feed end and the discharge section of the furnace to the middle exhaust pipe 015.

[0052] As another embodiment of the present invention: Fig.15 The molybdenum heating element 8 includes a plurality of vertically arranged straight segments 81, and the straight segments 81 are connected by curved segments 82, which structurally increase the surface heat load of the heating element as much as possible, thereby increasing the rated temperature of the furnace. The molybdenum heating element 8 is fixed to both sides of the furnace by fixing hooks. The upper part of the molybdenum heating element 8 is fixed and the lower part is a free end. This structure has the characteristics of easy disassembly and assembly and smooth thermal expansion; the electrode is led out from the side of the furnace and is provided with a multi-layer sealing structure. The molybdenum heating element 8 of the utility model is made of a new molybdenum-lanthanum alloy material prepared by adding rare earth oxide (La2O3) to a molybdenum matrix.

[0053] A specific implementation of the cooling mechanism 5: Fig.14 The cooling mechanism 5 includes: a cooling chamber 51, a top cooling jacket 52, a side cooling jacket 53 and a bottom cooling jacket 54. The top cooling jacket 52 and the bottom cooling jacket 54 are respectively arranged above and below the cooling chamber 51, and the two side cooling jackets 53 are respectively arranged on both sides of the cooling chamber 51. A sealing shell is provided on the outside of the cooling chamber 51. This structural design can effectively prevent water leakage in the furnace.

[0054] As another embodiment of the utility model: a heat-conducting mud is provided on the outside of the sealing shell, and the sealing shell is a steel plate shell fixed on the outside of the cooling cavity 51. The heat-conducting mud is filled between each cooling jacket and the steel plate shell, which can effectively improve the cooling effect.

[0055] A specific implementation of the buckle structure 413: Fig.13A clamping block 4131 is provided at the bottom of the track brick 411 , and a clamping groove 4132 matching with the clamping block 4131 is provided at the upper end of the support brick 412 . The two clamping blocks 4131 are respectively provided at the front and rear ends of the track brick 411 .

[0056] As another embodiment of the present invention: Fig. 9 and attached Fig.12 The support bricks 412 are embedded between the corundum bricks 414, and the track bricks 411 are provided with guide slopes 4112, which extend downward from the track surface 4111 of the track bricks 411. The support bricks 412 are vertically laid and inserted into the flat corundum bricks 414. The track bricks 411 are provided with guide slopes 4112, which extend downward from the track surface 4111 of the track bricks 411. This arrangement can effectively prevent the arching phenomenon caused by the uneven track surface 4111 due to inconsistent thermal expansion.

[0057] As another embodiment of the present invention: the track brick 411 is formed with baffles 4113 on both sides of the track surface 4111, and the two sides of the guide slope 4112 are respectively provided with guide slopes 4114 connected to the baffles 4113, and the distance between the two guide slopes 4114 near one end of the baffle 4113 is smaller than the distance between the other ends. This arrangement can effectively prevent the track brick 411 from getting stuck when a small deviation occurs.

[0058] Specifically, the track bricks 411, the side wall bricks 431, and the refractory bricks 421 are all made of high-purity alumina, which greatly improves the rated operating temperature of the furnace and meets the process requirements for sintering nuclear fuel pellets. The parameters are as follows: (1) maximum operating temperature 1800°C, (2) W (Al2O3) > 99.3%, (3) volume density ≥ 3.2g / cm3, (4) compressive strength ≥ 100MPa, (5) room temperature flexural strength ≥ 20Mpa.

[0059] The utility model of the continuous high-temperature sintering furnace for nuclear fuel pellets can maintain a common temperature of 1750°C and a maximum furnace temperature of 1800°C. It is mainly completed through the three aspects of furnace body 4 design, sealing design and heating design. Specifically, in the design of the furnace body 4, the furnace bottom 41, the furnace wall 43 and the furnace top 42 of the furnace chamber adopt dry masonry and mortise and tenon structures, the track bricks 411 and the support bricks 412 of the furnace bottom 41 are fixed by a snap structure 413, and the side wall bricks 431 of the furnace wall 43 are fixed by snap connection, which avoids the high-temperature refractory clay ablation phenomenon of the traditional furnace body 4 and improves the stability of the furnace structure. Then, the outer side of the furnace body 4 is sealed by a sealing layer, so that a more stable and higher furnace temperature can be obtained. In terms of heating, preheating treatment is provided, and heating is performed in the low temperature zone 100 and the high temperature zone 200 by combining the muffle 7 and the molybdenum heating element 8, so as to obtain a sufficient furnace temperature. At the same time, the muffle 7 cooperates with the air inlet pipe 9 to minimize the amount of water vapor in the muffle 7 from running outside the muffle 7 to corrode the molybdenum heating element 8, thereby extending the service life of the molybdenum heating element 8. In terms of sealing, a double sealing door structure of the furnace door 010 and the isolation door 011 is adopted, and during the feeding and discharging process, it is ensured that there is always a sealing door closed, and then the vacuum system 012 and the nitrogen supply mechanism 013 are cooperated to reduce the risk of hydrogen leakage or air entering the furnace, and at the same time, the furnace pressure can be maintained stable, so as to obtain a stable furnace temperature.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the utility model.

Claims

1. A continuous high temperature sintering furnace for nuclear fuel pellets, It is characterized in that The invention comprises a first boat pushing mechanism, a feeding chamber, a hydrogen combustion port, a furnace body, a cooling mechanism, a discharging chamber and a first boat pushing mechanism which are arranged in sequence. The furnace body is divided into a low temperature zone, a high temperature zone and a slow cooling zone. The high temperature zone is located between the low temperature zone and the slow cooling zone. A muffle is arranged in both the low temperature zone and the high temperature zone. A molybdenum heating element is arranged outside the muffle in the furnace body. An air inlet pipe for conveying dry hydrogen is arranged on the furnace body so as to make the air pressure outside the muffle greater than the air pressure inside the muffle.

2. The continuous high temperature sintering furnace for nuclear fuel pellets according to claim 1, It is characterized in that The feed chamber and the discharge chamber are both provided with furnace doors and isolation doors, and are also provided with vacuum extraction systems and nitrogen supply mechanisms. When the furnace doors and isolation doors are closed, the feed chamber and the discharge chamber are filled with nitrogen through the nitrogen supply mechanism.

3. The continuous high temperature sintering furnace for nuclear fuel pellets according to claim 2, It is characterized in that The furnace door and the isolation door are both connected with a sealing device, which includes: a bracket, a guide wedge, a guide wheel, a guide rail, a sealing ring, a hydraulic cylinder and a lifting rod. The sealing ring is respectively arranged between the furnace door and the door frame and between the isolation door and the door frame. The guide wheel fixed on the bracket rolls up and down along the guide rail. The guide wedge is respectively fixed on the furnace door and the isolation door. The hydraulic cylinder is fixedly connected to the bracket. One end of the lifting rod is fixed on the bracket, and the other end slides in the guide groove of the guide wedge to drive the furnace door to compress the sealing ring or the isolation door to compress the sealing ring.

4. The continuous high-temperature sintering furnace for nuclear fuel pellets according to claim 3, It is characterized in that The sealing device comprises two travel switches, one of which is used to detect the position of the piston rod of the hydraulic cylinder, and the other travel switch is used to detect the positions of the furnace door and the isolation door.

5. The continuous high-temperature sintering furnace for nuclear fuel pellets according to claim 1, It is characterized in that A sealing layer is provided on the outer side of the furnace body, and the furnace chamber of the furnace body includes a furnace bottom, a furnace top and a furnace wall. Track bricks and support bricks are provided on the furnace bottom, and the track bricks are laid flat on the support bricks. A gap is reserved between two adjacent track bricks, and a snap-on structure is provided between the track bricks and the support bricks. Side wall bricks are provided on the inner side of the furnace wall, and the side wall bricks are stacked from bottom to top, and the protrusion of the lower side wall brick is inserted into the limiting groove of the upper side wall brick. A V-shaped groove is provided on the upper end of the furnace wall, and refractory bricks, hollow ball bricks and insulation bricks are provided in sequence in the V-shaped groove from bottom to top.

6. The continuous high-temperature sintering furnace for nuclear fuel pellets according to claim 1, It is characterized in that A dry hydrogen curtain generating device is provided at one end of the low temperature zone away from the high temperature zone and at one end of the slow cooling zone away from the high temperature zone.

7. The continuous high-temperature sintering furnace for nuclear fuel pellets according to claim 6, It is characterized in that A waste discharge pipe is arranged between the low temperature zone and the high temperature zone, and a hydrogen combustion device is arranged at the top of the waste discharge pipe.

8. The continuous high-temperature sintering furnace for nuclear fuel pellets according to claim 4, It is characterized in that The feeding chamber and the discharging chamber are also provided with a vacuum gauge and a pressure sensor.

9. The continuous high-temperature sintering furnace for nuclear fuel pellets according to claim 7, It is characterized in that The molybdenum heating element includes a plurality of vertically arranged straight segments, and the straight segments are connected by curved segments.

10. The continuous high-temperature sintering furnace for nuclear fuel pellets according to claim 1, It is characterized in that The cooling mechanism comprises: a cooling chamber, a top cooling jacket, a side cooling jacket and a bottom cooling jacket, wherein the top cooling jacket and the bottom cooling jacket are respectively arranged above and below the cooling chamber, the two side cooling jackets are respectively arranged on both sides of the cooling chamber, and a sealing shell is provided on the outside of the cooling chamber.

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