A nitrogen sealing circulation system for rotary kiln

Abstract

The invention belongs to the technical field of rotary kilns, and particularly relates to a nitrogen sealing circulation system for a rotary kiln, comprising a rotary kiln cylinder and a kiln head supporting pipe, wherein a sealing structure is arranged between the rotary kiln cylinder and the kiln head supporting pipe, wherein nitrogen is injected into the sealing structure through a sealed nitrogen injection pipe fixed in the sealing structure, and then injected into the rotary kiln cylinder through a furnace nitrogen injection pipe penetrating and fixed in the sealing structure, and then the nitrogen in the sealing structure flows back into the furnace nitrogen injection pipe through a nitrogen reflux pipe, and while the nitrogen is continuously injected and the normal sealing pressure in the sealing structure is maintained, a part of the nitrogen is guided to the furnace pipe nitrogen injection pipe through a pre-nitrogen reflux pipe, that is, the nitrogen after absorbing heat and heating is reused, thereby reducing the loss of nitrogen while ensuring the sealing pressure, and effectively reducing the production cost of the rotary kiln.

Description

Technical Field

[0001] The invention belongs to the technical field of rotary kilns, and in particular relates to a nitrogen sealing circulation system for a rotary kiln. Background Art

[0002] The nitrogen sealing method used in the general high-temperature rotary kiln sealing system on the market does not include a nitrogen recovery system. The common practice of the current nitrogen sealing system is to continuously inject nitrogen into the sealing structure to ensure that a stable pressure range is maintained in the sealing structure, but this method will cause a large amount of nitrogen used for sealing to escape into the external atmosphere. Usually, in order to ensure the stability of the atmosphere in the furnace and isolate the external atmosphere, the amount of nitrogen injected is usually further increased in actual use, but this practice will also cause the problem of excessive nitrogen loss, thereby increasing production costs. Summary of the invention

[0003] The object of the present invention is to provide a nitrogen sealing circulation system for a rotary kiln to solve the problems in the prior art. The specific technical scheme is as follows:

[0004] A nitrogen sealing circulation system for a rotary kiln comprises a rotary kiln cylinder and a kiln head supporting pipe, wherein a sealing structure is arranged between the rotary kiln cylinder and the kiln head supporting pipe, wherein nitrogen is injected into the sealing structure through a sealed nitrogen injection pipe fixed in the sealing structure, and then nitrogen is injected into the rotary kiln cylinder through a furnace nitrogen injection pipe penetrating and fixed in the sealing structure, and then nitrogen in the sealing structure is guided to the furnace nitrogen injection pipe through a nitrogen reflux pipe.

[0005] Furthermore, the sealing structure comprises a cylinder flange, which is fixed to the end of the rotary kiln cylinder, and the cylinder flange is rotatably connected to a graphite packing fixed to the sealing tube.

[0006] Furthermore, a first sealing ring is fixed in the middle of the cylinder flange, and two second sealing rings are fixed in parallel at the edge of the cylinder flange. The first sealing ring and the second sealing ring are both rotatably connected to the sealing tube. The cylinder flange, the sealing tube and the first sealing ring enclose a first nitrogen sealing space, and the cylinder flange, the sealing tube and the second sealing ring enclose a second nitrogen sealing space.

[0007] Furthermore, a kiln head support tube is fixed in the sealed tube, a nitrogen guide space is provided between the sealed tube and the kiln head support tube, a sealed nitrogen injection tube is fixed on the sealed tube, nitrogen is injected into the nitrogen guide space through the sealed nitrogen injection tube, the nitrogen injection tube in the furnace is passed through and fixed on the sealed tube, the nitrogen injection tube in the furnace is connected with one end of the nitrogen reflux tube through the connecting tube 2, and the first nitrogen sealed space and the second nitrogen sealed space are connected with the other end of the nitrogen reflux tube through the two connecting tubes 1 respectively.

[0008] Furthermore, two nitrogen guide holes are provided in the sealing tube, the first nitrogen sealing space and the second nitrogen sealing space are connected to the nitrogen guide space through the two nitrogen guide holes respectively, a guide plate 1 and a guide plate 2 are fixed in the sealing tube, and a pressure check valve is provided in the nitrogen reflux pipe.

[0009] Further, the pressure check valve includes a piston 1, which slides in the nitrogen reflux pipe and is provided with a plurality of vent holes 1. The piston 1 is fixedly connected to one end of a spring 1, and the other end of the spring 1 is fixed to an adjusting plug. The adjusting plug slides in the nitrogen reflux pipe and is provided with a plurality of vent holes 2. The adjusting plug is rotatably connected to a rotating rod, which is slidably connected to a sealing member, which is fixed in the nitrogen reflux pipe. The rotating rod is threadedly connected to the end of the nitrogen reflux pipe, the end of the rotating rod is fixedly connected to a hexagonal nut, which is fixedly connected to an outer sliding tube, which is slidably connected to the end of the nitrogen reflux pipe, and a scale line is provided on the surface of the end of the nitrogen reflux pipe.

[0010] Furthermore, the nitrogen reflux pipe is fixedly connected to the connecting pipe three, an oxygen content detector is provided in the nitrogen reflux pipe, an electromagnetic valve one is provided in the connecting pipe two, an electromagnetic valve two is provided in the connecting pipe three, a guide plate three is provided at the connection between the nitrogen injection pipe in the furnace and the connecting pipe two, and an oxygen content reducing device is fixed at the end of the connecting pipe three.

[0011] Furthermore, a pressure plate is provided between the rotary kiln cylinder and the first nitrogen sealed space, and the pressure plate fixes the heat insulation plate on the cylinder flange.

[0012] Furthermore, the oxygen content reduction device includes a box body, which is fixedly connected to the connecting pipe three through the connecting pipe four, a metal mesh is inserted in the box body, a heater is arranged in the box body, the lower end of the metal mesh is in contact with the heater, a slide is slidably connected in the box body, and a cylinder is fixed at the end of the box body.

[0013] Furthermore, the slide is fixedly connected to one end of telescopic hose one, the other end of telescopic hose one is fixedly connected to the gas delivery mechanism, the gas delivery mechanism is fixedly connected to one end of telescopic hose two, the other end of telescopic hose two is fixedly connected to guide plate four, and a guide plate four is provided at the connection between connecting pipe four and telescopic hose two.

[0014] Furthermore, the slide is fixedly connected to one end of telescopic hose one, the other end of telescopic hose one is installed on the air inlet end of the gas circulation pump, the air outlet end of the gas circulation pump is fixedly installed to one end of telescopic hose two, the other end of telescopic hose two is fixedly connected to guide plate four, and a guide plate four is provided at the connection between connecting pipe four and telescopic hose two.

[0015] The advantages of the present invention are:

[0016] 1. While nitrogen is continuously injected and the normal sealing pressure in the sealing structure is maintained, a part of the nitrogen is led into the nitrogen injection pipe in the furnace through the nitrogen reflux pipe, that is, the nitrogen after absorbing heat and heating is reused. While ensuring the sealing pressure, the loss of nitrogen is reduced, which can effectively reduce the production cost of the rotary kiln.

[0017] 2. After the external normal temperature or low temperature nitrogen is injected into the sealed structure, the nitrogen can absorb the heat in the sealed structure to preheat itself. The preheated nitrogen enters the furnace through the nitrogen reflux pipe and the nitrogen is injected into the pipe, and then injected into the rotary kiln cylinder. The preheated nitrogen in the sealed structure can reduce the impact on the atmosphere temperature environment in the rotary kiln cylinder, which is conducive to the stable reaction in the furnace.

[0018] 3. After the preheated nitrogen in the sealed structure is injected into the rotary kiln cylinder, the amount of preheated nitrogen directly injected into the rotary kiln cylinder through the nitrogen injection pipe in the furnace can be reduced, saving the cost of preheating nitrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The sealing structure of the present invention is shown in FIG. Figure 1 ;

[0020] Figure 2 The sealing structure of the present invention is shown in FIG. Figure 2 ;

[0021] Figure 3 The sealing structure of the present invention is shown in FIG. Figure 3 ;

[0022] Figure 4 The sealing structure of the present invention is shown in FIG. Figure 4 ;

[0023] Figure 5 The sealing structure of the present invention is shown in FIG. Figure 5 ;

[0024] Figure 6 The sealing structure of the present invention is shown in FIG. Figure 6 ;

[0025] Figure 7 The sealing structure of the present invention is shown in FIG. Figure 7 ;

[0026] Figure 8 The structure of the pressure check valve of the present invention is shown in FIG. Figure 1 ;

[0027] Fig. 9 for Figure 8 A partial enlarged view of the middle part;

[0028] Fig.10 The structure of the pressure check valve of the present invention is shown in FIG. Figure 2 ;

[0029] Fig.11 for Fig.10 A partial enlarged view of point B in the middle;

[0030] Fig.12 The structure of the oxygen content reduction device of the present invention is shown in FIG. Figure 1 ;

[0031] Fig.13 The structure of the oxygen content reduction device of the present invention is shown in FIG. Figure 2 ;

[0032] Fig.14 The structure of the oxygen content reduction device of the present invention is shown in FIG. Figure 3 ;

[0033] Fig.15 The structure of the oxygen content reduction device of the present invention is shown in FIG. Figure 4 ;

[0034] Fig.16 The structure of the oxygen content reduction device of the present invention is shown in FIG. Figure 5 ;

[0035] Description of the markings in the figure:

[0036] 1. Rotary kiln cylinder; 2. Cylinder flange; 3. Insulation board; 4. Press plate; 5. Graphite packing; 6. Sealing tube; 7. Kiln head support tube; 8. First sealing ring; 9. Second sealing ring; 10. First nitrogen sealing space; 11. Second nitrogen sealing space; 12. Nitrogen flow guide space; 13. Sealed nitrogen injection pipe; 14. Furnace nitrogen injection pipe; 15. Nitrogen flow guide hole; 16. Guide plate 1; 17. Guide plate 2; 18. Nitrogen reflux pipe; 19. Piston 1; 20. Vent 1; 21. Spring 1; 22. Connecting pipe 1; 23. Adjusting plug; 24. Vent 2; 25. Turn rod; 26. Seal; 27. Hexagonal nut; 28. Outer slide tube; 29. ​​Graduation mark; 30. Connecting pipe 2; 31. Connecting pipe 3; 32. Solenoid valve 1; 33. Solenoid valve 2; 34. Guide plate 3; 35. Connecting pipe 4; 36. Box; 37. Guide plate 4; 38. Metal mesh; 39. Heater; 40. Slide; 41. Cylinder; 42. Telescopic hose 1; 43. Telescopic hose 2; 44. Gas circulation pump. DETAILED DESCRIPTION

[0037] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0039] Embodiment 1

[0040] like Figure 1-16 As shown, a nitrogen sealed circulation system for a rotary kiln comprises a rotary kiln cylinder 1 and a kiln head support pipe 7, a sealing structure is arranged between the rotary kiln cylinder 1 and the kiln head support pipe 7, nitrogen is injected into the sealing structure through a sealed nitrogen injection pipe 13 fixed in the sealing structure, nitrogen is injected into the rotary kiln cylinder 1 through a furnace nitrogen injection pipe 14 penetrating and fixed in the sealing structure, and nitrogen in the sealing structure is drained into the furnace nitrogen injection pipe 14 through a nitrogen reflux pipe 18;

[0041] The working principle of the above technical solution is as follows: nitrogen gas at normal or low temperature outside is injected into the sealing structure to separate the outside atmosphere from the atmosphere inside the rotary kiln cylinder 1, thereby achieving a further sealing effect; preheated nitrogen gas is injected into the rotary kiln cylinder 1 through the furnace nitrogen injection pipe 14 that penetrates and is fixed in the sealing structure; nitrogen gas is an inert gas and can be used as a protective gas to stabilize the reaction inside the rotary kiln cylinder 1; the nitrogen gas injected into the rotary kiln cylinder 1 needs to be preheated to prevent temperature fluctuations inside the rotary kiln cylinder 1, which is beneficial to the stable reaction inside the rotary kiln cylinder 1;

[0042] One end of the nitrogen reflux pipe 18 is connected to the sealing structure, and the other end is connected to the nitrogen injection pipe 14 in the furnace. As the ambient temperature or low temperature nitrogen is continuously injected into the sealing structure, the sealing pressure in the sealing structure exceeds the preset value, and a part of the nitrogen in the sealing structure will flow back into the nitrogen injection pipe 14 in the furnace through the nitrogen reflux pipe 18, and then be injected into the rotary kiln cylinder 1 through the nitrogen injection pipe 14 in the furnace;

[0043] The kiln head support pipe 7 is fixedly connected to the kiln head, and the kiln head feeds materials into the rotary kiln cylinder 1 through the kiln head support pipe 7;

[0044] The beneficial effects of the above technical solution are as follows: the nitrogen in the sealing structure flows back into the furnace through the nitrogen reflux pipe 18, and after the nitrogen is injected into the pipe 14, the nitrogen pressure in the sealing structure can be maintained at a certain value, thereby preventing continuous injection of nitrogen into the sealing structure, which causes the nitrogen pressure in the sealing structure to increase, squeezes the sealing structure to produce gaps, causes nitrogen to overflow, causes nitrogen loss, and shortens the service life of the sealing structure;

[0045] After the ambient temperature or low temperature nitrogen is injected into the sealed structure, the nitrogen can absorb the heat in the sealed structure to preheat itself. The preheated nitrogen enters the nitrogen injection pipe 14 in the furnace through the nitrogen reflux pipe 18, and then is injected into the rotary kiln cylinder 1. The preheated nitrogen in the sealed structure can reduce the impact on the atmosphere temperature environment in the rotary kiln cylinder 1, which is conducive to the stable reaction in the furnace.

[0046] After the preheated nitrogen in the sealing structure is injected into the rotary kiln cylinder 1, the amount of preheated nitrogen directly injected into the rotary kiln cylinder 1 through the nitrogen injection pipe 14 in the furnace can be reduced, saving the cost of preheating nitrogen;

[0047] When nitrogen at room temperature or low temperature is injected into the sealing structure, it will absorb the heat inside the sealing structure, so that the sealing structure originally designed according to the highest tolerable temperature can avoid working for a long time at the extreme temperature, thereby extending the service life of the sealing structure.

[0048] Embodiment 2

[0049] like Figure 1-16 As shown, the sealing structure includes a cylinder flange 2, which is fixed to the end of the rotary kiln cylinder 1, and the cylinder flange 2 is rotatably connected to a graphite packing 5 fixed to a sealing tube 6;

[0050] A first sealing ring 8 is fixed in the middle of the cylinder flange 2, and two second sealing rings 9 are fixed in parallel at the edge of the cylinder flange 2. The first sealing ring 8 and the second sealing ring 9 are both rotatably connected to the sealing tube 6. The cylinder flange 2, the sealing tube 6 and the first sealing ring 8 enclose a first nitrogen sealing space 10, and the cylinder flange 2, the sealing tube 6 and the second sealing ring 9 enclose a second nitrogen sealing space 11;

[0051] A kiln head support tube 7 is fixed in the sealing tube 6, a nitrogen guide space 12 is provided between the sealing tube 6 and the kiln head support tube 7, a sealed nitrogen injection tube 13 is fixed on the sealing tube 6, nitrogen is injected into the nitrogen guide space 12 through the sealed nitrogen injection tube 13, a furnace nitrogen injection tube 14 is passed through and fixed on the sealing tube 6, the furnace nitrogen injection tube 14 is connected to one end of the nitrogen reflux tube 18 through the connecting tube 2 30, and the first nitrogen sealed space 10 and the second nitrogen sealed space 11 are respectively connected to the other end of the nitrogen reflux tube 18 through two connecting tubes 1 22;

[0052] The sealing tube 6 is provided with two nitrogen guide holes 15, the first nitrogen sealing space 10 and the second nitrogen sealing space 11 are respectively connected to the nitrogen guide space 12 through the two nitrogen guide holes 15, a guide plate 16 and a guide plate 2 17 are fixed in the sealing tube 6, and a pressure check valve is provided in the nitrogen reflux pipe 18;

[0053] The working principle of the above technical solution is as follows: the ambient temperature or low temperature nitrogen is injected into the nitrogen guide space 12 through the sealed nitrogen injection pipe 13, the outlet of the sealed nitrogen injection pipe 13 is located at the upper position in the nitrogen guide space 12, the nitrogen moves downward through the guide plate 16 and the guide plate 2 17, the function of the guide plate 16 and the guide plate 2 17 is to increase the stroke of the nitrogen flow, so that the nitrogen can exchange heat with the sealing structure for as long as possible, the nitrogen enters the first nitrogen sealed space 10 and the second nitrogen sealed space 11 through the nitrogen guide hole 15, but in the first nitrogen sealed space The nitrogen gas flows upward in the space 10 and the second nitrogen sealed space 11, and enters the nitrogen reflux pipe 18 through the connecting pipe 22. The nitrogen reflux pipe 18 is provided with a pressure check valve to ensure that the nitrogen in the sealed structure continues to increase and has a certain sealing pressure. When the sealing pressure exceeds the preset value, the nitrogen pushes open the pressure check valve and flows into the nitrogen injection pipe 14 in the furnace. At this time, after the nitrogen flows in the sealed structure for one week, it absorbs the heat in the sealed structure and achieves the purpose of preheating. This part of the nitrogen enters the rotary kiln cylinder 1 together with the nitrogen directly injected into the nitrogen injection pipe 14 in the furnace.

[0054] Embodiment 3

[0055] like Figure 1-16 As shown, the pressure check valve includes a piston 19, the piston 19 slides in the nitrogen reflux pipe 18, the piston 19 is provided with a plurality of vent holes 20, the piston 19 is fixedly connected to one end of a spring 21, the other end of the spring 21 is fixed to a regulating plug 23, the regulating plug 23 slides in the nitrogen reflux pipe 18, the regulating plug 23 is provided with a plurality of vent holes 24, the regulating plug 23 is rotatably connected to a rotating rod 25, the rotating rod 25 is slidably connected to a sealing member 26, the sealing member 26 is fixed in the nitrogen reflux pipe 18, the rotating rod 25 is threadedly connected to the end of the nitrogen reflux pipe 18, the end of the rotating rod 25 is fixedly connected to a hexagonal nut 27, the hexagonal nut 27 is fixedly connected to an outer sliding pipe 28, the outer sliding pipe 28 is slidably connected to the end of the nitrogen reflux pipe 18, and a scale line 29 is provided on the surface of the end of the nitrogen reflux pipe 18;

[0056] The nitrogen reflux pipe 18 is fixedly connected to the connecting pipe 3 31, an oxygen content detector is arranged in the nitrogen reflux pipe 18, a solenoid valve 1 32 is arranged in the connecting pipe 2 30, a solenoid valve 2 33 is arranged in the connecting pipe 3 31, a guide plate 3 34 is arranged at the connection between the nitrogen injection pipe 14 in the furnace and the connecting pipe 2 30, and an oxygen content reducing device is fixed at the end of the connecting pipe 3 31;

[0057] The working principle of the above technical solution is as follows: when the nitrogen sealing pressure in the sealing structure exceeds the preset value, the nitrogen will push open the piston 19, driving the spring 21 to be compressed, and the nitrogen in the nitrogen reflux pipe 18 passes through the vent hole 20, and then passes through the vent hole 24 on the regulating plug 23, and enters the nitrogen injection pipe 14 in the furnace through the connecting pipe 2 30. When the nitrogen sealing pressure in the sealing structure is lower than the preset value, it cannot overcome the tension of the spring 21. Under the action of the tension of the spring 21, the piston 19 is driven to return to the initial position, so that the nitrogen cannot pass through until the nitrogen sealing pressure exceeds the preset value next time and then opens again;

[0058] The connecting pipe 2 30 and the connecting pipe 3 31 connected to the nitrogen reflux pipe 18 are respectively provided with an electromagnetic valve 1 32 and an electromagnetic valve 2 33. In the initial state, the electromagnetic valve 1 32 is in an open state, and the electromagnetic valve 2 33 is in a closed state. The oxygen content detection instrument is installed in the nitrogen reflux pipe 18 section in the sealing structure. When the oxygen content detection instrument detects that the oxygen content of the nitrogen in the sealing structure is higher than the preset value, the electromagnetic valve 1 32 is controlled to be closed and the electromagnetic valve 2 33 is opened. At this time, after the nitrogen pressure with an oxygen content higher than the preset value in the sealing structure is higher than the preset value, the nitrogen with an oxygen content higher than the preset value will enter the oxygen content reducing device through the connecting pipe 3 31 until the oxygen content detection instrument detects that the oxygen content of the nitrogen in the sealing structure is restored to a preset range, the electromagnetic valve 1 32 is opened, the electromagnetic valve 2 33 is closed, and the initial state is restored, thereby ensuring the stability of the oxygen content in the nitrogen and ensuring the reaction stability after the nitrogen is injected into the rotary kiln cylinder 1;

[0059] The hexagonal nut 27 is turned to drive the rotating rod 25 to rotate, and the rotating rod 25 is threadedly connected with the end of the nitrogen reflux pipe 18. The rotating rod 25 slides with the sealing member 26. The rotating rod 25 and the regulating plug 23 rotate and push the regulating plug 23 forward, driving the regulating plug 23 and the nitrogen reflux pipe 18 to slide, driving the regulating plug 23 and the piston 19 to slide, driving the spring 121 to be compressed, shortening the distance between the end of the regulating plug 23 and the piston 19. Under the tension of the spring 121, the pressure of the sealing structure to push the piston 19 is increased, thereby increasing the preset sealing nitrogen pressure in the sealing structure. The hexagonal nut 27 moves, The outer sliding pipe 28 slides on the outside of the nitrogen reflux pipe 18, and the edge of the outer sliding pipe 28 can correspond to the scale on the scale line 29. The scale line is positively related to the preset nitrogen pressure. The size of the preset sealed nitrogen pressure can be roughly inferred by the scale on the corresponding scale line 29. The preset sealed nitrogen pressure can be increased or decreased according to different usage scenarios and factors such as the quality and temperature of nitrogen. For example, the combustion in the rotary kiln cylinder 1 is not intense, and the heat conducted to the sealing structure is not much. The sealed nitrogen pressure value can be appropriately increased to make the nitrogen density in the nitrogen sealing structure higher and the residence time longer. After sufficient heat exchange, it passes through the pressure check valve;

[0060] The function of the guide plate 34 is to prevent the nitrogen injected through the nitrogen injection pipe 14 in the furnace from entering the nitrogen reflux pipe 18, while ensuring that the nitrogen refluxed to the nitrogen injection pipe 14 in the furnace through the nitrogen reflux pipe 18 flows into the rotary kiln cylinder 1.

[0061] Embodiment 4

[0062] like Figure 1-16 As shown, a pressing plate 4 is provided between the rotary kiln cylinder 1 and the first nitrogen sealed space 10, and the pressing plate 4 fixes the heat insulation plate 3 on the cylinder flange 2;

[0063] The working principle of the above technical solution is as follows: the heat insulation board 3 can reduce the heat overflow in the rotary kiln cylinder 1, thereby ensuring the temperature stability of the rotary kiln cylinder 1.

[0064] Embodiment 5

[0065] like Figure 1-16 As shown, the oxygen content reduction device includes a box 36, which is fixedly connected to the connecting pipe 31 through a connecting pipe 4 35, a metal mesh 38 is inserted into the box 36, a heater 39 is arranged in the box 36, and the lower end of the metal mesh 38 is in contact with the heater 39, a slide 40 is slidably connected in the box 36, and a cylinder 41 is fixed to the end of the box 36;

[0066] The slide 40 is fixedly connected to one end of a telescopic hose 42, the other end of the telescopic hose 42 is installed at the air inlet end of a gas circulation pump 44, the air outlet end of the gas circulation pump 44 is fixedly installed to one end of a telescopic hose 43, the other end of the telescopic hose 43 is fixedly connected to a guide plate 437, and a guide plate 437 is provided at the connection between the connecting pipe 435 and the telescopic hose 43;

[0067] The working principle of the above technical solution is as follows: the heater 39 is started to heat the metal mesh 38, and the nitrogen with an oxygen content higher than the preset value enters the box 36 through the connecting pipe three 31 and the connecting pipe four 35. When the nitrogen reaches the metal mesh 38, the oxygen in the nitrogen reacts with the heated metal mesh 38 and remains in the metal mesh 38. The nitrogen with reduced oxygen content passes through the metal mesh 38, pushing the slide 40 to move backward in the box 36. An oxygen content detection instrument is installed on the slide 40. The detection end of the oxygen content detection instrument penetrates the slide 40 to detect the oxygen content of the nitrogen in the enclosed area of ​​the box 36, the slide 40 and the metal mesh 38. A solenoid valve is provided at the connection between the slide 40 and the telescopic hose 1 42. In the initial state, the solenoid valve is closed. When the oxygen content detection instrument detects that the oxygen content of the nitrogen in the enclosed area of ​​the box 36, the slide 40 and the metal mesh 38 is still higher than the preset value, the solenoid valve is controlled to open, and the gas circulation pump 44 is started to drive the box 36, the slide 40 and The nitrogen in the area enclosed by the metal mesh 38 enters the telescopic hose 1 42, passes through the gas circulation pump 44, and flows back into the box 36 from the telescopic hose 2 43, and passes through the metal mesh 38 again for deoxygenation. The gas circulates continuously and passes through the metal mesh 38 for deoxygenation until the oxygen content in the nitrogen detected by the oxygen content detection instrument is reduced to below the preset value. At this time, the gas circulation pump 44 is stopped, the solenoid valve is closed, the solenoid valve 1 32 and the solenoid valve 2 33 are opened, the cylinder 41 is started, and the slide 40 is pushed forward, and the nitrogen in the area enclosed by the box 36, the slide 40 and the metal mesh 38 is returned into the nitrogen injection pipe 14 in the furnace through the connecting pipe 4 35, the connecting pipe 31 and the connecting pipe 2 30. The metal mesh 38 can be pulled out for cleaning or replacement. The oxygen content reducing device can collect nitrogen when the oxygen content in the nitrogen is high, and reduce the oxygen content in the nitrogen, and return the nitrogen that meets the requirements into the nitrogen injection pipe 14 in the furnace, thereby reducing the loss of nitrogen and saving energy.

[0068] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A nitrogen sealed circulation system for a rotary kiln, characterized in that: The rotary kiln comprises a rotary kiln body (1) and a kiln head support pipe (7), wherein a sealing structure is provided between the rotary kiln body (1) and the kiln head support pipe (7), wherein nitrogen is injected into the sealing structure through a sealed nitrogen injection pipe (13) fixed in the sealing structure, and nitrogen is injected into the rotary kiln body (1) through a furnace nitrogen injection pipe (14) penetrating and fixed in the sealing structure, and the nitrogen in the sealing structure is guided into the furnace nitrogen injection pipe (14) through a nitrogen reflux pipe (18); The sealing structure comprises a cylinder flange (2), the cylinder flange (2) is fixed to the end of the rotary kiln cylinder (1), and the cylinder flange (2) is rotatably connected to a graphite packing (5) fixed to a sealing tube (6); A first sealing ring (8) is fixed in the middle of the cylinder flange (2), two second sealing rings (9) are fixed in parallel at the edge of the cylinder flange (2), the first sealing ring (8) and the second sealing ring (9) are both rotatably connected to the sealing tube (6), the cylinder flange (2), the sealing tube (6) and the first sealing ring (8) enclose a first nitrogen sealing space (10), and the cylinder flange (2), the sealing tube (6) and the second sealing ring (9) enclose a second nitrogen sealing space (11); A kiln head support pipe (7) is fixed in the sealing pipe (6), a nitrogen guide space (12) is provided between the sealing pipe (6) and the kiln head support pipe (7), a sealed nitrogen injection pipe (13) is fixed on the sealing pipe (6), nitrogen is injected into the nitrogen guide space (12) through the sealed nitrogen injection pipe (13), a furnace nitrogen injection pipe (14) is fixed on the sealing pipe (6), the furnace nitrogen injection pipe (14) is connected to one end of the nitrogen return pipe (18) through the second connecting pipe (30), and the first nitrogen sealed space (10) and the second nitrogen sealed space (11) are respectively connected to the other end of the nitrogen return pipe (18) through two first connecting pipes (22); The sealing tube (6) is provided with two nitrogen flow guide holes (15), the first nitrogen sealing space (10) and the second nitrogen sealing space (11) are respectively connected to the nitrogen flow guide space (12) through the two nitrogen flow guide holes (15), a guide plate 1 (16) and a guide plate 2 (17) are fixed in the sealing tube (6), and a pressure check valve is provided in the nitrogen return pipe (18); The pressure check valve comprises a piston (19), the piston (19) slides in a nitrogen return pipe (18), a plurality of vent holes (20) are provided on the piston (19), the piston (19) is fixedly connected to one end of a spring (21), the other end of the spring (21) is fixed to a regulating plug (23), the regulating plug (23) slides in the nitrogen return pipe (18), a plurality of vent holes (24) are provided on the regulating plug (23), and the regulating plug (23) is connected to a rotating rod (25). ) is rotatably connected, the rotating rod (25) is slidably connected to the sealing member (26), the sealing member (26) is fixed in the nitrogen reflux pipe (18), the rotating rod (25) is threadedly connected to the end of the nitrogen reflux pipe (18), the end of the rotating rod (25) is fixedly connected to the hexagonal nut (27), the hexagonal nut (27) is fixedly connected to the outer sliding pipe (28), the outer sliding pipe (28) is slidably connected to the end of the nitrogen reflux pipe (18), and a scale mark (29) is provided on the surface of the end of the nitrogen reflux pipe (18); The nitrogen return pipe (18) is fixedly connected to the connecting pipe three (31), an oxygen content detector is arranged in the nitrogen return pipe (18), a solenoid valve one (32) is arranged in the connecting pipe two (30), a solenoid valve two (33) is arranged in the connecting pipe three (31), a guide plate three (34) is arranged at the connection between the nitrogen injection pipe (14) in the furnace and the connecting pipe two (30), and an oxygen content reducing device is fixed at the end of the connecting pipe three (31); The oxygen content reducing device comprises a box (36), the box (36) is fixedly connected to the connecting pipe (31) through the connecting pipe (35), a metal mesh (38) is inserted into the box (36), a heater (39) is arranged in the box (36), the lower end of the metal mesh (38) is in contact with the heater (39), a slide (40) is slidably connected in the box (36), and a cylinder (41) is fixed to the end of the box (36); The slide (40) is fixedly connected to one end of the telescopic hose (42), the other end of the telescopic hose (42) is installed at the air inlet end of the gas circulation pump (44), the air outlet end of the gas circulation pump (44) is fixedly installed to one end of the telescopic hose (43), the other end of the telescopic hose (43) is fixedly connected to the guide plate (37), and the guide plate (37) is provided at the connection between the connecting pipe (35) and the telescopic hose (43).

2. A nitrogen sealed circulation system for a rotary kiln according to claim 1, characterized in that: A pressing plate (4) is provided between the rotary kiln cylinder (1) and the first nitrogen sealed space (10), and the pressing plate (4) fixes the heat insulation plate (3) on the cylinder flange (2).

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