Online adjustable sealing structure for feeding and discharging of lithium iron phosphate calcination furnace

Abstract

The application provides a lithium iron phosphate calcination furnace inlet and outlet on-line adjustable sealing structure, which comprises a calcination furnace body, an inlet and outlet sealing system, an oxygen content analysis component and an electric control system; the inlet and outlet sealing system is provided with three cavity packing boxes, sealing packing components, packing gland and pressing and adjusting mechanisms, a plurality of cylinder assemblies are uniformly arranged along the circumference of the packing gland, the cylinder piston rods are fixedly connected with the packing gland, and the driving packing gland is pressed to seal the packing. The oxygen content analysis component is connected with an on-line oxygen content analyzer, the analyzer, the cylinder assembly and the displacement sensing part are connected with a PLC control module, and a closed loop control of the oxygen content linkage sealing and pressing distance is constructed. The packing gland pressing stroke can be automatically adjusted according to the real-time oxygen content in the furnace, the packing wear gap can be compensated without stopping the furnace, the material oxidation is prevented, the continuous calcination production is ensured, the circumferential pressing force of the packing gland can be balanced, the packing wear is reduced, and the inlet and outlet of the calcination furnace can be adapted to different leakage working conditions.

Description

Technical Field

[0001] This invention relates to the field of sealing technology for the preparation of lithium iron phosphate precursors, a cathode material for new energy, and particularly to a sealing structure for an online adjustable feed and discharge of a lithium iron phosphate roasting furnace. Background Technology

[0002] In the preparation of lithium iron phosphate, a cathode material for new energy, the roasting furnace is the core equipment. During the roasting process, the oxygen content inside the furnace needs to be strictly controlled, and inert gas protection is required to ensure that the oxygen content is below 20 PPM. If it exceeds the standard, it will lead to defects in the crystal structure of lithium iron phosphate, degradation of the electrochemical performance of the material, and seriously affect the product qualification rate.

[0003] The existing roasting furnace uses a traditional packing gland sealing method at the inlet and outlet ends. This requires manual periodic shutdowns to measure the gland gap and circumferential uniformity. Based on the measured values, bolts are tightened to achieve packing compression and uniform compensation. This structure has the following obvious defects:

[0004] During continuous operation of the roasting furnace, ordinary packing material experiences constant friction, causing the sealing gap to gradually widen over time. Oxygen can easily enter the furnace through the gaps at the inlet and outlet ends, resulting in excessive oxygen content inside the furnace. Wear and tear on the sealing gap cannot be detected and repaired online immediately, requiring manual intervention and shutdown. This prevents continuous production for extended periods, leading to significant capacity losses. Furthermore, frequent start-ups and shutdowns of the high-temperature expansion equipment severely damage the equipment's base material, creating high and low temperature fatigue conditions and generating alternating stress that reduces equipment lifespan. Manual intervention relies heavily on experience and is prone to measurement errors. Often, multiple people are needed simultaneously for tightening, and uneven, excessively tight, or loose tightening can exacerbate packing wear, making it impossible to accurately control the furnace atmosphere. The furnace oxygen content parameters cannot be linked to the sealing status, and the tightness of the packing gland cannot be adaptively adjusted based on real-time changes in the furnace atmosphere, making it difficult to guarantee product quality stability.

[0005] In summary, the industrial roasting furnaces currently used in this field are generally small in size, and the inlet and outlet sealing structures are still bolted. This leads to problems such as uneven gaps after the packing is damaged and cannot be repaired online, outside air can easily enter the equipment and cause excessive oxygen content, high-temperature oxidation of equipment materials, deterioration of materials due to oxidation, and the need for equipment shutdown for maintenance and adjustment, resulting in continuous production.

[0006] Therefore, there is an urgent need for a sealing structure that can solve problems such as unadjustable sealing, unstable oxygen content, cumbersome operation and maintenance, limited production capacity, and increased number of vulnerable parts in the packing material without requiring shutdown for maintenance. Summary of the Invention

[0007] To address the shortcomings of the existing technologies, this invention provides an online adjustable sealing structure for the feeding and discharging of a lithium iron phosphate roasting furnace, thereby solving the technical problems of cumbersome manual tightening, inability to sense, adjust and repair online, uncontrollable oxygen content, and reduced production capacity due to downtime maintenance.

[0008] To achieve the above objectives, the present invention provides an online adjustable sealing structure for the feeding and discharging of a lithium iron phosphate roasting furnace, comprising:

[0009] The furnace body of the roasting furnace;

[0010] The system includes a sealing system for the inlet and outlet boxes mounted on the furnace body of the roasting furnace; the sealing system includes a three-cavity stuffing box, a sealing packing assembly, a packing gland, and a pressing and adjusting mechanism. Multiple sets of cylinder assemblies of the pressing and adjusting mechanism are evenly arranged along the circumference of the packing gland. The piston rod end of each cylinder assembly is rigidly fixedly connected to the packing gland. The packing gland and the sealing packing assembly abut against each other to achieve sealing and pressing. The sealing packing assembly is mounted between the three-cavity stuffing box and the sealing surface of the roasting furnace body.

[0011] An oxygen content analysis component is assembled on the furnace body of the roasting furnace. The oxygen content analysis component is connected to an online oxygen content analyzer to collect the oxygen content signal inside the furnace.

[0012] The electronic control system includes a PLC control module. The online oxygen content analyzer, the sensing component for detecting the displacement of the packing gland, and all the cylinder assemblies are electrically connected to the PLC control module via signal lines.

[0013] In some embodiments, the sealing packing assembly includes: shaped packing, packing ring and pore ring; the three-cavity stuffing box forms an annular gap with the sealing surface of the roasting furnace body, and the shaped packing, pore ring and packing ring are sequentially filled in the annular gap;

[0014] The packing gland is slidably sleeved on the outside of the three-cavity stuffing box, and the inner side of the packing gland abuts against the packing. The cylinder assembly extends and retracts to drive the packing gland to slide axially to press or release the sealing packing assembly.

[0015] In some embodiments, the sealing packing assembly uses graphite braided PTFE high-temperature resistant packing, and the sealing packing is composed of a combination of shaped packing and packing, with two pore rings fitted to the shape of the packing being assembled between the shaped packing and the packing.

[0016] In some embodiments, the three-cavity stuffing box sealing cavities at the feed end and discharge end of the roasting furnace body are all connected to inert gas replenishment pipelines; the three-cavity stuffing box is provided with two nitrogen sealing cavities and one cooling cavity, both of which are connected to nitrogen pipelines, and the nitrogen sealing cavities maintain a slightly positive pressure environment inside, while expanding the irregularly shaped packing to form a sealed air channel; the cooling cavity is connected to a cooling water pipeline, and cooling water flows inside the cooling cavity.

[0017] In some embodiments, the pore ring is a first irregular pore ring and a second irregular pore ring, and the three-cavity stuffing box is equipped with two nitrogen inlet pipelines, which are respectively connected to the two nitrogen sealing cavities of the three-cavity stuffing box. Nitrogen is evenly distributed through the first irregular pore ring and the second irregular pore ring.

[0018] In some embodiments, the sensing component is a proximity switch, which is fixedly installed on the packing gland. The PLC control module receives the displacement signals transmitted by each proximity switch and adjusts the stroke of the corresponding cylinder assembly according to the distance values ​​at different circumferential positions of the packing gland.

[0019] In some embodiments, the sealing components at the feed end and the discharge end of the roasting furnace body are independently closed-loop controlled.

[0020] In some embodiments, the sealing structure further includes: a feed box housing, a cylinder assembly mounting bracket, and a rotary bearing; the three-cavity stuffing box and the oxygen content analysis component are fixedly assembled on the feed box housing; the base of the cylinder assembly is fixedly installed on the cylinder assembly mounting bracket; and the feed box housing is assembled and connected to the furnace body sealing position of the roasting furnace through the rotary bearing.

[0021] In some embodiments, the oxygen content analysis component includes an oxygen measuring element, one end of which is connected to the interior of the roasting furnace body, and the other end is connected to the online oxygen content analyzer. The online oxygen content analyzer collects oxygen content data in the furnace in real time and transmits the signal to the PLC control module.

[0022] In some embodiments, multiple sets of cylinder assemblies are evenly arranged at equal angles along the circumference of the packing gland, and each set of cylinder assemblies is matched with an independent proximity switch.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The online adjustable sealing structure for the lithium iron phosphate roasting furnace provided by this invention can adjust the distance between the packing gland and the end face of the packing gland online according to the real-time oxygen content in the furnace. It can complete the pressure fine adjustment without stopping the machine, automatically compensate for the wear gaps caused by long-term operation of the packing, and ensure that the oxygen content in the furnace is always maintained at the normal index of 20ppm, so that the material can be produced normally and continuously. It can ensure the stability of oxygen content and furnace pressure, and meet the reaction roasting requirements for the preparation of lithium iron phosphate, a cathode material for new energy. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the online adjustable sealing structure for the lithium iron phosphate roasting furnace as shown in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram illustrating the control principle of the online adjustable sealing structure for the feeding and discharging of the lithium iron phosphate roasting furnace as shown in an embodiment of the present invention.

[0027] In the attached figures, the following labels are used:

[0028] 1-Three-cavity stuffing box; 2-Stuffing gland; 3-Cylinder assembly; 4-Online oxygen content analyzer; 5-PLC control module; 6-Irregularly shaped packing; 7-Packed packing; 8-Cooling water pipeline; 9-First irregularly shaped pore ring; 10-Second irregularly shaped pore ring; 11-Proximity switch; 12-Inlet / outlet box housing; 13-Cylinder assembly mounting bracket; 14-Slewing bearing; 15-Roasting furnace body sealing position; 16-Oxygen measuring component; 17-First nitrogen inlet pipeline; 18-Second nitrogen inlet pipeline. Detailed Implementation

[0029] See Figure 1-2 An embodiment of the present invention provides an online adjustable sealing structure for the feeding and discharging of a lithium iron phosphate roasting furnace, comprising: a roasting furnace body; and a feeding and discharging box sealing system assembled on the roasting furnace body; the feeding and discharging sealing system includes a three-cavity stuffing box 1, a sealing packing assembly, a packing gland 2, and a pressing and adjusting mechanism; multiple sets of cylinder assemblies 3 of the pressing and adjusting mechanism are evenly arranged around the packing gland 2, and the piston rod end of each cylinder assembly 3 is rigidly fixedly connected to the packing gland 2; the packing gland 2 abuts against the sealing packing assembly. The sealing and pressing are achieved by assembling the sealing packing assembly between the three-cavity stuffing box 1 and the sealing surface of the roasting furnace body; the oxygen content analysis assembly is assembled on the roasting furnace body and is externally connected to an online oxygen content analyzer 4 to collect the oxygen content signal inside the furnace; the electrical control system includes a PLC control module 5, and the online oxygen content analyzer 4, the sensing component for detecting the displacement of the packing gland, and all the cylinder assemblies 3 are electrically connected to the PLC control module 5 through signal lines.

[0030] The sealing packing assembly described in this embodiment includes: shaped packing 6, packing 7, and a pore ring; an annular gap is formed between the three-cavity stuffing box 1 and the sealing surface of the roasting furnace body, and the shaped packing 6, the pore ring, and the packing 7 are sequentially filled in the annular gap; the packing gland 2 is slidably sleeved on the outside of the three-cavity stuffing box 1, and the inner side of the packing gland 2 abuts against the packing 7; the cylinder assembly 3 extends and retracts to drive the packing gland 2 to slide axially to press or release the sealing packing assembly.

[0031] In this embodiment, the sealing packing assembly uses graphite braided PTFE high-temperature resistant packing. The packing is divided into irregularly shaped packing and square packing for sealing, and the installation sequence is irregularly shaped first and then square. Two pore rings that fit the shape of the packing are placed in the middle for introducing nitrogen as an inert gas compensation. The sealing packing is composed of irregularly shaped packing 6 and packing packing 7. Two pore rings that fit the shape of the packing are installed between the irregularly shaped packing 6 and the packing packing 7 for introducing nitrogen as an inert gas compensation. The packing fills the gap between the stuffing box and the furnace sealing surface. The packing gland slides between the stuffing box and the furnace sealing surface to compress the sealing packing.

[0032] In this embodiment, the three-cavity stuffing box sealing cavities at the feed end and discharge end of the roasting furnace body are all connected to inert gas replenishment pipelines. The three-cavity stuffing box 1 is provided with two nitrogen sealing cavities and one cooling cavity. Both nitrogen sealing cavities are connected to nitrogen pipelines. The nitrogen sealing cavities maintain a slightly positive pressure environment and simultaneously expand the irregularly shaped packing to form a sealed air channel. The cooling cavity is connected to the cooling water pipeline 8, and cooling water flows through the cooling cavity. The pore rings are a first irregularly shaped pore ring 9 and a second irregularly shaped pore ring 10. The three-cavity stuffing box 1 is equipped with two nitrogen inlet pipelines, namely a first nitrogen inlet pipeline 17 and a second nitrogen inlet pipeline 18. The two nitrogen inlet pipelines are respectively connected to the two nitrogen sealing cavities of the three-cavity stuffing box 1, and the nitrogen is evenly distributed through the first irregularly shaped pore ring 9 and the second irregularly shaped pore ring 10.

[0033] In this embodiment, the sealing cavities of the stuffing box at the inlet and outlet ends of the roasting furnace are both connected to inert gas supply pipelines. The stuffing box with a three-cavity structure has two cavities connected to nitrogen pipelines, maintaining a slightly positive pressure environment inside the cavities. At the same time, the irregularly shaped stuffing structure opens the sealed air passage, preventing external oxygen from entering the furnace and affecting the oxygen-free environment. The stuffing box with a three-cavity structure also has a cavity connected to a cooling water pipeline. The cavity is filled with cooling water to reduce the heat generated by the friction of the stuffing and keep the stuffing at a suitable working temperature, thereby ensuring its performance and extending its service life.

[0034] In this embodiment, the sensing component is a proximity switch 11, which is fixedly installed on the packing gland 2. It provides real-time feedback of the packing gland's compression displacement signal. The PLC control module 5 receives the displacement signals transmitted by each proximity switch and adjusts the stroke of the corresponding cylinder assembly 3 based on the distance values ​​at different circumferential positions of the packing gland 2. The proximity switch 11 is located at the corresponding gland position of each cylinder assembly 3 to provide feedback on the distance between the gland and the end face of the stuffing box, thus providing a cylinder stroke signal. The PLC control module 5 adjusts the cylinder stroke based on the displacement signal and the distance at different circumferential positions of the gland, preventing the packing gland from being too tight, too loose, or having uneven circumferential distances, which could lead to severe packing wear and failure.

[0035] In this embodiment, the sealing components at the feed end and discharge end of the roasting furnace are independently controlled in a closed loop. The cylinder assembly is adjusted and controlled separately according to the different leakage conditions at the head and tail of the roasting furnace. The signals from the oxygen content analyzer 4, the proximity switch 11, and the pressing cylinder assembly are all connected to the PLC control module 5, forming a closed loop control from oxygen content to the sealing and pressing distance.

[0036] The online adjustable sealing structure for the lithium iron phosphate roasting furnace described in this embodiment further includes: a feed box housing 12, a cylinder assembly mounting bracket 13, and a rotary bearing 14; the three-cavity stuffing box 1 and the oxygen content analysis component are fixedly assembled on the feed box housing 12; the base of the cylinder assembly 3 is fixedly installed on the cylinder assembly mounting bracket 13; the feed box housing 12 is assembled and connected to the furnace body sealing position 15 of the roasting furnace through the rotary bearing 14.

[0037] In this embodiment, the oxygen content analysis component includes an oxygen measuring component 16. One end of the oxygen measuring component 16 is connected to the interior of the roasting furnace body, and the other end is connected to the online oxygen content analyzer 4. The online oxygen content analyzer 4 collects oxygen content data in the furnace in real time and transmits the signal to the PLC control module 5.

[0038] In this embodiment, the PLC control module 5 is equipped with a threshold range for oxygen content in the furnace. When the oxygen analyzer signal shows that the oxygen content is higher than 20ppm, the piston rod of the cylinder assembly is automatically extended to press the packing gland and reduce the leakage gap between the packings. When the oxygen content is stable below 20ppm and the pressing stroke is too large, the cylinder assembly can appropriately retract the piston rod to reduce excessive friction of the packings and increase wear.

[0039] In this embodiment, multiple sets of cylinder assemblies 3 are evenly arranged at equal angles along the circumference of the packing gland, and each set of cylinder assemblies is matched with an independent proximity switch 11.

[0040] In the above embodiment, the furnace body sealing position 15 of the lithium iron phosphate roasting furnace with online adjustable feeding and discharging structure is connected to the feeding and discharging box shell 12 and the rotary bearing 14; the three-cavity stuffing box 1 and the oxygen measuring component 16 are fixed on the feeding and discharging box shell 12; the cylinder assembly 3 base is installed on the cylinder assembly mounting bracket 13 of the feeding and discharging box, and the piston rods of multiple sets of cylinder assemblies 3 are evenly and circumferentially fixed on the packing gland 2; the packing gland 2 is installed according to the arrangement position of the cylinder assembly 3. The proximity switch is used to detect the cylinder stroke and gland displacement. A shaped packing 6, a first shaped perforated ring 9, a second shaped perforated ring 10, and packing 7 are respectively arranged between the packing gland 2 and the three-cavity stuffing box 1, fitting the sealing end face of the furnace body sealing position 15. The outer side is connected to the first nitrogen inlet pipeline 17, the second nitrogen inlet pipeline 18, and the cooling water inlet pipeline 8. A slight positive pressure gas protection is formed through inert gas compensation, while the cooling chamber reduces the temperature generated by the frictional heat of the sealing packing, reducing wear. The externally integrated PLC control module 5 is connected to the online oxygen analyzer 4, the proximity switch 11, and the cylinder assembly 3.

[0041] In actual operation, the PLC control module 5 presets the oxygen content process threshold of 0~20ppm. When the oxygen content exceeds the standard, the system controls the piston rod of the cylinder assembly to extend, press the packing gland, and judges the uniformity of the sealing gap through the displacement signal fed back by the proximity switch to achieve precise fine adjustment; wait for the oxygen content index to stabilize within the qualified range, the cylinder assembly receives the stop working signal to lock the stroke and operate stably.

[0042] This invention allows for online adjustment of the distance between the packing gland and the end face of the stuffing box based on real-time oxygen content within the furnace. Pressure fine-tuning can be achieved without stopping the furnace, automatically compensating for wear gaps caused by prolonged packing operation, and ensuring that the oxygen content within the furnace remains consistently below the normal level of 20 ppm, enabling continuous and normal material production. It guarantees stable oxygen content and furnace pressure, meeting the reaction roasting requirements for the preparation of lithium iron phosphate, a cathode material for new energy applications. The sealing structure of this invention solves the technical problems existing in the current market for sealing structures in roasting furnaces used for the preparation of lithium iron phosphate, enabling lithium iron phosphate production to meet the needs of relevant enterprises.

[0043] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sealing structure for an online adjustable feed and discharge of a lithium iron phosphate roasting furnace, characterized in that: include: The furnace body of the roasting furnace; The system includes a sealing system for the inlet and outlet boxes mounted on the furnace body of the roasting furnace; the sealing system includes a three-cavity stuffing box, a sealing packing assembly, a packing gland, and a pressing and adjusting mechanism. Multiple sets of cylinder assemblies of the pressing and adjusting mechanism are evenly arranged along the circumference of the packing gland. The piston rod end of each cylinder assembly is rigidly fixedly connected to the packing gland. The packing gland and the sealing packing assembly abut against each other to achieve sealing and pressing. The sealing packing assembly is mounted between the three-cavity stuffing box and the sealing surface of the roasting furnace body. An oxygen content analysis component is assembled on the furnace body of the roasting furnace. The oxygen content analysis component is connected to an online oxygen content analyzer to collect the oxygen content signal inside the furnace. The electronic control system includes a PLC control module. The online oxygen content analyzer, the sensing component for detecting the displacement of the packing gland, and all the cylinder assemblies are electrically connected to the PLC control module via signal lines.

2. The online adjustable sealing structure for the feed and discharge of the lithium iron phosphate roasting furnace according to claim 1, characterized in that: The sealing packing assembly includes: shaped packing, packing and pore ring; the three-cavity stuffing box forms an annular gap with the sealing surface of the roasting furnace body, and the shaped packing, pore ring and packing are sequentially filled in the annular gap; The packing gland is slidably sleeved on the outside of the three-cavity stuffing box, and the inner side of the packing gland abuts against the packing. The cylinder assembly extends and retracts to drive the packing gland to slide axially to press or release the sealing packing assembly.

3. The online adjustable sealing structure for the lithium iron phosphate roasting furnace according to claim 2, characterized in that: The sealing packing assembly uses graphite braided PTFE high-temperature resistant packing. The sealing packing is composed of shaped packing and packing, with two pore rings fitted to fit the shape of the packing between the shaped packing and the packing.

4. The online adjustable sealing structure for the feed and discharge of the lithium iron phosphate roasting furnace according to claim 3, characterized in that: The three-cavity stuffing box sealing cavities at the feed end and discharge end of the roasting furnace body are all connected to inert gas replenishment pipelines; the three-cavity stuffing box is provided with two nitrogen sealing cavities and one cooling cavity, and the two nitrogen sealing cavities are connected to nitrogen pipelines. The nitrogen sealing cavities maintain a slightly positive pressure environment inside, while the irregularly shaped stuffing is expanded to form a sealed air channel; the cooling cavity is connected to a cooling water pipeline, and cooling water flows inside the cooling cavity.

5. The online adjustable sealing structure for the feed and discharge of the lithium iron phosphate roasting furnace according to claim 4, characterized in that: The pore ring is a first irregular pore ring and a second irregular pore ring. The three-cavity stuffing box is equipped with two nitrogen inlet pipelines, which are respectively connected to the two nitrogen-sealed cavities of the three-cavity stuffing box. Nitrogen is evenly distributed through the first irregular pore ring and the second irregular pore ring.

6. The online adjustable sealing structure for the feed and discharge of the lithium iron phosphate roasting furnace according to claim 1, characterized in that: The sensing component is a proximity switch, which is fixedly installed on the packing gland. The PLC control module receives the displacement signals transmitted by each proximity switch and adjusts the stroke of the corresponding cylinder assembly according to the distance values ​​at different circumferential positions of the packing gland.

7. The online adjustable sealing structure for the feed and discharge of the lithium iron phosphate roasting furnace according to claim 1, characterized in that: The sealing components at the feed end and discharge end of the roasting furnace body are independently controlled in a closed loop.

8. The online adjustable sealing structure for the feed and discharge of the lithium iron phosphate roasting furnace according to claim 1, characterized in that: The sealing structure further includes: a feed box housing, a cylinder assembly mounting bracket, and a rotary bearing; the three-cavity stuffing box and the oxygen content analysis component are fixedly assembled on the feed box housing; the base of the cylinder assembly is fixedly installed on the cylinder assembly mounting bracket; the feed box housing is assembled and connected to the furnace body sealing position of the roasting furnace through the rotary bearing.

9. The online adjustable sealing structure for the feed and discharge of the lithium iron phosphate roasting furnace according to claim 1, characterized in that: The oxygen content analysis component includes an oxygen measuring element. One end of the oxygen measuring element is connected to the inside of the roasting furnace body, and the other end is connected to the online oxygen content analyzer. The online oxygen content analyzer collects oxygen content data in the furnace in real time and transmits the signal to the PLC control module.

10. The online adjustable sealing structure for the feed and discharge of the lithium iron phosphate roasting furnace according to claim 1, characterized in that: Multiple sets of the cylinder assemblies are evenly arranged at equal angles along the circumference of the packing gland, and each set of the cylinder assembly is matched with an independent proximity switch.

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