CN112414112B

CN112414112B - A continuous kiln and heat treatment method

Info

Publication number: CN112414112B
Application number: CN202011388498.5A
Authority: CN
Inventors: 王霞; 吴桢
Original assignee: Xinnuo Advanced Thermal Technology Suzhou Co ltd
Current assignee: Xinnuo Advanced Thermal Technology Suzhou Co ltd
Priority date: 2020-12-01
Filing date: 2020-12-01
Publication date: 2025-09-23
Anticipated expiration: 2040-12-01
Also published as: CN112414112A

Abstract

A continuous kiln and heat treatment method are disclosed, belonging to the field of lithium-ion battery material processing. The continuous kiln comprises a kiln, an airflow supply and exhaust device, and an airflow control device. The airflow supply and exhaust device and the airflow control device cooperate to control the atmosphere within the kiln cavity. The opposing air supply and exhaust nozzles in the airflow supply and exhaust device create a transverse airflow perpendicular to the length of the kiln, thereby maintaining a stable atmosphere within the kiln.

Description

Continuous kiln and heat treatment method

Technical Field

The application relates to the field of lithium ion battery material processing, in particular to a continuous kiln and a heat treatment or thermochemical treatment method.

Background

Continuous kilns are one of the important devices for producing lithium ion battery cathode materials. The continuous kiln is mainly built by refractory materials, heat-insulating materials and building materials, and is a kiln with a tunnel structure with two open ends.

In the production of positive electrode materials for lithium ion batteries, it is often necessary to introduce a specific gas (e.g., dry air, oxygen, nitrogen, etc.) into a continuous kiln to form the process atmosphere required for the positive electrode material during heat treatment or thermochemical treatment, such a specific gas being referred to as a process gas. Meanwhile, when the positive electrode material is subjected to heat treatment or thermochemical treatment in a kiln, some gaseous by-products (exhaust gas) during the reaction, such as water vapor and carbon dioxide, are released, and often contain some residual corrosive substances or gases. These exhaust gases need to be discharged from the kiln as soon as possible, otherwise the atmosphere control in the kiln is seriously affected, resulting in deterioration of the performance of the calcined cathode material.

Disclosure of Invention

In order to solve the problem of controlling the atmosphere in the existing kiln, the application provides a continuous kiln and a heat treatment or thermochemical treatment method.

The application is realized in the following way:

in a first aspect, examples of the present application provide a continuous kiln comprising a kiln, an air flow conveyor and an air flow control device.

Wherein the kiln has a furnace chamber extending in a first direction from the furnace head to the furnace tail. The air flow discharging device is used for forming a directional air flow which can flow along a second direction from one side wall to the other side wall of the kiln in the furnace chamber. The air flow feeding and discharging device is provided with a feeding and discharging group, and the feeding and discharging group is provided with a feeding nozzle and a pumping nozzle which are connected to the furnace wall and are mutually matched and opposite, and the feeding nozzle and the pumping nozzle are arranged along a third direction from the top to the bottom of the kiln. The air flow control device is connected with the air flow feeding and discharging device in a matching way, so as to control the air feeding nozzle and the suction nozzle.

The air flow feeding and discharging device is matched with the control of the air flow control device, and forms directional flowing air flow in the furnace chamber of the kiln through the matching of the air feeding nozzle and the air suction nozzle, so that the required process atmosphere can be continuously maintained in the furnace chamber, for example, the gas concentration or the pressure of the calcination atmosphere can be reached to the required degree. And the process gas is continuously input through the gas feeding nozzle, so that the atmosphere in the continuous kiln can be updated, and the waste gas in the continuous kiln can be discharged. Meanwhile, the loss of heat can also be controlled by controlling the flow rate of gas, etc.

In some examples of the application, the oven wall is provided with a gas distributor at the connection of the gas delivery nozzle, which communicates with the gas cavity of the gas distributor.

The gas distributor can achieve the effect of simplifying the gas conveying structure, and can also reduce the control difficulty of the gas flow control device.

In some examples of the application, the furnace wall has an intake port at the junction with the suction nozzle, the intake port being disposed in a third direction, the suction nozzle being in communication with the intake port.

Optionally, the air suction port is elongated.

The long and narrow air suction port can provide a larger air suction area and corresponds to more air supply nozzles, so that the uniformity of air suction and exhaust to various positions is further improved.

In some examples of the application, the continuous kiln includes a sagger for holding material, the sagger having a side wall with a gap that forms a channel for directional air flow through the sagger, the gap being oriented toward the suction port and the air delivery nozzle, respectively.

Optionally, the mouth of the air delivery nozzle is proximate the opening.

The sagger is provided with the notch which is beneficial to the flow of the air flow, so that the air flow can more easily take away the waste gas, and the turbulent flow of the air flow is reduced.

In some examples of the application, the continuous kiln comprises a detection device comprising a furnace pressure sensor and/or a gas concentration sensor for detecting the kiln.

Optionally, the detection means comprises a pressure sensor and/or a flow sensor, one or both of the suction nozzle and the delivery nozzle being provided with a pressure sensor and/or a flow sensor.

The furnace pressure sensor and the gas concentration sensor can reflect the concentration and the pressure of the atmosphere in the furnace chamber of the kiln, thereby facilitating the detection of the atmosphere condition in the furnace chamber by a user. The pressure sensor and the flow sensor can reflect the working conditions of the air feeding nozzle and the air extracting nozzle, and the air flow fed into the furnace chamber and the air flow discharged out of the furnace chamber, so that the control of the atmosphere in the furnace chamber is more effective and efficient.

In some examples of the application, the airflow control device includes an air feed valve and an air discharge valve, the air feed valve is matingly connected with the air feed nozzle, the air discharge valve is connected with the air suction nozzle, and the air feed valve and the air discharge valve are configured to be operated in response to the detection device.

In some examples of the application, the airflow control device is configured to control the air feeding nozzle and the air extracting nozzle in a linkage manner, so that the air input and the air output in the kiln can be controlled in a linkage manner, and the strength of the directional airflow in the kiln is more stable.

In some examples of the application, all of the suction nozzles in the plurality of feed rows are located on one side of the furnace wall and all of the suction nozzles in the plurality of feed rows are located on the other side of the furnace wall;

or the furnace wall on one side and the furnace wall on the other side are provided with a suction nozzle and a gas supply nozzle, and the suction nozzles and the gas supply nozzles on the furnace wall on the same side are alternately arranged at intervals in the third direction;

or the number of the air flow discharging devices is multiple and the air supply nozzles of the same air flow discharging device are arranged along the first direction, the air suction nozzles of the same air flow discharging device are positioned on one furnace wall, the air suction nozzles are positioned on the other furnace wall, and the air suction nozzles and the air supply nozzles of two adjacent air flow discharging devices are alternately arranged at intervals in the first direction.

Different configurations of the air flow discharging device can meet different modes of the continuous kiln, and different degrees of updating and temperature adjusting effects on the atmosphere in the furnace chamber can also be realized.

In some examples of the application, the continuous kiln includes a heater coupled to the kiln.

In some examples of the application, the heater is arranged along a third direction and is connected to a wall of the kiln. Optionally, the heaters are arranged along a third direction, and an air delivery nozzle or an air extraction nozzle is arranged between two adjacent heaters.

In a second aspect, examples of the application provide a method of performing a heat treatment or a thermochemical treatment by a continuous kiln as described above. The heat treatment or thermochemical treatment method comprises providing the temperature of heat treatment or thermochemical treatment in the furnace chamber of a kiln, conveying the object to be heat treated or thermochemical treatment in the furnace chamber along a first direction by a loading tool, and inputting process gas into the furnace chamber by a gas flow feeding and discharging device under the control of a gas flow control device and synchronously discharging the gas from the furnace chamber by the gas flow control device during conveying so as to maintain the heat treatment or thermochemical treatment atmosphere in the furnace chamber.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view of the structure of a kiln body in a continuous kiln according to an example of the application;

FIG. 2 shows a schematic view of the structure of a continuous kiln in an example of the application at a first view angle;

FIG. 3 shows a schematic view of the structure of the continuous kiln at a second view angle in an example of the application;

FIG. 4 shows a schematic structural view of a sagger for use in a continuous kiln in an example;

FIG. 5 illustrates a schematic view of an example air delivery nozzle having a cutout.

The icons are 101-kiln, 1011-furnace head, 1012-furnace tail, 1013-furnace chamber, 1014-furnace wall, 1015-furnace top, 1016-furnace bottom, 11-heater, 32-gas feed nozzle, 202-injection device, 203-exhaust device, 31-gas distributor, 2-sagger, 38-gap, 39-suction port, 40-exhaust valve, 42-gas feed valve, 18-process gas, 37-gas suction nozzle, 44-exhaust gas.

Detailed Description

As one of core materials of lithium ion batteries, a positive electrode active material (hereinafter, referred to as a positive electrode material) plays a vital role in the safety, the overall performance and the cost of the battery.

In the production process, the heat treatment or thermochemical treatment, especially high-temperature calcination, of the positive electrode material is a core element for determining the material properties. In addition, during the calcination process, many cathode materials require a specific process gas to be introduced into the kiln for calcination to maintain a specific atmosphere and to strictly control the specific atmosphere. For example, oxygen is required to be introduced into the ternary positive electrode material, particularly the high-nickel ternary material, and a nitrogen atmosphere is required to be used for protecting lithium iron phosphate. For the positive electrode materials requiring special atmosphere during calcination, the atmosphere control during the calcination process is one of very important conditions, which affects the performance of the positive electrode materials after calcination, so that manufacturers of the positive electrode materials and related researchers are striving to improve the atmosphere control capability of the kiln during the calcination of the positive electrode materials.

Currently, calcination of the cathode material is typically accomplished by a continuous kiln. Such as a pusher kiln (for short, pusher kiln) and a roller kiln (for short, roller kiln). The tunnel kiln is a kiln with a tunnel structure which is built by refractory materials, heat insulation materials and building materials and is provided with two open ends. According to different temperatures and functions, the tunnel kiln is generally segmented to form a heating zone, a heat preservation zone and a cooling zone. The kiln body is heated in the tunnel kiln by an electric heater or by a mode of burning injected fuel (such as natural gas, heavy oil and the like). The material to be heat treated or thermochemical treated or the carrier (such as sagger) for carrying the material is loaded by the carrier, enters the tunnel kiln from one end (kiln head) of the tunnel, moves through the heating zone, the heat preservation zone and the cooling zone, and exits from the other end (kiln tail) of the tunnel kiln to finish the heat treatment process.

However, as a result of the practice, the present inventors have found that existing kilns have various degrees of defects, which results in the calcination of the cathode material not meeting the requirements.

Through analysis, the inventors believe this is mainly because:

During calcination, the positive electrode material reacts with the process gas. The reaction is promoted to proceed sufficiently only when the process gas is in sufficient contact with the calcined material. In addition, a large amount of process gas flows through the surface of the materials, so that gas byproducts generated by the reaction can be carried away as soon as possible, and the reaction is promoted. However, the continuous kiln for calcining the anode material, such as a pusher kiln or a roller kiln, cannot sufficiently meet the two key requirements.

For example, lithium ion battery cathode materials are typically powdered materials prior to calcination, and the powdered material to be calcined is typically placed in a carrier. In order to increase the capacity of the kiln, the material-carrying sagger is placed in a stacked manner on the carrier, thereby severely affecting the air flow delivery.

Taking the prior art that the air is introduced from the bottom and the side wall of the kiln and the air is discharged from the kiln top as an example, the process gas introduced from the air inlet of the side wall of the kiln can flow upwards under the suction of the negative pressure of the air outlet of the kiln top, and is discharged from the air outlet of the kiln top.

The process gas entering from the bottom inlet is blocked by the bottom of the lower sagger, most of the process gas can only flow along the periphery of the sagger and is converged into the upward flowing gas flow, and a small part of the process gas passes through the gaps between the saggers and upwards enters the exhaust port.

The materials in the upper layer sagger can be in relatively full contact with the process gas because the top of the sagger is not provided with a shielding object, and meanwhile, the waste gas released by the materials in the upper layer sagger can be discharged from the top exhaust port along with the main air flow relatively smoothly.

However, the lower sagger is shielded by the upper sagger, so that the process gas cannot smoothly enter, and the waste gas released by the materials cannot be smoothly taken away by the air flow. The gas exchange inside and outside the lower layer sagger is mainly completed through diffusion, wherein a small part of process gas enters the sagger from the opening at the edge of the sagger through diffusion. Similarly, the waste gas released from the materials in the lower layer sagger escapes from the sagger through diffusion action from the opening at the edge of the sagger, and then is converged towards the kiln top along with the airflow at the periphery of the sagger and is discharged from the exhaust port.

Also, the prior art approaches of gas intake from the top and gas exhaust from the bottom of the kiln are not capable of solving the problems of blocked exhaust of the underlying sagger material and insufficient contact with fresh process gas.

In short, in the case of stacked saggers, because the upper sagger shields the lower sagger, either the process gas enters the lower sagger or the exhaust gas escapes the lower sagger, mainly by diffusion.

Therefore, the gas exchange efficiency between the inside and the outside of the lower sagger is very low. And the diffusion directions of the two gases are opposite, so that the exchange of the gases is weakened, the concentration of the process gas in the lower-layer sagger is far lower than that of the upper-layer sagger, and the accumulation of the waste gas in the lower-layer sagger is far higher than that of the upper-layer sagger.

The atmosphere contacted by the materials in the upper and lower saggers is greatly different, the performance of the positive electrode materials in the upper and lower saggers is also greatly different after calcination, and the consistency of the products is poor. Worse, with the pressure of cost reduction, the cathode material manufacturers stack more saggers in the kiln, and with the number of stacked saggers increasing, the problem becomes worse.

In addition, because the air pressure of the air inlet of the kiln is not high, the speed of the air flow can be greatly reduced after the process gas enters a larger space in the kiln body from the air inlet, so that the exhaust emission and the uniform distribution of the process gas are blocked. On the other hand, too high an intake pressure may cause excessive disturbance to the positive electrode material powder, causing it to fly, and not facilitating normal transportation.

In view of the current situation, the inventors propose to form an orderly highly directional gas flow in a kiln so that the positive electrode active material can be sufficiently contacted with the process gas to perform a reaction, and simultaneously, exhaust gas generated by the reaction can be timely discharged to inhibit adverse effects of the exhaust gas on the reaction.

In order to achieve the above-described effects, in the present application, the inventors propose a continuous kiln. The continuous kiln includes kiln 101, an air flow delivery device and an air flow control device, as will be described in more detail below.

Kiln 101

The kiln 101 in the example is structured as shown in fig. 1, having a wall 1014, a bottom 1016 and a roof 1015. In particular, to facilitate control of the process gas 18 therein and reduce ineffective process gas 18 consumption, the cross-section of the interior of the kiln 101 can be designed to be thin and tall, with a small proportion of free space (space without saggers 2) within the interior dome/roof 1015 of the kiln 101 (the arcuate structure at the top in fig. 2) being smaller (the area of the oven cavity in the region of the arcuate roof being smaller than the area of the oven cavity in the region of the oven wall).

The flow of process gas 18 in the continuous kiln of the present application is shown in figures 2 and 3. For ease of illustration and understanding, the kiln 101 defines three directions, a first direction, a second direction, and a third direction, respectively. Specifically, a first direction is defined by the jamb 1011 to the furnace tail 1012 as shown in direction B (or length direction) in fig. 1, a second direction is defined by the one side furnace wall 1014 to the other side furnace wall 1014 as shown in direction C (or width direction) in fig. 1, and a third direction is defined by the roof 1015 to the furnace bottom 1016 as shown in direction a (or height direction) in fig. 1.

The kiln 101 constitutes the main structure of a continuous kiln, and operations such as heat treatment or thermochemical treatment are also mainly performed in the kiln 101. As a place to provide a thermal or thermo-chemical treatment, the kiln 101 has a furnace chamber 1013 bounded by a furnace wall 1014. In the actual use process, the heat treatment or thermochemical treatment materials enter from the furnace head 1011 of the furnace 101, sequentially enter into different sections (such as a heating section, a heat preservation section and a cooling section which are sequentially distributed) of the furnace chamber 1013, and finally leave from the furnace tail 1012 thereof. It should be noted that, as a device for heat treatment or thermochemical treatment, the kiln 101 is generally required to maintain a certain airtight and closed state, and therefore, the furnace head 1011 and the furnace tail 1012 thereof are generally required to be provided with a shutter or the like which can be selectively opened and closed, and the kiln 101 can be also constructed to be airtight by a housing. This is not illustrated in the examples of the present application. Those skilled in the art will appreciate that the apparatus described above may be provided by the prior art, and the present application is briefly described herein in order to avoid unnecessary redundancy.

In order to perform the heating operation, the kiln 101 is generally required to be equipped with a heating device. As previously mentioned, the heating device may directly heat selected locations within the kiln 101 by injecting fuel. But taking into account the foreign matter that may be introduced and the effect on the calcination reaction. An electric heater 11, such as a heating rod, or a combustion heating method with a heat radiation pipe is generally selected. The heating rod may be a specific product such as the resistance heater 11.

In the present example, a heater 11 is provided in the continuous kiln, and the heater 11 is connected to the kiln 101 (shown in fig. 3). In some examples, the heater 11 may be inserted into the furnace chamber 1013 from the furnace roof 1015, or the heater 11 may be inserted into the furnace chamber 1013 through the furnace floor 1016 or the furnace wall 1014. Considering that the heater 11 may obstruct the material to be calcined conveyed in the furnace chamber 1013, in the example of the present application, the heater 11 is inserted and fixed near the furnace wall 1014 and is inserted in the direction a from the furnace top 1015 to the furnace bottom 1016, see fig. 1 and 3.

In the disclosure of fig. 3, the heater 11 is provided on both sides of the kiln 101 on the furnace walls 1014. The heaters 11 of the furnace walls 1014 on both sides are equal in number and are opposed one to another in the direction C. In the furnace wall 1014 on the same side, two adjacent heaters 11 are spaced apart from each other by an appropriate distance. Of course, other options are possible for the installation position and mode of the heater 11, which is not particularly limited in the present application.

In addition, various suitable devices and equipment, such as a detection device, may also be selectively configured for the kiln 101, according to different needs.

For example, in different modes of use, other gas supply plumbing may alternatively be provided if it is desired to provide additional atmosphere to the furnace chamber 1013 of the kiln 101.

For example, in order to monitor the temperature in the furnace chamber 1013 of the kiln 101 in order to adjust the temperature in good time, a temperature detecting device, such as a temperature sensor, in particular an infrared temperature detector, etc., may be provided in the kiln 101.

Since the calcination in the furnace chamber 1013 requires the supply of the process gas 18, a gas monitoring device may also be provided in the kiln 101 corresponding thereto. The gas monitoring device may be a gas pressure detector, a concentration detector, or both. The gas pressure sensor may be a furnace pressure sensor for detecting the pressure of the furnace 101 and the concentration sensor may be a gas concentration sensor for detecting the concentration of the process gas 18 (e.g., oxygen) within the furnace 101.

In addition, the continuous kiln can be equipped with a device for holding and transporting the calcined material (e.g., positive electrode material), such as a sagger 2, as shown in fig. 4. To facilitate the flow of air through the sagger 2, the side wall of the sagger 2 is provided with a notch 38. Thus, when multiple saggers 2 are stacked, the cutouts 38 of different saggers 2 can form channels for directing air flow through the saggers 2.

Air flow discharging device

In the present example, the air flow feeding and discharging device mainly includes an air flow input portion and an air flow discharge portion. And, the two parts cooperate to form a continuous and directed air flow within the kiln 101. The term "orientation" refers to a direction C that is staggered (e.g., crisscrossed) with respect to a direction B of the kiln 101, i.e., from one side wall 1014 of the kiln 101 to the other side wall 1014. In other words, during the longitudinal transport of the calciner material in the furnace chamber 1013 from the kiln head to the kiln tail, a transverse air flow can be formed by the air flow conveyor.

Wherein the gas flow inlet is used for delivering the process gas 18 into the furnace chamber 1013 of the kiln 101 for reaction requirements during calcination. Wherein the air flow exhaust portion is used for exhausting the exhaust gas 44 in the furnace chamber 1013 of the kiln 101 to the outside of the kiln 101.

With this gas flow feeding and discharging device, an update of the atmosphere in the furnace chamber 1013 of the kiln 101 can be achieved, for example an addition of fresh process gas 18, while discharging exhaust gases 44. Also, the temperature in the cavity 1013 can be controlled to some extent by controlling the conveyance state of the air flow such as the flow rate, and the like. Because the exhaust gas 44 may carry away a portion of the heat, the temperature of the freshly input process gas 18 may also absorb a portion of the heat.

The gas flow discharging device is provided with a gas flow discharging group. The feed bank includes any number of air feed nozzles 32 and air suction nozzles 37. And the air feed nozzle 32 and the air suction nozzle 37 are spaced and opposed to each other, and both the air feed nozzle 32 and the air suction nozzle 37 are connected to the furnace wall 1014, so that the spaced area therebetween is the passage of the furnace chamber 1013 for transporting the calcined material.

The air delivery nozzles 32 and air extraction nozzles 37 in the row of air delivery groups are arranged in a third direction from the top 1015 to the bottom 1016 of the kiln 101. I.e. the air delivery nozzles 32 and the air extraction nozzles 37 are arranged along the height direction of the kiln. Therefore, when the calcination object having a large height is placed in the furnace chamber 1013 of the kiln 101, the arrangement of the air supply nozzle 32 and the air exhaust nozzle 37 along the third direction can effectively cover the calcination object so that it is uniformly affected and influenced by the directional air flow. As a modification, the opening 38 of the sagger 2 for holding the calcined material is directed toward the gas nozzle 32. Further, the mouth opening (gas outlet) of the gas supply mouth 32 is close to the cutout 38 (to the extent that normal conveyance of the sagger is not hindered), so that it is easier to accurately convey the gas to the sagger 2.

FIG. 2 is a schematic cross-sectional view of a continuous kiln showing a row of air delivery groups comprising 8 air delivery nozzles 32 and 3 suction nozzles 37. In other examples, the number of air delivery nozzles 32 and suction nozzles 37 of a row of air delivery groups may be equal, or the number of air delivery nozzles 32 may be less than the number of suction nozzles 37. In other words, the air supply nozzles 32 and the air extraction nozzles 37 may be arranged one to one, or may be arranged one to many or many to one.

The above description is given by taking the continuous kiln having only one air flow feeding device as an example. When the continuous kiln in other examples has multiple gas flow banks, it has multiple banks accordingly. Thus, in the case of having multiple banks, all banks may be arranged along the length of kiln 101, as shown for example in fig. 3.

The above-described fig. 2 and 3 disclose only one arrangement of the feeding group in the present application, and in other examples, the feeding group may have other arrangements, which will be described in detail below.

In case one, in the direction a of the kiln 101, in one row group, the air nozzles 32 are all provided in one of the furnace walls 1014, and the air suction nozzles 37 are all provided in the other furnace wall 1014.

In the second case, in the direction a of the kiln 101, in one row group, part of the delivery nozzles 32 are provided in one of the furnace walls 1014, and the rest of the delivery nozzles 32 are provided in the other furnace wall 1014. Accordingly, in this bank, a portion of the suction nozzles 37 are disposed in one of the furnace walls 1014, and the remaining suction nozzles 37 are disposed in the other of the furnace walls 1014.

For continuous kilns having only one air flow conveyor, and accordingly one conveyor group, the air supply nozzles 32 and the air extraction nozzles 37 therein may be arbitrarily selected to be structured in the manner of the above-described case one or case two.

For a continuous kiln having a plurality of (e.g., more than two) gas flow rows, there are a plurality of rows. All the rows are arranged along the direction B of the kiln 101. And the air delivery nozzles 32 and the air extraction nozzles 37 in each row group can be arranged in a mode of a first case, a mode of a second case or a combination of the first case and the second case.

In the illustrated embodiment of the present application, a plurality of feed-line groups are provided, and the above-described first and second cases are adopted in which the air supply nozzles 32 and the air exhaust nozzles 37 are arranged in combination. In particular, adjacent two rows of gas feed nozzles 32 and gas extraction nozzles 37 of the same side wall 1014 are alternately arranged. In this way, when more than one row (two rows are shown in fig. 3) of sagger 2 is stacked on top of the carrier of calcined material in kiln 101 to pass through the kiln, sagger 2 on each side has equal opportunity to face gas injector 202 or exhaust 203, i.e. the probability of carrier etc. facing gas nozzle 32 and gas nozzle 37. This improves the consistency of calcination of the material in the different rows of magazines 2, so that each magazine 2 will have an alternating flow of air across it. To ensure better consistency, the saggers 2 in the example of the application are stacked in two columns, as shown in fig. 3.

The arrangement of the air delivery nozzle 32 and the air extraction nozzle 37 can be also pertinently adjusted according to the position and the structure of the heater 11 in the kiln. For example, the air feed nozzle 32 or the air suction nozzle 37 is provided between two adjacent heaters 11. That is, for the example of a plurality of row groups, the air supply nozzles 32 and the air extraction nozzles 37 of adjacent two row groups are alternately arranged, and therefore, the heater 11 may be disposed between the air supply nozzles 32 and the air extraction nozzles 37. Correspondingly, the air supply nozzle 32 or the air extraction nozzle 37 is also alternately clamped between the two heaters 11. The alternate mode may be one shown by one (one heater 11, one air supply nozzle 32, one heater 11, one air supply nozzle 32), or may be two heaters 11, two air supply nozzles 32, or the like. The process gas 18 can be sufficiently preheated again while preventing the heating power of the heater 11 from being affected by the direct injection of the gas onto the adjacent heater 11 when the process gas 18 is injected.

The arrangement of the rows is described above, and the specific structure of the air delivery nozzles and the suction nozzles therein will be described in detail below.

In the example, the air supply nozzle 32 is constructed in a cylindrical hollow tube. And one end thereof is inserted into the furnace wall 1014 and the other end thereof is inserted into the furnace chamber 1013. The gas delivery nozzles 32 may be configured to deliver the process gas 18 through a gas flow path through a conduit (which may be a hollow block of firebrick, a ceramic tube, or a metal tube lining ceramic refractory) embedded in the furnace wall 1014. In other examples, the air supply nozzle 32 may be disposed outside the kiln 101, and an injection tube connected to the air supply nozzle 32 may be inserted into the kiln through a hole in the kiln wall 1014, or the cavity 1013 may be filled with air from the air supply nozzle 32 outside the kiln through a hole in the kiln wall 1014 without adding an injection tube inserted into the kiln. Or adopting a hollow brick stacking kiln, then arranging air holes communicated with the hollow structure on the hollow bricks, and injecting gas through the air holes.

When the number of air delivery nozzles 32 is large, providing individual piping for each air delivery nozzle 32 may result in complex processes and structures. Thus, in the example shown, a cavity is optionally reserved in the furnace wall 1014, which can be supplied directly by a pipeline. The air nozzle 32 may be directly connected to the chamber. Functionally, the chamber essentially constitutes a gas distributor 31. A heating plate may also be provided in the gas distributor 31 for heating the process gas 18 entering therein to avoid cold process gas 18 entering directly into the furnace chamber 1013. Of course, the process gas 18 may also be preheated outside the continuous kiln and then introduced into the gas distributor 31 and then injected into the furnace chamber 1013 via the gas nozzle 32.

In addition, as a modification, the structure of the air supply nozzle 32 in the form of a hollow tube may be modified and fitted to the air distributor 31. For example, in some examples, the end of the air delivery nozzle 32 that extends into the air distributor 31 is notched to form an "L" end structure. And, the incident directions of the process gases 18 into the gas distributor 31 are far away from the gap of the gas nozzle 32 and are opposite to each other, as shown in fig. 5. Thus, the process gas 18 in the gas distributor 31 can be delayed in time to the nozzle, thereby allowing the process gas 18 to be heated in the distributor for a longer time and improving the heating effect.

Similarly, the suction nozzle 37 may also be constructed as a hollow tube. The suction nozzle 37 may also be configured by providing a trough structure in the furnace wall 1014 for the suction line to discharge the exhaust gases 44 from the furnace chamber 1013. In the present example, the furnace wall 1014 is provided with an air suction 39 at the suction nozzle 37, and obviously the suction nozzle 37 communicates with this air suction 39. And the suction port 39 is disposed in a third direction (i.e., a depth direction of the cavity 1013). In some examples, the air inlet 39 may be elongated, and may have a rectangular cross section, or an elliptical cross section. When the furnace wall 1014 is provided with the suction port 39, one end of the suction nozzle 37 may be inserted into the suction port 39, and the other end thereof may protrude outside the kiln 101.

In addition, as a power source for conveying the gas by the gas nozzle 32 and the gas nozzle 37, the air flow conveying and discharging device may be provided with a blower, a fan, an exhaust fan, an air pump, and the like in a matching manner. In the present example, the injection device 202 is provided in correspondence with the air supply nozzle 32, and the exhaust device 203 is provided in correspondence with the air exhaust nozzle 37.

Air flow control device

The air flow control device is equipment matched with the air flow feeding and discharging device. Which is capable of controlling the air delivery nozzle 32 and the air extraction nozzle 37 and having both the air delivery nozzle 32 and the air extraction nozzle 37 operate in a matched manner. I.e. the operating state of the air delivery nozzle 32 is associated with the operating state of the air extraction nozzle 37. When the operating conditions of the air delivery nozzle 32 are adjusted, the condition of the suction nozzle 37 is correspondingly adjusted. In principle, the intake air amount of the intake nozzle 32 is matched with the exhaust air amount of the air suction nozzle 37 by adjustment of the air flow control device, for example, the intake air amount is made equal to the exhaust air amount.

In other words, under some conditions, the airflow control device may control the air delivery nozzle 32 and the air extraction nozzle 37 in linkage. Of course, in other examples, the air flow control device may also independently control the air delivery nozzle and the suction nozzle, respectively. For example, when a certain automatic control fails or the automatic control adjusting range in the linkage mechanism cannot meet the actual requirement or needs to be changed into manual operation under certain special conditions, the system can be switched into manual mode through a program, the gas level in the furnace is achieved by manually adjusting the gas inlet control valve and the gas outlet control valve by means of on-site meters (the values of the flowmeter, the differential pressure meter and the pressure transmitter), and whether the gas is balanced or not is judged through the display of the oxygen partial pressure value.

The air inflow and the exhaust amount are controlled to be matched, so that the strength of the formed directional air flow is more stable. In addition, excessive flue gas generated by relatively too large exhaust gas amount can not bring away a large amount of heat in the kiln 101 to cause unnecessary energy loss, and the too high residual amount of the waste gas 44 in the kiln 101 caused by relatively too small exhaust gas amount can be avoided.

As one example, the airflow control device includes an air feed valve 42 (which may be an automatic control valve, which may have a manually adjustable handle) and an air discharge valve 40 (which may be an automatically controlled corrosion resistant high temperature valve, which may have a manually adjustable handle).

Wherein, the air supply valve 42 is connected with the air supply nozzle 32 in a matching way, and the exhaust valve 40 is connected with the air suction nozzle 37. Control of the process gas 18 delivery state and the exhaust gas 44 delivery state can be achieved by adjustment of the opening of the two valves. The valve may employ various butterfly valves, ball valves, regulating valves, throttle valves, and the like. In order to improve the accuracy of control and to facilitate operation, the exhaust valve 40 and the air supply valve 42 may be selectively provided with proportional solenoid valves.

Further, the continuous kiln may also be provided with detection means such that the gas feed valve 42 and the gas discharge valve 40 are configured to be operated in response to the detection means. In other words, the operation of the air feed nozzle 32 and the air discharge nozzle is realized by adjusting the air feed valve 42 and the air discharge valve 40 correspondingly according to the operation condition of the continuous kiln detected by the detecting means.

The detection device can comprise a pressure sensor and a flow sensor. Wherein the pressure sensor and the flow sensor may be connected in the plenum piping system and upstream of the air delivery nozzle 32. Alternatively, a pressure sensor and a flow sensor may be connected in the suction piping system downstream of the suction nozzle 37.

Furthermore, a furnace pressure sensor and a gas concentration sensor of the process gas 18, which are provided in the furnace 101, can also be provided as components of the detection device. Therefore, various states of the injected gas and the exhaust gas and the gas in the furnace chamber 1013 of the kiln 101 can be truly reflected by the detection means, so that the operation of the gas flow control means can be made more accurate.

Based on the need to enhance the automation of the control, the controller may be selected to control the air supply valve 42 and the air discharge valve 40, and the detection device is connected to the controller in a matching manner, so that the collection, processing and control information emission of the detection information are coordinated with each other. The controller may be various electronic components or a collection thereof capable of certain data storage and processing. Such as a Central Processing Unit (CPU), a Micro Control Unit (MCU), an editable logic controller (PLC), a Programmable Automation Controller (PAC), an industrial control computer (IPC), a Field-Programmable gate array (Field-Programmable GATE ARRAY, FPGA), an Application-specific integrated Circuit chip (ASIC chip), and the like. By such a structural design, the continuous kiln is capable of closed loop operation of gas injection and discharge.

The working principle of the controller can be as follows:

Partial pressure data of the process gas 18 in the furnace chamber 1013 is collected by a furnace pressure sensor and a gas concentration sensor. The controller judges the gas exchange efficiency in the furnace and then sets a target intake air amount to the intake air flow rate of the air feed valve 42 of the air feed nozzle 32 to adjust the actual intake air amount. Meanwhile, the controller calculates the target opening of the exhaust valve 40 of the exhaust system by taking the flow data of the air supply valve 42 as a parameter, and is used for adjusting the exhaust amount of the exhaust system to realize the linkage control of the exhaust amount and the air inflow.

When the partial pressure of the process gas 18 is lower than a set value by a certain percentage, the opening of the gas feed valve 42 is increased while the opening of the gas discharge control valve is increased, when the partial pressure of the process gas 18 is higher than the set value by a certain percentage, the gas feed flow control valve is closed while the opening of the gas discharge control valve is decreased, and when the partial pressure of the process gas 18 is maintained within the set value by a certain percentage, the gas feed flow control valve and the gas discharge control valve are maintained unchanged. In addition, in order for this feedback system to operate smoothly without excessive or slow motion, the furnace pressure within the furnace chamber 1013 of the kiln 101 acts as an intermediate equilibrium constant so that any adjustments need to maintain the furnace pressure within a set fluctuation range.

In summary, the continuous kiln provided by the application can achieve better use effect, and the concentration of the process gas 18 in the kiln is uniformly distributed, so that the calcined material can be uniformly and consistently contacted with the process gas 18, and the consistency of the performance of the calcined product is further improved.

As an example of application, the application also proposes a method of thermal or thermochemical treatment comprising:

step 1, providing a temperature of the heat treatment or thermochemical treatment in the furnace chamber 1013 of the kiln 101.

Wherein the temperature of the heat treatment or thermo-chemical treatment may be provided by a heater 11 of the continuous kiln arranged in the kiln 101. The number and position of the heaters 11 in operation can be adapted to different temperature sections (heating section, cooling section, etc.) of the kiln 101.

Step 2, the object to be heat-treated or thermo-chemical treated is transported in the furnace chamber 1013 in the first direction by the loading tool, and during the transportation, the process gas is inputted into the furnace chamber 1013 by the gas flow feeding and discharging device under the control of the gas flow control device, and the gas is synchronously discharged from the furnace chamber 1013 by the gas flow control device, so as to maintain the desired process atmosphere in the furnace chamber 1013.

The loading tool is, for example, a sagger 2, and is conveyed by a roller way, a push plate or a kiln car. In order to increase the throughput while simultaneously taking account of the utilization of the process gases 18, the magazines 2 on the transport means are arranged in two rows of eight layers each. The kiln car gradually passes through the temperature raising zone, the heat preserving zone and the cooling zone from the kiln head to convey the sagger 2, and in the process, the process gas 18 is continuously injected and the waste gas 44 is continuously discharged until the sagger 2 is discharged from the kiln tail to finish the calcination process.

With the continuous kiln provided by the application, for heat treatment or thermochemical treatment operation under the condition that the sagger 2 is stacked with a higher layer number, the sagger 2 at the lower layer can be contacted with the process gas 18 with increased concentration, and the accumulation of the waste gas 44 of the sagger 2 at the lower layer is reduced, so that the atmosphere consistency in the sagger 2 at the upper layer and the lower layer and the consistency of the performance of the calcined product are improved. In addition, the strength of the directional air flow is stabilized by selectively controlling the air inflow and the air exhaust in a linkage way, and the gas injection devices 202 and the air exhaust devices 203 are arranged on each kiln wall in a staggered way, so that when a plurality of rows of saggers 2 are stacked, the outermost saggers 2 can face the gas injection devices 202 and the air exhaust devices 203 with equal probability, and the consistency of the atmosphere in the saggers 2 at two sides is also improved.

It should be noted that, although in the present example, the continuous kiln is proposed as a positive electrode material for producing lithium ion batteries by calcination, this is not meant to limit the present application to be used only for this. In other examples, the continuous kiln may also be used to fire ceramic materials or other alloy materials thereof, and so forth.

The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A continuous kiln, which comprises a kiln body and a kiln body, characterized by comprising the following steps:

a kiln having a cavity extending in a first direction from a burner to a tail;

The air flow discharging device is used for forming directional air flow capable of flowing along a second direction from one side furnace wall to the other side furnace wall of the kiln in the furnace chamber, and is provided with a discharging group, wherein the discharging group is provided with air feeding nozzles and air extracting nozzles which are connected to the furnace wall and are mutually matched and opposite, and the air feeding nozzles and the air extracting nozzles are arranged along a third direction from the top to the bottom of the kiln;

The air flow control device is connected with the air flow feeding and discharging device in a matching way, so that the air feeding nozzle and the air extracting nozzle can be controlled;

all air exhaust nozzles in the row feeding group are positioned on the one side furnace wall, and all air exhaust nozzles in the row feeding group are positioned on the other side furnace wall;

Or the one side furnace wall and the other side furnace wall are respectively provided with the suction nozzle and the air feeding nozzle, and the suction nozzles and the air feeding nozzles on the furnace wall on the same side are alternately arranged at intervals in the third direction;

or the number of the air flow discharging devices is multiple and the air supply nozzles of the same air flow discharging device are arranged along the first direction, one of the furnace walls is provided with the air suction nozzles, the other furnace wall is provided with the air suction nozzles, and the air suction nozzles and the air supply nozzles in two adjacent air flow discharging devices are alternately arranged at intervals in the first direction.

2. The continuous kiln of claim 1, wherein the oven wall is provided with a gas distributor at the connection to the gas delivery nozzle, the gas delivery nozzle being in communication with the gas cavity of the gas distributor.

3. Continuous kiln according to claim 1 or 2, characterized in that the furnace wall has suction openings at the connection to the suction nozzles, which suction openings are arranged in the third direction, which suction nozzles communicate with the suction openings.

4. A continuous kiln according to claim 3, wherein the suction opening is elongate.

5. A continuous kiln according to claim 3, comprising a sagger for holding material, the sagger having a cutout in its side wall, the cutout constituting a passage for the directed air flow through the sagger, the cutout being directed towards the suction opening and the delivery nozzle, respectively.

6. The continuous kiln of claim 5, wherein the mouth of the air delivery nozzle is proximate the gap.

7. Continuous kiln according to claim 1, characterized in that the kiln comprises a detection device comprising a furnace pressure sensor and/or a gas concentration sensor for detecting the kiln.

8. A continuous kiln according to claim 7, wherein the detection means comprises a pressure sensor and/or a flow sensor, one or both of the suction nozzle and the delivery nozzle being provided with the pressure sensor and/or flow sensor in a matched arrangement.

9. The continuous kiln of claim 7, wherein the gas flow control device comprises a gas feed valve matingly coupled to the gas feed nozzle and a gas discharge valve coupled to the gas discharge nozzle, and wherein the gas feed valve and the gas discharge valve are configured to be actuated in response to the detection device.

10. The continuous kiln of claim 9, wherein the airflow control device is configured to control the air delivery nozzle and the suction nozzle in a coordinated manner to control the amount of air and the amount of exhaust gas within the kiln in a coordinated manner.

11. The continuous kiln of claim 1, wherein, the continuous kiln includes a heater coupled to the kiln.

12. The continuous kiln of claim 11, wherein the heater is disposed along the third direction and is connected to a wall of the kiln.

13. The continuous kiln of claim 12, wherein the heaters are arranged in the third direction and a gas delivery nozzle or a gas extraction nozzle is disposed between two adjacent heaters.

14. A heat treatment method, carried out by the continuous kiln according to any one of claims 1 to 13, characterized in that it comprises:

Providing a temperature required for heat treatment in a furnace chamber of the kiln;

The object to be heat-treated or thermochemical treated is transported in the furnace chamber along the first direction by a loading tool, and during the transportation, gas is input into the furnace chamber through the gas flow feeding and discharging device under the control of the gas flow control device, and gas is synchronously discharged from the furnace chamber through the gas flow control device, so that the process atmosphere of the heat treatment in the furnace chamber is maintained.