WO2022116547A1

WO2022116547A1 - Continuous kiln and thermal treatment or thermal chemical processing method

Info

Publication number: WO2022116547A1
Application number: PCT/CN2021/106417
Authority: WO
Inventors: 王霞; 吴桢
Original assignee: 信诺先端热工科技(苏州)有限公司
Priority date: 2020-12-01
Filing date: 2021-07-15
Publication date: 2022-06-09
Also published as: EP4249840A1; EP4249840A4; KR20230093510A

Abstract

A continuous kiln and a thermal treatment or thermal chemical processing method, relating 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 work in conjunction to control an atmosphere in a furnace chamber of the kiln. Since air supply nozzles and air exhaust nozzles in the airflow supply and exhaust device are arranged opposite to each other, transverse airflow perpendicular to the length direction of the kiln can be formed, and the internal atmosphere can be kept stable.

Description

A continuous kiln and heat treatment or thermochemical treatment method

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of the Chinese patent application No. 2020113884985, entitled "A Continuous Kiln and Heat Treatment or Thermochemical Treatment Method", filed with the China Patent Office on December 1, 2020, and filed on December 1, 2020 The priority of the Chinese Patent Application No. 2020228595682, entitled "A Continuous Kiln", filed with the Chinese Patent Office, the entire contents of which are incorporated herein by reference.

technical field

The present 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 technique

Continuous kiln is one of the important equipments for the production of cathode materials for lithium ion batteries. The continuous kiln is a kind of kiln mainly made of refractory materials, thermal insulation materials and building materials, and is usually built into a tunnel structure with openings at both ends.

In the production process of cathode materials for lithium ion batteries, it is usually necessary to pass a specific gas (such as dry air, oxygen or nitrogen, etc.) into the continuous kiln to form the process atmosphere required for the thermal treatment or thermochemical treatment of cathode materials. This particular gas is called process gas. At the same time, when the cathode material is subjected to heat treatment or thermochemical treatment in the kiln, some gaseous by-products (which can be called exhaust gas) generated during the reaction process will be released, such as water vapor and carbon dioxide. In addition, the exhaust gas often contains some Residual corrosive gases. These waste gases need to be discharged from the kiln as soon as possible, otherwise the atmosphere control in the kiln will be seriously affected, resulting in the deterioration of the performance of the calcined cathode material.

SUMMARY OF THE INVENTION

In order to improve the problem of atmosphere control in the existing kiln, the purpose of this application is to propose a continuous kiln and a heat treatment or thermochemical treatment method.

This application is implemented like this:

The present application provides a continuous kiln, which includes a kiln, an airflow sending and discharging device, and an airflow control device.

The kiln has a furnace cavity extending along the first direction from the furnace head to the furnace tail. The airflow sending and exhausting device is configured to form a directional airflow in the furnace cavity that can flow in a second direction from one side of the furnace wall to the other side of the furnace wall of the kiln. In addition, the air supply and exhaust device has a supply and exhaust group, and the supply and exhaust group has an air supply nozzle and an air extraction nozzle that are connected to the furnace wall and are matched with each other. Orientation arrangement. The air flow control device is matched and connected with the air supply and exhaust device, so as to control the air supply nozzle and the air suction nozzle.

Optionally, the furnace wall is provided with a gas distributor where the air supply nozzle is connected, and the air supply nozzle communicates with the air cavity of the gas distributor.

In some possible implementations of the present application, the furnace wall has a suction port where the suction nozzle is connected, the suction port is arranged along the third direction, and the suction nozzle communicates with the suction port.

Optionally, the suction port is elongated.

Optionally, the cross section of the suction port is rectangular or oval. Optionally, the continuous kiln includes a saggar for containing materials, the side wall of the saggar has a gap, the gap constitutes a channel for the directional airflow to pass through the saggar, and the gap is respectively facing the suction port and the air supply nozzle.

Optionally, the mouth of the air nipple is close to the gap.

Optionally, the continuous kiln includes a detection device including a furnace pressure sensor and/or a gas concentration sensor for detecting the kiln.

Optionally, the detection device includes a pressure sensor and/or a flow sensor, and one or both of the air suction nozzle and the air supply nozzle are matched with a pressure sensor and/or a flow sensor.

Optionally, the detection device further includes a temperature sensor. Optionally, the air flow control device includes an air supply valve and an exhaust valve, the air supply valve is matched with the air supply nozzle, the exhaust valve is connected with the air extraction nozzle, and the air supply valve and the exhaust valve are configured to be operated in response to the detection device.

Optionally, the airflow control device is configured to be able to control the air supply nozzle and the air extraction nozzle in a linkage manner, so that the intake air volume and the exhaust air volume in the kiln can be controlled in linkage.

Optionally, both the air supply valve and the exhaust valve are proportional solenoid valves.

Optionally, all the air extraction nozzles in the multiple supply and exhaust groups are located on one side of the furnace wall, and all the air supply nozzles in the multiple supply and exhaust groups are located on the other side of the furnace wall;

Alternatively, air extraction nozzles and air supply nozzles are provided on one side of the furnace wall and the other side of the furnace wall, and in the third direction, the air extraction nozzles and air supply nozzles on the same side of the furnace wall are alternately arranged at intervals;

Alternatively, the number of air supply and exhaust devices is multiple and arranged along the first direction, the air supply nozzle of the same air supply and exhaust device is located in one of the furnace walls, the air suction nozzle is located in the other furnace wall, and in the first direction, The air suction nozzles and the air supply nozzles in the two adjacent air supply and discharge devices are alternately arranged at intervals. Optionally, the continuous kiln includes a heater connected to the kiln.

Optionally, the heater is arranged in the third direction and connected to the furnace wall of the kiln.

Optionally, an air supply nozzle or an air extraction nozzle is arranged between two adjacent heaters.

Optionally, heaters are connected to furnace walls on both sides of the kiln, and the number of heaters connected to the furnace walls on both sides is equal.

The present application provides a method for performing heat treatment or thermochemical treatment through the above-mentioned continuous kiln. The heat treatment or thermochemical treatment method comprises: heating a furnace cavity of a kiln to a temperature of the heat treatment or thermochemical treatment; conveying an object to be heat treated or thermochemically treated in the furnace cavity along a first direction by a loading tool, and conveying During the process, under the control of the airflow control device, the process gas is input into the furnace cavity through the airflow sending and exhausting device, and the gas is synchronously exhausted from the furnace cavity through the airflow control device, so as to maintain the process of heat treatment or thermochemical treatment in the furnace cavity atmosphere.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present application more clearly, the following drawings will briefly introduce the drawings that need to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the structural representation of the kiln body in the continuous kiln of the application;

FIG. 2 shows a schematic structural diagram of the continuous kiln in the present application from a first perspective;

FIG. 3 shows a schematic structural diagram of the continuous kiln in the present application from a second perspective;

Fig. 4 shows the structural schematic diagram of the sagger used in the continuous kiln in the present application;

FIG. 5 shows a schematic structural diagram of an air supply nozzle with a cutout in the present application;

FIG. 6 shows a flow chart of a method of thermal treatment or thermochemical treatment in the present application.

FIG. 7 shows a schematic diagram of the positions of the various detection devices in the present application arranged in the continuous kiln.

Reference numerals: 101-kiln; 1011-furnace head; 1012-furnace tail; 1013-furnace cavity; 1014-furnace wall; 1015-furnace roof; 1016-furnace bottom; 11-heater; -Injection device; 203-Exhaust device; 31-Gas distributor; 2-Saggar; 38-Gap; 39-Suction port; 40-Exhaust valve; 42-Air supply valve; 18-Process gas; 37-Suction Gas nozzle; 44-exhaust gas; 55-temperature sensor; 65-pressure sensor; 66-flow sensor; 88-furnace pressure sensor; 89-gas concentration sensor.

Detailed ways

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

In the production process, the heat treatment or thermochemical treatment, especially the high temperature calcination treatment, for the cathode material is the core step that determines the properties of the material. Moreover, during the calcination process, many cathode materials need to pass a specific process gas into the calcined kiln to maintain a special atmosphere, and the special atmosphere also needs to be strictly controlled. For example, ternary cathode materials such as high nickel ternary materials need to be fed with oxygen; for cathode materials such as lithium iron phosphate, nitrogen needs to be fed. For this type of cathode material that requires a special atmosphere during calcination, the atmosphere control during calcination is very important, because it will affect the performance of the cathode material after calcination, so cathode material manufacturers and related researchers have been striving to improve The atmosphere control ability that the kiln should have when the cathode material is calcined.

At present, the calcination of cathode materials is generally realized by continuous kilns (also referred to as continuous kilns), such as pusher type tunnel kilns (referred to as pusher kilns) and roller tunnel kilns (referred to as roller kilns), both of which are continuous The way the kiln is realized. The so-called tunnel kiln is a kiln with a tunnel structure with openings at both ends, which is made of refractory materials, thermal insulation materials and building materials. Depending on the temperature and function, the tunnel kiln is generally divided into sections to form a heating zone, a heat preservation zone and a cooling zone. In the tunnel kiln, the kiln body is heated by means of electric heater or fuel injection (such as natural gas, heavy oil, etc.). The material to be heat treated or thermochemically treated or the carrier (such as a saggar) carrying the material is loaded by the carrier, and enters the tunnel kiln from one end (kiln head) of the tunnel, and moves through the heating zone, the heat preservation zone and the cooling zone successively. The other end (kiln tail) of the tunnel kiln exits the kiln to complete the heat treatment.

However, through practice, the inventors of the present application have found that the existing kilns all have defects to varying degrees, so that the calcination of the cathode material cannot meet the requirements.

After analysis, the inventor believes that the above problems are mainly caused by the following reasons:

During the calcination process, the positive electrode material and the process gas participate in the reaction, and two key conditions are required to promote the reaction: (1) the process gas is fully contacted with the calcined material; (2) a large amount of process gas flows over the surface of the material to The gaseous by-products produced by the reaction are taken away as soon as possible. However, the existing continuous kilns used for calcining cathode materials cannot meet at least one of these two key conditions. For example, the intake and exhaust systems of push-plate kilns or roller kilns cannot fully meet the above conditions.

For ease of understanding, taking the positive electrode material of lithium ion battery as an example, the positive electrode material of lithium ion battery generally exists in the form of powder before calcination, and when the powder material is calcined in a kiln, it is usually necessary to put the powder material to be calcined into a box such as a box. In order to improve the production capacity of the kiln, the saggars that carry the materials usually need to be placed on the carrier in a stacked manner, which will seriously affect the delivery and discharge of the airflow, and cannot make the process gas and the stacking saggers in the sagger. The powder material is in sufficient contact, and it is not possible for a large amount of process gas to flow over the surface of the powder material in the stacking saggar. For ease of understanding, detailed explanations are as follows:

Taking the existing typical technology of air intake from the bottom and side walls of the kiln, and exhaust from the kiln top as an example, the process gas entering from the air inlet of the kiln side wall will be attracted by the negative pressure of the kiln top exhaust port. , flows upward, and exits the kiln from the exhaust port on the top of the kiln.

The process gas entering the bottom air inlet is blocked by the bottom of the lower saggar, and most of it can only flow along the periphery of the saggar and merge into the main airflow that flows upward; a small part passes through the gap between the saggars and flows upward. into the exhaust port.

The materials in the upper saggar can have relatively sufficient contact with the process gas because there is no obstruction on the top of the saggar, and the waste gas released by the materials in the upper saggar can also be relatively smoothly discharged from the top exhaust port along with the main air flow.

However, because the lower saggar is blocked by the upper saggar, the process gas cannot enter smoothly, and the waste gas released by the calcination of the material cannot be smoothly taken away by the upward flowing airflow. The gas exchange inside and outside the lower saggar is mainly completed by diffusion, that is, a small part of the process gas around the lower saggar enters the saggar through the gap at the edge of the lower saggar through diffusion. Similarly, the waste gas released from the calcination of the material in the lower saggar also escapes from the saggar through the gap on the edge of the saggar by diffusion, and then collects to the top of the kiln with the airflow around the saggar, and is discharged from the exhaust port.

From the above, in the existing typical technology, the air intake from the bottom and side walls of the kiln, and the exhaust from the kiln top cannot solve the problems such as the obstruction of the exhaust of the lower saggar material and the insufficient contact with the fresh process gas. In the typical technology, the air intake from the top of the kiln and the exhaust from the bottom cannot solve the problems such as the obstruction of the exhaust of the material in the lower saggar and the insufficient contact with the fresh process gas.

In short, in the case of stacking saggars, since the upper saggar blocks the lower saggar, whether the process gas enters the lower saggar or the exhaust gas escapes from the lower saggar, it mainly depends on the diffusion effect. Therefore, the gas exchange efficiency inside and outside the lower saggar is very low. Moreover, the diffusion directions of the two gases are opposite, which weakens the gas exchange, so that the concentration of the process gas in the lower saggar is much lower than that of the upper saggar, and the accumulation of exhaust gas in the lower saggar is much higher than that of the upper saggar. Saggar.

The above phenomenon makes the atmosphere in contact with the material in the upper and lower saggars very different, which further causes the performance of the positive electrode material in the upper and lower saggars after calcination to be very different. Consistency deteriorates. To make matters worse, in order to reduce costs, manufacturers of cathode materials usually stack more saggars in the kiln, and as the number of layers of saggars stacked increases, the aforementioned problems become more serious.

In addition, because the air pressure at the air inlet of the kiln is not high, after the process gas enters the larger space in the kiln body from the air inlet, the airflow speed will be greatly slowed down, which hinders the discharge of exhaust gas and the uniform distribution of process gas. However, if the intake pressure is too high, it may cause excessive disturbance to the positive electrode material powder, causing it to fly up, making it inconvenient for normal transportation.

In view of the above situation, the inventor proposes to form an orderly and highly directional airflow in the kiln, so that the positive electrode active material can be fully contacted with the process gas, so as to fully react, and at the same time, the reaction can be timely The generated exhaust gas is discharged to suppress the adverse effect of the exhaust gas on the reaction.

In order to achieve the above effects, in the present application, the inventor proposes a continuous kiln. In some implementations, the continuous kiln mainly includes three major components: the kiln, the airflow sending and discharging device, and the airflow control device, which will be described in detail below.

(1) Kiln

The structure of the kiln 101 is shown in FIG. 1 , which has a furnace wall 1014 , a furnace bottom 1016 and a furnace top 1015 . In particular, in order to facilitate the control, reduction, and ineffective consumption of the process gas 18 therein, the internal section of the kiln 101 can be designed to be thin and tall, and the furnace top 1015 inside the kiln 101 (the arc at the top in FIG. 2 ) The free space (the space without the saggar 2) occupies a small proportion (the area of the furnace cavity in the arc top area is smaller than the area of the furnace cavity in the furnace wall area).

The flow direction of the process gas 18 in the continuous kiln of the present application is shown in FIGS. 2 and 3 . For the convenience of explanation and understanding, the kiln 101 is defined in three directions, namely a first direction, a second direction and a third direction. Specifically, the direction from the furnace head 1011 to the furnace tail 1012 is defined as the first direction, as shown in the direction B in FIG. 1 (or the length direction); it is defined by the direction from one furnace wall 1014 to the other furnace wall 1014 is the second direction, as shown in the direction C in FIG. 1 (or called the width direction); the direction from the furnace top 1015 to the furnace bottom 1016 is defined as the third direction, as shown in the direction A in FIG. 1 (or called the height direction) direction).

The kiln 101 constitutes the main structure of the continuous kiln, and operations such as heat treatment or thermochemical treatment are also mainly performed in the kiln 101 . The furnace 101 has a furnace cavity 1013 bounded by furnace walls 1014 as a location for providing thermal or thermochemical treatment. In the actual use process, the heat treatment or thermochemical treatment material enters from the furnace head 1011 of the kiln 101, and proceeds to different sections of the furnace cavity 1013 in sequence (for example, the sequentially distributed heating section, heat preservation section, and cooling section), and finally from its furnace Tail 1012 left. It should be noted that the furnace 101 usually needs to maintain a certain degree of airtightness and sealing as a place for providing heat treatment or thermochemical treatment. Therefore, the furnace head 1011 and the furnace tail 1012 usually need to be selectively opened and closed. At the same time, the kiln 101 can also be airtightly constructed through the outer casing. This is not illustrated in this application. Those skilled in the art can understand that the above-mentioned devices such as gates and housings can be provided in the prior art, which are briefly described in this application in order to avoid unnecessary repetition.

In order to perform the heating operation, the furnace 101 usually needs to be equipped with heating equipment. As previously mentioned, the heating device may directly heat selected locations within the kiln 101 by injecting fuel. However, the foreign matter that may be introduced and the influence on the calcination reaction are considered. Generally, the heater 11 is selected to be used, and the heater 11 can be an electric heater, for example, an electric heater such as a heating rod is used for electric heating, and the heater 11 can also be used for combustion heating, such as a radiant tube with heat. The heater may be a specific product such as a resistance heater, which is not limited here.

In the present application, the continuous kiln is provided with a heater 11 , and the heater 11 is connected to the kiln 101 . Alternatively, the heater 11 may be inserted into the furnace cavity 1013 from the furnace roof 1015 , or the heater 11 may be inserted into the furnace cavity 1013 through the furnace bottom 1016 or the furnace wall 1014 . Considering that the heater 11 may hinder the material to be calcined conveyed in the furnace cavity 1013, in the present application, the heater 11 is inserted and fixed near the furnace wall 1014, and is along the direction A from the furnace top 1015 to the furnace bottom 1016 For mating, see Figures 1 and 3.

In the disclosure of FIG. 3 , heaters 11 are provided on furnace walls 1014 on both sides of the furnace 101 . The number of heaters 11 on the furnace walls 1014 on both sides is equal, and they are opposite in the direction C one by one. 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, the installation position and manner of the heater 11 may also have other options, which are not specifically limited in this application.

In addition, according to different needs, the kiln 101 can also be selectively configured with various appropriate devices and equipment such as detection devices, which can be flexibly set according to the actual situation.

For example, in different usage modes, if other atmospheres need to be provided in the furnace cavity 1013 of the kiln 101, other gas supply pipeline equipment can also be selected.

For another example, in order to monitor the temperature in the furnace cavity 1013 of the kiln 101 so as to adjust the temperature in a timely manner, a temperature detection device such as a temperature sensor 55 can also be provided in the kiln 101, for example, an infrared temperature detector can be specifically used. Wait.

Since the process gas 18 needs to be provided for material calcination in the furnace cavity 1013, a detection device may also be provided in the furnace 101 corresponding to this. The detection device may be an air pressure detector, a concentration detector, or both. The gas pressure detector may be a furnace pressure sensor 88 for detecting the furnace 101 ; the concentration detector may be a gas concentration sensor 89 for detecting the concentration of the process gas 18 (eg oxygen) in the furnace 101 .

In addition, the continuous kiln can also be equipped with equipment for containing and conveying calcined materials (such as cathode materials), such as a sagger 2, as shown in FIG. 4 . In order to facilitate the air flow through the saggar 2, the side wall of the saggar 2 is provided with a gap 38. Therefore, when a plurality of saggars 2 are stacked, the openings 38 of different saggars 2 can constitute passages for directional airflow through the saggars 2 . The notch 38 provided in the saggar 2 facilitates the flow of the air flow, so that the air flow can more easily take away the exhaust gas and reduce the turbulent flow of the air flow.

(2) Air supply and discharge device

In the present application, the airflow sending and discharging device mainly includes an airflow input part and an airflow discharge part. Moreover, the two parts cooperate with each other to form a continuous and directional airflow in the furnace 101 . The “orientation” refers to the direction C that intersects with the direction B of the kiln 101 (eg, crosses vertically and horizontally), that is, the direction from one side of the furnace wall 1014 of the kiln 101 to the other side of the furnace wall 1014 . In other words, during the longitudinal conveying process of the calcined material from the kiln head to the kiln tail in the furnace cavity 1013, a transverse airflow can be formed by the airflow sending and exhausting device.

Wherein, the airflow input part is used to transport the process gas 18 into the furnace cavity 1013 of the kiln 101 for the reaction needs in the calcination process. The airflow discharge part therein is used to discharge the exhaust gas 44 in the furnace cavity 1013 of the kiln 101 to the outside of the kiln 101 .

By using the airflow sending and exhausting device, the atmosphere in the furnace cavity 1013 of the kiln 101 can be renewed, for example, fresh process gas 18 can be added, and the exhaust gas 44 can be discharged at the same time. In addition, by controlling the conveying state of the air flow such as flow rate, flow rate, etc., the temperature in the furnace cavity 1013 can also be controlled to a certain extent. Since the exhaust gas 44 can carry away some of the heat, the freshly input process gas 18 can also absorb some of the heat.

The airflow sending and discharging device has a sending and discharging group. The supply and discharge group includes any number of air supply nozzles 32 and air extraction nozzles 37 . In addition, the air supply nozzle 32 and the air extraction nozzle 37 are spaced apart from each other and opposite to each other, and the air supply nozzle 32 and the air extraction nozzle 37 are both connected to the furnace wall 1014. Therefore, the space between the two is the furnace cavity 1013 for conveyance. Channels for calcined material.

The air supply nozzles 32 and the air extraction nozzles 37 in the sending and discharging group are arranged along the third direction from the furnace top 1015 to the furnace bottom 1016 of the kiln 101 . That is, the air supply nozzle 32 and the air extraction nozzle 37 are arranged along the height direction of the kiln. Therefore, when a calcined object with a large height is placed in the furnace cavity 1013 of the kiln 101, the air supply nozzle 32 and the air suction nozzle 37 are arranged along the third direction to effectively cover the calcined object, so that it is uniformly affected by the directional airflow and influence. As an improved solution, the notch 38 of the saggar 2 for holding the calcined material faces the air supply nozzle 32 . Further, the mouth (gas outlet) of the air supply nozzle 32 is close to the gap 38 (as long as the normal transportation of the saggar is not hindered), so that it is easier to accurately deliver the gas to the saggar 2 .

FIG. 2 is a schematic cross-sectional structure diagram of a continuous kiln, wherein a supply and discharge group is shown, which includes 8 air supply nozzles 32 and 3 air extraction nozzles 37 . Optionally, the number of the air supply nozzles 32 and the air extraction nozzles 37 in one supply and exhaust group may also be equal, or the number of the air supply nozzles 32 is smaller than the number of the air extraction nozzles 37 . In other words, the air supply nozzles 32 and the air suction nozzles 37 may also be arranged in a one-to-one arrangement, and may also be arranged in a one-to-many or many-to-one arrangement, which is not limited herein.

The above description is given by taking the continuous kiln only having one airflow sending and discharging device as an example. Of course, the continuous kiln can also have a plurality of air-flow sending and discharging devices, optionally, when the continuous kiln has multiple air-flow sending and discharging devices, it has a plurality of sending and discharging groups correspondingly. Therefore, in the case of having a plurality of sending and discharging groups, all the sending and discharging groups can be arranged along the length direction of the kiln 101, as shown in FIG. 3, for example.

The above-mentioned Figures 2 and 3 only disclose one arrangement of the delivery and discharge groups in the present application. Optionally, the delivery and discharge groups may also have other arrangements. The two cases are used as examples to describe in detail as follows:

Case 1. In the direction A of the kiln 101, in a supply and exhaust group, all the air supply nozzles 32 are arranged in one of the furnace walls 1014, and all the air extraction nozzles 37 are arranged in the other furnace wall 1014.

Case 2: In the direction A of the kiln 101 , in a supply and exhaust group, part of the air supply nozzles 32 are arranged in one of the furnace walls 1014 , and the remaining part of the air supply nozzles 32 are located in the other furnace wall 1014 . Correspondingly, in the sending and discharging group, some of the air extraction nozzles 37 are arranged in one of the furnace walls 1014 , and the remaining air extraction nozzles 37 are arranged in the other furnace wall 1014 .

For a continuous kiln with only one gas supply and exhaust device (correspondingly with one supply and exhaust group), the air supply nozzle 32 and the air extraction nozzle 37 can be arbitrarily selected to be structured in the manner of the above-mentioned case 1 or case 2.

For a continuous kiln with multiple (eg, two or more) airflow feed and discharge devices (correspondingly with multiple feed and discharge groups), all feed and discharge groups are arranged along the direction B of the kiln 101 . Moreover, the air supply nozzles 32 and the air suction nozzles 37 in each delivery and discharge group can be arranged in the way of case 1, or they can be arranged in the way of case 2, or all the supply and discharge groups can be arranged in the way of case 1 and case 1. The second case is arranged in a combined manner.

In the illustrated solution of the present application, there are multiple supply and discharge groups, and the air supply nozzles 32 and the air extraction nozzles 37 are arranged in a combination of the above-mentioned cases 1 and 2. In particular, two adjacent supply and exhaust groups on the same side furnace wall 1014 are arranged in an alternate manner with the air supply nozzles 32 and the air extraction nozzles 37 . In this way, when more than one row (two rows are shown in FIG. 3 ) of saggars 2 are stacked on the carrier of the calcined material in the kiln 101 to pass through the kiln, the saggars 2 on each side have There is an equal chance of facing the gas injection device 202 or the exhaust device 203 , ie the vehicle is equally likely to face the air supply nozzle 32 and the air extraction nozzle 37 . In this way, the consistency of calcination of materials in different rows of saggars 2 can be improved, so that each saggar 2 will have air flow alternately passing from both sides. To ensure better consistency, the saggars 2 in this application are stacked in two columns, as shown in FIG. 3 .

The different structural modes of the air supply and discharge device can meet the different realization forms of the continuous kiln, and can also achieve different degrees of renewal and temperature adjustment effects on the atmosphere in the furnace cavity.

When considering the arrangement of the air supply nozzles 32 and the air extraction nozzles 37 , the position and structure of the heater 11 in the kiln can also be adjusted in a targeted manner. For example, an air supply nozzle 32 or an air extraction nozzle 37 is provided between two adjacent heaters 11 . That is, for multiple supply and exhaust groups, the air supply nozzles 32 and the air extraction nozzles 37 of two adjacent supply and exhaust groups are alternately arranged. Correspondingly, the air supply nozzles 32 or the air extraction nozzles 37 are alternately "clamped" between the two heaters 11 . The alternation mode can be one heater 11 , one air supply nozzle 32 , one heater 11 , one air supply nozzle 32 one spaced apart, or two heaters 11 , two air supply nozzles 32 , two There are two heaters 11, two air nozzles 32, and so on. Through the above arrangement, when the process gas 18 is sprayed, the gas can be prevented from being directly sprayed onto the adjacent heater 11 to affect the heating power of the heater 11 , and the process gas 18 can be sufficiently preheated again.

The arrangement of the sending and discharging groups has been described above, and the specific structures of the air supply nozzles and the air suction nozzles therein will be described in detail below.

Optionally, the air supply nozzle 32 is constructed as a cylindrical hollow tube. And one end is inserted into the furnace wall 1014 , and the other end extends into the furnace cavity 1013 . The air supply nozzle 32 can be used as an air flow channel through the pipeline buried in the furnace wall 1014, so as to convey the process gas 18 through the blower; wherein, the pipeline can be hollow refractory bricks spliced together, or a ceramic tube, or a refractory tube. High temperature metal tube and the metal tube is lined with ceramic, which is not limited here. Optionally, the air supply nozzle 32 can also be placed outside the furnace 101, and the injection pipe connected to the air supply nozzle 32 can be inserted into the furnace through the hole on the furnace wall 1014; Instead of the injection pipe, the gas is injected through the holes on the furnace wall 1014 from the gas supply nozzle 32 outside the furnace. Alternatively, the kiln is stacked with hollow bricks, and then the hollow bricks are provided with air holes communicating with the furnace cavity 1013, and gas is injected through the air holes.

When the number of air supply nozzles 32 is large, setting up an independent pipeline for each air supply nozzle 32 may result in complicated process and structure. Therefore, a cavity is selected to be reserved in the furnace wall 1014, which can be directly supplied with pipelines. The air supply nozzle 32 can also be directly communicated with the cavity. Functionally, the cavity essentially constitutes a gas distributor 31 . In other words, the furnace wall 1014 is provided with the gas distributor 31 where the air supply nozzle 32 is connected, and the air supply nozzle 32 communicates with the air cavity of the gas distributor 31 . A heating plate may also be provided in the gas distributor 31 for heating the process gas 18 entering therein, so as to prevent the cold process gas 18 from directly entering the furnace cavity 1013 . Of course, the process gas 18 can also be preheated outside the continuous kiln, and then introduced into the gas distributor 31 , and then injected into the furnace cavity 1013 through the gas supply nozzle 32 . The gas distributor 31 can achieve the effect of simplifying the gas delivery structure, and at the same time, can reduce the control difficulty of the gas flow control device.

In addition, as an improved solution, the structure of the air supply nozzle 32 in the form of a hollow tube can also be improved and matched with the gas distributor 31 . For example, optionally, one end of the air supply nozzle 32 extending into the gas distributor 31 is provided with a notch, thereby forming an "L" end structure. In addition, the incident direction of the process gas 18 entering the gas distributor 31 is away from the notch of the air supply nozzle 32 and is opposite to each other, as shown in FIG. 5 . Therefore, the time for the process gas 18 in the gas distributor 31 to enter the nozzle can be delayed, so that the process gas 18 can obtain a longer heating time in the distributor and improve the heating effect.

Similarly, the air extraction nozzle 37 can also be designed for hollow pipes. The air extraction nozzle 37 may also be provided with a groove structure in the furnace wall 1014 for the air extraction pipeline to discharge the exhaust gas 44 from the furnace cavity 1013 . In the present application, the furnace wall 1014 is provided with a suction port 39 at the suction nozzle 37 , and obviously, the suction nozzle 37 communicates with the suction port 39 . And the suction port 39 is arranged along the third direction (ie, the depth direction of the furnace cavity 1013). Optionally, the suction port 39 is elongated, for example, the suction port 39 may have a rectangular cross-section or an elliptical cross-section. The long and narrow suction port 39 can provide a larger area for gas suction, corresponding to more suction nozzles 37, thereby further improving the uniformity of suction and exhaust to various positions. When the furnace wall 1014 is provided with the suction port 39 , one end of the suction nozzle 37 can be inserted into the suction port 39 , and the other end of the suction nozzle 37 can be extended out of the furnace 101 .

In addition, as a power source for supplying gas to the air supply nozzle 32 and the air extraction nozzle 37, the air supply and exhaust device can also be equipped with one or more of the equipment such as exhaust fan, blower, exhaust fan, and air pump. In the present application, corresponding to the air supply nozzle 32 , the continuous kiln is equipped with an injection device 202 ; corresponding to the air suction nozzle 37 , the continuous kiln is equipped with an exhaust device 203 .

(3) Airflow control device

The air flow control device is a device that works in conjunction with the air supply and exhaust device, and can control the air supply nozzle 32 and the air extraction nozzle 37 and make the air supply nozzle 32 and the air extraction nozzle 37 work in a matched manner at the same time. That is, the operating state of the air supply nozzle 32 is associated with the operating state of the air extraction nozzle 37 . When the working state of the air supply nozzle 32 is adjusted, the state of the air extraction nozzle 37 is also adjusted correspondingly. By adjusting the air flow control device, the intake air volume of the air supply nozzle 32 can be matched with the exhaust air volume of the air suction nozzle 37, for example, the intake air volume can be made equal to the exhaust air volume.

In other words, optionally, the air flow control device may control the air supply nozzle 32 and the air extraction nozzle 37 in linkage. Of course, optionally, the air flow control device can also independently control the air supply nozzle and the air exhaust nozzle. For example, when an automatic control in the linkage mechanism fails, or the automatic control adjustment range cannot meet the actual needs, or in some special cases, it needs to be changed to manual operation, the system related to the airflow control device can be programmed Switch the automatic control to manual mode, rely on field instruments (such as flow meters, differential pressure gauges and pressure transmitters) to manually adjust the intake control valve and manually adjust the exhaust control valve based on the detection values of the field instruments, so as to achieve The gas balance in the furnace, in practical application, whether the gas balance is judged by the display of the oxygen partial pressure value.

By controlling the intake air volume and the exhaust air volume, the intake air volume and the exhaust volume can be matched, which can make the formed directional airflow more stable. In addition, doing so can not only effectively avoid the problem that excessive flue gas will take away a large amount of heat in the kiln 101 and cause energy damage due to the relatively large exhaust gas volume, but also can effectively avoid the problem that the exhaust gas volume is relatively too small. This results in the problem that the residual amount of the waste gas 44 in the kiln 101 is too high.

Optionally, the airflow control device includes an air supply valve 42 (which may be an automatic control valve, which may have a handle with manual adjustment) and an exhaust valve 40 (which may be an automatic control corrosion resistant high temperature valve, which may have a handle with manual adjustment).

Wherein, the air supply valve 42 is matched and connected with the air supply nozzle 32 , and the exhaust valve 40 is connected with the air extraction nozzle 37 . The control of the delivery state of the process gas 18 and the delivery state of the exhaust gas 44 can be achieved by adjusting the opening degrees of the two valves. Valves can use various butterfly valves, ball valves, regulating valves, throttle valves, etc., which will not be carried out here. In order to improve the accuracy of control and the convenience of operation, the exhaust valve 40 and the supply valve 42 can optionally use proportional solenoid valves.

Further, the continuous kiln may also be provided with a detection device such that the air supply valve 42 and the exhaust valve 40 are configured to be actuated in response to the detection device. In other words, according to the working condition of the continuous kiln detected by the detection device, the air supply valve 42 and the exhaust valve 40 are adjusted accordingly, so as to realize the operation of the air supply nozzle 32 and the air extraction nozzle 37 .

The detection device therein may include a pressure sensor 65 and/or a flow sensor 66 . Alternatively, pressure sensor 65 and flow sensor 66 may be connected in the air supply line system upstream of air supply nozzle 32 . Alternatively, the pressure sensor 65 and the flow sensor 66 can also be connected in the suction line system and located downstream of the suction nozzle 37 .

In addition, corresponding to the furnace 101, the furnace pressure sensor 88 and the gas concentration sensor 89 of the process gas 18 provided therein can also be used as components of the detection device. The furnace pressure sensor 88 and the gas concentration sensor 89 can respectively reflect the pressure and atmosphere concentration in the furnace cavity of the kiln, so as to facilitate the user to detect the atmosphere in the furnace cavity. The pressure sensor 65 and the flow sensor 66 can reflect the working conditions of the air supply nozzle 32 and the air extraction nozzle 37 as well as the air flow into the furnace cavity 1013 and the air flow out of the furnace cavity 1013 , so as to control the atmosphere in the furnace cavity 1013 More effective and efficient. Therefore, various states of the injected gas, the exhaust gas and the gas in the furnace cavity 1013 of the kiln 101 can be truly reflected by the detection device, so that the operation of the airflow control device can be more accurate.

Based on the need to improve the automation of control, the controller can be selected to control the air supply valve 42 and the exhaust valve 40, and the detection device and the controller are matched and connected, so that the collection, processing and control information sending of detection information cooperate with each other. The controller can be various electronic components or a collection thereof capable of storing and processing certain data. For example, Central Processing Unit (CPU), Micro Control Unit (MCU), Programmable Logic Controller (PLC), Programmable Automation Controller (PAC), Industrial Control Computer (IPC), Field-Programmable Gate Array (Field-Programmable Gate Array) Gate Array, FPGA), application-specific integrated circuit chips (ASIC chips, Application Specific Integrated Circuit), etc. Through such structural design, the continuous kiln can realize closed-loop operation of gas injection and discharge.

For ease of understanding, an exemplary overview of how the controller works is as follows:

First, the partial pressure data of the process gas 18 in the furnace cavity 1013 is collected by the furnace pressure sensor 88 and the gas concentration sensor 89 . The intake air flow sets a target intake air amount, and the actual intake air amount is adjusted based on the target intake air amount. At the same time, the controller also uses the flow data of the air supply valve 42 as a parameter to calculate the target opening degree of the exhaust valve 40 of the exhaust system, and adjust the exhaust volume of the exhaust system based on the target opening degree, so as to realize the exhaust volume Linkage control with intake air volume.

When the partial pressure of the process gas 18 is lower than a certain percentage of the set value, the opening of the air supply valve 42 is increased, and the opening of the exhaust control valve is increased; when the partial pressure of the process gas 18 is higher than a certain percentage of the set value, the The gas flow control valve is closed and the opening of the exhaust control valve becomes smaller; when the partial pressure of the process gas 18 is maintained within a certain percentage of the set value, the intake flow control valve and the exhaust control valve remain unchanged. In addition, in order to make this feedback system run smoothly and avoid unstable situations where the action is too large or too slow, the furnace pressure in the furnace cavity 1013 of the kiln 101 can be used as an intermediate equilibrium constant, and any adjustment needs to be The furnace pressure is maintained within the set fluctuation range.

To sum up, the continuous kiln proposed in the present application can achieve a better use effect, so that the concentration of the process gas 18 in the kiln is evenly distributed, so that the calcined material can be in contact with the process gas 18 evenly and consistently, thereby improving the performance of the calcined product. consistency.

As an application, the present application also proposes a method for heat treatment or thermochemical treatment, see the flowchart of a method for heat treatment or thermochemical treatment shown in FIG. 6 , which mainly includes the following steps S100 and S200:

Step S100, providing a temperature for heat treatment or thermochemical treatment in the furnace cavity of the kiln.

Here, the temperature of the heat treatment or thermochemical treatment can be provided by the heater 11 provided in the kiln 101 of the continuous kiln. For different temperature sections (heating section, heating section, cooling section, etc.) of the kiln 101, the number and position of the heaters 11 in the working state can be adjusted adaptively.

Step S200, convey the object to be heat-treated or thermochemically treated in the furnace cavity along the first direction by the loading tool, and during the conveying process, input process gas, And synchronously, the gas is exhausted from the furnace cavity through the gas flow control device, so as to maintain the process atmosphere required for the heat treatment or thermochemical treatment in the furnace cavity.

Among them, the loading tools such as the saggar 2 are transported by means of transportation such as roller tables, push plates or kiln cars. In order to increase the output and take into account the utilization of the process gas 18, the saggars 2 on the transportation means are arranged in two rows, and each row is arranged in a manner of eight layers. The kiln car transports the sagger 2 from the kiln head through the heating zone, the heat preservation zone and the cooling zone. During this process, the process gas 18 can be continuously injected and the waste gas 44 can also be continuously discharged until the saggar 2 is discharged from the kiln end. The kiln completes the process of calcination.

The continuous kiln proposed in the present application can increase the concentration of the calcined material in the lower sagger 2 in contact with the process gas 18 for the heat treatment or thermochemical treatment when the sagger 2 is stacked with a relatively high number of layers, and can reduce the number of lower saggers. The accumulation of the waste gas 44 of the bowl 2 ensures the consistency of the atmosphere in the upper and lower saggars 2, and the consistency of the product properties after calcination is also improved. In addition, the stability of the directional airflow is enhanced by the optional linkage control of the intake air volume and the exhaust air volume; by staggered arrangement of the gas injection device 202 and the exhaust device 203 on each side of the kiln wall, the stacking of multiple columns is ensured When the sag 2 is used, the outermost sag 2 can face the gas injection device 202 and the exhaust device 203 with equal probability, which also improves the consistency of the atmosphere in the sag 2 on both sides.

It should be noted that, although in this application, the continuous kiln is proposed as a cathode material for producing lithium ion batteries by calcination, this does not mean that the application is intended to limit its use only here. Optionally, the continuous kiln can also be used to fire its ceramic materials or other alloy materials and so on.

The above descriptions are only examples of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Industrial Applicability:

The continuous kiln and heat treatment or thermochemical treatment method of the present application can make the concentration of the process gas in the continuous kiln evenly distributed, so that the calcined material can contact the process gas uniformly and uniformly, thereby improving the consistency of product performance after calcination.

Claims

A continuous kiln is characterized in that, comprises:

A kiln, which has a furnace cavity extending along the first direction from the furnace head to the furnace tail;

an airflow sending and exhausting device, configured to form a directional airflow in the furnace cavity that can flow along a second direction from one side of the furnace wall to the other side of the furnace wall, the airflow sending and exhausting device has a sending and exhausting group , the supply and discharge group has an air supply nozzle and an air extraction nozzle that are connected to the furnace wall and are matched to each other, and the air supply nozzle and the air extraction nozzle are arranged along the third direction from the furnace top to the furnace bottom of the kiln ;

The airflow control device is matched and connected with the airflow sending and discharging device, so that the air supply nozzle and the air suction nozzle can be controlled.
The continuous kiln according to claim 1, wherein the furnace wall is provided with a gas distributor where the air supply nozzle is connected, and the air supply nozzle communicates with the air cavity of the gas distributor.
The continuous kiln according to claim 1 or 2, wherein the furnace wall has a suction port where the suction nozzle is connected, the suction port is arranged along the third direction, and the suction port is arranged along the third direction. A mouth communicates with the suction port.
The continuous kiln according to claim 3, wherein the suction port is elongated.
The continuous kiln according to claim 4, wherein the cross section of the suction port is rectangular or oval.
The continuous kiln according to any one of claims 3 to 5, wherein the continuous kiln comprises a saggar for containing materials, the side wall of the saggar has a gap, and the gap constitutes the directional airflow After passing through the channel of the saggar, the notch faces the suction port and the air supply nozzle respectively.
The continuous kiln according to claim 6, wherein the mouth of the air supply nozzle is close to the gap.
The continuous kiln according to claim 1, characterized in that, the continuous kiln includes a detection device, and the detection device includes a furnace pressure sensor and/or a gas concentration sensor for detecting the kiln.
The continuous kiln according to claim 8, wherein the detection device comprises a pressure sensor and/or a flow sensor, and one or both of the air suction nozzle and the air supply nozzle are matched with the Pressure sensor and/or flow sensor.
The continuous kiln according to claim 9, wherein the detection device further comprises a temperature sensor.
The continuous kiln according to any one of claims 8 to 10, wherein the air flow control device comprises an air supply valve and an exhaust valve, the air supply valve is matched and connected to the air supply nozzle, and the exhaust valve is connected to the air supply nozzle. The air extraction nozzle is connected, and the air supply valve and the air exhaust valve are configured to be actuated in response to the detection device.
The continuous kiln according to claim 11, wherein the air flow control device is configured to be able to control the air supply nozzle and the air extraction nozzle in linkage, so as to control the intake air volume and exhaust air in the kiln in linkage quantity.
The continuous kiln according to claim 11 or 12, wherein the air supply valve and the exhaust valve are proportional solenoid valves.
The continuous kiln according to any one of claims 1 to 13, characterized in that, all the air suction nozzles in the supply and discharge group are located on the one side furnace wall, and all the air supply nozzles in the supply and exhaust group are located in the on the other side of the furnace wall;

Alternatively, both the one side furnace wall and the other side furnace wall are provided with the air extraction nozzle and the air supply nozzle, and in the third direction, the air extraction nozzle and the air supply nozzle on the same side furnace wall are The air supply nozzles are alternately arranged at intervals;

Alternatively, the number of the air supply and exhaust devices is multiple and arranged along the first direction, the air supply nozzle of the same air supply and exhaust device is located in one of the furnace walls, the air suction nozzle is located in the other furnace wall, and In the first direction, the air suction nozzles and the air supply nozzles in the two adjacent air supply and discharge devices are alternately arranged at intervals.
The continuous kiln according to any one of claims 1 to 14, wherein the continuous kiln includes a heater connected to the kiln.
16. The continuous kiln of claim 15, wherein the heater is arranged along the third direction and is connected to a furnace wall of the kiln.
The continuous kiln according to claim 16, wherein an air supply nozzle or an air extraction nozzle is arranged between two adjacent heaters.
The continuous kiln according to claim 16 or 17, wherein the heaters are connected to the furnace walls on both sides of the kiln, and the heaters connected to the furnace walls on both sides are connected to the heaters. equal in quantity.
A heat treatment or thermochemical treatment method, implemented by the continuous kiln according to any one of claims 1 to 18, wherein the heat treatment or thermochemical treatment method comprises:

heating the furnace chamber of the kiln to a temperature required for heat treatment or thermochemical treatment;

The object to be heat-treated or thermochemically treated is conveyed in the furnace cavity along the first direction by the loading tool, and during the conveying process, the air-flow sending and discharging device is controlled by the airflow control device to the furnace to the furnace Gas is input into the chamber and synchronously exhausted from the furnace chamber through the gas flow control device to maintain a process atmosphere for thermal treatment or thermochemical treatment in the furnace chamber.