CN112414112A

CN112414112A - Continuous kiln and heat treatment or thermochemical treatment method

Info

Publication number: CN112414112A
Application number: CN202011388498.5A
Authority: CN
Inventors: 王霞; 吴桢
Original assignee: Individual
Current assignee: Xinnuo Advanced Thermal Technology Suzhou Co ltd
Priority date: 2020-12-01
Filing date: 2020-12-01
Publication date: 2021-02-26

Abstract

A continuous kiln and a heat treatment or thermochemical treatment method belong to the field of lithium ion battery material processing. The continuous kiln comprises a kiln, an air flow feeding and exhausting device and an air flow control device. Wherein the flow exhaust means and the flow control means cooperate to control the atmosphere within the furnace chamber of the kiln. Because the air supply nozzle and the air suction nozzle in the airflow delivery and exhaust device are opposite, transverse airflow vertical to the length direction of the kiln can be formed, and the internal atmosphere can be kept stable.

Description

Continuous kiln and heat treatment or thermochemical 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

The continuous kiln is one of important equipment for producing the anode material of the lithium ion battery. The continuous kiln is mainly built by refractory materials, heat insulation materials and building materials, and is a kiln with a tunnel structure with openings at two ends.

In the production process of the lithium ion battery cathode material, it is usually required to inject a specific gas (such as dry air, oxygen or nitrogen, etc.) into a continuous kiln to form a process atmosphere required by the cathode material in the heat treatment or thermochemical treatment, and the specific gas is called a process gas. Meanwhile, when the cathode material is subjected to heat treatment or thermochemical treatment in the kiln, some gaseous byproducts (waste gas) such as moisture and carbon dioxide are released during the reaction process, and often some residual corrosive substances or gases are also contained. These exhaust gases need to be exhausted from the kiln as soon as possible, otherwise the atmosphere control in the kiln is seriously affected, and the performance of the calcined cathode material is deteriorated.

Disclosure of Invention

In order to improve 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 as follows:

in a first aspect, examples of the present application provide a continuous kiln that includes a kiln, a gas flow arrangement, and a gas flow control arrangement.

Wherein the furnace is provided with a furnace chamber extending along a first direction from the furnace head to the furnace tail. The airflow discharge device is used for forming directional airflow in the furnace cavity, wherein the directional airflow can flow along a second direction from one side wall to the other side wall of the furnace. And the airflow delivery and exhaust device is provided with a delivery and exhaust group, the delivery and exhaust group is provided with a delivery nozzle and an air exhaust nozzle which are connected with the furnace wall and mutually matched and arranged oppositely, and the delivery nozzle and the air exhaust nozzle are arranged along a third direction from the furnace top to the furnace 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 suction nozzle are controlled.

In cooperation with the operation and control of the airflow control device, the airflow delivery and exhaust device forms directional airflow in the furnace chamber of the kiln through the cooperation of the air supply 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 calcining atmosphere reaches the required degree. Furthermore, the process gas is continuously supplied through the gas supply nozzle, so that the atmosphere in the continuous kiln can be refreshed, and the waste gas in the continuous kiln can be discharged. At the same time, the heat loss can be controlled by controlling the flow rate of the gas.

In some examples of the present application, the furnace wall is provided with a gas distributor at the connection of gas feeding nozzles, which are in communication with the gas cavity of the gas distributor.

The gas distributor can achieve the effect of simplifying a gas conveying structure, and meanwhile, the control difficulty of the gas flow control device can be reduced.

In some examples of the application, the furnace wall has a suction opening at the connection suction nozzle, the suction opening being arranged in a third direction, the suction nozzle communicating with the suction opening.

Alternatively, the suction opening is elongated.

The long and narrow air suction port can provide larger air suction area and correspond to more air supply nozzles, thereby further improving the uniformity of air suction and exhaust at each position.

In some examples of the application, the continuous kiln comprises a saggar for containing the material, the side wall of the saggar having a gap which constitutes a passage for the directed air flow through the saggar, the gap being directed towards the air suction opening and the air delivery nozzle, respectively.

Optionally, the nozzle of the air nozzle is close to the notch.

The saggar is provided with the notch, so that the flowing of the air flow is facilitated, the waste gas is more easily taken away by the air flow, and the turbulent flowing of the air flow is reduced.

In some examples of the present application, 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 means comprises a pressure sensor and/or a flow sensor, one or both of the suction nozzle and the air feed nozzle being provided with a pressure sensor and/or a flow sensor.

The furnace pressure sensor and the gas concentration sensor can reflect the atmosphere concentration and the pressure in the furnace chamber of the furnace, thereby being convenient for a user to detect the atmosphere condition in the furnace chamber. The pressure sensor and the flow sensor can reflect the working conditions of the air supply nozzle and the air exhaust nozzle, the conditions of air flow supplied into the furnace chamber and air flow discharged out of the furnace chamber, and therefore the control of atmosphere in the furnace chamber is more effective and efficient.

In some examples of the present application, the gas flow control device includes a gas delivery valve and an exhaust valve, the gas delivery valve is in mating connection with the gas delivery nozzle, the exhaust valve is connected with the gas extraction nozzle, and the gas delivery valve and the exhaust valve are configured to be manipulated in response to the detection device.

In some examples of the present application, the air flow control device is configured to be capable of controlling the air feeding nozzle and the air extracting nozzle in a linkage manner, so that the air intake amount and the air exhaust amount in the kiln can be controlled in a linkage manner, and the strength of the directional air flow in the kiln is more stable.

In some examples of the present application, all of the suction nozzles in the plurality of grate groups are located on one side of the furnace wall, and all of the feed nozzles in the plurality of grate groups 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 both provided with air suction nozzles and air supply nozzles, and the air suction nozzles and the air supply nozzles on the furnace wall on the same side are alternately arranged at intervals in a third direction;

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

Different construction modes of the airflow exhaust device can meet different modes of a continuous kiln, and different degrees of updating and temperature adjusting effects of the atmosphere in the furnace chamber can be realized.

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

In some examples of the present application, the heater is arranged in a third direction and is connected to a furnace wall of the furnace. Optionally, the heaters are arranged in a third direction and a gas feed nozzle or a gas suction nozzle is provided between two adjacent heaters.

In a second aspect, the present application provides a method of heat treatment or thermochemical treatment carried out by means of a continuous kiln as described above. The heat treatment or thermochemical treatment method comprises: providing a temperature of a thermal or thermochemical treatment within the furnace chamber of the furnace; the object to be heat-treated or thermochemically treated is conveyed in a first direction within the furnace chamber by the loading tool, and during the conveyance, process gases are input into the furnace chamber by the gas flow feeding and exhausting device under the control of the gas flow control device, and gases are simultaneously exhausted from the furnace chamber by the gas flow control device, so as to maintain a heat-treating or thermochemical treating atmosphere within the furnace chamber.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

FIG. 1 is a schematic view of a construction of a kiln body in a continuous kiln of an example of the present application;

FIG. 2 shows a schematic view of a continuous kiln in an example of the present application from a first perspective;

FIG. 3 shows a schematic view of a continuous kiln in an example of the present application from a second perspective;

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

fig. 5 is a schematic structural view of a gas nozzle having a notch in an example.

Icon: 101-a kiln; 1011-furnace head; 1012-furnace tail; 1013-furnace chamber; 1014-furnace wall; 1015-furnace top; 1016-hearth; 11-a heater; 32-air feeding nozzle; 202-an injection device; 203-an exhaust; 31-a gas distributor; 2-sagger; 38-a gap; 39-suction port; 40-an exhaust valve; 42-a gas delivery valve; 18-a process gas; 37-a suction nozzle; 44-exhaust gas.

Detailed Description

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

In the production process, the heat treatment or thermochemical treatment of the cathode material, particularly the high-temperature calcination process, is a core process determining the material performance. Moreover, during the calcination process, many cathode materials require a specific process gas to be introduced into the calcination kiln to maintain a specific atmosphere, and the specific atmosphere is strictly controlled. For example, for ternary cathode materials, particularly high nickel ternary materials, oxygen needs to be introduced; the lithium iron phosphate needs to be protected by a nitrogen atmosphere. For such a kind of cathode material requiring a special atmosphere during calcination, the atmosphere control in the calcination process is one of the very important conditions, which may affect the performance of the cathode material after calcination, so that manufacturers of cathode materials and related researchers have been trying to improve the atmosphere control capability of the kiln during the calcination of the cathode material.

Currently, the calcination of the cathode material is generally achieved by a continuous kiln. Such as push plate type tunnel kilns (short for push plate kilns) and roller type tunnel kilns (short for roller kilns). The tunnel kiln is a kiln of a tunnel structure with openings at both ends, which is built by refractory materials, heat insulating materials and building materials. Tunnel kilns are generally sectioned to form an elevated temperature zone, a heat preservation zone and a cooling zone according to different temperatures and functions. The tunnel kiln is internally heated by an electric heater or by injecting fuel (such as natural gas, heavy oil and the like) for combustion. The material to be heat treated or thermochemically treated or the carrier (such as sagger) carrying the material is carried by a carrier, enters the tunnel kiln from one end (kiln head) of the tunnel, moves through the heating area, the heat preservation area and the cooling area, and exits the tunnel kiln from the other end (kiln tail) of the tunnel kiln to complete the heat treatment process.

However, through practice, the inventors of the present application found that the existing kilns all have different degrees of defects, thereby causing the calcination of the cathode material to be unsatisfactory.

After analysis, the inventor considers that the reason is mainly that:

during the calcination process, the cathode material and the process gas participate in the reaction. 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 material, and can also carry away gas byproducts generated by the reaction as soon as possible to promote the reaction. However, the gas inlet and outlet systems of the prior continuous kiln for calcining the cathode material, such as a pusher kiln or a roller kiln, cannot sufficiently satisfy the two critical requirements.

For example, the lithium ion battery positive electrode material is generally a powdery material before calcination, and the powdery material to be calcined is usually placed in a carrier. In order to increase the capacity of the kiln, the saggars carrying the material are placed on the vehicle in a stacked manner, thus seriously affecting the delivery and discharge of the air flow.

Taking the typical prior art that air is fed from the bottom and the side wall of the kiln and exhausted from the top of the kiln as an example, the process gas fed from the air inlet of the side wall of the kiln flows upwards under the suction of the negative pressure of the exhaust port at the top of the kiln and is exhausted from the kiln through the exhaust port at the top of the kiln.

The process gas entering from the bottom gas inlet is blocked by the bottom of the lower sagger, so that most of the process gas can only flow along the periphery of the sagger and is converged into the upward flowing gas flow; a small portion of the material passes through the gap between the saggars and upwardly into the vent.

Materials in the upper-layer saggar can be in relatively sufficient contact with process gas because no shielding object is arranged at the top of the saggar; meanwhile, the waste gas released by the materials in the upper saggar 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 enter smoothly, and the waste gas released by the material cannot be taken away smoothly by the airflow. The gas exchange inside and outside the lower sagger is mainly completed through diffusion: and a small part of process gas around the lower sagger enters the sagger from the notch on the edge of the sagger through diffusion. Similarly, the waste gas released from the materials in the lower saggar escapes from the saggar through the openings on the edge of the saggar by diffusion, then is collected to the top of the kiln along with the airflow around the saggar and is exhausted from the exhaust port.

Similarly, the prior typical technology cannot solve the problems of blocked material exhaust of the sagger at the lower layer and insufficient contact with fresh process gas in a mode of air inlet from the top and air exhaust from the bottom of the kiln.

In short, in the case of a stack of saggars, both the entry of process gases into the lower saggars and the escape of exhaust gases from the lower saggars are mainly due to diffusion, since the upper saggars shield the lower saggars.

Therefore, the gas exchange efficiency inside and outside 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 sagger is far lower than that of the upper sagger, and the accumulation of waste gas in the lower sagger is far higher than that of the upper sagger.

The atmosphere contacted by the materials in the upper and lower saggars is greatly different, the performance of the anode materials in the upper and lower saggars after calcination is also greatly different, and the consistency of the product is poor. Worse still, as the pressure for cost reduction increases, more saggers are stacked in the kiln by positive electrode material production enterprises, and as the number of layers of sagger stacking increases, the problem becomes more serious.

In addition, because the air pressure at 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 hindered. On the other hand, an excessively high intake pressure may cause excessive disturbance to the anode material powder, causing it to fly, which is inconvenient for normal conveyance.

In view of the current situation, the inventor proposes that the cathode active material can be sufficiently contacted with the process gas to perform the reaction by forming an ordered high-directivity gas flow in the kiln, and simultaneously, the waste gas generated by the reaction can be timely discharged to inhibit the adverse effect of the waste 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 a kiln 101, an air flow exhaust and air flow control device, as will be described in more detail below.

Kiln 101

The exemplary kiln 101 is constructed as shown in fig. 1 with walls 1014, hearth 1016, and roof 1015. In particular, in order to facilitate the control of the process gas 18 therein and to reduce the consumption of ineffective process gas 18, the cross section of the inside of the kiln 101 can be designed to be thin and high, and the free space (space without saggars 2) of the vault/roof 1015 (arc structure of the top in fig. 2) of the inside of the kiln 101 occupies a small proportion (the area of the furnace chamber in the arc top area is smaller than the area of the furnace chamber in the furnace wall area).

The flow direction of the process gas 18 in the continuous kiln of the present application is shown in fig. 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. Specifically, a first direction is defined from the furnace head 1011 to the furnace tail 1012, as shown by direction B (or length direction) in fig. 1; a second direction is defined from one side wall 1014 to the other side wall 1014, as shown by direction C (or width direction) in fig. 1; a third direction is defined from the roof 1015 to the floor 1016 as shown by 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 mainly performed in the kiln 101. As a place to provide heat treatment or thermochemical treatment, the kiln 101 has a furnace chamber 1013 bounded by furnace walls 1014. In actual use, heat or thermo-chemically treated material enters from the furnace head 1011 of the furnace 101, sequentially proceeds through different sections (e.g., sequentially distributed temperature raising section, temperature holding section, temperature lowering section) of the furnace chamber 1013, and finally exits from the furnace tail 1012 thereof. It should be noted that, the kiln 101 as a heat treatment or thermochemical treatment apparatus is generally required to maintain a certain airtightness and sealing property, and therefore, the furnace head 1011 and the furnace tail 1012 thereof are generally required to be provided with a gate or the like which can be selectively opened and closed, and the kiln 101 can be configured to be airtight through a housing. This is not illustrated in the examples of the present application. Those skilled in the art will appreciate that the above-described apparatus may be provided in the prior art, and will be briefly described in this application in order to avoid unnecessary redundancy.

To perform the heating operation, the kiln 101 generally requires the deployment of heating equipment. As previously mentioned, the heating device may directly heat a selected location within the kiln 101 by injecting fuel. But taking into account possible introduction of foreign matter and the effect on the calcination reaction. Generally, an electric heater 11, such as a heating rod, or a combustion heating method with a heat radiation tube is selected. The heating rod may be a specific product such as a resistance heater 11.

In the present example, the continuous kiln is provided with a heater 11, 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 top 1015, or the heater 11 may be inserted into the furnace chamber 1013 through the furnace bottom 1016 or the furnace wall 1014. Considering that the heater 11 may obstruct the material to be calcined which is transported in the furnace chamber 1013, in the present example, the heater 11 is inserted and fixed near the furnace wall 1014 and inserted along the direction a from the furnace top 1015 to the furnace bottom 1016, please refer to fig. 1 and 3.

In the disclosure of fig. 3, the furnace walls 1014 on both sides of the furnace 101 are provided with heaters 11. The heaters 11 of the furnace walls 1014 on both sides are equal in number and are opposed one to one in the direction C. In the furnace wall 1014 on the same side, adjacent two heaters 11 are spaced apart from each other by an appropriate distance. Of course, the installation position and mode of the heater 11 may be selected, and the present application does not specifically limit this.

In addition, various suitable devices and equipment, such as, for example, a detection device, can be optionally provided for the furnace 101 according to different needs.

For example, in various applications, other gas supply line devices may be optionally provided if it is desired to provide other atmospheres within the furnace chamber 1013 of the furnace 101.

For example, in order to monitor the temperature in the furnace chamber 1013 of the kiln 101 so as to adjust the temperature timely, a temperature detection device, such as a temperature sensor, specifically an infrared temperature detector, or the like, may be further disposed in the kiln 101.

Since the process gas 18 is supplied for calcination in the furnace chamber 1013, a gas monitoring device may be provided in the furnace 101 corresponding thereto. The gas monitoring device may be a gas pressure detector, a concentration detector, or both. The air pressure detector can be a furnace pressure sensor for detecting the furnace 101; wherein the concentration detector can be a gas concentration sensor for detecting the concentration of the process gas 18 (e.g., oxygen) within the furnace 101.

In addition to this, the continuous kiln may be provided with a device for containing and conveying the calcined material (e.g., the cathode material), such as a sagger 2, as shown in fig. 4. In order to facilitate the air flow through the sagger 2, a gap 38 is formed in the side wall of the sagger 2. Thus, when a plurality of saggars 2 are stacked, the slits 38 of different saggars 2 can constitute a passage for the directed air flow through the saggars 2.

Airflow conveying and exhausting device

In the present example, the airflow delivery arrangement mainly comprises an airflow input portion and an airflow discharge portion. Moreover, the two parts cooperate to form a continuous and directed flow of air within the kiln 101. The term "orientation" refers to a direction C that is staggered (e.g., criss-cross) with respect to the direction B of the furnace 101, i.e., from one side wall 1014 of the furnace 101 to the other side wall 1014. In other words, during the longitudinal transport of the calcination material from the front end to the rear end of the kiln in the furnace chamber 1013, a transverse gas flow is formed by the gas flow discharge means.

Wherein the gas flow input part is used for transmitting the process gas 18 to the furnace chamber 1013 of the kiln 101 for reaction needs in the calcination process. Wherein the gas flow exhaust part is used for exhausting the waste gas 44 in the furnace chamber 1013 of the furnace 101 to the outside of the furnace 101.

With which renewal of the atmosphere in the furnace chamber 1013 of the furnace 101, such as addition of fresh process gas 18, can be achieved while simultaneously exhausting the exhaust gases 44. Also, by controlling the delivery state of the air flow such as the flow rate, etc., the temperature in the furnace chamber 1013 can be controlled to some extent. Since the exhaust gas 44 may carry away part of the heat, the temperature of the freshly supplied process gas 18 may also absorb part of the heat.

The airflow delivery and discharge device is provided with a delivery and discharge group. The supply and exhaust set includes any number of supply and

exhaust nozzles

32, 37. And the air supply nozzle 32 and the air exhaust nozzle 37 are spaced apart and opposed to each other, and the air supply nozzle 32 and the air exhaust nozzle 37 are connected to the furnace wall 1014, so that the space therebetween is a passage for the calcined material in the furnace chamber 1013.

The air delivery nozzles 32 and air extraction nozzles 37 in the set are arranged along a third direction from the roof 1015 to the floor 1016 of the furnace 101. I.e. the air supply nozzles 32 and the air extraction nozzles 37 are arranged along the height direction of the kiln. Therefore, when a calcination object having a large height is placed in the cavity 1013 of the furnace 101, the arrangement of the air supply nozzles 32 and the air suction nozzles 37 in 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 cutout 38 of the sagger 2 for containing the calcination material faces the air feed nozzle 32. Further, the mouth (gas outlet) of the gas delivery nozzle 32 approaches the notch 38 (to the limit of not obstructing the normal transport of the saggars), so that it is easier to accurately deliver the gas to the saggars 2.

Fig. 2 is a schematic sectional view of the continuous kiln, in which a feed-discharge group comprising 8 feed nozzles 32 and 3 extraction nozzles 37 is shown. In other examples, the number of air delivery nozzles 32 and air extraction nozzles 37 may be equal for a single air delivery set, or the number of air delivery nozzles 32 may be less than the number of air extraction nozzles 37. In other words, the air supply nozzles 32 and the air suction nozzles 37 may be arranged one-to-one, or may be arranged one-to-many or many-to-one.

The above description has been given by way of example of a continuous kiln having only one gas stream discharge device. When a continuous kiln in other examples has multiple banks, it will have multiple banks accordingly. Thus, where there are multiple staging groups, all of the staging groups may be arranged along the length of the kiln 101, such as shown in FIG. 3.

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

In the first case, in the direction a of the kiln 101, in a single grate group, the air delivery nozzles 32 are all disposed in one of the furnace walls 1014 and the air extraction nozzles 37 are all disposed in the other of the furnace walls 1014.

In case two, in the direction a of the kiln 101, in one of the grate groups, part of the air delivery nozzles 32 are arranged in one of the walls 1014, and the remaining part of the air delivery nozzles 32 are located in the other wall 1014. Accordingly, in the present fire bank, a portion of the extraction nozzles 37 are disposed in one of the walls 1014 and the remaining extraction nozzles 37 are disposed in the other wall 1014.

In the case of a continuous kiln in which there is only one gas flow supply and discharge device, respectively, with one supply and discharge group, the configuration of the supply and

exhaust nozzles

32, 37 can be chosen arbitrarily and configured in the manner described in case one or case two above.

For continuous kilns where there are multiple (e.g. more than two) gas stream conveyors, there are also multiple sets of conveyors. All the feeding and discharging groups are arranged along the direction B of the kiln 101. And the air supply nozzles 32 and the air suction nozzles 37 in each air supply and exhaust group may be arranged in a manner of the case one, or in a manner of the case two, or in a manner of the combination of the case one and the case two.

In the illustrated embodiment, there are multiple supply and exhaust groups, and the supply nozzle 32 and the exhaust nozzle 37 are arranged in a combination of the first and second cases. In particular, two adjacent rows of the same side wall 1014 are arranged with the air delivery nozzles 32 and the air extraction nozzles 37 alternating. In this way, when more than one row (two rows are shown in fig. 3) of saggers 2 stacked on carriers of the calcination material in the kiln 101 passes through the kiln, the saggers 2 on each side have equal opportunity to face the gas injection means 202 or the exhaust means 203, i.e. the carriers, etc. with equal opportunity to face the gas feeding nozzles 32 and the air suction nozzles 37. This improves the consistency of the calcination of the material in different rows of saggars 2, so that each saggar 2 has an air flow passing alternately from both sides. To ensure better consistency, the saggers 2 in the present example are stacked in two columns, as shown in fig. 3.

The position and configuration of the air supply nozzles 32 and the air extraction nozzles 37 can also be adjusted in a targeted manner with respect to the heaters 11 in the kiln. For example, the air supply nozzle 32 or the air suction nozzle 37 is provided between two adjacent heaters 11. That is, for the example of a plurality of feed groups, the feed nozzles 32 and the suction nozzles 37 of adjacent two feed groups are alternately arranged, and therefore, the heater 11 may be disposed between the feed nozzles 32 and the suction nozzles 37. Accordingly, the two heaters 11 are also alternately "sandwiched" between the air delivery nozzles 32 or air extraction nozzles 37. The alternating pattern may be a pattern of one (one heater 11, one air feed nozzle 32, one heater 11, one air feed nozzle 32) at intervals, or may be a pattern of two heaters 11, two air feed nozzles 32, and the like. When the process gas 18 is injected, the process gas 18 can be sufficiently preheated again while preventing the gas from being directly injected onto the adjacent heater 11 to affect the heating power of the heater 11.

The arrangement of the air supply and exhaust groups is explained above, and the specific structure of the air supply nozzle and the air exhaust nozzle will be described in detail below.

In the example, the air delivery nozzle 32 is configured as a cylindrical hollow tube. And has one end inserted into the furnace wall 1014 and another end extending into the furnace chamber 1013. The gas feed nozzles 32 may be configured to provide gas flow paths through a buried conduit (which may be a hollow refractory brick splice, or a ceramic tube, or a refractory metal tube lined with ceramic) in the furnace wall 1014 for the purpose of delivering the process gas 18 through the gas feed blower. In other examples, the air delivery nozzle 32 may be located outside the furnace 101, and an injection tube connected to the air delivery nozzle 32 may be inserted into the furnace through a hole in the furnace wall 1014; alternatively, instead of installing an injection tube inserted into the furnace, the chamber 1013 is inflated by air nozzles 32 from outside the furnace through holes in the furnace walls 1014. Or, a hollow brick stacking kiln is adopted, then air holes communicated with the hollow structure are formed in the hollow bricks, and air is injected through the air holes.

When the number of air feed nozzles 32 is large, providing a separate piping for each air feed nozzle 32 may result in a complicated process and structure. Thus, in the example shown, a cavity is optionally provided in the furnace wall 1014, which can be directly supplied with gas by a pipeline. The air delivery nozzle 32 may also be in direct communication with the chamber. Functionally, the chamber essentially constitutes a gas distributor 31. Heating plates may also be provided in the gas distributor 31 for heating the process gas 18 entering therein to avoid direct entry of cold process gas 18 into the furnace chamber 1013. Of course, the process gas 18 may also be preheated outside the continuous kiln and then passed into the gas distributor 31 and then injected into the furnace chamber 1013 via the gas feed nozzles 32.

Further, as a modification, the structure of the air feed nozzle 32 in the form of a hollow pipe may be modified and fitted to the air distributor 31. For example, in some examples, the end of the gas delivery nozzle 32 that extends into the gas distributor 31 is notched, thereby forming an "L" end structure. Also, the process gas 18 is introduced into the gas distributor 31 in an incident direction away from the gap of the gas supply nozzle 32 and away from each other, as shown in fig. 5. Thereby, the process gas 18 in the gas distributor 31 can be delayed from entering the nozzle, so that a longer heating time of the process gas 18 in the distributor is obtained, and the heating effect is improved.

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

Further, as a power source for delivering the air from the air supply nozzle 32 and the air suction nozzle 37, an exhaust fan, a blower, an air pump, or the like may be provided in the air flow supply and discharge device in a matching manner. In the present example, the continuous kiln is provided with an injection device 202 corresponding to the air delivery nozzle 32; the continuous kiln is provided with an exhaust device 203 corresponding to the exhaust nozzle 37.

Air flow control device

The air flow control device is matched with the air flow delivery and discharge device. Which can control the air supply nozzle 32 and the air suction nozzle 37 and make the air supply nozzle 32 and the air suction nozzle 37 work simultaneously and matchedly. I.e. the working condition of the air nozzle 32 is linked to the working condition of the suction nozzle 37. When the operating state of the air supply nozzle 32 is adjusted, the state of the air suction nozzle 37 is adjusted accordingly. In principle, the air intake of the air supply nozzle 32 is matched to the displacement of the suction nozzle 37 by the adjustment of the air flow control device, for example, the air intake is equal to the displacement.

In other words, under some conditions, the air flow control device may control the air supply nozzle 32 and the air extraction nozzle 37 in a coordinated manner. Of course, in other examples, the air flow control device may control the air supply nozzle and the air extraction nozzle independently of each other. For example, when a certain automatic control fails or the automatic control adjustment range cannot meet the actual requirement in the linkage mechanism or a certain special condition needs to be changed into manual operation, the system can be switched to a manual mode through a program, and the gas level in the furnace are achieved by manually adjusting the gas inlet control valve and the gas exhaust control valve by depending on field instruments (values of a flowmeter, a differential pressure gauge and a pressure transmitter), and whether the gas is balanced or not is judged by displaying the oxygen partial pressure value.

The air inflow and the air displacement are controlled to match, so that the strength of the formed directional airflow is more stable. In addition, the unnecessary energy loss caused by the fact that a large amount of heat in the kiln 101 is taken away by excessive smoke generated due to the relatively large exhaust amount can be avoided, and the phenomenon that the residual amount of the waste gas 44 in the kiln 101 is too high due to the relatively small exhaust amount can be avoided.

As an example, the gas flow control device includes a gas delivery valve 42 (which may be an automatically controlled valve, which may have a handle with a manual adjustment) and a gas exhaust valve 40 (which may be an automatically controlled corrosion resistant high temperature valve, which may have a handle with a manual adjustment).

The air supply valve 42 is connected to the air supply nozzle 32, and the exhaust valve 40 is connected to the suction nozzle 37. The control of the process gas 18 delivery state and the off-gas 44 delivery state can be achieved by adjusting the opening of the two valves. The valve can adopt various butterfly valves, ball valves, regulating valves, throttle valves and the like. In order to improve the accuracy of control and to facilitate the operation, proportional solenoid valves may be optionally used for the discharge valve 40 and the air feed valve 42.

Further, the continuous kiln may also be provided with a detection device, such that the air bleed valve 42 and the air exhaust valve 40 are configured to be manipulated in response to the detection device. In other words, the operation of the air supply nozzle 32 and the exhaust nozzle is performed by adjusting the air supply valve 42 and the exhaust valve 40 according to the operation of the continuous kiln detected by the detection means.

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

In addition, a furnace pressure sensor and a gas concentration sensor for the process gas 18 provided therein may also be provided as part of the detection device, corresponding to the furnace 101. Therefore, various states of the injected gas and the exhausted gas and the gas inside the cavity 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 more accurate.

Based on the requirement of improving automation of control, the controller can be selected to control the air supply valve 42 and the air discharge valve 40, and the detection device is connected with the controller in a matching way, so that the collection, processing and control information sending of the detection information are matched with each other. The controller may be any type of electronic component or collection of components capable of certain data storage and processing. For example, 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 (FPGA), an Application Specific Integrated Circuit chip (ASIC chip), and the like. By such a structural design, the continuous kiln enables closed loop operation of gas injection and exhaust.

The working principle of the controller can be as follows:

data of the partial pressure of the process gas 18 in the furnace chamber 1013 is collected by the furnace pressure sensor and the 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 also calculates the target opening of the exhaust valve 40 of the exhaust system by taking the flow data of the air feeding valve 42 as a parameter, and the target opening is used for adjusting the exhaust volume of the exhaust system to realize linkage control of the exhaust volume and the air inflow volume.

When the partial pressure of the process gas 18 is lower than the set value by a certain percentage, the opening of the gas 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 set value by a certain percentage, the air inlet flow control valve is closed and the opening of the exhaust control valve is reduced; the inlet flow control valve and the exhaust control valve remain unchanged while the process gas 18 partial pressure is maintained within a certain percentage of the set point. In addition, in order for this feedback system to operate smoothly without acting excessively large or excessively slow, the furnace pressure within the furnace chamber 1013 of the furnace 101 acts as an intermediate equilibrium constant such that any adjustments require the furnace pressure to be maintained within a set fluctuation range.

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

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

step 1, providing a temperature of thermal or thermochemical treatment within the furnace chamber 1013 of the furnace 101.

Wherein, the temperature of the heat treatment or the thermochemical treatment can be provided by the heater 11 of the continuous kiln arranged in the kiln 101. The number and location of the heaters 11 in operation can be adaptively adjusted for different temperature zones (temperature rise, heating, and cooling zones, etc.) of the furnace 101.

Step 2, the object to be heat-treated or thermochemically treated is transported in the furnace chamber 1013 by the loading tool in a first direction, and during the transport process, process gases are input into the furnace chamber 1013 by the gas flow feeding and exhausting device under the control of the gas flow control device, and gases are simultaneously exhausted from the furnace chamber 1013 by the gas flow control device, so as to maintain a desired process atmosphere in the furnace chamber 1013.

The loading tool is, for example, a sagger 2, and is transported by a transport means such as a roller, pusher, or kiln car. In order to increase the yield while allowing for the use of process gas 18, the saggars 2 on the transport vehicle are arranged in two rows of eight layers each. The kiln car transports the sagger 2 from the kiln head gradually through the heating zone, the heat preservation zone and the cooling zone, in the process, the process gas 18 is continuously injected and the waste gas 44 is continuously discharged until the sagger 2 is taken out of the kiln from the kiln tail to finish the calcining process.

With the continuous kiln proposed in the present application, for heat treatment or thermochemical treatment work in the case where saggars 2 are stacked in a higher number of layers, the saggars 2 of the lower layer can be brought into contact with the concentration of the process gas 18 of increased concentration, and the accumulation of the exhaust gas 44 of the saggars 2 of the lower layer is reduced, thereby making the atmosphere in the saggars 2 of the upper and lower layers uniform, and the uniformity of the properties of the product after calcination improved. In addition, the air inflow and the air displacement are selectively controlled in a linkage manner, so that the strength of the directional air flow is stabilized; by arranging the gas injection devices 202 and the exhaust devices 203 on each side of the kiln wall in a staggered manner, when a plurality of saggars 2 are stacked, the saggars 2 on the outermost side can face the gas injection devices 202 and the exhaust devices 203 at equal probability, and the consistency of the atmosphere in the saggars 2 on the two sides is also improved.

It should be noted that although the continuous kiln is presented as a cathode material for producing a lithium ion battery by calcination in the present example, this is not intended to limit the present application to this. In other examples, the continuous kiln may also be used to fire ceramic materials or other alloy materials, etc. thereof.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A continuous kiln, comprising:

the furnace is provided with a furnace chamber extending along a first direction from the furnace head to the furnace tail;

the airflow feeding and discharging device is used for forming directional airflow capable of flowing along a second direction from one side of a furnace wall to the other side of the furnace wall in the furnace chamber, and is provided with a feeding and discharging group, the feeding and discharging group is provided with a feeding nozzle and an air suction nozzle which are connected to the furnace wall and are matched and opposite to each other, and the feeding nozzle and the air suction nozzle are arranged along a third direction from the furnace top to the furnace bottom of the furnace;

and the air flow control device is connected with the air flow delivery and exhaust device in a matching way, so that the air delivery nozzle and the air suction nozzle can be controlled.

2. Continuous kiln according to claim 1, characterized in that the furnace wall is provided with gas distributors at the connection of the gas feed nozzles, which gas feed nozzles communicate with the gas chambers of the gas distributors.

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

optionally, the suction opening is elongated.

4. The continuous kiln according to claim 3, comprising a saggar for containing the material, the saggar having a cutout in a side wall thereof, said cutout constituting a passage for the directed gas flow through the saggar, said cutout being directed towards the suction opening and the gas feed nozzle, respectively;

optionally, the nozzle opening of the air feeding nozzle is close to the notch.

5. The continuous kiln according to claim 1, characterized in that it comprises detection means comprising a furnace pressure sensor and/or a gas concentration sensor for detecting the kiln;

optionally, the detection device comprises a pressure sensor and/or a flow sensor, and one or both of the suction nozzle and the air feeding nozzle are provided with the pressure sensor and/or the flow sensor in a matching manner.

6. The continuous kiln as claimed in claim 5, wherein the gas flow control means comprises a gas feed valve and a gas exhaust valve, the gas feed valve being in mating connection with the gas feed nozzle, the gas exhaust valve being connected with the gas exhaust nozzle, and the gas feed valve and the gas exhaust valve being configured to be manipulated in response to the detection means;

optionally, the air flow control device is configured to be capable of controlling the air feeding nozzle and the air extracting nozzle in linkage, thereby controlling the air intake amount and the air exhaust amount in the kiln in linkage.

7. The continuous kiln as claimed in claim 1, wherein all of the extraction nozzles in the bank are located on the one side wall and all of the extraction nozzles in the bank are located on the other side wall;

or the furnace wall on one side and the furnace wall on the other side are both provided with the air suction nozzles and the air feeding nozzles, and the air 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 airflow conveying and exhausting devices is multiple and is arranged along the first direction, the air feeding nozzle of the same airflow conveying and exhausting device is positioned on one furnace wall, the air suction nozzle is positioned on the other furnace wall, and in the first direction, the air suction nozzles and the air feeding nozzles in two adjacent airflow conveying and exhausting devices are alternately arranged at intervals.

8. The continuous kiln of claim 1, comprising a heater coupled to the kiln.

9. The continuous kiln as claimed in claim 8, wherein the heater is disposed in the third direction and is connected to a wall of the kiln;

optionally, the heaters are arranged along the third direction, and a gas supply nozzle or a gas suction nozzle is arranged between two adjacent heaters.

10. A thermal or thermochemical treatment process, carried out by means of the continuous kiln according to any of claims 1 to 9, characterized in that it comprises:

providing a temperature required for thermal or thermochemical treatment in a furnace chamber of the furnace;

transporting the object to be heat-treated or thermochemically treated in the first direction within a furnace chamber by a loading tool, and during the transporting, inputting gas into the furnace chamber by the gas flow exhaust device under the control of the gas flow control device and simultaneously exhausting gas from the furnace chamber by the gas flow control device to maintain a process atmosphere of the heat-treatment or thermochemical treatment within the furnace chamber.