DRYING APPLIANCE

Abstract

In this context, a drying apparatus is provided, comprising at least one oven and an external circulation system for supplying hot air into the oven. The external circulation system includes a heating device, an air inlet duct, and a connecting damper. The air inlet duct comprises a high-temperature air duct and a low-temperature air duct, the outlets of which are connected to the oven via the connecting damper, and the inlets of which communicate with the external air via a fan. The heating device is arranged on a branch of the high-temperature air duct, and the airflow ratio between the high-temperature and low-temperature air ducts can be controlled by adjusting the connecting damper.The oven can adjust the temperature, and the adjustment is simple and results in highly accurate temperature control. See Figure 1 for an abbreviation.

Description

Title of the invention: DRYING APPARATUS

[0001] The present application claims priority from Chinese patent application No. 2023212858959 filed on May 24, 2023. Technical field

[0002] The disclosure relates to the field of lithium battery production, in particular a drying apparatus. PREVIOUS ART

[0003] In the manufacturing process of lithium batteries, the electrode sheets and separators must be heated and dried in a drying apparatus after coating. The electrode sheets and separators are dried with hot air in most existing drying apparatus. Fresh air, drawn in by a fresh air blower, undergoes heat exchange in a waste heat recovery heat exchanger and is heated by a heating element before being sent to a chamber inside an oven for a drying process. Finally, the air is extracted from the oven by an exhaust fan and, after waste heat recovery and further treatment, is discharged to the environment or reused in circulation.

[0004] However, the energy structure varies from region to region and is also influenced by site conditions. Some local drying apparatus manufacturers do not have steam and heat transfer oil heating facilities and can only use electric heating, which requires higher power levels for the distribution and wiring of facilities and apparatus. Each oven in the drying apparatus can operate under different actual drying conditions, but all ovens are designed for the highest operating conditions, which leads to a higher overall installed power. Currently, the oven temperature can only be adjusted by controlling the output power of the heating element, which is not easy to adjust and the temperature fluctuates greatly. Summary of the invention

[0005] In order to overcome the disadvantages of the prior art, the present disclosure provides a drying apparatus, which comprises at least one oven and an external circulation system for supplying hot air inside the oven. By means of the external circulation system, an air flow ratio between high-temperature air and low-temperature air can be adjusted via a connecting damper, thereby adjusting the temperature inside the oven. This adjustment is simple and results in high accuracy in temperature control. The apparatus adopts a heating centralized for the entire system to reduce the installed power; it also allows different heating methods to be selected to heat the furnace, making it applicable to a greater number of scenarios.

[0006] The technical scheme adopted by the disclosure to solve the technical problems is as follows:

[0007] A drying apparatus comprises at least one oven and an external circulation system for supplying hot air to the interior of the oven, wherein the external circulation system comprises a heater, an air duct and a connecting damper, and the air duct comprises a high-temperature air duct and a low-temperature air duct; an outlet of the high-temperature air duct and an outlet of the low-temperature air duct are connected to the oven via the connecting damper, and an inlet of the high-temperature air duct and an inlet of the low-temperature air duct are in communication with outside air via a fresh air blower.The heater is arranged on the pipeline of the high-temperature air duct and can heat the fresh air entering the high-temperature air duct, and an air flow ratio between the high-temperature air duct and the low-temperature air duct can be controlled by adjusting the linkage damper, thereby regulating the mixed temperature of the high-temperature air and the low-temperature air.

[0008] According to one embodiment, the external circulation system further comprises a waste heat recovery heat exchanger, the inlet of which is in communication with the outlet of the fresh air blower and the outlet of which is in communication with the inlet of the high temperature air duct and the inlet of the low temperature air duct.

[0009] According to one embodiment, the furnace comprises an exhaust duct, which is in communication with the waste heat recovery heat exchanger and an exhaust fan, and the exhaust fan is used to extract exhaust air which has undergone heat exchange with fresh air in the waste heat recovery heat exchanger into the outside environment.

[0010] According to one embodiment, the drying apparatus further comprises a filter, and the fresh air blower is in communication with the outside air via the filter.

[0011] According to one embodiment, the exhaust duct, the high-temperature air duct and the low-temperature air duct are all equipped with a temperature sensor and a pressure sensor, and the furnace is internally equipped with a temperature sensor and a pressure sensor, so that the temperature and pressure are detected at all points.

[0012] According to one embodiment, the external circulation system further comprises a circulation fan, which is in communication with an outlet of the crossover register and can mix mixed air at the outlet of the crossover register with return air inside the furnace and transport it into a chamber inside the furnace.

[0013] According to one embodiment, the furnace comprises an extraction duct and a condenser, and an extraction air from the extraction duct is discharged into the condenser through the waste heat recovery heat exchanger, and then discharged into the external environment through the condenser or it continues to participate in the circulation.

[0014] According to one embodiment, an outlet of the condenser is in communication with an NMP recuperator which, in turn, is in communication with the external environment.

[0015] According to one embodiment, the heating device is provided with a U-shaped heating tube or a natural gas burner, and the front and rear of the heating device are provided with a flame arrester.

[0016] The disclosure has the following beneficial effects:

[0017] a. the drying apparatus, through the use of an external circulation system, replaces individual heating of the ovens with centralized heating in several ovens. The power of the heating device can be designed according to the heat required for drying the entire line of ovens, which makes it possible to considerably reduce the installed power;

[0018] b. an air flow ratio between high-temperature air and low-temperature air can be controlled by adjusting the connecting damper, and the temperature of the mixed air can be changed, thereby adjusting the temperature inside the furnace. This adjustment is simple and results in high accuracy of temperature control; and

[0019] c. since the hot air of each furnace is centrally heated in the external circulation system, it is possible to select different heating modes such as heat transfer oil, steam, gas or electric heating to heat the hot air, thereby expanding the scope of application. Brief Description of the Drawings

[0020] The disclosure will be explained in more detail with the accompanying drawings and embodiments.

[0021] [Fig-1] shows a diagram according to a first embodiment of the disclosure;

[0022] [Fig.2] shows a diagram of a link register in the disclosure;

[0023] [Fig.3] shows a diagram of multiple furnaces sharing a circulation system external according to the first embodiment; and

[0024] [Fig.4] shows a diagram according to a second embodiment of the disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0025] The concept, concrete structure and technical effects of the present disclosure will be described clearly and completely with the help of embodiments and drawings, so as to fully illustrate the objective, characteristics and effects of the present disclosure. Obviously, the described embodiment is only a part of the embodiment of the disclosure. Based on the embodiment of the disclosure, other embodiments obtained by those skilled in the art without paying creative labor belong to the protection scope of the disclosure. In addition, all the connection / connection relationships involved in the disclosure do not mean that the components with a single finger are directly connected, but that a better connection structure can be formed by adding or reducing the connection accessories according to the specific implementation situation.All technical features of creating disclosure can be combined interactively without conflicting with each other.

[0026] Embodiment 1:

[0027] The present disclosure provides a drying apparatus which comprises an oven 2 and an external circulation system. The drying apparatus may be equipped with one or more ovens 2, and an external circulation system may be shared by several ovens 2.

[0028] Referring to [Fig. 1], it shows a connection diagram between the furnace and the external circulation system. The furnace 2 is equipped with an air inlet 20 and an air outlet 21, and the external circulation system is connected to the air inlet 20 and the air outlet 21.

[0029] The external circulation system comprises a fresh air blower 24, a waste heat recovery heat exchanger 22, an air duct, a heater 2220, and a connecting damper. An inlet of the fresh air blower 24 is connected to the outdoor environment, and an outlet of the fresh air blower 24 is connected to an inlet of the waste heat recovery heat exchanger 22. The fresh air blower 24 draws air from the outdoor environment and transports it to the waste heat recovery heat exchanger 22, and an outlet of the waste heat recovery heat exchanger 22 is connected to the air duct. The air duct comprises a high-temperature air duct 222 and a low-temperature air duct 223.The heating device 2220 is arranged on a pipeline of the high-temperature air duct 222 and can heat the air inside the high-temperature air duct 222. The outlet of the high-temperature air duct 222 and the outlet of the low-temperature air duct 223 are connected to the air inlet 20 of the furnace 2 via the connecting damper. Exhaust air from the air outlet 21 of the furnace 2 is collected at the waste heat recovery heat exchanger 22 via an exhaust duct 224 and is discharged to the outside environment by an exhaust fan 23, after the waste heat has been recovered by the waste heat recovery heat exchanger 22.

[0030] Referring to [Fig.2], the link damper is equipped with a high temperature damper 2221 in communication with the high temperature air duct 222 and a low temperature damper 2231 in communication with the low temperature air duct 223. The opening degree of the high temperature damper 2221 is inversely proportional to that of the low temperature damper 2231. The link damper also includes an electric actuator 2222 for controlling the opening degree of the damper. The electric actuator 2222 is controlled by a program, and the opening degree of the link damper can be realized by electrical or mechanical link actions. The opening ratio of the high temperature damper 2221 and the low temperature damper 2231 is 1:-1, which is realized by the mechanical design of the damper itself.In other words, when the high temperature damper 2221 is fully open, the low temperature damper 2231 is fully closed, and then the electric actuator automatically controls the opening degree through the program.

[0031] The exhaust duct 224, the high-temperature air duct 222 and the low-temperature air duct 223 are all equipped with a temperature sensor and a pressure sensor, and the furnace is also equipped with a temperature sensor and a pressure sensor inside, so that the temperature and pressure can be detected at different points.

[0032] When it is necessary to heat the furnace, i.e., when the set temperature of the furnace is higher than the temperature detected by the temperature sensor, the high temperature damper 2221 is automatically controlled to be opened gradually by the program, and can be fully opened to the maximum. When the actual detected temperature is close to the set temperature, the high temperature damper 2221 closes slowly until the actual detected temperature is equal to the set temperature, after which its opening degree is fixed and is no longer adjusted. When the furnace is to be cooled, i.e., when the set temperature of the furnace is lower than the actual detected temperature, the adjustment process is opposite to the heating process. The design of the linkage damper makes it possible to adjust the furnace temperature more quickly.

[0033] In this embodiment, the furnace is a negative electrode furnace, and the heating device 2220 is gas heated, and a flame arrester is disposed in front and on the rear of the 2220 heater to improve safety during operation.

[0034] A filter is disposed in front of the inlet of the fresh air blower 24, where the air will be filtered before being drawn into the air duct by the fresh air blower 24. The filter comprises a primary filter 251 and a medium efficiency filter 25. After being filtered, the air is then conveyed by the fresh air blower 24 to the waste heat recovery heat exchanger 22 to undergo heat exchange with the exhaust air from the furnace 2. The waste heat recovery heat exchanger 22 is connected to the exhaust fan 23, and all the exhaust air after the heat exchange is discharged to the outside environment by the exhaust fan 23.

[0035] Referring to [Fig. 3], it shows a diagram of multiple ovens sharing an external circulation system in the drying apparatus. The drying apparatus is divided into two modules, each comprising seven ovens. Each module is equipped with a natural gas burner 2220 as a heating device, which is responsible for the heating work of the seven ovens in the module. The drying apparatus is provided with centralized heating, and a natural gas burner 2220 can provide the heat required for drying multiple ovens, thereby effectively reducing the installed power of the entire apparatus. In addition, the high energy conversion rate of natural gas can reduce the overall energy consumption of the apparatus.

[0036] The work flow of the drying apparatus according to the disclosure is as follows. Fresh air, after being filtered, is transported to the waste heat recovery heat exchanger 22 by the fresh air blower 24, and the fresh air in the waste heat recovery heat exchanger 22 exchanges heat with the exhaust air from the furnace 2. The waste heat recovery heat exchanger 22 then transports the exchanged low-temperature air to the high-temperature air duct 222 and the low-temperature air duct 223. A burner 2220 is disposed on the pipeline of the high-temperature air duct 222, and the burner 2220 releases heat by burning natural gas to heat the low-temperature air in the high-temperature air duct 222.The high-temperature heated air from the high-temperature air duct 222 and the low-temperature air from the low-temperature air duct 223 are mixed once through the high-temperature air damper 2221 and the low-temperature air damper 2231 of the connecting air damper to form a total fresh air, which is then sent into the furnace 2 by the circulating fan. The total fresh air is mixed with the return air from the furnace 2 a second time to form a circulating air, which is sent to the furnace chamber 2 by the circulating fan and then expelled through an air nozzle.

[0037] Embodiment 2:

[0038] The difference between Embodiment 2 and Embodiment 1 is that the furnace of this embodiment is a positive electrode furnace and the heater is provided with a U-shaped electric heating tube. In practice, other heating methods such as heat transfer oil or steam can be selected according to the needs of the scenario, making it applicable in a wider range of scenarios. By designing an electric heater with a higher energy conversion rate, the air that has been treated after recovering waste heat is directly heated, reducing the output power of the heater and minimizing energy losses. The apparatus uses a centralized heating method, which can reduce the overall energy consumption of the apparatus.

[0039] Referring to [Fig. 4], the exhaust air from the positive electrode furnace contains a high concentration of N-Methylpyrrolidone (NMP), and in this embodiment, the U-shaped heating tube 1220 is equipped with a flame arrester at the front and rear to prevent the NMP from burning and exploding. In addition, in this embodiment, a condenser and an NMP recuperator 14 are also provided to reduce the NMP vapor in the exhaust air, to prevent explosions in the heater 1220 due to the high concentration of NMP. The exhaust outlet 11 of the furnace 2 carries the exhaust air to the waste heat recovery heat exchanger 12 through the exhaust duct 124 for heat exchange and cooling, and then to the condenser.The condenser comprises a chilled water condenser 13 and a cooling water condenser 131 for cooling the exhaust air to produce low NMP concentration exhaust air. The high temperature and high NMP concentration exhaust air in the furnace 2 is converted into low temperature and low NMP concentration exhaust air after secondary cooling treatment by the waste heat recovery heat exchanger 12 and the condenser.A portion of the exhaust air, between 4% and 10%, is treated by the NMP recuperator 14 to meet emission levels before being discharged to the outside environment by the exhaust fan 140, while the remainder of the exhaust air is drawn by a fresh air blower 15 to the waste heat recovery heat exchanger 12 to undergo heat exchange with the high temperature, high NMP concentration exhaust air, thereby becoming low temperature exhaust air to continue to be reused in circulation.

[0040] The low temperature air which has undergone heat exchange in the waste heat recovery heat exchanger 12 flows into the high temperature air duct 122 and into the low temperature air duct 123. The low temperature air temperature passing through the high-temperature air duct 122 becomes high-temperature air after being heated by the U-shaped heating tube 1220. The low-temperature air volume passing through the low-temperature air duct 123 and the high-temperature air volume passing through the high-temperature air duct 122 can be controlled by the high-temperature air damper 2221 and the low-temperature air damper 2231, which are finally mixed to form fresh air that flows through the air inlet 10 into the furnace 2.

[0041] A circulating fan is arranged at the air inlet of the furnace, and the air leaving through the connecting damper and the return air inside the furnace can be mixed again to form circulating air, which is transported into the furnace chamber by the circulating fan and then expelled through an air nozzle.

[0042] The foregoing merely describes specific embodiments of the present disclosure, which are not intended to limit the scope of protection of the present disclosure. All modifications, equivalent variations, or substitutions and improvements made in the spirit and principle of the present disclosure by those skilled in the art, in accordance with the disclosed technical field, should be included within the scope of protection of the present disclosure.

Claims

Claims

1. A drying apparatus comprising at least one oven and an external circulation system for supplying hot air to the interior of the oven, wherein the external circulation system comprises a heater, an air duct and a connecting damper; wherein the air duct comprises a high-temperature air duct and a low-temperature air duct; an outlet of the high-temperature air duct and an outlet of the low-temperature air duct are connected to the oven via the connecting damper, and an inlet of the high-temperature air duct and an inlet of the low-temperature air duct are in communication with outside air via a fresh air blower;and wherein the heating device is arranged on the pipeline of the high-temperature air duct to heat fresh air entering the high-temperature air duct, and an air flow rate ratio between the high-temperature air duct and the low-temperature air duct is controlled by adjusting the connecting damper, thereby regulating the mixing temperature of the high-temperature air and the low-temperature air.;

2. A drying apparatus according to claim 1, wherein the external circulation system further comprises a heat exchanger for waste heat recovery, the inlet of which is connected to the outlet of the fresh air blower and the outlet of which is connected to the inlet of the high temperature air duct and the inlet of the low temperature air duct.

3. A drying apparatus according to claim 2, wherein the oven comprises an exhaust duct, which communicates with the waste heat recovery heat exchanger and an exhaust fan, and the exhaust fan is used to discharge exhaust air which has undergone heat exchange with fresh air in the waste heat recovery heat exchanger.

4. A drying apparatus according to claim 2, further comprising a filter, wherein the fresh air blower is in communication with outside air through the filter.

5. A drying apparatus according to claim 3, wherein the extraction duct, the high temperature air duct and the low temperature air duct Low temperature ovens are equipped with a temperature sensor and a pressure sensor, and the oven is equipped with a temperature sensor and a pressure sensor inside, so that the temperature and pressure are detected at all points.

6. A drying apparatus according to claim 1, wherein the external circulation system further comprises a circulation fan, which is connected to an outlet of the crossover register and mixes mixed air at the outlet of the crossover register with return air inside the oven and transports it to a chamber inside the oven.

7. A drying apparatus according to claim 2, wherein the oven comprises an exhaust duct and a condenser, and an exhaust air from the exhaust duct is discharged into the condenser via the waste heat recovery heat exchanger, and then discharged to the outside environment through the condenser or continues to participate in circulation.

8. A drying apparatus according to claim 7, wherein an outlet of the condenser is in communication with an NMP recuperator which, in turn, is in communication with the external environment.

9. A drying apparatus according to claim 7, wherein the heating device is provided with a U-shaped heating tube or a natural gas burner, and the front and rear of the heating device are provided with a flame arrester.

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