Electromagnetic induction heating supercritical drying device

Abstract

The electromagnetic induction heating supercritical drying device comprises a drying kettle body, the drying kettle body comprises a kettle cover, a heating device and a cooling device, and the kettle wall is provided with a heat preservation and insulation layer, an electromagnetic induction heating coil and a reaction contact layer from outside to inside. The heating device comprises an electromagnetic heating wire, an electromagnetic heating interface, a heater wire, a temperature detection signal line and an electromagnetic induction heating controller, electromagnetic induction heating coils are adopted for heating, the segmented heating coils are controlled by the digital electromagnetic heating controller, the control mode is high in automation degree, manual adjustment is not needed, and the heating efficiency is greatly improved. The possibility of misoperation in the production process is reduced, the energy consumption is greatly reduced compared with a resistance wire heating mode and a heat conduction oil heating mode, and the later maintenance cost is lower compared with the maintenance cost of the resistance wire heating mode and the heat conduction oil heating mode.

Description

Technical Field

[0001] The present invention relates to the field of aerogel drying process equipment, and in particular to an electromagnetic induction heating alcohol supercritical drying device. Background Art

[0002] Supercritical drying is the oldest and most mature aerogel drying process. Drying temperatures typically range from 10°C to 50°C above the critical temperature, and drying pressures range from 1 to 3 MPa above the critical pressure. Variations in temperature and pressure can alter the density of the supercritical fluid over a wide range, ultimately affecting the specific surface area and pore structure of the aerogel, resulting in the production of aerogels with superior structure and performance. Due to the high critical temperatures and pressures of common solvents, alcohols (such as methanol, ethanol, isopropanol, n-propanol, isobutanol, n-butanol, and sec-butanol) or carbon dioxide are commonly used as drying media. Ethanol, with a critical temperature of 243°C and a critical pressure of 6.38 MPa, is a preferred drying medium. Currently, ethanol is the most commonly used drying medium in aerogel production, and the following examples will use ethanol as the drying medium. The heating method used in ethanol supercritical drying is typically resistance wire heating or thermal oil heating. Resistance wire heating involves passing an electric current through the wire, generating heat through the current, which is then transferred to the drying vessel wall. However, the maximum heat utilization rate achieved with this type of resistance wire heating is only around 50%. The non-stirring high-pressure reaction drying kettle uses oil bath circulation heating, with oil pipes installed on the kettle wall for heating. Thermal oil heating involves heating the thermal oil to the appropriate temperature, then flowing through the drying kettle body through a thermal oil coil to transfer heat to the drying kettle wall. This thermal oil heating method typically requires a heating and cooling time of more than 10 hours. Due to the expansion of aerogel production and the increase in civilian demand, higher heating efficiency is required for supercritical drying. The heating method currently used in the production process is no longer able to meet this demand, and a more efficient and environmentally friendly heating device is currently needed. Summary of the Invention

[0003] The technical problem to be solved by this solution is to overcome the deficiencies and defects mentioned in the above background technology and provide a

[0004] In order to solve the above technical problems, the technical solutions proposed in this plan are:

[0005] A supercritical drying device with electromagnetic induction heating includes a drying kettle body, which includes a kettle wall, a kettle cover, a heating device, and a cooling device. The kettle wall is provided with a heat insulation layer, an electromagnetic heating coil, and a reaction contact layer from the outside to the inside.

[0006] In one embodiment, a sealing ring is provided on the kettle cover, and a latch is provided at the connection between the kettle body and the kettle cover.

[0007] In one embodiment, a pressure relief port and a medium injection port are provided on the upper portion of the kettle body.

[0008] In one embodiment, the heating device includes an electromagnetic heating wire, an electromagnetic heating interface, a heater wire, a temperature detection signal line, and an electromagnetic induction heating controller. The heater wire is connected to the electromagnetic heating wire through the electromagnetic heating interface provided on the kettle body. The heater wire is also connected to the electromagnetic induction heating controller. The electromagnetic heating wire is wound around the wall of the drying kettle as an electromagnetic heating coil; the temperature detection signal line connects the electromagnetic induction heating controller and the electromagnetic heating wire.

[0009] In one embodiment, the cooling device includes a cooling water pipe and a cooling water circulation pipe joint; the cooling water pipe is spirally wound around the wall of the drying kettle along the winding direction of the electromagnetic heating wire, is located between adjacent spiral layers of the electromagnetic heating wire, and is connected end to end to the bottom of the kettle body through the cooling water circulation pipe joint, and a gas cooling port is opened at the bottom of the kettle body.

[0010] In one embodiment, the electromagnetic heating coils are provided in several groups, and the number of groups is set according to the volume of the drying kettle and the power required for drying.

[0011] In one embodiment, the electromagnetic heating coils are set into four groups, including a first heating coil, a second heating coil, a third heating coil, and a fourth heating coil. The power of the first heating coil is 40KW, the power of the second heating coil is 40KW, the power of the third heating coil is 30KW, and the power of the fourth heating coil is 30KW.

[0012] In one embodiment, the electromagnetic heating coils are arranged into six groups, including a first heating coil, a second heating coil, a third heating coil, a fourth heating coil, a fifth heating coil, and a sixth heating coil. The power of the first heating coil is 60KW, the power of the second heating coil is 60KW, the power of the third heating coil is 40KW, the power of the fourth heating coil is 40KW, the power of the fifth heating coil is 30KW, and the power of the sixth heating coil is 30KW.

[0013] In one embodiment, the electromagnetic heating coil is a copper tube, and the kettle body is a cylindrical container.

[0014] In one embodiment, the thermal insulation layer is an aerogel felt thermal insulation material, and the reactive contact layer is a carbon steel material coated with stainless steel.

[0015] The electromagnetic induction heating coil in this solution is a copper tube. To minimize heat dissipation, cooling water flows through the tube during heating. Furthermore, the kettle body is cooled by forced nitrogen gas flow, with a nitrogen cooling port located at the bottom of the kettle. The main difference between this solution and supercritical drying kettles heated by resistance wire or thermal oil is the inclusion of an electromagnetic induction heating coil.

[0016] The principle of electromagnetic induction heating is to generate an alternating magnetic field through the components of the electronic circuit board, causing the surface of the iron container to cut the alternating magnetic lines of force, causing an alternating current to be generated in the metal at the bottom of the iron container. Under the influence of the alternating current, the carriers at the bottom of the iron container move at high speed and irregularly. The movement of the carriers causes collision and friction with the atoms, generating heat energy, thereby heating the iron container. Electromagnetic induction heating technology heats the iron container itself and is a direct heating method with a particularly high heat conversion rate. After the heating is started in this solution, the electronic switch components in the electromagnetic induction heating control cabinet generate an alternating magnetic field in the copper tube, and the kettle body itself generates alternating current and eddy currents. Under the influence of the eddy currents, the kettle body itself heats up and the temperature inside the kettle is raised to the temperature required for the supercritical state of the alcohol.

[0017] Compared with the existing technology, the beneficial effects of this solution are:

[0018] 1. The electromagnetic induction heating method of this scheme is to greatly reduce the time required for the supercritical alcohol drying kettle to heat up during the heating stage. The heating efficiency and safety are higher than the previous traditional heating methods.

[0019] 2. This solution uses electromagnetic induction heating coils for heating. The segmented heating coils are individually controlled by digital electromagnetic heating controllers. This control method has a high degree of automation. During the entire production process, the operator only needs to press the motor heating start button on the control computer, and the automated program will run and stop autonomously. In the event of an emergency, heating will automatically stop. No manual adjustment is required, which reduces the possibility of misoperation during production and ensures the stability of each kettle product. Energy consumption is also greatly reduced compared to resistance wire heating and thermal oil heating. Later maintenance costs are also lower than those of resistance wire heating and thermal oil heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present solution or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present solution. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 Structural diagram of the supercritical drying device using electromagnetic induction heating according to Example 1 of this solution;

[0022] Figure 2 This is a structural diagram of a supercritical drying device using electromagnetic induction heating according to Example 2 of this solution;

[0023] Figure 3 This is a top-down hierarchical structure diagram of the electromagnetic induction heating supercritical drying device of Examples 1 and 2 of this solution;

[0024] Figure 4 This is a heating time temperature rise rate diagram of Example 1 of this scheme;

[0025] Figure 5 This is a heating time temperature rise rate diagram of Example 2 of this scheme;

[0026] Figure 6 This is the heating time and temperature rise rate diagram of the non-stirring high-pressure reaction drying kettle with oil bath circulation heating in this scheme.

[0027] Figure numerals: 101: kettle cover, 102: sealing ring, 103: latch, 201: medium injection port, 202: pressure relief port, 203: kettle body, 2031: reaction contact layer, 2032: electromagnetic heating coil, 2033: thermal insulation layer, 204: gas cooling port, 301: first coil 301, 302: second coil, 303: third coil, 304: fourth coil, 305: fifth coil, 306: sixth coil, 401: cooling water pipe, 402: cooling water circulation pipe joint, 403: electromagnetic heating wire, 404: electromagnetic heating interface, 405: heater wire, 406: temperature detection signal line, 407: electromagnetic induction heating controller. DETAILED DESCRIPTION

[0028] To facilitate understanding of the present solution, the present solution will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments of the specification, but the scope of protection of the present solution is not limited to the following specific embodiments.

[0029] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this solution.

[0030] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this scheme can be purchased from the market or prepared by existing methods.

[0031] Example 1:

[0032] A supercritical drying device with electromagnetic induction heating, see Figure 1, including a drying kettle body 203, the drying kettle body 203 includes a kettle wall, a kettle cover 101, a heating device, and a cooling device. The kettle wall is provided with a thermal insulation layer 2033, an electromagnetic induction heating coil 2032, and a reaction contact layer 2031 from the outside to the inside. The cooling device includes a cooling water pipe 401 and a cooling water circulation pipe joint 402; the cooling water pipe 401 is spirally wound around the drying kettle wall along the winding direction of the electromagnetic heating wire 403, is located between adjacent spiral layers of the electromagnetic heating wire 403, and is connected end to end to the bottom of the kettle body 203 through the cooling water circulation pipe joint 402. A gas cooling port 204 is opened at the bottom of the kettle body 203.

[0033] A sealing ring 102 is provided on the kettle cover 101 , and a latch 103 is provided at the connection between the kettle body 203 and the kettle cover 101 .

[0034] A pressure relief port 202 and a medium injection port 201 are provided on the upper portion of the kettle body 203 .

[0035] The heating device includes an electromagnetic heating wire 403, an electromagnetic heating interface 404, a heater wire 405, a temperature detection signal line 406, and an electromagnetic induction heating controller 407. The heater wire 405 is connected to the electromagnetic heating wire 403 through the electromagnetic heating interface 404 provided on the kettle body 203. The heater wire 405 is also connected to the electromagnetic induction heating controller 407. The electromagnetic heating wire 403 is wound around the wall of the drying kettle as an electromagnetic heating coil 2032; the temperature detection signal line 406 connects the electromagnetic induction heating controller 407 and the electromagnetic heating wire 403.

[0036] The electromagnetic heating coils 2032 are provided in a plurality of groups, and the number of groups is set according to the volume of the drying kettle and the power required for drying.

[0037] The drying kettle body 203 has a volume of 1000L and is equipped with four sets of electromagnetic heating coils 2032, including a first heating coil, a second heating coil, a third heating coil, and a fourth heating coil. The power of the first heating coil 301 is 40KW, the power of the second heating coil 302 is 40KW, the power of the third heating coil 303 is 30KW, and the power of the fourth heating coil 304 is 30KW.

[0038] The heating coil is a copper tube, and the kettle body 203 is a cylindrical container.

[0039] The thermal insulation layer 2033 is an aerogel felt thermal insulation material, and the reaction contact layer 2031 is a carbon steel material with a stainless steel coating.

[0040] According to the product process requirements, the kettle is filled to 40% capacity and maintained at 270°C and 12MPa for 24 hours. After opening the drying kettle lid 101 and loading 180L of material to be dried, the lid 101 is closed until the latch 103 stops. 220L of ethanol is injected through the upper medium injection port 201 to ensure that the sum of the material and medium meets 40% of the kettle capacity. Cooling water is introduced into the electromagnetic heating coil 2032, and the drying process parameters are set on the electromagnetic induction heating controller 407 as follows: 35°C (room temperature) is increased to 270°C at 1°C / min, and the pressure is maintained at 12MPa for 24 hours. After the insulation and pressure maintenance is completed, the equipment automatically opens the pressure relief port 202 above the kettle body 203 and slowly releases the pressure at 3MPa / h. After 4 hours, the pressure is released and the coil heating is turned off. Nitrogen is introduced into the cooling nitrogen port at the bottom of the kettle body 203 to accelerate the cooling of the kettle body 203. When the temperature of the kettle body 203 drops to 60°C, the kettle cover 101 can be opened and the material can be taken out. The supercritical drying process is completed.

[0041] Example 2:

[0042] A supercritical drying device with electromagnetic induction heating, see Figure 2 , including a drying kettle body 203, the drying kettle body 203 includes a kettle wall, a kettle cover 101, a heating device, and a cooling device. The kettle wall is provided with a thermal insulation layer 2033, an electromagnetic induction heating coil 2032, and a reaction contact layer 2031 from the outside to the inside. The cooling device includes a cooling water pipe 401 and a cooling water circulation pipe joint 402; the cooling water pipe 401 is spirally wound around the drying kettle wall along the winding direction of the electromagnetic heating wire 403, is located between adjacent spiral layers of the electromagnetic heating wire 403, and is connected end to end to the bottom of the kettle body 203 through the cooling water circulation pipe joint 402. A gas cooling port 204 is opened at the bottom of the kettle body 203.

[0043] A sealing ring 102 is provided on the kettle cover 101 , and a latch 103 is provided at the connection between the kettle body 203 and the kettle cover 101 .

[0044] A pressure relief port 202 and a medium injection port 201 are provided on the upper portion of the kettle body 203 .

[0045] The heating device includes an electromagnetic heating wire 403, an electromagnetic heating interface 404, a heater wire 405, a temperature detection signal line 406, and an electromagnetic induction heating controller 407. The heater wire 405 is connected to the electromagnetic heating wire 403 through the electromagnetic heating interface 404 provided on the kettle body 203. The heater wire 405 is also connected to the electromagnetic induction heating controller 407. The electromagnetic heating wire 403 is wound around the wall of the drying kettle as an electromagnetic heating coil 2032; the temperature detection signal line 406 connects the electromagnetic induction heating controller 407 and the electromagnetic heating wire 403.

[0046] The electromagnetic heating coils 2032 are provided in a plurality of groups, and the number of groups is set according to the volume of the drying kettle and the power required for drying.

[0047] The drying kettle body 203 has a volume of 1000L and is equipped with four groups of electromagnetic heating coils 2032, including a first heating coil, a second heating coil, a third heating coil, a fourth heating coil, a fifth heating coil, and a sixth heating coil. The power of the first heating coil 301 is 60KW, the power of the second heating coil 302 is 60KW, the power of the third heating coil 303 is 40KW, the power of the fourth heating coil 304 is 40KW, the power of the fifth heating coil 305 is 30KW, and the power of the sixth heating coil 306 is 30KW.

[0048] The thermal insulation layer 2033 is an aerogel felt thermal insulation material, and the reaction contact layer 2031 is a carbon steel material with a stainless steel coating.

[0049] According to the product process requirements, the kettle is filled with 50% of the material and maintained at 270°C for 20 hours. After opening the drying kettle lid 101 and loading 550L of the material to be dried, the lid 101 is closed until the latch 103 is in the position, and 450L of ethanol is injected through the upper medium injection port 201 to ensure that the sum of the material and the medium meets 50% of the kettle filling volume; cooling water is introduced into the electromagnetic heating coil 2032, and the drying process parameters are set in the electromagnetic induction heating controller 407 as follows: 35°C (room temperature) is increased to 270°C at 1°C / min and the pressure is 12MPa. After maintaining the temperature and pressure for 48 hours, the equipment automatically opens the pressure relief port 202 above the kettle body 203 and slowly releases the pressure at 3MPa / h; after 2 hours, the pressure relief rate is adjusted to 1MPa / h, and after 6 hours, the pressure relief is completed and the coil heating is turned off. Nitrogen is introduced into the cooling nitrogen port at the bottom of the kettle body 203 to accelerate the cooling of the kettle body 203. When the temperature of the kettle body 203 drops to 60°C, the kettle cover 101 can be opened and the material can be taken out. The supercritical drying process is completed.

[0050] This solution uses nitrogen for forced cooling. The cooling nitrogen port is opened, nitrogen is filled in, and the pressure relief port 202 is opened at the same time to keep the pressure in the kettle unchanged. When the nitrogen density is high, the ability to remove heat through the vent channel is stronger, so that the kettle body 203 is cooled quickly. While ensuring the cooling efficiency, it is safer than the cooling method using thermal oil.

[0051] The time it takes to heat a supercritical drying kettle from room temperature to 260°C using electromagnetic induction heating is about four hours, while the time it takes to heat a supercritical drying kettle using thermal oil heating is twelve hours. Figure 4 and Figure 5The heating curve shows that before heating begins and the lower temperature approaches the supercritical temperature of the medium, there is a large temperature difference between the upper and lower temperatures within the kettle. However, as the lower temperature approaches the supercritical temperature of the medium, the upper temperature of the kettle rises sharply and quickly reaches the same level as the lower temperature. Temperature balance within the kettle is guaranteed under the supercritical state. Furthermore, due to the significant reduction in heating time, the production process according to this solution can achieve two kettles in three days. Each kettle only takes an average of sixteen hours, while heating with thermal oil requires twelve hours. In comparison, the product output of the supercritical drying kettle using electromagnetic induction heating is higher than that of the supercritical drying kettle using thermal oil.

[0052] This solution also greatly reduces energy consumption compared to resistance wire heating and thermal oil heating. Electromagnetic induction heating is a direct heating method. The temperature of the electromagnetic induction coil is only a few dozen degrees, and the heating energy conversion efficiency reaches 90% to 95%. The energy of electromagnetic heating acts directly on the kettle body, reducing the heat energy loss of heat transfer. Figure 6 It can be seen that there is a significant temperature difference between the thermal oil temperature and the kettle temperature of the thermal oil supercritical dryer. Energy is already lost in the process of heating the thermal oil before it is delivered to the dryer through the oil pipeline. The actual temperature of the thermal oil reaching the dryer is lower than the temperature at the exit of the tank. Combined with the heat energy loss from heat transfer, the energy consumption of thermal oil heating is significantly higher than that of electromagnetic induction heating. Furthermore, due to this heat loss, thermal oil heating cannot directly control the kettle temperature, resulting in low temperature control accuracy. Electromagnetic heating, on the other hand, is highly accurate because the heating coil itself does not generate heat, resulting in minimal thermal retardation and low thermal inertia. The inner and outer walls of the dryer are essentially the same temperature, enabling accurate and real-time temperature control. Furthermore, in terms of environmental protection, the high heat loss of thermal oil can lead to high temperatures near the dryer and the oil pipeline. The electromagnetic induction heating coil, with its external insulation layer, significantly reduces the ambient temperature of the dryer during heating, improving the working environment at the production site.

[0053] This solution also offers lower maintenance costs than both resistance-wire heating and thermal oil heating. Since the heating coil operates at only a few tens of degrees, there's no risk of damage or scaling. No maintenance or secondary coil replacement is required, resulting in a long service life. Furthermore, the lack of external heating piping reduces maintenance costs. In contrast, resistance-wire heating heats the wire to a specified temperature, which can easily lead to scaling and burnout from prolonged high-temperature operation. Common heating coils typically have a service life of around six months, making maintenance a significant undertaking. Thermal oil heating requires careful consideration of its quality, requiring regular testing. Prolonged operation can lead to deterioration in quality, and in severe cases, carbonization, which can clog the oil pipeline. Therefore, the oil pipelines used in thermal oil heating require regular maintenance and oil replacement to ensure high quality.

[0054] This solution utilizes electromagnetic induction heating coils, each segmented by a digital electromagnetic heating controller. This control method offers a high degree of automation. Throughout the production process, the operator simply presses the motor heating start button on the control computer, and the automated program automatically runs and stops, even automatically stopping heating in the event of an emergency. This eliminates the need for manual adjustments, reducing the possibility of operational errors and ensuring the stability of each batch of product.

Claims

1. A supercritical drying device using electromagnetic induction heating, characterized in that: The invention comprises a drying kettle body, which comprises a kettle wall, a kettle cover, a heating device and a cooling device. The kettle wall is provided with a thermal insulation layer, an electromagnetic heating coil and a reaction contact layer from the outside to the inside. The cooling device comprises a cooling water pipe and a cooling water circulation pipe joint. The cooling water pipe is wound around the outer wall of the kettle body and is connected end to end to the bottom of the kettle body through the cooling water circulation pipe joint. A gas cooling port is provided at the bottom of the kettle body.

2. The supercritical drying device of electromagnetic induction heating according to claim 1, characterized in that: A sealing ring is provided on the kettle cover, and a latch is provided at the connection between the kettle body and the kettle cover.

3. The supercritical drying device of electromagnetic induction heating according to claim 1, characterized in that: The upper part of the kettle body is provided with a pressure relief port and a medium injection port.

4. The supercritical drying device of electromagnetic induction heating according to claim 1, characterized in that: The heating device includes an electromagnetic heating wire, an electromagnetic heating interface, a heater wire, a temperature detection signal line, and an electromagnetic induction heating controller. The heater wire is connected to the electromagnetic heating wire through the electromagnetic heating interface provided on the kettle body. The heater wire is also connected to the electromagnetic induction heating controller. The electromagnetic heating wire is wound around the wall of the drying kettle as an electromagnetic heating coil; the temperature detection signal line connects the electromagnetic induction heating controller and the electromagnetic heating wire.

5. The supercritical drying device of electromagnetic induction heating according to claim 1, characterized in that: The electromagnetic heating coils are arranged in several groups, and the number of groups is set according to the volume of the drying kettle and the power required for drying.

6. The supercritical drying device of electromagnetic induction heating according to claim 5, characterized in that: The electromagnetic heating coils are set to four groups, including a first heating coil, a second heating coil, a third heating coil, and a fourth heating coil. The power of the first heating coil is 40KW, the power of the second heating coil is 40KW, the power of the third heating coil is 30KW, and the power of the fourth heating coil is 30KW.

7. The supercritical drying device of electromagnetic induction heating according to claim 5, characterized in that: The electromagnetic heating coils are set to six groups, including a first heating coil, a second heating coil, a third heating coil, a fourth heating coil, a fifth heating coil, and a sixth heating coil. The power of the first heating coil is 60KW, the power of the second heating coil is 60KW, the power of the third heating coil is 40KW, the power of the fourth heating coil is 40KW, the power of the fifth heating coil is 30KW, and the power of the sixth heating coil is 30KW.

8. The electromagnetic induction heating supercritical drying device according to claim 1, characterized in that: The electromagnetic heating coil is a copper tube, and the kettle body is a cylindrical container.

9. The supercritical drying device of electromagnetic induction heating according to claim 1, characterized in that: The thermal insulation layer is an aerogel felt thermal insulation material, and the reaction contact layer is a carbon steel material with a stainless steel coating.

Images