A device and method for removing oil from fried food

Abstract

This invention discloses an oil removal device and method for fried foods. The oil removal device includes a frame and an upper chamber, a middle chamber, and a lower chamber arranged sequentially from top to bottom. Each chamber is equipped with a conveying mechanism and connected by a transfer trough with a rotary airlock discharge valve, enabling continuous production and maintaining pressure isolation between the chambers. The upper chamber forms a microcrystalline frozen layer on the food surface through an ultra-low temperature spray mechanism. The middle chamber causes oil to migrate to the surface under the action of a vacuum system and a heating mechanism. The lower chamber peels off the surface oil through a pulsed airflow jet device. This invention solves the problems of difficult vacuum isolation and discontinuous production in existing equipment through a three-layer vertical layout and airlock design, combined with freeze-drying and other technologies. It has the advantages of high oil removal efficiency, oil recovery, good food quality, and low energy consumption.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to an oil removal device and method for fried foods, and particularly to a continuous oil removal device and method that employs the synergistic effect of freeze drying and pulsed airflow stripping. Background Technology

[0002] Fried foods are loved by consumers for their crispy texture and unique flavor, but traditional fried foods have a high oil content (usually 15% to 40%), and excessive consumption is detrimental to health. Existing oil removal technologies mainly include centrifugal oil removal, hot air oil removal, vacuum oil removal, and freeze-drying oil removal.

[0003] The problems with existing technologies are mainly reflected in the following three aspects: First, production is discontinuous and oil removal efficiency is low. Centrifugal oil removal can only remove surface free oil, and its effect on removing internal oils from porous foods is poor, and it easily causes food breakage; hot air oil removal is prone to oil oxidation and acrylamide formation due to high temperatures, resulting in high energy consumption; vacuum oil removal can reduce the degree of oxidation, but its oil removal efficiency is limited; freeze-drying oil removal uses overall freezing, which has high energy consumption, long cycle time, and low oil migration efficiency. At the same time, existing equipment is mostly operated intermittently, with each process carried out at different times, resulting in low equipment utilization and difficulty in matching the continuous output rhythm of the frying production line.

[0004] Secondly, vacuum isolation is difficult and energy consumption is high. There is a lack of reliable continuous material conveying and sealing devices between the process unit that needs to maintain a vacuum environment and the atmospheric pressure unit, which leads to the need for repeated evacuation of the vacuum system, resulting in high energy consumption and low efficiency.

[0005] Third, inadequate oil collection leads to resource waste. The oil produced during the degreasing process lacks a dedicated collection system, causing it to accumulate at the bottom of the tank, affecting heat transfer and hygiene, and resulting in resource waste.

[0006] Therefore, there is an urgent need for a device and method for removing oil from fried foods that can achieve continuous production, reliable vacuum isolation, high oil removal efficiency, and perfect oil collection. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to provide an oil removal device and method for fried foods. This invention achieves continuous production through a three-layer vertical layout and a rotary airlock unloading valve, enabling surface microcrystallization, vacuum sublimation oil removal, and pulsed airflow stripping. This solves the problems of difficult vacuum isolation, mutually restrictive process parameters, and low oil removal efficiency in existing equipment. Simultaneously, by incorporating an oil collection system, side baffles, a rotary airlock unloading valve, and a pressure control mechanism, the invention improves oil recovery rate, material conveying stability, and equipment operational reliability.

[0008] The objective of this invention is achieved through the following technical solution: This invention first provides an oil removal device for fried foods, including a frame and a control system. Three compartments are installed within the frame, arranged from top to bottom as an upper compartment, a middle compartment, and a lower compartment. Each of the three compartments is equipped with a conveying mechanism. The upper compartment has an ultra-low temperature spraying mechanism above its conveying mechanism, a feeding trough at the top of the upper compartment above the feeding end of its internal conveying mechanism, and a first transfer trough at the bottom of the upper compartment below the unloading end of its internal conveying mechanism. The middle compartment has a heating mechanism above its conveying mechanism and is connected to a vacuum system. The lower end of the first transfer trough penetrates the middle compartment and extends above the feeding end of its internal conveying mechanism. A second transfer trough is located at the bottom of the middle compartment below the unloading end of its internal conveying mechanism. The lower compartment has a pulsed airflow jetting device above its conveying mechanism. The lower end of the second transfer trough penetrates the lower compartment and extends above the feeding end of its internal conveying mechanism. An unloading trough is located at the bottom of the lower compartment below the unloading end of its internal conveying mechanism. Rotary airlock unloading valves are installed in the feeding trough, the first transfer trough, the second transfer trough, and the unloading trough. The control system is electrically connected to each conveying mechanism, the cryogenic spraying mechanism, the heating mechanism, the pulsed airflow injection device, the vacuum system, and each rotary airlock unloading valve.

[0009] Furthermore, the upper chamber is also provided with a first exhaust mechanism, which includes an exhaust port, an exhaust pipe and a regulating valve. A pressure sensor is provided in the upper chamber, and the control system adjusts the opening of the regulating valve according to the feedback of the pressure sensor to maintain the pressure inside the chamber within the range of 101 kPa to 104 kPa.

[0010] Furthermore, the bottom of the middle compartment is provided with a first oil collection system, and the lower compartment is provided with a second oil collection system.

[0011] Furthermore, side baffles are installed on both sides of the conveyor mechanism inside each cabin, and the side baffles fit snugly against the inner wall of the cabin they are in.

[0012] Furthermore, the cryogenic spray mechanism includes a liquid nitrogen storage tank, a compressed air pipeline, a gas-liquid mixing chamber, a nozzle array, a flow regulating valve, and a pulse control valve. The liquid nitrogen storage tank is located outside the frame and connected to the gas-liquid mixing chamber via a liquid nitrogen delivery pipeline. The compressed air pipeline is connected to the gas-liquid mixing chamber. The gas-liquid mixing chamber is suspended at the top of the upper chamber and located directly above the conveying mechanism inside the upper chamber. The nozzle array is installed below the gas-liquid mixing chamber at a 15° angle to the vertical direction. The cryogenic spray mechanism adopts an intermittent spraying method, and the spraying cycle is linked to the conveying speed of the conveying mechanism inside the upper chamber.

[0013] Furthermore, the vacuum system includes a suction pipe, a vacuum pump, and a cold trap. The middle chamber is equipped with a resistance gauge and an ionization gauge. The resistance gauge is used for pressure monitoring during the vacuuming stage, and the ionization gauge is used for precise pressure control during the sublimation stage.

[0014] Furthermore, the pulsed airflow injection device includes an air source, a second pulse control valve, a distribution pipe, and a second nozzle array; the air source is a nitrogen storage tank, located outside the lower compartment; the distribution pipe is installed on the top inside the lower compartment; the second pulse control valve is installed outside the lower compartment, with its inlet end connected to the air source and its outlet end connected to the distribution pipe via a through-chamber connector; the second nozzle array is installed on the distribution pipe via a spherical hinge joint and is located directly above the third conveying mechanism, at a 45° angle to the vertical direction, and its injection direction is opposite to the conveying direction of the conveying mechanism inside the lower compartment.

[0015] Furthermore, the rotary airlock unloading valve includes a valve body, a rotary impeller and a motor. The rotary impeller adopts a wide blade structure with an arc-shaped groove on the blade surface. The gap between the rotary impeller and the valve body is 2 mm to 5 mm. The inner wall of the valve body is provided with an elastic sealing strip.

[0016] Furthermore, the lower compartment is also provided with a second exhaust mechanism, which includes an exhaust pipe installed on the lower compartment and connected to the interior of the lower compartment, and a one-way exhaust valve installed on the exhaust pipe. The opening pressure of the one-way exhaust valve is 101.3 kPa to 105 kPa.

[0017] The present invention also provides a method for removing oil from fried foods using the above-described apparatus, comprising the following steps: S1. Continuous feeding step: The fried food enters the upper chamber through the feeding trough and falls onto the conveyor mechanism inside the upper chamber.

[0018] S2. Surface microcrystallization step: During the process of food being transported on the conveyor mechanism in the upper chamber, the ultra-low temperature spray mechanism sprays ultra-low temperature cooling medium onto the food surface, causing a microcrystalline frozen layer to form on the food surface.

[0019] S3. First airlock conveying step: The food after surface microcrystallization treatment falls into the conveying mechanism in the middle compartment through the first transfer trough.

[0020] S4. Vacuum sublimation step: During the process of food being transported on the conveyor mechanism in the middle chamber, the middle chamber is kept in a vacuum state. At the same time, the heating mechanism heats the food, causing the water inside the food to sublimate and escape, and driving the internal oil to migrate to the surface.

[0021] S5. Second airlock conveying step: The food after vacuum sublimation treatment falls into the conveying mechanism in the lower chamber through the second transfer tank.

[0022] S6. Airflow stripping step: During the process of food being transported on the conveyor mechanism in the lower chamber, a pulsed airflow jet device sprays pulsed airflow onto the surface of the food, blowing off the free oil that has migrated to the surface.

[0023] S7. Continuous discharge step: The deoiled food is conveyed to the discharge chute by the conveyor mechanism in the lower chamber and discharged out of the device through the discharge chute.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) Continuous production: Through the three-layer vertical layout and the airlock design of four rotary airlock unloading valves, the entire process of feeding, processing and discharge is continuously operated, and the production capacity is increased by 2 to 3 times, which can match the continuous discharge rhythm of the frying production line.

[0025] (2) Completely solve the vacuum isolation problem: The three chambers are independent of each other. The middle chamber is isolated from the upper and lower chambers through the rotary airlock unloading valve in the first and second transfer slots. The gap between the rotating impeller and the valve body forms a labyrinth-type air seal. The vacuum degree of the middle chamber is stable and undisturbed, and there is no need to repeatedly pump vacuum, reducing energy consumption by more than 40%.

[0026] (3) Independent optimization of process parameters: The temperature, pressure and conveying speed of each chamber can be adjusted independently without interference. The upper chamber can be sprayed quickly (completed in 10-30 seconds), the middle chamber can be sublimated slowly (processing time of 2-4 hours), and the lower chamber can be peeled off quickly (processing time of 5-10 minutes). Dynamic matching is achieved by rotating the airlock unloading valve.

[0027] (4) High oil removal efficiency: Based on freeze-drying technology, the oil migrates to the surface through surface microcrystallization and vacuum sublimation, and the pulsed airflow actively removes the surface oil.

[0028] (5) Improved grease collection: The middle compartment is equipped with a first grease collection system to collect grease dripping during vacuum sublimation, and the lower compartment is equipped with a second grease collection system to collect grease blown off during airflow stripping. The total grease recovery rate is over 85%, reducing pollution inside the compartment and realizing resource recycling.

[0029] (6) Stable material conveying: Side baffles that fit against the inner wall of the cabin are installed on both sides of each conveying mechanism to effectively prevent food from falling off the edge of the conveyor belt, reducing the drop rate by more than 95%, reducing material loss and equipment cleaning frequency.

[0030] (7) Anti-crushing design: The rotary lock unloading valve adopts a wide blade structure with an arc groove on the blade surface. The gap between the impeller and the valve body is increased to 2-5 mm. An elastic sealing strip is installed on the inner wall of the valve body, reducing the food breakage rate to below 0.5%.

[0031] (8) Reliable pressure control: The upper chamber is equipped with a first exhaust mechanism, which adopts pressure feedback control to maintain stable pressure inside the chamber and avoid pressure rise caused by continuous cold air injection; the lower chamber is equipped with a second exhaust mechanism to automatically maintain normal pressure and ensure the stripping effect of pulse airflow.

[0032] (9) Reasonable surface microcrystalline layer treatment: During the vacuum sublimation process, the microcrystalline layer undergoes a gradual transformation of “dense ice crystal layer → micropore formation → micropore network expansion → thin shell formation”. It serves as a barrier layer in the initial stage to accumulate driving pressure, and as a directional channel in the subsequent stage to guide the migration of oil, ultimately transforming into a crispy thin shell of food, realizing “multiple uses of one material and dynamic transformation”.

[0033] (10) Good quality is maintained: the whole process is low temperature (not exceeding 25℃) to avoid oil oxidation and nutrient loss, and the thin shell gives the food a crispy texture.

[0034] (11) Convenient maintenance: Each compartment is equipped with an independent inspection door, which can be cleaned in sections without affecting each other, reducing maintenance time by more than 50%. Attached Figure Description

[0035] Figure 1 This is a front view of the oil removal device for fried food according to the present invention.

[0036] Figure 2 for Figure 1 A full sectional view (or a schematic diagram of the internal structure of a deep-frying food degreasing device).

[0037] Figure 3 This is a schematic diagram of the internal structure of the upper cabin described in this invention.

[0038] Figure 4 This is a schematic diagram of the internal structure of the middle compartment described in this invention.

[0039] Figure 5 This is a schematic diagram of the internal structure of the lower compartment described in this invention.

[0040] Figure 6 This is a schematic diagram of the internal structure of the rotary airlock unloading valve described in this invention.

[0041] As shown in the figure: 100-rack; 200 - Upper chamber; 210 - First conveying mechanism; 220 - Cryogenic spraying mechanism; 221 - Nozzle array one; 222 - Flow regulating valve; 223 - Compressed air pipeline; 224 - Liquid nitrogen delivery pipeline; 225 - Gas-liquid mixing chamber; 226 - Pulse control valve one; 230 - Feed trough; 240 - Rotary airlock unloading valve; 241 - Valve body; 242 - Rotary impeller; 2421 - Arc-shaped groove; 250 - First transfer trough; 260 - First exhaust mechanism; 261 - Exhaust port; 262 - Exhaust pipe; 263 - Regulating valve; 270 - Pressure sensor; 280 - Safety relief valve; 300 - Middle compartment; 310 - Second transfer mechanism; 320 - Heating mechanism; 321 - Infrared heating tube array; 330 - Vacuum system; 331 - Suction pipe; 340 - Second transfer tank; 350 - First oil collection system; 351 - First oil guide plate; 352 - First oil collection trough; 353 - First electric heat tracing insulation layer; 354 ​​- First oil drain valve; 400-Lower hull; 410-Third conveying mechanism; 420-Pulse airflow injection device; 421-Nozzle array two; 422-Air source; 423-Pulse control valve two; 424-Distribution pipe; 425-Inlet pipe; 430-Unloading trough; 440-Second exhaust mechanism; 441-Exhaust pipe; 442-One-way exhaust valve; 450-Second oil collection system; 451-Second oil guide plate; 452-Second oil collection trough; 453-Second electric heat tracing insulation layer; 454-Second oil drain valve; 500-Control System. Detailed Implementation

[0042] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0044] In the description of this invention, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" or "linked" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a mechanical connection or an electrical connection; it can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. It should be noted that the terms "comprising," "including," or any other variations are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0045] Example 1: like Figures 1 to 6 As shown, this embodiment provides an oil removal device for fried foods, including a frame 100 and a control system 500. Rack 100:

[0046] like Figure 1 and Figure 2 As shown, the frame 100 is welded from 304 stainless steel square tubing and has an overall rectangular frame structure. Inside, the upper compartment 200, middle compartment 300, and lower compartment 400 are installed sequentially along the vertical direction. A conveying mechanism is installed in each of the three compartments. The bottom of the frame 100 is provided with adjustable feet (such as threaded connections) for adjusting the levelness. Upper cabin 200:

[0047] like Figure 3 As shown, the upper chamber 200 is a rectangular parallelepiped-shaped, hollow cryogenic pretreatment chamber. Its outer shell is made of double-layer stainless steel plate structure, and the space between the double-layer stainless steel plate structure is filled with polyurethane insulation material.

[0048] The conveying mechanism installed inside the upper compartment 200 is the first conveying mechanism 210. The first conveying mechanism 210 adopts a stainless steel mesh belt conveyor, driven by a servo motor, and its speed can be steplessly adjusted within the range of 0.2 m / min to 1.0 m / min. Side baffles are provided on both sides of the first conveying mechanism 210, which are fitted against the inner wall of the upper compartment to prevent food from falling from both sides of the first conveying mechanism.

[0049] A cryogenic spray mechanism 220 is provided above the first conveying mechanism 210. The cryogenic spray mechanism 220 is used to spray cryogenic atomized gas flow onto the food surface. The cryogenic spray mechanism 220 includes a liquid nitrogen storage tank, a compressed air pipeline 223, a gas-liquid mixing chamber 225, a nozzle array 221, a flow regulating valve 222, and a pulse control valve 226.

[0050] The liquid nitrogen storage tank is located outside the upper chamber 200 and is fixed by a bracket. A weighing module is provided at the bottom. The outlet of the liquid nitrogen storage tank is connected to the liquid nitrogen inlet of the gas-liquid mixing chamber 225 through a liquid nitrogen delivery pipeline 224.

[0051] The liquid nitrogen delivery pipeline 224 adopts a double-layer vacuum insulation pipe, and a shut-off valve, a filter, a flow regulating valve 222 and an electromagnetic safety valve (the electromagnetic safety valve is set close to the liquid nitrogen storage tank) are installed on the pipeline in sequence.

[0052] The compressed air pipeline 223 is connected to the factory's compressed air network or an independent air compressor at its inlet end. It is laid along the outside of the frame 100 and enters the upper compartment 200. It is made of 304 stainless steel pipe with a diameter of DN15. An air filter, a pressure reducing valve, a pressure gauge and a pulse control valve 226 are installed sequentially on the upper end of the compressed air pipeline 223.

[0053] The gas-liquid mixing chamber 225 is suspended on the top inner side of the upper chamber 200 and located directly above the first conveying mechanism 210. It is suspended from the top of the upper chamber 200 by a hanger, and a rubber vibration damping pad is provided between the hanger and the top plate. The gas-liquid mixing chamber 225 is a cuboid structure, welded from 304 stainless steel, with a mirror-polished inner wall. Multiple atomizing nozzle cores are provided inside the chamber. The liquid nitrogen inlet of the gas-liquid mixing chamber 225 is connected to the outlet of the liquid nitrogen delivery pipeline 224 through a flange, and the compressed air inlet is connected to the outlet of the compressed air pipeline 223 through a flange. A temperature sensor is installed at the outlet of the gas-liquid mixing chamber 225.

[0054] The nozzle array 221 is installed below the gas-liquid mixing chamber 225, and is arranged at equal intervals of 100 mm along the width direction of the first conveying mechanism 210, for a total of 8 groups of nozzles. The installation height is 200 mm from the surface of the first conveying mechanism 210. Each group of nozzles includes a nozzle body, a nozzle seat, and a spherical hinge joint. The nozzle body is made of 304 stainless steel and has internal swirl vanes. The nozzle seat is connected to the outlet of the gas-liquid mixing chamber by a thread. The spherical hinge joint is located between the nozzle seat and the nozzle body. The spray direction of the nozzle is at a 15° angle to the vertical direction, facing the feed end of the first conveying mechanism 210.

[0055] The flow regulating valve 222 is installed on the liquid nitrogen delivery pipeline 224, located outside the upper chamber 200 near the outlet of the liquid nitrogen storage tank. It is an electric regulating valve and is electrically connected to the control system 500.

[0056] The pulse control valve 226 is installed on the compressed air pipeline 223, located outside the upper chamber 200 near the inlet of the gas-liquid mixing chamber 225. It is a solenoid valve and is electrically connected to the control system 500.

[0057] The cryogenic spray mechanism 220 adopts an intermittent spraying method with a spraying cycle of 5-10 seconds (spraying time of 2-5 seconds and stopping time of 3-8 seconds), a duty cycle of 30%-50%, and the spraying cycle is linked to the conveying speed of the first conveying mechanism 210.

[0058] A feed trough 230 is located on the top of the upper chamber 200, above the feed end of the first conveying mechanism 210. The feed trough 230 is funnel-shaped with a polished inner wall. A rotary airlock discharge valve 240 is installed inside the feed trough 230. Figure 6 As shown, the rotary lock air discharge valve 240 includes a valve body 241, a rotating impeller 242 disposed within the valve body 241, and a motor driving the rotating impeller 242. The rotating impeller 242 adopts a wide blade structure with arc-shaped grooves on the blade surface. The gap between the rotating impeller 242 and the valve body 241 is 3 mm. The inner wall of the valve body 241 is provided with an elastic sealing strip made of food-grade silicone rubber with a Shore A hardness of 50, which forms elastic contact with the edge of the blade of the rotating impeller 242. The motor is a variable frequency motor with a speed controlled at 5 rpm.

[0059] A first transfer trough 250 is located at the bottom of the upper chamber 200, below the unloading end of the first conveying mechanism 210; the first transfer trough 250 has a conical tapered structure. The lower end of the first transfer trough 250 extends through the middle chamber 300 and above the feeding end of the second conveying mechanism 310. A rotary airlock unloading valve is also installed in the first transfer trough 250. The structure of the rotary airlock unloading valve is the same as that of the rotary airlock unloading valve 240 in the feeding trough 230. The gap between its rotating impeller and the valve body is 3 mm, its surface is coated with Teflon, and it is equipped with an external heat insulation jacket.

[0060] The upper chamber 200 is also equipped with a first exhaust mechanism 260, which is located on the top of the upper chamber 200 away from the feed chute 230. The first exhaust mechanism 260 includes an exhaust port 261, an exhaust pipe 262, and a regulating valve 263. The exhaust pipe 262 is installed at the exhaust port 261 and communicates with the interior of the upper chamber 200. The regulating valve 263 is an electric butterfly valve, electrically connected to the control system 500. Simultaneously, a pressure sensor 270, electrically connected to the control system 500, is installed inside the upper chamber 200. The pressure sensor 270 is used to monitor the pressure inside the upper chamber 200 in real time. The control system 500 adjusts the opening of the regulating valve 263 based on the pressure signal transmitted from the pressure sensor 270, maintaining the pressure inside the chamber within the range of 101-104 kPa. The upper chamber 200 is also equipped with a mechanical safety relief valve 280, with an opening pressure of 110 kPa. This valve automatically opens to relieve pressure when the pressure inside the upper chamber 200 exceeds 110 kPa, providing overpressure safety protection. Mid-hull 300:

[0061] like Figure 4 As shown, the middle chamber 300 is a rectangular, hollow vacuum sublimation oil removal chamber. The middle chamber 300 is located below the upper chamber 200 and is made of 304 stainless steel welded structure. It is designed to withstand a pressure of 0.1 MPa (absolute pressure).

[0062] The conveying mechanism installed inside the middle compartment 300 is a second conveying mechanism 310. The second conveying mechanism 310 is a stainless steel mesh conveyor belt with many mesh holes and a Teflon anti-stick coating. It is driven by a servo motor, and its speed can be steplessly adjusted within the range of 0.1m / min to 0.5m / min. Side baffles are also provided on both sides of the second conveying mechanism 310. The side baffles are fitted to the inner wall of the middle compartment 300 to prevent food from falling from the sides of the second conveying mechanism 310.

[0063] A heating mechanism 320 is located on the top inner side of the middle hull 300, above the conveying mechanism. The heating mechanism 320 is an infrared heating tube array 321 (several infrared heating tubes), consisting of six groups arranged at equal intervals. Each group has a power of 2 kW and a temperature control range of -5℃ to 25℃, employing a segmented temperature control method. Two Pt100 thermal resistors, electrically connected to the control system 500, are mounted on the surface of the heating mechanism 320. These Pt100 thermal resistors are used to monitor the temperature of the heating elements and provide feedback to control the output power.

[0064] A vacuum system 330 is connected to the middle chamber 300; the vacuum system 330 includes an extraction pipe 331, a vacuum pump, and a cold trap. One end of the extraction pipe 331 is connected to the inner top of the middle chamber 300, and the other end is connected to the inlet of the vacuum pump; the vacuum pump is a Roots pump and rotary vane pump unit with a pumping speed of 300 L / s. The cold trap is located between the middle chamber 300 and the vacuum pump (the inlet is connected to the middle chamber 300 via the extraction pipe 331, and the outlet is connected to the inlet of the vacuum pump via the extraction pipe 331), and is a coil-type heat exchanger with a cooling temperature of -50℃.

[0065] A pressure monitoring system is installed on the intermediate chamber 300, which includes a resistance gauge, an ionization gauge, and a pressure switch. The resistance gauge is installed on the middle side wall of the intermediate chamber 300, with a measurement range of 0.1 Pa to 100 kPa, and is used for monitoring the vacuuming process. The ionization gauge is installed on the top of the intermediate chamber 300, with a measurement range of 0.001 Pa to 1 Pa, and is used for precise control of the vacuum level during the sublimation stage. The pressure switch is installed on the side wall of the intermediate chamber 300, with a set value of 50 Pa, and is interlocked with the heating mechanism 320 for safety. When the pressure exceeds the set value, the heating power is automatically turned off.

[0066] A temperature monitoring system is also installed on the middle compartment 300. This system includes three K-type thermocouples and one T-type thermocouple. The three K-type thermocouples are respectively installed at the inlet, middle, and outlet of the second conveying mechanism 310 to monitor the surface temperature of the food. The T-type thermocouple is installed at the inlet of the cold trap to monitor the temperature of the cold trap. The control system 500 controls the start and stop of the refrigeration unit of the cold trap based on the feedback signal from the T-type thermocouple to maintain the cold trap temperature below -40°C.

[0067] A second transfer trough 340 is located at the bottom of the middle chamber 300, below the unloading end of the second conveying mechanism 310. The second transfer trough 340 has a conical converging structure. The lower end of the second transfer trough 340 extends through the lower chamber 400 and above the feeding end of the third conveying mechanism 410. A rotary airlock unloading valve is also installed inside the second transfer trough 340. The rotary airlock unloading valve has the same structure as the rotary airlock unloading valve 240 in the feeding trough 230, and is used to transport the vacuum-sublimated food to the lower chamber 400 and maintain the vacuum level of the middle chamber 300 during rotation.

[0068] A first oil collection system 350 is provided at the bottom of the intermediate chamber 300. The first oil collection system 350 includes a first oil guide plate 351 and a first oil collection trough 352. The first oil guide plate 351 is a thin plate of 304 stainless steel with an inclination angle of 15°. Its surface is mirror polished and coated with Teflon. It is located directly below the second conveying mechanism 310 and is used to collect the grease dripping during the vacuum sublimation process. The first oil collection tank 352 has a V-shaped cross-section and extends along the length of the middle tank 300. It is located at the lower end of the first oil guide plate 351. The bottom of the tank is provided with a first electric heat tracing insulation layer 353, which maintains the temperature at 40℃. The lowest point of the first oil collection tank 352 is connected to a first oil drain valve 354. The first oil drain valve 354 is an electric ball valve or an electric butterfly valve and is electrically connected to the control system 500 to realize automatic control. A liquid level sensor (such as a float switch or a capacitive liquid level gauge) is installed in the first oil collection tank 352. When the oil level reaches the set value (such as when the set liquid level reaches 80% of the height of the first oil collection tank 352, oil draining is triggered, and when the set liquid level reaches 10% of the height of the first oil collection tank 352, oil draining stops).

[0069] Lower cabin 400: like Figure 5 As shown, the lower chamber 400 is a rectangular, hollow gas stripping and deoiling chamber located below the middle chamber 300. It is constructed of 304 stainless steel and is an atmospheric pressure chamber.

[0070] The conveying mechanism installed inside the lower compartment 400 is a third conveying mechanism 410. The third conveying mechanism 410 is a stainless steel mesh conveyor belt with many mesh holes. It is driven by a servo motor and adopts a stepping motion (advancing 50mm every 2 seconds, pausing for 1 second). Side baffles are also provided on both sides of the third conveying mechanism 410. The side baffles are attached to the inner wall of the lower compartment 400 to prevent food from falling from the sides of the third conveying mechanism 410.

[0071] A pulsed air jet device 420 is provided above the third conveying mechanism 410; the pulsed air jet device 420 includes an air source 422, a second pulse control valve 423, a distribution pipe 424, and a second nozzle array 421.

[0072] The gas source 422 is a nitrogen storage tank, located on the right side of the external frame of the lower compartment 400. The outlet is connected to a pressure reducing valve (pressure adjusted to 0.3-0.6 MPa), and then connected to the inlet of the pulse control valve 423 through a stainless steel inlet pipe 425. The inlet pipe 425 is equipped with a filter, a pressure gauge and a manual shut-off valve.

[0073] Pulse control valve 423 is a solenoid valve, installed outside the lower compartment 400, and electrically connected to the control system 500. Its outlet is connected to the transom connector via a stainless steel pipe. The transom connector is welded to the top of the lower compartment 400 and adopts a double-sealed structure, with the inner side connected to the distribution pipe 424.

[0074] The distribution pipe 424 is a straight pipe structure, arranged horizontally along the width direction of the third transmission mechanism 410, with both ends fixed to the inner wall of the cabin. Its inlet end is connected to the air outlet end of the pulse control valve 423. The distribution pipe 424 is provided with multiple outlets, and each outlet is connected to a nozzle through a metal hose.

[0075] The nozzle array 421 consists of 7 groups, arranged at equal intervals of 100 mm. Each group of nozzles is installed on the distribution pipe 424 via a spherical hinge joint. The spherical hinge joint is adjustable in all directions. The nozzles are at a 45° angle to the vertical direction, and the spraying direction is opposite to the conveying direction of the third conveying mechanism 410 (countercurrent blowing). The nozzles are 150 mm away from the food surface.

[0076] A discharge trough 430 is provided at the bottom of the lower compartment 400, below the discharge end of the third conveying mechanism 410; the discharge trough 430 has a conical converging structure. A rotary airlock discharge valve 4 is also installed in the discharge trough 430. The rotary airlock discharge valve 4 has the same structure as the rotary airlock discharge valve 240 of the feed trough 230 and is used to discharge the finished product.

[0077] A second exhaust mechanism 440 is provided at the top of the lower compartment 400. The second exhaust mechanism 440 includes an exhaust pipe 441 and a one-way exhaust valve 442 installed on the exhaust pipe 441. The exhaust pipe 441 is connected to the interior of the lower compartment 400. The one-way exhaust valve 442 has an opening pressure of 103 kPa and contains a lightweight valve core. When the pressure inside the compartment exceeds the opening pressure, the valve core is pushed open, and gas is discharged; when the pressure inside the compartment is lower than the opening pressure, the valve core closes to prevent external air from flowing back in.

[0078] A second oil collection system 450 is provided at the bottom of the lower compartment 400. The second oil collection system 450 includes a second oil guide plate 451 and a second oil collection trough 452. The second oil guide plate 451 is a thin 304 stainless steel plate with an inclination angle of 15°. Its surface is mirror polished and coated with Teflon. It is located directly below the third conveying mechanism 410 and is used to collect grease blown off the food surface. The second oil collection tank 452 has a V-shaped cross-section and extends along the length of the lower compartment 400. It is located at the lower end of the second oil guide plate 451. The bottom of the tank is equipped with a second electric heat tracing insulation layer 453, which maintains the temperature at 40℃. The lowest point of the second oil collection tank 452 is connected to the second oil drain valve 454. The second oil drain valve 454 is an electric ball valve or an electric butterfly valve and is electrically connected to the control system 500 to realize automatic control. A liquid level sensor (such as a float switch or a capacitive liquid level gauge) is installed in the second oil collection tank 452. When the oil level reaches the set value (such as when the set liquid level reaches 80% of the height of the second oil collection tank 452, oil draining is triggered, and when the set liquid level reaches 10% of the height of the second oil collection tank 452, oil draining stops). Control System 500:

[0079] like Figure 1 and Figure 2 As shown, the control system 500 is a PLC programmable controller, located in the control cabinet outside the frame 100, and is electrically connected to the pressure sensor 270, regulating valve 263, drive motors of the first conveying mechanism 210, second conveying mechanism 310, and third conveying mechanism 410, pulse control valve 226 and flow regulating valve 222 of the cryogenic spray mechanism 220, infrared heating tube array 321 of the heating mechanism 320, pulse control valve 423 of the pulsed airflow jet device 420, vacuum pump and refrigeration unit of the cold trap in the vacuum system 330, and motors of each rotary airlock unloading valve.

[0080] The control system 500 has the following built-in control logic: (1) Pressure control of upper chamber 200: The control system 500 reads the feedback signal of the pressure sensor 270 in real time, compares it with the preset pressure value (101-104 kPa), and outputs the adjustment signal to the regulating valve 263 through the PID algorithm to adjust the exhaust opening so that the pressure inside the chamber is maintained within the set range; when the pressure exceeds 110 kPa, the mechanical safety pressure relief valve 280 automatically opens to relieve pressure, and the control system 500 issues an audible and visual alarm at the same time.

[0081] (2) Intermittent spray control of cryogenic spray mechanism 220: The control system 500 calculates the required spray cycle based on the conveying speed of the first conveying mechanism 210 (obtained through encoder feedback), outputs a pulse signal to the pulse control valve 226 to control the on / off of compressed air and realize intermittent spray; at the same time, based on the feedback signal of the temperature sensor, it outputs an analog signal to the flow regulating valve 222 to regulate the liquid nitrogen flow rate and keep the temperature of the atomized gas flow at -100℃±10℃.

[0082] (3) Vacuum control of the middle chamber 300: The control system 500 reads the feedback signal of the resistance gauge during the vacuuming stage and controls the operation of the vacuum pump; when the pressure drops below 10Pa, it switches to read the feedback signal of the ionization gauge and controls the pumping speed of the vacuum pump or the opening of the gas supply valve through the PID algorithm to maintain the vacuum at 25Pa±5Pa; when the pressure switch is triggered, the control system 500 immediately cuts off the power supply of the heating mechanism 320 to prevent overheating.

[0083] (4) Temperature control of the middle chamber 300: The control system 500 reads the feedback signal of the Pt100 thermal resistor and compares it with the preset heating curve (e.g., 5℃ for 1.5 h, then 0.8℃ / min to 18℃). The system outputs the adjustment signal to the solid-state relay of the infrared heating tube array 321 through the PID algorithm to adjust the heating power. At the same time, the system reads the feedback signals of the three K-type thermocouples and monitors the surface temperature of the food in real time. If the temperature deviates from the preset value by more than ±2℃, the heating rate is automatically adjusted.

[0084] (5) Cold trap temperature control: The control system 500 reads the feedback signal of the T-type thermocouple. When the cold trap inlet temperature is higher than -40℃, it outputs a signal to start the refrigeration unit of the cold trap; when the temperature is lower than -45℃, it outputs a signal to stop the refrigeration unit, so that the cold trap temperature is maintained in the range of -45℃ to -40℃.

[0085] (6) Lower cabin 400 pulse jet control: The control system 500 outputs a pulse signal to the pulse control valve 423 to generate a pulse airflow with a frequency of 2 Hz and a single jet duration of 0.2 s; at the same time, it coordinates with the drive motor of the third transmission mechanism 410 for control: when the third transmission mechanism 410 is in a stopped state, it outputs a jet signal; when the third transmission mechanism 410 is running, it stops outputting the jet signal.

[0086] (7) Coordinated control of each conveying mechanism and rotary airlock unloading valve: The control system 500 outputs frequency signals to the frequency converters of the first conveying mechanism 210, the second conveying mechanism 310 and the third conveying mechanism 410 according to the preset process parameters to control the conveying speed; at the same time, it outputs frequency signals to the motors of the rotary airlock unloading valves in the four tanks of feeding tank 230, first transfer tank 250, second transfer tank 340 and unloading tank 430 to control the rotation speed of the rotary airlock unloading valves, so that the material processing speed of each tank is dynamically matched to achieve continuous production.

[0087] (8) Fault diagnosis and safety protection: The control system 500 monitors the signal status of each sensor in real time. When it detects abnormal sensor signal, excessive pressure, excessive temperature or motor overload, it automatically executes the shutdown procedure, cuts off the power supply of the relevant actuators, and issues an audible and visual alarm. At the same time, it displays the fault code and fault location on its own display screen. Example 2

[0088] This embodiment takes fried chicken nuggets as an example of fried foods. The device described in Embodiment 1 is used to deoil the fried chicken nuggets (initial oil content 27%). (Fried foods, in addition to the fried chicken nuggets of this embodiment, can also be fried potato chips, fried chili peppers, fried fruits, fried vegetables, or fried meat products.) The steps include: S1. Continuous feeding step: The fried food enters the upper chamber 200 through the rotary airlock unloading valve of the feeding trough 230 and falls onto the first conveying mechanism 210.

[0089] S2. Surface microcrystallization step: The food is conveyed on the first conveying mechanism 210 at a speed of 0.5 m / min. The ultra-low temperature spraying mechanism 220 sprays atomized liquid nitrogen gas at -100℃, forming a microcrystalline frozen layer with a thickness of 1.2 mm on the surface of the food, while maintaining the core temperature of the food at -3℃. At the same time, the first exhaust mechanism 260 maintains the pressure inside the upper chamber 200 within the range of 101-104 kPa.

[0090] S3. First airlock conveying step: The food after surface microcrystallization treatment is conveyed to the first transfer tank 250 by the first conveying mechanism 210, and falls onto the second conveying mechanism 310 of the middle chamber 300 through the rotary airlock unloading valve of the first transfer tank 250. The rotary airlock unloading valve of the first transfer tank 250 maintains the vacuum level of the middle chamber 300 during rotation.

[0091] S4. Vacuum sublimation step: The food is conveyed on the second conveying mechanism 310 at a speed of 0.2 m / min, and the vacuum degree of 25 Pa is maintained in the middle chamber 300. The heating mechanism 320 adopts segmented temperature control: first, it is kept at 5℃ for 1.5 hours, and then it is raised to 18℃ at a rate of 0.8℃ / min and kept for 2 hours.

[0092] The microcrystalline layer undergoes the following dynamic changes during vacuum sublimation: Phase 1 (0-40 minutes): The microcrystalline layer remains intact, internal moisture vaporizes, the microcrystalline layer prevents water vapor from escaping, and the internal pressure gradually increases, exerting a "pushing" effect on the grease, causing the grease to accumulate towards the inside of the microcrystalline layer.

[0093] The second stage (40-100 minutes): When the internal pressure exceeds the strength of the microcrystalline layer, water vapor "bursts open" the micropores at the weak points of the microcrystalline layer, forming directional micropores with a diameter of 0.02-0.1 mm. The water vapor escapes at high speed along the micropores, generating a "jet effect" that carries the grease outwards.

[0094] The third stage (100-150 minutes): Ice crystals in the microcrystalline layer begin to sublimate, the microporous network expands, and a large amount of grease migrates to the surface. Under the action of gravity, it drips through the mesh of the second conveying mechanism 310 onto the first oil guide plate 351 of the first oil collection system 350. The grease is collected in the first oil collection tank 352 through the first oil guide plate 351. After the liquid level in the first oil collection tank 352 reaches the set value, it is automatically discharged through the first oil drain valve 354.

[0095] Fourth stage (after 150 minutes): The ice crystals completely sublimate, and the microcrystalline layer transforms into a porous thin-shell structure with a porosity of about 60%, resulting in a crisp texture and oil-resistant properties.

[0096] S5. Second airlock conveying step: The food after vacuum sublimation treatment is conveyed to the second transfer tank 340 by the second conveying mechanism 310, and falls onto the third conveying mechanism 410 of the lower chamber 400 through the rotary airlock unloading valve in the second transfer tank 340. The rotary airlock unloading valve in the second transfer tank 340 maintains the vacuum level of the middle chamber 300 during rotation.

[0097] S6. Airflow Separation Step: The food is conveyed in a stepping manner on the third conveyor mechanism 410 (advancing 50 mm every 2 seconds, pausing for 1 second). During the pause, the pulsed airflow jet device 420 sprays pulsed airflow (frequency 2Hz, single duration 0.2s, pressure 0.25MPa) onto the food surface, blowing off the free grease that has migrated to the surface. The blown-off grease falls through the mesh of the third conveyor mechanism 410 onto the second oil guide plate 451, and is collected in the second oil collection tank 452. After the liquid level in the second oil collection tank 452 reaches the set value, it is automatically discharged through the second oil drain valve 454. The lower chamber 400 is maintained at a normal pressure through the second exhaust mechanism 440. After the pulsed airflow is injected, excess gas is automatically discharged through the one-way exhaust valve 442.

[0098] S7. Continuous discharge step: The deoiled food is conveyed to the discharge tank 430 by the third conveyor mechanism 410 and discharged through the rotary airlock discharge valve of the discharge tank 430.

[0099] Processing results: final oil content 4.9%, oil removal rate 81.9%, vacuum fluctuation in the middle chamber ±3 Pa, 8.5 kg of grease recovered by the first oil collection system, and 10.7 kg of grease recovered by the second oil collection system (processing time 8 hours, processing capacity 450 kg). Verification Experiment 1:

[0100] This verification experiment used the same method as in Example 2 to process fried lotus root slices (initial oil content 22%), testing the oil removal effect under different combinations of microcrystalline layer thickness and heating rate. The microcrystalline layer thickness was controlled by adjusting the spraying time and liquid nitrogen flow rate of the ultra-low temperature spray mechanism 220, and the heating rate was achieved by adjusting the temperature rise curve of the heating mechanism 320 through the control system 500. The experimental results are shown in Table 1.

[0101] Table 1. Experiment on the synergistic optimization of microcrystalline layer thickness and heating rate

[0102] As shown in Table 1, the optimal oil removal effect is achieved when the microcrystalline layer thickness is 1.0 mm to 1.5 mm and the heating rate is 0.5℃ / min to 1.0℃ / min, with a preferred microcrystalline layer thickness of 1.2 mm and a heating rate of 0.8℃ / min. When the microcrystalline layer is too thin (0.5 mm), micropores form prematurely and unevenly, leading to localized leakage of oil before it has fully migrated; when the microcrystalline layer is too thick (2.0 mm), the internal pressure is insufficient to break through the microcrystalline layer, causing oil to remain inside the food, resulting in poor oil removal performance. Verification Experiment 2:

[0103] This verification experiment used the same method as in Example 2 to process fried chicken nuggets, testing the pressure stability and liquid nitrogen consumption under different spraying modes. The experimental results are shown in Table 2.

[0104] Table 2. Effects of different injection modes on upper chamber pressure

[0105] As shown in Table 2, after adopting intermittent injection + pressure feedback control, the pressure in the upper chamber 200 stabilized within the range of 101-104 kPa, with fluctuations of only ±1.5 kPa. Liquid nitrogen consumption was reduced by 28.9% compared to continuous injection, and the uniformity of the microcrystalline layer was excellent. This proves the effectiveness of the coordinated control between the first exhaust mechanism 260 and the control system 500. Verification Experiment 3:

[0106] This verification experiment used the same method as in Example 2 to process five different types of fried foods to verify the adaptability of the device of the present invention. The test results are shown in Table 3.

[0107] Table 3. Oil removal effect of different food types

[0108] As shown in Table 3, the device of the present invention has good adaptability to fried foods of different types and oil contents, with an oil removal rate of more than 80%. The two oil collection systems can effectively recover the oil removed at different stages, with a total oil recovery rate of more than 85% and excellent sensory quality.

[0109] Other aspects of this invention that are not detailed herein are all conventional techniques known to those skilled in the art.

[0110] It should be noted that the terms “comprising,” “including,” or any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0111] The scope of protection of this invention is not limited to the technical solutions disclosed in the specific embodiments. Any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of this invention shall fall within the scope of protection of this invention.

Claims

1. A device for removing oil from fried foods, comprising a frame (100) and a control system (500), characterized in that: Three compartments are installed inside the frame (100), which are, from top to bottom, the upper compartment (200), the middle compartment (300) and the lower compartment (400); a conveying mechanism is installed in each of the three compartments; The upper chamber (200) is provided with a cryogenic spray mechanism (220) above the conveying mechanism, a feeding trough (230) is provided at the top of the upper chamber (200) above the feeding end of the inner conveying mechanism, and a first transfer trough (250) is provided at the bottom of the upper chamber (200) below the unloading end of the inner conveying mechanism. A heating mechanism (320) is provided above the conveying mechanism of the middle chamber (300), and a vacuum system (330) is connected to the middle chamber (300); the lower end of the first transfer trough (250) penetrates the middle chamber (300) and extends to the upper part of the feed end of the conveying mechanism inside the middle chamber (300); a second transfer trough (340) is provided at the bottom of the middle chamber (300) below the discharge end of the conveying mechanism inside the middle chamber (300). A pulsed air jet device (420) is provided above the conveying mechanism of the lower chamber (400); the lower end of the second transfer trough (340) extends through the lower chamber (400) and extends above the feed end of the conveying mechanism of the lower chamber (400); a discharge trough (430) is provided at the bottom of the lower chamber (400) below the discharge end of the conveying mechanism of the lower chamber (400). Rotary airlock discharge valves are installed in the feed trough (230), the first transfer trough (250), the second transfer trough (340), and the discharge trough (430); The control system (500) is electrically connected to each conveying mechanism, the cryogenic spraying mechanism (220), the heating mechanism (320), the pulsed airflow jetting device (420), the vacuum system (330), and each rotary lock unloading valve.

2. The oil removal device for fried foods according to claim 1, characterized in that: The upper compartment (200) is also provided with a first exhaust mechanism (260), which includes an exhaust port (261), an exhaust pipe (262) and a regulating valve (263). The upper compartment (200) is provided with a pressure sensor (270). The control system (500) adjusts the opening of the regulating valve (263) according to the feedback of the pressure sensor (270) to maintain the pressure inside the compartment in the range of 101 kPa to 104 kPa.

3. The oil removal device for fried foods according to claim 1, characterized in that: The bottom of the middle compartment (300) is also provided with a first oil collection system (350), and the lower compartment (400) is also provided with a second oil collection system (450).

4. The oil removal device for fried foods according to claim 1, characterized in that: Side baffles are installed on both sides of the conveyor mechanism inside each compartment, and the side baffles fit snugly against the inner wall of the compartment they are in.

5. The oil removal device for fried foods according to claim 1, characterized in that: The cryogenic spray mechanism (220) includes a liquid nitrogen storage tank, a compressed air pipeline (223), a gas-liquid mixing chamber (225), a nozzle array (221), a flow regulating valve (222), and a pulse control valve (226). The liquid nitrogen storage tank is located outside the frame (100) and is connected to the gas-liquid mixing chamber (225) via a liquid nitrogen delivery pipeline (224). The compressed air pipeline (223) is connected to the gas-liquid mixing chamber (225). The gas-liquid mixing chamber (225) is suspended at the top of the upper chamber (200) and is located directly above the conveying mechanism inside the upper chamber (200). The nozzle array (221) is installed below the gas-liquid mixing chamber (225) at a 15° angle to the vertical direction. The cryogenic spray mechanism (220) adopts an intermittent spraying method, and the spraying cycle is linked to the conveying speed of the conveying mechanism inside the upper chamber (200).

6. The oil removal device for fried foods according to claim 1, characterized in that: The vacuum system (330) includes a suction pipe (331), a vacuum pump and a cold trap. The middle chamber (300) is equipped with a resistance gauge and an ionization gauge. The resistance gauge is used for pressure monitoring during the vacuuming stage, and the ionization gauge is used for precise pressure control during the sublimation stage.

7. The oil removal device for fried foods according to claim 1, characterized in that: The pulsed airflow injection device (420) includes an air source (422), a second pulse control valve (423), a distribution pipe (424), and a second nozzle array (421). The air source (422) is a nitrogen storage tank, which is located outside the lower compartment (400). The distribution pipe (424) is installed on the top of the inner side of the lower compartment (400). The second pulse control valve (423) is installed outside the lower compartment (400), with its inlet end connected to the air source (422) and its outlet end connected to the distribution pipe (424) through a through-chamber connector. The second nozzle array (421) is installed on the distribution pipe (424) through a ball joint and is located directly above the third conveying mechanism (410), forming a 45° angle with the vertical direction. Its injection direction is opposite to the conveying direction of the conveying mechanism inside the lower compartment (400).

8. The oil removal device for fried foods according to claim 1, characterized in that: The rotary airlock unloading valve includes a valve body (241), a rotary impeller (242), and a motor. The rotary impeller (242) adopts a wide blade structure, and the blade surface is provided with an arc-shaped groove (2421). The gap between the rotary impeller (242) and the valve body (241) is 2 mm to 5 mm. The inner wall of the valve body (241) is provided with an elastic sealing strip.

9. The oil removal device for fried foods according to claim 1, characterized in that: The lower compartment (400) is also provided with a second exhaust mechanism (440), which includes an exhaust pipe (441) installed on the lower compartment (400) and connected to the interior of the lower compartment (400) and a one-way exhaust valve (442) installed on the exhaust pipe (441). The opening pressure of the one-way exhaust valve (442) is 101.3 kPa to 105 kPa.

10. A method for removing oil from fried food using the apparatus described in any one of claims 1 to 9, characterized in that, Includes the following steps: The fried food enters the upper compartment (200) through the feeding trough (230) and falls onto the conveying mechanism inside the upper compartment (200); During the process of food being transported on the conveying mechanism inside the upper compartment (200), the ultra-low temperature spraying mechanism (220) sprays ultra-low temperature cooling medium onto the food surface, causing a microcrystalline frozen layer to form on the food surface; After surface microcrystallization treatment, the food falls through the first transfer tank (250) onto the conveying mechanism inside the middle compartment (300); During the process of food being transported on the conveying mechanism inside the middle chamber (300), the middle chamber (300) is kept in a vacuum state, while the heating mechanism (320) heats the food, causing the moisture inside the food to sublimate and escape, and driving the internal oil to migrate to the surface. After vacuum sublimation, the food falls through the second transfer tank (340) onto the conveying mechanism inside the lower chamber (400); During the process of food being transported on the conveyor mechanism inside the lower compartment (400), the pulsed air jet device (420) sprays pulsed air jets onto the surface of the food to blow off the free oil that has migrated to the surface; After the oil removal process, the food is conveyed to the unloading trough (430) by the conveying mechanism in the lower compartment (400) and discharged out of the device through the unloading trough (430).

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