Dynamic-static switchable closed cycle drying system and method

Abstract

The invention belongs to the technical field of marine biological resource processing equipment, and particularly relates to a dynamic-static switchable closed cycle drying system and method. The system comprises a control system, a circulating ventilation pipeline, a nitrogen supply mechanism, a drying tower, a drying main machine, a conveying mechanism, a raw material container, a grading screening mechanism, a heat energy recycling mechanism, an electric heating box and a static drying mechanism. The method comprises a static drying mode and a dynamic drying mode. According to the system, the oxygen content in the system can be accurately controlled, the heat energy utilization rate is increased, the krill drying quality is guaranteed, and classified screening of krill drying products is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of marine biological resource processing equipment, and particularly relates to a dynamic-static switchable closed-loop circulation drying system and method. Background Art

[0002] As an important biological resource in the Antarctic Sea area, Antarctic krill is rich in high-quality protein, unsaturated fatty acids and various bioactive substances (such as astaxanthin, etc.), and is a high-value raw material in the fields of food, health products and feed. However, the on-board processing of Antarctic krill faces severe challenges: firstly, the water content in krill is as high as 70%-80%, and traditional drying processes are prone to cause oxidation and deterioration of nutrients; secondly, the on-board processing space is limited, and it is necessary to achieve efficient and continuous drying operations under limited energy and site conditions; thirdly, the processing of krill needs to simultaneously handle intermediate products in different forms (such as shrimp powder and whole shrimp dried shrimp), and a single drying equipment mode is difficult to take into account their different requirements.

[0003] Currently, on-board drying technologies mainly adopt hot air drying or vacuum disk drying. Although hot air drying has high efficiency, the open system design is prone to introduce oxygen, resulting in oxidation and rancidity of unsaturated fatty acids, and shrimp powder is easily scattered at high wind speeds, causing material loss and dust pollution. Although vacuum disk drying has low energy consumption, it has a long cycle, the material is repeatedly dried and hygroscopic, and the quality of shrimp powder drops significantly. In addition, existing closed-loop circulation drying systems mostly focus on a single drying mode. For example, dynamic air drying is suitable for powdery materials, but it cannot meet the low-speed dehydration requirements of whole dried shrimp. Although a static drying oven can avoid material scattering, it lacks an efficient heat energy distribution mechanism, resulting in redundant energy consumption. More critically, existing systems rely on manual intervention when switching between dynamic and static modes, with low switching efficiency and lagging parameter adjustment, and it is difficult to adapt to the real-time changing processing requirements in the on-board environment.

[0004] In view of the above problems, the prior art has the following key unsolved defects: 1. Oxygen sensitivity is incompatible with closed-loop circulation: The airtightness of traditional closed-loop systems is insufficient, and the control accuracy of oxygen concentration is low (usually >5%), making it impossible to effectively inhibit the lipid oxidation of krill, resulting in a decline in product quality; 2. Poor adaptability to drying multi-morphology materials: Although the high wind speed and high temperature (>200°C) of the dynamic drying unit are suitable for rapid dehydration of shrimp powder, they will damage the tissue structure of dried shrimp, while the low-speed drying mode of the static unit cannot meet the high-efficiency evaporation requirements of shrimp powder; 3. Energy waste and space contradiction: The shipboard environment requires the system to be compact and low-energy-consuming, but the existing dynamic-static split design occupies a large space, and the thermal energy cannot be reused across units. The direct discharge of drying waste gas results in an energy utilization rate of less than 40%; 4. Lack of intelligent control: The switching between dynamic and static modes relies on empirical operation, lacking a coordinated control strategy based on material moisture content, temperature, and oxygen concentration. The switching response time is long, resulting in large fluctuations in drying efficiency; 5. The existing devices cannot operate dynamic and static drying simultaneously and cannot achieve the classification and screening of shrimp pellet raw materials. Summary of the Invention

[0005] The present invention discloses a dynamic-static switchable closed-loop circulation drying system and method, aiming to achieve efficient, low-energy-consuming, and nutrition-preserving drying of Antarctic krill powder and whole shrimp dried shrimp, so as to solve the problems described in parts 1-5 of the background technology.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] A dynamic-static switchable closed-loop circulation drying system, comprising: a control system, a circulating ventilation pipeline, and a nitrogen supply mechanism. A drying tower and a drying main machine are connected in series on the circulating ventilation pipeline. The drying main machine is connected to a raw material container through a conveying mechanism and is used to dry the raw materials entering the drying main machine dynamically. The drying tower is provided with a classification and screening mechanism. An air outlet one of the drying tower is connected to a heat recovery mechanism through a pipeline one. The heat recovery mechanism is connected to an electric heating box. The electric heating box is connected to the nitrogen supply mechanism. The gas output end of the electric heating box is connected to the drying main machine through the circulating ventilation pipeline. The drying main machine is connected to the lower end of the drying tower. A branch pipeline is connected in parallel on the circulating ventilation pipeline. A static drying mechanism is provided on the branch pipeline. The control system is configured to control the operation of the dynamic drying mode, the static drying mode, and the switching between the dynamic and static drying modes.

[0008] Preferably, the drying main machine includes a main machine housing. A driving shaft is arranged axially in the main machine housing. A plurality of stirring blades are evenly distributed on the driving shaft. One end of the driving shaft and located outside the main machine housing is connected to a first driving motor. Driven by the first driving motor, the raw materials entering the main machine housing are dried during the stirring and turning process.

[0009] Preferably, a first feed inlet is provided at the top of the main machine housing. The conveying mechanism is a screw conveyor passing through the raw material container. The feed end of the screw conveyor is located at the bottom inside the raw material container, and the discharge end is opposite to the first feed inlet. The screw conveyor is driven by a second driving motor. A feed hopper is provided at the top of the raw material container.

[0010] Preferably, one end of the circulating ventilation pipeline is connected to the side wall of the main machine housing near the first feed inlet. A first ventilation opening is provided at the top of the outer wall of the main machine housing away from the first feed inlet. The first ventilation opening is hermetically connected to the bottom end of the drying tower. A sealing cover is provided at the top end of the drying tower. The classification and screening mechanism includes a bag filter and a rotating shaft vertically penetrating the sealing cover and rotatably connected to the sealing cover. A plurality of cutting knives are evenly distributed on the outer wall of the rotating shaft. The top end of the rotating shaft is connected to a third driving motor. A sealing fan for adjusting the air pressure inside the drying tower is connected to the lower part of the outer wall of the drying tower. The sealing fan is connected to the drying tower through a first air outlet pipe and connected to the circulating ventilation pipeline through a first air inlet pipe. A first air pressure sensor is provided on the inner wall of the drying tower near the cutting knives. A second ventilation opening is provided on the outer wall of the drying tower above the cutting knives. The second ventilation opening is connected to the bottom of the side wall of the bag filter through a first connecting pipe. An air reverse blower is further provided on one side of the bag filter.

[0011] Preferably, an induced draft fan is provided on the side of the air reverse blower away from the bag filter. The first air inlet end of the induced draft fan is connected to the second air outlet of the top of the side wall of the bag filter through a second connecting pipe. The first air outlet end of the induced draft fan is connected to the heat energy recovery mechanism through a first pipeline. The second air outlet end of the air reverse blower is connected to the bag filter through a third connecting pipe, and the second air inlet end is connected to the first pipeline through a fourth connecting pipe.

[0012] Preferably, the heat energy recovery mechanism includes a condensing unit and a heat exchanger. The first pipeline is communicated with the inner cavity of the condensing unit. One end of the condensing unit away from the first pipeline is connected to one end of the heat exchanger. The cold water pipeline of the condensing unit is connected in series with the heat exchange pipe of the heat exchanger. One end of the heat exchanger is connected to one end of the electric heating box, and the other end of the electric heating box is connected to the other end of the circulating ventilation pipeline.

[0013] Preferably, the nitrogen supply mechanism is connected to the electric heating box through a second pipeline. Oxygen concentration sensors are respectively arranged in the drying main machine, the drying tower, and the static drying box. The water inlet and outlet of the condensing unit are respectively connected to the water outlet end and the water inlet end of the water chiller through a third pipeline and a fourth pipeline.

[0014] Preferably, the static drying mechanism includes a static drying box which is provided with a sealing door. Inside the static drying box, there are several trays for carrying whole raw shrimps. An exhaust pipe 1 is provided on the side wall of the static drying box. The branch pipe includes branch pipe A and branch pipe B. One end of branch pipe A is connected to connecting pipe 1, and the other end is connected to the air outlet end 3 of the static drying box. One end of branch pipe B is connected to the air inlet end 3 of the static drying box, and the other end is connected to the circulating ventilation pipeline through a first three-way joint. The end of exhaust pipe 1 is provided with a second three-way joint. One free end of the second three-way joint is communicated with the outside air through a ventilation pipe 1, and the other free end is connected to branch pipe A through a ventilation pipe 2. The ventilation pipe 1 and the ventilation pipe 2 are respectively provided with a first electromagnetic flow regulating valve and a second electromagnetic flow regulating valve. The circulating ventilation pipeline is provided with an exhaust pipe 2. The opening end of branch pipe A facing connecting pipe 1 is provided with a filter screen for filtering shrimp powder. The branch pipe A, branch pipe B, circulating ventilation pipeline, exhaust pipe 2, and connecting pipe 1 are respectively provided with a third electromagnetic flow regulating valve, a fourth electromagnetic flow regulating valve, a fifth electromagnetic flow regulating valve, a sixth electromagnetic flow regulating valve, and a seventh electromagnetic flow regulating valve. The fifth electromagnetic flow regulating valve is arranged on the side of the first three-way joint facing the drying tower, and the seventh electromagnetic flow regulating valve is located above branch pipe A. Temperature and humidity sensors are respectively arranged on the inner wall of the drying main body, the inner wall of the drying tower, the inner cavity of the condensing unit, and the inner wall of the static drying box. A second air pressure sensor is arranged inside the static drying box. The control system is a PLC controller.

[0015] A working method of a dynamic-static switchable closed-loop circulation drying system includes: a dynamic drying mode and a static drying mode. In all drying modes, first, the nitrogen supply mechanism is opened, and the control system makes the heated nitrogen enter the drying system through the induced draft fan. Then, the exhaust valve 1 and the exhaust valve 2 are opened to reduce the oxygen in the drying system to the set standard, and then the exhaust valve 2 and the nitrogen supply mechanism are closed.

[0016] The specific dynamic drying mode is as follows: The third electromagnetic flow regulating valve and the fourth electromagnetic flow regulating valve are closed, so that the heated nitrogen circulates in the closed-loop pipeline formed by the circulating ventilation pipeline, the drying main body, the drying tower, connecting pipe 1, the bag filter, connecting pipe 2, the induced draft fan, pipeline 1, the condensing unit, the heat exchanger, and the electric heating box to dry the shrimp pellet raw materials in the drying main body. The moisture in the hot nitrogen is discharged through the condensing unit, and the dried shrimp pellet raw materials are discharged through the discharge port of the drying main body.

[0017] The specific static drying mode is as follows: The whole shrimp raw materials are pre-placed on the trays of the static drying oven. The third electromagnetic flow regulating valve and the fourth electromagnetic flow regulating valve are opened, and the fifth electromagnetic flow regulating valve and the seventh electromagnetic flow regulating valve are closed, so that the hot nitrogen gas circulates among the branch pipeline A, the lower part of the connecting pipe 1, the bag filter, the connecting pipe 2, the induced draft fan, the pipeline 1, the condensing unit, the heat exchanger, the electric heating box, the circulating ventilation pipeline on the side far from the drying tower of the first three-way joint, the first three-way joint, the branch pipeline B, and the static drying oven, realizing the drying of the whole shrimp raw materials.

[0018] Preferably, it also includes a grading and screening method, specifically: In the dynamic drying mode or the combined dynamic and static drying mode, the sealing fan is turned on, and the control system controls the power of the sealing fan based on the signal of the first air pressure sensor. Some small-particle raw materials in the shrimp pellet raw materials are driven by the nitrogen gas flow to the cutter position and are chopped into smaller particles. Under the set air pressure data environment, the shrimp powder particles that meet the air pressure dynamic characteristics enter the bag filter through the connecting pipe 1 for recovery, and the remaining shrimp pellet particles are recovered by the drying main machine; by changing the power of the sealing fan, the grading of shrimp pellet particles with different particle sizes is realized.

[0019] The beneficial effects of the dynamic-static switchable closed-loop circulation drying system and method of the present invention are as follows:

[0020] 1. Realize the effective compatibility of oxygen sensitivity and closed-loop circulation: The traditional closed-loop system has insufficient airtightness and low precision in controlling the oxygen concentration (usually >5%), and cannot effectively inhibit the lipid oxidation of krill, resulting in a decline in product quality; the closed-loop circulation drying system of the present invention can accurately control the oxygen concentration to <2.0%, effectively avoiding the lipid oxidation of krill and ensuring product quality.

[0021] 2. Improve the adaptability of drying multi-form materials: The present invention can perform static drying on the whole shrimp raw materials, dynamic drying on the shrimp pellet raw materials, and drying grading and recovery on the shrimp powder raw materials.

[0022] 3. Effectively improve the thermal energy utilization rate and save occupied space.

[0023] 4. Realize the automatic switching between the dynamic and static drying modes through the control system, and can also realize the simultaneous drying of dynamic and static states.

[0024] 5. Realize the grading and screening of the dried products of shrimp pellet raw materials within different particle size ranges by regulating the air pressure in the drying tower. Description of the Drawings

[0025] Figure 1 It is a top view layout diagram of a dynamic-static switchable closed-loop circulation drying system of the present invention;

[0026] Figure 2Front view structure diagram of a dynamic-static switchable closed-loop circulation drying system of the present invention;

[0027] Figure 3 Partial structure diagram (omitting the rotating shaft and the third driving motor) at position A of a dynamic-static switchable closed-loop circulation drying system of the present invention.

[0028] Figure 4 Structure schematic diagram of Embodiment 8 of the present invention.

[0029] Markings in the figure: 1, raw material container; 2, screw conveyor; 3, drying main machine; 31, main machine housing; 32, stirring blade; 4, drying tower; 41, cutter; 42, rotating shaft; 43, third driving motor; 5, connecting pipe; 6, circulating ventilation pipeline; 7, sealing fan; 71, first air outlet pipe; 72, first air inlet pipe; 8, bag filter; 9, reverse blower; 91, fourth connecting pipe; 92, third connecting pipe; 10, induced draft fan; 11, condensing unit; 12, heat exchanger; 13, static drying oven; 14, electric heating box; 15, water chiller; 16, first connecting pipe; 17, branch pipeline A; 18, first three-way joint; 19, branch pipeline B; 20, connecting pipeline B; 21, connecting pipeline A; 22, drainage fan; 101, second connecting pipe; 102, pipeline 1. Detailed implementation manners

[0030] The following description is only for the preferred embodiments of the present invention and is not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0031] The following embodiments can be understood as separately expressing a part of the local structure or method of the present invention, or can also be understood as the embodiments combined with each other to explain the connotation of the structure or method of a larger scope of the present invention.

[0032] Embodiment 1

[0033] A dynamic-static switchable closed-loop circulation drying system, as Figures 1-3As shown in the figure, it includes: a control system (not shown in the figure), a circulating ventilation pipeline 6, and a nitrogen supply mechanism (not shown in the figure). A drying tower 4 and a drying main machine 3 are connected in series on the circulating ventilation pipeline 6. The drying main machine 3 is connected to the raw material container 1 through a conveying mechanism and is used to dry the raw materials entering the drying main machine 3 dynamically. The drying tower 4 is provided with a grading and screening mechanism. An air outlet one of the drying tower is connected to a heat energy recovery mechanism through a pipeline 102. The heat energy recovery mechanism is connected to an electric heating box 14. The electric heating box 14 is connected to the nitrogen supply mechanism. A gas output end of the electric heating box 14 is connected to the drying main machine 3 through the circulating ventilation pipeline. The drying main machine 3 is connected to the lower end of the drying tower 4. A branch pipeline is connected in parallel on the circulating ventilation pipeline 6. A static drying mechanism is provided on the branch pipeline. The control system is configured to control the operation of the dynamic drying mode, the static drying mode, and the switching between the dynamic and static drying modes.

[0034] In this embodiment, the nitrogen supply mechanism is used to fill nitrogen into the system so that the oxygen content in the system reaches below the set standard value, effectively inhibiting the lipid oxidation of krill. Among them, the static drying mechanism is used to dry the whole shrimp raw materials, and the drying main machine can dynamically stir and dry the shrimp pellet raw materials. The shrimp powder in the shrimp pellet raw materials and the shrimp powder obtained by crushing in the drying tower are screened by the grading and screening mechanism. The grading and screening mechanism controls the air pressure in the drying tower to achieve the screening of shrimp powder within a certain particle size range under specific air pressure conditions, thereby realizing the grading of the dried products.

[0035] Embodiment 2

[0036] As Figures 1-3 shown, the drying main machine 3 includes a main machine housing 31. A driving shaft is arranged axially in the main machine housing 31. A plurality of stirring blades 32 are evenly distributed on the driving shaft. One end of the driving shaft and located outside the main machine housing 31 is connected to a first driving motor (not marked in the figure). Driven by the first driving motor, the raw materials entering the main machine housing 31 are dried during the stirring and turning process (a discharge port is provided on the bottom end of the main machine housing close to the drying tower side. An electric door is provided at the discharge port. The stirring blades are arranged in a spiral pattern and push the shrimp pellet raw materials towards the discharge port side while stirring. When the detected humidity data reaches the set value, the electric door can be opened for discharging).

[0037] As Figures 1-3 shown, a feed inlet one is provided at the top of the main machine housing 31. The conveying mechanism is a screw conveyor 2 passing through the raw material container 1. The feed end of the screw conveyor 2 is located at the bottom inside the raw material container 1, and the discharge end is opposite to the feed inlet one. The screw conveyor 2 is driven by a second driving motor (not marked in the figure). A feed hopper is provided at the top of the raw material container 1.

[0038] Example 3

[0039] As Figures 1-3 shown, one end of the circulating ventilation pipeline 6 is connected to the side wall of the main machine housing 31 near the feeding port. At the top of the outer wall of the main machine housing 31 on the side far from the feeding port, there is a first ventilation port (not marked in the figure). The first ventilation port is hermetically connected to the bottom end of the drying tower 4. The top end of the drying tower 4 is provided with a sealing cover. The grading and screening mechanism includes a bag filter 8 and a rotating shaft 42 that vertically penetrates the sealing cover and is rotatably connected to the sealing cover. A plurality of cutting knives 41 are evenly distributed on the outer wall of the rotating shaft 42. The top end of the rotating shaft 42 is connected to a third driving motor 43. The lower part of the outer wall of the drying tower 4 is connected with a sealing fan 7 for adjusting the air pressure in the drying tower. The sealing fan 7 is connected to the drying tower 4 through an air outlet pipe 71 and is connected to the circulating ventilation pipeline 6 through an air inlet pipe 72. At a position on the inner wall of the drying tower 4 close to the cutting knife 41, there is a first air pressure sensor (not drawn in the figure). Above the cutting knife 41, there is a second ventilation port on the outer wall of the drying tower 4. The second ventilation port is connected to the bottom side wall of the bag filter 8 through a connecting pipe 16. On one side of the bag filter 8, there is also a reverse blower 9.

[0040] As Figure 1 、 2 shown, on the side of the reverse blower 9 far from the bag filter 8, there is an induced draft fan 10. The air inlet end one of the induced draft fan 10 is connected to the air outlet two at the top of the side wall of the bag filter 8 through a connecting pipe 101. The air outlet end one of the induced draft fan is connected to the heat energy recovery mechanism through a pipeline 102. The air outlet end two of the reverse blower 9 is connected to the bag filter 8 through a connecting pipe 92, and the air inlet end two is connected to the pipeline 102 through a connecting pipe 91.

[0041] In this embodiment, the reverse blower is used to blow the bag filter in reverse to prevent blockage, and at the same time, it promotes the shrimp powder to fall to the bottom of the bag filter and is discharged after accumulating to a certain extent. The induced draft fan is used to provide the air flow circulation power for the whole system. The sealing fan is used to regulate the air pressure in the drying tower to achieve grading and screening. During the grading and screening process, the small particle shrimp powder in the drying tower is in a boiling state. Affected by the set air pressure, part of the shrimp powder particles enter the bag filter, and the other part of the small particle raw materials fall back to the drying main machine due to their own gravity. Among them, the cutting knife plays a role in cutting the boiling shrimp powder particles and cutting them into shrimp powder that can enter the bag filter due to the action of air pressure (to improve the grading and screening effect, an axial screw fan can also be set in the drying tower. Using centrifugal force, the large particle raw materials settle on the periphery, and the shrimp powder that meets the air pressure is discharged upward, that is, the principle of a screw classifier). The raw materials in the drying tower and the drying main machine are quickly dried by the heated nitrogen.

[0042] Example 4

[0043] As Figure 1 、 2 shown, the heat energy recovery mechanism includes a condensing unit 11 and a heat exchanger 12. The first pipeline 102 communicates with the inner cavity of the condensing unit 11. One end of the condensing unit 11 away from the first pipeline 102 is connected to one end of the heat exchanger 12. The cold water pipeline of the condensing unit 11 is connected in series with the heat exchange pipes of the heat exchanger 12. One end of the heat exchanger 12 is connected to one end of the electric heating box 14, and the other end of the electric heating box 14 is connected to the other end of the circulating ventilation pipeline 6.

[0044] In this embodiment, the nitrogen gas that absorbs moisture passes through the bag filter and enters the condensing unit 11 through the induced draft fan. The moisture in the nitrogen gas is discharged under the condensing action and then enters the heat exchanger. The cold water pipeline of the condensing unit heats up after absorbing the heat of the nitrogen gas. At the same time, the nitrogen gas flowing through the condensing unit cools down. The high-temperature water enters the heat exchange pipes of the heat exchanger and exchanges heat with the flowing nitrogen gas again, causing the temperature of the nitrogen gas to rise again, thereby effectively improving the utilization rate of heat energy. The heat exchanger of the present invention preferably uses a finned heat exchanger. The nitrogen gas after passing through the heat exchanger re-enters the electric heating box for further heating.

[0045] Example 5

[0046] As Figure 1 、 2 shown, the nitrogen gas supply mechanism is connected to the electric heating box 14 through the second pipeline. The water inlet and outlet of the condensing unit 11 are respectively connected to the water outlet end and water inlet end of the water chiller 15 through the third pipeline and the fourth pipeline.

[0047] In this embodiment, the nitrogen gas supply mechanism selects a nitrogen generation device, wherein the nitrogen generation purity ≥ 99.9%, and the nitrogen generation capacity ≥ 5 Nm3 / h; in order to effectively monitor the oxygen concentration in the system, oxygen concentration sensors are respectively arranged in the drying host, drying tower, and static drying box to real-time feedback the oxygen concentration in the system and control the oxygen concentration < 2.0%; in order to achieve the above effect, the control system realizes the precise control of the oxygen concentration by controlling the on-off of the exhaust pipe and the input amount of nitrogen gas based on the monitored data of the oxygen concentration.

[0048] Example 6

[0049] As Figure 1 、 2As shown in the figure, the static drying mechanism includes a static drying box 13, which is provided with a sealing door. Inside the static drying box 13, there are several trays for carrying whole raw shrimps (a common device, not shown in the figure. Usually, brackets are set inside the box, and several trays are inserted and connected to the brackets). The side wall of the static drying box 13 is provided with an exhaust pipe 1 (a common device, not shown in the figure, and the purpose is to ensure that the oxygen content in the box meets the standard). The branch pipeline includes branch pipeline A 17 and branch pipeline B 19. One end of the branch pipeline A 17 is connected to the connecting pipe 16, and the other end is connected to the air outlet end 3 of the static drying box. One end of the branch pipeline B 19 is connected to the air inlet end 3 of the static drying box, and the other end is connected to the circulating ventilation pipeline 6 through the first three-way joint 18. The end of the exhaust pipe 1 is provided with a second three-way joint. One free end of the second three-way joint is connected to the outside air through the ventilation pipe 1, and the other free end is connected to the branch pipeline A through the ventilation pipe 2. The ventilation pipe 1 and the ventilation pipe 2 are respectively provided with a first electromagnetic flow regulating valve and a second electromagnetic flow regulating valve; when it is necessary to discharge the air in the static drying box, open the ventilation pipe 1. When the oxygen concentration in the static drying box reaches the set value, close the ventilation pipe 1 and open the ventilation pipe 2;

[0050] As Figure 1 、 2 shown in the figure, the circulating ventilation pipeline 6 is provided with an exhaust pipe 2 (a common device, not shown in the figure) to discharge the air in the system when nitrogen is filled. The opening end of the branch pipeline A 17 facing the connecting pipe 16 is provided with a filter screen for filtering shrimp powder (a common device, not shown in the figure). The branch pipeline A 17, the branch pipeline B 19, the circulating ventilation pipeline 6, the exhaust pipe 2, and the connecting pipe 16 are respectively provided with a third electromagnetic flow regulating valve, a fourth electromagnetic flow regulating valve, a fifth electromagnetic flow regulating valve, a sixth electromagnetic flow regulating valve, and a seventh electromagnetic flow regulating valve. The fifth electromagnetic flow regulating valve is arranged on the side of the first three-way joint 18 facing the drying tower 4 (as Figure 2 shown in the figure), and the seventh electromagnetic flow regulating valve is located above the branch pipeline A 17; Temperature and humidity sensors are respectively arranged on the inner wall of the drying main body 3, the inner wall of the drying tower 4, the inner cavity of the condensing unit 11, and the inner wall of the static drying box 13. A second wind pressure sensor is arranged inside the static drying box 13. The control system is a PLC controller.

[0051] Example 7

[0052] Based on the above embodiments, this embodiment discloses a working method of a dynamic-static switchable closed-loop circulation drying system, as Figures 1-3As shown in the figure, it includes: dynamic drying mode and static drying mode; for all drying modes, the nitrogen supply mechanism is first turned on, and the control system uses the induced draft fan to let heated nitrogen enter the drying system. Then, Exhaust Valve 1 and Exhaust Valve 2 are opened to reduce the oxygen in the drying system to the set standard, and then Exhaust Valve 2 and the nitrogen supply mechanism are closed.

[0053] The specific dynamic drying mode is as follows: Close the third electromagnetic flow regulating valve and the fourth electromagnetic flow regulating valve, so that the heated nitrogen circulates in the closed-loop pipeline formed by the circulating ventilation pipeline, the drying main machine, the drying tower, Connecting Pipe 1, the bag filter, Connecting Pipe 2, the induced draft fan, Pipeline 1, the condensing unit, the heat exchanger, and the electric heating box to dry the shrimp pellet raw materials in the drying main machine. The moisture in the hot nitrogen is discharged through the condensing unit, and the dried shrimp pellet raw materials are discharged through the discharge port of the drying main machine.

[0054] The specific static drying mode is as follows: The whole shrimp raw materials are pre-placed on the trays of the static drying box. Open the third electromagnetic flow regulating valve and the fourth electromagnetic flow regulating valve, close the fifth electromagnetic flow regulating valve and the seventh electromagnetic flow regulating valve, close Ventilation Pipeline 1, and open Ventilation Pipeline 2, so that the hot nitrogen circulates among Branch Pipeline A, the lower part of Connecting Pipe 1, the bag filter, Connecting Pipe 2, the induced draft fan, Pipeline 1, the condensing unit, the heat exchanger, the electric heating box, the circulating ventilation pipeline on the side of the first three-way joint away from the drying tower, the first three-way joint, Branch Pipeline B, and the static drying box to realize the drying of the whole shrimp raw materials.

[0055] Example 8

[0056] Based on the above examples, this example proposes a further improved method, specifically:

[0057] The working method also includes a drying mode in which dynamic and static drying are carried out simultaneously, including: One end of the static drying box is connected to the nitrogen output pipeline of the condensing unit through Connecting Pipe B20, and the other end is connected to Pipeline 102 through Connecting Pipe A21. A drainage fan 22 and an electric valve are provided on Connecting Pipe A21. The flow rate of the nitrogen flowing through the static drying box is regulated by controlling the third electromagnetic flow regulating valve and the fourth electromagnetic flow regulating valve. When the temperature in the static drying box is lower than the set value range, increase the flow rates of the third electromagnetic flow regulating valve and the fourth electromagnetic flow regulating valve to make the temperature in the static drying box reach the set value range. When the temperature in the static drying box is higher than the set value range, reduce or close the third electromagnetic flow regulating valve and the fourth electromagnetic flow regulating valve, and open the electric valve and the drainage fan 22 to input nitrogen that has not been heated by the heat exchanger 14 into the static drying box 13 through Connecting Pipe B20, so that the temperature in the static drying box 13 returns to the set value range. At the same time, the nitrogen output through Connecting Pipe A21 is re-discharged of excess moisture through the condensing unit.

[0058] Example 9

[0059] As Figure 1 , 2 shown, it also includes a grading and screening method, specifically: in the dynamic drying mode or the drying mode with simultaneous dynamic and static operation, the sealing fan is turned on, and the control system controls the power of the sealing fan based on the signal of the first air pressure sensor. Some of the small-particle-size raw materials in the shrimp pellet raw materials are driven by the nitrogen gas flow to the cutter position and chopped into smaller particles. Under the set air pressure data environment, the shrimp powder particles that meet the air pressure dynamic characteristics enter the bag filter through connecting pipe 1 for recovery, and the remaining shrimp pellet particles are recovered by the drying main machine; by changing the power of the sealing fan, the grading of shrimp pellet particles with different particle sizes is realized.

[0060] Example 10

[0061] The drying main machine is an axial flow stirring tank, which includes a cylindrical main machine housing. An actuating shaft (not marked in the figure) is arranged axially in the main machine housing. The two ends of the actuating shaft are respectively rotatably connected to the two ends of the main machine housing. One end of the actuating shaft penetrates the main machine housing and is connected with a first driving motor. The stirring blades include a first stirring blade and a second stirring blade. Multiple groups of first stirring blades and second stirring blades are distributed at intervals on the actuating shaft. Each group of the first stirring blades and the second stirring blades has multiple blade bodies and is evenly distributed about the actuating shaft. The first stirring blade has a certain angle with the plane where the axis and the radial direction of the actuating shaft are located (that is, an axial flow blade is formed around the actuating shaft), and it satisfies that: when the first driving motor rotates forward and backward, the directions of driving the shrimp powder raw materials in the main machine housing to move forward and backward are opposite. The second stirring blade is parallel to the plane where the axis and the radial direction of the stirring shaft at the position where it is located are, that is, the second stirring blade drives the shrimp powder raw materials to move circumferentially around the stirring shaft (that is, during the stirring process, not only can the shrimp powder raw materials be moved around the stirring shaft, but also can move forward or backward, so that the raw materials can be fully contacted with the hot nitrogen gas and quickly dried).

Claims

1. A dynamic-static switchable closed-loop circulation drying system, characterized in that: Including: A control system, a circulating ventilation pipeline, and a nitrogen supply mechanism. A drying tower and a drying main machine are connected in series on the circulating ventilation pipeline. The drying main machine is connected to a raw material container through a conveying mechanism and is used to dry the raw materials entering the drying main machine dynamically. The drying tower is provided with a grading and screening mechanism. An air outlet one of the drying tower is connected to a heat energy recovery mechanism through a pipeline one. The heat energy recovery mechanism is connected to an electric heating box. The electric heating box is connected to the nitrogen supply mechanism. A gas output end of the electric heating box is connected to the drying main machine through the circulating ventilation pipeline. The drying main machine is connected to the lower end of the drying tower. A branch pipeline is connected in parallel on the circulating ventilation pipeline. A static drying mechanism is provided on the branch pipeline. The control system is configured to control the operation of the dynamic drying mode, the static drying mode, and the switching between the dynamic and static drying modes.

2. The dynamic-static switchable closed-loop circulation drying system according to claim 1, characterized in that: The drying main machine includes a main machine housing. A driving shaft is arranged axially in the main machine housing. A number of stirring blades are evenly distributed on the driving shaft. One end of the driving shaft and located outside the main machine housing is connected to a first driving motor. Driven by the first driving motor, the raw materials entering the main machine housing are dried during the stirring and turning process.

3. The dynamic-static switchable closed-loop circulation drying system according to claim 2, characterized in that: A feed inlet one is arranged at the top of the main machine housing. The conveying mechanism is a spiral conveyor penetrating the raw material container. The feed end of the spiral conveyor is located at the bottom inside the raw material container, and the discharge end is opposite to the feed inlet one. The spiral conveyor is driven by a second driving motor. A feed hopper is arranged at the top of the raw material container.

4. A dynamic-static switchable closed-loop circulation drying system according to claim 3, characterized in that: One end of the circulating ventilation pipeline is connected to the side wall of the main machine housing near the feed inlet one. A ventilation opening one is arranged at the top of the outer wall of the main machine housing away from the feed inlet one. The ventilation opening one is hermetically connected to the bottom end of the drying tower. A sealing cover is arranged at the top end of the drying tower. The grading and screening mechanism includes a bag filter and a rotating shaft vertically penetrating the sealing cover and rotatably connected to the sealing cover. A number of cutting knives are evenly distributed on the outer wall of the rotating shaft. The top end of the rotating shaft is connected to a third driving motor. A sealing fan for adjusting the air pressure in the drying tower is connected to the lower part of the outer wall of the drying tower. The sealing fan is connected to the drying tower through an air outlet pipe one and is connected to the circulating ventilation pipeline through an air inlet pipe one. A first air pressure sensor is arranged at a position on the inner wall of the drying tower near the cutting knives. A ventilation opening two is arranged on the outer wall of the drying tower above the cutting knives. The ventilation opening two is connected to the bottom of the side wall of the bag filter through a connecting pipe one. An air reverse blower is also arranged on one side of the bag filter.

5. The dynamic-static switchable closed-loop circulation drying system according to claim 4, characterized in that: An induced draft fan is arranged on the side of the air reverse blower away from the bag filter. An air inlet end one of the induced draft fan is connected to an air outlet two at the top of the side wall of the bag filter through a connecting pipe two. An air outlet end one of the induced draft fan is connected to the heat energy recovery mechanism through a pipeline one. An air outlet end two of the air reverse blower is connected to the bag filter through a connecting pipe three, and an air inlet end two is connected to the pipeline one through a connecting pipe four.

6. The dynamic-static switchable closed-loop circulation drying system according to claim 5, characterized in that: The described heat energy recovery mechanism includes a condensing unit and a heat exchanger. The first pipeline is communicated with the inner cavity of the condensing unit. One end of the condensing unit away from the first pipeline is connected to one end of the heat exchanger. The cold water pipeline of the condensing unit is connected in series with the heat exchange pipes of the heat exchanger. One end of the heat exchanger is connected to one end of the electric heating box, and the other end of the electric heating box is connected to the other end of the circulating ventilation pipeline.

7. The dynamic-static switchable closed-loop circulation drying system according to claim 6, characterized in that: The described nitrogen supply mechanism is connected to the electric heating box through the second pipeline. Oxygen concentration sensors are respectively arranged in the drying main machine, the drying tower, and the static drying box. The water inlet and outlet of the condensing unit are respectively connected to the water outlet end and the water inlet end of the water chiller through the third pipeline and the fourth pipeline.

8. A dynamic-static switchable closed-loop drying system according to claim 7, characterized in that: The described static drying mechanism includes a static drying box. The static drying box is provided with a sealing door. A number of trays for carrying whole raw shrimps are arranged in the static drying box. An exhaust pipe 1 is arranged on the side wall of the static drying box. The branch pipeline includes branch pipeline A and branch pipeline B. One end of branch pipeline A is connected to connecting pipe 1, and the other end is connected to the air outlet end 3 of the static drying box. One end of branch pipeline B is connected to the air inlet end 3 of the static drying box, and the other end is connected to the circulating ventilation pipeline through the first three-way joint. The end of the exhaust pipe 1 is provided with a second three-way joint. One free end of the second three-way joint is communicated with the outside air through the ventilation pipe 1, and the other free end is connected to branch pipeline A through the ventilation pipe 2. The ventilation pipe 1 and the ventilation pipe 2 are respectively provided with a first electromagnetic flow regulating valve and a second electromagnetic flow regulating valve. The circulating ventilation pipeline is provided with an exhaust pipe 2. The opening end of branch pipeline A facing connecting pipe 1 is provided with a filter screen for filtering shrimp powder. The branch pipeline A, branch pipeline B, circulating ventilation pipeline, exhaust pipe 2, and connecting pipe 1 are respectively provided with a third electromagnetic flow regulating valve, a fourth electromagnetic flow regulating valve, a fifth electromagnetic flow regulating valve, a sixth electromagnetic flow regulating valve, and a seventh electromagnetic flow regulating valve. The fifth electromagnetic flow regulating valve is arranged on the side of the first three-way joint facing the drying tower, and the seventh electromagnetic flow regulating valve is located above branch pipeline A. Temperature and humidity sensors are respectively arranged on the inner wall of the drying main machine, the inner wall of the drying tower, the inner cavity of the condensing unit, and the inner wall of the static drying box. A second air pressure sensor is arranged in the static drying box. The control system is a PLC controller.

9. The working method of a dynamic-static switchable closed-loop circulation drying system as claimed in claim 8, It is characterized by including: a dynamic drying mode and a static drying mode. For all drying modes, first, the nitrogen supply mechanism is turned on. The control system makes the heated nitrogen enter the drying system through the induced draft fan, opens the exhaust valve 1 and the exhaust valve 2 to reduce the oxygen in the drying system to the set standard, and then closes the exhaust valve 2 and the nitrogen supply mechanism. The specific dynamic drying mode is as follows: Close the third electromagnetic flow regulating valve and the fourth electromagnetic flow regulating valve, so that the heated nitrogen gas circulates in the closed-loop pipeline formed by the circulating ventilation pipeline, the drying main machine, the drying tower, the first connecting pipe, the bag filter, the second connecting pipe, the induced draft fan, the first pipeline, the condensing unit, the heat exchanger, and the electric heating box, and dry the shrimp pellet raw materials in the drying main machine. The moisture in the hot nitrogen gas is discharged through the condensing unit, and the dried shrimp pellet raw materials are discharged through the discharge port of the drying main machine. The specific static drying mode is as follows: Place the whole shrimp raw materials on the trays of the static drying oven in advance. Open the third electromagnetic flow regulating valve and the fourth electromagnetic flow regulating valve, and close the fifth electromagnetic flow regulating valve and the seventh electromagnetic flow regulating valve, so that the hot nitrogen gas circulates between the branch pipeline A, the lower part of the first connecting pipe, the bag filter, the second connecting pipe, the induced draft fan, the first pipeline, the condensing unit, the heat exchanger, the electric heating box, the circulating ventilation pipeline on the side of the first three-way joint far from the drying tower, the first three-way joint, the branch pipeline B, and the static drying oven to realize the drying of the whole shrimp raw materials.

10. The working method of a dynamic-static switchable closed-loop circulation drying system as described in claim 9, characterized in that: The working method further includes a drying mode in which dynamic and static are carried out simultaneously, including: One end of the static drying oven is connected to the nitrogen output pipeline of the condensing unit through the connecting pipeline B, and the other end is connected to the first pipeline through the connecting pipeline A. The connecting pipeline A is provided with a drainage fan and an electric valve. By controlling the third electromagnetic flow regulating valve and the fourth electromagnetic flow regulating valve, the nitrogen gas flow rate flowing through the static drying oven is regulated. When the temperature in the static drying oven is lower than the set value range, increase the flow rates of the third electromagnetic flow regulating valve and the fourth electromagnetic flow regulating valve to make the temperature in the static drying oven reach the set value range. When the temperature in the static drying oven is higher than the set value range, reduce or close the third electromagnetic flow regulating valve and the fourth electromagnetic flow regulating valve, and open the electric valve and the drainage fan to input the nitrogen gas that has not been heated by the heat exchanger into the static drying oven through the connecting pipeline B, so that the temperature in the static drying oven returns to the set value range, and at the same time, the nitrogen gas output through the connecting pipeline A is discharged of excess moisture through the condensing unit again. The working method further includes a method of grading and screening, specifically: In the dynamic drying mode or the drying mode in which dynamic and static are carried out simultaneously, open the sealing fan, and the control system controls the power of the sealing fan based on the signal of the first air pressure sensor. Some of the small-particle-size raw materials in the shrimp pellet raw materials are driven by the nitrogen gas flow to the cutter position and are chopped into smaller particles. Under the set air pressure data environment, the shrimp powder particles that meet the air pressure dynamic characteristics enter the bag filter through the first connecting pipe for recovery, and the remaining shrimp pellet particles are recovered through the drying main machine; By changing the power of the sealing fan, the grading of shrimp pellet particles with different particle sizes is realized.

Images