Tobacco stem redrying system and redrying method thereof

Abstract

The invention discloses a tobacco stem re-drying system and a re-drying method thereof. The re-drying system comprises a temperature increasing and pressurizing device A or a temperature increasing and pressurizing device B, a tobacco stem spreading machine and a tobacco stem re-drying machine which are arranged in sequence. The temperature increasing and pressurizing equipment A comprises a shell A, a heating pusher I A or a heating pusher II A, isolation airlocks A respectively arranged at a feed port A and a discharge port A, and a compressed air guide pipe A connected to the front end face of the shell A; the warming and pressurizing equipment B comprises a shell B, a heating pusher B, isolation airlocks B respectively arranged at a feed port B and a discharge port B, and a compressed air guide pipe B connected to the front end face of the shell B. Tobacco stems are subjected to first-stage temperature increasing and pressurizing through temperature increasing and pressurizing equipment and then enter a second-stage pressure releasing and stem expanding, the tobacco stems are fed into a tobacco stem redrying machine through a tobacco stem spreading machine to be subjected to third-stage drying and cooling, and needed redried tobacco stems are obtained. The tobacco stem redryer can improve the tobacco stem processing quality, reduce the drying hot air temperature, improve the heat energy utilization rate and eliminate the fire hazard of the tobacco stem redryer.

Description

Technical Field

[0001] The invention belongs to the technical field of tobacco processing, and in particular relates to a tobacco stem redrying system and a redrying method thereof. Background Art

[0002] Tobacco stem redrying is an important link in the leaf threshing and redrying production line. The main process purpose of tobacco stem redrying is to redry wet tobacco stems with a wet basis moisture content of 18% to 20% and a temperature of 25℃ to 35℃ to make them dry tobacco stems with a wet basis moisture content of 10% to 13% and a stem temperature of ≤55℃, so as to facilitate subsequent packaging, storage and aging fermentation.

[0003] At present, tobacco stem redrying is completed by tobacco stem redrying machine. The tobacco stem redrying machine is mainly composed of a feed end, a horizontal tunnel, a discharge end and a conveyor belt. The length of the horizontal tunnel is 15m to 22m, and it is divided into drying zone 1, drying zone 2 and cooling zone from the tunnel feed port to the tunnel discharge port; the conveyor belt is a horizontal circulating metal mesh of a certain width, which connects the feed end of the tobacco stem redrying machine and passes through the horizontal tunnel to the discharge end. When working, the tobacco stems on the belt pass through the drying zone 1, drying zone 2 and cooling zone from the feed end in turn, and finally output from the discharge end. Drying zone 1 and drying zone 2 each contain their own hot air system, and the hot air flow direction is perpendicular to the movement direction of the belt. In drying zone 1, the hot air moves upward from the bottom of the belt through the belt and the tobacco stem material layer (called lower air intake); in drying zone 2, the hot air moves downward from the top of the belt through the tobacco stem material layer and the belt (called upper air intake); the cooling zone uses room temperature air and lower air intake to cool the tobacco stems.

[0004] The incoming material temperature of the tobacco stem redrying machine is the ambient temperature, generally 25℃~35℃. According to the processing process of the tobacco stem redrying machine on the tobacco stems, the tobacco stems undergo three stages during the redrying process: heating, constant temperature dehydration, and cooling. Both heating and constant temperature dehydration are carried out by convection between the tobacco stems and hot air, and the tobacco stems are also accompanied by a certain degree of dehydration during the heating process. Since the tobacco stem tissue has a certain thickness (equivalent diameter 3~8mm), the surface temperature of the tobacco stem is higher than the internal temperature during the heating process. The surface tissue is first dehydrated and shrunk, and the formation of a dense structure increases the difficulty of the internal moisture to diffuse outward, and at the same time increases the thermal resistance of the hot air heat transfer to the interior of the tobacco stem. These unfavorable factors have led to some problems in the existing tobacco stem redrying methods.

[0005] Existing tobacco stem re-roasting machines make it difficult to roast the tobacco stems thoroughly. Although the moisture content on the surface of the tobacco stems can reach the specified 10% to 13%, the moisture content inside the tobacco stems is higher than that on the surface, and the average moisture content exceeds the standard, causing the tobacco stems to turn black during the later storage process, which directly affects the use of the tobacco stems.

[0006] To ensure that the tobacco stems are thoroughly roasted, the tobacco stem re-roasting machine often uses a hot air temperature higher than 120°C, which exceeds the 110°C hot air process requirement and makes the discharge temperature higher than the index requirement. As described in the article "Improvement Measures to Reduce the Temperature of Finished Tobacco Stems" in the 12th issue of Strait Science in 2009, the hot air temperature of the tobacco stem re-roasting machine can reach up to 128°C, and the average discharge temperature of the equipment is 67.3°C. In fact, too high a hot air temperature will also cause the exhaust gas temperature of the tobacco stem re-roasting machine to be too high, and the exhaust gas temperature is generally higher than 100°C, resulting in a large waste of energy.

[0007] In addition, excessively high hot air temperatures pose a fire hazard to processing equipment. As described in the article "Optimization of Fire Protection System Design of Tobacco Stem Redrying Machine in Leaf Threshing and Redrying Enterprises" in the 2020 Issue 1 (Part 2) of Equipment and Management, hot air exceeding 120°C can easily ignite paper, hemp, cotton, hair and other debris mixed in the tobacco stems. In fact, there have been cases where tobacco stem redrying machines caught fire during processing.

[0008] Compared with tobacco leaves, tobacco stems are thicker and take much longer to dry and dehydrate. Loose tobacco stems are conducive to faster drying of tobacco stems. In the prior art, tobacco stem expansion methods and equipment, such as the steam stem moistening method disclosed in Chinese patent document CN101862021B, place the tobacco stems in a water vapor environment at a certain temperature and pressure, use the temperature and pressure of water vapor to achieve rapid penetration of water into the tobacco stems, and then quickly release the pressure to achieve the purpose of puffing the tobacco stems. The method is to directly increase the temperature and pressurize the tobacco stems with external water vapor, with the purpose of quickly moistening the tobacco stems. As a result, the moisture and temperature of the tobacco stems increase rapidly, and the tobacco stems are puffed at the same time. However, the tobacco stems processed by this method increase the amount of dehydration in the subsequent re-roasting and dehydration. Summary of the invention

[0009] In view of the above-mentioned problems existing in the existing tobacco stem redrying methods and equipment, the present invention proposes a new tobacco stem redrying system and redrying method, which decomposes the prior art of directly "drying and cooling" the incoming tobacco stems with convection air into three stages of "warming and pressurizing, pressure release and stem expansion, and drying and cooling", and processes the tobacco stems in sequence to improve the processing quality of the tobacco stems, reduce the temperature of the drying hot air, and improve the utilization rate of thermal energy, while eliminating the fire hazard of the tobacco stem redrying machine.

[0010] The technical solution 1 adopted by the present invention is as follows: A tobacco stem redrying system, comprising a sequentially arranged A temperature increasing and pressurizing device or B temperature increasing and pressurizing device, a tobacco stem spreading machine and a tobacco stem redrying machine; The temperature-increasing and pressurizing equipment includes an A shell, an A heating pusher I arranged in the A shell, an A feed port and an A discharge port respectively arranged at the lower end and the higher end of the A shell, an A isolation air lock respectively arranged at the A feed port and the A discharge port, and an A compressed air guide pipe connected to the front end face of the A shell. The A isolation air lock and the inner cavity of the A shell form a closed chamber together to ensure that the internal pressure of the closed chamber is isolated from the outside; the A isolation air lock connected to the A feed port introduces foreign tobacco stems into the closed chamber, and the tobacco stems that have been heated and pressurized in the closed chamber are discharged from the closed chamber through the A isolation air lock connected to the A discharge port; The A shell is a long cylindrical structure, closed at both ends, and arranged at a certain angle to the horizontal plane; the A shell is provided with an A feed port at the lower end and an A discharge port at the higher end; the A shell is a double-layer hollow structure, an A external heat medium inlet is provided on the outer surface of the higher end of the A shell near the A discharge port, and an A external heat medium outlet is provided on the outer surface of the lower end near the A feed port, and the heat medium enters the hollow cavity of the A shell from the A external heat medium inlet and is discharged from the A external heat medium outlet; The A heating pusher I comprises a core shaft, a spiral blade and an A rotating joint I located at both ends of the core shaft; the A heating pusher I passes through the interior of the A shell and is fixed at both ends of the A shell through the core shaft, the A heating pusher I is driven by a motor reducer through, including but not limited to, a chain drive, and the driving wheel is sleeved on the outer circumferential surface of the core shaft between the low-end A rotating joint I and the A shell; The core shaft and the spiral blades are both hollow structures, and the hollow part of the core shaft includes an inflow chamber, a straight-through chamber and an outflow chamber. The straight-through chamber runs through both ends of the core shaft and is isolated from the inflow chamber and the outflow chamber. The A rotary joint I includes an outer tube I, a dynamic seal I, a dynamic seal II, and an outer shell I. The hollow part of the spiral blade is respectively connected with the inflow chamber and the outflow chamber, the inflow chamber is connected with the outer tube I of the A rotary joint I at the high end of the core shaft, one end of the straight-through chamber is inserted into the inner hole of the dynamic seal I of the A rotary joint I at the high end, and the outflow chamber is connected with the outer tube I of the A rotary joint I at the low end of the core shaft. The tube I is connected, and the other end of the straight-through cavity is inserted into the inner hole of the dynamic seal I of the low-position end A rotary joint I; two independent heat media and two ports of the high-position end A rotary joint I of the core shaft enter the inflow cavity and the straight-through cavity respectively; the heat media entering the inflow cavity passes through the hollow part of the spiral blade to reach the outflow cavity, and the heat media entering the straight-through cavity passes through the entire core shaft to reach the other end; the heat media from the outflow cavity and the heat media from the straight-through cavity are discharged respectively through the two ports of the low-position end A rotary joint I of the core shaft; the two heat media flowing through the core shaft and the spiral blades transfer heat to the tobacco stems respectively; The A heating pusher II comprises a core shaft, a spiral blade and an A rotary joint II located at both ends of the core shaft, the spiral blade is spirally fixed on the outer circumferential surface of the core shaft, and an A rotary joint II is connected to the high and low ends of the core shaft respectively; the A heating pusher II passes through the interior of the A shell and is fixed at both ends of the A shell through the core shaft, the A heating pusher II is driven by a motor reducer through a chain transmission method including but not limited to, and the driving wheel is sleeved on the outer circumferential surface of the core shaft between the low end A rotary joint II and the A shell; The core shaft comprises a high-end hollow structure, a low-end hollow structure, and a middle solid part; the A rotary joint II comprises an outer tube II, a dynamic seal, and an outer shell II; the high-end hollow structure and the low-end hollow structure of the core shaft are respectively connected with the hollow part of the spiral blades and are respectively connected with the outer tube II of the A rotary joint II; The heat medium enters the hollow structure at the high end of the mandrel through the interface of the A rotary joint II at the high end of the mandrel. The heat medium entering the hollow structure passes through the hollow part of the spiral blade and reaches the hollow structure at the low end of the mandrel, and is discharged through the interface of the A rotary joint II connected to the hollow structure. The heat medium flowing through the spiral blade of the A heating pusher II transfers heat to the tobacco stem through the outer surface of the spiral blade. The heat medium includes hot water, hot oil or water vapor; The A isolation air lock and the inner cavity of the A shell together form a closed chamber to ensure that the internal pressure of the closed chamber is isolated from the outside; the A isolation air lock connected to the feed port introduces foreign tobacco stems into the closed chamber, and the tobacco stems that have been heated and pressurized in the closed chamber are discharged from the closed chamber through the A isolation air lock connected to the A discharge port; The B heating and pressurizing equipment includes a B shell, a B heating pusher arranged in the B shell, a B isolation air lock respectively arranged at the B feed port and the B discharge port, and a B compressed air guide pipe connected to the discharge end face of the B shell; The B shell is a long cylindrical structure, closed at both ends, and arranged at a certain downward angle from the B feed port to the B discharge port; the B feed port is arranged above the high end of the B shell, and the B discharge port is arranged below the low end; the B shell is a double-layer hollow structure, and a B external heat medium inlet is arranged on the outer surface of the end face of the B shell near the B feed port, and a B external heat medium outlet is arranged on the outer surface of the end face near the B discharge port. The heat medium enters the hollow cavity of the B shell from the B external heat medium inlet and is discharged from the B external heat medium outlet; The bottom of the working inner cavity of the B shell is composed of two arc surfaces, and its cross-sectional shape is similar to an ω shape. The shape and size of the inner cavity match the B heating pusher; The B heating pusher is composed of two blade shafts parallel to each other, each blade shaft includes a hollow shaft, a plurality of blades evenly distributed along the shaft length, B rotary joints at both ends of the hollow shaft, an inlet pipe and an outlet pipe, and the blades on the two blade shafts are arranged in an interlaced manner; the blades are wedge-shaped hollow closed structures with a fan-shaped axial direction and a thickness that changes from thin to thick, and the hollow part of each blade is connected to the inner cavity of the hollow shaft by the inlet pipe and the outlet pipe; the B heating pusher runs through the interior of the B shell and is fixed at both ends of the B shell through a core shaft, and the B heating pusher is driven by a motor reducer through a chain drive method including but not limited to, and the driving wheel is sleeved on the outer cylindrical surface of the hollow shaft between the feed end of the B shell and the B rotary joint; The heat medium enters the inner cavity of the hollow shaft through the interface of the rotary joint B at the high end of the hollow shaft, enters the hollow part of each blade through the inlet pipe, and then flows back to the inner cavity of the hollow shaft through the outlet pipe, and is discharged through the interface of the rotary joint B at the low end of the hollow shaft. The heat medium includes hot water, hot oil or water vapor; The B isolation air lock and the inner cavity of the B shell together form a closed chamber to ensure that the internal pressure of the closed chamber is isolated from the outside world; the B isolation air lock connected to the B feed port introduces foreign tobacco stems into the closed chamber, and the tobacco stems that have been heated and pressurized in the closed chamber are discharged from the closed chamber through the B isolation air lock connected to the B discharge port.

[0011] The tobacco stem redrying method of the tobacco stem redrying system of the present invention comprises the following steps: S1. One-stage heating and pressurization: The heat medium is introduced into the hollow cavity of the shell, the hollow part of the core shaft or hollow shaft, and the hollow part of the spiral blade or paddle, and the tobacco stems are sent into the closed chamber of the heating and pressurization equipment. During the process of the heated pusher pushing the tobacco stems forward continuously, the heat medium is used to heat the tobacco stems in the closed chamber in a non-direct contact manner, so that the temperature of the tobacco stems gradually rises to 70℃~130℃; the water vapor overflowing from the tobacco stems during the heating process is sealed in the closed chamber to form a water vapor partial pressure, and the closed chamber pressure is established and maintained mainly based on the water vapor partial pressure. The closed chamber pressure continuously penetrates, pressurizes and maintains the internal tissue of the tobacco stems. At the same time, compressed air is introduced through the compressed air inlet pipe to supplement and adjust the closed chamber pressure, so that the internal surface pressure of the closed chamber reaches 0kg / cm 2 ~6kg / cm 2 ; S2, two-stage pressure release and stem expansion: at the outlet of the heating and pressurizing equipment, the tobacco stems that have undergone the first stage of heating and pressurization are discharged into an open tobacco stem spreading machine in a zero gauge pressure environment, so that the internal pressure of the tobacco stem tissue is quickly released to zero gauge pressure, and expanded tobacco stems with a temperature of 70°C to 110°C and a wet basis moisture content similar to that of the feed are obtained; S3, three-stage drying and cooling: send the tobacco stems in the tobacco stem spreading machine into the tobacco stem redrying machine, use convection air with a temperature of ≤110℃ to heat and dry the tobacco stems, and use convection air with a temperature of ≤35℃ to cool the tobacco stems, so that the wet basis moisture content of the tobacco stems reaches 10% to 13%, and the wet basis moisture content inside and outside the tobacco stems is consistent, and the tobacco stem temperature is ≤55℃.

[0012] Furthermore, the discharge temperature of the expanded tobacco stems is 70°C to 110°C, and the moisture content on a wet basis is similar to that of the feed tobacco stems.

[0013] Furthermore, the heat medium is hot water, hot oil or water vapor.

[0014] Furthermore, in the above step S1, the gauge pressure of the external compressed air is 0 kg / cm 2 ~8kg / cm 2 , the temperature is room temperature ~ 150℃.

[0015] The present invention first delivers the incoming tobacco stems into the heating and pressurizing equipment for a stage of heating and pressurizing. The incoming tobacco stems continuously enter the closed chamber of the heating and pressurizing equipment through the rotating isolation air lock, and the heating pusher in the closed chamber pushes the tobacco stems to move from the shell feed port to the shell discharge port. The heat medium flowing through the hollow cavity of the shell, the core shaft of the heating pusher and the hollow part of the spiral blade simultaneously conducts heat conduction to heat the tobacco stems in the closed chamber. The tobacco stems are continuously heated and heated during the movement process, and the temperature at the discharge port reaches 70°C to 130°C. While the tobacco stems are heated and heated, part of the moisture therein is converted from liquid to gas due to the temperature increase and transferred to the closed chamber. A closed chamber pressure dominated by the partial pressure of water vapor is established and maintained in the closed chamber, and this pressure osmotically pressurizes the internal tissue of the tobacco stems in the closed chamber. External compressed air supplements and adjusts the closed chamber pressure to make the closed chamber surface pressure reach 0kg / cm 2 ~6kg / cm 2 . The tobacco stems that move to the discharge port of the shell are discharged into an open 0 gauge pressure environment through a rotating isolation air lock, and the internal tissue pressure of the tobacco stems is quickly released to the open 0 gauge pressure environment and returns to 0, completing the pressure release and expansion process. The tobacco stems that have been heated and expanded are sent to the feed end of the tobacco stem redrying machine by the tobacco stem spreading machine, covering the width of the tobacco stem redrying machine mesh belt to form a material layer of uniform thickness. Driven by the mesh belt, the material layer passes through the drying zone 1, drying zone 2 and cooling zone of the tobacco stem redrying machine in turn, and is output from the discharge end, so that the wet basis moisture content of the tobacco stems reaches 10% to 13% and the temperature drops below 55°C. After the above process, the tobacco stems are heated and pressurized, pressure released and expanded, and dried and cooled.

[0016] The beneficial effects of the present invention are as follows: 1. Compared with the tobacco stem re-roasting equipment and re-roasting method in the prior art, the step-by-step treatment method of heating and pressurizing, pressure releasing to expand the stems, and drying and cooling adopted in the present invention can significantly improve the quality of tobacco stem re-roasting. The moisture content inside and outside the tobacco stems after roasting is uniform, reaching the processing technology requirement of 10% to 13%, avoiding the blackening of the tobacco stems during the later storage process due to incomplete roasting.

[0017] 2. Under the premise of ensuring that the tobacco stems are completely roasted, the convection hot air temperature of the tobacco stem re-roasting machine is lower than 110°C, and the exhaust gas temperature of the equipment is simultaneously reduced, effectively reducing energy waste of the equipment and eliminating the fire hazard of the equipment.

[0018] 3. Lower drying hot air temperature is conducive to reducing the temperature of tobacco stems after baking, so that the discharge temperature is ≤55℃, avoiding the burning of tobacco stems after packaging.

[0019] 4. The fluffy tobacco stem texture is conducive to the subsequent processing such as the moisture regain of the tobacco stem. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of Example 1 of a tobacco stem redrying system of the present invention; Figure 2 for Figure 1 A schematic diagram of the structure of the heating and pressurizing device embodiment 1; Figure 3 for Figure 2 A magnified view of the feed port area of ​​the heating and pressurizing equipment; Figure 4 for Figure 2 A magnified view of the discharge port area of ​​the heating and pressurizing equipment; Figure 5 for Figure 3 , Figure 4 A schematic diagram of the structure of the cross-section of the rotary joint I; Figure 6 for Figure 1 A schematic diagram of Example 2 of the temperature increasing and pressurizing device; Figure 7 for Figure 6 A magnified view of the feed port area of ​​the heating and pressurizing equipment; Figure 8 for Figure 6 A magnified view of the discharge port area of ​​the heating and pressurizing equipment; Fig. 9 for Figure 7 , Figure 8 A schematic diagram of the structure of the cross-section of the rotary joint II; Fig.10 This is a schematic diagram of Example 3 of a tobacco stem redrying system of the present invention; Fig.11 for Fig.10 Schematic diagram of the structure of the heating and pressurizing equipment B; Fig.12 for Fig.11 Schematic diagram of the cross-sectional structure of the temperature-increasing and pressurizing equipment B in FIG. Fig.13 The present invention is a process flow chart of the method.

[0021] The numbers in the figure are: 1—A heating and pressurizing equipment; 11—A shell, 111—A feed port, 112—A discharge port, 113—A external heat medium inlet, 114—A external heat medium outlet, 12a—A heating pusher I, 12a1—core shaft, 12a11—inflow cavity, 12a12—through cavity, 12a13—outflow cavity, 12a2—spiral blade, 12a3—A rotary joint I, 12a31—outer tube I, 12a32—dynamic seal I, 12a33—dynamic seal II, 12a34—housing I, 12b—A heating pusher II, 12b1—core shaft, 12b11—high end hollow structure, 12b12—low end hollow structure, 12b2—A rotary joint II, 12b21—outer tube II, 12b22—dynamic seal, 12b23—housing II; 13-A isolating air lock, 14-A compressed air guide pipe, 2—tobacco stem spreading machine; 3—tobacco stem redrying machine; 4—B heating and pressurizing equipment; 41—B housing, 411—B feed inlet, 412—B discharge outlet, 413—B external heat medium inlet, 414—B external heat medium outlet, 42—B heating pusher, 421—hollow shaft, 422—paddle, 423—B rotary joint, 424—inflow pipe, 425—outflow pipe, 43-B isolating air lock, 44-B compressed air guide pipe. DETAILED DESCRIPTION

[0022] In order to make the technical means of the present invention and the technical effects achieved by the same clearer, the contents of the present invention are further described below in conjunction with the accompanying drawings.

[0023] like Figure 1 As shown, the tobacco stem redrying system of the present invention comprises a sequentially arranged inclined A temperature increasing and pressurizing device 1, a tobacco stem spreading machine 2 and a tobacco stem redrying machine 3. Example 1

[0024] like Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, the A heating and pressurizing equipment 1 includes an A shell 11, an A heating pusher 112a arranged in the A shell, an A feed port 111 respectively opened at the low end of the A shell and an A discharge port 112 respectively opened at the high end, an A isolation air lock 13 respectively arranged at the A feed port and the A discharge port, and an A compressed air guide pipe 14 connected to the front end face of the A shell.

[0025] The A shell 11 is a long cylindrical structure with closed ends and is arranged at a certain angle to the horizontal plane. The A feed port 111 is arranged above the low end of the A shell, and the A discharge port 112 is arranged below the high end. The A feed port 111 and the A discharge port 112 are respectively connected to an A isolation air lock 13. The A isolation air lock 13 and the inner cavity of the A shell 11 together form a closed chamber to ensure that the internal pressure of the closed chamber is isolated from the outside. The A isolation air lock 13 connected to the A feed port 111 is used to introduce foreign tobacco stems into the closed chamber. The tobacco stems that have been heated and pressurized in the closed chamber are discharged from the closed chamber through the A isolation air lock 13 connected to the A discharge port 112. The A heating pusher I 12a penetrates the interior of the A shell 11 and is fixed to both ends of the A shell through its core shaft. The A heating pusher I 12a can rotate freely relative to the A shell 11. The rotating A heating pusher I 12a pushes the tobacco stems from the A feed port 111 to the A discharge port 112. The A compressed air guide pipe 14 is connected to the closed chamber at the lower end of the A shell 11 to introduce compressed air into the closed chamber to supplement and adjust the pressure of the closed chamber.

[0026] The A shell 11 is a double-layer hollow structure, and an A external heat medium inlet 113 is provided on the high-end outer surface of the A shell near the A discharge port 112, and an A external heat medium outlet 114 is provided on the low-end outer surface near the A feed port 111. Heat medium can enter the hollow cavity of the A shell 11 from the A external heat medium inlet 113 and be discharged from the A external heat medium outlet 114. The heat medium flowing through the hollow cavity of the A shell transfers heat to the tobacco stems through the inner cavity surface of the A shell, and the heat medium includes hot water, hot oil or water vapor.

[0027] The A heating pusher I 12a includes a core shaft 12a1, a spiral blade 12a2 and an A rotary joint I 12a3. The spiral blade 12a2 is spirally fixed on the outer circumferential surface of the core shaft 12a1, and an A rotary joint I 12a3 is connected to the high and low ends of the core shaft 12a1 respectively. The core shaft 12a1 and the spiral blade 12a2 are both hollow structures. The hollow part of the core shaft 12a1 includes an inflow chamber 12a11, a straight-through chamber 12a12 and an outflow chamber 12a13; the straight-through chamber 12a12 runs through both ends of the core shaft and is isolated from the inflow chamber 12a11 and the outflow chamber 12a13. The hollow part of the spiral blade 12a2 is connected to the inflow chamber 12a11 and the outflow chamber 12a13 respectively. The structure of the A rotary joint I 12a3 is as follows: Figure 5As shown, it includes an outer tube I 12a31, a dynamic seal I12a32, a dynamic seal II12a33, and an outer shell I 12a34. The inflow chamber 12a11 is connected to the outer tube I 12a31 of the high-end A rotary joint I 12a3 of the core shaft, and one end of the straight-through chamber 12a12 is inserted into the inner hole of the dynamic seal I12a31 of the high-end A rotary joint I, so that one end of the straight-through chamber is connected to the pipeline of the high-end A rotary joint I; the outflow chamber 12a13 is connected to the outer tube I 12a31 of the low-end A rotary joint I 12a3 of the core shaft, and the other end of the straight-through chamber 12a12 is inserted into the inner hole of the dynamic seal I12a31 of the low-end A rotary joint I, so that the other end of the straight-through chamber is connected to the pipeline of the low-end A rotary joint I. The outer tube I channel of the high-low end A rotary joint I of the core shaft is isolated from the inner pipeline formed by the straight-through chamber. Two independent heat media Fa and Fb enter the inflow cavity and the straight-through cavity respectively through the two ports of the A rotary joint I at the high end of the core shaft; the heat media Fa entering the inflow cavity reaches the outflow cavity after passing through the hollow part of the spiral blade, and the heat media Fb entering the straight-through cavity reaches the other end through the entire core shaft; the heat media Fa from the outflow cavity and the heat media Fb from the straight-through cavity are discharged respectively through the two ports of the A rotary joint I at the low end of the core shaft. The two heat media flowing through the core shaft 12a1 and the spiral blade 12a2 of the A heating pusher I 12a transfer heat to the tobacco stems through the outer surface of the core shaft 12a1 and the outer surface of the spiral blade 12a2 respectively. The heat media include hot water, hot oil or water vapor, and the pressure and flow rate of the two heat media can be adjusted separately.

[0028] In order to ensure the expansion effect of tobacco stems, compressed air is introduced through the compressed air guide pipe 14 to supplement and adjust the pressure of the closed chamber so that the internal surface pressure of the closed chamber reaches 0kg / cm 2 ~6kg / cm 2 , in order to achieve the desired expansion effect. Example 2

[0029] The main difference from Example 1 is that the structure of the A heating pusher II 12b of the A heating and pressurizing device 1 in Example 2 is different. Figure 6 , Figure 7 , Figure 8 , Fig. 9 shown.

[0030] The A heating pusher II 12b includes a core shaft 12b1, a spiral blade 12a2 and an A rotary joint II 12b2 located at both ends of the core shaft. The spiral blade 12a2 is a hollow structure and is spirally fixed on the outer circumferential surface of the core shaft 12b1. An A rotary joint II 12b2 is connected to the high and low ends of the core shaft 12b1. The core shaft 12b1 includes a high end hollow structure 12b11, a low end hollow structure 12b12, and a solid middle part. The hollow structures 12b11 and 12b12 are respectively provided with through holes connected to the hollow part of the spiral blade 12a2. The structure of the A rotary joint II 12b2 is as follows: Fig. 9 As shown, it includes an outer tube II 12b21, a dynamic seal 12b22, and an outer shell II 12b23. The hollow structure 12b11 at the high end and the hollow structure 12b12 at the low end of the core shaft 12b1 are respectively connected to the outer tube II 12b21 of the A rotary joint II 12b2.

[0031] The heat medium enters the hollow structure 12b11 at the upper end of the mandrel 12b1 through the interface of the A rotary joint II at the upper end of the mandrel. The heat medium entering the hollow structure 12b11 passes through the hollow part of the spiral blade and reaches the hollow structure 12b12 at the lower end of the mandrel 12b1, and is discharged through the interface of the A rotary joint II connected to the hollow structure 12b12. The heat medium flowing through the spiral blade 12a2 of the A heating pusher II 12b transfers heat to the tobacco stem through the outer surface of the spiral blade, and the heat medium includes hot water, hot oil or water vapor. Example 3

[0032] The main difference from Example 1 is that Example 3 uses B heating and pressurizing device 4, whose structure and arrangement are different from A heating and pressurizing device 1. The arrangement and structure of B heating and pressurizing device 4 in Example 3 are as follows: Fig.10 , Fig.11 , Fig.12 shown.

[0033] The B heating and pressurizing equipment 4 includes a B shell 41, a B heating pusher arranged in the B shell, a B isolation air lock 43 respectively arranged at the B feed port and the B discharge port, and a B compressed air guide pipe 44 connected to the front end surface of the B shell 41.

[0034] The B shell 41 is a long cylindrical structure, closed at both ends, and arranged at a certain downward angle from the B feed port to the B discharge port; a B feed port 411 is arranged above the high end of the B shell 41, and a B discharge port 412 is arranged below the low end; the B shell is a double-layer hollow structure, and a B external heat medium inlet 413 is arranged on the outer surface of the end face of the B shell near the B feed port 411, and a B external heat medium outlet 414 is arranged on the outer surface of the end face near the B discharge port 412. The heat medium enters the hollow cavity of the B shell from the B external heat medium inlet 413 and is discharged from the B external heat medium outlet 414. The bottom of the working inner cavity of the B shell 41 is composed of two arc surfaces, and its cross-sectional shape is similar to the ω shape. The shape and size of the inner cavity match the B heating pusher.

[0035] The B heating pusher is composed of two blade shafts parallel to each other, each blade shaft includes a hollow shaft 421, a plurality of blades 422 evenly distributed along the shaft length, B rotary joints 423 at both ends of the hollow shaft 421, an inlet pipe 424 and an outlet pipe 425, and the blades on the two blade shafts are arranged in an interlaced manner. The blades 422 are wedge-shaped hollow closed structures with a fan-shaped axial direction and a thickness that changes from thin to thick. The hollow part of each blade is connected to the inner cavity of the hollow shaft 421 by the inlet pipe 424 and the outlet pipe 425; the B heating pusher runs through the interior of the B shell 41 and is fixed at both ends of the B shell 41 through a hollow shaft. The B heating pusher is driven by a motor reducer through a chain drive method including but not limited to, and the driving wheel is set on the outer cylindrical surface of the hollow shaft between the feed end of the B shell and the B rotary joint.

[0036] The heat medium enters the inner cavity of the hollow shaft 421 through the interface of the rotary joint 423 at the high end B of the hollow shaft 421, enters the hollow part of each blade 422 through the inlet pipe 424, and then flows back to the inner cavity of the hollow shaft through the outlet pipe 425, and is discharged through the interface of the rotary joint 423 at the low end B of the hollow shaft. The heat medium includes hot water, hot oil or water vapor.

[0037] The B isolation air lock 43 and the inner cavity of the B shell 41 together form a closed chamber to ensure that the internal pressure of the closed chamber is isolated from the outside. The B isolation air lock connected to the B feed port 411 introduces foreign tobacco stems into the closed chamber. The two blade shafts turn in opposite directions, and the blades rotate in opposite directions. The two inclined surfaces of the blades repeatedly stir, squeeze and push the tobacco stems to move toward the discharge port. The tobacco stems are continuously heated by the blades, the hollow shaft and the inner surface of the closed chamber, and part of the water in them is converted from liquid to gas due to the temperature increase and transferred to the closed chamber. A closed chamber pressure dominated by the partial pressure of water vapor is established and maintained in the closed chamber. This pressure osmotically pressurizes the internal tissue of the tobacco stems in the closed chamber. The heated and pressurized tobacco stems are discharged into an open 0 gauge pressure environment through the B isolation air lock connected to the B discharge port 412. The internal tissue pressure of the tobacco stems is quickly released to the open 0 gauge pressure environment and returns to 0, completing the pressure release and expansion process.

[0038] In order to ensure the expansion effect of tobacco stems, compressed air is introduced through compressed air lead pipe B 44 to supplement and adjust the pressure of the closed chamber so that the internal surface pressure of the closed chamber reaches 0kg / cm 2 ~6kg / cm 2 , in order to achieve the desired expansion effect.

[0039] After being processed by the heating and pressurizing equipment, the temperature of the tobacco stems arriving at the outlet is 70℃~130℃, and the internal tissue pressure of the tobacco stems is close to or equal to the gauge pressure, usually 0kg / cm 2 ~6kg / cm 2 .

[0040] The temperature of the tobacco stems discharged from the closed chamber through the isolation air lock is 70℃~110℃, and the internal tissue pressure is quickly released to the open 0 gauge pressure environment and returns to 0, achieving tobacco stem tissue expansion.

[0041] The heated and expanded tobacco stems are sent to the feeding end of the tobacco stem re-drying machine 3 by the tobacco stem spreading machine 2, covering the width of the tobacco stem re-drying machine mesh belt to form a material layer with uniform thickness. Driven by the mesh belt, the material layer passes through the drying zone 1, the drying zone 2 and the cooling zone in turn, and then is output from the discharging end of the tobacco stem re-drying machine 3. The drying zone and the cooling zone use convection wind to complete the heating and drying of the tobacco stems and the cooling of the temperature. The hot air temperature in the drying zone is ≤110℃, so that the wet basis moisture content of the tobacco stems reaches 10% to 13%, and the temperature of the tobacco stems drops below 55℃.

[0042] The tobacco stem spreading machine 2 and the tobacco stem redrying machine 3 described in the present invention can both adopt existing technical equipment.

[0043] The method for redrying tobacco stems using the tobacco stem redrying system of the present invention is as follows: Fig.13 As shown, the details are as follows: S1. One-stage heating and pressurization: tobacco stems with a wet basis moisture content of 18% to 20% and a temperature of 25°C to 35°C are fed into the closed chamber of the A heating and pressurizing device 1 (or the B heating and pressurizing device 4) through the A feed port 111 (or the B feed port 411), and hot water or hot oil or water vapor is injected into the hollow cavity of the shell through the A external heat medium inlet 113 (or the B external heat medium inlet 413), and heat medium is injected into the hollow part of the core shaft 12a1 (or the hollow shaft 421) and the hollow part of the spiral blade 12a2 (or the paddle 422) through the rotary joint inlet. When the A heating pusher I 12a or A heating pusher II 12b (or B heating pusher 42) continuously pushes the tobacco stems forward, the tobacco stems in the closed chamber are heated indirectly by the heat medium, so that the temperature of the tobacco stems gradually rises to 70°C to 130°C; the water vapor overflowing from the tobacco stems during the heating process is sealed in the closed chamber to form a water vapor partial pressure, and the closed chamber pressure is established and maintained mainly based on the water vapor partial pressure, and the closed chamber pressure continuously permeates and pressurizes the internal tissue of the tobacco stems; In order to ensure the subsequent expansion effect, external compressed air is used to supplement and adjust the pressure of the closed chamber so that the surface pressure of the closed chamber reaches 0kg / cm 2 ~6kg / cm 2 , in order to achieve the desired expansion effect. The gauge pressure of the external compressed air is 0kg / cm 2 ~8kg / cm 2 , the temperature is room temperature to 150°C. At the same time, ensure that the tobacco stems have enough residence time in the closed chamber (usually 2 to 8 minutes) so that the internal tissue pressure is close to or equal to the closed chamber pressure.

[0044] S2. Second stage of pressure release and expansion of the tobacco stems: At the A outlet 112 (or B outlet 412) of the heating and pressurizing equipment, the tobacco stems that have undergone a stage of heating and pressurization are discharged into an open 0 gauge pressure environment, and the internal pressure of the tobacco stem tissue is quickly released to 0 gauge pressure, obtaining expanded tobacco stems with a temperature of 70°C to 110°C and a wet basis moisture content similar to that of the feed tobacco stems.

[0045] S3, three-stage drying and cooling: The tobacco stems that have undergone the second-stage expansion are sent to the feeding end of the tobacco stem redrying machine 3 by the tobacco stem spreading machine 2, spread over the width of the mesh belt, and form a material layer with uniform thickness. Driven by the mesh belt, the material layer passes through the drying zone 1, drying zone 2 and cooling zone in turn, and then is output from the discharge end of the tobacco stem redrying machine; the drying zone and the cooling zone use convection air to complete the heating and drying of the tobacco stems and the cooling and cooling.

[0046] In the drying zone 1, the tobacco stems enter the drying area at a discharge temperature slightly lower than that of step S2. Tobacco stems ≥100°C directly enter the constant temperature dehydration stage without the need for a heating stage, and tobacco stems <100°C can enter the constant temperature dehydration stage with a slight heating. In both cases, the working section of the drying zone 1 can be fully utilized to dry and dehydrate the tobacco stems. Compared with the low-temperature incoming tobacco stems in the prior art, the dehydration capacity of the high-temperature incoming tobacco stems in the drying zone 1 is 20% to 30% higher. The large dehydration capacity of the drying zone 1 can reduce the dehydration burden of the drying zone 2.

[0047] The loose tobacco stem tissue is conducive to the diffusion of internal moisture outward, and improves the moisture exchange rate between the external convection wind and the tobacco stem. In the drying area, the convection wind with a temperature of ≤110℃ is used to heat and dry the tobacco stems, and in the cooling area, the convection wind with a temperature of ≤35℃ is used to cool the tobacco stems. The wet basis moisture content of the tobacco stems reaches 10% to 13%, and the wet basis moisture content inside and outside the tobacco stems is consistent, and the tobacco stem temperature is ≤55℃.

[0048] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A tobacco stem redrying system, characterized in that: It comprises a heating and pressurizing device (1) or (4), a tobacco stem spreading machine (2) and a tobacco stem redrying machine (3) which are arranged in sequence; The temperature increasing and pressurizing device (1) comprises an A shell (11), an A heating pusher I (12a) or an A heating pusher II (12b) arranged in the A shell, an A isolation air lock (13) respectively arranged at the A feed inlet and the A discharge outlet, and an A compressed air guide pipe (14) connected to the front end surface of the A shell; The A shell (11) is a long cylindrical structure, closed at both ends, and arranged at an angle to the horizontal plane; the A shell (11) is provided with an A feed port (111) at the lower end, and an A discharge port (112) at the upper end; the A shell is a double-layer hollow structure, an A external heat medium inlet (113) is provided on the outer surface of the higher end of the A shell near the A discharge port (112), and an A external heat medium outlet (114) is provided on the outer surface of the lower end near the A feed port (111); the heat medium enters the hollow cavity of the A shell from the A external heat medium inlet (113) and is discharged from the A external heat medium outlet (114); The A heating pusher I (12a) comprises a core shaft (12a1), a spiral blade (12a2) and an A rotating joint I (12a3) located at both ends of the core shaft; the A heating pusher I passes through the interior of the shell and is fixed to both ends of the A shell through the core shaft, the A heating pusher I is driven by a motor reducer through a method including but not limited to a chain drive, and the driving wheel is sleeved on the outer circumferential surface of the core shaft between the low-end A rotating joint I and the A shell; The core shaft (12a1) and the spiral blade (12a2) are both hollow structures. The core shaft (12a1) comprises an inflow chamber (12a11), a straight-through chamber (12a12) and an outflow chamber (12a13). The straight-through chamber (12a12) runs through both ends of the core shaft and is isolated from the inflow chamber (12a11) and the outflow chamber (12a13). The A rotary joint I (12a3) comprises an outer tube I (12a31), a dynamic seal I (12a32), a dynamic seal II (12a33) and an outer shell I (12a34). The hollow parts of the spiral blade (12a2) are respectively connected to the inflow chamber (12a11), the outflow chamber (12a12) and the outflow chamber (12a13). The two chambers (12a13) are connected, the inflow chamber (12a11) is connected to the outer tube I (12a31) of the rotary joint I at the high end A of the core shaft, one end of the straight-through chamber (12a12) is inserted into the inner hole of the dynamic seal I (12a32) of the rotary joint I at the high end A of the core shaft, the outflow chamber (12a13) is connected to the outer tube I (12a31) of the rotary joint I at the low end A of the core shaft, and the other end of the straight-through chamber (12a12) is inserted into the inner hole of the dynamic seal I (12a32) of the rotary joint I at the low end A of the core shaft; two independent heat media Fa and Fb enter the inflow chamber and the straight-through chamber respectively through two ports of the rotary joint I at the high end A of the core shaft; The heat medium Fa entering the inflow chamber passes through the hollow part of the spiral blade and reaches the outflow chamber, while the heat medium Fb entering the straight-through chamber passes through the entire core shaft and reaches the other end; The heat medium Fa from the outflow cavity and the heat medium Fb from the straight-through cavity are discharged through the two ports of the rotary joint I at the lower end A of the mandrel respectively; the two heat mediums flowing through the mandrel and the spiral blades transfer heat to the tobacco stems respectively; The A heating pusher II (12b) comprises a core shaft (12b1), a spiral blade (12a2) and an A rotary joint II (12b2) located at both ends of the core shaft, the spiral blade (12a2) being fixed on the outer circumferential surface of the core shaft (12b1) in a spiral shape, and an A rotary joint II (12b2) is connected to the high and low ends of the core shaft (12b1) respectively; the A heating pusher II (12b) passes through the interior of the A shell (11) and is fixed to the two ends of the A shell through the core shaft, the A heating pusher II (12b) is driven by a motor reducer through a method including but not limited to a chain drive, and the driving wheel is sleeved on the outer circumferential surface of the core shaft between the low end A rotary joint II and the A shell; The core shaft (12b1) comprises a high-end hollow structure (12b11), a low-end hollow structure (12b12), and a middle solid part; the A rotary joint II (12b2) comprises an outer tube II (12b21), a dynamic seal (12b22), and an outer shell II (12b23); the high-end hollow structure (12b11) and the low-end hollow structure (12b12) of the core shaft (12b1) are respectively provided with through holes communicating with the hollow part of the spiral blade (12a2), and are also respectively connected with the outer tube II (12b21) of the A rotary joint II (12b2); The heat medium enters the hollow structure (12b11) at the high end of the core shaft (12b1) through the interface of the A rotary joint II (12b2) at the high end of the core shaft (12b1). The heat medium entering the hollow structure (12b11) reaches the hollow structure (12b12) at the low end of the core shaft (12b1) after passing through the hollow part of the spiral blade, and is discharged through the interface of the A rotary joint II connected to the hollow structure (12b12). The heat medium flowing through the spiral blade (12a2) of the A heating pusher II (12b) transfers heat to the tobacco stem through the outer surface of the spiral blade, and the heat medium includes hot water, hot oil or water vapor; The A isolation air lock (13) and the inner cavity of the A shell (11) together form a closed chamber, ensuring that the internal pressure of the closed chamber is isolated from the outside; the A isolation air lock connected to the feed port (111) introduces foreign tobacco stems into the closed chamber, and the tobacco stems that have been heated and pressurized in the closed chamber are discharged from the closed chamber through the A isolation air lock connected to the A discharge port (112); The B heating and pressurizing device (4) comprises a B shell (41), a B heating pusher (42) arranged in the B shell, a B isolation air lock (43) respectively arranged at the B feed port and the B discharge port, and a B compressed air guide pipe (44) connected to the discharge end surface of the B shell (41); The B shell (41) is a long cylindrical structure, closed at both ends, and arranged at a certain downward angle from the B feed port to the B discharge port; a B feed port (411) is arranged above the high end of the B shell (41), and a B discharge port (412) is arranged below the low end; the B shell is a double-layer hollow structure, and a B external heat medium inlet (413) is arranged on the outer surface of the end face of the B shell near the B feed port (411), and a B external heat medium outlet (414) is arranged on the outer surface of the end face of the B shell near the B discharge port (412); the heat medium enters the hollow cavity of the B shell from the B external heat medium inlet (413) and is discharged from the B external heat medium outlet (414); The bottom of the working inner cavity of the B shell (41) is composed of two arc surfaces, and its cross-sectional shape is similar to an ω shape. The shape and size of the inner cavity match those of the B heating pusher (42); The B heating pusher (42) is composed of two blade shafts parallel to each other, each blade shaft comprising a hollow shaft (421), a plurality of blades (422) evenly distributed along the shaft length, B rotating joints (423) at both ends of the hollow shaft (421), an inlet pipe (424) and an outlet pipe (425), and the blades on the two blade shafts are arranged in a staggered and interlocking manner; the blades (422) are wedge-shaped hollow closed structures with a fan-shaped axial direction and a thickness that gradually increases from thin to thick, and the hollow part of each blade is connected to the inner cavity of the hollow shaft (421) by the inlet pipe (424) and the outlet pipe (425); the B heating pusher (42) penetrates the interior of the B shell (41) and is fixed to both ends of the B shell by a core shaft, and the B heating pusher (42) is driven by a motor reducer through a chain drive method, including but not limited to, and the driving wheel is sleeved on the outer cylindrical surface of the hollow shaft between the feed end of the B shell and the B rotating joint; The heat medium enters the inner cavity of the hollow shaft (421) through the interface of the rotating joint (423) at the upper end B of the hollow shaft (421), enters the hollow part of each blade (422) through the inflow pipe (424), flows back to the inner cavity of the hollow shaft through the outflow pipe (425), and is discharged through the interface of the rotating joint (423) at the lower end B of the hollow shaft. The heat medium includes hot water, hot oil or water vapor. The B isolation air lock (43) and the inner cavity of the B shell (41) together form a closed chamber, ensuring that the internal pressure of the closed chamber is isolated from the outside; the B isolation air lock connected to the B feed port (411) introduces external tobacco stems into the closed chamber, and the tobacco stems that have been heated and pressurized in the closed chamber are discharged from the closed chamber through the B isolation air lock connected to the B discharge port (412).

2. A tobacco stem redrying method using the tobacco stem redrying system according to claim 1, characterized in that it comprises the following steps: S1. One-stage heating and pressurization: The heat medium is introduced into the hollow cavity of the shell, the hollow part of the core shaft or hollow shaft, and the hollow part of the spiral blade or paddle, and the tobacco stems are sent into the closed chamber of the heating and pressurization equipment. During the process of the heated pusher pushing the tobacco stems forward continuously, the heat medium is used to heat the tobacco stems in the closed chamber in a non-direct contact manner, so that the temperature of the tobacco stems gradually rises to 70℃~130℃; the water vapor overflowing from the tobacco stems during the heating process is sealed in the closed chamber to form a water vapor partial pressure, and the closed chamber pressure is established and maintained mainly based on the water vapor partial pressure. The closed chamber pressure continuously penetrates, pressurizes and maintains the internal tissue of the tobacco stems. At the same time, compressed air is introduced through the compressed air inlet pipe to supplement and adjust the closed chamber pressure, so that the internal surface pressure of the closed chamber reaches 0kg / cm 2 ~6kg / cm 2 ; S2, two-stage pressure release and stem expansion: at the outlet of the heating and pressurizing equipment, the tobacco stems that have undergone the first stage of heating and pressurization are discharged into an open tobacco stem spreading machine in a zero gauge pressure environment, so that the internal pressure of the tobacco stem tissue is quickly released to zero gauge pressure, and expanded tobacco stems with a temperature of 70°C to 110°C and a wet basis moisture content similar to that of the feed are obtained; S3, three-stage drying and cooling: send the tobacco stems in the tobacco stem spreading machine into the tobacco stem redrying machine, use convection air with a temperature of ≤110℃ to heat and dry the tobacco stems, and use convection air with a temperature of ≤35℃ to cool the tobacco stems, so that the wet basis moisture content of the tobacco stems reaches 10% to 13%, and the wet basis moisture content inside and outside the tobacco stems is consistent, and the tobacco stem temperature is ≤55℃.

3. The tobacco stem redrying method according to claim 2 is characterized in that the discharge temperature of the expanded tobacco stems is 70°C to 110°C and the moisture content on a wet basis is similar to that of the feed tobacco stems.

4. The tobacco stem redrying method according to claim 2, characterized in that the heat medium is hot water, hot oil or water vapor.

5. The tobacco stem redrying method according to claim 2, characterized in that in the above step S1, the surface pressure of the external compressed air is 0 kg / cm 2 ~8kg / cm 2 , the temperature is room temperature ~ 150℃.

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