Natural rubber low-oxygen drying device and drying method

Abstract

The invention discloses a natural rubber low-oxygen drying device and a natural rubber low-oxygen drying method. Comprising a drying cabinet which is a cavity in a cubic shape, and the drying cabinet comprises a feeding port, a discharging port, a nitrogen inlet, a nitrogen outlet and a vacuumizing port; the discharge port and the feed port are provided with cabinet doors; guide rails are arranged at the bottoms of the two sides of the drying cabinet and used for supporting the drying trolley. The drying trolley is of a frame structure with an upper opening, and the bottom surface of the drying trolley is a woven mesh; rollers are arranged at four corners of the bottom of the drying trolley and are matched with the guide rails in the drying cabinet for use; the multiple drying trolleys can be contained in the drying cabinet in an end-to-end connection mode. And the auxiliary heat transfer device is arranged at the upper part in the drying cabinet and can be used for punching the materials passing through the lower part in the drying trolley. A drying trolley is used for bearing the rubber materials and feeding the rubber materials into a drying cabinet for drying; during drying, vacuumizing is performed to keep negative pressure and high-temperature nitrogen alternately used, and an auxiliary heat transfer device is used for promoting hot air to flow through, so that the processing quality of rubber is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of the primary processing and drying of natural rubber, and particularly to a natural rubber low-oxygen drying device and a drying method. Background Art

[0002] When producing coagulated standard rubber during the production process of the primary processing of natural rubber, it is necessary to crush, soak, stir, wash, and remove impurities from the raw rubber blocks. After the impurity removal process, the moisture content in the rubber material is relatively high, and it is necessary to perform dehydration and drying treatment on it. Currently, in the dehydration and drying process of the natural rubber primary processing industry, atmospheric pressure high-temperature hot air is used to circulate and dry the material. The highest temperature of the hot air during the drying process reaches above 125°C. Since oxygen participates in the drying process, the natural rubber is prone to thermal-oxidative degradation during the drying process, thereby greatly reducing the rubber performance. Since natural rubber is a natural polymer material and a poor conductor of heat, it is prone to oxidation in a high-temperature environment, ultimately resulting in inconsistent product performance. To improve the performance of the finished natural rubber product, it is necessary to reduce the drying temperature during the drying process and avoid the participation of oxygen in the drying process at the same time. At the same time, in the current natural rubber primary processing industry, a coal combustion furnace is usually used for hot air heating to obtain heat energy, which has problems such as difficult precise control of the hot air temperature and high environmental protection treatment costs for combustion exhaust gas. Therefore, it is urgent to upgrade and transform the drying link of the natural rubber primary processing. The present invention improves the drying link of the natural rubber primary processing in combination with the rubber resilience characteristics. Summary of the Invention

[0003] To solve the problems of the existing technology, the purpose of the present invention is to provide a natural rubber low-oxygen drying device and a drying method, in which only a very small amount of oxygen participates in the drying process of the material, solving the problem of thermal-oxidative degradation of the natural rubber material during drying, and at the same time, the drying efficiency is increased by punching holes in the dried rubber through an auxiliary heat transfer device; the specific content is as follows:

[0004] A natural rubber low-oxygen drying device includes

[0005] A drying cabinet, which is a cubic-shaped cavity. The drying cabinet includes a feed inlet, a discharge outlet, a nitrogen inlet, a nitrogen outlet, and a vacuum pumping port; the discharge outlet and the feed inlet are provided with cabinet doors; guide rails are provided at the bottom of both sides of the drying cabinet for supporting the drying cart;

[0006] A drying cart, which is an upper-open frame structure with a woven net bottom; rollers are provided at the four corners of the bottom of the drying cart for cooperating with the guide rails in the drying cabinet; several drying carts can be accommodated in the drying cabinet in a head-to-tail connection;

[0007] An auxiliary heat transfer device, which is installed above the inside of the drying cabinet and can punch holes in the material in the drying cart passing below;

[0008] An installation space for an auxiliary heat transfer device is provided with an upward bulge at the top of the middle section of the drying cabinet. The auxiliary heat transfer device includes a lifting push rod, a mounting plate, a plurality of long nails, and a baffle; the lifting push rod is fixedly connected to the top of the outer side of the drying cabinet; the push rod part of the lifting push rod passes through the top surface of the installation space of the auxiliary heat transfer device and enters the interior of the drying cabinet to be fixedly connected to the upper surface of the mounting plate; the long nails are vertically and fixedly connected to the lower surface of the mounting plate; the baffle is horizontally arranged at the lower edge of the installation space of the auxiliary heat transfer device, and through holes corresponding to the positions of the long nails are formed in the baffle, and the through holes have the same diameter as the long nails.

[0009] Further, bottom longitudinal partitions, bottom transverse partitions, side partitions, and top partitions are arranged around the inner wall of the drying cabinet; the side partitions are arranged at the connection between two drying positions on the inner side wall of the drying cabinet to block the air flow on both sides of the drying cart and prevent the air flow from flowing through the gap between the drying cart and the inner side wall of the drying cabinet; the top partition and the bottom longitudinal partition are respectively arranged on the upper surface and the lower surface inside the drying cabinet, and the top partition and the bottom longitudinal partition are alternately arranged at the connection between two drying positions to guide the air in the drying cabinet to flow through the drying cart.

[0010] Further, a heating system and a vacuum pumping system are also included; the heating system is connected to the nitrogen outlet and the nitrogen inlet, used to provide high-temperature nitrogen to the drying cabinet, output the low-temperature nitrogen after heat exchange, and the heating system circulates and uses the low-temperature nitrogen after treatment; the vacuum pumping system is connected to the vacuum pumping port and the other end is connected to the heating system, and can evacuate the cavity of the drying cabinet.

[0011] Further, the heating system includes a temperature and humidity meter a, a stop valve a, a circulation pump a, a stop valve b, a steam-water separator, a nitrogen generator, a stop valve c, a stop valve d, a nitrogen buffer tank, a heat pump, a stop valve e, a secondary heater, a nitrogen thermometer, a circulation pump b, a circulation pipeline, a stop valve f; the nitrogen generator generates normal-temperature nitrogen and first enters the nitrogen buffer tank for buffering through the control of the stop valve c. The nitrogen in the nitrogen buffer tank passes through the heat pump, the stop valve e, the secondary heater, the nitrogen thermometer, the circulation pump b, the circulation pipeline, the stop valve f, and the circulation pipeline in sequence and is then transported into the drying cabinet from the nitrogen inlet for heating and drying; the nitrogen output from the drying cabinet passes through the nitrogen outlet and then passes through the temperature and humidity meter a, the stop valve a, the circulation pump a, the stop valve b, the steam-water separator, and the stop valve d in sequence and then enters the nitrogen buffer tank; the vacuum pumping system connects the vacuum pumping port and the steam-water separator.

[0012] Further, the evacuation system is successively connected with a vacuum isolation valve a, a vacuum gauge, a temperature and humidity meter, a vacuum buffer tank, a vacuum pump, and a vacuum isolation valve b. The vacuum isolation valve b is connected to the steam-water separator; the vacuum pump is also connected with a vacuum isolation valve c.

[0013] A drying method for a natural rubber low-oxygen drying device uses a drying cart 19 to carry rubber materials and feeds the materials into a drying cabinet 1 for drying. During the drying process, several drying carts 19 are fed in sequence, moving from the feed port through the drying stations in the drying cabinet 1 towards the discharge port. After the natural rubber materials are fed, the feed door and the discharge door are closed, and drying is started. When drying is started, the drying cart 19 stops moving, the cabinet door is closed to seal the cavity of the drying cabinet 1, the evacuation system 4 evacuates the gas in the drying cabinet 1, and then the heating system 3 inputs high-temperature nitrogen into the drying cabinet 1 to conduct low-oxygen drying on the materials. When drying stops, the drying cart 19 moves one station towards the discharge port to allow the next drying cart 19 to enter the drying cabinet 1. When the drying cart 19 moves out from the discharge port, the drying of this cart is completed.

[0014] Further, when low-oxygen drying is started, first, a nitrogen generator 315 generates normal-temperature nitrogen. The normal-temperature nitrogen is first controlled by a shut-off valve c316 to enter a nitrogen buffer bin 318 for buffering. At this time, the shut-off valve d317 is in a closed state. When nitrogen needs to be input into the drying cabinet 1, the nitrogen in the nitrogen buffer bin 318 is first heated by a heat pump 319 through a circulation pipeline. The maximum temperature heated by the heat pump 319 is about 75°C. After passing through a shut-off valve e320, it enters a secondary heater 321 to heat the nitrogen to 95°C - 100°C. A nitrogen thermometer 322 detects the temperature of the nitrogen in the circulation pipeline to accurately control the temperature of the high-temperature nitrogen entering the drying cabinet 1. The nitrogen is transported into the drying cabinet 1 through a circulation pump b323 through the circulation pipeline for heating and drying. The low-temperature nitrogen output from the drying cabinet 1 passes through a shut-off valve a311 and is transported by a circulation pump a312 to a steam-water separator 314 for dehumidification. The nitrogen after dehumidification is then transported back to the nitrogen buffer bin 318 through the circulation pipeline for recycling.

[0015] Further, the evacuation system 4 starts to work. The stop valve a311, stop valve f324, and vacuum stop valve b46 are closed, and the vacuum stop valve c47 is opened to extract and evacuate the initial air in the drying cabinet 1. After the absolute pressure in the drying cabinet 1 is pumped down to less than 10,000 Pa, the vacuum stop valve c47 is closed, and the evacuation system 4 stops evacuating. At this time, the stop valve e320 is opened, and high-temperature nitrogen is input into the drying cabinet 1 to break the vacuum, so that the high-temperature nitrogen fills the entire drying cabinet 1, and the rubber material is dried in a nitrogen environment. When the heating system 3 has carried out nitrogen circulation heating and drying for the drying cabinet 1 for 30 to 60 minutes, the stop valve a311, stop valve b313, stop valve f324, and vacuum stop valve c47 are closed. The evacuation system 4 evacuates the drying cabinet 1 until the absolute pressure in the drying cabinet 1 is less than 10,000 Pa and holds the pressure for 20 to 30 minutes. After reaching the negative pressure holding time, the vacuum stop valve a41 and vacuum stop valve b46 are closed, and the stop valve f324 is opened. High-temperature nitrogen is input into the drying cabinet 1 through the circulation pipeline in the heating system 3 to break the vacuum, and the pressure in the drying cabinet 1 rises to atmospheric pressure. The drying cabinet 1 enters nitrogen circulation drying again. When carrying out nitrogen circulation, the vacuum stop valve a41, vacuum stop valve b46, and vacuum stop valve c47 are closed.

[0016] Further, after the rubber material is dried, if the drying cabinet 1 is inputting high-temperature nitrogen in circulation, the heating system 3 stops heating the circulating nitrogen and inputs nitrogen at normal temperature and atmospheric pressure without moisture into the drying cabinet 1 for material cooling; if the drying cabinet 1 is being evacuated to maintain a negative pressure, the evacuation system 4 stops evacuating the drying cabinet 1 and inputs nitrogen at normal temperature and atmospheric pressure into the drying cabinet 1 to break the vacuum and cool it. When the pressure in the drying cabinet 1 rises to atmospheric pressure and the material in the drying cabinet 1 reaches the discharge temperature, the nitrogen input is stopped, the discharge door is opened to output the material from the drying cabinet 1. After the natural rubber material is output, the feed door is opened to input the material and carry out material drying.

[0017] Furthermore, the auxiliary heat transfer device 2 is located inside the drying cabinet 1. During the drying process of the material, due to the passage of drying time, the material in the material box will change from the initial fluffy state. After drying for about 2 hours, the material will become compact and the height direction of the material will settle toward the bottom. The height of the material in the drying car 19 is reduced, making the material dense. The gaps between the fluffy materials gradually disappear, and the material state becomes unfavorable for hot air to pass through for sufficient and uniform heat transfer. There are often clamped points and hot spots inside the rubber block. The auxiliary heat transfer device 2 can allow hot air to fully pass through the material during the drying process to fully transfer heat; when the drying cart 19 moves below the auxiliary heat transfer device 2, the auxiliary heat transfer device 2 is used to punch holes in the rubber material in the drying cart 19 below; the auxiliary heat transfer device 2 does not work when the drying cart 19 moves, and only works when the drying cart 19 is stationary during the drying process. When the drying cart 19 is stationary, the long spikes 23 of the auxiliary heat transfer system completely penetrate the material in the drying cart 19 and the woven mesh 191 on the bottom of the drying cart 19, so that hot air can pass through the material pores formed after the long spikes 23 rise to fully transfer heat.

[0018] At the junction of the parking spaces inside the drying cabinet 1, the top partitions 18 and bottom longitudinal partitions parallel to the discharge door are alternately fixed on the top plate and the bottom plate. The function of the top partitions 18 and the bottom longitudinal partitions is to guide the flow of nitrogen, so that the nitrogen entering the drying cabinet 1 can smoothly form a "∽" shape to flow through the natural rubber material. The bottom longitudinal partition is arranged parallel to the lower side of the drying car 19 and fixed to the bottom plate of the drying cabinet 1. The bottom longitudinal partition is close to the bottom longitudinal beam of the drying car 19, so that the nitrogen in the drying process cannot leak out of the guide rail 14.

[0019] The position where the heating system 3 inputs high-temperature nitrogen into the drying cabinet 1 is on the vertical plate near the discharge door, vertically passing through the guide rail 14 directly to the lower side of the drying cart 19. After the high-temperature nitrogen passes through the material upward from the bottom of the last drying cart 19, it flows in the opposite direction of the feed in a similar "∽" shape. After flowing through the lower side of the drying cart 19 near the feed door, the high-temperature nitrogen is converted into low-temperature nitrogen and output to the heating system 3. The advantage of this arrangement is to ensure that the high-temperature nitrogen flowing through the material on the drying cart 19 during discharge has the lowest humidity and the highest temperature in the drying cabinet 1.

[0020] The present invention has the following beneficial effects compared with the prior art:

[0021] (i) Compared with the prior art, the low-oxygen drying method can dry the natural rubber material at a relatively low temperature and dry it in a low-oxygen environment, thereby avoiding oxidation and decomposition of the rubber by oxygen and high temperature, and maintaining the quality and performance of the rubber.

[0022] (2) The combination of vacuum negative pressure drying and normal pressure low oxygen drying proposed by the present invention, with the alternate use of vacuum pumping to maintain negative pressure and high temperature nitrogen, can reduce the moisture evaporation temperature in the drying cabinet. The vacuum environment is conducive to improving the drying rate and can extract nitrogen and water vapor in the dead corners in the drying cabinet.

[0023] (3) Compared with the drying methods currently used in the industry, using a coal combustion furnace for hot air heating to obtain heat energy has problems such as difficult precise control of hot air temperature and high environmental protection treatment costs for combustion exhaust gas. The present invention uses an electric energy utilization method combining a heat pump and electric heating, which can reduce energy consumption and precisely control the temperature.

[0024] (4) Using an auxiliary heat transfer device to promote the cross-flow of hot air can improve the problems of uneven heat transfer and low heat transfer efficiency caused by the tight state of the fluffy material after sedimentation during the drying process, and avoid the undercooked points and overheated points at the internal positions of the rubber blocks. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the connection relationship of the device described in the present invention;

[0026] Figure 2 It is a front sectional view of the drying cabinet described in the present invention;

[0027] Figure 3 It is a top sectional view of the drying cabinet described in the present invention;

[0028] Figure 4 It is a half-sectional view of the drying cabinet described in the present invention;

[0029] Figure 5 It is a left sectional view of the drying cabinet described in the present invention;

[0030] Figure 6 It is a front sectional view of the auxiliary heat transfer device described in the present invention;

[0031] Figure 7 It is a schematic diagram of the use state of the auxiliary heat transfer device described in the present invention;

[0032] Figure 8 It is a schematic diagram of the use state of the auxiliary heat transfer device described in the present invention;

[0033] Figure 9 It is a three-dimensional structure schematic diagram of the drying cart described in the present invention;

[0034] Figure 10 It is a three-dimensional structure schematic diagram of the bottom surface of the drying cart described in the present invention;

[0035] Figure 11 It is a flow chart of the drying method described in the present invention.

[0036] In the figure:

[0037] 1 - drying cabinet, 11 - nitrogen inlet, 12 - nitrogen outlet, 13 - vacuum port, 14 - guide rail,

[0038] 15 - bottom longitudinal partition, 16 - bottom transverse partition, 17 - side partition, 18 - top partition, 19

[0039] - drying cart, 191 - woven mesh, 192 - rollers;

[0040] 2 - auxiliary heat transfer device, 21 - lifting push rod, 22 - mounting plate, 23 - spike, 24 - baffle; 3 - heating system, 310 - temperature and humidity meter a, 311 - stop valve a, 312 - circulation pump a, 313

[0041] - stop valve b, 314 - steam - water separator, 315 - nitrogen generator, 316 - stop valve c, 317

[0042] - stop valve d, 318 - nitrogen buffer bin, 319 - heat pump, 320 - stop valve e, 321

[0043] - secondary heater, 322 - nitrogen thermometer, 323 - circulation pump b, 324 - stop valve f; 4 - evacuation system, 41 - vacuum stop valve a, 42 - vacuum gauge, 43 - temperature and humidity meter, 44 - vacuum buffer tank, 45 - vacuum pump, 46 - vacuum stop valve b, 47 - vacuum stop valve c. Detailed implementation method

[0044] In order to make the technical means, creative features, and achievements of the present invention easy to understand, the following further elaborates on the technical solutions of the invention by combining one of the embodiments and the detailed implementation method of a natural rubber low - oxygen drying device and drying method given by the present invention.

[0045] As Figures 1-11 shown, the specific embodiments given for the invention are as follows:

[0046] A low - oxygen drying method and device for natural rubber, comprising: a drying cabinet 1, a heating system 3, an evacuation system 4, and a drying cart 19.

[0047] The drying cabinet 1 is a cubic - shaped cavity, inside which a drying cart 19 is arranged. The drying cart 19 is used to carry natural rubber materials, and the feeding and discharging of the materials are realized through the entry and exit of the drying cart 19. The natural rubber materials in the drying cabinet 1 can achieve the drying process of reducing the moisture content of the natural rubber materials from more than 40% to less than or equal to 1%.

[0048] The heating system 3 is connected to the drying cabinet 1, used to supply high-temperature nitrogen to the drying cabinet 1, and output the low-temperature nitrogen after heat exchange. The heating system 3 processes the low-temperature nitrogen and then recycles it. The evacuation system 4 is connected to the drying cabinet 1 through one end of the circulation pipeline, capable of evacuating the cavity of the drying cabinet 1, and the other end is connected to the heating system 3, while an exhaust port is provided. When the evacuation system 4 evacuates the drying cabinet 1, it can evacuate the air with a relatively high oxygen content initially in the drying cabinet 1, and can also evacuate and recover the low-temperature nitrogen in the drying cabinet 1 to the heating system 3.

[0049] After the material enters the drying cabinet 1, the gas evacuated by the evacuation system 4 for the first time is discharged to avoid the presence of oxygen remaining in the drying cabinet 1. After the initial air is discharged, the heating system 3 inputs high-temperature nitrogen into the drying cabinet 1. After the high-temperature nitrogen undergoes cross-flow heat exchange with the material in the drying cabinet 1, the temperature of the nitrogen decreases, the temperature of the material increases and moisture evaporation occurs, and the material in the drying cabinet 1 undergoes low-oxygen drying. The low-temperature nitrogen and the evaporated water vapor after the heat exchange are output to the heating system 3 through the circulation pipeline. After the moisture is removed by the heating system 3, the nitrogen is recovered, and is reheated by the heating system 3 and then recycled. When the nitrogen loss during the circulation process results in insufficient nitrogen volume, the heating system 3 can replenish the nitrogen. When the material in the drying cabinet 1 is being dried, the evacuation system 4 alternately evacuates the drying cabinet 1 at fixed intervals and maintains a negative pressure. Maintaining a negative pressure can accelerate the drying rate of the material in the drying cabinet 1. When the evacuation system 4 evacuates the drying cabinet 1, the heating system 3 stops supplying high-temperature nitrogen to the drying cabinet 1 to ensure that a negative pressure state can be established.

[0050] The drying cabinet 1 is composed of a feed door, a discharge door, vertical plates, a top plate, a bottom plate, side partitions 17, a top partition 18, a bottom longitudinal partition, guide rails 14, a heat insulation layer, and a bottom transverse partition 16. The feed door, discharge door, vertical plates, top plate, and bottom plate form the drying cabinet 1 body with a cubic shape. The top plate is vertically fixed to two vertical plates, the two vertical plates are arranged in parallel, and the two vertical plates are vertically fixed to the bottom plate. The heat insulation layer covers the outer surfaces of the vertical plates and the top plate to reduce heat loss in the drying cabinet 1.

[0051] The guide rails 14 are two parallel and at the same height, respectively close to the vertical plates of the drying cabinet 1. The guide rails 14 support the drying cart 19, and the drying cart 19 can move on the guide rails 14. There are several positions for the drying carts 19 in the drying cabinet 1. When the drying cart 19 moves in the drying cabinet 1, it moves an integer multiple of the distance of one parking space each time.

[0052] The side partitions 17 are arranged at the joints between the parking spaces inside the drying cabinet 1, parallel to the feed door and the discharge door, and are fixed to the vertical plates. Their function is to prevent the high-temperature nitrogen from flowing through the gap between the drying cart 19 and the vertical plate in the drying cabinet 1.

[0053] The drying cart 19 includes a top cross beam, top longitudinal beams, columns, bottom longitudinal beams, bottom cross beams, rollers 192, roller 192 shafts, and a woven mesh 191. Two top cross beams are arranged in parallel and fixedly connected to two parallel top longitudinal beams. Four columns are arranged in parallel and fixedly connected to the top cross beams and top longitudinal beams. Two bottom longitudinal beams are arranged in parallel and fixedly connected to two parallel bottom cross beams. The two top cross beams, two top longitudinal beams, four columns, two bottom longitudinal beams, and two bottom cross beams form the framework of the cubic shape of the drying cart 19. Metal panels are fixedly connected to the four sides of the drying cart 19 framework for covering. The woven mesh 191 is fixedly connected to the bottom surface of the drying cart 19, and the drying cart 19 is a square framework without a cover on the top surface. The roller 192 shafts are fixedly connected to the four corner positions at the bottom of the drying cart 19, and rollers 192 for supporting the movement of the drying cart 19 are installed on the roller 192 shafts. The drying cart 19 is arranged on the parallel guide rails 14 through the rollers 192.

[0054] At the position of the transfer of the parking spaces inside the drying cabinet 1, top partition sheets 18 parallel to the discharge door and bottom longitudinal partition sheets are alternately fixedly connected to the top plate and the bottom plate. The functions of the top partition sheets 18 and the bottom longitudinal partition sheets are to achieve the diversion of nitrogen gas, so that the nitrogen gas introduced into the drying cabinet 1 can smoothly form a "∽" - shaped cross - flow through the natural rubber materials. The bottom longitudinal partition sheets are arranged in parallel under the drying cart 19 and fixedly connected to the bottom plate of the drying cabinet 1. The bottom longitudinal partition sheets are closely attached to the bottom longitudinal beams of the drying cart 19, so that the nitrogen gas during the drying process cannot leak outside the guide rails 14.

[0055] The position where the heating system 3 inputs high - temperature nitrogen gas into the drying cabinet 1 is on the vertical plate near the discharge door, passing vertically through the guide rails 14 and reaching the lower side surface of the drying cart 19. After the high - temperature nitrogen gas passes upward through the materials from the bottom of the last drying cart 19, it flows in a direction similar to a "∽" shape in the opposite direction of the feeding. After flowing through the lower side of the drying cart 19 near the feeding door, the high - temperature nitrogen gas turns into low - temperature nitrogen gas and is output to the heating system 3.

[0056] The heating system 3 consists of a temperature and humidity sensor a310, a stop valve a311, a circulation pump a312, a stop valve b313, a steam-water separator 314, a nitrogen generator 315, a stop valve c316, a stop valve d317, a nitrogen buffer tank 318, a heat pump 319, a stop valve e320, a secondary heater 321, a nitrogen thermometer 322, a circulation pump b323, a circulation pipeline, and a stop valve f324. When starting low-oxygen drying, first, the nitrogen generator 315 generates normal-temperature nitrogen. The normal-temperature nitrogen first enters the nitrogen buffer tank 318 for buffering through the control of the stop valve c316. At this time, the stop valve d317 is in the closed state. When nitrogen needs to be input into the drying cabinet 1, the nitrogen in the nitrogen buffer tank 318 is first heated by the heat pump 319 through the circulation pipeline. The maximum heating temperature of the heat pump 319 is about 75°C. After passing through the stop valve e320, it enters the secondary heater 321, where the nitrogen is heated to 95°C - 100°C. The nitrogen thermometer 322 detects the temperature of the nitrogen in the circulation pipeline to accurately control the temperature of the high-temperature nitrogen entering the drying cabinet 1. Then, it is transported into the drying cabinet 1 through the circulation pump b323 through the circulation pipeline for heating and drying. The low-temperature nitrogen output from the drying cabinet 1 passes through the stop valve a311 and is transported by the circulation pump a312 to the steam-water separator 314 for dehumidification. The dehumidified nitrogen is then transported back to the nitrogen buffer tank 318 through the circulation pipeline for recycling.

[0057] The evacuation system 4 consists of a vacuum stop valve a41, a vacuum gauge 42, a temperature and humidity sensor 43, a vacuum buffer tank 44, a vacuum pump 45, a vacuum stop valve b46, and a vacuum stop valve c47. After the natural rubber material feeding is completed, the feeding door and the discharging door are closed. The stop valve a311, the stop valve f324, and the vacuum stop valve b46 are closed, and the vacuum stop valve c47 is opened. The evacuation system 4 starts to work to evacuate the initial air in the drying cabinet 1. After the absolute pressure in the drying cabinet 1 is pumped down to less than 10,000 Pa, the vacuum stop valve c47 is closed, and the evacuation system 4 stops evacuating. At this time, the stop valve e320 is opened, and high-temperature nitrogen is input into the drying cabinet 1 to break the vacuum, so that the high-temperature nitrogen fills the entire drying cabinet 1, and the natural rubber material is dried in a nitrogen environment.

[0058] When the heating system 3 has been circulating nitrogen for heating and drying the drying cabinet 1 for 30 to 60 minutes, the stop valve a311, stop valve b313, stop valve f324, and vacuum stop valve c47 are closed, and the evacuation system 4 evacuates the drying cabinet 1 until the absolute pressure in the drying cabinet 1 is less than 10,000 Pa and holds the pressure for 20 to 30 minutes. After reaching the negative pressure holding time, the vacuum stop valve a41 and vacuum stop valve b46 are closed, and the stop valve f324 is opened. High-temperature nitrogen is input into the drying cabinet 1 through the circulation pipeline in the heating system 3 to break the vacuum, and the pressure in the drying cabinet 1 rises to atmospheric pressure. The drying cabinet 1 enters the nitrogen circulation drying again. When circulating nitrogen, the vacuum stop valve a41, vacuum stop valve b46, and vacuum stop valve c47 are closed.

[0059] After the drying target of the material is achieved, if the heating system 3 is heating the circulating nitrogen in the drying cabinet 1, the heating system 3 stops heating the circulating nitrogen and inputs nitrogen at normal temperature and atmospheric pressure without moisture into the drying cabinet 1 for cooling the material; if the drying cabinet 1 is being evacuated and maintaining a negative pressure, the evacuation system 4 stops evacuating the drying cabinet 1 and inputs nitrogen at normal temperature and atmospheric pressure into the drying cabinet 1 to break the vacuum and cool it, and the pressure in the drying cabinet 1 rises to atmospheric pressure. When the temperature of the material in the drying cabinet 1 reaches the discharging temperature, the nitrogen input is stopped, the discharging door is opened to output the material from the drying cabinet 1. After the natural rubber material is output, the feeding door is opened to input the material, and the material drying is carried out.

[0060] The auxiliary heat transfer device 2 is located inside the drying cabinet 1. During the drying process of the material, as the drying time progresses, the material in the material box changes from the initial fluffy state. After drying for about 2 hours, the material becomes compact, the height direction of the material settles towards the bottom, the height of the material in the drying cart 19 decreases, making the material denser, and the gaps between the fluffy materials gradually disappear. The material state becomes unfavorable for hot air to pass through for sufficient heat transfer and uniform heat transfer, and there are often undercooked points and overheated points in the internal position of the rubber block. The auxiliary heat transfer device 2 can enable hot air to fully pass through the material during the drying process for sufficient heat transfer.

[0061] The auxiliary heat transfer device 2 includes a lifting push rod 21, a mounting plate 22, a slide rail, a slider, a long nail 23, and a baffle 24. The lifting push rod 21 is fixedly connected to the outside of the drying box body. The push rod part of the lifting push rod 21 passes through the top surface of the drying box body and is sealed. The push rod of the lifting push rod 21 can be lifted and lowered. The mounting plate 22 is horizontally arranged at the end of the push rod of the lifting push rod 21. The slider is fixedly connected to the corner position of the mounting plate 22. The slide rail is vertically connected to the inside of the drying box body perpendicular to the mounting plate 22. The slider drives the mounting plate 22 to slide in the slide rail to ensure that the mounting plate 22 can move horizontally up and down.

[0062] The spike 23 is vertically and fixedly connected to the bottom surface of the mounting plate 22, so that the spike 23 can move up and down along the slide rail driven by the lifting push rod 21 following the mounting plate 22. The baffle 24 is fixedly connected to the bottom of the slide rail and is arranged parallel to the mounting plate 22. The spike 23 can slide in the baffle 24. The function of the baffle 24 is that when the spike 23 rises after descending to the lowest position, it may drive the dense material to rise, and the baffle 24 blocks the material to prevent the material from being carried out of the drying cart 19.

[0063] The auxiliary heat transfer device 2 is located directly above the position of a drying cart 19 in the drying chamber. The auxiliary heat transfer device 2 does not work when the drying cart 19 is moving and only works when the drying cart 19 is stationary during the drying process. When the drying cart 19 is stationary, the spike 23 acts on the material in the drying cart 19 to guide the hot air through the material for sufficient heat transfer. The spike 23 can completely penetrate the dense material during the drying process and the woven mesh 191 on the bottom surface of the drying cart 19. So that the hot air can pass through the pores formed in the material after the spike 23 rises.

[0064] It should be understood that the above specific embodiments are only used for illustrative explanation or interpretation of the principle of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. 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 equivalent forms of such scope and boundaries.

Claims

1. A natural rubber low oxygen drying device, characterized in that: include, The drying cabinet (1) is a cubic cavity, the drying cabinet (1) comprising a feed port, a discharge port, a nitrogen inlet (11), a nitrogen outlet (12) and a vacuum port (13); the discharge port and the feed port are provided with cabinet doors; guide rails (14) are provided at the bottom of both sides of the drying cabinet (1) for supporting the drying vehicle (19); A drying cart (19), the drying cart (19) being an upper open frame structure, the bottom surface of which is a woven mesh (191); rollers (192) are arranged at four corners of the bottom of the drying cart (19) and are used in conjunction with the guide rails (14) in the drying cabinet (1); the drying cabinet (1) can accommodate a plurality of the drying carts (19) connected end to end; An auxiliary heat transfer device (2) is installed at the top of the drying cabinet (1) and is capable of punching holes in the material in the drying vehicle (19) passing below; The top of the middle section of the drying cabinet (1) is protruding upwards and is provided with an auxiliary heat transfer device (2) installation space, and the auxiliary heat transfer device (2) comprises a lifting push rod (21), a mounting plate (22), a plurality of long spikes (23) and a baffle (24); the lifting push rod (21) is fixedly connected to the top of the outer side of the drying cabinet (1); the push rod part of the lifting push rod (21) passes through the top surface of the auxiliary heat transfer device (2) installation space, enters the interior of the drying cabinet (1), and is fixedly connected to the upper surface of the mounting plate (22); the long spike (23) is vertically fixedly connected to the lower surface of the mounting plate (22); the baffle (24) is horizontally arranged at the lower edge of the auxiliary heat transfer device (2) installation space, and a through hole is opened on the baffle (24) at the position corresponding to the long spike (23), and the through hole has the same diameter as the long spike (23).

2. A natural rubber low oxygen drying device as claimed in claim 1, characterized in that: The inner wall of the drying cabinet (1) is provided with a bottom longitudinal partition, a bottom transverse partition (16), a side partition (17) and a top partition (18); the side partition (17) is arranged at the connection between two drying carts (19) on the inner wall of the drying cabinet (1) to block the air flow on both sides of the drying cart (19) and prevent the air flow from flowing through the gap between the drying cart (19) and the inner wall of the drying cabinet (1); the top partition (18) and the bottom longitudinal partition (15) are respectively arranged on the upper surface and the lower surface of the interior of the drying cabinet (1), and the top partition (18) and the bottom longitudinal partition (15) are alternately arranged at the connection between the two drying carts (19) to guide the air in the drying cabinet (1) to flow through the drying cart (19).

3. A natural rubber low oxygen drying device as claimed in claim 2, characterized in that: It also includes a heating system (3) and an evacuation system (4); the heating system (3) is connected to the nitrogen outlet (12) and the nitrogen inlet (11), and is used to provide high-temperature nitrogen to the drying cabinet (1), and output low-temperature nitrogen after heat exchange, and the heating system (3) processes the low-temperature nitrogen for recycling; the evacuation system (4) is connected to the vacuum port (13), and the other end is connected to the heating system (3), so that the cavity of the drying cabinet (1) can be evacuated.

4. A natural rubber low oxygen drying device as claimed in claim 3, characterized in that: The heating system (3) comprises a temperature and humidity meter a (310), a stop valve a (311), a circulation pump a (312), a stop valve b (313), a steam-water separator (314), a nitrogen generator (315), a stop valve c (316), a stop valve d (317), a nitrogen buffer chamber (318), a heat pump (319), a stop valve e (320), a secondary heater (321), a nitrogen temperature meter (322), a circulation pump b (323), and a stop valve f (324); the nitrogen generator (315) generates room temperature nitrogen which is controlled by the stop valve c (316) to first enter the nitrogen buffer chamber (318) for buffering, and the nitrogen in the nitrogen buffer chamber (318) passes through the nitrogen generator (315) in sequence. The nitrogen gas is transported from the nitrogen inlet (11) into the drying cabinet (1) for heating and drying after passing through the heat pump (319), the stop valve e (320), the secondary heater (321), the nitrogen temperature gauge (322), the circulation pump b (323), and the stop valve f (324); the nitrogen gas output from the drying cabinet (1) passes through the nitrogen outlet (12) and then passes through the temperature and humidity meter a (310), the stop valve a (311), the circulation pump a (312), the stop valve b (313), the steam-water separator (314), and the stop valve d (317) in sequence before entering the nitrogen buffer chamber (318); the vacuum system (4) is connected to the vacuum port (13) and the steam-water separator (314).

5. A natural rubber low oxygen drying device as claimed in claim 4, characterized in that: The evacuation system (4) is sequentially connected to a vacuum stop valve a (41), a vacuum gauge (42), a temperature and humidity meter (43), a vacuum buffer tank (44), a vacuum pump (45), and a vacuum stop valve b (46); the vacuum stop valve b (46) is connected to the steam-water separator (314); the vacuum pump (45) is also connected to a vacuum stop valve c (47).

6. A drying method of a natural rubber low oxygen drying device according to claim 5, characterized in that: A drying vehicle (19) is used to carry rubber materials and deliver the materials into a drying cabinet (1) for drying. During the drying process, a plurality of drying vehicles (19) are sequentially moved from a material inlet through a drying station in the drying cabinet (1) toward a material outlet. When drying is started, the drying vehicle (19) stops moving, the cabinet door is closed to seal the cavity of the drying cabinet (1), the vacuum system (4) extracts and empties the gas in the drying cabinet (1), and then the heating system (3) inputs high-temperature nitrogen into the drying cabinet (1) to perform low-oxygen drying on the materials. When drying is stopped, the drying vehicle (19) moves one station toward the material outlet to allow the next drying vehicle (19) to enter the drying cabinet (1). When the drying vehicle (19) moves out of the material outlet, the drying of the vehicle is completed.

7. The drying method of a natural rubber low oxygen drying device as claimed in claim 6, characterized in that: When the low oxygen drying is started, the nitrogen generator (315) first generates nitrogen at room temperature, and the nitrogen at room temperature is first controlled by the stop valve c (316) to enter the nitrogen buffer bin (318) for buffering. At this time, the stop valve d (317) is in a closed state. When nitrogen needs to be input into the drying cabinet (1), the nitrogen in the nitrogen buffer bin (318) is heated for the first time by the heat pump (319) through the circulation pipeline. The maximum temperature heated by the heat pump (319) is about 75°C. After passing through the stop valve e (320), the nitrogen enters the secondary heater (321) to be nitrogen. The nitrogen is heated to 95°C to 100°C, and the nitrogen temperature meter (322) detects the temperature of the nitrogen in the circulation pipeline to accurately control the temperature of the high-temperature nitrogen entering the drying cabinet (1). The nitrogen is transported into the drying cabinet (1) through the circulation pipeline by the circulation pump b (323) for heating and drying. The low-temperature nitrogen output from the drying cabinet (1) passes through the stop valve a (311) and is transported to the steam-water separator (314) by the circulation pump a (312) for dehumidification. The dehumidified nitrogen is then transported to the nitrogen buffer bin (318) through the circulation pipeline for recovery and recycling.

8. The drying method of a natural rubber low oxygen drying device as claimed in claim 7, characterized in that: The evacuation system (4) starts to work, the stop valve a (311), the stop valve f (324), and the vacuum stop valve b (46) are closed, and the vacuum stop valve c (47) is opened to evacuate and exhaust the initial air in the drying cabinet (1). After the absolute pressure in the drying cabinet (1) is less than 10000 Pa, the vacuum stop valve c (47) is closed, and the evacuation system (4) stops evacuating. At this time, the stop valve e (320) is opened, and high-temperature nitrogen is input into the drying cabinet (1) to break the air, so that the high-temperature nitrogen fills the entire drying cabinet (1), and the rubber material is dried in the nitrogen environment; when the heating system (3) performs nitrogen circulation heating and drying for 30 minutes to 60 minutes, the stop valve a (311), the stop valve f (324), and the stop valve b (46) are opened. The valve b (313), the stop valve f (324) and the vacuum stop valve c (47) are closed, and the evacuation system (4) evacuates the drying cabinet (1) until the absolute pressure in the drying cabinet (1) is less than 10000 Pa and the pressure is maintained for 20 to 30 minutes. After the negative pressure maintenance time is reached, the vacuum stop valve a (41) and the vacuum stop valve b (46) are closed, and the stop valve f (324) is opened. High-temperature nitrogen is input into the drying cabinet (1) through the circulation pipeline in the heating system (3) to break the air, and the pressure in the drying cabinet (1) is increased to normal pressure. The drying cabinet (1) enters nitrogen circulation drying again. When the nitrogen circulation is performed, the vacuum stop valve a (41), the vacuum stop valve b (46) and the vacuum stop valve c (47) are closed.

9. A drying method for natural rubber low oxygen drying device as claimed in claim 8, characterized in that: After the rubber material is dried, the drying cabinet (1) is inputting high-temperature nitrogen for circulation, then the heating system (3) stops heating the circulating nitrogen, and inputs moisture-free nitrogen at room temperature and pressure into the drying cabinet (1) to cool the material; if the drying cabinet (1) is being evacuated to maintain negative pressure, then the vacuum system (4) stops evacuating the drying cabinet (1), and inputs nitrogen at room temperature and pressure into the drying cabinet (1) to break the air and cool the material. The pressure in the drying cabinet (1) is increased to normal pressure. When the material in the drying cabinet (1) reaches the discharge temperature, the nitrogen input is stopped, and the discharge door is opened to discharge the material from the material drying cabinet (1). After the natural rubber material is discharged, the feed door is opened to input the material, and the material is dried.

10. The drying method of a natural rubber low oxygen drying device as claimed in claim 9, characterized in that: When the drying vehicle (19) moves to the bottom of the auxiliary heat transfer device (2), the auxiliary heat transfer device (2) is used to punch holes in the rubber material in the drying vehicle (19) below; the auxiliary heat transfer device (2) does not work when the drying vehicle (19) moves, and only works when the drying vehicle (19) is stationary during the drying process. When the drying vehicle (19) is stationary, the long spikes (23) of the auxiliary heat transfer system completely penetrate the material in the drying vehicle (19) and the woven mesh (191) on the bottom surface of the drying vehicle (19), so that hot air can pass through the material pores formed after the long spikes (23) rise to fully transfer heat.

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