Grain drying machine with online dust removal and hot air circulation functions

Abstract

The invention discloses a grain drying machine with on-line dust removal and hot air circulation functions, which comprises a tower type drying machine with a hot air inlet and a waste heat outlet; a hot air outlet of the hot air furnace communicates with the hot air inlet through a hot air pipe; an exhaust opening of the exhaust fan communicates with the waste heat outlet through an exhaust pipe, and an outlet of the exhaust fan is connected with an exhaust pipe; an inlet of the dust removal device is communicated with the exhaust pipe; a first pipe orifice of the three-way reversing pipe is communicated with an outlet of the dust removal device, a second pipe orifice of the three-way reversing pipe is communicated with a hot air hearth of the hot blast stove through a return pipe, and a third pipe orifice of the three-way reversing pipe is connected with an ash discharge pipe; a movable air door mechanism is arranged on the three-way reversing pipe and used for controlling connection and disconnection of the first pipe opening and the second pipe opening and controlling connection and disconnection of the first pipe opening and the third pipe opening. According to the dryer, waste heat can be recycled, the energy-saving effect is good, impurities and dust in the waste heat can be filtered through the dust removal device, and the grain quality is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of drying equipment, and more particularly to a grain dryer with online dust removal and hot air circulation functions. Background Art

[0002] Current grain dryers (such as CN221666521U, a sun-drying grain dryer)—whether mixed flow, crossflow, continuous, or batch vertical—all use a through-heating method. This means that hot air generated by a hot air blower, under negative pressure, enters the dryer's hot chamber from the inlet, passes through the grain layer in the middle chamber, and bakes the grain. During the drying process, moist heat is emitted, carrying weeds and dust with it, and is discharged into the residual air chamber. An exhaust fan located outside the residual air chamber extracts this heat and exhausts it to the ash room. Statistics show that 30% of the incoming air heat is lost. This indicates that the waste heat in existing dryers is not reused, resulting in a 15-25% increase in dryer energy consumption.

[0003] In addition, a new type of static room-type grain drying equipment is currently on the market. It heats the room temperature in the drying room to the required temperature through a heat source. The drying room is connected to the hot air furnace through an air inlet channel and an air outlet channel to realize hot air circulation. During the circulation process, the hot air carries fibrous dust, which poses a safety hazard. Its dust exhaust device is installed on the upper part of the elevator. Although there are centrifugal motors and pipes for dust collection, the dust scattered in the huge drying room cannot be integrated and extracted cleanly, causing the dust to stick to the surface of the grains, changing the original color of the grains, which is extremely unpopular.

[0004] Therefore, how to provide a grain dryer that is more energy-efficient and has high grain quality and has online dust removal and hot air circulation functions is a problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a grain dryer with online dust removal and hot air circulation functions, which is more energy-saving and has high grain quality.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A grain dryer with online dust removal and hot air circulation functions, comprising:

[0008] A tower dryer, wherein one side of the bottom of the tower dryer is provided with a hot air inlet and a waste heat outlet;

[0009] A hot air stove, the hot air stove is placed outside the tower dryer, and the hot air outlet of the hot air stove is connected to the hot air inlet through a hot air pipe;

[0010] An exhaust fan, the exhaust fan is placed outside the tower dryer, the exhaust port of the exhaust fan is connected to the waste heat outlet through an exhaust pipe, and the outlet of the exhaust fan is connected to an exhaust pipe;

[0011] a dust removal device, wherein the inlet of the dust removal device is connected to and communicates with the pipe opening of the exhaust pipe away from the exhaust fan;

[0012] a three-way reversing pipe, wherein a first pipe opening of the three-way reversing pipe is connected to the outlet of the dust removal device and is in communication therewith, a second pipe opening of the three-way reversing pipe is in communication with the hot air furnace of the hot air furnace via a return pipe, and a third pipe opening of the three-way reversing pipe is connected to an ash discharge pipe, the end of which is connected to an ash discharge room;

[0013] Wherein, the three-way reversing pipe is provided with a movable damper mechanism for controlling the opening and closing of the first pipe opening and the second pipe opening, and controlling the opening and closing of the first pipe opening and the third pipe opening.

[0014] It can be seen from the above technical solution that compared with the prior art, the present invention discloses a grain dryer with online dust removal and hot air circulation functions. When drying grains, the movable damper mechanism controls the connection between the first pipe port and the second pipe port, and blocks the first pipe port and the third pipe port. The hot air generated by the hot blast furnace enters the tower dryer through the hot air pipe and the hot air inlet to dry the grains. The moisture, grass, dust and waste heat generated during the drying process are drawn into the exhaust fan through the waste heat outlet and the exhaust pipe, and then enter the exhaust pipe through the outlet of the exhaust fan, and are filtered by the dust removal device. The filtered hot air enters the second pipe port of the three-way reversing pipe and then flows back through the return pipe to the hot air furnace of the hot blast furnace, mixed with the hot air and enters the tower dryer again, thereby realizing the repeated reuse of waste heat and achieving energy-saving effects. In addition, during the reuse of the waste heat and hot air, the grass, dust and waste heat in the waste heat are filtered through the filtering device, so that the reused waste heat is clean hot air, reducing the adhesion of dust on the surface of the grains during the drying process and improving the quality of the grains. When the grains reach the inspection standards, the hot air furnace automatically stops running and stops supplying heat to the tower dryer, but the exhaust fan is still running to extract the remaining wet air heat and dust and grass stagnant in the corners of the tower dryer. At this time, the movable damper mechanism controls the connection between the first pipe port and the third pipe port, and blocks the first pipe port and the second pipe port, that is, opens the ash discharge channel, so that the remaining wet air heat and dust and grass stagnant in the corners are discharged into the ash discharge room through the ash discharge pipe. It takes about an hour to completely extract them. At the same time, all the grains in the tower dryer are cooled to room temperature, so the exhaust fan is turned off and all operations are completed.

[0015] Furthermore, the dust removal device includes:

[0016] a dust removal pipe, one end of which is connected to and communicates with a pipe opening on the exhaust pipe away from the exhaust fan, and the other end of which is connected to and communicates with the first pipe opening of the three-way reversing pipe;

[0017] A filter screen is provided in the dust removal pipe and is used for filtering grass and dust in the waste heat.

[0018] Furthermore, the filter has a first state and a second state. In the first state, grass, debris and dust in the residual heat are filtered, and in the second state, grass, debris and dust in the residual heat are not filtered.

[0019] The beneficial effect of adopting the above technical solution is: when the grain is dried, the filter is in the first state, which can filter the circulating waste heat and remove grass, debris and dust in the waste heat; when the grain drying reaches the inspection standard and needs to continue to discharge the remaining moisture, waste heat and impurities in the tower dryer, the filter is in the second state. At this time, the filter does not play a filtering role, so that the remaining moisture, waste heat and impurities can be quickly discharged through the ash discharge pipe.

[0020] Furthermore, in the first state, the filter is arranged at an angle in the dust removal pipe, wherein the high end of the filter abuts the upper edge of the pipe opening at one end of the dust removal pipe, and the low end of the filter abuts the lower edge of the pipe opening at the other end of the dust removal pipe; in the second state, the filter is arranged horizontally in the dust removal pipe.

[0021] The beneficial effect of adopting the above technical solution is that the filter screen is arranged obliquely, and its filtering area is larger than that of the filter screen arranged vertically, thereby improving the filtering effect.

[0022] Furthermore, the dust removal device also includes a driving mechanism for driving the filter to switch back and forth between the first state and the second state.

[0023] Furthermore, the driving mechanism includes:

[0024] A rotating shaft, the two ends of which are rotatably connected to the two opposite walls of the dust removal pipe, and the rotating shaft is fixedly connected to the crossbeam on the filter screen;

[0025] A driving arm, wherein the driving arm is located on one side of the dust removal pipe, and one end of the driving arm is fixedly connected to one end of the rotating shaft;

[0026] A driving cylinder is provided on an outer tube wall on one side of the dust removal tube, and a telescopic end of the driving cylinder is hinged to the other end of the driving arm.

[0027] The beneficial effect of adopting the above technical solution is that the extension and contraction of the driving cylinder can drive the driving arm to swing, and then the driving arm drives the rotating shaft to rotate, thereby realizing the switching of the filter screen between the tilted and horizontal states.

[0028] Furthermore, the filter is provided with a vibration pump for shaking off grass, debris and dust attached to the filter.

[0029] The beneficial effect of adopting the above technical solution is to prevent the filter from being clogged by impurities and affecting the filtering effect.

[0030] Furthermore, an ash outlet is provided on the bottom wall of the dust removal pipe near the lower end of the filter screen, and a straight ash discharge pipe is fixed to the bottom end of the three-way reversing pipe. One end of the straight ash discharge pipe is connected and communicated with the ash outlet, and the ash outlet at the other end of the straight ash discharge pipe is communicated with the inner cavity of the ash discharge pipe.

[0031] The beneficial effect of adopting the above technical solution is that the grass and debris dust shaken off by the vibration pump enters the ash discharge straight pipe through the ash outlet under the push of the residual wind, and is directly discharged into the ash discharge room after entering the ash discharge pipe, thereby cleaning the shaken off grass and debris dust and avoiding accumulation in the dust removal pipe and blockage.

[0032] Furthermore, the movable damper mechanism includes:

[0033] A door shaft, the door shaft being rotatably arranged at the second pipe opening of the three-way reversing pipe, a movable damper being fixed on the door shaft, and a push-pull plate being fixed on the upper end of the door shaft;

[0034] The damper control cylinder is arranged on the top end of the three-way reversing pipe, and the telescopic end of the damper control cylinder is hinged to the push-pull plate.

[0035] The beneficial effects of adopting the above technical solution are: the damper control cylinder drives the push-pull plate to swing, thereby realizing the movable damper to cover the third pipe opening or the second pipe opening, respectively realizing the connection between the first pipe opening and the second pipe opening, ensuring that the purified waste heat flows into the hot air furnace through the return pipe for reuse, and realizing the connection between the first pipe opening and the third pipe opening, ensuring that the remaining hot air and dust impurities in the tower dryer are directly discharged through the ash discharge pipe.

[0036] Furthermore, limit blocks are fixed on the inner top wall and the inner bottom wall of the three-way reversing tube, and the movable damper can abut against the limit blocks.

[0037] The beneficial effect of adopting the above technical solution is that when the movable damper abuts against the limit block, the movable damper can just cover the third pipe opening, preventing the movable damper from moving excessively under the drive of the damper control cylinder, which may cause the movable damper to get stuck with the inner wall of the three-way reversing pipe, damage to the movable damper, abnormal noise and other problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0039] Figure 1 This is a structural schematic diagram from a first perspective of a grain dryer with online dust removal and hot air circulation functions provided by the present invention.

[0040] Figure 2 This is a structural schematic diagram from a second perspective of a grain dryer with online dust removal and hot air circulation functions provided by the present invention.

[0041] Figure 3 This is a schematic diagram of the top structure of a grain dryer with online dust removal and hot air circulation functions provided by the present invention.

[0042] Figure 4 This is a first-person perspective diagram of the assembly of the exhaust fan, dust removal device, three-way reversing pipe, return pipe, and movable damper mechanism.

[0043] Figure 5 This is a schematic diagram from a second perspective of the assembly of the exhaust fan, dust removal device, three-way reversing pipe, return pipe, and movable damper mechanism.

[0044] Figure 6 for Figure 5 Schematic diagram of the enlarged structure of part A in the middle.

[0045] Figure 7 A schematic diagram showing the assembly of the dust removal device, three-way reversing pipe, return pipe, and movable damper mechanism from a third perspective.

[0046] Figure 8 for Figure 7 Schematic diagram of the enlarged structure of part B in the middle.

[0047] Figure 9 This is a schematic diagram from the first perspective of a tee reversing pipe equipped with an ash discharge straight-through pipe.

[0048] Figure 10 for Figure 9 Schematic diagram of the enlarged structure of local C in the middle.

[0049] Figure 11 This is a schematic diagram from a second perspective showing that a ash discharge straight-through pipe is provided on the three-way reversing pipe.

[0050] Figure 12 for Figure 11 Schematic diagram of the enlarged structure of local D in the middle. DETAILED DESCRIPTION

[0051] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0052] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0053] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0054] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0055] See also Figures 1-12 The embodiment of the present invention discloses a grain dryer with online dust removal and hot air circulation functions, comprising:

[0056] The tower dryer 1 has a hot air inlet 101 and a waste heat outlet 102 on one side of the bottom of the tower dryer 1;

[0057] The hot air furnace 2 is placed outside the tower dryer 1, and the hot air outlet 201 of the hot air furnace 2 is connected to the hot air inlet 101 through the hot air pipe 3;

[0058] The exhaust fan 4 is placed outside the tower dryer 1. The exhaust port 401 of the exhaust fan 4 is connected to the waste heat outlet 102 through the exhaust pipe 5. The outlet of the exhaust fan 4 is connected to the exhaust pipe 6.

[0059] A dust removal device 7, the inlet of the dust removal device 7 is connected to and communicates with the pipe opening of the exhaust pipe 6 away from the exhaust fan 4;

[0060] A three-way reversing pipe 8, a first pipe opening 81 of the three-way reversing pipe 8 is connected to and communicates with the outlet of the dust removal device 7, a second pipe opening 82 of the three-way reversing pipe 8 is communicated with the hot air furnace of the hot air furnace 2 through a return pipe 9, and a third pipe opening 83 of the three-way reversing pipe 8 is connected to an ash discharge pipe 10, the end of which is connected to an ash discharge room;

[0061] The three-way reversing pipe 8 is provided with a movable damper mechanism 11 for controlling the opening and closing of the first pipe opening 81 and the second pipe opening 82 , and controlling the opening and closing of the first pipe opening 81 and the third pipe opening 83 .

[0062] See Figure 8 As shown, the dust removal device 7 includes:

[0063] A dust removal pipe 71, one end of which is connected to and communicates with the pipe opening of the exhaust pipe 6 away from the exhaust fan 4, and the other end of which is connected to and communicates with the first pipe opening 81 of the three-way reversing pipe 8;

[0064] The filter screen 72 is arranged in the dust removal pipe 71 and is used to filter grass and dust in the residual heat.

[0065] The filter 72 has a first state and a second state. In the first state, grass, debris and dust in the residual heat are filtered, and in the second state, grass, debris and dust in the residual heat are not filtered.

[0066] In the first state, the filter 72 is arranged at an angle in the dust removal pipe 71, wherein the high end of the filter 72 abuts against the upper edge of the pipe opening at one end of the dust removal pipe 71, and the low end of the filter 72 abuts against the lower edge of the pipe opening at the other end of the dust removal pipe 71; in the second state, the filter 72 is arranged horizontally in the dust removal pipe 71.

[0067] The dust removal device 7 further includes a driving mechanism 73 for driving the filter screen 72 to switch back and forth between the first state and the second state.

[0068] The driving mechanism 73 includes:

[0069] The rotating shaft 731 has two ends rotatably connected to the two opposite tube walls of the dust removal tube 71, and the rotating shaft 731 is fixedly connected to the crossbeam 721 on the filter screen 72;

[0070] A driving arm 732 is located on one side of the dust removal pipe 71, and one end of the driving arm 732 is fixedly connected to one end of the rotating shaft 731;

[0071] The driving cylinder 733 is arranged on the outer tube wall of one side of the dust removal tube 71 , and the telescopic end of the driving cylinder 733 is hinged to the other end of the driving arm 732 .

[0072] In some embodiments of the present invention, a vibration pump 12 is provided on the filter screen 72 for shaking off grass, debris and dust attached to the filter screen 72 .

[0073] In other embodiments, an ash outlet 711 is provided on the bottom wall of the dust removal pipe 71 at the lower end near the filter screen 72, and a straight ash discharge pipe 13 is fixed to the bottom end of the three-way reversing pipe 8. One end of the straight ash discharge pipe 13 is connected to and communicated with the ash outlet 711, and the ash discharge port 131 at the other end of the straight ash discharge pipe 13 is communicated with the inner cavity of the ash discharge pipe 10.

[0074] In some embodiments, the movable damper mechanism 11 includes:

[0075] The door shaft 111 is rotatably arranged at the second pipe opening of the three-way reversing pipe 8. A movable damper 112 is fixed on the door shaft 111, and a push-pull plate 113 is fixed on the upper end of the door shaft 111.

[0076] The damper control cylinder 114 is arranged on the top end of the three-way reversing tube 8 , and the telescopic end of the damper control cylinder 114 is hinged to the push-pull plate 113 .

[0077] In this embodiment, limit blocks 84 are fixed on both the inner top wall and the inner bottom wall of the three-way reversing tube 8 , and the movable damper 112 can abut against the limit blocks 84 .

[0078] The tower dryer 1 of the present invention is prior art. For its specific structure, please refer to publication number CN221666521U, which is titled "A Sun-Drying Grain Dryer." It comprises a hot air chamber, a drying chamber, and a waste heat chamber. Multiple layers of drying pipes are arranged vertically within the drying chamber. The hot air chamber communicates with the hot air outlet 201 of the hot air furnace 2 via a hot air inlet 101 via a hot air pipe 3. The waste heat outlet 102 of the waste heat chamber communicates with the exhaust port 401 of the exhaust fan 4 via an exhaust pipe 5. In tower dryer 1, grain is spread out in thin layers through the multiple layers of drying pipes arranged vertically, using a sun-drying method. This doubles the drying area, changing the existing drying process of densely packed grains, high-temperature baking, and slow-cooling layers to achieve a low-temperature drying effect, ensuring that the grain's nutritional content is not destroyed.

[0079] The working process of the present invention is as follows: Under normal operation, the driving cylinder 733 drives the filter screen 72 to the first state of the inclined arrangement through the driving arm 732, and the damper control cylinder 114 drives the movable damper 112 to abut against the limit block 84 through the push-pull plate 113. Figure 6 At the middle dotted line position, at this time, the movable damper 112 blocks the passage from the first pipe opening 81 of the three-way reversing pipe 8 to the third pipe opening 83, preventing the waste hot air flowing in after being filtered by the filter screen 72 from being discharged through the ash discharge pipe 10, and opens the passage from the first pipe opening 81 of the three-way reversing pipe 8 to the second pipe opening 82, so that the hot air extracted from the tower dryer 1 by the exhaust fan 4 passes through the filter screen 72 in the first state and then flows back to the furnace of the hot air furnace 2 through the return pipe 9 to be reused, thereby achieving energy-saving effect, and the grass dust attached to the filter screen 72 can be shaken off to the bottom of the dust removal pipe 71 in time through the vibration pump 12, and discharged directly to the ash discharge pipe 10 through the ash outlet 711 and the ash discharge straight pipe 13. When the grain moisture meter (not shown) installed on the tower dryer 1 shows that the moisture content reaches the test standard, the hot air furnace 2 automatically stops running and stops supplying hot air to the tower dryer 1. However, the exhaust fan 4 is still running to extract the remaining wet air heat and dust and grass trapped in the corners of the tower dryer 1. At this time, the driving cylinder 733 drives the filter screen 72 to the second state of horizontal arrangement through the driving arm 732. The damper control cylinder 114 drives the movable damper 112 through the push-pull plate 113 to close the second pipe opening 82, open the channel from the first pipe opening 81 to the third pipe opening 83, and open the dust discharge channel. Figure 6 As shown in the figure, the remaining waste heat and dust and weeds can be directly discharged into the ash discharge room through the ash discharge pipe 10, and are completely exhausted in about an hour. At the same time, the grains in the tower dryer 1 are also cooled to room temperature, so the exhaust fan 4 is turned off, and all operations are completed, achieving a low-temperature (50 degrees) and fast (14 hours) drying effect, saving 40% of fuel, and the dust and other impurities generated during the drying process are filtered online through the filter net to remove the dust and weeds, thereby ensuring the quality of the grains.

[0080] Because the hot air returning to the hot air furnace is dust-free, it eliminates dust and other impurities, posing no safety risks. This dryer not only removes dust and impurities online, but also recycles the remaining hot air. Furthermore, the dryer thinly spreads the grain through a multi-layered drying tube, mimicking a sun-drying method. This allows for rapid, low-temperature drying (48°C) of incoming grain, ensuring energy conservation and environmental protection. It is the optimal choice for grain drying worldwide and contributes to the World Food and Agriculture Organization's Zero Hunger initiative.

[0081] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0082] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A grain dryer with online dust removal and hot air circulation functions, characterized in that: include: A tower dryer (1), wherein one side of the bottom of the tower dryer (1) is provided with a hot air inlet (101) and a waste heat outlet (102); A hot air furnace (2), the hot air furnace (2) being placed outside the tower dryer (1), the hot air outlet (201) of the hot air furnace (2) being connected to the hot air inlet (101) via a hot air pipe (3); An exhaust fan (4), the exhaust fan (4) is placed outside the tower dryer (1), the exhaust port (401) of the exhaust fan (4) is connected to the waste heat outlet (102) via an exhaust pipe (5), and the outlet of the exhaust fan (4) is connected to an exhaust pipe (6); A dust removal device (7), wherein the inlet of the dust removal device (7) is connected to and communicates with a pipe opening of the exhaust pipe (6) away from the exhaust fan (4); a three-way reversing pipe (8), wherein a first pipe opening (81) of the three-way reversing pipe (8) is connected to and communicates with an outlet of the dust removal device (7), a second pipe opening (82) of the three-way reversing pipe (8) is communicated with the hot air furnace of the hot air furnace (2) via a return pipe (9), and a third pipe opening (83) of the three-way reversing pipe (8) is connected to an ash discharge pipe (10), and a terminal end of the ash discharge pipe (10) is connected to an ash discharge room; The three-way reversing pipe (8) is provided with a movable damper mechanism (11) for controlling the opening and closing of the first pipe opening (81) and the second pipe opening (82), and controlling the opening and closing of the first pipe opening (81) and the third pipe opening (83).

2. The grain dryer with online dust removal and hot air circulation functions according to claim 1, characterized in that: The dust removal device (7) comprises: a dust removal pipe (71), one end of the dust removal pipe (71) being connected to and in communication with a pipe opening on the exhaust pipe (6) away from the exhaust fan (4), and the other end of the dust removal pipe (71) being connected to and in communication with a first pipe opening (81) of the three-way reversing pipe (8); A filter screen (72) is provided in the dust removal pipe (71) and is used for filtering grass and dust in the waste heat.

3. The grain dryer with online dust removal and hot air circulation functions according to claim 2, characterized in that: The filter (72) has a first state and a second state. In the first state, grass, debris and dust in the residual heat are filtered, and in the second state, grass, debris and dust in the residual heat are not filtered.

4. The grain dryer with online dust removal and hot air circulation functions according to claim 3, characterized in that: In the first state, the filter screen (72) is arranged obliquely in the dust removal pipe (71), wherein the high end of the filter screen (72) abuts against the upper edge of the pipe opening at one end of the dust removal pipe (71), and the low end of the filter screen (72) abuts against the lower edge of the pipe opening at the other end of the dust removal pipe (71); in the second state, the filter screen (72) is arranged horizontally in the dust removal pipe (71).

5. The grain dryer with online dust removal and hot air circulation functions according to claim 4, characterized in that: The dust removal device (7) further comprises a driving mechanism (73) for driving the filter screen (72) to switch back and forth between a first state and a second state.

6. The grain dryer with online dust removal and hot air circulation functions according to claim 5, characterized in that: The driving mechanism (73) comprises: A rotating shaft (731), both ends of which are rotatably connected to two opposite tube walls of the dust removal tube (71), and the rotating shaft (731) is fixedly connected to the crossbeam (721) on the filter screen (72); a driving arm (732), the driving arm (732) being located on one side of the dust removal pipe (71), and one end of the driving arm (732) being fixedly connected to one end of the rotating shaft (731); A driving cylinder (733) is provided on an outer tube wall of one side of the dust removal tube (71), and a telescopic end of the driving cylinder (733) is hinged to the other end of the driving arm (732).

7. A grain dryer with online dust removal and hot air circulation functions according to any one of claims 4 to 6, characterized in that: The filter screen (72) is provided with a vibration pump (12) for shaking off grass, dirt and dust attached to the filter screen (72).

8. The grain dryer with online dust removal and hot air circulation functions according to claim 7, characterized in that: An ash outlet (711) is provided on the bottom wall of the dust removal pipe (71) near the lower end of the filter screen (72), and an ash discharge straight pipe (13) is fixed to the bottom end of the three-way reversing pipe (8), one end of the ash discharge straight pipe (13) is connected to and communicates with the ash outlet (711), and the ash discharge outlet (131) at the other end of the ash discharge straight pipe (13) is communicated with the inner cavity of the ash discharge pipe (10).

9. A grain dryer with online dust removal and hot air circulation functions according to any one of claims 1-6 and 8, characterized in that: The movable damper mechanism (11) comprises: A door shaft (111), the door shaft (111) is rotatably arranged at the second pipe opening position of the three-way reversing pipe (8), a movable damper (112) is fixed on the door shaft (111), and a push-pull plate (113) is fixed on the upper end of the door shaft (111); A damper control cylinder (114) is provided on the top end of the three-way reversing pipe (8), and a telescopic end of the damper control cylinder (114) is hinged to the push-pull plate (113).

10. The grain dryer with online dust removal and hot air circulation functions according to claim 9, characterized in that: Limit blocks (84) are fixed on the inner top wall and the inner bottom wall of the three-way reversing tube (8), and the movable damper (112) can abut against the limit blocks (84).

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