Cellulose drying equipment capable of recycling waste heat

Abstract

The invention relates to the technical field of airflow dryers, and provides cellulose drying equipment capable of recovering waste heat, which comprises a feeder, an air heater, a drying pipeline, a separator, a filter and a fan which are arranged in sequence, and is characterized by further comprising a waste heat recovery mechanism, the waste heat recovery mechanism comprises a heat exchange shell arranged between the drying pipeline and the fan and a preheating shell arranged at the air inlet end of the air heater, a water outlet pipe and a water return pipe are connected between the heat exchange shell and the preheating shell, a circulating pump is arranged on the water outlet pipe and / or the water return pipe, and the water outlet pipe is used for inputting water in the heat exchange shell into the preheating shell; the preheating shell is used for preheating gas entering the air heater. By means of the technical scheme, the technical problems that in the prior art, an air flow drying machine lacks a waste heat recovery structure, and energy is wasted are solved, and heat recycling of waste hot gas is achieved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of pneumatic dryers, and in particular to a cellulose drying device capable of recovering waste heat. Background Art

[0002] Cellulose is a polysaccharide whose main component is plant cell wall. It is a white, odorless powder that is insoluble in water and organic solvents, but soluble in cuprammonia and NMMO. It absorbs water and begins to decompose above 200°C. It is widely used in papermaking, textiles, food, medicine, and high-performance materials.

[0003] Prior to molding, cellulose fibers required drying, often using a pneumatic dryer. The operating principle of a pneumatic dryer is that wet material is evenly fed into the bottom of a drying tube via a feeder. A high-temperature hot air stream is generated by a burner or other heat source, flowing upward at high speed from the bottom of the drying tube. This high-speed hot air stream rapidly disperses and suspends the wet material in the air stream, forming a uniform solid-gas mixture. Due to the large contact area between the gas and solid phases and the significant temperature difference between the hot air stream and the wet material, heat is rapidly transferred from the hot air stream to the wet material, rapidly evaporating the moisture in the wet material. Driven by the hot air stream, the material is dried while being transported upward by the air stream. During this process, moisture in the material is continuously evaporated, and by the time it reaches the top of the drying tube, it has reached the required dryness, becoming a dry product. The dried product, along with the air stream, enters a cyclone separator or other gas-solid separation device for separation. The separated product is collected, while the exhaust gas is discharged via a fan.

[0004] However, the existing air flow dryer lacks a waste heat recovery structure. The hot air after drying is directly discharged through the fan, which wastes heat and is not energy-saving and environmentally friendly. Therefore, it is necessary to recover the waste heat in the existing air flow dryer to fully utilize and save energy. Summary of the Invention

[0005] In order to overcome the above-mentioned defects, the present invention provides a cellulose drying device capable of recovering waste heat, which solves the technical problem in the related art that the air flow dryer lacks a waste heat recovery structure and wastes energy.

[0006] According to one aspect, at least one embodiment of the present invention provides a cellulose drying device with waste heat recovery, comprising an air heater, a drying pipeline, a feeder, a separator, a filter and a fan arranged in sequence, and also comprising a waste heat recovery mechanism, wherein the waste heat recovery mechanism comprises a heat exchange shell arranged between the drying pipeline and the fan and a preheating shell arranged at the air inlet end of the air heater, a water outlet pipe and a return water pipe are connected between the heat exchange shell and the preheating shell, a circulating pump is provided on the water outlet pipe and / or the return water pipe, the water outlet pipe is used to input water in the heat exchange shell into the preheating shell, and a horizontally through-air chamber is provided in the preheating shell for preheating the gas entering the air heater.

[0007] For example, at least one embodiment of the present disclosure provides a cellulose drying device that can recover waste heat. The waste heat recovery mechanism also includes a rotating shaft rotatably arranged at the bottom of the preheating shell, and the rotating shaft is arranged perpendicular to the through-direction of the air cavity. A first filter screen and a second filter screen arranged at a right angle are provided on the rotating shaft. The rotating shaft is configured to be able to rotate, driving the first filter screen to swing vertically to vertical, and at the same time driving the second filter screen to swing vertically to horizontal, or driving the first filter screen to swing vertically to horizontal, and at the same time driving the second filter screen to swing vertically to vertical.

[0008] For example, at least one embodiment of the present disclosure provides a cellulose drying device that can recover waste heat, wherein the inner bottom wall of the preheating shell has an overflow trough connected to the air chamber, and a splash guard is movably provided in the overflow trough. When the first filter screen is swung vertically to the horizontal, it can enter the overflow trough to clean the first filter screen with the help of the water after heat exchange.

[0009] For example, at least one embodiment of the present disclosure provides a cellulose drying device that can recover waste heat, and the waste heat recovery mechanism also includes a cleaning member movably arranged on one side of the splash plate, and the cleaning member can slide along the through direction of the air cavity, and the cleaning member is configured to clean the top surface of the first filter located in the overflow trough after moving.

[0010] For example, at least one embodiment of the present disclosure provides a cellulose drying device with waste heat recovery, wherein the inner wall of the preheating shell is provided with an avoidance groove, the opening of the avoidance groove is provided with a sealing plate, the shaft end of the rotating shaft passes through the sealing plate and extends into the avoidance groove, the rotating shaft and the sealing plate are rotatably matched, and a rotation limit assembly is provided on the end of the rotating shaft, and the rotation limit assembly is used to limit the rotation angle of the rotating shaft.

[0011] For example, at least one embodiment of the present disclosure provides a cellulose drying device that can recover waste heat, wherein the rotation limiting assembly includes a first connecting rod arranged at the end of the rotating shaft and forming an angle with the first filter, and a limiting member arranged to be lifted and lowered on the sealing plate, the limiting member and the first connecting rod are connected by a second connecting rod, and after the limiting member descends, the second connecting rod is used to apply pressure to the first connecting rod to limit it.

[0012] For example, at least one embodiment of the present disclosure provides a cellulose drying device with waste heat recovery, wherein two limit blocks extending vertically are provided on the sealing plate, and the limit blocks are symmetrically located on both sides of the limit member and are used to limit the limit member. A first elastic member is also connected between the limit member and the sealing plate, and the first elastic member is used to provide force for the limit member to push the second connecting rod downward.

[0013] For example, at least one embodiment of the present disclosure provides a cellulose drying device that can recover waste heat, and the inner wall of the preheating shell is also provided with a slide groove, and the slide groove is located on the opposite side of the avoidance groove. A push rod is provided for sliding in the slide groove, and the sliding direction of the push rod is parallel to the through direction of the air cavity. The push rod has a push-up part extending out of the slide groove, and the first filter screen has a corresponding avoidance opening. The push rod is configured to push the vertical second filter screen to be horizontal after sliding.

[0014] For example, at least one embodiment of the present disclosure provides a cellulose drying device with waste heat recovery, wherein the side of the cleaning member is provided with a connecting block extending into the slide groove, the connecting block is located below the ejection rod, and a gear is provided for rotation between the ejection rod and the connecting block, the ejection rod and the connecting block both have teeth that mesh with the gear, and a second elastic member is connected between the ejection rod and the inner wall of the slide groove, the second elastic member is used to provide a force for the ejection rod to reset after being moved by the cleaning member.

[0015] For example, at least one embodiment of the present disclosure provides a cellulose drying device with waste heat recovery, wherein the top wall of the preheating shell also has a horizontally extending limit bar, and the extension direction of the limit bar is arranged perpendicular to the through direction of the air cavity, and is used to limit the first filter screen and the second filter screen.

[0016] The beneficial effects of the embodiments of the present invention are: In the present invention, the waste heat recovery mechanism can effectively recover the waste heat in the drying exhaust gas and use it to preheat the air entering the air heater, reducing the energy required by the air heater to heat the air, improving the energy utilization rate of the entire drying equipment, and reducing energy waste; by saving energy consumption, such as natural gas, electricity, etc., the cost of cellulose drying production is directly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly describes the drawings required for describing the embodiments of the present invention. Obviously, the drawings described below are merely exemplary embodiments of the present invention. Those skilled in the art can, without inventive effort, derive other drawings based on the contents of the exemplary embodiments of the present invention and these drawings.

[0018] Figure 1 A schematic structural diagram of a drying device in one embodiment of the present invention; Figure 2 for Figure 1 A schematic structural diagram of a preheating shell in an embodiment of the present invention; Figure 3 for Figure 2 A schematic structural diagram of the preheating shell from another angle in the embodiment; Figure 4 for Figure 3 Schematic diagram of the structure of the enlarged part A in the middle; Figure 5 for Figure 3 A schematic diagram of the structure of the enlarged part B in the middle; Figure 6 for Figure 3 A schematic diagram of the structure of the preheating shell after removing the splash plate in the embodiment; Figure 7 This is a schematic diagram of the structure inside the preheating shell in another embodiment of the present invention; Figure 8 for Figure 7 Schematic diagram of the structure with the enlarged local C in the middle; Figure 9 for Figure 8 A schematic diagram of the structure in which the first filter screen is removed in the embodiment; In the figure: 1. feeder, 2. air heater, 3. drying pipeline, 4. separator, 5. filter, 6. fan, 7. waste heat recovery mechanism, 71. heat exchange shell, 72. preheating shell, 721. overflow trough, 722. splash plate, 723. cleaning part, 724. avoidance groove, 725. sealing plate, 726. slide, 727. ejector rod, 7271. ejector top, 7272. second elastic part, 728. connecting block, 729. gear, 7291. tooth part, 73. outlet pipe, 74. return pipe, 75. rotating shaft, 76. first filter screen, 761. avoidance port, 77. second filter screen, 78. rotation limit assembly, 781. first connecting rod, 782. limit part, 783. second connecting rod, 784. limit block, 785. first elastic part, 79. limit strip. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention.

[0020] To simplify the drawings, only portions relevant to the invention are schematically depicted in each figure; they do not represent the actual structure of the product. Furthermore, to simplify the drawings and facilitate understanding, in some figures, only one component with the same structure or function is schematically depicted or labeled. In this document, "one" not only means "only one" but also "more than one," and "several" includes "two" and "more than two."

[0021] It should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0022] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0023] In the description of this embodiment, the terms "up", "down", "left", "right", etc., and the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0024] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0025] like Figure 1As shown, it shows a cellulose drying equipment with waste heat recovery in one embodiment of the present invention. In some examples, wet cellulose material is evenly added to the bottom of the drying pipeline 3 by the feeder 1. At the same time, the air heater 2 starts to work, heating the external air into a high-temperature hot air flow. The hot air flow flows upward from the bottom of the drying pipeline 3 at a high speed, contacts the wet material and quickly disperses and suspends it to form a solid-gas mixture, thereby drying the cellulose.

[0026] After the hot airflow completes its drying process, the waste gas, still containing residual heat, continues to flow toward the separator 4, filter 5, and fan 6. At this point, the waste heat recovery mechanism 7 comes into play. A heat exchange shell 71 is positioned between the drying pipeline 3 and the fan 6. As the waste gas passes through the heat exchange shell 71, the water within the shell exchanges heat with the waste gas. The circulating pump activates, transferring the heated water within the heat exchange shell 71 to the preheating shell 72 via the outlet pipe 73. The water flows within the preheating shell 72, exchanging heat with the cold air about to enter the air heater 2. Because the water is hotter than the cold air, heat is transferred to the cold air, preheating it. The preheated air then enters the air heater 2, which now consumes less energy to heat the air to the required high temperature, thus saving energy. After the heat exchange, the water cools down and flows back into the heat exchange shell 71 through the return pipe 74, where it again exchanges heat with the waste gas, completing the cycle.

[0027] The benefit of such a setting is that it improves energy utilization: the waste heat recovery mechanism 7 can effectively recover the waste heat in the drying exhaust gas and use it to preheat the air entering the air heater 2, reducing the energy required by the air heater 2 to heat the air, improving the energy utilization of the entire drying equipment, and reducing energy waste; reducing production costs: by saving energy consumption, such as natural gas, electricity, etc., the cost of cellulose drying production is directly reduced.

[0028] like Figure 2 As shown, it shows a cellulose drying equipment with waste heat recovery in one embodiment of the present invention. In some examples, considering that the external gas may be mixed with dust and affect the purity of the cellulose, a filter is also provided to filter the gas. When in use, the impurities are mainly intercepted by the vertical first filter 76. After a period of operation, a large amount of impurities accumulate on the vertical first filter 76, affecting the circulation of air. At this time, the air pressure received by the first filter 76 will increase, and it will eventually be blown and rotated to the horizontal, while the second filter 77 becomes vertical. In this way, the originally horizontal second filter 77 temporarily replaces the first filter 76 for filtering, and the first filter 76 can be cleaned, for example, by simply vibrating or blowing to clean off the impurities attached to it. After cleaning, the rotating shaft 75 is adjusted to reset the first filter 76. In this way, while ensuring the filtering effect, there is no need to stop the machine and the normal operation of the drying equipment is not affected.

[0029] The advantage of such a setting is that the switching between the first filter 76 and the second filter 77 can clean one of the filters without losing the filtering effect, so there is no need to stop the machine and it does not affect the continuous operation of the equipment. In addition, it avoids the mixing of impurities into the cellulose and improves the product quality.

[0030] like Figures 3 to 5 As shown, a cellulose drying device with waste heat recovery in one embodiment of the present invention is shown. In some examples, when impurities attached to the first filter 76 block air flow, it rotates horizontally and enters the overflow trough 721. The splash plate 722 can be elastically moved using a spring to support the first filter 76, preventing the first filter 76 from directly hitting the water surface and splashing water everywhere. When the first filter 76 presses down the splash plate 722 and enters the overflow trough 721, water will pass through the splash plate 722 and submerge the first filter 76. Impurities attached to it will also enter the water. The water in the overflow trough 721 soaks the filter, helping to soften and dissolve some sticky impurities. In addition, some external electric brushes can be used to clean the surface of the first filter 76 to effectively remove impurities. After the first filter 76 is cleaned, it and the adjustment shaft 75 return to the vertical state again to continue filtering, while the second filter 77 can be cleaned.

[0031] The advantage of such a setting is that it can effectively clean impurities in the filter: the setting of the overflow tank 721 provides a convenient and effective cleaning method for the first filter 76. By soaking in water and using an external electric brush, etc., it can effectively remove impurities on the filter, ensuring that the filter always maintains good filtering performance, extending the service life of the filter, and thus ensuring the efficient operation of the drying equipment.

[0032] like Figures 3 to 6 As shown, it shows a cellulose drying device with waste heat recovery in one embodiment of the present invention. In some examples, after the first filter 76 enters the overflow tank 721, the cleaning member 723 starts to work. For example, the cleaning member 723 can be a scraper with bristles, which is driven by a motor to move along the bottom of the inner wall of the preheating shell 72 parallel to the air inlet direction of the air heater 2. When the cleaning member 723 moves to the top of the overflow tank 721, the bristles come into contact with the first filter 76. The motor drives the cleaning member 723 to move slowly, and the bristles carefully scrub the surface of the filter. When the cleaning member 723 completes cleaning the first filter 76, it returns to the initial position along the original path and waits for the next cleaning task.

[0033] The advantage of such an arrangement is that the cleaning efficiency is improved: the cleaning member 723 is driven by a motor to automatically move to perform the cleaning work, which reduces the time and workload of removing the filter and then cleaning it, thereby improving the cleaning efficiency.

[0034] like Figure 7 、 Figure 9 As shown, it shows a cellulose drying device with waste heat recovery in one embodiment of the present invention. In some examples, considering the continuous filtering effect of the filter, the first filter 76 cannot be blown into a horizontal state with a little impurity, and the rotation angle of the first filter 76 needs to be limited, that is, the first filter 76 will not be completely rotated to a horizontal state until it is rotated to a certain angle. Before it is rotated to this angle, it will maintain its angle or reset to a vertical state.

[0035] The avoidance groove 724 provides space for the rotation limit assembly 78, and the sealing plate 725 can prevent gas from passing through the avoidance groove 724 without passing through the filter screen. The first connecting rod 781 is fixedly connected to the rotating shaft 75, and the first connecting rod 781 and the limit member 782 are movably connected by the second connecting rod 783. When the external gas blows the first filter screen 76 to rotate, the first connecting rod 781 rotates synchronously, and the second connecting rod 783 pushes the limit member 782 to move upward. The first elastic member 785 can be a spring to apply a reaction force to the limit member 782. Therefore, as long as the first connecting rod 781 does not rotate more than a certain angle, it will be pushed back to its original position by the limit member 782. However, after exceeding a certain angle, the first connecting rod 781 will drive the second connecting rod 783 to swing to the other side. At this time, the force exerted by the limit member 782 on the first connecting rod 781 is in the same direction as the gas blowing, that is, the first filter screen 76 will be blown and horizontal, and then cleaned.

[0036] The advantages of this arrangement are that it prevents the frequent rotation of the first filter 76 from affecting the filtration effect, improves the filtration efficiency of the first filter 76, reduces the frequency of cleaning, and resists the influence of external factors such as vibration on the rotation of the first filter 76. In addition, the rotation angle limit of the rotating shaft 75 can be flexibly adjusted according to different production working conditions.

[0037] like Figures 3 to 5 , which illustrates a cellulose drying apparatus with waste heat recovery according to an embodiment of the present invention. In some examples, before the cellulose drying apparatus is started, the components within the preheating housing 72 are in their initial positions. A chute 726 is located opposite the avoidance groove 724 . The ejector rod 727 is in its initial position within the chute 726 , near the rotating shaft 75 , with its ejector portion 7271 extending outside the chute 726 . The first filter screen 76 is vertical and the second filter screen 77 is horizontal. When too many impurities adhere to the first filter screen 76 and it automatically rotates to a horizontal position, the avoidance opening 761 located on it can avoid the pushing top portion 7271, and the first filter screen 76 does not interfere with the pushing member. When the first filter screen 76 needs to be reset after cleaning, the pushing member slides and the pushing top portion 7271 pushes the second filter screen 77. After it rotates to a certain angle, it automatically continues to rotate to a horizontal position under the action of the limiting member 782, so that the first filter screen 76 is vertical. The pushing member that has completed its work can be reset, and the pushing top portion 7271 passes through the avoidance opening 761 without interference.

[0038] The advantage of such a setting is that the first filter 76 is automatically reset: the push rod 727 can push the vertical second filter 77 to the horizontal position, and work together with the rotation limit assembly 78 and other components to achieve automatic reset of the first filter 76 and reduce the workload of manual operation.

[0039] like Figures 3 to 5 As shown, it shows a cellulose drying device with waste heat recovery in one embodiment of the present invention. In some examples, before the cellulose drying device is started, each component is in the initial position. The cleaning member 723 is located on one side of the overflow trough 721 near the air inlet end of the preheating shell 72. The connecting block 728 is in the slide 726 and is located below the ejection rod 727. At this time, the connecting block 728 is not engaged with the gear 729. Under the action of the second elastic member 7272, the ejection rod 727 remains in the initial position. The gear 729 rotates and is set on the inner wall of the slide 726, located below the ejection rod 727, and is engaged with the tooth portion 7291 on the ejection rod 727. At this time, the first filter screen 76 is vertical and the second filter screen 77 is horizontal. The air filtration work is carried out normally, and the entire device is ready for drying cellulose.

[0040] When there are too many impurities attached to the first filter screen 76, the air flow through it is reduced, and the air pressure received by the first filter screen 76 becomes larger, then the external air will blow the first filter screen 76 to rotate toward the overflow groove 721, and after overcoming the force of the limiter 782, it becomes horizontal. At the same time, the second filter screen 77 gradually breaks away from the horizontal state and becomes vertical. Then, as shown in FIG. Figure 5As shown, the cleaning member 723 starts to move toward the overflow trough 721, preparing to clean the first filter screen 76. When the cleaning member 723 moves close to the overflow trough 721, the connecting block 728 moves synchronously with the cleaning member 723, but the initial position of the connecting block 728 is a distance away from the gear 729. It will not engage with the gear 729 until it follows the cleaning member 723 and moves a distance, thereby driving the gear 729 to rotate counterclockwise, and under the action of meshing, it drives the ejection rod 727 to slide in the direction away from the second filter screen 77 (at this time it is in a vertical state) in the slide groove 726. At this time, the ejection rod 727 will move away from the second filter screen 77 and will not push the second filter screen 77 to avoid pushing the second filter screen 77 to rotate when cleaning the first filter screen 76, thereby affecting the cleaning of the first filter screen 76. After the connecting block 728 is disengaged from the gear 729, the ejection rod 727 is reset to its initial position under the action of the second elastic member 7272. After the cleaning is completed, the part 723 will move in the opposite direction and away from the overflow trough 721. In the process of returning to its original position after leaving the overflow trough 721, it will mesh with the gear 729 again. At this time, it will drive the gear 729 to rotate clockwise, and then drive the ejection part to approach the second filter screen 77 until the second filter screen 77 is pushed to rotate. After the second filter screen 77 rotates more than a certain angle, the first connecting rod 781 and the second connecting rod 783 will reverse direction, and with the help of the force of the limit member 782, the second filter screen 77 will continue to be pushed to the horizontal, and the first filter screen 76 will be vertical. At this time, the first filter screen 76 will not hit the cleaning part 723 when it rotates. It will automatically reset while completing the cleaning of the first filter screen 76. The connecting block 728 returns to its original position again and disengages from the gear 729. The ejection rod 727 is reset to its original position again under the action of the second elastic member 7272.

[0041] The advantage of such a setting is that it realizes the linkage and automatic switching of components: the setting of the gear 729, the tooth portion 7291 and the connecting block 728 realizes the linkage of the cleaning member 723 and the ejection rod 727, so that the various components work together during the filter switching process, without the need for an additional drive device, simplifying the equipment structure, and realizing the automatic reset of the first filter 76 to the vertical position after cleaning.

[0042] like Figure 9 As shown, it shows a cellulose drying device with waste heat recovery in one embodiment of the present invention. In some examples, during the assembly stage of the cellulose drying device, a limit bar 79 is installed on the top of the inner wall of the preheating shell 72. When the first filter screen 76 and the second filter screen 77 are installed on the rotating shaft 75, and the rotating shaft 75 is installed on the side of the inner wall of the preheating shell 72, the top edge of the first filter screen 76 is close to the limit bar 79. At this time, the first filter screen 76 and the second filter screen 77 are in the initial setting position, for example, the first filter screen 76 is vertical and the second filter screen 77 is horizontal. When the first filter screen 76 and the second filter screen 77 rotate, the limit bar 79 can limit the maximum rotation angle of the first filter screen 76 and the second filter screen 77 to prevent damage to the filter screen due to excessive rotation.

[0043] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A cellulose drying device capable of recovering waste heat, comprising an air heater (2), a drying pipeline (3), a feeder (1), a separator (4), a filter (5) and a fan (6) arranged in sequence, characterized in that: The heat exchanger (7) further comprises a waste heat recovery mechanism (7), the waste heat recovery mechanism (7) comprising a heat exchange shell (71) arranged between the drying pipeline (3) and the fan (6) and a preheating shell (72) arranged at the air inlet end of the air heater (2), a water outlet pipe (73) and a water return pipe (74) being connected between the heat exchange shell (71) and the preheating shell (72), a circulating pump being provided on the water outlet pipe (73) and / or the water return pipe (74), the water outlet pipe (73) being used to input water in the heat exchange shell (71) into the preheating shell (72), and a horizontally through-going air cavity being provided in the preheating shell (72) for preheating the gas entering the air heater (2).

2. The cellulose drying equipment capable of recovering waste heat according to claim 1, characterized in that: The waste heat recovery mechanism (7) further includes a rotating shaft (75) rotatably arranged at the bottom of the preheating shell (72), the rotating shaft (75) being arranged perpendicular to the through-going direction of the air cavity, and a first filter screen (76) and a second filter screen (77) arranged at a right angle are provided on the rotating shaft, and the rotating shaft (75) is configured to be rotatable, driving the first filter screen (76) to swing vertically to vertical, and at the same time driving the second filter screen (77) to swing vertically to horizontal, or driving the first filter screen (76) to swing vertically to horizontal, and at the same time driving the second filter screen (77) to swing vertically to vertical.

3. The cellulose drying equipment capable of recovering waste heat according to claim 2, characterized in that: The inner bottom wall of the preheating shell (72) is provided with an overflow trough (721) connected to the air passage cavity. A splash plate (722) is movably provided in the overflow trough (721). When the first filter screen (76) is vertically swung to a horizontal position, it can enter the overflow trough (721) to clean the first filter screen (76) with the help of water after heat exchange.

4. The cellulose drying equipment capable of recovering waste heat according to claim 3, characterized in that: The waste heat recovery mechanism (7) further comprises a cleaning member (723) movably arranged on one side of the splash plate (722), wherein the cleaning member (723) is capable of sliding along the through-going direction of the air cavity, and the cleaning member (723) is configured to clean the top surface of the first filter (76) located in the overflow trough (721) after moving.

5. The cellulose drying equipment capable of recovering waste heat according to claim 4, characterized in that: The inner side wall of the preheating shell (72) is provided with an avoidance groove (724), and the opening of the avoidance groove (724) is provided with a sealing plate (725). The shaft end of the rotating shaft (75) passes through the sealing plate (725) and extends into the avoidance groove (724). The rotating shaft (75) and the sealing plate (725) are rotatably matched. A rotation limiting assembly (78) is provided on the end of the rotating shaft (75), and the rotation limiting assembly (78) is used to limit the rotation angle of the rotating shaft (75).

6. The cellulose drying equipment capable of recovering waste heat according to claim 5, characterized in that: The rotation limiting assembly (78) includes a first connecting rod (781) arranged at the end of the rotating shaft (75) and forming an angle with the first filter (76), and a limiting member (782) arranged on the sealing plate (725) in a lifting manner. The limiting member (782) and the first connecting rod (781) are connected via a second connecting rod (783). A first elastic member (785) is further connected between the limiting member (782) and the sealing plate (725). The first elastic member (785) is used to provide a force for the limiting member (782) to push the second connecting rod (783) downward. When the first filter (76) is in a blocked state, the first filter (76) can drive the limiting member (782) under the action of wind to make the first filter (76) and the second filter (77) swing vertically synchronously.

7. The cellulose drying equipment capable of recovering waste heat according to claim 6, characterized in that: Two vertically extending limit blocks (784) are provided on the sealing plate (725). The limit blocks (784) are symmetrically located on both sides of the limit member (782) and are used to limit the limit member (782).

8. The cellulose drying equipment capable of recovering waste heat according to claim 5, characterized in that: The inner wall of the preheating shell (72) is further provided with a slide groove (726), the slide groove (726) is located on the opposite side of the avoidance groove (724), and a push rod (727) is provided in the slide groove (726) for sliding, and the sliding direction of the push rod (727) is parallel to the through direction of the air cavity, and the push rod (727) has a push-up portion (7271) extending out of the slide groove (726), and the first filter (76) has a corresponding avoidance opening (761), and the push rod (727) is configured to push the vertical second filter (77) to be horizontal after sliding.

9. The cellulose drying equipment capable of recovering waste heat according to claim 8, characterized in that: The side of the cleaning member (723) is provided with a connecting block (728) extending into the slide groove (726), the connecting block (728) is located below the ejector rod (727), a gear (729) is provided between the ejector rod (727) and the connecting block (728), and both the ejector rod (727) and the connecting block (728) have teeth (7291) meshing with the gear (729), a second elastic member (7272) is connected between the ejector rod (727) and the inner wall of the slide groove (726), and the connecting block (728) follows the cleaning member (723) close to the rotating shaft ( 75), the ejection rod (727) can be driven by the gear (729) to move away from the rotating shaft (75) and press against the second elastic member (7272), and can be reset under the elastic action of the second elastic member (7272) when the gear (729) and the connecting block (728) are disengaged; when the connecting block (728) follows the cleaning member (723) away from the rotating shaft (75), the gear (729) can drive the ejection rod (727) to move toward the side close to the rotating shaft (75) so as to push the second filter screen (77) to swing vertically to a horizontal state with the help of the ejection rod (727).

10. The cellulose drying equipment capable of recovering waste heat according to claim 2, characterized in that: The inner top wall of the preheating shell (72) is also provided with a horizontally extending limit strip (79), the extension direction of the limit strip (79) being arranged perpendicular to the through direction of the air passage cavity, and being used to limit the first filter screen (76) and the second filter screen (77).

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