A drying device for the preparation of hardwood pellets

Abstract

This utility model discloses a drying device for preparing mixed wood pellets, belonging to the field of pellet drying. It includes an inclined conveyor box, inside which are a conveying and dispersing component and a preheating layer, which can respectively convey, disperse, and preheat the raw materials. The conveyor box is connected to a spiral drying box through a guide pipe. The bottom end of the spiral drying box is connected to the outlet end of a high-pressure blower, and the inlet end of the high-pressure blower is connected to a hot air furnace. The feed end and exhaust end of the cyclone separator are connected to the top end of the spiral drying box and the inlet end of a bag filter, respectively. The exhaust end of the bag filter is connected to the inlet end of a circulating fan, and the outlet end of the circulating fan is connected to the preheating layer.

Description

Technical Field

[0001] This utility model relates to the field of particle drying, specifically to a drying device for preparing mixed wood particles. Background Technology

[0002] In the field of biomass pellet fuel production, the drying of hardwood pellets is a crucial and energy-intensive step. As an important raw material for biomass pellet fuel, the quality of hardwood pellet drying directly affects the quality of the subsequent product and the cost of the entire production process. Currently, hardwood pellet drying occupies a core position in the entire hardwood pellet production process because the quality and efficiency of drying have a significant impact on the combustion performance and storage stability of the final biomass pellet fuel.

[0003] Mixed wood pellets are characterized by high moisture content, high viscosity, and uneven particle size. Many dryers use only simple screw or belt conveyors for feeding, lacking effective dispersing devices. This causes the wet material to easily adhere and clump at the feed inlet of the drying equipment, leading to arching and blockages, and ultimately production interruptions. Furthermore, the material enters the dryer in clumps and blocks, resulting in uneven material distribution within the drying chamber. Large clumps may have a charred exterior but remain wet inside, severely impacting the uniformity of drying and heat exchange efficiency.

[0004] During the drying process, the material is lifted and falls with poor dispersion, failing to form a uniform material curtain on the drying cross-section. Hot air passes directly through the sparse areas of the material curtain, significantly reducing thermal efficiency. Moreover, small particles and lightweight materials are quickly blown away by the airflow, resulting in short residence time; while large pieces and heavy materials have long residence time, leading to extremely uneven moisture content in the finished product.

[0005] Due to the high dust content and abrasiveness of mixed wood materials, the sealing structure is prone to severe air leakage. External cold air is drawn into the drying system, significantly reducing the hot air temperature at the dryer's inlet and weakening the drying power. Furthermore, the escape of dust not only causes material loss and environmental pollution but also poses a serious risk of dust explosion. Utility Model Content

[0006] To address the technical problems mentioned above, such as uneven material distribution in the drying chamber, large material clumps being charred on the outside but still wet on the inside, severely affecting drying uniformity and heat exchange efficiency, small particles and lightweight materials being quickly blown away by the wind with short residence time, and large and heavy materials having long residence time, resulting in extremely uneven moisture content in the finished product, and the sealing structure being prone to serious air leakage, dust escape not only causes material loss and environmental pollution, but also poses a serious dust explosion safety risk, this utility model provides a drying device for the preparation of mixed hardwood pellets.

[0007] A drying device for preparing hardwood pellets includes an inclined conveyor box. The conveyor box is equipped with a conveying and dispersing component and a preheating layer, which can convey, disperse, and preheat the raw materials respectively. The conveyor box is connected to a spiral drying box through a guide pipe. The bottom end of the spiral drying box is connected to the outlet end of a high-pressure blower. The inlet end of the high-pressure blower is connected to a hot air furnace. The inlet and outlet ends of a cyclone separator are connected to the top end of the spiral drying box and the inlet end of a bag filter, respectively. The outlet end of the bag filter is connected to the inlet end of a circulating fan. The outlet end of the circulating fan is connected to the preheating layer.

[0008] A further proposed solution is as follows: the guide pipe is installed through the inclined bottom of the conveyor box, and the whole structure is a funnel shape that narrows from wide to narrow. The feed hopper is fixedly installed on the top wall of the inclined top of the conveyor box. Rotary valves are installed at the bottom of the feed hopper and the narrow part of the guide pipe to seal the feed.

[0009] A further proposed solution is as follows: a geared motor is installed on the outer wall of the conveyor box, and the conveying and dispersing assembly includes a rotating shaft fixedly installed on the output end of the geared motor. Several spiral propulsion blades are fixedly installed on the outer wall of the rotating shaft, which can propel and convey the material. Dispersing blades are fixedly installed on the outer wall of the rotating shaft in the gaps between the spiral propulsion blades, which can disperse the material.

[0010] A further proposed solution is as follows: the bottom of the spiral drying oven is set as a conical bottom, and a metal expansion joint is connected to the conical bottom. The other end of the metal expansion joint is connected to the air outlet of the high-pressure blower. A partition wall is fixedly installed inside the hot air furnace, which divides the hot air furnace into a combustion chamber and a heat exchange chamber. A heat exchanger is installed inside the heat exchange chamber. Several air vents are set on the partition wall, which can transport the high-temperature flue gas in the combustion chamber to the heat exchanger for heat exchange. The other end of the heat exchanger is connected to the air inlet of the high-pressure blower through an air supply pipe.

[0011] A further proposed solution is as follows: an exhaust pipe is installed at the top of the spiral drying box, with the other end of the exhaust pipe located at the feed end of the cyclone separator. The exhaust end of the cyclone separator is also connected to the inlet end of the bag filter through the exhaust pipe. A filter screen is fixedly installed inside the bag filter. The inlet and outlet ends of the bag filter are located below and above the filter screen, respectively. Several dust collection filter bags are detachably installed on the top wall of the filter screen. The outlet end of the bag filter is also connected to the inlet end of the circulating fan through the exhaust pipe.

[0012] A further solution is: the air outlet of the circulating fan discharges part of the air to the external environment, and the rest of the air is connected to the preheating layer through the exhaust pipe. A circulating air pump is installed on the exhaust pipe. The preheating layer is fixedly installed on the side wall of the conveying box, and several air vents are also provided through it on the side near the conveying and dispersing components.

[0013] A further proposed solution is to install rotary valves at the bottom discharge pipes of both the cyclone separator and the bag filter, and to install collection boxes at the bottom of the discharge pipes respectively.

[0014] Compared with existing technologies, the beneficial effects of this invention are as follows: The conveying and dispersing component can disperse the high-moisture, high-viscosity mixed wood particles during spiral conveying, preventing material adhesion and clumping at the feed inlet of the spiral drying chamber, thus ensuring continuous production. Simultaneously, the pre-drying effect of the preheating layer makes the material fluffy, laying the foundation for subsequent efficient drying, reducing the load on the main dryer, improving overall drying efficiency, and allowing for the recycling of the hot air generated during subsequent drying. The spiral structure of the spiral drying chamber extends the residence time of the material in the drying zone, and the friction between the material and the spiral inner wall of the chamber further breaks and disperses the material, completely enveloping it in hot air, achieving instantaneous evaporation of moisture and greatly improving the uniformity of drying. The use of a cyclone separator and bag filter can better achieve dust removal, preventing dust-laden gas from being directly emitted into the outside air and polluting the environment. Attached Figure Description

[0015] Figure 1 This is a front view schematic diagram of the structure of this utility model;

[0016] Figure 2 This is a top view of the structure of this utility model;

[0017] Figure 3 This is a schematic diagram of part A of the structure of this utility model;

[0018] Figure 4 This is a schematic diagram of part B of the structure of this utility model;

[0019] Figure 5 This is a schematic diagram of part C of the present invention.

[0020] In the diagram: 1. Conveyor box; 2. Guide pipe; 3. Spiral drying box; 4. Conveying and dispersing assembly; 5. Preheating layer; 6. Cyclone separator; 7. Bag filter; 8. High-pressure blower; 9. Circulating blower; 10. Hot air furnace; 11. Rotary valve; 12. Gear motor; 13. Rotating shaft; 14. Spiral propulsion blades; 15. Dispersing blades; 16. Metal expansion joint; 17. Partition wall; 18. Combustion chamber; 19. Heat exchange chamber; 20. Vent; 21. Heat exchanger; 22. Gas pipeline; 23. Exhaust pipe; 24. Filter screen; 25. Dust collector filter bag; 26. Circulating air pump; 27. Collection box; 28. Feed hopper. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of the utility model described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0024] Furthermore, some of the aforementioned terms, besides indicating location or positional relationships, may also have other meanings. For example, the term "above" may, in certain circumstances, indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances. Additionally, the term "multiple" should mean two or more.

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments of the present invention can be combined with each other. The following will refer to the accompanying drawings. Figures 1-5 The present invention will be described in detail with reference to the embodiments.

[0026] A drying device for preparing mixed wood pellets includes an inclined conveyor box 1. The conveyor box 1 is equipped with a conveying and dispersing component 4 and a preheating layer 5, which can convey, disperse, and preheat the raw materials respectively. A feed hopper 28 is fixedly installed on the top wall through the inclined top of the conveyor box 1. A rotary valve 11 is installed at the bottom of the feed hopper 28 for sealing the feed.

[0027] The feeding hopper 28 has a structure that is wide at the top and narrow at the bottom. The material enters from the wide part of the feeding hopper 28 to the narrow part. The rotary valve 11 is located at the narrow part to seal the feeding and prevent gas from escaping. The material enters the conveying box 1 and is broken up and pre-dried. The broken material is then propelled forward by the spiral propulsion blades 14 to ensure smooth material conveying. The inclined design utilizes gravity to accelerate the material conveying speed.

[0028] A geared motor 12 is installed on the outer wall of the conveyor box 1. The conveying and dispersing assembly 4 includes a rotating shaft 13 fixedly installed on the output end of the geared motor 12. Several spiral propulsion blades 14 are fixedly installed on the outer wall of the rotating shaft 13, which can propel and convey materials. Dispersing blades 15 are fixedly installed on the outer wall of the rotating shaft 13 in the gap between the several spiral propulsion blades 14, which can disperse materials.

[0029] Start the geared motor 12 to drive the rotating shaft 13 to rotate, which in turn causes several spiral propulsion blades 14 to rotate synchronously, thus propel the raw material in a spiral direction downwards. When the raw material reaches the dispersing blade 15, the high-speed rotation of the dispersing blade 15 generates a strong impact force, which completely breaks down the mixed wood raw material with high moisture content, high viscosity, and uneven particle size. After the dispersing blade 15 comes into contact with the material, it can break down and crush the material, preventing the raw material from clumping together and effectively solving the problem of arching and blockage.

[0030] The conveyor box 1 is connected to the spiral drying chamber 3 via a guide pipe 2. The guide pipe 2 runs through the inclined bottom end of the conveyor box 1 and has a funnel-shaped structure that narrows from wide to narrow. A rotary valve 11 is installed at the narrow end of the guide pipe 2 to seal the feed. The raw material conveyed by the conveyor box 1 falls into the wide end of the guide pipe 2, which has a conical structure and is also inclined. Under the action of gravity, the material falls from the wide end to the narrow end. When the rotary valve 11 is opened, the material falls into the feed inlet of the spiral drying chamber 3.

[0031] The bottom end of the spiral drying box 3 is connected to the outlet end of the high-pressure blower 8, and the inlet end of the high-pressure blower 8 is connected to the hot air furnace 10. The bottom end of the spiral drying box 3 is set as a conical bottom end, and a metal expansion joint 16 is connected to the conical bottom end. The other end of the metal expansion joint 16 is connected to the outlet end of the high-pressure blower 8. A partition wall 17 is fixedly installed inside the hot air furnace 10. The partition wall 17 divides the hot air furnace 10 into a combustion chamber 18 and a heat exchange chamber 19. A heat exchanger 21 is installed inside the heat exchange chamber 19. Several air vents 20 are provided on the partition wall 17, which can transport the high-temperature flue gas in the combustion chamber 18 to the heat exchanger 21 for heat exchange. The other end of the heat exchanger 21 is connected to the inlet end of the high-pressure blower 8 through a gas pipeline 22.

[0032] The burner inside combustion chamber 18 generates hot air, which enters heat exchange chamber 19 through several vents 20 and is heated by heat exchanger 21, which is a plate heat exchanger. The high-pressure blower 8 is started, causing the hot air in heat exchanger 21 to enter the inlet of the high-pressure blower 8 through the air supply pipe 22, then flow from the outlet of the high-pressure blower 8 into the metal expansion joint 16, and finally enters the spiral drying chamber 3 from the bottom, driving the conveyed raw material upwards along the spiral structure of the drying chamber 3. During this upward movement, the hot air fully contacts and dries the material, and then moves upwards with the hot air to the exhaust end at the top.

[0033] The feed end and exhaust end of the cyclone separator 6 are connected to the top of the spiral drying box 3 and the air inlet of the bag filter 7, respectively. The top of the spiral drying box 3 is equipped with an exhaust pipe 23, and the other end of the exhaust pipe 23 is located on the feed end of the cyclone separator 6. The exhaust end of the top of the cyclone separator 6 is also connected to the air inlet of the bag filter 7 through the exhaust pipe 23.

[0034] The raw material moves upward with the hot air to the exhaust pipe 23 at the top of the spiral drying chamber 3, and then enters the cyclone separator 6. The material moves downward along the lower conical end of the cyclone separator 6, while the dust-laden gas enters the exhaust pipe 23 at the top exhaust end of the cyclone separator 6 and then enters the inlet end of the bag filter 7. A rotary valve 11 is installed at the bottom discharge pipe of the cyclone separator 6, and a collection box 27 is installed at the bottom of the discharge pipe. When the rotary valve 11 is opened, the raw material is discharged from the bottom discharge pipe of the cyclone separator 6 into the collection box 27 for storage.

[0035] The exhaust end of the bag filter 7 is connected to the inlet end of the circulating fan 9. A filter screen 24 is fixedly installed inside the bag filter 7. The inlet end and outlet end of the bag filter 7 are respectively located below and above the filter screen 24. Several dust collection filter bags 25 are detachably installed on the top wall of the filter screen 24. The outlet end of the bag filter 7 is also connected to the inlet end of the circulating fan 9 through the exhaust pipe 23.

[0036] Dust-laden gas enters the bag filter 7 from the inlet end. After passing through the filter screen 24, larger dust particles are filtered out and fall to the bottom, while smaller dust particles pass through the filter screen 24 and are then filtered by several dust collection filter bags 25 before being discharged from the exhaust pipe 23 at the outlet end. The circulating fan 9 can attract the dust-laden gas to move along the gas movement trajectory inside the bag filter 7.

[0037] A rotary valve 11 is installed at the bottom discharge pipe of the bag filter 7, and a collection box 27 is installed at the bottom of the discharge pipe. After the rotary valve 11 is opened, the dust can be collected in the collection box 27.

[0038] The outlet of the circulating fan 9 is connected to the preheating layer 5. The outlet of the circulating fan 9 discharges part of the air to the external environment, and the rest of the air is connected to the preheating layer 5 through the exhaust pipe 23. A circulating air pump 26 is installed on the exhaust pipe 23. The preheating layer 5 is fixedly installed on the side wall of the conveying box 1, and several air vents 20 are also provided through it on the side near the conveying and dispersing component 4.

[0039] Turn on the circulating air pump 26 so that the warm gas in the outlet of the circulating fan 9 is transported to the preheating layer 5 through the exhaust pipe, and enters the conveying box 1 through several air vents 20 to preheat and dry the raw materials. Some of the air in the outlet of the circulating fan 9 can also be discharged to the outside air through the air vents 20.

[0040] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A drying device for preparing hardwood pellets, comprising an inclined conveyor box (1), characterized in that: The conveying box (1) is equipped with a conveying and dispersing component (4) and a preheating layer (5) to convey, disperse, and preheat the raw materials respectively. The conveying box (1) is connected to the spiral drying box (3) through the guide pipe (2). The bottom end of the spiral drying box (3) is connected to the outlet end of the high pressure blower (8). The inlet end of the high pressure blower (8) is connected to the hot air furnace (10). The feed end and exhaust end of the cyclone separator (6) are connected to the top end of the spiral drying box (3) and the inlet end of the bag filter (7) respectively. The exhaust end of the bag filter (7) is connected to the inlet end of the circulating fan (9). The outlet end of the circulating fan (9) is connected to the preheating layer (5).

2. The drying equipment for preparing hardwood pellets according to claim 1, characterized in that: The guide pipe (2) is installed through the inclined bottom end of the conveyor box (1). The whole structure is a funnel-shaped structure from wide to narrow. The feed hopper (28) is fixedly installed through the top wall of the inclined top end of the conveyor box (1). Rotary valves (11) are installed at the bottom end of the feed hopper (28) and the narrow part of the guide pipe (2) to seal the feed.

3. A drying device for preparing hardwood pellets according to claim 2, characterized in that: A geared motor (12) is installed on the outer wall of the conveyor box (1). The conveying and dispersing assembly (4) includes a rotating shaft (13) fixedly installed on the output end of the geared motor (12). Several spiral propulsion blades (14) are fixedly installed on the outer wall of the rotating shaft (13), which can promote and convey the material. Dispersing blades (15) are fixedly installed on the outer wall of the rotating shaft (13) in the gap between the several spiral propulsion blades (14), which can disperse the material.

4. A drying device for preparing hardwood pellets according to claim 2, characterized in that: The bottom of the spiral drying oven (3) is set as a conical bottom end, and a metal expansion joint (16) is provided at the conical bottom end. The other end of the metal expansion joint (16) is connected to the air outlet of the high pressure blower (8). A partition wall (17) is fixedly installed inside the hot air furnace (10). The partition wall (17) divides the hot air furnace (10) into a combustion chamber (18) and a heat exchange chamber (19). A heat exchanger (21) is installed inside the heat exchange chamber (19). Several air vents (20) are provided on the partition wall (17) so that the high temperature flue gas in the combustion chamber (18) can be transported to the heat exchanger (21) for heat exchange. The other end of the heat exchanger (21) is connected to the air inlet of the high pressure blower (8) through the gas pipeline (22).

5. A drying device for preparing hardwood pellets according to claim 4, characterized in that: The top of the spiral drying box (3) is provided with an exhaust pipe (23), and the other end of the exhaust pipe (23) is provided on the feed end of the cyclone separator (6). The exhaust end of the top of the cyclone separator (6) is also connected to the air inlet of the bag filter (7) through the exhaust pipe (23). The bag filter (7) is fixedly provided with a filter screen (24). The air inlet and outlet of the bag filter (7) are respectively located below and above the filter screen (24). Several dust removal filter bags (25) are detachably installed on the top wall of the filter screen (24). The air outlet of the bag filter (7) is also connected to the air inlet of the circulating fan (9) through the exhaust pipe (23).

6. A drying device for preparing hardwood pellets according to claim 5, characterized in that: The air outlet of the circulating fan (9) discharges part of the air to the external environment, and the rest of the air is connected to the preheating layer (5) through the exhaust pipe (23). A circulating air pump (26) is installed on the exhaust pipe (23). The preheating layer (5) is fixedly installed on the side wall of the conveying box (1), and several air vents (20) are also provided on the side of the preheating layer (5) that is close to the conveying and dispersing component (4).

7. A drying device for preparing hardwood pellets according to claim 6, characterized in that: A rotary valve (11) is installed at the bottom discharge pipe of both the cyclone separator (6) and the bag filter (7), and a collection box (27) is installed at the bottom of the discharge pipe respectively.

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