Organic solid waste composite heat source low-temperature drying device and method

Abstract

The application discloses a kind of organic solid waste composite heat source low-temperature drying device and method, it is related to poultry house organic solid waste drying technical field, mainly applied in chicken house field, including poultry house, with the heat collection air duct that poultry house is communicated by exhaust fan, with the drying machine air inlet duct that heat collection air duct is communicated, with the heat pump unit for dehumidification and heating of ambient gas that drying machine air inlet duct is communicated, and with the drying bin that drying machine air inlet duct is communicated, first air door is arranged between heat collection air duct and drying machine air inlet duct, first air door and drying machine air inlet duct between first air door are arranged with the first air draught fan that is communicated with external environment, second air door is arranged between first air draught fan and drying machine air inlet duct, third air door is arranged between heat pump unit and drying machine air inlet duct, first air door, second air door and third air door are used to realize the on-off of corresponding communication pipeline, the optimal air path selection under different climate conditions can be realized.

Description

Technical Field

[0001] This invention relates to the field of organic solid waste drying technology, specifically to a low-temperature drying device and method for organic solid waste using a composite heat source. Background Technology

[0002] The collection and treatment of livestock and poultry manure is a crucial link in promoting the green development of animal husbandry. Currently, the main methods for treating livestock and poultry manure include drying for fertilizer production and fermentation composting. Drying for fertilizer production is an important way to achieve the harmlessness and resource utilization of wet livestock and poultry manure. Taking chicken coops as an example, wet chicken manure in chicken coops has a moisture content of 60%-70%. After drying, ammonia emissions can be effectively reduced, and it is easier to store and transport. Traditional drying for fertilizer production uses sun drying. The disadvantages of this method are that it requires a large area, cannot dry manure on rainy days, and cannot meet the needs of large-scale farms.

[0003] Drying manure using drying equipment requires a significant amount of heat energy for evaporating manure. In large-scale chicken farms, forced ventilation helps maintain comfort. Utilizing waste heat from the chicken house and other low-cost heat sources can effectively reduce drying costs. Current technologies primarily utilize heat pumps to recover heat from the chicken house and solar water heaters to dry chicken manure. However, during rainy spring or summer weather, high humidity and insufficient heat in the chicken house make drying difficult. In summer, even on non-rainy days, water curtains are needed for cooling, leading to high humidity and failing to meet drying requirements. In other words, current technologies lack efficient, low-energy-consumption drying devices for chicken manure suitable for different seasons.

[0004] Therefore, it is necessary to develop and design a low-temperature drying device and method for organic solid waste with composite heat source, and to dry livestock and poultry manure according to the characteristics of different seasons. This is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a low-temperature drying device and method for organic solid waste using a composite heat source, which dries livestock and poultry manure according to the characteristics of different seasons.

[0006] To achieve the above objectives, the present invention provides the following solution: A low-temperature drying device for organic solid waste using a composite heat source includes a livestock and poultry house, a heat collection duct connected to the livestock and poultry house via an exhaust fan, a dryer inlet duct connected to the heat collection duct, a heat pump unit connected to the dryer inlet duct for dehumidifying and heating ambient air, and a drying chamber connected to the dryer inlet duct. A first damper is provided between the heat collection duct and the dryer inlet duct. A first induced draft fan connected to the external environment is provided between the first damper and the dryer inlet duct. A second damper is provided between the first induced draft fan and the dryer inlet duct. A third damper is provided between the heat pump unit and the dryer inlet duct. The first damper, the second damper, and the third damper are used to open and close the corresponding connecting pipes.

[0007] Preferably, a fourth air door is provided at the end of the heat collection air duct away from the first air door, and the fourth air door is used to realize the connection and disconnection between the livestock and poultry house and the external environment.

[0008] Preferably, it also includes an ambient temperature and humidity sensor installed in the external environment, an air inlet duct temperature and humidity sensor installed in the air inlet duct of the dryer, and a control system, wherein the control system is electrically connected to the ambient temperature and humidity sensor, the heat pump unit, the air inlet duct temperature and humidity sensor, the first damper, the second damper, the third damper, and the fourth damper.

[0009] Preferably, a ventilation opening is provided at the end of the livestock and poultry house away from the exhaust fan.

[0010] Preferably, the heat pump unit includes an air inlet, an evaporator, a condenser, and a second induced draft fan arranged sequentially from the end away from the air inlet duct of the dryer to the end closer to the air inlet duct of the dryer.

[0011] Preferably, the drying chamber is equipped with a belt dryer for supporting livestock and poultry manure, and the drying chamber is equipped with an air inlet connected to the air inlet duct of the dryer and an air outlet connected to the external environment through a third induced draft fan.

[0012] Preferably, the belt dryer is equipped with a mesh conveyor belt, and an air distribution plate is provided at the air outlet end of the air inlet, with the air distribution plate located at the bottom of the mesh conveyor belt.

[0013] Preferably, the diameter of the air distribution disc is greater than or equal to the width of the mesh conveyor belt.

[0014] Preferably, the air outlet is connected to the waste gas treatment unit.

[0015] This invention also discloses a low-temperature drying method for organic solid waste using a composite heat source. The method utilizes the aforementioned low-temperature drying device for organic solid waste using a composite heat source. During spring or rainy summer days, the first and second air doors are closed, and the third air door is opened. The heat pump unit dehumidifies and heats the ambient air to dry livestock and poultry manure. During autumn and winter, the first air door is opened, while the second and third air doors are closed, allowing the air exhausted from the livestock and poultry shed to dry the livestock and poultry manure. During non-rainy summer days, the first and third air dampers are closed, while the second air damper is open, allowing the livestock and poultry manure to be dried directly through ambient air.

[0016] The present invention achieves the following technical effects compared to the prior art: By integrating multiple modes such as waste heat recovery from livestock and poultry houses, dehumidification and heating by heat pump units, and direct introduction of outside air, the energy efficiency and environmental adaptability of the drying equipment are significantly improved. In autumn and winter, the system can use exhaust fans to introduce air rich in waste heat from the sheds into the air intake duct of the dryer through the heat collection duct, realizing waste heat recovery and reducing drying energy consumption. In spring or summer rainy season, when the outside humidity is too high, the heat pump unit dehumidifies and heats the ambient air to ensure that the air entering the drying chamber is dry and at a suitable temperature, thus ensuring that the drying effect is not affected by high humidity weather. In summer non-rainy weather, dry and hot outside air is directly introduced through the first exhaust fan, and with the flexible switching of the first, second, and third air dampers, the optimal air path selection can be achieved under different climatic conditions. This not only effectively reduces the energy consumption of the drying process, but also ensures the continuity and stability of drying operations throughout the year, significantly improving the economy and environmental protection of livestock and poultry waste drying. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Appendix Figure 1 This is a schematic diagram of the overall structure of the organic solid waste composite heat source low-temperature drying device disclosed in this invention; The components include: 1. Livestock and poultry shed; 2. Belt dryer; 3. Third induced draft fan; 4. Third air damper; 5. Second induced draft fan; 6. Heat pump unit; 7. Air inlet; 8. First induced draft fan; 9. Second air damper; 10. First air damper; 11. Fourth air damper; 12. Heat collection duct; 13. Exhaust fan; 14. Ventilation outlet; 15. Control system; 16. Ambient temperature and humidity sensor; and 17. Dryer air inlet duct. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0020] The purpose of this invention is to provide a low-temperature drying device and method for organic solid waste using a composite heat source, which is designed to dry livestock and poultry manure according to the characteristics of different seasons.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] refer to Figure 1 The organic solid waste composite heat source low-temperature drying device disclosed in this embodiment of the invention mainly takes a chicken house as an example, and includes at least a poultry house 1 (i.e., a chicken house). A heat collection duct 12 is connected to the chicken house, and the heat collection duct 12 is connected to the inside of the chicken house through an exhaust fan 13. The heat collection duct 12 is connected to the air inlet duct 17 of the dryer. In autumn and winter, the residual heat in the chicken house can be directly introduced into the drying chamber through the air inlet duct 17 of the dryer. A heat pump unit 6 is connected to and installed on the air inlet duct 17 of the dryer. The heat pump unit 6 is used to dehumidify and heat the ambient gas, so as to dehumidify the gas with high humidity in spring or summer rainy season. Humidification and heating are introduced into the drying chamber for drying. A first damper 10 is provided between the heat collection air duct 12 and the dryer air inlet air duct 17. A first induced draft fan 8, which is connected to the external environment, is provided between the first damper 10 and the dryer air inlet air duct 17. The first induced draft fan 8 can directly introduce the external ambient air into the drying chamber for drying during non-rainy weather in summer. A second damper 9 is provided between the first induced draft fan 8 and the dryer air inlet air duct 17. A third damper 4 is provided between the heat pump unit 6 and the dryer air inlet air duct 17. The first damper 10, the second damper 9, and the third damper 4 are used to realize the opening and closing of the corresponding connecting pipes. In this embodiment, by integrating multiple modes such as waste heat recovery from the chicken coop, dehumidification and heating by the heat pump unit 6, and direct introduction of outside air, the energy efficiency and environmental adaptability of the drying equipment are significantly improved. In autumn and winter, the system can use the exhaust fan 13 to introduce the air rich in waste heat from the coop into the air inlet duct 17 of the dryer through the heat collection duct 12, thereby realizing waste heat recovery and reducing drying energy consumption. In spring or summer rainy season, when the outside humidity is too high, the heat pump unit 6 dehumidifies and heats the ambient air to ensure that the air entering the drying chamber is dry and at a suitable temperature, thus ensuring that the drying effect is not affected by high humidity weather. In summer non-rainy weather, the first exhaust fan 8 directly introduces dry and hot outside air, and with the flexible switching of the first damper 10, the second damper 9, and the third damper 4, the optimal air path selection under different climatic conditions can be achieved. This not only effectively reduces the energy consumption of the drying process, but also ensures the continuity and stability of drying operations throughout the year, significantly improving the economy and environmental protection of livestock and poultry waste drying.

[0023] It should be noted that the opening and closing of each damper can also be done without adjusting according to seasonal changes, and is also within the scope of protection of this invention, simply by setting thresholds in the control system.

[0024] refer to Figure 1 In one embodiment, a fourth damper 11 is provided at the end of the heat collection duct 12 away from the first damper 10. The fourth damper 11 is used to connect and disconnect the chicken house from the external environment. When there is no need to recover waste heat or the temperature inside the chicken house is too high, the inside of the chicken house can be directly connected to the external environment. The exhaust fan 13 is used to exhaust the hot and humid air inside the house to the outside, thereby achieving ventilation and cooling of the chicken house, improving the air quality inside the house, and avoiding heat accumulation that affects the health of livestock and poultry. At the same time, when waste heat needs to be recovered, the fourth damper 11 is closed to ensure that the hot air inside the house enters the heat collection duct 12 first for drying and to prevent heat from escaping. This design allows the chicken house exhaust system to flexibly switch between the two modes of "waste heat recovery" and "indoor environment control", which not only ensures the energy-saving operation of the drying equipment, but also takes into account the comfort and hygiene requirements of the breeding environment.

[0025] refer to Figure 1In one embodiment, the system also includes an ambient temperature and humidity sensor 16 installed in the external environment and an air inlet duct temperature and humidity sensor installed in the dryer's air inlet duct 17, as well as a control system 15 installed outside the entire device. The control system 15 is electrically connected to the heat pump unit 6, the ambient temperature and humidity sensor 16, the air inlet duct temperature and humidity sensor, the first damper 10, the second damper 9, the third damper 4, and the fourth damper 11. The ambient temperature and humidity sensor 16 and the air inlet duct temperature and humidity sensor can respectively collect the temperature and humidity data of the ambient air and the air inlet duct 17 of the dryer in real time, and transmit the data to the control system 15. The control system 15 adjusts the drying parameters according to the preset drying parameters. The system automatically judges the current climate conditions (such as dry and cold winters, hot and humid summers, and high humidity during the rainy season) based on process parameters, and then intelligently controls the on / off combination of the first to fourth dampers 11. It automatically switches between "livestock and poultry house waste heat recovery mode", "heat pump dehumidification and heating mode" or "direct external air intake mode". This closed-loop control mechanism not only avoids the lag and misjudgment of manual operation, ensuring that the drying chamber can obtain a drying medium with suitable temperature and controllable humidity under any season and weather conditions, but also makes the greatest priority to utilize the waste heat of the chicken house or favorable external climate conditions, and only starts the heat pump unit 6 when necessary, thereby significantly reducing the overall energy consumption of the system and improving the automation level and operating economy of the drying operation.

[0026] It should be noted that when the temperature or humidity of the gas in the air inlet duct 17 of the dryer is detected by the air inlet temperature and humidity sensor as not meeting the requirements, the air volume of the second induced draft fan 5 or the exhaust fan 13 can be controlled by the control system 15, or the operating parameters of the heat pump unit 6 (such as the evaporator / condenser fan speed) can be adjusted. That is, when the temperature is too low, the control system 15 can appropriately reduce the air volume of the first induced draft fan 8 or the second induced draft fan 5 to prolong the residence time of hot air in the heating components (such as the condenser or the waste heat channel of the livestock and poultry house), or increase the heating output of the heat pump unit. When the humidity is too high, the air volume of the second induced draft fan 5 can be increased or the dehumidification intensity of the evaporator can be increased to reduce the moisture content of the incoming air. At the same time, adjusting the air volume of the exhaust fan 13 can flexibly control the amount of waste heat recovery, avoiding excessive ventilation in the house from affecting the breeding environment. This dynamic adjustment method based on sensor feedback can achieve smoother and more accurate temperature and humidity control compared to simple on / off control, significantly improving the stability and consistency of the drying effect, while avoiding energy waste and extending the equipment life.

[0027] A preset threshold is established in the control system 15. When the temperature is between 5℃ and 19℃ and the relative humidity is below 60% (absolute humidity below 0.005 kg / kg), the control system 15 determines it to be autumn or winter. At this time, the control system 15 performs the following operations: closes the second damper 9 (cuts off the intake of external air), closes the fourth damper 11 (prevents heat loss from the chicken house), opens the first damper 10 (connects the chicken house to the heat collection duct 12), and closes the third damper 4 (the heat pump unit 6 does not start). When the temperature is between 20℃ and 35℃ and the air humidity is above 70% (absolute humidity above 0.01 kg / kg), this... When the temperature is between 30℃ and 40℃ and the relative humidity is between 40% and 65%, the control system 15 performs the following operations: closes the first damper 10 (cuts off the waste heat circuit of the chicken house), closes the second damper 9 (cuts off the direct intake of outside air), opens the third damper 4 (connects to the heat pump unit 6), and starts the heat pump unit 6 to dehumidify and heat the outside air. When the temperature is between 30℃ and 40℃ and the relative humidity is between 40% and 65%, the control system 15 performs the following operations: closes the first damper 10 (does not recover waste heat from the chicken house), closes the third damper 4 (does not start the heat pump unit 6), opens the second damper 9 (connects to the external environment), and starts the first exhaust fan 8 to directly extract dry and hot outside air.

[0028] refer to Figure 1 As a preferred method, a vent 14 is provided at the end of the chicken house away from the exhaust fan 13. The vent 14 and the exhaust fan 13 together form a through airflow channel, allowing air inside the house to enter through the vent 14, flow through the entire chicken house, and be discharged by the exhaust fan 13. This effectively avoids airflow short-circuiting or dead zones and significantly improves the uniformity of air quality distribution inside the house. When the fourth air door 11 is closed for waste heat recovery, the vent 14 can introduce a small amount of fresh air from outside to maintain oxygen supply and air freshness inside the house and prevent the accumulation of harmful gases such as carbon dioxide and ammonia due to closed recovery. When the fourth air door 11 is opened for ventilation and cooling inside the house, the vent 14 and the exhaust fan work together to greatly improve ventilation efficiency and quickly discharge hot and humid air, creating a healthier and more comfortable growth environment for livestock and poultry.

[0029] refer to Figure 1As a preferred embodiment, the heat pump unit 6 includes an air inlet 7, an evaporator, a condenser, and a second induced draft fan 5, arranged sequentially from the end furthest from the dryer's air inlet duct 17 towards the end closest to the dryer's air inlet duct 17. Outside air first enters through the air inlet 7, passes through the evaporator for cooling and dehumidification (releasing moisture), then passes through the condenser for heating, and finally is sent into the dryer's air inlet duct 17 by the second induced draft fan 5. This "dehumidification first, then heating" sequential design results in lower humidity and higher temperature air entering the drying chamber, significantly improving the moisture carrying capacity and drying efficiency per unit volume of air. At the same time, the evaporator and condenser are arranged in series in the same airflow channel, resulting in a compact structure and reducing heat loss in intermediate pipelines. The second induced draft fan 5 is located at the end, which can effectively overcome the wind resistance of the evaporator and condenser, ensuring a stable and sufficient airflow into the drying chamber and guaranteeing reliable operation of the heat pump unit 6 in humid or low-temperature environments.

[0030] refer to Figure 1 As one implementation method, a belt dryer 2 is installed inside the drying chamber to support livestock and poultry manure. The drying chamber is equipped with an air inlet connected to the air inlet duct 17 of the dryer and an air outlet connected to the external environment through a third exhaust fan 3. After the hot drying air enters the drying chamber through the air inlet, it passes through the manure layer on the belt dryer 2 from bottom to top or horizontally, making full contact with the material and removing moisture. The humid air is discharged outside the chamber through the air outlet under the suction of the third exhaust fan 3, forming a stable "air inlet-drying-moisture removal" airflow cycle. The belt dryer 2 can continuously or intermittently transport manure, so that the material is heated evenly during the movement, avoiding local over-drying or under-drying, and significantly improving drying uniformity and efficiency. At the same time, the third exhaust fan 3 can adjust the exhaust volume according to the needs of the drying stage, flexibly control the humidity and temperature inside the chamber, and prevent moisture accumulation that leads to a decrease in drying effect. The overall structure is compact and the airflow organization is reasonable. It is suitable for batch continuous drying operations and is also easy to connect efficiently with front-end waste heat recovery, heat pump dehumidification and other systems.

[0031] As one implementation method, a mesh conveyor belt is installed on the belt dryer 2 to support livestock and poultry manure. An air distribution plate with multiple through holes is installed at the air outlet of the air inlet. The air distribution plate is located at the bottom of the mesh conveyor belt. The air distribution plate diverts and diffuses the hot air entering the drying chamber through the multiple through holes, so that the airflow changes from a concentrated jet to a uniformly distributed multi-stream airflow, avoiding excessive local wind speed or uneven temperature. After being rectified by the air distribution plate, the hot air passes through the mesh conveyor belt and the manure layer it carries from bottom to top, forming a through-flow heat exchange with the material, which significantly increases the contact area and penetration depth between the hot air and the manure, and improves the moisture evaporation efficiency.

[0032] As one implementation method, the diameter of the air distribution disc is greater than or equal to the width of the mesh conveyor belt, that is, the coverage width of the through holes on the air distribution disc is greater than or equal to the width of the mesh conveyor belt. Since the distribution width of the through holes on the air distribution disc is not less than the width of the conveyor belt, the hot air can be distributed with a consistent wind speed and volume throughout the entire cross-section of the conveyor belt after passing through the air distribution disc. This avoids the problem of insufficient airflow and incomplete drying of the material on both sides of the conveyor belt under the traditional narrow-width air distribution method. At the same time, this "wide-width air distribution" structure allows the manure layer at any position on the conveyor belt to receive an equal amount of hot air penetration, which significantly improves the uniformity and consistency of the drying of the whole machine and prevents the "drying gradient" phenomenon of the middle being too dry and the sides still wet. In addition, this design also reduces the requirements for the alignment accuracy of the conveyor belt, simplifies the installation and debugging difficulty, and does not require the air distribution disc to be replaced when the width specification of the conveyor belt is upgraded, thus enhancing the versatility and expandability of the equipment.

[0033] As one implementation method, the air outlet is connected to the exhaust gas treatment unit. During the drying process, the hot air carries a large amount of water vapor, ammonia, hydrogen sulfide and volatile organic compounds, which are odorous components, after passing through the manure layer. If directly discharged into the atmosphere, it will cause air pollution to the farm and the surrounding environment. By connecting the air outlet to the exhaust gas treatment unit, all exhaust gases must be purified (such as chemical washing, biological filter bed, activated carbon adsorption or photocatalytic oxidation), effectively removing harmful substances and odorous components, and ensuring that the exhaust gases meet environmental protection standards.

[0034] The present invention also discloses a low-temperature drying method for organic solid waste composite heat source. Using the organic solid waste composite heat source low-temperature drying device described above, when it is spring or rainy in summer, the control system 15 controls the first air door 10 and the second air door 9 to close and the third air door 4 to open. The heat pump unit 6 dehumidifies and heats the ambient air to dry the livestock and poultry manure. The gas in the chicken house is discharged through the fourth air door 11. During autumn and winter, the control system 15 controls the first air door 10 to open, and the second air door 9, the fourth air door 11 and the third air door 4 to close, so that the air discharged from the chicken house dries the livestock and poultry manure. During non-rainy summer days, the control system 15 controls the first damper 10 and the third damper 4 to close, and the second damper 9 to open, allowing the livestock and poultry manure to be dried directly through ambient air. The gas inside the chicken house is discharged through the fourth damper 11.

[0035] The following are the specific implementation methods: During periods of high humidity in spring (plum rain season) or rainy weather in summer, when the ambient temperature is between 20℃ and 35℃ and the air humidity is above 70% (absolute humidity above 0.01 kg / kg), heat pump drying is used to improve the drying rate of organic solid waste. Air from the chicken house is directly discharged sequentially through exhaust fan 13, heat collection duct 12, and the fourth damper 11. The control system 15 obtains temperature and humidity parameters from the ambient temperature and humidity sensor 16 and determines whether the input values ​​are within the preset parameters: temperature (15-25℃), humidity (70-100%). The second damper 9 and the first damper 10... When the fourth damper 11 is closed, the heat pump unit 6 is started. Fresh ambient air enters the heat pump unit 6 through the air inlet 7, first passing through the evaporator to cool down to the dew point to remove some moisture, and then passing through the condenser to heat up to 20℃-40℃. At this time, the relative humidity of the heated air drops to below 30% (absolute humidity is below 0.008kg / kg). The air then passes through the third damper 4 and directly enters the belt dryer 2 to dry the organic solid waste. The dried exhaust gas is discharged through the third induced draft fan 3. Using this drying mode, organic solid waste with a moisture content of about 70% can be dried to below 25% within 30 hours.

[0036] In autumn and winter, the ambient temperature is between 5℃ and 20℃ and the relative humidity is below 60% (absolute humidity is below 0.005kg / kg). The air discharged from the chicken house ventilation (temperature 18℃-28℃) is used as a heat source to directly dry organic solid waste. The fourth air door 11, the second air door 9 and the third air door 4 are closed, and the first air door 10 is opened. The air from the chicken house ventilation passes through the heat collection air duct 12, the first air door 10 and the dryer air inlet air duct 17, and enters the belt dryer 2 for low-temperature drying of organic solid waste. The dried exhaust gas is discharged through the third exhaust fan 3. Using this drying mode, organic solid waste with a moisture content of about 70% can be dried to below 25% within 48 hours.

[0037] In summer, the ambient temperature is high, ranging from 30℃ to 40℃, with relative humidity between 50% and 65%. After the chicken house adopts water curtain evaporative cooling, the relative humidity of the ventilation exceeds 70%. Ambient air is used directly as the drying air to dry organic solid waste. The ventilation air in the chicken house is directly discharged through exhaust fan 13, heat collection duct 12, and fourth air door 11. The third air door 4 and the first air door 10 are closed. Ambient air is blown into the belt dryer 2 by the first exhaust fan 8 through the second air door 9 and the dryer inlet air duct 17. The dried exhaust gas is discharged through the third exhaust fan 3. Using this drying mode, organic solid waste with a moisture content of about 70% can be dried to below 25% within 30 hours.

[0038] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A low-temperature drying device for organic solid waste using a composite heat source, characterized in that, The system includes a livestock and poultry house (1), a heat collection duct (12) connected to the livestock and poultry house (1) via an exhaust fan (13), a dryer inlet duct (17) connected to the heat collection duct (12), a heat pump unit (6) connected to the dryer inlet duct (17) for dehumidifying and heating ambient air, and a drying chamber connected to the dryer inlet duct (17). A first damper (10) is provided between the heat collection duct (12) and the dryer inlet duct (17). A first induced draft fan (8) connected to the external environment is provided between the first air damper (10) and the air inlet duct (17) of the dryer. A second air damper (9) is provided between the first induced draft fan (8) and the air inlet duct (17) of the dryer. A third air damper (4) is provided between the heat pump unit (6) and the air inlet duct (17) of the dryer. The first air damper (10), the second air damper (9) and the third air damper (4) are used to realize the opening and closing of the corresponding connecting pipes.

2. The organic solid waste composite heat source low-temperature drying device according to claim 1, characterized in that, The heat collection duct (12) is provided with a fourth air door (11) at the end away from the first air door (10). The fourth air door (11) is used to realize the connection and disconnection between the livestock house (1) and the external environment.

3. The organic solid waste composite heat source low-temperature drying device according to claim 2, characterized in that, It also includes an ambient temperature and humidity sensor (16) installed in the external environment, an air inlet duct temperature and humidity sensor installed in the air inlet duct (17) of the dryer, and a control system (15). The control system (15) is electrically connected to the heat pump unit (6), the ambient temperature and humidity sensor (16), the air inlet duct temperature and humidity sensor, the first damper (10), the second damper (9), the third damper (4), and the fourth damper (11).

4. The organic solid waste composite heat source low-temperature drying device according to claim 1, characterized in that, The livestock shed (1) has a ventilation opening (14) at the end away from the exhaust fan (13).

5. The organic solid waste composite heat source low-temperature drying device according to claim 1, characterized in that, The heat pump unit (6) includes an air inlet (7), an evaporator, a condenser, and a second induced draft fan (5) arranged sequentially from the end away from the air inlet duct (17) of the dryer to the end near the air inlet duct (17) of the dryer.

6. The organic solid waste composite heat source low-temperature drying device according to claim 1, characterized in that, The drying chamber is equipped with a belt dryer (2) for supporting livestock and poultry manure. The drying chamber is equipped with an air inlet that is connected to the air inlet duct (17) of the dryer and an air outlet that is connected to the external environment through a third induced draft fan (3).

7. The organic solid waste composite heat source low-temperature drying device according to claim 6, characterized in that, The belt dryer (2) is equipped with a mesh conveyor belt, and the air outlet of the air inlet is equipped with an air distribution plate, which is located at the bottom of the mesh conveyor belt.

8. The organic solid waste composite heat source low-temperature drying device according to claim 7, characterized in that, The diameter of the air distribution disc is greater than or equal to the width of the mesh conveyor belt.

9. The organic solid waste composite heat source low-temperature drying device according to claim 6, characterized in that, The air outlet is connected to the waste gas treatment unit.

10. A method for low-temperature drying of organic solid waste using a composite heat source, employing the low-temperature drying apparatus for organic solid waste using a composite heat source as described in any one of claims 1-9, characterized in that, When it is rainy in spring or summer, the first damper (10) and the second damper (9) are closed, and the third damper (4) is opened. The heat pump unit (6) dehumidifies and heats the ambient air to dry the livestock and poultry manure. During autumn and winter, the first air door (10) is opened, and the second air door (9) and the third air door (4) are closed, so that the air discharged from the livestock and poultry house (1) dries the livestock and poultry manure. During non-rainy summer days, the first air door (10) and the third air door (4) are closed, and the second air door (9) is opened, allowing the livestock and poultry manure to be dried directly through ambient air.

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