Heat recovery device and method for kitchen waste biomass fermentation process

Abstract

The invention discloses a heat recovery device and method for a kitchen waste biomass fermentation process, the device comprises a drying system, a heat pump system and a heat recovery system, the device is divided into two working modes according to the oxygen content of air in a fermentation bin, closed circulation can recover heat in the whole fermentation and drying process, open circulation can provide an aerobic environment, and the heat recovery system can recover heat in the fermentation and drying process. And generating fermentation heat and effectively fermenting and drying to obtain the kitchen waste organic fertilizer. The double air ducts are adopted, the main air duct and the auxiliary air duct are arranged, the problem that a drying dead zone exists at the bottom of the fermentation bin is solved, the second fresh air branch and the auxiliary air duct share the same porous spraying structure, and the time for drying kitchen waste biomass into organic fertilizer and system energy consumption are greatly reduced.

Description

Technical Field

[0001] The present application relates to the field of fermentation and drying of food waste biomass, and in particular to a heat recovery device and method for a food waste biomass fermentation process. Background Art

[0002] The production of food waste biomass is increasing day by day, and how to properly handle it has become an important factor affecting social development. Traditional treatment methods such as landfill and incineration not only occupy a large amount of land resources, but also easily cause soil and air pollution. Relevant research has shown that drying pretreatment of food waste biomass can effectively reduce its moisture content and eliminate some microorganisms, reduce the load of subsequent treatment processes, and significantly improve the treatment efficiency of food waste biomass. Currently, commonly used drying methods include hot air drying and microwave drying, but these methods generally have the problems of high energy consumption and low efficiency. There is an urgent need for a more efficient and energy-saving drying method.

[0003] With the development and utilization of heat pump technology, heat pump drying technology, due to its unique drying principle, is both energy-efficient and environmentally friendly while ensuring the overall quality of the product. Through a reverse Carnot cycle, heat pumps can consume a portion of high-grade heat sources, absorb heat energy from the surrounding environment, and release this heat, along with the heat energy converted from the consumed high-grade energy, to the working fluid requiring heating. Heat pumps can serve as both a heat source for drying food waste biomass and remove moisture from it, achieving rapid drying and dehumidification. Using heat pumps to dry food waste biomass offers significant advantages, including high controllability, harmless treatment, and the ability to reuse the dried product as fertilizer.

[0004] Composting refers to the process of using the metabolic functions of microorganisms under aerobic conditions to decompose the organic matter in food waste biomass, converting it into stable humus-like substances. The final product can be used as fertilizer. As one of the current food waste biomass resource utilization technologies, aerobic composting not only solves environmental pollution problems but also recycles resources, which is why it is widely used. However, composting fermentation takes a long time and it is difficult to control the parameters of the process well. Therefore, a heat pump system is used to generate high-temperature, low-humidity air to dry the food waste biomass. Under aerobic fermentation, the heat pump drying system can effectively control the parameters of the food waste biomass drying process and accelerate the acquisition of the dried product food waste organic fertilizer.

[0005] Patent CN115371401A discloses a garbage drying device and method. This device removes moisture from the garbage through the combined action of a preheating chamber and a drying chamber. While this patent can remove moisture from the garbage, it does not utilize a heat pump system as a heat source for drying and dehumidification. Furthermore, the drying chamber is small, resulting in a small amount of garbage dried at one time and low drying efficiency.

[0006] Patent CN215217111U describes a kitchen waste drying system that uses solar energy and a heat pump to dry kitchen waste biomass. While this patent utilizes a heat pump system to dry kitchen waste biomass, the system requires a large floor space, significantly limiting its implementation.

[0007] Therefore, there is currently a lack of a heat recovery device and method for the food waste biomass fermentation and drying process. Summary of the Invention

[0008] The embodiments of the present application provide a heat recovery device and method for a food waste biomass fermentation and drying process, which is used to solve the technical problems of the existing food waste biomass fermentation and drying process, such as small amount of dried waste per unit area, high energy consumption, and low drying efficiency.

[0009] In a first aspect of the present application, a heat recovery device for a food waste biomass fermentation and drying process is provided, the device comprising a drying system, a heat pump system, and a heat recovery system, wherein: The drying system includes a fermentation bin with a U-shaped cross-section and a closed upper opening, wherein the upper area inside the fermentation bin is a main air duct, and a main air duct air inlet and a main air duct air outlet are respectively provided on the fermentation bin walls at both ends in the longitudinal direction of the main air duct; A partition with an inverted U-shaped cross section is provided in the fermentation bin below the main air duct. The inverted U-shaped partition is arranged along the length of the main air duct and is spaced apart from the side walls and bottom wall of the fermentation bin. The inverted U-shaped partition is provided with a through hole penetrating the inner and outer areas of the inverted U-shaped partition on one side of the main air duct. A stirring rod and an oxygen content meter are provided in the inner cavity area of ​​the fermentation bin surrounded by the inverted U-shaped partition. A first air inlet of the auxiliary air duct and a second air inlet of the auxiliary air duct are provided on the fermentation bin walls at both ends in the length direction of the main air duct, an auxiliary air duct pipe is provided inside the inverted U-shaped partition, wherein an auxiliary air duct main pipe connecting the first air inlet of the auxiliary air duct and the second air inlet of the auxiliary air duct is provided in the middle of the upper edge of the inverted U-shaped partition, and a plurality of auxiliary air duct branch pipes are provided inside the two side areas of the inverted U-shaped partition, one end of which is opened to be connected to the auxiliary air duct main pipe and the other end of which is opened to the opening located at the bottom of the inverted U-shaped partition, and the auxiliary air duct branch pipes are distributed at intervals along the length direction of the main air duct; The drying system further includes an air inlet duct and an air outlet duct, the air inlet duct including a circulating air branch, a first fresh air branch, and a second fresh air branch, the circulating air branch and the first fresh air branch being connected in parallel and then divided into two branches and connected to the main air duct inlet and the first air inlet of the auxiliary air duct respectively, and the second fresh air branch being connected to the second air inlet of the auxiliary air duct; the air outlet duct includes a circulating air branch and an exhaust branch connected in parallel, wherein the exhaust branch leads to the outside; The heat pump system includes a first heat exchanger, a first condenser, a second condenser, and a third condenser. The circulating air branch is sequentially connected in series with the first heat exchanger and the first condenser and then merges with the first fresh air branch. The working medium flow channel of the heat pump system is connected in series with the first heat exchanger, the first condenser, the second condenser, and the third condenser to form a cycle, and a working medium switching branch is connected in parallel to the second condenser. The second condenser is arranged on the first fresh air branch. The first fresh air branch, the second fresh air branch, in front of the first air inlet of the auxiliary air duct, the exhaust branch, between the first condenser and the second condenser, and the working medium switching branch are all provided with switches; The heat recovery system includes a third condenser and a second heat exchanger. The working fluid flow path of the heat pump system is connected to the first heat exchanger after passing through the third condenser. One heat exchange pipeline in the second heat exchanger is set on the second fresh air branch and the other is set on the exhaust branch.

[0010] Furthermore, at least two thermometers are provided in the fermentation bin, one of which is provided in the inner cavity area surrounded by the inverted U-shaped partition and close to the main air duct, and the other is provided near the bottom of the fermentation bin.

[0011] Furthermore, air volume meters are provided on the first fresh air branch, the second fresh air branch, the exhaust branch, and in front of the first air inlet of the auxiliary air duct.

[0012] Furthermore, the first heat exchanger is a fin-tube evaporative heat exchanger.

[0013] Furthermore, the first condenser and the second condenser are heat pump air-cooled condensers.

[0014] Furthermore, the third condenser is a water-cooled condenser.

[0015] Furthermore, the line connecting the main air duct air inlet and the main air duct air outlet is perpendicular to the U-shaped cross-section of the fermentation bin.

[0016] A second aspect of the present application provides a method for fermentation using the apparatus described in the first aspect of the present application, wherein when the oxygen content in the fermentation chamber is lower than the critical oxygen content, the second fresh air branch is opened, the first air inlet of the auxiliary air duct is closed, the passage between the first condenser and the second condenser is opened, the working medium switching branch is closed, and the exhaust branch is opened; When the oxygen content in the fermentation bin is higher than or equal to the critical oxygen content, the second fresh air branch is cut off, the first air inlet of the auxiliary air inlet is opened, the passage between the first condenser and the second condenser is cut off, the working medium switching branch is opened, and the exhaust branch is cut off.

[0017] Furthermore, when the oxygen content in the fermentation chamber is higher than or equal to the critical oxygen content, by monitoring the real-time temperature difference between the upper and lower layers in the fermentation chamber ∆T=T1-T2, the main air duct air volume Q is dynamically adjusted according to the following formula: 主 And auxiliary air duct air volume Q 底 distribute: , where T1 is the real-time temperature of the upper part of the inner cavity area surrounded by the inverted U-shaped partition, and T2 is the real-time temperature of the lower part of the inner cavity area surrounded by the inverted U-shaped partition; A 主 The cross-sectional area of ​​the main air duct, A 底 It is the cross-sectional area of ​​the inner cavity area surrounded by the inverted U-shaped partition.

[0018] Furthermore, when the oxygen content of the air in the fermentation chamber is lower than the critical oxygen content, the air volume of the exhaust branch is kept equal to the sum of the air volume of the first fresh air branch and the air volume of the second fresh air branch; According to the ratio A of the real-time oxygen content in the fermentation chamber to the critical oxygen content, the air volume of the first fresh air branch and the second fresh air branch is adjusted to the sum of the air volumes of the basic fresh air volume 1+A, where the basic fresh air volume ,in, is the fresh air oxygen concentration, is the critical oxygen content in the fermentation chamber, is the oxygen consumption rate per unit mass of kitchen waste biomass, It is the mass of kitchen waste biomass in the fermentation bin. Beneficial effects

[0019] As can be seen from the above technical solutions, the technical solution of the present invention provides a heat recovery device and method for a food waste biomass fermentation process, which has the following beneficial effects compared to the prior art: (1) A heat pump system was used to discharge condensed water through a fin-tube evaporative heat exchanger, achieving efficient dehumidification of kitchen waste biomass. The system was divided into two working modes according to the oxygen content of the air in the fermentation chamber. The closed cycle could recover the heat during the entire fermentation and drying process, while the open cycle could provide an aerobic environment, generate fermentation heat, and effectively ferment and dry the kitchen waste into organic fertilizer.

[0020] (2) The present invention adopts a dual air duct, setting up a main air duct and an auxiliary air duct to solve the problem of a drying "dead zone" at the bottom of the fermentation bin. In order to allow the kitchen waste biomass at the bottom to be effectively aerobically fermented and dried using the exhaust heat, a second fresh air branch is set up, sharing the same multi-porous injection structure with the auxiliary air duct, which greatly reduces the time for drying the kitchen waste biomass into organic fertilizer and the energy consumption of the system.

[0021] (3) By installing a stirring device in the fermentation chamber, the contact area between the kitchen waste biomass and the high-temperature and low-humidity air can be increased, thereby accelerating the dehumidification effect of the kitchen waste biomass. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings: Figure 1 Schematic diagram of a heat recovery device for a food waste biomass fermentation process according to an embodiment of the present invention.

[0023] Figure 2 This is a schematic cross-sectional view of a fermentation bin according to an embodiment of the present invention.

[0024] In the figures, the meanings of the reference numerals are as follows: 1. Filter; 2. Fan I; 3. First heat exchanger; 4. Compressor; 5. First condenser; 6. Second condenser; 7. Third condenser; 8. High-pressure liquid storage tank; 9. Expansion valve; 10. Stop valve I; 11. Stop valve II; 12. Air valve I; 13. Air valve II; 14. Air valve III; 15. Air valve IV; 16. Water pump; 17. Water tank; 18. Fan II; 19. Second heat exchanger; 20. Fermentation bin; 21. Motor; 22. Drive shaft; 23. Main air duct; 24. Auxiliary air duct pipeline; 25. First fresh air branch; 26. Second fresh air branch; 27. Exhaust air branch; 28. Circulating air branch; 29. ​​First air inlet of auxiliary air duct; 30. Second air inlet of auxiliary air duct; 31. Multi-hole injection nozzle. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, 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, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0028] To address the long fermentation and drying time and energy consumption associated with converting food waste biomass into organic fertilizer, as well as the presence of a drying "dead zone" at the bottom of the fermentation chamber 20, embodiments of the present application provide a heat recovery device and method for a food waste biomass fermentation process. The food waste biomass is fermented, the moisture content of the circulating air is reduced by a heat pump system, and the food waste biomass is aerobically dried by a drying system, with the heat generated during the fermentation and drying process being recovered.

[0029] like Figure 1 As shown in the figure, a heat recovery device for a food waste biomass fermentation process according to an embodiment of the present application is provided. Figure 1 It can be seen that the heat recovery device for the food waste biomass fermentation process includes a drying system, a heat pump system and a heat recovery system, wherein: The drying system, combined Figure 2 As shown, it includes a fermentation bin 20 with a U-shaped cross section and a closed upper opening. The upper area inside the fermentation bin 20 is a main air duct 23. The walls of the fermentation bin 20 at both ends of the length direction of the main air duct 23 are respectively provided with Figure 1 The main air duct inlet on the left and Figure 1 The main air duct outlet on the right side. The line between the main air duct inlet and the main air duct outlet is perpendicular to the U-shaped cross-section of the fermentation bin 20.

[0030] A partition with an inverted U-shaped cross section is provided in the fermentation bin 20 below the main air duct 23. The kitchen waste biomass is placed in the area surrounded by the inverted U-shaped partition. The inverted U-shaped partition is arranged along the length of the main air duct 23 and is spaced apart from the side walls and bottom wall of the fermentation bin 20. The inverted U-shaped partition is provided with a through hole that penetrates the inner and outer areas of the inverted U-shaped partition on one side of the main air duct 23, so that the air flowing through the main air duct 23 above it can carry away the heat and water vapor generated by the biomass in the area surrounded by the inverted U-shaped partition through the through hole. A stirring rod and an oxygen content meter are provided in the inner cavity area of ​​the fermentation bin 20 surrounded by the inverted U-shaped partition. Specifically, a transmission shaft 22 is arranged in the center of the inner cavity area of ​​the fermentation bin 20 surrounded by the inverted U-shaped partition, parallel to the length of the main air duct 23, and is driven by a motor 21. A plurality of stirring rods are fixedly connected to the transmission shaft 22. The driving shaft 22 drives the stirring rod to stir the kitchen waste biomass, thereby increasing the contact area between the kitchen waste biomass and the high-temperature and low-humidity air, thereby accelerating the dehumidification effect of the kitchen waste biomass drying process.

[0031] The walls of the fermentation bin 20 at both ends of the main air duct 23 in the longitudinal direction are provided with Figure 1 The first air inlet 29 of the auxiliary air duct on the left and the Figure 1 The auxiliary air duct second air inlet 30 on the right side is provided with an auxiliary air duct 24 inside the inverted U-shaped partition, wherein an auxiliary air duct main pipe is provided in the middle of the upper edge of the inverted U-shaped partition, connecting the auxiliary air duct first air inlet 29 and the auxiliary air duct second air inlet 30. A plurality of auxiliary air duct branch pipes are provided inside the two side areas of the inverted U-shaped partition, one end of which is connected to the auxiliary air duct main pipe and the other end of which is opened at the opening at the bottom of the U-shaped partition. The auxiliary air duct branch pipes are spaced along the length of the main air duct to form a multi-porous injection port 31 at the bottom of the fermentation bin 20. Air outside the fermentation bin 20 can be introduced through the auxiliary air duct first air inlet 29 or the auxiliary air duct second air inlet 30 and flow along the auxiliary air duct, specifically first entering the auxiliary air duct main pipe, then entering the auxiliary air duct branch pipe, and finally flowing into the bottom of the fermentation bin 20 from the multi-porous injection port 31 of the auxiliary air duct branch pipe located near the bottom of the inverted U-shaped partition, thereby drying the kitchen waste biomass from the bottom, avoiding the existence of a drying "dead zone" at the bottom. The gas at the bottom will flow from bottom to top through the gap between the inverted U-shaped partition and the wall of the fermentation chamber 20 into the main air duct 23 and out of the fermentation chamber 20 from the air outlet of the main air duct 23.

[0032] The drying system also includes an air inlet and outlet duct. The air inlet duct includes a circulating air branch 28, a first fresh air branch 25, and a second fresh air branch 26. The circulating air branch 28 carries gas that flows out of the fermentation chamber 20 and returns to the fermentation chamber 20, while the first fresh air branch 25 and the second fresh air branch 26 carry fresh air introduced from outside the fermentation chamber 20. The circulating air branch 28 and the first fresh air branch 25 are connected in parallel and then split into two branches, connected to the main air duct inlet and the first air inlet 29 of the auxiliary air duct. The second fresh air branch 26 is connected to the second air inlet 30 of the auxiliary air duct. The outlet duct includes the circulating air branch 28 and an exhaust air branch 27 connected in parallel, with the exhaust air branch 27 leading to the outside. Air volume meters are installed on the first fresh air branch 25, the second fresh air branch 26, the exhaust air branch 27, and in front of the first air inlet 29 of the auxiliary air duct. Through the connection relationship between the above-mentioned air paths, the source of air entering the fermentation bin 20 can be selected according to needs, and the air volume can also be precisely controlled, so as to better adapt to the current environment in the fermentation bin 20 and improve drying efficiency.

[0033] The heat pump system includes a first heat exchanger 3, a first condenser 5, a second condenser 6, and a third condenser 7. The circulating air branch is connected in series with the first heat exchanger 3 and the first condenser 5, and then merges with the first fresh air branch 25. Specifically, the outlet of the first heat exchanger 3 is connected to a compressor 4, and the outlet of the compressor 4 is connected to the first condenser 5. The working medium flow path of the heat pump system is connected in series with the first heat exchanger 3, the first condenser 5, the second condenser 6, and the third condenser 7 to form a circulation, and a working medium switching branch is connected in parallel to the second condenser 6. The second condenser 5 is arranged on the first fresh air branch 25 to heat the fresh air on the first fresh air branch 25. The first heat exchanger 3 is a fin-tube evaporative heat exchanger. The refrigerant exchanges heat with the air through the fin-tube heat exchanger, increasing the contact area between the heat exchanger and the heat exchange medium and improving the heat exchange capacity. The refrigerant enters the fin-tube evaporative heat exchanger to absorb heat, and the generated condensed water flows out through the water tray below the fin-tube evaporative heat exchanger. Its evaporation temperature is lower than the dew point temperature of the circulating air at the main air duct outlet of the fermentation bin 20, and it can cool and dehumidify the high-temperature and high-humidity gas coming out of the fermentation bin 20, thereby achieving the purpose of rapid drying of kitchen waste biomass.

[0034] The first condenser 5 and the second condenser 6 are heat pump air-cooled condensers, and the third condenser 7 is a water-cooled condenser. The above heat pump system cooperates with the drying system to fully utilize the waste heat for a second time, thereby improving the heat exchange efficiency.

[0035] The first fresh air branch 25, the second fresh air branch 26, in front of the first air inlet 29 of the auxiliary air duct, the exhaust branch 27, between the first condenser 5 and the second condenser 6, and the working medium switching branch are all equipped with switches. Specifically, the first fresh air branch 25 is equipped with an air valve II 13, the second fresh air branch 6 is equipped with an air valve III 14, the first air inlet 29 of the auxiliary air duct is equipped with an air valve IV 15, the exhaust branch 27 is equipped with an air valve I 12, a stop valve I 10 is provided between the first condenser 5 and the second condenser 6, and the working medium switching branch is equipped with a stop valve II 11. Through the combination of switches, the flow of air and working medium is carried out in the required direction. Preferably, the switches can be adjusted in opening degree, which can further refine the flow control to adapt to the real-time status in the fermentation bin 20.

[0036] The heat recovery system includes a third condenser 7 and a second heat exchanger 19. The working fluid flow path of the heat pump system is connected to the first heat exchanger 3 after passing through the third condenser 7. Specifically, the third condenser 7 is a water-cooled condenser. The outlet of the third condenser 7 is connected to a high-pressure liquid reservoir 8, the outlet of the high-pressure liquid reservoir 8 is connected to an expansion valve 9, and the outlet of the expansion valve 9 is connected to the inlet of the first heat exchanger 3. At the same time, the water outlet of the third condenser 7 is connected to the water inlet of a water tank 17, the water outlet of the water tank 17 is connected to the suction port of a water pump 16, and the outlet of the water pump 16 is connected to the water inlet of the condenser. Through the external water tank 17 and the water pump 16, the water passing through the third condenser is heated by the working fluid passing through it, thereby recovering heat and converting it into hot water for supply. The heat exchange pipeline in the second heat exchanger 19 is arranged on the second fresh air branch 26 and the other on the exhaust branch 27. The second heat exchanger 19 is used to recover waste heat from the exhaust air to heat the fresh air. Specifically, the second heat exchanger 19 is a fin-tube heat exchanger, which is connected in series between the exhaust duct 27 and the auxiliary fresh air duct 26, and uses the waste heat of the exhaust air to heat the fresh air to 50°C~70°C.

[0037] In specific implementation, a filter 11 is provided at one end of the suction port of the fan 12 for removing particulate matter in the circulating air.

[0038] In some preferred embodiments, in order to better control the ventilation volume of the two channels, at least two thermometers are provided in the fermentation bin 20, such as Figure 1 As shown in FIG, one thermometer T1 is located in the inner cavity area surrounded by the inverted U-shaped partition and close to the main air duct, and the other thermometer T2 is located near the bottom of the fermentation bin 20. The two thermometers measure the temperature of the two channels after ventilation, and the temperature difference determines whether the air volume matching of the two channels is appropriate.

[0039] In a specific implementation, a heat recovery method is used for the fermentation process of kitchen waste biomass. 5% of fermentation bacteria are added to the fermentation bin 20. Under the high-efficiency dehumidification of the heat pump system, the high-moisture content kitchen waste biomass is fermented and dried into kitchen waste organic fertilizer with a moisture content of less than 15%. Depending on the actual situation, the feeding method of the kitchen waste biomass adopts one or more combinations of continuous or intermittent methods, and the fermentation and drying cycle of the kitchen waste biomass is 24 hours.

[0040] In certain preferred embodiments, varying oxygen levels within the fermentation chamber 20 can affect the fermentation process. Low oxygen levels, such as those below a critical oxygen level of 10%, are detrimental to fermentation. Therefore, during use, the aforementioned device simultaneously draws air from two channels to dry the fermentation chamber 20. The air sources in these channels are adjusted based on varying oxygen levels within the fermentation chamber 20. This adjustment is achieved by cooperating with switches in each air channel.

[0041] When the oxygen content in fermentation bin 20 falls below the critical oxygen content, the drying system exhausts some of the high-temperature, high-humidity air and introduces fresh air to replenish it. This opens the second fresh air branch 26, blocks the first air inlet 29 of the auxiliary air duct, opens the passage between first condenser 5 and second condenser 6, blocks the working medium switching branch, and opens the exhaust branch 27. This opens air valve III 14 and closes air valve IV 15. The heat pump system opens shutoff valve I 10 and closes shutoff valve II 11. In this case, the circulating air output by fan I2 only enters the upper layer of the fermentation bin 20 through the main air duct 23; the second fresh air branch 26 is opened, and the fresh air output by fan II18 is heated by the second heat exchanger 19, and then enters the bottom layer of the fermentation bin 20 through the auxiliary air duct 24, which can not only provide oxygen to the "dead zone" at the bottom of the fermentation bin 20 but also dry the kitchen waste biomass; part of the high-temperature and high-humidity air discharged from the fermentation bin 20 is discharged through the exhaust duct 27, and part of it is used as circulating air for cooling and dehumidification through the first heat exchanger 3; the circulating air after cooling and dehumidification is heated by the heat pump air-cooled condenser I5 to raise the temperature to 70°C; the fresh air is heated by the second condenser 6, mixed with the circulating air, and then sent to the fermentation bin 20 to dry the kitchen waste biomass; the heat pump system is connected to an external water source, and the water is heated by the third condenser 7 to produce domestic hot water.

[0042] When the oxygen content in fermentation bin 20 is above or equal to the critical oxygen content, the high-temperature, high-humidity air in the drying system is not exhausted, and fresh air is not required. Therefore, the second fresh air branch 26 is closed, the auxiliary air inlet first inlet 29 is opened, the passage between the first condenser 5 and the second condenser 6 is blocked, the working medium switching branch is opened, and the exhaust branch 27 is closed. No fresh air is supplied, and air valve IV 15 is opened and air valve III 14 is closed. The heat pump system opens shutoff valve II 11, closes shutoff valve I 10, and closes valve 12. In this case, the circulating air output by fan I 2 is split into two paths: the first path enters the upper level of fermentation bin 20 through the main air duct 23, and the second path enters the lower level of fermentation bin 20 through the auxiliary air duct 24. All the high-temperature, high-humidity air discharged from fermentation bin 20 is used as circulating air and cooled and dehumidified by the first heat exchanger 3. After cooling and dehumidification, the circulating air is heated by the first condenser I 5, raising its temperature to 70°C. The heat pump system connects to an external water source, which is heated by the third condenser 7 to produce domestic hot water.

[0043] In the above embodiment, when the oxygen content in the fermentation chamber 20 is higher than or equal to the critical oxygen content, the real-time temperature difference between the upper and lower layers in the fermentation chamber 20 is further monitored ∆T=T1-T2, and the main air duct air volume Q is dynamically adjusted according to the following formula: 主 And auxiliary air duct air volume Q 底 distribute: , where T1 is the real-time temperature of the upper portion of the inner cavity area surrounded by the inverted U-shaped partition, and T2 is the real-time temperature of the lower portion of the inner cavity area surrounded by the inverted U-shaped partition, which are specifically measured by thermometers set at corresponding positions; A 主 The cross-sectional area of ​​the main air duct, A 底 It is the cross-sectional area of ​​the inner cavity area surrounded by the inverted U-shaped partition.

[0044] The above control method can automatically adjust the air volume of the main air duct and the auxiliary air duct according to the temperature, so that the upper and lower areas tend to have the same temperature. Figure 1 As shown, an air volume meter G4 is provided next to the air valve IV 15 , which controls the opening of the air valve IV 15 by detecting the air volume passing through the auxiliary air duct main 24 .

[0045] For example, when ∆T is greater than 0, such as ∆T>5℃, the proportion of auxiliary duct air volume is relatively increased to enhance bottom heat exchange; when ∆T is less than 0, such as ∆T<-2℃, the proportion of auxiliary duct air volume is relatively reduced to avoid overcooling.

[0046] In the above embodiment, when the oxygen content of the air in the fermentation bin 20 is lower than the critical oxygen content, although fresh air needs to be added, the air volume of the exhaust branch needs to be kept equal to the sum of the air volume of the first fresh air branch 25 and the air volume of the second fresh air branch 26. Specifically, the corresponding air valves are measured and adjusted by the air volume meter G2 on the first fresh air branch 25, the air volume meter G3 on the second fresh air branch 16, and the air volume meter G1 on the exhaust branch 27 to keep the total air volume passing through the fermentation bin 20 consistent.

[0047] Specifically, when adjusting, it is also necessary to consider calculating the fresh air volume according to the oxygen content. Specifically, the oxygen content is measured by an oxygen content meter, and according to the ratio A of the real-time air oxygen content in the fermentation bin 20 to the critical oxygen content, the air volume of the first fresh air branch 25 and the second fresh air branch 26 is adjusted to be the sum of the air volumes of the basic fresh air volume 1+A, where the basic fresh air volume ,in, Fresh air oxygen concentration (unit: m 3 / h), is the critical oxygen content in the fermentation chamber 20, is the oxygen consumption rate per unit mass of kitchen waste biomass (in g / (kg·h)), is the mass of the kitchen waste biomass in the fermentation bin 20 (in kg).

[0048] Compared to the prior art for drying food waste biomass, the above-described device utilizes heat pump drying technology, utilizing a fin-and-tube heat exchanger within the heat pump system for cooling and dehumidification, achieving rapid food waste drying. When the oxygen content in the fermentation chamber 20 exceeds the critical oxygen content, the high-temperature, high-humidity air in the drying system is entirely transferred through the first heat exchanger 3 for heat exchange. This closed cycle recycles all heat from the fermentation and drying process, increasing heat recovery. When the oxygen content is below the critical oxygen content, a three-stage condensing heat exchanger is used to first heat the circulating air to the required temperature for drying the food waste biomass. Secondly, aerobic drying of the food waste biomass is required, utilizing heat absorbed from the fermentation and drying process and the work of the compressor 4 to heat the fresh air. Finally, excess heat is recovered by heating water through the third condenser 7. This improves the heat release efficiency of the heat pump, ensures the stability of the drying system, and significantly reduces the drying system's electrical energy consumption, significantly accelerating the efficiency of food waste drying.

[0049] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A heat recovery device for a food waste biomass fermentation process, characterized in that: The device includes a drying system, a heat pump system and a heat recovery system, wherein: The drying system includes a fermentation bin with a U-shaped cross-section and a closed upper opening, wherein the upper area inside the fermentation bin is a main air duct, and a main air duct air inlet and a main air duct air outlet are respectively provided on the fermentation bin walls at both ends in the longitudinal direction of the main air duct; A partition with an inverted U-shaped cross section is provided in the fermentation bin below the main air duct. The inverted U-shaped partition is arranged along the length of the main air duct and is spaced apart from the side walls and bottom wall of the fermentation bin. The inverted U-shaped partition is provided with a through hole penetrating the inner and outer areas of the inverted U-shaped partition on one side of the main air duct. A stirring rod and an oxygen content meter are provided in the inner cavity area of ​​the fermentation bin surrounded by the inverted U-shaped partition. A first air inlet of the auxiliary air duct and a second air inlet of the auxiliary air duct are provided on the fermentation bin walls at both ends in the length direction of the main air duct, an auxiliary air duct pipe is provided inside the inverted U-shaped partition, wherein an auxiliary air duct main pipe connecting the first air inlet of the auxiliary air duct and the second air inlet of the auxiliary air duct is provided in the middle of the upper edge of the inverted U-shaped partition, and a plurality of auxiliary air duct branch pipes are provided inside the two side areas of the inverted U-shaped partition, one end of which is opened to be connected to the auxiliary air duct main pipe and the other end of which is opened to the opening located at the bottom of the inverted U-shaped partition, and the auxiliary air duct branch pipes are distributed at intervals along the length direction of the main air duct; The drying system further includes an air inlet duct and an air outlet duct, the air inlet duct including a circulating air branch, a first fresh air branch, and a second fresh air branch, the circulating air branch and the first fresh air branch being connected in parallel and then divided into two branches and connected to the main air duct inlet and the first air inlet of the auxiliary air duct respectively, and the second fresh air branch being connected to the second air inlet of the auxiliary air duct; the air outlet duct includes a circulating air branch and an exhaust branch connected in parallel, wherein the exhaust branch leads to the outside; The heat pump system includes a first heat exchanger, a first condenser, a second condenser, and a third condenser. The circulating air branch is sequentially connected in series with the first heat exchanger and the first condenser and then merges with the first fresh air branch. The working medium flow channel of the heat pump system is connected in series with the first heat exchanger, the first condenser, the second condenser, and the third condenser to form a cycle, and a working medium switching branch is connected in parallel to the second condenser. The second condenser is arranged on the first fresh air branch. The first fresh air branch, the second fresh air branch, in front of the first air inlet of the auxiliary air duct, the exhaust branch, between the first condenser and the second condenser, and the working medium switching branch are all provided with switches; The heat recovery system includes a third condenser and a second heat exchanger. The working fluid flow path of the heat pump system is connected to the first heat exchanger after passing through the third condenser. One heat exchange pipeline in the second heat exchanger is set on the second fresh air branch and the other is set on the exhaust branch.

2. The device according to claim 1, characterized in that At least two thermometers are arranged in the fermentation bin, one of which is arranged in the inner cavity area surrounded by the inverted U-shaped partition and close to the main air duct, and the other is arranged near the bottom of the fermentation bin.

3. The device according to claim 1, characterized in that Air volume meters are provided on the first fresh air branch, the second fresh air branch, the exhaust branch, and in front of the first air inlet of the auxiliary air duct.

4. The device according to claim 1, characterized in that The first heat exchanger is a fin-tube evaporative heat exchanger.

5. The device according to claim 1, characterized in that The first condenser and the second condenser are heat pump air-cooled condensers.

6. The device according to claim 1, characterized in that The third condenser is a water-cooled condenser.

7. The device according to claim 1, characterized in that The connecting line between the main air duct air inlet and the main air duct air outlet is perpendicular to the U-shaped cross-section of the fermentation bin.

8. A method for fermentation using the device according to any one of claims 1 to 7, characterized in that: When the oxygen content in the fermentation bin is lower than the critical oxygen content, the second fresh air branch is opened, the first air inlet of the auxiliary air duct is closed, the passage between the first condenser and the second condenser is opened, the working medium switching branch is closed, and the exhaust branch is opened; When the oxygen content in the fermentation bin is higher than or equal to the critical oxygen content, the second fresh air branch is cut off, the first air inlet of the auxiliary air inlet is opened, the passage between the first condenser and the second condenser is cut off, the working medium switching branch is opened, and the exhaust branch is cut off.

9. The method according to claim 8, characterized in that When the oxygen content in the fermentation chamber is higher than or equal to the critical oxygen content, the main air duct air volume Q is dynamically adjusted according to the following formula by monitoring the real-time temperature difference between the upper and lower layers in the fermentation chamber ∆T=T1-T2. 主 And auxiliary air duct air volume Q 底 distribute: , where T1 is the real-time temperature of the upper part of the inner cavity area surrounded by the inverted U-shaped partition, and T2 is the real-time temperature of the lower part of the inner cavity area surrounded by the inverted U-shaped partition; A 主 The cross-sectional area of ​​the main air duct, A 底 It is the cross-sectional area of ​​the inner cavity area surrounded by the inverted U-shaped partition.

10. The method according to claim 8, characterized in that: When the oxygen content of the air in the fermentation chamber is lower than the critical oxygen content, the air volume of the exhaust branch is kept equal to the sum of the air volume of the first fresh air branch and the air volume of the second fresh air branch; According to the ratio A of the real-time oxygen content in the fermentation chamber to the critical oxygen content, the air volume of the first fresh air branch and the second fresh air branch is adjusted to the sum of the air volumes of the basic fresh air volume 1+A, where the basic fresh air volume ,in, is the fresh air oxygen concentration, is the critical oxygen content in the fermentation chamber, is the oxygen consumption rate per unit mass of kitchen waste biomass, It is the mass of kitchen waste biomass in the fermentation bin.

Images