Drying system and drying method

Abstract

A drying system that can operate even during maintenance of a hot air generator using biomass fuel. [Solution] A drying treatment system 10 comprising a hot air generating unit 20 that generates hot air HA, and a drying unit 50 that dries a material to be processed UB derived from livestock excrement with the hot air while stirring, wherein the hot air generating unit has a first hot air generating device 21 that uses biomass fuel and a second hot air generating device 32 that uses fossil fuel, and the first hot air generating device and the second hot air generating device are each connected to the drying unit and are interconnected.

Description

Technical Field

[0001] The present invention relates to a system and method for drying a material to be treated derived from livestock excrement.

Background Art

[0002] Livestock excrement is generally treated together with bedding laid on the floor of a livestock house. The bedding is used for the purpose of improving the livability of livestock and absorbing excrement to improve the handling property of excrement. As the bedding, for example, dried hay, straws (wheat straws), sawdust, rice husks, etc. are used. Such bedding finishes its role when it absorbs the moisture of excrement and reaches a saturated state. For example, in a dairy cattle breeding facility, it reaches a saturated state in a few days. The used bedding in a saturated state needs to be properly treated. Patent Documents 1 and 2 disclose a bedding regeneration device that regenerates used bedding into bedding safe for livestock by drying it with hot air at a high temperature while stirring.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The bedding recycling apparatus described in Patent Documents 1 and 2 can use biomass fuel as fuel. However, if the hot air generator is not in operation due to maintenance or other reasons, the entire bedding recycling apparatus cannot be operated. Furthermore, unlike biomass power generation equipment that operates continuously for long periods, the drying of livestock waste such as used bedding is usually carried out only during the daytime, or at most for a few days. However, there is a problem that it takes time for the hot air generator to heat up, which shortens the effective operating time during which the drying process can actually be carried out.

[0005] The present invention has been made in consideration of the above, and aims to provide a drying system and method for a device and method for drying materials derived from livestock excrement, such as used bedding, which can be operated even during maintenance of a hot air generator using biomass fuel, and furthermore, can shorten the time during which drying cannot be performed when the hot air generator using biomass fuel is started up, thereby increasing the effective operating rate. [Means for solving the problem]

[0006] The drying system of the present invention comprises a hot air generating unit that generates hot air, and a drying unit that dries a material to be processed, derived from livestock excrement, with the hot air while stirring it. The hot air generating unit comprises a first hot air generating device that uses biomass fuel and a second hot air generating device that uses fossil fuel. The first hot air generator and the second hot air generator are each connected to the drying section and are interconnected.

[0007] Preferably, in the drying system described above, the second hot air generator is connected in series upstream of the first hot air generator and generates starting hot air to raise the temperature of the first hot air generator.

[0008] Preferably, in any of the above drying systems, the material to be processed includes used bedding containing livestock excrement.

[0009] Preferably, in any of the above drying systems, the material to be treated includes compost derived from livestock excrement.

[0010] Preferably, in any of the above drying systems, the first hot air generator is a fluidized bed type device.

[0011] Preferably, in any of the above drying systems, the first hot air generator has an auxiliary heating means downstream of the biomass fuel input section.

[0012] The drying method of the present invention comprises a hot air generation step of generating hot air using a first hot air generator, and a drying step of producing a processed product by drying a material to be processed from livestock excrement with the hot air while stirring it. The hot air generation step comprises a first step of generating hot air using an auxiliary heating means provided in the first hot air generator while sending starting hot air generated by a second hot air generator using fossil fuel to the first hot air generator to raise the temperature of the first hot air generator, and generating the hot air, and a second step of generating the hot air by burning biomass fuel in the first hot air generator while sending outside air to the first hot air generator.

[0013] Another drying method of the present invention comprises a hot air generation step of generating hot air, and a drying step of drying a material to be treated derived from livestock excrement with the hot air while stirring to produce a processed product. The hot air generation step is carried out by switching between a first hot air generation step of generating hot air using a first hot air generator that uses biomass fuel, and a second hot air generation step of stopping the first hot air generator and generating hot air using a second hot air generator that uses fossil fuel. [Effects of the Invention]

[0014] According to the drying system or method of the present invention, since both the first hot air generator and the second hot air generator are connected to the drying section, drying of the material to be processed in the drying section can be performed even when one of the hot air generators is being maintained or when the first hot air generator cannot be operated due to a shortage of biomass fuel. Furthermore, while it takes time to start up the first hot air generator using biomass fuel, since the first and second hot air generators are interconnected, the drying of the material to be processed in the drying section can be started while the second hot air generator is heating up the first hot air generator, thereby shortening the time from the start-up of the first hot air generator to the start of the drying process. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram showing the configuration of a drying system in one embodiment. [Figure 2] This is a schematic diagram showing the structure of a first hot air generator according to one embodiment. [Figure 3] A: Plan view, B: Side view of the drying drum in the drying section. [Figure 4] A: Side cross-sectional view showing the drum body; B-C: Schematic diagrams showing the position of the stirring blades. [Figure 5] This diagram shows the state of the valves and the flow of hot air between the first hot air generator, the second hot air generator, and the drying section. A: When hot air from the first hot air generator is supplied to the drying section, B: When hot air from the second hot air generator is supplied to the drying section. [Modes for carrying out the invention]

[0016] A first embodiment of the drying system and method of the present invention will be described with reference to Figures 1 to 5.

[0017] The objects of the drying treatment system and method of this embodiment are derived from livestock excreta, such as used bedding materials containing livestock excreta, compost obtained by fermenting livestock excreta, and organic substances including livestock excreta such as livestock excreta. In the following, the case of drying used bedding materials as the object to be treated will be described.

[0018] Used bedding material refers to bedding material that contains livestock manure as a result of use. For example, manure-containing bedding material taken out from a cowshed, etc., and dried manure-containing bedding material whose moisture has been evaporated by ventilation or sunlight, etc. are included. In addition, those obtained by mixing a moisture conditioner such as compost returned to manure-containing bedding material and sawdust, etc. for moisture adjustment are also included in the dried manure-containing bedding material. Generally, the moisture content of manure-containing bedding material is 85% - 99%, and the moisture content of dried manure-containing bedding material is 20% - 85%.

[0019] Referring to FIG. 1, the drying treatment system 10 is for drying used bedding material UB, and includes a hot air generating unit 20 that generates hot air HA, and a drying unit 50 that dries the used bedding material UB with the hot air HA while stirring it.

[0020] The hot air generating unit 20 has a first hot air generating device 21 and a second hot air generating device 32. The first hot air generating device 21 uses biomass fuel. The second hot air generating device 32 uses fossil fuel. The first hot air generating device 21 and the second hot air generating device 32 are each connected to the drying unit 50 and can supply hot air HA to the drying unit independently. Also, the first hot air generating device 21 and the second hot air generating device 32 are connected to each other.

[0021] Referring to Figure 5A, when valve 38 is closed and valves 36 and 37 are opened, a path is formed from the second hot air generator 32 through the first hot air generator 21 to the drying drum 51 of the drying section 50, allowing the hot air HA1 generated by the first hot air generator to be supplied to the drying section as hot air HA. At this time, when the first hot air generator 21 is started up, starting hot air SA is supplied from the second hot air generator 32 to the first hot air generator, and after the first hot air generator 21 has started up, the second hot air generator 32 is stopped and outside air OA is supplied to the first hot air generator. Further details will be described later.

[0022] Referring to Figure 5B, when valves 36 and 37 are closed and valve 38 is opened, a path is formed from the second hot air generator 32 directly to the drying drum 51, and the hot air HA2 generated by the second hot air generator can be supplied to the drying section as hot air HA. At this time, the first hot air generator 21 may be stopped.

[0023] Referring to Figures 1 and 2, the first hot air generator 21 has a shaft-shaped body, an air inlet 22 at the bottom, a fuel input 23 above it as a biomass fuel input bay, and an auxiliary burner (auxiliary heating means) 26 near the hot air outlet at the top. During steady-state operation, the first hot air generator 21 burns fuel supplied into the device from the fuel input bay 23 to heat the air introduced from the air inlet bay 22 and generate hot air HA1. The fuel used to generate the hot air HA1 is biomass fuel, and in this embodiment, processed material DB obtained by drying used bedding material UB is used as the biomass fuel.

[0024] The first hot air generator 21 is preferably a fluidized bed type device, which heats the air by flowing a heat transfer medium such as sand within the device. Fluidized bed type devices are energy efficient, and the temperature of the generated hot air HA1 tends to remain stable even if the moisture content of the fuel fluctuates.

[0025] Air is supplied to the air inlet 22 from the second hot air generator 32 to fluidize the heat transfer medium such as sand in the first hot air generator 21. When the first hot air generator 21 is started, the starting hot air SA generated by the second hot air generator 32 is supplied to the air inlet 22 in order to raise the temperature of the first hot air generator 21. During steady operation after the first hot air generator 21 has been heated, outside air OA is supplied to the air inlet 22 without being heated by the second hot air generator 32.

[0026] The fuel input unit 23 introduces fuel for generating hot air HA1 into the first hot air generator 21. Hereinafter, the fuel introduced from the fuel input unit 23 will be referred to as the main fuel. The main fuel burns in the first hot air generator, heating the air introduced from the air introduction unit 22 to generate hot air HA1. The fuel input unit 23 has an input hopper 24 and an input conveyor 25. The main fuel, after passing through the input hopper 24 and the input conveyor 25, is blown into the first hot air generator 21 using air from the suction blower 43 of the material transport unit 40.

[0027] Biomass fuels used as the main fuel include processed material DB obtained by drying used bedding material UB, as well as compost obtained by drying and fermenting livestock excrement. Preferably, the main fuel consists of processed material DB obtained by drying used bedding material and compost derived from livestock excrement, and more preferably consists of processed material DB obtained by drying used bedding material.

[0028] Dried used bedding material can be reused as bedding or fermented and used as compost. However, securing storage space for recycled bedding and compost, as well as the costs of transporting unused material off-site, pose problems, and there is a need for efficient methods to reduce their volume. By using dried material and compost derived from livestock waste as biomass fuel, carbon dioxide emissions can be reduced.

[0029] The main fuel may also contain other fuels, but since the processed material DB dried in the drying section 50 can be returned to the barn as recycled bedding, it is preferable to use a main fuel that does not contaminate the processed material DB even if the hot air HA comes into direct contact with the used bedding.

[0030] When processed material DB is used as the main fuel, the processed material DB may be stored after drying, or, more preferably, a portion of the processed material DB is transported from the drying unit 50 while the drying process is being carried out. The configuration of the processed material transport unit 40 that transports the processed material DB from the drying unit 50 will be described later.

[0031] The moisture content of the main fuel is preferably 45% or less, more preferably 40% or less, and particularly preferably 35% or less. The moisture content of the processed material DB of the used bedding processed in the drying section 50 is 10% to 50%, and the moisture content of the composted bedding is generally 10% to 50%. The drying system 10 of this embodiment can shorten the time from the start-up of the first hot air generator 21 to the start of the drying process, even when using fuel with such a high moisture content.

[0032] The auxiliary burner 26 is located downstream of the fuel input section 23 (upper side in Figure 2), preferably near the outlet of the first hot air generator 21. The auxiliary burner 26 is preferably a kerosene burner, supplied with kerosene fuel from the kerosene supply source 28 and outside air from the combustion fan 27.

[0033] The auxiliary burner 26 is used to heat the hot air HA1 when the temperature of the hot air HA1 decreases due to fluctuations in the moisture content of the main fuel during steady operation of the first hot air generator 21.

[0034] Furthermore, the auxiliary burner 26 is also used when starting the drying process system 10. When the first hot air generator 21 is heated up, the starting hot air SA introduced from the air inlet 22 loses heat to various parts of the first hot air generator and to heat transfer media such as sand, causing its temperature to drop. Therefore, the auxiliary burner can be used to heat the SA so that hot air HA1 at the required temperature can be generated from the first hot air generator.

[0035] In particular, when a fluidized bed type device is used as the first hot air generator 21, the temperature of the hot air HA1 is easily stabilized by the heat transfer medium with a large heat capacity, but there is a problem that it takes a long time to heat up. Even if the first hot air generator 21 is a fluidized bed type device, by using an auxiliary burner 26, it becomes possible to dry the used bedding material UB in the drying section 50 from an early stage of heating up the first hot air generator 21, without wasting time or fuel for heating up.

[0036] A cooling damper 29 is connected to the piping at the outlet of the first hot air generator 21. By opening the cooling damper 29 and drawing in outside air OA, the outside air OA can be mixed with the hot air HA1, thereby lowering the temperature of the hot air HA1. The cooling damper 29 is used to cool the hot air HA1 when the temperature of the hot air HA1 rises too high during steady operation of the first hot air generator 21, for example, when the moisture content of the main fuel becomes low due to fluctuations. When the temperature of the hot air HA1 is within a predetermined range, the cooling damper is kept closed.

[0037] The method for cooling the hot air HA1 is not limited to using a damper. For example, outside air OA may be drawn in using a fan and mixed with the hot air HA1. Alternatively, the hot air HA1 may be cooled by passing it through a heat exchanger with the outside air OA. Alternatively, the hot air HA1 may be cooled by passing it through a heat exchanger with a gas or liquid that is cooler than the hot air HA, other than outside air.

[0038] Referring to Figure 1, the second hot air generator 32 has a kerosene burner 33 as a heating means. The push fan 31 can send a portion of the incoming outside air OA to the combustion fan 34 of the kerosene burner 33. When the first hot air generator 21 is started, the kerosene burner 33 is supplied with kerosene fuel from the kerosene supply source 35 and outside air from the combustion fan 34, heating the air inside the second hot air generator 32 to generate starting hot air SA. The starting hot air SA is guided from the second hot air generator 32 to the air inlet 22 of the first hot air generator 21.

[0039] The fuel for the second hot air generator 32 is not limited to kerosene; various fossil fuels such as natural gas and liquefied petroleum gas can be used. By using fossil fuels, the second hot air generator 32 can heat up quickly and easily control the heat output.

[0040] During steady-state operation of the first hot air generator 21, when the kerosene burner 33 is not in use, the entire volume of outside air OA taken in by the push fan 31 is directed to the second hot air generator 32, and the outside air OA can be sent directly from the second hot air generator 32 to the first hot air generator 21 without being heated.

[0041] The drying unit 50 includes a drying drum 51, an input hopper 52 and input conveyor 53 for loading used bedding material UB into the drying drum, dust collectors 54 and 55 for removing powder and the like from the exhaust EA discharged from the drying drum 51, an induction fan 56 for drawing in the exhaust EA from the drying drum 51, and a processed material conveyor 57 for transporting the processed material removed from the drying drum 51.

[0042] Referring to Figures 3 and 4, the drying drum 51 has a cylindrical drum body (processing tank) 61 supported by a frame 62. The drum body 61 is installed at an angle such that the upstream end, i.e., the end into which the used bedding material UB is introduced, is higher than the downstream end, i.e., the end from which the processed material DB is removed. The shape and structure of the frame 62 are not particularly limited as long as it can support the drum body 61, and in particular, as long as it can support the drum body 61 at an angle such that the upstream end is higher than the downstream end.

[0043] The inclination angle of the drum body 61 is preferably 5 to 25 degrees, more preferably 10 to 20 degrees, and particularly preferably 12 to 18 degrees. If it is less than 5 degrees, the used bedding material UB that is put in tends to accumulate. If it is greater than 25 degrees, there is a risk that the used bedding material that is put in will not be able to be held inside the drum body 61 and dried sufficiently.

[0044] The length X of the drum body 61 is 1000mm to 3000mm, preferably 1500mm to 2100mm. The diameter Y of the drum body 61 is 210mm to 1500mm, preferably 500mm to 1000mm. The ratio of the diameter Y (Y / X) of the drum body 61 to the length X is 0.1 to 0.5, preferably 0.2 to 0.3.

[0045] The drum body 61 is equipped with an inlet 63 for used bedding material and a hot air inlet 64 for supplying hot air HA on the upper side near one end (upstream side). On the lower side near the other end (downstream side), there is an outlet 65 for the dried processed material DB, and gas exhaust ports 66 are provided on the top and sides. In Figure 3, two hot air inlets 64, two gas exhaust ports 66, and two outlets 65 are depicted, but at least one of each is sufficient. However, by providing two of each, the processing time can be adjusted according to the condition of the used bedding material UB, such as changes in moisture content. Reference numeral 67 denotes a viewing window for checking the internal condition.

[0046] The drum body 61 comprises a shaft 70 that is fixed to rotate freely within the drum body 61, a plurality of stirring blades 71 that are attached to the shaft 70 within the drum body 61 and rotate around the shaft 70, and a drive device 76 that drives the shaft 70.

[0047] As shown in Figure 4, the stirring blade 71 consists of a rotating base 72 connected to the shaft 70, and two blades 73 extending radially outward from the rotating base 72 at 180-degree intervals. Each blade 73 has support parts 74, 74 extending from the front and rear in the axial direction of the drum body, and a plate-shaped blade part 75 connecting the tips of these support parts. The plate-shaped blade part 75 has a width parallel to the radial direction of the drum body 61 and a length parallel to the shaft 70 of the drum body 61. Thus, the stirring blade 71 does not push air in the axial direction by rotating, but rather finely crushes and grinds the used bedding material UB that has been put into the drum body. However, the shape of the stirring blade 71 is not particularly limited.

[0048] Multiple stirring blades 71 are arranged at equal intervals in the axial direction within the drum body 61, and adjacent stirring blades 71 are set with the angle of the blades 73 offset by 90 degrees. Figure 4B shows odd-numbered stages of stirring blades 71, and Figure 4C shows even-numbered stages of stirring blades 71. In other words, the angles of the blades 73 coincide every other blade. In this embodiment, 13 stirring blades 71 are provided, but the number is not particularly limited.

[0049] The drive unit 76 is installed outside the drum body 61 and includes a motor 77, a reduction gear 78 connecting the motor 77 to the shaft 70, and a cover 79 covering the reduction gear 78. The type and structure of the drive unit 76 are not particularly limited.

[0050] Returning to Figure 1, the input hopper 52 and input conveyor 53 are not particularly limited in their form, as long as they collect the used bedding material UB and guide it to the drum body of the drying drum 51.

[0051] The processed material DB, which has been dried in the drying drum 51, is collected from the outlet (65 in Figure 3B) and transported to the temporary processing area 58 by the processing material conveyor 57. The processed material DB is then removed from the temporary processing area 58 and stored in silos or other containers, or returned to the livestock barn as recycled bedding.

[0052] The exhaust gas EA discharged from the gas exhaust port (66 in Figure 3) of the drying drum 51 is released into the atmosphere through dust collectors 54 and 55 and an induced draft fan 56. The temperature of the exhaust gas EA from the drying drum 51 can be controlled by changing the output of the induced draft fan 56 to control the amount of induced draft. The dust collectors 54 and 55 are not particularly limited in type, but for example, they are cyclone-type dust collectors. Since the exhaust gas from the drying drum 51 contains a large amount of powdery material DB, the material DB collected by the dust collectors 54 and 55 is returned to the material conveyor 57. If an appropriate dust collector is selected, almost all of the material DB in the exhaust gas will be collected by the preceding dust collector 54, so the subsequent dust collector 55 mainly functions to purify the exhaust gas before it is released into the atmosphere.

[0053] The material transport unit 40 includes a transport pipe 41, a dust collector 42, and a suction blower 43. The material transport unit 40 transports the material DB pneumatically from the drying unit 50 to the first hot air generator 21.

[0054] The transport pipe 41 has its inlet facing near the end of the material conveyor 57 and sucks up the material DB on the material conveyor. The material transported through the transport pipe 41 goes to the dust collector 42 and is discharged into the main fuel input hopper (24 in Figure 2). The suction blower 43 generates an airflow that flows through the transport pipe 41.

[0055] The processed material transport unit 40 can be omitted, but by including the processed material transport unit in the drying system 10, the used bedding material UB can be dried in the drying unit 50, and the processed material DB can be directly transported to the first hot air generator 21 and used as the main fuel.

[0056] Next, the drying process method of this embodiment will be described. This process is carried out using the drying process system 10 described above and includes a hot air generation step and a drying step for drying the used bedding material UB. The reference numerals for each part are shown in Figures 1 to 5.

[0057] First, let me explain the drying process.

[0058] In the drying section 50, used bedding material UB is placed in the drying drum 51, and hot air HA generated by the first hot air generator 21 is supplied. Inside the drying drum 51, the used bedding material UB is agitated and crushed by the stirring blades 71 while being dried by the hot air HA applied directly. Because the drum body 61 of the drying drum 51 is inclined, the used bedding material is agitated by the stirring blades 71 and carried to the outlet 65 by gravity. In this way, the used bedding material is dried inside the drying drum 51 for a predetermined time.

[0059] The temperature of the hot air HA supplied to the drying drum 51 is usually 400°C or higher, preferably 450°C or higher, more preferably 500°C or higher, and particularly preferably 550°C or higher. By setting the temperature of the hot air HA to 400°C or higher, odors contained in the used bedding material UB (for example, ammonia at 500°C or higher) can be removed. The temperature of the hot air HA is preferably 900°C or lower. If the hot air temperature is 900°C or higher, it may adversely affect the materials of the equipment. The temperature of the hot air HA is even more preferably 700°C or lower.

[0060] The temperature of the exhaust EA discharged from the drying drum 51 is preferably 90°C or higher, more preferably 95°C or higher, and particularly preferably 110°C or higher. If the temperature of the exhaust EA is lower than 90°C, the used bedding material being introduced cannot be sufficiently sterilized. On the other hand, the temperature of the exhaust EA is preferably 300°C or lower, more preferably 150°C or lower, and particularly preferably 130°C or lower. If the temperature of the exhaust EA is higher than 300°C, the processed material DB may turn into dust, which may harm the health of livestock, such as damaging their respiratory system, when used as recycled bedding material. The temperature of the exhaust EA can be adjusted by changing the output of the induced draft fan 56 to control the airflow velocity inside the drying drum 51.

[0061] The dried used bedding material DB is collected from the outlet of the drying drum 51 (65 in Figure 3B), and a portion is collected from the exhaust EA by dust collectors 54 and 55, and then transported to the temporary storage area 58 by the processed material conveyor 57. The drying process is carried out under conditions that reduce the moisture content of the processed material to 10% to 30%, preferably 20% to 30%.

[0062] The hot air generation process is a process that generates hot air HA for drying the used bedding material UB in the drying section.

[0063] The hot air HA can be generated by the first hot air generator 21 with valves 36-38 in the state shown in Figure 5A, or by the second hot air generator 32 with valves 36-38 in the state shown in Figure 5B. In other words, the hot air HA1 generated by the first hot air generator 21 can be supplied to the drying section 50 as hot air HA, or the hot air HA2 generated by the second hot air generator 32 can be supplied to the drying section 50 as hot air HA.

[0064] Furthermore, the device that generates the hot air HA can be switched as needed, from the first hot air generator 21 to the second hot air generator 32, or vice versa. For example, when the biomass fuel, which is the main fuel for the first hot air generator, is depleted, the state of valves 36-38 can be switched from the state shown in Figure 5A to the state shown in Figure 5B, stopping the first hot air generator 21 and starting the second hot air generator 32, thereby allowing the drying process to continue without interruption.

[0065] Compared to the second hot air generator 32 which uses fossil fuels, the first hot air generator 21 which uses biomass fuel takes longer to start up. Therefore, when starting up the first hot air generator 21 at the beginning of operation, or when switching the hot air generating device from the second hot air generator 32 to the first hot air generator 21, the start-up of the first hot air generator 21 can be divided into two stages: the first stage is the initial start-up stage to raise the temperature of the first hot air generator 21, and the second stage is the steady-state operation stage after the first hot air generator 21 has been heated up.

[0066] In the first stage of startup, the second hot air generator 32 heats the outside air OA to generate starting hot air SA, which is supplied to the air inlet 22 of the first hot air generator 21. The starting hot air SA heats the various parts of the first hot air generator and the sand inside. The temperature of the starting hot air SA supplied to the first hot air generator 21 is 200°C to 800°C, preferably 500°C to 700°C. As the starting hot air SA loses heat to the various parts of the first hot air generator and the sand, its temperature decreases, so the auxiliary burner 26 heats it to raise the temperature of the hot air HA1 coming out of the first hot air generator to a predetermined temperature. This allows the hot air HA1 generated during startup to also be used for drying the used bedding material UB in the drying section 50.

[0067] Once the first hot air generator 21 has reached a sufficient temperature, specifically exceeding the ignition temperature of the material DB, which is 200-250°C, it moves from the first stage to the second stage of steady-state operation. When the kerosene burner 33 of the air supply unit 30 is stopped, the outside air OA taken in by the push fan 31 passes through the second hot air generator 32, but without being heated except for preheating, and is supplied to the air inlet 22 of the first hot air generator 21. In this state, the main fuel is supplied from the fuel input unit 23 of the first hot air generator 21 and combusted.

[0068] The main fuel is transported from the first stage of the hot air generation process, while drying the used bedding material UB, to the input hopper 24 from the processing material conveyor 57. Even after moving to the second stage of the hot air generation process, the weight of the processing material DB in the input hopper 24 is monitored, and processing material DB is transported from the processing material conveyor 57 to replenish it as needed.

[0069] The processed material DB used as the main fuel may be processed material DB that has been stored from a previously carried out drying process. In addition to processed material DB, compost made from dried and fermented livestock manure may be added to the main fuel. Other fuels besides processed material DB and compost may also be added to the main fuel. The moisture content of the main fuel is preferably 45% or less, more preferably 40% or less, and particularly preferably 35% or less, as described above.

[0070] As described above, the hot air generation process may generate hot air HA using the first hot air generator 21, or using the second hot air generator 32, or by switching between both devices as appropriate. When starting up the first hot air generator 21, the first stage involves using the starting hot air SA from the second hot air generator 32 and the auxiliary burner 26, and the second stage involves stopping the second hot air generator 32 and generating hot air HA using the combustion of the main fuel and, if necessary, the auxiliary burner 26 and cooling damper 29. When using a fluidized bed type first hot air generator, in a typical operation example, the first stage consists of the first 3-4 hours at the start-up, and the remainder is the second stage, and in daytime-only operation, the operating time for one drying treatment is about 10 hours.

[0071] According to the drying method of this embodiment, even when the first hot air generator is undergoing maintenance or when the biomass fuel runs out, hot air can be generated in the second hot air generator to perform the drying process on the material to be processed in the drying section. Furthermore, when starting up the first hot air generator, the drying process on the material to be processed in the drying section can be started while the second hot air generator is heating up the first hot air generator, thereby shortening the time until the drying process can begin.

[0072] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of its technical concept. [Explanation of symbols]

[0073] 10. Drying System 20 Hot air generating section 21. First Hot Air Generator 22 Air intake section 23 Fuel input section 24 Input Hopper 25 Input conveyor 26. Auxiliary burner (auxiliary heating means) 27 Combustion fan 28 Kerosene supply sources 29 Cooling damper 31 Push-in fan 32. Second Hot Air Generator 33. Kerosene burner 34 Combustion Fan 35 Kerosene supply sources 36, 37, 38 valves 40 Processing and Transport Department 41 Transport pipe 42 Dust collector 43. Suction Blower 50 Drying section 51 Drying Drum 52 Input hopper 53 Input conveyor 54, 55 Dust collector 56 Inducing Fan 57. Conveyor belt for processed materials 58 Temporary storage area for processed materials 61 Drum body (processing tank) 62 mounting bases 63 Used bedding disposal slot 64 Hot air inlet 65 Outlet 66 Gas exhaust port 67 Peephole 70 axis 71 Agitator blade 72 RPM base 73 Wings 74 Support part 75 Blade section 76 Drive unit 77 Motor 78 Reduction gear 79 Cover DB Processing Items EA exhaust HA, HA1, HA2 hot air OA outside air SA Starting Hot Air UB Used bedding material (material to be processed) X Length of the drum body Y Drum body diameter

Claims

1. A hot air generating unit that generates hot air, It comprises a drying section that dries the material to be processed, derived from livestock excrement, with hot air while stirring it, The hot air generating unit comprises a first hot air generating device that uses biomass fuel and a second hot air generating device that uses fossil fuel. The first hot air generator and the second hot air generator are each connected to the drying section and are interconnected. Drying system.

2. The second hot air generator is connected in series upstream of the first hot air generator and generates starting hot air to raise the temperature of the first hot air generator. The drying process system according to claim 1.

3. The material to be processed includes used bedding containing livestock excrement. The drying process system according to claim 1.

4. The material to be treated includes compost derived from livestock excrement. The drying process system according to claim 1.

5. The first hot air generator is a fluidized bed type device. The drying process system according to claim 1.

6. The first hot air generator has an auxiliary heating means downstream of the biomass fuel input section. The drying process system according to claim 1.

7. A hot air generation process in which hot air is generated by a first hot air generating device, The process includes a drying step in which a material to be treated, derived from livestock excrement, is dried with hot air while being stirred to produce a treated product. The aforementioned hot air generation process is: The first step involves sending the starting hot air generated by the second hot air generator using fossil fuels to the first hot air generator to raise the temperature of the first hot air generator, while generating the hot air using an auxiliary heating means provided in the first hot air generator. The system comprises a second stage in which outside air is supplied to the first hot air generator, and biomass fuel is burned inside the first hot air generator to generate the hot air, Drying method.

8. A hot air generation process that generates hot air, The process includes a drying step in which a material to be treated, derived from livestock excrement, is dried with hot air while being stirred to produce a treated product. The hot air generation process is carried out by switching between a first hot air generation process, in which hot air is generated by a first hot air generator using biomass fuel, and a second hot air generation process, in which the first hot air generator is stopped and hot air is generated by a second hot air generator using fossil fuels. Drying method.

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