Fermentation and drying apparatus and fermentation and drying method

Abstract

To provide a fermentation and drying apparatus and a fermentation and drying method which can perform air-inlet control according to each of a fermentation stage and a drying stage, and can efficiently perform fermentation and drying.SOLUTION: A fermentation and drying apparatus 1 includes a rotary shaft 3 and agitating blades 4 provided in a container 2, an air feed blower 6, and exhaust means 9, and ferments and dries a fermentation raw material while introducing outside air into the container 2 and exhausting inside air from the container 2 by the exhaust means 9, and agitating the fermentation raw material with the agitating blades 4 includes: calculation means for calculating a change amount of a fermentation heat quantity at an arbitrary time interval; determination means for determining timing of changing the change amount from an increasing trend to a decreasing trend on the basis of the calculated change amount of the fermentation heat quantity; and operation control means for performing an operation mode of setting at least any one of an amount of the outside air introduced into the container and a temperature of the outside air introduced into the container to be larger than an item before the timing is determined, after the timing has been determined by the determination means.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fermentation and drying apparatus and a fermentation and drying method. [Background technology]

[0002] Conventionally, sealed vertical composting equipment that utilizes the fermentation action of microorganisms has been known as equipment for fermenting and drying fermentation materials such as livestock waste, food waste, and sewage sludge to turn them into compost. This equipment is a vertical cylindrical tank in which the fermentation materials fed into the sealed container are stirred and forced aerated while fermenting and drying.

[0003] For example, Patent Document 1 discloses a closed fermentation and drying apparatus comprising a rotating shaft provided in a vessel, a plurality of stirring blades attached thereto, an air supply means, and an exhaust means. In this apparatus, the amount of fermentation heat and the amount of evaporated water per given time are used as fermentation indices, and the amount of outside air introduced into the vessel is controlled based on these fermentation indices. The fermentation heat and the amount of evaporated water, which serve as indices, are calculated based on the temperature and flow rate of the outside air introduced into the vessel, and the temperature and flow rate of the inside air discharged from the vessel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-172272 A Summary of the Invention [Problem to be solved by the invention]

[0005] In general, when operating a fermentation and drying device, it is important to control the flow rate and temperature of the outside air introduced into the container. The functions of the outside air introduced into the container include (1) supplying oxygen to activate microorganisms, and (2) removing moisture from the fermentation raw materials and inside the container and drying them. In conventional fermentation and drying devices, even though fermentation and drying proceed simultaneously in parallel, the fermentation and drying process from the input of the fermentation raw materials to their removal has not been operated with a focus on either fermentation or drying. On the other hand, it is known from experience that the degree of fermentation is high up to a certain stage after the input of the fermentation raw materials, and the degree of drying is high thereafter. For this reason, it is considered desirable to perform air intake control that places more emphasis on either fermentation or drying.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a fermentation and drying apparatus and method that can perform air intake control appropriate for each of the fermentation and drying stages in the fermentation and drying process from the input to the removal of fermentation raw materials, and can efficiently perform fermentation and drying. Specifically, the purpose of the air intake control with emphasis on fermentation is to increase the amount of dry matter decomposition, and the purpose of the air intake control with emphasis on drying is to increase the amount of water evaporation. [Means for solving the problem]

[0007] The fermentation drying apparatus of the present invention is a sealed type fermentation drying apparatus comprising a rotating shaft provided in a container and a plurality of stirring blades attached thereto, an air supply means for taking in outside air into the container, and an exhaust means for discharging the inside air accumulated in the container to the outside of the container. The fermentation drying apparatus is an apparatus for fermenting and drying fermentation raw materials while stirring them with the stirring blades, while introducing outside air into the container by the air supply means and exhausting the inside air from the container by the exhaust means. The fermentation drying apparatus is characterized by having a calculation means for calculating a change in the amount of fermentation heat (hereinafter also simply referred to as ΔQ) at any time interval, a judgment means for judging the timing at which the amount of change changes from an increasing trend to a decreasing trend based on the calculated change in the amount of fermentation heat, and an operation control means for performing an operation mode in which at least one of the items of the amount of outside air introduced into the container and the temperature of the outside air introduced into the container is made larger than the item before the timing was judged by the judgment means.

[0008] In this specification, the temperature of outside air introduced into the container refers to the temperature of the outside air finally introduced into the container after passing through the air supply means, heater, etc., and this temperature is referred to as the "intake air temperature." If there are multiple intake air paths, the average of the temperatures of the outside air introduced into the container from each intake air path is referred to as the intake air temperature. Also, in this specification, the amount of outside air introduced into the container refers to the amount of outside air introduced into the container per unit time, and is referred to as the "intake air volume." If there are multiple intake air paths, the intake air volume is referred to as the sum of the amounts of outside air introduced into the container per unit time from each intake air path.

[0009] The operation control means, in the operation mode, is further characterized in that it makes at least one of the stirring frequency and the stirring speed of the stirring blades larger than the item before the timing is determined.

[0010] The judgment means calculates the slope of the change in the fermentation heat, and judges the timing if the slope is less than a threshold value and if at least one of the following conditions is satisfied: the fermentation heat is increasing at that point in time, the temperature of the inside air (exhaust temperature) is increasing, and the temperature of the inside air is equal to or higher than a predetermined temperature.

[0011] The operation control means is characterized in that after the timing is determined by the determination means and during a predetermined period before the operation mode is performed, it reduces at least one of the items of the amount of outside air introduced into the container, its temperature, the stirring frequency of the stirring blades, and its stirring speed, compared to the items before the timing was determined.

[0012] The predetermined period is a period from when the timing is determined by the determining means until the amount of change in the amount of fermentation heat becomes negative.

[0013] The fermentation and drying method of the present invention is a fermentation and drying method in a closed fermentation and drying apparatus comprising a rotating shaft provided in a container and a plurality of stirring blades attached thereto, an air supply means for taking in outside air into the container, and an exhaust means for discharging the inside air accumulated in the container to the outside of the container, wherein the fermentation and drying apparatus is an apparatus for fermenting and drying fermentation raw materials while stirring them with the stirring blades, while introducing outside air into the container by the air supply means and exhausting the inside air from inside the container by the exhaust means, and the fermentation and drying method is characterized by comprising a calculation step for calculating an amount of change in the amount of fermentation heat at any time interval, a judgment step for judging the timing at which the amount of change changes from an increasing trend to a decreasing trend based on the calculated amount of change in the amount of fermentation heat, and an operation control step for increasing at least one of the items of the amount of outside air introduced into the container and the temperature of the outside air introduced into the container after the timing is judged by the judgment step, compared to the items before the timing was judged. Effect of the Invention

[0014] The fermentation and drying apparatus of the present invention has a calculation means for calculating the amount of change in the amount of fermentation heat at any time interval, a judgment means for judging the timing at which the amount of change in the amount of fermentation heat changes from an increasing trend to a decreasing trend based on the calculated amount of change in the amount of fermentation heat, and an operation control means for performing an operation mode in which at least one of the items of the amount of intake air and the intake air temperature introduced into the container is made larger than the items before the judgment of the timing after the judgment means, so that after the judgment of the timing, intake control can be performed with an emphasis on drying, particularly to increase the amount of water evaporation. This makes it possible to perform intake control according to the fermentation stage and the drying stage in the fermentation and drying process from the input of the fermentation raw material to its removal, and to efficiently carry out fermentation and drying. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a vertical cross-sectional view showing an example of a fermentation drying apparatus of the present invention. [Diagram 2] FIG. 1 is a schematic diagram of the inlet and exhaust paths of a fermentation drying apparatus in a test example. [Diagram 3] FIG. 1 is a graph showing changes in fermentation heat Q and exhaust temperature over time. [Figure 4] FIG. 13 is a graph showing the correlation between the amount of change in fermentation heat, ΔQ, and the exhaust temperature. [Diagram 5] FIG. 1 is a graph showing changes in fermentation heat Q and exhaust temperature over time. [Figure 6] FIG. 13 is a graph showing the correlation between the amount of change in fermentation heat, ΔQ, and the exhaust temperature. [Figure 7] FIG. 1 is a diagram showing an example of operation modes divided according to the amount of change in fermentation heat, ΔQ. [Figure 8] FIG. 11 is a diagram showing another example of operation modes divided according to the amount of change in the amount of fermentation heat, ΔQ. [Figure 9] FIG. 9 is a model diagram showing the time transition of exhaust temperature in the operational control of FIG. 8. [Figure 10] FIG. 13 is a diagram showing the results for each calculation span of the change in fermentation heat quantity, ΔQ. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The fermentation and drying apparatus of the present invention will be outlined with reference to Fig. 1. Fig. 1 is a vertical cross-sectional view showing an example of the configuration of a fermentation and drying apparatus. As shown in Fig. 1, the fermentation and drying apparatus 1 is a sealed vertical fermentation and drying apparatus (compo) comprising a cylindrical vertical vessel 2, a rotating shaft 3 provided vertically within the vessel 2, a plurality of stirring blades 4 provided in multiple stages around the rotating shaft 3, an air blower 6 as an air supply means for taking in outside air into the vessel 2, and an exhaust means 9 for discharging the internal air accumulated within the vessel 2 to the outside of the vessel. The apparatus of the present invention is a vertical fermentation and drying apparatus (compo) comprising a cylindrical vertical vessel 2, a rotating shaft 3 provided vertically within the vessel 2, a plurality of stirring blades 4 provided in multiple stages around the rotating shaft 3, an air supply blower 6 as an air supply means for taking in outside air into the vessel 2, and an exhaust means 9 for discharging the internal air accumulated within the vessel 2 to the outside of the vessel. 3 The main target is a large-scale commercial device as described above. The shape of the stirring blade 4 is not particularly limited, and can be, for example, a pitched paddle shape extending linearly from the rotating shaft 3 toward the inner wall side of the container 2, with an inclined surface on the front side in the direction of rotation.

[0017] The lower part of the lowest stirring blade has an air hole 4a, and outside air (intake air) sent from an air blower 6 is introduced into the container from the air hole via a pipe 6a provided in the rotating shaft. The container 2, which is a fermenter, is an insulated container having a metallic outer layer and an insulating layer, and is an airtight container that is unlikely to come into contact with outside air other than that introduced from the air hole. The container 2 also has an inlet 2a for fermentation raw materials and an exhaust outlet 2c at the top, and an outlet 2b for the fermented and dried product after processing at the bottom. The exhaust outlet 2c is connected to an exhaust means 9. The inlet 2a and the outlet 2b are provided with an openable lid or the like to ensure the airtightness of the container.

[0018] In the embodiment shown in Fig. 1, a machine room 5 is provided below the container 2, and a hydraulic cylinder 8, which is a drive means for the rotating shaft 3, and the above-mentioned air blower 6 are provided in this machine room. The rotating shaft 3 penetrates inside the machine room 5, and is rotated at a predetermined rotation speed by the hydraulic cylinder 8. It is preferable to use the air blower 6 with a blower rotation speed that can be controlled by an inverter frequency so that the amount of air intake can be adjusted. Also, an air supply valve for adjusting the amount of air intake may be provided midway through the piping 6a.

[0019] Gas and water vapor generated in the container are exhausted to the outside air through the exhaust port 2c via the exhaust means 9. The exhaust means 9 has an exhaust pipe 10, an exhaust blower 11, and a deodorizing device 12. The exhaust blower 11 forcibly exhausts gas and the like in the container. The deodorizing device 12 is, for example, a water-washing scrubber that captures odorous components by contacting gas with water as a cleaning liquid. Examples of odorous components include lower fatty acids such as propionic acid, normal butyric acid, and isovaleric acid, sulfur compounds, and ammonia. A temperature sensor 13 that detects the exhaust temperature is provided in the exhaust pipe 10 between the container 2 and the exhaust blower 11.

[0020] In the embodiment shown in Fig. 1, a heater 7 is provided for heating the outside air sent from the air blower 6. The heater 7 is not essential, and for example, a heat exchange means (not shown) may be provided for heating the outside air introduced into the container from the air blower 6 by utilizing the heat of the exhaust from the exhaust means 9. In this case, the heater is not required, and running costs can be reduced. The form and installation location of the heat exchange means are not particularly limited, and for example, the air supply piping before being introduced into the container may be passed through a heat exchanger filled with exhaust air.

[0021] The fermentation and drying apparatus 1 may have an external insulation panel installed so as to cover at least a part of the outer periphery of the container 2 through a space. By providing the external insulation panel and forming a double insulation structure with the container, more stable processing can be achieved in the apparatus installed outdoors. The shape of the external insulation panel can be, for example, a square tube shape in which the outer wall of the apparatus formed by the panel is approximately circumscribed on the cylindrical outer periphery of the container.

[0022] In the fermentation and drying apparatus of the present invention, the fermentation raw material to be fermented and dried includes livestock waste, food waste, sludge, or a mixture thereof, which are rich in organic components. Specifically, livestock waste includes chicken manure, pig manure, cow manure, horse manure, etc., food waste includes food waste, food manufacturing by-products, etc., and sludge includes sludge generated from sewage treatment facilities, sludge generated from agricultural village wastewater treatment facilities, sludge generated in the livestock wastewater treatment process, and sludge generated in the wastewater treatment process of food factories. In addition, the fermentation and drying process in the fermentation and drying apparatus is performed in a container by aerating the material in the presence of aerobic fermentation bacteria. As the aerobic fermentation bacteria, fermentation bacteria that are activated at about 30 to 90°C are preferable, and examples thereof include the genus Geobacillus and the genus Bacillus.

[0023] In the fermentation and drying apparatus 1 of FIG. 1, the fermentation raw material is put into the inside of the container 2 through the inlet 2a, and after fermentation and drying in the container, the fermented and dried product is taken out from the outlet 2b at the bottom of the container. Fermentation and drying are performed by rotating each agitator 4 at a low speed while introducing a predetermined amount of outside air through the ventilation hole 4a of the lowest agitator blade by the air blower 6 and exhausting the inside air through the exhaust port 2c and the exhaust means 9, thereby aerating and agitating the fermentation raw material such as sewage sludge, and fermenting it aerobically. In addition, drying is also performed by aeration at the same time. The air exhausted from the exhaust port 2c is the air that is introduced into the container through the ventilation hole and flows upward while passing through the treated material, and contains gas and water vapor generated from the fermentation raw material. Note that the air entering the container is not limited to the ventilation hole 4a of the lowest agitator blade, but may also be provided with a ventilation hole in the agitator one level above the lowest level, and air may also be introduced through that ventilation hole. In this case, air may be sent from a separately provided air blower to the vent holes of the mixing impeller one level above the lowest level.

[0024] The operation procedure is as follows: first, the fermentation raw materials are charged into the fermentation and drying apparatus, leaving a space (head space) of 10 to 30% of the internal volume of the apparatus. By charging the fermentation raw materials leaving a space of 10 to 30%, stirring is performed sufficiently, and fermentation and drying are performed efficiently. The charging is performed every day, fermentation and drying are performed for a predetermined residence time (about 3 to 20 days), and a predetermined amount (for example, about 20% by mass) of fermented and dried product is taken out every certain period (for example, every day). The above charging is performed after the fermentation and drying product is taken out. In this way, the charging of a portion of the fermentation raw materials and the removal of a portion of the fermentation and drying product are repeated in a certain time cycle to perform continuous processing. The obtained fermentation and drying product is usually in the form of a loose powder.

[0025] 1, the fermentation and drying apparatus 1 is equipped with a control panel 14 that controls the operation of the apparatus. The control panel 14 can be used to, for example, switch between automatic and manual operation modes, perform various settings in the automatic operation mode, and perform various operations in the manual operation mode (for example, turning the air blower 6 on / off, turning the exhaust blower 11 on / off, turning the hydraulic cylinder 8 on / off, raising and lowering the bucket (not shown), etc.).

[0026] As described above, in the series of fermentation and drying processes from the input to the removal of the fermentation raw materials, the fermentation and drying of the fermentation raw materials are basically performed simultaneously. As a result of investigating the relationship between the amount of change in fermentation heat ΔQ and the exhaust temperature, the inventors found that the amount of change in fermentation heat ΔQ changes from increasing to decreasing at a certain temperature range, even though the exhaust temperature is increasing. Furthermore, they found that by using this amount of change ΔQ as an index, it is possible to perform intake control specialized for each of the fermentation stage and the drying stage. The present invention is based on such findings.

[0027] The fermentation and drying apparatus 1 of the present invention is characterized by having a calculation means for calculating the amount of change ΔQ in the amount of fermentation heat at any time interval, a judgment means for judging the timing at which the amount of change ΔQ changes from an increasing trend to a decreasing trend based on the calculated amount of change ΔQ, and an operation control means for performing a predetermined operation mode after the judgment means judges the above timing. The control device 15 in FIG. 1 includes the calculation means, judgment means, and operation control means, and is mainly composed of a microcomputer consisting of a known CPU, ROM, RAM, etc. The control device 15 is configured to continuously acquire and store information from temperature sensors that can measure the air temperature at each point, an acquisition means that can acquire the amount of intake air, an acquisition means that can acquire the amount of exhaust air, etc. The control device 15 also has various calculation functions.

[0028] The calculation means repeatedly acquires the amount of fermentation heat at any time interval. Then, each time the amount of fermentation heat is acquired, the difference (amount of change ΔQ) between the amount of fermentation heat at the current time and the amount of fermentation heat at a time a predetermined time ago is calculated. In the present invention, the time interval between the current time and the time a predetermined time ago in the calculation of the above ΔQ is called the calculation span. The calculation span can be set appropriately, for example, from a short interval of about 1 to several minutes to a relatively long interval such as 60 minutes or 120 minutes. The calculation span may be the same as or different from the time interval for acquiring the amount of fermentation heat.

[0029] Below, we will first explain the relationship between the amount of change in fermentation heat, ΔQ, and the exhaust temperature, using a test example conducted at a pig farm. In this test, the fermentation and drying equipment used was a Compo S-36ET (volume 39 m) manufactured by Chubu Ecotec Co., Ltd. 3 A schematic diagram of the inlet and exhaust paths of this fermentation and drying device is shown in Figure 2.

[0030] As shown in FIG. 2, the fermentation and drying apparatus 1' is configured such that air is continuously supplied by air blowers 6A and 6B, and exhaust is performed from the exhaust port 2c at the top of the vessel by an exhaust blower 11. Air is supplied to the lowest stage agitator 4A by the air blower 6A installed at the bottom of the vessel, and air is supplied to the second lowest stage agitator 4B by the air blower 6B installed at the top of the vessel. Filters 16A and 16B are provided on the upstream side of the air supply of the air blowers 6A and 6B, respectively. This test was performed with the agitator blades of the fermentation and drying apparatus 1' in intermittent operation, with one cycle consisting of 7 minutes of rotation and 9 minutes of rest. The total air intake volume of the air blowers 6A and 6B installed at the bottom and top was 0.20 m per fermentation tank volume. 3 / min·m 3 During the test period, the heater 7 for heating the outside air was not operated and the operation was performed under non-heating conditions, but the outside air that passed through the air blowers 6A and 6B was heated by each of the air blowers.

[0031] The fermented and dried material was removed once a day from the outlet at the bottom of the vessel, with an average of about 1,400 kg being removed. After the fermented and dried material was removed, the fermentation raw material, pig manure, was added using a bucket through the inlet at the top of the vessel, without adjusting its moisture content or specific gravity, once a day, with an average of about 3,300 kg. The removal of the fermented and dried material and the addition of the fermentation raw material were basically carried out at a designated time every day (between 9:00 and 11:00 a.m.).

[0032] The test was carried out for 11 days from February 5 to February 15, and the fermentation heat quantity Q, the change in fermentation heat quantity ΔQ, the temperature at each point of the intake air route, the exhaust air temperature, the intake air volume, the exhaust air volume, the outside air humidity, the temperature inside the container, the container weight, etc. were continuously recorded. The fermentation heat quantity Q and its change in quantity ΔQ were calculated using the following formulas (1) to (4).

[0033] The temperature at each point in the intake air path was measured at two of the points a to d shown in Figure 2 (point a: outside air (lower part), point b: after the blower (lower part)), and the exhaust air temperature was measured at point e. At these points, the temperature inside the pipe was measured at one-minute intervals using a K thermocouple (Shimaden, model number: STD-23S series). The amount of intake air introduced into the container (unit: m 3 / h) was determined by measuring the wind speed in the pipes at points b and d with an anemometer (manufactured by Nippon Kanomax, model number: 0965-00) and calculating the total amount from the following formula (1). The exhaust volume was set to 1.2 times the intake volume.

number

[0034] The value of 0.82 in the above formula (1) is 2n 2 This shows the average velocity coefficient expressed as / (n+1) × (2n+1), and is the value when the number of impeller blades in the impeller is n = 7.

[0035] The heat quantity of the air entering the fermentation and drying equipment was the sum of the heat quantity Qg(b) after the blower (lower) and the heat quantity Qg(d) after the blower (upper), and each heat quantity was calculated using the following formula (2). For the heat quantity Qg(b) after the blower (lower) and the heat quantity Qg(d) after the blower (upper), the amount of water vapor per unit volume was calculated from the relative humidity of the heat quantity Qg(a) of the outside air (lower) and the heat quantity Qg(c) of the outside air (upper), and the heat quantity was calculated under the assumption that the moisture content does not change even if the temperature changes. The temperature at point d was calculated as the temperature at point c + 24°C. The heat quantity of the exhaust air Qg(e) was also calculated using the following formula (2). Since the water vapor at point e was discharged in a nearly saturated state, the relative humidity of the exhaust air was set to 100%. The humidity of the outside air was calculated as the hourly average value from the data observed every 10 minutes by the local meteorological observatory, and used for the heat quantity calculation.

number

[0036] Using each calorific value obtained, the fermentation heat amount Q (unit: MJ / h) per unit time was calculated from the following formula (3). In formula (3), the inlet air heat amount was defined as the heat amount supplied to the container, and the exhaust air heat amount was defined as the total heat amount of the inlet air heat amount and the heat amount generated in the container. Assuming that there is no heat radiation or heat storage in the device (container), the fermentation heat amount was defined as the amount obtained by subtracting the inlet air heat amount from the exhaust air heat amount. In other words, the fermentation heat amount can be said to be the heat amount itself generated by the fermentation and drying of the fermentation raw materials in the device (container).

number

[0037] Using the obtained fermentation heat quantity Q per unit time, the change amount per hour ΔQ (unit: MJ / h) was calculated according to the following formula (4). The change amount ΔQ in formula (4) represents the increase or decrease amount of the fermentation heat quantity Q, and t represents time.

number

[0038] Figure 3 shows the data for February 10th during the above test period (February 5th to February 15th). Figure 3(a) shows the time trends of the fermentation heat Q and exhaust temperature per unit time. The exhaust temperature is shown as the average value for one hour. In Figure 3(a), the fermentation heat Q increases steadily from 14:00, peaks at 2:00 the following day, and then decreases until 9:00 the following day. During the period when the fermentation heat Q increases, the fermentation heat Q increases quadratically until 20:00, and then increases gradually. From the value of the second-order differential of the approximation formula for the fermentation heat Q, the timing when the change amount ΔQ changes from an increasing trend to a decreasing trend is 20:00. During the time period when the increase in the fermentation heat Q becomes gentle, the slope (increase) of the exhaust temperature also becomes smaller.

[0039] Figure 3(b) shows the change in fermentation heat quantity ΔQ and the exhaust temperature over time. This change ΔQ is the difference between the fermentation heat quantity Q at the present time (the time shown on the graph) and the fermentation heat quantity one hour earlier. As shown in Figure 3(b), ΔQ peaks between 7:00 and 8:00 p.m. and then decreases. After the peak, the change ΔQ drops sharply and goes from positive to negative. Note that when the change ΔQ becomes negative, it means that the fermentation heat quantity Q is decreasing.

[0040] FIG. 4 shows a graph with the change in fermentation heat ΔQ on the vertical axis and the exhaust temperature on the horizontal axis. The circles in the figure are plots of the exhaust temperature during the period corresponding to each change ΔQ in FIG. 3(b), and the dotted lines in the figure are their approximate curves. This curve represents the movement in the process of increasing the exhaust temperature, which moves irreversibly. As shown in FIG. 4, the change ΔQ changes from increasing to decreasing when the exhaust temperature is around 59°C to 60°C. In this specification, the peak of the change ΔQ is also called the inflection point. Since the change ΔQ represents the increase or decrease in the amount of heat generated when microorganisms decompose organic matter, the fact that the change ΔQ reaches a peak and plateaus means that the decomposition rate (growth rate) of organic matter by microorganisms plateaus. In other words, it is considered that the microorganisms are gradually deactivated during the period after the peak of the change ΔQ. Also, in FIG. 4, the exhaust temperature reverses at a change ΔQ of about 16 MJ / h.

[0041] Next, data from another day (February 13th) is shown in Figures 5 and 6. Figures 5 and 6 are graphs corresponding to Figures 3 and 4, respectively. As shown in Figure 5(b), the change amount ΔQ on February 13th was maximum in the time period from 8:00 p.m. to 9:00 p.m., and the exhaust temperature at the peak was about 59°C to 60°C. Also, as shown in Figure 6, the approximation curve of the change amount ΔQ shows a cyclical pattern similar to that in Figure 4, and an inflection point where the increase turns to a decrease can be confirmed. Thus, even on another day, the fermentation heat amount Q, the change amount ΔQ, and the exhaust temperature behave in the same way as on February 10th.

[0042] From the data in Figs. 3 to 6, it was found that the change in fermentation heat quantity ΔQ changes from increasing to decreasing at a certain temperature range of the exhaust temperature. The peak of the change ΔQ can be said to be the peak of the decomposition rate of organic matter by microorganisms, and after the peak, the activity and proliferation rate of the microorganisms are thought to decrease. Therefore, the period before the peak of the change ΔQ can be said to be a stage in which fermentation is dominant inside the container, and the period after the peak of the change ΔQ can be said to be a stage in which drying is dominant. After detecting the peak of the change ΔQ, the fermentation and drying apparatus of the present invention performs an operation mode different from that before the peak.

[0043] Figure 7 shows an example in which the operation mode is divided into two around the peak of the change amount ΔQ. Specifically, the operation control from the input of raw materials to their removal is divided into operation mode 1, which covers the period from the input of raw materials to when the change amount ΔQ reaches its peak, and operation mode 2, which covers the period from when the change amount ΔQ reaches its peak to when the raw materials are removed. In this case, operation mode 1 is an operation mode that emphasizes fermentation so as to prolong the growth rate of microorganisms without slowing it down, while operation mode 2 is an operation mode that emphasizes drying so as to increase the weight loss resulting from the amount of water evaporation. The details of each operation mode are shown in Table 1.

[0044] [Table 1]

[0045] The unit air inlet volume shown in Table 1 is 1 m3 of material to be processed in the container. 3 The unit intake volume for operation mode 1 is 0.25 to 0.35 m3. 3 / min·m 3 In the early stages of fermentation, oxygen demand is generally high, so a certain amount of unit air intake is necessary. On the other hand, if the unit air intake is too large, the particle surfaces of the fermentation raw materials tend to dry out, which may reduce the activity of microorganisms. For this reason, the unit air intake is set at a moderate level.

[0046] During the period until the change amount ΔQ reaches its peak, the growth rate of the microorganisms is at its highest, so the inlet air temperature (55 to 60°C) is set according to the activation temperature of the microorganisms. During this period, the fermentation raw materials and the processed material in the vessel must be mixed quickly after being added to adjust the moisture and pH, and the fermentation must begin sooner. For this reason, the mixing frequency is set somewhat higher; specifically, the ratio of rotation time to stop time during intermittent operation is set to be approximately the same. Note that if the mixing frequency is set too high during this period, the added fermentation raw materials tend to fall to the bottom of the vessel, so the ratio of rotation time to stop time during intermittent operation is preferably 2:1 to 1:1.5.

[0047] In contrast, the operation mode 2 in Table 1 is set to an operation condition specialized for drying. Specifically, the unit intake air volume and the intake air temperature are set larger in the operation mode 2 than in the operation mode 1. As described above, since the period after the peak of the change amount ΔQ is considered to be a stage in which drying is dominant, the amount of water evaporation is increased by inletting a large amount of air at a relatively high intake air temperature, and the drying of the treated material is promoted. The intake air temperature can be increased, for example, by heating the air after the air blower with a heater or burner (ON / OFF), or by increasing the heater output in a configuration in which the heater output is adjustable. For example, the intake air temperature can be adjusted by controlling the heater output with a temperature regulator, etc., based on the temperature measured by the temperature sensors provided at points b and d in FIG. 2 or the temperature sensor provided between the heater 7 and the container 2 in FIG. 2. The unit intake air volume can also be increased, for example, by increasing the inverter frequency of the air blower.

[0048] In operation mode 2, the agitator blades are rotated continuously, and the agitation frequency is higher than that in operation mode 1. The agitation speed in continuous operation is, for example, about two rotations per hour. By increasing the agitation frequency, air comes into contact with the material to be treated evenly, and drying can be further promoted. Note that the mode for increasing the agitation frequency compared to operation mode 1 is not limited to continuous operation, and may be, for example, intermittent operation with a larger ratio of rotation time than the intermittent operation in operation mode 1 (for example, 18 minutes of rotation, 6 minutes of stop). Also, intermittent operation with the same time ratio as the intermittent operation in operation mode 1 may be used, and the agitation speed during rotation may be higher than that in operation mode 1.

[0049] In operation mode 2 in Table 1, both the unit intake air volume and the intake air temperature are set large, but it is sufficient that at least one of the unit intake air volume and the intake air temperature is set large. Furthermore, in each operation mode, the unit intake air volume and the intake air temperature do not have to be constant, and may be varied on condition that operation mode 2 has a relationship in which at least one of the unit intake air volume and the intake air temperature is larger than operation mode 1. Furthermore, the specific values ​​in Table 1 are not limited to these, and can be set appropriately taking into consideration the power consumption and the amount of energy consumed.

[0050] In addition, in Table 1, the unit inlet air volume, inlet air temperature, and mixing frequency in operation mode 2 are changed relative to the items in operation mode 1, but other items may be changed as well. For example, in consideration of the fact that the oxygen demand of microorganisms is large in the early stage of fermentation, the oxygen concentration of the inlet air in operation mode 1 may be made higher than the oxygen concentration of the inlet air in operation mode 2. In this case, in operation mode 1, control is performed to intentionally increase the oxygen concentration of the inlet air, and such control is not performed in operation mode 2. In addition, the humidity of the inlet air in operation mode 2 may be made lower than the humidity of the inlet air in operation mode 1. In this case, dry outside air is introduced into the container in operation mode 2, which contributes to the efficiency of drying.

[0051] Next, the determination of the ΔQ peak will be described with reference to FIG. 7. As shown in FIG. 7, the ΔQ peak is the amount of change ΔQ at the timing when the amount of change ΔQ changes from an increasing trend to a decreasing trend. Therefore, the presence or absence of the ΔQ peak can be determined by calculating the amount of change (slope) of the amount of change ΔQ and determining whether the slope is less than a threshold value. If the slope is less than the threshold value, it is determined that there is a ΔQ peak, that is, the timing when the amount of change ΔQ changes from an increasing trend to a decreasing trend has arrived. If the slope is equal to or greater than the threshold value, it is determined that the ΔQ peak has not been reached. The value of the threshold value is not particularly limited, but is set to, for example, zero, taking into consideration that the slope of ΔQ changes from plus to zero to minus before and after the ΔQ peak.

[0052] In order to improve the accuracy of the judgment of the ΔQ peak, it is preferable to judge the ΔQ peak by adding other items. As shown in FIG. 7, when the amount of change ΔQ reaches its peak, both the amount of fermentation heat Q and the exhaust temperature tend to increase. Also, as shown in FIG. 3 to FIG. 6, when the amount of change ΔQ reaches its peak, the exhaust temperature is approximately around 60°C. In consideration of these, it is preferable to use at least one of the items of (a) an increase in the amount of fermentation heat Q, (b) an increase in the exhaust temperature, and (c) the exhaust temperature being equal to or higher than a predetermined temperature, for the judgment of the ΔQ peak.

[0053] The judgment of (a) above is made based on whether the amount of change in fermentation heat, ΔQ, is positive. The judgment of (b) above is made based on whether the exhaust temperature at that time point has increased compared to the exhaust temperature a predetermined time before. The judgment of (c) above is made based on whether the exhaust temperature at that time point is, for example, 56°C or higher. Moreover, it is more preferable to judge the ΔQ peak based on the condition that all of the above (a) to (c) are satisfied in addition to the slope of the amount of change, ΔQ.

[0054] Figure 8 shows an example of further subdivision of the operation modes as another operation control. In Figure 8, the operation control from the input of raw materials to their removal is divided into operation mode 1, which is the period from the input of raw materials to the time when the amount of change ΔQ reaches its peak, operation mode 3, which is the period from when the amount of change ΔQ reaches its peak to when ΔQ becomes negative, and operation mode 2, which is the period from when the amount of change ΔQ becomes negative to when the material is removed. Unlike Figure 7, operation mode 3 is provided between operation mode 1 and operation mode 2 in Figure 8. During this period, the exhaust temperature is roughly constant at a high temperature, and operation mode 3 operates to maintain the exhaust temperature. The details of each operation mode are shown in Table 2.

[0055] [Table 2]

[0056] The details of operation modes 1 and 2 shown in Table 2 are the same as those in Table 1. On the other hand, in operation mode 3, the unit inlet air volume and inlet air temperature are smaller than those in operation mode 1 in order to maintain the exhaust temperature without rapidly increasing the growth rate of the microorganisms. The mixing frequency is also smaller than that in operation mode 1. By providing operation mode 3 as a bridge before operation mode 2, which prioritizes drying, it is possible to delay the inactivation of the microorganisms and increase the amount of dry matter decomposition during fermentation.

[0057] In the operation control of Fig. 8, the determination that ΔQ becomes negative is performed by determining whether ΔQ is less than zero. In order to improve the accuracy of this determination, other items may be added. As shown in Fig. 8, at the point in time when ΔQ becomes negative, the exhaust temperature is roughly constant, so it may also be determined that the amount of change in the exhaust temperature is within a predetermined range.

[0058] Figure 9 shows a model diagram of the time transition of the exhaust temperature when the operation control of Figure 8 is performed. As shown in Figure 9, by combining three operation modes, it is possible to perform inlet control that distinguishes between the fermentation stage and the drying stage. As a result, the exhaust temperature rises stepwise, and it is expected that the amount of dry matter decomposition and the amount of water evaporation will increase. In operation mode 1, the exhaust temperature is quickly raised by inlet control that prioritizes fermentation, in operation mode 3, the exhaust temperature is maintained by suppressing the unit inlet air volume and the inlet air temperature, and in operation mode 2, drying is promoted by increasing the unit inlet air volume and the inlet air temperature. It is preferable to shorten the operation period of operation mode 3 in order to suppress power consumption.

[0059] On the other hand, the conventional operation control shown in Fig. 9 does not focus on fermentation and drying. For example, the exhaust temperature drops in the latter half of the fermentation and drying process, which is not necessarily suitable for the drying stage. Note that the conventional operation control here is, for example, 3 / min·m 3 It is assumed that the intake air temperature is controlled at a constant 65°C.

[0060] In the above FIG. 8, a configuration is shown in which operation mode 3 is performed during the period from when the amount of change ΔQ reaches its peak until ΔQ becomes negative, but the operation period of operation mode 3 is not limited to this. For example, operation mode 3 may be performed during the period from when the amount of change ΔQ reaches its peak until ΔQ suddenly drops. This sudden drop indicates that the activity of the microorganisms has significantly decreased, and in FIG. 8, the amount of change ΔQ from 11:00 p.m. to midnight suddenly drops. This sudden drop is determined based on the fact that the slope of the amount of change ΔQ has decreased by a threshold value (e.g., 3 MJ / h) or more.

[0061] Next, the calculation span of the change amount ΔQ was examined. In the above Figs. 3 to 9, the calculation span of the change amount ΔQ is 60 minutes. In the test on February 10th in Fig. 4, the fermentation heat amount obtained at 1-minute intervals was used, and the calculation span of the change amount ΔQ of the fermentation heat amount was set to 10 minutes, 60 minutes, 120 minutes, 180 minutes, 240 minutes, and 300 minutes, respectively. A correlation diagram of ΔQ and exhaust temperature is shown in Fig. 10. For example, in the case of a calculation span of 60 minutes, the calculation means obtains the fermentation heat amount every minute, and calculates the difference between the current fermentation heat amount (at the time of acquisition) and the fermentation heat amount 60 minutes ago as ΔQ.

[0062] As shown in Fig. 10, when the calculation span was 10 minutes and 60 minutes, it was relatively difficult to grasp the inflection point of the change amount ΔQ. On the other hand, when the calculation span was 120 minutes, 180 minutes, 240 minutes, and 300 minutes, the entire plot showed cyclicity, and the inflection point could be easily grasped. From the results of Fig. 10, the calculation span is preferably 120 minutes to 300 minutes, and more preferably 180 minutes to 240 minutes.

[0063] The fermentation drying method of the present invention includes a calculation step of calculating the amount of change in the amount of fermentation heat at any time interval of the fermentation drying apparatus, a judgment step of judging the timing at which the amount of change in the amount of fermentation heat changes from an increasing trend to a decreasing trend based on the calculated amount of change in the amount of fermentation heat, and an operation control step of making at least one of the items of the amount of outside air introduced into the container and the temperature of the outside air greater than the items before the timing was judged after the judgment step, and each of the above steps may be performed automatically using a means provided in the fermentation drying apparatus, such as a control device 15 (see FIG. 1), or all or part of the steps may be performed manually. In the latter case, for example, the calculation step and judgment step may be performed by the control device 15 of the fermentation drying apparatus, and the operation mode may be switched manually as the operation control step. [Industrial Applicability]

[0064] The fermentation and drying apparatus of the present invention can perform air intake control according to each of the fermentation and drying stages in the fermentation and drying process from the input to the removal of fermentation raw materials, and can carry out fermentation and drying efficiently, so it can be suitably used, for example, as an apparatus for fermenting and drying organic waste. [Explanation of symbols]

[0065] 1, 1' Fermentation and drying equipment 2 containers 2a Inlet 2b Outlet 2c Exhaust port 3 Rotation Axis 4, 4A, 4B Agitator blade 4a Ventilation hole 5 Machine room 6, 6A, 6B Air Blower 7 Heater 8 Hydraulic Cylinders 9 Exhaust means 10 Exhaust pipe 11 Exhaust Blower 12 Deodorizing equipment 13 Temperature Sensor 14 Control Panel 15 Control device 16A, 16B Filters

Claims

1. A closed fermentation and drying apparatus comprising a rotating shaft provided in a vessel and a plurality of stirring blades attached thereto, an air supply means for introducing outside air into the vessel, and an exhaust means for exhausting the inside air accumulated in the vessel to the outside of the vessel, The fermentation and drying apparatus is an apparatus for fermenting and drying a fermentation raw material while stirring it with the stirring blades, while introducing outside air into the container by the air supply means and exhausting internal air from the container by the exhaust means, The fermentation and drying apparatus has a calculation means for calculating a change in the amount of fermentation heat in a time interval of 60 to 300 minutes, a judgment means for judging a timing at which the amount of change in the amount of fermentation heat changes from an increasing trend to a decreasing trend based on the calculated change in the amount of fermentation heat, and an operation control means for performing an operation mode in which at least one of the amount of outside air introduced into the container and the temperature of the outside air introduced into the container is made larger than the item before the timing is judged by the judgment means, The fermentation and drying apparatus is characterized in that the judgment means calculates the slope of the change in the amount of fermentation heat, and judges the timing based on the condition that the slope is less than a threshold value and that at least one of the following is satisfied: the amount of fermentation heat is increasing at that point in time, and the temperature of the inside air is increasing.

2. The fermentation and drying apparatus according to claim 1, characterized in that, in the operation mode, the operation control means further increases at least one of the stirring frequency and the stirring speed of the stirring blades to a value greater than the value before the timing is determined.

3. The fermentation and drying apparatus according to claim 1 or claim 2, characterized in that the operation control means reduces at least one of the items of the amount of outside air introduced into the container, its temperature, the stirring frequency of the stirring blades, and its stirring speed during the period from after the timing is determined by the determination means to when the amount of change in the fermentation heat quantity becomes negative, compared to the items before the timing is determined.

4. A fermentation and drying method in a closed fermentation and drying apparatus comprising a rotating shaft provided in a vessel and a plurality of stirring blades attached thereto, an air supply means for introducing outside air into the vessel, and an exhaust means for exhausting the inside air accumulated in the vessel to the outside of the vessel, The fermentation and drying apparatus is an apparatus for fermenting and drying a fermentation raw material while stirring it with the stirring blades, while introducing outside air into the container by the air supply means and exhausting internal air from the container by the exhaust means, The fermentation and drying method includes a calculation step of calculating a change in the amount of fermentation heat in a time interval of 60 to 300 minutes, a determination step of determining a timing when the amount of change in the amount of fermentation heat changes from an increasing trend to a decreasing trend based on the calculated change in the amount of fermentation heat, and an operation control step of increasing at least one of the amount of outside air introduced into the container and the temperature of the outside air introduced into the container after the timing is determined by the determination step, compared to the item before the timing is determined; The fermentation and drying method is characterized in that the judgment step calculates the slope of the change in the amount of fermentation heat, and judges the timing based on the condition that the slope is less than a threshold value and that at least one of the following is satisfied: the amount of fermentation heat is increasing at that point in time, and the temperature of the inside air is increasing.

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