JPWO2019053855A1 - Organic waste treatment equipment and treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic waste treatment apparatus and a treatment method capable of reducing the water content of a dried product to 30% or less. An indirect heating type dryer 3 for drying an organic waste W and recovering the dried product, which is an indirect heating type dryer 3 for drying the organic waste W, and the indirect. It has a continuous hot air dryer 5 in which hot air is brought into contact with the organic waste W dried by the heating type dryer 3 to further dry the organic waste W.

Description

The present invention relates to an organic waste treatment apparatus and a treatment method.

In the process of treating organic waste, first, the organic waste is dehydrated using a dehydrator, and then the dehydrated product (organic waste after dehydration) is dried using a dryer. The dried organic waste (hereinafter referred to as "dried waste") is treated as landfill treatment or industrial waste, and has been effectively used as a fuel resource in recent years. In the drying process, the dried product and exhaust gas (heat medium gas or carrier gas) may be discharged from the dryer in a mixed state. This mixture is separated into powder or granular material and a separation gas using a solid air separator. Then, the separated gas is released to the atmosphere through a deodorizing step and a dust collecting step.

As a technique related to this, Patent Document 1 below discloses a sludge incineration facility in which sludge is dehydrated by a dehydrator, the dehydrated sludge is dried by a dryer, and then the dried sludge is incinerated in an incinerator. ..

JP-A-2005-279331

When burying dried organic sludge, or when using it as fertilizer or fuel, it may be required to reduce the water content of the dried product to 30% or less. It may be required that the water content be 10% or less. However, in order to reduce the water content to 30% or less, there is a problem that it is often difficult to combine a conventional dehydrator and a dryer.

Further, when the organic waste having high adhesiveness is supplied to the dryer, the organic waste may adhere to the inside of the dryer, the passage of the organic waste may be blocked, and continuous operation may become difficult. In order to prevent such blockage, the operation of the dehydrator is controlled or dehydrated so that the properties (particle size, adhesiveness, moisture content, etc.) of the organic waste supplied to the dryer are appropriate. It is necessary to adjust the type of drug to be injected into the machine and the injection rate.

However, since there is a limit to the control and adjustment of such a dehydrator, there is a problem that the desired properties may not be obtained no matter how much the control and adjustment are performed. In particular, depending on the type of organic waste, it is difficult to obtain organic waste with appropriate properties. For example, excess sludge has the characteristics of having a small amount of fibrous substances and a small particle size, so that it is generally difficult to dehydrate and it is difficult to adjust the properties of organic waste.

Furthermore, in order to make the properties of organic waste suitable for drying in a dryer (small particle size, low adhesion, low water content), a large amount of expensive chemicals are supplied to the dehydrator. There is also the problem that it is necessary and the running cost is high.

The above problem does not occur without the use of a dehydrator. Therefore, there is also a coping method of using only a dryer having a high drying capacity without using a dehydrator.
However, when the moisture content of the dried product is dried to 30% or less using, for example, a disc dryer, there is a problem that the speed of the disc being worn by the dried product in the drying process is high, and the maintenance cost and replacement cost of the dryer are high. is there.

Therefore, a main object of the present invention is to provide a treatment apparatus and a treatment method for organic waste capable of reducing the water content of the dried product to 30% or less.

The present invention that solves the above problems is as follows.
(1) An organic waste treatment device that dries organic waste and collects the dried product.
An indirect heating dryer that dries organic waste,
A continuous hot air dryer that brings hot air into contact with the organic waste dried by the indirect heating type dryer to further dry the organic waste.
An organic waste treatment device characterized by having.

(Action effect)
The processing apparatus according to the present invention has a configuration in which an indirect heating type dryer is arranged in the front stage and a continuous hot air dryer is arranged in the rear stage. With such a configuration, it becomes easier than before to reduce the water content of the dried product to 30% or less. Further, by adjusting the operating conditions of each dryer, it is possible to reduce the water content of the dried product to 10% or less.
In the present specification, the water content refers to the weight water content obtained by dividing the weight of water by the sum of the weight of water and the weight of solid content.

Further, by using the indirect heating type dryer, the particle size of the organic waste supplied to the continuous hot air dryer can be made small, the adhesiveness can be reduced, and the water content can be lowered. Therefore, it is possible to prevent the organic waste from adhering to the inside of the continuous hot air dryer and blocking the passage of the organic waste.

Further, since the processing device does not use only one disc dryer as described above, there is no problem that the wear rate of the disc is high.

(2) The organic waste treatment apparatus according to (1) above, wherein the indirect heating type dryer is a disk type dryer, a heating tube type dryer, or a centrifugal thin film type dryer.

(Action effect)
Disc-type dryers, heating tube-type dryers, and centrifugal thin-film dryers have high drying capacity for organic waste (high heat transfer capacity coefficient). Therefore, as compared with other dryers, it is easy to reduce the particle size of the organic waste, the adhesiveness, and the water content.

(3) The organic waste treatment apparatus according to (1) above, wherein the continuous hot air dryer is a circular tube type air flow dryer, a flow dryer, a band dryer or a straight tube type air flow dryer.

(Action effect)
Circular-tube airflow dryers and straight-tube airflow dryers have higher drying capacity (higher heat transfer capacity coefficient) than indirect heating dryers because the airflow directly hits organic waste. Therefore, it becomes easy to reduce the water content of the dried product to 30% or less.

Further, the circular tube type airflow dryer and the straight tube type airflow dryer have an advantage that the initial cost is lower than that of other dryers (for example, Steam Tube Dryer). Another advantage is that the floor area required to install the dryer is small.

(4) A hot air generator that generates hot air used in the continuous hot air dryer, and
A supply line that connects between the indirect heating type dryer and the hot air generator and supplies a part of the carrier gas discharged from the indirect heating type dryer to the hot air generator.
The organic waste treatment apparatus according to (1) above.

(Action effect)
Carrier gas is flowing in the indirect heating type dryer. This carrier gas is supplied to one end side of the dryer, flows toward the other end side with steam generated by drying the organic waste, and is discharged to the outside of the dryer from the other end side. The carrier gas discharged to the outside of the dryer is dehumidified by a dehumidifying device such as a scrubber, and then returned to one end side of the dryer again.

In the present invention, a part of the carrier gas discharged from the indirect heating type dryer is sent to the hot air generator and burned by the hot air generator. As a result, the load on the dehumidifying device such as a scrubber is reduced, so that the device can be miniaturized.

(5) A dehumidifying device that dehumidifies the carrier gas exhausted from the indirect heating type dryer, and
Further having a circulation path connecting the indirect heating type dryer and the dehumidifying device.
The circulation path
A first circulation path that supplies the carrier gas exhausted from the indirect heating type dryer to the dehumidifier, and
It has a second circulation path for supplying the dehumidifying carrier gas exhausted from the dehumidifying device to the indirect heating type dryer.
The organic waste treatment device according to (4) above, wherein the supply line is provided between at least one of the first circulation path or the second circulation path and the hot air generator.

(Action effect)
The carrier gas used in the indirect heating type dryer can be recycled by connecting the indirect heating type dryer and the dehumidifying device with a circulation path. That is, the carrier gas exhausted from the indirect heating type dryer is sent to the dehumidifying device via the first circulation path, and is dehumidified by the dehumidifying device. The dehumidified carrier gas is sent to the indirect heating type dryer via the second circulation path, and can be reused in the indirect heating type dryer.

However, there is a disadvantage that the odor concentration of the carrier gas gradually increases as this circulation is repeated. Therefore, in the present invention, at least one of the first circulation path and the second circulation path and the hot air generator are connected by a supply line. That is, a part of the carrier gas is extracted from the circulation path and burned by a hot air generator. Then, an amount of fresh gas corresponding to the extracted carrier gas (the amount does not have to be exactly the same as the extracted carrier gas, but may be approximately the same amount) is newly added to the circulation path. With such a configuration, it is possible to suppress an increase in the odor concentration of the carrier gas.

(6) A heat exchanger is provided in the supply line.
The treatment of organic waste according to (4) above, wherein the heat exchanger uses a part of the hot air generated by the hot air generator as a heat medium to heat the carrier gas passing through the supply line. apparatus.

(Action effect)
Since the carrier gas is sent from the indirect heating type dryer to the hot air generator through the supply line, the amount of hot air generated by the hot air generator increases as compared with the case where the supply line is not provided. That is, the amount of gas discharged from the hot air generator becomes larger than before, and surplus gas is generated, so that it is desired to make effective use of this.

In the present invention, the surplus gas is returned to the supply line to heat the carrier gas in the supply line. That is, by heating the carrier gas sent from the indirect heating type dryer to the hot air generator with the surplus gas, the load on the hot air generator can be reduced, which can lead to the saving of fuel and the like.

(7) A method for treating organic waste by drying the organic waste and recovering the dried product.
The first drying step of drying organic waste with an indirect heating dryer,
In the continuous hot air dryer, the second drying step of bringing the organic waste dried in the first drying step into contact with the organic waste to further dry the organic waste,
A method for treating organic waste, which is characterized by having.

(Action effect)
It has the same effect as (1) above.

(8) In the first drying step,
Organic waste with a moisture content of 60% to 90% is supplied to the indirect heating type dryer.
Using the indirect heating type dryer, the organic waste is dried so that the water content is 30% to 50%.
In the second drying step,
Organic waste with a moisture content of 30% to 50% is supplied to the continuous hot air dryer.
The method for treating organic waste according to (7) above, wherein the continuous hot air dryer is used to perform a drying treatment so that the water content of the organic waste is 40% or less.

(Action effect)
According to the present invention, the water content of organic waste can be reduced to 40% or less.

According to the organic waste treatment apparatus and treatment method according to the present invention, the water content of the dried product can be reduced to 30% or less.

It is a processing flow diagram of the organic waste processing apparatus which concerns on this invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description and drawings merely show one embodiment of the present invention, and the contents of the present invention should not be construed as being limited to this embodiment.

FIG. 1 is a treatment flow chart of the organic waste treatment apparatus 1. The processing device 1 includes a hot air generator 4, a continuous hot air dryer 5, a solid air separator 6, and the like. The configuration of the processing device 1 and the processing flow will be described in detail below.

(Organic waste W)
The treatment apparatus 1 according to the present invention treats the organic waste W. Examples of this organic waste are sewage sludge (including surplus sludge, initial sedimentation sludge, mixed raw sludge, mixed sludge, digested sludge, sludge mixed and digested with biomass, etc.), wastewater treatment sludge, papermaking sludge, activated sludge. , Building pit sludge, agricultural settlement sludge, and other organic sludge. Of these sludges, it is particularly suitable for treating sewage sludge. In addition, the organic waste W also includes wastes containing inorganic substances.

The organic waste W is stored in the organic waste storage tank 2 and is supplied to the indirect heating type dryer 3 by the supply pump 21.
Before supplying the organic waste W to the indirect heating type dryer 3, it may be dehydrated by a dehydrator (not shown). Dehydration by the dehydrator may be performed before the storage in the storage tank 2 or after the storage.
At this time, the water content of the organic waste supplied to the indirect heating type dryer is preferably 60% to 90%, more preferably 70 to 80%. Therefore, it is advisable to dehydrate with a dehydrator so as to have such a water content.

(Indirect heating type dryer 3)
The processing apparatus 1 according to the present invention has an indirect heating type dryer 3 for drying the organic waste W. In the form of FIG. 1, the organic waste W is dehydrated by the indirect heating type dryer 3 and then sent to the continuous hot air dryer 5.

Examples of the indirect heating type dryer 3 include an inclined disk dryer (inclined disk type dryer), a disk dryer, a centrifugal thin film dryer, a granulation dryer, a vertical steam indirect dryer and the like.

Among the above dryers, an inclined disk dryer is particularly suitable. The tilt disc dryer is mounted with the disc tilted with respect to the shaft. Further, usually, a plurality of shafts are arranged in parallel. Then, by rotating the disc, the organic waste adhering to the adjacent shaft or casing can be automatically scraped off. Further, the heat medium is supplied to the shaft and the casing, and the organic waste is indirectly heated by contacting the shaft and the casing heated to, for example, about 150 ° C. to 170 ° C. with the organic waste.

Therefore, the inclined disc dryer is highly energy efficient due to the effect of renewing the heat transfer surface by indirect heating or self-cleaning. In addition, since the amount of exhaust gas is smaller than that of the direct heating type dryer, the deodorizing device can be miniaturized.

The indirect heating type dryer 3 is provided with a carrier gas supply port for supplying carrier gas for discharging steam generated from organic waste in the drying process to the outside, and a carrier gas discharge port. In FIG. 1, a carrier gas supply port and a carrier gas discharge port are provided so that the moving directions of the carrier gas are opposite to the moving directions of the organic waste. That is, the carrier gas flows from the right side to the left side of the drawing, while the organic waste moves from the left side to the right side of the drawing. The flow of the carrier gas is not limited to the countercurrent method as described above, and may be a parallel flow method in which the moving direction of the carrier gas and the moving direction of the organic waste are the same.
When the organic waste W dries, vapor with an odor is generated. The carrier gas flows from one end side having the carrier gas supply port to the other end side having the carrier gas discharge port together with this steam, and is exhausted from the other end side to the outside of the indirect heating type dryer 3.

By using an indirect heating type dryer, the water content of organic waste can be reduced. For example, when an inclined disk dryer is used, the water content of the organic waste after drying can be set to about 50% to 30%. When organic waste is dehydrated using a dehydrator (for example, a two-component tempering type centrifugal dehydrator), the water content of the dehydrated product is often about 80% or more, so an indirect heating type dryer is used. The benefits are clear.

Further, the properties of organic waste suitable for drying of the continuous hot air dryer 5 have various factors such as viscosity, but for long-term continuous operation of the continuous hot air dryer, organic waste is used. It is important to reduce the particle size of the object. This is because if the particle size of the organic waste is small, the weight is inevitably light and it becomes easy to carry it with hot air in the dryer. Specifically, the maximum particle size is preferably 60 mm or less, and more preferably 30 mm or less. The average particle size is preferably 1 mm to 30 mm, more preferably 1 mm to 5 mm.

(Conveyor 7)
The organic waste discharged from the indirect heating type dryer 3 (hereinafter, referred to as “indirect dry matter”) is supplied to the conveyor 7. The water content of the indirect dried product is preferably 30% to 50%, more preferably 35% to 40%. As for the performance of the indirect heating type dryer / dryer 3, it is possible to set the water content to 30% or less, but if it is less than 30%, the disc wears rapidly, which is not preferable.
In FIG. 1, the indirect heating type dryer 3 and the conveyor 7 are connected by the pipe 30, and the indirect dried product moves to the transporter 7 through the inside of the pipe 30. Further, a moisture meter AM is attached to the pipe 30 to measure the amount of moisture contained in the indirect dry matter.

As the conveyor 7, a screw conveyor, a belt conveyor, or the like that transports by mechanical power can be used. In FIG. 1, a screw conveyor is used as the conveyor 7. Further, a supply port is provided in the middle portion (near the center) in the longitudinal direction of the screw conveyor 7 of FIG. 1, and indirect dried products are supplied into the screw conveyor 7 from this supply port.
For the purpose of reducing the initial cost, the indirect dried product may be directly charged from the indirect heating type dryer 3 to the continuous hot air dryer 5 without providing the conveyor 7.

(Indirect dry matter supply method)
When supplying the indirect dried product to the continuous hot air dryer 5, the amount of the indirect dried product supplied to the continuous hot air dryer 5 (kg-ds / min) is set to X, and the indirect dried product of the continuous hot air dryer is set to X. When the holding amount (kg-ds) of is Y, the average residence time T of the indirect dried product defined by the following formula 1 staying in the continuous dryer is within the range of 0.05 to 10 minutes. It is preferable to supply to the continuous hot air dryer 5.
T = Y / X ・ ・ ・ Equation 1
The residence time T is preferably in the range of 0.1 to 7 minutes, and more preferably in the range of 0.2 to 5 minutes.
By keeping the amount of the indirect dried product supplied to the continuous hot air dryer 5 within the above range, the time for the indirect dried product to stay in the continuous hot air dryer 5 becomes an appropriate value, and a foul odor is generated from the final product. Can be suppressed.

(Maximum particle size)
The transporter 7 can be provided with a measuring means for measuring the particle size of the indirect dried product. As a result of measuring the particle size of the indirect dried product, if the maximum particle size of the indirect dried product is higher than the standard value, the indirect dried product is sent to the organic waste storage tank 2, and if it is less than the standard value, the indirect dried product is indirectly dried. The object is sent to the continuous hot air dryer 5. The reference value can be determined arbitrarily, but if the maximum particle size of the indirect dried product is larger than 60 mm, it is sent to the digestion tank 20, and conversely, if the maximum particle size of the indirect dried product is 60 mm or less, continuous hot air drying is performed. It is preferable to send it to the machine 5.

When an indirect dried product having a maximum particle size of larger than 60 mm is supplied to the continuous hot air dryer 5, there is a high possibility that the indirect dried product adheres to or accumulates in the continuous hot air dryer 5. When the amount of sediment exceeds a certain amount, it becomes necessary to temporarily stop the operation of the continuous hot air dryer 5 and artificially discharge the sediment. In the present invention, long-term continuous operation of the continuous hot air dryer 5 is realized by not supplying an indirect dried product having a maximum particle size of more than 60 mm.

For the measurement of the maximum particle size of organic waste, for example, a part of the indirect dried product is artificially extracted as a sampling and measured using a caliper or the like, and the maximum diameter of the measured value is set as the maximum particle size.

When the indirect heating type dryer 3 is used, the indirect dried product tends to be in uniform particles (granular substances), and the maximum particle size and the average particle size can be easily measured. By granulating the indirect dried product, it becomes easy to stably supply the indirect dried product to the continuous hot air dryer 5. Further, when the indirect dried product is granular, the resistance to the hot air flowing in the continuous hot air dryer 5 is reduced, and there is an advantage that the chance of contact between the hot air and the indirect dried product can be increased.

In some cases, the indirect dried product is not homogeneously granular, that is, the indirect dried product is agglomerated by moisture or the like. Even if there is an indirect dried product (lump product) that is agglomerated in this way, it can be supplied to the continuous hot air dryer 5.

(Average particle size)
The average particle size is measured by, for example, the following method. When the particle size of the indirect dried product is 500 microns or more, it is sifted by the method described in JIS (Japanese Industrial Standards) M 8801 coal test method, and the sieving result is represented by the rosin Ramler distribution, and the integrated mass (on the sieve) is The particle size when it corresponds to 50% is defined as the average particle size. When the particle size of the indirect dried product is less than 500 microns, the particle size distribution is measured using a laser diffraction type particle size distribution measuring device (trade name SALD-3100, manufactured by Shimadzu Corporation), and the cumulative volume corresponds to 50%. The particle size at the time is defined as the average particle size.

The measurement method according to the JIS (Japanese Industrial Standards) disclosed in the present specification is merely an example, and the measurement method is not limited to this measurement method when defining the technical scope of the patented invention. If so, you will fully understand this.

The average particle size of the indirect dried product may be measured, and if the average particle size is 1 mm to 30 mm, it may be sent to the continuous hot air dryer 5, and if it is outside the range, it may be sent to the digestion tank 20. If the average particle size is larger than 30 mm, the continuous hot air dryer 5 may not be sufficiently dried and discharged, and the water content of the final product may exceed 30%. Further, if the average particle size is larger than 30 mm, there is a high possibility that the indirect dried product adheres to or accumulates in the continuous hot air dryer 5.

(Particle size distribution)
In order to stabilize the operation of the continuous hot air dryer 5, it is preferable to reduce the fluctuation of the particle size distribution of the indirect dried product supplied per unit time. This is because a problem occurs when the value of the particle size distribution changes widely. Specifically, when the value of the particle size distribution of the indirect dried product becomes wide, the moisture content of the dried product (hereinafter referred to as “hot air dried product”) discharged from the continuous hot air dryer 5 tends to be non-uniform, and the particle size tends to be uneven. When the value of the distribution is narrow and uniform, the moisture content of the hot air dried product tends to be uniform.

(Other)
A crusher (not shown) may be provided as a preliminary facility between the conveyor 7 and the continuous hot air dryer 5. When the maximum particle size or the average particle size of the indirect dried product is large, it may be crushed by this crusher to a desired size, and then supplied to the continuous hot air dryer 5. In this case, the particle size of the granules after crushing may be measured, it may be determined whether the maximum particle size or the average particle size is desirable, and whether or not the particles may be supplied to the continuous hot air dryer 5 may be determined.

A method of providing an indirect dry matter storage facility (not shown) between the conveyor 7 and the continuous hot air dryer 5 and periodically sending the indirect dry matter from the storage facility to the continuous hot air dryer 5 is also considered. be able to.

(Circulation route 25)
The carrier gas used in the indirect heating type dryer 3 circulates between the indirect heating type dryer 3 and the dehumidifying device 11A. The carrier gas circulation path 25 has a first circulation path 25A and a second circulation path 25B.

Specifically, the carrier gas (saturated gas) exhausted from the indirect heating type dryer 3 is supplied to the dehumidifying device 11A through the first circulation path 25A to be dehumidified. The dehumidified carrier gas is supplied to the indirect heating type dryer 3 again through the second circulation passage 25B. With these configurations, the carrier gas supplied to the indirect heating type dryer 3 can be circulated and used.

As the dehumidifier 11A, for example, a scrubber, a mechanical dehumidifier, and a heat exchanger (shell & tube type, plate type, etc., which perform gas / gas exchange or liquid / gas exchange) can be used. .. The same applies to the dehumidifying device 11B.
Further, the second circulation passage 25B is provided with a fan 12 for supplying the dehumidified carrier gas to the indirect heating type dryer 3. It is also possible to provide the fan 12 in the first circulation passage 25A together with the fan of the second circulation passage 25B or in place of the fan of the second circulation passage 25B.

The temperature of the carrier gas discharged from the dehumidifying device 11A has dropped to, for example, about 40 ° C.

By recycling the carrier gas as described above, there is a disadvantage that odorous components (hydrogen sulfide, ammonia, methyl mercaptan, methyl sulfide, etc.) contained in the carrier gas are gradually concentrated in the drying process.

Therefore, a part of the carrier gas (exhaust gas) discharged from the indirect heating type dryer 3 is supplied to the hot air generator 4. By extracting a part of the circulating carrier gas, sending it to the hot air generator 4, and burning it in the hot air generator 4, it is possible to remove the odor without newly installing a deodorizing device.

As a specific configuration, in the processing apparatus 1 shown in FIG. 1, the supply line 40 communicates between the second circulation path 25B and the hot air generating furnace 4.
In addition, a supply line 40 may be used to communicate between the first circulation path 25A and the hot air generator 4. By connecting the supply line 40 to the first circulation path 25A, the amount of carrier gas supplied to the dehumidifying device 11A can be reduced. Therefore, the dehumidifying device 11A can be miniaturized, and the initial cost of the processing device 1 can be reduced.
In order to control the flow rate of the carrier gas passing through the supply line 40, it is preferable to provide a flow rate adjusting valve (not shown) on at least one of the supply line 40 or the circulation path 25 (25A or 25B).

On the other hand, since a part of the carrier gas is sent to the hot air generator 4, there is a disadvantage that the amount of carrier gas is reduced. Therefore, it is preferable to connect a pipe (not shown) for newly introducing outside air to the carrier gas circulation path 25 (25A or 25B).
Further, the inside of the indirect heating type dryer 3 has a negative pressure. Therefore, when the conveyor 7 is provided, new air flows back from the pipe connecting the indirect heating dryer 3 and the conveyor 7 and flows into the indirect heating dryer 3, so that this is used as the carrier gas. You may use it.

(Hot air generator 4)
The indirect dried product discharged from the indirect heating type dryer 3 is sent to the continuous hot air dryer 5, and is dried in contact with the hot air in the continuous hot air dryer 5. The hot air used in the continuous hot air dryer 5 is generated by the hot air generator 4. Specifically, the burner 4A supplied with fuel F (LPG or the like) from a fuel tank (not shown) heats the compressed air sent from the storage tank 18 for storing the compressed air generated by the air compressor 17. Generates hot air. When the organic waste W is sludge, the digestion gas generated when the sludge is digested may be used as the fuel F. The control of the hot air generator 4 measures the outlet temperature of the hot air generator 4 and controls the amounts of fuel F and air A supplied to the hot air generator 4 so as to reach a target temperature.

The hot air temperature is not particularly limited, but it is preferable that the hot air temperature is 250 ° C. to 500 ° C. By using hot air in this range, the moisture content of the hot air dried product can be reduced to 30% or less, preferably 10% or less.

The hot air temperature is more preferably 350 ° C. to 450 ° C., further preferably 390 ° C. to 410 ° C., and most preferably 400 ° C. When the hot air temperature is low, the indirect dried product cannot be sufficiently dried, and the water content of the hot air dried product becomes high. On the other hand, when the hot air temperature is high, the fuel cost of the hot air generator 4 increases and the economy becomes poor. Therefore, considering the economic balance between the water content of the dried product and the fuel cost, it is most appropriate to set the temperature to around 400 ° C.

(Continuous hot air dryer 5)
The continuous hot air dryer 5 brings the indirect dried product from the indirect heating type dryer 3 into contact with the hot air from the hot air generator 4 to dry the indirect dried product into powder or granular material.

Generally, an indirect heating type dryer (stirring heat transfer type device) is often used, but in the present invention, it is preferable to use the continuous hot air dryer 5.
The continuous hot air dryer 5 includes (1) a spray dryer, an air flow dryer, a fluidized layer dryer, a rotary dryer, and the like, in which an indirect desiccant is dispersed and dried in hot air. 2) Transfer the indirect desiccant in a stationary state, such as a ventilation band dryer, tunnel dryer (parallel flow band dryer), spout flow dryer, etc., and blow hot air to the indirect desiccant during the transfer process. Illustrate a form in which the indirect dried product is mechanically agitated and hot air is brought into contact with the indirect dried product to be dried, such as (3) a stirring dryer or the like. Can be done. The "continuous type" of the continuous type hot air dryer 5 means that it can be operated continuously.

Of the continuous hot air dryers 5, it is preferable to use the airflow dryer 5F. This is because it is inexpensive and has excellent maintainability.

There are various types of airflow dryer 5F, but if the organic waste W is dried using the indirect heating type dryer 3, the adhesiveness of the indirect dried product can be weakened. An airflow dryer 5F without a crusher for crushing can be used.

FIG. 1 shows an example of the airflow dryer 5F. The airflow dryer 5F is a circular tube type airflow dryer 5CF in which pipes through which hot airflow passes (hereinafter, also referred to as “pipes”) are arranged in an annular shape. The illustrated circular tube type air flow dryer 5CF has a pipe 5a to which the hot air sent from the hot air generator 4 first arrives, a pipe 5b extending upward from the pipe 5a, and a direction of turning back from the pipe 5b. It is composed of a pipe 5c extending horizontally and a pipe 5d extending downward from the pipe 5c. An R-shaped curved pipe is located between the adjacent pipes (for example, between the pipes 5a and 5b). The lower end of the pipe 5d is joined to the left end of the pipe 5a, and the insides of the pipes are connected to each other at this joint. An indirect dry matter supply port 5X is provided in the middle portion of the pipe 5a, and a dry matter discharge port 5Y is provided in the middle portion of the pipe 5d.

The hot air generated by the hot air generator 4 is supplied to the pipe 5a. At the same time, the indirect dried product conveyed by the conveying means 7 falls from the supply port 5X into the hot air (hot air flow) of the pipe 5a. The dropped indirect dry matter is dispersed in powder particles in hot air. Then, the powder or granular material is instantaneously dried while being sent in parallel with the hot air flow (while being carried by the hot air in the air flow). Specifically, the hot air accompanied by the powder or granular material flows in the order of pipe 5a, pipe 5b, pipe 5c, and pipe 5d, and a part of the hot air is exhausted from the discharge port 5Y to the outside of the vessel. On the other hand, the indirect dry matter not exhausted from the discharge port 5Y merges with the hot air newly sent from the hot air generator 4, flows again to the pipes 5a, 5b, 5c, and 5d, and a part of them is exhausted. Exhaust to the outside of the device from outlet 5Y. As described above, a part of the hot air is exhausted from the discharge port 5Y, and the other hot air circulates in the pipes 5a to 5d. In this way, the newly introduced indirect dry matter and the indirect dry matter circulating in the pipe are mixed in the pipe, whereby the adhesiveness and the water content are adjusted. That is, in the circular tube type airflow dryer 5CF, the indirect dried product is dried by absorbing the heat in the hot air. Therefore, this circular tube type air flow dryer 5CF has a structure that is fundamentally different from that of an indirect heating type dryer or the like that dries by contacting an indirect dried product with a heated pipe.

The indirect dried product immediately after being supplied to the circular tube type airflow dryer 5CF often flows on the outer peripheral side of each of the pipes 5a to 5d due to the influence of centrifugal force. Then, as the drying of the indirect dried product progresses, the agglomerated state of the indirect dried product is dissolved and the average particle size becomes smaller, so that the indirect dried product flows on the inner peripheral side of each of the pipes 5a to 5d and is discharged inside the pipe 5d. It is discharged from the outlet 5Y.

In the operation of the circular tube type airflow dryer 5CF, it is preferable that the wind speed of the hot air in each pipe 5a to 5d is 10 m / s or more. More preferably, it is preferably 15 m / s or more in order to smoothly convey the indirect dried product by hot air. More preferably, the indirect dry matter supplied from the supply port 5X is made to collide with the circulating hot air at high speed, so that the indirect dry matter can be dispersed in the hot air. Therefore, the temperature is preferably 20 m / s or more.

In FIG. 1, a circular tube type airflow dryer 5CF in which pipes 5a to 5d are formed in an annular shape is shown. However, the continuous hot air dryer 5 is not limited to the annular airflow dryer 5F, and may be a straight pipe type airflow dryer 5LF in which all pipes are arranged in a straight line or a substantially linear shape. The circular airflow dryer 5CF is superior to the straight tube airflow dryer 5LF in that the installation space is smaller. However, even with the straight pipe type airflow dryer 5LF, the installation space can be reduced when the pipes are extended in the height direction.

Even if the size of the circular tube type airflow dryer 5CF is increased or decreased, there is almost no change in the residence time in which the indirect dried product stays in the dryer 5CF.

A stirring heat transfer dryer may be used instead of the continuous hot air dryer 5, or an air flow dryer with a crusher may be used as the continuous hot air dryer 5. An indirect heating dryer (steam tube dryer) may be provided instead of the continuous hot air dryer 5, but the initial cost is overwhelmingly low, the ground contact area of the equipment is not taken, and the delivery time is shortened. Therefore, the continuous hot air dryer 5 (particularly, the circular tube type air flow dryer 5CF and the straight tube type air flow dryer 5LF) is preferable.

In the continuous hot air dryer 5 of the present invention, the heat capacity coefficient obtained from the size of the continuous hot air dryer 5 and the temperature and amount of the supplied hot air gas is in the range of 2000 to 4000 kcal / m ³ h ° C. It is preferable to use the dryer 5. The higher the heat capacity coefficient, the more heat energy can be transferred to the sludge, and that energy can be used to evaporate the water content of the sludge. Since the circular tube type air flow dryer 5CF has an extremely high heat capacity coefficient as compared with an indirect heating type dryer such as an inclined disk type dryer, sufficient drying can be performed with a short residence time.

As described above, by using the organic waste W treatment device 1 provided with the indirect heating type dryer 3 and the continuous hot air dryer 5, the water content of the final product (powder and granular material after solid air separation) Can be significantly lower than before. Specifically, the water content can be 40% or less. Depending on the operating conditions (for example, control such as raising the hot air temperature to a high temperature), it can be reduced to 30% or less or 10% or less.

(Heat retention means)
It is preferable that the continuous hot air dryer 5 is provided with heat insulating means (not shown) around each of the pipes 5a to 5d. By providing this heat retaining means, it is possible to prevent the occurrence of dew condensation in the continuous hot air dryer 5, and it is possible to stably discharge the dried product. Examples of this heat retaining means include a heat insulating sheet and a heating tube. Further, in order to prevent dew condensation, it is preferable to provide the same heat retaining means in the piping between the continuous hot air dryer 5 and the solid air separator 6.

(Solid air separator 6)
The hot air whose humidity has increased due to the drying of the powder or granular material is exhausted as exhaust gas from the continuous hot air dryer 5 and sent to the solid air separator 6. Since this exhaust gas contains powder or granular material, it is separated into powder or granular material and a separated gas (gas separated from the powder or granular material) by using a solid air separator 6.

By using the airflow dryer 5F (circular tube type airflow dryer 5CF or straight tube type airflow dryer 5LF), it is possible to carry the powder and granules from the airflow dryer 5F to the solid air separator 6 with hot air. There is an advantage that it can be done. That is, since it is not necessary to provide a transport means (conveyor or the like) for transporting the powder or granular material from the air flow dryer 5F to the solid air separator 6, the initial cost of the processing device 1 as a whole can be reduced.

Examples of the solid air separator 6 include a cyclone that collects dust by centrifugal force, a gravity settling chamber that collects dust by gravity, a mist separator that collects dust by inertia, a bag filter that collects dust by a filter cloth, and filling. A moving particle layer air filter that collects dust by a layer, an electrostatic precipitator that collects dust by electricity, or the like can be used.

(Exhaust treatment)
The separated gas separated from the powder or granular material by the solid air separator 6 is dedusted by a dehumidifying device 11B (for example, a venturi scrubber) that collects dust by washing, and then sucked by a fan 12 to be sucked by a deodorizing device (for example, for example). It is deodorized by the plasma deodorizer) 13. The deodorized separated gas is dissipated into the atmosphere E from the chimney 14 provided in the upper part of the dehumidifying device 11B. The method for treating the separated gas discharged from the solid air separator 6 is not limited to the above contents, and each facility may be appropriately changed.

(Return line 43)
A pipe is connected between the exhaust port from the solid air separator 6 and the air supply port of the hot air generator 4, and a part of the exhaust gas exhausted from the solid air separator 6 is returned to the hot air generator 4 to be returned to the hot air generator 4. It may be deodorized by burning in 4. By performing such a return, the amount of exhaust gas processed by the dehumidifying device 11B and the dehumidifying device 13 in the subsequent stage is reduced, so that the dehumidifying device 11B can be miniaturized and the filtration filter used in the dehumidifying device 13 can be replaced. The parts can be saved.

The return of the return line 43 is performed using, for example, a fan 12C.
Since a part of the carrier gas is sent to the hot air generator 4 by the supply line 40, the amount of exhaust gas returned by the return line 43 is small. This is because the amount of air required by the hot air generator 4 is fixed.
Therefore, by providing the supply line 40, as a result, the flow rate of the fan 12C of the return line can be reduced, and the initial cost can be reduced by downsizing the fan 12C.

(Heating line 41)
The amount of gas supplied to the hot air generator 4 by the supply line 40 and the return line 43 increases, and as a result, the amount of hot air blown from the hot air generator 4 to the continuous hot air dryer 5 increases. However, since the amount of hot air required by the continuous hot air dryer 5 is naturally determined by the operating conditions of the continuous hot air dryer 5, the hot air generated by the hot air generator 4 may not be required in some cases.

In the present invention, in order to effectively utilize the hot air that is not used in the continuous hot air dryer 5, a pipe is provided to return a part of the hot air exhausted from the exhaust port of the hot air generator 4 to the supply line 40. The hot air returned by this pipe warms the carrier gas of the supply line 40. As a result, the temperature of the carrier gas sent to the hot air generator 4 becomes high, so that the fuel F used in the hot air generator 4 can be saved.

In FIG. 1, the hot air passing through the heating line 41 is exhausted to the atmosphere E after the carrier gas passing through the supply line 40 is heated by the heat exchanger 42A.

However, the present invention is not limited to such a form, and the piping of the heating line 41 and the piping of the supply line 40 are joined, and the hot air returned by the heating line 41 merges with the carrier gas flowing through the supply line 40 and becomes a carrier gas. The hot air may be configured to be sent to the hot air generator 4 together.
The heating line 41 may be provided with a flow rate control valve (not shown) for controlling the flow rate of hot air passing through the heating line 41.

(Auxiliary heating line 45)
An auxiliary heating line 45 may be provided for the purpose of effectively utilizing the hot air exhausted from the hot air generator 4. The hot air passing through the auxiliary heating line 45 is exhausted to the atmosphere E after the return gas passing through the return line 43 is heated by the heat exchanger 42B.

(Hot air flow control)
The hot air exhausted from the hot air generator 4 is supplied to the heating line 41, the auxiliary heating line 45, and the continuous hot air dryer 5. At this time, it is preferable to provide a flow rate control means for controlling the amount of hot air supplied to each supply destination. Specifically, a flow rate adjusting valve is provided in the hot air supply line 46 connecting the hot air generator 4 and the continuous hot air dryer 5, the heating line 41, and the auxiliary heating line 45, and the flow rate is adjusted by adjusting the opening degree thereof. It is good to control. The flow rate adjusting valve may be installed in at least two flow paths of the hot air supply line 46, the heating line 41, and the auxiliary heating line 45.

(White smoke prevention line 44)
A white smoke prevention line 44 may be provided for the purpose of effectively utilizing the hot air exhausted from the hot air generator 4. The piping constituting the white smoke prevention line 44 is connected to a chimney 14 provided in the upper part of the dehumidifying device 11B, and the gas discharged to the atmosphere E is warmed to suppress the generation of white smoke. Can be done.

(Retention of powder and granules)
The powder or granular material accumulated at the lower end of the solid air separator 6 is cut out by the rotary valve 19 and then supplied to the powder or granular material upstream transporter 9 through the pipe 31. If the water content of the powder or granular material at the lower end of the solid air separator 6 is high, the powder or granular material may adhere to the valve and the discharge may not be successful. Therefore, it is preferable to use a rotary valve 19 that is scraped out by a rotary blade.

Further, in the illustrated embodiment, a moisture meter AW is provided in the pipe 31 to measure the water content of the powder or granular material passing through the pipe 31. If the measured moisture content is out of the appropriate range, control such as raising the temperature of the hot air supplied from the hot air generator 4 to the continuous hot air dryer 5 is performed.

As the powder or granular material upstream transporter 9, a screw conveyor, a belt conveyor, or the like that transports by mechanical power can be used. In the illustrated form, a screw conveyor composed of biaxial screws is used. By using a biaxial screw conveyor, the powder or granular material adhering to one shaft can be scraped out by the other rotating blade.

In the screw conveyor 9, the supply port for the powder or granular material is provided in the middle portion in the longitudinal direction of the screw conveyor 9, and the discharge port for the powder or granular material is one end side end in the longitudinal direction of the screw conveyor 9 (right side in the drawing) and others. It is provided at the end side (left side of the drawing). The powder or granular material supplied from the supply port is carried to one end side end by the forward rotation of the screw conveyor 9, and is discharged from the discharge port at one end side end. On the contrary, when the screw conveyor 9 rotates in the reverse direction, the powder or granular material is carried to the other end side end and discharged from the discharge port at the other end side end. In order to store the powder or granular material in a plurality of containers 15 arranged downstream in a well-balanced manner, the screw conveyor 9 is rotated forward for a certain period of time and then rotated in the reverse direction for the same time. It is preferable that the amount of powder or granular material discharged from one end side end and the amount of powder or granular material discharged from the other end side end are the same amount.

The temperature of the powder or granular material supplied to the screw conveyor 9 is as high as about 65 ° C to 90 ° C. Therefore, it is preferable to make the screw conveyor 9 water-cooled in order to remove the rough heat of the powder or granular material and lower it to about 65 ° C. Specifically, the powder or granular material is cooled from both the outside and the inside by flowing cooling water to the outside of the jacket of the screw conveyor 9 and also flowing water to the inside of the shaft.

The powder or granular material discharged from each discharge port (one end side discharge port and the other end side discharge port) of the screw conveyor 9 passes through the pipe 32 and is supplied to separate powder or granular material downstream conveyors 10. Each of the illustrated powder or granular material downstream conveyors 10 is a uniaxial screw conveyor 10 and has the same structure as the powder or granular material upstream conveyor 9 except that it does not have a cooling function and is a uniaxial screw.

When the screw conveyor 10 rotates in the forward or reverse direction, the powder or granular material is distributed to one end side and the other end side of the screw conveyor 10. Then, the powder or granular material discharged from the one end side discharge port or the other end side discharge port is stored in each container 15 (four containers in the figure) through the pipe 33. In this way, the powder or granular material is distributed to the plurality of containers 15 by using the screw conveyor 10 to prevent the containers 15 from being filled up immediately.

The temperature of the powder or granular material stored in the container 15 may rise due to oxygen or carbon monoxide in the container 15. Therefore, it is preferable to attach a thermometer to the container 15 to monitor the temperature from the outside and supply nitrogen into the container 15 from a nitrogen tank (not shown). Further, a mechanism for dropping water may be provided in the container 15 in case the temperature suddenly rises.

(Method of treating organic waste)
The present invention also provides a method for treating organic waste W by drying the organic waste W and recovering powders and granules which are final products. The treatment method includes a first drying step of drying the organic waste W by the indirect heating type dryer 3 and hot air to the indirect dried product dried in the first drying step inside the continuous hot air dryer 5. It has a second drying step in which the indirect dried product is further dried.

In this treatment method, a part of the carrier gas circulating between the indirect heating type dryer 3 and the dehumidifying device 11A is extracted between the first drying step and the second drying step, and the carrier gas supplied to the hot air generator 4 is supplied. A supply process may be provided.

The hot air generated by the hot air generator 4 is used in the continuous hot air dryer 5, but the amount of hot air generated may be more than necessary due to the provision of the supply process. Therefore, in such a case, between the supply step and the second step, a heating step of returning a part of the hot air generated by the hot air generator 4 to the supply line 40 to heat the carrier gas of the supply line 40 is performed. It may be provided.

In addition, after the second drying step, a separation step of separating the hot air dried product into a solid (powder / granular material) and a gas using the solid air separator 6 can be provided. Further, after the separation step, a return step may be provided in which a part of the gas discharged from the solid air separator 6 is sent to the hot air generator 4.

After the return step, a part of the hot air generated by the hot air generator 4 may be returned to the return line 43 to provide an auxiliary heating step for warming the gas in the return line 43.

1: Processing equipment 2: Organic waste storage tank 3: Indirect heating type dryer 4: Hot air generator 5: Continuous hot air dryer 5F: Air flow dryer 5CF: Circular pipe type air flow dryer , 5LF: Straight pipe type air flow dryer, 5a to 5d: Pipe, 5X: Supply port, 5Y: Discharge port, 6: Solid air separator, 7: Conveyor, 8: Measuring device, 9: Powder and granule upstream transfer Machine, 10: Powder and granule downstream transporter, 11: Dehumidifier, 12: Fan, 13: Deodorizer, 14: Chimney, 15: Container, 17: Air compressor, 18: Storage tank, 19: Rotary valve, 20 : Digestion tank, 21: Supply pump, 31-33: Piping, 40: Supply line, 41: Heating line, 42: Heat exchanger, 43: Return line, 44: White smoke prevention line, 45: Auxiliary heating line, 46 : Hot air supply line, AM: Moisture meter, E: Atmosphere, F: Fuel, M: Motor, W: Organic waste

Claims (8)

An organic waste treatment device that dries organic waste and collects the dried product.
An indirect heating dryer that dries organic waste,
A continuous hot air dryer that brings hot air into contact with the organic waste dried by the indirect heating type dryer to further dry the organic waste.
An organic waste treatment device characterized by having. The organic waste treatment apparatus according to claim 1, wherein the indirect heating type dryer is a disk type dryer, a heating tube type dryer, or a centrifugal thin film type dryer. The organic waste treatment device according to claim 1, wherein the continuous hot air dryer is a circular tube type air flow dryer, a flow dryer, a band dryer, or a straight tube type air flow dryer. A hot air generator that generates hot air used in the continuous hot air dryer,
A supply line that connects between the indirect heating type dryer and the hot air generator and supplies a part of the carrier gas discharged from the indirect heating type dryer to the hot air generator.
The organic waste treatment apparatus according to claim 1, further comprising. A dehumidifying device that dehumidifies the carrier gas exhausted from the indirect heating dryer,
Further having a circulation path connecting the indirect heating type dryer and the dehumidifying device.
The circulation path
A first circulation path that supplies the carrier gas exhausted from the indirect heating type dryer to the dehumidifier, and
It has a second circulation path for supplying the dehumidifying carrier gas exhausted from the dehumidifying device to the indirect heating type dryer.
The organic waste treatment device according to claim 4, wherein the supply line is provided between at least one of the first circulation path or the second circulation path and the hot air generator. A heat exchanger is provided in the supply line.
The organic waste treatment apparatus according to claim 4, wherein the heat exchanger uses a part of the hot air generated by the hot air generator as a heat medium to heat the carrier gas passing through the supply line. .. A method of treating organic waste by drying the organic waste and recovering the dried product.
The first drying step of drying organic waste with an indirect heating dryer,
In the continuous hot air dryer, the second drying step of bringing the organic waste dried in the first drying step into contact with the organic waste to further dry the organic waste,
A method for treating organic waste, which is characterized by having. In the first drying step,
Organic waste with a moisture content of 60% to 90% is supplied to the indirect heating type dryer.
Using the indirect heating type dryer, the organic waste is dried so that the water content is 30% to 50%.
In the second drying step,
Organic waste with a moisture content of 30% to 50% is supplied to the continuous hot air dryer.
The method for treating organic waste according to claim 7, wherein the continuous hot air dryer is used to perform a drying treatment so that the water content of the organic waste is 40% or less.

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