JPH0222080Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention is an aeration method for energy-saving drying of sludge and other granular and lumpy water-containing solids generated in the treatment of wastewater such as sewage, human waste, and various industrial wastewater. This relates to a drying device.

[Prior art]

In conventional ventilation drying equipment (the typical model is the ventilation band dryer), the discharge pressure of the blower that supplies warm air for drying is several hundred mmAq or less. The amount of gas leaking from the discharge section is not a problem, and as a result, rotary valves, screw feeders, etc. can be used with gas-sealing properties without requiring any special modifications to the structures of the wet solid material supply section and dry material discharge section. This could easily be countered by an insufficient opening/closing mechanism.

[Problem that the invention attempts to solve]

However, the compression heat (temperature 60-80
When attempting to dry water-containing solids using a temperature of approximately
The pressure is about 0.6 to 0.7 Kgf/cm ² . No conventional ventilation drying device can handle such high-pressure hot air or other high-pressure hot air. Therefore, there is a need to develop a new type of aeration drying device that can efficiently utilize the heat retained in compressed air or other high-pressure hot air discharged from an aeration blower.

This invention makes it possible to efficiently utilize the air discharged from an aeration blower and other high-pressure hot air, which was not applicable to conventional aeration drying equipment, and enables not only batch drying but also continuous processing without the problem of gas leaks.
We provide a new type of ventilation drying equipment that improves heat utilization efficiency and simplifies operation, and can always obtain dried products with a moisture content below the target moisture content even if the moisture content of the hydrated solids to be dried fluctuates. This is what I am trying to do.

[Means for solving problems]

In the present invention, the bottom part is formed into an inverted conical shape, the top part and the water-containing solid material supply part above the top part are connected through valves arranged facing each other with a space interposed therebetween, and the bottom part is provided with a space part. a first dryer provided with a discharge section consisting of facing valves, further having a first exhaust port opened at the top and a first warm air supply port opened at the bottom;
It consists of a second dryer having a second exhaust port at the top, a second hot air supply port at the bottom, and an exhaust port at the bottom, and the top of the second dryer is connected to the first dryer. This is a ventilation drying device characterized by being connected to a discharge section.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a first dryer wrapped with a heat insulating material, the bottom of which is formed into an inverted conical shape. At the top of the first dryer 1, a valve 2 (a butterfly valve, a ball valve, etc. with excellent gas sealing properties is suitable) is provided. Similar to the valve 2, butterfly valves, ball valves, etc.) are arranged opposite to each other, and a water-containing solid material supply section 5 is provided above the valve 3. Further, a discharge section is provided at the bottom of the first dryer 1, and a valve 6 (butterfly valve, ball valve, etc.) and a valve 7 are disposed facing each other in this discharge section with a space 8 interposed below the valve 6. , the dried material in the first dryer 1 is discharged from the valve 7 when the valve is opened.

Furthermore, a first exhaust pipe 9 is provided in the upper part of the first dryer 1.
is opened, and a first hot air supply pipe 10 is provided at the bottom.
is opened. The first hot air supply pipe 10 is connected to an appropriate hot air supply source, and for example, the discharge air pipe of an aeration blower 11 that supplies aeration air to an aeration tank in a biological treatment process for organic wastewater is used. The first exhaust pipe 9 is preferably connected to an aeration diffuser in an aeration tank (not shown).

In addition, as for the structure of the inverted cone-shaped bottom of the first dryer, an inverted cone-shaped member 13 (a plurality of ventilation holes may be provided) is provided so as to form a space 12 above the bottom surface. If the first hot air supply pipe 10 is opened in the space 12 and communicated with the inside of the first dryer 1 at the center, then (most of) the supplied hot air will flow from the center of the first dryer 1. As it flows through and diffuses in an upward flow,
Undesirable drifting phenomena along the side walls in the first dryer 1 can be avoided.

14 is a second dryer, in which a second exhaust pipe 15 is opened at the top, a second hot air supply pipe 17 connected to a hot air fan 16 is opened at the bottom, and a valve 18 (rotary valve, The top of the second dryer 14 is connected to the valves 6 and 7 at the bottom of the first dryer 1 and the space. connected to a discharge section consisting of section 8;
The dried material in the first dryer 1 can fall into the second dryer 14.

Although the second exhaust pipe 15 is opened to the atmosphere outside the second dryer 14, it may be passed through a dust remover or a deodorizer, and the second hot air supply pipe 10 of the first dryer 1 may be opened to the atmosphere. It is also a preferred embodiment to connect the aeration blower 11 and other hot air supply blowers in the blower installation chamber 19 for supplying warm air to the air.

In the figure, A indicates a water-containing solid to be dried.

However, to explain its function, the water-containing solid A to be dried is dehydrated to a water content of 80% or less using a screw press, filter press, belt press, etc., and then crushed or pulverized to a particle size of about 10 to 30 mm. The granulated dehydrated cake is put into the upper supply section 5,
After adjusting the amount of cake to a predetermined amount using a particle interface detector or a timer, open the valve 3, drop the cake into the lower space 4, close the valve 3, and then open the valve 2 to transfer the cake to the first layer. It is dropped into the dryer 1 to form a packed layer with a layer thickness of about 500 to 1000 mm in order to maintain maximum heat utilization efficiency. Next, when hot air is supplied from the first hot air supply pipe 10, the hot air passes through the packed bed in an upward flow, the cake is dried, and the exhaust gas whose humidity has increased and the temperature has become low is passed through the first exhaust pipe 9. is discharged to the outside. On the other hand, when the valve 6 is opened, the dried cake that has been dried to a moisture content of around 40 to 50% in the first dryer 1 is ejected or falls into the space 8 due to air pressure (at this time, the dry cake is
(closed), then close the valve 6 and open the valve 7 to allow it to fall into the second dryer 14 to form a packed bed again.

In this way, the supply of the water-containing solid material A and the discharge of the dried material in the first dryer 1 are performed by alternately opening and closing the double valves arranged opposite each other, so that even if high-pressure hot air is supplied, there is no leakage to the outside of the dryer. Leakage is prevented.

Note that when this aerated drying device is used for drying water-containing solids generated during the treatment of organic wastewater such as sewage, human waste, and various industrial wastewaters, it is extremely energy-saving and advantageous.

In other words, a large amount of aeration air is supplied from a blower to an aeration tank for biological treatment, such as activated sludge treatment of organic wastewater. Conventionally, this blower simply supplies the air necessary for biological treatment. Only a single function was used. but,
As shown in the adiabatic compression theory of gases in thermodynamics, the temperature of the hot air discharged from the aeration blower is significantly higher than that of the blower suction air, reaching 60 to 80°C.

Therefore, the air discharged from the aeration blower 11 that supplies aeration air is supplied from the first hot air supply pipe 10 into the first dryer 1, and the retained heat is used as a heat source for drying the water-containing solids A. After that, the temperature dropped and the first
If the exhaust gas (air) exhausted from the exhaust pipe 9 is supplied to the diffuser in the aeration tank, a heat source for drying can be obtained at no cost, resulting in extremely energy saving. The bad odors in the exhaust gas (air) are biologically deodorized in the aeration tank, eliminating the need for special deodorization equipment and deodorization costs.

In the second dryer 14, a hot air fan 1 blows air from the bottom of the packed bed formed by falling from the first dryer 1.
The dry cake dried in the first dryer 1 is further dried by blowing hot air with a temperature of about 80 to 100°C supplied by the dryer 6 and aerating the inside of the packed bed in an upward flow. Dry to low moisture. At this time, the discharge pressure of the hot air fan 16 is at most several tens to
Approximately 100 mmAq is sufficient, and it is sufficient for the valve 18 to be a rotary valve, double damper, slide gate valve, etc. whose gas sealing performance is not as good as the one shown on the left. Note that if the pressure of the warm air supplied into the first dryer 1 is made higher than the pressure of the warm air supplied into the second dryer 14, the dried cake in the first dryer 1 will be transferred to the second dryer 14. It is easily expelled (like pneumatically).

In addition, if the temperature of the hot air blown into the dryer is too high (over 150℃), the surface of the dried cake may burn and cause a burnt odor (strong odor), so the temperature should be below 100℃. It is better to set

In this way, the dried material is finally discharged to the outside through the outlet having the valve 18 at the bottom of the second dryer 14. In addition, the second exhaust pipe 1 of the second dryer 14
Since the exhaust gas discharged from 5 still has a temperature of about 50 to 60°C, it is discharged into the blower installation chamber 19 to the first dryer 1 and sucked into the suction side of the blower. It is preferable to use it effectively as part of the drying heat source in the first dryer 1 from the viewpoint of energy saving.

[Effect of idea]

As described above, the present invention provides the following beneficial effects.

Compared to the hot air supplied to conventional aeration dryers, the structure allows for effective use of air discharged from aeration blowers and other hot air at much higher pressures and lower temperatures, significantly reducing fuel costs for drying water-containing solids. It is easy to process continuously.

When drying with air discharged from an aeration blower or other low-temperature hot air, if the moisture content of the hydrated solids increases, it will become insufficiently heated and cannot be dried to the target moisture content. Therefore, it is possible to always obtain a dry product with a moisture content below the target level.

Since the second dryer can also be used as a hopper, there is no need for a separate hopper for storing dried material.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view showing an embodiment of the present invention. 1...First dryer, 2, 3, 6, 7, 18...
Valve, 4... Space part, 5... Supply part, 8... Space part, 9... First exhaust pipe, 10... First hot air supply pipe, 11... Aeration blower, 12... Space part, 1
3... Inverted conical member, 14... Second dryer, 15...
...Second exhaust pipe, 16...Hot air fan, 17...Second hot air supply pipe, 19...Blower installation room, A...
Water-containing solids.

Claims (1)

[Claims for Utility Model Registration] (1) The bottom part is formed into an inverted conical shape, and the top part and the water-containing solids supply part above the top part are connected via valves arranged oppositely with a space interposed therebetween, and the bottom part A first dryer having a first exhaust port opened at the top and a first hot air supply port opened at the bottom, and a second dryer located at the top. It consists of a second dryer having an exhaust port, a second hot air supply port opened at the bottom, and a discharge port at the bottom, and the top of the second dryer is connected to the discharge part of the first dryer. An aeration drying device characterized by: (2) The inverted cone-shaped bottom of the first dryer has a double structure with a space interposed therebetween, and the first hot air supply port is opened in the space to communicate with the inside of the first dryer. The ventilation drying device according to claim 1 of the utility model registration claim. (3) The first hot air supply port of the first dryer is connected to the discharge port of an aeration blower, and the first exhaust port is connected to an aeration tank, as claimed in claim 1. Or the ventilation drying device according to item 2. (4) The scope of the utility model registration claim is that the second exhaust port of the second dryer is guided to the suction side of a hot air supply blower connected to the first hot air supply port of the first dryer. The ventilation drying device according to any one of items 1 to 3.