JPH044877Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an aerated drying device for drying sludge and other granular and flaky water-containing solids generated in sewage treatment in an energy-saving manner.

[Conventional technology]

In conventional ventilation drying equipment (the typical model being a ventilation band dryer), the discharge pressure of the blower that supplies warm air for drying is several hundred mmAq or less. The leakage gas amount is not a problem, and therefore no special measures are required for the structure of the wet solids supply section and dry matter discharge section, and the opening and closing of rotary valves, screw feeders, etc. with insufficient gas sealing properties can be avoided. The organization was also able to respond adequately.

[Problem that the invention attempts to solve]

However, attempts have been made to dry water-containing solids using the compression heat (temperature of about 60 to 90°C) of the air discharged from the aeration blower that supplies aeration air to the aeration tank in the activated sludge treatment process of wastewater. Then, the pressure of the air discharged from the aeration blower becomes a gauge pressure of about 0.6 to 0.7 Kgf/cm ² when the aeration water depth of the aeration tank is 5 m, so for such high-pressure hot air, Conventional aerated drying equipment leaked a large amount of gas, and there was no one that could withstand practical use.

Therefore, it is necessary to develop a new type of ventilation drying device that can efficiently utilize the heat retained in high-pressure hot air such as the air discharged from an aeration blower.

Furthermore, in conventional aerated drying devices, the thickness of the packed layer of water-containing solids is small (several centimeters), so there is a problem in that the required cross-sectional area of the device is large. In addition, there is a ventilated vertical dryer that operates with a high packed bed thickness, but this dryer is made using materials such as coal, rice grains, wheat, and plastic pellets, which have high strength and do not have the property of adhering to each other. This method could only be applied to water-containing granular materials, and could not be applied at all to highly sticky materials such as sludge. Moreover, the direction of hot air supply is complicated, construction costs are high, and manufacturing is troublesome.

This invention can efficiently utilize high-pressure hot air called the aeration blower discharge air, and by devising a hot air supply method, it can be used to remove highly adhesive water-containing solids such as sludge dewatering cake. Another object of the present invention is to provide a new type of ventilation drying device that can form a thick packed layer, improve heat utilization efficiency, and perform continuous drying.

[Means and actions for solving problems]

In the present invention, the bottom of the tank body is formed into an inverted conical shape, and the upper part of the tank body and the water-containing solids supply section above the tank body are connected via valves arranged facing each other with a space interposed between them. A discharge section consisting of valves arranged opposite each other with a space interposed therebetween is provided, and a hot air supply port is opened in the upper part of the tank body, and an exhaust port is opened in the lower part of the tank body to ventilate the tank with a downward flow. This is an aeration drying device that supplies water-containing solids and discharges dried materials by alternately opening and closing 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 tank. In addition, due to the downward flow of hot air, the water-containing solids that are sequentially supplied into the tank from above are dried most quickly at the interface of the packed bed, preventing adhesion at the interface of the packed tank. It can be prevented.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a tank body wrapped with a heat insulating material, and the bottom of the tank body 1 is formed into an inverted conical shape. A valve 2 (a butterfly valve, a ball valve, etc. with excellent pressure gas sealing properties are suitable) is provided at the top of the tank body 1.
Valve 3 (valve 2
Similarly, 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 valve 6 (butterfly valve, ball valve, etc.) is provided at the bottom of the tank body 1, and a valve 7 is disposed opposite to the lower part of the valve 6 with a space 8 interposed therebetween. When opened, the dry matter in the tank body 1 is discharged.

Further, a hot air supply pipe 9 is opened at the upper part of the tank 1, and an exhaust pipe 10 is opened at the lower part of the tank 1. The hot air supply pipe 9 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 an aerobic biological treatment process for organic wastewater is used. The exhaust pipe 10 can be communicated with an aeration diffuser (disk user, sparger, etc.) in an aeration tank (not shown).

The shape of the space 8 between the valves 6 and 7 at the bottom is as follows:
It may have a straight body shape, but it is also preferable to have a bulged shape.

In addition, as for the structure of the inverted conical bottom of the tank body 1, an inverted conical member 13 (a plurality of vent holes may be provided in the surface of this member) is provided to form a space 12 above the bottom surface. However, if the exhaust pipe 10 is opened in this space 12 and communicated with the inside of the tank body 1 at the center, the supplied warm air will flow downward from the top to the center of the tank body 1. Since the water is diffused, drifting along the side walls inside the tank body 1 can be avoided.

In the figure, 14 indicates a tank filled with water-containing solids to be dried, such as a sludge dewatered cake.

Then, a water-containing solid material to be dried, for example, a granular sludge dewatered cake with a water content of 75% or less, is introduced into the supply section 5 at the top, and the amount of cake is adjusted to a predetermined amount using a particle interface detector or a timer. After that, open the valve 3, drop it into the lower space 4, close the valve 3,
Furthermore, the valve 2 is opened to allow the cake to fall into the tank body 1 to form a packed layer 14 having a layer thickness of about 200 to 1000 mm.

Next, hot air is supplied from the hot air supply pipe 9, the hot air flows downward through the packed bed 14, the cake is dried through ventilation, and the exhaust gas with increased humidity is passed through the exhaust pipe 1.
0 and is discharged outside the tank. On the other hand, when the valve 6 is opened, the dry cake dried in the tank body 1 is ejected or falls into the space 8 by air pressure and gravity (at this time, the valve 7 is closed), and when the valve 6 is closed, the 7 is opened and the water is discharged outside the tank body 1.

In this way, the supply of water-containing solids and the discharge of dry materials are performed by alternately opening and closing the double valves arranged opposite each other, so even if high-pressure hot air is supplied, leakage to the outside of the tank is prevented. Discharging of dried matter is forced by hot air pressure, so no dried matter remains in the tank, and continuous operation can be easily performed.

Furthermore, as described above, it is important to allow the hot air to flow downwardly through the packed bed 14. In other words, in order to make maximum use of the heat capacity of the supplied hot air, it is necessary to increase the thickness of the packed bed of water-containing solids and increase the contact time with the hot air. When hot air is supplied in an upward flow, the lower part of the packed bed dries faster than the upper part, and the drying of the upper part of the packed bed, where the water content of the water-containing solids is highest, is delayed. Strongly sticky materials adhere to each other at the top of the packed bed, forming a "dango-like" shape, so to speak.
Even though the warm air is good, it is no longer possible to ensure ventilation, causing significant uneven drying.

On the other hand, in the present invention, since hot air is supplied to the packed bed 14 in a downward flow, drying progresses from the top of the packed bed 14 where the sludge dewatered cake and the like are most likely to adhere to each other. As a result, the air permeability of the packed bed 14 can be ensured.Furthermore, since adhesion is unlikely to occur at the filled bed interface, the packed bed 14 is It can be made as high as 1m or more, and the tank body 1
The installation area can be significantly reduced.

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 advantageous in terms of energy saving. In other words, a large amount of aeration air is supplied from a blower to the aeration layer for aerobic biological treatment, typically activated sludge treatment of organic sewage, but conventionally, this blower simply supplies the air necessary for aerobic biological treatment. Only one function was used: supplying air. However, 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 90°C.

Therefore, the air discharged from the aeration blower 11 that supplies aeration air is supplied into the tank body 1 from the hot air supply pipe 9, and the retained heat is transferred to the packed bed 14 of water-containing solids.
If the exhaust gas (air) that is cooled down and exhausted from the exhaust pipe 10 is supplied to the diffuser in the aeration layer, the heat source for drying can be obtained at no cost, resulting in extremely energy saving. Since the bad odor in the exhaust gas (air) exhausted from the exhaust pipe 10 is biologically deodorized in the aeration tank, special deodorizing equipment and deodorizing costs are unnecessary.

[Effect of idea]

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

Even when using high-pressure hot air, which was conventionally considered to be unsuitable as a heat source for drying, there is no leakage, and water-containing solids can be continuously dried. There is less loss,
Heat utilization efficiency improves.

Since dry matter can be forcibly discharged by hot air pressure, there is no problem of dry matter remaining inside the tank.

The air permeability of the packed bed of water-containing solids to be dried is ensured, the height of the packed bed can be increased, and the installation area of the apparatus can be made compact.

[Brief explanation of drawings]

The drawing is a longitudinal sectional view showing an embodiment of the present invention. 1... Tank body, 2, 3... Valve, 4... Space part, 5
... Supply section, 6, 7 ... Valve, 8 ... Space section, 9 ...
... Hot air supply pipe, 10 ... Exhaust pipe, 11 ... Aeration blower, 12 ... Space part, 13 ... Inverted conical member,
14...Filled layer.

Claims (1)

[Claims for Utility Model Registration] 1. The bottom of the tank is formed into an inverted conical shape, and the top of the tank and the supply section for water-containing solids above the tank are connected via valves arranged facing each other with a space interposed therebetween. A discharge section consisting of valves arranged opposite each other with a space interposed at the bottom of the tank body is provided, and a hot air supply port is opened at the top of the tank body, and an exhaust port is opened at the bottom of the tank body to ventilate with a downward flow. An aeration drying device characterized by: 2. Utility model registration claim 1, wherein the inverted conical bottom of the tank body has a double structure with a space interposed therebetween, and the exhaust port is opened in the space to communicate with the inside of the tank body. Ventilation drying device as described in section. 3. Utility model registration claim 1, in which the warm air supply port is connected to the discharge port of the aeration blower, and the exhaust port is connected to the aeration tank.
The ventilation drying device according to item 1 or 2.