JPH0677758B2 - Sludge activated carbonization method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sludge activated carbonization method for regenerating sludge obtained in a wastewater treatment process, industrial waste sludge or the like as activated carbon.

[0002]

2. Description of the Related Art Conventionally, the one disclosed in the following publication is known. JP-A-57-156097 A method of dehydrating sludge, mixing it with plant waste such as bark, depositing the mixture, fermenting it to compost it, and then carbonizing and activating it. JP-A-62-149400 A method in which iron powder and inorganic carbide are mixed with industrial waste sludge and carbonized and dried.

[0003]

However, in these conventional methods, since other substances are mixed with sludge and carbonized, not only the productivity is poor, but also the cost is high, and mercury which is a toxic substance is removed. There were problems such as not dealing with removal.

An object of the present invention is to make it possible to regenerate activated carbon efficiently using only sludge and containing no mercury.

[0005]

In the first aspect of the present invention, dehydrated activated sludge is carried into a drying kiln, heated and dried with stirring, and then continuously sent from the drying kiln to a carbonization kiln. Into the carbonization kiln, high temperature gas is heated to a temperature higher than the boiling point of mercury for carbonization, and the mercury is evaporated and then continuously discharged from the carbonization kiln.

In the second embodiment, the dehydrated activated sludge is carried into a drying kiln, heated and dried with stirring, solidified by a solidifying machine, and then put into a carbonization kiln and heated to a temperature not lower than the boiling point of mercury. It is carbonized and the mercury is evaporated before it is discharged.

[0007]

According to such a method, the activated carbon can be regenerated from the activated sludge and using it alone as a raw material. The mercury contained in the activated sludge is removed by evaporation in the carbonization process. The regenerated activated carbon can be used for applications such as soil conditioners.

[0008]

EXAMPLES Examples of the present invention will be described in detail below. FIG. 1 shows a first embodiment of the present invention. The dehydrated activated sludge (activated sludge dehydrated cake) is introduced into the carry-in hopper 2 by the raw material carry-in conveyor 1, and continuously fed from the front end into the dry kiln 4 which is the rotary kiln by the raw material supply screw feeder 3. To be done. The dry distillation gas from the dry distillation gas combustion furnace 5 is fed into the dry kiln 4 from the front end and discharged from the rear end, and the activated sludge fed into the dry kiln 4 is the dry kiln. 4 is forcibly dried by the heat of the dry distillation gas while being stirred by the rotation of 4, and is discharged from the rear end of the drying kiln 4 and then continuously fed into the carbonization kiln 6 from the upper end of its front end.

The carbonization kiln 6 is longer than the drying kiln 4, and a high temperature gas having a temperature higher than that of the dry distillation gas fed into the drying kiln 4 is used for the carbonization gas generator 7 at the front end.
Gas from the external heat circulation gas generator 8 is circulated and sent into the outer cylinder 6a covering the carbonization kiln 6 as well as sludge dried in the drying kiln 4. Is carbonized by being heated by the high temperature gas while being stirred in the carbonization kiln 6. The average temperature in the carbonization kiln 6 should be higher than the boiling point of mercury (the boiling point of mercury itself is 356 degrees Celsius, and that of the compound is 300 to 400 degrees Celsius) so that the mercury contained in the sludge evaporates. Adjusted.

The carbide obtained in the carbonization kiln 6, that is, activated carbon, is discharged from the rear end of the carbonization kiln 6 and cooled by the rotary cooler 9, and then the product carrying conveyor 10
Are carried into the product tank 11.

The dry distillation gas combustion furnace 5, the carbonization gas generator 7, and the external heat circulation gas generator 8 use heavy oil supplied from a heavy oil tank 12 as fuel. The dry distillation gas from the dry distillation gas combustion furnace 5 is sent to the drying kiln 4 from the front end portion thereof via the exhaust heat boiler 13 to which soft water is supplied. A part of the gas from the exhaust heat boiler 13 is also supplied to the carbonization gas generator 7 and also used for carbonization.

The gas used for drying in the drying kiln 4 is discharged from the rear end of the drying kiln 4 and removed by the cyclone separator 14, and the dust collecting filter 1
After being finely filtered by No. 5, it is heated in the deodorizing furnace 16 to be deodorized, and then discharged from the chimney 17 into the atmosphere. The deodorizing furnace 16 also uses heavy oil from the heavy oil tank 12 as fuel.

The gas from the external heat circulation gas generator 8 is introduced into the outer cylinder 6a of the carbonization kiln 6 from its rear end and is used for heating the carbonization kiln 6, and then from the front end of the outer cylinder 6a. It is discharged and mixed with dry-distilled gas from the dry-distilled gas combustion furnace 5, and is also used for drying in the dry kiln 4.
The gas used for carbonization in the carbonization kiln 6 is discharged from the rear end of the carbonization kiln 6 and burned again in the carbonization gas combustion furnace 5. By circulating the gas and repeatedly using it in this manner, it is possible to prevent the vaporized mercury from scattering into the atmosphere and improve the thermal efficiency. Furthermore,
The rotary cooler 9 is of a water cooling type, and the water supplied thereto is radiated by the cooling tower 18 and then circulated for use. In addition, 19 is a damper.

The example shown in FIG. 1 is a continuous type in which sludge is continuously fed and treated, whereas the example shown in FIG. 2 is a batch type in which sludge is transferred and treated. That is, the dehydrated activated sludge fed into the raw material hopper 20 is fed into the drying kiln 22 by a fixed amount by the metering pump 21 and dried, and then discharged from the rear end of the drying kiln 22 and conveyed by the conveyor 23 into a plurality of solids. It is sent to the machine 24 and solidified into, for example, granules by the solid machine 24, and then stored in a plurality of silos 25.

The solid matter stored in the silo 25 is taken out at any time and is fed into a plurality of vertical carbonization kilns 27 by a conveyor 26 to be carbonized, and then is taken out from the carbonization kiln 27 as activated carbon. Then, it is conveyed to the cooling device 29 by the conveyor 28 and cooled. The cooled activated carbon is sent to the product silo 31 by the conveyor 30 and stored therein.

The drying kiln 22 and the carbonization kiln 27 are dried and carbonized by the high temperature gas from the gas combustion furnace 33 which uses the heavy oil from the heavy oil tank 32 as a fuel. The exhaust gas discharged from the rear end of the drying kiln 22 is collected by the dust collector 34 and then discharged from the chimney 35 into the atmosphere. Dust collector 3
The solid separated in 4 is sent to the solid machine 24 by the conveyor 23. In addition, 36 is a pushing fan and 37 is a suction fan.

[0017]

EFFECTS OF THE INVENTION According to the present invention, activated carbon can be efficiently and economically regenerated from activated sludge using only that as a raw material. Further, since the mercury contained in the activated sludge is vaporized in the carbonization process, it can be regenerated as activated carbon containing no mercury, which is suitable for use as a soil improving material and the like.

[Brief description of drawings]

FIG. 1 is a flow sheet of a first embodiment of the present invention.

FIG. 2 is a flow sheet of a second embodiment.

[Explanation of symbols]

 4.22 Drying kiln 6.27 Carbonizing kiln 24 Solid machine

Claims (2)

[Claims] 1. A dehydrated activated sludge is carried into a drying kiln, heated and dried with stirring, and then continuously fed into the carbonization kiln from the drying kiln to generate mercury by high temperature gas in the carbonization kiln. A method for activated carbonization of sludge, which comprises heating to a temperature not lower than the boiling point for carbonization, vaporizing mercury, and then continuously discharging it from a carbonization kiln. 2. The dehydrated activated sludge is carried into a drying kiln, heated and dried with stirring, solidified by a solidifying machine, then put into a carbonization kiln and heated to a temperature not lower than the boiling point of mercury for carbonization. At the same time, the activated sludge carbonization method is characterized in that mercury is evaporated and then discharged.