JPS6054158B2 - Filter cloth tension control method for belt press type dehydrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter cloth tension control method for a belt press type dehydrator.

In conventional belt press type dehydrators, the tension of the filter cloth is set manually, which makes it difficult to change the tension setting during operation, and it depends on the properties of the flocculated sludge, such as the concentration and organic matter ratio. It has the disadvantage that when the gravity dewatering property changes, the water content of the dehydrated cake changes accordingly.

In particular, if the gravity dewatering property is poor, the moisture content of the dehydrated cake becomes high, which poses a problem that it adversely affects subsequent processing such as incineration. Therefore, an object of the present invention is to automatically apply filter cloth tension (dewatering pressure) that is optimal for the properties of flocculated sludge, thereby reducing and stabilizing the water content of the dewatering cake.

To achieve this objective, the present invention uses a level meter to detect changes in liquid level caused by changes in the dewaterability of flocculated sludge in a gravity dewatering zone, and based on this detection signal, the higher the liquid level is, the more the filter is removed. The filter cloth tensioning device is operated to increase the tensioning force of the filter cloth.

Therefore, the filter cloth tension force, which is the driving force for dewatering, can be controlled by the liquid level change resulting from the change in dewatering property in the gravity dewatering zone, thereby simultaneously reducing and stabilizing the water content of the dewatering cake. This allows subsequent processing such as incineration to be carried out effectively.

Embodiments of the present invention will be described below based on the drawings.

The drawing shows a belt press type dehydrator, in which coagulated sludge 3 is dehydrated using two endless belt-shaped filter cloths 1 and 2.
Here, 4 is a gravity dewatering zone where water in the sludge 3 is dehydrated through the filter cloth 1 by the action of gravity, 5 is a pressure dewatering zone where the sludge 3 is sandwiched between both filter cloths 1 and 2 and dehydrated, and 6 is a gravity dewatering zone A compression dehydration zone by roll 7, and a shear dehydration zone 8 by rolls 9 to 16 arranged in a staggered manner,
The sludge is configured to be dehydrated in stages as it passes through each zone. 17 is gravity dehydration zone 4
This is a cake thickness adjusting roll installed between the cake pressure dehydration zone 5 and the cake pressure dehydration zone 5.

The roll 18 on which the filter cloth 1 is hung and the roll 19 on which the filter cloth 2 is hung are provided with filter cloth tensioning devices 20 and 21 that move the rolls 18 and 19 to adjust the tension of the filter cloths 1 and 2. are provided, and the filter cloth tensioning/tensioning devices 20, 21 are constituted by, for example, air cylinders.

Further, the gravity dewatering zone 4 is provided with a plurality of level meters 22, so that the liquid level of the flocculated sludge 3 in this zone 4 can be detected. The control method will be explained.

When the flocculated sludge 3 is introduced into the gravity dewatering zone 4,
Due to its gravity dewatering properties, the liquid level in this zone 4 changes. This liquid level change is detected by several level meters 22, and when the liquid level is high, that is, when the moisture content of the cake is high, a signal is sent to the p cloth tensioning devices 20 and 21, and the dehydration driving force is p. Increase the tension of cloths 1 and 2. If the opposite is true, the tension of the cloths 1 and 2 is reduced. The tension of the both lining cloths 1 and 2 can be determined, for example, by calculating the optimum value of the lining cloth tension from the detection signal of the level meter 22, and operating the lining cloth tensioning devices 20 and 21 based on the calculation result.
Optimally controlled. The flocculated sludge 3 from which most of the moisture has been dehydrated in the gravity dewatering zone 4 is transferred to the cake thickness adjusting roll 1
After the thickness is adjusted to a predetermined thickness by step 7, the pressure dewatering zone 5
, a compression dewatering zone 6 and a shear dewatering zone 8.

At this time, since the tension of the cloths 1 and 2 is properly controlled as described above, the moisture content of the cake 23 discharged after dehydration and sent to the incineration bin etc. Regardless of the degree of dehydration, it will be stabilized at a low level. Note that the sludge to be treated can be applied to sewage sludge, human waste treatment sludge, industrial wastewater treatment sludge, etc.

As described above, according to the present invention, the fabric tension force, which is the dehydration driving force, can be controlled by the liquid level change resulting from the change in dehydration properties in the gravity dehydration zone, and the water content of the dehydrated cake can be reduced. It is possible to simultaneously reduce and stabilize
Post-processing such as incineration can be carried out effectively.

[Brief explanation of drawings]

The drawing is a diagram showing a schematic configuration of an apparatus for carrying out the method of the present invention. 1, 2... Tofu, 3... Coagulated sludge, 4
...Gravity dehydration zone, 20,21...
? Cloth tension device, 22●◆●●Lebel meter.

Claims (1)

[Claims] 1 A level meter detects changes in the liquid level due to changes in the dewaterability of flocculated sludge in the gravity dewatering zone, and this detection signal is used to adjust the filter cloth so that the tension on the filter cloth increases as the liquid level increases. A method for controlling filter cloth tension in a belt press type dehydrator, characterized by operating a tension device.