JPS6121760B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a belt press type dehydrator used for dewatering sludge and the like generated in sewage treatment plants.

BACKGROUND ART In recent years, with the spread of sewage treatment plants and stricter regulations on industrial wastewater, the amount of sludge generated has been gradually increasing year by year. The actual treatment of this sludge is to dehydrate it using a belt press type dehydrator or centrifugal decanter, and then incinerate the dumping area. In this case, the higher the dehydration rate, the more desirable it is because, in the case of dumping, transportation costs can be reduced, and in the case of incineration, the cost of combustion improvers can be reduced. For this reason, various attempts have been made to improve dehydrators, but at present no satisfactory dehydrator has been completed.

Problems to be Solved by the Invention The present invention was proposed to improve and improve the dewatering efficiency of conventional belt press type dehydrators, and provides a new belt press type dehydrator. The sludge dehydration function of conventional belt press dehydrators is a gravity dehydration function using natural force on a running cloth, and then the sludge is sandwiched between two upper and lower cloth belts running in the same direction and then compressed by a roll with a large diameter. A low-pressure dehydration function is achieved by rotating and detouring between a group of small diameter rolls, and a shear dehydration function is achieved by the interaction of shear force and squeezing, and by pressing the cloth belt against the rolls with strong pressure using another metal belt. This depends on the high-pressure dewatering function, but the thickness of the cake sandwiched between the two running cloth belts is generally 5 to 10 mm.
Even if the moisture inside the thickness of the cake is once separated from the sludge particles due to the above-mentioned squeezing action, it has a tendency to be difficult to come out to the outside surface of the cake, and this suppresses the improvement in the dewatering rate of the belt press type dehydrator. This is one of the major factors. The present invention has been made with this in mind.In order to make it easier to release the moisture inside the cake, the cake is crushed, then sheared and squeezed again to create a passageway for the liquid.It is a belt press type that has an unprecedented high dehydration rate. It provides a dehydrator.

Configuration of the Invention The configuration of the present invention will be explained below based on the drawings.
FIG. 1 is an overall assembly diagram showing an embodiment of the belt press type dehydrator of the present invention. In the figure, 1 is a lower belt made of endless liquid-permeable cloth stretched between rolls, and 2 is an upper belt made of polyester.
Made of durable synthetic fibers such as nylon. 3 is a sludge supply tank equipped with stirring blades that rotate slowly. Reference numeral 4 denotes a gravity section consisting of an inclined portion of the lower belt 1, 5 a low-pressure roll section consisting of rolls with a large diameter, and 6 a single-stage shearing roll consisting of a group of rolls with a plurality of small diameters. Reference numeral 7 denotes a crushing roll section which is an essential part of the present invention and is provided subsequent to the first-stage shearing roll section 6, and is a roll group that separates and guides the upper and lower two belts 1 and 2 exiting the first-stage shearing roll section. 8 to 8, knives 12 and 12' that scrape off the cake by coming into contact with the separated belt, and crushing rolls 9 and 9' that crush the peeled sheet-like cake into grains. As for the type of crushing roll, an appropriate type suitable for the properties of the cake is selected from among paddle type, uneven groove meshing type, screw type, etc. Reference numeral 10 designates a transfer means, such as a hood, located below the crushing rolls 9, 9' to prevent the crushed cake from scattering and to transfer it onto the lower belt 1 again. Reference numeral 11 is a two-stage shearing roll section consisting of a plurality of small diameter rolls, and 12'' is a knife that comes into contact with the final roll of the lower belt to scrape off the dehydrated cake.

Function The function of the device having the above configuration will be explained. The sludge to be treated is quantitatively transferred from the supply tank 3 to the lower belt 1.
It is fed to the lower part of the gravity flow section 4. Water in the sludge is dehydrated on a liquid-permeable cloth under the action of gravity. The sludge exiting the gravity flow section is then sandwiched between the upper belt 2 and lower belt 1 running in the same direction, and is then compressed and dewatered on the low pressure roll 5, then enters the first stage shear roll section and rotates between a group of small diameter rolls.・During the detour, the sludge cake held between the two belts is further dehydrated by the synergistic effect of shearing force and squeezing force, and becomes a fairly hard sheet-like cake. Two belts 1 and 2 exiting the first stage shear roll section
are separated separately by separation guide roll groups 8 to 8, the sheet cake on the belt is scraped off by the abutting knives 12, 12', and the peeled cake falls between the two crushing rolls 9, 9'. The sheet-like cake is crushed into pieces by a paddle-shaped roll or the like and transferred onto the lower belt 1 by the transfer means 10. This crushed cake is again sandwiched between two upper and lower belts, and subjected to compression and shearing action in the two-stage shearing roll section, whereby the water contained inside the cake is efficiently dehydrated. The cake finally dehydrated as described above is peeled off from the belt by the knife 12'' that comes into contact with the lower belt 1 on the final roll, and is conveyed outside the machine by a conveyor or the like (not shown).In this embodiment, Dewatering is completed in the two-stage shear roll section, but depending on the properties of the sludge, it may be better to install a high-pressure dewatering roll after this.

Effects of the Invention According to the present invention having the above configuration and operation, the following effects not available in conventional belt press type dehydrators can be obtained.

The sheet-shaped cake that leaves the first-stage shearing roll section is once made into granules and then compressed and dehydrated again in the shearing roll section. This makes it possible to dehydrate the adhered water inside the sheet, which is difficult to remove, and to reduce the water content in the cake. Since it can be reduced by about 5%, the capacity of the equipment following the sludge dewatering equipment can be reduced, and for example, in the case of incineration equipment, the fuel consumption of the auxiliary combustion agent can be greatly reduced.

[Brief explanation of the drawing]

FIG. 1 is an overall assembly diagram showing an embodiment of the belt press type dehydrator of the present invention. 1... Lower belt, 2... Upper belt, 3... Supply tank, 4... Gravity excess section, 5... Low pressure roll section, 6
...1st stage shearing roll section, 7... Crushing roll section, 8
~8...Separation guide roll, 9,9'...Crushing roll, 10...Transfer means, 11...Two-stage shearing roll section, 12~12''...Knife.

Claims (1)

[Claims] 1 In a belt press type dewatering machine in which sludge is held between two running endless cloth belts (upper and lower) and compressed and dehydrated by sequentially passing through a gravity dewatering section, a low pressure roll section, a shearing roll section, etc., water in the sludge is compressed and dehydrated. 1
Separated into a stage shearing roll section and a two-stage shearing roll section, in between, a roll separates and guides the two belts, a knife contacts the separated belts, a roll crushes the peeled cake, and a roll separates and guides the two belts. A belt press type dewatering machine characterized by being provided with a crushing roll section consisting of a transfer means for transferring onto a belt.