JPH0515482B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for improving the degree of dehydration through electroosmosis by applying direct current to a liquid to be dehydrated, such as sewage sludge, while compressing and dehydrating it under pressure; In particular, the present invention relates to improvements in filter plates used in filter press type electroosmotic dehydrators.

(Prior Art) FIGS. 5A, 5B and 5C schematically show the basic structure and operation steps of this type of filter press type electroosmotic dehydrator.

At the stage shown in Fig. 5A, the electrodes of the filter press are arranged in alternating rows, a compressed filter plate a to which a compressed diaphragm is attached, and an ordinary filter plate b to which only electrodes are attached.
and press diaphragm d between two filter cloths c and c.
The sludge water of the liquid to be dehydrated is then forced into the filter chamber between the filter cloths from the raw liquid inlet e using the raw liquid pump, and the sludge water is forced into the filtration chamber between the filter cloths and passed through the filter cloth. The filtered water is discharged from the filtered water outlet f and subjected to primary dehydration. In the step shown in FIG. 5B, compressed air is introduced behind the compression diaphragm, and the pressure causes the filter cloth to expand and further squeeze out the water in the sludge cake for secondary dehydration. In the latter stage, direct current is applied between electrodes g and g to further promote dehydration by electroosmotic dehydration, and tertiary dehydration is performed until the water content of the sludge cake reaches approximately 50%. Thereafter, as shown in FIG. 5C, the filter plates a and b are opened and the filter cloths c and c are pulled down to take out the dehydrated cake h. Repeat the above batch operation. The dehydrated cake, which has reduced weight and volume and is heated to a temperature close to 90°C inside the machine, is much easier to transport and process.

(Problems to be Solved by the Invention) In the conventional dehydrator, water leaks out of the filter plate. This is because water oozes out through the mesh or texture of the filter cloth due to capillary action, so it cannot be completely stopped even if the tightening force of the filter plate is strengthened. This amount of leakage is particularly large at the beginning of pump injection of sludge. Furthermore, if the filter plate is mechanically incompletely tightened, sludge water may blow out. As filtration progresses, water seepage gradually decreases as sludge particles fill the gaps between the meshes of the filter cloth, but after the sludge cake is removed, the filter plate is closed again and the next dewatering process begins. Since pressurized water is introduced and water is blown from the back side of the filter cloth in order to eliminate clogging of the filter cloth, the pressure at the tightening part is weak at this time and leakage is likely to occur due to the water pressure. At this time, no leakage prevention effect due to sludge can be expected. FIG. 7 schematically shows that this water leakage occurs around the entire circumference of the filter plate.

This water leakage, especially lateral leakage or scattering, may protrude through the leakage pan, staining the floor surface, and may even adversely affect electrical equipment and measuring equipment, making operation and maintenance difficult. Make it.

As a countermeasure against this water leakage, an attempt has been made to seal the tightening peripheral portion C' of the filter cloth c by filling it with a resin such as silicone to make it impermeable, as shown in FIG. However, this measure increases the cost of the special filter cloth, and new problems arise, such as a decrease in the filtration area if the tightening setting is deviated.

(Means for solving the problems) The problems of the prior art are solved in the present invention.
The filter plate itself has been improved, and a drainage groove is provided on the tightening seal surface around the filter plate, which runs around the circumference and drains water that leaks through the filter cloth from inside the filtration chamber and collects it in the drainage groove. This problem can be solved rationally by draining the water out of the filter plate from the bottom end of the drain.

That is, the filter plate of the electroosmotic dehydrator of the present invention is
The overall structure is that in a filter press type electroosmotic dehydrator, a continuous drainage groove is provided on the tightening seal surface around the filter plate, which is tightened with two filter cloths sandwiched between them, and the end of the groove is It is characterized by communicating with the outside of the board at the bottom side.

(Function) When an electroosmotic dehydrator is constructed using the filter plate according to the present invention, the drain groove communicates with the outer sphere at the end, so that the pressure becomes atmospheric. Therefore, leakage water that passes through the filter cloth seeps out to this extent due to the pressure difference potential with the internal pressure, but at the outer periphery of the filter plate, the pressure difference potential is essentially 0, and it seeps into the filter cloth due to capillary action. Water is also not pushed out.

The leakage water received in the drain groove flows through the drain groove, is collected, is received from the lower end by the leakage receiver tray located below, and is removed. The lower end is provided within the range of the saucer.

In this way, all the above-mentioned problems of the prior art do not occur.

(Examples) Hereinafter, the present invention will be specifically described based on Examples with reference to FIGS. 1 to 4.

FIG. 1 shows a filter plate 1 according to an embodiment of the present invention. This corresponds to the ordinary filter plate b described in the prior art, and a divided electrode 2 is provided in its central region. The peripheral portion thereof is a flat tightening sealing surface 3, which presses against the corresponding surface of the squeeze filter plate through two filter cloths during tightening, thereby sealing between both surfaces. In the present invention, a continuous drainage groove 4 is formed in the tightening sealing surface 3 in approximately one round.
FIG. 2 shows a cross section of this drain groove 4. An end 4' of the drain groove 4 is provided at the lower end and communicates with the outside of the filter plate at the lower side of the filter plate 1. The drain groove 4 circulates around the outside of the stock solution passage 5 that communicates with the stock solution inlet e. Reference numeral 6 indicates a compressed air passage for the compressed diaphragm, and 7 indicates a drainage passage leading to the drainage outlet f.

FIG. 3 shows the state of leakage water 8 passing through the filter cloth with arrows. c represents the adjacent filter cloth. This leaked water is collected in the drain groove 4, flows down the groove, and is discharged from the lower part 4' to the outside of the machine. When the filter plate is tightened, the filter cloth gets wedged in the drain groove, but the water that leaks along the filter cloth is still collected in the groove. The discharged leakage water is received by the lower leakage receiver 9 and drained into the gutter 1 as shown in FIG.
0 and is eliminated.

Drainage grooves may be provided not only on the normal filter plate but also on the tightening sealing surface of the compressed filter plate that is in contact with the filter cloth, or may be provided on both sides. The present invention can also be effectively applied to ordinary filter presses having no electrodes, and this is within the similar scope of the present invention.

(Effects of the Invention) According to the present invention, it is possible to reliably prevent splashing of leaking water from an electroosmotic dehydrator with a simple structure that does not particularly increase costs, and to solve problems in operation, maintenance, and equipment safety.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a filter plate of an electroosmotic dehydrator according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of its drain groove, and Fig. 3
Figure 4 is a perspective view schematically showing the state of the leaked water, Figure 4 is a longitudinal cross-sectional end view of the leaking liquid receiving tray, and Figure 5 A shows the basic configuration of the filter press type electroosmotic dehydrator.
FIG. 5B is a longitudinal side view showing a different operation stage; FIG. 5C is a longitudinal side view showing a further different operation stage; FIG. 7 is a perspective view schematically showing a water leakage situation in a conventional electroosmotic dehydrator, and FIG. 8 is a front view of a trial deformed filter cloth. 1...Filter plate, 2...Divided electrode, 3...Tightening sealing surface, 4...Drain groove, 4'...End, 5...
Raw solution passage, 6... Compressed air passage, 7... Filtration passage, 8... Leaking water, 9... Leaking liquid receiver, 10... Gutter section, a... Compressed filter plate, b... Ordinary filter plate, c...filter cloth, C'...periphery, d...compression diaphragm, e
...Standard solution inlet, f...filtrate outlet, g...electrode, h
...Dehydrated cake.

Claims (1)

[Claims] 1. In a filter press type electroosmotic dehydrator, a continuous drainage groove is provided on the tightening seal surface around the filter plate, which is tightened with two filter cloths sandwiched between them.
A filter plate for an electroosmotic dehydrator, characterized in that an end portion thereof communicates with the outside of the filter plate at a lower side position.