JPH0418906A - Electroosmotic dehydrator - Google Patents

Abstract

PURPOSE:To surely prevent the sympathetic detonation of an flammable gas due to the spark of a collector brush by providing a water spray nozzle for injecting cleaning water to the rear of a press belt in parallel with the brush slinding on the rear of the press belt. CONSTITUTION:A rotary drum 1 and an endless press belt 2 laid around the drum 1 are used as counter electrodes, and sludge 12 is supplied to a passage between the counter electrodes and dehydrated. A collector brush 6 connecting a power source 4 and the belt 2 is furnished on the rear side of the belt 2 in its dehydration zone, and a water spray nozzle 10 for injecting water on the rear of the belt 2 is provided in parallel with the brush 6. Namely, the bubbles contg. a flammable gas generated on the rear side of the belt because of the properties of sludge are carried away by the sprayed cleaning water, hence the sympathetic detonation of the flammable gas due to the spark produced between the brush and belt is prevented, and safety is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electroosmotic dehydrator for dewatering excess sludge in a sewage treatment plant or sludge in factory waste liquid.

[Conventional technology]

As the above-mentioned electroosmotic dehydrator, for example, JP-A-63-
A rotating drum type electroosmotic dehydrator described in Japanese Patent No. 256112 has already been put into practical use. This electroosmotic dehydrator uses a rotating drum and an endless press belt, which is superimposed on a filter cloth and stretched around the rotating drum, as opposing electrodes as an anode and a cathode, respectively, and there is a direct line between the electrodes.
Voltage is applied from ta, and the water contained in the sludge supplied to the sludge passage between the rotating drum and the press belt is collected on the press belt side of the cathode by electroosmosis, and is dehydrated by passing through the filter cloth and press belt here. It was designed to do so.

On the other hand, in order to effectively collect the current flowing from the rotating drum on the anode side through the sludge to the press belt, a current collector brush is installed on the back side of the dewatering section of the press belt, and the current flows through the current collector brush. A current collection system in which a press belt and a power source are connected has also been put into practical use.

[Problem to be solved by the invention]

By the way, in the above-mentioned electroosmotic dehydrator, the following problems may occur during operation depending on the properties of the sludge that is the material to be dehydrated.

If the sludge is an organic substance, the properties of the sludge will depend on the temperature 6. Due to the exothermic action of electrolysis during the dehydration process, a large amount of flammable gas such as knee water particles will be generated in the sludge. It forms bubbles and leaks out to the back side of the press belt. Such a phenomenon is often experienced in actual driving.

Moreover, when a large amount of bubbles containing flammable gases are generated, and the current collector brush placed on the back side of the press belt is used to collect current as described above, it will slide on the press belt and the belt surface! Electric sparks generated between Jden Gibran (
Sparks) can become a source of ignition and cause hydrogen gas to explode, which is extremely dangerous.

The present invention is based on the above-mentioned point 2, and by additionally equipping a simple means, it is possible to securely prevent the explosion of flammable gas caused by the spark of the current collector blank. The purpose is to provide an electroosmotic dehydrator with high performance.

Means for Solving 11] In order to solve the above problems, in the electroosmotic dehydrator of the present invention,! A water spray nozzle that sprays cleaning water is installed on the back side of the press belt parallel to the JtJ run.

[Function] With the above configuration, cleaning water is sprayed from the water spray nozzle toward the peripheral knee of the current collecting plane from the back side of the press belt during operation of the electroosmotic dehydrator, thereby removing the water generated during the electroosmotic process. The bubbles disappear immediately after washing with water, and the flammable gases trapped within the bubbles diffuse into the surrounding air atmosphere. As a result, the concentration of the flammable gas is reduced, and there is no possibility that sparks generated between the current collector blank and the press belt will become an ignition source and cause a gas explosion.

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

Figure 1 5 In Figure 2, 1 is the rotating tram on the anode side, 2
3 is an endless press belt (metal caterpillar type belt or wire mesh belt) on the cathode side that is laid around the circumferential area facing the rotating drum 1, and 3 is a filter that is laid over the press belt 2 on its circumferential surface. Cloth belt, 4:; DC; 5.5
Siyo rotating drum 1 and fi! 4 is connected to the press belt 1 in the region facing the rotary tractor 1;
The current collector plane 7 installed opposite to the plane side served as a support for the current collector plane 6 and was connected to 'gLrA4! ! Electric conductor, 8 is a conductive spring that presses the current collecting flanno 6 against the press belt surface, 9
The container for the liquid is a plate. Note that the rotating drum 1 is rotationally driven by a drive motor (not shown).

Further, the cathode side of the power source 4 is grounded together with the press belt 2 and the like.

Furthermore, a water spray nozzle 10 that sprays cleaning water toward the back surface of the press belt 2 from below is installed in the vicinity of the current collector blank 6 . Washing water using industrial water or the like is supplied under pressure to the water spray nozzle IO through a pump (not shown) 7, and as shown in FIG. Spray cleaning water towards.

With this configuration, with voltage applied from f 1llll 4 and rotating drum 1 being driven to rotate, the sludge passage 2/7; Then, the sludge 12 is transferred to the rotating door;
, and the root 2, and are conveyed while receiving an axial wedge force; Filter cloth health! -3 also moves around. At the same time, the water contained in the sludge is affected by the electroosmotic force caused by the electric field formed in the opposing surface area between the rotating drape 41 and the press belt 2, and the water contained in the sludge is (
-) The filter cloth 2 is charged with electricity and flows toward the press belt side of the cathode 3. The water that has passed through the press belt 2 is drained out of the system through a tray 9. This: Rubbing mud 12 is dehydrated with low moisture content -F12. I, and when it exits the sludge passage, the scraper 13 removes °° less belt 2;)
・Peel off and take a minute! ! It was collected.

On the other hand, in the process of electroosmotic dehydration, flammable gases such as hydrogen are generated in the sludge depending on the nature of the sludge 12 (organic substances) due to electrolysis, and the gas becomes bubbles and passes through the filter cloth from the sludge passage side. It passes through the belt 3 press belt 2 and leaks out from the back side. Incidentally, such flammable gas bubbles occur most frequently in the central region of the dewatering passage where electroosmotic dehydration has progressed to some extent, and on the contrary, they hardly occur in the latter half of the dehydration passage where sludge cake formation has progressed. Therefore, while the dehydrator is running, wash water is sprayed from the water spray nozzle lO installed at the position where bubbles are most likely to occur.
By spraying toward the back side of the bubble, the bubbles are washed away by the spray water and disappear immediately, and the flammable gas trapped in the bubbles is dispersed into the surrounding air atmosphere. The spray water flows down into the drain tray 9 and is drained out of the system together with the filtrate of the sludge.

Therefore, even if electric sparks are scattered between the press belt 2 and the current collecting brush 6 that slides on the belt surface as the press belt 2 circulates during electroosmotic dehydration operation, flammable gas will not be absorbed into the surrounding air. There is no risk of explosion as the concentration is low.

In addition, foreign matter such as sludge slag adhering to the back surface of the press belt 2 is also washed away and cleaned by the jet of washing water, so that good electrical contact can be maintained between the press belt 2 and the current collecting brush 6. It remains stable and can maintain one current collection.

[Effects of the Invention: ζ Temperature dehydrator according to the present invention: Since it is constructed as described above, the following effects are achieved.

In other words, by installing a water spray nozzle that sprays cleaning water onto the back side of the press belt in parallel to the current collector plane that slides on the back side of the press belt, ignition that occurs on the back side of the press belt due to the properties of the sludge can be prevented. It is possible to improve safety by washing away foam containing scum with a spray of cleaning water and preventing flammable gas from detonating due to electric sparks generated between the current collector blank and the press belt. .

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an electroosmotic dehydrator according to an embodiment of the present invention, and FIG. 2 is a sectional view of the main structure in FIG. 1. In the figure, there is a rotating drum, 2 nibless belts, 3; filter cloth belt, 4
．． Power supply, 6: Current collector blank, 10: Water spray nozzle, 1
2-Sludge. Ihe Danboku Iwao Yamaguchi 3'5. /L square, 10k square)
Suru・Figure 1 V Δ 112

Claims (1)

[Claims] 1) An electroosmotic dewatering machine that uses a rotating drum and an endless press belt stretched around the drum as opposed electrodes to dehydrate sludge supplied to a passage between the opposed electrodes, A current collector brush is arranged on the back side of the dewatering section to connect between the power source and the press belt, and a water spray nozzle for spraying cleaning water onto the back side of the press belt is installed in parallel to the current collector brush. An electroosmotic dehydrator characterized by