JPH074489B2 - Sludge scraping method and rotary drum type filter using the same - 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 scraping method for a stock solution containing sludge and a rotary drum type filter using the same.

[0002]

2. Description of the Related Art A rotary drum type filter in which a rotating filtration drum is housed inside a stock solution tank and sludge is filtered on the surface of the filtration drum has been widely known.
Then, on the side of the filter drum of such a rotary drum type filter, a scraping plate having sharp edges is provided, and a layer of sludge adhering to the surface of the filter drum is utilized by using the rotation of the filter drum. It is supposed to be scraped off. However, when the sludge particles are fine, the sludge layer is firmly solidified on the surface of the filtration drum, and the scraping by the scraping plate may not be successful.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art and is able to successfully scrape off a layer of sludge adhering to the surface of a filtration drum by a scraping plate even when the sludge particles are fine. The present invention has been completed to provide a possible sludge scraping method and a rotary drum type filter using the same.

[0004]

[Means for Solving the Problems] The above problem is solved by rapidly reducing the pressure inside the stock solution tank when the sludge layer deposited on the filtration drum housed inside the stock solution tank becomes thick. Can be expanded, and the sludge can be scraped off by a scraping plate disposed on the side of the filtration drum. Further, the above problem is, in a rotary drum type filter containing a rotating filtration drum inside a stock solution tank, in a stock solution supply system or a sludge discharge system to the stock solution tank, when the pressure inside the stock solution tank rises above a predetermined value. In addition to connecting a control means for rapidly reducing this pressure to the side of the filtration drum, a scraping plate for scraping off the sludge expanded due to this pressure drop is installed, and the problem is solved by a rotary drum type filter. You can

[0005]

The present invention will be described below in more detail with reference to the illustrated embodiments. In FIG. 1, 1 is a stock solution tank, 2 is a rotating filtration drum housed therein, and 3 is a stock solution supply pipe for supplying the stock solution pressurized by a pump 4 into the stock solution tank 1. The rotary shaft of the filtration drum 2 is a clarified filtrate discharge pipe 5, the stock solution is filtered on the surface of the filter drum 2, and the filtrate is discharged from the clarified filtrate discharge pipe 5 to the outside. Reference numeral 6 is a scraping plate obliquely installed on the side of the filtration drum 2. A hopper portion 7 for receiving the scraped sludge and a sludge discharge pipe 8 are provided on the outer side thereof.

In the present invention, a pressure gauge 9 is provided inside such a stock solution tank 1, and the pressure inside the stock solution tank 1 measured by this is input to a control circuit 10.
The control circuit 10 is for rapidly reducing the pressure inside the stock solution tank 1 when the pressure rises above a predetermined value. For that purpose, for example, a signal is sent to the pump 4 of the stock solution supply pipe 3 described above. The rotation speed may be reduced or the valve 11 of the sludge discharge pipe 8 may be opened.

[0007]

In the rotary drum type filter of the present invention thus constructed, the internal pressure of the stock solution tank 1 is normally maintained while the amount of sludge deposited on the surface of the filter drum 2 is small. As shown in FIG. 2, the filtration proceeds in the same manner as the conventional one. However, as the amount of sludge accumulated increases, the pressure loss in the filtration drum 2 increases, and the pressure inside the stock solution tank 1 gradually rises. This state is shown in FIG.

In this way, when the pressure inside the stock solution tank 1 exceeds a predetermined value, the pressure gauge 9 detects this and the control circuit 1
0 sends a signal and sends a signal to the pump 4 to reduce the number of rotations thereof, or to open the valve 11 of the sludge discharge pipe 8 to rapidly reduce the pressure inside the stock solution tank 1.
Due to such a pressure drop, the layers of the precoat material and the filter material adhering to the surface of the filtration drum 2 expand as shown in FIG. 4, and the sludge layer also expands outward. As a result, the tip of the scraping plate 6 installed on the side of the filtration drum 2 bites into the expanded sludge layer, and the sludge is scraped off by the scraping plate 6. In this case, even if the particle size of the sludge is small and the sludge layer is hard, the sludge layer is in a state of being pushed out by expansion, so that it can be smoothly scraped off by the scraping plate 6. When the pressure in the stock solution tank 1 returns to a predetermined value by scraping in this way, the control circuit 10 causes the pump 4 and the valve 11 to operate.
Will be returned to the original state, and filtration will be started again.

In order to more fully expand the sludge layer to the outside as described above, the filter drum 2 is replaced with a conventional rigid material, and elastic porous material such as porous rubber or sponge is used. It may be made of a quality material. This makes it possible to scrape off the sludge more reliably.

As described above, according to the sludge scraping method of the present invention, when the sludge layer accumulated on the filtration drum becomes thick, the pressure inside the stock solution tank is rapidly lowered to make it sludge layer. Is expanded and the scraping plate disposed on the side of the filtration drum scrapes sludge,
Even if the sludge particles are fine, the sludge layer can be scraped off smoothly. Further, according to the rotary drum type filter of the present invention, the control circuit automatically scrapes off the sludge by measuring the pressure inside the stock solution tank, so that the filtration can be always performed in a good condition. . Therefore, the present invention has a great contribution to the industry as a solution to the conventional problems.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a filtration drum at normal pressure.

FIG. 3 is a cross-sectional view showing the filtration drum when the pressure reaches a predetermined value.

FIG. 4 is a cross-sectional view showing the filtration drum when the pressure is reduced.

[Explanation of symbols]

 1 stock solution tank 2 filtration drum 3 stock solution supply pipe 4 pump 5 clarified filtrate discharge pipe 6 scraping plate 7 hopper 8 sludge discharge pipe 9 pressure gauge 10 control circuit 11 valve

Claims (3)

[Claims] 1. When the sludge layer accumulated on the filtration drum housed inside the stock solution tank becomes thicker, the pressure inside the stock solution tank is rapidly reduced to expand the sludge layer and to the side of the filtration drum. A sludge scraping method, which comprises scraping off the sludge by a scraping plate arranged in the. 2. A rotary drum type filter containing a rotating filtration drum inside a stock solution tank, when the pressure inside the stock solution tank rises above a predetermined value in a stock solution supply system to the stock solution tank or a sludge discharge system. A rotary drum type filter characterized in that a control means for rapidly reducing this pressure is connected, and a scraping plate for scraping off the sludge expanded by this pressure decrease is installed on the side of the filtration drum. 3. The rotary drum type filter according to claim 2, wherein the filtration drum is made of a porous material having elasticity.