JPH075846Y2 - Rotating drum type precoat filter - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary drum type precoat filter for filtering a stock solution containing a sludge such as a grinding solution by a precoat layer on the surface of a filter drum.

[0002]

2. Description of the Related Art A rotary drum type precoat filter is a filtrate obtained by filtering a stock solution while rotating a filtration drum having a precoat layer directly formed on the surface of a filter material supported by a drum type support material in a stock solution tank. Is discharged from the filtrate discharge port of the filtration drum. Then, a scraping plate having a sharf edge installed on the side of the filtration drum scrapes off the sludge accumulated on the surface of the filtration drum.

However, when the sludge particles are fine,
In some cases, sludge sticks firmly to the surface of the filtration drum and cannot be easily scraped off. Therefore, when the sludge is accumulated on the filtration drum, the present applicant rapidly expands the sludge by lowering the internal pressure of the stock solution tank, and scrapes the expanded sludge by a scraping plate arranged on the side of the filtration drum. Has developed a rotary drum type precoat filter and has already applied for it as Japanese Patent Application No. 3-44249.

However, in the rotary drum type precoat filter of this prior application, since the filter drum is made of a rigid material such as punching metal, expansion may be insufficient depending on the thickness of the sludge layer. For this reason, there is a problem that the thickness of sludge that can be scraped by one scraping operation is limited, the number of scrapes performed after stopping the filtration is increased, and the filtration time is shortened.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and increases the thickness of the sludge layer that can be scraped by one scraping operation to reduce the number of times sludge is scraped. The present invention has been completed to provide a rotating drum type precoat filter that can prolong the filtration time.

[0006]

SUMMARY OF THE INVENTION The present invention, which has been made to solve the above-mentioned problems, is designed to expand the sludge by rapidly reducing the internal pressure of the stock solution tank when sludge is accumulated on the filtration drum. A rotary drum type precoat filter of a scraping type by a scraping plate arranged on the side of the drum, wherein an outer cylinder made of a porous material having elasticity is attached to the outer periphery of a liquid-permeable supporting inner cylinder. It is characterized by being wrapped.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. 1 and 2, reference numeral 1 denotes a cylindrical stock solution tank, and a precoat type rotatable filtration drum 2 is provided in the stock solution tank 1. The filtration drum 2 is formed by winding an outer cylinder 5 made of a porous material having elasticity around an outer periphery of a liquid-permeable support inner cylinder 4 having a large number of through holes 3 formed therein, and a center part on one side thereof Has a filtrate outlet 6 formed therein. The support inner cylinder 4 has strength as a structural material such as stainless steel having a large number of through holes 3 or fiber reinforced plastic having a large number of through holes 3, porous ceramics, and liquid permeability. If so, the material is not limited. The outer cylinder 5 is made of a porous material having sufficient elasticity such as felt, porous rubber, sponge rubber.

Inside the stock solution tank 1, there is provided a scraping plate 7 adjacent to the filtration drum 2. The scraping plate 7 scrapes off the sludge adhering and deposited on the surface of the filtration drum 2 together with the precoat to a sludge reservoir 8. It is intended to fall. Reference numeral 9 is a sludge discharge port formed at the lower end of the sludge reservoir 8 and 10 is a precoat liquid supply port.

[0009]

With this structure, first, the precoat liquid is supplied from the precoat liquid supply port 10 to form a precoat layer on the surface of the outer cylinder 5 having elasticity of the filtration drum 2. When the stock solution is supplied into the stock solution tank 1 after the precoat layer is formed, the stock solution is filtered by the precoat layer of the filtration drum 2. Then, the filtrate in the filtration drum 2 is discharged to the outside from the filtrate discharge port 6 provided in the central portion on one side of the filtration drum 2. When the filtration is performed as described above and sludge is attached to the precoat layer of the filtration drum 2 to increase the filtration resistance, the supply of the stock solution to the stock solution tank 1 is stopped and the pressure in the stock solution tank 1 is rapidly reduced. Let

As a result, the pressure inside the filter drum 2 becomes relatively higher than the pressure on the outside, and the outer cylinder 5 wound around the support 4 of the filter drum 2 and made of an elastic porous material.
Expands due to the pressure difference. At the same time, the sludge layer also expands, so that the sludge is scraped off by the scraping plate 7 from the surface of the rotating filtration drum 2. The sludge thus scraped off by the scraping plate 7 falls into the sludge reservoir 8 and is discharged from the sludge discharge port 9.

FIG. 3 shows another embodiment of the outer cylinder 5 having elasticity. The outer cylinder 5 is made of felt having a raised surface (5a) on one side. Alternatively, the filter drum 2 is formed by winding a plurality of layers. The felt thickness is, for example, 1.4 mm to 3 mm, and the raised portion is 30 to 60% of the felt thickness. It is preferable to wind the felt in multiple layers because the expansion rate of the outer cylinder 5 increases and the scraping amount of the scratch plate 7 increases when the stock solution tank 1 is depressurized. Is increased,
When the length of the filtration drum 2 was set to 300 mm, it was most suitable that the felt having a thickness of 3 mm was wound twice. Further, the raised surface (5a) of the felt may be wound as an inner side or an outer side, but if the inner side is wound, the elastic deformation amount at the time of decompression becomes large and the scraping effect of the precoat layer becomes large. Is.

FIG. 4 shows another embodiment of the support inner cylinder 4 of the filtration drum 2, which has a drum-like shape in which the central portion has a smaller diameter than the both side portions. By making the central portion thin in this way, it is possible to further increase the expansion amount of the outer cylinder 5 having elasticity when the pressure is reduced. For example, when the filter medium 5 is a porous rubber having a thickness of 5 mm, the length of the support 4 is 400 mm, and the outer diameters of both sides are 300 mm, the precoat layer has the best peeling effect when the outer diameter of the central portion is 298 mm. it was high.

[0013]

As is apparent from the above description, the present invention reduces the pressure reduction by providing the outer cylinder of the porous material having elasticity around the outer circumference of the liquid-permeable supporting inner cylinder. At this time, not only the sludge layer but also the filtration drum itself can be expanded, and the scraping amount by the scraping plate can be increased. As a result, the filtration time in the filtration cycle becomes longer and the filtration efficiency can be improved. Further, by using a felt having a raised surface on one side as in the example, it is possible to increase the amount of expansion of the filter medium during depressurization, increase the amount of scraping of the precoat layer, and further lengthen the filtration time. it can.
Further, as in the other examples, if the diameter of the central portion of the support of the filtration drum is made smaller than that on both sides, more preferable results can be obtained. Therefore, the present invention is of great practical value as a rotary drum type precoat filter that eliminates the conventional problems.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view of a filtration drum.

FIG. 3 is a perspective view showing another embodiment.

FIG. 4 is a partially cutaway perspective view showing still another embodiment.

[Explanation of symbols]

 1 undiluted solution tank 2 filtration drum 4 supporting inner cylinder 5 outer cylinder 6 filtrate outlet 7 scratching plate

Claims (3)

[Scope of utility model registration request] 1. When sludge is accumulated on the filtration drum (2), the sludge is expanded by rapidly lowering the internal pressure of the stock solution tank (1), and the sludge disposed on the side of the filtration drum (2) is expanded. A rotary drum type precoat filter scraped by a plate (7), wherein the filter drum (2) is an outer cylinder made of a porous material having elasticity around the liquid-permeable supporting inner cylinder (4).
A rotating drum type precoat filter characterized in that (5) is wound. 2. The rotary drum type precoat filter according to claim 1, wherein the outer cylinder (5) of the filtration drum (2) is made of felt with one surface being a raised surface (5a). 3. A liquid-permeable support tube (4) for a filtration drum (2).
The rotary drum type precoat filter according to claim 1, wherein the center portion is formed in a drum shape having a smaller diameter than both side portions.