JP2002153711A - Vacuum filter using laminated filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary cylindrical vacuum filter using a laminated filter, especially, laminating filter media to enable precise filtering. SOLUTION: In the vacuum filter wherein a vacuum drum (1) having a filter medium provided on the peripheral part thereof under tension is immersed in a raw liquid tank (2) in a freely rotatable manner and a filtrate is sucked in the filter chamber 4 of the vacuum drum (1) to perform solid-liquid separation, the long filter (8) is wound around the outer peripheral surface of the vacuum drum (1) in a multilayered state to form a laminated filter (8a) and the filter (8) of the surface layer of the laminated filter (8a) is separated from the vacuum drum (1) by rotating the vacuum drum (1) to be taken up by a taking-up roll (11). The meshes of the laminated filter (8) become fine and fine particles in a raw liquid are caught to enable precise filtering. If the filter 8 is separated from the vacuum drum (1), a dehydrated cake is placed on the filter (8) and can be easily peeled from the filter (8). Therefore, the filter becomes a filter medium having strength and peelability and prevented from clogging and can be used repeatedly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary cylindrical vacuum filter using a laminated filter, and more particularly, to an improvement in a vacuum filter capable of precision filtering by laminating long filters.

[0002]

2. Description of the Related Art Conventionally, a precoat layer is formed on a surface of a vacuum drum immersed in a stock solution tank with diatomaceous earth or the like, and while the precoat layer on the filtration surface is slightly scraped, a cake captured by the precoat layer is scraped. Is
For example, it is well known as described in JP-A-56-89814. Also, a filter cloth reciprocating filter in which a filter cloth such as a nonwoven fabric is wound around a vacuum drum immersed in a stock solution tank, and both ends of the filter cloth separated from the vacuum drum are wound up and fastened to an unwinding shaft, for example, Utility model registration No. 302
It is known as described in US Pat. Further, a vacuum filter using a metal mesh as a filter material of the vacuum drum and having a peeling strip running in synchronization with the metal mesh is also disclosed in, for example, Utility Model Registration No. 2553598. Applicant has proposed.

[0003]

However, the conventional precoat filter described above always captures the SS of the stock solution inside the diatomaceous earth and partially cuts the diatomaceous earth surface by cutting the surface of the diatomaceous earth inside the diatomaceous earth. By selecting the particle size of diatomaceous earth, it is possible to perform high-clarity filtration corresponding to the particle size of SS in the stock solution. The diatomaceous earth cannot be incinerated and will be discarded. For this purpose, reuse of diatomaceous earth has been considered, but this has led to an increase in cost. In the case of a filter cloth reciprocating filter in which a nonwoven fabric is wound around a vacuum drum,
Although the nonwoven fabric can be incinerated, it is difficult to obtain a filtrate having a higher degree of clarity as compared with a precoat filter. In addition, a filter using a metallic filter medium as a filter medium has a good cake peeling property and is durable, but the filter medium has a large mesh, and fine SS content in the stock solution is reduced from the screen mesh. There was a drawback. SUMMARY OF THE INVENTION The present invention provides a vacuum filter that enables microfiltration using a stacked filter as a filter medium and enables continuous operation for a long time.

[0004]

SUMMARY OF THE INVENTION The gist of the present invention is that a vacuum drum having a filter medium stretched around its periphery is rotatably immersed in a stock solution tank, and the filtrate is sucked into a filtration chamber of the vacuum drum to separate solid and liquid. In the filter, a long filter is wrapped around the outer peripheral surface of the vacuum drum in multiple layers to form a laminated filter, and the vacuum drum is rotated to separate the filter on the surface layer of the laminated filter from the vacuum drum and take up. Since it is wound up in a roll, the eyes of the laminated filter become finer, and fine particles in the sludge are also captured, and microfiltration similar to a precoat filter can be performed. Then, when the filter is separated from the vacuum drum, the dehydrated cake is placed on the filter, and the cake can be easily peeled off from the filter, and can be repeatedly used after washing or the like. If the filter is made of a metal mesh, a filter medium excellent in strength can be obtained and the releasability can be improved. If the metal mesh is a twilled woven filter medium, the stitches are arranged in the direction in which the filter medium is transferred, so that clogging is reduced and the processing capacity is increased. In addition, if an inexpensive nonwoven fabric is used as the filter, the clogged filter cloth can be discarded and incinerated together with the separated cake.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The apparatus according to the present invention is configured as described above, supplies a stock solution to be filtered to a stock solution tank, and winds a vacuum drum while winding the filter on the surface layer of the laminated filter around a winding roll. By rotating and vacuum-suctioning from the filtration chamber of the vacuum drum immersed in the stock solution,
S is adsorbed on the filter on the surface layer of the laminated filter,
The filtrate separated from the SS is sucked into the filtration chamber (adsorption zone). S adsorbed on the laminated filter and moved to the liquid level
In S, the filtrate is sucked into the filtration chamber and dehydrated (dehydration zone). Next, the dewatered cake is placed and transferred on a filter separated from the vacuum drum, and the filter from which the cake has been discharged is wound up on a take-up roll. Then, when the stacked filter wound around the vacuum drum is terminated, if the vacuum suction of the vacuum drum is stopped and the vacuum drum is rotated in reverse, the unwound filter is wound around the vacuum drum to form a stacked filter. Then, solid-liquid separation can be performed again. In the vacuum drum of the present invention, since the filters are stacked, the screen has finer meshes, and small particles can be captured to increase the recovery rate. Then, a plurality of filters are polymerized to form a laminated filter,
This also increases the strength of the filter medium.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vacuum filter using a laminated filter according to the present invention will be described in detail with reference to the drawings.
In the figure, reference numeral 1 denotes a vacuum drum rotatably supported by partially immersing a part thereof in a stock solution tank 2 and divided by a partition plate 3 in the width direction of the vacuum drum 1 to form a large number of filtration chambers 4. It is provided on the periphery. A suction pipe 5 is connected to each of the filtration chambers 4, and a start end of the suction pipe 5 is connected to a small hole 7 of a rotary valve 6 provided at the axis of the vacuum drum 1. A fixed valve (not shown) is in sliding contact with the rotary valve 6, and a small hole 7 of the rotary valve 6 communicating with the filtration chamber 4 of the vacuum drum 1 is connected to a vacuum source via the fixed valve (not shown). They are communicating.

Reference numeral 8 denotes a filter whose one end is fixed to the outer peripheral surface of the vacuum drum 1, which is wrapped around the vacuum drum 1 multiple times to form a laminated filter 8a, which is laminated to form a fine screen. Thus, microfiltration can be performed by capturing SS in the stock solution. The filter 8 of the surface layer of the laminated filter 8a is separated from the vacuum drum 1 and is wrapped around a peeling roll 9, and the dewatered cake separated from the vacuum drum 1 is placed on the filter 8 of the surface layer and the peeling roll 9 is removed. It is designed to be peeled off when running in reverse. A washing nozzle 10 is provided in the vicinity of the back surface of the filter 8 behind the peeling roll 9, and high-pressure water is sprayed from the back surface of the filter 8 from which the cake has been peeled, so that the attached residue is washed away. is there. The washed filter 8 is fixed to a take-up roll 11, and the filter 8 is wound around the take-up roll 11. The vacuum drum 1 and the take-up roll 11 are connected to a forward / reverse rotation driving device (not shown) so that the take-up roll 11 is rotated in conjunction with the vacuum drum 1 so that the vacuum drum 1 is continuously driven. Driving or intermittent driving may be used. When the laminated filter 8a of the filter 8 wound around the vacuum drum is at the end, if the driving device is rotated in reverse, the unwound filter 8 is wound around the vacuum drum 1 again to form the laminated filter 8a. It is.

[0008] If the filter 8 is a metal mesh,
A filter medium excellent in strength is obtained, and the releasability is improved. Even if the metal mesh has a large screen mesh as a filtering material, the mesh of the laminated metal mesh is fine and the fine particles in the stock solution are also captured, enabling microfiltration similar to a precoat filter. If the metal mesh is a twilled woven filter medium, the stitches are arranged in the direction in which the filter medium is transferred, so that clogging is reduced and the processing capacity is increased. If a non-woven fabric is used as the filter 8, the filter material is inexpensive, a thin and small-sized one can be used, and the clogged non-woven fabric together with the separated cake can be discarded and incinerated. And these filter media can obtain the effect of capturing SS by lamination,
The metal mesh and the non-woven fabric used as the filter 8 may be coarse with good reproducibility by washing. The coarseness and the number of layers of the filter medium are selected according to the pressure loss, the liquid property, the concentration, and the method of post-treatment of the solid matter.

[0009] In order to predict whether filtration is possible with a metal screen wrapped around the vacuum drum 1 immersed in the undiluted solution in multiple layers, and to estimate the degree of reduction in filtration speed, a test was conducted with a vacuum dehydrator under the following conditions. Was performed. Filter material: metal mesh of twill tatami weave with screen mesh of 600 mesh Number of layers wound around a vacuum drum: 1, 5, 10, 1
5, 20 (sheets) Test liquid: tap water to which 5% W / V (wet base) diatomaceous earth is added Table 1 shows the number of filter media (sheets) on the horizontal axis and the filtration rate (Kg) on the left vertical axis
/ M ² h), taking the cake moisture (%) on the right vertical axis, and predicting the filtration speed and cake moisture of the multilayer filter wound multiple times from the test results. From Table 1, from the graph of the number of filter media (X) and the filtration speed (Y), Y = 7
An approximate expression of 9.205X ^-0.015 can be derived. The approximate expression of the number of filter media (X) and the cake moisture (Y) is Y = 61.
A 06X ^{-0.0 006.} From this approximation formula, when a metal mesh is wrapped around a vacuum drum,
The filtration speed was 79 kg / m ² h. Assuming that the filtration speed is 100%, the laminated filter of 50 sheets is 7
4.7 kg / m ² h filtration rate, 100-ply laminated filter can be expected to be a filtration rate of 73.9Kg / m ² h. Also, the cake moisture has an approximate line gradient of -0.0008.
There is no change, and it can be predicted that there is almost no increase in cake moisture even in a stacked filter in which 50 or 100 sheets are stacked.

[0010]

[Table 1]

As shown in FIG. 2, the filter 8 according to the present invention uses, for example, a metal mesh having a thickness of 0.5 to 1.0 mm and a filter medium length of 400 m, and a drum diameter of 1.5 mm. When the metal mesh is wound around the metal drum, a laminated filter 8a having a thickness of about 80 mm is formed on the metal mesh, the screen becomes finer, and fine filtration can be performed. If the thickness of the filter medium detached from the metal mesh separating from the vacuum drum 1 is set to 10 mm / h, the operation time can be performed at 8 h / cycle.
This enables continuous operation for approximately one day.

[0012]

As described above, the vacuum filter using the laminated filter of the present invention can approximate the pre-coating by separating the laminated filter cloth from the vacuum drum as the filtration proceeds and removing the filter cloth on the surface layer from the vacuum drum. It is expected that a filtration mechanism will be used. That is, the filter is wound around the vacuum drum in multiple layers to form a laminated filter, the filter on the surface layer is separated from the vacuum drum, and the cake captured on the metal mesh is peeled off. Particles are also trapped and microfiltration is possible. If the filter of the surface layer is separated from the vacuum drum, the cake can be easily peeled from the vacuum drum. If the filter is a metal mesh, the filter becomes a filter medium having strength and releasability, and can be used repeatedly. If this metal mesh is made into a twill tatami weave, a filter medium excellent in strength can be obtained, stitches are arranged in the direction of transport of the filter medium, clogging is reduced and processing capacity is increased. In addition, if a nonwoven fabric is used as a filter, the filter medium is inexpensive and a thin and small opening can be used, and the clogged nonwoven fabric can be discarded and incinerated together with the cake.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal side view of a vacuum filter using a laminated filter according to the present invention.

FIG. 2 is a conceptual diagram showing a state where a filter is wound around the vacuum filter according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum drum 2 Stock solution tank 4 Filtration chamber 8 Filter 8a Multilayer filter 11 Winding roll

Claims (4)

[Claims] 1. A vacuum drum (1) having a filter medium stretched around its periphery.
Is rotatably immersed in the undiluted solution tank (2), and the filtrate is sucked into the filtration chamber (4) of the vacuum drum (1) to perform solid-liquid separation on the outer peripheral surface of the vacuum drum (1). A long filter (8) is wound in multiple layers to form a laminated filter (8a), and the vacuum drum (1) is rotated to filter the surface layer of the laminated filter (8a) (8).
Is separated from the vacuum drum (1) to take up the winding roll (1).
A vacuum filter using a laminated filter, which is wound up in 1). 2. A vacuum filter using a laminated filter according to claim 1, wherein said filter (8) is a metal mesh. 3. The vacuum filter using a laminated filter according to claim 2, wherein the metal mesh is a twill tatami weave. 4. The vacuum filter using a laminated filter according to claim 1, wherein said filter is a non-woven fabric.