JPS59230614A - Method and apparatus for rotary type vacuum filtering - Google Patents

Abstract

PURPOSE:To enable treatment generating no clogging by one stage of a disc filter and to attain decrease in cost, by performing filtering through formation of at least two layers consisting of a mat comprising a filter agent and a mat comprising a substance to be filtered. CONSTITUTION:When a sweetener 22 or a sweetener mixture 22b is supplied from an inlet box 14 and while water 21 is supplied from a second inlet box 27, liquid layer of the sweetener 21 or the sweetener mixture 22b is constituted at a water level near to a liquid surface 28 while the liquid layer of white water 21 is constituted therebelow. When a rotary disc 3 advances in the liquid, the mat 29 of the sweetener 22 or the sweetener mixture 22b is at first formed on the filtering surface of a sector 12 and, thereafter, the mat 30 of white water 21 is formed. As a result, the fine solid substance in the white water is surely collected by the first layer comprising the liquid layer of the sweetener 22 or the sweetener mixture 22b and, even in the clarification and filtering of the white water with a high concn., treatment is enabled by one stage of disc filter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary vacuum filtration method and device that can be applied to a vacuum polydisk filter, a drum vacuum dehydrator, and the like.

In conventional paper machines, pulp slurry is filtered and dehydrated during the process of forming paper layers. The filtrate at this time is called white water, and this white water contains fine inorganic fillers passed through the paper machine wire and solids such as fine pulp fibers.

In order to reuse this white water as process water, it is necessary to filter and separate the solids, and generally a vacuum filtration type disc filter shown in FIG. 1 is used. However, if white water is filtered as it is, most of the solids will pass through or the filter will become clogged, so a pulp slurry called Sui-1-su is mixed as a filter aid (this mixture is hereinafter referred to as mixed slurry).

The structure and principle of a disk filter are shown in FIGS. 1 to 4. The apparatus shown in FIG. 1 includes a vat 2.1 for storing mixed slurry 1.
．． A disk 3 constituting the S filtration surface, a center shaft 5 that holds the disk 3 through the sector mounting hole 4 and has a filtrate flow path 5a, and a valve that connects this to a vacuum system and discharges the slurry to the outside. It is composed of a header 6, a sliding surface 7 for maintaining airtightness between the valve header 6 and the center shaft 5.
There is.

The valve header 6 includes a semi-turbid filtrate boat 8 for collecting semi-filtrate 10 and a clarified filtrate boat 9 for collecting clarified liquid 11.
is provided. In FIG. 1, the position of the semi-turbid filtrate port 8 is shifted upward for clarity, but in reality it is below the liquid level as shown in FIG. 3. Further, an intermediate port is provided between the semi-turbid filtrate port 8 and the clear filtrate port 9, but it is omitted in the drawing.

FIG. 2 illustrates the structure of the disk 3 and center shirt 1-5 in more detail. The disk 3 is composed of a plurality of sectors 12, and each sector 12 is attached to the same number of slot holes 4 as the sectors 12 provided in the center shaft 5 for each stage of the disk 3. The interior of the center shaft 5 has a space, and is partitioned by partitions 13 corresponding to the number of sectors 12 passing through the center shaft 5 in the axial direction.
This is a mud liquid flow path 5a. □ FIG. 3 is a sectional view taken along line A-A in FIG. 1, and the disk 3 rotates counterclockwise. Further, an inlet box 14 is provided at the left end of the vat 2 over the entire length in the axial direction, and the mixed slurry 1 is continuously supplied from the bottom and flows into the hunt 2 via a weir 15.

Next, when the disk 3 rotates and the sector 12 approaches the semi-turbid filtrate port 8, suction is started through the filtration surface 16 of the sector 12, and the solids suspended in the mixed slurry 1 are collected on the surface of the filtration surface 16. At the same time as the cloak is formed, the semi-turbid waves 10 are collected.

In addition, as the sector 12 progresses, the mantle grows, so the filtrate is clarified, and the filtrate is transferred from the clarified liquid reduction boat 9 to the clarified liquid reduced liquid 1.
1 is collected. When the sector 12 leaves the liquid level 17,
The mat will be collected outside the aircraft.

FIG. 4 shows the i-side of the sector 12. The sector 12 consists of a sector core 18 and a magazine cloth 19, and 20 indicates a generated cloak.

In this way, the white water is clarified and reused, but recently the number of twin-wire type paper machines has increased. The white water of this model has a high concentration, and the filtrate is not clear enough to be reused when treated with a single stage disc filter as in the past. Therefore, the actual situation is that two stages of processing are carried out using disk filters in series. Therefore, there were drawbacks such as the initial cost, running cost, and installation area being doubled.

FIG. 5 conceptually shows the state of conventional two-stage processing.

In FIG. 5, the first stage is on the left, and the second stage is on the right. The mixed slurry 1 supplied to the first stage is white water 21
and Suitona 22.

This Suitona 22 is used as a filter aid.

23 is the first stage semi-turbid wave, and 24 is the first stage clear filtrate. In addition, the concentration of the clarified reduced liquid 24 in the first stage is several + ppn
The following is desirable, but since the amount reaches 10 times or more, the respective filtrates 23 and 24 are remixed, and Suitoner 22 is added to this.
Mix a and perform the second stage treatment. 25 and 26 are a semi-turbid filtrate and a clear reduced liquid in the second stage, respectively, and similar clear a filtrate is recovered by performing the two-stage treatment in this way. However, this conventional device has two rows of disk filters, which has the disadvantage of high cost.

The present invention has been proposed in order to solve the above-mentioned drawbacks of the conventional art, and involves supplying a substance to serve as a filter aid to form a pine layer 1- of the filter agent on the first layer on the cutting surface. It is an object of the present invention to provide a rotary vacuum filtration method characterized in that a filtered material mat is formed in a second layer on the second layer by supplying the filtered material, and at least two layers of filtered material cloak are formed and the filtered material is directly passed through the mat. It is something to do.

In addition, the present invention provides a rotary vacuum filtration system that can perform clogging-free processing with one stage of disc filters and reduce costs by providing a plurality of inlet boxes in the butt of the rotary vacuum filtration machine. The aim is to provide the equipment.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 6 shows a second in-reflex box 27 in addition to the bat 2 of FIG. 3.
It has been established. 'ff52 inlet box 2
Similarly to the inlet box 14, the reference numeral 7 is provided over the entire length in the axial direction. Also, inref 1-box 14
Next, the suitosu 22 and the mixed suitoner 22b, which is the same suitoner 22 mixed with a small amount of white water, are supplied. On the other hand, a two-stage liquid supply system is adopted in which white water 21 is supplied to the second inlet box 27. Note that 10a and lla are a semi-turbid filtrate and a clear filtrate, respectively. Further, 3 is a disk, 6 is a valve header, 12 is a sector, and 16 is a filtering surface, which are the same as the conventional ones shown in FIGS. 1 to 5.

Now, since the Suitoner 22 or the mixed Suitoner 22b is supplied from the inlet box 14 and the white water 21 from the second inlet box 27, the liquid layer of the Suitoner 22 or the mixed Suitoner 22b is at a water level close to the liquid level 28 at the bottom. A liquid layer of white water 21 is formed. When the rotating disk 3 moves through the liquid, first a mat 29 of suitosu 22 or mixed sutona 22b is formed on the filtering surface 16 of the sector 12, and then man 1-30 of white water 21 is formed.

FIG. 7 is a cross-sectional view of the sector 12 showing the state of formation of the cloak, and shows the mat 29 of the suitona 22 or the mixed suitosu 22b.
This shows a state in which 2N is formed with a mat of white water 21 at 3° on top of it.

Conventionally, a mixed slurry of white water and Suitona was supplied to the disc filter using a so-called body feed method, but in the present invention, Suitona and white water are separately supplied in two stages, and the slurry is fed to the first layer. By forming a cloak and giving it a pre-coat function, fine solids in white water are reliably collected in the first layer, and even when clarifying and filtrating highly concentrated white water, it can be processed in one stage of the disc filter. This also eliminates the problem of clogging.

On the other hand, basic experiment results show that with one-stage treatment using mixed slurry,
Semi-turbid filtrate concentration 2000ppm, clear filtrate concentration 300p
pm, but according to the present invention, the total of both is 20
pprr became less than 1. Furthermore, since the filtration speed is the same as the conventional one, although there is a cost increase due to the addition of the second inlet box, the overall cost can be reduced to approximately 2.

[Brief explanation of drawings]

Fig. 1 is a partial side view showing an example of a conventional disc filter, Fig. 2 is a perspective view of the same main part, and Fig. 3 is A of Fig. 1.
-A sectional view, FIGS. 4(A) and 4(B) are sectional views showing the formation state of the cloak on the sector core in FIG. 1, respectively, and FIG. 5 is a front view conceptually showing the conventional two-stage processing disk filter. 11i side view, FIG. 6 is a front sectional view of a rotary vacuum filtration device showing an embodiment of the present invention, and FIGS. It is. Explanation of the main parts of the figure 2-・Hesotho 3-・Disk 10a-・-
Semi-turbid filtrate 11a - Clear υ & liquid 12 - Sector
14-Inlet box 16・-Filtration surface
18-Sector core 21-White water (filtered material) 22-・-Suitona 22b-・Mixed Suitona 2
7-Second inlet box 29-First layer mantle 30-・Second layer manoto rA
Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] (Kl di) A mat formed by the filtering agent is formed on the ff11 layer on the filtering surface by supplying a substance to be a filter aid, and then a mat is formed on the ff11 layer on the filtering surface by supplying a substance to be filtered. A rotary vacuum filtration method characterized by forming a filtrate mantle in layers and forming at least two layers of filtration mats for filtration. (2) A plurality of inlet boxes are installed in the butt of a rotary vacuum filtration machine. A rotary vacuum filtration device characterized by: