JP2799376B2 - High-speed filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application fields> The present invention relates to tap water for industrial works, sewage, river water, lake water, coagulated sedimentation supernatant water, various process intermediate water, various recovered water, various wastewater, biological treatment equipment The present invention relates to a high-speed filter for removing suspended matter in a stock solution such as treated water or valuables-containing liquid, liquor, oil and the like.

<Prior Art> Various filters have been conventionally used for the purpose of removing a suspension in a stock solution.

For example, a filter that removes a relatively large suspension in a stock solution with a screen such as a wire mesh is a type of filter, and a filter that finely filters fine particles in a stock solution using a filtration membrane having fine pores is also used as a filter. Is a kind of One type of a filter is to precoat a filter aid with a filter aid and filter the suspension with the precoat layer.

As described above, various types of filters are used according to the type of the stock solution and its purpose, and the most commonly used filter is a packed bed type filter.

The packed bed filter fills a filtration tower with a particulate filter medium such as filter sand or anthracite or a filter medium such as a short fiber or a fiber ball, and allows the undiluted liquid to flow through the packed bed in a downward flow or an upward flow. To capture the suspension in the stock solution with the packed bed,
Filtrate is obtained, and filtration is terminated due to an increase in pressure loss or deterioration of the quality of the filtrate, and the packed layer is washed with water or expanded or stirred with a stream of water and air to wash a captured suspension, and washed. The filtration is performed again in a later packed bed.

In the packed bed type filter, the pressure loss does not increase so much even if the filtration is performed at a high flow rate in the filtration step, and the quality of the filtrate is good. It is desired that objects can be reliably removed in a short time with a small amount of washing water.

However, in a conventional filter using a particulate filter medium such as sand or anthracite, the flow velocity is at most about 20 m / H, and depending on the type of the suspension, clogging occurs immediately and a pressure loss occurs. There is a disadvantage that it rises relatively early, and also in the washing, the washing is at a flow rate that does not allow the particulate filter material to flow out of the tower, so that the washing is likely to be insufficient, and the suspended matter gradually accumulates, There is also a drawback that mud balls and the like are sometimes formed, a relatively large amount of washing water is required, and a drawback is that the concentration ratio of the suspension is small.

In addition, a filter using a filter medium such as a short fiber or a fiber ball can select an arbitrary size as a filter medium to be used. Therefore, there is an advantage that an optimum filter can be selected according to a type of a suspension of a stock solution. However, since the filter medium to be used is extremely light, it is essential to provide a screen or the like that does not allow the filter medium to flow out of the tower during washing, and the structure tends to be complicated, and the screen becomes an obstacle. At the time of washing, the suspension is difficult to be discharged out of the tower, so that the washing is insufficient and the suspension gradually accumulates.

The present inventor has solved the above-mentioned drawbacks of the conventional packed bed type filter, and is capable of performing filtration at a high flow rate, without increasing the pressure loss so much, and reliably performing washing with a small amount of washing water in a short time. As a filter, a high-speed filter using a long fiber bundle was proposed.

In the proposed high-speed filter, a support is horizontally placed or filled inside the filtration tower, and a length of 400 mm to
The lower end of the 1,000 mm long fiber bundle is fixed and a filter body is formed with the upper end as a free end, and the undiluted liquid flows through the lower fiber bundle in a downward flow from the upper end to the lower end. The suspension is trapped in the gap.

By using a filter filled with such a long fiber bundle, it is possible to perform filtration at a high flow rate, furthermore, the pressure loss does not increase so much, and it is possible to reliably wash with a small amount of washing water in a short time. Although the filter filled with anthracite has various advantages that cannot be expected, there is a problem that the filtration time is somewhat unsatisfactory.

<Problems to be Solved by the Invention> The present invention solves the above-mentioned problems in the high-speed filter using the long fiber bundle previously proposed, has the advantages of the high-speed filter, and further extends the filtration time. It is an object of the present invention to provide a high-speed filter capable of causing a high-speed filtration.

<Means for Solving the Problems> A high-speed filter according to the present invention, which has been made to achieve the above object, has a support provided horizontally or packed inside a filtration tower, and a length of 1,000 m above the support. While fixing the lower end of the long fiber bundle of not less than 3,000 mm and the upper end thereof as a free end, the whole erects upright when the undiluted liquid flows in a downward flow from the upper end to the lower end of the long fiber bundle. A high-speed filter characterized by forming a filter body made of a long fiber bundle having a filling amount, and capturing a suspension contained in a stock solution in a void portion in the long fiber bundle.

Hereinafter, the present invention will be described in detail with reference to the drawings, taking water containing a suspension as an undiluted solution as an example.

FIG. 1 is a schematic cross-sectional view showing an example of one embodiment of the present invention, showing a state at an initial stage of filtration, in which a support 2 made of a perforated plate is provided horizontally inside a lower part of a filtration tower 1, The lower end of the long fiber bundle 3 having a length of 1,000 mm or more and less than 3,000 mm is fixed to the support 2, and the upper end of the long fiber bundle 3 is a free end. A raw water inflow pipe 4 is communicated with the upper part of the filtration tower 1, and a backflow water outflow pipe 5 is branched and connected to the raw water inflow pipe 4.

Further, a filtered water outflow pipe 6 communicates with the lower part of the filtration tower 1, and the filtered water outflow pipe 6 is connected to the backwash water inflow pipe 7 and the air inflow pipe 8.
Branch and communicate. 9, 10, 11, 12, and 13 indicate valves.

In addition, the filling amount of the long fiber bundle 3 is such that, even if raw water having a relatively high flow rate flows downflow, the long fiber bundle 3 is slightly bent and its height shrinks. The filling amount is set such that it does not bend horizontally by the water flow and stands entirely upright in the filtration tower 1. With such a filling amount, a filter having an extremely large porosity can be formed.

<Operation> In the case where raw water is filtered by the filter of the present invention, the following is performed.

That is, the valves 9 and 13 are opened, and the raw water containing the suspended matter flows in from the raw water inflow pipe 4 in a downward flow.

As shown in FIG. 1, the lower part of the long fiber bundle 3 is slightly bent at the initial stage due to the flow of the raw water, and its height is slightly reduced. The raw water passes in a downward flow from the upper end to the lower end of the elongate long fiber bundle 3, and thus the elongate long fiber bundle 3
The suspended matter is trapped in the gap portion of, and the filtered water flows out from the filtered water outflow pipe 6.

In addition, since the lower part of the long fiber bundle 3 is slightly bent by the downward flow of water, the lower part of the long fiber bundle is slightly more densely filled than the vertical long fiber bundle in the upper part which is not bent, and as a result, the raw water short-passes the long fiber bundle. Without this, the suspension in the raw water can be effectively captured by the long fiber bundle. When the suspension in the raw water is fine particles, a coagulant such as polyaluminum chloride, aluminum sulfate, a cationic, anionic or nonionic polymer may be added to the raw water.

By continuing the flow of water, the suspended matter or the aggregate of the suspended matter is captured in the voids of the long fiber bundle, and the pressure loss gradually increases. With the increase in the pressure loss, the degree of bending of the long fiber bundle in the lower part increases, and a phenomenon that the upright height of the long fiber bundle gradually decreases as shown in FIG. However, the phenomenon that the upper end portion of the long fiber bundle does not bend does not occur, and the end of the long fiber bundle is vertical even at the time when the water flow ends.

By continuing such water flow, the pressure loss is reduced to the default value,
Alternatively, the flow of water is stopped due to a decrease in the quality of the filtered water, and the following back washing is performed.

That is, the valves 9 and 13 are closed, the valves 10 and 12 are opened, and compressed air flows in from the air inlet pipe 8.

Due to the inflow of the compressed air, the water in the filtration tower 1 is stirred and the long fiber bundle vibrates, the voids formed between the fibers are broken, and the aggregate of the suspended matter or the aggregate of the suspended matter is formed. The suspension and the aggregates that have been broken and adhered to the long fiber bundle are peeled off.

Then, while the inflow of the compressed air continues,
The valve 12 is closed to stop the flow of the compressed air. The valve 11 is opened while the valve 10 is kept open, and the backwash water flows from the backflow water inlet pipe 7.

Since the lower end of the long fiber bundle 3 is fixed to the support 2 and the upper end thereof is a free end, the long fiber bundle 3 is moved upward by the inflowing backflow water as shown in FIG. Each of the fibers vibrates while extending like a windsink with the support 2 as a fixed portion.

Therefore, the suspension cannot stay in the long fiber bundle,
The suspension is separated from the long fiber bundle, and the backflow wastewater containing a large amount of the suspension flows out from the backwash water outflow pipe 5.

As the backwash method in the filter of the present invention, in addition to the above-described method, a method of intermittently flowing compressed air while flowing a certain amount of backwash water in an upward flow may be used. It is more effective to adopt the method in most cases.

In the filter of the present invention, since the lower end of the long fiber bundle 3 is fixed to the support 2, the long fiber bundle 3 flows out of the filtration tower 1 even if high-speed backwash water or compressed air flows. Nothing.

Therefore, it is possible to flow backwash water or compressed air at a higher flow rate than a conventional filter using a filler such as sand or anthracite, and obstacles of the screen tower are located above the filter tower. Since the filter is not provided at all, the filter of the present invention can remove the filtrate by backwashing in a short time and effectively.

Although the embodiment shown in FIGS. 1 to 3 uses a perforated plate as the support 2, steel wool can be used as the support 2.

That is, a long fiber bundle 3 is attached to a support made of steel wool.
Is fixed, and its upper end is a free end.
In addition, a screen for fixing and supporting the steel wool is provided horizontally below the steel wool. Other configurations are the first
This is the same as FIGS.

When the filler layer made of steel wool is present under the long fiber bundle 3 as described above, fine suspensions in the raw water that would pass through the long fiber bundle 3 while passing water are captured by the steel wool. Therefore, the quality of the filtered water can be further improved. The backwashing after the filtration may be performed in the same manner as described above. Instead of steel wool, a sintered metal or a porous laminate of a ceramic tower may be used as a support for the long fiber bundle 3.

Even when such a porous laminate is used, the same effect as that of steel wool is achieved. When the diameter of the filtration tower 1 is considerably large, a plurality of split plates parallel to the long fiber bundle 3 are provided in the filtration tower 1 in order to prevent the long fiber bundle 3 from being bent horizontally or diagonally in flowing water. It is good to stand vertically.

 Next, the long fiber bundle 3 used in the present invention will be described.

As described above, even if raw water having a relatively high flow rate flows downflow, the lower part of the long fiber bundle is slightly bent at the initial stage, and the height thereof is slightly reduced. In addition, the bent portion of the lower part increases due to the continuation of water flow, and the upright height of the long fiber bundle 3 gradually decreases,
Synthetic of acrylic fiber, polysell fiber, polyamide fiber, etc., which requires a stiffness such that the long fiber bundle does not bend horizontally and stands upright as a whole even in water in the filtration tower 1 and a filling amount. Fibers or natural fibers such as cotton and wool can be used.

Note that it is preferable to use an aggregate of non-twisted single fibers having a thickness of 50 μm or less, usually about 35 μm, which is a material of these synthetic resin or natural fiber fibers.

However, an aggregate of twisted yarns may be used as long as it is a long fiber bundle that does not bend horizontally in flowing water and stands entirely upright in the filtration tower 1.

The larger the aggregate density of the long fiber bundle used in the present invention, the more the fine suspension can be removed and the quality of the filtered water can be improved, but conversely, the pressure loss increases.

Also, as the aggregate density decreases, the quality of the filtered water decreases, but conversely, the pressure loss decreases.

Therefore, it is advisable to select and use the most suitable aggregate density long fiber bundle according to the quality or quality of the raw water suspension. For example, when a long fiber bundle consisting of an aggregate of non-twisted single fibers having a length of 1,000 mm to 3,000 mm is used, the filtration cross-sectional area is 1 m ^2.
The packing density should be such that 50 to 200 kg (dry weight) per fiber bundle is obtained.

In the present invention, the length of the long fiber bundle is 1,000 mm or more, 3,000
The reason for limiting to less than mm is as follows.

That is, if the length of the long fiber bundle is 1,000 mm or less, the filtration time becomes short, which is not satisfactory as an industrial device. Although the filtration time is extended as the length of the long fiber bundle is increased, the equilibrium state is approached when the length exceeds 3,000 mm, and the effect of increasing the length of the long fiber bundle is weakened. It is not preferable because it only increases the production cost of the container.
In other words, it can be said that the effect is remarkable in the filtration time when the length of the long fiber bundle is 1,000 mm to 3,000 mm.

Regarding the quality of filtered water, the length of long fiber bundle is 1,000m
Although it is slightly worse below m, there is no significant difference between 1,000mm and 3,000mm.

<Effect> As described above, the filter of the present invention is used as a filter,
Since a long fiber bundle that stands upright in the filtration tower during filtration is used, the pressure loss in flowing water is small, and therefore, filtration can be performed at a high flow rate. It is suitable for filtering a stock solution which is difficult to filter with a filter filled with conventional sand such as white water or anthracite.

In addition, since a filter body in which long fiber bundles stand upright in the direction perpendicular to the diameter of the filtration tower as a whole is used, when a stock solution passes between a large number of fibers, suspended matter is effectively removed, and filtration is performed. The water quality of the liquid is also good.

Further, in the filter of the present invention, since the lower end of the long fiber bundle is fixed by the support, even if high-speed backwash water or compressed air is passed, the long fiber bundle does not separate from the filtration tower, Therefore, the backwashing process can be performed in a short time with high-speed backwashing water or compressed air, and the backwashing time can be significantly reduced as compared with the conventional filter, and the backwashing process can be more reliably performed. The suspension can be discharged outside the tower
There is no accumulation of suspended matter unlike the conventional filter, and the amount of backwash water is extremely small.

In addition, since the filtration flow rate can be significantly increased as compared with the conventional filter, it goes without saying that the cross-sectional area of the filtration tower can be reduced, and the installation cost and installation area can be significantly reduced.

Examples will be shown below to further clarify the effects of the present invention.

Example A perforated plate was attached to the lower part of a stainless steel filtration tower with a diameter of 650 mm and a height of 4,000 mm (straight section), 35 μm in thickness and length
A filter as shown in FIGS. 1 to 3 in which the lower end of a long fiber bundle made of an aggregate of seven types of acrylic non-twisted single fibers of 800 mm to 3,500 mm is fixed and the upper end is a free end. From the top of the filter, the suspended solids (SS) concentration 30mg /
Papermaking wastewater containing water was passed at a downward streamline speed of 50 m / H.

The end point of water flow is 0.5 kg / cm ² as the differential pressure (initial pressure difference 0.1 kg / cm ² ), and after completion of water flow, the rising linear flow rate is 1,000 Nm ³ / m ²
Backwash with air (1,000Nm ³ / m ² ) and 100m / H backwash water for 3 minutes, and then backwash with only 100m / H backwash water for 1 minute. The pressure returned to the initial pressure difference, and the suspended matter trapped in the long fiber bundle could be completely removed, and the state before the filtration could be restored.

Table 1 shows the filtration time and the average turbidity of the treated water with respect to the length of each long fiber bundle when such a filtration experiment was carried out for 6 months.

[Brief description of the drawings]

1 to 3 show a filter according to an embodiment of the present invention. FIG. 1 is a schematic cross-sectional view showing an initial stage of filtration, and FIG. 2 shows a state of later stage of filtration. FIG. 3 is a schematic cross-sectional view, and FIG. 3 is a schematic cross-sectional view showing a state of back washing. DESCRIPTION OF SYMBOLS 1 ... Filtration tower, 2 ... Support 3 ... Long fiber bundle, 4 ... Raw water inflow pipe 5 ... Backwash water outflow pipe, 6 ... Filtered water outflow pipe 7 ... Backwash water inflow pipe, 8 ... … Air inlet pipes 9, 10, 11, 12, 13 …… Valves

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B01D 24/12 B01D 24/22 B01D 35/10

Claims (1)

(57) [Claims] (1) A support is provided horizontally or filled inside a filtration tower, and the lower end of a long fiber bundle having a length of 1,000 mm or more and less than 3,000 mm is fixed on the upper part of the support, and the upper end is a free end. As a whole, when a stock solution is passed in a downward flow from the upper end to the lower end of the long fiber bundle, a filter body composed of a long fiber bundle having a filling amount that stands upright is formed, and a void portion in the long fiber bundle is formed. A high-speed filter characterized by capturing a suspension contained in a stock solution by a high-pressure filter.