JP2001276514A - Method and device for back washing of metal powder- removing filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for back washing, high in the recycling efficiency of back wash liquid. SOLUTION: After back-washing an iron powder-removing filter and recovering iron powder together with the back wash liquid 7 into a back wash liquid tank 8, the iron powder in the back wash tank is settled by leaving them at rest for a predetermined time. Subsequently, a discharge pipe 9 connected to the bottom of the back wash liquid tank 8 is opened to discharge the back wash liquid 7 and the iron powder from the tank 8. At this time, the concentration of the iron powder in the back wash liquid 7 flowing through the discharge pipe 9 is estimated by a turbidity meter 26, and when it is judged that the concentration of the iron powder becomes a value of not more than a prescribed value, the discharge pipe 9 is closed. Thereby the amount of the back wash liquid 7 to be disposed is remarkably reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal powder filter in which a backwashing liquid in a backwashing liquid tank is circulated backward when a filter for removing a metal powder such as an electromagnetic filter is clogged and the filter performance deteriorates. The present invention relates to a backwashing method and a backwashing apparatus for a circulating metal powder filter that removes metal powder trapped in a filter.

[0002]

2. Description of the Related Art For example, since iron powder adheres to a steel strip after cold rolling, as shown in FIG. 1, the steel strip 1 after the rolling is washed with a cleaning liquid 2 and then annealed. Sent to the process. The cleaning with the cleaning liquid 2 is performed using the steel strip 1
Is immersed in the cleaning tank 3 containing the cleaning liquid 2 or by spraying the cleaning liquid 2 onto the surface of the steel strip 1. FIG. 1 illustrates only the case of immersion.

The cleaning liquid 2 in the cleaning tank 3
Is circulated by being sent into the process liquid tank 4 and at the same time the clean liquid 2 in the process liquid tank 4 is sent to the cleaning tank 3. The cleaning liquid 2 in the process liquid tank 4 continuously or intermittently circulates in the iron powder removing filter 5 (for example, an electromagnetic filter) in the filtration direction A, and becomes the cleaning liquid 2 in the process liquid tank 4. It captures and removes mixed iron powder. Code 6
Is a filtration pump for pumping. The cleaning liquid 2 is generally an alkaline liquid containing no oil.

When the iron powder removing filter 5 is clogged, the circulation for filtration from the process liquid tank 4 is temporarily stopped, and the iron powder removing filter 5 is backwashed. Backwashing refers to washing a filter by flowing a washing liquid in a direction opposite to a filtration direction. In FIG. 1, backwashing moves the inside of an iron powder removal filter 5 from an outlet side to an inlet side, that is, the filtration. This is performed by pumping the backwash liquid 7 made of hot water in the direction B opposite to the direction A and discarding the backwash liquid 7 containing iron powder discharged from the inlet side of the filter 5.

In the backwashing apparatus shown in FIG. 1, in order to use the backwashing liquid 7 economically, the backwashing liquid 7 contained in the backwashing liquid tank 8 is circulated to perform the backwashing. Upon completion, open the discharge pipe 9 provided at the bottom of the backwash liquid tank 8,
The backwash liquid 7 and the iron powder in the backwash liquid tank 8 are all discharged. When the discharge is completed, the backwashing liquid supply valve 11 is opened, and the backwashing liquid tank 8 is filled with the backwashing liquid 7 to a predetermined level. Reference numeral 10 represents a level meter.

[0006]

However, in the above-mentioned conventional backwashing method, even in the above-mentioned circulation system, the backwashing liquid 7 stored in the backwashing liquid tank 8 is discarded every time one backwashing is performed. Therefore, there is a problem that economic efficiency is not good.
Here, the backwash liquid 7 stored in the backwash liquid tank 8 is used.
Is 500 liters, for example, and backwashing is performed many times a day.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and provides a backwashing method and apparatus having high recycle efficiency of a backwashing solution.

[0008]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, the backwashing liquid in the backwashing liquid tank is supplied to the metal powder removing filter in the direction of filtration. By circulating in the reverse direction, the metal powder captured by the metal powder removal filter is collected together with the backwash liquid in the backwash liquid tank, and then a discharge pipe connected to the bottom of the backwash liquid tank is provided. In the backwashing method of the metal powder removing filter that opens and discharges the backwashing liquid and the metal powder from the backwashing liquid tank, the metal powder in the backwashing liquid tank is allowed to stand for a predetermined time after the collection of the metal powder, and then the above-described method is performed. The discharge pipe is opened, and when it is determined that the concentration of metal powder in the backwash liquid flowing through the discharge pipe has become equal to or lower than a predetermined concentration, the discharge pipe is closed.

Here, the predetermined concentration may be set, for example, to a steady state or a slightly higher value than the concentration of the metal powder in the backwash liquid being discharged. Since the metal powder is discharged after being precipitated, it is considered that the concentration rapidly changes before and after the precipitated metal powder is discharged. In addition,
The above-mentioned steady state means a state in which the precipitated metal powder is discharged and the metal powder concentration of the backwash liquid being discharged becomes substantially constant, as described later.

Next, a second aspect of the present invention is characterized in that, in contrast to the configuration of the first aspect, the metal powder concentration is estimated from the transparency of the backwash liquid flowing through the discharge pipe. is there. Next, the invention according to claim 3 is a circuit for circulating the backwash liquid in the backwash liquid tank in the metal powder removal filter in a direction opposite to the filtration direction and returning the backwash liquid to the backwash liquid tank;
Backwashing of a metal powder removing filter including a pump for pumping backwashing liquid along a circulation path, a discharge pipe extending downwardly communicating with the bottom of the backwashing liquid tank, and an on-off valve for opening and closing the discharge pipe. In the apparatus, based on the estimation by the concentration estimating means for estimating the metal powder concentration in the backwash liquid falling in the discharge pipe, the concentration of the metal powder in the backwash liquid flowing in the discharge pipe is equal to or less than a predetermined concentration. And a drop stop means for supplying a closing command to the on-off valve.

Next, the invention according to claim 4 is different from the structure according to claim 3 in that the concentration estimating means estimates the concentration of the metal powder by the transparency of the backwash liquid flowing in the discharge pipe. It is a feature.

[0012]

Next, embodiments of the present invention will be described with reference to the drawings. It should be noted that the same devices and the like as those in the above-described conventional example are denoted by the same reference numerals and described. Further, in the present embodiment, the backwashing of the iron powder removing filter 5 will be described as an example as in the above-described conventional example. As shown in FIG. 2, the backwashing device of the present embodiment includes a forward pipe 20 connecting the backwashing liquid tank 8 and an outlet side of the filter 5, an inlet side of the filter 5, and an inlet side of the backwashing liquid tank 8. Return pipe 21 connecting to
Thus, a circulation path is formed, and a pump 22 for backwashing is inserted into the outward pipe 20.

The backwashing liquid tank 8 contains a backwashing liquid 7 made of hot water and filled through a valve 11 for supplying a backwashing liquid. The adjustment of the supply amount of the backwash liquid 7 through the valve 11 is determined based on a level meter (not shown) provided in the backwash liquid tank 8. The bottom of the backwash liquid tank 8 is formed in a cone shape so that the backwash liquid 7 and the collected iron powder can be easily discharged. A discharge pipe 9 is connected to the center of the bottom, and the discharge pipe 9 extends downward.

An open / close valve 23 is interposed in the discharge pipe 9. A part of the discharge pipe 9 above the on-off valve 23 is provided with a transparent window 24 so that the inside can be observed. In this embodiment, the window portion 24 is provided by forming a part of the discharge pipe 9 with the transparent pipe 25. In the window 24, a turbidity meter 26 is installed, which measures the transparency of the fluid flowing through the discharge pipe 9, and sends the measurement signal to a controller 27 which constitutes a drop stop means.
It can be supplied to

The controller 27 estimates the iron powder concentration in the backwash liquid 7 flowing through the discharge pipe 9 based on the measurement signal from the turbidity meter 26, and when it is determined that the iron powder concentration has reached a predetermined concentration, A closing signal is supplied to the on-off valve 23. here,
As the predetermined concentration, the concentration ratio to the average iron powder concentration in the backwash liquid 7 in the backwash liquid tank 8 may be set to 10%, preferably 8%. This was determined for the following reasons.

When the average iron concentration in the backwashing liquid 7 in the backwashing liquid tank 8 is 30.4 g / L, the concentration ratio to the above average iron content for each 10 L unit discharged from the discharge pipe 9 is actually obtained. As a result, the result shown in FIG. 3 was obtained. As can be seen from FIG. 3, when the concentration ratio becomes 8.0% or less, almost the subsequent concentration ratio becomes a steady state, and it can be seen that all of the deposited iron is discharged. Preferably, it is slightly higher than 10%. When converted to an actual iron powder concentration instead of a concentration ratio, it is 2.43 g / L, preferably 3.0.
The predetermined concentration may be 4 g / L.

Further, the cleaning liquid 2 passing through the iron removing filter 5 in the filtration direction A is an alkaline liquid containing almost no oil and the like, and the backwashing liquid 7 is a highly transparent warm water, so Since the turbidity (transparency) of the backwash liquid 7 flowing through the tube is proportional to the concentration of iron mixed in the backwash liquid 7, the iron concentration can be accurately estimated from the turbidity.

In the backwashing apparatus having the above structure, the backwashing pump 7 is driven to circulate the backwashing liquid 7 in the backwashing liquid tank 8 between the iron removing filter 5 and the backwashing liquid tank 8. Then, the backwashing of the filter 5 is performed, so that the iron powder is collected in the backwashing liquid tank 8. After the iron powder is collected in the backwash liquid tank 8, the backwash liquid 7 in the backwash liquid tank 8 is allowed to stand for a predetermined time, for example, 10 minutes, until the iron powder is sufficiently settled. As a result, the iron concentration of the backwashing liquid 7 located in the lower part in the backwashing liquid tank 8 is greatly increased.

Next, when the discharge pipe 9 is opened, the lower back washing liquid 7 is removed.
In other words, the iron is discharged from the backwash liquid 7 having a high iron concentration, but when the controller 27 determines that the concentration is lower than the predetermined concentration, a closing command is supplied to the on-off valve 23 to close the pipe, so that the iron concentration in the discharge pipe 9 is reduced. Only the strong backwash liquid 7 is discharged, and the remaining backwash liquid 7 can be used. In this way, only the backwash solution 7 having a high iron content is discharged, and the remaining backwash solution 7 is reused, so that the cost for the backwash solution 7 can be suppressed.

By the way, as can be seen from FIG. 3, the amount of the discarded backwashing liquid 7 including iron powder is not more than 20 liters.
When it reaches 480 liters or more, most of the backwash liquid 7 in the backwash liquid tank 8 is reused. In addition, the fact that the amount of discharge is significantly small means that the time required for discharge is greatly reduced, and the time for replenishing the backwash liquid 7 via the backwash liquid supply valve 11 is also significantly reduced. As a result, there is also an effect that the backwash interval can be shortened even if the circulation type backwash is applied.

Here, in this embodiment, the iron concentration in the backwash liquid 7 flowing through the discharge pipe 9 is estimated based on the transparency (turbidity) of the backwash liquid 7 flowing through the discharge pipe 9. Not limited. For example, the average iron concentration in the backwash liquid tank 8 immediately after the backwash is completed is measured, and a discharge flow rate or a discharge time at which the predetermined concentration is obtained is estimated from the measured average iron concentration. The discharge may be stopped at that point. In this case, the iron concentration in the backwash liquid 7 flowing through the discharge pipe 9 is estimated based on the amount of the discharge flow rate or the elapsed time of the discharge time based on the average iron concentration.

Alternatively, the relationship between the backwash solution 7 to be discharged and the iron concentration is determined in advance as shown in FIG. 3 in accordance with the type of the cleaning solution 2, and based on the relationship,
The iron concentration in the currently washed backwash liquid 7 may be estimated based on the discharge flow rate and the discharge time. Further, in the above embodiment, iron powder is exemplified as the metal powder, but the present invention is also applicable to backwashing of the filter 5 for removing other metal powder such as aluminum powder.

[0023]

As described above, in the backwashing method and the backwashing apparatus according to the present invention, the amount of waste of the backwashing liquid used in the backwashing is greatly reduced. Is greatly suppressed, and the economical efficiency of backwashing is improved.
In addition, even in the case of the circulation type backwash, there is an effect that the backwash interval is shortened.

At this time, adopting claim 2 or claim 4 has the effect that the iron concentration can be reliably estimated in real time.

[Brief description of the drawings]

FIG. 1 is a configuration diagram for explaining the removal of iron powder by a filter and the configuration of a conventional backwashing device.

FIG. 2 is a diagram illustrating a backwashing device according to an embodiment based on the present invention.

FIG. 3 is a diagram showing a change in an iron concentration ratio in a backwash liquid discharged from a discharge pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel strip 2 Cleaning liquid 3 Cleaning tank 4 Process liquid tank 5 Iron powder removal filter 6 Filtration pump 7 Backwash water 8 Backwash water tank 9 Discharge pipe 10 Level meter 11 Valve 20 Outgoing path 21 Return path 22 Backwash pump 23 On-off valve 24 Window 25 Transparent piping 26 Turbidimeter 27 Controller A Filtration direction B Backwash direction

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koji Kawashima 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba F-term inside the Chiba Works, Chiba Works (reference) 3B201 AB53 BB03 BB75 BB87 BB94 CB01 CD41 4K053 PA02 PA12 QA01 QA04 RA21 SA06 YA06 YA07

Claims (4)

[Claims] 1. A backwash liquid in a backwash liquid tank is circulated through a metal powder removal filter in a direction opposite to a filtration direction,
After collecting the metal powder captured by the metal powder removal filter together with the backwash liquid in the backwash liquid tank, open a discharge pipe connected to the bottom of the backwash liquid tank to reverse the backwash liquid and the metal powder. In the backwashing method of the metal powder removal filter discharged from the washing liquid tank, the metal pipe in the backwashing liquid tank is allowed to stand for a predetermined time after the collection of the metal powder, and after the metal powder in the backwashing liquid tank is settled, the discharge pipe is opened and flows through the discharge pipe. A method for backwashing a metal powder removal filter, comprising closing the discharge pipe when it is determined that the concentration of metal powder in the backwash liquid has fallen below a predetermined concentration. 2. The method for backwashing a metal powder removal filter according to claim 1, wherein the metal powder concentration is estimated from the transparency of the backwash liquid flowing through the discharge pipe. 3. A circulation path for circulating the backwashing liquid in the backwashing liquid tank in a direction opposite to the filtration direction in the metal powder removing filter and returning the backwashing liquid to the backwashing liquid tank, and a backwashing liquid along the circulation path. A back-flushing device for a metal powder removal filter, comprising: a pump for pumping water; a discharge pipe extending downwardly communicating with the bottom of the back-wash liquid tank; and an on-off valve for opening and closing the discharge pipe. The concentration estimating means for estimating the metal powder concentration in the backwash liquid to be performed, and based on the estimation by the concentration estimating means, closes the on-off valve when the metal powder concentration in the backwash liquid flowing through the discharge pipe becomes equal to or less than a predetermined concentration. A backwashing device for a metal powder removal filter, comprising: a drop stop means for supplying a command. 4. The backwashing apparatus for a metal powder removing filter according to claim 3, wherein said concentration estimating means estimates the concentration of the metal powder based on the transparency of the backwashing liquid flowing in the discharge pipe.