JPS6084122A - Method and apparatus for washing electromagnetic filter - Google Patents

Abstract

PURPOSE:To prevent the deterioration in filtering capacity caused by long-term continuous use by further increasing the washing effect of an electromagnetic filter, by combining the regular washing process of filter media with the backwashing process thereof. CONSTITUTION:Only a raw water introducing valve 7, a filtrate discharge valve 10 and an opening and closing valve 16 are opened and raw water is supplied to an electromagnetic filter 1 by a pump 6 and magnetic particles in raw water are collected by magnetized filter media. A definite amount of the filtrate is stored in a storage tank 9 and the excessive part is discharged from the valve 10. In washing the media 3, the magnetization thereof is released and only an air valve 3, the valve 16 and a washing water discharge valve 8 are opened while high pressure air of an air tank 11 is introduced into the tank 9 and sends the washing water in the tank 9 to the filter 1 from a secondary side 5 under pressure to perform backwashing. Herein, only the valve 13, a discharge valve 15 and a regular washing water supply valve 18 are further opened and the washing water in the tank 19 is passed through an arranged pipe 17 and guided to the filter 1 and a discharge pipe 14 from a primary side 4 to perform regular washing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cleaning an electromagnetic filter that captures magnetic particles in Kik by magnetic force, and a waterfall device.

As is already known, electromagnetic filters are used to separate and recover magnetic particles from steel wastewater such as hot rolling wastewater from steel materials, converter dust collection wastewater, vacuum degassing equipment cooling wastewater, or various industrial dead waters. A multilayer mesh filter media made of magnetic thin wires is magnetized by placing it in the magnetic field of an excitation coil, and raw water containing magnetic particles is passed through the filter media. Grooves are formed in the filter media so that magnetic particles are captured by magnetic force. The magnetic filter is great! As time passes, the captured magnetic particles accumulate on the filter media and the capture effect gradually decreases, so generally when the processing time or filter pressure loss reaches a certain value, the current in the exciting coil is cut off and the filter media is removed. A method has been adopted in which, at the same time as demagnetization is released, filtered water stored in a tank in the filtered water passage is made to flow back into the electromagnetic filter to wash the filter media (hereinafter referred to as a backwashing process). 1st
The figure shows a piping system diagram of a conventional electromagnetic filter. In the figure, 1 is the electromagnetic filter, 2 is its excitation coil, and 3 is the excitation coil 2.
multilayer mesh filter media placed in a magnetic field of 4
is the primary side of the electromagnetic filter 1, 5 is the secondary side, 6 is a pump for supplying raw water, 7 is a raw water introduction valve communicating with the primary side 4,
8 is a washing water discharge valve that also communicates with the primary side 4; 9
are a filtrate water storage tank and a 10-piece filtrate discharge valve provided on the secondary side 5 to store filtrate water. 1] is an air tank, and 1 is a compressor that maintains the inside of the air tank at a predetermined air pressure.Air piping is connected from the air tank n to the filtered water storage tank 9 via an air valve.

However, in this lever device, raw water is driven by a pump 6 to flow through a magnetized filter media 3, magnetic particles in the raw water are captured, and a certain amount of the filtrated water is stored in a storage tank 9, and when cleaning the filter media, Filter media 3
The air valve is demagnetized, the cleaning water discharge valve 8 is opened, the air in the air tank H is forced into the storage tank 9, and the stored filtered water flows back from the secondary side of the electromagnetic filter 1 to the primary side 4 for cleaning. However, even with such backwashing, the cleaning effect is still insufficient, and the particles remain attached to the filter media, and when used for a long period of time, the amount of particles remaining attached gradually increases. .

The present invention aims to provide a cleaning method and an apparatus therefor that further enhances the cleaning effect of an electromagnetic filter and leaves as few particles as possible. The filter media is washed by both a backwashing process in which the water flows in the opposite direction to the raw water, and a forward flow process in which the water flows in the same direction as the raw water. A pipe and a filtered water storage tank are provided in that order, and the filtered water storage tank and the primary side of the electromagnetic filter are connected by a downstream water supply pipe.

An embodiment of the present invention will be described below with reference to FIG. Second
Reference numerals in the drawings that are the same as those in Fig. 1 indicate the same parts or parts, and their explanations will be omitted. In this device, a washing water discharge pipe 14 is connected to the secondary side 5 of the electromagnetic filter 1, and the discharge pipe 14 is provided with a discharge valve. 16 is an on-off valve provided between the secondary side 5 and the storage tank 9. 17 is a downstream water supply pipe connecting the storage tank 9 and the primary side of the electromagnetic filter 1, and a helmet is a downstream water supply valve provided in the pipe.

In this grooved device, when the raw water inlet valve 7, permeate water discharge valve 10, and opening/closing valve 16 are opened, the other valves are closed and the pump 6 is driven to supply raw water to the electromagnetic filter 1. Magnetic particles in the raw water are captured and filtered by the magnetized filter media 3. A certain amount of the filtrated water is stored in the storage tank 9, and the remainder is removed by the filtrated water discharge valve 1.
Discharge from 0. Now, when cleaning the filter media 3, the power to the excitation coil 2 is stopped, the filter media 3 is demagnetized, and the air valve and opening/closing valve t are removed.
o, a Open the water-saving discharge valve 8 and close the other valves to introduce high-pressure air from the air tank H into the storage tank 9, and from the secondary side 5 containing cleansing water stored in the tank 9 to the electromagnetic filter 1. The water is forced to pass through the 4-30 gap of the filter in the opposite direction to the raw water.

Such a backwashing process has been used in the past, but in the present invention, following this backwashing process, a forward flow process is adopted in which the washing water is flowed in the same direction as the raw water. That is, the air valve ratio, the discharge valve, the downstream water supply valve is opened, the other valves are closed, and the cleaning water in the storage tank 9 is guided to the primary side 4 of the electromagnetic filter 1 through the downstream water supply piping 17, and the filter is The cleaning water is passed through the gap in the media 3 in the same direction as the raw water and discharged into the cleaning water discharge pipe 14.

Next, in order to confirm the effects of the present invention, we will examine two cases: one in which the electromagnetic filter for filtering iron W4 hot rolling wastewater is simply backwashed as in the past, and the other in which the electromagnetic filter that filters iron W4 hot rolling wastewater is compliant with the backwashing method according to the present invention. We tested the difference in filtration performance (removal rate) when backwashing was performed once more, and the results will be disclosed.

However, the specifications of the electromagnetic filter, washing device, and raw water tested were as follows: Filter media diameter: 0.2 m Magnetic field strength + 3 kilogauss Washing water storage mH/201 (However, in the present invention, this is divided into three times and used each time at 11.01 mH) Washing Interval: Every 30 minutes of filtration, the iron particle concentration of the raw water +/j□PPm The oil concentration of the raw water, / 7 ppm, used immediately after the start of the test and continuously for several months (approximately 70 times of washing)
The analysis results of the treated water after 00 times) are shown in the following table.

In this way, immediately after the start of the test, no difference was observed between the present invention and the conventional method, but after continuous use for several months, it was found that the rate of decrease in the removal rate of the present invention was much lower than that of the conventional method. It was recognized that the performance of the electromagnetic filter could be maintained for a long period of time. In addition, the amount of iron particles remaining on the filter media after being used for t evenings reached 13g with the conventional method, but with the cleaning method of the present invention, the amount of remaining adhesion was only r,
, 2g.

The above data is based on dividing the washing water of /201 into 3 times.
This is a case in which 1-01 is used in the order of backwashing - forward flow -> backwashing, but this can also be done by simply performing backwashing -> forward flow, or washing in order of washing -> backwashing, or even more times. The backwashing and compliance methods may be repeated, and furthermore, the conventional method of mixing air into the washing water to diffuse air bubbles may be used in combination to increase the washing effect. Of course.

As explained above, the present invention is advantageous in that the cleaning effect is further enhanced and the filtration performance does not deteriorate even when used continuously for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a piping system diagram of a conventional electromagnetic filter, and FIG. 2 is a piping system diagram of an electromagnetic filter according to the present invention. 1... Electromagnetic filter, 3... Filter media 4...-Next side, 5... Secondary side, 9... Filtered water storage tank. 14...Washing water discharge pipe, 17...
- Legally compliant water supply piping. Patent applicant: Daido Steel Co., Ltd.

Claims (1)

[Claims] 1. In an electromagnetic filter that traps particles in the raw water by flowing raw water through a filter media magnetized by an excitation coil, the filter media is demagnetized by the excitation coil, and the cleaning water is directed in the opposite direction to the raw water. 1. A method for cleaning an electromagnetic filter, characterized in that the filter media is washed by a backwashing process in which the filter media is flowed in the same direction as raw water, and a compliance process in which the filter media is flown in the same direction as raw water. 2. In an electromagnetic filter in which raw water is magnetized by an excitation coil and is passed through a Taffilter media to trap particles in the raw water, a cleaning discharge pipe and a filtered water storage tank are provided in that order on the secondary side of the electromagnetic filter. An electromagnetic filter cleaning device characterized in that the filtered water storage tank and the primary side of the electromagnetic filter are connected by a legal water supply piping.