JPH0234645B2 - DENJIFUIRUTANOSENJOHOHOOYOBISENJOSOCHI - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method and apparatus for cleaning an electromagnetic filter, and more particularly, a method and a method for extremely effectively cleaning an electromagnetic filter by using a suitable combination of a surfactant-containing solution and pressurized air. Relating to equipment used directly for. Urban sewage, industrial wastewater, and manufacturing process wastewater such as rolling wastewater and continuous casting wastewater from the steel industry (hereinafter simply referred to as raw water) contain suspended or suspended substances (hereinafter simply referred to as impurities). However, if these are released into the environment as they are, they become a source of serious pollution, so they must be treated by some means, and in recent years, electromagnetic filters have been used as such treatment means. This electromagnetic filter is used to magnetically filter and separate raw water after subjecting it to appropriate pretreatment if necessary. By the way, when raw water containing impurities is treated with an electromagnetic filter, the impurities separate and adhere to the filter media, so this is cleaned at regular intervals, for example, and the separated and adhering impurities are removed from the outside of the electromagnetic filter. need to be discharged to Conventionally, such cleaning is accomplished by backwashing the electromagnetic filter with water and pressurized air. However, in practice, if an electromagnetic filter is repeatedly used only by conventional backwashing, impurities that cannot be cleaned by conventional backwashing will gradually accumulate in the filter media, which will have a serious negative effect on the processing efficiency of the electromagnetic filter. Become. In such a case, there is a need for a method and apparatus that can effectively clean and regenerate the electromagnetic filter instead of or in addition to conventional backwashing. The present invention provides an improved cleaning method and cleaning apparatus for electromagnetic filters that meet the above requirements. Hereinafter, the configuration of the present invention will be explained in detail based on the drawings while comparing it with a conventional case. FIG. 1 is a system diagram illustrating a conventional electromagnetic filter processing procedure, and FIG. 2 is a detailed diagram of the electromagnetic filter portion, which is filled with magnetic thin wire as a filter medium 31a. After the raw water has been subjected to appropriate pretreatment if necessary, such as co-coagulation treatment with a coagulant and magnetite, it is supplied to an electromagnetic filter 31 by a pump 11 via a valve 21.
Impurities are magnetically filtered and separated using valve 2.
2. Treated water is obtained by sequentially passing through the backwash water pressurized tank 41 and valve 23. After the raw water is continuously treated for a predetermined period of time by the filtration system consisting of the above-mentioned units with the electromagnetic filter 31 as the core, the power to the electromagnetic filter 31 is cut off, appropriate valve operations are performed, and the electromagnetic filter 31 is filtered by the next backwashing system. Wash and discharge impurities that have separated and adhered to the surface. That is,
Pressurized air from a compressor (not shown) passes through the valve 24 and pushes out some of the treated water stored in the backwash water pressurizing tank 41 via the valve 22, while the pressurized air is pushed out via the valve 25. The pressurized air and treated water are injected into the electromagnetic filter 31 in a mixed state. Then, impurities separated and attached to the filter media 31a in the electromagnetic filter 31 are washed away by a certain kind of impact flow at this time, and the backwash water is thus discharged. After backwashing, the raw water is treated by the filtration system again, and the filtration system and backwashing system are repeated in the same manner. However, as described above, when an electromagnetic filter is repeatedly used by only conventional backwashing, impurities that are not cleaned by such backwashing gradually accumulate in the filter media 31a in the electromagnetic filter, and the processing of the electromagnetic filter becomes difficult. This will have a significant negative impact on efficiency. The present inventors investigated the composition of impurities that are not cleaned by conventional backwashing and accumulates in the filter media 31a in the electromagnetic filter, and are working diligently to thoroughly clean and discharge the impurities. As a result of research, the reason why impurities are difficult to peel off from the filter media 31a in the electromagnetic filter is due to oils and fats, which strongly adhere to the filter media 31a as if they contain other impurities. Therefore, they discovered that it is sufficient to take in the fats and oils with something that has a strong affinity to negate their mediating ability, and at the same time apply impact to peel them off, leading to the completion of the present invention. That is, the present invention relates to a method for cleaning an electromagnetic filter, in which an electromagnetic filter, on which various impurities have separated and adhered due to use, is cleaned by introducing a suitable combination of a surfactant-containing solution and pressurized air. This relates to a cleaning device that is used directly in the cleaning method. In the present invention, the surfactant is usually used in the form of an aqueous solution, but its type, concentration, liquid temperature, etc. are selected as appropriate depending on the nature and amount of the impurity to be cleaned, as well as the desired degree of cleaning. . As the concentration and liquid temperature increase, the cleaning effect generally improves, although it depends on other conditions. However, in most cases, it is standard to use an aqueous solution of a mixture of anionic and nonionic surfactants dissolved at a concentration of 0.5 to 10% at a temperature of 20 to 80°C.
On the other hand, the pressurized air used in combination with such a surfactant-containing solution may be the same as that used for conventional backwashing. In completing the present invention, the present inventors conducted various tests and found that even when only a surfactant-containing solution was used, a reasonable cleaning effect was obtained. The specific effect will be mentioned in a comparative example described later, but this level of cleaning effect was still insufficient and did not lead to the regeneration of the electromagnetic filter.
In order to sufficiently wash and discharge impurities that have strongly adhered to the filter media through the mediation of oils and fats, the mediating ability of the oils and fats can be counteracted by incorporating the oils and fats with a surfactant that has a strong affinity for the oils and fats. At the same time, it is important to peel impurities from the filter media using the impact force of pressurized air. In this case, the surfactant-containing solution and pressurized air may be used in appropriate combination. In the system diagram of FIG. 1, for example, a surfactant-containing solution is filled into the electromagnetic filter 31 from the direction of the raw water,
After being allowed to stand still for a certain period of time, pressurized air may be fed into the electromagnetic filter 31 via the valve 25 and discharged from the valve 26. Alternatively, for example, a surfactant may be added to the backwash water pressurized tank 41. Inject the containing solution,
The same operation as the conventional backwashing described above may be performed. In short, pressurized air should be introduced when the filter media is wet with the surfactant, and for this purpose, the surfactant-containing solution and the pressurized air should be fed simultaneously, separately, or even continuously. The air may be fed in at once or intermittently, and as a result, the function of pressurized air can be exerted in addition to the function of a surfactant. In fact, the present invention can be applied in place of conventional backwashing in such cases, since impurities may adhere to the electromagnetic filter even after one use. Usually applied in addition to conventional backwashing. That is, daily cleaning is performed by conventional backwashing, and the present invention is applied after conventional backwashing, for example, once every three months. FIG. 3 is a schematic diagram corresponding to FIG. 1, illustrating a cleaning device according to the present invention. As in the case of FIG. 1, an electric heater 51 is connected to the electromagnetic filter 32 to which the filtration system and the backwash system are connected.
A cleaning system including a cleaning liquid tank 61 attached thereto, a liquid feeding pump 12 connected to the cleaning liquid tank 61, and control valves 27 and 28 connected thereto includes the electromagnetic filter 32 and a circulation path. connected to form. The heater may be one that heats the surfactant-containing solution introduced into the cleaning liquid tank 61 to a desired temperature, and may be one that uses heated steam, for example, in addition to the one shown in the drawing. Further, in the drawing, the cleaning liquid tank 61 is open at the top, but it may be a closed tank, for example. As mentioned above, there are many specific embodiments for cleaning electromagnetic filters with a combination of a surfactant-containing solution and pressurized air. However, in practice, conventional backwashing is often performed, and in order to utilize the existing filtration system and backwashing system as is, it is preferable to be able to clean the electromagnetic filter in a completely separate system. The surfactant-containing solution used can be heated in relation to the cleaning effect.
Furthermore, a cleaning device that can repeatedly use the surfactant-containing solution is most preferable. The embodiment illustrated in the drawings is a representative example that satisfies these desired conditions. As explained in FIG. 1, when an electromagnetic filter is repeatedly used only by conventional backwashing, impurities accumulate in the filter media. Therefore, when conventional backwashing is performed, appropriate valve operations are performed to clean the electromagnetic filter using a combination of a surfactant-containing solution and pressurized air. In FIG. 3, for example, an aqueous solution of a surfactant is prepared in advance in a cleaning liquid tank 61 by appropriately selecting its type, concentration, etc., and heated to a desired temperature by an electric heater 51. Next, the heated surfactant-containing solution is passed through the electromagnetic filter 32 by the pump 12 through the valve 27.
and the cleaning liquid tank 61 via the valve 28.
Send it back to Then, while the surfactant-containing solution is being circulated through the electromagnetic filter 32, pressurized air is intermittently injected into the electromagnetic filter 32 via the valve 29. Thus, the electromagnetic filter 32
The inner filter media is completely cleaned and regenerated by the affinity of the surfactant for fats and oils and the impact stripping force of pressurized air against impurities mediated by the fats and oils. Incidentally, although the explanation is omitted, the specific usage mode of the cleaning device according to the present invention is not limited to the above-mentioned case. In order to make the effects of the present invention explained above more concrete, Table 1 is listed as a representative example. Table 1 shows the results of tests conducted under the following conditions and categories by selecting each system of the apparatus illustrated in FIG. 3 above by operating valves. (1) Conditions Raw water: Steel hot rolling wastewater, SS = 170 to 220 ppm. Electromagnetic filter...Magnetic field = 3KO _e , filtration rate =
300m/hour, filter diameter = 180mmψ, and was used repeatedly for 3 months using only conventional backwashing on a daily basis, and the electromagnetic filter that had been subjected to conventional backwashing was the subject of cleaning. At this time, the amount of SS remaining on the filter media was 270 to 310 g. Surfactant: Aqueous solution of a mixture of equal amounts of anionic surfactant and nonionic surfactant, concentration = 1% by weight, liquid temperature = 60°C, PH = 6.5, liquid feeding rate = 85/min. Pressurized air...Using the air used for conventional backwashing, pressure = 3-5Kg/cm ² , total amount used =
^0.24Nm3 . Backwash water...Total amount used = ^0.08m3 . (2) Category Target: New electromagnetic filter. Conventional example 1: As before, the object to be cleaned remains the same. Conventional Example 2: A case where conventional backwashing is performed again on the object to be cleaned. Comparative Example 1: The object to be cleaned was filled with a surfactant-containing solution, allowed to stand for 1 hour, and then drained under its own weight. Comparative example 2...1 surfactant-containing solution was applied to the cleaning target
When the self-weight is discharged after a time cycle. Example 1: The object to be cleaned was filled with a surfactant-containing solution, left to stand for 1 hour, and then discharged by spraying pressurized air. Example 2: The process of spraying pressurized air every 10 minutes while circulating a surfactant-containing solution to the object to be cleaned was carried out for one hour.

【table】

[Table] From the results in Table 1, it is clear that according to the present invention, the filter media portion of the electromagnetic filter is sufficiently cleaned and regenerated.

[Brief explanation of drawings]

Figure 1 is a system diagram illustrating the conventional electromagnetic filter processing procedure, Figure 2 is a detailed diagram of the electromagnetic filter section,
FIG. 3 is a schematic diagram corresponding to FIG. 1, illustrating a cleaning device according to the present invention. 11...Pump, 12...Liquid feeding pump, 21,2
2,...29...Valve, 31,32...Electromagnetic filter, 31a...Filter media, 41...Backwash water pressure tank, 51...Electric heater, 61...Washing liquid tank.

Claims (1)

[Claims] 1. A method for cleaning an electromagnetic filter, which cleans an electromagnetic filter on which various floating or suspended substances have separated and adhered due to use, by introducing a suitable combination of a surfactant-containing solution and pressurized air. . 2. A cleaning system in which a cleaning liquid tank equipped with a heater, a liquid sending pump connected to the cleaning liquid tank, and a control valve are installed by appropriately piping the electromagnetic filter to which the filtration system and the backwashing system are connected, as described above. An electromagnetic filter cleaning device that includes an electromagnetic filter and is connected to form a circulation path.