JPS60153914A - Element for electromagnetic filter - Google Patents

Abstract

PURPOSE:To make it possible to stably collect even weak magnetic fine particles such as colloidal iron hydroxide particles, by holding both surfaces of a thin layer constituted of a magnetic fine wire between metal nets each constituted of a strand. CONSTITUTION:Both surfaces of a thin layer 10 constituted of a magnetic fine wire having a wire diameter of about 10mum, pref., 5-20mum and comprising ferrite soft steel are held between metal nets 16 each of which is constituted of transverse wires 10 and longitudinal wires 12, both of which are sufficiently thicker than the above mentioned magnetic fine wire, and comprises a ferromagnetic material. Said thin layer 10 and the metal net 16 are laminated in a multi- layered form to constitute an element 4. As a result, weak magnetic fine particles such as colloidal iron hydroxide particles can be stably collected.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an electromagnetic filter element (hereinafter sometimes simply referred to as an element) which is a p-layer part of an electromagnetic filter.
Regarding.

[Background technology]

An electromagnetic filter is a device that magnetically captures fine magnetic particles suspended in water. As shown in Figure 1, this electromagnetic filter has a population 1 and an outlet 2 of the water to be treated.
an element 4 housed inside the filter container 3; a porous magnetic pole plate 5 disposed above and below the element 4; and an element disposed around the outer circumference of the filter container 3. 4, and a return frame 7 that converges +a east in the space outside the electromagnetic coil 6.

By energizing the electromagnetic coil, a magnetic flux is generated, and a spatial i-field is generated on the surface of the element 4 that crosses this magnetic flux. Therefore, magnetic particles suspended in the water to be treated passing through the element are magnetically captured on the surface of the element 4. When the amount of captured particles reaches a certain value or more,
After demagnetization, a cleaning step is performed in which the elements are passed through cleaning water to remove captured particles from the layer of the element 4.

The element is generally filled with thin ferromagnetic metal wires, and the configuration of this element is closely related to the performance of the electromagnetic filter. As the wire diameter of the thin metal wire becomes smaller, the gradient of the magnetic field generated on the surface of the thin wire becomes larger, and the efficiency of capturing magnetic particles increases. Furthermore, increasing the filling rate improves the capture efficiency. However, if the wire diameter is too small,
There is a problem that the mechanical strength of the element decreases and it is easily consolidated. Consolidation of the element increases water flow resistance, which has the disadvantage of further accelerating consolidation, and eventually causes the element to become clogged. This tendency is further promoted as the flow time becomes longer and trapped particles accumulate on the surface of the element. Furthermore, when the filling rate of the thin wires is increased, the water flow resistance of the element increases in the same manner as described above, and the tendency for consolidation becomes significantly large.

For this reason, in conventional electromagnetic filters, the wire diameter of the thin metal wire that makes up the element gold is 10 μm! l(W-), and wire diameters less than this value are 1. From the point of view of mechanical strength,
It had not been put into practice.

- In the field of condensate treatment at thermal or nuclear power plants,
It is necessary to remove the crud in the condensate.

The main component of cladding is considered to be magnetic particles.

The present inventors investigated the application of an electromagnetic filter to the above-mentioned cladding. As a result, it was found that the electromagnetic filter according to the prior art had an unsatisfactory removal performance in removing the crud in the condensate. The reason for this is that the condensate contains a considerable amount of colloidal iron hydroxide with a particle size of 0.5 μm or less, and this iron hydroxide is weakly magnetic.

It has been found that the electromagnetic filter does not capture the cladding, resulting in a decrease in the cladding removal rate.

Figure 2 shows an example of the experimental results. In this experiment, a magnetic flux density of 5 KG was applied to an element composed of magnetic fine wires with different wire diameters with a filling rate of 5% and a P layer height of 150 mm. The comparison shows the crud removal rate of each element under various conditions. As is clear from Fig. 2, the crud removal rate decreases as the wire diameter of the magnetic fine wire constituting the element increases. It is necessary to make it approximately 10 μm.

[Purpose of the invention]

The object of the present invention is to solve the problems of the prior art described above.

Even when an element made of magnetic fine wire with a wire diameter of about 10μ711 is used, the degree of compaction is small, and therefore even weakly magnetic fine particles such as colloidal iron hydroxide can be stably captured. An object of the present invention is to provide an element for an electromagnetic filter.

[I ready-made from IJJ]

The magnetic filter element of the present invention has a wire diameter of 10
tzm It is assumed that both sides of a thin layer made of a magnetic thin wire of ♀ degree are covered with a wire mesh made of a wire that is sufficiently thicker than the magnetic thin wire.

The magnetic wire according to this research is preferably a ferromagnetic metal wire, +&! For example, ferritic mild steel or stainless steel is used. The wire diameter is preferably 5 to 20 μL. If the thickness is less than 51 tm, it is difficult to manufacture a thin layer, and problems occur in 11j1 erodibility and mechanical strength, making it impractical. Also, if it is 20 μm or more.

The effect of trapping weakly magnetic fine particles is small, making it difficult to achieve the object of the present invention. The thin layer is formed by uniformly filling magnetic thin wires by appropriate means, and the filling rate is preferably 3 to 10%. If it is less than 3%, the mechanical strength becomes small, the element is likely to be deformed, and the effect of trapping @ particles is reduced. 1 for 10% or more
1 by capturing magnetic particles with high water flow resistance.
Water flow resistance increases, promoting compaction. The thickness of the thin layer is 1
~5 mm is preferred. In the case of 1111111 and above, the amount of discontinuous magnetic wires per thin layer is insufficient. For this reason.

H [In order to obtain the desired removal rate, it is necessary to laminate many thin layers, which is impractical. - If it is 5J or more, it is difficult to obtain the effects of the present invention described below.

The wires constituting the wire mesh according to the present invention are preferably made of a ferromagnetic material, which can be expected to have an effect of trapping magnetic particles. However, the main purpose of the wire mesh in the present invention is not to capture magnetic particles, but because its shape and strength work together with the thin layer of magnetic fine wires to exert a predetermined function and effect. A ferromagnetic material is not necessarily required. The thickness of the wire needs to be sufficiently larger than the wire diameter of the magnetic thin wire, and is preferably 100 to 1000 μm. If the thickness is less than 100 μ7, the mechanical strength of the wire mesh is low, and it becomes difficult to expect the effect of the wire mesh to improve the rigidity of the element.

At 1000 μm or more.

The degree of unevenness of the gold 114 becomes sparse, which reduces the other effect of the wire mesh, which is to sandwich the thin layer from both sides and reinforce the thin layer. Wire mesh is usually made by knitting a single piece of wire with a circular or square cross section. However, the invention is not limited to this, and for example, a thin plate with a large number of 1; Expanded wire mesh has a rectangular cross-section with sharp edges, so it is highly compatible (if it is a straight material, the magnetic flux will concentrate and the magnetic particle trapping effect will be sufficient). 1υji, ′f can be done.

The basic unit of the element according to 6 Ming is a thin layer sandwiched between two wire meshes, but if necessary, the above basic units may be laminated in multiple layers, or ,
Thin layer, wire mesh, and f: Constructed by laminating one layer at a time alternately. In order to increase the mechanical strength of the element, the thin layers are preferably made by joining thin metal wires to each other by expansion joining. Also, if the oil layer and the wire mesh are diffused and expanded in the same way,
The elements are integrated to further improve mechanical strength.

[Embodiments of the invention]

An embodiment of the present invention will be described based on FIGS. 3 and 4.

In the figure, both sides of the thin layer 1o made of magnetic thin wires are shown.

The thin layer 10 and the wire mesh 16 are stacked in multiple layers to form the element 4. FIG. 4 shows a model of the deformation state of the element when water to be treated is passed through the element for a certain period of time.

Figure (a) shows a state in which the thin layer 10 is partially consolidated by the wire meshes 16 on both sides. That is, the final layer 10 has a lower pressure at the portion A where the upper and lower wire meshes are closest to each other, and is not consolidated at other portions B, so that the initial layered thickness can be maintained. Therefore, the consolidated parts A are scattered at several points on a circular surface.

These parts 5) A k only through 9 water flow resistance is wire mesh 1
Transmitted to 0? b. Therefore, even during long-time operation, the thin layer 10 can maintain a large proportion of the portion B where the degree of consolidation is low, and the resistance to counterfeit water does not increase, and stable continuous rotation can be maintained.

FIG. 4(b) shows another deformed state of the element.

In this case, the mechanical strength of the wire mesh 16 is high, and +
iJ)! i'410 has a slight consolidation ratio on average due to 9 water flow resistance, and the upper surface of the wire mesh 16B on the side of the upper 1 jif,
The thin layers 10 are spaced apart in the F direction, creating a gap g. On the other hand, the lower surface of the downstream full wire mesh 16A and the upper surface of the thin layer 10 are in close contact with each other. Therefore, one water flow resistance is divided into 4σ of each layer of the wire mesh 16, and the water flow resistance does not accumulate and act on the oil layer of the last layer. In the actual element according to the present invention, depending on its structure, either one of the elements explained in FIG. Prevent compaction. Therefore, magnetic particles can be collected stably.

The element according to the present invention has ninth-order effects in addition to the effects μ described above. First of all, the cleaning process is performed smoothly. In the cleaning process, the element is first demagnetized and then cleaning water is passed through it, usually in the opposite direction to the direction in which the water to be treated is passed.

Because it has been demagnetized.

The magnetic particles captured by the element are removed from the element by the flow of washing water. In the present invention, the thin layer 1
0 is surrounded by wire mesh 16.

Thin layer 10f: Due to the difference in thickness between the thin magnetic wires and the wires forming the gold wire 16, countless free spaces C (see FIG. 3) are formed in the wire mesh 16. For this reason + 4 layers 1
The magnetic particles that have separated from the magnetic particles pass through the free space C and move to the primary thin layer together with the cleaning water. In such a free space C.

Since the flow of the cleaning water is changed in the direction of low water flow resistance, the magnetic particles selectively pass through the thin layer of molecules: ljJ with low water flow resistance together with the cleaning water. Therefore, the cleaning step 8 can be performed quickly and efficiently. The above-mentioned effects are greater as the layer is thinner, but as mentioned above, from a practical standpoint, the limit for the thickness of the thin layer is approximately 1 mm.

Second, in the present invention, there are fewer adverse effects caused by mutual aggregation and coarsening of the magnetic particles captured in the element. It is well known that captured magnetic particles physically or chemically bond to each other and become coarse, and for this reason, the element cannot be removed even after cleaning, and the performance of the electromagnetic filter is reduced. This results in a negative effect of a drop in performance. Since the element according to the present invention has a free space C before and after the oil layer as described in tjij, even magnetic particles that have become coarse to some extent can be extracted from the element relatively easily. therefore,
This can prevent a vicious cycle in which the remaining coarse magnetic particles become even coarser even after cleaning.

Magnetic Il:llI wire f of 5US430 whose material is ferritic stainless steel, where the wire diameter is )-(/Z nt, and the filling rate is 7%.

A thin layer was formed so that the layer height was: h mm. It can also be used as a wire mesh) 1 is 5O8430, which is a ferritic stainless steel, and the diameter of the wire is 250 μm.

The one with an opening diameter of 1.5 tn x 3 +nm and a thickness of 1 mm was used.

For each of the above oil layers, gold was sandwiched from both sides to form an element with a total thickness of 4.5 mm. Ten of these unit elements were laminated to form an element with a layer height of 45M. 9 in an electromagnetic filter using this enment.
Colloidal iron hydroxide with a particle size of 05 μm or less 10 to 50 p
Water containing PB was passed through the process at a flow rate of 600 full/h, and a magnetic flux density of KG was applied to the element, and the removal rate of iron hydroxide and the change in the differential pressure before and after the element over time were measured at 61
I got 4. The results are shown by solid line a in FIG.

In addition, the element was constructed under the same conditions as above, except that the # layer itself, the thin layer, and the wire mesh were processed by diffusion bonding (flexibility: 10-5 mmHg or less, heat treatment at a temperature of 1100°C for 1 hour). The results of the water flow experiment with f'l= are as follows:
This is shown by the solid line in FIG.

Furthermore, for comparison, a water flow experiment was conducted under the same conditions as above, except that an element according to the prior art was composed of a magnetic thin wire with a wire diameter of 811 nL and a material of 5US430 with a filling rate of 7%, +, 1 height 25 mm. The results are shown by broken line C in FIG.

Note that in each of the water passage experiments described above, no washing step was performed.

As is clear from FIG. 5, the solid lines a and 2 according to the present invention are accurate to such an extent that the removal rate gradually decreases and the differential pressure gradually increases even after long-term operation. On the other hand, the broken line C according to the prior art shows that compaction rapidly progresses from the filtration time of about 40 intercostals, and the differential pressure - color soil f1. The removal rate temporarily increases due to consolidation, but after that the differential pressure becomes excessive.
h) cannot be secured.

〔Effect of the invention〕

As mentioned above, according to the electromagnetic filter element according to the present invention, the degree of compaction is small even when using a magnetic wire made of thin magnetic wires with a wire diameter of about 10 μm.
Weakly magnetic fine particles such as colloidal iron hydroxide f<7. + can be stably captured.

Fortunately, the cleaning process can be carried out smoothly, and the harmful effects of the aggregated particles that have been captured can be greatly reduced.

[Brief explanation of the drawing]

Figure 1 shows the main structure of the electromagnetic filter.
figure. Fig. 2 is a graph showing the relationship between the wire diameter of the thin metal wire for the element and the crud removal rate, Fig. 3 is an explanatory diagram showing one embodiment of the present invention, and Figs. FIG. 5, which is an explanatory diagram showing the modified state of the example, is a graph of the results of the IIn water experiment. 3...6 filters 4...element 5...4
f1 pole plate 6... Electromagnetic coil 7... Return frame 10... Thin layer 16... Wire mesh C... Free space.

Claims (1)

[Claims] (1) Both sides of a thin layer made of thin magnetic wires with a gA diameter of about 10 μ〃L were sandwiched between wire meshes made of wires that were sufficiently thicker than the thin magnetic wires, and the wire meshes were alternately laminated. An electromagnetic filter element characterized by being