JPH04126511A - Large-capacity cylindrical filter - Google Patents

Abstract

PURPOSE:To increase the amt. of air passed without increasing the outer diameter and flow resistance of a filter by enlarging the air inlet of an element contg. a filter medium and diminishing the inlet in size toward the outlet and increasing the width of the pleat of the filter medium to increase the filter medium area. CONSTITUTION:A pleated filter medium 17 is rolled into a cylinder so that the area of the inlet opening is increased and reinforced by the inner wire net 14 and outer wire net 15 of the same shape to constitute an element 20 which is placed in a large-capacity cylindrical filter 10. The air contg. radioactive dust, etc., is introduced from the upper opening of an inner cavity 18 of the cylinder and passed through the inner wire net 14 and then through the filter medium 17, in which the dust, etc., are collected and removed, and the purified air is passed through the outer wire net 15 and discharged in the peripheral direction of the cylinder. At this time, the velocity of air is decreased at the upper opening, air is diffused toward the filter medium, hence the pressure drop is remarkably reduced, and the rescattering of the dust collected is prevented without decreasing collection efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to filter equipment used in air supply and exhaust systems of ventilation and air conditioning equipment in nuclear facilities and the like.

(Prior Art) The supply and exhaust systems of ventilation and air conditioning equipment in nuclear facilities and the like are equipped with particle filters for the purpose of removing radioactive dust from the air. This particle filter uses a filter medium to collect and remove dust particles in the air, but there is a limit to the amount of air that can be passed through a single area of the filter medium due to performance and strength considerations.

That is, if more than the rated air volume is passed through a single area of the filter medium, the efficiency of collecting dust and the like decreases, making it impossible to satisfy a predetermined collection efficiency. Furthermore, since the wind pressure per unit area increases, the pressure resistance of the filter medium cannot be maintained.

Therefore, in order to increase the amount of air processed by the filter, it is conceivable to widen the passage area of the filter medium, but generally a method is used in which the filter medium is folded into pleats.

There are two types of filters based on the way air flows through the pleated filter material: box-shaped filters that simply flow straight from the upstream side to the downstream side of the pleated filter material, and box-shaped filters that flow straight from the upstream side to the downstream side of the pleated filter material. There is a cylindrical filter in which water is rolled into a cylindrical shape and flows from the inner cavity side of the cylinder toward the outer circumference of the cylinder or in the opposite direction. The present invention is applied to common cylindrical filters.

When conventional cylindrical filters are used in the supply and exhaust systems of ventilation and air conditioning equipment at nuclear facilities, the following problems arise.

When the volume of air processed by the air supply and exhaust systems of ventilation and air conditioning equipment increases due to the expansion of nuclear facilities, the only option is to increase the number of filters. Filters that collect radioactive materials become radioactive waste, which increases in size, and the space required to store it also increases.

When considering retrofitting cylindrical filters, increasing the size of the filter requires the disposal of existing containment equipment. In order to increase the processing air volume while keeping the collection efficiency and pressure resistance at the specified performance without changing the outer diameter of the filter, it is possible to increase the ventilation area of the filter medium by increasing the pleat width of the filter medium. , there are the following structural problems.

That is, when the width of the pleated filter medium is increased, the distance between the ridges of the folds on the outer circumferential side and that on the inner circumferential side becomes longer, and the pressure resistance of the filter medium itself decreases. If an attempt is made to insert a reinforcing separator between the filter media, the space between the filter media will widen, reducing the number of pleats and conversely reducing the area of the filter media.

Furthermore, when the width of the pleated filter medium is increased, the circumferential internal cavity is narrowed to a smaller diameter, and the upper or lower opening of the internal cavity also becomes smaller, increasing the pressure loss of the entire filter. The current blower equipment lacks capacity.

If we try to increase the processing air volume by 1.3 to 1.5 times the current level, the pressure loss will increase by 2 to 4 times. By increasing the area, it is not possible to cope with an increase in the amount of air to be processed.

If the radioactive dust collected in the filter is re-dispersed when the filter is replaced or transported, it will lead to the spread of contamination, so currently the filter is packed in polyethylene bags, but the filter itself is not designed to contain the dust. If the filter is heavily contaminated, it is preferable to replace or transport the filter remotely to reduce radiation exposure to workers. Conventional cylindrical filters are not equipped with attachments for remote control using robots, etc. Not yet.

(Problems to be Solved by the Invention) An object of the present invention is to increase the amount of passing air without increasing the outer diameter of the filter (and without increasing ventilation resistance).

Another object of the present invention is to provide a filter that can prevent workers from being exposed to radiation during filter replacement work and can also prevent radioactive waste from leaking outside.

(Means for Solving the Problems and Their Effects) The above-mentioned object of the present invention is to roll a pleated filter medium into a cylindrical shape, and to release radioactive material from the internal cavity of the cylinder through the filter medium in the direction of the outer circumference of the cylinder. A cylindrical filter that allows air containing dust, etc. to flow through and collects the dust, etc. in the air with a filter medium, and the inner wall shape of the element containing the filter medium is changed so that the opening area of the air inlet is enlarged and the air outlet side is This is achieved by a large-capacity cylindrical filter that is formed into a substantially bellmouth shape with a smaller opening area toward the end of the filter, and the pleat width of the filter medium is increased to increase the area of the filter medium.

Based on this configuration, according to the filter of the present invention, air flows along the bellmouth shape of the element, and even if the processing air volume is increased without changing the outer diameter dimension, the pressure loss of the entire filter increases. This prevents the collected dust from scattering again without reducing the collection performance. If an attachment is installed, filters can be replaced and transported by remote control, preventing workers from being exposed to radiation and preventing radioactive waste from scattering.

One method of forming the inner wall of the element into a bellmouth shape is to form the element by stacking a plurality of donut-shaped elements such that the inner diameter of the element at the air inlet is the largest and the inner diameter of the element at the air outlet is the smallest. They can also be arranged so that their inner walls have a substantially bellmouth shape.

According to this method, it becomes easy to form a bellmouth shape.

In addition, the element containing the filter material is vertical, and air containing radioactive dust is introduced from the upper part of the internal cavity of the element, and the air flow is guided from the inner surface of the filter material to the outer surface of the filter material. and a remote control axle on the top of the cylinder.

By attaching a timent, a structure can be created that can prevent radiation exposure to workers and the scattering of radioactive waste.

Other features and advantages of the invention will become apparent from the following description with reference to the embodiments of the accompanying drawings.

Embodiment FIGS. 1-3 illustrate a large capacity cylindrical filter 10 according to a preferred embodiment of the present invention.

The filter 10 is formed by rolling a pleated filter medium 17 into a cylindrical shape so that the inlet opening area becomes large, and using an inner wire mesh (or punched metal) formed into a similar shape.
14 and an outer wire mesh (or punched metal) 15 to form an element 20, which is sandwiched between an upper casing 11 and a lower casing 12 by adhesion with a sealant 16, and fixed with fixing bolts 13.

Air containing dust, etc. flows in from the upper opening of the internal cavity 18 of the cylinder, passes through the inner wire mesh 414, and passes through the filter medium 17, where the dust and the like are collected and removed, and the purified air is passed through the outer wire mesh. 15 and is discharged toward the outer circumference of the cylinder.

When looking at the pressure loss of a filter, it can be divided into the upper opening pressure loss, the internal cavity pressure loss, the wire mesh pressure..., and the filter media pressure loss, but the part that has the greatest effect is the upper opening pressure loss. found. Therefore, in order to reduce the pressure loss at the upper opening, it is sufficient to increase the area of the inlet opening. As a result, the inflow speed of air at the upper opening is slowed down, and the air is dispersed toward the filter medium, resulting in a significant reduction in pressure loss.

According to experiments, the pressure loss at the top opening before widening the pleat width is only about 10% of the entire filter, so it does not have a large effect on the pressure loss of the entire filter. As the pressure loss increases, the pressure loss at the upper opening comes to account for about 40% of the entire filter. Here, when the opening area of the inlet is widened, the pressure loss of the entire filter becomes smaller than before widening the pleat width, and
The pressure loss at the upper opening is reduced to about 10% of the entire filter.

The pressure loss of the entire filter is reduced by the upper opening pressure...
If the pressure drops even further, the area of the filter medium has become larger, so the amount of air to be processed per single area of the filter medium has been reduced, and the pressure loss of the filter medium has been significantly reduced.

Here, the amount of air to be processed can be increased by the amount that the pressure loss of the entire filter is reduced, and a margin is created.

Conversely, even if the processing air volume is increased, the pressure loss will not increase, and the capacity of the cylindrical filter can be increased.

If the width of the pleats is increased to increase the passage area of the filter medium in order to increase the processing air volume, the internal cavity of the cylinder will become smaller and the pressure loss of the entire filter will increase, but the opening area of the inlet port will need to be increased. By doing so, it is possible to eliminate an increase in pressure loss.

In FIG. 2, an attachment 19 for hoisting the filter 10 by remote control is attached to the filter IO, and a joint part 21 for attaching the filter 10 to the filter unit is attached.
These are used for purposes described below.

4 and 5 illustrate a large capacity cylindrical filter 40 according to a second embodiment of the present invention. This filter 40
This is made by piling up pleated filter media rolled into a cylindrical shape, so that the inner surface has a stepped pseudo-bellmouth shape, which is different from the embodiments shown in Figures 1 to 3. This has the advantage of making manufacturing easier.

As shown in the figure, the element 41 in the uppermost stage has the largest inner diameter, the element 42 in the second stage has the next smallest inner diameter, and the inner diameters of the elements 43 to 45 in the third to fifth stages are the smallest. Therefore, the filter 45 in which these are stacked has a pseudo-bellmouth shape with a stepped inner surface. As a result, the same effects as in the first embodiment described above can be obtained.

Each element is reinforced with a plate at its upper or lower end,
Adjacent elements are bonded with a sealant to allow fluid to flow only in the horizontal direction. Elements 43 to 45
It is also possible to make the inside of each element tapered so that the inside diameter decreases toward the bottom, rather than vertically as shown in the figure, to more closely approximate the bellmouth shape. be.

FIG. 6 shows an embodiment in which an additional bellmouth is attached to the top surface of a filter 50 with a bellmouth-like inner surface according to the present invention, which may be adapted for specific applications.

FIG. 7 represents an example of how to use the filter according to the invention, in which the filter 10 according to the invention is housed in a filter unit 70. The filter 10 is suspended inside by opening a lid 74 disposed at the upper end of the filter unit 70, and inserted into the central opening of a horizontal partition plate 73 provided at the central portion of the filter unit 70.

The joint portion 21 of the filter 10 is seated and sealed on the gasket 75, and the attachment 19 and the lid 74 are connected and fixed by a mounting spring 78.

A gasket 77 seals between the ll74 and the unit 70.

The air containing dust and the like that flows in from the input lower 1 of the filter unit 70 is collected and removed by the cylindrical filter 10, and the purified air is discharged from the output lower 2. At this time, the collected dust, etc. is collected and removed on the inner surface of the cylinder of the filter medium 17, so even if the dust, etc. is radioactive, it will be sealed inside the cylinder, and after the filter is used. This also prevents dust from scattering and spreading contamination during movement.

Figures 8 and 9 represent situations in which a filter according to the invention is replaced. The lid 74 in FIG. 7 is removed,
A lid 84 is suspended from a hanging tool 86 and has an attachment (plug side) 81 at its lower end that can be connected to an attachment (socket side) 19 at the upper end of the filter IO. ! A gasket 85 for sealing is attached to the lower surface of 84.

As the lid 84 is lowered, the attachment 81 attached to the lower surface of the lid is automatically connected to the attachment 19 on the filter side, and the gasket 85 connects the lid 84 and the filter IO in a sealed state. Therefore, radioactive dust, etc. inside the filter is completely contained and will not leak out from this connecting part.If you lift the two together, the state shown in Figure 9 will be obtained, and the filter lO is taken out from the filter unit 70.

Furthermore, since the filter can be replaced with another filter by remote control, it is possible to prevent workers from being exposed to radiation.

(Effects of the Invention) As explained in detail above, according to the filter of the present invention,
It becomes possible to increase the amount of passing air without increasing the outer diameter and without increasing ventilation resistance, and the filter storage equipment can be used as is. By attaching an attachment to the filter, it is possible to prevent workers from being exposed to radiation during replacement work.
Furthermore, its technical effects are extremely remarkable, such as being able to prevent radioactive waste from leaking outside.

[Brief explanation of the drawing]

Fig. 1 is a top view of a filter according to the present invention, with one side shown in cross section, Fig. 2 is a front view of the filter, with one side shown in cross section, and Fig. 3 is a bottom view of the filter, with one side shown in cross section. Fig. 4 is a top view of a filter according to another embodiment, with one side shown in cross section, Fig. 5 is a front view thereof, with one side shown in cross section, and Fig. 6 is a filter according to yet another embodiment. A front view of the filter with one side shown in cross section, Figure 7 is a schematic vertical cross-sectional view of the unit housing the filter, Figure 8 is a schematic vertical cross-sectional view showing the filter before it is lifted, and Figure 9 is the filter. FIG. 10.40... Filter 11.12... Casing 14.15... Wire mesh 16... Sealing agent 17... Filter medium 18... Cavity 19... Attachment 20... Element 41 ~45... Element patent applicant Shinryo Corporation Representative Patent Attorney Masataka Ninomiya Figure 1 Figure 3 Figure 4 Figure 5 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1. A pleated filter medium is rolled into a cylindrical shape, and air containing radioactive dust, etc. is caused to flow from the internal cavity of the cylinder through the filter medium in the direction of the outer circumference of the cylinder, and the A cylindrical filter that collects dust, etc. with a filter medium, and the inner wall shape of the element enclosing the filter medium has a substantially bell-mouth shape in which the opening area of the air inlet is increased and the opening area is decreased toward the air outlet side. A large-capacity cylindrical filter characterized in that the pleat width of the filter medium is increased to increase the area of the filter medium. 2. The element is formed by stacking a plurality of donut-shaped elements, arranged so that the inner diameter of the element at the air inlet is the largest and the inner diameter of the element at the air outlet is the smallest, so that the inner walls thereof are shaped like a bell. The filter according to claim 1, which is formed into a mouse shape. 3. The element containing the filter medium is vertical, and air containing radioactive dust is introduced from the upper part of the internal cavity of the element, and the air flow is guided from the inner surface of the filter medium to the outer surface of the filter medium. Claim 1 further comprising an attachment for remote control attached to the upper part of the cylinder.
Filters listed.