JPS58128120A - Method for reducing volume of high-performance air filter by incineration - Google Patents

Abstract

PURPOSE:To reduce the volume of a filter by incineration, by using combustible fibers instead of glass fibers used for holding the strength of filter paper of a high-performance air filter. CONSTITUTION:High-performance filter paper used for an air filter used in factories, etc. which handle radioactive materials, is constituted of fine glass fibers having the level of 20-50% by weight and 0.3-0.15mu diameter and of large glass fibers having the level of 50-80% by weight and 0.5mu and 1-10mu diameter. Among these fibers, the large-diameter glass fibers are used for holding the strength, but chemical fibers or natural fibers can be used instead of the glass fibers when the diameter is >=1mu, then such combustible fibers having >=1mu diameter are used. Thus the volume of radioactive waste is remarkably reduced because the weight of residuum of filter paper manufactured in such manner, is reduced after incineration treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for reducing the volume of a high performance air filter by incineration.

In workplaces that handle radioactive materials, such as nuclear power plants, reactor fuel processing plants, and laboratories that handle radioactive materials, it is necessary to prevent radioactive dust from dispersing to the outside. Therefore, an air tank filter using high-performance filter paper, which has a dust collection efficiency of 99.97% or more for dust with a short diameter of 0.8 μm, is used to ventilate and exhaust the room.

In this case, the air filter will be replaced when the pressure loss reaches about twice the original value, but since the air filter to be discarded is contaminated with radioactive materials,
It cannot be disposed of as is. For this reason, it is privileged to be stored in a certain place along with other radioactive waste, but in the current situation where there is no established method for disposing of it, the amount of stored waste is increasing year by year, creating great difficulties in its disposal. I am in a situation where I am. Therefore, there is a strong need to reduce the volume.

Therefore, various efforts have been made to reduce the volume as much as possible, and in the case of air filters, crushing methods and incineration methods have been proposed and implemented. For example, in the case of incineration, a high-performance filter paper (2) constructed by sandwiching metal corrugated spacing plates (1) and folding them into a corrugated shape is used in the conventionally used high-performance air filter shown in the figure. In an air filter formed by housing the spacer in a metal frame (3), the spacer plate (1) and the frame (3) are made of combustible materials such as synthetic resin or wood-based materials. This method is used to reduce the amount of waste. However, as is well known, in order to achieve a high dust collection efficiency of 99.97% or more, it is necessary to use fairly thin fibers as the material for the filter paper, and for this purpose, glass 1II1. Use of # is mandatory. Therefore, although the spacer plate and frame burn during the incineration process, the filter paper does not burn and remains as a lump, so it is impossible to reduce it to zero.
, a standard type with a depth of 800 fl and an air throughput of 80 m''/min, which is about 1 in 2 large per unit.

The present invention proposes a method for reducing the volume of a filter by incineration, which enables an even larger reduction in volume, thereby making it possible to alleviate the difficulties in waste disposal. Next, the present invention will be explained in detail using the drawings.

According to research, high-performance filter paper in high-performance filters has two
Glass fibers with a small diameter of about 0, 8 to 0.15μ account for 0 to 50% by weight, and the remaining 0.5μ and 1 to 10μ
It is composed of hyaline fibers as thick as the diameter. Glass fibers with a small diameter (approximately 0.8 to 0.15μ) increase the density of the paper, achieving a high dust collection efficiency of over 99.97%, while glass fibers with a large diameter increase the mechanical strength of the filter paper. It is mixed in to maintain strength, and this has little effect on dust collection efficiency.

Therefore, from now on, as long as a specified level of mechanical strength is satisfied under normal usage conditions, the thick glass fibers for maintaining strength among all the glass fibers in the filter paper structure should be replaced by combustible fibers such as chemical fibers and natural fibers. In this way, the volume of the used air filter due to incineration treatment can be further significantly reduced, and the amount of radioactive waste generated by the air injector can be significantly reduced.

The present invention was made based on the above idea, but
As a result of research and research, fibers with a diameter of 1μ or more can be created using chemical fibers or natural fibers (2) without using glass fibers, and filter paper using these fibers for strength retention is sufficient to withstand wind pressure under normal usage conditions. It was revealed that the dust was able to withstand and collect dust.

Furthermore, 20 to 50, which cannot be obtained depending on chemical fibers.
Only fibers with a thin diameter of 1μ or less by weight are considered glass fibers,
It has become clear that in a filter paper in which the remaining fibers with a large diameter of 1 μm or more are made of chemical fibers, the volume can be significantly reduced by incineration treatment as described below. To give an example of the experimental results, 20% by weight of polystyrene fibers with a diameter of 1 μm and 80% by weight of glass fibers with a diameter of 0.8 to 0.15μ,
A polystyrene corrugated spacing plate is inserted into a filter paper made by mixing it with a small amount of adhesive and paper-making using a paper machine, and then bending it to form a filter paper with external dimensions of 61Qsi+X610m+X3.
Air handling capacity 30 n? housed in a QOm polystyrene frame. /min filter, the residue after incineration is 0.4Kj compared to the conventional filter (2).
'Became. Comparing this as the volume before and after incineration, the volume before incineration is determined by the external dimensions of the frame 61 ff1X 5 l cmX 3 Q cI
n=l 11630cIIL3, but on the other hand, after incineration treatment, the ocher residue weight is 10.4 KP, and the thickness is 1.
4crIL1 length, 10crrL horizontally, i.e. 1.4x10X
Since 10=140cIn30) volume, the volume reduction ratio is 11161)7140 797. Therefore, it can be seen that the volume of radioactive waste can be significantly reduced by incinerating the air filter into extremely small pieces. The dust collection efficiency of this filter is the same as before, 99.97% or more for 0.8μ dust, and the pressure loss is 2.5cm/s.
15-20 MI (water column) was obtained with an air flow rate of ec.

As is clear from the above description, according to the present invention, the volume of waste produced by air filters used in offices that handle radioactive materials can be significantly reduced, and the practical effects are significant.

[Brief explanation of the drawing]

The figure is a perspective view of a high performance air filter. (1)... Corrugated spacing plate, (2)... High performance filter, (3)... Frame. Patent applicant: Yoshimi Shinobu, agent: Daibutsu, 1 person from outside the university

Claims (1)

[Claims] In high-performance air filters that use filter paper made of glass fibers, by replacing the glass fibers that maintain the strength of the filter paper with flammable fibers such as chemical fibers or natural fibers, it is possible to reduce the strength of the filter by incineration. A method for reducing the volume of a high-performance air filter by incineration, which is characterized by reducing the volume.