JPS5876116A - Optimum operation of filtering and desalting vessel - Google Patents

Abstract

PURPOSE:To prolong the filtering life of a filtering and desalting vessel, in the condensed water filtering and desalting vessel of an atomic power plant, by a method wherein precoating operation is carried out one time or more during water sampling and the density of a precoated layer after a second layer is made lower than that of a first layer. CONSTITUTION:After a turbine is rotated by steam generated in a nuclear reactor to carry out the production of electric power, said steam is recovered as condensed water from a condenser and impurities in the condensed water are removed by a filtering and desalting vessel and a desalting vessel. In this filtering and desalting vessel, an element is precoated with a powdery ion exchange resin to filter solid substance but precoating operation is carried out one time or more during water sampling and the density of a precoated layer after a second layer is made lower than that of a first layer. That is, the resin density of the first layer is adjusted to 0.15g/cm<2> or more and the resin amount thereof is adjusted to 0.045g/cm<2> and the concn. of a precoating resin in a liquid above the second layer is adjusted to 0.05wt%. By this method, clad is perfectly removed and the utilization efficiency of the resin can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a condensate purification device, and particularly to an optimal operating method for a filtration demineralizer for condensate in a nuclear power plant.

Figure 1 shows a typical example of a conventional condensate purification system for a nuclear power plant. Steam 2 generated in the nuclear reactor 1 rotates a steam turbine 3 to generate electricity, and then is recovered as condensate 5 by a condenser 4.

Condensate contains solids (clad iron dioxide) and ionic impurities, which must be removed to improve the safety and reliability of power plants.

Precoat the element and filter especially solids.

In addition, the desalter is filled with granular ion exchange resin.
The purpose is to remove ionic impurities. The current problem with this system is that - the over-demineralizer 6 has a short lifespan. Due to the short filtration life, a large amount of fugitive waste is generated, and it is difficult to treat and dispose of it, so countermeasures are urgently needed. One countermeasure is to limit the life of the filtration, and the other is to reuse the filter agent.

An object of the present invention is to provide a good condensate purification system by effectively operating this long-life filtration system.

We propose an effective filtration method to extend the life of the temporary agent. As shown in Fig. 2, this pre-coat operation is performed again during sampling, which increases the internal filtration time (the part where the differential pressure ΔP at the inlet and outlet of the filter slowly rises). ) becomes longer.

This has the effect of increasing filtration life.

In order to extend the life of the filtration demineralizer, it is necessary to improve the utilization rate of the resin, and it is necessary to capture the crud as much as possible inside the precoat layer, but if the crud penetrates the resin layer, the filtration demineralization It is impossible to improve the performance as a salter.

Using the experimental equipment shown in Figs. 2 and 3, resin 1f was measured.
The present invention was achieved by measuring the amount of crud taken into i. The specific results will be explained below. Third
The figure is an enlarged view of the broken line Ω in FIG. 2.

In FIG. 2, raw water is sent into a filter tower 9 by a pump 8. On the other hand, from the compressor 10 to the air chamber 1
1 and sent to a filter tower 9, where the raw water is pumped. Filtration tower 9
The details of the bottom part will be explained with reference to FIG. The filtration area of the filtration tower 9 is 19.6 cm", and the amount of permeated water is 0.26 t/
minutes (flow rate = 8 m/hour). A SUS plate with a 5-diameter hole was provided at the bottom, two sheets of paper were placed on top of the SUS plate, and resin was further placed on top of that.

First, the crud removal performance of the filtration demineralizer cannot be reduced. Kg-dry resin/ currently used as a pre-coat material
Figure 4 shows the removal performance obtained by varying the resin density at m2. Entrance iron gorge degree 100ppb (
Fe20a), but the removal rate is 90%.
Since the above performance is required, the density of the $1 resin pre-coated on the element must be 0.15 g/mouth 3 or more.

Furthermore, the penetration rate of iron into the resin no. in the field treatment with a resin density of 0.15 g/(7)3 was calculated by
It was determined by line analysis using a line microanalyzer. The results are shown in FIG.

It was found that the iron had penetrated only about 3 layers from the filtration surface, trapping the crud at a thickness of 3 layers. In other words, it is sufficient for the amount of resin to be 0.0459/cm2 or more, and currently, unused resin from many companies is being used.

As mentioned above, if the filtration is sparse, the cladding will more easily penetrate into the interior, and the filtration life will be longer. 1st
The resin density of the layer should be 0.15 El/an3 or more, and since the cladding is almost completely removed, it is better if the resin density of the precoat j- after the 2nd j- is lower than the resin density of the first layer. Since the cladding penetrates into the layer, the utilization rate of the resin increases. The number of times to precoat during sampling should be determined by the life of the filtration demineralizer and the amount of priming resin. Even if the lifespan is extended, it is meaningless if the total amount of waste 5# increases. Furthermore, in order to maximize the effects of the long-life filtration system, it is important to optimize the slurry concentration of the p-filtering aid. The inventor experimentally determined the optimal operating conditions using the basic experimental apparatus shown in Figures 5g2 and 3.

The resin slurry concentration during the precoat operation is 0.01 to 1% by weight when forming the first layer, that is, the precoat layer before water sampling. This is a commonly used value. next.

2nd I--That is, when precoating is performed during sampled water, the # degree of the slurry should be 0.05% or more in terms of weight concentration in the condensate. This has become clear from the results of basic experiments, and as shown in FIG. 6, when the slurry concentration was 0.05% or more, the effect of increasing the filtration life was remarkable. To investigate in more detail, we sampled filtration 1-, which had been tested at a filtration differential pressure ΔP-1, 75 Kg/cm'', and measured the X-ray intensity of pe on the filtration HImF surface with an X-ray microanalyzer. As shown in the figure.

It was found that when the slurry concentration was small, surface filtration became more dominant than internal filtration as the second PE capture mechanism. It can be assumed that this is because when the slurry concentration is low, the second layer is formed densely, so that Fe cannot penetrate inside.

Figure 8 shows a comparison of the pressure loss increase curve for the single precoat method and the current method. It is clear that the effect of extending life is extremely large.

[Brief explanation of the drawing]

Figure 1 shows the conventional double water purification system, Figures 2 and 3 show the experimental equipment, Figure 4 shows the influence of the pre-coat layer resin density, and Figure 5 shows the influence of the resin layer in the depth direction. Figure 6 shows the iron penetration rate, and Figure 6 shows the optimum slurry concentration.
Figure 7 is a diagram showing the relationship between slurry concentration and filtration mechanism, Figure 8
The figure shows the amount of movement of the present invention 1, 1, 1, 1, 3, 4, 5, 1' (mm), 6
0 'i Aigumata Rally Destruction (wt'A) No. 8 Old Unko 8 Strange Questions (-It) Continuation of page 1 0 Invention Author: Shoji Kubota 3-1-1 Saiwaimachi, Hitachi City Stock % Formula % Hitachi, Ltd., 5-1 Marunouchi, Chiyoda-ku, Tokyo 0 Inventor Makoto Numazaki - 3-1-1 Saiwaimachi, Hitachi City Stock% Formula %

Claims (1)

[Claims] 1. An optimal operating method for a filtration demineralizer, in which the precoat operation is performed once or more during water sampling, and the density of the precoat layers after the second layer is lower than the first layer. 2. In the method described in item 1 above, the resin density of the first layer is 0.15 g/mouth 3 or more, and the resin amount is 0.045 f/cm.
Optimal operating method for filtration demineralizer with 3 or more. 3. An optimal method for operating a filtration demineralizer in the method described in WJ 1 above, in which the liquid content of the precoat resin after the second layer is set to 0.05 Wt% or more.