RU2305070C2 - Method of purification of the water by the weakly-dissociable polydispersed ionites - Google Patents

Abstract

FIELD: heat-and-power industry; other industries; methods of the ion-exchange purification of the water.

SUBSTANCE: the invention is pertaining to the production process of the ion-exchange purification of the water and may be used in the heat-and-power industry and other industries. For realization of the method the subjected to purification water is passing in the top-down direction through the floating layer of the inert substance and the separated from it by the free space area layer of the weakly-dissociable polydispersed ionite with the directly located on it layer of the coarse-grained filtering inert substance. The latter has the high mechanical strength and the density exceeding 1 g/cm³, but less than the density of the used ionite. Periodically they conduct the layer-by-layer ripper washing of the whole volume of the ionite with the coarse-grained filtering inert substance at the speed of the ascending current of 15-20 m/h and the subsequent descending feeding of the regeneration solution through all layers of the substances. The method ensures extension of the field of usage of the polydispersed weakly-dissociable ionites, increases efficiency of the water purification and allows to realize the effective regeneration of the ionites.

EFFECT: the invention ensures extension of the field of usage of the polydispersed weakly-dissociable ionites, increases efficiency of the water purification and allows realization of the effective regeneration of the ionites.

2 cl, 2 ex, 2 dwg

Description

The invention relates to techniques for ion-exchange water purification using polydisperse weakly dissociable ion exchangers, including weakly acid cation exchangers and low-basic anion exchangers, and can be used in power engineering and other industries.

A known method of purifying water in a filter loaded with a weakly acidic polydisperse cation exchange resin, comprising passing a purified water in a downward flow through a carboxylic cation exchange resin, periodically loosening the washing of the entire cation exchange resin layer with its subsequent downward regeneration with a solution of sulfuric acid (see journal. “Energy Saving and Water Treatment”, No. 1, 2003, p. 25-28).

The disadvantages of this method are its low productivity, associated with high hydraulic resistance of the cation exchanger loading layer, which has a polydisperse particle size distribution in the range of 0.3-1.2 mm, as well as leaching of fine working fractions of the ion exchanger from the filter during loosening washing.

The closest technical solution is a method of treating water with polydisperse ion exchangers, including passing purified water in a top-down direction through a floating layer of inert material and separated from it by a free space zone, loading with a layer of polydisperse ionite. Directly on the ion exchanger layer is a layer of coarse-grained filtering inert material having high mechanical strength and density greater than 1 g / cm ³ but lower than the density of the ion exchanger used, which reduces the hydraulic resistance of the loading layer and improves the productivity of the ion-exchange water treatment method. Periodic washing and regeneration of the layers is carried out in the direction from the bottom up in a dense layer (see RF patent No. 2206520, C02F 9/02, B01J 47/02, publ. 06/20/2003).

However, this method is intended only for use in it highly dissociated ion exchangers, for the regeneration of which by traditional direct-flow technology requires a significant excess of chemicals. Therefore, the use of countercurrent regeneration in this method can reduce the excess of reagents, but entails complex technological methods for its implementation. The use of weakly dissociated ion exchangers in this countercurrent technology is not effective, since it is known that when weakly dissociated ion exchangers are used for water purification, their regeneration with direct-flow technology is carried out with practically stoichiometric consumption of chemical reagents, that is, practically without their excess (see B.E. Ryabchikov “Modern water preparation methods for industrial and domestic use ”, Moscow, DeLi print, 2004, p.118).

In addition, the washing of the loading materials is carried out in a dense layer, which does not allow to efficiently remove impurities from the compressed particles of ion exchanger and filter material without increasing water consumption and energy costs.

The invention is aimed at creating a method that allows you to expand the scope of weakly dissociable polydisperse ion exchangers, increase their service life, reduce the loss of working fractions of the ion exchanger and increase the performance of the purification method and the efficiency of use of these ion exchangers in combination with simpler downstream regeneration.

This object is achieved in that the water to be purified is passed in a downward direction through a floating layer of inert material and a layer of weakly dissociable polydisperse ionite separated from it by a free space zone with a layer of coarse-grained filtering inert material directly placed on it having high mechanical strength and density greater than 1 g / cm ³ , but less than the density of the ion exchanger used, carry out a periodic loosening washing of the ion exchanger layer with a coarse-grained filtering layer of its inert material at an upward flow rate of 15-20 m / h, which ensures layer-by-layer expansion to the entire height of the free space zone, and the regeneration solution is fed from top to bottom and successively passed through layers of inert material, coarse filter material and ion exchanger.

The height of the free space zone is 10-100% of the total height of the ion exchanger layer and the layer of coarse filter inert material.

As a coarse filter inert material, for example, a styrene-divinylbenzene copolymer is used.

The particle size distribution of the styrene-divinylbenzene copolymer is 0.5-3.0 mm, which is significantly larger than the particle size distribution of 0.3-2.0 mm of weakly dissociable polydisperse ion exchangers. This material has high mechanical strength. For example, the copolymer grain is destroyed under a load of 15-20 kg per grain, and the grain of any ion exchanger is destroyed under a load of 0.4-1.2 kg per grain.

Figure 1 presents a diagram of a method of purifying water with a weakly dissociable polydisperse ionite at the stage of purification and regeneration, figure 2 is a diagram in the washing mode.

The filter 1 contains a nozzle 2 for supplying purified water, a regeneration solution and a stream outlet after loosening washing, an upper distribution device 3 connected to a nozzle 2, a nozzle 4 for draining purified water, spent regeneration solution and an upward flow for loosening washing, a lower distributing device 5, connected to the fitting 4, a floating layer of inert material 6 and a load consisting of a layer of weakly dissociable polydisperse ionite 7 and a coarse-grained layer located on it first filtering inert material 8. Between the layers of floating inert material and coarse-grained filtering inert material is a free space zone 9 (Fig. 1).

The method is as follows.

The purified water is fed into the filter 1 through the nozzle 2 and the upper distribution device 3. The water flows downward in succession to a floating layer of inert material 6, a layer of coarse filter inert material 8 and a layer of weakly dissociable polydisperse ionite 7. The purified water is discharged through the lower distribution device 5 and the union 4. The non-mixing of the loading layers is ensured by the difference in grain densities of the coarse filter inert material and ion exchanger. A coarse-grained filtering inert material, for example, a styrene-divinylbenzene copolymer, protects a polydisperse ionite layer having low hydraulic characteristics from contamination and mechanical failure due to a decrease in hydraulic resistance, since the upper load of up to 90% resistance is taken by the upper layer of high-strength and coarse-grained styrene and divinylbenzene (figure 1).

After completion of the working cycle, the washing process (Fig. 2) and subsequent regeneration (Fig. 1) are carried out with the aim of respectively removing impurities and restoring the exchange capacity of the ion exchanger. To do this, through the nozzle 4 (figure 2) and the lower switchgear 5 serves upward flow of water for loosening the washing of the load at a speed that provides a layer-by-layer expansion of the load. In this washing mode, the fine working fractions of the ion exchanger are not washed out with a stream of water. At the same time, the loading volume expands and occupies the free space zone 9. Due to the arising effect of intralayer friction, an effective process of cleaning the surface of the grains of the filter material and ion exchanger from pollution occurs. Floating inert material freely passes a stream of water with impurities during loosening and delays whole grain grains.

Next, through the nozzle 2 and the switchgear 3, the regeneration solution is supplied in a downward flow, passed through it in a downward flow through all layers and the spent regeneration solution is discharged through the lower switchgear 5 and the nozzle 4 (Fig. 1)

Example 1

Imported low-acid cation exchange resin of type MAC-3, IRC-86, C-104 or CNP-80 is imported into a parallel-flow hydrogen-cation exchange filter with a diameter of 2000 mm with a particle size distribution of 0.3-1.2 mm, density 1.15-1.20 g / cm ³ and in the amount of 3800 l to a height of 1.2 m. As a coarse filter inert material, a granular copolymer of styrene and divinylbenzene with a particle size distribution of 0.8-2.0 mm and a density of 1.05 g / cm ³ located on a layer of cation exchanger. The height of the layer of filtering inert material is 300 mm. As an inert material of the floating layer, low-pressure polyethylene with a particle size distribution of 2-5 mm and a density of 0.95 g / cm ³ , the lower layer of which is 200 mm lower than the upper switchgear 3, is used. The height of the free space zone 9 is 1000 mm. Purified water with a suspended matter content of 7-8 mg / l, a total hardness of 4.5 mEq / l and a total alkalinity of 3.5 mEq / l is passed at a speed of 30 m / h, i.e. with a flow rate of 94 m ³ / hour from top to bottom sequentially through a layer of floating inert material, a layer of filtering inert material and a layer of cation exchanger. At the outlet of the hydrogen-cation filter, the purified water had a suspended matter content of less than 0.5 mg / l, a total hardness of 1.7 mEq / l, and a total alkalinity of 0.7 mEq / l. The quality of the purified water fully meets the quality requirement of replenishment of heating networks according to the carbonate index for a heating temperature of up to 130 ° C.

With an increase in total alkalinity in purified water above 1.0 mEq / L, the hydrogen-cation exchange filter is switched off for regeneration. For this purpose, water is preliminarily fed into the filter from the bottom up with a flow rate of 15-20 m / h in order to loosen the washing of the filter layer and the cation exchange layer, which are in suspension and occupy the entire filter volume in layers. At the same time, a layer of floating inert material does not pass the grains of the styrene-divinylbenzene copolymer, but passes undissolved contaminants delayed by the copolymer layer during filtration of the treated water. Layer-by-layer expansion of the load is necessary due to the prevention of the removal of small working fractions of cation exchange resin from the filter. After completion of the loosening washing, a regeneration solution of 0.7% sulfuric acid is fed in a downward flow at a speed of 10 m / h to restore the exchange capacity of the cation exchange resin.

Example 2

A low-basic anionite AN-31 of domestic production with a particle size distribution of 0.3-2.0 mm, with a density of 1.15-1.20 g / cm ³ and in the amount of 4000 l to a height of 1.3 is loaded into a parallel-flow anion exchange filter with a diameter of 2000 mm m. A layer of filtering inert material and a layer of floating inert material are used similarly to the above example 1. It is known that the AN-31 anion exchanger has low mechanical strength and its annual refilling into the filter is up to 30% of the used volume, which in turn limits the flow rate of the cleaned water through it no more than 10 m / h. The use of a coarse-grained filter layer of a high-strength styrene-divinylbenzene copolymer will protect the anion exchange resin from mechanical failure, as well as increase the speed of water treatment to 20-25 m / h.

Thus, the use of this method provides an extension of the field of application of polydisperse weakly dissociated ion exchangers, increases the productivity of water purification and allows for the efficient regeneration of ion exchangers.

Claims (2)

1. A method of purifying water with polydisperse ion exchangers, including passing the purified water in a downward direction through a floating layer of inert material and a layer of polydisperse ionite separated from it by a free space zone with a layer of coarse-grained filtering inert material directly on it having high mechanical strength and density greater than 1 g / cm ³ but less than the density of the ion exchanger is used, periodic flushing of the ion exchanger layers and the coarse filter inert material upwardly a stream followed by a supply of a regeneration solution, characterized in that weakly dissociable ion exchangers are used as polydisperse ion exchange resin, washing the layers of ion exchange resin and coarse-grained filter inert material is carried out in a loosening mode at an upward flow velocity of 15-20 m / h, which provides layer-by-layer expansion over the entire zone height free space, and the regeneration solution is fed in the direction from top to bottom and sequentially pass it through layers of inert material, coarse filter conductive inert material and ion exchanger. 2. The method of claim 1, characterized in that the height of the free space zone is 10-100% of the total height of the layer of ion exchanger and the layer of coarse filter inert material.

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