SU1389839A1 - Method of regeneration of h-cation exchanger filter - Google Patents

Abstract

The invention relates to processes of ion-exchange water purification on H-cation-exchange filters, followed by their regeneration. The purpose of the method is to increase the degree of regeneration of the filter and increase its quality. A method for regenerating an H-cation-exchange filter operating in a mode of desalting water containing calcium, magnesium, and sodium ions is that after forming in the filter successively located from top to bottom saturation zones of calcium, magnesium and sodium with intermediate zones of magnesium displacement by calcium and sodium and magnesium, as well as zones of hydrogen displacement by sodium; sodium filter is disconnected from the filter for regeneration and solutions of sodium chloride and sulfuric acid are sequentially passed from bottom to top, and the solution p sodium chloride solution is fed into the displacement area of magnesium and sulfuric acid - hydrogen displacement zone sodium. The method allows to increase the working exchange capacity of the H-cation exchanger by 15% and to reduce the residual sodium content in the filtrate by 2.5 times. The lack of acidity in the treated sodium chloride solution simplifies waste disposal. 2 Il. 2 tab. o (l

Description

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The invention relates to the processes of ion-exchange water purification and the extraction of valuable components from it and can be used in the chemical, thermal power, electronic and other industries.

The purpose of the invention is to increase the degree of filter regeneration and improve the quality of the filtrate.

FIG. Figure 1 shows the dependences of the distribution of the Ca, Na cations over the height of the H-cation exchanger; in fig. 2 - the pattern of distribution of ions in the lower part of the filter after preliminary regeneration with a solution of NaCl and acid.

The method is carried out as follows.

The KU-2 cation exchanger in the H form is loaded onto a plexiglass column with an internal diameter of 16 mm and a loading height of 120 cm, through which water of the following cationic composition mEq / l is filtered: 3.4; Mg 0.9, Na 1.5 until sodium breakthrough into the filtrate. When filtering through the H-cation exchanger from top to bottom of water containing calcium, magnesium and sodium, the H-ions of the upper layers of the cation exchanger are replaced by these ions. After formation of consecutively saturated calcium, magnesium and sodium saturation zones in the H-cationite layer with intermediate zones of calcium and magnesium displacement with magnesium, as well as a zone of sodium displacement by sodium, the filter is disconnected for two-stage regeneration by sodium.

The regeneration is carried out by sequential processing of the filter from bottom to top with solutions of sodium chloride and acid, and the solution of sodium chloride for regeneration is fed into the filter in the sodium-magnesium replacement zone, which is practically free of H + -ONES. At the final stage of regeneration, a 5% solution of H2SO4 is fed through the lower drainage of the filter to the zone of hydrogen displacement by sodium, which passes through the entire ion-exchange layer with the discharge of the spent solution through the upper distribution unit.

An experimental study was carried out of the pattern of absorption by the cation exchanger in the H-form of a mixture of Ca, Mg, Na cations in the mode of water desalination of the specified composition and the distribution of components along the height of the cation exchanger KU-2 was found by the time it was turned off at the beginning of the breakthrough of Na into the filtrate. The total height of the cation exchanger - 1.2 m was divided into 12 equal layers 10 cm high, each of which ended with an intermediate drainage. The total volume of loading is 240 ml, the volume of loading of each section is 20 ml. The part of the load that was spent on Ca and is determined by successive passing of 8% NaCl first through the intermediate drainage of section No. 1 (top), then No. 2, etc.

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with the continuous determination in the spent solution, the concentration of ions of Ca, Mg and acidity. In this case, Ca and Mg are determined by a titrimetric method using Trilon B, Na is determined by plasma photometry, and acidity is determined by a titrimetric method.

The section, from loading of which there is a sharp decrease in the desorbed Ca, Mg ions and, accordingly, an increase in Na ions, provided that the solution is neutral, is defined as a transition zone. Said determination of the location of the zones is performed one-phase prior to the operation of the filter.

The upper (frontal) layers of the cation exchanger (Fig. 1) are equilibrated by the Ca + cations, with the maximum saturation with the Ca cations occurring on the 1-3th layers. The downstream layers 4-6 relate to a calcium-calcium replacement zone. The 6th layer also contains the zone of maximum magnesium content and the zone of substitution of sodium for magnesium, the 7th layer is the continuation of the zone of substitution of sodium for magnesium. The zone of maximum saturation of sodium is layers 7 and 8.

Below is the zone of substitution of hydrogen by sodium (protective layer of H-ions) - layers 9-12. For the water composition in question, the NaCl solution at stage I of the regeneration must be supplied at the boundary of the 6th and 7th layers, i.e., to the sodium replacement zone with magnesium.

The found layer-by-layer distribution of cations reflects the state of the H-cation exchanger layer only for the reduced composition of water. However, in general, it gives a characteristic picture of the placement of zones for the conditions of the H-cation exchanger shutdown at the beginning of the sodium leakage into the filtrate in the desalting mode.

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Possessing relatively high mobility, single charged sodium ions appear in the filtrate long before the filter exchange capacity is exhausted. This is confirmed by FIG. 1. on which the area occupied by H-ions in the ion exchanger, at the time of passage of sodium ions is large enough.

In tab. 1 shows the percentage distribution of ions after sorption over the height of the cation exchanger KU-27. Presented in table. 1 data indicate that the percentage of H ions, starting from the 8th layer, exceeds 50%. The supply of the NaCl solution at the preliminary stage of regeneration to the zone of substitution of sodium by magnesium allows, in the proposed method, to preserve all the reactive H ions.

The degree of regeneration of the lower layers of ionite 5 determines the quality of the filtrate. The more fully the lower layers of sodium are regenerated (the first ion that slips into the filtrate), the higher the quality of the filtrate.

In order to compare the degree of regeneration of the lower (output) layers of the cation exchanger, an experimental study of the layer-by-layer distribution of ions after the I and II stages of the regeneration of the H-cation exchanger was carried out in the known and proposed methods. In the known method, the NaCl solution is fed from below through the entire filter loading, i.e. the regenerating solution enters the last 12th layer, and in the proposed method, the NaCl solution

total salt and acid consumption for regeneration, solution concentrations, regeneration and sorption rates, loading volumes are the same in both cases).

As can be seen from the data table. 2, the residual Na content is 2.5 times lower, and the working exchange capacity of the H-cation exchanger is 15% higher in the proposed method than in the known one. The advantage of the proposed method is also an increase in the quality

Tra operating in the desalting mode of water containing calcium, magnesium and sodium ions, which means that after the formation in the H-cationite layer, it is subsequently passed through an intermediate drainage, the filtrate is 10, as it is not concentrated in the 6th and 7th layers. of the nd layer of lottery simplifies and reduces the cost of utilization-cation exchanger. As a result, in the well known range of wastewater — waste solutions of a coolant after stage I of the regeneration of soluble sodium, the NaCl rum all the lower part of the filter is over-.

Claims (1)

leads to the Na form (Fig. 2a), since the formula of the invention During the passage of the NaCI solution, the ions. The method of regeneration of the H-cation-exchange filter — Na easily displaces the remaining unused H ions and a small part of the hardness ions. In the proposed method, the supply of NaCl solution through intermediate drainage allows to preserve all reactively located from top to bottom zone-capable H ions in the lower part of the saturation with calcium, magnesium and sodium from the load, as well as to displace part of the ions by intermediate zones of displacement of the magnetization (Fig. 2 b). Calcium and sodium with magnesium, and in addition, if in the known method of sodium displacement zone by sodium, the filter that was worked out at the preliminary stage of sodium is turned off, the NaCl solution contains the H ions, which requires 25 tion and, from it upwards, the succession of alkali to neutralize it, the solutions of sodium chloride are passed through; in the proposed method, the spent NaCl solution contains only hardness ions. The neutrality of the filtrate in this case facilitates its further chemical softening and reduces the cost of processing. Thus, the selective removal of hardness ions from the filter simultaneously solves two problems: it simplifies and reduces the cost of waste disposal and prepares a layer of cation exchanger for efficient regeneration with an acid solution. In both methods, sulfuric acid is passed through the entire load of the filter from the bottom up. Different initial layer-by-layer ion distributions at the bottom of the filter lead to different degrees of regeneration of the ion exchanger with the same 40 stoichiometric acid consumption. By passing an acid in a known method (Fig. 2 b), it is not possible to displace deeply the Na ions from the bottom of the filter. In the proposed method (Fig. 2 g), the entire lower part of the ion exchanger is almost completely converted into the H-form. In this case, not only an increase in the degree of regeneration of the output layers is achieved, but also an expansion of the zone, which is almost completely converted to the H form. In fact, the output layers of the cation exchanger (11 and 12) in the known method after regeneration 50 with acid have approximately the same degree of regeneration as far from the exit of the 6th and 7th layers of the cation exchanger in the proposed method. The difference in the degree of regeneration of the lower layers of propion and sulfuric acid, the solution of sulfuric acid being supplied to the hydrogen displacement zone by sodium, characterized in that, in order to increase the degree of filter regeneration and improve the quality of the filtrate, the sodium chloride solution is supplied to the sodium displacement zone with magnesium. Table 1 35 is as a filtrate. The obtained technological parameters of the filter, as well as a comparison of known, are given in table. 2 (with 55 total salt and acid consumption for regeneration, solution concentrations, regeneration and sorption rates, loading volumes are the same in both cases). As can be seen from the data table. 2, the residual Na content is 2.5 times lower, and the working exchange capacity of the H-cation exchanger is 15% higher in the proposed method than in the known one. The advantage of the proposed method is also an increase in the quality a trap operating in a desalting mode of water containing calcium, magnesium and sodium ions, which means that after the formation of an H-cationite calcium, magnesium and sodium saturation zone with intermediate displacement zones in the H-cation layer after the Magnesium calcium and sodium magnesium, as well as the zone of hydrogen displacement by sodium, cut off the filter through the sodium passage to the regeneration and through it from the bottom upwards sequentially pass the solutions of sodium chloride The method of regeneration of N-cationite calcium-, magnesium-and-sodium-containing saturation zones from top to bottom with intermediate zones of magnesium displacement by calcium and sodium by magnesium, as well as hydrogen displacement zone by sodium, is cut off by sodium filter through regeneration and from bottom to top, solutions of sodium chloride are consistently passed through. sulfuric acid, and the sulfuric acid solution is supplied to the hydrogen displacement zone by sodium, characterized in that, in order to increase the filter regeneration rate and improve the quality of the filtrate, sodium chloride solution is supplied to the sodium displacement zone with magnesium. Table 1  40 45 50 35 55 table 2 Working exchange capacity, mEq / l 600 The residual amount of sodium in the filtrate, mg / l Acidity of the treated solution, mEq / l SU i  - 5С five "ABOUT ( t (U I "J § I I s as Numbers Layer8 Figure 1 U 12 750 1.0 Stage I of generation M stage of regeneration 2.0 ;,five W 0.5 about Had S 10 k If- layer stage regeneration On 8 Yu 12 f / s Slo R stage by Peiefiepaijiuu one 8 to iZ // SMYA S Yu IZ f / s layer FIG. 2