RU2163568C1 - Water treatment process - Google Patents

Abstract

FIELD: water treatment. SUBSTANCE: invention relates to ion-exchange technology for desalting and softening of water with simultaneous reduction of water alkalinity, which can be applied in powering engineering for production of high-quality conditioned water appropriate as heat carrier. For that, initial water is desalted on H- filters by consecutively passing it through carboxyl cationite and sulfonic cationite, after which water is treated on OH-filters. Softening is performed by consecutively or concurrently passing water through carboxyl and sulfonic cationites in two steps: desalted water is first passed through cationites depleted in water desalting operation until hardness ions slip through sulfonic cationite and then water is passed through the same cationites additionally treated with spent OH-filter-regeneration solution, which is passed successively through carboxyl and sulfonic cationites. Exhausted H-filters are regenerated by passing regeneration acid solution first through sulfonic cationite and then through carboxyl cationite. Working capacity of cationites is further increased by treating carboxyl cationite with acid spent H-filter-regeneration solution from previous regeneration operation before acid regeneration of carboxyl cationite filter. Invention allows sodium ion level in desalted water to be reduced by 80 times and alkalinity in softened water to be stabilized and reduced to values 0.34-0.4 mg-equ/cu.dm. Working capacity of cationites increases by 2.6-3.4 times resulting in 2.6-3.8-fold increase of summarily produced desalted and softened water. EFFECT: essentially increased water treatment efficiency. 2 cl, 1 dwg, 1 tbl, 3 ex

Description

 The invention relates to the field of water treatment, in particular to the ion-exchange technology of desalination, water softening while reducing its alkalinity, and can be used in the energy sector to produce high-quality conditioned water, suitable for use as a coolant.

A known method of producing deeply softened water / SNiP 2.04.02-84. Water supply. External networks and facilities. Gosstroy of the USSR. -M.: Stroyizdat, 1985. -136 p. / [1]. According to the method [1], water is treated sequentially in two ion-exchange filters. The first filter contains a carboxyl cation exchanger regenerated by an acid, and the second contains a sulfocation exchanger regenerated by a solution of sodium chloride. The residual hardness of the treated water is 0.01 mEq / dm ³ , the alkalinity is 0.7-1.5 mEq / dm ³ , the specific acid consumption is 1 eq / eq of removed cations of temporary hardness, the specific consumption of sodium chloride is not less than 100 g / equiv of removed ions of constant hardness, the working capacity of carboxylic cation exchanger is 500-600 mEq / dm ³ , the working capacity of sulfocationite is not more than 1350 mEq / dm ³ .

 The disadvantages of the method [1] are high specific consumption of reagents, low working capacity of carboxylic cation exchange resin, large discharges of water-soluble salts, low productivity of the process.

A known method of producing demineralized water / Prokhorova A.M., Alekseeva T.V. On the prospect of using domestic carboxyl cation exchangers for stepwise countercurrent cationization of water. // Heat power engineering. - 1976.-N 9.P. 83-85 / [2]. According to the method [2], water desalination is carried out by H-OH ionization, moreover, on H-filters, water is treated by sequential filtering through carboxyl cation exchange resin and sulfocationite. The regeneration of cation exchangers is carried out with an amount of acid close to stoichiometry (1 equiv / equiv of absorbed cations). The average working capacity of carboxyl and sulfocationite is about 600 mEq / dm ³ . The method is effective with significant relative alkalinity of the water subjected to H-ionization: the stoichiometric consumption of sulfuric acid for the regeneration of cation exchangers is achieved if the ratio of alkalinity to the sum of acid anions in the source water is at least 0.75.

 The disadvantages of the method [2] are a narrow area of its effective application and low working capacity of cation exchangers.

Closest to the invention in technical essence and the achieved result is a method of preparing desalinated and softened water / A.s. N 1791392 A1, SU, MKI ⁵ C 02 F 1/42, Method for continuous preparation of water. // B.V. Stavitsky, M.N. Kobzarenko. - Publ. 01/30/93. Bull. N4 / [3]. According to the known method [3], the source water is subjected to reagent softening to obtain water with no constant stiffness, followed by desalination on H and OH filters. After depletion during desalination (when sodium ions pass into the filtrate), H-filters are used to produce softened water. To do this, the reagent softened source water is filtered through H-filters used during water desalination. Water softening on H-filters is stopped when the maximum permissible stiffness of the filtrate is reached, which is determined by the requirements of the water consumer, after which the filters regenerate. OH filters are regenerated with alkali, and the neutral part of the obtained spent regeneration solution, together with the soft effluents of the previous H-filter regeneration operation, is used for pre-treatment of the latter. H filters are regenerated in two stages: by pretreatment with a mixture of soft effluents of H and OH filters, and then with a stoichiometric flow of sulfuric acid. After the first stage of regeneration, hard drains are obtained, and after the second stage, soft (containing sodium salts) drains are obtained, which are mixed with the neutral part of the wastewater of OH filters and used for pretreatment of the H filter in the next operation of its regeneration.

 According to the known method [3], water is processed on H- and OH-filters in which there is no constant hardness (there is only temporary hardness), which makes it possible to obtain both desalted and softened water using the same H-filters at a stoichiometric flow rate sulfuric acid to regenerate the latter.

In the description of the known method [3] there is no data on the quality of the obtained demineralized water, the alkalinity of softened water, the working capacity of the cation exchanger, and also on the efficiency of using the method in the case of treatment of water with constant hardness on H- and OH-filters. To determine the quality indicators of demineralized and softened water, the working capacity of the cation exchange resin, we implemented the well-known water treatment technology [3]. It was found that when desalting and softening the source water only with temporary hardness of the composition, mEq / dm ³ ; stiffness - 0.8; alkalinity - 0.8; strong acid anions - 2; sodium ions - 2 (table, example 4) according to the known method [3], the content of sodium ions in demineralized water was 0.32 mEq / dm ³ . The alkalinity of the softened water was 0.74 mEq / dm ³ , and the hardness was 0.01 mEq / dm ³ . The working capacity of the cation exchanger was 680 mEq / dm ³ , (table, example 4). Similar results were obtained during the preparation according to the known method [3] of water with both temporary and constant hardness: the sodium content in demineralized water was 0.32 mEq / dm ³ , the alkalinity of water decreased from 0.8 to 0.62 mg equiv / dm ³ , and the working capacity of the cation exchanger was 650 mEq / dm ³ (table, example 6).

In the known method [3], the stoichiometric consumption of sulfuric acid for the regeneration of H filters (1 equiv / equiv of absorbed ions) is achieved by regeneration of the cation exchange resin with sulfuric acid from the sodium form, into which the cation exchange resin is converted by pretreatment with soft effluents. This technique, as is known, allows for the stoichiometric consumption of sulfuric acid to desorb from the cation exchanger no more than 700 mEq / dm ³ of sodium ions, which corresponds to the conversion of cation exchanger to the H form by (700/1700) · 100 = 41% / G. .Feysiev. Highly effective methods of softening, desalination and desalination of water. - M .: Energoatomizdat, 1988 (Fig. 5.1 a, p. 100) / [4]. Such a value of the regeneration efficiency coefficient corresponds to the concentration of sodium ions in H-ionized and, therefore, in demineralized water, equal to 1.4; 2.8; 5.6 mEq / dm ³ with a content of strong acid anions in the feed water, respectively 2.5; 5 and 10 mEq / dm ³ [4, table 5.2], which is consistent with our data on the low quality of desalted water according to method [3] due to the high content of sodium ions.

 Thus, the disadvantages of the known method [3] are the low quality of demineralized and softened water, which is due to the significant content of sodium ions in demineralized water, close to the alkalinity of the source water, the alkalinity of softened water, as well as the low working capacity of cation exchange resin.

 It follows from the foregoing that the problem of improving the quality of water used as a coolant by reducing the content of sodium ions in demineralized water, lowering the alkalinity of softened water, increasing the working capacity of cation exchange resin with a stoichiometric flow of acid to regenerate cation exchange resin is relevant and important.

Indeed, for example, the content of sodium ions in demineralized water intended for feeding boilers with a pressure of 13.8 MPa should not exceed 100 μg / dm ³ (0.0043 mEq / dm ³ ) / Rules for the technical operation of power plants and networks. M .: Energoatomizdat, 1989, - p. 152 / [5]. For boilers with a pressure of 3.9 MPa with drums having riveted joints, the relative alkalinity of softened water should not exceed 20% [5, p. 149]. Upon receipt of softened water according to the known method, the relative alkalinity is 24 - 27% (table, examples 4, 6).

 The basis of the invention is the task to develop such a method of water treatment that would ensure, through the use of a complex of ion-exchange materials and technological operations, the achievement of a technical result - improving the quality of demineralized water (by reducing the content of sodium ions) and deeply softened water (by reducing its alkalinity) , increasing the working capacity of cation exchanger with stoichiometric specific acid consumption.

 To solve this problem, a method for preparing water is proposed, which includes desalting the source water on H and OH filters, softening the source water on H filters depleted during desalination, regenerating OH filters with alkali, treating spent H filters with spent regeneration solution of OH filters and their regeneration with acid, in which, according to the invention, carboxyl cation exchange resin and sulfocation ion exchange are used as H-filter charge, and desalination is carried out by sequentially passing the initial water through carbo strong cation exchange resin and sulfation cation exchange resin, softening is carried out by sequential or parallel passing of water through carboxyl cation exchange resin and sulfation cation exchange resin in two stages: at the first stage, water is passed through cation exchangers depleted during desalination of water until the hardness ions pass through sulfation cation exchange resin, and at the second stage water is passed through them the cation exchangers treated additionally with the spent regeneration solution of OH filters by passing the latter successively through carboxyl cation exchange resin and sulfocati it is regenerated and H-filters subjected to regeneration are subjected to softening by passing the acid sequentially through sulfocationite and carboxylic cation exchanger, and when regenerating H-filters with acid, carboxylic cation exchanger is pretreated with the spent regeneration solution of H-filters from the previous regeneration operation.

We found that sequential filtering of water through a carboxylic and then sulfocationionite at the stage of desalination, softening of the initial water by sequential or parallel passing through carboxylic cationite and sulfocationite in two stages: at the first stage - through cation exchangers depleted during water desalination, until the hardness ions pass through sulfocationite, and on the second - by passing water through the same cation exchangers, additionally treated with the spent regeneration solution of OH filters by passing the last Thus, through carboxylic cation exchange resin and sulfocationite, as well as the regeneration of H-filters spent upon water softening, passing the acid sequentially through sulfationation and carboxylic cation exchange resin provides desalted water with a low (0.004 mEq / dm ³ ) content of sodium ions and deeply softened water ( hardness of 0.01 mEq / dm ³ ) with low (0.34 - 0.4 mEq / dm ³ ) alkalinity and the relative alkalinity of softened water (14-17%) corresponding to standards [5] with less than stoichiometric, acid consumption for regen cation exchange resin (0.84 - 0.96 equiv / equiv), high working capacity of cation exchangers (1670 - 1800 mEq / dm ³ ) (table, examples 1, 2, 5).

An additional positive effect (increasing the working capacity of cation exchangers in the H-filter to 2320 mEq / dm ³ ) in the proposed method is achieved through the use of acid spent regeneration solutions of H-filters of the previous regeneration operation for pre-treatment of the carboxyl cation exchange resin during the regeneration of the H-filter with acid ( table, example 3).

 The result obtained is unexpected, since it is known that, in contrast to sulfocathionite, a carboxylic ionite can absorb only part of the cations associated with carbonic anions when desalting water, while sulfocathionite can absorb all cations (associated with both strong acid and carbonic anions) [ 12]. Based on this, it was impossible to expect that the use of carboxylic ionite along with sulfocationionite at the stage of water desalination can lead to a decrease in the content of sodium ions in demineralized water.

It is known that the alkalinity of water treated with carboxylic cation exchanger regenerated at a stoichiometric flow rate of sulfuric acid is 0.7-1.5 mEq / dm ³ , and its hardness is 0.7-1.5 mEq / dm ³ more than constant hardness of the source water [1]. The working capacity of carboxylic cation exchanger with a stoichiometric acid consumption for regeneration with water softening is 500 - 600 mEq / l [1]. When desalting water by sequentially filtering it through a carboxylic and then sulfocationite, the working capacity of cation exchangers is 508–615 mEq / L [2]. The treatment of carboxylic cation exchange resin with an alkaline solution leads to a decrease in the hardness of the treated water, but is accompanied by a simultaneous increase in the pH and, consequently, in the alkalinity of the softened water / U.S. Patent No. 4083782, MKI 02 02 1/76. A method of conditioning water. //R.Kunin- Publ. 04/11/78 / [6]. Therefore, due to the use of carboxylic ionite at the stage of water softening, along with sulfocationionite in the treatment of cation exchangers with alkaline wastewater OH filters, one could not expect a decrease in the alkalinity of water treated by the proposed method, compared with the same indicator for the known method [3] and working capacity of cation exchangers (table, examples 1 to 6).

 Thus, the production of demineralized water with a low content of sodium ions and deeply softened water with a low alkalinity with an increase in the working capacity of the cation exchanger at a lower than stoichiometric specific acid consumption by the proposed method is not a consequence of the use of known techniques, but is guaranteed by the whole set of essential features.

Thus, the set of essential features is necessary and sufficient to achieve the technical result provided by the invention — improving the quality of demineralized water (by reducing the content of sodium ions to 0.004 mEq / dm ³ (95 mcg / dm ³ ) and deeply softened water (due to reducing its alkalinity to 0.34 - 0.4 mEq / dm ³ ) with an increase in the working capacity of cation exchanger to 1670 - 2320 mEq / dm ³ with less than the stoichiometric specific acid consumption (0.84 - 0.96 eq. / equiv) for the regeneration of cation exchangers.

 The implementation of the method is illustrated by the diagram in the drawing.

The source water (as source water can be used only water with temporary hardness (table, examples 1-3), and water with constant hardness (table, example 5)) are successively filtered through carboxylic cation exchange resin, sulfocationite and anion exchange resin, respectively loaded into ion-exchange apparatuses 1, 2, 3. As a result, desalted water is obtained with a content of sodium ions at the level of the required indicators (in specific examples, no more than 0.004 mEq / dm ³ , which is equivalent to 4 mcg eq / dm ³ ). After reaching the specified maximum permissible concentration of sodium ions in demineralized water, the apparatus 3 loaded with an anion is turned off, and the transmission of the source water through cation exchangers in apparatuses 1 and 2 is continued in order to obtain softened water. Softened water is obtained by sequentially filtering the source water through a carboxyl cation exchange resin in apparatus 1, and then through sulfocationion in the apparatus 2 or by dividing the initial water into two streams, one of which (stream B) is passed through the carboxyl cation exchanger and the second (stream C) through sulfocationite in parallel with the subsequent combination and obtaining softened water. After reaching the maximum permissible hardness in softened water with sulfocationite water, the transmission of the source water through the apparatus 1, 2 is stopped, and the anion exchange resin in apparatus 3 is regenerated with an alkali solution (sodium hydroxide) to desorb anions. Residual alkali from anion exchange resin is washed with demineralized water. The result is a spent OH-filter regeneration solution (stream A), which is first passed through a carboxyl cation exchanger, and then through a sulfocationite. After passing the spent regeneration solution of the OH filter, the cation exchangers are washed with water. Then, the source water is continued to be passed through the apparatuses 1, 2 loaded with cation exchangers using one of the methods described above in order to obtain softened water.

The result is softened water with quality at the level of the required indicators (in examples 1-3, 5: hardness - not more than 0.01 mEq / dm ³ ; alkalinity - 0.34-0.4 mEq / dm ³ ) .

 After reaching the maximum permissible hardness in softened water, cation exchangers are regenerated with an acid solution. To do this, the acid solution is first passed through sulfocationite, and then through the carboxyl cationite (through apparatus 2, and then 1).

 An additional increase in the working capacity of cation exchangers in the H-filter at a lower acid consumption than stoichiometric for their regeneration is achieved by pretreating the carboxyl cation exchange resin in apparatus 1 with the acid spent regeneration solution of the H-filter of the previous regeneration operation (table, example 3). For this, the spent H-filter regeneration solution of the previous regeneration operation (stream D) is passed through the carboxyl cation exchange resin in apparatus 1, and then the cation exchangers are regenerated with acid in the manner described above. The acidic spent solution is collected in a container 4 and used for pretreatment of the carboxyl cation exchange resin during the next regeneration of the H-filter with acid.

 After passing the acid solution, the cation exchangers are washed in the same sequence with demineralized water. The regenerated ion exchangers are used in the next cycle of desalination and water softening.

 The hardness and alkalinity of water is determined by generally accepted methods / Handbook of an energy chemist. Under the general editorship of S.M. Gurvich. M .: Energy. -1972. T.1. S. 391-397 / [7], and the content of sodium ions - using a flame photometer.

 Examples of the implementation of the proposed method.

Example 1
The source water of the composition, mEq / dm ³ : hardness - 0.8; alkalinity - 0.8; strong acid anions - 2; sodium ions - 2 are sequentially passed through three columns (H- and OH-filters), regenerated after the previous cycle of water preparation. Columns contain: the first (column 1) - 60 cm ^{3 of} carboxyl cation exchanger Lewatit CNP 80; the second (column 2) - 50 cm ^{3 of} sulfonic cation exchanger KU 2-8, the third (column 3) - 47 cm ^{3 of} anionite AN-31. In demineralized water, the content of sodium ions is measured. Upon reaching the maximum permissible concentration of sodium ions (0.004 mEq / dm ³ , which is equivalent to 4 mcg eq / dm ³ ), the desalination of water is stopped. As a result, 18.5 dm ^{3 of} desalted water with a content of sodium ions of 0.004 mEq / dm ³ (4 mcg eq / dm ³ ) was obtained.

Cation exchangers pass the feed water through depleted water during desalination in order to obtain softened water. To do this, the source water is sequentially passed through column 1, and then through column 2. In softened water, the hardness value is controlled. The transmission of water through columns 1 and 2 is stopped when the specified maximum permissible stiffness of the filtrate is reached (0.01 mEq / dm ³ ).

Then the OH filter (column 3) is regenerated with 75 mEq sodium hydroxide (GOST 4328-77) dissolved in 0.1 dm ^{3 of} demineralized water and 1 dm ^{3 of} demineralized water is washed. The total cost of demineralized water for the regeneration of anion exchange resin was 1.1 dm ³ . Get the spent regeneration solution with a volume of 1.1 DM ³ (stream A).

The spent regeneration solution of column 3 with a volume of 1.1 dm ³ (stream A) is successively passed through columns 1 and 2. Then columns 1 and 2 in the same order wash 1 dm ^{3 of the} source water.

Columns 1 and 2, processed by the spent regeneration solution of the OH filter and washed with the source water, continue to pass the source water sequentially in order to obtain softened water. In softened water control the amount of hardness. The transmission of water through columns 1 and 2 is stopped when the specified maximum permissible stiffness of the filtrate is reached (0.01 mEq / dm ³ ).

During the filter cycle received 235 dm ³ softened water with the following indicators: hardness - 0.01 mEq / dm ³ ; alkalinity - 0.39 mEq / dm ³ . The relative alkalinity of softened water is [0.39 / (0.39 + 2)] · 100 = 16%.

The H-filter is regenerated by passing a solution containing 187 mEq of sulfuric acid (GOST 4207-77), first through column 2 with sulfocationite, and then through column 1 with carboxylic ion exchanger. After passing the acid solution, the cation exchangers are washed in the same sequence with demineralized water. For the preparation of a solution of sulfuric acid and the washing of cation exchangers, 1.6 dm ^{3 of} demineralized water was spent. The regenerated H- and OH-filters are used to prepare water in the next cycle identical to the described example.

As a result, the following was obtained for the working cycle (minus the costs of regeneration of H and OH filters): demineralized water — 15.8 dm ³ ; softened water - 235 dm ³ ; total - 250.8 dm ³ . The ratio of the volume of produced water to the volume of ion exchangers is 250.8 / (0.05 + 0.060 + 0.047) = 1600. The consumption of sulfuric acid to remove 1 equiv of hardness ions was 187 / [(0.8-0.01) · 250.8] = 0.95, i.e. less stoichiometric. The working capacity of cation exchangers for stiffness ions in the H filter is (0.8-0.01) · 250.8 / (0.06 + 0.05) = 1800 mEq / dm ^{3 of} the H filter load (columns 1 and 2) (table, example 1).

Identical to the above example, the following water treatment cycle was carried out. As a result, the following indicators of the proposed method. Received water, dm ³ : desalted - 15.9; softened - 236. In total - 251.9 dm ³ . The ratio of the volume of produced water to the volume of ion exchangers is 251.9 / (0.05 + 0.06 + 0.047) = 1600. The content of sodium ions in demineralized water is 0.004 mEq / dm ³ (4 mcg eq / dm ³ ). Quality indicators of softened water: hardness - 0.01 mEq / dm ³ ; alkalinity - 0.4 mEq / dm ³ . The relative alkalinity of softened water is [0.4 / (0.4 + 2)] · 100 = 17%. The consumption of sulfuric acid to remove 1 equiv of hardness ions was 187 / [(0.8-0.01) · 251.9] = 0.94, ie, less than the stoichiometric. The working capacity of cation exchangers for hardness ions in the H filter is (0.8-0.01) · 251.9) / (0.06 + 0.05) = 1800 mEq / dm ³ .

Example 2
The treatment of the same source water and ion exchangers is carried out identically to Example 1, except for the stage of obtaining softened water, where the source water is treated by passing through carboxyl and sulfocationite not sequentially, but in parallel streams. To obtain softened water, the initial water is divided into two streams, B and C. Stream B is passed through column 1 with carboxylic cation exchanger, and stream C is passed through column 2 with carboxylic cation exchange resin, after which flows B and C are mixed and softened water is obtained.

As a result, the following was obtained for the working cycle (minus the costs of regeneration of H- and OH-filters): demineralized water — 15.7 dm ³ ; softened water - 230 dm ³ . In total - 245.7 dm ³ . The ratio of the volume of produced water to the volume of ion exchangers is 245.7 / (0.05 + 0.06 + 0.047) = 1570. The content of sodium ions in demineralized water is 4 μg-eq / dm ³ . The hardness of the softened water is 0.01 mEq / dm ³ . The alkalinity of softened water is 0.38 mEq / dm ³ . The relative alkalinity of softened water is [0.38 / (0.38 + 2)] · 100 = 16%. Spent 187 mEq of sulfuric acid. The consumption of sulfuric acid to remove 1 equiv of hardness ions was 187 / [(0.8-0.01) · 245.7] = 0.96, i.e. less stoichiometric. The working capacity of cation exchangers for stiffness ions in the H-filter is (0.8-0.01) · 245.7 / (0.06 + 0.05) = 1770 mEq / dm ^{3 of} the H-filter load (columns 1 and 2) (table, example 2).

Example 3
The treatment of the same source water and ion exchangers is carried out identically to Example 1 except for the regeneration step of the cation exchangers used in water softening with acid. After the preparation of softened water is completed, the carboxyl cation exchanger in column 1 is treated with 1.6 dm ^{3 of the} spent regeneration solution of the previous H-filter regeneration containing 131 mEq sulfuric acid. Then the H-filter is regenerated by passing a solution containing 233 mEq sulfuric acid (GOST 4207-77), first through column 2 with sulfocationite, and then through column 1 with carboxylic ion exchanger. After passing the acid solution, the cation exchangers are washed in the same sequence with demineralized water. The result is 1.6 dm ^{3 of an} spent solution containing 132 mEq of sulfuric acid, which is used to treat carboxylic cation exchange resin in the next H-filter regeneration operation with acid. For the preparation of a solution of sulfuric acid and the washing of cation exchangers, 1.6 dm ^{3 of} demineralized water was spent. The regenerated H- and OH-filters are used to prepare water in the next cycle identical to the described example.

As a result, the following was obtained for the working cycle (minus the costs of regeneration of H- and OH-filters): demineralized water — 15.5 dm ³ ; softened water - 306 dm ³ . In total - 321.5 dm ³ . The ratio of the volume of produced water to the volume of ion exchangers is 321.5 / (0.05 + 0.06 + 0.047) = 2050. The content of sodium ions in demineralized water is 4 μg-eq / dm ³ . The hardness of the softened water is 0.01 mEq / dm ³ . The alkalinity of softened water is 0.34 mEq / dm ³ . The relative alkalinity of softened water is [0.34 / (0.34 + 2)] · 100 = 14%. Spent 232 mEq of sulfuric acid. The consumption of sulfuric acid to remove 1 equiv of hardness ions was 321.5 / [(0.8-0.01) · 308.3] = 0.91, i.e. less stoichiometric. The working capacity of cation exchangers for stiffness ions in the H filter is (0.8-0.01) · 321.5 / (0.06 + 0.05) = 2320 mEq / dm ^{3 of} the H filter load (columns 1 and 2) (table, example 3).

When preparing the same source water according to the known method [3], the following results were obtained. Received water, dm ³ : desalted - 12.9; softened - 30. In total - 42.9 dm ³ . The ratio of the volume of produced water to the volume of ion exchangers is 42.9 / (0.05 + 0.03) = 535. The sodium content in demineralized water is 0.32 mEq / dm ³ . Quality indicators of softened water: hardness - 0.01 mEq / dm ³ ; alkalinity - 0.74 mEq / dm ³ . The relative alkalinity of softened water is [0.74 / (0.74 + 2)] · 100 = 27%.

Spent, mEq: sulfuric acid - 35. The consumption of sulfuric acid to remove 1 equiv of hardness ions was 35 / [(0.8-0.01) · 42.9] = 1.03. The working capacity of the cation exchanger for stiffness ions in the H-filter is (0.8-0.01) · 42.9 / 0.05 = 680 mEq / dm ³ (table, example 4).

In order to establish the comparative effectiveness of the proposed and known [3] methods for producing desalinated and softened water from source water with constant hardness (composition, mEq / dm ³ : hardness - 1.8; alkalinity - 0.8; anions of strong acids - 2; sodium ions - 1) experiments were carried out identically to the examples described above. The results are shown in the table (examples 5 and 6).

The advantages of the proposed method compared to the known [3] are confirmed by examples of their implementation (table, examples 1-6). Using the proposed method can improve the quality of both demineralized and softened water: demineralized by reducing the content of sodium ions from 320 to 4 μg-eq / dm ³ (80 times); softened - by reducing alkalinity from 0.62 - 0.74 to 0.34 - 0.4 mEq / dm ³ , as a result of which softened water is brought into compliance with the requirements [5] for water intended for use as for feeding the heating system and low-pressure steam boilers. In this case, deep water softening is achieved (residual hardness 0.01 mEq / dm ³ ) and less than the stoichiometric consumption of sulfuric acid for H-filter regeneration (0.84 - 0.96 eq / eq of absorbed hardness ions).

It should be noted that the application of the proposed method provides a significant increase in the working capacity of the H-filter loading by stiffness ions: from 650 - 680 to 1670 - 2320 mEq / dm ³ (2.6 - 3.4 times). This leads to an increase in the total production of desalinated and softened water per unit volume of ion exchangers 2.6-3.8 times.

Claims (2)

 1. A method of preparing water, including desalting the source water on H and OH filters, softening the source water on H filters depleted during desalination, alkali regeneration of OH filters, treatment of the treated H filters with a spent regeneration solution of OH filters and their regeneration with acid characterized in that the carboxyl cation exchanger and sulfocationite are used as the H-filter load, and desalination is carried out by sequentially passing the initial water through the carboxylation cationite and sulfocationite, softening is carried out They are caused by sequential or parallel transmission of water through carboxylic cation exchange resin and sulfocationite in two stages: in the first stage, water is passed through cation exchangers depleted by desalination of water until the hardness ions break through through sulfocationite, and in the second stage, water is passed through the same cation exchangers treated additionally with spent with a regeneration solution of OH filters by passing the latter sequentially through carboxyl cation exchange resin and sulfocationite, and H filters are subjected to regeneration; they are softened by passing the acid sequentially through sulfocationite and carboxylic cationite.  2. The method according to claim 1, characterized in that during the regeneration of the H-filters with acid, the carboxyl cation exchange resin is pre-treated with the treated regeneration solution of the H-filters of the previous regeneration operation.

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