RU2655141C1 - Method of removing oxygen from water - Google Patents

Abstract

FIELD: heat-and-power engineering.

SUBSTANCE: invention can be used in heat-and-power engineering to protect heat exchange equipment, boilers, pipelines and other metal elements in electrical power generating plant, firerooms, industrial plants in the production of steam, obtaining hot water for water supply, obtaining desalted and softened water. To carry out the process, the raw water is filtered through low- and high-basic mesoporous anion exchange materials synthesized by modification of copolymers of styrene and divinyl benzene in sulfite form. Regeneration of waste anion exchange materials is carried out by successive processing with solutions of natron or alkali with transfer to the main form, and a solution of sodium bisulphite with concentration of 1–10 % is passed through ion exchanger.

EFFECT: with this processing of resin charge, effective persorption of the sulfite anions occurs, which doubles the oxygen ion capacitance, which is removed from the water; the method also provides for increasing the efficiency of the use of ion exchanger and minimizing the volume of liquid waste.

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Description

The invention relates to a power system in the field of protection of heat-exchange equipment, boilers, pipelines and other metal elements in power plants, boiler houses, industrial enterprises in the production of steam, producing hot water for water supply networks, obtaining demineralized and softened water to feed steam boilers. To implement the method, water is filtered through mesoporous anion exchangers synthesized upon modification of styrene-divinylbenzene copolymers in sulfite form before being fed to the boiler.

Most methods of deoxygenation of water are based on thermal and vacuum deaeration (Application for the invention of Russia No. 2002135791/15, IPC С02F 1/20, the date of publication of the application is 05.06.2006). According to this application, the desorption of dissolved gases is carried out first in a vacuum deaerator, and the deaerated water is diverted to the deaerator's storage tank at elevated temperatures.

The disadvantage of this method is the use of a vacuum installation and heat treatment, which significantly increases energy consumption in the preparation of water. In addition, the disadvantage is the use of overall equipment.

A known method of obtaining filter material and water deaeration, based on filtering water through a mixture of cateonite and anion exchange resin treated with iron compounds, alkali, sulfite and sodium thiosulfate (Ukrainian Patent No. 99903, MKP (2009) B01J 20/20, B01J 20/30, B01D 39/16, B03B 3/00, publication date - 03/10/2010).

The disadvantage of this method is the use of solutions of iron sulfate with a concentration of 5-10%, sodium thiosulfate, sodium sulfite and alkali in the processing of a mixture of cation exchange resin and anion exchange resin, which leads to the formation of large volumes of liquid waste that are difficult to dispose of. In addition, due to the filling of the pores of the ion-exchange material with iron (III) hydroxide during its use during dehydration of water and repeated regenerations, the absorption capacity of the ion exchanger for oxygen sharply decreases with an increase in the number of filter cycles. With 3 to 4 filter cycles, the capacity of the filter material for oxygen decreases by 3-5 times.

The closest in technical essence to the invention is a method for removing oxygen from water, based on filtering water that contains oxygen through a highly basic anion exchanger of a gel structure in a sulfite (SO ₃ ^2- ) form, where the regeneration of anion exchanger is carried out with a solution of sodium sulfite with a concentration not higher than 8 % (Patent No. 2217382, Russia, MKI ⁷ C02F 1/20, 1/42, publication date -27.11.2003).

The disadvantages of this method include the use of concentrated solutions of sodium sulfite during the regeneration of ion exchanger, which leads to the formation of significant volumes of liquid waste and significant losses of sodium sulfite, which is used in significant excess of stoichiometric amounts during regeneration. Such solutions are contaminated with desorbed chlorides or sulfates, and therefore unsuitable for reuse.

The basis of the invention is the task of increasing the efficiency of removing oxygen from water when filtering through anion exchange resin in sulfite form while reducing sulfite losses in the processes of regeneration of anion exchange resin, increasing the efficiency of its use and minimizing the volume of liquid waste in the processes of obtaining and regenerating filter material.

The problem is solved in that when receiving or regenerating the filter material, which is a low- or highly basic ion exchanger, is treated with a solution of soda or alkali with the transfer to the main form. Then, sodium bisulfite solution is passed through the ion exchanger. In this case, effective sorption of sulfite occurs due to the neutralization reaction without a significant excess of the reagent in the reactions (1, 2):

where P is the polymer residue of styrene and divinylbenzene.

With this treatment of the filter load, superequivalent sorption of sulfite anions occurs, which almost doubles the capacity of the ion exchanger in oxygen, which is removed from the water.

EXAMPLE 1 A column of sodium bisulfite at a flow rate of 2-5 cm ³ / min was passed through a column filled with a 50 cm ³ low-basic DOWEX Marathon WBA anion exchange resin converted into a 2% soda solution into the basic form. The output was controlled by the content of sulfite and pH of the medium. The solution was passed until the pH in it was reduced to 5.3. After that, the ion exchanger was washed with 1 dm ^{3 of} demineralized water. Subsequently, desalted water was filtered through anion exchange resin at a flow rate of 5-10 cm ³ / min, controlling the oxygen content in it at the inlet and outlet of the column. After a breakthrough of oxygen at a concentration of 1 mg / dm ^{3, the} anion exchange resin was regenerated by sequentially treating with a solution of soda and a solution of sodium bisulfite. The results are presented in the table.

Example 2. Through a column filled with highly basic anion exchange resin AB-17-8 with a volume of 50 cm ³ , converted with a 4% alkali solution into the basic form, a solution of sodium bisulfite was passed as described in Example 1. After the conversion of the anion exchange resin to a sulfite form, it was filtered through it tap water at a flow rate of 2-5 cm ³ / min, controlling the oxygen content. After a breakthrough of oxygen at a concentration of 1 mg / dm ^{3, the} anion exchange resin was regenerated by sequentially treating with a 4% alkali solution and sodium bisulfite solution. The results are presented in the table.

Claims (1)

The method of removing dissolved oxygen from water, based on filtering water that contains oxygen, through an ion exchanger with further regeneration, which is characterized in that low- and highly basic mesoporous anion exchangers in the SO ₃ ² -form are used as the ion exchanger, and spent anion exchangers are regenerated during their sequential treatment with solutions of alkali or soda and a solution of sodium bisulfite with concentrations of 1-10%.