Demineralization filters

    Designation Operation concept Advantages

    Designation of.demineralization filters.

    Water coming from natural sources always contains soluble compounds of calcium and manganese. During heating they convert into insoluble ones and form a stable hydrocarbonate residual matter; this matter decreases heat-exchange efficiency and obstructs free liquid motion via pipelines. The demineralization equipment removes hardness salts from water flow and reduces their concentrations to acceptable levels which do not significantly impact on processes and which are safe in terms of drinking water consumption. 

    Equipment model range.

    Spc Promvodochistka ltd provides a wide range of filters and units intended for water treatment and removal of hardness salts:

    • Demineralization filters of y series with a range of capacities from 0.7 to 11 m3/h;
    • Demineralization filters of d-y series with a range of capacities from 0.7 to 3.5 m3/h;
    • Demineralization filters of c series with a range of capacities from 13.2 to 109.2 m3/h.

    Demineralization process flow diagrams (pfds) may be implemented in one-or two -stages depending on requirements set to the water quality. The first pfd is based on the use of filters of c or y series, the second pfd – on the use of filters of d-y series. Water hardness resulted from one-stage treatment is 0.05-0.1 mg-equ/l. Water hardness after two-stage treatment is 0.01 mg-equ/l.

    Design of continuous demineralization filters.

    An ion exchange filter simplified design includes the following elements:

    • Body;
    • Drainage & distribution system;
    • Active filter medium (ion exchange resin);
    • Wash vessel;
    • Control & monitoring module.

    Operation concept of demineralization filters.

    The filter cycle of operation includes two stages:

    • Filtration through an active filter medium;
    • Regeneration flushing.

    Sodium resins are most frequently used as an active filter medium. Such preferred selection is due to safety of reaction products and a regenerant (sodium chloride).
    During the filtration stage ion exchange between water flow and the filter medium takes place.
    As a result calcium and manganese are incorporated into the ion exchange resin structure displacing sodium from it. Hardness salt concentration in water sharply declines. They are replaced by sodium carbonates, sulphates and chlorides. Scale shall not be generated during further water heating.

    фильтр для умягчения воды установка умягчения воды
    Filtration mode Chemical flushing mode


    Direct flushing with the help of sodium chloride solution is performed during the filter medium regeneration. A reverse process takes place-hardness cations are washed off from resin and are replaced by sodium ions from the regeneration solution.
    In addition to sodium cation resins hydrogen cation resins may be used in continuous demineralization filters.

    In this case hydrogen ion plays a role of a displacing ion. Sulphuric acid is used for the purpose of regenerating; such acid imposes significant constraints on utilization and makes the process more complicated.

    Advantages of demineralization filters:

    • Simplicity and reliability of operation and maintenance;
    • Implementation of complex multistage pfds and their integration into existing water treatment circuits thanks to equipment modular design;
    • Possibility to arrange continuous demineralization process due to inclusion of parallel redundant circuits;
    • Full automation of operation;
    • Delivery of consumable reagents required for the equipment operation.

    Scope of application of demineralization filters.

    Demineralization filters аre mainly used in heat-exchanging technologies and equipment in which water plays a role of a heat carrier:
    • Boiler house heat-exchanging equipment;
    • Water heat-exchangers in hvac systems;
    • Reactors and pipelines with water heating.

    Design of.demineralization filters.

    Demineralization filter includes the following elements:
    • Body;
    • Distribution system;
    • Filling medium – ion exchange resin;
    • Wash vessel;
    • Control unit.
    Demineralization process flow diagrams (pfds) of equipment manufactured by spc promvodochistka ltd may be implemented in one (c and y series) or two (d-y series) stages.