Demineralisation plants (DM-plants)

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Demineralisation plants (DM-plants)

Demineralisation plants produce demineralised water of highest quality

• easy to use
• fully automatic 2-column units
• automatic regeneration
• automatic chemical feed
• suitable for the circulation of rinse water
  
  

Figure: Decker Demineralisation plant

Demineralisation

With demineralisation by ion exchange dissolved salts are removed from the untreated water
Due to destructive effects of high alkalinity and salt concentration in the most industrial processes the content of dissolved salts in the process water has normally to be reduced.

The 2-column principle

The unit consists of a column with strongly acid cation exchange resins followed by a column with strongly alkaline anion exchange resins, regenerated with hydrochloric acid resp. sodium hydroxide. During passage through the columns, the salts dissolved in the raw water are exchanged with hydrogen and hydroxyl ions, forming water together.

Design of the installation

The installation consists of two polyethylene covered filter tanks with ion exchange materials. The connecting pipe system is made of PVC with manually operated drain and rinsing valves. The tank is also equipped with a 4-cycle-valve for the regeneration. The conductivity of the demineralised water can also be read on a measuring device in the range of 0 – 50 µS.

Regeneration

When the plant capacity is exhausted, it is regenerated with hydrochloric acid and sodium hydroxide. The programmed regeneration is initiated and consists of the following cycles: Backwash, draw of acid and sodium hydroxide, rinse. The regeneration takes approx. 2 hours.

Operation

The conductivity of the demineralised water increases at the end of an operating phase and the unit is switched off by closing the drain valve. Then regeneration is started by pressing the start button. When regeneration is completed the unit is rinsed in order to achieve the required water quality.

Storage tanks for acid and sodium hydroxide

Acid and sodium hydroxide can directly be aspired from the original containers. If requested, the plant may be delivered with special polyethylene storage tanks.

Circulation

Very low flow per minute or standstill can cause an increase in the conductivity and thereby unnecessary regenerations. The installation can be supplied with a circulation pump, eliminating this problem.

Plant capacity

The basic capacity is valid for ordinary clean waterworks water with a moderate salt content, and states the quantity of water – with a total salt content equivalent to one degree of German Hardness (1°GH) – which can be demineralised per regeneration. The actual capacity between the regenerations is found by dividing the basic capacity of the installation by the ion content in the raw water, measured in equivalent hardness.

Water quality

The conductivity of the demineralised water is normally between 5 and 30 microsiemens. This quality is satisfactory for most industrial processes. If a higher quality is required, the plant can be combined with a mixed-bed exchange unit.

Installation

Pay attention to local regulations.
Pipe works for demineralised water as well as drain valves have to be made of PVC, acid resistant and stainless steel etc.

Drain water neutralization

For the neutralization of the acid and alkaline waste waters of the plant we can offer several solutions.

Application

Beside the production of demineralised water these units are especially suited for the circulation of rinse water.

Figure: Decker demineralisation plant engeneering drawing

Specifications

Operating pressure: 2-6 bar. untreated water temperature: max. 35°C, however lower with certain fillings in use. Power connection: 220/12V, 50 Hz.

*1°dH corresponds 2,8 mval/l

Decker Verfahrenstechnik GmbH
Bruckaecker 12, 92348 Berg/Opf., Germany
Web: http://www.decker-vt.de E-Mail: info@decker-vt.de
Phone: +49 (0)9189/4410-0 Fax: +49 (0)9189/4410-20

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