1. High-Purity Water Standards for Industrial Steam Boilers
High-pressure industrial steam boilers operate under extreme thermodynamic conditions where even micro-gram quantities of dissolved minerals, silica, or dissolved gases cause severe operational hazards. Scale accumulation of just 1 mm on boiler firetubes can decrease thermal efficiency by 15% and trigger catastrophic tube failures due to localized overheating.
Demineralized (DM) water production aims to strip all ionized minerals from raw water, achieving electrical conductivity values under 0.1 µS/cm and silica concentrations under 0.01 ppm (10 ppb).
2. Ultrafiltration (UF) as Advanced Pre-Treatment
Replacing traditional media filters with hollow-fiber Ultrafiltration (UF) modules revolutionized DM plant reliability. With nominal pore sizes around 0.01 to 0.02 microns, UF provides an absolute physical barrier against colloidal silica, suspended solids, bacteria, and macro-molecules.
By consistently delivering feed water with a Silt Density Index (SDI 15) below 1.5, UF pre-treatment protects downstream ion exchange resins and reverse osmosis membranes from mechanical fouling, reducing chemical consumption during resin regeneration cycles by over 30%.
3. Ion Exchange Technology: Cation, Anion & Mixed Bed Polishing
Demineralization employs synthetic ion-exchange resin beads engineered with specific chemical functional groups:
- Strong Acid Cation (SAC) Exchanger: Replaces metallic cations (Ca2+, Mg2+, Na+, K+) with Hydrogen ions (H+), generating acidic water.
- Degasifier Tower: Strips liberated carbonic acid (H2CO3) as Carbon Dioxide gas (CO2) using counter-current air blowing, reducing downstream anion resin load.
- Strong Base Anion (SBA) Exchanger: Replaces anions (Cl-, SO42-, NO3-, SiO32-) with Hydroxide ions (OH-). Recombined H+ and OH- ions form pure H2O molecules.
- Mixed Bed (MB) Polisher: Intimately mixes SAC and SBA resins in a single vessel to perform micro-polishing, delivering boiler feedwater with resistivity up to 18.2 Megohm-cm.
4. Continuous Electrodeionization (EDI): The Chemical-Free Future
Modern CODEX DM plants increasingly integrate Electro-Deionization (EDI). EDI combines ion-exchange membranes, resin media, and a direct current (DC) electrical field to continuously regenerate resins without handling hazardous liquid acid (HCl) or caustic (NaOH) chemicals. This eliminates chemical handling risks, effluent neutralization costs, and batch downtime.