Tons per Hour High-Pressure Boiler Feedwater Treatment - DA Process Design - Dual-Stage RO + EDI

I. Process Design

1. Overall Process Flow
   Raw water → Pretreatment System (Multi-medium Filtration + Activated Carbon Filtration + Security Filtration) → First-Stage RO System (85% recovery rate) → EDI System (90% recovery rate) → Polishing Mixed Bed System → Product Water Tank → Feed Pump → User End
2. Water Balance

• Raw water flow: 6.54 m³/h (Calculation basis: RO feedwater = 5 / 0.9 / 0.85 ≈ 6.54 m³/h)
• RO product water: 5.56 m³/h (recovery rate 85%)
• EDI product water: 5 m³/h (recovery rate 90%)
• Concentrate discharge: RO concentrate 0.98 m³/h, EDI concentrate 0.56 m³/h (partially reusable for RO feedwater)

II. Working Principles and Equipment Selection for Each Process Segment

1. Pretreatment System

• Function: Remove suspended solids, organic matter, residual chlorine, and hardness to protect RO membranes.
• Equipment Selection:
  • Multi-medium Filter: Quartz sand + anthracite, flow rate 7 m³/h, tank dimensions Φ800×2000 mm, power 0.5 kW (backwash pump).
  • Activated Carbon Filter: Coconut shell activated carbon, flow rate 7 m³/h, tank dimensions Φ800×2000 mm, power 0.5 kW (backwash pump).
  • Security Filter: 5 μm filter cartridge, flow rate 7 m³/h, housing dimensions Φ300×1000 mm.

2. First-Stage RO System

• Function: Remove more than 97% of salts and colloids.
• Equipment Selection:
  • High-Pressure Pump: Centrifugal pump, flow rate 6.54 m³/h, head 120 m, power 4 kW.
  • RO Membrane Array: 4040 anti-fouling membranes, single-stage 2 segments, 4:2:2 configuration.
  • Dosing System: Antiscalant (2 L/h, power 0.1 kW).

3. EDI System

• Function: Further desalination to achieve conductivity <0.1 μS/cm.
• Equipment Selection:
  • EDI Modules: 3 parallel modules (single module capacity 1.85 m³/h), dimensions 400×600×1200 mm, DC power 0.5 kW/module, total power 1.5 kW.
  • Booster Pump: Centrifugal pump, flow rate 5.56 m³/h, head 30 m, power 1.1 kW.

4. Polishing Mixed Bed System

• Function: Further removal of trace ions to ensure hydrogen conductivity <0.10 μS/cm.
• Equipment Selection:
  • Mixed Bed Vessel: Nuclear-grade ion exchange resin, tank dimensions Φ600×2000 mm, working cycle 30 days, regeneration pump power 0.75 kW.

III. Installed Power and Installation Dimensions

IV. Key Design Verification

1. Water Quality Compliance:
   • RO product water conductivity 56.8 μS/cm → EDI reduces to 0.1-0.2 μS/cm → Polishing mixed bed achieves final hydrogen conductivity <0.10 μS/cm.
   • Total iron is reduced to <0.01 mg/L through RO + EDI + polishing resin adsorption.
2. Equipment Compatibility:
   • High-pressure pump matches RO membrane array flow (6.54 m³/h), with a head of 120 m to meet RO operation requirements.
   • Parallel EDI module design ensures a product water flow of 5 m³/h, with a booster pump head of 30 m to ensure feedwater pressure.

V. Notes

• Energy Efficiency: EDI concentrate is reused for RO feedwater, achieving an overall system recovery rate >85%.
• Automation: PLC controls backwashing, regeneration, and dosing processes to minimize manual intervention.
• Safety Redundancy: Backup high-pressure pumps and EDI modules ensure continuous water supply.