Thermal Power · Boiler Make-up Water
Shaanxi Coal Chemical Xiantao Clean Energy Power Plant Demineralized Water System
A two-phase demineralized water system using two-pass RO + EDI: phase 1 at 30 m³/h × 2 (132 elements) and phase 2 at 40 m³/h × 2 (232 elements), with permeate conductivity held steady at 8 μS/cm. Accepted in August 2023.
Thermal PowerTwo-Pass RO + EDIBoiler Make-up WaterTwo-Phase Build
8Permeate conductivity μS/cm
132 / 232Elements in two phases
43Phase 2 system output m³/h
24hContinuous operation
01
Project Overview
Client, scale, feed water and project background
The demineralized water preparation system at the power plant of Shaanxi Coal Chemical Xiantao Clean Energy Co., Ltd. supplies boiler make-up water, with a mixed feed of groundwater and tap water. The project was built in two phases: phase 1 at 30 m³/h × 2 with 132 elements (36 × 2 first pass, 30 × 2 second pass); phase 2 at 40 m³/h × 2 with 232 elements (74 × 2 first pass, 42 × 2 second pass).
The process is groundwater → pretreatment → first-pass RO → second-pass RO → EDI, a two-pass RO plus electrodeionization route whose product water goes directly to boiler make-up, operating 24 hours a day continuously. With a mixed groundwater and tap water feed, a reducing agent and an antiscalant are dosed to control residual chlorine and scaling risk.
Both phases were contracted on 4 August 2023; installation started on 14 August and was completed on 16 August, with operation qualified and acceptance organized on 17 August. Permeate conductivity held steady at 8 μS/cm, system output reached 30 m³/h and 43 m³/h respectively, operation was good with no abnormalities, and the owner signed off.
- Client
- Shaanxi Coal Chemical Xiantao Clean Energy Co., Ltd.
- Location
- Xiantao, Hubei Province
- Project type
- Power plant demineralized water preparation system (two phases)
- System scale
- Phase 1 30 m³/h × 2; Phase 2 40 m³/h × 2
- Feed water
- Mixed groundwater and tap water
- Product water use
- Boiler make-up water
- Membrane elements
- QC-LP-8040-400 (132 in phase 1; 232 in phase 2)
- Acceptance date
- 17 August 2023
02
Process Design
System flow, design boundaries and key control points
01Groundwater / tap water
→02Pretreatment (multi-media + cartridge filtration)
→03Reducing agent / antiscalant
→04First-pass RO
05Second-pass RO
→06EDI
→07Demineralized tank
→08Boiler make-up water
Two-pass RO brings permeate conductivity down to a level EDI can accept; EDI then provides continuous polishing demineralization without acid or caustic regeneration, suiting continuous power plant operation.
Progressive scaling across two phases
Phase 1 at 30 m³/h × 2 met initial unit demand and phase 2 expanded to 40 m³/h × 2, with elements rising from 132 to 232, avoiding an oversized one-off investment.
Two-pass RO combined with EDI
The first and second RO passes share the desalination load in stages, so EDI only treats low-conductivity feed, making module life and product resistivity more stable.
Dual dosing of reducing agent and antiscalant
For residual chlorine and hardness in groundwater, a reducing agent protects the polyamide membrane while an antiscalant controls concentrate-side scaling.
Permeate conductivity as the core control indicator
System rejection is not assessed separately; permeate conductivity of 8 μS/cm is the core control indicator, directly corresponding to boiler make-up water quality.
03
Key Equipment & Membrane Configuration
Membrane models, loading arrangement and auxiliary equipment
| Phase | System scale | Membrane configuration | System output | Permeate conductivity |
|---|---|---|---|---|
| Phase 1 | 30 m³/h × 2 | 132 elements (36 × 2 first pass, 30 × 2 second pass) | 30 m³/h | 8 μS/cm |
| Phase 2 | 40 m³/h × 2 | 232 elements (74 × 2 first pass, 42 × 2 second pass) | 43 m³/h | 8 μS/cm |
Membrane model QC-LP-8040-400; both phases use two-pass RO + EDI and operate 24 hours continuously.
04
Operating & Acceptance Data
Field measurements versus contractual guarantee values
| Item | Phase 1 | Phase 2 |
|---|---|---|
| Contract signed | 2023-08-04 | 2023-08-04 |
| Installation started | 2023-08-14 | 2023-08-14 |
| Installation completed | 2023-08-16 | 2023-08-16 |
| Acceptance date | 2023-08-17 | 2023-08-17 |
| System permeate flow | 30 m³/h | 43 m³/h |
| Permeate conductivity | 8 μS/cm | 8 μS/cm |
| Operating status | Good, no abnormalities | Good, no abnormalities |
Both phases were installed and accepted within 12 days of contract signing, with permeate conductivity steady at 8 μS/cm. Per the owner's requirement, system rejection is not assessed separately; permeate conductivity is the acceptance criterion.
05
Project Results
Client acceptance conclusions and reusable engineering experience
✓
Both phases delivered quickly
Only 13 days from contract signing to acceptance, meeting the power plant's boiler make-up water commissioning milestone.
✓
Stable product water quality
Permeate conductivity of 8 μS/cm satisfies boiler make-up requirements over the long term, with no abnormal system operation.
✓
Expansion without changing the process framework
Phase 2 scaled the membrane configuration proportionally on the phase 1 process basis, reducing duplicated design and spare part variety.
✓
A standard configuration for power plant demineralized water
Two-pass RO + EDI together with the dual dosing strategy can serve as the reference configuration for comparable power plant demineralized water systems.
