2026-10-31
A 600 MW Combined Cycle Gas Turbine (CCGT) cogeneration power plant in the Rayong Industrial Zone, Thailand, operates a closed-loop condensate recovery system returning 1,200 m³/h of condensed steam to heat recovery steam generators (HRSG). To eliminate ionic contaminants and silica carryover, the returned condensate passes through a pre-clarification process featuring a double-pass Reverse Osmosis (RO) condensate polishing system followed by electrodeionization (EDI).
Condensate return water temperatures fluctuate between 45°C and 65°C, containing fine colloidal silica ($SiO_2$), particulate hematite ($Fe_2O_3$), and trace lubricant oil. The plant's original string-wound cartridge pre-filters allowed fine hematite particulates ($2\text{--}10\,\mu\text{m}$) and silica micro-flocs to slip through screen gaps. These contaminants deposited directly onto the primary RO membrane surfaces, causing rapid membrane fouling, severe flux decline, and high feed pressure spikes. The plant operator partnered with LEFILTER to install a high-efficiency high-flow cartridge barrier to protect the RO membrane assets.
Rapid RO Membrane Foul Scaling: Particulate hematite and colloidal silica slipping through legacy string-wound elements coated RO membrane feed spacers. The Silt Density Index ($SDI_{15}$) of the RO feed water hovered between 4.2 and 5.8, far exceeding the RO manufacturer's limit ($SDI_{15} < 3.0$).
Frequent RO Chemical Cleaning (CIP) Cycles: Severe membrane fouling forced the plant to conduct aggressive Clean-In-Place (CIP) washings with caustic soda and citric acid every 12 to 14 days. Frequent CIP cycles shortened RO membrane life from 4 years to under 11 months.
Elevated High-Pressure Pump Energy Costs: As RO membranes fouled, the feed pressure required to maintain 1,200 m³/h output surged from 1.2 MPa to 2.1 MPa, increasing auxiliary power consumption on high-pressure pump drives.
Silica Carryover into HRSG Steam: Un-intercepted silica particulate bypass passed through fouled RO seals into the HRSG drum water, risking silica deposition on steam turbine blades and threatening turbine efficiency.
LEFILTER engineered a ultra-high-efficiency condensate polishing pre-filtration skid featuring two parallel LEFILTER HF-Series Stainless Steel Vessels housing 1 $\mu\text{m}$ absolute-rated high-flow pleated cartridges.
Micro-Denier Polypropylene Media: The filter elements utilize multi-layered micro-denier melt-blown polypropylene fibers with a graded-density pore structure. Coarse outer layers trap larger rust particles, while dense inner layers capture sub-micron silica and hematite particulates down to 1 $\mu\text{m}$.
Positive O-Ring Sealing Mechanism: Unlike standard elements relying on flat gasket compression (which can bypass under thermal stress), LEFILTER high-flow cartridges feature a dual-elastomer O-ring plug-in neck seal, ensuring zero bypass under differential pressure surges.
Absolute 1 $\mu\text{m}$ Filtration Efficiency ($\beta \ge 10,000$): Verified by laser particle counter testing, the 1 $\mu\text{m}$ absolute rating intercepts over 99.99% of particulate iron oxides and suspended silica, reducing feed water SDI dramatically.
High-Temperature Structural Stability: All cartridge components, including end caps, inner cores, outer cages, and media layers, are thermally bonded without adhesives, rated for continuous operation in hot 80°C condensate streams.
Turnkey Engineering Execution: LEFILTER executed vessel design, non-destructive weld testing, sea shipment to Laem Chabang Port, and deployed senior water treatment engineers for site installation, line flushing, and RO commissioning integration.
Following 16 months of continuous operation at the Rayong CCGT power plant, the LEFILTER high-flow RO protection skid achieved exceptional operational metrics:
RO Feed Water Quality Transformation: Feed water Silt Density Index ($SDI_{15}$) dropped from an average of 4.8 down to a clean 1.4 to 1.7, providing an ideal feed stream for downstream RO membranes.
RO Membrane CIP Frequency Reduction: RO membrane Chemical Clean-In-Place (CIP) intervals expanded from once every 14 days to over 140 days, reducing chemical usage by 90% and extending expected RO membrane lifespan to over 4.5 years.
Auxiliary Power Savings: Lower RO membrane fouling reduced high-pressure pump operating pressure by 0.7 MPa, saving over 185,000 kWh of auxiliary electrical power annually.
Elimination of Steam Turbine Silica Scaling: Particulate silica in the final RO permeate was held consistently below 2 ppb, eliminating silica scale deposits on HRSG boiler tubes and steam turbine blading.
Project Capital Amortization: Savings in RO membrane replacements, reduced CIP chemical purchasing, and lowered pump power consumption fully amortized the capital cost of the LEFILTER system within 5.2 months of startup.
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