Free Flow Plate Heat Exchanger

Original HEXNOVAS article

Free Flow Plate Heat Exchanger

Free Flow Plate Heat Exchanger

Design, Advantages and Applications in High-Fouling Industries. Free Flow Plate Heat Exchangers are engineered for high-viscosity fluids, fiber-containing media, and fouling-prone process streams. Compared with conventional chevron (herringbone) plates, Free Flow plates provide wide and open channels to reduce clogging risk while maintaining reliable heat transfer.

What Is a Free Flow Plate Heat Exchanger?

A Free Flow Plate Heat Exchanger is typically a gasketed plate heat exchanger or a semi-welded plate heat exchanger using a special plate geometry that:

• Creates wide flow channels (wide gap / wide channel designs) compatible with common wide-gap references such as ALFA LAVAL MA30S, MA30W, T20S, T35S, Wide Gap 100S / 200S / 300S
• Minimizes contact points
• Reduces turbulence intensity (to prevent rapid blockage)
• Allows solids and fibers to pass more easily

Best fit: sludge, wastewater, pulp & paper stock, fruit pulp, syrup, digestate, and other high-fouling media.

Typical Applications

Free Flow Plate Heat Exchangers are widely used in:

• Edible oil cooling and heating
• Pulp & paper industry (stock / fiber)
• Wastewater treatment and sludge heating
• Sugar processing (syrup / molasses)
• Biogas systems (digestate)
• Marine oil systems (viscous fluids)

Design Parameters to Consider

When selecting a Free Flow heat exchanger, engineers should evaluate:

• Fluid viscosity at operating temperature
• Solid particle size and concentration
• Fouling tendency
• Acceptable pressure drop
• Cleaning method (CIP or mechanical opening)

Note: incorrect material selection or underestimating fouling characteristics may lead to premature corrosion or pitting.

Why Free Flow Plate Heat Exchangers Matter

In high-fouling environments, the wrong plate pattern can dramatically shorten equipment lifetime. A Free Flow (wide gap) plate design helps maintain stable thermal performance, reduce downtime, and optimize lifecycle cost.

Free Flow Plate Heat Exchanger FAQ

Free Flow PHEs are suitable for dirty or particle-containing fluids, such as fruit pulp and juice with fibers, sugar syrup and molasses, wastewater and sludge, pulp and paper stock, biogas digestate, slurry with soft solids, and other high-viscosity liquids.

Free Flow prioritizes anti-clogging performance, while standard PHE maximizes compact heat transfer.

Channel gap determines allowable particle size. Typical guidance: 5 mm gap → particles up to ~3–4 mm; 8 mm gap → up to ~6 mm; 10–12 mm gap → soft solids and fibrous materials. Hard or abrasive particles require reinforcement and wear evaluation.

Typical handling: 2–5% suspended solids for standard cases; up to ~8–10% soft organic solids depending on viscosity and fiber behavior. Mineral solids or sand significantly increase wear and must be evaluated carefully.

Higher viscosity fluids require larger channel gaps, reduced flow velocity, increased heat transfer area, and optimized port diameter. For fluids above ~500 cP, calculations must account for reduced turbulence and heat transfer coefficient.

Compared to narrow-gap high-chevron plates, heat transfer coefficient may be slightly lower, but pressure drop is reduced and fouling resistance is significantly improved. In real dirty-service operation, overall long-term performance is often superior.

Common materials include 304 stainless steel, 316L stainless steel, titanium, SMO 254, and Hastelloy. Selection depends on chloride concentration, pH, temperature, and corrosion risk.

For gasketed Free Flow PHE, typical design pressure is 10–16 bar and maximum temperature up to ~180°C (depending on gasket). Higher pressure designs require reinforced frames and should be confirmed by model specification.

Cleaning methods include CIP (clean-in-place), manual opening with high-pressure washing, and chemical cleaning. Pressure drop monitoring is a primary indicator for when cleaning is needed.

Common industries include food & beverage, sugar, pulp & paper, wastewater treatment, biogas processing, and chemical processing where fouling or fibers are present.

Yes. Options may include mixed plate packs (Free Flow + standard plates), reinforced frame, special port sizes, double gasket systems, and hybrid configurations to improve application flexibility.