Knowledge base
A plate heat exchanger works for years with almost no attention if its liquids are clean, and loses performance quickly if they are not. The narrow channels that make it so efficient are also where deposits build up. This guide explains what fouls a plate exchanger, how to recognise it, how the different types are cleaned and what keeps the problem away.
What Fouls A Plate Exchanger
Four kinds of deposit are common. Scale forms from hard water on the warm plates. Particles - rust, sand, fibre - settle in the channels. Biological growth, slime and algae, builds up in warm open water. And corrosion products, from steel parts elsewhere in the circuit, travel to the exchanger and settle on the plates. Any of them narrows the channel, insulates the plate and cuts the heat transfer.
How To Recognise It
The signs are the two the operators watch: the temperatures stop reaching their targets, and the pressure drop across the exchanger rises. A gradual change over months is normal ageing of a fouling circuit; a sudden change points to a blockage or a failed upstream filter. Keeping a record of the temperatures and pressure drops at a known load makes any change visible long before the plant complains.
How Each Type Is Cleaned
A gasketed exchanger is opened: the plates are separated, cleaned with brushes and water, or chemically, and the gaskets are inspected and replaced if they are worn. A brazed exchanger cannot be opened and is cleaned by circulating a cleaning liquid through it, and a badly fouled unit is replaced. Welded designs depend on the construction: some can be opened on one side, others are cleaned by circulation. Whatever the type, cleaning liquids must suit the plate material, or the cure will do the damage.
Keeping It Clean
Prevention is cheaper than cleaning. A strainer or filter upstream keeps the channels clear of particles; water treatment keeps scale and growth down; and a closed, well-filled circuit keeps air and corrosion products out. Regular inspection of gaskets, a log of performance and a plan for opening or flushing the unit at intervals complete the picture. TECS Engineering designs and delivers plate heat exchanger solutions for engine, power plant and industrial cooling circuits; send the fluids and the conditions and the engineering team will answer.
In Short
- Scale, particles, biological growth and corrosion products foul the plates
- Warning signs: temperatures not reached, pressure drop rising
- Gasketed units are opened; brazed units are flushed; welded depends on the design
- Cleaning liquids must suit the plate material
- Strainers, water treatment and a closed circuit prevent most fouling
- Keep a performance record and inspect the gaskets
What To Send With An Enquiry
- The fluids and their quality, including any open circuit
- Whether the circuit is closed and treated
- Cleaning access needed and how often cleaning is expected
- Material of the rest of the circuit
- Filtration already fitted
- Site conditions and available space for service
Questions We Are Often Asked
How do I know a plate heat exchanger is fouled?
The temperatures no longer reach their targets and the pressure drop across the unit rises, compared with the record at the same load.
Can every plate heat exchanger be opened for cleaning?
Only the gasketed type. Brazed units are cleaned by circulating a liquid through them, and welded ones depend on the design.
What fouls them most often?
Scale from hard water, particles and biological growth in open circuits.
How can fouling be prevented?
With a strainer or filter upstream, water treatment and a closed, well-filled circuit.
Does cleaning damage the plates?
It can, if the cleaning liquid does not suit the plate material or the gaskets, so the liquid and the method are chosen for the unit.
Contact Us
Send us the heat duty, the fluid temperatures and flow rates, the ambient conditions and the installation limits. We answer with a design proposal - or write to us on WhatsApp.
