Efficient emission control for ships: how does WESP support compliance?

Part of Valmet’s Marine Emission Control solutions offering, wet electrostatic precipitator (WESP) technology is a highly effective and energy-efficient way to remove harmful pollutants from ship smokestacks. It offers a way to comply with increasingly strict regulations aimed at reducing the environmental impact of shipping and pre-treat exhaust gases for carbon capture processes.

Valmet solutions for marine

The maritime industry is adopting a variety of technologies to support compliance with tightening emissions limits – including global targets set by the International Maritime Organization and local and regional targets defined by bodies such as the European Union.

How does WESP for ships work?

A WESP unit has the following elements:

  1. Inlet, where the particle-laden exhaust gas from the ship’s engine or scrubbers enters
  2. Quenching, which is needed to treat hot gases coming directly from the ship’s engines
  3. Gas distribution stage, which distributes the exhaust gas evenly across the collection tubes in the precipitation stage
  4. Precipitation stage, comprising multiple grounded collection electrodes and discharge electrodes; the gas is cleaned as it travels through the high-voltage field created by the electrodes
  5. Field flushing, which is used for periodic cleaning of the discharge and collection electrodes
  6. Outlet, from where the cleaned gas exits to the ship’s smokestack 

A transformer-rectifier is used to generate a very strong electrical field between the discharge electrodes and collection tubes. This creates a corona discharge on the electrodes, which charges the particles traveling through the collector tubes. 

These charged particles then migrate to the surface of the grounded collection tubes, and the cleaned gas exits to the stack. Particles and droplets that accumulate on the tube surfaces are removed by continuous draining and periodic washing.  

How much particulate matter can WESP remove?

Valmet’s pilot testing using a marine test engine and a combination of a scrubber and WESP demonstrated:

  • Particulate matter (PM) levels from the engine exhaust gas outlet were between 120 and 150 mg/m3 at different load points using HFO as fuel.
  • The reduction in the scrubber was between 30 and 40%.
  • After the scrubber and WESP, both the PM and black carbon levels were reduced to almost zero, reaching over 98.5% reduction in all tested operation points. 

What other emissions can WESP remove?

As well as particulate matter including black carbon, WESP is highly efficient at removing:

  • heavy metals,
  • acid mist (sulfuric acid), oil mist, and water mist (required pretreatment before carbon capture processes), and
  • visible emissions.

Find out more by watching our webinar

Take a closer look at Valmet’s WESP and other cutting-edge solutions for marine exhaust gas treatment by watching our on-demand webinar. 

What you’ll learn more about:

  1. How WESP works
  2. How much particulate matter WESP can remove
  3. What other emissions WESP can reduce significantly

Register to watch the webinar – hosted by Juha Jokiluoma, Product Technology Manager, Marine Solutions, Valmet – to learn more about how WESP can help you with regulatory compliance.

Sign up to watch the webinar recording now!
The WESP content begins at 18:53.

Forerunner in emission control to reach a cleaner environment

The Valmet Wet Electrostatic Precipitator (WESP) controls a wide range of emissions, including particulate matter and black carbon, heavy metals, acid mist, oil mist, and visible emissions, for a brighter future.

Reducing Black Carbon with Valmet Wet ESP for Marine

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Valmet’s Wet ESP removes over 99% of harmful ship emissions—delivering cleaner oceans, healthier lives, and a faster path to climate impact.

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