Dry Exhaust Gas Cleaning System

By Keith Henderson at November 18, 2010 08:12
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MAN Diesel & Turbo recently signed a cooperation agreement with the German company Couple Systems to jointly develop customer solutions for dry scrubbing technology. Couple Systems developed and patented DryEGCS®, an exhaust dry scrubbing system suitable for marine applications and following successful completion of wide-ranging field tests, in April of this year DryEGCS® was certified by Germanischer Lloyd.

The solution is aimed at offering integrated systems to enable ships to continue to operate on HFO while complying with the SOx and NOx emission regulations applicable in the different parts of the world.

Couple Systems dry system claims to be a world first as until now only wet scrubbing systems have been available. Building on experience gained in similar dry systems used in power generation applications, the DryEGCS® system comprises distinct two parts.

Exhaust gas directly downstream from the turbocharger is passed through Stage One, comprising an absorber with a bed of Calcium Hydroxide Ca(OH)2 (lime) granulated pellets. The sulfurous SO2 and SO3 gases in the hot (240-350 deg C) exhaust gas reacts with the lime to produce CaSO4, commonly known as gypsum.

If required, the granular pellets of the first stage can be discharged more quickly allowing the absorber to simultaneously take on the function of a diesel particle precipitator.

The relatively high temperature of the decontaminated exhaust gases passing into the SCR Stage Two of the process allows a smaller catalyst to be used. The SCR converts the NOx gases into harmless  nitrogen and water vapour..

The active agents of the system are inexpensive and freely available. The system includes a simple handling system that can be connected up by tube to a truck alongside the quay. Replenishment and removal of the agents is achieved by the same truck discharging and loading the agents.

The system provides a possible solution that will enable ships to operate economically on HFO and simultaneously comply with even the most stringent emission regulations.


Simplified illustration of an MAN Diesel & Turbo engine with a DryEGCS system. Credit: MAN Diesel & Turbo

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