The wet electrostatic precipitator as a cause of mist formation-Results from the amine-based post-combustion capture pilot plant at Niederaussem

The investigation of emission formation mechanisms in particular for aerosol driven mist formation - and also the development and testing of emission reduction measures for amine based post-combustion capture are essential parts of the joint development programme of BASF, Linde and RWE Power at the postcombustion capture pilot plant at Niederaussem. During more than 28,000 operating hours with BASF's innovative capture technology OASE blue (R) several emission mitigation systems have been evaluated under real power plant conditions. A wet electrostatic precipitator (WESP) is often regarded as a suitable option to avoid mist formation. In contrast to this, our investigations have shown that the WESP can cause aerosol formation by increasing the number concentration of ultrafine particles/droplets in the flue gas. Our results also indicate that this highly negative, voltage-dependent effect cannot be explained by a measurable increase of the SO3 concentration downstream of the WESP at the entrance of the CO2 absorber. Varying concentrations of SO2 in the flue gas which can react to SO3 by ozone that is generated in the high-voltage field of the WESP does not verifiably influence the entrainment. Low emission levels can be achieved by a special pre-treatment of the flue gas and by the so-called Dry Bed configuration. (C) 2015 Elsevier Ltd. All rights reserved.