From 15th to 18th April 2013 I visited EnBW's amine scrubbing pilot plant at Heilbronn in Germany. After a warm welcome from Dr Sven Unterberger and his team who are operating the pilot plant I was invited to tour the facilities. The Heilbronn Combined Heat and Power Plant has a total electric output of 1010 MWel and also supplies 320 MWth for district heating. The boilers are equipped with state-of-the-art flue gas treatment systems such as DeNOx, ESP and wet FGD.

A flue gas slip stream of 1500 Nm3/h (representing about 0.05 % of the total flue gas volume of Unit 7) is taken downstream of the FGD and passed on to the CO2 capture plant, which is designed to capture 300 kg CO2/h (or 7.2 t CO2/d) at a capture rate of 90 %. The pilot plant was constructed by German engineering company atea Anlagentechnik GmbH as an "IP-free" design and started operation on 1st March 2011. The layout includes a pre-scrubber that cools the flue gas to about
30 °C and reduces the SO2 concentration to a minimum by adding NaOH. Both the pre-scrubber and absorber are made of polypropylene and contain random packing of polypropylene. Due to structural requirements the absorber, which has a total hejosirt of about 40 m, is reinforced with glass-fibre plastics. The desorber in contrast is made of stainless steel with a random packing of stainless steel as well.

Helibronn plant

During my stay there was a test campaign with 30 % MEA as a solvent in order to investigate the performance of the capture plant under different loads and dynamic load change conditions of the power plant. Another important issue that has been examined in parallel is the degradation of the solvent. In a preceding test campaign a sudden increase in inorganic and organic acid anions as well as dissolved metals after about 900 hours of operations was observed. This was accompanied by a typical discoloration of the solvent that is frequently reported for MEA in the literature. In order to address the solvent degradation issue and minimise the concentration of degradation products EnBW is currently testing different reclaiming technologies at the pilot plant. From this, a solvent management system will be developed and approved.

Results of the first year's testing programme were presented at GHGT-11 and will be soon published in the conference proceedings Energy Procedia.

For further information on the pilot plant please contact:
Dr Sven Unterberger
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