The laboratory ship "Max Prüss" – owned by CLINSH partner LANUV NRW - was retrofitted in October 2015 with an SCRT exhaust gas retrofit system on both main engines. The measurements - now available as a report in English, Dutch and German -  were carried out in November 2018 in cooperation with the technical service of "TÜV-Nord Mobilität GmbH & Co KG".

Check and evaluate
The aim of the measurements was to check and evaluate the effectiveness of the exhaust gas retrofit system by measuring gaseous pollutant emissions and soot as well as particle emissions, using very high-quality measuring technology. The investigation concept provides for measurements of the emissions in real operation of the ship. By measuring at four load points, a result comparable to an E3 test of ISO 8178, as prescribed for inland navigation engines, had been achieved. The measurement campaign also offered the opportunity to validate the continuous monitoring system installed within the CLINSH project.

Measurements
The measurement concept provides for a simultaneous measurement of gaseous emissions before and after exhaust after treatment. In addition, gravimetric particle measurements and soot measurements are carried out with a photoacoustic aerosol sensor. As the measurement technology is only readily available, these surveys are carried out in separate measurement campaigns before and after exhaust gas after treatment.

Results
The results show good reduction rates in all measuring points for all limited pollutants. For the leading components nitrogen oxide are between 66% and 96%. An exception is the lowest measuring point (low speed, e.g. during mooring manoeuvres). Here the injection of the reagent is stopped due to insufficient exhaust gas temperatures. The reduction rate then drops to 6.6% during the measuring period. Since higher speeds are generally used in normal operation, the effect on the reduction of total emissions remains low, however.

For soot, reduction rates of 97.7% to 99.8% are achieved, while particulate emissions are reduced by 77.8% to 96.7%. For hydrocarbon compounds, reduction rates of between 81.0% and 97.3% were achieved. For carbon monoxide the reduction rates vary between 31.6% and 62.5%. When considering NO2 direct emissions, reduction rates of 9.6% to 49.3% can be observed in the first three load points. At the last measuring point (lowest speed), there is a very significant increase in the NO2 content of the exhaust gas due to the low exhaust gas temperature and the resulting stop of the reagent supply. 

Reduction rates after application of the calculation methods for the E-3 cycle according to ISO 8178
 

Validation after system installation
An obvious NH3 breakdown or slip of the exhaust system could be detected during the measurement. The NH3 slip was minimized during the measuring run by readjusting the system for the "Max Prüss".

Second, there is a measurement uncertainty due to in homogeneities in the exhaust gas flow after exhaust after treatment. Therefore, it must be checked whether the sensor for continuous monitoring is installed in such a way that a preferably homogeneous exhaust gas flow is recorded.

For a high quality of the continuous monitoring data, a validation after system installation with the help of suitable measurement technology seems to be absolutely necessary to minimize the risk of incorrect measurements during continuous monitoring.