To help it ensure its engines meet these strict emissions standards, the world’s largest producer of marine diesel engines has adopted the highly accurate ABB AZ10 Zirconia combustion oxygen analyzer.
To meet the stricter emissions limits, the engine manufacturer needed to ensure the efficiency of the Exhaust Gas Reduction (EGR) system used by its two-stroke engines. This takes a proportion of the exhaust and mixes it with carbon dioxide (CO2), feeding it back to the air inlet. With a higher heat capacity than oxygen (O2), the CO2 reduces the peak engine temperature, leading to a reduction in the formation of NOx.
In a series of experiments, the marine diesel engine manufacturer found that mixing the exhaust air with the inlet air can reduce the oxygen inlet percentage by roughly 3-6% percent, rather than natural air’s 21 percent, reduced NOx production by 85 percent.
For maximum emissions reduction, the key to managing this oxygen intake is highly accurate measurement. Beyond this the instrument also needed a low response time and the company were keen to find a solution which would reduce the use of expensive gases for calibration.
In comparisons between devices supplied by the major vendors, the ABB AZ10 achieved an accuracy better than ±0.05 percent of the actual O2 level.
The device’s use of low-drift sensor technology means that it experiences a drift of only 1.0 percent O2 per month, compared to other vendors’ drift of 2 percent O2 per month.