Photoacoustic gas detector for the monitoring of sulfur dioxide content in ship emissions

Ship emissions heavily pollute marine ecosystems and are extremely detrimental to the health of humans in harbour areas. From 2020 on, the International Maritime Organization (IMO) is imposing tighter limits on global sulphur emissions. Although shipping companies can continue using heavy fuel oils, they are then obligated by international maritime law to install gas scrubbers for the purification of the exhaust gas. In addition, special exhaust gas measuring technology must be installed subsequent to the gas scrubber to detect the actually emitted SO2. We present the development of a low-cost, resonant photoacoustic (PA) gas detector for the monitoring of SO2 in marine vessels. A UV LED at 285 nm is used as light source in combination with a microphone as acoustic detector. In first experiments, we used acetone gas as a substitution for the harmful SO2 for sensor characterization. The results of the experiments show that SO2 concentrations between 0 and 111 ppm should be detectable with 2 ppm accuracy.