The information on the trace gases including nitrogen and sulphur species is essential for environmental concerns and downstream utilization of coal-derived syngas. The emission of nitrogen and sulphur species from two low rank coals (Maddingley and Yallourn coal using an entrained flow reactor were investigated under two different atmospheres: pyrolysis and CO₂ gasification. The gaseous nitrogen compounds (HCN and NH₃) and sulphur pollutants (H₂S and COS) during pyrolysis and gasification were measured. The effects of temperature (1000-1400°C), CO₂ concentration (10-40%), and gasification processes (direct and two-step gasification) were assessed under pyrolysis and gasification conditions. It was found that no NH₃ and COS were detected during pyrolysis and gasification of coal. High temperature improved H₂S and HCN emission during coal pyrolysis. High temperature promoted the HCN release during entrained flow gasification, whereas high CO₂ concentration inhibited H₂S and HCN emission. The majority of H₂S and HCN emissions came from the pyrolysis part during two-step gasification. Compared to two-step coal gasification, direct coal gasification released less H₂S and HCN. The results provide important information for the gas cleaning process downstream of entrained flow gasifiers.

nitrogen and sulphur species,low-rank coal,entrained flow,pyrolysis,gasification