Tar formation in a steam-O2 blown CFB gasifier and a steam blown PBFB gasifier (BabyHPR): Comparison between different on-line measurement techniques and the off-line SPA sampling and analysis method

Two on-line tar measurement campaigns were carried out using an atmospheric pressure 100 “”kWth steam-O2 blown circulating fluidized bed (CFB) gasifier at the Delft University of Technology (TUD) and a 30–40kWth steam blown pressurized bubbling fluidized bed (PBFB) gasifier BabyHPR (Heatpipe Reformer) at the Technical University Munich (TUM). Agrol, willow and Dry Distiller's Grains with Solubles (DDGS) were used. An FID based on-line tar analyzer (OTA), an induced fluorescence spectroscopy (LIFS) based on-line laser instrument, and off-line solid phase adsorption (SPA) were used to quantify tar content.In general, there was a fairly good agreement between the measured results of the 10 corresponding individual tar compounds obtained from Agrol and willow CFB and PBFB atmospheric pressure tests using the SPA and LIFS methods. The measured tar concentration difference between these two methods was less than 10%. However, a higher difference (up to 30%) was observed for fluoranthene and pyrene obtained from DDGS CFB test as well as those obtained from willow PBFB under pressure test. The total tar concentration measured by the LIFS, SPA and OTA methods varied in a comparable way with changing process parameters. Both the LIFS and OTA methods can be used as indicators to observe gasifier's performance change in real time, but a regular calibration of the OTA analyzer is required to achieve good and reliable results.

► Different on-line and off-line tar measuring techniques were compared.
► Tar formation in a steam-O2 blown CFB and a steam blown PBFB gasifier was studied.
► Both LIFS and OTA can be used as indicators to observe the gasifier's performance in real-time.
► LIFS is a reliable on-line tar measurement technique and the measured results agree well with SPA.