Pilot scale entrained flow gasification of Turkish lignites

Abstract

As a part of a coal to methanol project, experimental results obtained from gasification of five different lignites, namely Saray, Çan, Orhaneli, Tunçbilek and Soma lignites, in a 6 ton/day pilot scale entrained flow gasifier are presented. The gasification experiments were conducted using pure oxygen as the gasification agent. The proximate and ultimate analyses for the lignites were performed and presented at the beginning of the study. The gasifier had been operated at an equivalence ratio (ER) of around 0.5 for all the runs. The syngas compositions (H2, CO and CO2 concentrations) and steady state reactor temperatures were recorded; cold gas efficiencies and lower heating values of produced gases were calculated for each run. The ash flow temperatures and lower heating values of lignites played an important role in the effective gasification of the lignites. Among the five lignites studied, two, namely Tunçbilek and Soma, were found to be appropriate for gasification with the entrained flow gasifier. The Tunçbilek lignite produced a syngas with 60.1% CO and 20.5% H2, which had a lower heating value (LHVmax) of 9.8 MJ/Nm3. The Soma lignite produced a syngas with 62.4% CO and 24.2% H2, which had a lower heating value (LHVmax) of 10.5 MJ/Nm3. For Saray, Çan and Orhaneli lignites, CO compositions were between 41 and 50.1%, H2 compositions were between 12.2 and 19.3% and the LHVmax values ranged between 6.6 and 8.3 MJ/Nm3. The cold gas efficiencies (ηcold gas) for Saray, Çan, Orhaneli, Tunçbilek and Soma lignites were found to be 41, 42, 41, 64 and 72%, respectively. A short discussion about operational problems encountered during the gasification of Çan, Saray and Orhaneli lignites are also given in the discussion part.