Distributions and Formation Laws of Polycyclic Aromatic Hydrocarbons During Steam-Coal Chars Gasification

In order to control effectively typical pollutants polycyclic aromatic hydrocarbons ( PAHs) generated in underground coal gasification ( UCG) process, the experiment was carried out to study the generation and distribution laws of PAHs in the process of steam-coal char gasification by simulated fixed-bed gasifier with ligni te from Ulanqab, Inner Mongolia. The results showed that the 3-ring PAHs dominated in the cooled gas, the acenaphthylene and acenaphthene content were the highes t. As the gasification temperature increased from 900。C to 1 000。C, the total yield of PAHs decreased from 73. 19 mg 1 kg to 9. 40 mg 1 kg, namely a reduction by nearl y 90%. However, further increasing of temperature to 1 100 °C caused the total amount of PAHs increment. As the flow rate of steam increased from0. 17 mol 1 min to 0.61 mol/ min, the total yield of PAHs increased firstly and then decreased. When the steam flow rate was 0. 39 mol 1 min, the yield of PAHs reached the maximum val ue 73. 19 mg 1 kg, which was 1. 5 times of the minimum. The yield of PAHs could decrease when the temperature ranged from 1 000~ 1 100 °C. With the flow rate of st eam increased, PAHs yield decreased in cooled gas, so the PAHs in condensate water should be treated more intensively.