The potential pollution
risk of underground coal gasification (UCG)
has become a key factor restricting the development of UCG industrialization.
Therefore, studying the migration and diffusion behavior of harmful
pollutants is of great significance for preventing UCG pollution.
In this paper, a large-scale three-dimensional similar simulation
experimental device for UCG is used to simulate the gasification of
Tianjin fat coal under actual working conditions. The rock layer around
the simulated coal seam was sampled after the gasification was completed,
the contaminants in the samples were examined by XRD, and the changes
in the relative content of the contaminants at different sampling
points were studied by FTIR. The results showed that benzene, phenols,
aldehydes, aromatic hydrocarbons, and aromatic heterocyclic compounds
remained after the gasification of No. 7 sampling point in Qianjiang,
Tianjin, and that the main pollutants were aromatic hydrocarbons.
The migration and enrichment of phenol and aldehyde pollutants were
about the same on the east and west sides of the gasification center,
while benzene pollutants were more easily migrated and enriched than
aromatic heterocyclic compounds. The migration distance of phenolic
pollutants on the south side of the gasification area is smaller than
that of other pollutants and their maximum vertical distance from
the gasification reaction area to the south is about 0.7 m. The results
can provide a scientific basis for pollutant risk identification and
prevention and control in the later UCG field test.