The invention relates to an
underground coal gasification system and a production process thereof. The
system comprises an air course and a
gas transmission course which are arranged in a
coal seam, a plurality of gasification channels are arranged in the
coal seam, the two mutually parallel ends of each gasification channel respectively communicate with the air course and the
gas transmission course, and a water drainage closed wall is arranged in the
gas transmission course; and the both ends of the air course are respectively connected with an intake
airway and a return
airway of a mine
system. The gasification process comprises the following steps: igniting; judging whether the burning point is required to be moved forward; moving the burning point of the
coal seam backwards; plugginga gas passage of a
combustion-supporting gas injection
branch pipe which is disabled, and filling a burning
control area with paste. The coal underground gasification system and the production process have the advantages that the coal seam can be mined to the utmost extent; the leakage of the
combustion-supporting gas to the burning
control area can be thoroughly
cut off when the secure retraction during the coal underground gasification process is realized; the problem that the gasification agent is short-circuited because a passage is formed due to the collapsing of the coal seam floors in the gasification channel and the earlier period gasification area can be solved in the later period of the
underground coal gasification, the gas production is secure and reliable, and the gasification rate is high.