Coal slurry pipeline blowback system

The utility model discloses a coal slurry pipeline back flushing system which comprises a coal slurry pipeline (1) and is characterized in that one end of a high-pressure nitrogen purging pipeline (9) is communicated with a nitrogen purging tank (13), and a nitrogen purging stop valve (10) is arranged on the other end of the high-pressure nitrogen purging pipeline (9); a purging stop valve subline (11) is also arranged between the inlet pipeline and the outlet pipeline of the nitrogen purging stop valve (10); and a throttle valve (12) for controlling the nitrogen amount in the back flushing process is arranged on the purging stop valve subline (11). Stable high-pressure nitrogen purging is used as a power gas source, a throttle valve is added, and a purging procedure is designed, so that the problems of furnace temperature drop, flash explosion and the like caused by the fact that coal slurry enters the furnace in advance, a large amount of inflammable volatile components escape in advance and the oxygen-carb