Blast furnace coal injection system and control method thereof

The invention provides a blast furnace coal injection system. The blast furnace coal injection system comprises an injection tank, a distributor, an injection gun and a coal powder bin communicated through pipes, wherein a quantitative feeder is arranged at the bottom of the injection tank; a coal powder main pipe is arranged between an outlet of the quantitative feeder and the distributor and the injection gun, and is provided with a coal outlet valve and a coal conveying valve; and a pressure homogenizing pipe is arranged between the coal powder main pipe and the top of the injection tank. An air source main pipe is divided into three pipes of pressure stabilization, injection and air replenishment, which are respectively connected with the injection tank, the quantitative feeder and the coal powder main pipe. A control method of the blast furnace coal injection system is as follows: while one injection tank injects, the other injection tank performs preparations of pressure relief, quick relief, powder loading, pressurization and waiting; after the injection of the first injection tank is finished, the tank is replaced; and then, the second injection tank enters the preparation process for alternate circulation. The quantitative feeder is mounted at the bottom of the injection tank, so that the injection precision is improved, the tank replacement fluctuation time is shortened, and necessary conditions are provided for stabilization of blast furnace production.