Multi-stage mixed flow primary air pipe anti-blocking system

The invention relates to a multi-stage mixed flow primary air pipe anti-blocking system. According to the technical scheme, the multi-stage mixed flow primary air pipe anti-blocking system comprises aprimary air pipe; the primary air pipe is of a round hollow tubular structure formed by sequentially connecting a primary air pipe horizontal section, a bend transition section and a primary air pipevertical section together; and a first-stage swirler, a second-stage flow mixer and a third-stage flow mixer are sequentially arranged in the primary air pipe horizontal section in the pulverized coal conveying direction, a vertically-through pulverized coal deposit collecting opening is formed in the bottom of the junction of the primary air pipe horizontal section and the bend transition section, and a pulverized coal collecting device stretching downwards is connected to the pulverized coal deposit collecting opening. As the first-stage flow mixer, the second-stage flow mixer and the third-stage flow mixer are arra