Drop tube furnace device and method for reducing NOx discharge of blended coal combustion

The invention belongs to the field of drop tube furnaces and discloses a drop tube furnace device for reducing NOx discharge of blended coal combustion. The drop tube furnace device comprises a drop tube furnace body, a powder feeding pipeline assembly and a smoke graded circulating assembly. The powder feeding pipeline assembly comprises a secondary air tube, two primary air powder tube and a main smoke tube; the smoke graded circulating assembly comprises a main smoke tube and two smoke circulating tubes; the secondary air tube is vertically mounted on the upper portion of a hearth, the two primary air powder tubes are separately a primary air powder tube A and a primary air powder tube B, and one end of the main smoke tube is connected to a smoke outlet A of the drop tube furnace body while the other end of the main smoke tube is separately connected to the two smoke circulating tubes. The device provided by the invention improves incomplete combustion of coal ash while reducing NOx discharge, so that the