Method for upgrading and transforming counter-rotating fan in coal mine main ventilation system

The invention discloses a method for upgrading and transforming a counter-rotating fan in a coal mine main ventilation system. The method comprises the following steps that S1, an air duct section ofan original standby fan of the main ventilation system is dismantled, and a power section of the original standby fan is reserved, wherein the power section comprises a motor and fan blades; S2, a main operation component and an air duct part of a fresh air ventilator are installed behind an exhaust outlet of the power section of the original standby air ventilator in the exhaust direction; S3, the reserved part of the original standby fan in the first step is dismantled; S4, a connecting front part of the fresh air ventilator is installed in front of a main operation part of the fresh air ventilator, and an outlet of an exhaust pipeline of the main ventilation system is connected with an air inlet of the fresh air ventilator; and S5, the step 1 to the step 4 are repeated to replace the original main operation fan