Nitrogen drilling anti-erosion wellhead apparatus

The invention provides a nitrogen drilling anti-erosion wellhead apparatus, comprising a drilling cross, a lower gate blowout preventer, a sand discharge cross, an upper gate blowout preventer, a circular blowout preventer, a rotary control head, a first row of sand discharge line, a second row of sand discharge line, a third row of sand discharge line, a first sand discharge tee and a second sand discharge tee; a first end of the drilling cross is connected with one end of the lower gate blowout preventer; the other end of the lower gate blowout preventer is connected with a first end of the sand discharge cross; a third end of the sand discharge cross is connected with one end of the upper gate blowout preventer; the other end of the upper gate blowout preventer is connected with one end of the circular blowout preventer; the other end of the circular blowout preventer is connected with one end of the rotary control head; a second end of the sand discharge cross is connected with the first row of sand discharge line through the first sand discharge tee; a fourth end of the sand discharge cross is connected with a first end of the second sand discharge tee, and a second end of the second sand discharge tee is connected with the second row of the sand discharge line. Improvements are given to nitrogen drilling heating safety and reliability.