Y4-73No.20 ~ 31 1 / 2F boiler drum Fan is 100-200MW thermal power generating units supporting. The fan is in the original production of G4-73-11, y4-73-11NO. (20-291 / 2) D, based on 20 years of production and use in accordance with the existing problems, re-design of new products. Compared with the original series, made the following significant improvements in design: (1) the original fan cantilever support (D type) rotation mode to intermediate support (F-type) rotation methods to improve the fan running stability; especially for induced draft fan for the balance due to the influence of the rotor and impeller wear after fouling, easy to cause fan vibration, this improvement is particularly important. (2) is equipped with five airfoil blade damper in the inlet chamber at the entrance to adjust fan characteristics, improve the efficiency of the fan regulator, adjust the blade support at the air-bearing, rotating flexible, reliable.