Bag filter structure type are: 1, according to the shape of the bag is divided into: flat bags (trapezoidal and flat-shaped) and round bags (cylindrical). 2, according to the way into and out of the wind: the wind under the air intake on the wind and motivated wind down and DC-type (confined to the plate-like flat bags). 3, according to the bag filter is divided into: external filter type and within the filter type.