Big double-blade agitator with wide viscosity domain

The invention discloses a big double-blade agitator with wide viscosity domain. The big double-blade agitator comprises an agitation tank, an agitation shaft, an upper blade, a lower blade, an upper shaft sleeve and a lower shaft sleeve, wherein the upper blade and the lower blade are fixed on the agitation shaft at a certain distance and angle and are all provided with even numbers of grids. A downward extension plate is arranged at the bottom end on two sides of the upper blade. An upward extension plate is arranged on two sides of the middle part at the top end of the lower blade. A folding plate with a certain width and an inclination angle is arranged at the blade end of two sides of the lower blade. The big double-blade agitator has the beneficial effects that the efficient mixing performance of the agitator can be kept within the wider viscosity domain; and as the projected area on a longitudinal section of the agitation tank occupies a larger proportion of the longitudinal section of the agitation tank, the coefficients of a local heat transfer film on the wall of the tank are more uniform, and the coefficient of a whole heat transfer film is also improved. The big double-blade agitator has the advantages that the liquid level is allowed to have larger fluctuation, the structure is simple, and the machining and the industrial scale-up design are convenient.