Experimental investigation on solid particle distribution in dense solid–liquid stirred tank

As an important indicator to evaluate the suspension effect, the uniformity of solid particle distribution is directly related to mass transfer and reaction efficiency. Therefore, it is necessary to investigate the solid particle distribution in viscous system. The particle distribution of a dense solid–liquid system composed of glass beads-malt syrup stirred by the propeller is investigated experimentally by optical probe method, and the effects of impeller speed, number of baffles, particle size, average solid concentration and liquid viscosity on the solid particle distribution are discussed. The results show that, compared with the radial direction, the axial concentration distribution in the stirred tank is more uneven, and the axial mixing index is about 2–5 times the radial one. With the increasing stirring speed, the axial mixing index decreases slowly at first, then sharply decreases after reaching the just off-bottom suspension speed, and finally tends to be stable. The uniformity varies inversely with particle size and average solid concentration and directly with liquid viscosity. When the same effect is achieved, less energy is required without baffles.