The working principle of the mixer

The working principle of the mixer: mainly rely on the mechanical stirrer, air flow and the jet of the liquid to be mixed, etc., so that the materials to be mixed are agitated so as to achieve uniform mixing. The agitation causes a portion of the liquid to flow, which in turn propels the liquid around it, resulting in the formation of a circulating flow within the vessel. The resulting diffusion between the liquids is called the body convection diffusion. When the liquid flow velocity caused by the agitation is high, shear occurs at the interface between the high velocity liquid flow and the surrounding low velocity liquid flow, thereby generating a large amount of localized vortices. These vortices quickly spread to the surrounding, and more liquid is entrained in the vortex. The turbulent convection spread formed in a small area is called eddy diffusion. Mixing requires uniform distribution of all materials involved in mixing. The degree of mixing is divided into three states: ideal mixing, random mixing and complete mixing. The degree of mixing of the various materials in the mixing machine depends on the proportion of the material to be mixed, the physical state and characteristics, and the type of mixing machine used and the duration of the mixing operation.

The moving parts of the mechanical stirrer also have a shearing effect on the liquid when it is rotated. The liquid is also subjected to shearing when it flows through the wall and various fixing members installed in the container. These shearing actions will cause many Local eddy diffusion. The convection and eddy diffusion of the main body caused by the stirring increase the surface area of ​​the diffusion of molecules between different liquids to reduce the diffusion distance, thereby shortening the diffusion time of the molecules. If the viscosity of the liquid to be mixed is not high, a random mixing state can be achieved without a long stirring time; if the viscosity is higher, a longer mixing time is required.

For liquids of different density, composition, and incompatibility, the shearing action and the strong turbulence produced by the agitation shred the dense liquid into small droplets and disperse it evenly into the main liquid. The flow rate of the liquid produced by the agitation must be greater than the settling velocity of the liquid droplets.

The mechanism of mixing a small amount of undissolved powdered solid with a liquid is different from that of the density, and the mixing mechanism of the immiscible liquid is the same, except that stirring can not change the particle size of the powdery solid. If the solid particles before mixing cannot make the settling velocity slower than the flow rate of the liquid, no uniform suspension can be formed regardless of the stirring method used.

Mixing of different pastes is mainly the repeated shearing of the materials to be mixed and subjected to pressure, squeezing, squeezing, etc., resulting in a strong shearing action, followed by repeated merging, kneading, and finally achieving the required degree of mixing. This mixing is difficult to achieve the ideal mix, only to achieve random mixing. The powdery solid is mixed with a small amount of liquid and becomes a paste. The mixing mechanism is the same as the mixing mechanism of the paste material.

The mixing of different thermoplastic materials and thermoplastic materials with a small amount of powdery solids requires strong shearing and repeated kneading and kneading to achieve random mixing.

The good fluidity of granular solids is mainly caused by the rotation of the container itself, or by the action of moving parts contained in the container, and it is repeatedly turned and blended to be mixed. Such material can also be used to generate convection or turbulence through the airflow to achieve mixing. . The convection or turbulence of solid particles is not easy to generate turbulence. The mixing speed is much lower than the mixing of liquids, and the mixing degree can only generally achieve random mixing. Poorly fluid particles that adhere to each other or powdered solids often require mixing machinery with mechanical tumbling, pressure, and tamper action.