Categories

Knowledge

How the mixer works
Dec 24, 2018

The mixer is determined by a number of parameters, and it is not possible to describe a mixer with any single parameter. Shaft power (P), blade discharge (Q), head (H), blade diameter (D), and agitation speed (N) are five basic parameters that describe a mixer. The discharge volume of the blade is proportional to the flow rate of the blade itself, the primary of the blade rotation speed and the cube of the blade diameter. The shaft power consumed by the agitation is proportional to the specific gravity of the fluid, the power level of the blade itself, the third of the rotational speed and the fifth power of the blade diameter. In the case of a certain power and blade form, the blade discharge volume (Q) and the indenter (H) can be adjusted by changing the matching of the diameter (D) and the rotational speed (N) of the blade, that is, the large diameter blade is matched. A mixer with low speed (with constant shaft power) produces a higher flow and a lower head, while a small diameter blade with a higher speed produces a higher head and lower flow. In the agitation tank, the only way to cause the micelles to collide with each other is to provide a sufficient shear rate. From the stirring mechanism, it is precisely because of the difference in fluid velocity that the fluid layers are mixed with each other. Therefore, the stirring process always involves the fluid shear rate. Shear stress is a force that is the real cause of bubble dispersion and droplet breakage in agitation applications. It must be pointed out that the shear rate of each point of the fluid in the entire agitation tank is not uniform. Studies on the shear rate distribution show that there are at least four values of shear rate in a stirred tank. They are: experimental studies have shown that, in terms of the paddle area, no matter what type of pulp, when the blade diameter is constant Both the maximum shear rate and the average shear rate increase with increasing speed. However, when the rotational speed is constant, the relationship between the maximum shear rate and the average shear rate and the diameter of the blade is related to the slurry type. When the rotational speed is constant, the maximum shear rate of the radial blade increases as the diameter of the blade increases, and the average shear rate is independent of the diameter of the blade. These concepts regarding the shear rate of the paddle zone require special care in the mixer's shrinking and amplifying design. Small tank mixers tend to have high speed (N), small blade diameter (D) and low tip speed (ND) compared to large tanks, while large tank mixers tend to have low speed (N) Features such as blade diameter (D) and high tip speed (ND).


  • QR CODE
  • facebook