![]() ![]() ![]() Since the gas will escape upward in a matter of seconds, it is necessary to agitate vigorously to keep as much gas in the liquid as possible.Īlso, P/ V in gas-liquid mixing depends on the process. In solid-liquid mixing, the density difference is a few times at most, but in gas-liquid mixing, the difference is about 1,000 times. Gas-liquid mixing is the most difficult of all multiphase systems. However, it is important to note that if the P/ V is set too high, the metal particles are likely to hit the impellers and vessel walls, causing wear or erosion. On the other hand, heavier particles such as metals require more energy to lift, so their P/ V tends to be higher. The density of polymer particles is often close to the density of the liquid, so not much power is required. If the density of the solid particles is close to the density of the liquid, the P/ V is low. Solid-liquid agitation depends on the density of solid particles. However, when mixing two phase-separating liquids such as water and oil, it may take up to 1.0 to 2.0 P/ V.įurthermore, it is difficult to achieve completely uniform dispersion. Liquid-liquid agitation is a relatively easy system for uniform mixing. P/V value for each type of mixingįor each agitation systems, P/ V is a value assuming the liquid is of low viscosity.Īs is usual with agitation, it is very difficult to uniformly mix materials with different densities, and power is required. The P/ V is separated by up to 5.0, meaning that liquids that are too viscous are difficult to mix in the mixing vessel. ![]() It may no longer be better to use a kneader in that area than to use an mixing vessel. It will be mixed with a liquid that has properties similar to a solid, such as syrup. When the P/ V exceeds 5.0, the liquid is no longer agitated as generally imagined. High viscosity agitation requires more power for agitation, resulting in higher P/ V. On the other hand, operating P/ V at 1.0 or higher is not recommended because the mixing performance does not change much for the power required. It may be possible in an mixing vessel that does not require uniform mixing. P/ V of 0.1 or less is unlikely to be selected for a stirred reaction tank because the agitation power is too low and mixing performance is poor. Low-viscosity liquids that do not require much agitation power are often designed with P/ V of 1.0 or less. P/V Guidelineīelow is P/ V guideline for each mixing system. Therefore, the effect of scale is eliminated by dividing by the liquid volume in the mixing vessel. If this is the case, it is impossible to determine whether power is excessive or insufficient. When evaluated simply by the required agitation power P, the larger the mixing vessel and agitation impeller, the higher the value. P/ V is often used as an indicator to determine if sufficient power is being applied to the liquid in the mixing vessel. Where P is the agitation power, V is the liquid volume. P/ V is expressed by the following equation: The power required to agitate per unit volume (liquid volume) is called P/ V value. ![]()
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