Gas-liquid mixing

Propeller andturbine open mixers are widely used in various industries for mechanical mixing of gas-liquid media. These mixers are distinguished by the principle of mixing. The turbine mixer generates significant shear stresses that allow dispersing the gas. The propeller mixer generates an intense circulation flow in the axial plane, which makes it possible to suspend solid particles when mixing three-phase media.

One of the variations of theturbine mixer is an open turbine mixer having blades located at an angle of 45 degrees relative to the vertical. This type of mixer makes it possible to take advantage of the open turbine and propeller mixers. That is, it produces both high shear stresses and intense circulation.

During the mechanical mixing of liquid gases behind the blades of the mixers, significant gas caverns are formed. Three types of gas cavities are formed depending on the speed of rotation of the mixers. So, when the mixer is operating at low speeds, a large gas cavity appears, which can occupy almost the entire area located behind the mixer blade. A change in the angular velocity of rotation of the mixer causes an inversely proportional change in the gas cavity. That is, with increasing speed, the cavity decreases and turns into vortex gas formations descending from the blades of the unit. With a subsequent increase in speed, the gas cavity will change position from the outer edge to the inner edge of the mixer blade.>

The power phase is greatly influenced by the gas phase. So, with an increase in the feed rate, the produced power of the mixer decreases.

A drop in power consumption is caused due to the presence of dispersed gas bubbles. The formation of bubbles leads to a decrease in the average density of the medium.

The type of gas cavity that appears behind the blades also affects power consumption. A large degree of influence of the blades on the environment can be observed at low speeds. This is due to the liquid surrounding the outer ends of the blades.

Also, an important factor affecting power consumption is the radius of the mixer, raised to the fifth degree.

The dependence of the rotation speed and power consumption is the inverse, that is, a gas cavity covering the entire rear surface of the blade, which forms with increasing speed, generates large-scale vortex formations. At lower speed, these vortexes are liquid, which means more energy is needed to give them the necessary kinetic energy. A continued increase in speed leads to a decrease in the size of the gas cavity and an increase in power consumption. A further increase in speed leads to an increase in power consumption due to the displacement of the cavity from the gas to the inner edge of the blade.

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