Gas Rate and Bubble Size

Column cells are operated in the bubbly region where bubbles rise in a swarm. The flow regime in the column may change to the 'churn-turbulent' condition when coalescence is caused by gas entering a region faster than it can leave as small bubbles. As smaller bubbles have lower swarm rising velocity, the flooding occurs at a lower gas rate for fine bubble dispersions. Thus, there is a link between maximum gas rate at the flooding point and bubble size. Also, flooding is enhanced by countercurrent slurry flow; the higher its superficial velocity, the lower the gas rate at the flooding point. At bubble size ranges used for column flotation, flooding occurs typically at a superficial air velocity of 2.5-3 cms-1. More precise values can be calculated from the drift flux model.

It is also possible for uniform countercurrent froth flow to occur in the column even at lower superficial air and slurry rates when the bubbles are very stable (gas hold-up at both bubble and froth flow regimes can also be estimated based on the drift flux model).

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook

Post a comment