7 replies to this topic

[Art Montemayor]

Anshul:

I think your difficulty lies in the way you are interpreting the Mott data and spargers. You will note that they employ a porous medium for the creation of micro-sized, multiple gas bubbles. The area that they calculate relates to the super-efficient area of their “elements” – their porous media.

You, on the other hand are converting this area to conventional, circular holes. This is OK, but you can easily visualize how a conventional circular hole is not competitive with a porous medium in lending effective, sparging area to a gas.

When I have required multiple, efficient sparging area I have always resorted to using something similar to what Mott employs: sintered bronze or sintered stainless steel. Many machine shops or foundries located in developing countries can produce this type of element if they are requested to do so. You will find that a properly manufactured sintered stainless steel element will produce such fine and dispersed bubbles that the required area you calculate will be far less than the element you employ.

The one, important problem in using sintered elements for spargers is that the fluids – particularly the parent liquid fluid – must be essentially pure and clean, and not be very viscous. The closer to water viscosity it is, the better the sparging operation. Slurry or dirty liquids will plug or negatively affect a porous sparger. If you are located in a developing country, I would try to have a sintered stainless element made locally and I would employ as much area as I could after experimenting with the element and its sparging action.

Art Montemayor

[djack77494]

Anshul:
For very simple (holes in a pipe) type of spargers where you'd like to get somewhat equitable distribution of the introduced fluid, I have designed spargers using a very simple criterion. As long as the pressure drop through the sparger holes significantly exceeds the fluid's velocity head, the fluid should tend to equitably distribute itself through the holes. I like to use a dP of at least 4 velocity heads, but this is totally arbitrary. Consider the liklihood of solid contaminants, including some pipe scale, being present in deciding on what hole size to specify. Again, it's totally arbitrary, but I like to specify a hole size of at least 1/8 inch (6 mm) diameter. With your preliminary design, as above, decide on whether you are satisfied with the number and layout of holes, and iterate as needed. For large systems, you very likely would employ a manifold system to provide good distribution of the introduced fluid.
Good Luck,
Doug

[anshulagr]

Thank you group for your valuable inputs.

Anshul

[sdarone]

Anshul,
There was an article on the chemical engineering, april6, 1981, titled: hole-area distribution in liquid spargers, this article shows a program (iterative) to dimension the area of the holes in the TI-59 calculator, this one is a correctio to a previous article, about the same issue, but were velocity head was not considered in the equation.
I encourage you to read this article... you will find that the first orifices in the sparger must be larger, that the ones at the end, in order to have a good distribution.

Hope this Helps.

Sergio

[SPEORC]

Sergio,

I am looking for details of sparger design for liquid distribution in vessel filled with water. I think an article on the chemical engineering, april6, 1981, titled: hole-area distribution in liquid spargers will be useful for me. I am unable to get this article. Can anyone post this article to my e mail id joshivinayak@gmail.com.

Thanks,

Vinayak

[SPEORC]

Sergio,

I am looking for details of sparger design for liquid distribution in vessel filled with water. I think an article on the chemical engineering, april6, 1981, titled: hole-area distribution in liquid spargers will be useful for me. I am unable to get this article. Can anyone post this article to my e mail id joshivinayak@gmail.com.

Thanks,

Vinayak