Q & A > Question Details
If top pressure is maintained on lower side, what is the effect on top temperature, side draw - off temperatures, pressure profile in the column and on the quantity and quality of overhead product?
29/10/2015 A: Dharmendra Singh Bhati, BHARAT OMAN REFINERIES LIMITED, dharam5058@gmail.com
If we have good condensing media to reduce column pressure:
Any column pressure generally designs on the basis of Utility available for Overhead Condenser, Reduced column pressure means high relative volatility or good distillation as well as low energy required for re-boiler but at the expense of high utility required to condense the overhead vapors.So column pressure should be optimum for energy point of view.If column pressure is maintained low side in that case whole column temperature profile would be low side, Column top temperature as well as draw off temperatures.IF top pressure is lower side hence pressure drop would be lower side.Quantity of overhead product would reduce slightly because of more rectification and quality of overhead product would improve.
21/08/2014 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
In general, other factors aside, such as not needing a compressor, the pressure should be as low as practical to minimize energy usage, but still able to condense the overhead product. Some plants change pressures seasonally for this reason.
When the pressure is lowered:
1. The required top, side-draw, and bottom temperatures are reduced for the same product separation.
2. Column pressure drop increases.
3. Unless the tray loadings are excessive and cause entrainment, the same separation can be achieved. Quantity and quality.