Bell bottom (distillation)
The bubble tray is in the industrial chemistry , an installation in a rectification to fractional distillation . Such a distillation apparatus is simply called a column in the chemical industry . In order to separate liquid substance mixtures into fractions with different boiling ranges , several bubble trays are placed on top of each other.
function
The hot vapor mixture to be fractionated flows continuously through the column from bottom to top .
The purpose of the bell bottom is to achieve the largest possible contact area between the vapor mixture and the condensed liquid standing on the trays. Through this contact, condensable components are condensed from the gas phase, the heat of condensation is released and causes volatile components from the liquid phase to evaporate. This is repeated on each tray, so that the condensed low boilers accumulate in the upper trays, while the high boilers accumulate in the lower trays. The gas phases of the floors below have higher temperatures and higher pressures than those of the higher floors. This drives the throughput of the column. The thermal management of the column is optimized as far as possible by the gas temperature and the supply pressure and little heat is given off ( adiabatic behavior).
A bell bottom consists of a horizontal perforated plate, the openings of which are extended upwards by tubes. These are provided with screwed -on bell-shaped covers, hence the name. Overflow weirs hold back part of the gas that has condensed into liquid on the floors, while another part runs back over the weir to the next lower floor. High boilers are conveyed downwards, while low boilers rise as steam. Side draws enable the continuous separation of intermediate fractions, which, however, are contaminated with the dissolved low boilers and can optionally be cleaned by strippers . Low boilers or products are drawn off via the top of the column and high boilers are drawn off via the bottom.
See also
literature
- Arno Behr, David W. Agar, Jakob Jörissen: Introduction to Technical Chemistry . Spektrum Akademischer Verlag, Heidelberg 2010, ISBN 978-3-8274-2073-2 , Chapter 7: Thermal separation processes I (distillation and rectification) , doi : 10.1007 / 978-3-8274-2195-1_7 .