Page 2 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

Preface

Separation processes in gas (vapour) - liquid systems, like absorption, des-
orption and rectification, are estimated to account for 40%-70% of both capital
and operating costs in process industry [1]. A significant part of the costs are
connected with the packed bed columns used for these processes. The employ-
ment of these apparatuses also for direct heat transfer between gas and liquid,
including utilization of waste heat from flue gases, enlarges their importance.
Packed bed columns are the best type of apparatuses, from thermodynamical
point of view, for carrying out of mass and heat transfer processes between gas and
liquid phase. It is because of all types of highly effective apparatuses, they operate
as near as possible to the conditions of countercurrent flow, i.e., at maximum
driving force for given initial and end concentrations of the two phases and a given
ratio between their flow rates.
The history of packed bed columns has begun with absorption and desorption
processes. The first apparatus of this type was proposed by Gay-Lussac in 1827
who at this time was a consulting chemist of Saint Gobain Company [2]. The
column, called by his name, was designed to absorb NO X after the nitrosyl method
for production of sulphuric acid. 10 years later, filled up with coke, it was
implement in industry.
After 1980 a gradual displacement of the tray-type contactors by packet
columns began in the distillation plants, and until 1990 it was considered the
greatest novelty in the area of distillation [42].
Because of high efficiency, low pressure drop, and high admissible flow rates,
packed bed columns are now largely used in chemical and food industry,
environmental protection and also for carrying out of some processes in thermal
power stations such as water purification, flue gas heat utilization and SO 2
removal.
This book is intended for chemical and heat engineers working in these
industries and also especially for chemical engineers and scientists working on
development of new technologies which include absorption, desorption,
distillation, and direct heat transfer processes in gas-liquid systems. It is especially
proper for designers of such types of apparatuses.

N. Kolev