(522b) Studies On a Newly Developed Modular Packed Absorption Column

Studies on a newly developed modular packed absorption
column

1.   
Motivation

Increasing product differentiation and changing from
commodities to specialized products are reasons for shortened product life
circles in chemical engineering. Traditionally, large scale-plants possess
inadequate flexibility in capacity and product portfolio based on their ?one
purpose' development. Therefore apparatus with increased flexibility, like
modular devices, becomes necessary to handle fluctuating customer demands. Due
to modular assembly capacity can be increased either by equaling up modules from general structures or by numbering up equipment. Hence, a ?smart scale-up' of the complete
modular apparatus becomes possible. In favor of smart scale-up only the
operating parameters of the single module are necessary and thus reduced
time-to-market periods for the products (see figure 1). In fact the challenge
on scaling-up modular devices is an equal feed flow for every single module.

Modular
devices are state of the art in chemical engineering. Apparatus types like
plate heat exchangers or filter presses are established technologies with a
long history of development. Nevertheless, most of other apparatus principles
are not modular in terms of adaptable capacity and operational flexibility.
Even continuously working multiphase reactors and separation units are scale-up
by the traditional similarity analysis. Therefore our chair is running several research
projects presently dealing with the modularization of multiphase units like
packed columns and bubble column reactors for example.

In
this contribution first experimental studies on a newly developed packed
absorption module are compared with the operation behavior of a conventional
packed column.

2.    Experimental Studies

For the experimental studies
a packed absorption module with rectangular cross-section was developed (see
figure 2). Firstly, experimental studies regarding hydrodynamics and mass
transfer efficiency of the module have been performed. Those studies have been
performed with dumped and structured packings for
liquid and gas loads up to the flooding point. In detail, this work presents
results of measurements with Pall Ring 25 M and Raschig
Super-Pak 250. A comparison of experimental results between a packed absorption
module and conventional packed columns shows the practicality of this new
apparatus (see figure 3). With regard to identical packings,
the module's results are comparable to conventional packed columns. Although
the single module shows the expected losses in capacity for the gas and liquid
load, it shows comparable results for the mass transfer efficiency in
consideration of the reduced cross-section. Particularly with regard to the
distribution of the fluids in the module, experimental studies have been
performed to show the influence of the rectangular cross section and thus the
shortened distance for liquid and gas to the wall. For   qualitative and quantitative investigations of
the wall effect a new in-situ measurement method for the   thickness of the wall near liquid film in
packed columns will be developed. By a detailed examination of the wall effect
inside the module, internals will be designed to minimize the wall film thickness
and increase the mass transfer efficiency.

For an investigation
of the gas distribution, studies have been performed with fog to visualize the
stream of the gas inside the rectangular absorption module. The tests with fog
will show the need of a gas distributor and the behavior of gas stream inside
the newly module.

3.    Interconnection of the
modules

As aforementioned the utilization
of the packed absorption module can be increased by a multiple connection of
single modules, the so-called numbering-up.
Purpose of this work is to show possible design studies to connect single
modules (see figure 4). These studies indicate the conduction of gas and liquid
flows and possible integration of the modules into existing modular concepts
like frames of plate heat exchangers.