Intensified desulphurization process in the production of renewable

Intensified desulphurization process in the production of renewable gaseous
A. Makaruk, M. Miltner, M. Harasek
Institute of Chemical Engineering, Vienna University of Technology
A-1060 Vienna, Getreidemarkt 9/166, Austria
tel: 0043-1-58801-15927, fax: 0043-1-58801-15999,
Methane and hydrogen can be obtained in several different biomass conversion processes
like anaerobic digestion or gasification to yield renewable gaseous fuels. These gases are
supposed to play a crucial role in future energy systems. Besides their apparent advantages
like high energy densities and easy convertibility to other energy forms, their possible energy
storage function has gained much importance recently.
Virtually any production process of renewable gaseous fuel is associated with gas
upgrading, i.e. basically separation of carbon dioxide, and with gas processing, i.e. separation
of undesired gas components. In the latter one, the separation of hydrogen sulfide is often
indispensable. Hydrogen sulfide is a common gas component in methane and hydrogen
containing biogases originating from anaerobic digestion processes and in gas mixtures
originating from biomass gasification. The hydrogen sulfide content is typically below 5000
ppmv, while the content of carbon dioxide is much higher and equals >20% v/v.
In this work we present an intensified process for the selective separation of hydrogen
sulfide from carbon dioxide containing gases that is to be used in the processing of renewable
methane and hydrogen. The objective is to develop a compact apparatus, whose dimensions
are at least one order of magnitude smaller than those of conventional absorption or
adsorption processes. The process is to be realized on the basis of absorption in high alkaline
solutions and the separation selectivity is to exploit the different absorption rates between
hydrogen sulfide and carbon dioxide. Since absorption of hydrogen sulfide is instantaneous
while the rate of carbon dioxide absorption is limited, the selectivity is obtained through
preserving very short contact times between gas and absorbent.
The evaluation of the process is first done by experiments on laboratory scale (Figure 1).
Here the fundamental design and operation features are worked out. This concerns parameters
like optimal contact times, optimal
chemical composition of absorbent
and gas to liquid ratios. The second
part of the work concerns the
economics of the process. The
operational and investment costs are
extrapolated from the data obtained
in the experiments.
Figure 1: Experiments in the laboratory scale
improvements of economics and
renewable gaseous fuels. This is
intensification, which leads to the
reduction of equipment size and
operational costs.
Figure 1: Experiments on the laboratory scale