Carbon dioxide removal in indirect gasification - SGC

SGC Rapport 2013:277
Figure 1. Haldor Topsoe's methanation process TREMP [7].
The disadvantage with recycling the product gas is the higher volume of gas that
needs to be processed and the dilution of the reactant gases. It also increases the
cost and energy loss due to the need to compress the recycled gas.
2.2.2 TWR – Throughwall Cooled Reactor
Throughwall cooled reactors are commonly used reactors in chemical processes
that utilize heterogeneous gas reactions and is also known as the plug-flow reactor.
The reactor design is relatively simple and uses a shell and tube approach.
The tubes are filled with catalyst and the tubes are cooled either by boiling water
or oil. Figure 2 shows a TWR system [1].
The cooling method utilized in these types of reactors increases the difficulties of
controlling the heat of reaction. As the methanation reactions are highly exothermic,
the temperature control becomes increasingly difficult and thus, hot-spots can
pose a problem in TWR reactors [1].
The main advantage with the plug-flow reactor is that only one reactor is needed
and this is because the reactor can contain any number of tubes. This results in
lower investment and operating cost. The biggest disadvantage of the reactor is
the problems involved in replacing depleted catalyst [1].
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