Figure 1: The effect of pressure on the amount of carbon dioxide
absorption at 313 K and at 1M piperazine concentration in comparison
with literature data (Chung et al. 2010).
Figure 1 shows the effect of pressure on the amount of carbon dioxide
absorption at 333 K and at 1M piperazine concentration. As seen in the
figure, carbon dioxide absorption increases with increasing pressure.
The reason for this is that, at higher pressures of the gradient, carbon
dioxide concentrations in the gas phase increase, and this increase in
concentration increases the chemical potential of the mass transfer from
gas to the liquid solution, and the absorption efficiency improves in
the gas absorption process, resulting in high pressure Increased
absorption potential improves separation (steep slope of the graph). But
at high pressures, this increase in pressure increases the flow rate of
gas passing through the tower, which reduces the time remaining and does
not allow sufficient time to transfer carbon dioxide from the gas phase
to the soluble phase. So in this case, the carbon dioxide absorption
rate (curve slope) is lower than the lower pressures.
Figure 2 depicts the carbon dioxide absorption in the system in terms of
pressure variations at various operating temperatures at a concentration
of 1M of piperazine and a temperature of 333 K.
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