https://doi.org/10.1016/j.egypro.2017.03.1312
“Figure 3 shows the overall gas phase mass transfer coefficient (KGa) for CO2 absorption as a function of
rotational speed and liquid: gas (L/G) mass flow ratio. The black and white markers shows results from this
experimental study and the coloured markers show the results from Jassim and his co-workers [1]. The most
noticeable trend in the data is that KGa is a strong function of the strength of the MEA solution, more than doubling
as the solution strength increases from 30 mass% MEA to 90 mass% MEA. The L/G ratio has no effect on KGa for
30 mass% amine solutions but a noticeable effect for the 90 mass% solutions. This is because changes in the feed
flow rate of the 30 mass% solution do not lead to significant changes in the number of moles of MEA being fed to
the rotating packed bed. The rotational speed has a weak effect on K Ga which increases sligh tly as the rotational
speed increases.”
“The measured values of K Ga were compared with the results from Jassim [1] and Tan and Chen[4]. The work of
Jassim is most directly comparable because they worked with solutions of similar strength and, with the exception of
the 30 mass% solution, preloaded them to 0.1 mol CO 2/mol MEA. The major difference between the two
experiments is that the L/G ratios are very large in Jassim’s work, 16 and 33. These L/G ratios would never be used
in practice because of the implications for the regeneration cost of such large liquid flows. For 30 mass% solutions
the K Ga values are lower despite the L/G ratio. This is because Jassim preloaded the 30 mass% amine solution to
0.33 mol CO2/mol MEA. The KGa values measured by Jassim for the 75 mass% MEA soluti on are similar to the
values we measured for 90 mass% MEA. This is due to the higher L/G ratios used for the tests with 75 mass%
MEA. Tan and Chen used weaker solutions containing 6.1 mass% MEA and 3.1 mass% MEA with 4.3 mass%
Piperazine. All their data was measured at 1300 rpm and they used L/G ratios in the range 4.3 to 6.2. For the 6.1
mass% MEA solution they found that K Ga increased from 0.3 to 0.4 as the L/G ratio increased and for the mixed
amine solution KGa increased from 0.6 to 1.5 as the L/G ratio increased.
The force required to maintain the torque arm in a hori zontal position was found to be constant with increasing
liquid flow rate suggesting that the force re quired to overcome the fri ction from the seals described in section 3.1 is
dominant. The measured torque was 0.86 Nm ± 0.25 Nm. Using equation 3, the power consumption was found to
increase from 108 -261 W as the rotational speed increased from 600-1450 rpm. These results indicate that the
torque arm needs to be longer so that changes in power consumption with liquid flow rate can be measured.”