Fig. 10　Effect of highest loading factor on net output power and total packed column volume

Fig. 11　Effect of size of packing on net output power and total packed column volume

Fig. 12　Flow sheet of a diesel engine system and detailed operating conditions

　

4.3　Effects of Packing Size

Fig. 11 shows the effect of the packing nominal size： the size does not change the net output power and the CO₂ recovery ratio： but larger nominal size of the packing results in larger total volume of the packed columns.

　

4.4 Detail of Operating Condition

A detail data set of the operating conditions of the diesel engine with CO₂ recovery equipment is shown in Fig. 12. A maximum CO₂ recovery ratio of 70% is obtained at expense of engine output power of 860 kW.

　

5. Discussion

5.1　Limit of CO₂ Recovery Ratio

Correlations of the CO₂ partial pressures in the gas phase with the CO₂ loading factor in the liquid phase both in the absorbing column and in the stripping column, which are calculated for the reference calculation condition, are shown as the solid lines, called operating lines, in Figs. 13 and 14 respectively; in which the operating lines are drawn for three CO₂ recovery ratios, α_R. Also equilibrium lines, the dotted lines in Figs. 13 and 14, for correlations of the equilibrium CO₂ partial pressure of the liquid phase with the CO₂ loading factor are shown. Distance between the operating line and the equilibrium line indicates degree of CO₂ transfer driving force.

The equilibrium lines bend around CO₂ loading factor of 0.4, and the equilibrium pressure of CO₂ increases steeply when the CO₂ loading factor exceeds about 0.4. On the other hand, the operating lines of the absorber can be regarded as straight ones, although those of the stripper slightly curve downward due to condensation of the stripping steam.

　

Fig. 13　Distribution of CO₂ partial pressure and loading factor in absorber on reference calculation conditions

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