When does the operating line for the gas absorber touch the equilibrium curve?

The operating line for a gas absorber touches the equilibrium curve when the specific condition of minimum liquid-to-gas ratio, Ls/Gs min, is achieved. At this point, the system operates at its most efficient level, which maximizes the mass transfer of the soluble component from the gas phase to the liquid phase.

By reaching this condition, the system is fully utilizing the potential for mass transfer without exceeding the necessary liquid flow rate to achieve the desired absorption. This means that the operating line aligns perfectly with the equilibrium curve, indicating that the two phases are in optimal contact and that the absorption process is being carried out effectively.

In other contexts, equilibrium conditions signify that the mass transfer between the gas and liquid phases has been fully balanced, which corresponds to the saturation point of absorbance, but it is the specific condition of Ls/Gs min that describes when the operating line actually contacts the equilibrium curve. The optimal temperature condition may influence the overall efficiency of the absorption process but is not the direct reason for the touchpoint of the operating line and equilibrium curve.