Dear Sir. Concerning your issue about the determination of the molar flow rate of the lean solvent. To calculate the molar flow rate of the monoethanolamine (MEA), we should know the density of the Liquid amine and the volumetric flow rate, and from this we can calculate the mass flow rate of the stream by multiplying these two values together. For more details, I think the following below attached file may help you in your analysis.