This book is intended to simulate model for the gas absorbers in LNG facility for removing of CO2 using aqueous solution of DGA. The objective of this work is to present a Mathematic based on the Quantity approach using Calculations, which can be used to design an acid gas absorption tower using aqueous solutions of DGA. The Mathematic is based on Total calculation, Rich amine CO2 loading and product specification is studied. The Mathematic is essential for process simulation during the normal operation and in the design stage of gas treating operation.