A new method is proposed for solving the multicomponent gas absorption problem, where an infinite number of plates is assigned in the column. The method uses the concept of hypothetical pinch plate, which is used in solving the minimum reflux problem of nonideal multicomponent distillation.⁸),⁹⁾ In this problem, a real pinch point exists in the middle part of the column and, therefore, two ... [Show full abstract] hypothetical pinch plates are assumed to stride over the real pinch point. Figure 1 shows a physical picture of the present model, where an infinite number of plates is assigned between the hypothetical pinch plates, and a finite number of plates is assigned between the two hypothetical pinch plates and the upper and lower ends of the column, respectively. The temperatures and molar flow rates of each component in gas and liquid leaving the hypothetical pinch plate are assumed to be equal, respectively, to those of the real pinch point (see Eq. (1)). The proposed method here is applied to the following cases, which are classified according to conditions of inert gas in the rich gas and inert oil in the lean oil. [Case 1] The case with inert gas and inert oil. [Case 2] The case with inert gas but without inert oil. [Case 3] The case without inert gas but with inert oil. [Case 4] The case without inert gas and inert oil. Flow charts for the calculation are shown in Figs. 2-a~d, characterized by the following items; (i) For cases  and  the calculation starts from a set of assumed value of gas composition in the pinch point. (ii) For cases  and  the calculation starts from a set of assumed value of liquid composition in the pinch point. (iii) For all cases the normalized θ-method⁴),⁷⁾ is used for correcting the assumed values of gas and liquid composition on the hypothetical pinch plates. Table 1 shows the operating conditions for the examples. In Table 2 the constants necessary for predicting physical properties of components are given. Tables 3 and 4 show calculated molar flow rates and temperatures of the gas and liquid leaving the column and in the pinch point (i.e. hypothetical pinch plate), respectively. From these calculation results it is demonstrated that the proposed method provides stable solutions as well as wide range of application to multicomponent gas absorption problems where an infinite number of plates is assigned to the column. The solution obtained here may be used to predict a minimum rate of lean oil necessary for a specified recovery of a component in the rich gas.