The present invention is related to a method for determination of unit operations of a chemical plant for acid gas removal, the method carried out by a computer or a distributed computer system and the method comprising the steps of: providing a first set of parameters for the unit operations; providing a second set of parameters for the unit operations based on the provided first set of parameters and based on data retrieved from a database; determining a digital model of the chemical plant based on the first set of parameters and the second set of parameters, wherein the digital model comprises a system of equations defining the unit operations of the chemical plant; selecting starting points for an equation-based solution method of the system of equations, wherein the starting points are at least partially selected from the: (i) the first set of parameters; (ii) the second set of parameters; and (iii) the data retrieved from the database; determining resultant settings for the unit operations of the chemical plant using the equation-based solution method for the system of equations initialized by the selected starting points.