This article shows the interest and the benefit of hierarchical control through a typical example as applied to a gas plant. After a description of the hierarchical control principles, the plant is presented to highlight the interest of such an approach. The implemented control architecture consists of regular controllers and two Model Based Predictive Control algorithms (MONOREG and IDCOM-HIECON) whose capabilities were helpful in this application. The implementation of these algorithms follows several steps which make use of the corresponding CAD tools. The performance is evaluated in different operating conditions, once the designed controllers are installed on the process computer.