Classical 1-D numerical simulations of dryers involve the solution of non linear differential relations which include balance equations and transfer functions : namely, the drying rate equation and the heat transfer equation. These relations are integrated by means of the network theory and a new approach - the Number of Transfer Units method. This process leads to a non-linear algebraic system used to develop computer simulation programs. In this pager, the applications are based on the study of multiple-conveyor dryers. This type of dryer is used for many chemical engineering industrial applications to dry coarse particles (i.e., over 5 to 10 mm) or for fond engineering, Numerical simulations are performed to analyse the drying efficiency of these conveyor dryers. Due to the heat and mass numbers of transfer units and to the network idea, the computer programs run faster than classical ones. This program is involved in the expertise and study of the effectiveness of multiple-conveyor dryers, Some rules of behaviour of conveyor dryers are discussed and may be used in order to improve their design.