Direct mapping of the conservation processes onto executable structure based computer programs has been applied for the dynamic simulation of various chromatographic processes. The method eliminates the many-fold transformation of the conventional modelling from the cognitive model through the mathematical construct and via the numerical algorithm to the computer program. The introduction of the new approach induced also the systematic revision of the measurement technique and those of the applied phenomenological formulae. In the first paper of the series the methodological background of the new tool will be described and illustrated bit a simple example.