The cooperation of quite different engineering disciplines characterize plant design. The layout of chemical plants is a part, where the designer trys to determine an effective layout based on collected principles and experience. Mathematical methods are only the initial position. The main point build up the treatment of empirical basis. This basis is available in chemical engineering. The present work describes a new approach for knowledge-based plant design on empirical basis. The reference model take as a basis both knowledge-based techniques (production rule and frames). Production rules represent empirical engineering rules. Frames describe objects which are components of chemical plants.