NOTE ON THE EFFECT OF RECYCLE ON THE DYNAMICS OF CHEMICAL PROCESS PLANTS

The complex multivariate multiunit problem formulation of analyzing th e effect of recycles on the dynamics of chemical process plants is con sidered in this Note. Based on the notion of exchange plants and resul ts on conservation matrices, the effect of connections, such as recycl es and external sources, such as chemical reaction, heating/cooling et c. is analysed. It has been found that exchange plants are not unstabl e, regardless of the connections of their operating units. If constant total flow is maintained through each unit then an increase of all ki nds of connections including recycles at the expense of an external st ream may move the eigenvalues of the plant towards the instability reg ion. This effect can cause stable nonexchange plants to become unstabl e.