Dryspec2: a computer model of a two-stage dryer

Dryspec2 (DRYer System for Property and Energy Control) is an interactive computer program for use in making calculations relative to a two-stage dryer for dairy products. The program indicates the relationship between the energy consumed by the drying process, the process parameters and the properties of the raw material and of the powder produced. To develop Dryspec2, simple model representations of both drying stages were made. Moreover, known physical relations were used to the maximum possible extent. Sorption isotherms form an essential part of the total drying model. The model can be attuned to the situation prevailing in actual practice by taking two model parameters of the first drying stage and one parameter of the second drying stage from data associated with the drying installation concerned. This gives the model a high degree of flexibility. Dryspec2 can be applied for such purposes as finding the optimum process conditions needed to produce a powder that must satisfy specific quality requirements at the lowest possible energy consumption. Dryspec2 is also suitable for use in designing or modifying a spray drying plant. Incorporation of the drying model underlying Dry spec2 into on-line process control is currently under development.