On-line correction of process temperature deviations in continuous retorts

Two algorithms, the fixed point (FP) and the worst case (WC), were developed for correcting on-line process temperature deviations in continuous retort operations through the adjustment of the product residence time, which could be performed by changing either the conveyor speed in hydrostatic retorts or the rotation speed in rotary retorts. After a process temperature deviation occurs, the FP algorithm consists in the selection of a point, for convenience close to the retort steam chamber exit, where process sterility is calculated, so that the product residence time can be changed accordingly. Alternatively, the WC algorithm consists in identifying the worst case, i.e. the more affected, container, for determining a conservative product residence time. Computer simulations showed that both algorithms provided fast estimations of the effect of process deviations on the product temperature and process lethality. This shows the potential of these algorithms for thermal processing industrial applications that may require on line control. © 2007 Elsevier Ltd. All rights reserved.