Abstract
The principles of blending control are explained with particular reference to a control scheme currently being implemented by G.E.C. Computers & Automation Ltd. for Skanska Cement AB at their Limhamn cement works. The control principles can, however, be applied to other blending plants.
The Limhamn blending process is briefly described in order to give an appreciation of the control problems involved. The computer, instrumentation and X-ray analysing systems are outlined.
The iterative optimiser is explained. This calculates set points for the material flows which, when implemented, result in manufacture of slurry with correct chemical composition at minimum cost.
On-line regulating techniques which control the blending machinery are described. The regulating programmes maintain material flows at their calculated set point values. They also control water addition in order to keep slurry water content constant.
Distinct advantages are to be obtained by the separate implementation of the optimising calculations or the regulating control, but the two are complementary, and to obtain maximum benefits, a computer control scheme should include both.
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