Mix ADEX Contoller (MAC)
The quality control (QC) modules of the raw mix for the kiln feed in the cement industry can be controlled by proportioning the flow rates of different raw materials such as limestone, sandstone, marl, iron ore and others. The most generally used QC modules, i.e. Lime Saturation Factor (LSF), Silica Modulus (SM) and Iron Modulus (IM), are non linear functions of the concentration in the mix of four metallic oxides (i.e., calcium, iron, aluminium, and silicon), but the concentrations of these oxides in the different mix sources are generally unknown and time-varying. Thus, the cement raw mix process is of a complex, unknown, multivariable, time-varying and non-linear nature. The Mix ADEX Controller (MAC) for the cement raw mix process, is based in the use of ADEX controllers and QC modules measurements, provided by on line PGNAA or XRF systems.
The patented MAC control strategy processes the QC module measurements provided periodically by an analyzer to generate an ADEX control signal for each quality module under control and then, using the said ADEX control signals, computes the flow rate set point values for the different sources of the mix process. This control strategy, for the case in which LSF, SM and IM are the selected QC modules, has been depicted in the attached figure.
Basic MAC features: 1) No need for precise knowledge of the source compositions; 2) no need for controllers tuning; 3) robust control under source compositions discontinuous and stochastic changes; 4) diagnoses of source compositions deficiencies; 5) use of corrective feeders to compensate composition deficiencies; and 6) handles time delays and can manage any number of feeders. These features allow MAC to optimize the use of raw materials. The attached figure shows MAC operator interface.
