Patent ID: 7567856

Claim:
A method of operating a computer control system for a mixing vessel to determine an estimated volumetric ratio of a material to total materials in a mixing vessel, comprising: summing a commanded input flowrate of the material and a volumetric disturbance flowrate of the material being fed to the mixing vessel; estimating the output flowrate of the material exiting the mixing vessel based on the summed commanded input flowrate and the volumetric disturbance flowrate; negatively feeding back the estimated output flowrate of the material to obtain an estimated volumetric rate of change of the material in the mixing vessel; and integrating the estimated volumetric rate of change of the material to compute the estimated volumetric ratio of the material to the total materials in the mixing vessel; wherein the mixing process computer control system controls the mixing process volumetrically utilizing the estimated volumetric ratio of the material to control at least one input valve.