Patent ID: 7356427

Claim:
A system for estimating nominal fluid heights in a series of two mixing tanks having one or more input rates into the first tank, an intermediate flow rate from the first mixing tank into the second mixing tank, and one or more output rates out of the second tank, the system comprising: a dynamic control device with a feedback estimated height of the fluid in the second mixing tank and a measured height of the fluid in the second mixing tank, wherein the dynamic control device compares the feedback estimated height of the fluid in the second mixing tank with the measured height of the fluid in the second mixing tank to obtain an estimation of a height error, the height error being iteratively recomputed and used in conjunction with the one or more input and output rates to drive the estimated fluid heights in both the first mixing tank and second mixing tank to nominal fluid height values; a dynamic model device of the two mixing tanks including an estimating function of the intermediate flow rate from the first mixing tank into the second mixing tank; and a derivative control component comprising a positive feed derivative control loop, wherein the positive feed derivative control loop includes a derivative gain receiving the height error and feeding a height error signal into the dynamic model device for estimation of an estimated height of the fluid in the first mixing tank.