Measurement uncertainty in integrated control and process design—A case study

Measurement uncertainty may be a decisive factor on the structure of process and control flow sheet design: e.g. whether a controller can achieve required level of disturbance attenuation or whether costly process equipment needs to be included. However, the effect of measurement uncertainty on the process performance is rarely if ever discussed. In this paper, we illustrate through a case study, how the control structure design is affected by measurement uncertainty and how the corresponding dynamic problem is defined and solved with rather regular tools. Our case is a conceptual and simplified paper machine short circulation control design, which involves defining a dynamic design optimization problem with scenarios on dynamic effects external to the process. With the case, we also want to illustrate that in practical design the choice of dynamic scenarios, their relative frequency of occurrence and even the objective function are far from being self-evident. These choices affect strongly the outcome of optimization. Therefore, scenarios and objective function should be understood more as advanced design tuning parameters rather than strictly given design requirements derived from business analysis.