E.i. Dupont De Nemours and Company

E. I. Du Pont De Nemours + Company

David V Cardner

The present invention is a system and method for improved processing of flow data signals to provide output flow data signals which better approximate the true flows being measured. The general approach on which the invention is based is commonly known as flow data reconciliation. A dynamic simulation is run in parallel with a flow data reconciliation, and model predicted flows are used to complete balances wherever sensor measurements are unavailable. Model predicted compositions are also used to allow the computation of stream enthalpies so that enthalpy balances can be used in the reconciliation. The use of model predicted values of changes in inventory allow dynamic material balances to be used, making the reconciliation much more effective for processes with slow dynamic behavior. Weighting factors on sensors, computed based on the current value of the error of the sensor, reduce the impact of sensors with high errors. A multiplicative correction factor distributes corrections more evenly among streams with large and small flows. Statistical behavior of historical performance of sensors is used to reduce the adverse impact of rapid shifts in sensor accuracy and to detect unconverged reconciliation solutions.

System and method for improved flow data reconciliation

The present invention is a system and method for improving stream composition and/or product property estimates from process models, which better reflect the true conditions of the process. One or more process simulation models are run on a computer in parallel with the actual process to provide estimates of stream composition and/or product properties to be used to control the process. Adjustments are made to the models to maintain them in alignment with continuously measured key process variables that are closely related to stream composition and/or product properties where such a relationship exists. This greatly improves the ability of the model to track the actual process. Additional adjustments are made to both the models and to the model estimates based on differences between measured and calculated stream composition/product properties. The combination of model calibration adjustments and direct correction of model estimates greatly improves the accuracy of the stream composition/product property estimates. Adjustments are made to model input variables and model parameters through use of controllers acting on the difference between measured and calculated properties. Differences obtained using relative error or the logarithm of the ratio of the measured and calculated values produce improved adjustments of component concentrations at low concentrations. Artificial measurements of stream composition and/or product properties can be synthesized by combining model composition estimates and flows at two or more locations in the process with an analytical measurement to produce and artificial analytical value at a second location in the process.

Growing community of inventors

Orange, TX, United States of America

David V Cardner