Multivariate statistical process analysis systems and methods for the production of melt polycarbonate

A computerized system for the production of melt polycarbonate, comprising:

• a plurality of sensors operable for obtaining a plurality of measurements relating to a plurality of predetermined process variables;
• wherein the plurality of predetermined process variables comprise process variables selected from the group consisting of molar ratio, adjusted molar ratio, catalyst concentration, flow rate, vacuum, temperature, torque, discharge pressure, melt viscosity, stirring speed, throughput, and pellet speed;
• a preprocessor having a scaling algorithm, operable for preprocessing each of the plurality of measurements for multivariate statistical analysis;
• an identifier having a pattern recognition analysis algorithm, operable for identifying which of the plurality of predetermined process variables affect each of a plurality of predetermined product variables, individually and in combination;
• a correlator having a correlation analysis algorithm, operable for correlating the plurality of predetermined process variables and the plurality of predetermined product variables, individually and in combination;
• a model generator having a multivariate calibration algorithm, operable for modeling the relationship between the plurality of predetermined process variables and the plurality of predetermined product variables;
• and
• an analyzer having a multivariate control chart algorithm, operable for analyzing the plurality of predetermined process variables to ensure that the value of each of the plurality of predetermined process variables is within a predetermined range.

A computerized method for the production of melt polycarbonate, comprising the steps of:

• obtaining a plurality of measurements relating to a plurality of predetermined process variables;
• wherein the plurality of predetermined process variables comprise process variables selected from the group consisting of molar ratio, adjusted molar ratio, catalyst concentration, flow rate, vacuum, temperature, torque, discharge pressure, melt viscosity, stirring speed, throughput, and pellet speed;
• preprocessing each of the plurality of measurements for multivariate statistical analysis;
• identifying which of the plurality of predetermined process variables affect each of a plurality of predetermined product variables, individually and in combination;
• correlating the plurality of predetermined process variables and the plurality of predetermined product variables, individually and in combination;
• modeling the relationship between the plurality of predetermined process variables and the plurality of predetermined product variables;
• and
• analyzing the plurality of predetermined process variables to ensure that the value of each of the plurality of predetermined process variables is within a predetermined range.

A computerized method for controlling the process for the production of melt polycarbonate, the method comprising the steps of:

• measuring the process for the production of melt polycarbonate with a plurality of sensors, the plurality of sensors operable for collecting data representative of a plurality of predetermined process variables and a plurality of predetermined product variables;
• wherein the plurality of predetermined process variables comprise process variables selected from the group consisting of molar ratio, adjusted molar ratio, catalyst concentration, flow rate, vacuum, temperature, torque, discharge pressure, melt viscosity, stirring speed, throughput, and pellet speed;
• generating a surrogate variable, using a computer in communication with the plurality of sensors, the computer having software operable for performing multivariate statistical analysis, the surrogate variable having a value representative of a control state of the process for the production of melt polycarbonate, the surrogate variable further being a function of a plurality of intermediate variables, each of the plurality of intermediate variables being a weighted function of the plurality of process variables and the plurality of product variables;
• determining which of the plurality of intermediate variables primarily contribute to the value of the surrogate variable when the value of the surrogate variable is outside of a predetermined limit;
• identifying which of the plurality of process variables primarily contribute to the value of each of the plurality of intermediate variables;
• and
• modifying the process for the production of melt polycarbonate to change each of the plurality of process variables such that the value of the surrogate variable is brought within the predetermined limit.