Abstract: A management system for improving operation of a plant. A server is coupled to the management system for communicating with the plant via a communication network. A computer system has a web-based platform for receiving and sending plant data related to the operation of the plant over the network. A display device interactively displays the plant data. An optimization unit is configured for optimizing at least a portion of a refining or petrochemical process of the plant by acquiring the plant data from the plant on a recurring basis, analyzing the plant data for completeness, correcting the plant data for an error. The optimization unit corrects the plant data for a measurement issue and an overall mass balance closure, and generates a set of reconciled plant data based on the corrected plant data.