Energy cost minimization and data reconciliation

Abstract

Gas separation plant was studied for energy analysis because it consumed a high energy. This plant consists of three main distillation coumns (demethanizer, deethanizer and depropanizer) and ten heat exchangers. First of all, the process values, are needed to be measured and collected. The simulation used for this research because there were not enough measured data to appl energy saving technique. The commercial sftware, Aspen Plus, was used to run to run to figure out the unmeasured values. Grand Composite Curve (GCC) and Column Grand Composite Curve (CGCC) were plotted in order to study the integration between the columns and the process. To modify the process, retrofit techniques such as inspection and integration were presented. Four alternatives were proposed and the results showed that the largest energy saving (alternative number three) was 36.96% of total steam consumption and 26.14% of total cooling water consumption. This alternative was done by adding side reboiler at the deethanizer coumn that used hot stream of the background process to recover the heat. The consequent results would be energy saving on both the cooling water load of E70601 and the main reboiler duty of the deethanizer column. The process modifications were based on the possibility of changing existing plant. Data reconciliation is the technique for ensuring the reliability of measurement. This plant contained 20 measured and 170 unmeasured variables. Based on the energy and material balance, 30 reconciled variables were given.