(420e) Simulation and Optimization for Product Loss Reduction in a Chemical Plant

The hydrogen/methane separation section is the coldest section in an ethylene plant. This section includes mainly two facilities, chilling train and de-methanizer. Chilling train consists of countercurrent multi-stream heat exchangers (cold box) and separation drums. The front-end of this facility is used to liquefy C2+ components from the charge gas and feed them to the de-methanzier. The back-end of chilling train is to split the left charge gas of hydrogen and methane as well as provide cooling duty for the liquefaction in the front-end. De-methanizer is employed to separate methane from C2+ components as the top stream, which is directed to the fuel gas system. If ethylene effluents from the de-methanizer top, it will be accounted as the product loss. Obviously, the hydrogen/methane system is a highly integrated and energy-concentrated cryogenic separation system. Its operation strategy should be optimized to effectively balance the ethylene product loss and the energy consumption. This work employs rigorous simulation, optimization, and principle component analysis method to identify the best operating conditions of the hydrogen/methane system, so as to reduce the ethylene product loss with the consideration of energy consumption. A virtual study shows that the optimized operation based on the developed methods can save millions of dollars per year compared with the original plant operations.