Dynamic optimization of an Intensive Energetically Integrated Large-Scale Process

摘要

In this work we propose a first principles dynamic optimization model for an intensivernenergetically integrated process, a natural gas processing plant, within a simultaneousrndynamic optimization framework. We have developed rigorous models, includingrnthermodynamics with a cubic equation of state, for separation tanks, distillationrncolumns, turboexpanders and cryogenic countercurrent heat exchangers with partialrncondensation. The resulting partial differential algebraic equation system is transformedrninto an ordinary differential algebraic equation one (DAE) by applying the method ofrnLines for the spatial coordinate. The high integration between process units as well asrnpath constraints have been efficiently handled by a simultaneous dynamic optimizationrnapproach in which the DAE is transformed into a large nonlinear programming problemrnthrough orthogonal collocation over finite elements in time and solved with an interiorrnpoint algorithm. In the case study, we maximize ethane recovery under a ramp changernin natural gas feed flowrate. The model provides temporal and spatial profiles ofrncontrolled and manipulated variables that are in good agreement with plant data.