Petrochemical manufacturing is a typical example of a continuous chemical process, which usually involves several interconnected process units. The unit interactions introduce many degrees of freedom for process operation, and also complicate supply chain management. Optimisation is therefore brought in to support decision-making on both process operation and supply chain aspects. In order to enhance operational feasibility and model accuracy, the optimisation should in principle be executed directly in a site-wide fashion and employing igorous process representations. This however results in an extremely large-scale site-wide model. This hinders the continuous process from obtaining the utmost benefit from the optimisation. This thesis hence aims to remove the obstacle by developing a practical direct optimisation method for site-wide supply chain problems. The thesis employed an ethylene process as an example of a continuous process for the solution method development. Based on the process, four types of problems with different complexities were established. They are (i) single-site single-period; (ii) single-site multi-period; (iii) multi-site single-period and (iv) multi-site multi-period. A novel direct optimisation technique, namely gPROMS-Based Application (gBA) Approach, was developed and examined using the example problems. It overcame the difficulty of the large problem size by separating the optiser from the process simulator, gPROMS. This allowed gPROMS to simulate each site and each period in the supply chain one-by-one, and send the required information to the optimiser individually. This avoided computer memory shortage problems, which could be triggered by a simultans optimisation ot the complete supply chain. Other solution approaches were also investigated in the thesis to compare with the gBA approach. For example, Successive Linear Programming (SLP) was used for the single-site single-period problem.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:501426 |
| Date | January 2009 |
| Creators | Cheung, Kwok Yuen |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10044/1/8325 |
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