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Design, planning and implementation of the dilution and recycle section of the engineering pilot plant

Sebesta, Radomir (2018) Design, planning and implementation of the dilution and recycle section of the engineering pilot plant. Honours thesis, Murdoch University.

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The Murdoch University Engineering Pilot Plant simulates a Bayer process in which alumina is extracted from bauxite. Water is utilised as the process medium for teaching purposes. Recently, table salt has been introduced into the process for conductivity testing purposes. As the plant comprises of 316 grade stainless steel construction, the presence of salt within the plant presents corrosion concerns. Additionally, the Water Corporation advises that a maximum of 20,000 g/L of total dissolved solids inclusive of salts, can be sent to drain as a result of plant activities.

The design and planning of the dilution and recycle section of the Engineering Pilot Plant was successfully completed. This allows the salt concentration to be diluted within a holding tank arrangement attached to the current output of the pilot plant, before being pumped to drain. This is only possibly when below permissible limits. If further dilution is required, the recycle stream is employed to recycle product within this arrangement until the desired concentration is achieved. This provides a feasible solution to these problems. Additionally, an operational Foundation Fieldbus communications network was established within the plant to provide future students with alternate means of plant communications.

In the absence of an implemented dilution and recycle section addition to the plant, a process model was derived from fundamental principles instead. An overall mass balance and salt component balance were utilised for this purpose. Differential equations were then derived. A simulation based on these equations was then implemented via Mathwork’s simulation program, Simulink.

The method of direct synthesis was then used to derive both Proportional and Proportional and Integral controllers. Both types of controllers were then applied to both of the desired process variables: holding tank level and conductivity. The performance of each controller was assessed for set point tracking and disturbance rejection capabilities using both statistical process control and integral error criteria. The PI controller was found to have the most desired system response for both level and conductivity.

A fully operational Foundation Fieldbus network was also successfully established within the pilot plant. This entailed the use of a Fieldbus interface module, power conditioner, segment coupler and a Foundation Fieldbus instrument in the plant. This network will provide future students with the option of utilising a new communications network with diagnostic capabilities for future plant and instrument implementation.

Item Type: Thesis (Honours)
Murdoch Affiliation(s): School of Engineering and Information Technology
Supervisor(s): Cole, Graeme
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