Optimal Design and Scheduling of Unsteady State Material Recovery Networks
Rabie, Arwa H.
MetadataShow full item record
This research developed novel methodologies to achieve cost effective solutions to overcome many of the difficulties associated with unsteady state material recovery network synthesis. The work focuses on the development of three different methodologies: the first is a hierarchical multi-step methodology developed for the design and scheduling of batch water (material of interest) recycle networks. A new source- double tank-sink arrangement is introduced to overcome the limitation of samecycle assignment by permitting sources to be optimally recycled within the same batch cycle and/or storing and recycling sources to sinks in the following batch cycle. The problem is solved in interconnected stages. First, network targets such as minimum fresh water consumption and minimum waste water discharge are identified ahead of network design. Once design targets have been identified, an iterative procedure is followed to tradeoff fixed and operating cost to achieve a network design which has the minimum total annualized cost (TAC). The second developed methodology is a one-step simultaneous approach to design and schedule cost-effective batch water recycle networks. A new source-tank-sink representation is developed to embed potential configurations of interest for design and scheduling. As a result, water may be assigned from sources to sinks within the same cycle (with or without a storage tank) and in two subsequent cycles using a double tank arrangement. A mathematical formulation is developed to determine the network design and sufficient information on the scheduling of the network with the minimum TAC in one step. The third methodolgy this research developed is a systematic procedure to schedule the operation of an unsteady state material recovery network. The network has a set design and receives a number of feedstocks (sources) that are to be processed into higher value/quality products. The sources may be stored in tanks, mixed, and/or intercepted in separation devices to produce the desired products while maximizing profits and meeting all process constraints. The developed systematic procedure includes mathematical formulations that allow available sources to be stored, mixed, intercepted and determine the optimal scheduling scheme over time period ??with the objective of maximizing total annualized profit of the network.