Chemical Processing - June 2008 - (Page 22)

tHe use of models in plant opeRations type of model Traditional process simulations off-line process models used for Troubleshooting, debottlenecking, process revamps supporting operational decisions, advising operations, reconciling plant, mass balances, calculating product properties, training process staff calculating and advising on optimal plant operating conditions to maximize financial performance as for open-loop models description Used by plant-based engineers on an “as required” basis to support plant operations Used daily, weekly or whenever needed Typically have a customized user interface in Excel or Visual Basic may link to some real-time data initiated by a person Typically used each shift, daily automatic model execution person accepts or rejects any operating advice interface directly with plant control system and adjust the process automatically real-time open-loop models real-time closed-loop models Table 1. Real-time models are more capable but take more effort to make robust. • for moving rigorous analytical models into the operating environment. The effort required to build discipline-specific and plant-specific models coupled with the need to hide the complexity of these models from people performing specific roles have driven innovations in modeling tools. Here are some key developments: Modularized systems. Process modeling systems can be redesigned for re-use in a modular fashion throughout an asset’s lifecycle. One example is the physical properties database. AspenTech now offers its as a re-usable resource, a “standardized component” for a number of different model-based applications. This ensures maximum flexibility and consistency regardless of choice of modeling tools. Another example is the unit operations models. These can be modularized so they are usable by systems ranging from simulation, basic engineering, optimization, economic evaluation to advanced process control. User console and simplicity. New concepts build the workflow right into the user interface — presenting the appropriate analytical models and tools to users depending upon their role, the phase of a project and their position in the workflow. Models in engineering. This enables calling models from downstream in the design process, including basic design, start-up and control (without looping back to the modeling group). Modeling can be performed in-plant without intervention by design engineering. Common engineering data backbone. A lifecycle database incorporates unit operations models, process, equipment and instrumentation data and control information to facilitate lifecycle optimization. Realize Real benefits to developments that make these analytical models usable by other disciplines and plant staff. This is leading to measurable savings in dollars, energy, time and staffing. Future work by software innovators will lead to the modularization of unit operations models and increased ease of use and integration of work processes. Rigorous models are destined to become even more widely used and more valuable tools in the operation and optimization of process facilities. Rob Hockley is a Warrington, U.K.,-based senior consultant for Aspen Technology, Inc. Ron beck, is marketing manager for Aspen Technology in Burlington, Mass. E-mail them at rob. hockley@aspentech.com and ron.beck@aspentech.com. RefeRences 1. mullick, s. and V. Dhole, “consider integrated plant design and engineering,” p. 81, Hydrocarbon Proc. (Dec. 2007). 2. lofton, W. and l. Dansby, “adding value by integrating process engineering concepts and cost estimating,” presented at aspenWorld 2002 conference (oct. 2002). 3. Wiesel, a. and a. polt, “paradigm shifts in conceptual process optimization,” aspenTech User group meeting, Frankfurt, germany (apr. 2007). 4. Donkers, m., “runaway reaction hazard assessment within shell international chemicals,” available online at www.safetynet.de. 5. cox, r. et al., “can simulation technology enable a paradigm shift in process control? modeling for the rest of us,” p. 1,542, Computers & Chem. Eng. (sept. 12, 2006). 6. pres, r. and p. s. peyrigain, “minimizing VDU heat exchanger fouling through application of rigorous modeling,” presented at aspen hTFs annual User group meeting, cologne, germany (Dec. 2006). 7. griffith, J. et al., “advances in front-end engineering workflow and integration,” p. 32, Hydrocarbon Eng. (Jan. 2008). Process engineering models created during conceptual design increasingly are being applied downstream in the design process and operations, thanks JUNE 2008 chEmicalprocEssiNg.com 22 http://www.safetynet.de http://chemicalprocessing.com

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Chemical Processing - June 2008 Contents From the Editor ChemicalProcessing.com Field Notes In Process Energy Saver Compliance Advisor Achieve Model Operations Bolster Your Condition Monitoring Toolbox Particle Analysis Makes Solid Progress Improve Batch Reactor Temperature Control Improve Your Job Security Plant InSites Process Puzzler Equipment & Services Product Spotlight/Classifieds Ad Index End Point

Chemical Processing - June 2008

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