There are many factors driving the global increase in the use of computational fluid dynamics (CFD) in the chemical & process (CP) industries over the last 5 years. Key factors include the increased drive for cost savings, process efficiency improvements, health & safety compliance, and a need to meet environmental legislation imposed by governments. Initiatives like "Six Sigma" and marketplace corporate mergers and acquisitions force decision-makers to re-evaluate every unit operation in CP plants. Questions being asked are:

• "Can we improve our operating efficiency?"
• "Can we increase process throughput?"
• "Can we reduce planned and unplanned maintenance costs?"
• "Can we meet new environmental and safety regulations?"
• "Can we scale-up new process prototypes effectively?" and
• "Can we troubleshoot flow-related problems in a timely and cost effective manner?"

CFD software has been around for almost 20 years and has moved from an esoteric R&D "plaything" to an easy-to-use design and analysis tool. This CFD revolution rides on the back of dramatic improvements in computer hardware, particularly machine speed, parallel processors, and memory enhancements.

CFD is a tool for analyzing flow. Most chemical and process engineers are familiar with the Bernoulli Equation as well as heat, mass, and momentum conservation laws. CFD uses computers to solve the fundamental non-linear differential equations that describe fluid flow (the Navier-Stokes and allied equations), for pre-defined geometries and a set of initial boundary conditions, process flow physics, and chemistry. The result is a wealth of predictions of flow velocity, temperature, and species concentrations for almost any piece of chemical and process equipment. Therefore, CFD is a very potent, non-intrusive, virtual modeling technique with powerful visualization capabilities.

"Engineers who scoffed at CFD analysis a year and a half ago now prefer that design changes be evaluated using CFD before being tried in the field. Computer simulation using Fluent's CFD software made it possible to triple the efficiency of equipment design engineers while improving the quality of our product."
Phil Staples
DuPont

Leading chemical and process companies ^1-5 invest $K into training and equipping their engineers to use CFD software in order to improve efficiencies in fluid flow, heat, and mass transfer processes that are common to all CP unit operations. CFD allows CP engineers unprecedented insight and understanding into many plant operations. This facilitates innovative solutions to age-old problems. In the hands of an engineer trained in the use of CFD, the software yields savings in the order of $M in each unit process, because of the large throughput typical of many CP plants. Properly used and validated CFD simulations demonstrate again and again that major financial bottomline and topline benefits can be gained. It allows engineers to move beyond simple rules-of-thumb and empirical correlations to in-depth unit operation simulations that provide comprehensive flow field predictions. This makes CFD an indispensable tool that provides detailed insight into processes and equipment previously considered to be "black boxes".

Many industry leaders have shifted emphasis from traditional physical modeling and trial-and-error troubleshooting approaches to CFD-based strategies. Significant cost savings and revenue increases can be achieved. The table below demonstrates how CFD-based approaches have made a major impact on oil refinery operations. These simulations enable chemical and process engineers to understand and optimize many unit processes.

Recent advances in the field of CFD drive and aid the use of the modeling tool in the CP industries. Fluent has made it possible for its customers to analyze flow problems of greater and greater complexity, such as those involving multiphase flows, mixing related phenomena, intricate equipment geometries, and detailed, chemically-reacting flows all within industrially relevant timescales.

"Using FLUENT we have improved performance of commercial equipment in both single phase and multiphase applications. Positive results of CFD-based hardware designs in areas such as gas-solids mixing, jet dynamics, phase segregation, and combustion, illustrate the rigor of FLUENT's physical models."
Greg P. Muldowney
Mobil Technology Center

CFD is an invaluable computer aided engineering tool for the chemical & process industries. The question being asked now is not "what is CFD and how can it be used" but "why isn't it being applied to various unit operation flow problems?"Frontiers in fluid flow, heat, and mass transfer applications are regularly rolled back and problems that were inconceivable just a few years ago are being solved. It is precisely for these reasons that the technical benefits to engineers and the financial benefits to managers are driving the phenomenal rise in the use of CFD in the CP industries, and it shows no sign of abating in the foreseeable future.

CFD-based strategies allow chemical & process companies to lower costs and improve bottomline and topline numbers through:

• Improved operating performance
• Better unit operation reliability
• More confident process scale-up
• Improved product consistency
• Increased plant productivity
• Deeper technical knowledge and understanding of unit processes
• Lower equipment downtime for maintenance, and
• Compliance with health & safety and environmental regulations.

CP Unit Operation Process Improvement through CFD

REFERENCES

• "Computational Fluid Dynamics: Understanding Unit Operations", Derek A. Colman, BPAmoco Chemicals, PETROLEUM TECHNOLOGY QUARTERLY, Autumn 1999, Vol. 4, No. 3, p75.
• "CFD Hits the Engineer's Desktop", Ken Fouhy, (ed.), CHEMICAL ENGINEERING, Nov 1999, p178, Example from DuPont.
• "Mixing by Model", Peter Hoffman, Hoechst Celanese, OCCUPATIONAL HEALTH & SAFETY, Aug 1999, p110.
• "CFD Reduces Time for Reactor Redesign", CHEMICAL ENGINEERING, Nov 1998, p166, Example from Degussa.
• "Modeling Software Targets Restricted Flow", Dick Jung, Texaco Inc, CHEMICAL ENGINEERING, May 1995, p133.

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