Simulation Gets a New Dynamic

Efforts aim to boost the use of dynamic models by process and control engineers.

By Mike Spear

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Beyond training

PSE’s managing director, Costas Pantiledes, characterizes operator training as “a very mature, very steady” market for dynamic simulation. However, he questions whether there is yet a demand for “simple” dynamic simulation. “It obviously has evolved and is being used, but it’s not on every engineer’s desktop and I doubt it will be, as I don’t see the demand for that.” The real value of dynamic simulation, in his view, comes from the complex, very detailed modeling “which tells you things you won’t get just by staring at the problem.”

As an example, he cites the help given by PSE to the BP team investigating the March 2005 explosion at its Texas City refinery. (See CP, Jan., p. 7, for a summary of the final incident investigation report) Working from first principles and with no prior assumptions of liquid and vapor flows in the raffinate splitter believed to be at the root of the accident, PSE’s consultants used gPROMS to develop a high-fidelity model of the tower that showed, against all expectations, that hydrocarbon liquid did in fact overflow the top of the column. “That was a case of dynamic simulation adding value,” Pantiledes says, “in the sense of fully understanding what happened.”

Simulation specialists developed the Texas City model and they too are finding dynamic systems easier to use. “Technologies like gPROMS,” explains Pantiledes, “let you put together models from first principles over a wide range of operations.” And once those models are developed, they increasingly are being used for process optimization. Traditionally, he says, models would have been built for offline design, but working with partners like Honeywell, PSE has been taking the model across the boundary between offline and online applications.

Cal Depew, dynamic simulation product director for the SimSci-Esscor unit of Invensys Process Systems, Lake Forest, Calif., paints a similar picture of dynamic models being put to much wider use. “One of the key trends,” he says, “is that more and more control engineers are now able to use dynamic simulation, because of the improved GUIs [graphical user interfaces], ‘drag and drop’ and interfacing with packages like Excel.” Traditionally, he notes, models would only have been developed for a single purpose <em dash>—<em dash> process design, control checkout or just for an OTS. Now, he notes, a single model can be evolved all the way from a steady-state simulation in, say, SimSci’s Pro/II program, into a dynamic form that can be of benefit in all those applications.

SimSci’s dynamic simulation tool, Dynsim, is powered by the company’s common modeling environment SIM4ME, which provides a consistent look and feel across all its simulation programs. This allows reuse of the same model through multiple stages of the project, Depew says. “Dynsim is a way of bringing the process control department in with the process engineering department, so they can see how the control design and process design interact.”

Other companies expanding their dynamic simulation capabilities include Chemstations, Houston, Texas. The latest release of its ChemCAD Suite boasts a “snapshot” feature for OTS applications. For dynamic simulation, snapshots of the flowsheet taken at any time during the run can then be used afterwards to “rewind” the dynamic time and flowsheet information.

Another firm, Fantoft Process Technologies, Sandvika, Norway, although more involved in upstream OTS applications in oil and gas, has recently been making inroads into the chemical industry with its D-SPICE dynamic simulator. Jan Eckhoff, president of the company’s Houston-based U.S. operation, notes that Bayer recently has taken out several licenses for the software and Shell has just ordered an OTS system for its Norco olefins complex at St. Charles, La. — the fourth such full-scope OTS that Fantoft will have supplied for ethylene plants.

Eckhoff notes that in the past D-SPICE was considered to be the type of simulator that Fantoft itself would engineer, building the models and then delivering the OTS. But the software now has evolved so that third parties like Bayer can do the modeling and simulations themselves.

Plug and play

The goal of allowing third-party model developments to integrate more easily with the big commercial simulators lies behind the work of the CAPE-OPEN Laboratories Network (CO-LaN), headquartered in Rueil-Malmaison, France, and supported by most of the major simulation vendors and operators such as Total, IFP, BASF and BP. (For more on CO-Lan, see http://www.chemicalprocessing.com/articles/2005/510.html.) Gilles Hameury, marketing manager for simulation and optimization company ProSim, Labege, France, says the CO-LaN “component software” approach allows users to assemble only those components needed, and so to reduce costs.

ProSim’s Simulis Thermodynamics software is a case in point, permitting users to generate their own “property packages” to plug into the simulators.

ProSim recently organized a CO training session for specialty chemical producer Rhodia, Paris, France, which CO-LaN’s chief technology officer, Michel Pons, says is a clear sign that industrial users are “increasingly integrating CAPE-OPEN standards into their software considerations.”

Reactions on the vendor side remain mixed, however.

Honeywell’s Henderson sees it “as a great opportunity for the end user, allowing our customers to integrate their own technologies into the simulations.” Depew says SimSci is committed to making Dynsim compliant with the emerging CO standard for dynamic unit operations once CO-LaN members agree upon it. PSE’s Pantiledes notes, “it’s a useful technology that in a few years may be taken for granted.”

For now though, Pantiledes does express some reservations, saying CO doesn’t really go much below the unit-operations and thermodynamics level. “It makes life easier,” he says, “but it doesn’t help in making the model in the first place.” And AspenTech’s Dissinger thinks that other developments, by Microsoft with OLE, have provided alternative ways of integrating applications and models. However, he emphasizes that AspenTech does support the CO interfaces with all its steady-state and dynamic simulation tools.

The simulator companies might be rising to Weinstein’s challenge to make their dynamic products easier for non-specialists, but there’s still a long way to go before ordinary process and control engineers use such software routinely.

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