Print page

Email page

Achieve model operations

By Rob Hockley and Ron Beck

ChemicalProcessing.com

Plants can solve a range of problems by leveraging design models

Engineering models can play a significant role in improving plant efficiency and safety. Software modularization, user interface innovation and computing power increasingly open up opportunities for models in operations.

This growing potential makes it even more critical to re-use the same models to solve different problems across the asset lifecycle and at different levels of granularity in operations. After all, a simulation that reliably predicts a particular application and situation becomes much more valuable if it can be applied to all tasks that require modeling of that unit or process. Indeed, the broader use of these models promises to have a profound business impact. So we’ll describe current trends toward re-use of models and the integrated workflows that result.

First, though, let’s set the stage by briefly summarizing the business challenges that are spurring the use of modeling technology to address a complete plant lifecycle:

• Pressure of global competition imposes the need to accelerate engineering, reduce capital costs and optimize operations. This increases the value of having one common set of models that can be used from process synthesis through to plant operations and debottlenecking.
• Rapidly rising cost of energy and secondary cost of greenhouse gas emissions require the redesign and optimization of processes. Models suitable for use by design, plant engineering, compliance and operations groups are a key tool.
• Shortages of skilled veteran engineers will continue over the next decade. Effectively transferring optimization expertise to new staff demands increasingly powerful and easy-to-use models that capture organizational knowledge and experience.

These challenges call for moving to common models to solve multiple problems, making models simpler to use, and integrating models with other software to solve broader business problems. Today’s integrated modeling tools already attack many of these areas and the technology continues to evolve.

Key trends in modeling

Figure 1. Process models can play an important role in all four phases.

1. Initially modeling tools were developed to solve specific problems such as energy analysis, heat exchanger design, dynamic analysis and cost estimation. Next industry began to build links between these individual tools so they could share information and data. Then, with development of process data models and modularized tools, links evolved into real integrated process simulation workflow (Figure 1). This integrated approach yields time, cost and quality benefits. (Such streamlined workflow also offers advantages to engineering firms, which face increasing pressures to efficiently execute projects with fewer engineers. [1])
2. Process models originally developed for front-end engineering design (FEED) now are being used in plant operations. Owner-operators increasingly rely on models to support operating decisions, to optimize processes in real-time and to improve the accuracy of planning systems.

Let’s look at some ways integrated modeling now is providing value:

Simulation/economics work process. The integration of economic analysis with the basic process development activity yields sizable benefits. Process engineers don’t need to wait until a formal package is handed over to the estimating department before gaining accurate understanding of the economic trade-offs between alternative designs. Process costs are calculated and optimized concurrently with the conceptual process development, allowing the engineers to better understand the economic impact of their design decisions.

Fluor, which calls such integration “cost optimized design,” cites a number of benefits [2]. These include the ability to focus on technology/cost trade-offs early, improved quality of estimates and better cost awareness during design.

BASF estimates it saves 10% to 30% in capital costs and up to $2 million/yr. in energy through its i-TCM (intelligent Total Cost Minimization) project approach, which involves performing process simulation, cost analysis and equipment modeling in parallel [3]. The goal is to optimize capacity, reduce operating costs and develop better designs for new or revamped plants.

Design/operability workflow. The use of dynamic models for safety and operability analysis is another advance. This clarifies whether a design simulation solution is stable under real-world dynamic conditions. The goal is to use the same unit operations models for both steady-state and dynamic analysis, avoiding having to develop the models again.

Shell Chemicals takes this approach to model reactor and relief systems to ensure that designed safety systems will be able to contain any runaway reactions. This application of dynamic modeling improves operations safety and reliability and saves operating costs through optimized normal operations [4].

Conceptual/basic/detailed engineering workflow. Integrated basic engineering represents another area where workflows have advanced. The heat and material balance and flow sheets from simulation studies are directly input into the basic engineering process, where multiple disciplines define the FEED and then pass that information to detailed design.

WorleyParsons, by linking together process simulation, basic engineering and detailed design, achieves an estimated 25% increase in engineering efficiency and 50% reduction in time for basic engineering [5].