April 2007 Archives

There has been quite a bit of lively discussion around comparisons with HART and Foundation fieldbus. The first item someone pointed out to me was a paper done by Jim Russell, the Chair of Australia's Foundation Fieldbus End User Council, entitled HART v FOUNDATION FIELDBUS - THE FACTS and THE REAL DIFFERENCE. It compares from a strong Foundation fieldbus perspective as indicated by:

Don't believe all the "hype" given out by manufacturers, especially those that tell you that you can get everything provided by Foundation Fieldbus with HART.

Then John Rezabek wrote a piece for ControlGlobal.com entitled, Users driving the bus. He created a stir with these words:

Newer HART I/O promises support for FF-like diagnostics, but some end users feel they're getting a smokescreen when they ask suppliers to clarify the real capabilities and limitations. DCS vendors, eager to win upgrade jobs in brownfield sites, should be telling their customers how much of the installed base of HART devices will need upgrades to support the watered-down, fieldbus-like diagnostics.

Walt Boyes in his Sound Off blog wrote a post A Word from Ron Helson at HART. Ron responds:

The statement about "watered-down, fieldbus-like diagnostics" is also very ironic and misleading. Contrary to the implication, the fact is that all HART-enabled devices - dating back to the early 90's - contain device status and diagnostic information that is easily used by today's HART-enabled automation and I/O systems without any upgrade to the device. Users evaluating their automation system and field communication protocol options must consider many issues including; device replacement, training, project risk, infrastructure upgrades, automation and I/O system upgrades and others. In many cases, total cost vs. benefits have shown HART to be the most cost-effective option.

The discussion continued with a response posted by John Rezabek.

I thought I'd take a different approach and look at what the protocols were designed to do, and how those original design goals influence protocol functionality. Emerson's Tom Wallace recently wrote a white paper entitled, Functional Comparison of HART and FOUNDATION fieldbus. It comes right out by describing the different design objectives of the two technologies.

Prior to digital communications protocols, 4-20mA analog transmitters required multimeters and screwdrivers to adjust potentiometers to range transmitters. Other potentiometers adjusted calibration, zero settings, and damping factors. Signals drifted and required constant maintenance. Electrical interference causing offset were other issues which required maintenance attention.

In the whitepaper, Tom summed up the HART design objectives this way:

When devices became smart, better ways to configure, calibrate, maintain devices, and communicate the process variable became possible. The HART protocol was developed to address this problem set. It had one huge market adoption advantage over other protocols of the day, in that it was not intended to solve all the problems of analog. Process control was still expected to be done from the 4-20 mA signal. Although this solution was technically inferior to a fully digital protocol, it maintained compatibility with the entire control system infrastructure installed in the field. HART was extended to provide the process variable digitally, but this capability is largely unused.

And the Foundation fieldbus design objectives:

FOUNDATION fieldbus was designed to support all the configuration and maintenance capabilities of HART and more. It was designed to be a completely digital process control network capable of being the control system. It does all the things that a regulatory control system does. It is deterministic and real time, handles alarms and alerts, has trending capability, provides the function blocks used for basic and advanced regulatory control, and the sequencing and logic associated with it. To accomplish this larger set of goals, it needs to support more robust messaging and processing power.

In addition, FOUNDATION fieldbus was designed to support all the configuration, calibration, diagnostics, setup, and maintenance activities associated with both devices and the control strategy.

The whitepaper goes on to compare various attributes including:

• Compatible with 4-20 mA control host
• Compatibility with existing control wires
• Communications robustness
• Multivariable capability
• Control via digital signal
• Control/calculation capability
• Accuracy, Stability, and reliability of the process variable
• Availability of process control
• Alarms and alerts
• Ability to access and deliver diagnostic information
• Compatibility with existing knowledge base and work practices

The bottom line is that both HART and Foundation fieldbus continue to provide value for process manufacturers and continue to improve, taking advantage of advancements in technology. As such, Emerson continues to invest in both these communications protocols and take advantage of the rapid advancements in technologies brought to us courtesy of Moore's Law. The different initial design objectives shape what capabilities each protocol can deliver now and in the future.

I caught up with Riyaz Ali who is in our organization managing Emerson's Fisher brand of valves and regulators. You may recall Riyaz from some earlier posts on safety valve local control panels, partial-stroke test in safety applications, and testing safety solenoid valves.

Riyaz has been hearing more and more questions from process manufacturers, consultants, integrators, and other automation professionals about the adoption of the IEC 61508 and IEC 61511 international safety standards. These questions tend to get very specific about the safety integrity levels (SIL) for the components within the Safety Instrumented Function (safety loop.) Today all components of the safety instrumented function (SIF) including the logic solver, sensor, and final control element may have microprocessors that can perform self-diagnostics and communicate these diagnostics digitally to the logic solver.

Riyaz wanted to help clarify some questions on SIL ratings and field devices. If a process manufacturer hears that that field device is "SIL 3-rated" in accordance with IEC 61508, this is not the case. Field devices alone are not capable of a particular SIL rating.

These devices may be suitable for use in a SIL 3-rated safety instrumented function. In other words, this SIL rating applies to the entire loop and not the individual components within the loop.

The second key point Riyaz made with me is that a single microprocessor-based device (categorized as Type B in the IEC 61508 part 2, table 3) cannot have suitability for use in a SIL 3 safety instrumented function without additional hardware fault tolerance per these IEC standards.

Obviously, there is quite a bit to these safety standards and their application, and I hope some of these blog posts on the topic of safety help you in your adoption of these standards in your facilities.

I had mentioned in an earlier post that short screencasts are a great way to quickly convery ideas in lieu of hundreds of words. One of Emerson's product application specialists, Rune Reppenhagen, graciously agreed to demonstrate how advanced diagnostics can be used in automation system control strategies.

Today's example shows how air in a fluid can impact Coriolis flow measurement and cause the automation system control strategy to falsely assume it needs to increase the speed of a pump to try to raise compensate for the low flow measurement. This situation called entrained air or slug flow causes the measurement on the coriolis meter to go to zero. The actual flow is OK but the problem is with the measurement.

Rune demonstates in this screencast (runtime: 4:51) how advanced diagnostics like those found in Micro Motion Elite mass flow and density meters can be configured in systems like the DeltaV system to read these diagnostics and take action in the control strategy to turn the loop to manual control for the operator and notify him of the cause of the situation.

This immediate recognition of a process problem and operator notification of the situation is one example of how advanced diagnostics and digital communications protocols like Foundation Fieldbus provide ways for process manufacturers to avoid losses in production, quality excursions, and abnormal situations which can impact the efficiency of the production process.

I caught up the other day with Michael Barrett who manages some of Emerson's relationships with providers of production management software like OSIsoft.

Michael strongly believes that production management is a key success factors for process manufacturers competing in a global market. He defines production management as the area of management information systems that work with the planning and scheduling applications that drive the manufacturing operations in a Continuous Improvement Loop. This supports a company's Supply Chain Management by insuring the availability of right product at right time at the lowest cost.

As an example, Michael cites a refiner who imports heavy crudes. They may have several locations to decide where to process it. The refinery ultimately receiving this heavy crude must ensure that they have available tankage to receive the crude, processing capacity to run it and logistics capability to handle the products. They must also make sure they are receiving precisely the quantity for which they are being invoiced. One of the challenges is accurate measurement of water in the crude receipt. If a refinery needs to wait on a 2MM Barrel parcel to let it settle in a tank to accurately measure water--that takes time and at the current price of crude is huge investment tied up ($50/Bbl times 2MM = $100,000,000).

They also may have to consider the hydrogen and fuel requirements to keep the refinery in hydrogen and fuel balance. Doing monthly or even weekly mass balance on the refinery and the internal units does not generate enough visibility to maximize the operational efficiency for the refiner in a global market. To accomplish these objectives many sites are facing a measurement shortfall. An obvious example is the water in crude measurement. Typical errors here can translate into millions of dollars paid for water. Many refineries also have issues with high levels of unaccounted losses in the loss control reports. Top tier refineries maintain unaccounted losses to less than 0.5% on crude. That kind of performance is not possible if you only measure the loss once per month.

Companies are engineering new refineries today coming on-line in 5-7 years in parts of the world where the owners will own the crude feed. They are being designed with digital communications technologies in the processing equipment and systems to interact more tightly with the scheduling and planning systems to maximize and optimize these assets and the added value products coming from the crude.

Michael believes the challenge for existing refineries is to improve and integrate the production management systems to account accurately on a daily basis actual verses planned production. This allows the planning and scheduling departments to improve asset utilization and squeeze more efficiency from existing equipment. Production Management systems should provide key metrics for operations management to make decisions that maximize response to market demands, spot opportunities and operating flexibility to better differentiate themselves from their competitors. This agility coupled with improved asset utilization will help existing refiners better compete as the modern, high-tech refineries begin to come on-line.

Michael recommends beginning with a thorough analysis of the production management system as a first step. This can be the basis of building a business case for change to more agile production. Developing and providing decision alternatives with their business impact is an important part of this improvement plan. There is no one thing, but rather a combination of tools, work flow changes and operational discipline which can reveal the scale of performance improvements possible.

From my prior post with Greg McMillan and his thoughts on PAT and Advanced Control, I neglected to mention that he will be at the Interphex 2007 Conference & Exhibition next week presenting two seminars in the Emerson booth (#2354). The seminars will be held 1:30pm on Tuesday and 10am on Thursday. He'll also be around the booth demonstrating the Virtual Plant and DeltaV InSight.

In case you will be there at Interphex2007, I'd be remiss in not mentioning two other Emerson presenters featured here at the Emerson Process Experts blog.

Todd Ham is co-presenting with Genentech's Todd Edgington a session entitled Automating Fermentation on Tuesday from 9-10am.

Mark Coughran is presenting a session entitled Practical Control of Batch Reactors also on Tuesday from 3:15 to 4:15.

I'll work to get my hands on these presentations to recap them for you in future blog posts.

Recently I discovered in my PAT RSS persistent search feed an article in Pharmaceutical Processing magazine entitled, PAT Solutions-Eight advanced process control technologies worth considering. This article was written by Rick Rys, President, at R2 Controls, and Janice Abel, Director, Global Pharmaceutical and Biotech Industries, at Invensys.

Since ModelingAndControl.com's Greg McMillan recently co-authored a book New Directions in Bioprocess Modeling and Control-Maximizing Process Analytical Technology Benefits and recently had an article published entitled Maximizing PAT Benefits from Bioprocess Modeling and Control in the November 2006 issue of Pharmaceutical Technology IT Innovations, I had to ask for his thoughts.

Greg sent me a great email which I'll pass along with my edits to insert hyperlinks:

The DeltaV systems offers the advanced control technologies mentioned in the PAT article, such as synthetic analyzers, feedforward and predictive control, dead time compensation, and model predictive control in its standard integrated graphical configuration studio that uses Fieldbus function blocks. The synthetic analyzers not only include online regression models such as Neural Networks but also embedded first principal models. Furthermore, innovative analytics, control systems, and models can be prototyped faster than real time in a virtual plant on a desktop or laptop PC anywhere. The virtual plant uses an exact duplicate rather than an emulation or simulation of the control system in the control room. Advanced technologies in the virtual plant can be developed and tested from the high speed play back of historical data from existing systems used to automate bench top fermentors. This includes a new adaptive control technology that identifies process dynamics and indicates the relative improvement possible from better control. The high speed virtual experimentation capability of the virtual plant is a key feature and may be the only way to provide enough historical data particularly on "what if' scenarios since a fermentor batch for most new bioprocesses takes 14-17 days.

The same virtual plant can be used for education of operations and technical support by the dynamic restore and high speed playback of instructive periods of operation.

The technologies can be connected to the bench top system for evaluation, verification, and adaptation of models early on in the commercialization process.

The uses and advantages of the synergistic environment of the virtual plant are explored in the book New Directions in Bioprocess Modeling and Control, the article "Maximizing PAT Benefits from Bioprocess Modeling and Control" in the November 2006 issue of Pharmaceutical Technology IT Innovations, and in the lectures on the Modeling and Control.com blog. The important practical implications of the extremely slow one direction integrating response of biomass and product concentration on modeling and control are also discussed in the book, article, and website.

The integration and knowledge management of a diversity of technologies in DeltaV addresses the essence of the PAT initiative as expressed in the following statements by the FDA:

Process Analytical Technology:

• It is important to note that the term analytical in PAT is viewed broadly to include chemical, physical, microbiological, mathematical, and risk analysis conducted in an integrated manner.

Process Analytical Technology Tools:

• Multivariate data acquisition and analysis tools
• Process and endpoint monitoring and control tools
• Continuous improvement and knowledge management tools
• An appropriate combination of some, or all, of these tools may be applicable to a single-unit operation, or to an entire manufacturing process and its quality assurance.

Emerson's Terry Blevins has been a driving force in much of the advancements in process automation. In the early days of the DeltaV system developments, he was at the heart of the Foundation Fieldbus standards development. As technologies advanced and it became possible to put advanced control algorithms in controllers rather than host level computers, Terry was again at the forefront working to add model predictive control, neural networks, fuzzy logic, and most recently continuous control performance monitoring into the DeltaV system.

Over at ModelingAndControl.com Terry shares his wisdom gained over many years for the next generation of automation and control engineers.

So why am I telling you all this? It's because today the ISA announces, ISA Standards Committee Launches EDDL Website. Terry, as the chairman of the SP104 committee, was integral in making this happen. Earlier this year, he summarized the goals of the SP104 committee well in this blog post.

He even enlisted me to seek out the EDDL.org domain, secure it, and donate it to the ISA organization. I was more than happy to help.

The EDDL.org site clearly states what EDDL is all about:

Electronic Device Description Language (EDDL) technology is used by major manufacturers to describe the information that is accessible in digital devices. Electronic device descriptions are available for over 15 million devices that are currently installed in the process industry. The technology is used by the major process control systems and maintenance tool suppliers to support device diagnostics and calibration.

Terry was concerned that information about EDDL was scattered around a number of sites including the HART Communication Foundation, Fieldbus Foundation, and Profibus International. This made it difficult for automation professionals to learn about this important standard. The goal of EDDL.org as described in the press release:

The website is a good way for interested parties to learn how to ensure long-term viability of device management solutions, protect their investment in these systems and easily keep it current, ensure security and robustness... The site also features links to training, technical articles about EDDL, online tutorials, and other related standards efforts.

Standards have played and will continue to play a key role in process automation as process manufacturers increasingly rely on the technologies to get their process operations running efficiently and being able to serve their customers better.

Charlie Masi, over at Control Engineering magazine's Ask Charlie blog, had an interesting post recently. Entitled, When is a piece of equipment or system obsolete?, he writes:

After spending several hundreds of thousands, or just as often millions, of dollars building up infrastructure based on earlier-technology equipment, dumping it as "old and yukky" just because something "new and improved" has come out is fiscally irresponsible. Not only would you have to write off the old equipment (which the accounting department would rather depreciate over another two or three years--or more) and lay out the cost of the "new and improved" stuff, everyone in the plant would have to drop what they're doing (hopefully, productive work) to take training classes on the "new and improved" stuff (which is definitely unproductive).

It's interesting because it ties in with a draft of a paper that Emerson's John Dolenc is writing about planning automation upgrades. You may recall John, an advanced automation services consultant, from an earlier post. One of his key points is that economic justifications based on obsolescence are a difficult route to take, unless the obsolete equipment is causing unplanned downtime. One problem is that it's hard to quantify the improvement. Another is that the new equipment may be replaced "in-kind" where no benefit is received from its improved technologies--it simply mimics what the old equipment did.

He stresses a path which begins with the business objectives like increasing production capacity, reducing manufacturing costs, or increasing process flexibility to more quickly respond to customer demand. From these business objectives, an audit of the process unit should be done to identify areas for financial improvement.

This audit feeds a conceptual engineering study to develop the process automation modernization plan. John has developed these studies working with members from operations, maintenance, plant engineering and management, even sales and marketing to better understand the flexibility the plant's customers require.

This study provides the business case whether to pursue the capital investment for modernization or to maintain the status quo. It may also identify quick opportunities for improvement with the existing equipment.

The draft also describes his methodology for moving forward with the modernization plan, which I'll save for a future post.

Emerson Educational Services' John Egnew has posted another LoopTip, entitled Is Your Process a Real Character? In it, he explores loops that are in constant need of retuning.

The likely situation is that the process that the loop controls is non-linear.

The solution is either to take advantage on gain scheduling, where the gain of the loop is changed based on which operating region the loop is trying to control. This solution only works for the automation systems which support gain scheduling or built-in adaptive modeling.

John notes that you can select control valves with non-linear characteristics which offset the non-linearity of the process. He describes it:

The control valve characteristic is used to compensate for the process gain to achieve an approximate installed linear process.

He does note it is difficult to exactly get the non-linearities to cancel one another out, but that at least you can come close in approximating a linear constant gain process and be in better shape than before you made the change.

A leading research organization, the Aberdeen Group, says it well when they say:

In asset intensive industries, such as automotive, metals, mining, oil and gas, process manufacturing, utilities, and the public sector, the reliability and productivity of capital assets is essential to an organization's financial success. Maintenance of these assets can dramatically impact the overall performance and useful life of an asset.

Petrochemical manufacturers definitely consider themselves in this "asset intensive" group. As such, solid maintenance programs are essential. And it is especially critical to plan the times when they are shut down for maintenance. Known in industry parlance as a turnaround, these may happen only every 4-6 years. This means they frequently involve new personnel as people move on to new roles.

A Houston, Texas-based petrochemical manufacturer saw an Emerson Exchange presentation given by Emerson's Instrument & Valve Services (IVS) consultant Wade Enns. He described a Northern Alberta Oil Sands production project with 120,000 I/O to commission. A key to the success of this project was the use of the Smart Start project services methodology. It helped bring a well thought out plan and order to this huge commissioning task.

This methodology and associated software provides embedded check sheets and commissioning procedures for 196 specific equipment types, customized check sheets for planning and checking off tasks during the turnaround as they are completed. The process also helps prioritize the maintenance activities and documents them to provide an audit trail, should the refiner need to refer back to the maintenance activities performance.

The petrochemical manufacturer shared how they had real problems with their last turnaround with scheduling and quality of the work performed. Obviously, any delays impacting the start-up schedule mean lost revenue.

The IVS team worked with the manufacturer to plan the maintenance turnaround on the process with 600 loops and 1800 devices. The process began by building a Smart Start Project Tool database to capture the entire scope of the instruments and valves which were in use. The team took advantage of the plants installed AMS Device Manager. Next, to fully understand and document how everything was installed, they performed "loop walk-downs". This helped put together the plan for the priority and order of the maintenance to be performed.

Working collaboratively, the maintenance and IVS team fully documented and received signoff on the plan in time for the turnaround. With milestones in place, the team could catch deviations from the plan early so that additional resources could help in these areas.

The results were what this manufacturer wanted--a smooth turnaround executed in the allotted time. Given the pressures on everyone to get the maintenance work done in the allotted schedule, having this well thought out and documented plan definitely helped reduce the stress along the way.

In an earlier post, I mentioned seeing a draft article by Emerson's Terry Blevins and James Beall on performance monitoring and the Process Analytical Technologies (PAT) initiative.

The article, Monitoring and Control Tools for Implementing PAT, has now been published in Pharmaceutical Technology magazine.

Terry and James do a great job in summarizing the common problems process monitoring can detect. These include problems where the control is limited, information from the field transmitters is bad or uncertain, loop modes are incorrect, or there is high variability associate with the loop.

You can do process monitoring with an application that runs either on top of the existing automation system or embedded within it as I discussed in an earlier post on DeltaV InSight.

Here's a few tips gleaned from the article which I'll paraphrase:

• Make sure the performance monitoring application understands the operating states of the batch process avoid false indications or failed measurements
• Where you are using smart field devices like Foundation fieldbus, HART, or others include the status which accompanies the measurement so that performance calculations are based on valid information
• Check the operating modes of the loops versus their design as a basic measurement of control performance.
• Having a model to compare the actual running process against can help spot the largest areas of variability to focus improvement efforts.

Terry and James wrap up their article nicely pointing out that the Food and Drug Administration's PAT initiative has opened up the opportunity to use these performance monitoring tools to improve the operations of their processes. The timing is great with newer technologies coming along to simplify the performance monitoring process.