January 2007 Archives

Pharmaceutical Technology Europe has a recent article entitled, Artificial intelligence the key to process understanding. It discusses the opportunity to enhance the FDA's Process Analytical Technologies (PAT) initiative using artificial intelligence based tools like neural networks, fuzzy logic and genetic algorithms. I shared this article with Greg McMillan who has been quite immersed with advanced control as it applies to bioprocesses.

I received this response which I'll share in total (I've inserted some context-sensitive hyperlinks to his work on Process Control Insights):

There are opportunities to improve plant performance in the front end of the process where most of the product qualities are set by the use of online process models, batch analytics, and Model Predictive Control (MPC). Online process models based on first principals offer a significant source of knowledge discovery for both the process and the control system. The models are part of a virtual plant that enables virtual experimentation for the exploration of "what if scenarios".

This is important for the next steps of implementing online batch analytics and MPC. Since fermentation batches take days to weeks to complete and the cost of wasted batches is considerable, the virtual plant can provide data on various degrees of adverse operating conditions that would be infeasible to obtain from the actual plant in terms of time and cost.

The virtual plant facilitates the development of techniques for the proper unfolding and alignment of batch data and more advanced analysis techniques such as super model based Principal Component Analysis. Neural networks can be employed to provide reaction rates when information on the kinetics is insufficient.

Fuzzy logic rules can be formularized and tested for a wide variety of scenarios. Inferential measurements can be developed for viable mass growth rates and product formation rates to fill in the blanks between lab measurements for MPC applications to improve batch consistency and yield and to reduce batch cycle time.

In summary, the virtual plant offers a synergistic environment for the application of online batch analytics, artificial intelligence, and advanced control. These opportunities and others are discussed in the book New Directions in Bioprocess Modeling and Control published and in the lectures on the Process Control Insights website.

The ARC Advisory Group just released a Foundation fieldbus study which indicates that fieldbus solutions are expected to grow globally by more than 22% annually over the next five years. Specifically, the announcement of the Fieldbus Solutions study cites:

The worldwide market for Fieldbus Solutions in the Process Industries is expected to grow at a compounded annual growth rate (CAGR) of 22.3% over the next five years. The market was greater than $831 million in 2006 and is forecasted to be over $2,279 million in 2011...

When the Foundation fieldbus technology was introduced in the mid 1990s, the compelling benefits were in capital expenditure savings, primarily in wiring and commissioning savings. I got to see this personally when I went to Alaska's North Slope to see an Oil & Gas producer be one of the first to adopt this digital communications technology. It made perfect sense given the tremendous labor costs, and cost of building structures to shield the equipment from the harsh, arctic environment. You can see some photos on slides 75-76 of a Foundation fieldbus Installation tutorial in the Fieldbus Tutorial section of EasyDeltaV.com.

The ARC study announcement indicates that more and more process manufacturers are seeing operating expenditure benefits, especially through predictive maintenance. The study indicates:

Manufacturers are recognizing that the real value of fieldbus is Operating Expenditure (OpEx) related rather than Capital Expenditure (CapEx) related. End users have reported that predictive maintenance is the single largest savings resulting from the use of fieldbus.

I caught up with Emerson fieldbus consultant Dan Daugherty to get examples of predictive maintenance benefits. He cited a study by Dow in a Hydrocarbon Processing magazine article from a few years back. The article cited remote diagnostics in smart instruments helping to eliminate 63% of "problem not found" maintenance tickets through remote diagnostics. These diagnostics also helped reduce problems associated with drift, plugged impulse lines, and zero shifts in the field devices. Use of the ValveLink Snap-On in AMS Device Manager makes it possible to diagnose valves without having to pull them offline and look inside them. In another study by DuPont, they found that only 14% of the valves scheduled for preventative maintenance actually required being pulled and rebuilt. Dan summed it up well:

The savings on valves more than justifies implementing predictive maintenance methodology, so it is as if all the other benefits (fewer trips to the field, etc.) are for free.

The ARC announcement concludes that new installations benefit most. The greatest growth areas for these installations are in Brazil, Russia, India and China.

Depending on the conditions of an existing facility in terms of maintenance costs, the benefits from predictive maintenance may provide the economic justification to retrofit existing non-digital instrumentation and communications.

Since the ModelingAndControl.com blog was launched a few months back, Terry Blevins and Greg McMillan have been sharing their expertise in process control gained from years of plant and R&D experience. It's a real treasure trove if you want to learn more about process dynamics, process modeling, and technologies and control strategies to consider in better managing your process.

We decided to put together an area on the EasyDeltaV.com website called Process Control Insights to provide a common area for people to find this experience. As a new, global generation of process automation professional joins us, the hope is that they'll find sites like this to connect to the wisdom of those who lived it for so many years. We are pleased that Greg allowed us to give this a try with much of his work. Here's Process Control Insights' mission:

Welcome to Process Control Insights -- your central spot to learn and explore the nature of process control and its fundamental relationships with your processes. We hope this helps you gain a better understanding of the true nature of these dynamics and how it can help you optimize your process.

The site currently includes application notes, lectures, links to written books, and of course links back to the ModelingAndControl.com site. I had a chance to sit down with Greg before the holidays and record a presentation he had recently given to a major pharmaceutical manufacturer on using modeling and advanced control strategies in a batch manufacturing process. Although these control strategies are common in continuous processes, there use in batch processes is still in its infancy.

You can get a flavor for the lecture by listening to the Introduction Batch Control Story. I have some work to do to get the audio better for future lectures. (Hmmm Gary... I hear I'm not alone in this!)

We hope over time to have others provide their real-world experience and expertise to shorten the learning curve for our next generation of process control experts.

Do you ever feel that pressure when things just aren't right? Things like increasing production costs, growing raw material and/or finished product inventories, inconsistent quality and inflexible production to meet changing customer needs. According to John Dolenc, a principal consulting engineer for Emerson's Advanced Applied Technology team, these are potential business drivers to consider modernizing your process automation.

Other potential drivers include unreliable operations caused by false trips and excessive plant alarms, poor-to-nonexistent production data, time wasting manual data entry and checking, and time consuming regulatory compliance and documentation. Each of these drivers has a cost associated with it that can be used to develop a business case for improvement.

John helps process manufacturers understand and quantify these opportunities for improvement in Process Automation Feasibility studies. The study begins with gathering the background information found in process flow diagrams, P&IDs, operating procedures, operator log sheets, plant history data, production costs and trends, quality reports, and current control strategies.

Usually a team forms with members from plant management, plant engineering, operations, maintenance, quality assurance, and even corporate engineering and management depending on the level of potential improvement. John and other advanced applied technology consultants bring expertise in production processes, plant operations, and the impact control strategies have on the process to help develop an improvement plan. They are experienced in providing a methodology based on past experiences and bring an outside perspective to facilitate discussion and have the freedom to challenge the rational behind past practices to get at the underlying issues.

The methodology examines the process unit performance first from a financial perspective. Key performance indicators (KPIs) are identified and the performance versus these KPIs is analyzed. Base line performance is established, potential improvements are identified, and financial gains are calculated. An automation plan to achieve the financial benefits is developed based on examining the production process; looking at process constraints, process disturbances, and limitations in equipment or other areas of the operation.

The cost to implement the automation plan is estimated and a financial analysis is done to determine if the projected benefits justify an automation project. For smaller units this process can take four weeks to perform the feasibility study, while larger units or plant-wide studies may take several months.

The real fun happens when projects get funded and quantified improvements get made. It goes a long way to relieve that pressure!

Safety risk assessments require a methodical look at all the areas of a manufacturing process where hazardous conditions may exist. I caught up with certified functional safety expert (CFSE), Mike Schmidt, who recently worked with a terminal operator to relook at the safety risks at the terminal. Mike is a consultant in Emerson's Refining and Chemical industry center.

Mike worked with the risk assessment team which included members from HSE (health, safety and environmental), engineering, operations, and the terminal manager.

The team looked at the layers of protection in place as well as the current safety instrumented functions (SIF) that were currently in place to reduce the risks of various hazards. For a terminal which takes in and sends refined hydrocarbon products like gasoline and diesel these possible hazards include things like ruptured pipelines, loss of pipeline containment, storage tank overfill, tank truck overfill, and barge overfill to name some.

Following the total safety lifecycle as prescribed by the global IEC 61511 safety standard (ISA S84.01 2004 in the U.S.), the team very methodically considered every risk, its likelihood, and the consequence of the hazard occurring. Areas were identified to add to the existing layers of protection and safety instrumented functions.

An example Mike shared was the hazardous condition caused by a storage tank overfill condition. These tanks are filled either by an incoming pipeline or from a marine vessel. The team determined that the likely cause of a storage tank overfill with the worst consequences is an error or failure condition during receipt of product from a pipeline, because a pipeline represents an essentially infinite source of spilled material. To mitigate this risk, redundant level sensors are placed on each tank. The operating level is monitored and controlled with a separate level transmitter. Should a possible overfill condition begin to occur the safety instrumented system initiates closure on the pipeline isolation valve. Given the consequences and impact of this potential hazard, this safety instrumented function was rated SIL 2.

Out of this assessment, the next step was to develop a detailed safety requirements specification, again consistent with the IEC 61511 standard.

The performance-based standards outlined in the IEC 61511 standard more and more require this close working relationship between the process manufacturer and safety instrumented system provider to carefully examine the hazards and develop and execute a plan to mitigate the risks identified.

The DeltaV New RSS feed today points to a U.S. Department of Homeland Security press release, Government, private industry work together to increase cybersecurity. It mentions how the Department of Homeland Security is facilitating a group called the Control Systems Cyber Security Vendors Forum to provide an open discussion on those issues affecting control system security.

Although a U.S. initiative, process manufacturers around the globe have an interest in the cyber-security of their automation and control systems.

I caught up with Bob Huba, whom you might recall from earlier discussions on the issue of cyber-security. Bob explained to me that the goal of this initiative is to share ideas around a common goal of protecting automation systems from unauthorized cyber or physical access. Much like the IEC and ISA standards committees, the Vendor Forum offers a neutral place for suppliers to get together to talk about cyber-security best practices and develop guidelines.

Today there are labs like Idaho National Labs who started the Control System Security Program, Sandia National Laboratories and WurldTech Security. These organizations will test systems for many known exploits and provide reports to the suppliers for these to be fixed. Although these tests are necessary and valuable, there are no existing agreed on standards to test against. Providing inputs to the groups who are defining the security standards is one of the hoped for results of the Control Systems Cyber Security Vendors Forum.

One goal of the vendor group is the partnership of federal regulators working with the automation system suppliers who best understand the issues with their respective systems. It will help lead to workable guidelines and best practices that can be shared with global process manufacturers.

The feeling among the suppliers seems to be that basic cyber-security is not an area for system differentiation--it's an absolute requirement like PID control or connectivity with business systems. As part of maintaining the security of our process infrastructure we all need to rely on the products process manufacturers make and want to make sure their systems are as secure as they can be made.

I caught a sneak preview of draft article that ModelingAndControl.com's Terry Blevins who collaborated with James Beall whom you may recall from earlier posts.

The draft explores the initial steps Pharmaceutical and Biotech manufacturers should consider when preparing to implement the U.S. Food and Drug Administration's Process Analytical Technology (PAT) initiative. For those unfamiliar with the PAT guidelines, they were established to encourage innovation in development and implementation of manufacturing processes to improve product quality. The existing regulation designed to achieve quality through rigorous design and documentation actually served to discourage improvements due to the time-consuming nature of the revalidation of any changes.

Terry and James offer some guidance on some initial steps that Life Sciences manufacturers can take. Since most of their manufacturing processes are batch-based, it can be trickier to apply some of the advanced process control technologies more often found in continuous processes found in the chemical, petrochemical, and oil and gas industries. They recommend starting by looking at ongoing performance monitoring. This software has typically layered on top of the automation systems but has begun to become embedded in the automation system. DeltaV Insight is a good example of this type of performance monitoring software embedded in the DeltaV system. This performance monitoring can be keyed to the phases within the running batch to account for the changing process conditions. The dynamics of the process are learned as changes in the process are made.

Terry points out that these performance monitoring tools can help manufacturers spot issues like excessive process variability which can have direct impact on product quality. Other conditions this software can help detect include control-limited conditions, bad/unreliable data coming from intelligent field devices, and control loops operating in modes other than those intended. All of these conditions can contribute to quality issues in the final product.

He notes that the ability of intelligent field devices to provide status of the goodness of the data is a key part of performance monitoring so that the control strategies, history collection, and analytical tools have a clear picture of what is really happening in the process.

I look forward to seeing the finished article!

While thumbing through the November/December issue of Pharmaceutical Manufacturing magazine, I came across a great article, Getting the Most from Coriolis Flowmeters in Pharmaceutical Processes, co-written by Vince Salupo of Eli Lilly and Franki Parson of Emerson Process Management's Micro Motion division. It's a great article for discussing the advantages and disadvantages of bent-tube vs. straight-tube meters depending on the requirements of the application. If you are already well-versed in Coriolis flow technology, this may all be too basic for you. If you're like me and not as well-versed, the article is worth a read because it makes the complex understandable.

Coriolis meters provide mass flow and density measurements, and are available in both bent-tube and straight-tube design. The article discusses the two types of designs and their advantages specifically in Life Sciences applications. The bent-tube meters have better accuracy and turndown. The straight-tube meters offer improved drainability which is something critical for pharmaceutical and biotech manufacturing processes which have clean-in-place operations to clean and sterilize the process piping between batches. The choice for of Coriolis design most suitable really is based on the application. If accuracy and repeatability are the overriding concern, the bent-tube technology is recommended. If raw material contamination within a batch or between batches is the key concern, the straight-tube flowmeters are recommended.

Another reason for the popularity of Coriolis flowmeters in Life Sciences manufacturing applications is their non-intrusiveness into the process. There are no fluids or moving parts that can cause problems on failure. Only the inside of the flow tubes touch the process.

The article further explores specific challenges found in Life Science applications like API synthesis and purification, formulation, and high purity water and what you should consider in selecting bent-tube versus straight-tube Coriolis meters for these unique applications.

I hope others considering their options in these types of applications found the Pharmaceutical Manufacturing article as clear and succinct as I did.

Before the holidays, Dave Harrold wrote a post, A Wee Bit More About Safety Instrumented Systems, in his Dave @ AFAB Group blog. He describes his work with Dr. Angela Summers, founder/president of SIS-Tech Solutions on a guidelines book for the global IEC 61511 safety standards. Dave also referenced an SIS-related Q&A article Angela wrote for Flow Control magazine.

I forwarded the post and Flow Control article link to Riyaz Ali, whom you may recall from an earlier post. Riyaz wanted to add to the conversation and make three specific points in reference to the Flow Control article.

On the question regarding the use of digital valve positioners to perform partial testing and its relationship to the proof test interval, Riyaz agrees that the proof test is far more than a partial stroke test. The proof test can be performed on a final control element either on-line when a bypass valve exists or offline when the process is shutdown, such as during a plant turnaround. Many process manufacturers do not have large bypass valves and seek to extend the interval between plant turnarounds as long as possible. The on-line partial stroke testing provided by digital valve positioners can help extend the time between proof tests. They do not replace these tests. Riyaz points to a Control Engineering magazine article authored by Dr. Summers, Partial Stroke Testing of Safety Block Valves, in which she points out:

Also affecting the SIL is diagnostic coverage and testing intervals of partial-stroke testing to supplement full-stroke testing to reduce a block valve's PFD.

Being a mechanical item, testing of SIS "Final Control Element" offers challenges but at the same time represents a significant failure contributor to SIF loop. Partial stroke test by digital valve positioners not only allows "audit documentation" but also allows diagnostics health of valve, a key feature to improve reliability of SIF loop.

Riyaz did take exception to a statement in the article about throttling valves:

Positioner failures are the leading cause of control failure, so the positioner should not be used to actuate the valve in an SIS application when preventing events associated with a loss of control. Instead, a solenoid-operated valve should be used to independently close the control valve.

He notes that control valves are better geometrically designed with proper actuator and valve plug connection to reduce hysteresis, dead motion, sticktion, backlash etc., compare to shut down valves those are typically keyed shaft and mainly used for On and Off function. The main concern for shut down valves is stuck condition. If initial inertia force is broken during normal exercise of valve either through partial stroke test or by modulating through DCS signal, it is very likely that valve will be available during a safety demand, when required to bring the process to safe state.

His final point is on the question regarding smart positioners for partial stroke testing of smart valves. Positioners operated by air have been used in process control industries for years to improve performance of control loop. It is becoming rarer to come across a process loop not without positioners, especially where the application improved process variability. Based on its usage and benefits in process control, process manufacturers have started using them for Safety Instrumented Systems also. Riyaz agrees with Dr. Summers comment that positioners have smaller orifice but any thing larger than 8"-12" size valve, even otherwise a Quick Exhaust Valve or similar mechanical device will be used, if fast stroking speed is desired. Len Laskowski adds that the driving factor is process safety time. Many times larger valves do not need to close in one or two seconds, and in fact require a more controlled closure to avoid negative effects on process and utility equipment. It all hinges on the process safety time for each application.

Positioners by design are to bleed very small air to keep the air flowing as well keep pressure higher than atmospheric so as avoid any external atmospheric corrosive gas getting inside the housing. Also during partial stroke test positioners exhaust and fill the air, which makes its mechanical parts moving and avoid any build up.

Digital valve positioners allows partial stroke testing, while process is running and provides date and time stamp of test with capability to store and compare test results. Also, being a microprocessor based, these positioners allow remote testing and retrieval of data remotely. The main advantage is predictive maintenance by providing valve degradation analysis, which is important to critical valves in safety related systems. If by any chance valve is stuck, digital valve positioners are capable of providing alerts to operators to fix the problem.