Dairy Processor Stays Flexible

Milk is a demanding product. Let the temperature drift during processing, and purity can be compromised or the product’s flavor or texture might be ruined. To perform the delicate balancing act that dairy products demand, plant operators need complete control, including the ability to know precisely what is happening at every moment and to perform minor tweaks on a dime.

By Walter Staehle, Siemens Energy & Automation June 1, 2008

Milk is a demanding product. Let the temperature drift during processing, and purity can be compromised or the product’s flavor or texture might be ruined. To perform the delicate balancing act that dairy products demand, plant operators need complete control, including the ability to know precisely what is happening at every moment and to perform minor tweaks on a dime. It’s not easy, especially when the product is hidden from sight in tanks and pipes more than 90% of the time.

Companies that process the same products day-in-and-day-out have experience on their side, but those that change frequently have to be very agile and adaptable. That’s the way it is at the gleaming new Dietrich’s Specialty Processing plant in the hills of Pennsylvania. While most dairy processing plants focus on high-volume runs, Dietrich’s Specialty Processing is a “boutique” facility that handles small, specialized batches of product such as organic or kosher foods and food ingredients.

“For the most part we produce spray-dried food ingredients,” says Thomas Dietrich, president. “We don’t produce a lot of finished product, so we aren’t at the end of the chain where we’re dealing with the final customers. When you’re an ingredient processor, you’re an intermediate step. It’s not a high-margin business.”

Like any dairy processing plant, Dietrich’s Specialty Processing must clean its equipment according to very strict procedures between every production run. However, the diverse requirements of conventional, organic, and kosher, plus dairy and non-dairy products add yet another level of complexity to its process control and record-keeping challenges.

Dietrich’s Specialty Processing chose Kline Process Systems (KPS), a systems integrator that specializes in solutions for the dairy industry, to design and build a state-of-the-art control system that would set a new standard of excellence.

Kline Process Systems was formed in 1991 with a focus on introducing automated process controls into the dairy industry at a time when the technology was relatively unknown. Over the years, it grew into a turnkey mechanical, electrical, and engineering firm that could design, program, and build custom control systems, provide sanitary welders to install equipment, and electricians to fabricate panels and wire systems. Now, food and beverage is 75% of its business.

“The very strong message we got from Dietrich’s Specialty Processing was that they wanted to deliver the highest quality product and processing services available to the marketplace, and they wanted to drive that quality with superior technology,” says Kirby Powell, a KPS director. “A good control system keeps the equipment operating efficiently and cleanly, and sanitation is everything in the dairy industry.”

One platform for everything

While KPS could have chosen to mix and match best-in-breed solutions from any number of vendors, the company picked Totally Integrated Automation (TIA) from Siemens for the entire control system. From the WinCC SCADA (supervisory control and data acquisition) software to PLCs (programmable logic controllers), operator screens, drives, and motor controls, Siemens equipment controls most aspects of the process.

Once he became involved in laying out the control architecture, Powell says the choice was relatively easy. “We saw some unique features in the Siemens products, and we liked the top-to-bottom pervasiveness of their offering. With Siemens’ emphasis on integrated automation we knew everything was engineered to work together, and we liked the idea of having one company to hold accountable.”

Powell says the first product to grab his attention was the Mobic Tablet T8, a ruggedized laptop or Web pad designed specifically for the special demands of industrial settings. “Dietrich was keenly interested in wireless tablet capability,” says Powell. “With the plant’s lean operation and a low headcount, the operators are highly empowered to make decisions and act on them immediately. The operators need to be everywhere at once, so they need to be able to control any operation from any location.”

The Mobic Web pad has rubber bumpers on the corners that cushion it from the rough use it is likely to encounter in a plant setting, and is drop rated to eight feet. Most important, it provides resistance to both the water and dust encountered with spray-dried products.

“The Mobic has a touch screen interface featuring Microsoft Windows CE and Remote Desktop embedded, giving the plant’s operators, management and our KPS personnel a lightweight industrial mobile terminal for plant operation and troubleshooting,” Powell adds. “We’ve worked with other Web-based HMIs, and they were not as full-featured or robust.”

Wireless control successful

Dietrich is also very positive about the success of wireless control in the plant. “The entire facility is set up to operate in wireless mode,” he says. “The Mobic devices are essentially portable laptops that the operators can carry with them.”

Dietrich knows that when operators are in manufacturing areas, they can tell more of what’s going on, and wireless makes it possible. “A lot of the process is more than you can see on a monitor in the control room,” he notes. “In there it’s hard to pick up vibrations, odors, and sounds. In our former environment, we had centralized control and we had people out on the floor. The most capable people with the best process knowledge tended to be the ones sitting in the control room, communicating with floor operators through a radio system. Someone who’s not fully trained may not observe what he needs to see, and if he’s trying to communicate something back to another party through a radio, the chance of the observation matching the message that’s passed on is unlikely. Successful communication occurs maybe a third of the time.”

The control system runs the plant through Microsoft Internet Explorer in a thin client environment. Therefore, employees can use any PC in the plant as an HMI. Authorized users can log on through virtual private network (VPN) technology from any computer worldwide and see the same information they would see if they were on-site at the plant. This has been particularly valuable for customers who want to see relevant production records, such as kosher practices, for specific product batches.

Powell says he especially appreciates the fact that operators receive the same performance whether they use a fat client linked directly to the central server or a thin client operating remotely over the Web. “That not only simplifies the training, but allows faster response to problems. Speed is critical in this facility; you rarely have more than five or 10 minutes to troubleshoot a problem.”

Specialized solution for a specialized plant

Dietrich’s Specialty Processing focuses on producing intermediary products rather than finished ones, such as separating milk into cream and skim or producing the raw ingredients needed to formulate an organic nutritional drink. The products it makes are then sent elsewhere for additional processing or packaging. Because its customers tend to provide the marketplace with high-value specialty products, a relentless focus on quality is a key part of what the company brings to the table.

Dietrich’s built its business on providing small, specialty batch processing for niche players in growing alternative food markets, which has particular operational demands. Dietrich has worked through the start-up process many times. “You stand there with your controls and do what you need to do,” he says. “Make sure everything is up and stable, the cyclones are clear, and then you go back to the control room and move on to the next thing. The portability of this system greatly simplifies the process. Your ability to start up and fine tune a system is much improved when you don’t have to run back and forth to the control room. With small batches and frequent product change overs, you have to be right there to see what’s happening.”

Quality through process visibility

The control system’s ability to give operators a clear view of and total control over their processes is a key part of impressing Dietrich’s customers. “Keeping the milk and other ingredients at the right temperatures and being able to document it; ensuring that vessels are cleaned according to all of the Food and Drug Administration’s (U.S. FDA) specifications and regulations; ensuring the operators have the right information to make the proper decisions — those are all functions of the control system,” Powell notes. “The system also should give you an immediate notification of any process disturbance, providing all of the information you need to diagnose the problem immediately and make adjustments.”

WinCC collects data, temperatures, humidity and other key parameters from PLCs throughout the plant, and presents it to operators on their Mobic Web pads or on a desktop computer. Custom-developed screens display the information in the format operators need, and touchscreen capabilities allow them to send instructions back to the PLCs to open or close a valve, change a temperature or modify flow rates. Siemens drives and motor controls carry out the instructions from the PLCs.

“Temperature is key because it has a huge bearing on purity, quality, flavor, and consistency,” Powell says. “The operators must be able to have the data, understand the data, and make adjustments.”

Process verification

KPS also chose to incorporate Simatic IT, a manufacturing execution system (MES), into its plant operations to provide a plant-wide layer of information management that compiles information from the control system with other inputs throughout the plant. The Simatic IT historian captures process data second by second and stores it in a database. The data can then be used, among other things, to document to the FDA that cleaning processes were performed under the proper conditions, or to document that all predetermined, kosher processes were performed.

“In the past, MES systems required you to write a lot of custom code for lot tracking, genealogy, recipe scheduling, and lab management,” Powell says. “Every system was built from scratch, and that introduced a lot of potential for error into the process. The beauty of Simatic IT is its pre-built modules. Instead of writing every program from scratch, you use the modules to provide the bulk of the code, so the integrator can focus only on what needs to be customized. It should remove a lot of the trial and error from the process of implementing an MES, and significantly reduce the de-bugging process.”

Project now a showcase

Dietrich’s Specialty Processing plant has been in operation since October 2006, and “it’s definitely a first-class installation, the kind of showcase we had hoped it would be,” Powell says. “The operators in particular love it, especially the Mobic Web pads. They’re crazy about the ability to stand on the process floor and still be able to start and stop equipment remotely and study their data. When you’re trying to run a lean operation, efficiency is the name of the game.”

Author Information

Walter Staehle is director, food & beverage industry management for Siemens Energy & Automation. Reach him at walter.staehle@siemens.com