Dairy advances its capabilities from MES to process control and batch
By Kirby Powell and Jay Munro
Milk might be a natural, but it is a very demanding product. Let the temperature during processing drop a degree too low, and there is potential to compromise its purity. Let it rise a degree too high, and it ruins the product’s flavor or texture.
To perform the delicate balancing act dairy products demand, plant operators need complete control over the process. They need the ability to know precisely what is happening at every moment and to perform minor tweaks on a dime. It is not easy, especially when the manufacturer cannot see the product, which remains out of sight in tanks and pipes 90% of the time.
It is even more difficult at Dietrich’s new specialty processing plant in the rolling hills of Pennsylvania. While most dairy processing plants focus on high-volume runs designed to compensate for low margins, Dietrich’s specialty processing handles small, specialized batches of product such as organic or kosher foods and food ingredients.
Like all dairy processing plants, Dietrich must clean its processing equipment between every production run. The diverse requirements of conventional, organic and kosher, and dairy and non-dairy products add yet another level of complexity to its process control and record-keeping challenges.
Kline Process Systems (KPS), a systems integrator that specializes in solutions for the dairy industry, won the contract to design and build a state-of-the-art control system. Trust levels between the two companies were so high that Dietrich gave KPS complete freedom to choose the control equipment.
The very strong message Dietrich gave was 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. A good control system keeps the equipment operating efficiently and cleanly, and sanitation is everything in the dairy industry.
With the ability to mix and match best-in-breed solutions from any number of vendors, KPS decided on a control system from one supplier.
After looking at various technologies, one of the products that caught Dietrich’s eye was the wireless capability of the tablets. Dietrich liked the wireless tablet capability. Dietrich liked to empower the operators to make decisions and act on them immediately, but the plant has a lean operation and a low headcount. The operators need to be everywhere at once, so they need to be able to control any operation from any location.
The tablet has rubber bumpers on the corners that cushion it from the rough use it is likely to encounter in a plant setting, and it is drop rated to eight feet. In the liquid environment of a dairy, equipment is subject to splashing, so water-resistance is critical. But Dietrich also needed dust resistance because its primary business activity is in powdered products.
The tablet had a touch screen interface that really worked, and because it has Windows CE and Remote Desktop embedded, it gives the plant’s operators, management, and KPS personnel a truly lightweight industrial mobile terminal for plant operation and troubleshooting.
The plant runs through Internet Explorer in a thin client environment. Employees can use any PC in the plant as an HMI.
Authorized users can log on through virtual private network technology from any computer worldwide and see precisely the same information they would see if they were on-site at the plant. In one such case, Dietrich and KPS worked closely with the Koshering Organization to leverage this technology. The organization now has a network user ID and has the ability to view plant process information from their office when the plant is processing a Kosher product. This provides the organization with the option of monitoring processes on site or remotely. To maintain the integrity of the certification process, DSP employees never know if or when the rabbi will choose to use the remote technology versus monitoring the process in person. DSP and the Kosher OU benefit by saving time and improved responsiveness.
One of the benefits is 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.
Batching it up
While most dairy plant operators focus on high-volume processing, Dietrich saw a market opportunity in going against the flow with a focus on small, specialty batch processing. A food company with a special need but a low volume cannot fit into the business model of most dairy processing plants. So, Dietrich caters to that specialized niche, providing low-volume, high-quality specialty milk and non-milk processing capabilities.
Dietrich focuses on producing intermediary products rather than finished ones, 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. The company may use its cream to make butter or as an ingredient in candy or ice cream.
Because its customers tend to provide the marketplace with high-value specialty products, a focus on quality is a key part of Dietrich’s value-add.
Keeping the milk and other ingredients at the right temperatures and being able to document that you did, ensuring that vessels are cleaned according to all of the Food and Drug Administration’s specifications and regulations, ensuring the operators have the right information to make the proper decisions—those are all functions of the control system. The system also should give an immediate notification of any process disturbance, providing all of the information you need to immediately diagnose the problem and make adjustments.
This system collects data—temperatures, humidity, and other key parameters—from PLCs scattered throughout the plant, and presents it to operators on their tablets or on a desktop. Custom-developed display screens present the information in precisely 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. The 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. If it varies more than one or two degrees, it can create off flavors, but if it is too low, the product will not be pasteurized. The operators need the data, need to understand the data, and be able to make adjustments. The system collects the data, presents it in an understandable format, and carries out the operators’ instructions.
The MES files
KPS also chose a manufacturing execution system (MES) to provide a plant-wide layer of information management that compiles information from the control system with other inputs from throughout the plant. After production, the MES compiles a record of all the materials consumed, all the finished materials produced, and all the process parameters that applied to each individual batch.
The data historian is the first piece of the MES executed at Dietrich. The historian captures process data second by second and stores it in a database. The data can, among other things, document to the FDA that cleaning processes occurred under the proper conditions, or document to the koshering agency they executed all predetermined koshering processes.
You do not disassemble the pipes to clean them, you clean them in place, what the FDA calls CIP. The data is all you have to know that the process performed properly. If you have good monitoring of CIP, you improve your process dramatically, and the historian allows you to document for the FDA or the koshering agency that everything was done the way it should be.
Traditionally, historical data occurred with a mechanical chart recorder. But storing and recovering the paper charts on demand was difficult and time consuming, especially for a plant like Dietrich that may do 50 or more cleaning cycles per week. MES collects more data and stores it electronically, making it searchable and retrievable on demand.
In the past, MES systems required a programmer to write a ton of custom code for lot tracking, genealogy, recipe scheduling, and lab management. Every system started from scratch, and that introduced a greater potential for error into the process. 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 customization. It should remove a lot of the trial and error from the process of implementing an MES, and significantly reduce the de-bugging process.
The plant has been in operation since October 2006. The operators, in particular, love it, especially the tablets. They are crazy about the ability to stand on the process floor and still be able to start and stop equipment remotely and study their data. It is saving them a lot of time because they do not have to run back and forth to the control room.
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