Integrating process control and building automation systems
If your systems communicate with each other, you may save money on energy, improve quality and enhance food safety.
You go to a lot of trouble to fine-tune your process and eke out as much product as you can with minimal waste and downtime while striving for high quality and food safety. But do you feel like you’re continuously fighting a losing battle to get your products consistently on spec?
Maybe your plant’s environment is too moist or dry, too cool or warm, the airflow is all wrong—or worse yet, the environment’s totally inconsistent from day to day and season to season. Put simply, maybe your facility’s operating environment is out of control and is adversely affecting your process and products.
Granted, there are many food applications that are not necessarily so dependent upon your facility’s immediate environment, but with today’s demand for RTE meals, salads, desserts and more, you don’t want to be fighting your plant’s operating environment. You want it under control—not only for maintaining product quality and consistency, but also food safety.
But, who—or what—controls your facility’s environment? If your operations team doesn’t have control of it, then it’s basically out of control like any other process variable. Yes, your building’s environmental control system responds to some preset level of temperature, humidity and maybe pressure, but these settings may not be suited to the current product you’re making, nor are they helpful in changing operational modes from cleanup to production cycle or vice versa. Does someone have to remember to reset the building controls after the third-shift cleaning operation?
In this article, we’ll look at why you might want your process control system to “talk” to your environmental controls (HVAC [heating, ventilation, air conditioning] and/or building automation system) and what steps you may need to take to get them to talk to each other.
“I’d say there are very few processes that wouldn’t benefit from an integrated control system,” says Leah Ackerman, automation engineer for Tamaki Control LLC, based in New Zealand, the US, UK and Ireland. “Most applications have an end goal of improving quality and efficiency, and reducing operator error, downtime and waste. The key to meeting that goal is reliable automation that optimizes run time, as well as an interface that interprets and provides easy access to collected data.”
Applications that depend on zero or minimal downtime will benefit from the visibility that process/HVAC integration offers, says Ed Garibian, CEO of eRPortal Software. As process parameters or machine conditions vary over time, proactive, predictive action can be taken, well in advance of a fault. eRPortal’s software works with OPC/IOT-enabled control systems and can spot out-of-spec trends and alert operators before an important parameter is out of control.
“Ready-to-eat food factories will benefit from integrating HVAC into their process control and food safety system,” says Pablo Coronel, CRB director food processing.
Control of temperature and humidity of the production rooms is critical to maintain food safety in these products, and documentation of both the room conditions and the air handling would make a good preventive control.
“Ambient conditions, specifically temperature and humidity, are important factors in the production of low-moisture foods,” says Doug Beloskur, product manager, digital services, Bühler Aeroglide.
Goods that require drying and subsequent cooling prior to packaging to prevent in-package condensation could greatly benefit from integrated HVAC controls. Linking HVAC controls and instrumentation with cooler controls and instrumentation would provide enough information to develop a process control system to mitigate condensation risks, says Beloskur.
“Also keep in mind that not only the temperature and humidity of the room are important, but also the environmental microbial monitoring, which is integral for food safety,” adds Coronel.
Integrating the HVAC into the production system will allow continuous monitoring of airflows/pressures and filter performance, and minimize the possibility of contamination into the air streams.
When ovens are used in the food process, static pressure in the manufacturing space is critical to allow for proper ventilation for them, says Bob Gray, HVAC/R segment manager, US business, Schneider Electric. Inadequate airflows are problematic for more than one reason, says Gray.
“For example, I worked with a manufacturer of candy products in an enrobing room application where mechanical equipment would shut down, preventing the chocolate coating on the candy from setting up and drying properly. Additionally, inadequate filtration caused particles to settle on the candy products.”
Where precise control of temperature and humidity is critical to the process, an integrated system has an important role, says Dan Homan, Rockwell Automation engineering manager. Common issues that food producers run into are too high humidity that makes product gummy and temperatures outside the required specification, making it brittle or too soft.
Having standards-based controllers allows this integration to go a lot more smoothly. For example, Rockwell’s PlantPAx DCS, or distributed control system, is a single, integrated plant-wide control platform for process automation, environmental monitoring and building management. The DCS can validate both a process control system and meet building automation requirements.
Likewise, having a PLC-based machine level controller, such as Schneider’s Modicon M172, in HVAC systems makes it easier to communicate with process control and building automation systems. These controllers can tie into production management systems where required.
“The question really is, where does HVAC control end and process control begin?” asks Tim Skell, ABB sales application engineering manager.
When looking at applications like spray drying, the control will come from the process’s automation system, not an HVAC control or building automation system. This allows maintaining recipe management and traceability records. But when you think of cooling plants or refrigeration or freezer systems, these are often part of the process and under control of the process itself, says Skell.
Products (especially hygroscopic ingredients like sugar or powders) that are in storage would benefit from very accurate temperature and humidity control, adds Skell.
“The control may fall under an HVAC building control system or, again, as part of the automation system.”
Because ABB HVAC systems use their own variable speed drives (VSDs), they can be controlled either by a factory automation or building control system.
A brewery is an example of where process control and HVAC/building automation systems should talk, as many parts of the brewing process are sensitive to environmental conditions. To provide total connectivity between systems, New Belgium Brewery established eight “zones of control” for the brewing side of its operation. Seven of the eight, including the complex brewing processes, are controlled by Opto 22 programmable automation controllers (PACs).
The Opto 22 hardware handles all of the facility’s brewing processes, as well as the water process systems and virtually all other building management and facility systems. In total, more than 10,000 individual digital and analog I/O points are monitored and/or controlled. The systems also play a major role in the facility’s sustainability efforts and its cogeneration system, which provides heat and electricity to the brewery.
Benefits to linking process and building controls
What are the benefits of integrating or linking the HVAC/building controls system with the process control or quality system responsible for making the product?
“Integrating/linking of data—there are a lot of words that get used for this,” says Michael Risse, Seeq Corporation VP/CMO. “Most common is contextualization: putting data in the context of its environment.”
For example, was it hot or cold? Was it humid or dry? Was it first shift to third? Were the ingredients from supplier A or B?
Answers to all of these questions could better inform an analysis as to what has an impact on a process or business outcome, to go from an equation with five or seven variables to one with 15 or 20 and thus gain that additional precision over variation associated with a higher degree of detail, adds Risse. Analyzing all this data will allow the plant or facility to improve quality, yield, margins, asset uptime, predictive maintenance, etc.
“Using two disparate systems for process control and building controls introduces unnecessary complexity into food production that is often already complex,” says Rockwell’s Homan. Integrating the two, along with energy management, can help reduce the total costs and increase efficiency.
By using a single control platform for both systems, operators have one view of all systems to identify more proactively potential issues and better predict how one could affect the other, adds Homan. For example, an issue with air conditioning could affect quality control in a frozen food processing plant, or an increase in energy use in one part of the line could indicate that a motor in the packaging line requires maintenance. Leveraging one combined platform can also help reduce the number of spare parts required and streamline workforce training.
As mentioned previously, the most common form of process and HVAC control integration is the ability to change the function of air handling equipment from production mode to cleanup mode, says Matt Hartenstein, PE, Shambaugh & Son mechanical engineering manager. Shambaugh is an EMCOR company and has several engineering business groups.
Production mode will normally recirculate the internal air and maintain a temperature per the process specifications, says Hartenstein. During cleanup mode, the unit changes to 100 percent outside air and normally allows the temperature of the space to rise for more efficient drying of the process space, thus allowing the area to be placed back into production mode more rapidly.
Another use of this integration is to allow for space pressure control or monitoring, says Hartenstein. This is of particular importance to the quality control team in that the pressure relationship between process and non-process areas is maintained to minimize the risk of allergen contamination or product contamination from outside sources. By integrating the process and HVAC controls, issued alarms are seen by all stakeholders, so corrective action can be taken.
Some applications are simply well suited to an integrated control system. According to Hartenstein, “the milk powder packaging process is particularly sensitive to temperature, humidity and filtration requirements, thus lending these processes to more stringent monitoring. Aseptic filling of milk is another place where we see tight process/utility integration.”
A single integrated HVAC/process control system is simply easier to manage. Production personnel tend to be focused on making product and may not always remember to make mode changes to the building systems, says Shambaugh’s Brook Schroeder, PE, senior mechanical engineer. By linking the HVAC system to the process controls, the human factor can be removed, and these changes can be automated—facilitating the quickest return to production and to help ensure the environment is correct and safe while in production.
Data accumulated by an integrated system can be a big help in risk assessments. For example, during a risk assessment, an identified hazard within a food safety plan could be product spoilage due to improper processing, says Bühler’s Beloskur. If so, a monitor and preventative measure will be required to detect processing irregularities and implement risk-reducing measures. On this basis, satisfying the regulatory requirements would be the benefit of integrating the HVAC to process controls, says Beloskur. The integrated data of HVAC and process control could be aggregated with any required corrective measure in time-series databases and reported to satisfy a processor’s data retention plan.
Energy/utilities usage and quality
What are the benefits of integrating or linking HVAC/building controls with process control or quality systems?
“I wouldn’t couple quality with HVAC at first thought,” says Seeq’s Risse. “I would assume that optimization of energy costs in the context of a desired production outcome [i.e., energy usage] would be first on the list. Then, with HVAC variables, I’d look to quality parameters in product outcomes, since heat and humidity and air quality could be critical inputs to product quality.”
“In certain cases, products rely on the atmosphere of the production space, so the space can be controlled to optimize the output of production,” says Justin Hoover, Shambaugh refrigeration engineer. “Active pressure control goes hand in hand with quality management systems to help maintain hygienic zone conditions.”
Many processors now realize that quality systems, process control and HVAC work together. For example, Yalumba, Australia’s oldest family-owned winery, recently updated the controls at its Angaston, south Australia location. The winery’s 30-year-old-plus bottling lines were simply unable to cope with demand. To maintain the flavor and freshness of each bottle of Yalumba wine, dissolved oxygen meters with alarming were installed to avoid oxidation, and line one contains a CO2 meter to measure dissolved CO2 in sparkling wine.
The quality systems are integrated with the SCADA system, so data is collected with Rockwell’s FactoryTalk Transaction Manager to provide all relevant information on the product being bottled through the filtration skid and is stored in a historian for future reference.
The wine bottling and labeling are carried out in an insulated room that is controlled by an air conditioning system. Rockwell CompactLogix controls the air conditioning system, so that parameters, such as relative humidity, dew point and room temperature, are monitored on the SCADA system.
“We’re now using 10 percent less overall power for the bottling area compared to what was consumed prior to setting up the new lines, and we have also increased capacity on line two by 50 percent,” says John Ide, manager of winery operations.
The automation solution has also reduced labor costs and improved safety.
An integrated HVAC/process control system can deliver a real, tangible business result.
“One of the main benefits in linking HVAC and building control systems with the process or quality control system is purely financial,” says Arun Sinha, Opto 22 director of business development.
Typically, energy or WAGES—water, air, gas, electricity and steam—is treated as overhead and a fixed cost. Energy is always assumed to be “on,” and there is no correlation between it and the process.
Unfortunately, the current way of thinking is one of “process ignores environment, and environment ignores process,” says Dave McMorran, business development manager, ICONICS, a Control System Integrators Association partner member. “These two [process and environment] are part of the same ecosystem and need to be looked at as one.”
Therefore, energy savings can be gained by tracking the process and building data to see where improvements can be made in energy efficiency, says McMorran. Energy management should be looked at from a product basis, not as overhead. Why not measure the energy required to make a product? McMorran contends that this method allows efficiencies to be reviewed at a granular level, and decisions can be made around making the process more efficient.
Sinha takes this idea of energy and product a step further. The benefit of integrating process and building controls is to move toward treating energy as a variable cost and include it as a component in the “bill of materials” of the product. In process applications, the unit of measurement for the product is often in something like gallons, tons, etc. If costs per unit of water, air, gas, electricity or steam can be included along with the other costs, such as raw materials and labor, then energy management becomes a very important part of improving the bottom line.
What might be possible in energy savings? McMorran notes that by providing visibility just to the building automation system, companies typically find a 10 to 20 percent reduction in energy usage. Adding the plant could most likely double that number, and processors could potentially realize a 20 to 40 percent overall energy savings.
Integrating HVAC with the process control or factory automation system provides another benefit to the processor, and that comes not only from energy-saving opportunities, but also demand management, says ABB’s Skell.
Energy management should always be part of the process, especially with respect to electricity tariffs and day/night costs, adds Skell. For example, if a product needs to be frozen, and the rates for electricity are lower in the evening, is it possible to shift production to match the rates? Of course, it’s not always possible, depending on production demands.
Monitoring energy usage and water management has real benefits. For example, Tamaki Control’s Ackerman notes that an increase in energy usage can indicate an issue with a specific piece of process equipment. Monitoring energy usage can also help identify the biggest users and create a focal point for system optimization.
Thinking about making the connection?
Before you make any physical connection between your process and HVAC system, one option requiring little in the way of system integration would be to provide operator screens for both systems on the same HMI or portable device. This, of course, would involve approvals and access rights for those involved, but at least it would give operators a more convenient look into what both systems are doing.
In terms of making a physical connection/integration, ICONICS’ McMorran suggests a top-down approach. The first step is to get C-level management to champion the concept around energy and savings. The next would be to get operations and facility personnel together to create a plan based around high-energy usage equipment and facilities, gaining visibility into these systems. IT should also be brought in early to discuss what issues may be involved in terms of connectivity. You’ll want to discuss what it is you want to accomplish with any integration and make use of existing data you may have to help understand the relationships between process and building control systems.
In terms of energy usage, Opto 22’s Sinha suggests starting with a top-down approach as well—though he means identifying the largest loads first. Managers should correlate loads with what is actually happening in the plant, for example, anomalies like spikes in demand, energy consumption trends and conditions during steady state—like weekends or nights.
There may already be plenty of existing historical data, but unfortunately, it may be in silos. Seeq’s Risse suggests starting with any data silo to get insights and connect to other data sources as needed. But don’t get bogged down waiting for the data to be assembled and perfect—as it never is. Rather than making this an IT project, start in the plant with better analytics tools in the hands of process engineers and experts.
Shambaugh’s Austin Halter, electrical engineer, provides a few good pointers in integrating building management and process control systems:
- A robust, well-defined, communications network is required to have stable, uninterrupted interaction between systems.
- Existing plant retrofits have great potential to be successful when starting small. Close attention to scalability allows a plant to start small and add on as circumstances warrant.
- There are many opportunities to reduce HVAC-related energy usage in existing plants; however, the benefits are difficult to capture when there is not a building management system. The initial investment to implement a system in an existing plant can be steep, whereas inclusion in new plant construction is more economical.
Finally, some of the major automation suppliers have experience with both industrial control systems and building automation systems. System integrators also provide the experience necessary, and many of the architectural and engineering/construction firms have people who span the various disciplines and can bring them together.
For more information:
Tamaki Control LLC, www.tamaki.co.nz
Schneider Electric, www.schneider-electric.com
Opto 22, www.opto22.com
eRPortal Software, www.erportalsoftware.com
Rockwell Automation, www.rockwellautomation.com
Seeq Corporation, www.seeq.com
Bühler Aeroglide, www.buhlergroup.com or www.buhlercloud.com