Process, power and plant controls join forces to achieve performance gains

These three control types have evolved to use more software and digital components, removing many of the functional obstacles between them and allowing them to communicate more freely.

By Jim Montague

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Remember when electricity was an accounting job? Remember when plant tasks were mostly maintenance? Remember when process control was just in isolated loops?

For many, those memories are yesterday's and today's—not to mention many difficult days to come. For others, it's an old and isolated perspective that's rapidly shrinking in their rearview mirrors, as they coordinate their increasingly digital process, plant and power controls to various degrees and in combinations of twos and even threes that can cooperate to achieve new levels of efficiency, optimization and performance.

In past years, power distribution/conditioning and building management/automation systems (BMS/BAS) historically provided the energy and environment for production, while process control monitored and optimized operations as they happened. However, as all three control types evolved to use more software and digital components in recent years, they've also grown more similar in appearance and in how they're applied. This removed many of the functional obstacles between them, allowing them to communicate more freely and begin to make performance gains by working in unison.

"Process, power and plant control are coming together for two reasons. We're seeing a push from the top in favor of technology that's blurring the lines between these formerly distinct functions. Meanwhile, users want the ability to blend production and facility responsibilities, and do more with reduced headcount," says Will Aja, customer operations VP at Panacea Technologies Inc., a CSIA-member system integrator in Montgomeryville, Pa. "However, most building and power systems are fundamentally different from process systems, and they don’t provide a seamless interface between each other. They also have different languages, programs, hardware and lifecycles, as well as proprietary features that sometimes aren’t shared with clients out of the box.

2017 State of Technology Report: control systems

"We're studying three and working on two BAS migration projects for pharmaceutical applications, and evaluating what DCS or BAS might replace them. A BAS can do power and building automation, but it doesn’t handle true process applications well. Our studies show a DCS can successfully control building automation, utility generation and process control, though most manufacturers will segregate the functions under a common platform. Even segregated, this leads to stocking parts for fewer systems, less training costs, and better lifecycle support options, as well as integrated reports between the two systems."

Ira Sharp, product marketing manager for control, safety and I/O at Phoenix Contact, adds that, "There's a growing trend of users seeking to tie their industrial applications and assets to their building systems. If you have a process or factory line running with PLCs, and lights and HVAC running nearby on a BAS, then the idea is to connect them for better resource conservation. Maybe not as much light or cooling is needed based on what operations is doing?

"The other piece is better analytics. Where we used to have three separate control systems and independent consoles for process, power and building, software like Niagara 4 from Tridium Inc. has drivers that can bring together data from these disparate systems onto one interface. Our ILC 2050 BI building controller runs Niagara in an industrial hardware package that can bridge facility and factory production."

Closer to fine

"To move air and control temperature, humidity and pressure, BMSs historically used thermostats or larger devices, but recently they've been transitioning more to PLCs, which semiconductor manufacturers and data centers use for finer control," says Ed Elliott, business manager of the Process Automation Group at Wunderlich-Malec Engineering, a CSIA-certified system integrator, fabricator and engineering firm in Eden Prairie, Minn. "Previously, commercial temperature transmitters kept applications at ±2-3 °F, but their response time was slow. Presently, while some data centers can be at ±4-5 °F, their equipment needs to be kept at ±0.5% relative humidity, while some semiconductor fab areas need to be maintained at ±0.5 °F.

"What's happening is, other users want this tighter control for their processes, such as pharmaceutical applications that need room-to-room zone pressure control at ±0.5 inch water column (in.WC) barometric pressure, which is 0.02 psi. Many regular building applications may also need more accurate instruments because a difference of just 2 in.WC between rooms can create pressure on doors. This is why uses are going with more high-end instruments or putting many more regular instruments in more places."

For instance, instead of using 50 regular temperature probes and transmitters in a typical facility, Elliott reports that some users are deploying 200 of these lower-end devices, but averaging their results for greater accuracy and more granular measurement in more locations. Meanwhile, he adds, some users may also decide to add higher-end temperature transmitters with ±0.05 °F accuracy that can determine ±0.5% relative humidity as a reference check on the regular transmitters.

"Putting thermocouples every 4-5 feet all over an application or building makes it much easier to find hotspots more quickly, which allows for specific zone control of temperature, saving on energy and other expenses," explains Elliott. "These savings are crucial for data centers and other facilities, which require BMS equipment that can't fail because they're often built and rented as reclassified space that's guaranteed to be secure and maintain very specific environmental conditions."

Melissa Topp, senior global marketing director at Iconics, adds that, "Over the past decade, many automation software vendors, Iconics included, have noticed the increasing need in building automation applications for monitoring and control abilities traditionally found in HMI/SCADA for industrial automation or manufacturing processes. Building operators now require the same level of data visualization, analysis, historical storage and mobility previously only found in legacy process control systems.

"The process-power-plant convergence is due to each automation vendor’s ability to integrate with multiple disparate data sources. On the industrial side, this involves OPC-UA or Modbus. On the building controls side, devices and software typically communicate via BACnet. For networking or office machinery, communication may occur via SNMP. On the software side, some applications, including those from Iconics, allow quick recognition of electric, gas, water and other meters for energy monitoring, or equipment specifications for fault detection and diagnostics."

Upgrade and unify

Probably the choicest time to try to bring process, power and plant controls closer together is during scheduled downtime for renovations and migrations to new control systems.

For example, when Eastern Province Cement Co. (EPCC) in Saudi Arabia revamped the electrical infrastructure on two 30-year-old production lines at its plant in Al Khursaniyad in 2016, the company upgraded its existing 75 medium-voltage (MV) switchgear panels to new protection relays, but it also integrated these power supplies with the plant's existing 800xA distributed controls from ABB.

“ABB completed the final upgrade onsite during planned maintenance shutdowns, and teamwork by EPCC and ABB engineers made it possible to meet this challenge without affecting the other production lines,” says Mohammad Arif Khan, electrical and instrumentation manager at EPCC.

The project included replacing the old protection compartment of the 75 MV (13.8- and 4.16 kV) switchgear panels with ABB Relion protection relays, integrating via IEC 61850 compliance with 800xA, and implementing other computer and network equipment. ABB also provided project management, engineering, site services and training together with its supplier EcoWatt Projects AG.   

Likewise, Anchor Glass Container Corp. reports one of two old melting furnaces at its food-grade container plant in Shakopee, Minn., was causing energy inefficiencies, threatening productivity, and not allowing more than two weeks of production data to be viewed. The facility is one of six that takes crushed, recycled glass; chemicals and other raw materials, melts it at 2,700 °F, and produces about 600 bottles per minute, or about 300 million per year with about 18 changeovers per month (Figure 1).

The larger, 27 x 46-foot furnace is 17 years old, and needed to be re-bricked because its aging bricks provided poor insulation. This meant the furnace couldn't maintain consistent temperatures, wasted energy, and risked producing lower-quality product. The glassmaker adds its furnace's need for better thermal control was most evident in its reversal process, which relies on the regenerative furnace to maximize heat utilization. One side of the furnace captures heat; the process is reversed; and captured heat is reused by injecting it back into the furnace. Without tight control during this process, the furnace lost even more heat, and Anchor lost even more revenue.

In addition, the furnace's old thermal monitoring system wasn't user-friendly, required time-consuming manual adjustments and charting, and only stored two weeks of data. This lack of data visibility made monitoring and trending difficult, and prevented valuable analysis. Furnace operators also relied on an old, analog alarm system with only 12 alarms for the plant.

To develop a new furnace control system, Anchor Glass worked with longtime collaborator Stone Technologies Inc., a CSIA-certified system integrator from Chesterfield, Mo., and they implemented a PlantPAx DCS from Rockwell Automation to monitor more than 1,000 tags and 2,600 alarms, which are tracked for frequency to improve predictive maintenance. Historian software in the PlantPAx system also gathers data on furnace temperature, air pressure and other data points, which are viewable on an intuitive HMI with detailed sequencing that allows Anchor's operators to fine-tune processes for more energy efficiency. PlantPAx also let Anchor Glass adopt more intuitive controls with consistent faceplates that require less training to operate, which was essential because only six staffers run the Shakopee plant.

“Everything we do relies on temperature control,” says Kyle Fiebelkorn, batch and furnace manager at Anchor Glass. “Implementing PlantPAx gives us improved batch management and data collection to monitor our furnace operations.”

To address energy losses during furnace reversal, Stone Technologies implemented scalable, controller-based sequencing that gives Anchor Glass' operators better control over each step of the reversal process. The system integrator also convinced Anchor Glass to employ new controls for slow processes by using the PlantPAx internal model control (IMC) process function, which assisted slow-acting loops such as Anchor's glass level and temperature control.

“IMC for advanced process control applications provides a simplified control algorithm and model to provide better control without reaction to disturbances created by reversal or other factors,” explains Brad Downen, MES project manager at Stone Technologies.

This enhanced data visibility lets the glassmaker's operators manage temperature stability better during every minute of their day, recognize operational trends and patterns, pinpoint potential problems faster, and efficiently produce the optimum number of bottles per day. Since implementing PlantPAx at the Shakopee plant in 2013, Anchor Glass has also installed similar systems in three of its other facilities.

“Since rebricking the furnace and implementing the PlantPAx solution, we've seen huge savings in our gas and electrical expenses,” adds Fiebelkorn. “I'd estimate an average of 15% of the cost savings is from having a better control system on the furnace.” In all, rebricking the melting furnace and implementing PlantPAx have improved glass quality and saved the Shakopee plant about 350 dekatherms per day, or about $766,500 in gas per year gas and $337,260 in electricity per year.

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