Serious Sustainability

In addition, the historian helped bridge the intelligence gap between the plant floor and management, and provides an accurate, long-term data management and reporting system to enable better decisions. LY Steel's project manager, Wenyi Wang, adds that one of the EMS' most important benefits is that it enabled a change in the plant's management concept from decentralized to a leaner structure. "This automation technology facilitates energy management across our enterprise and gave us a professional and efficient diagnostic tool that helps us optimize our energy efficiency," says Wang.     

Similarly, to help users gather the data needed to improve their efficiency and sustainability, Iconics (www.iconics.com) is launching its Energy Analytics software to aggregate and organize information from many process equipment sources and its Facility Analytics software to predict where possible energy offenders will arise in a given application.

Likewise, Parsec Automation Corp.'s (www.parsec-corp.com) TrakSys software also enables users to collect and organize large amounts of diverse process performance data to monitor and improve their energy productivity per item produced.    

APC's New Role

Luckily, another of the best bridges between efficiency and sustainability is well-known in many process industries—advanced process control (APC). Though historically used mostly in big-ticket processes, APC is finding wider acceptance as its costs decline and as green efforts ramp up because its sophisticated data analysis and modeling methods can help extend efficiency into the wider sustainability world.

For example, Canadian fertilizer manufacturer Yara Belle Plaine Inc. (www.yaracanada.ca) of Belle Plaine, Saskatchewan, recently sought to improve its new nitric acid plant's energy efficiency by implementing advanced process control (APC) to maintain consistent, stable, high levels of production, while simultaneously achieving tighter control of its greenhouse gas emissions. Yara is one of the largest producers of granular urea, urea ammonium nitrate and anhydrous ammonia in North America (Figure 3).

Specifically, Yara's engineers wanted to control the amount of NOx leaving their catalytic combustor, while minimizing fuel gas consumption. "We needed to maintain NOx emissions below 200 ppm while minimizing the use of fuel gas. We also needed to maintain the combustor temperature within an appropriate range—hot enough to power the expander, but not hot enough to damage it or the platinum gauze in the combustor," says Mark Sax, Yara's controls engineer. "We also saw the combustor as a potential bottleneck to increasing nitric acid production."

Fortunately, Yara had just upgraded its control system to Honeywell Process Solution's (www.honeywell.com/ps) Experion PKS, and now wanted to apply APC to it. The plant's engineers had also recently replaced their old NOx analyzer with a more reliable and accurate one. They estimated they could use Honeywell's Profit Controller application in an Experion Application Server (EAS) node that covers the whole nitric acid plant, and they implemented it over three months.

Conservatively, Yara estimates its APC project increased its nitric acid production by 3%, while tighter control of the combustor's outlet NOx permits a higher average combustor temperature, which allowed it to reduce methane emissions by 25%. Despite these gains, Sax says the project's biggest impact is that it makes Yara's operations much more stable and consistent and reduces plant upsets.

"When the operators run the plant in manual they can push the unit pretty well to its limits, but sometimes they end up swinging the unit," explains Sax. "With the new controller, the plant runs in nice flat lines, so we can achieve higher sustained production levels because it is so stable. Operator focus on the nitric acid unit has been considerably reduced, allowing them to be able to focus more closely on the urea plant that they also operate."

Similarly, Tom Kinney, Invensys' solutions developer, reports that his firm has worked with Abu Dhabi Gas Liquification Co. (ADGAS, www.adnoc.com) at Das Island in the Persian Gulf to minimize traditionally variable and inconsistent fuel gas system flaring levels. ADGAS and Invensys first installed ExperTune's PlantTriage (www.expertune.com) to identify valves that needed to be fixed and loops that needed to be tuned, and then implemented an APC approach using quadratic calculations to better match gas supply with demand from the application's boilers.

PlantTriage helped ADGAS reduce its former gas flare burn-off rate of 5.5-6 million cubic feet per day by half, and the APC solution cut it in half again for a total reduction of about 84%, which was worth about $3 million per year. "My advice is to do both, because PlantTriage can help other tools provide additional benefits," adds Kinney. "These two technologies gave us more benefits than either could have done alone."

Conserving Resources and Future Green

As process users and their applications migrate from basic efficiency to adding sustainability, most go from just saving energy to also conserving raw materials and other resources. And, once they catch the sustainability bug, they find more ways to go green. In fact, once efficiencies have been secured and resources conserved, it becomes apparent that sustainability and its supporters can return the favor to efficiency by developing some new versions of traditional applications and industries, and then eventually creating new ones.

For example, since Jeff Lebesch began making his Fat Tire Amber Ale in 1991, his New Belgium Brewing Co. (www.newbelgium.com) has grown to occupy a 50-acre campus in Fort Collins, Colo., with multiple brewing processes, water processing systems and building and facility management systems, which are monitored and controlled by more than 10,000 digital and analog I/O points that are organized into eight control zones. Seven of these zones, including the brewhouse, filtering, malting, yeasting, cellaring and other complicated brewing processes, are controlled by Opto 22's (www.opto22.com) SNAP programmable automation controllers (PACs), which monitor and regulate oven temperatures for drying and roasting the grains, machines that crush and mash them, and water and resting brew mixture temperatures. To help power all its brewing and support operations, New Belgium has used a series of wind turbines for more than 10 years.