"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.
Using control strategies designed and programmed by New Belgium's own automation team, Opto 22's hardware also handles all other processes relating to brewing, such as boiling, blending, temperature and pressure regulation, and complex cascading proportional integral derivative (PID) control loops, where the output of one PID loop calculation is used as a process variable input for calculations in a second PID loop.
In fact, Igor Valuyev, New Belgium's chief electrical and automation engineer, has programmed Opto 22's SNAP PACs to operate New Belgium's fermentation systems differently based on the type of beer being brewed. The SNAP PACs at New Belgium can perform up to 96 PID loops, which more than meets its needs.
"We have many different malt recipes. To ensure that each comes out perfect, the Opto 22 systems must perform to very specific operational standards," says Valuyev. "Mashers, mixers, milling systems, chilling systems, filtration systems and our other equipment must all be made to work together."
More recently, the brewery redoubled its commitment to sustainability by installing its own water-treatment facility, which transfers wastewater from New Belgium into a series of large ponds, and treats it with bacteria that feed on and break down organic waste. As with the brewing processes, SNAP PACs monitor and control the treatment plant's aerobic and anaerobic water treatment, including pH stabilization, sludge
dewatering and auxiliary processes. The byproduct of this pathogen purification treatment process is methane gas, which collects in a huge balloon-like container, is piped back to the brewery and fuels a combined heat and power engine that produces electrical and thermal energy. In fact, 10-15% of the brewery's power comes from this co-generated methane, which significantly decreases New Belgium's electrical demand on Fort Collins.
Likewise, Granger Electric (www.grangernet.com) in Lansing, Mich., has developed a process for extracting, refining and selling methane from decomposing organic waste in landfills. Its method uses wells to oxygenate the waste mass and expedite decomposition, recover raw biogas before it escapes and separate the methane from it. For example, one of its largest projects, Conestoga Landfill Gas Recovery near Lancaster, Pa., supplies a large food ingredient supplier located 13 miles away with enough methane to power its boilers and keep the whole plant operating. Because this biogas substitute costs about half as much as natural gas and required only the resizing of a few pipes, the food company was able to dramatically cut its power bill. "It was just another supply link that had to be put in and retrofitted into the user's existing scheme, but the cost was quickly recouped by the savings received from our program," says Joe DiFerdinando, Granger's electrical engineer.
To monitor gas-flow variables and usage, Granger outfitted the food plant's buildings with Rockwell Automation's (www.rockwellautomation.com) CompactLogix Ethernet-capable PACs, and then linked them to the PACs via ProSoft Technology's (www.prosoft-technology.com) water- and dust-tight, 802.11abg Industrial Hotspot radios (RLX-IHW-66).
"We use Cat-5 cable and power over Ethernet (PoE) for power supply to the radio and communication between the radio and the PACs. PoE allows us to plug the radios right into our PACs, plus the casing allows them to be mounted outside without weather concerns," adds DiFerdinando. "Landfill-gas-to-energy is not just environmentally responsible, it makes sense financially. The savings we offer our customers can be enough to help companies stay in the United States. Another one of our customers is one of the largest manufacturers of disposable dishware, and they were able to save enough using our natural gas substitute to add a third shift during the week and schedule weekends into production, and those extra shifts mean extra jobs. It's a nice feeling."
Jim Montague is Control's executive editor.