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December 2009

System Integration

Every last drop

Energy alternatives span continents; automation sees use to recycle energy

By Jeff Krbec

Maximizing energy is a growing global concern, and using biodiesel fuel is becoming more and more common around the world. Communities from the Falkland Islands to South Africa to Pittsboro, N.C., are doing their part to use automation to the fullest to help in recycling energy.

The Falkland Islands, located in the South Atlantic, nearly 300 miles east of the South American coast, is home to more than 2,300 people, most of who live in the capital, Port Stanley. While the Islands’ economy was originally based on revenue from sheep ranching, the creation of a conservation and management zone in the 1980s spurred income from a major offshore fishery as the driver of economic growth.

Today, improving facilities is one of the Islands’ biggest criteria. And with that comes the creation of an environmentally friendly district heat system for the main school and hospital. The installation of a new automated control system with HMI paved the way for potential expansion.

Recapture heat for power punch

With long supply lines and shipping costs, the Falkland Islands is focused on energy conservation. Authorities wanted to maximize the benefits of the Islands’ power station in Port Stanley by using recaptured heat from the station to heat the Falkland Islands Community School and King Edward Memorial Hospital.

The project involved recovering heat created by four of the largest diesel generators at the power station and reusing it to heat the school and hospital, replacing the boilers at each site, saving 55,000 liters of diesel per year.

After studying the problem several times, they decided to shelve it “due to problems in transferring heat 1km from the power plant to the community buildings,” said Peter Oldman, a manager at Stewart Thermal Technical Services, a renewable and biomass energy specialist contracted for the job.

A system to transfer the heat from the power plant uses thermal oil, rather than the traditional methods of water or steam, which helps simplify engineering difficulties and eliminate the issue of distance. The generator exhausts at the power plant emit heat at 500°C.

By installing exhaust gas heat recovery units in four of the eight generator exhausts, the engineers were able to extract heat at 300°C to heat the thermal oil. High temperature engine exhaust gas flows across a finned tubing heat exchange arrangement, which contains a mineral oil-based heat transfer fluid. The fluid heats and maintains at a temperature of 130°C by using a self-contained temperature control system, which allows the exhaust gases to bypass the heat recovery units once it achieves the required oil temperature setting.

The heat transfer fluid constantly circulates around the heat pick-up circuit by two circulating pumps (duty and standby), which draw fluid from a 5000-liter insulated storage/expansion tank and pump it through the operating recovery units and back to the tank, maintaining a constant supply of fluid at the required temperature. A secondary closed-loop district heating transfer circuit also consists of two (duty and standby) circulating pumps, which draw heated fluid from the storage/expansion tank and pump it via a single 100mm bore insulated steel-feed pipe to the high-temperature inlet connections of each plate-type heat exchanger located in the school and hospital boiler rooms.

A PLC with seven compact I/O modules operates the system. The main control system is responsible for controlling and regulating the heat transfer and temperature of the oil and the pumping system for oil transfer. The HMI, a rugged electronic interface graphics terminal, monitors and controls the system.

Designed to be simple to operate and maintain, the exhaust gas heat recovery and heat transfer fluid circulation systems operate continuously with heat take-off, controlled and regulated at the local plant rooms. System operational alarms for the pump station and exhaust gas heat recovery area are relayed to the Stanley power station control room, which is manned continuously on a 24-hour basis.

Save tons of diesel

The installation helps save an average of 55,000 liters of diesel a year, and after initial capital costs, the project should pay for itself within the first five years. However, when the project was first in discussion, the delivered price per liter of diesel was in the region of 25 Falkland pounds (FKP); it is now well over this price, so the economic benefits are rising fast. The additional good news for the environment is the system saves nearly 900 tons of carbon dioxide each year. Being fully automated, the system is also easier to control and maintain. “The temperature, the pumps, the oil flow are all automated,” Oldman said. “The system is a green button to start and a red button to stop, and the process is looked after by the PLC.”

If the system requires maintenance, engineers are able to quickly access information and make changes as required on the standardized control system. The system is also scalable for future use should Island authorities decide to extend it.

Biodiesel clears view

The Falkland Islands are not the only ones building automation into an eco-friendly service. Bioneer is a multi-disciplinary engineering consultancy responsible for the engineering and technology for the first continuous, fully automated biodiesel plant in South Africa, located in Chamdor, on the West Rand of Johannesburg.

The plant was constructed for biodiesel production company, Greenpower Fields, Bioneer & Comchem Organic Fuels (GBC) and converts used cooking oil, sourced from fast food chains, into biodiesel through a double catalytic process using methanol, as well as a two-stage settling process.

“Bioneer engineered this process to provide maximum efficiency in regards to energy, methanol, and catalyst consumption, as well as cooking-oil conversion rate. We don’t use water in the process, which means that the plant is more environmentally friendly,” said Bioneer’s Managing Director Gerrit Smith. “The biodiesel yielded is of an excellent quality and is even used in the plant’s boiler.”

Visible challenge

One of the key challenges of the project was to have complete visibility of the process plant from a central engineering station or remote location at all times. The answer included a processor housed in a 17-slot chassis, Ethernet IP bridge module for communication to the engineering workstation and for remote programming. HART-enabled analogs provided a clear vision of plant process instrument health at all times.

It is the first biodiesel plant in the country to use ultrasonic technology and solid esterification, which “converts free fatty acids from cooking oil straight into biodiesel, and is followed by transesterification, where the oil reacts with methanol, is converted to biodiesel, and the resulting glycerol is settled,” Smith said.

Seeing results

The seamless upgrade allowed for reduced engineering time, premier integration with the drives, and vertical integration for excellent visualization from the office environment straight down to the drives. It also allowed single vendor responsibility for supply of all automation equipment. Using a powerful control system and associated software “also allows us to upgrade the plant easily and seamlessly. We would even be able to add another line because we have the infrastructure to support it. There is also the potential for remote monitoring of operations,” Smith said.

The integrated architecture features a controller, programming software, SCADA system, intelligent motor control, and analogs.

Now, the plant meets environmental and safety standards and currently has a capacity of 100,000 liters per month, which will increase to approximately 500,000 liters per month once it is running at optimum levels. GBC Organic Fuels sells the biodiesel to diesel distributors to be used as a 5% blend, while the logistic trucks servicing the fast food outlets that supply the used cooking oil run on a 20% blend. Bioneer was able to obtain single-vendor responsibility for supply of all automation equipment.

ABOUT THE AUTHOR

Jeff Krbec is a business development manager for the EMEA region at Rockwell Automation. His e-mail address is jkrbec@ra.rockwell.com.

Biofuels booming business in small town By Ellen Fussell Policastro On a cold January day in 2005, Lyle Estill had a vision of vast environmental proportions; he put a board on a piece of metal frame and pulled up a chair at his new workspace in the control room of an abandoned chemical plant on the edge of the bucolic town of Pittsboro, N.C. Since that day, Estill’s small workspace has bloomed into a thriving biodiesel plant and industrial park with several buildings housing like-minded environmentally friendly business owners. “We hired welders and fitters and riggers and plumbers, and assembled a five-person crew, and we pulled in subcontractors from all over the area,” Estill said. “We bought some engineering, changed our design 17 times, sometimes on the fly, endured countless inspections, and got one of North Carolina’s first commercial facilities off the ground.” Estill sells biodiesel at a 100% or 99.99% blend.  “Sometimes, we even add petroleum to a greater percentage.” But every drop of biodiesel is fully warranted, EPA-registered biodiesel that meets the national American Society for Testing and Materials quality specification. “We are the only BQ9000 certified producer of biodiesel in North Carolina,” Estill said. “We stand behind our product and will cover any fuel quality related problems should they occur.” Estill is proud his business represents the smallest BQ9000 (quality accredited) biodiesel producer on earth. “Small is good because in traditional thinking, BQ9000 accreditation is only for the big guys, like Cargill and Archer Daniels Midland Company, who produce 100 million gallons, as opposed to us—we produce 1 million gallons of fuel per year.” Last year, Estill sold 1.3 million gallons, some of which was shipped to Rotterdam, The Netherlands. “We have thousands of visitors every year. Most of our customers are oil companies, some of which are Potter Oil, Hunter Oil, and Greenergy in the U.K.,” he said. Turnips from the biofarm will go to the local farmers market. “We used to do 2,000 gallons of fuel in the morning and 2,000 gallons of fuel in the afternoon, so a total of 4,000 gallons a day. Nowadays, we’re glad to get 1,400 gallons since production is down,” he said. Community outreach The whole idea behind Estill’s venture is to educate the community on how to transition to a low-carbon economy. Estill also sells traveling biodiesel plants. There are also small-scale plants on trailers that can “pull up behind a restaurant, gather used oil, spin oil through the plant, and have biodiesel,” Estill said. “They might make 10,000 gallons, or they could make 50,000 if they run all day, but they usually wouldn’t do that.” Piedmont Biofuels industrial park is also home to several other eco-friendly businesses who have “jumped the fence” to join this growing business community. Eco Organics is a farm co-op remaking the company’s food shed. Screech Owl Greenhouse runs a hydroponics greenhouse on the project. Vermiculture runs a worm bed that consumes all the project’s fine paper waste and is powered by ECO food waste. Piedmont Biofarms runs the farm operation at the co-op facility. Green Bean Counter Business Services is a bookkeeper/accountant who is focusing on the renewable energy tax credit niche. The Abundance Foundation has set up shop to promote advances in areas like solar, wind, and biodiesel and to encourage conservation and alternative energy paradigms. And HOMs produces natural bug repellant out of wild tomato extract and biodiesel. Myriad ways to purchase oil Anyone interested in purchasing oil from Estill can join the local B100 community by becoming a member of Piedmont Biofuels. You can buy fuel at any of the stops on the B100 Community Trail. Today, there are nine locations in the Triangle area in North Carolina, serviced by multiple companies, “and we are hard at work to add more,” he said. Estill can bring you fuel. “We have two short trucks that deliver fuel around the region. Each one carries about 1,500 gallons or so. If you have your own fueling infrastructure, we can simply drop fuel off. If you would like to buy fueling infrastructure, we can sell it to you.” Or you can visit the terminal in Pittsboro, N.C. “We have engineered and constructed the first B100 fuel terminal in North Carolina, from which we can fill top-loading tank trucks, bottom-loading tractor trailers, 250-gallon totes, 55-gallon drums, and everything in between.” ABOUT THE AUTHOR Ellen Fussell Policastro is a freelance writer /editor based in Raleigh, N.C.  Her e-mail is elizapolicastro@hotmail.com.