Low-charge scenarios serving North American plants
Ammonia21, June 12, 2017
Packages and ammonia/CO2 systems reduce ammonia charge, improve safety and boost efficiency, according to ATMOsphere America case studies.
Low-charge-ammonia packaged units and ammonia/CO2 cascade systems installed at industrial plants are drastically cutting ammonia charge, increasing safety and increasing efficiency throughout North America, according to case studies presented at ATMOsphere America 2017 last week in San Diego.
For example, Evapco’s Evapcold units are reducing ammonia charge significantly at a Turner Dairy plant, enabling the facility to remain well under the 10,000-lb. regulatory threshold, according to a presentation by Kurt Liebendorfer, vice president, Evapco
Turner Dairy, a member of Prairie Farms for 10 years, operates a milk and juice processing plant in Memphis, Tenn., that has an outdated ammonia refrigeration system and is undergoing significant expansion to production and a refrigerated warehouse. The plant wants to reduce ammonia charge and improve safety with Evapco’s packaged units while avoiding disruption to production – which it can do because the packaged units are made off-site.
The plant is installing four Evapcold low-charge ammonia packaged units – two 35°F penthouse coolers (200 TR total) and two process cooling chillers (260 TR total). The total charge of the four units is 960 lbs. (2.1 lbs./TR). which is 1/10th the charge of what the system would have had in a conventional expansion system.
The chillers use secondary glycol to do process cooling (for ingredient tanks and pasteurizers), eliminating ammonia from the process area. The penthouse units also confine ammonia to the roof. Cooling to the new warehouse and existing plant is done via ducted air supplied to separate rooms.
“By significantly reducing the quantity of ammonia, including expansion, we allowed safer operation, a real reduction of the regulatory burden, and a lower cost of ownership,” said Liebendorfer. Other benefits include reduced energy consumption, no central machine room, one-day installation and faster start-up.
Low-charge ammonia chillers from Azane are being used to safely provide air-conditioning for a bakery in a populated area of Portland, Ore.
The bakery plant uses three low-charge-ammonia chillers, each at 300 TR and 450 lbs. of ammonia (1.5 lbs./TR, which received jurisdictional acceptance. They have four levels of ammonia release prevention, three levels of leak detection, and fresh air dilution. Each chiller has a TEWI (total equivalent warming impact) that is 32% less than that of a water-cooled R507 unit.
“Azane’s packaged outdoor ammonia chillers are inherently safe, energy efficient and use no water,” said Caleb Nelson, refrigeration engineer, Azane. “They have lower operating costs than traditional industrial systems.”
General Cold Storage is installing eight low-charge NXTCOLD packaged units at a facility in South Gate, Calif., according to John Scherer, chief technical officer, NXTCOLD.
The units will be used in five -10°F freezer areas and one 34°F dock. The energy efficiency is being vetted by the California Energy Commission, EPRI and Southern California Edison (SCE).
SCE has calculated an energy incentive of about $85,000; the facility is expected to save $1.4 million in energy costs over five years compared to a traditional system, and will pay for itself in 6-7 years, said Scherer.
Leading Mexican cold-storage operator Frialsa expanded a facility in Culiacán, Mexico, with a cold-storage room (350 TR), frozen storage room (130 TR) and blast freezing (71 TR).
Frialsa, which uses an ammonia/CO2 cascade system at other plants, here installed an ammonia/glycol chiller on the roof that suppliers glycol inside the building to condense a low-temperature CO2 DX system and a medium-temperature pumped CO2. The total ammonia charge is about 1 lb./TR.
Because this system is using secondary glycol, “there is no chance of an ammonia-CO2 interaction,” said Ely Espinosa, with Bohn De Mexico, who presented with Javier Atencia, chief technical officer, Tewis.
For a new Flanagan Foodservice cold-storage plant in Ontario, Canada, CIMCO Refrigeration proposed three refrigeration alternatives: all-ammonia, ammonia/CO2 cascade (with recirculated CO2, not DX), and transcritical CO2. “We were trying to find the solution that matched the customer’s requirements,” said Benoit Rodier, director of business development, CIMCO.
Ammonia/CO2 was chosen because of its lower total cost of ownership (TCO). Energy costs were the biggest contributor to TCO. “Some customers are capable of understanding TCO while most of the others have limited knowledge and are the hostage of some consultants and contractors still promoting lower initial cost Freon systems,” said Rodier.
efficient energy, a German firm, has developed an eChiller centrifugal chiller that uses water as a refrigerant. In a process cooling case study involving the condensing of a solvent, the eChiller provides a constant flow of chilled water at 64°F without temperature deviation, said Juergen Suess, managing director, efficient energy.
The process, which operates in a near-vacuum (.16 to 2.3 psi), includes 68% free cooling and 32% compressor cooling, depending on ambient temperature. It provides up to 20 kW of cooling.
The company has installed 20 eChillers to date, with 30-40 by the end of the year.