Aaron Fagen, Manager of Chilled Water Services, stands next to a concentrated sulfuric acid-injection system in an OUC Chilled Water plant.
Driven by a desire to be “good stewards of resources,” OUC’s Chilled Water Services division, OUCooling, has adopted a technology that substantially reduces the amount of water a chilled water plant uses.
With the installation of a concentrated sulfuric acid (CSA)-injection system, the Downtown North chilled water plant consumes nearly 25% less water, saving 8 to 10 million gallons of water annually when compared to the 2017 production baseline. OUC has retrofitted two other plants with the system and plans to install it on other chilled water units located throughout Orlando. OUCooling provides commercial customers, such as apartment and office buildings, an efficient and affordable air-conditioning solution.
“What motivated Chilled Water Services to adopt this system was we wanted to be good stewards of resources like everybody else at OUC and in the community,” said Aaron Fagen, Manager of Chilled Water Services. “With the installation of the acid-feed systems, we’re using a lot less water now.”
The upshot of CSA injection is increased cycles of concentration (COC), or the number of times water can be recycled in the chilled water process before it has to be “blown down,” or discharged. The standard COC for a chilled water plant is three, but that number increases to eight or nine with the addition of minute dosages – totaling about 7 gallons per plant per day – of CSA, which lowers the pH level in the water. The drop in pH lessens the potential for the calcium carbonate hardness in water to build up on condenser tubes of the chiller, which could degrade system efficiency.
The key results of the updated process are a significant decrease in water consumption and a 65% reduction in wastewater discharges into the sanitary sewer system. The cost to implement the system is approximately $80,000 per plant, and OUC recovers the investment in about a year, said Fagen.
“This is not a new technology, but the safety of the product was a concern,” he said, referring to sulfuric acid, a hazardous chemical. “We found a vendor with expertise in this area, and they manage the dosing and chemical deliveries. Our employees don’t touch it. Numerous safety mechanisms are in place, and all injection piping is double walled.”