In 2007, Delaware’s Kent County passed legislation requiring that users of cooling towers in the county transition from chemically based to chemical-free water treatment on their cooling systems. The reason behind this legislation was that biocide residuals in the discharge (blow-down) water going into the sewer from these systems made it extremely difficult and time-consuming to treat the water for any beneficiary purposes.
Upon reviewing this new regulation, Ismail (“Smiley”) El-Abd, P.E., a vice president with the G.F. Morin Company in Laurel, MD, advised one of his long-term clients, Wayne Rossi, director of engineering, in the Playtex Products plant in Dover, DE, that he had a solution for this mandate.
Installing the Dolphin System™ water treatment would fulfill the legislative requirements of Kent County and provide economic benefits as well. Having a solid working relationship and history of trust with Smiley, Wayne agreed to look into the possibility of changing from chemical treatment of his cooling towers and boilers to the chemical-free alternative. However, there was one major caveat: the economics of such a proposal had to be justified.
Planning to Achieve GoalsThe initial step in planning for the potential installation of the Dolphin System on four cooling towers and two steam boilers was to obtain and analyze the quality of the water coming into these cooling and heating operations. Smiley and personnel from Clearwater Systems Corporation, manufacturer of the Dolphin System, Mark Winter, director of engineering, and Jamie Downie, senior manager of technical support, looked at the conductivity setpoints for the cooling towers and boilers under chemical treatment. They agreed that the chemical-free alternative would produce savings in purchasing the water, using less water during operations through higher cycles of concentration (COC), and in reducing the water volume going to sewer.
Based on the amount of chemicals being used, conservative estimates were that approximately 30% in water savings could be achieved under the Dolphin System. These preliminary findings interested Wayne Rossi and his team members at Playtex - Joe Konrad, Craig Weidner, and Lawrence Haldeman - to move forward with the concept.
Although the Kent County legislation on banning cooling tower discharge water into sewers was being held up in litigation at the time, there were other stimuli to make this transition. Some of Playtex’s high-profile clients were implementing green policies on their business operations and were asking their product and service vendors what they were doing to lessen the environmental footprint of their own operations. By installing the Dolphin System, Playtex would have a compelling story to tell how the plant fulfilled such goals.
ResultsThe project called for a Dolphin System installation on a cooling tower located outside the building, three cooling tower installations inside the building, and two steam boiler installations inside the building.
The outside cooling tower, used for air conditioning, comprises approximately 1,200 tons of cooling. Following the Dolphin System installation, the cooling system began to “de-scale,” with scale coming off from the fill and settling in the cold water basin of the cooling tower. The re-circulating water was crystal clear, the system was operating at higher COCs than under chemical treatment, and total bacteria counts (TBC) were in the hundreds, far better than what is typically determined as “excellent water treatment” by the Cooling Technology Institute.
Furthermore, efficient heat transfer, as indicated by the approach temperature, was being maintained. Under chemical treatment, the total water use was estimated at 16,200 million gallons per year (mgpy), while under Dolphin System treatment, the total water use is 11,340 mgpy, resulting in a 30% reduction in total water use. This reduction is a direct result of increased COCs, resulting in less blow-down or discharge water. Under chemical treatment, water discharge was calculated as 8,100 mpgy; the water discharge is 3,240 mgpy under Dolphin System control, resulting in a 60% water discharge reduction.
The inside cooling towers, specifically tower 3, 4, and 6 are used to maintain humidity control so the cellulose fiber used to make Playtex products can be processed. At first, the TBC results from this tower were considerably higher than the results from the outside tower, due to an inordinate amount of cellulose dust in the surrounding air. The joint decision among G.F. Morin, Clearwater, and Playtex personnel was to replace the cooling tower fill pack and drift eliminators, thereby bringing the overall cooling system back to its initial condition. An improved filtration system was also installed to minimize cellulose fiber concentration.
When these adjustments were made, TBC counts noticeably decreased. Within two to three weeks, TBCs were under 1,000 colony forming unit (cfu)/ml. Under chemical treatment, the total water use for this tower was calculated as 4,990 mgpy, as compared to Dolphin System water use at 2,851 mgpy, resulting in a 43% reduction in water use (a direct result of increased COC resulting in less blowdown water). Under chemical treatment water discharge was calculated at 3,564 mgpy. Under Dolphin System control, water discharge is 1,426 mgpy, equating to a 60% reduction in water discharged to sewer.
Later on, when cooling towers 3 and 4 were initialized under Dolphin System operation, neither the fill pack nor the drift eliminators were changed. Still, the TBC levels were reduced to less than 2,000 cfu/ml, then later averaging less than 1,000 cfu/ml.
The two boilers operate on alternative annual use (one boiler in operation for a year, then shut down as the other one goes into operation, etc.). After a season of operation under Dolphin System control, the boiler in use was opened and found to be in optimal condition: no scale, no corrosion. These operational results correspond directly to energy savings through maintaining efficient heat transfer properties.
The Playtex team was very committed to making the transition from chemical treatment to chemical-free treatment work. Investing in the Dolphin System and in new filtration was well worth the investment. Payback has already been achieved, and continued cost savings will make its mark for years to come, all with creating a safer and healthier environment for Playtex employees and their community.ES