Replacing sodium hypochlorite with bleach generators for industrial cooling tower water treatment | News press | MIOX

Case Study: Cooling Water Treatment at Power Plants of Puerto Rico Power Authority

CASE STUDY

Cooling Towers at Power Plants of Puerto Rico Electric Power Authority

MIOX sodium hypochlorite (chlorine) generators remove and prevent biofilm, at a cost 50% lower than delivered sodium hypochlorite. MIOX on-site generation boosts power production output at one of the major Puerto Rico power plants by 7%, achieving annual savings of more than $3.4 million.

LOCATION

PREPA Palo Seco Power Plant (590 MW)
San Juan, Puerto Rico, USA

EQUIPMENT & CHEMISTRY

Dual MIOX oX Cells
30 lbs/day MIOX Mixed Oxidant Solution

PREVIOUS DISINFECTION

Sodium Hypochlorite 12.5%

CUSTOMER’S CHALLENGE

In 2010, one of the Power Plants of Puerto Rico Electric Power Authority (PREPA) faced a crisis due to biological growth in their power plant’s cooling tower. The plant was using straight hypochlorite, which was not effective at controlling biological growth. Consequently, plant heat exchangers were plugged and temperature rose above manufacturers specifications due to biofouling of the condenser tube sheets which inhibited effective heat transfer. Due to the biofouling, the units were operating above their limit at 5 or 6 grades over manufacturers specifications even with the valves fully open. The heat exchangers were incapable of removing all the heat, which resulted in a drop in the plant’s energy output.

MIOX’S SOLUTION

Instead of using an expensive proprietary biocide, MIOX’s Puerto Rico channel partner, New Technology Systems, Inc. (NTS), installed a MIOX chemical generator at the site and started treating the water with Mixed Oxidant Solution (MOS) chemistry. PREPA witnessed an immediate improvement in temperature and the energy load of the plant started to increase. After installing the MIOX system, the temperature decreased, and all the generating capacity lost due to biofouling was gained back because the exchanger was cooling effectively. It resulted in 40 megawatts of additional capacity in just one month.
In total, the power authority’s chief chemist estimates that the switch to MOS chemistry returns an overall savings over $3.4 million per year.
Due to the success experienced at the Palo Seco Power Plant, NTS installed similar treatment systems at all of PREPA’s nine power plants on the island of Puerto Rico.

RESULTS

Since the MIOX Dual oX Cell system’s installation in 2010, the PREPA Palo Seco Power Plant has realized millions in annual savings due to:

  • $3.4 MILLION ADDITIONAL CAPACITY

Boosted power plant production by 7% due to improved efficiencies after biofilm and scaling removal translating to $3.4 million in additional capacity.

  • $1.4 MILLION O&M SAVINGS

57% reduction in operation and maintenance (O&M) costs. When the heat exchangers would plug, the temperature would cause them to break. Prior to utilizing MIOX systems in their cooling towers, PREPA’s O&M costs were approximately $2.5 million a year. After the system was running on all units, O&M costs fell to $1.1 million; nearly a 57% reduction.

  • ELIMINATE 31,000 LBS DELIVERED CHEMICALS

Reduction of 31,000 pounds of delivered chemicals per year, in addition to the savings for shipping, handling, storage, training and documentation for those chemicals.

  • 56% REDUCTION IN WATER CONSUMPTION

56% reduction in water consumption from 72 million gallons per year to 32 million gallons per year.

  • $300,000 REDUCTION IN ENERGY CONSUMPTION

$300,000 in energy consumption per idled pump. The solution from MIOX allowed PREPA to shut down one of the cooling tower’s two 400-horsepower pumps required to push water through the previously biofouled system—each of which uses about 4.8 million kilowatts per hour at a cost of $300,000 a year in energy consumption.

  • 50% REDUCTION IN CHEMICAL COSTS

50% biofilm reduction at a cost 50% lower than bulk hypo.

 


Case Study: Cooling Water Treatment at Power Plants of Puerto Rico Power Authority