Sherbrooke WTP upgrades to compact, efficient treatment system
In Spring 2014, the city of Sherbrooke, Quebec, Canada, installed a new Pinnacle Zenith Series ozone system to replace older ozone technology at the site. Pinnacle technology was selected based in its ability to offer the greatest functionality and lowest total lifetime cost. The new system allows ozone production to precisely match real-time demand via seamless automatic control of three ozone generator platforms using Pinnacle’s Ozone-On-Demand controls. Since installation the new ozone system has exceeded expectations in terms of performance, reliability, and operating cost.
The City of Sherbrooke water treatment plant (WTP) receives raw water from the Magog River in eastern Quebec. The plant has historically used ozone for the treatment of seasonal organics, color, taste and odor issues in its process. During significant plant upgrades in 2013, the facility decided to replace and upgrade its aging air-based conventional ozone technology, which had been in place for well over 20 years.
Pinnacle Ozone’s Zenith ozone generator system was selected based on its superior design features, low maintenance and low total ownership cost. The extremely compact and modular design of Pinnacle’s technology simplified design of the system and allowed it to be installed within the existing space at the facility. Additionally, Pinnacle’s maintenance-free ozone cells and industry leading power efficiency resulted in significantly lower operating costs over the lifetime of the project. Finally, because Pinnacle’s ozone technology does not require nitrogen gas for operation, the overall cost and complexity of the oxygen feed system were reduced.
The integrated controls of Pinnacle’s Zenith ozone system platform also helped resolve a significant technical challenge of the ozone project. Pinnacle’s Ozone-On-Demand technology allows for continuous real-time monitoring of ozone demand in each of two independent process trains. The system calculates total ozone demand for the entire process to automatically control the production of ozone. Each of the three Pinnacle Zenith ozone generators is brought on- and offline automatically based on the needs of the process. This is possible due to the unique features of Pinnacle’s technology, which allow any ozone generator to go into service in less them a minute from startup. Moreover, the system maintains constant 10% by-weight ozone concentration under any turn-up/turn-down scenario, which minimizes total operating cost.
To accommodate project needs, Pinnacle supplied three Zenith 20x ozone generator platforms, each equipped to provide approximately 280 lb of ozone per day (5.3 kg/hr). The modular design allows for up to 15% expansion via new ozone cells, should it ever be required. The overall system is normally operated with two duty ozone generator platforms and one standby unit to meet redundancy requirements. However, each of the generators, including the standby unit, are automatically brought into and out of service based on the actual ozone demand at the plant.
Since installation and startup, the new Pinnacle Ozone system at the Sherbrooke WTP has exceeded expectations for performance, cost-effectiveness and ease of use. Because the Pinnacle systems produce constant concentration ozone at any turndown, ozone transfer efficiency has significant increased across all operating points. The WTP has also realized some unexpected benefits from the upgrade. Because the new Pinnacle systems operate at five times the original concentration (10% vs. 2%), ozone transfer efficiency has been significantly increased. As a result, the plant is able to operate at much lower ozone production capacity. Overall, the WTP has realized significant savings in reduced operating cost through the combination of lower ozone dose and substantially higher energy efficiency. Equally important, the facility’s operations staff has seen much lower maintenance and seamless control of the new ozone technology, reducing overall labor costs.
Louis LeBrun, P.E., is vice president of Pinnacle Ozone Solutions. LeBrun can be reached at [email protected].