Ozone Process Control and Monitoring at Las Vegas

摘要

The Southern Nevada Water Authority (SNWA) ozone facilities at thern2270 MLD (600-MGD) Alfred Merritt Smith and 570 MLD (150-rnMGD) River Mountains Water Treatment Facilities were installed tornattain an enhanced disinfection barrier of 2-logs Cryptosporidiumrnoocyst inactivation credit. Both facilities generate high-concentrationrnozone from high-purity oxygen gas that is generated on-site withrnvacuum-pressure-swing-adsorption (VPSA) oxygen productionrnequipment. Both facilities are direct filtration plants with pre-ozone.rnThe plants are operated a low water flow rates during the day and atrnnear peak flow rates at night in order to reduce daytime power demandrnand lower overall electrical expense. Constant-concentration andrnconstant-range-concentration control logic was examined. Constantrange-rnconcentration logic was selected because it uses feed forwardrncontrol algorithms that provide quicker adjustment to ozone productionrnrate-change needs.rnMonitoring data are summarized in tabular format on the computerrncontrol screens. The consideration is to provide operating, supervisoryrnand management staff with a quick and complete picture of importantrnoperating and performance parameters for the ozone system. These datarncan be utilized in multiple activities, such as troubleshooting,rnoptimization, balancing parallel unit operation, and training.