Ozone Process Control and Monitoring at Las Vegas

摘要

The Southern Nevada Water Authority (SNWA) ozone facilities at the 2270 MLD (600-MGD) Alfred Merritt Smith and 570 MLD (150- MGD) River Mountains Water Treatment Facilities were installed to attain an enhanced disinfection barrier of 2-logs Cryptosporidium oocyst inactivation credit. Both facilities generate high-concentration ozone from high-purity oxygen gas that is generated on-site with vacuum-pressure-swing-adsorption (VPSA) oxygen production equipment. Both facilities are direct filtration plants with pre-ozone. The plants are operated a low water flow rates during the day and at near peak flow rates at night in order to reduce daytime power demand and lower overall electrical expense. Constant-concentration and constant-range-concentration control logic was examined. Constantrange- concentration logic was selected because it uses feed forward control algorithms that provide quicker adjustment to ozone production rate-change needs. Monitoring data are summarized in tabular format on the computer control screens. The consideration is to provide operating, supervisory and management staff with a quick and complete picture of important operating and performance parameters for the ozone system. These data can be utilized in multiple activities, such as troubleshooting, optimization, balancing parallel unit operation, and training.