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<br />Facility Audit Report 7 <br />San Leandro WWTF <br />To validate the 2010 baseline, the performance of the blowers recorded in the SCADA system <br />was validated against the existing Lamson blower factory curves. They were also compared to a <br />March 3, 2011 spot measurement of flow, power, and discharge pressure with one blower <br />operating at full output. There were two important correlations to validate: 1) the power required <br />vs. airflow and 2) the system pressure required vs. airflow. <br /> <br />The pressure at the aeration blower discharge is critical to estimating the blower power <br />consumption vs. airflow. The blower discharge pressure will be higher than the system <br />pressure measured, due to friction from fittings between the discharge point and the system <br />pressure measurement point. We used a conservative estimate of 1 psig for this friction loss; a <br />well designed piping system should be substantially less, but in a retrofit scenario optimal <br />discharge pipe design is often not feasible. <br /> <br />Vendors of Neuros and ABS turbo blowers and EE-PAC positive displacement blowers provided <br />performance curves for blowers sized to operate over the lower to mid airflow range. Minor <br />adjustments had to be made to each performance curve relation to compare all three blowers <br />under the same operating conditions. These adjustments were either for discharge pressure or <br />inlet temperature. The adjustments were made with the thermodynamic efficiency equation, by <br />keeping the efficiency constant while inputting temperature or pressure adjustments, as well as <br />using the adjusted blower power requirement in the performance estimate. <br /> <br />A Sutorbilt lobe-type constant speed positive displacement blower (PD) was used for <br />performance and cost estimation to supply air to the offline basin. Its energy demand was minor <br />compared to the process air, and a constant discharge pressure was estimated based on a <br />minimal water cover depth,at the airflow preferred by operations staff. <br /> <br />A time of use power baseline cost and savings analysis was done based on June 2011 E19P <br />rate tariff using a monthly billing summary from June 2010 to May 2011 in order to weight the <br />various time-of-use rate periods. From this analysis, a blended energy and demand rate was <br />applied to the 2010 baseline data to determine annual cost savings. <br /> <br />Assumptions in the energy analysis process: <br />1. The SCADA airflow readings are accurate across the entire range. <br />2. When one or more existing Lamson blowers are required to supplement the retrofit <br />blower at higher flows, the power required is the same as measured at baseline, <br />smoothed with a regression fit linear relationship. <br />3. When operated post retrofit, the existing Lamson blowers will maintain the same <br />relationship between system pressure and airflow as the baseline. <br />4. The system pressure vs. airflow relationship established in March 2011 extrapolates in a <br />linear fashion to airflows above the measured data. <br />5. There will be a pressure drop of 1 psig between the high efficiency retrofit blower <br />discharge point and the baseline system pressure measurement point, to allow for pipe <br />friction losses. <br />6. The average ambient temperature is 65 F, for the purposes of estimating blower power <br />consumption.