Author: Rahimov, Ashraf Rasul o‘g‘li; Murodullayev, Javoxir Raxmatillo o‘g‘li

Annotation: The paper analyses the composition, nameplate parameters and energy efficiency of the pumping fleet of the centralised water supply system of Karshi city and substantiates the electricity saving achievable through variable-frequency drive (VFD) control. Based on the primary records of the Karshi city branch of «Qashqadaryo suv ta’minoti» JSC, 164 pump units at 39 facilities were inventoried (156 serviceable, 8 out of order). For the most widespread unit, NSC200-150-460, the operating point was determined as the intersection of the pump and system curves, and the shaft power was computed for five speed settings using the affinity laws. Reducing the relative speed by 8 % (to s = 0.92) lowers the unit power by 23.9 % while the pump efficiency remains virtually unchanged (0.77 to 0.75). The system-wide computed saving is 17.7 %; with the conservatively adopted value of 14.7 % the annual saving equals 503.9 thousand kWh, or 0.50 billion soums.

Keywords: water distribution network, pump unit, variable-frequency drive, affinity laws, operating point, energy efficiency, pump efficiency, energy saving, Karshi city.

Pages in journal: 302 - 312