| Abstrakt: |
For seawater reverse osmosis (SWRO), the electrical energy consumption by pumps takes a major share in the water production cost, thus the optimal design and operation of the major process pumps are essential. Two major pumps in SWRO are the seawater supply pump (SSP) and the high pressure pump (HPP). In order to improve the energy efficiency of the 2 million imperial gallons per day (MIGD) line of the Gijang SWRO plant in Busan, Korea, the required hydraulic head of the SSP is analyzed from the plant operation data and the SSP head is adjusted by removing one of the four impeller stages and trimming the remaining impellers. In addition, a variable frequency drive is added to the existing HPP for optimal operation to the seasonal seawater temperature variation. The energy savings are carefully evaluated from the plant operation data, and it is found that about 89 kW from the SSP and 105–326 kW from the HPP could be saved. In terms of specific power consumption (SPC), these are 0.221 and 0.261–0.811 kWh/ton reduction. Second law (exergetic) analyses are conducted and it is found that the unnecessary exergy destructions in the pressure regulating valve after the SSP and the control valve after the HPP are minimized from the modifications. The second law efficiency of the Gijang 2 MIGD line is improved from 42.83% to 46.61%, resulting in the SPC drop from 4.213 to 3.493 kWh/ton at about 16°C based on the first pass SWRO permeate water flow rate. [ABSTRACT FROM AUTHOR] |
