Operating Performance And Stability Evaluation Of Reciprocating Fluid-switcher Energy Recovery Device Under Different Capacities

With the advantages of high energy recovery efficiency，large handling capacityand easy modularization design，the positive displacement named Fluid-SwitcherEnergy Recovery Device（FS-ERD） has become the most important equipment toreduce the energy consumption in seawater reverse osmosis（SWRO）system. Basedon the previous work by the research group and aimed at the demand for capacity inreverse osmosis desalination project，experimental performance of ReciprocatingFluid-Switcher Energy Recovery Device（RFS-ERD）under different conditions wasfurther studied in this article.At the flow rate of32m3/h and operating pressure of6.0MPa, the pressurizationas well as decompression process of RFS-ERD was tested on the pilot-scale SWROplatform. The results show that the fluctuation rules of high and low pressure fluidshave no obvious change with the increase or decrease of operating pressure, whichproves the device is of great self-adaptability at transition phase. Meanwhile, theswitching time of Reciprocating Fluid-Switcher at25m3/h and6.0MPa was studied,the conclusion of which is as follows: the pressure volatility of high pressure brine isflat with high pressure seawater when controlled at the same switching time, and thepressure volatility of both flows increase as the rise of switching time, although theincrement is small.When the operating pressure is6.0MPa, operating data of RFS-ERD at differentflow rates such as32m3/h,27m3/h and22m3/h reveals that the flow rate andpressure of high pressure brine keep good stability and synchronization, the energyrecovery efficiency of which reach up to97%, and wide operation flexibility couldmeet the demand for capacity in SWRO project.On the basis of the fact that RFS-ERD runs smoothly at three different flow rates,the utilization ratio of cylinder is also explored under the same experiment condition.The outcome indicates that the utilization ratio of cylinder is relatively low whenequipped with non-through pistons, however, as the original pistons were replaced byself-relieving pistons, the utilization ratio of cylinder increase to more than97%fromless than90%, which weakens the field noise caused by the brunt of pistons and reduces the fluctuating amplitude of high pressure fluid when the flow rates did notmatch well. The fluctuation frequency of high and low pressure fluids have gonedown and the stability of RFS-ERD have been enhanced finally.