Method of improving performance of a reverse osmosis system for seawater desalination, and modified reverse osmosis system obtained thereby

Example

[0047]In the original system 11:

[0048]Pump power requirement is calculated as follows:

PPUMP=QW·TDHPUMP36·EPUMP

where TDHPUMP is total dynamic head of the pump, and EPUMP is the pump efficiency.

[0049]Values of the above parameters used in the present example are:

QW=800m3hTDHPUMP=65BARGEPUMP=84%PPUMP=800·6536·0.84=1719.6kW

[0050]Power supplied by the turbine is calculated as follows:

PTURBINE=QB·TDHTURBINE36·ETURBINEQB=QW-QP

where TDHTURBINE is total dynamic head of the turbine, and ETURBINE is the turbine efficiency.

[0051]Values of the above parameters are:

QP=0.48QW=384m3h⇒QB=800-384=416m3hTDHTURBINE=70BARGETURBINE=87%PTURBINE=416·7036·0.87=703.7kW

[0052]Power supplied by the motor is calculated as follows:

PMOTOR=PPUMP−PTURBINE1719.6−703.7=1015.9 kW

[0053]In the modified system 21:

PPUMP=PPUMP′

[0054]Power supplied by the motor is:

PMOTOR=1300 kW

[0055]Power supplied by the turbine is:

PTURBINE=PPUMP−PMOTOR=1719.6−1300=419.6 kW

[0056]Brine flow rate through the turbine is:

QB2=PTURBINETDHTURB