Hybrid energy recovery system
A system is designed to recover energy from a fluid processing operation that uses membranes to remove impurities from a feed stream. Energy recovery devices, such as turbochargers, an isobaric chamber and a multistage pump are utilized to recover the energy.
1 . A fluid treatment system comprising:
a first membrane for treating a fluid having an inlet for the fluid to be treated, an outlet for the treated fluid and a discharge opening for untreated fluid;
a source of fluid under pressure to be treated, operatively connected to the inlet of the first membrane;
a multistage feed pump having a first stage stack and a second stage stack, the first stage stack having an inlet port operatively connected to the source of fluid under pressure and an outlet port that is operatively connected to a first inlet opening for the second stage stack, and a second inlet opening in the second stage stack;
a second membrane for treating a fluid having an inlet for the fluid to be treated, an outlet for the treated fluid and a discharge opening for untreated fluid;
a first energy recovery turbocharger having a pump section with a feed inlet and a feed outlet and a turbine section with a brine inlet and a brine outlet, the discharge opening of the first membrane operatively connected to the feed inlet of the pump section, the feed outlet of the pump section operatively connected to the inlet of the second membrane, the discharge opening of the second membrane being operatively connected to the brine inlet on the turbine section;
a second energy recovery turbocharger having a pump section with a feed inlet and a feed outlet, a turbine section with a brine inlet and a brine outlet, the brine outlet of the first turbocharger being operatively connected to the brine inlet on the turbine section of the second turbocharger, the feed inlet on the pump section of the second turbocharger being operatively connected to the second inlet opening in the second stage stack.
2 . The system of claim 1 wherein a motor is used to drive the multi-stage feed pump, a variable frequency drive connected to the motor to provide control of the pressure of the fluid supplied to the inlet of the first membrane.
3 . The system of claim 2 wherein a motor is connected to the turbine section of the second energy recovery turbocharger, a variable frequency drive connected to the motor to provide control of the pressure of the fluid supplied to the second inlet opening of the multistage pump.
4 . The system of claim 3 wherein a first flow meter is operatively connected to the outlet of the first membrane, a second flow meter is operatively connected to the outlet of the second membrane, a third flow meter operatively connected to the discharge outlet of the turbine section of the second energy recovery turbocharger.
5 . The system of claim 4 wherein a controller is operatively connected to the first, second, and third flow meters, and to the variable frequency drive for the motor connected to the turbine section of the second energy recovery turbocharger, the controller regulating the flow rate and pressure in the system to achieve the desired pressure for the feed of fluid supplied to the inlets for the first and second membranes.
6 . The system of claim 1 wherein a pressure reduction valve is operatively connected to the feed outlet of the pump section of the second turbocharger, the pressure reduction valve regulating the flow of the fluid from the feed outlet.