Electric-hydraulic reversing energy recovery device

Abstract

The invention provides an electric-hydraulic reversing energy recovery device, which is simple in control and less in pressure oscillation. The device comprises an electric-hydraulic reversing valve, two pressure exchanging pipes and four unidirectional check valves. A free piston is arranged in each pressure exchanging pipe to divide the pressure exchanging pipe into two working cavities which are a transmitted liquid working cavity and a waste liquid working cavity. The device has the following beneficial effects that because the electric-hydraulic reversing valve is piloted by using a magnetic pilot valve, and the main valve is pushed by the high pressure waste liquid which is manipulated and controlled by the magnetic pilot valve in the system pipeline, the pushing power can be very large, the operation is simple, and the reversing is stable and fast. The electric-hydraulic reversing energy recovery device is suitable for a reverse osmosis desalination system with high pressure and large flow rate.

Description

technical field [0001] The invention relates to a pressure exchange device for transferring pressure energy from one fluid to another fluid, in particular to an electro-hydraulic reversing energy recovery device used in a reverse osmosis seawater desalination system. Background technique [0002] Reverse osmosis technology belongs to pressure-driven membrane separation technology. The semi-permeable membrane used in the process operation organically separates fresh water and concentrated sea water, and separates fresh water from sea water or brackish water under high pressure. The separated fresh water is discharged as permeate, and the remaining concentrated seawater or brackish water is discharged as brine. In reverse osmosis seawater desalination projects in my country, the operating pressure is generally between 5.0-6.8MPa, and the pressure of concentrated seawater discharged from the membrane unit is still as high as 4.8-6.6MPa. If calculated according to the usual 40%...

AI Technical Summary

Problems solved by technology

In these three designs, the main structure of the energy exchange adopts relatively complex moving parts

In addition, the efficiency of hydraulic turbine energy recovery devices is low, and the general energy recovery efficiency is between 40% and 70%; The efficiency of the recovery device is as high as 94%, and it has become the focus of research and promotion at home and abroad

[0004] Chinese patent ZL98809685.4 discloses a pressure exchanger. The pressure exchanger is limited by the speed of the rotor and the volume of the rotor channel. The processing capacity of a single PX is small. Secondly, the rotor channel is not equipped with a solid piston to isolate seawater. Mixing with concentrated seawater, the mixing section sacrifices about 50% of the volume of the rotor channel, and at the same time, the salinity of the pressurized high-pressure seawater increases, thereby increasing the operating pressure of the system; finally, when the flow rate changes, the rotor speed will be affected, resulting in poor system operation. Stable, and the large amount of noise emitted by the rotor during operation seriously pollutes the surrounding environment

The device uses 4 electromagnetic three-way valves to switch between high-pressure concentrated water and low-pressure seawater. Due to the slow switching speed of the electromagnetic three-way valves, at least two sets of devices need to be connected in parallel to work alternately to meet the pressure and flow fluctuation requirements of the reverse osmosis system; At the same time, due to the large pressure difference between the high and low pressure sides under seawater desalination conditions, firstly, the electromagnetic head with sufficient torque must be able to drive the electromagnetic three-way valve, and secondly, the electromagnetic three-way valve must overcome the unbalanced force on the high and low pressure sides to achieve long-term stable operation. It is still a difficult problem at present; the device requires a relatively complicated valve control system, and the electromagnetic three-way valves cannot form a reliable mechanical interlock with each other at the moment of switching. There are large fluctuations, and the practical application is limited

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