Differential energy recovery device and method for seawater desalination system

Abstract

The invention discloses a differential energy recovery device and a method for a seawater desalination system. The differential energy recovery device comprises two hydraulic cylinders connected in parallel. A piston divides each hydraulic cylinder into two cavities. The piston is fixedly connected with a piston rod. A low-pressure raw water inlet is connected with two left cavities through liquid inlet valves. The left cavities are connected with a high-pressure raw water outlet through liquid drain valves. Two right cavities are connected with reversing valves. The reversing valves are connected with a high-pressure concentrated water inlet and are connected with a low-pressure concentrated drain outlet. The method is that high-pressure concentrated water coming from a reverse osmosis device is enabled to enter the right cavities of the two hydraulic cylinders through the reversing valves, and low-pressure raw water in the left cavities is pushed and pressurized to enter the reverse osmosis device. Since the direct pressurization principle of the hydraulic cylinders is used for the special design, one-time energy conversion is adopted and the pressure of high-pressure seawater after pressure exchange is larger than the pressure of concentrated saline water, the invention has the advantages that the pressurizing pumps are not required for pressurization once more, the energy conversion efficiency is high, the operating cost is saved and the energy consumption of the reverse osmosis system is further reduced.

Description

technical field [0001] The invention relates to the field of seawater desalination, in particular to a differential energy recovery device and method of a reverse osmosis seawater desalination system. Background technique [0002] An important goal of the development of seawater desalination technology is to reduce operating costs. Energy consumption accounts for the largest proportion of operating costs. Therefore, reducing energy consumption is the most effective means to reduce the cost of seawater desalination. Reverse osmosis seawater desalination is one of the mainstream technologies of seawater desalination at present. The reverse osmosis seawater desalination process needs to consume a lot of electric energy to increase the inlet water pressure to overcome the osmotic pressure of the water. The residual pressure of concentrated water discharged from the reverse osmosis membrane is as high as 5.5-6.5MPa. According to the calculation of the recovery rate of 40%, the di...

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Problems solved by technology

Piston-type valve-controlled pressure exchangers need to be equipped with a booster pump to boost the initial boosted raw seawater into the RO system. The booster pump needs to be made of seawater corrosion-resistant materials and has high requirements for sealing. Currently, it is purchased through imports, and the cost very high

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