Membrane-process seawater desalination system without pretreatment process

Abstract

The invention relates to a membrane-process seawater desalination system without pretreatment process. The system comprises a reverse osmosis subsystem used for separating brine at an inlet into freshwater and strong brine; a pressure damping osmosis and hot-membrane osmosis subsystem used for supplementing water and heating the strong brine at an outlet of the reverse osmosis subsystem and returning to the inlet of the reverse osmosis subsystem to realize stepped supplemented water circulation; and an organic Rankine cycle subsystem used for providing exchange heat for the pressure damping osmosis and hot-membrane osmosis subsystem. The pressure damping osmosis and hot-membrane osmosis subsystem comprises a forward osmosis membrane element, a porous membrane element and a deep sea seawater introducing mechanism. The reverse osmosis subsystem, the forward osmosis membrane element, the porous membrane element and the organic Rankine cycle subsystem are successively connected. The deepsea seawater introducing mechanism and the forward osmosis membrane element are connected. A salinity and water temperature measuring point is arranged at the outlet of the porous membrane element. incomparison with the prior art, the invention has the following beneficial effect: by stepped water supplementation for strong brine at the outlet of the reverse osmosis subsystem, recycling of strongbrine is achieved, and then investment and operation costs are reduced.

Description

technical field [0001] The invention belongs to the technical field of seawater desalination, and relates to a membrane seawater desalination system, in particular to a membrane seawater desalination system without a pretreatment process. Background technique [0002] Fresh water is one of the indispensable resources for human survival. According to statistics from the Ministry of Water Resources, 9 of China's 14 open coastal cities are seriously short of fresh water resources. Seawater desalination has become an important technology to solve the shortage of fresh water resources in coastal cities. At present, seawater desalination technology is mainly divided into distillation, electrodialysis and membrane method. Membrane seawater desalination technology has become the mainstream of seawater desalination technology due to its advantages of low energy consumption, continuous and stable operation, and small footprint. [0003] Although membrane seawater desalination technolo...

AI Technical Summary

Problems solved by technology

First, the cost of water production is high

The main operating costs are concentrated on the power consumption of water pumps, pretreatment chemical reagents and replacement costs of reverse osmosis membranes, especially the power consumption of high-pressure pumps in reverse osmosis systems. In addition, with the improvement of water quality requirements, imported seawater pretreatment process The requirements are gradually increasing. In order to prolong the service life of the reverse osmosis membrane, the imported seawater needs to maintain a certain temperature, which also indirectly increases the cost of water production.

Second, the pressure on environmental protection is huge

Third, the initial investment cost is high

[0004] Chinese patent CN102249459B proposes a seawater desalination system. Although the use of a two-stage reverse osmosis system increases the water production ratio, improves operating efficiency, and reduces operating costs, it is composed of a coagulant dosing device, a grit chamber, and a fungicide dosing system. equipment, water pumps to lift water from the grit chamber to the multi-media filter, multi-media filter, self-cleaning filter, and ultrafiltration equipment, the huge pretreatment process makes the initial investment cost of the system too high, and does not take into account the discharge Contaminant Treatment Issues

Chinese patent CN104692492B proposes a reverse osmosis seawater desalination device based on the organic Rankine cycle. Although it can reduce the power consumption of the high-pressure pump and maintain the water temperature at 38°C-45°C, it only makes technical improvements to the middle part of seawater desalination and does not consider It cannot be regarded as a complete seawater desalination system due to the pretreatment process in the early stage and the discharge in the later stage

Images