System for producing fresh water

A technology for manufacturing systems and fresh water, applied in seawater treatment, energy waste water treatment, water/sewage treatment, etc., can solve the problems of deteriorating osmotic membranes, lowering the purity of fresh water, corrosion of metal structures by ammonia water, etc. energy effect

Inactive Publication Date: 2012-09-19
HITACHI LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] In this method, there is generation of NH 3 Problems such as high pH ammonia water corrodes metal structures or deteriorates permeable membranes
In addition, the removal rate of the salt removed by the forward osmosis membrane is not 100%. Therefore, if the circulating high-osmotic pressure solution is used for a long time, the NH 3 and CO 2 The salts not removed in the separation process are concentrated, the purity of the obtained fresh water is reduced, or cations and carbonates in seawater are formed and precipitated in the device.

Method used

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  • System for producing fresh water

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no. 1 approach 〕

[0048] figure 1It is a block diagram of the fresh water production system concerning 1st Embodiment of this invention. The fresh water production system of the present embodiment consists of a pretreatment device 2 that takes in seawater, a forward osmosis membrane treatment device 3 connected to the pretreatment device 2, a crystallization device 5 connected to the forward osmosis membrane treatment device 3 via a cooling device 4, and a Heating device 6b, water pump 15 are connected with the reverse osmosis membrane treatment device 7 of crystallization device 5, the switching device 8 that is connected with reverse osmosis membrane treatment device 7, are installed on the piping that connects reverse osmosis membrane treatment device 7 and switching device 8 The chloride ion sensor 13 and the storage tank 14 connected to the switching device 8 constitute, the crystallization device 5 is connected to the forward osmosis membrane processing device 3 via the heating device 6a,...

no. 2 approach 〕

[0083] image 3 It is a block diagram of the fresh water production system concerning 2nd Embodiment of this invention. The system of this embodiment is based on the structure of 1st Embodiment, and the structure which provided the heat exchanger 31a, 31b between the crystallization apparatus 5 and the heating apparatus 6a, 6b.

[0084] In the heat exchanger 31 a, heat is recovered from the hypertonic solution discharged from the forward osmosis membrane treatment device 3 . The recovered heat is transferred to the heat exchanger 31b via the fluid used as the medium, and is again heat-exchanged with the slurry and supernatant discharged from the crystallizer 5 . The fluid used as the heat medium circulates between the heat exchangers 31a and 31b, and is used when cooling the hypertonic solution before the crystallization treatment and heating the slurry and supernatant after the crystallization treatment are continuously performed. When the predetermined water temperature is...

no. 3 approach 〕

[0089] Figure 4 It is a block diagram of the fresh water production system which concerns on 3rd Embodiment of this invention. The system of the present embodiment is based on the constitution of the first embodiment, and a pressure transducer 41 is set between the flow path connecting the forward osmosis membrane treatment device 3 and the cooling device 4 and the flow path connecting the heating device 6b and the water pump 15 composition.

[0090] The hypertonic solution discharged from the forward osmosis membrane treatment device 3 is introduced into the pressure transducer 41 . The pressure of the hypertonic solution is transmitted to the supernatant water of the crystallization device 5 connected to the pressure transducer 41 . After further obtaining the pressure required only for the reverse osmosis membrane treatment from the water pump 15 , the pressurized supernatant water is supplied to the reverse osmosis membrane treatment device 7 . The pressure-reduced hyp...

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Abstract

The purpose of the invention is to provide a system which uses an osmosis membrane to obtain fresh water from salt-containing raw water such as seawater, wherein the system produces fresh water at lower energy consumption. According to the present invention, the system for producing fresh water includes: a forward osmosis membrane processing means for removing salt from raw water via a forward osmosis membrane to obtain permeated water in a solution having an osmotic pressure higher than that of the raw water; a separating means for separating the solute component of the high-osmotic pressure solution, the high-osmotic pressure solution containing the permeated water obtained by the forward osmosis membrane processing means and Na2HPO4 or ethylene carbonate as the solute component; a reverse osmosis membrane processing means for desalinizing the solution separated from the solute component by the separating means as raw water through a reverse osmosis membrane to obtain fresh water; a pump for supplying the raw water to the reverse osmosis membrane processing means; and a pipe for mixing the solute component separated and collected by the separating means, in the high-osmosis pressure solution supplied to the forward osmosis membrane processing means.

Description

technical field [0001] The present invention relates to a fresh water production system which uses a forward osmosis membrane to obtain fresh water from seawater or sewer discharge water. Background technique [0002] In recent years, seawater desalination devices using reverse osmosis membranes for filtration treatment tend to increase. The reverse osmosis membrane is made of raw materials such as cellulose or polyamide, and a pressure more than twice the osmotic pressure of seawater (about 2.5 MPa) is applied to the reverse osmosis membrane to make water permeate the membrane and prevent salt from permeating the membrane, thus obtaining freshwater. The power of a high-pressure water pump for applying a pressure twice or more the osmotic pressure of seawater to the reverse osmosis membrane accounts for most of the cost of desalination of seawater by the reverse osmosis membrane. [0003] For example, Patent Document 1 discloses a method of obtaining fresh water from seawa...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/10C02F1/44C02F103/08
CPCB01D2313/243C02F1/445C02F2303/10C02F2303/16B01D61/005B01D61/002C02F1/441C02F2103/08Y02A20/131Y02W10/30
Inventor 横井浩人阴山晃治三宫丰田所秀之馆隆广
Owner HITACHI LTD
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