Production method for desalting seawater by de-hardening preprocessing

A production method and a pretreatment technology, which are applied in the field of desalination of seawater desalination, can solve problems such as desalination of seawater that have not been seen before desharding, and achieve the effects of simple and reliable pretreatment process, cost reduction and new technology.

Active Publication Date: 2011-04-06
天津海泽惠科技发展有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although there are quite a lot of literature on seawater desalination, so far ...

Method used

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  • Production method for desalting seawater by de-hardening preprocessing
  • Production method for desalting seawater by de-hardening preprocessing
  • Production method for desalting seawater by de-hardening preprocessing

Examples

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Embodiment 1

[0036] Example 1 3m after precipitation in the pre-sedimentation tank 3 / h seawater and 1mol / L sodium carbonate solution according to 1.2:1Na 2 CO 3 / Ca 2+ The molar ratio is 10min under the condition of a stirring speed of 60r / min. The reaction liquid is pumped into the clarifier and settled for 50min. 70m2 The hollow ultrafiltration membrane is used for filtration, and the reflux rate is controlled at 20%. The permeate is used to extract magnesium hydroxide, and the concentrated solution is used to recover nano-scale calcium carbonate. The sediment at the bottom of the clarifier is discharged periodically.

[0037] Seawater 3m after hollow fiber ultrafiltration membrane treatment 3 / h, after analyzing the concentration of calcium and magnesium ions, according to 2.2:1NaOH / Mg 2+ Molar ratio, add mass concentration 10% sodium hydroxide sodium solution online, enter the magnesium extraction water tank, pump the seawater mixed with magnesium hydroxide into the tubular ultra...

Embodiment 2

[0041] 5m after settling in the pre-sedimentation tank 3 / h seawater and 1mol / L sodium carbonate solution according to 1.2:1Na 2 CO 3 / Ca 2+ The molar ratio is 30min under the condition of a stirring speed of 90r / min. The reaction liquid is pumped into the clarifier and settled for 90min. 80m 2 Hollow ultrafiltration membrane filtration, reflux control is 15%, the permeate is used to extract magnesium hydroxide, and the concentrate is used to recover nano-scale calcium carbonate. The sediment at the bottom of the clarifier is discharged periodically.

[0042] Seawater 5m after hollow fiber ultrafiltration membrane treatment 3 / h, after analyzing the concentration of calcium and magnesium ions, according to 2.2:1NaOH / Mg 2+ Molar ratio, add mass concentration of 10% sodium hydroxide sodium solution online, enter the magnesium extraction water tank, pump the seawater mixed with magnesium hydroxide into the tubular ultrafiltration membrane filtration unit with a diameter of ...

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Abstract

The invention relates to a production method for desalting seawater by de-hardening preprocessing. A chemical method is combined with an ultrafiltration membrane method and a micro filtration membrane method for seawater to extract calcium carbonate and magnesium hydroxide; and the seawater in which calcium and magnesium ions are extracted is desalted to generate freshwater while the produced strong brine is used for comprehensive utilization. In the method of the invention, after the seawater is subject to de-hardening preprocessing of calcium extraction and magnesium extraction, antisludging agent is not added in the desalting process; thus, freshwater recovery rate for a reverse osmosis process can be above 60%, and the freshwater recovery rate for a distillation method can be above 80%; nanoscale calcium carbonate and nanoscale magnesium hydroxide can be by-produced in the preprocessing process; and after desalted, the strong brine can be comprehensively utilized in a high additional value product mode so as to greatly lower investment and operation cost for desalting the seawater. Thus, the production method of the invention is a typical low-carbon, environmentally-friendly, recycling and economical seawater desalting technology.

Description

technical field [0001] The invention relates to a production method for seawater dehardening pretreatment and desalination. Specifically, the seawater uses chemical methods combined with ultra- and microfiltration membrane methods to extract calcium carbonate and magnesium hydroxide, and the seawater after extracting calcium and magnesium ions is desalinated to produce fresh water, and the concentrated brine produced is for comprehensive utilization. After the seawater of the present invention is pretreated by removing calcium and magnesium ions (hardening), the desalination process does not need to add scale inhibitors, not only the recovery rate of fresh water can reach more than 60% by reverse osmosis, and more than 80% by distillation. Zhongke produces nano-scale calcium carbonate and nano-magnesium hydroxide products by-products. The desalinated concentrated brine can be comprehensively utilized in the form of high value-added products, which greatly reduces the investmen...

Claims

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Application Information

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IPC IPC(8): C02F9/04C02F103/08
CPCY02A20/131
Inventor 马敬环
Owner 天津海泽惠科技发展有限公司
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