High-desalting-rate seawater desalination method and device based on liquefied natural gas cold energy

Active Publication Date: 2015-09-09
CHINA PETROLEUM & CHEM CORP +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] Patent document CN102583848A "Seawater Desalination System and Method Based on Liquid Natural Gas Cold Energy" and Patent Document CN101628740A "Direct Contact Freezing Seawater Desalination Method Utilizing Liquefied Natural Gas Cooling Energy" both use an ice-making device in which the secondary refrigerant directly contacts seawater , although the heat exchange efficiency is high, there are problems that the secondary refrigerant needs to be separated from the ice crystals, the ice crystals are washed, and the desalination rate of the simple freezing method is low
[0007] P

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  • High-desalting-rate seawater desalination method and device based on liquefied natural gas cold energy

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Effect test

Embodiment 1

[0061] Follow the steps below to desalinate seawater:

[0062] (1) Take seawater with an original salt concentration of 3%; fully perform indirect heat exchange between liquefied natural gas and gaseous R410a to obtain gaseous natural gas and liquid R410a, then fully perform indirect heat exchange between the liquid R410a and the seawater to obtain Gaseous R410a, ice and concentrated seawater; after the separation of ice and water, recover the concentrated seawater and store ice for later use;

[0063] The concentration of salt in the ice is 39% of the original salt concentration of seawater;

[0064] (2) Take the ice gained in step (1), and let it stand under normal pressure, so that the melting rate of the ice is 49%, and separate the ice and water while standing; reclaim the liquid, and use the remaining ice for subsequent use;

[0065] (3) Take the remaining ice obtained in step (2), break it into ice crystal particles, centrifuge at 3000 rpm for 4 minutes, and separate t...

Embodiment 2

[0069] Follow the steps below to desalinate seawater:

[0070] (1) Take seawater with an original salt concentration of 3%; fully perform indirect heat exchange between liquefied natural gas and gaseous R410a to obtain gaseous natural gas and liquid R410a, then fully perform indirect heat exchange between the liquid R410a and the seawater to obtain Gaseous R410a, ice and concentrated seawater; after the separation of ice and water, recover the concentrated seawater and store ice for later use;

[0071] The concentration of salt in the ice is 60% of the original salt concentration of seawater;

[0072] (2) Take the ice gained in step (1), and let it stand under normal pressure, so that the melting rate of the ice is 39.5%, and separate the ice and water while standing; reclaim the liquid, and use the remaining ice for subsequent use;

[0073] (3) Take the remaining ice obtained in step (2), break it into ice crystal particles, centrifuge at 5000 rpm for 4 minutes, and separate...

Embodiment 3

[0085] A seawater desalination device with high desalination rate based on the cold energy of liquefied natural gas (such as figure 1 shown), the device includes sequentially connected seawater supply system 9, seawater freezing and gravity centrifugal desalination system, and freshwater system; the device also includes a liquefied natural gas gasification system and a secondary refrigerant phase change circulation system for seawater freezing ;

[0086]The seawater freezing and gravity centrifugal desalination system includes an ice maker 2, an ice-water separator 3, a gravity desalination tank 4, an ice crusher 5, and a filter type centrifugal desalination device 6 connected in sequence;

[0087] The ice maker 2 includes an indirect heat exchanger; one side of the indirect heat exchanger is a secondary refrigerant circulation system, and the other side is a seawater distribution device 11 and a mechanical deicing device;

[0088] The liquefied natural gas gasification syste...

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Abstract

The invention discloses a high-desalting-rate seawater desalination method based on liquefied natural gas cold energy, which comprises the following steps: sufficiently carrying out indirect heat exchange on liquefied natural gas and a gas-state secondary coolant, and sufficiently carrying out indirect heat exchange on the obtained liquid-state secondary coolant and seawater to obtain ice and concentrated seawater; (2) taking the ice obtained in the step (1), standing under atmospheric pressure until the melting rate of ice is 10-50%, recovering the liquid, and taking the residual ice for later use; (3) crushing the residual ice obtained in the step (2) to obtain ice crystal granules, centrifuging, recovering the liquid, and taking the ice crystal granules for later use; and (4) completely melting the ice crystal granules obtained in the step (3). The invention also discloses a seawater desalination plant based on liquefied natural gas cold energy. The method utilizes the cold energy released in the liquefied natural gas gasification process, comprehensively utilizes the freeze desalting, gravity desalting and centrifuging desalting techniques, has the advantages of simple steps, energy saving and environment friendliness, and enhances the seawater desalting rate on the basis of freeze desalting.

Description

technical field [0001] The invention relates to the interdisciplinary field of oil and gas storage and transportation, engineering thermophysics and water treatment technology, and specifically relates to a method and device for desalination of seawater with high desalination rate based on the cold energy of liquefied natural gas. Background technique [0002] LNG (Liquefied Natural Gas) is liquefied natural gas at normal pressure and low temperature (-162°C). Theoretically, 830kJ / kg cold energy will be released. Imported LNG receiving stations are generally built near seaports, and the cold energy released by LNG gasification is usually directly discharged into seawater. With the continuous expansion of the receiving station, a large amount of cold energy will affect the ecological environment of nearby sea areas. If this part of the cold energy can be used for seawater desalination, it will have the following advantages: reduce the impact of LNG gasification process on th...

Claims

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Application Information

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IPC IPC(8): C02F1/22C02F103/08
CPCY02A20/124
Inventor 杨晖李恒松张思健
Owner CHINA PETROLEUM & CHEM CORP
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