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Recovery processing method of waste alkaline liquor in ethylene plant

A technology for ethylene waste lye and oxidizing liquid, which is applied in the fields of neutralization, crystallization and recovery of sodium sulfate, and oxidation of waste lye in ethylene plants, and can solve the problems of expensive precipitants, limited utilization of lye, and poor precipitation quality. , to achieve the effect of reducing salt content, avoiding impact and good product quality

Active Publication Date: 2012-05-16
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Na can be obtained after secondary crystallization 2 Industrial products with an S content of 28% to 31%, containing NaOH and Na 2 CO 3 If the mother liquor is recycled to absorb the acid gas of the cracked gas, it will cause Na 2 CO 3 Accumulate in the lye and affect the operation of the device
[0009] Ethylene waste lye is deodorized by wet oxidation, diluted, and then biochemically treated. The high salt content will still have an impact on the biochemical treatment system; and the existing comprehensive utilization technology: either the amount of lye used is limited, or the waste lye is directly There is still no way out for the crystallization mother liquor, or the precipitant is expensive, and the quality of the precipitate obtained is not good

Method used

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  • Recovery processing method of waste alkaline liquor in ethylene plant
  • Recovery processing method of waste alkaline liquor in ethylene plant
  • Recovery processing method of waste alkaline liquor in ethylene plant

Examples

Experimental program
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Effect test

Embodiment 1

[0050] The ethylene spent lye was oxidized in wet air at 160°C (6MPa) for 5 hours without dilution and pH adjustment, and the resulting oxidized solution was neutralized to pH 4.64 with concentrated sulfuric acid. The neutralized solution was crystallized by vacuum evaporation and partially evaporated. The mother liquor is de-biochemical, evaporated, crystallized and dried into Yuanming powder. Part of the evaporated mother liquor is returned to the neutralization unit to reduce the content of sodium carbonate and increase the yield of qualified products.

[0051] The sodium sulfate content of the obtained sodium sulfate is 97.05%, which meets the "GB-T 6009-2003 Industrial Anhydrous Sodium Sulfate" Class II qualified product standard; the amount of the obtained frozen mother liquor is reduced to about 1 / 7 of the neutralization liquid amount, and the COD 1300mg / L, total dissolved solids 34%.

[0052] About step (4): With the progress of evaporation and crystallization, the c...

Embodiment 2

[0054] The ethylene spent lye was oxidized in wet air at 180°C (6MPa) for 5 hours without dilution and pH adjustment, and the obtained oxidized solution was neutralized to pH 4.01 with concentrated sulfuric acid. The neutralized solution was crystallized by vacuum evaporation and partially evaporated. The mother liquor is de-biochemical, evaporated, crystallized and dried into Yuanming powder. Part of the evaporated mother liquor is returned to the neutralization unit to reduce the content of sodium carbonate and increase the yield of qualified products. The sodium sulfate content of the obtained sodium sulfate is 97.12%, which is in line with the "GB-T6009-2003 Industrial Anhydrous Sodium Sulfate" Class II qualified product standard; the amount of the obtained frozen mother liquor is reduced to about 1 / 7 of the neutralization liquor amount, and the COD is 900mg / L , 34% total dissolved solids.

Embodiment 3

[0056] The spent ethylene liquor was subjected to wet oxygen oxidation at 210°C (6MPa) for 2 hours without dilution and pH adjustment, and the resulting oxidation solution was neutralized to pH 4.70 with concentrated sulfuric acid. The neutralization solution was crystallized by vacuum evaporation and partially evaporated. The mother liquor is de-biochemical, evaporated, crystallized and dried into Yuanming powder. Part of the evaporated mother liquor is returned to the neutralization unit to reduce the content of sodium carbonate and increase the yield of qualified products. The sodium sulfate content of the obtained sodium sulfate is 97.13%, which meets the "GB-T6009-2003 Industrial Anhydrous Sodium Sulfate" Class II qualified product standard; the amount of the obtained frozen mother liquor is reduced to about 1 / 7 of the neutralization liquor amount, and the COD is 600mg / L , 34% total dissolved solids.

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Abstract

The invention provides a recovery processing method of waste alkaline liquor in an ethylene plant. The method comprises the following steps: (1) under the condition of wet oxidation, carrying out wet oxidation on waste alkaline liquor with air or oxygen so as to obtain oxidized liquid; (2) neutralizing the oxidized liquid so as to obtain a neutralized liquid; (3) crystallizing the neutralized liquid by adopting an evaporation and crystallization method so as to obtain anhydrous sodium sulfate containing entrained water; (4) returning a part of evaporation mother liquid back to a neutralization unit, and carrying out non-biochemical treatment on another part of evaporation mother liquid; and (5) drying the anhydrous sodium sulfate containing entrained water so as to obtain the anhydrous sodium sulfate product. By using the method, the technical problem that high-content salt still generates impact on a biochemical treatment system after the ethylene waste alkaline liquor is deodorized and diluted through wet oxidation and then is subjected to biochemical treatment can be solved; and the method provided by the invention can be used for the fields of petrifaction, chemical industry, environmental conservation, comprehensive resource utilization, light industry and the like.

Description

technical field [0001] The present invention relates to the technology that reclaims sodium sulfate from ethylene plant waste lye, more specifically relates to the technology of the wet oxidation treatment of waste lye and the technology that separates sodium sulfate from waste liquid, i.e. the oxidation of ethylene plant waste lye, Neutralize and crystallize to recover sodium sulfate. Background technique [0002] The acid gases in the ethylene cracking gas mainly include hydrogen sulfide, carbon dioxide, organic sulfur, etc. To remove the acid gases, the alkaline solution is used to contact and wash the cracking gas in countercurrent, and the waste liquid produced is called ethylene spent alkali. In addition to Na in waste lye 2 S, Na 2 CO 3 , NaOH and a small amount of Na 2 SO 3 、Na 2 S 2 o 3 In addition, it also contains organic sulfur compounds such as mercaptans, so it has an unpleasant odor. [0003] The methods for treating waste ethylene lye include direct ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01D5/16C01D5/18C02F9/14
Inventor 高凤霞程学文张宾莫馗许树华
Owner CHINA PETROLEUM & CHEM CORP
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