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Treatment method of spent lye in propylene production

A treatment method and technology for waste lye, applied in natural water treatment, chemical instruments and methods, multi-stage water/sewage treatment, etc., can solve the problems of high energy consumption and high COD content, and achieve the effect of zero discharge

Active Publication Date: 2014-05-07
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the evaporation and crystallization step consumes a lot of energy, and the COD content in the evaporation mother liquor is high, so it needs to be further treated by biochemical method

Method used

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  • Treatment method of spent lye in propylene production

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Effect test

Embodiment 1

[0020] One piece of waste lye in the production process of propylene, its COD is 117350mg / L, and sodium sulfide is 6.83wt% (S 2- : 29421mg / L), sodium hydrosulfide is 4.85wt% (S 2- : 29108mg / L), oily 280mg / L, pH 13.4.

[0021] The process of the present invention is carried out under the following conditions.

[0022] Air flotation degreasing: Air is introduced into the waste lye to generate air bubbles in the waste lye, and a small amount of light oil entrained in the waste lye sticks to the air bubbles, and is removed by floating on the water surface with the gas. The oil content in the waste lye drops to 18mg / L.

[0023] Removal of sodium hydrosulfide: add 55wt% sodium hydroxide solution to the waste lye, if there is already a sodium hydroxide solution obtained after the treatment of the present invention, use the sodium hydroxide solution of the present invention. The dosing amount is 170L per 1m3 of waste lye, so that all the sodium hydrosulfide in the waste lye is conv...

Embodiment 2

[0027] One piece of spent lye in the propylene production process, its COD is 82400mg / L, and sodium sulfide is 4.8wt% (S 2- : 20697mg / L), sodium hydrosulfide is 3.4wt% (S 2- : 20380mg / L), oily 245mg / L, pH 13.8.

[0028] The process of the present invention is carried out under the following conditions.

[0029] Air flotation degreasing: Air is introduced into the waste lye to generate air bubbles in the waste lye, and a small amount of light oil entrained in the waste lye sticks to the air bubbles, and is removed by floating on the water surface with the gas. The oil content in the waste lye drops to 13mg / L.

[0030] Removing sodium hydrosulfide: according to the concentration of sodium hydrosulfide in the waste caustic, add 40wt% sodium hydroxide solution to the waste caustic, preferably adopt the sodium hydroxide solution obtained after the treatment of the present invention. The dosing amount is 255L per 1m3 of spent lye, so that all the sodium hydrosulfide in the spent ...

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Abstract

The invention discloses a treatment method of spent lye in propylene production. The method includes the following steps: (1) air flotation oil removal to remove trace light oil entrained in the spent lye; (2) removal of sodium hydrosulfide by adding 25wt%-60wt% sodium hydroxide solution into the spent lye to completely convert sodium hydrosulfide in the spent lye into sodium sulfide; (3) wet-type oxidation treatment by carrying out wet-type oxidation treatment on the spent lye with sodium hydrosulfide removed; and (4) alkali concentration adjustment by adding solid sodium hydroxide into the spent lye subjected to wet-type oxidation treatment, controlling the temperature at 40-120 DEG C, recovering precipitated sodium sulfate, and reusing the generated high-concentration sodium hydroxide solution to the step (2) and / or an upstream alkaline tower. The method provided by the invention can effectively remove COD and sulfides in the spent lye, recover sodium sulfate and reuse the sodium hydroxide solution after spent lye treatment, so as to achieve zero discharge of spent lye in the propylene production.

Description

technical field [0001] The invention belongs to the field of waste water treatment, and relates to a treatment method for waste lye in chemical plants, in particular to a treatment method for waste lye produced in propane dehydrogenation to propylene by utilizing the Oleflex process of UOP Company. Background technique [0002] Propylene is an important chemical raw material, its consumption is second only to ethylene, in addition to being used in the production of polypropylene, it is also the main raw material of various chemical products. In recent years, with the rapid growth of the demand for derivatives such as polypropylene, the demand for propylene is also increasing year by year. Compared with the traditional propylene production process, the propane catalytic dehydrogenation to propylene process has the advantages of high propylene yield and less equipment investment, and can effectively use liquefied petroleum gas resources to convert it into useful olefins. Propa...

Claims

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Application Information

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IPC IPC(8): C02F9/04C01B17/22C01D5/00C02F103/36
Inventor 周彤邓德刚秦丽姣
Owner CHINA PETROLEUM & CHEM CORP
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