Comprehensive treatment method of high-sulphur high-COD (Chemical Oxygen Demand) caustic sludge waste liquid

A technology for comprehensive treatment of alkali slag waste liquid, applied in sulfur compounds, chemical instruments and methods, sulfur preparation/purification, etc., to achieve the effects of low equipment investment and operating costs, good economic benefits, and low investment and operating costs

Active Publication Date: 2013-04-17
CHINA PETROLEUM & CHEM CORP +1
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Problems solved by technology

However, this method will produce alkaline waste liquid during the stripping process of alkali slag

Method used

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  • Comprehensive treatment method of high-sulphur high-COD (Chemical Oxygen Demand) caustic sludge waste liquid

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Embodiment 1

[0032] Catalytic gasoline alkali slag waste liquid in an oil refinery, in which COD is 2.83×10 5 mg / L, the sulfide is 1.68×10 4 mg / L, volatile phenol 7.19×10 4 mg / L. Use the method of the present invention to process, first use N 2 and SO 2 The mixed gas acidifies the alkali slag waste liquid, N 2 / SO 2=30 (molar ratio), until the pH of the alkali slag waste liquid drops to 3-4. The acidified tail gas is condensed to recover organic sulfides and then sent to the sulfur workshop Claus plant for sulfur production. The organic sulfides recovered by condensation are mainly methyl mercaptan and ethanethiol and a small amount of dimethyl disulfide. The water phase after acidification and dephenolization is subjected to 10-stage cross-flow extraction with crude kerosene, the ratio of extractant to waste liquid is 1:3, and the waste extractant is returned to the kerosene hydrotreating unit. The alkali residue waste liquid is acidified to remove more than 99.7% of sulfides, reco...

Embodiment 2

[0036] A refinery liquid hydrocarbon and gasoline mixed alkali residue waste liquid, in which COD is 1.65×10 5 mg / L, sulfide is 1.38×10 4 mg / L, volatile phenol 4.17×10 4 mg / L. Use the method of the present invention to process, first use N 2 and SO 2 The mixed gas acidifies the alkali slag waste liquid, N 2 / SO 2 =50 (molar ratio), until the pH of the alkali slag waste liquid drops to 3-4. After the acidification tail gas is condensed to recover organic sulfides, it is sent to the Claus plant in the sulfur workshop to produce sulfur. The organic sulfides recovered by condensation are mainly methyl mercaptan and ethyl mercaptan. The acidified aqueous phase was left to stand to recover crude phenol. Then use straight-run diesel to perform 10-stage cross-flow extraction on the dephenolized wastewater, the ratio of extractant to waste liquid is 1:5, and the waste extractant is returned to the diesel hydrotreating unit. The alkali residue waste liquid is acidified, the sulf...

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Abstract

The invention relates to a comprehensive treatment method of high-sulphur high-COD (Chemical Oxygen Demand) caustic sludge waste liquid. The comprehensive treatment method comprises the steps of: 1, acidizing high-sulphur high-COD caustic sludge waste liquid by using an N2/SO2 mixed gas, when the pH value of the waste liquid reaches 2-6, stopping acidizing; 2, sending tail gas discharged in the acidizing process in the step 1 to a sulphur production device for preparing sulphur; 3, settling the waste liquid generated in acidizing treatment in the step 1and recovering an oil phase; 4, further reducing the COD of the waste liquid by adopting an extraction method when the COD of the waste liquid after the oil phase is separated in the step 3 is always high; and 5, regenerating the waste liquid extracted in the step 4 by using lime. The comprehensive treatment method is low in investment, is mild in operation conditions, is capable of recycling the caustic sludge waste liquid, avoiding the impact of the high-concentration wastewater on a wastewater treatment field, is also capable of recovering sulfide and crude carbolic acid from the caustic sludge waste liquid, and has a certain economic benefit.

Description

technical field [0001] The invention relates to a treatment method for alkali slag waste liquid, in particular to a comprehensive treatment method for liquid hydrocarbons and alkali slag waste liquid produced in the alkali washing and refining process of gasoline. Background technique [0002] In the process of alkaline cleaning and refining of oil products in refineries, alkaline waste liquid containing high concentrations of pollutants is produced, and the emissions of COD, sulfides and phenols account for more than 40% to 50% of the emissions of such pollutants in refineries. It is mainly composed of atmospheric diesel soda residue, catalytic gasoline soda residue, liquid hydrocarbon soda residue, etc. If the alkali residue waste liquid is discharged directly, it will seriously pollute the environment. If it is sent to the sewage treatment plant, it will seriously affect the normal operation of the sewage treatment plant, making it difficult to discharge the sewage up to ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C10G19/08C01B17/06C01B17/50C07C37/68
Inventor 赵磊刘忠生王有华王新周旗
Owner CHINA PETROLEUM & CHEM CORP
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