Method for carrying out injection-reducing standard discharging treatment on high-sulfur wastewater of oil-gas field

A treatment method and high-sulfur technology, which is applied in mining wastewater treatment, multi-stage water treatment, water/sewage treatment, etc., can solve the problems of reducing the amount of wastewater reinjection and excessive oil content, and achieve the reduction of wastewater reinjection, Solve the effect of huge equipment

Active Publication Date: 2017-10-24

CHINA PETROLEUM & CHEM CORP +1

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AI-Extracted Technical Summary

Problems solved by technology

[0005] In view of the defects existing in the prior art, the purpose of the present invention is to provide a treatment method for the treatment of high-sulfur wastewater from oil and gas fields, which uses negative pressure desulfurization + chemical reaction desulfurization + flocculation sedimentation + ceramic membrane filtration + high-pressure reverse osmosis + Ozone catalytic oxidation technology, oil and gas field high sulf...

Method used

2, negative pressure desulfurization unit of the present invention carries out waste water circulation by adopting circulation pump, accelerates the hydrogen sulfide in high sulfur waste water to overflow, shortens waste water desulfurization time, has improved desulfurization effect;

3, negative pressure desulfurization unit of the present invention is by matching between negative pressure and waste water pH, while reducing waste water desulfurization cost, maximum efficiency has removed the hydrogen sulfide in waste water;

4, the present invention is by the high-efficiency coupling of negative pressure desulfurization technology and chemical reaction desulfurization technology, on the basis of adopting negative pressure desulfurization technology to remove most of the sulfide ions in waste water, adopting chemical reaction desulfurization technology depth to remove residual in waste water again A small amount of sulfur ions in the wastewater minimizes the content of sulfur ions in the wastewater, reduces the consumption of chemicals and the amount of waste residue, and greatly reduces the operating cost;

5, the present invention solves the filtration problem of the oil-gas field waste water with high oil content by adopting porous ceramic membrane to filter, overcomes the limitation of organic membrane treatment oil-gas fiel...

Abstract

The invention relates to a method for carrying out injection-reducing standard discharging treatment on high-sulfur wastewater of an oil-gas field. According to the method disclosed by the invention, technologies of negative-pressure desulfurization, chemical reaction desulfurization, flocculating settling, ceramic membrane filtering, high-pressure reverse osmosis and ozone catalytic oxidation are adopted, so that the purpose of deeply removing sulfide, suspended matters, organic matters, chloride and oil in the high-sulfur wastewater of oil-gas field can be realized, the sulfur content, the suspended matter content and the oil content in high-pressure reverse osmotic concentrated water can meet the reinjection water standard of the oil-gas field, and effluent after ozone catalytic oxidation is subjected to standard discharging.

Application Domain

Waste water treatment from quariesWater contaminants +5

Technology Topic

ChemistrySulfur content +12

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Examples

Experimental program(5)

Example Embodiment

[0083] Example 1

[0084] The main water quality characteristics of high-sulfur wastewater in oil and gas fields are: sulfide 2000mg/L, total dissolved solids 10000mg/L, suspended solids content 500mg/L, oil content 100mg/L, total hardness (CaCO 3 Count) 1000mg/L, Na + 5000mg/L, Cl - 6000mg/L, SO 4 2- 1000mg/L, COD 800mg/L.

[0085] The processing steps are as follows:

[0086] In the first step, sulfuric acid is used to adjust the pH of the high-sulfur wastewater to 6 for the first time, and then it enters the negative pressure desulfurization unit for desulfurization. The operating conditions for negative pressure desulfurization are: inlet water temperature 35°C, operating negative pressure -0.04MPa, The wastewater retention time is 20 minutes, and the reflux ratio of the circulating pump is 5:1;

[0087] In the second step, the negative pressure desulfurization effluent adopts sulfuric acid to adjust the pH of the wastewater for the second time to 6.5, and then enters the chemical reaction desulfurization unit for chemical reaction desulfurization, the chemical reactant is ferrous sulfate, and the dosage is 30mg/L;

[0088] In the third step, the effluent of chemical reaction desulfurization uses sodium hydroxide to adjust the pH of the wastewater to 8 for the third time, and then enters the flocculation and sedimentation unit for flocculation and sedimentation. The flocculant is polyaluminum chloride, and the coagulant aid is anionic polyacrylamide with molecular weight. 5 million, the amount of flocculant is 50mg/L, the amount of coagulant aid is 2mg/L, and the flocculation settling time is 10min;

[0089] In the fourth step, the effluent from flocculation and sedimentation enters the ceramic membrane filtration unit for micro-crossflow filtration. The pore size of the ceramic membrane is 0.15μm, the membrane surface velocity is 0.6m/s, the inlet water pH is 6, and the inlet water temperature is 15°C;

[0090] In the fifth step, the effluent filtered by the ceramic membrane enters the high-pressure reverse osmosis unit for separation and concentration to obtain reverse osmosis product water and reverse osmosis concentrated water. The operating conditions are: operating pressure 9MPa, inlet water pH 6, and inlet water temperature 15°C;

[0091] Under these conditions, the recovery rate of high-pressure reverse osmosis is over 80%;

[0092] In the sixth step, the high-pressure reverse osmosis product water enters the ozone catalytic oxidation unit for ozone catalytic oxidation treatment. The operating conditions are: inlet water pH 6, inlet water temperature 15°C, residence time 1.5h, and ozone concentration 10mg/L.

[0093] After the above steps, the high-sulfur wastewater of oil and gas fields, the sulfur content of high-pressure reverse osmosis concentrated water <0.5mg/L, oil content <5mg/L, suspended solids content <1mg/L, meet the oil and gas field reinjection water standard, ozone catalytic oxidation effluent COD <100mg/L, Cl - <300mg/L, meeting emission standards.

[0094] The hydrogen sulfide generated after the negative pressure desulfurization is collected for incineration treatment, and the flocculation and sedimentation residues are solidified and transported outside for centralized treatment.

Example Embodiment

[0095] Example 2

[0096] The main water quality characteristics of high-sulfur wastewater in oil and gas fields are: sulfide 5000mg/L, total dissolved solids 20000mg/L, suspended solids content 1500mg/L, oil content 150mg/L, total hardness (CaCO 3 Count) 1100mg/L, Na + 8000mg/L, Cl - 9000mg/L, SO 4 2- 1300mg/L, COD 1000mg/L.

[0097] The processing steps are as follows:

[0098] In the first step, the high-sulfur wastewater uses hydrochloric acid to adjust the pH of the wastewater to 4.8 for the first time, and then enters the negative pressure desulfurization unit for desulfurization. The operating conditions of the negative pressure desulfurization are: inlet water temperature 40°C, operating negative pressure -0.05MPa, The wastewater retention time is 27 minutes, and the reflux ratio of the circulating pump is 4:1;

[0099] In the second step, the pH of the negative pressure desulfurization effluent is 5.5, so there is no need to adjust the pH again, and it directly enters the chemical reaction desulfurization unit for chemical reaction desulfurization. The chemical reactant is ferrous sulfate and the dosage is 40mg/L;

[0100] In the third step, the effluent of chemical reaction desulfurization uses sodium hydroxide to adjust the pH of the wastewater to 8 for the third time, and then enters the flocculation and sedimentation unit for flocculation and sedimentation. The flocculant is polyaluminum chloride, and the coagulant aid is anionic polyacrylamide with molecular weight. 6 million, the amount of flocculant is 70mg/L, the amount of coagulant is 2mg/L, and the flocculation settling time is 10min;

[0101] In the fourth step, the effluent from flocculation and sedimentation enters the ceramic membrane filtration unit for micro-crossflow filtration. The pore size of the ceramic membrane is 0.1μm, the membrane surface velocity is 0.8m/s, the inlet water pH is 7, and the inlet water temperature is 25°C;

[0102] In the fifth step, the effluent filtered by the ceramic membrane enters the high-pressure reverse osmosis unit for separation and concentration to obtain reverse osmosis product water and reverse osmosis concentrated water. The operating conditions are: operating pressure 10MPa, inlet water pH 7, and inlet water temperature 25°C;

[0103] Under these conditions, the recovery rate of high-pressure reverse osmosis is more than 70%;

[0104] In the sixth step, the high-pressure reverse osmosis product water enters the ozone catalytic oxidation unit for ozone catalytic oxidation treatment. The operating conditions are: inlet water pH 7, inlet water temperature 25°C, residence time 1h, and ozone concentration 30mg/L.

[0105] After the above steps, the high-sulfur wastewater of oil and gas fields, the sulfur content of high-pressure reverse osmosis concentrated water <0.5mg/L, oil content <5mg/L, suspended solids content <1mg/L, meet the oil and gas field reinjection water standard, ozone catalytic oxidation effluent COD <100mg/L, Cl - <300mg/L, meeting emission standards.

[0106] The hydrogen sulfide generated after the negative pressure desulfurization is collected for incineration treatment, and the flocculation and sedimentation residues are solidified and transported outside for centralized treatment.

Example Embodiment

[0107] Example 3

[0108] The main water quality characteristics of high-sulfur wastewater in oil and gas fields are: sulfide 10000mg/L, total dissolved solids 30000mg/L, suspended solids content 3000mg/L, oil content 200mg/L, total hardness (CaCO 3 Count) 1200mg/L, Na + 10000mg/L, Cl - 11000mg/L, SO 4 2- 1400mg/L, COD 1200mg/L.

[0109] The processing steps are as follows:

[0110] In the first step, the high-sulfur wastewater is adjusted to pH 5 with nitric acid for the first time, and then enters the negative pressure desulfurization unit for desulfurization. The operating conditions for negative pressure desulfurization are: inlet water temperature 45°C, operating negative pressure -0.06MPa, The wastewater retention time is 30min, and the reflux ratio of the circulating pump is 3:1;

[0111] In the second step, the pH of the negative pressure desulfurization effluent is 5.7, so there is no need to adjust the pH again, and it directly enters the chemical reaction desulfurization unit for chemical reaction desulfurization. The chemical reactant is ferrous sulfate, and the dosage is 60mg/L;

[0112] In the third step, the effluent from chemical reaction desulfurization uses sodium hydroxide to adjust the pH of the wastewater for the third time to 8.5, and then enters the flocculation and sedimentation unit for flocculation and sedimentation. The flocculant is polyaluminum chloride, the coagulant aid is anionic polyacrylamide, and the molecular weight is 7 million, the amount of flocculant is 100mg/L, the amount of coagulant aid is 3mg/L, and the flocculation settling time is 20min;

[0113] In the fourth step, the effluent from flocculation and sedimentation enters the ceramic membrane filtration unit for micro-crossflow filtration. The ceramic membrane has a pore size of 0.1 μm, a membrane surface velocity of 1.0 m/s, an inlet water pH of 7, and an inlet temperature of 35°C;

[0114] In the fifth step, the effluent filtered by the ceramic membrane enters the high-pressure reverse osmosis unit for separation and concentration to obtain reverse osmosis product water and reverse osmosis concentrated water. The operating conditions are: operating pressure of 11MPa, inlet water pH 7, and inlet water temperature 35°C;

[0115] Under these conditions, the recovery rate of high-pressure reverse osmosis is over 60%;

[0116] In the sixth step, the high-pressure reverse osmosis product water enters the ozone catalytic oxidation unit for ozone catalytic oxidation treatment. The operating conditions are: inlet water pH 7, inlet water temperature 35°C, residence time 2h, and ozone concentration 40mg/L.

[0117] After the above steps, the high-sulfur wastewater of oil and gas fields, the sulfur content of high-pressure reverse osmosis concentrated water <0.5mg/L, oil content <5mg/L, suspended solids content <1mg/L, meet the oil and gas field reinjection water standard, ozone catalytic oxidation effluent COD <100mg/L, Cl - <300mg/L, meeting emission standards.

[0118] The hydrogen sulfide generated after the negative pressure desulfurization is collected for incineration treatment, and the flocculation and sedimentation residues are solidified and transported outside for centralized treatment.

PUM

Property	Measurement	Unit
Hardness	1200.0
Hardness	1600.0

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