CN114538725B - Super-critical CO of oil sludge and oil-containing soil 2 Extraction recovery comprehensive treatment process - Google Patents

Super-critical CO of oil sludge and oil-containing soil 2 Extraction recovery comprehensive treatment process Download PDF

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CN114538725B
CN114538725B CN202210223804.2A CN202210223804A CN114538725B CN 114538725 B CN114538725 B CN 114538725B CN 202210223804 A CN202210223804 A CN 202210223804A CN 114538725 B CN114538725 B CN 114538725B
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reaction kettle
extraction reaction
oil
sent
extraction
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CN114538725A (en
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刘宗宽
李进
顾兆林
梁馨心
张冠
胡文睿
杨瑶林
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Xian Jiaotong University
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Xian Jiaotong University
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C02F11/15—Treatment of sludge; Devices therefor by de-watering, drying or thickening by treatment with electric, magnetic or electromagnetic fields; by treatment with ultrasonic waves
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
    • C10G1/002—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal in combination with oil conversion- or refining processes
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
    • C10G1/04—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal by extraction
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G33/00—Dewatering or demulsification of hydrocarbon oils
    • C10G33/04—Dewatering or demulsification of hydrocarbon oils with chemical means
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F2001/007—Processes including a sedimentation step
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids

Abstract

Super-critical CO of oil sludge and oil-containing soil 2 Extraction recovery comprehensive treatment process for liquid CO 2 Becomes supercritical CO through the compressor and the preheater in sequence 2 The fluid is sent into a first extraction reaction kettle and a second extraction reaction kettle to be in countercurrent contact with the oil sludge or the oil-containing soil which is subjected to dehydration and desalination treatment; the first extraction reaction kettle and the second extraction reaction kettle are connected in series when treating the oil sludge, and are connected in parallel when treating the oil-containing soil; the extract is sequentially sent into a first separator and a second separator for water-oil-gas three-phase separation, the separated oil is sent into a storage tank for separating wastewater and CO containing a small amount of light petroleum hydrocarbon 2 The gas is sent into a high-grade oxidation pond, the raffinate is sent into the high-grade oxidation pond or is used as clean soil backfill, and the wastewater after the dehydration and desalination treatment of the oil sludge is firstly subjected to the removal of inorganic salt by an electrodialyzer and then is sent into the high-grade oxidation pond; adding sodium persulfate and biochar into the advanced oxidation pond, and sending the rest solid-liquid mixture into a vertical flow sedimentation pond for solid-liquid separation; the invention realizes the safe disposal and comprehensive utilization of the oil sludge and the oil-containing soil.

Description

Super-critical CO of oil sludge and oil-containing soil 2 Extraction recovery comprehensive treatment process
Technical Field
The invention relates to oil sludgeThe technical field of comprehensive treatment of oil-containing soil, in particular to an oil sludge and oil-containing soil supercritical CO 2 Extraction and recovery comprehensive treatment process.
Background
Petroleum is used as an important strategic energy source, and oil-containing sludge (oil sludge for short) is produced due to the fact that soil and other impurities are mixed in crude oil in the processes of petroleum exploration, exploitation, storage and transportation, refining and processing. Long-term accumulation of the sludge can pollute the atmosphere, soil and water sources; in addition, improper treatment of oil sludge and leakage of crude oil can cause petroleum to enter soil, thereby destroying soil structure, affecting permeability of soil, reducing soil quality and producing oil-containing soil. The oil sludge is solid dangerous waste rich in petroleum hydrocarbon and mainly consists of oil (10-70%), sediment and water (40-90%). The oil sludge and the oil-containing soil contain a large amount of petroleum resources, and if the petroleum resources are not recycled, the waste of the resources is caused.
Besides oil, sediment and water, the oil sludge and the oil-containing soil also contain a large amount of metal ions (such as iron, copper, nickel and the like) and toxic and harmful compounds with malodorous smell such as benzene series, phenols, anthracene, pyrene and the like, so that the solid wastes, waste water and toxic and harmful compounds contained in waste gas generated in the recovery process need to be removed while recycling the oil sludge and the oil-containing soil. In addition, the oily sludge is generally composed of oil-in-water (O/W), water-in-oil (W/O) and suspended solids, is a stable suspension emulsion system, and is characterized in that the oily sludge particles are flocculent, and three phases of water, oil and sediment are fully emulsified and have higher viscosity, so that suspended matters in the oily sludge are difficult to settle. Supercritical fluid extraction is a technique for separating a component (extract) from a mixture by using a supercritical fluid as an extractant, and is often used for extraction separation of oil components from oil sludge. CO 2 As a nontoxic solvent, the supercritical fluid has the characteristics of no smell, nonflammability, low cost, easy availability, recycling and the like, and becomes the most commonly used supercritical fluid.
Both Chinese patent (bulletin No. CN 21189182U) and (bulletin No. CN 102453494B) propose supercritical CO 2 Process and method for extracting sludge, but notConsidering the influence of the high viscosity of the oil sludge on the extraction device, and the problems of comprehensive treatment and resource utilization of the oil sludge and the oil-containing soil.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to provide the supercritical CO of the oil sludge and the oil-containing soil 2 The extraction and recovery comprehensive treatment process is used for recovering oil in the oil sludge and the oil-containing soil, so that the safe disposal and comprehensive utilization of the oil sludge and the oil-containing soil are realized.
In order to achieve the above purpose, the invention adopts the following technical scheme:
super-critical CO of oil sludge and oil-containing soil 2 The extraction and recovery comprehensive treatment process comprises the following steps:
first step, CO 2 Liquid CO in tank 1 2 The high-pressure pump 2 is used for increasing the pressure to 10-20MPa and then is mixed with entrainer methanol conveyed by a metering pump 4 in a mixer 5, then respectively feeding the hot water into the tube passes of the first preheater 6A and the second preheater 6B, and sequentially feeding the hot water into the shell passes of the first preheater 6A and the second preheater 6B and liquid CO 2 The fluid is in countercurrent contact to preheat the fluid to 45-55 ℃, and then the fluid is respectively sent into the first supercritical CO at the bottoms of the first extraction reaction kettle 9 and the second extraction reaction kettle 11 2 Injection pipe 94 and second supercritical CO 2 In the ejector tube 114; the heat preservation jacket after preheating the first preheater 6A and the second preheater 6B is respectively sent into the first heat preservation jacket 92 of the first extraction reaction kettle 9 and the second heat preservation jacket 112 of the second extraction reaction kettle 11; the heat preservation water outlet water of the first extraction reaction kettle 9 is sent into a third heat preservation jacket 72 of the pretreatment tank 7, and the heat preservation water outlet water of the second extraction reaction kettle 11 is sent into a fourth heat preservation jacket 131 of the first separator 13;
secondly, adding the oil sludge into a pretreatment tank 7, adding a demulsifier, dehydrating and desalting under the synergistic effect of ultrasonic waves, conveying the dehydrated and desalted oil sludge to the upper part of a first extraction reaction kettle 9 through a first spiral feeding device 8, and conveying the dehydrated and desalted oil sludge into the first extraction reaction kettle 9 through a first primary lock hopper 91 to carry out supercritical CO 2 Countercurrent contact of the fluid; after extraction by the first extraction reaction kettle 9The extract of (2) is fed into a first central tube 132 of a first separator 13 from the upper discharge of a first extraction reaction kettle 9 by regulating the pressure through a first reducing valve 12, the raffinate is fed into the upper part of a second extraction reaction kettle 11 from the bottom discharge of the first extraction reaction kettle 9 by a second spiral feeding device 10, and is fed into the second extraction reaction kettle 11 and supercritical CO through a second primary lock bucket 111 2 Countercurrent contact of the fluid; the extract extracted by the second extraction reaction kettle 11 is sent into a first central pipe 132 of a first separator 13 from the upper discharge of the second extraction reaction kettle 11 through a first pressure reducing valve 12, and the raffinate flows into a higher oxidation pond 20 from the bottom discharge of the second extraction reaction kettle 11 to further remove petroleum and other aromatic compounds (benzene series, phenols, anthracene, pyrene and the like) and heavy metals remained in the raffinate; the wastewater removed by the pretreatment tank 7 is sent into an electrodialysis device 19 through a first discharge pump 18, concentrated brine produced by the electrodialysis device 19 is subjected to subsequent concentration and crystallization treatment, and the rest water is sent into a high-grade oxidation tank 20 for further treatment;
for the oil-containing soil, the oil-containing soil is respectively sent to the upper parts of a first extraction reaction kettle 9 and a second extraction reaction kettle 11 through a first spiral feeding device 8 and a second spiral feeding device 10, and then is respectively sent into the first extraction reaction kettle 9 and the second extraction reaction kettle 11 through a first primary lock bucket 91 and a second primary lock bucket 111 to be communicated with supercritical CO 2 Countercurrent contact of the fluid; the extracted extracts are respectively sent into a first central pipe 132 of a first separator 13 from the upper discharge materials of a first extraction reaction kettle 9 and a second extraction reaction kettle 11 through a first pressure reducing valve 12, and the raffinate is respectively directly used as clean soil backfill from the bottom discharge materials of the first extraction reaction kettle 9 and the second extraction reaction kettle 11;
third, the raffinate is subjected to water-oil-gas three-phase separation in a first separator 13, and CO containing part of light component oil 2 The gas is discharged from the top of the first separator 13, the pressure of the gas is regulated by the second pressure reducing valve 14 and is sent to the middle part of the second separator 15, the oil phase is sent to the first storage tank 16 from the upper middle part of the first separator 13, and the water phase flows into the advanced oxidation tank 20 from the bottom of the first separator 13; CO containing a portion of the light component oil 2 The gas is further in a second separator 15Separated light component oil flows into a second storage tank 17 from the bottom of the second separator 15, and CO containing a small amount of oil 2 CO gas fed into the bottom of the advanced oxidation unit 20 2 In the ejector coil 201; then adding biochar and sodium persulfate into the advanced oxidation pond 20, and removing CO of petroleum hydrocarbon by oxidation reaction 2 The gas is discharged from the top of the advanced oxidation tank 20 and passes through a filter valve 21 and supplemented CO 2 The gas is sent from the compressor 22 to the cooler 23 for cooling and then sent to the CO 2 The solid-liquid mixture is discharged from the lower part of the advanced oxidation tank 20 and is sent into a second central pipe 251 of the vertical-flow sedimentation tank 25 through a second discharge pump 24, the supernatant after sedimentation is discharged from the upper part of the vertical-flow sedimentation tank 25 for recycling, and the solid residues are discharged from the bottom of the vertical-flow sedimentation tank 25 as clean soil backfill.
The temperature of the water after preheating the first preheater 6A and the second preheater 6B is 80-85 ℃.
An ultrasonic vibration plate 71 is arranged in the pretreatment tank 7, the operation temperature is 50 ℃, and the stirring intensity is 0.9-1.2kW/m 3 The liquid retention time was 1.5h.
The temperature of the heat preservation water outlet of the first extraction reaction kettle 9 and the second extraction reaction kettle 11 is 65-70 ℃.
The sieve plates in the first extraction reaction kettle 9 are obliquely arranged, the inclination angle is 25 degrees, the operating temperature is 45-55 ℃, the operating pressure is 10-20MPa, and the extraction time is 8-10h; the sieve plates in the second extraction reaction kettle 11 are obliquely arranged, the inclination angle is 25 degrees, the operating temperature is 45-55 ℃, the operating pressure is 10-20MPa, and the extraction time is 8-10h.
The first supercritical CO 2 Injection pipe 94 and second supercritical CO 2 The injection pipes 114 are respectively arranged at the lower parts of the first extraction reaction kettle 9 and the second extraction reaction kettle 11 in the form of coils, and the first supercritical CO 2 Injection pipe 94 and second supercritical CO 2 Micropores with a diameter of 5mm and an aperture ratio of 30% are formed below the ejector tube 114.
The first separator 13 is internally provided with a central tube 132, the operating temperature is 60 ℃, and the operating pressure is 2.5-3.0MPa; the operating pressure of the second separator 15 is 4.5-5.0MPa.
The bottom of the advanced oxidation tank 20 is provided with CO 2 Injection coil 201, CO 2 Micropores are formed below the spraying coil 201, the diameter of the micropores is 3mm, the aperture ratio is 35%, and the reaction time is 5-7h.
The mass ratio of the biochar to the sodium persulfate is 1:6.
The CO cooled by the cooler 23 2 The gas temperature is 0-4 ℃.
Compared with the prior art, the invention has the beneficial effects that:
1. the demulsifier and the ultrasonic wave are added into the pretreatment tank 7 for auxiliary combination, so that the structure of the oily sludge can be destroyed by utilizing the mechanical vibration and cavitation of the ultrasonic wave, the viscosity of petroleum hydrocarbon in the oily sludge can be reduced, the separation of the petroleum hydrocarbon can be accelerated under the action of the demulsifier, the purpose of dehydration and desalination can be achieved, and the subsequent supercritical extraction and separation efficiency can be improved.
2. Both the pretreatment tank 7 and the first separator 13 use heat-insulating water to control the operation temperature, which is beneficial to reducing the viscosity of petroleum hydrocarbon and increasing the fluidity; furthermore, separation can be facilitated by adjusting the operating temperature of the first separator 13 to change the extract to a low pressure gas.
3. Extracting and separating CO 2 The gas is introduced into the bottom of the advanced oxidation tank 20, so that the stirring effect can be achieved, the stirring energy consumption can be reduced, and CO can be removed 2 The small amount of light petroleum hydrocarbon compounds carried in the gas is obtained by using CO 2 Recycling gas; in addition, CO generated by oxidation of organic matters in advanced oxidation pond 2 Also CO 2 A supplement to the gas.
4. The advanced oxidation method of activated sodium persulfate by using biochar can not only oxidize and remove raffinate, wastewater and CO 2 The petroleum hydrocarbon and aromatic compounds in the gas can also realize the stabilization/immobilization of heavy metals in the gas; in addition, the biochar is a good soil conditioner, and is beneficial to backfilling of the treated clean soil.
Drawings
FIG. 1 is a schematic flow chart of the process of the present invention.
Detailed Description
The invention is further described below with reference to the drawings and examples.
Referring to FIG. 1, an oil sludge and oil-bearing soil supercritical CO 2 The extraction and recovery comprehensive treatment process comprises the following steps:
first step, CO 2 Liquid CO in tank 1 2 At 55m by means of a high-pressure pump 2 3 After the pressure is increased to 10-20MPa, the mixture is mixed with entrainer methanol in a methanol storage tank 3 which is conveyed by a metering pump 4 at 5kg/h in a mixer 5, and then the mixture is respectively sent into tube passes of a first preheater 6A and a second preheater 6B, and hot water at the temperature of 95-100 ℃ is sequentially added at the pressure of 4.0m 3 /h is fed to the shell side of the first preheater 6A and the second preheater 6B with liquid CO 2 The fluid is in countercurrent contact to preheat the fluid to 45-55 ℃, and then the fluid is respectively sent into the first supercritical CO at the bottoms of the first extraction reaction kettle 9 and the second extraction reaction kettle 11 2 Injection pipe 94 and second supercritical CO 2 In the ejector tube 114; the heat preservation water at 80-85 ℃ after preheating the first preheater 6A and the second preheater 6B is respectively sent into a first heat preservation jacket 92 of the first extraction reaction kettle 9 and a second heat preservation jacket 112 of the second extraction reaction kettle 11, and the first extraction reaction kettle 9 and the second extraction reaction kettle 11 are heated; the heat preservation water outlet water with the temperature of 65-70 ℃ in the first extraction reaction kettle 9 is sent into a third heat preservation jacket 72 of the pretreatment tank 7, and the heat preservation water outlet water with the temperature of 65-70 ℃ in the second extraction reaction kettle 11 is sent into a fourth heat preservation jacket 131 of the first separator 13;
secondly, for the oil sludge, as the water content of the oil sludge is higher and the oil sludge is a stable suspension emulsion system, the oil sludge with the oil content of 30 percent and the water content of 50 percent is firstly added into a pretreatment tank 7 at 100kg/h, then a demulsifier is added at 1.5kg/h, the aim of dehydration and desalination is achieved under the synergistic effect of ultrasonic waves, the desalination rate is more than 90 percent, the dehydration rate is more than 80 percent, the oil sludge after dehydration and desalination is sent to the upper part of a first extraction reaction kettle 9 through a first spiral feeding device 8 at 60kg/h, and is sent into the first extraction reaction kettle 9 through a first one-stage lock hopper 91 and supercritical CO 2 Countercurrent contact of the fluid; after extraction by the first extraction reaction kettle 9Is discharged from the upper part of the first extraction reaction kettle 9 by 60m 3 The pressure is regulated by the first pressure reducing valve 12 and is sent into the first central pipe 132 of the first separator 13, and the extraction rate reaches more than 70 percent; the raffinate is discharged from the bottom of the first extraction reaction kettle 9 and is sent to the upper part of a second extraction reaction kettle 11 through a second spiral feeding device 10 at a rate of 39kg/h, and is sent into the second extraction reaction kettle 11 and supercritical CO through a second primary lock bucket 111 2 Countercurrent contact of the fluid; the extract extracted by the second extraction reaction kettle 11 is discharged from the upper part of the second extraction reaction kettle 11 by 58m 3 The/h is sent into the central tube 132 of the first separator 13 through the first pressure reducing valve 12, and the extraction rate reaches more than 99 percent; the raffinate flows into the advanced oxidation pond 20 from the bottom discharge of the second extraction reaction kettle 11 at a rate of 30kg/h to further remove the residual petroleum and other aromatic compounds (benzene series, phenols, anthracene, pyrene and the like), heavy metals and other toxic and harmful substances in the raffinate; the wastewater removed by the pretreatment tank 7 is sent into an electrodialysis device 19 at 40kg/h through a first discharge pump 18, concentrated brine produced by the electrodialysis device 19 is subjected to subsequent concentration crystallization treatment, and the rest water is sent into a high-grade oxidation tank 20 for further treatment;
for the oil-containing soil, as the water content of the oil-containing soil is lower and the oil content is also low (generally 3-10%), the oil-containing soil can be completely extracted by only one-stage extraction without pretreatment, so that the oil-containing soil with the oil content of 5% is respectively delivered to the upper parts of a first extraction reaction kettle 9 and a second extraction reaction kettle 11 through a first spiral feeding device 8 and a second spiral feeding device 10 at 300kg/h, and then respectively delivered into the first extraction reaction kettle 9 and the second extraction reaction kettle 11 through a first-stage lock hopper 91 and a second-stage lock hopper 111 and supercritical CO 2 The fluid is in countercurrent contact, and the extracts extracted by the first extraction reaction kettle 9 and the second extraction reaction kettle 11 are discharged from the upper parts of the first extraction reaction kettle 9 and the second extraction reaction kettle 11 respectively at a speed of 60m 3 The/h is sent into the central tube 132 of the first separator 13 through the first pressure reducing valve 12, and the extraction rate reaches more than 99.5 percent; the raffinate is discharged from the bottoms of the first extraction reaction kettle 9 and the second extraction reaction kettle 11 respectively and can be directly used as clean soil backfill;
third, the raffinate is subjected to water-oil-gas three-phase separation in a first separator 13, and CO containing part of light component oil 2 The gas is discharged from the top of the first separator 13 at 550m 3 The pressure of the water phase is regulated to be 4.5-5.0MPa by a second pressure reducing valve 14, the water phase is sent to the middle part of a second separator 15, the oil phase is sent to a first storage tank 16 from the middle upper part of a first separator 13 at the rate of 28kg/h, and the water phase is sent to a high-grade oxidation pond 20 from the bottom of the first separator 13 at the rate of 10 kg/h; CO containing a portion of the light component oil 2 The gas is further separated in a second separator 15, the separated light fraction oil flows from the bottom of the second separator 15 into a second storage tank 17, and CO containing a small amount of oil 2 With 165m of gas 3 /h CO fed to the bottom of the advanced oxidation tank 20 2 In the ejector coil 201; then adding biochar and sodium persulfate into the advanced oxidation pond 20 according to the mass ratio of 1:6, and removing CO of petroleum hydrocarbon through oxidation reaction 2 The gas is discharged from the top of the advanced oxidation tank 20 and passes through a filter valve 21 and supplemented CO 2 The gas is sent to a cooler 23 by a compressor 22 to be cooled to 0-4 ℃ and then sent to CO 2 The solid-liquid mixture is discharged from the lower part of the advanced oxidation tank 20 and is sent into a second central pipe 251 of the vertical-flow sedimentation tank 25 through a second discharge pump 24, the supernatant after sedimentation is discharged from the upper part of the vertical-flow sedimentation tank 25 for recycling, and the solid residues are discharged from the bottom of the vertical-flow sedimentation tank 25 as clean soil backfill.
An ultrasonic vibration plate 71 is arranged in the pretreatment tank 7, the operation temperature is 50 ℃, and the stirring intensity is 0.9-1.2kW/m 3 The liquid retention time was 1.5h.
The sieve plates in the first extraction reaction kettle 9 are obliquely arranged, the inclination angle is 25 degrees, the operating temperature is 45-55 ℃, the operating pressure is 10-20MPa, and the extraction time is 8-10h; the sieve plates in the second extraction reaction kettle 11 are obliquely arranged, the inclination angle is 25 degrees, the operating temperature is 45-55 ℃, the operating pressure is 10-20MPa, and the extraction time is 8-10h; when the oil sludge is treated, the first extraction reaction kettle 9 and the second extraction reaction kettle 11 are operated in series; when the oil-containing soil is treated, the first extraction reaction kettle 9 and the second extraction reaction kettle 11 are operated in parallel.
The first supercriticalCO 2 Injection pipe 94 and second supercritical CO 2 The injection pipes 114 are respectively arranged at the lower parts of the first extraction reaction kettle 9 and the second extraction reaction kettle 11 in the form of coils, and the first supercritical CO 2 Injection pipe 94 and second supercritical CO 2 Micropores with a diameter of 5mm and an aperture ratio of 30% are formed below the ejector tube 114.
The first separator 13 is internally provided with a first central tube 132, the operating temperature is 60 ℃, and the operating pressure is 2.5-3.0MPa.
The operating pressure of the second separator 15 is 4.5-5.0MPa.
The bottom of the advanced oxidation tank 20 is provided with CO 2 Injection coil 201, CO 2 Micropores are formed below the spraying coil 201, the diameter of the micropores is 3mm, the aperture ratio is 35%, and the reaction time is 5-7h.
The above embodiments are merely illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solution of the present invention may be made without departing from the spirit of the present invention, which is defined in the claims of the present invention.

Claims (6)

1. Super-critical CO of oil sludge and oil-containing soil 2 The extraction and recovery comprehensive treatment process is characterized by comprising the following steps of:
first step, CO 2 Liquid CO in a tank (1) 2 The high-pressure pump (2) is used for increasing the pressure to 10-20MPa and then mixing the high-pressure pump with entrainer methanol conveyed by a metering pump (4) in a mixer (5), then respectively feeding the hot water into tube passes of the first preheater (6A) and the second preheater (6B), and sequentially feeding the hot water into shell passes of the first preheater (6A) and the second preheater (6B) and liquid CO 2 Fluid is in countercurrent contact to preheat the fluid to 45-55 ℃, and then the fluid is respectively sent into first supercritical CO at the bottoms of a first extraction reaction kettle (9) and a second extraction reaction kettle (11) 2 Injection pipe (94) and second supercritical CO 2 A jet pipe (114); the heat preservation water after preheating the first preheater (6A) and the second preheater (6B) is respectively sent into the first preservation of the first extraction reaction kettle (9)A temperature jacket (92) and a second heat-preserving jacket (112) of the second extraction reaction kettle (11); the heat preservation water outlet of the first extraction reaction kettle (9) is sent into a third heat preservation jacket (72) of the pretreatment tank (7), and the heat preservation water outlet of the second extraction reaction kettle (11) is sent into a fourth heat preservation jacket (131) of the first separator (13);
secondly, adding the oil sludge into a pretreatment tank (7), then adding a demulsifier, carrying out dehydration and desalination under the synergistic effect of ultrasonic waves, conveying the dehydrated and desalted oil sludge to the upper part of a first extraction reaction kettle (9) through a first spiral feeding device (8), and conveying the dehydrated and desalted oil sludge into the first extraction reaction kettle (9) through a first primary lock hopper (91) to carry out supercritical CO 2 Countercurrent contact of the fluid; the extract extracted by the first extraction reaction kettle (9) is discharged from the upper part of the first extraction reaction kettle (9), is sent into a first central pipe (132) of a first separator (13) by regulating pressure through a first pressure reducing valve (12), and the raffinate is discharged from the bottom of the first extraction reaction kettle (9), is sent to the upper part of a second extraction reaction kettle (11) by a second spiral feeding device (10), and is sent into the second extraction reaction kettle (11) through a second primary lock hopper (111) and supercritical CO 2 Countercurrent contact of the fluid; the extract extracted by the second extraction reaction kettle (11) is sent into a first central pipe (132) of a first separator (13) from the upper discharge of the second extraction reaction kettle (11) through a first pressure reducing valve (12), and the raffinate flows into a higher oxidation pond (20) from the bottom discharge of the second extraction reaction kettle (11) to further remove petroleum and other aromatic compounds and heavy metals remained in the raffinate, wherein the other aromatic compounds comprise benzene compounds, phenols, anthracene and pyrene; the wastewater removed by the pretreatment tank (7) is sent into an electrodialysis device (19) through a first discharge pump (18), concentrated brine produced by the electrodialysis device (19) is subjected to subsequent concentrated crystallization treatment, and the rest water is sent into a high-grade oxidation tank (20) for further treatment;
for oil-containing soil, the oil-containing soil is respectively sent to the upper parts of a first extraction reaction kettle (9) and a second extraction reaction kettle (11) through a first spiral feeding device (8) and a second spiral feeding device (10), and then is respectively sent into the first extraction reaction kettle (9) and the second extraction reaction kettle (11) through a first-stage lock hopper (91) and a second-stage lock hopper (111) to be mixed with supercritical CO 2 Fluid inversionFlow contact; the extracted extracts are respectively sent into a first central pipe (132) of a first separator (13) from the upper discharge of a first extraction reaction kettle (9) and a second extraction reaction kettle (11) through a first pressure reducing valve (12), and the raffinate is respectively directly used as clean soil backfill from the bottom discharge of the first extraction reaction kettle (9) and the second extraction reaction kettle (11);
thirdly, the raffinate is subjected to water-oil-gas three-phase separation in a first separator (13), and CO containing part of light component oil 2 The gas is sent to the middle part of the second separator (15) through the pressure regulation of the second pressure reducing valve (14) from the top discharge of the first separator (13), the oil phase is sent to the first storage tank (16) from the middle upper discharge of the first separator (13), and the water phase flows into the advanced oxidation pond (20) from the bottom discharge of the first separator (13); CO containing a portion of the light component oil 2 The gas is further separated in a second separator (15), the separated light component oil flows into a second storage tank (17) from the bottom of the second separator (15), and CO containing a small amount of oil 2 CO gas is sent to the bottom of the advanced oxidation tank (20) 2 In the ejector coil (201); then adding biochar and sodium persulfate into the advanced oxidation pond (20), and removing CO of petroleum hydrocarbon through oxidation reaction 2 The gas is discharged from the top of the advanced oxidation tank (20) and passes through a filter valve (21) and supplemented CO 2 The gas is sent to a cooler (23) for cooling by a compressor (22) and then is sent to CO 2 The solid-liquid mixture is sent into a second central pipe (251) of a vertical flow sedimentation tank (25) from the lower part of the advanced oxidation tank (20) through a second discharge pump (24), the supernatant after sedimentation is discharged from the upper part of the vertical flow sedimentation tank (25) for recycling, and the solid residues are discharged from the bottom of the vertical flow sedimentation tank (25) as clean soil backfill;
the temperature of the heat preservation water after preheating the first preheater (6A) and the second preheater (6B) is 80-85 ℃;
the temperature of the heat preservation water outlet of the first extraction reaction kettle (9) and the second extraction reaction kettle (11) is 65-70 ℃;
the mass ratio of the biochar to the sodium persulfate is 1:6;
the CO cooled by the cooler (23) 2 The gas temperature is 0-4 ℃;
the first extraction reaction kettle (9) and the second extraction reaction kettle (11) are internally provided with a sieve plate.
2. The process according to claim 1, characterized in that: an ultrasonic vibration plate (71) is arranged in the pretreatment tank (7), the operation temperature is 50 ℃, and the stirring strength is 0.9-1.2kW/m 3 The liquid retention time was 1.5h.
3. The process according to claim 1, characterized in that: the sieve plate in the first extraction reaction kettle (9) is obliquely arranged, the inclination angle is 25 degrees, the operation temperature is 45-55 ℃, the operation pressure is 10-20MPa, and the extraction time is 8-10h; the sieve plates in the second extraction reaction kettle (11) are obliquely arranged, the inclination angle is 25 degrees, the operating temperature is 45-55 ℃, the operating pressure is 10-20MPa, and the extraction time is 8-10h.
4. The process according to claim 1, characterized in that: the first supercritical CO 2 Injection pipe (94) and second supercritical CO 2 The injection pipes (114) are respectively arranged at the lower parts of the first extraction reaction kettle (9) and the second extraction reaction kettle (11) in the form of coils, and the first supercritical CO 2 Injection pipe (94) and second supercritical CO 2 Micropores are arranged below the jet pipe (114), the diameter of the micropores is 5mm, and the aperture ratio is 30%.
5. The process according to claim 1, characterized in that: a first central tube (132) is arranged in the first separator (13), the operation temperature is 60 ℃, and the operation pressure is 2.5-3.0MPa; the operating pressure of the second separator (15) is 4.5-5.0MPa.
6. The process according to claim 1, characterized in that: the bottom of the advanced oxidation pond (20) is provided with CO 2 Injection coil (201), CO 2 Micropores are formed below the spraying coil pipe (201), the diameter of the micropores is 3mm, the aperture ratio is 35%, and the reaction time is 5-7h.
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