A comprehensive treatment system and method for oily sludge

Abstract

The invention relates to the technical field of energy conservation and environmental protection, and in particular to a comprehensive treatment system and method for oily sludge. The treatment system comprises an oily sludge pretreatment device and a pyrolysis and incineration combination device which are sequentially connected and arranged; the oily sludge pretreatment device comprises an oily sludge tank, a tank bottom oil sludge tank, a floor oil sludge tank, a solvent circulation tank, a solvent modification device, a solid-liquid separation device, an electric desalting device, a solvent recovery unit, a hydrogenation device oil recovery and quality separation unit and a solid residue drying and desolventizing device; the pyrolysis and incineration combination device comprises a feeding belt conveyor, a first air lock feeder, a second air lock feeder, a double screw feeder, an external heat type pyrolysis furnace, a burner, a rotary incinerator and an oil recovery and treatment device; compared with the prior art, the oily sludge is utilized in stages, and by setting a pyrolysis and incineration module, the crude oil in the sludge can be completely extracted and recovered, and the treatment can be ensured to be thorough, thereby achieving maximum reduction, harmlessness and resource utilization.

Description

Technical Field

[0001] The present invention relates to the technical field of energy conservation and environmental protection, and in particular to a comprehensive treatment system and method for oily sludge. Background Art

[0002] Oily sludge is one of the oily solid pollutants produced during crude oil extraction, oil refining and transportation, and sewage treatment. It has the characteristics of stable chemical properties, complex and variable composition, high oil content, few comprehensive utilization methods, and great difficulty in treatment. It has always been listed as one of the pollutants that need to be treated urgently by oil-related companies. Its production mainly includes tank bottom sludge produced by sedimentation tanks, storage tanks, sewage tanks, and pool bottom mud; ground sludge produced by crude oil extraction and downhole operations; and sludge produced by crude oil refining in refineries and sewage treatment in sewage treatment plants.

[0003] The main components of oily sludge are crude oil, water and mud, and the oil content is usually between 10% and 50%. It is estimated that China produces nearly 3 million tons of oily sludge annually, of which the crude oil resources are about 600,000 tons. Oily sludge contains a large amount of odorous toxic substances such as benzene, phenols, anthracene, pyrene, etc., but at the same time these substances are also components of crude oil. Oily sludge is not only a waste generated in the production process of oil fields, but also a resource. If the oily sludge is not treated to recover the oil in it, it will not only pollute the environment, but also cause a waste of resources.

[0004] The treatment of oily sludge has always been a major problem that plagues oil fields. For many years, the method of disposing oily sludge in my country's oil fields has basically been to landfill abandoned oil pits. The non-standard abandonment and disposal process has great potential environmental pollution. If appropriate technical means are used to harmlessly treat oily sludge and recover residual oil, it will not only produce certain economic benefits, but also reduce pollution and bring huge environmental and social benefits.

[0005] Common treatment and disposal technologies for oily sludge include extraction, incineration, thermochemical washing, thermal desorption and other methods. From a comprehensive comparison of investment and operating costs, treatment scale and treatment effect, the use of a single process has shortcomings. Therefore, it is necessary to develop an oily sludge treatment device that can meet more stringent standards. Summary of the invention

[0006] The purpose of the present invention is to address the shortcomings of the existing single treatment process for oily sludge. The present invention aims to provide a comprehensive treatment system for oily sludge to achieve the purpose of improving the operating effect and economic benefits of the oily sludge treatment and disposal technology.

[0007] The object of the present invention is achieved through the following technical solutions: The present application provides an oily sludge comprehensive treatment system, comprising an oily sludge pretreatment device and a pyrolysis and incineration combination device which are sequentially connected; the oily sludge pretreatment device comprises an oily sludge tank, a tank bottom oil sludge tank, a floor oil sludge tank, a solvent circulation tank, a solvent modification device, a solid-liquid separation device, an electric desalting device, a solvent recovery unit, a hydrogenation device oil recovery unit and a solid residue drying and desolventizing device; the oily sludge tank, the tank bottom oil sludge tank, the floor oil sludge tank and the solvent circulation tank are respectively connected to the solvent modification device, the solvent modification device is respectively connected to the electric desalting device and the solid residue drying and desolventizing device through the solid-liquid separation device, the electric desalting device is connected to the solvent recovery unit, the solvent recovery unit is respectively connected to the hydrogenation device oil recovery unit and the solvent circulation tank, and the hydrogenation device oil recovery unit It is connected to the solvent circulation tank, and the solid slag drying and desolventizing device is connected to the solvent circulation tank; the pyrolysis and incineration combination device includes a feeding belt conveyor, a first air lock feeder, a second air lock feeder, a double screw feeder, an external heating pyrolysis furnace, a burner, a rotary incinerator and an oil recovery and processing device; the feeding port and the discharging port of the double screw feeder are respectively connected to the first air lock feeder and the second air lock feeder, the end of the feeding belt conveyor is arranged at the feeding end of the first air lock feeder, the double screw feeder is fixedly installed in the inner cylinder of the external heating pyrolysis furnace, and the end of the double screw feeder is connected to the oil recovery and processing device; the starting end of the feeding belt conveyor is connected to the solid slag drying and desolventizing device of the oil-containing sludge pretreatment device; the air inlet of the external heating pyrolysis furnace is connected to the rotary incinerator, one side of the rotary incinerator is connected to the burner, and the other side is connected to the second air lock feeder.

[0008] Among them, the flow direction of the flue gas in the external heating pyrolysis furnace is opposite to the conveying direction of the double-screw feeder.

[0009] Among them, a feeding hopper is arranged at the feeding end of the first air lock feeder.

[0010] The pyrolysis and incineration combined device also includes a flue gas purification device, which is connected to the gas outlet of the external heating pyrolysis furnace.

[0011] The present application also provides a comprehensive treatment method for oily sludge, comprising the following steps: step A, oily sludge modification, the oily sludge in the oily sludge tank, the bottom oily sludge tank, the floor oily sludge tank and the naphtha fraction solvent in the solvent circulation tank are transported to a solvent modification device, and the oil phase is dissolved and diluted by utilizing the similarity dissolving property of the solvent, so that the oil phase originally fixed in the oily sludge is transferred to the liquid phase of the solvent through leaching; step B, dehydration and impurity removal, the modified oily sludge in step A is transported to a solid-liquid separation device for solid-liquid two-phase separation, the liquid phase separated from the solid-liquid separation enters the electric desalting device and removes the water and solid phase residue remaining in the oil agent mixture, the solid phase separated from the solid-liquid separation enters the solid residue drying and desolventizing device for drying treatment and then transported to a hot Decomposition and incineration module; Step C, solvent recovery, the oil-agent mixture after desalting and dehydration in the electric desalting device in Step B is heat exchanged to 160°C and then enters the solvent recovery unit, in the solvent recovery unit, the solvent is evaporated and vaporized to be separated from the dissolved oil phase, the solvent vapor is heat exchanged with the oil-agent mixture and then cooled and condensed, and enters the solvent circulation tank, and the regenerated oil in the solvent recovery unit enters the hydrogenation device to recover the oil separation unit. Step D, pyrolysis and incineration, the oil-containing sludge in Step B is pretreated by solvent modification, the oil-containing sludge is sent to the external heating pyrolysis furnace through the oil sludge feeding belt conveyor through the double screw conveyor for pyrolysis and desorption to obtain regenerated oil, and the remaining oil-containing sludge continues to enter the rotary incinerator for incineration to generate high-temperature flue gas, and the generated high-temperature flue gas is used as the heat source required for pyrolysis in the external heating pyrolysis furnace.

[0012] Among them, in step D, there is a space for high-temperature flue gas to circulate between the outer cylinder and the inner cylinder of the external heating pyrolysis furnace. The temperature in the space is between 450 and 600°C. The high-temperature flue gas transfers heat to the oil sludge in the double-screw feeder.

[0013] Wherein, in step D, the flow direction of the flue gas in the external heating pyrolysis furnace is opposite to the material conveying direction of the double screw conveyor.

[0014] Among them, in step D, the rotary incinerator adopts a mixed heat exchange method, and the material is in direct contact with the high-temperature flue gas, so that the combustibles in the material are burned out quickly.

[0015] Among them, in step D, the material coming out of the external heating pyrolysis furnace contains a trace amount of oil hydrocarbons and charcoal, which are completely burned in the rotary incinerator. The flue gas temperature in the rotary incinerator is between 850 and 1100°C.

[0016] Among them, in step D, a burner is arranged at one end of the rotary incinerator. When the calorific value of the oily sludge in the rotary incinerator is low, the burner provides a supplementary heat source for the rotary incinerator and the external heating pyrolysis furnace, and the fuel in the burner is natural gas.

[0017] Beneficial effects of the present invention: Compared with the existing oily sludge treatment technology, the comprehensive treatment system of the oily sludge of the present application, first, the oily sludge is pretreated by an oily sludge pretreatment device, and solvent extraction is used to achieve oil recovery of the oily sludge, which meets the requirements of circular economic development; second, the present application realizes the cascade utilization of oily sludge. By setting up a pyrolysis and incineration module, it can not only fully extract and recover the crude oil in the sludge, but also ensure thorough treatment. The thermal reduction rate of the treated sludge is close to zero, thereby achieving maximum reduction, harmlessness and resource utilization.

[0018] The present application discloses a comprehensive treatment method for oily sludge. Compared with the prior art, the treatment method of the present application can not only completely extract and recover the crude oil in the sludge, but also ensure thorough treatment. The thermal reduction rate of the treated sludge is close to zero, thereby achieving maximum reduction, harmlessness and resource utilization, and avoiding the technical feasibility and economic defects brought about by a single process treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described using the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative work.

[0020] Figure 1 It is a schematic structural diagram of the comprehensive treatment system of oily sludge in this embodiment.

[0021] Figure markings: 1-oil sludge tank, 2-bottom oil sludge tank, 3-ground oil sludge tank, 4-solvent circulation tank, 5-solvent modification device, 6-solid-liquid separation device, 7-electric desalting device, 8-solvent recovery unit, 9-hydrogenation device oil recovery and separation unit, 10-solid residue drying and desolventizing, 11-oil sludge feeding belt conveyor, 12-feeding hopper, 13a-first air lock feeder, 13b-second air lock feeder, 14-double screw conveyor, 15-external heating pyrolysis furnace, 16-burner, 17-rotary incinerator, 18-oil recovery and processing device, 19-flue gas purification device. DETAILED DESCRIPTION

[0022] The present invention is further described in conjunction with the following examples.

[0023] A specific implementation of the oily sludge comprehensive treatment system of the present invention is as follows Figure 1 As shown, the treatment system includes an oily sludge treatment device and a pyrolysis and incineration combination device which are connected in sequence.

[0024] In this embodiment, the oily sludge treatment device includes an oily sludge tank 1, a tank bottom oil sludge tank 2, a floor oil sludge tank 3, a solvent circulation tank 4, a solvent modification device 5, a solid-liquid separation device 6, an electric desalting device 7, a solvent recovery unit 8, a hydrogenation device oil recovery unit 9 and a solid residue drying and desolventizing device 10; the oily sludge tank 1, the tank bottom oil sludge tank 2, the floor oil sludge tank 3, and the solvent circulation tank 4 are respectively connected to the solvent modification device 5, the solvent modification device 5 is respectively connected to the electric desalting device 7 and the solid residue drying and desolventizing device 10 through the solid-liquid separation device 6, the electric desalting device 7 is connected to the solvent recovery unit 8, the solvent recovery unit 8 is respectively connected to the hydrogenation device oil recovery unit 9 and the solvent circulation tank 4, the hydrogenation device oil recovery unit 9 is connected to the solvent circulation tank 4, and the solid residue drying and desolventizing device 10 is connected to the solvent circulation tank 4.

[0025] In this embodiment, the pyrolysis and incineration combined device includes a feeding belt conveyor, a first air lock feeder 13a, a second air lock feeder 13b, a double screw feeder 14, an external heating pyrolysis furnace 15, a burner 16, a rotary incinerator 17 and an oil recovery and processing device 18. The feeding port and the discharge port of the double screw feeder 14 are respectively connected to the first air lock feeder 13a and the second air lock feeder 13b, the end of the feeding belt conveyor is arranged at the feeding end of the first air lock feeder 13a, the double screw feeder 14 is fixedly installed in the inner cylinder of the external heating pyrolysis furnace 15, and the end of the double screw feeder 14 is connected to the oil recovery and processing device 18. The starting end of the feeding belt conveyor is connected to the solid residue drying and desolventizing device 10 of the oily sludge treatment device; the air inlet of the external heating pyrolysis furnace 15 is connected to the rotary incinerator 17, one side of the rotary incinerator 17 is connected to the burner 16, and the other side is connected to the second air lock feeder 13b. A feeding hopper is provided at the feeding end of the first air lock feeder 13a.

[0026] In this embodiment, the flue gas flow direction in the external heating pyrolysis furnace 15 is opposite to the conveying direction of the double screw feeder 14. The high-temperature flue gas and the material are in a countercurrent and indirect heat exchange mode, and the oil sludge is turned and stirred in the external heating pyrolysis furnace 15 and moves forward, further improving and enhancing the heat transfer efficiency.

[0027] In this embodiment, the pyrolysis and incineration combined device further includes a flue gas purification device 19 , and the flue gas purification device 19 is connected to the gas outlet of the external heating pyrolysis furnace 15 .

[0028] Compared with the existing oily sludge treatment technology, the comprehensive treatment system of oily sludge in the present application has the following advantages: first, the oily sludge is pretreated by an oily sludge pretreatment device, and the oil in the oily sludge is recovered by solvent extraction, which meets the requirements of circular economic development; second, the present application realizes the cascade utilization of oily sludge. By setting up a pyrolysis and incineration module, it can not only fully extract and recover the crude oil in the sludge, but also ensure thorough treatment. The thermal reduction rate of the treated sludge is close to zero, thereby achieving maximum reduction, harmlessness and resource utilization.

[0029] The specific implementation method of the comprehensive treatment method of oily sludge of the present invention comprises the following steps: Step A, oily sludge modification, the oily sludge in the oily sludge tank 1, the tank bottom oily sludge tank 2, the floor oily sludge tank 3 and the naphtha fraction solvent in the solvent circulation tank 4 are transported to the solvent modification device 5, and the oil phase is dissolved and diluted by utilizing the similarity dissolving property of the solvent, so that the oil phase originally fixed in the oily sludge is transferred to the liquid phase of the solvent through leaching. Step B, dehydration and impurity removal, the oily sludge modified in step A is transported to the solid-liquid separation device 6 for solid-liquid two-phase separation, the liquid phase separated from the solid-liquid enters the electric desalting device 7 and removes the water and solid phase residue remaining in the oil agent mixture (after desalting: salt content <2ppm; water content <0.15%; organic impurities <0.1%), the solid phase separated from the solid-liquid enters the solid residue drying and desolventizing device 10 for drying treatment and then transported to the pyrolysis incineration module. Step C, solvent recovery, the oil-agent mixture after desalting and dehydration in the electric desalting device 7 in step B is heat exchanged to 160°C and then enters the solvent recovery unit 8, in which the solvent is evaporated and vaporized to separate from the dissolved oil phase, the solvent vapor is heat exchanged with the oil-agent mixture and then cooled and condensed, and enters the solvent circulation tank 4, and the regenerated oil in the solvent recovery unit 8 enters the hydrogenation device oil recovery and separation unit 9. Step D, pyrolysis and incineration, the oil-containing sludge in step B is pre-treated by solvent modification, and the oil-containing sludge is sent to the external heating pyrolysis furnace 15 through the oil sludge feeding belt conveyor 11 through the double screw conveyor 14 for pyrolysis and desorption to obtain regenerated oil, and the remaining oil-containing sludge continues to enter the rotary incinerator 17 for incineration to generate high-temperature flue gas, and the generated high-temperature flue gas is used as the heat source required for pyrolysis in the external heating pyrolysis furnace 15.

[0030] In step D, there is a space between the outer cylinder and the inner cylinder of the external heating pyrolysis furnace 15 for high temperature flue gas to circulate, and the temperature in the space is between 450 and 600°C. The high temperature flue gas transfers heat to the oil sludge in the double screw feeder 14. The oil sludge is pyrolyzed in the air-tight condition, so that the oil hydrocarbon organic matter is volatilized and precipitated, and the water in the sludge is also evaporated and precipitated. The oil-gas mixture released by the pyrolysis is collected and enters the oil recovery and processing device 18.

[0031] In step D, the flue gas flow direction in the external heating pyrolysis furnace 15 is opposite to the material conveying direction of the double screw feeder 14. The high-temperature flue gas and the material are in a countercurrent and indirect heat exchange mode, and the oil sludge is turned and stirred in the external heating pyrolysis furnace 15 and moves forward, further improving and enhancing the heat transfer efficiency.

[0032] Among them, in step D, the rotary incinerator 17 adopts a mixed heat exchange method, and the material is in direct contact with the high-temperature flue gas, so that the combustibles in the material are quickly burned out. In addition, the material coming out of the external heat pyrolysis furnace 15 contains a trace amount of oil hydrocarbons and charcoal, which are completely burned in the rotary incinerator 17. The flue gas temperature in the rotary incinerator 17 is between 850 and 1100°C, and the thermal ignition reduction rate of the discharged ash is close to zero.

[0033] Among them, in step D, a burner 16 is arranged at one end of the rotary incinerator 17. When the calorific value of the oil-containing sludge in the rotary incinerator 17 is low, the burner 16 provides a supplementary heat source for the rotary incinerator 17 and the external heating pyrolysis furnace 15. The fuel in the burner 16 is natural gas, the combustion temperature is about 900°C, and the flue gas temperature discharged from the kiln tail is about 600°C. The non-condensable gas containing trace amounts of VOC discharged from the oil recovery and processing device 18 is sent to the burner 16 as part of the air required for combustion and is not discharged. Finally, the ash discharged from the rotary incinerator 17 is transported out after cooling as building materials or roadbed materials.

[0034] The comprehensive treatment method of oily sludge in this embodiment can not only completely extract and recover the crude oil in the sludge, but also ensure thorough treatment. The thermal reduction rate of the treated sludge is close to zero, thereby achieving maximum reduction, harmlessness and resource utilization, and avoiding the technical feasibility and economic defects brought about by a single process treatment.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A comprehensive treatment system for oily sludge, characterized in that: It comprises an oily sludge pretreatment device and a pyrolysis and incineration combined device which are connected in sequence; The oily sludge pretreatment device comprises an oily sludge tank (1), a tank bottom oily sludge tank (2), a floor oily sludge tank (3), a solvent circulation tank (4), a solvent modification device (5), a solid-liquid separation device (6), an electric desalination device (7), a solvent recovery unit (8), a hydrogenation device oil recovery unit (9) and a solid residue drying and desolventizing device (10); The oily sludge tank (1), the bottom oil sludge tank (2), the floor oil sludge tank (3), and the solvent circulation tank (4) are respectively connected to the solvent modification device (5); the solvent modification device (5) is respectively connected to the electric desalting device (7) and the solid residue drying and desolventizing device (10) through the solid-liquid separation device (6); the electric desalting device (7) is connected to the solvent recovery unit (8); the solvent recovery unit (8) is respectively connected to the hydrogenation device oil recovery unit (9) and the solvent circulation tank (4); the hydrogenation device oil recovery unit (9) is connected to the solvent circulation tank (4); and the solid residue drying and desolventizing device (10) is connected to the solvent circulation tank (4); The pyrolysis and incineration combined device comprises a feeding belt conveyor (11), a first air-locking feeder (13a), a second air-locking feeder (13b), a double-screw conveyor (14), an external-heating pyrolysis furnace (15), a burner (16), a rotary incinerator (17), and an oil recovery and processing device (18); The feed port and the discharge port of the double-screw feeder (14) are respectively connected to the first air-locking feeder (13a) and the second air-locking feeder (13b); the end of the feeding belt conveyor (11) is arranged at the feed end of the first air-locking feeder (13a); the double-screw feeder (14) is fixedly installed in the inner cylinder of the external heating pyrolysis furnace (15); and the end of the double-screw feeder (14) is connected to the oil recovery and processing device (18); The starting end of the feeding belt conveyor (11) is connected to the solid residue drying and desolventizing device (10) of the oily sludge pretreatment device; The air inlet of the external heating pyrolysis furnace (15) is connected to the rotary incinerator (17); one side of the rotary incinerator (17) is connected to the burner (16), and the other side is connected to the second air lock feeder (13b); The flow direction of the flue gas in the externally heated pyrolysis furnace (15) is opposite to the conveying direction of the double-screw conveyor (14); The pyrolysis and incineration combined device also includes a flue gas purification device (19), wherein the flue gas purification device (19) is connected to the gas outlet of the external heating pyrolysis furnace (15).

2. The oily sludge comprehensive treatment system according to claim 1 is characterized by: A feeding hopper (12) is provided at the feeding end of the first air lock feeder (13a).

3. A comprehensive treatment method for oily sludge, characterized in that: The steps include: Step A, oil sludge modification, the oil sludge in the oily sludge tank (1), the bottom oil sludge tank (2), the floor oil sludge tank (3) and the naphtha fraction solvent in the solvent circulation tank (4) are transported to the solvent modification device (5), and the oil phase is dissolved and diluted by utilizing the similarity dissolving property of the solvent, so that the oil phase originally fixed in the oil sludge is transferred to the liquid phase of the solvent through leaching; Step B, dehydration and impurity removal, the oil sludge modified in step A is transported to a solid-liquid separation device (6) for solid-liquid two-phase separation, the liquid phase separated from the solid-liquid separation enters an electric desalting device (7) to remove the water and solid phase residues remaining in the oil agent mixture, the solid phase separated from the solid-liquid separation enters a solid residue drying and desolventizing device (10) for drying treatment and then transported to a pyrolysis incineration module; Step C, solvent recovery, the oil-agent mixture after desalting and dehydration in the electric desalting device (7) in step B is heat exchanged to 160° C. and then enters the solvent recovery unit (8), in which the solvent is evaporated and vaporized and separated from the dissolved oil phase, the solvent vapor is heat exchanged with the oil-agent mixture and then cooled and condensed and enters the solvent circulation tank (4), and the regenerated oil in the solvent recovery unit (8) enters the oil recovery and separation unit (9) of the hydrogenation device; Step D, pyrolysis and incineration, after the oily sludge in step B is pre-treated by solvent modification, the oily sludge is sent to an external heating pyrolysis furnace (15) through an oily sludge feeding belt conveyor (11) and a double screw conveyor (14) for pyrolysis and desorption to obtain regenerated oil, and the remaining oily sludge continues to enter a rotary incinerator (17) for incineration to generate high-temperature flue gas, and the generated high-temperature flue gas is used as a heat source required for pyrolysis in the external heating pyrolysis furnace (15).

4. The comprehensive treatment method for oily sludge according to claim 3 is characterized in that: In step D, there is a space between the outer cylinder and the inner cylinder of the external heating pyrolysis furnace (15) for high-temperature flue gas to circulate, and the temperature in the space is between 450 and 600° C. The high-temperature flue gas transfers heat to the oil sludge in the double-screw conveyor (14).

5. The comprehensive treatment method for oily sludge according to claim 3 is characterized in that: In step D, the flow direction of the flue gas in the externally heated pyrolysis furnace (15) is opposite to the material conveying direction of the double screw conveyor (14).

6. The comprehensive treatment method for oily sludge according to claim 3 is characterized in that: In step D, the rotary incinerator (17) adopts a mixed heat exchange method, where the material is in direct contact with the high-temperature flue gas, so that the combustibles in the material are quickly burned out.

7. The comprehensive treatment method for oily sludge according to claim 3 is characterized in that: In step D, the material coming out of the external heating pyrolysis furnace (15) contains a small amount of oil hydrocarbons and charcoal, which are completely burned in the rotary incinerator (17). The flue gas temperature in the rotary incinerator (17) is between 850 and 1100°C.

8. The comprehensive treatment method for oily sludge according to claim 3 is characterized in that: In step D, a burner (16) is arranged at one end of the rotary incinerator (17). When the calorific value of the oily sludge in the rotary incinerator (17) is low, the burner (16) provides a supplementary heat source for the rotary incinerator (17) and the external heating pyrolysis furnace (15). The fuel in the burner (16) is natural gas.

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