A system for treating oil-containing sludge and a method of treating the same

Abstract

The application discloses a treatment system and method for oily sludge, which comprises a pretreatment and storage module, a wet oxidation heat exchange reaction module, a conditioning water module, an oily sludge pumping module and a self-gas stripping sedimentation separation module. The pretreatment and storage module is used to remove impurities in foreign oily sludge, the wet oxidation heat exchange reaction module is used to perform wet oxidation reaction on the oily sludge to realize oxidation modification and demulsification, the self-gas stripping sedimentation separation module is used to perform three-phase separation on the oxidized oily sludge and utilize reaction heat and reaction gas in the oxidation reaction process, the reaction heat is used to make the temperature in the separation process higher than the 'wall temperature' to ensure efficient separation, and the reaction gas is used to adhere to oil droplets to accelerate the floating separation of the oil phase. In particular, carbon dioxide in the reaction gas dissolves in water to generate carbonic acid to form an acidic environment, which can promote the polymerization of oil droplets to improve the separation effect.

Description

Technical Field

[0001] This invention relates to the field of oily sludge treatment technology, and particularly to an oily sludge treatment system and method. Background Technology

[0002] Oily sludge is a byproduct of the petroleum industry, possessing the dual characteristics of both petroleum resource and hazardous waste. It is typically a black, viscous colloidal substance, formed by the emulsification of petroleum, crude oil, oil products, silt, and water. Its composition is complex, usually containing crude oil / mineral oil (5%–40%), water (10%–50%), silt (30%–70%), and small amounts of heavy metals and organic pollutants (such as polycyclic aromatic hydrocarbons (PAHs)). On the one hand, the petroleum substances in oily sludge are recyclable secondary resources (currently, my country loses hundreds of thousands of tons of crude oil annually due to oily sludge); on the other hand, its high oil content and high organic pollution characteristics have led to its inclusion in the "National Hazardous Waste List." Direct dumping or simple landfilling will not only cause soil and groundwater pollution (petroleum hydrocarbons can penetrate several meters into the soil), but also threaten the surrounding ecosystem and human health through the release of volatile organic compounds (VOCs). With the advancement of "dual carbon" targets and the upgrading of environmental regulations, my country has mainly formulated standards such as SY / T 7300—2016 "Technical Specification for Treatment, Disposal and Pollution Control of Oily Sludge from Onshore Oil and Gas Extraction" and SY / T 7301—2016 "Technical Requirements for Resource Utilization and Pollution Control of Oily Sludge from Onshore Oil and Gas Extraction." In addition, HJ607—2011 "Technical Specification for Pollution Control of Waste Mineral Oil Recycling" stipulates that oily sludge with an oil content greater than 5% should be utilized for resource recovery, and the oil content of the treated oily sludge should be less than 2%. The "Law of the People's Republic of China on the Prevention and Control of Environmental Pollution by Solid Waste" stipulates that the emission threshold for petroleum hydrocarbons from oily sludge should be ≤2%. Therefore, developing efficient, low-consumption, and resource-efficient oily sludge treatment technologies has become an urgent need for the industry and has significant economic and social implications.

[0003] Current mainstream technologies for treating oily sludge can be categorized into traditional physical methods, pyrolysis / incineration, biological methods, and chemical oxidation methods, but each has its own limitations. Traditional physical methods suffer from low separation efficiency, high cost, and a high risk of secondary pollution. Solvent extraction utilizes organic solvents (such as diesel oil and furfural) to dissolve the oil phase before separation. This method is effective for low-viscosity sludge, but solvent recovery is costly (requiring distillation and purification) and carries the risk of solvent residue. For high-viscosity, heavily emulsified sludge, the solvent struggles to penetrate the sludge, significantly reducing treatment efficiency. Centrifugation / filtration dehydration separates free water and oil phases mechanically, but it only removes surface-adsorbed free oil (oil removal rate is typically <60%), proving almost ineffective against emulsified oil and oil components adsorbed on the surface of sludge particles, and it cannot degrade organic pollutants in the sludge.

[0004] Pyrolysis / incineration technology: This technology uses high temperatures (400~800℃) to pyrolyze the organic matter in oil sludge into oil and gas for recovery, with the residue used in building materials. However, this technology is extremely energy-intensive, and the incineration process easily produces highly toxic substances such as dioxins, requiring a complex exhaust gas purification system. Furthermore, the high temperatures may cause some light oil components to be excessively pyrolyzed into non-condensable gases (CO / CO2), reducing crude oil recovery rates and easily leading to deflagration and explosion accidents, posing significant safety risks.

[0005] (3) Biological treatment method: long cycle and limited applicability. Theoretically, the biological method degrades the organic matter in oil sludge through microorganisms. However, in practical applications, the high toxicity of oil sludge (heavy metals and PAHs inhibit microbial activity), low nutrient ratio (C / N / P imbalance) and complex emulsification system lead to a long adaptation period for microorganisms. Moreover, the treatment effect on oil sludge with high oil content (>15%) is poor (the final residual oil rate is often >3%), making it difficult to meet strict environmental protection standards.

[0006] (4) Chemical oxidation method: This method is rarely used in practice and suffers from incomplete oxidation, high cost of oxidants, and separation bottlenecks. Chemical oxidation (such as Fenton oxidation and ozone oxidation) decomposes large molecular organic matter in sludge using strong oxidants, which can partially demulsify and reduce oil content. However, traditional oxidation methods have the following problems: ① Low utilization rate of oxidants (e.g., Fenton reaction requires strict control of pH=3~4, and Fe 2+ ① It is difficult to regenerate, resulting in high treatment costs; ② It has limited demulsification effect on emulsion systems with high viscosity oil phases, and the sludge after oxidation is still in a stable three-phase mixture of oil-water-sludge, resulting in low efficiency of subsequent separation (such as centrifugation and sedimentation); ③ The reaction process is prone to generating secondary solid waste such as iron-containing sludge, increasing the treatment burden.

[0007] (5) Hydrothermal Treatment Technology: Literature review shows that existing hydrothermal treatment technologies involve hydrolyzing, breaking down, and oxidizing the large organic molecules in oily sludge under high temperature and pressure, followed by mechanical dehydration. Based on whether an oxidant is introduced, it is divided into two technical routes: hot hydrolysis and wet oxidation. Currently, most patents and scientific literature on hydrothermal treatment of oily sludge use hot hydrolysis technology, such as CN108892348A, CN117361813A, CN119528400A, CN210287095U, etc.; while relatively few use wet oxidation technology to treat oily sludge, such as CN210855744U, CN106396312A, CN100480201C, etc., and most of the wet oxidation treatments of oily sludge utilize oxidants (oxygen, hydrogen peroxide) in water at ultra-high temperature and pressure. The superoxidant capacity of the sludge degrades most of the organic matter in the sludge into small molecule organic matter and even CO2 and H2O, and then mechanically dewaters it. The oil in the sludge, as a harmful organic matter, is mainly oxidized and degraded and cannot be utilized. However, there are relatively few research and application cases of wet oxidation treatment of oily sludge under medium-low temperature and pressure conditions. The main reason is that wet oxidation under medium-low temperature and pressure conditions is difficult to oxidize the oil in oily sludge. Extraction is also required (such as the combined wet oxidation + solvent extraction process used in CN112062366A), which makes separation difficult and the process complex. Furthermore, existing patented technologies for wet oxidation treatment of oily sludge have several shortcomings: 1) They employ ultra-high pressure and high temperature, resulting in extremely high equipment investment and insufficient safety. Corrosion and scaling are also severe under ultra-high temperature conditions; 2) In terms of heat recovery, traditional flash evaporation technology has a heat recovery rate of only 30-50%, wasting a large amount of reaction waste heat and resulting in high energy costs. Simultaneously, high-temperature acidic vapors cause corrosion and perforation in stainless steel equipment; 3) Regarding the reliability of key components, most existing technologies use a batch process, and frequent depressurization operations cause rapid wear of the pressure-reducing valve sealing surfaces, with instantaneous wear of 1.5-3... 4) Regarding material adaptability, the viscosity of oily sludge increases sharply (3-5 times or even tens of times) at low temperatures (<15℃), leading to the failure of the feeding system; 5) In terms of system integration, most patents have not achieved energy coupling, failing to fully utilize the pressure and heat energy of the oily sludge after reaction. The main reasons are the high flow resistance of oily sludge, making transportation difficult and heat exchange performance poor, even causing blockage of pipes and equipment on the walls; 6) Regarding separation after wet oxidation, due to the lack of full utilization of the heat energy in the process, the temperature of the oily sludge after wet oxidation is uncontrollable and low due to the influence of environment, season, incoming materials, operation, and other factors, making separation difficult. In particular, the temperature is likely to be lower than the wall temperature during the separation process, making separation difficult to achieve. Even with technologies such as centrifugation, extraction, and membrane separation, the separation effect is poor and the cost is high, or separation may not be achieved at all. Therefore, these defects in the current wet oxidation technology for treating oily sludge seriously restrict the industrial application of wet oxidation technology in the field of oily sludge treatment.

[0008] Wet oxidation technology, as an advanced oxidation technology, can effectively destroy emulsion structures and has been proven in the field of water treatment. For example, wet oxidation is used to demulsify emulsions in machining processes. Published literature includes: Research on the influencing factors of wet oxidation of high-concentration, recalcitrant emulsified wastewater, Environmental Science Research, 2004, 17(2):38-41. Existing studies generally regard wet oxidation as a degradation method, with the goal of organic matter mineralization, reduction, COD removal and improvement of biodegradability. However, "demulsification-oil recovery" is not taken as the core goal. That is, the research on wet oxidation treatment of oily sludge focuses on "degradation" rather than "demulsification-recovery". However, there are relatively few studies on "demulsification + recovery" of sludge containing wet oxidation technology. When using the proven wet oxidation technology in the field of wastewater treatment to demulsify oily sludge, the separation of oil, water and sludge, as well as efficiency and cost, are still bottlenecks. In addition, conventional static sedimentation + flotation separation, extraction, membrane separation and other processes require additional chemical reagents and energy, which increases operating costs and process complexity. Furthermore, wet oxidation processes themselves generate reaction heat, acidic substances, and gases such as carbon dioxide. These byproducts are typically considered an additional burden requiring processing in traditional processes and are not effectively utilized. However, if fully utilized, they can be transformed from waste into valuable resources. Therefore, developing a new method and system that can fully utilize the materials and energy of the process itself, especially the process waste (such as carbon dioxide) and low-grade waste heat energy, to achieve low-energy consumption, high-efficiency, and resource-based treatment of oily sludge, has significant industrial application value and social significance. Summary of the Invention

[0009] This invention aims to overcome the deficiencies in the prior art by providing a treatment system and method for oily sludge. It combines wet oxidation as a modified demulsification method with oil phase separation and recovery processes, proposing a triple objective of "modified demulsification - oil recovery - sludge reduction." Furthermore, it accelerates and improves the separation effect through "deep heat recovery" and "self-extraction of reaction gas generated during the process." This significantly reduces process energy consumption and treatment costs while improving the oil recovery rate and the quality of the recovered oil, thus differing from the traditional "degradation-reduction" approach. This significantly reduces energy consumption and operating costs, achieves oil phase recovery and resource utilization, and further reduces the overall treatment cost significantly.

[0010] To achieve the above objectives, the present invention provides a system for treating oily sludge, comprising: The pretreatment and storage module includes an oil sludge storage tank, a sorting and filtering unit, and an oil sludge storage tank. The oil sludge storage tank is used to temporarily store foreign oil sludge, the sorting and filtering unit is used to remove impurities from the foreign oil sludge, and the oil sludge storage tank is used to store pretreated oil sludge. The wet oxidation heat exchange reaction module is used to perform wet oxidation reaction and heat exchange between conditioned sludge and oxidant to generate pressurized low-temperature sludge after wet oxidation, thereby achieving oxidative modification and demulsification of the sludge, and generating reaction gas containing carbon dioxide. Conditioning water module, which is used to provide conditioning water to the system; The sludge pumping module, which provides the power for the flow of sludge within the system, includes a raw sludge conveying pump installed on the pipeline between the sludge storage tank and the sludge storage tank, and a conditioning conveying pump installed on the pipeline between the sludge storage tank and the wet oxidation heat exchange reaction module. The conditioning conveying pump is used to mix the conditioning water provided by the conditioning water module with the pretreated sludge to generate conditioning sludge. The self-gas-lift sedimentation separation module includes a separation tower and a crude oil storage tank. The separation tower is used to receive pressurized low-temperature sludge and reaction gas after wet oxidation and to perform three-phase separation of oil, water and sediment within it. The crude oil storage tank is used to store the oil separated by the separation tower. In the three-phase separation process, the reaction gas in the separation tower is dissolved in water or dispersed in the liquid phase in the form of bubbles. The reaction gas bubbles can adhere to the oil droplets to accelerate the oil phase to float and separate. The carbon dioxide in the gas can dissolve in water to generate carbonic acid to form an acidic environment to promote the aggregation of oil droplets, thereby achieving efficient separation of oil, water and sediment.

[0011] Further configuration includes a sludge dewatering module connected to the bottom of the separation tower, used to separate the sludge and water pressed out of the separation tower to obtain dewatered sludge and separation liquid.

[0012] The further configuration includes a mud pool reheating module installed on the conveying pipeline between the separation tower and the mud dewatering module. The mud pool reheating module heats the foreign oil sludge in the oil storage mud pool by means of heat and mass exchange, using the heat of the mud and water pressed out by the separation tower.

[0013] Further configured as follows: the wet oxidation heat exchange reaction module includes a heat exchanger, a reactor and a static mixer, wherein the heat exchanger includes a first heat exchange pipeline for the flow of conditioned sludge and a second heat exchange pipeline for the flow of high-temperature sludge after wet oxidation, and the first heat exchange pipeline and the second heat exchange pipeline exchange heat to convert the conditioned sludge and the high-temperature sludge after wet oxidation into high-temperature sludge before wet oxidation and pressurized low-temperature sludge after wet oxidation, respectively. The reactor is connected in series between the outlet of the first heat exchange pipeline and the inlet of the second heat exchange pipeline. The static mixer is installed on the pipeline between the outlet of the first heat exchange pipeline and the reactor. The static mixer is used to add the oxidant required for the wet oxidation reaction to the high-temperature sludge before wet oxidation to obtain the high-temperature sludge before wet oxidation with added oxidant. The reactor is used to convert the high-temperature sludge before wet oxidation with added oxidant into high-temperature sludge after wet oxidation through a wet oxidation reaction.

[0014] The reactor is further configured to have a wet oxidation temperature of 160-230℃ and a pressure of 1.6-3.2MPa.

[0015] The further configuration is as follows: the conditioning water module includes a conditioning water storage tank and a first conditioning water pump. The conditioning water storage tank is used to mix and adjust the reclaimed water with the reagent to form conditioning water and store it. The first conditioning water pump is used to pump the conditioning water in the conditioning water storage tank to the conditioning delivery pump or a pipeline connected to the inlet of the conditioning delivery pump.

[0016] The conditioning water module is further configured such that a conditioning reheating unit is installed on the pipeline provided by the conditioning water storage tank to the conditioning delivery pump. The conditioning reheating unit heats the conditioning water by using the heat of the separated liquid separated by the sediment dewatering module through heat and mass exchange.

[0017] The further configuration includes a second conditioning water pump, which is used to pump the conditioning water from the conditioning water storage tank to the raw mud conveying pump or a pipeline connected to the inlet of the raw mud conveying pump.

[0018] The preprocessing and storage module is further configured to include a debris pool. The sorting and filtration unit includes a first-stage filtration unit and a second-stage filtration unit for sequentially filtering foreign oil sludge before it enters the oil sludge tank, as well as a third-stage backwashing filtration unit installed on the pipeline between the oil sludge tank and the oil sludge storage tank. The first-stage filter unit is a porous mesh structure or a plate / rod chain structure. The second-stage filtration unit is a structure that uses a motor to drive the filter screen to circulate, and during the circulation of the filter screen, the separated debris is transported to the debris pool; The third-stage backwashing filtration unit returns the separated debris to the second-stage filtration unit through backwashing.

[0019] Further configuration: The path along which the second-stage filtration unit conveys debris to the debris pool is constructed with an upwardly sloping ramp.

[0020] The sorting and filtering unit is further configured to include a rinsing unit disposed above the first-stage filtering unit and / or above the second-stage filtering unit.

[0021] Further configuration includes: a pressure control module for controlling system pressure, the pressure control module including a pressure control unit disposed at the top of the sludge storage tank, and / or disposed at the top of the separation tower, and / or disposed at the top of the separated crude oil storage tank; The pressure control unit includes a control valve and piping connected to the control valve, which controls the pressure by venting or injecting compressed air and / or the system's reaction gas.

[0022] A further configuration is provided: a first pressure control unit is provided at the top of the separation tower, and the pipeline of the first pressure control unit includes a first gas path for sending the gas discharged from the separation tower into the sludge storage tank.

[0023] The design further includes: a second pressure control unit is provided on the top of the crude oil separation tank, and a second gas passage for gas exchange between the first pressure control unit and the second pressure control unit is also constructed between them.

[0024] A further configuration is provided: a third pressure control unit is provided on the top of the sludge storage tank, and the pipeline of the third pressure control unit is used to send the gas discharged from the sludge storage tank into the third gas path of the conditioning water module.

[0025] The method is further configured such that: an oil-water interface level measurement sensor assembly is installed inside the separation tower, and the oil-water interface level measurement sensor assembly is used to measure and control the oil-water interface to ensure the separation performance, continuity and stability of the oil-water separation process.

[0026] The setting is further configured such that the heat energy of the process is used in the separation tower to keep the oil temperature above the "wall temperature" during the separation process.

[0027] The setting is further defined as follows: the "wall hanging temperature" is 40-80℃.

[0028] The present invention also provides a processing method for treating oily sludge using the above-described processing system.

[0029] Compared with the prior art, the present invention has the following beneficial effects: 1. High-efficiency separation: Synergistic effects of multiple mechanisms (oxidative demulsification, physical self-extraction, thermal viscosity reduction, and acid-induced polymerization) ensure thorough separation of oil, water, and sediment, resulting in high oil recovery. Simultaneously, the thermal energy of the process keeps the oil temperature above the "wall-hanging temperature," guaranteeing efficient and complete separation. 2. Extremely low energy consumption: The system efficiently recovers heat energy from the process, makes deep use of the heat of wet oxidation reaction and waste heat from the process, and makes full use of the pressure energy of the process. The system can achieve energy self-sufficiency or near self-sufficiency, significantly reducing external energy consumption. 3. High degree of resource utilization: While achieving a high oil recovery rate, the quality of the recovered oil is improved and it can be reused; water and sediment are effectively separated, facilitating subsequent treatment or disposal. 4. Waste-to-waste treatment: The CO2 and acidic substances produced by wet oxidation are transformed from a "processing burden" into "separated resources," realizing the recycling of materials and utilization of waste within the process, and reducing the amount of chemical reagents added and secondary pollution; 5. Stable operation: Through multi-stage separation, adjustment of the ratio of oil sludge to water (oil sludge conditioning), and control of system temperature and pressure, especially by utilizing process heat energy recovery to reduce the impact of external oil sludge differences and environmental climate changes, it can operate normally even in the cold season; the process heat energy is used to ensure that the oil temperature is above the "wall adhesion temperature", and the separation performance, continuity and stability of the separation process are guaranteed by automatically controlling the oil-water interface. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the principle structure of an oily sludge treatment system according to the present invention; Figure 2 This is a schematic diagram illustrating the structural principle of the preprocessing and storage module of the present invention; Figure 3 This is a schematic diagram of the structural principle of the wet oxidation heat exchange reaction module of the present invention; Figure 4 This is a schematic diagram of the structure of the self-airlift sedimentation separation module of the present invention; Figure 5 This is a schematic diagram illustrating the structural principle of the sediment dewatering module of the present invention; Figure 6 This is a schematic diagram illustrating the structural principle of the conditioning water module of the present invention; Figure 7 This is a schematic flowchart of the oily sludge treatment method of the present invention.

[0031] The following reference numerals are marked on the accompanying drawings: 1. Pretreatment and storage module; 11. Oil sludge storage tank; 12. Sorting and filtration unit; 121. First-stage filtration unit; 122. Second-stage filtration unit; 123. Third-stage backwashing filtration unit; 124. Flushing unit; 13. Debris tank; 14. Oil sludge storage tank; 2. Wet oxidation heat exchange reaction module; 21. Heat exchanger; 211. First heat exchange pipeline; 212. Second heat exchange pipeline; 22. Reactor; 221. Reaction pipeline; 23. Static mixer; 24. Oxygen supply unit; 25. Heating unit; 3. Conditioning water module; 31. Conditioning water storage tank; 32. First conditioning water pump; 33. Second conditioning water pump; 34. Conditioning and regeneration unit; 35. Chemical dosing unit; 4. Oil sludge pumping module; 41. Raw sludge conveying pump; 42. Conditioning and conveying pump; 5. Self-lifting sedimentation separation module; 51. Separation tower; 52. Separated crude oil storage tank; 6. Sediment dewatering module; 61. Sediment dewatering machine; 62. Dewatered sediment storage unit; 63. Separated liquid storage unit; 64. Separated liquid transfer pump; 7. Mud pool reheating module; 8. Pressure control module; 81. First pressure control unit; 82. Second pressure control unit; 83. Third pressure control unit; 84. First air path; 85. Second air path; 86. Third air path; 9. Separation liquid treatment module; OSW, imported sludge; S1, pretreated sludge; S2, conditioned sludge; S3, high-temperature sludge before wet oxidation; S4, high-temperature sludge before wet oxidation with added oxidant; S5, high-temperature sludge after wet oxidation; S6, low-temperature sludge under pressure after wet oxidation; S7, sludge after wet oxidation; S8, oil. W1, greywater; W2, low-temperature conditioning water; W3, high-temperature conditioning water; W4, high-temperature separation liquid; W5, low-temperature separation liquid; W6, reagents; G1, oxygen-enriched compressed air or high-concentration oxygen; G2, post-oxidation reaction gas; G3, gas generated by the separation tower; G4, gas generated by the crude oil storage tank; G5, mixed reaction gas; TE1: Heat exchanger recovers process heat energy; TE2: Utilizes process heat energy to make the temperature of the sludge after wet oxidation higher than the "wall temperature"; TE3: Sludge pool reheating module reheats; TE4: Conditioning reheating unit heats conditioning water; TE5: Waste heat from reaction gas heats sludge; TE6: Waste heat from reaction gas heats conditioning water. Detailed Implementation

[0032] The following detailed description of a specific embodiment of the present invention is provided in conjunction with the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0033] This invention provides a system for treating oily sludge, such as... Figure 1As shown, the system includes a pretreatment and storage module 1, a wet oxidation heat exchange reaction module 2, a conditioning water module 3, an oil sludge pumping module 4, a self-lift sedimentation separation module 5, a sludge dewatering module 6, a sludge pool reheating module 7, a pressure control module 8, and a separation liquid treatment module 9. The pretreatment and storage module 1 is used to pretreat imported oil sludge (OSW) by filtering out most impurities to obtain pretreated oil sludge (S1). The wet oxidation heat exchange reaction module 2 is used to perform a wet oxidation reaction and heat exchange between the oil sludge and the oxidant to achieve oxidative modification and demulsification of the oil sludge. The conditioning water module 3 is used to provide conditioning water to the treatment system. To improve the fluidity and anti-fouling properties of oil sludge; the oil sludge pumping module 4 is used to drive the oil sludge to flow within the treatment system; the self-lift sedimentation separation module 5 is used to achieve three-phase separation of oil droplets, water, and sediment in the oil sludge; the sediment dewatering module 6 is used to perform solid-liquid separation on the separated sediment (oil sludge S7 after wet oxidation); the sludge pool reheating module 7 is used to utilize the residual heat from the water and sediment pressed out by the self-lift sedimentation separation module 5 to heat the temperature of the external oil sludge OSW in the pretreatment and storage module 1; the pressure control module 8 is used to control the pressure of each module within the system; and the separation liquid treatment module 9 is used to treat the separation liquid generated during dewatering.

[0034] In this embodiment, as Figure 2 As shown, the pretreatment and storage module 1 includes an oil sludge storage tank 11, a sorting and filtering unit 12, a debris tank 13, and an oil sludge storage tank 14; wherein, the oil sludge storage tank 11 is used to temporarily store imported oil sludge OSW, the sorting and filtering unit 12 is used to filter and remove most of the debris in the imported oil sludge OSW, and the oil sludge storage tank 14 is used to store the pretreated oil sludge S1 after pretreatment.

[0035] Specifically, the sorting and filtering unit 12 includes a first-stage filtration unit 121 and a second-stage filtration unit 122 for sequentially filtering incoming oil sludge (OSW) entering the oil sludge storage tank 11, and a third-stage backwashing filtration unit 123 installed on the pipeline between the oil sludge storage tank 11 and the oil sludge storage tank 14. The first-stage filtration unit 121 is located at the top or adjacent area of ​​the oil sludge storage tank 11 and has a porous mesh structure or a plate / rod chain structure for removing large-diameter impurities. The second-stage filtration unit 122 is located below or on the lower side of the first-stage filtration unit 121 and is used to receive the oil sludge filtered by the first-stage filtration unit 121 and continue filtering it. The second-stage filtration unit 122 is driven by a motor. The structure includes a rotating filter screen that circulates and conveys the separated medium-sized impurities to a debris pool 13. The debris pool 13 is located on one side of the oil sludge storage pool 11 and above the second filter unit. The filter screen of the second filter unit is constructed with an inclined slope extending upward toward the debris pool 13, which reduces the amount of water and oil in the oil sludge entering the debris pool 13. Furthermore, the sorting filter unit 12 also includes a rinsing unit 124 located above the first-stage filter unit 121 and / or the second-stage filter unit 122. Preferably, both the first-stage and second-stage filter units 122 are equipped with rinsing units 124. In this way, cleaning the filter units can minimize the amount of sludge and oil phase in the debris and improve the oil phase recovery rate.

[0036] In this embodiment, the sludge pumping module 4 includes a raw sludge conveying pump 41 installed on the pipeline between the sludge storage tank 11 and the sludge storage tank 14, and a conditioning conveying pump 42 installed on the pipeline between the wet oxidation heat exchange reaction modules 2. The raw sludge conveying pump 41 is used to pump the sludge from the sludge storage tank 11 into the raw sludge storage tank for storage. The raw sludge conveying pump 41 is preferably a plunger pump or a screw pump. The conditioning conveying pump 42 is used to mix the pretreated sludge S1 in the sludge storage tank 14 with the conditioning water from the conditioning water module 3 to form conditioned sludge S2. By injecting a certain proportion of conditioning water into the pretreated sludge S1, the power consumption of the conditioning sludge S2 conveying pump and the energy consumption of the subsequent wet oxidation treatment of the sludge can be reduced. This is because the solids content of imported oily sludge (OSW) is generally around 20%-50% (moisture content around 80%-50%). This high solids content of oily sludge has poor fluidity, making pumping difficult. A certain amount of water needs to be added to reduce the solids content and viscosity of the sludge. However, the amount of water added should not be too much. If the moisture content of the oily sludge to be treated is too high, although the viscosity can be significantly reduced, the energy consumption for transportation will also increase. In particular, it will significantly increase the heating energy consumption and dehydration energy consumption of the oily sludge treatment. Generally, the solids content of the oily sludge entering the heat exchanger 21 should be controlled between 15% and 5%, with a preferred range of 12% to 8%. The specific range should be adjusted according to the original solids content and the proportion of organic matter in the imported oily sludge (OSW).

[0037] The imported sludge OSW, after having most of its impurities removed, is transported to the third-stage backwash filter unit 123 for further filtration via the raw sludge transfer pump 41 installed at the bottom of the sludge storage tank 11. Simultaneously, the separated small-diameter impurities are returned to the second-stage sorting filter unit 12 via backwashing and then transported to the impurity tank 13. The pretreated sludge S1 after filtration by the third-stage backwash filter unit is then pumped to the sludge storage tank 14 for storage. The imported sludge OSW passes through the first-stage filter unit 121, the second-stage filter unit 122, and the third-stage backwash filter unit 123 in sequence. Through three stages of filtration and gradually reducing the pore size, large-diameter impurities, medium-diameter particles, and fine impurities are removed in sequence to become the pretreated sludge S1.

[0038] The pretreated sludge S1 enters from the lower middle part of the sludge storage tank 14 under the pumping of the raw sludge conveying pump 41. The sludge storage tank 14 maintains a pressure within a certain range, generally 0~1.2MPa, preferably 0.1~0.3MPa, so as to transport the pretreated sludge S1 in the sludge storage tank 14 to the wet oxidation heat exchange reaction module 2 under pressure drive. The pressure control module 8 includes a third pressure control unit 83 set at the top of the sludge storage tank 14 to control the pressure in the sludge storage tank 14. The third pressure control unit 83 includes a control valve and a pipeline connected to the control valve. The third pressure control unit 83 monitors the pressure in the sludge storage tank 14 through a pressure sensor and ensures that the pressure in the sludge storage tank 14 is maintained within the set range by venting or injecting compressed air and / or the system's reaction gas. The system's reaction gas includes oxidation reaction gas G2, separation tower generation gas G3, and crude oil storage tank generation gas G4.

[0039] In this embodiment, as Figure 1 As shown, the wet oxidation heat exchange reaction module 2 is connected to the sludge storage tank 14 and is used to carry out wet oxidation reaction and heat exchange between the conditioned sludge S2 and the oxidant, so as to realize the wet oxidation modification and demulsification of the conditioned sludge S2, and generate pressurized low-temperature sludge S6 after wet oxidation. The pressurized low-temperature sludge S6 after wet oxidation carries the oxidation reaction gas G2 containing carbon dioxide.

[0040] Specifically, such as Figure 3As shown, the wet oxidation heat exchange reaction module 2 includes a heat exchanger 21, a reactor 22, an oxygen supply unit 24, and a static mixer 23. The heat exchanger 21 includes a first heat exchange pipe 211 and a second heat exchange pipe 212. The reactor 22 is connected in series between the outlet of the first heat exchange pipe 211 and the inlet of the second heat exchange pipe 212. The static mixer 23 is located on the pipe between the outlet of the first heat exchange pipe 211 and the reactor 22. The oxygen supply unit 24 is connected to the static mixer 23 through a pipe. Thus, the low-temperature conditioning sludge S2 is pumped into the first heat exchange pipe 211 and the second heat exchange pipe 212 in the heat exchanger 21 by the conditioning transfer pump 42 and flows from the reactor 22. The high-temperature sludge S5, which flows in after wet oxidation, undergoes heat exchange. The heat exchange between the high- and low-temperature sludge is set as countercurrent heat exchange, resulting in a smaller logarithmic heat exchange temperature difference and more efficient heat exchange. Therefore, the low-temperature conditioned sludge S2 is heated to form the high-temperature sludge S3 before wet oxidation, and the high-temperature sludge S5 after wet oxidation is cooled to become the pressurized low-temperature sludge S6 after wet oxidation. This heat exchanger 21 can realize a self-heating process, i.e., sludge-to-sludge heat exchange, thereby maximizing the recovery of process heat energy. In some cases, it can even achieve process self-sustainability, significantly reducing the energy consumption of the wet oxidation treatment system for oily sludge and significantly improving its energy-saving economic benefits. The operating cost of the wet oxidation treatment of oily sludge is extremely low. The heat exchanger recovers the process heat energy TE1, which is the first point of the waste heat utilization in the process of this invention. Several mixing swirl structures are installed in the first heat exchange pipe 211 of the heat exchanger 21 to facilitate the full mixing and conditioning of the conditioned sludge S2, thereby improving its fluidity and enhancing the heat exchange process. Several mixing swirl structures are installed in the second heat exchange pipe 212 of the heat exchanger 21 to facilitate the full mixing and homogenization of the sludge after the wet oxidation reaction with the reaction gas, thereby avoiding problems such as plug flow, stratified flow, local deposition and large pressure fluctuations in the three-phase gas-liquid-solid flow.

[0041] The static mixer 23 is used to add the oxidant required for the wet oxidation reaction to the high-temperature sludge S3 before wet oxidation to obtain high-temperature sludge S4 before wet oxidation with added oxidant. The oxygen supply unit 24 is used to provide oxygen-enriched air or pure oxygen as an oxidant. In this way, the high-temperature sludge S4 before wet oxidation can be mixed with oxygen-enriched compressed air or high-concentration oxygen G1 through the static mixer 23 to form high-temperature sludge S4 before wet oxidation with added oxidant, and then enters the reactor 22 for wet oxidation reaction to form high-temperature sludge S5 after wet oxidation. Several mixing swirl structures are set in the reaction pipeline 221 of the reactor 22 to facilitate the full mixing and conditioning of sludge and oxidant (oxygen-enriched compressed air or high-concentration oxygen G1) and enhance the reaction process. The reactor 22 is also equipped with a heating unit 25 to further increase the sludge temperature, thereby controlling the temperature of the wet oxidation reaction.

[0042] In this embodiment, the wet oxidation temperature in reactor 22 is 160-230℃, and the pressure is 1.6-3.2MPa. Under these low-to-medium wet oxidation temperature and pressure parameters, some organic matter is oxidized and modified, achieving demulsification of the three phases of oil, water, and sludge. Simultaneously, under these wet oxidation conditions, impurities such as sulfur, phosphorus, and heavy metals in the oil may be oxidized, reducing toxicity and improving oil quality. The multiple effects of the aforementioned wet oxidation efficiently achieve demulsification of oily sludge and oil modification. In reactor 22, while the oily sludge is demulsifying, some organic matter is oxidized to small-molecule organic matter, carbon dioxide, and water, releasing heat of reaction. The high-temperature oily sludge S5 after wet oxidation flows into the second heat exchange pipe 212 of heat exchanger 21, where it exchanges heat with the low-temperature conditioned oily sludge S2 in the first heat exchange pipe 211 for cooling, subsequently becoming pressurized low-temperature oily sludge S6 after wet oxidation. This is the heat energy TE1 recovered by the heat exchanger during the process. The pressurized low-temperature sludge S6 after wet oxidation is then transported into the sludge self-airlift sedimentation separation module 5.

[0043] In this embodiment, the oil sludge self-lift sedimentation separation module 5 is connected to the wet oxidation heat exchange reaction module 2, including a separation tower 51 and a crude oil separation storage tank 52. The function of the separation tower 51 is to receive pressurized low-temperature oil sludge S6 after wet oxidation and reaction gas G2 after oxidation, and to achieve three-phase separation of oil, water, and solid (mud and sand containing a small amount of oil) through the action of self-lift-gravity sedimentation. The crude oil separation storage tank 52 is used to receive and store the oil liquid S8 separated by the separation tower 51.

[0044] After wet oxidation, pressurized low-temperature sludge S6 enters the separation tower 51 from the lower middle part. Due to its low density, the oil phase floats upward under the action of buoyancy; due to its higher density, the sludge settles downward under the action of gravity. The sludge and water are squeezed out from the bottom of the tower and then transported to the sludge dewatering module 6 under the action of pressure energy to achieve the separation of water and sludge. Meanwhile, the post-oxidation reaction gas G2 includes some incompletely oxidized residual oxygen, nitrogen introduced with the oxygen, and gases such as carbon dioxide produced by the reaction. In particular, carbon dioxide gas has the effect of accelerating demulsification and oil droplet accumulation (referred to as carbon dioxide demulsification and oil polymerization promotion). Under the action of the above gases, that is, under the action of self-gas lifting, the oil phase is accelerated to float upward, and the gas that floats to the top of the separation tower 51 constitutes the separation tower generation gas G3. In addition, the carbon dioxide and small molecule acidic substances produced by wet oxidation make the oil, water and silt mixture after wet oxidation treatment an acidic environment (pH about 3-5), which is conducive to demulsification and oil-water separation. In addition, the reaction heat generated during the wet oxidation reaction raises the temperature of the oil, water and silt mixture in the separation tower 51 (above room temperature), which can reach above the wall temperature, which is conducive to demulsification and oil-water separation. Thus, efficient separation of oil, water and silt is achieved in the separation tower 51.

[0045] In particular, the carbon dioxide (CO2) produced during the wet oxidation reaction also has the functions of demulsification and promoting oil accumulation: CO2 dissolves in water to form carbonic acid, which lowers the pH value, neutralizes the surface charge of oil droplets, and promotes oil droplet polymerization; at the same time, the reaction gas (including carbon dioxide) produced during the wet oxidation reaction is dispersed in the oil sludge after the wet oxidation reaction in the form of bubbles (especially microbubbles). The reaction gas bubbles are dispersed in the pressurized low-temperature oil sludge S6 after wet oxidation in the separation tower 51. The reaction gas bubbles attach to the oil droplets (especially due to the polar bonds of carbon dioxide in the reaction gas), which can increase buoyancy and accelerate the floating, thereby significantly enhancing the separation effect of oil phase from water and silt, and achieving efficient separation of oil, water and silt.

[0046] Separation tower 51 is equipped with an oil-water interface level measurement sensor assembly. During the process, the oil-water interface level is monitored by the oil-water interface level measurement sensor assembly to measure and control the level of the oil and water interface, ensuring the separation effect, stability, and reliability of oil-water separation. The pressure of separation tower 51 is maintained within a certain range, such as 1.0~2.0MPa. The pressure of the crude oil storage tank 52 is slightly lower than that of the separation tower 51, and the pressure difference between the two is preferably controlled to be ≤0.3MPa. Utilizing this pressure difference and precise valve control, the oil S8 separated in the separation tower 51 can be easily transported to the crude oil storage tank 52 for temporary storage to facilitate subsequent external transportation and resource utilization. The gas rising to the top of the crude oil storage tank 52 constitutes the crude oil storage tank generating gas G4. Specifically, the pressure control module 8 includes a first pressure control unit 81 located at the top of the separation tower 51 and a second pressure control unit 82 located at the top of the crude oil sludge storage tank. Both the first and second pressure control units 81 and 82 include control valves and pipelines connected to the control valves. By venting or injecting compressed air and / or the system's reaction gas, the pressure of the separation tower 51 and the crude oil sludge storage tank is maintained within a set range. Specifically, the pipeline of the first pressure control unit 81 includes a channel for the gas discharged from the separation tower 51 through the lower part of the sludge storage tank 14. A first gas passage 84 is provided, and a second gas passage 85 is constructed between the first pressure control unit 81 and the second pressure control unit 82 for gas exchange between the separation tower 51 and the crude oil storage tank 52. Thus, the mixed reaction gas G5, composed of the separation tower generator gas G3 and / or the generator gas from the crude oil storage tank, can be sent to the sludge storage tank 14 through the first gas passage 84. The mixed reaction gas G5 provides pressure energy to the sludge storage tank 14, and the exhaust / intake of the third pressure control unit 83 at the top of the sludge storage tank 14, through the synergistic effect of the intake and exhaust, maintains a certain pressure in the sludge storage tank 14 so that the sludge can be transported to the wet oxidation heat exchange reaction module 2 using this pressure energy. At the same time, the CO2 in the mixed reaction gas G5 dissolves to form carbonic acid, which lowers the pH in the tank to 3~5.5, inhibiting carbonate scaling. Furthermore, the sludge storage tank 14 also absorbs the waste heat of the reaction gas for further energy saving. This allows the sludge to obtain better anti-scaling performance and demulsification effect. This is the waste heat of the reaction gas heating the sludge TE5.

[0047] In an embodiment, such as Figure 1 and Figure 4As shown, the separation tower 51 and / or connected pipelines and equipment are equipped with oil temperature sensors to measure and control the temperature inside the separation tower 51 to maintain a temperature higher than the crude oil's "wall-hanging temperature" (i.e., the temperature at which the oil does not adhere to the equipment wall, generally around 40-80°C). This not only helps reduce viscosity and promote oil droplet aggregation and separation, but more importantly, it prevents oil from adhering to or even clogging the equipment and pipelines. The temperature inside the separation tower 51 is higher than the temperature of the external oily sludge. Its heat comes from the reaction heat generated by the wet oxidation reaction, the supplementary heat from the process, and the reheat from the process. Utilizing process heat energy to ensure that the temperature of the sludge after wet oxidation is higher than the "wall-hanging temperature" TE2 is the second point of waste heat utilization in the process of this invention. It is particularly important to emphasize that the temperature inside the separation tower 51 being higher than the crude oil's "wall-hanging temperature" is crucial; otherwise, separation cannot proceed or the separation effect will be difficult to meet requirements.

[0048] The lower part of the separation tower 51 is equipped with a discharge port, which discharges a mixture of hot water with a relatively high water content and a small amount of mud and oil when needed (which can be returned to the system for demulsification and separation again) to reduce the water content of the oil S8 discharged from the top and further improve the quality of the separated crude oil.

[0049] In this embodiment, the separation tower 51 uses its internal pressure to press out the sludge (mainly wet-oxidized sludge S7) separated at the bottom and transport it to the sludge dewatering module 6 for dewatering. The sludge pool reheating module 7 is installed on the conveying pipeline between the separation tower 51 and the sludge dewatering module 6. On the one hand, it recovers the wet-oxidized sludge S7 (waste heat from the wet oxidation reaction process) pressed out by the separation tower 51 to heat the external sludge OSW in the sludge storage pool 11. On the other hand, it controls the temperature of the separated sludge to facilitate its entry into the sludge dewatering module 6. The sludge temperature meets the process requirements. This not only effectively reduces the feed temperature into the sludge dewatering module 6, improving its service life, but more importantly, it recovers waste heat from the process to heat the external oily sludge (OSW), increasing its temperature in the oily sludge storage tank 11. This helps reduce the viscosity of the external oily sludge, thereby improving its transport characteristics. Simultaneously, it increases the feed temperature of the wet oxidation heat exchange reaction module 2, avoiding heat waste, reducing supplementary heating energy consumption, and achieving deep heat recovery and energy saving. This is the third point of the invention's deep utilization of process waste heat: using the sludge tank reheating module TE3 to reheat the external oily sludge in the oily sludge storage tank 11 increases the temperature of the external oily sludge (OSW).

[0050] Based on process requirements, the mud tank reheating module 7 has three heating and reheating methods: 1) Intermediate medium heat exchange method: An intermediate medium heat exchanger 21 is provided. In the intermediate medium heat exchanger 21, the relatively high-temperature wet-oxidized sludge S7 pressed out from the bottom of the separation tower 51 continues to exchange heat with the intermediate medium (water W1) circulated by the pump. The intermediate medium (water W1) then continues to exchange heat with the heat exchanger 21 set in the oil sludge storage tank 11 - the pipeline regenerative heat exchanger 21. The waste heat (heat) of the process is transferred to the external oil sludge OSW in the oil sludge storage tank 11 through the indirect heat exchange. The external oil sludge OSW inside and outside the oil sludge storage tank 11 is heated, realizing the utilization of the waste heat of the process.

[0051] 2) Direct heat exchange and regeneration method is set in the oil sludge storage tank 11: A pipeline regeneration heat exchanger 21 is set in the oil sludge storage tank 11. The relatively high temperature wet oxidation oil sludge S7 pressed out from the bottom of the separation tower 51 is cooled by the pipeline regeneration heat exchanger 21 in the oil sludge storage tank 11 before being transported to the sludge dewatering module 6 for dewatering. At the same time, the oil sludge OSW coming from inside and outside the oil sludge storage tank 11 is heated, so that the waste heat in the process can be utilized.

[0052] 3) Direct heat exchange and recuperation method is set outside the oil sludge tank 11: A direct heat exchange and recuperation device is set outside the oil sludge tank 11. The oil sludge OSW from inside and outside the oil sludge tank 11 is pumped to the direct heat exchange and recuperation device to be heated and then returned to the oil sludge tank 11. It exchanges heat with the relatively high-temperature wet-oxidized oil sludge S7 pressed out from the bottom of the separation tower 51. After the wet-oxidized oil sludge S7 is cooled down, it is transported to the sludge dewatering module 6 for dewatering. At the same time, the oil sludge OSW from inside and outside the oil sludge tank 11 is heated, so that the waste heat in the process is utilized.

[0053] like Figure 1 and Figure 5 As shown, the sludge dewatering module 6 includes a sludge dewatering machine 61, a dewatered sludge storage unit 62, a separation liquid storage unit 63, and a separation liquid transfer pump 64. After being cooled by the sludge pool reheating module 7, the wet oxidation reaction sludge S7 enters the sludge dewatering machine 61 for solid-liquid separation. The sludge products generated by the separation enter the dewatered sludge storage unit 62 for storage. The high-temperature separation liquid W4 generated during the dewatering process enters the separation liquid storage unit 63 for storage. The separation liquid transfer pump 64 is used to transport the high-temperature separation liquid W4 in the separation liquid storage unit 63 to the separation liquid treatment module 9 for treatment to meet discharge standards or for reuse. To ensure that the temperature of the high-temperature separation liquid W4 entering the separation liquid treatment module 9 is suitable for biochemical treatment, the high-temperature separation liquid W4 needs to be cooled by heat exchange with the low-temperature conditioning water W2 from the conditioning water storage tank 31 through the conditioning and reheating unit 34. The heating of the conditioning water TE4 by the conditioning and reheating unit is the fourth point of waste heat utilization in the process of this invention.

[0054] like Figure 1 and Figure 6As shown, the conditioning water module 3 includes a conditioning water storage tank 31, a dosing unit 35, a first conditioning water pump 32, a conditioning reheating unit 34 (regenerator), and a second conditioning water pump 33. The conditioning water storage tank 31 is used to store conditioning water and to mix reclaimed water W1 and chemicals W6 within the tank. Reclaimed water W1 is injected through an interface in the middle of the conditioning water storage tank 31 to replenish the required conditioning water. The dosing unit 35 adds chemicals W6 (such as scale inhibitors, demulsifiers, and / or catalysts) to the conditioning water storage tank 31 to achieve the corresponding scale inhibition, demulsification, and / or catalytic effects. The first conditioning water pump 32 transports low-temperature conditioning water W2 to the conditioning transfer pump 42, which then heats the water via the conditioning reheating unit 34 to form high-temperature conditioning water W3. The conditioning and reheating unit 34 is used to exchange heat between the low-temperature conditioning water W2 and the high-temperature separated liquid W4 to form high-temperature conditioning water W3 and low-temperature separated liquid W5 respectively; thereby increasing the temperature of the conditioning water entering the conditioning transfer pump 42 and reducing the temperature of the separated liquid entering the separated liquid storage and treatment unit, which facilitates biochemical treatment; the second conditioning water pump 33 is used to transport the conditioning water to the raw sludge transfer pump 41 or the pipeline at the inlet of the raw sludge transfer pump 41 to improve the flow of oil sludge.

[0055] In this embodiment, the pipeline of the third pressure control unit 83 at the top of the sludge storage tank 14 also includes a third gas path 86 for sending the gas discharged from the sludge storage tank 14 into the conditioning water module 3; thus, excess mixed reaction gas G5 in the sludge storage tank 14 can be introduced into the conditioning water storage tank 31 through the third gas path 86, which can not only absorb and treat harmful pollutants in the gas, but also recover the waste heat of the reaction gas, further saving energy. This is the waste heat utilization of the reaction gas in this invention to heat the conditioning water TE6, and absorb part of CO2 to improve anti-scaling performance and oil phase separation effect. The initial system pressure can be established by injecting air into the sludge storage tank 14 and the separation tower 51 through an air compressor.

[0056] This invention also provides a method for treating oily sludge, such as... Figure 7 As shown, the oily sludge is treated by the above-mentioned treatment system, including the following steps: Step 1: Imported oil sludge is sorted and filtered to form pretreated oil sludge. The imported oil sludge OSW is first sorted and filtered through the first-stage filtration unit 121 and the second-stage filtration unit 122 to remove most of the impurities. Then it is transported to the third-stage backwash filtration unit 123 by the raw sludge transfer pump 41 for further filtration, thereby obtaining pre-treated oil sludge S1 with smaller particle size after filtration, and stored in the oil sludge storage tank 14.

[0057] The reaction gas generated in the subsequent wet oxidation reaction comes from the top of the separation tower 51 and the crude oil storage tank 52 and enters the sludge storage tank 14. The waste heat (TE5) of the reaction gas is recovered, and some of the carbon dioxide and organic matter in the reaction gas are also recovered. This achieves energy-saving effect while giving the sludge better anti-fouling performance and demulsification effect.

[0058] Step 2: Pre-treated sludge is mixed with high-temperature conditioning water to form conditioning sludge. Pretreated sludge S1 from sludge storage tank 14 is initially mixed with high-temperature conditioning water W3 from conditioning water storage tank 31 by conditioning transfer pump 42 to obtain conditioning sludge S2.

[0059] Step 3: The conditioned sludge undergoes heat exchange and temperature rise in a heat exchanger. The low-temperature conditioned sludge S2 and the high-temperature sludge S5 after wet oxidation flowing out of the reactor 22 are exchanged through heat exchanger 21. The low-temperature conditioned sludge S2 is heated to form high-temperature sludge S3 before wet oxidation, and the high-temperature sludge S5 after wet oxidation is cooled to form pressurized low-temperature sludge S6 after wet oxidation. In heat exchanger 21, the low-temperature conditioned sludge S2 recovers the process heat energy of the high-temperature sludge S5 after wet oxidation, that is, the heat exchanger recovers the process heat energy TE1, so as to achieve a significant energy saving effect.

[0060] Step 4: Add the oxidant for wet oxidation. The high-temperature sludge S3 before wet oxidation is mixed with an oxidant through a static mixer 23 to form a high-temperature sludge S4 before wet oxidation with added oxidant, wherein the oxidant is usually oxygen-enriched compressed air or high-concentration oxygen G1.

[0061] Step 5: The sludge reacts in the reactor. The high-temperature oil sludge S4 before wet oxidation with added oxidant is subjected to wet oxidation reaction in reactor 22 to obtain high-temperature oil sludge S5 after wet oxidation. The intermediate oxidation temperature of reactor 22 is 160-230℃ and the pressure is 1.6-3.2MPa. Under these wet oxidation temperature and pressure parameters, some organic matter is oxidized and modified, and the demulsification of the three phases of oil, water and sludge is achieved.

[0062] Step Six: Cooling the Reaction Sludge After wet oxidation, the high-temperature sludge S5 flows into the second heat exchange pipe 212 of the heat exchanger 21 and exchanges heat with the low-temperature conditioned sludge S2 in the first heat exchange pipe 211 to cool down, so as to transform it into pressurized low-temperature sludge S6 after wet oxidation.

[0063] Step 7: Three-phase separation of oil sludge in the separation tower After wet oxidation, pressurized low-temperature sludge S6 (carrying the reaction gas formed during the wet oxidation process) enters the separation tower 51 for storage. Due to its high density, the sludge settles downward under the action of gravity to obtain wet-oxidized sludge S7. The reaction gas is released upward under the action of buoyancy. That is, under the action of self-gas lifting, the oil is accelerated to float upward, thereby achieving efficient separation of oil, water and sludge in the separation tower 51. As a result, the three phases can easily form a layered structure of upper oil-middle water-lower sludge in the tower.

[0064] The temperature inside the separation tower 51 is higher than the temperature of the incoming oily sludge. Its heat comes from the reaction heat generated by the wet oxidation reaction, the heat supplementation of the process, and the heat recovery of the process. The process heat energy is used to make the temperature of the oily sludge after wet oxidation higher than the "wall temperature" TE2.

[0065] Step 8: Oil-water separation By utilizing the pressure difference between the separation tower 51 and the crude oil separation tank 52, the upper floating oil S8 is pressure-transported into the crude oil separation tank 52 unit.

[0066] Step Nine: Dewatering of Sediment After wet oxidation, the oil sludge S7 is transported to the sludge dewatering module 6 by the pressure energy of the gas stored in the separation tower 51 for solid-liquid separation. The separated high-temperature liquid W4 is stored in the liquid storage unit 63.

[0067] Step 10: Conditioning of greywater The reaction gas from the sludge storage tank 14 is introduced into the conditioning water storage tank 31 for absorption treatment. Some carbon dioxide and harmful organic matter are absorbed by the greywater W1, and some of the waste heat of the reaction gas is recovered. This waste heat of the reaction gas heats the conditioning greywater ET6, further recovering waste heat and saving energy while improving anti-scaling performance and oil phase separation effect. The remaining reaction gas is treated to meet the discharge standards or is discharged directly to meet the standards. The greywater W1 and the agent W6 (such as scale inhibitor, and / or demulsifier, and / or catalyst, etc.) from the dosing unit are mixed to form conditioning water and supplied to the conditioning transfer pump 42 through the first conditioning water pump 32. It is mixed with the pretreated sludge S1 to form conditioning sludge S2, realizing the conditioning of oily sludge.

[0068] Step 11: Heat recovery and treatment of the separated liquid The high-temperature separated liquid W4 in the separated liquid storage unit 63 is pumped to the conditioning and reheating unit 34, where it exchanges heat with the low-temperature conditioning water W2 on the other side to form a low-temperature separated liquid W5, which is stored in the separated liquid treatment module 9. Then it is discharged for treatment or treated by a wastewater treatment unit before being discharged. During this process, the low-temperature conditioning water W2 in the conditioning and reheating unit 34 recovers the residual heat of the high-temperature separated liquid W4, that is, the conditioning and reheating unit heats the conditioning water ET4.

[0069] Step 12: Heat recovery in the oil sludge storage tank The residual heat of the wet-oxidized sludge S7 is transferred to the external sludge OSW in the sludge storage tank 11 through the sludge pool reheat module 7. This is the sludge pool reheat module ET3, which increases the temperature of the external sludge OSW, reduces the viscosity of the external sludge OSW, and improves the transport characteristics. At the same time, it can save energy consumption for heating the external sludge OSW. It can even achieve reaction self-sustaining or extremely low energy consumption in conjunction with the wet oxidation heat exchanger 21. Even in the cold season, it can maintain the temperature of the external sludge OSW within a reasonable range, so that it can operate normally in the cold season in the north, especially in winter.

[0070] The above-disclosed embodiments are merely examples of the present invention. However, the present invention is not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A system for treating oily sludge, characterized in that, include: The pretreatment and storage module includes an oil sludge storage tank, a sorting and filtering unit, and an oil sludge storage tank. The oil sludge storage tank is used to temporarily store foreign oil sludge, the sorting and filtering unit is used to remove impurities from the foreign oil sludge, and the oil sludge storage tank is used to store pretreated oil sludge. The wet oxidation heat exchange reaction module is used to perform wet oxidation reaction and heat exchange between conditioned sludge and oxidant to generate pressurized low-temperature sludge after wet oxidation, thereby achieving oxidative modification and demulsification of the sludge, and generating reaction gas containing carbon dioxide. Conditioning water module, which is used to provide conditioning water to the system; The sludge pumping module, which provides the power for the flow of sludge within the system, includes a raw sludge transfer pump installed on the pipeline between the sludge storage tank and the sludge storage tank, and a conditioning transfer pump installed on the pipeline between the sludge storage tank and the oxidation heat exchange reaction module. The conditioning transfer pump is used to mix the conditioning water provided by the conditioning water module with the pretreated sludge to generate conditioning sludge. The self-gas-lift sedimentation separation module includes a separation tower and a crude oil separation storage tank. The separation tower is used to receive pressurized low-temperature sludge and reaction gas after wet oxidation and to perform three-phase separation of oil, water and sediment within it. The crude oil separation storage tank is used to store the oil separated by the separation tower. In the three-phase separation process, the reaction gas in the separation tower is dissolved in water or dispersed in the liquid phase in the form of bubbles. The reaction gas bubbles can adhere to the oil droplets to accelerate the oil phase to float and separate. The carbon dioxide in the gas can dissolve in water to generate carbonic acid to form an acidic environment to promote the aggregation of oil droplets, thereby achieving efficient separation of oil, water and sediment.

2. The oily sludge treatment system according to claim 1, characterized in that, It also includes a sludge dewatering module, which is connected to the bottom of the separation tower and is used to separate the sludge and water pressed out of the separation tower to obtain dewatered sludge and separation liquid.

3. The oily sludge treatment system according to claim 2, characterized in that, It also includes a mud pool reheating module installed on the conveying pipeline between the separation tower and the mud and sand dewatering module. The mud pool reheating module heats the foreign oil sludge in the oil storage mud pool by using the heat of the mud and sand and water pressed out by the separation tower through heat and mass exchange.

4. The oily sludge treatment system according to claim 1, characterized in that, The wet oxidation heat exchange reaction module includes a heat exchanger, a reactor, and a static mixer. The heat exchanger includes a first heat exchange pipeline for the flow of conditioned sludge and a second heat exchange pipeline for the flow of high-temperature sludge after wet oxidation. The first heat exchange pipeline and the second heat exchange pipeline exchange heat to convert the conditioned sludge and the high-temperature sludge after wet oxidation into high-temperature sludge before wet oxidation and pressurized low-temperature sludge after wet oxidation, respectively. The reactor is connected in series between the outlet of the first heat exchange pipeline and the inlet of the second heat exchange pipeline. The static mixer is installed on the pipeline between the outlet of the first heat exchange pipeline and the reactor. The static mixer is used to add the oxidant required for the wet oxidation reaction to the high-temperature sludge before wet oxidation to obtain the high-temperature sludge before wet oxidation with added oxidant. The reactor is used to convert the high-temperature sludge before wet oxidation with added oxidant into high-temperature sludge after wet oxidation through a wet oxidation reaction.

5. The oily sludge treatment system according to claim 4, characterized in that, The wet oxidation temperature in the reactor is 160-230℃, and the pressure is 1.6-3.2MPa.

6. The oily sludge treatment system according to claim 2, characterized in that, The conditioning water module includes a conditioning water storage tank and a first conditioning water pump. The conditioning water storage tank is used to mix and adjust the reclaimed water with the reagent to form conditioning water and store it. The first conditioning water pump is used to pump the conditioning water in the conditioning water storage tank to the conditioning delivery pump or a pipeline connected to the inlet of the conditioning delivery pump.

7. The oily sludge treatment system according to claim 6, characterized in that, The conditioning water module also includes a conditioning reheating unit installed on the pipeline that supplies conditioning water to the conditioning delivery pump in the conditioning water storage tank. The conditioning reheating unit heats the conditioning water by using the heat of the separated liquid separated by the silt dewatering module through heat and mass exchange.

8. The oily sludge treatment system according to claim 6, characterized in that, The conditioning water module also includes a second conditioning water pump, which is used to pump the conditioning water in the conditioning water storage tank to the raw mud conveying pump or the pipeline connected to the inlet of the raw mud conveying pump.

9. The oily sludge treatment system according to claim 1, characterized in that, The pretreatment and storage module also includes a debris pool; The sorting and filtration unit includes a first-stage filtration unit and a second-stage filtration unit for sequentially filtering foreign oil sludge before it enters the oil sludge tank, as well as a third-stage backwashing filtration unit installed on the pipeline between the oil sludge tank and the oil sludge storage tank. The first-stage filter unit is a porous mesh structure or a plate / rod chain structure. The second-stage filtration unit is a structure that uses a motor to drive the filter screen to circulate, and during the circulation of the filter screen, the separated debris is transported to the debris pool; The third-stage backwashing filtration unit returns the separated debris to the second-stage filtration unit through backwashing.

10. The oily sludge treatment system according to claim 9, characterized in that, The path through which the second-stage filtration unit conveys debris to the debris pool is constructed with an upward-sloping ramp.

11. A treatment system for oily sludge according to claim 9 or 10, characterized in that, The sorting and filtering unit also includes a rinsing unit disposed above the first-stage filtering unit and / or above the second-stage filtering unit.

12. The oily sludge treatment system according to claim 1, characterized in that, It also includes a pressure control module for controlling the system pressure, the pressure control module including a pressure control unit disposed at the top of the sludge storage tank, and / or disposed at the top of the separation tower, and / or disposed at the top of the separated crude oil storage tank; The pressure control unit includes a control valve and piping connected to the control valve, which controls the pressure by venting or injecting compressed air and / or the system's reaction gas.

13. The oily sludge treatment system according to claim 12, characterized in that, The top of the separation tower is equipped with a first pressure control unit, and the pipeline of the first pressure control unit includes a first gas path for sending the gas discharged from the separation tower into the sludge storage tank.

14. The oily sludge treatment system according to claim 13, characterized in that, The top of the crude oil separation tank is equipped with a second pressure control unit, and a second gas passage for gas exchange between the first pressure control unit and the second pressure control unit is also constructed between them.

15. The oily sludge treatment system according to claim 12, characterized in that, A third pressure control unit is installed on the top of the sludge storage tank. The pipeline of the third pressure control unit is used to send the gas discharged from the sludge storage tank into the third gas path of the conditioning water module.

16. The oily sludge treatment system according to claim 1, characterized in that, The separation tower is equipped with an oil-water interface level measurement sensor assembly, which is used to measure and control the oil-water interface to ensure the separation performance, continuity and stability of the oil-water separation process.

17. The oily sludge treatment system according to claim 1, characterized in that, The separation tower utilizes the thermal energy from the process to keep the oil temperature above the "wall-hanging temperature" during the separation process.

18. The oily sludge treatment system according to claim 17, characterized in that, The "wall hanging temperature" is 40-80℃.

19. A treatment method for treating oily sludge using the treatment system described in any one of claims 1-18.

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