Coupling method for oil gas recovery of oily sludge and preparation of biochar

Abstract

The invention discloses a coupling method for oily sludge oil gas recovery and biochar preparation, and belongs to the technical field of oily sludge resource utilization, and the coupling method specifically comprises the following steps: compounding oily sludge and biomass waste to form a composite raw material with a clay-carbon precursor structure; and then carrying out programmed temperature control coupling pyrolysis in an inert atmosphere, carrying out slow pyrolysis in a first temperature zone of 200-400 DEG C to fully recover oil gas, heating to a second temperature zone of 500-700 DEG C, and carrying out heat preservation to promote the reconstruction of clay minerals and biomass carbon skeletons to form stable biochar. According to the coupling method for oil-gas recovery of the oily sludge and preparation of the biochar, the light yield of an oil-gas product can be increased synchronously, and pyrolysis residues can be converted into the high-performance biochar in situ. The method does not need exogenous additives and subsequent modification, is simple in process and low in cost, and realizes comprehensive recycling and high-value utilization of the oily sludge.

Description

Technical Field

[0001] This invention relates to the field of oily sludge resource utilization technology, and in particular to a coupling method for oil and gas recovery from oily sludge and biochar preparation. Background Technology

[0002] With the rapid development of the petroleum industry, the amount of oily sludge generated during oil and gas exploration, development, refining, storage, and transportation is increasing daily. This type of waste has diverse sources (including landfill sludge, tank bottom sludge, and oily scum) and complex compositions (such as petroleum hydrocarbons, heavy metals, clay, and rock fragments). It is listed in the National Hazardous Waste List as HW08 hazardous waste, and its efficient resource recovery and harmless treatment is a major challenge facing the industry. Currently, pyrolysis technology is one of the mainstream methods for treating oily sludge and recovering oil and gas resources. However, existing technologies and processes are mostly designed with the sole aim of recovering pyrolysis oil and gas resources. Due to the large variation in the oil content of pyrolysis feedstocks and the unstable nature of the residues after pyrolysis, which contain pollutants such as heavy metals and polycyclic aromatic hydrocarbons, subsequent treatment of the pyrolysis residues usually requires methods such as incineration, cement kiln co-firing, and safe landfill. This results in low resource utilization and high secondary treatment costs. In order to pursue the resource value of the residues, some studies have attempted to prepare them into adsorbent materials or soil conditioners, but these often require complex subsequent activation or modification processes, which are not economically viable and difficult to industrialize.

[0003] On the other hand, although the technology for preparing high-value-added biochar from pure biomass is mature, the raw material cost is high and the process is independent, making it difficult to couple with existing oily sludge treatment facilities.

[0004] Therefore, current processes focused on oil and gas recovery cannot solve the problem of residue disposal, while processes focused on biochar production face high raw material or post-processing costs. Developing a synergistic coupling technology that can simultaneously and efficiently recover oil and gas and convert residues in situ into high-quality, directly applicable biochar, thus achieving a closed loop of pollutant treatment, resource recovery, and product utilization, has become a critical technological bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a coupling method for oil and gas recovery from oily sludge and biochar preparation to solve the above-mentioned problems.

[0006] This invention provides a coupling method for oil and gas recovery from oily sludge and biochar preparation, comprising the following steps: (1) Raw material construction: oily sludge and biomass waste are compounded to form a composite raw material with a clay-carbon precursor structure; The composite raw material obtained after compounding has an oil content of 15%–40% in the oily sludge, a natural clay mineral content of 10%–30%, and a water content of 50%–60%. The biomass waste is an agricultural or forestry processing byproduct, and its addition amount accounts for 5% to 25% of the total mass of the composite raw materials; (2) Coupled pyrolysis: The composite raw material is placed in an inert atmosphere and subjected to programmed temperature-controlled coupled pyrolysis; Slow pyrolysis is carried out in the first temperature zone of 200℃~400℃, with a heating rate of 3℃ / min~5℃ / min, and the temperature is held at the end of this temperature zone for 60~90 minutes. The temperature is raised to a second temperature zone of 500℃~700℃, the heating rate is increased to 10℃ / min~20℃ / min, and the temperature is held for 60~120 minutes; (3) Product output: collect and condense the oil and gas products generated in the first temperature zone and the second temperature zone, and collect the solid biochar obtained after the second temperature zone is completed.

[0007] Preferably, in step (1), the oily sludge is a mixture of bottom sediment from crude oil and crude oil product storage tanks, fallen oily sludge, and dehydrated oily scum; the oil content of the bottom sediment from crude oil and crude oil product storage tanks is 30%–60%, the water content is 20%–40%, and the solid content is 3%–6%; the oil content of the fallen oily sludge is 5%–15%, the natural clay mineral content is 30%–70%, and the water content is 30%–50%; the oil content of the dehydrated oily scum is 8%–10%, the water content is 75%–80%, and the solid content is 6%–8%.

[0008] Preferably, in step (1), the natural clay mineral is montmorillonite or bentonite with a layered structure.

[0009] Preferably, in step (1), the biomass waste is selected from at least one of straw, sawdust, rice husk, and coconut shell.

[0010] Preferably, in step (2), the heating rate of the first temperature zone is set according to the total volatile content of the composite raw material, and the heating rate decreases by 1℃ / min for every 5% increase in the total volatile content.

[0011] Preferably, in step (2), the endpoint temperature of the second temperature zone is set according to the application requirements of the target biochar: when used for acidic soil improvement, the endpoint temperature is controlled at 600℃~700℃; when used for water adsorption, the endpoint temperature is controlled at 500℃~600℃.

[0012] Preferably, in step (2), the inert atmosphere is nitrogen.

[0013] Preferably, in step (1), the ratio of the composite raw materials needs to satisfy the following relationship: 0.15 ≤ (O / C) 原料 / ω 粘土 ≤0.30, where (O / C) 原料 The oxygen-carbon atomic ratio of the composite raw material, ω 粘土 The percentage of clay minerals in the composite raw material (wt%).

[0014] Preferably, the endpoint temperature T (°C) of the second temperature zone and the pH value of the obtained biochar follow the following empirical relationship: pH = 0.011T + 2.4, where the value of T ranges from 500°C to 700°C.

[0015] Preferably, the heat preservation time t (min) in the second temperature zone and the biomass addition amount B (wt%) in the composite raw material satisfy a functional relationship: t=α×B, where α is a proportionality coefficient with a value range of 1.8~2.2min / wt.

[0016] Preferably, the prepared biochar has a multi-level porous structure formed by the in-situ cross-linking and interpenetration of a clay mineral framework derived from oily sludge and a carbon framework derived from biomass through pyrolysis; its specific surface area is ≥200 m². 2 / g, fixed carbon content ≥45%, pH value between 8.0 and 9.5; the mass ratio R of alkaline oxides (CaO, MgO, K2O, Na2O) to acidic oxides (SiO2, Al2O2) in its ash is between 0.25 and 0.65.

[0017] Therefore, the above-mentioned coupling method for oil and gas recovery from oily sludge and biochar preparation has the following beneficial effects: (1) Achieved a dual improvement in oil and gas recovery efficiency and quality: By constructing an oily sludge-biomass composite raw material system and implementing segmented targeted pyrolysis, the catalytic effect of natural clay in the oily sludge and the supporting effect of biochar are fully utilized in the first temperature zone to promote the cracking of heavy petroleum hydrocarbons. Compared with the pyrolysis of single oily sludge under the same conditions, this invention can systematically increase the yield of medium and light components in the pyrolyzed oil and gas by more than 15%, significantly improving the quality and value of the recovered resources.

[0018] (2) In-situ conversion of pyrolysis residue into high-quality biochar was achieved: Through the synergistic design of raw material ratio and pyrolysis parameters, pyrolysis residue can be directly converted into high-quality biochar with application value without any exogenous additives or post-processing. The resulting biochar has a unique multi-level porous structure formed by the interpenetration of clay mineral framework and biomass-derived carbon framework, and its specific surface area is stable at ≥200 m². 2 / g, fixed carbon content ≥45%, pH value can be adjusted within the ideal range of 8.0-9.5, meeting the physicochemical requirements for soil improvement or water adsorption.

[0019] (3) A predictable and controllable precision process system has been established: breaking through the traditional experience-based trial-and-error optimization model, the key quantitative relationship has been revealed for the first time: by controlling the (O / C) of composite raw materials. 原料 / ω 粘土 A ratio between 0.15 and 0.30 can fundamentally balance reactivity and structural stability, ensuring optimal synergistic effects. A linear relationship between the final pyrolysis temperature T and the pH value of biochar was established, enabling precise customization of product properties directly through process parameters.

[0020] (4) A win-win solution for both environmental and economic benefits has been formed: This invention treats waste with waste, co-converting oily sludge and inexpensive biomass waste into two products: high-calorific-value oil and gas and high-performance biochar. This completely eliminates the hazardous waste properties of the residue and avoids landfill costs. The process does not require complex modifications and is particularly suitable for upgrading existing small and medium-sized pyrolysis devices. It achieves a significant reduction in processing costs and maximizes the value of resource output, forming a complete environmental and economic closed loop with broad application prospects.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of a coupling method for oil and gas recovery and biochar preparation of oily sludge according to the present invention. Detailed Implementation

[0023] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0025] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0026] This invention provides a coupling method for oil and gas recovery from oily sludge and biochar preparation, comprising the following steps: (1) Raw material construction: oily sludge and biomass waste are compounded to form a composite raw material with a clay-carbon precursor structure; The composite raw material obtained after compounding has an oil content of 15%–40% in the oily sludge, a natural clay mineral content of 10%–30%, and a water content of 50%–60%. The biomass waste is an agricultural or forestry processing byproduct, and its addition amount accounts for 5% to 25% of the total mass of the composite raw materials; (2) Coupled pyrolysis: The composite raw material is placed in an inert atmosphere and subjected to programmed temperature-controlled coupled pyrolysis; Slow pyrolysis is carried out in the first temperature zone of 200℃~400℃, with a heating rate of 3℃ / min~5℃ / min, and the temperature is held at the end of this temperature zone for 60~90 minutes. The temperature is raised to a second temperature zone of 500℃~700℃, the heating rate is increased to 10℃ / min~20℃ / min, and the temperature is held for 60~120 minutes; (3) Product output: collect and condense the oil and gas products generated in the first temperature zone and the second temperature zone, and collect the solid biochar obtained after the second temperature zone is completed.

[0027] Specifically, the raw material design of the clay-carbon precursor structure is the foundation of the synergistic effect. The first temperature zone (200-400℃) mainly targets the volatilization and catalytic cracking of petroleum hydrocarbons in oily sludge, prioritizing oil and gas recovery efficiency and quality. The second temperature zone (500-700℃) focuses on the pyrolysis and carbonization of biomass and its interaction with clay minerals, dominating the formation of high-quality biochar. The orderly connection between the two temperature zones achieves precise matching of the reaction pathways of different components in the time and temperature dimensions, which is a process manifestation of the overall synergistic effect.

[0028] To further optimize the above technical solution, in step (1), the oily sludge is a mixture of bottom sediment of crude oil and crude oil product storage tanks, fallen oily sludge, and dehydrated oily scum; the oil content of the bottom sediment of crude oil and crude oil product storage tanks is 30% to 60%, the water content is 20% to 40%, and the solid content is 3% to 6%; the oil content of the fallen oily sludge is 5% to 15%, the natural clay mineral content is 30% to 70%, and the water content is 30% to 50%; the oil content of the dehydrated oily scum is 8% to 10%, the water content is 75% to 80%, and the solid content is 6% to 8%. Specifically, this method can treat various types of oily sludge generated in the petroleum industry. The sources of oily sludge include tank bottom sludge (i.e., sediment at the bottom of crude oil and crude oil product storage tanks), dehydrated oily scum, and oily sludge that falls to the ground during daily production. Among them, tank bottom sludge has the highest oil content and is used to adjust the oil content in the raw materials, while dehydrated oily scum has the highest water content and is used to adjust the water content of the raw materials. To ensure no residue on site, the soil within a certain range around the oily sludge needs to be collected and treated together, so clay can be provided. After the three are compounded with biomass, the composite raw material meets the feed requirements of 15% to 40% oil content, 10% to 30% natural clay content, and 50% to 60% water content.

[0029] To further optimize the above technical solution, in step (1), the natural clay mineral is montmorillonite or bentonite with a layered structure. During pyrolysis, the layered structure of montmorillonite or bentonite can act as a catalyst carrier to promote the cracking of heavy oil molecules (improving oil and gas quality), and can also act as a skeletal support to prevent excessive shrinkage and melting of biomass pyrolysis carbon, which helps to form a stable multi-level porous structure and is the material basis for simultaneously optimizing oil and gas and biochar products.

[0030] To further optimize the above technical solution, in step (1), the biomass waste is selected from at least one of straw, sawdust, rice husk, and coconut shell. The biomass is limited to common agricultural and forestry by-products such as straw, sawdust, rice husk, and coconut shell. These raw materials are widely available, inexpensive, and rich in pyrolyzable components such as cellulose and hemicellulose. The selected biomass not only serves as a supplementary carbon source and volatile matter, increasing the total oil and gas yield, but its carbon-rich skeleton formed by pyrolysis interweaves with the clay skeleton, which is key to constructing biochar with a high specific surface area and abundant pores. Simultaneously, the ash of this type of biomass is usually rich in alkaline elements such as potassium and calcium, which helps to adjust the pH value and surface chemical properties of biochar, meeting different application needs.

[0031] To further optimize the above technical solution, in step (2), the heating rate of the first temperature zone is set according to the total volatile matter content of the composite raw material. For every 5% increase in the total volatile matter content, the heating rate is reduced by 1℃ / min. For raw materials with high volatile matter content, reducing the heating rate can slow down the pyrolysis process, promote the full and gradual release of oil and gas, and avoid dust entrainment or local overheating and coking caused by rapid pyrolysis. This ensures the oil and gas recovery rate while laying the foundation for the subsequent formation of well-structured biochar residue.

[0032] To further optimize the above technical solution, in step (2), the endpoint temperature of the second temperature zone is set according to the application requirements of the target biochar: when used for acidic soil improvement, the endpoint temperature is controlled at 600℃~700℃; when used for water adsorption, the endpoint temperature is controlled at 500℃~600℃. Higher temperatures (600-700℃) are conducive to the formation of biochar with stronger alkalinity and higher stability, which is suitable for acidic soil improvement to neutralize acidity. Moderate temperatures (500-600℃) can retain more oxygen-containing functional groups while maintaining a higher specific surface area, which is more conducive to the adsorption of pollutants in water.

[0033] To further optimize the above technical solution, in step (2), the inert atmosphere is nitrogen. An inert atmosphere is a necessary condition to ensure that the pyrolysis process proceeds along the preset path and achieves the expected synergistic effect. It can effectively prevent the oxidation and combustion of raw materials and intermediate products, thereby ensuring the recovery rate and quality of oil and gas products; it ensures that the pyrolysis residue is in a reducing environment, promotes the aromatization and ordering of biomass carbon, and is conducive to the transformation of heavy metals into more stable forms, which is a key guarantee for obtaining high-quality, low-environmental-risk biochar.

[0034] To further optimize the above technical solution, in step (1), the ratio of composite raw materials must satisfy the following relationship: 0.15≤(O / C) 原料 / ω 粘土 ≤0.30, where (O / C) 原料 The oxygen-carbon atomic ratio of the composite raw material, ω 粘土 This represents the mass percentage (wt%) of clay minerals in the composite raw material. (O / C) 原料 This reflects the reactivity of the raw materials and their tendency to form gas / carbon. 粘土 This ratio represents the structural support and stability. Maintaining this ratio between 0.15 and 0.30 signifies an optimal balance between reactivity and structural stability in the feedstock system. A ratio that is too low may result in insufficient oil and gas production; a ratio that is too high may lead to poor biochar structural strength. This quantitative indicator is a prerequisite for achieving the synergistic goal of efficient oil and gas recovery and high-quality biochar production.

[0035] To further optimize the above technical solution, the final temperature T (°C) of the second temperature zone and the pH value of the obtained biochar follow the following empirical relationship: pH = 0.011T + 2.4, where T ranges from 500°C to 700°C. This formula quantitatively correlates the core control parameter of the process with an important application performance indicator of the product. Operators can accurately calculate the required final pyrolysis temperature based on the pH value required for the target biochar, achieving precise and targeted control of the product's chemical properties.

[0036] To further optimize the above technical solution, the holding time t (min) in the second temperature zone and the biomass addition amount B (wt%) in the composite raw material satisfy a functional relationship: t = α × B, where α is a proportionality coefficient with a value ranging from 1.8 to 2.2 min / wt%. This relationship clarifies that sufficient reaction time is required for biomass pyrolysis and its interaction with clay. The holding time increases proportionally with the amount of biomass added, ensuring that biomass can be fully pyrolyzed and carbonized under different ratios, and achieve sufficient interfacial bonding and structural reconstruction with clay minerals. This avoids incomplete reaction due to insufficient time or energy waste due to excessive time.

[0037] To further optimize the above technical solution, the prepared biochar has a multi-level porous structure composed of a clay mineral framework derived from oily sludge and a carbon framework derived from biomass, which are cross-linked and interpenetrated in situ through pyrolysis; its specific surface area is ≥200 m². 2 / g, fixed carbon content ≥45%, pH value between 8.0 and 9.5; the mass ratio R of alkaline oxides (CaO, MgO, K2O, Na2O) to acidic oxides (SiO2, Al2O2) in its ash is between 0.25 and 0.65.

[0038] To provide a clearer and more detailed description of the coupling method for oil and gas recovery and biochar preparation of oily sludge provided by the embodiments of the present invention, specific embodiments will be described below.

[0039] Example 1 General-purpose biochar was prepared under typical conditions to treat oily sludge from typical oil refineries, simultaneously recovering oil and gas and producing high-quality biochar.

[0040] Raw material preparation and pretreatment: The oily sludge originated from the wastewater treatment unit of an oil refinery. Testing revealed an oil content of 8% on a dry basis and a natural clay mineral content (mainly montmorillonite) of 20%. The wet sludge was dried, crushed, and set aside for use. Wheat straw was selected as the biomass, and pulverized for use.

[0041] Based on dry weight, 85 parts of oily sludge and 15 parts of wheat straw were thoroughly mixed. The elemental composition of the composite material was determined, and its (O / C) ratio was calculated. 原料The value is 0.155. The clay mass percentage ω in the composite raw material. 粘土 =(100%-15%)×20%=17.0wt.

[0042] (O / C) 原料 / ω 粘土 =0.155 / 0.170≈0.912.

[0043] Coupled pyrolysis process: Weigh 500g of the above composite raw material and place it in a continuous feed rotary pyrolysis furnace. Introduce nitrogen as a protective gas to maintain a slightly positive pressure environment.

[0044] First temperature zone: The temperature is increased to 350°C at a rate of 5°C / min, and held at this temperature for 80 minutes. The volatiles generated in this stage are recovered through a condensation system.

[0045] Second temperature zone: Increase the heating rate to 15℃ / min and continue heating to 600℃.

[0046] Based on the biomass addition amount B=15wt% and the proportionality coefficient α=2.0min / wt%, the required heat preservation time is calculated to be t=2.0×15=30 minutes; the actual heat preservation time is 80 minutes.

[0047] After pyrolysis, the mixture is cooled under a nitrogen atmosphere.

[0048] Product analysis and synergistic effect verification: After measurement and analysis of the oil and gas products, compared with the pyrolysis of the oily sludge alone under the same conditions, the total yield of light and medium fractions (C5-C20) in the obtained pyrolysis oil increased by 18.5%, which verified the catalytic cracking effect of clay minerals and the synergistic effect of biomass addition.

[0049] Biochar product (labeled BC-1): BET specific surface area is 285 m². 2 / g, with a fixed carbon content of 53%; the pH value of BC-1 was measured to be 9.05.

[0050] According to the formula, the predicted pH value is 0.011 × 600 + 2.4 = 9.0. The measured value is in high agreement with the predicted value.

[0051] Ashing and XRF analysis of BC-1 revealed the following main ash oxides by mass percentage: SiO2 (42.1%), Al2O3 (18.5%), CaO (22.3%), MgO (4.8%), K2O (7.5%), and Na2O (2.1%).

[0052] The calculated mass ratio of alkaline to acidic oxides, R = (22.3 + 4.8 + 7.5 + 2.1) / (42.1 + 18.5) ≈ 0.605. This R value indicates that the product has moderate chemical activity. Furthermore, the coexistence of its high specific surface area and R value demonstrates the excellent preservation effect of the clay skeleton on the pore structure, overcoming the common problem of pore blockage caused by high alkali ash content.

[0053] Example 2 Customized biochar for water adsorption applications: By adjusting the endpoint temperature of the second temperature zone, customized biochar suitable for water adsorption can be created.

[0054] Raw materials: Same as in Example 1.

[0055] Process adjustment: The pyrolysis process parameters are the same as in Example 1, the only difference being that the endpoint temperature of the second temperature zone is set to 550℃ (for water adsorption).

[0056] Product validation: The specific surface area of ​​the obtained biochar (labeled BC-2) increased to 320 m². 2 / g, with a fixed carbon content of 49%.

[0057] The measured pH was 8.48, and the predicted value using the empirical formula was 0.011×550+2.4=8.45, showing a good match. The lower final temperature resulted in a slightly lower pH and a higher specific surface area, which is more conducive to the adsorption of heavy metal ions in the water.

[0058] For those containing 50 mg / Lb 2+ Adsorption experiments were conducted on the wastewater, and the saturated adsorption capacity of BC-2 reached 158 mg / g, demonstrating excellent adsorption performance.

[0059] Example 3 Customized biochar for acidic soil improvement: By adjusting the endpoint temperature of the second temperature zone, biochar suitable for acidic soil improvement can be customized.

[0060] Raw materials: Same as in Example 1.

[0061] Process adjustment: The pyrolysis process parameters are the same as in Example 1, the only difference being that the final temperature of the second temperature zone is set to 650℃ (for acid soil improvement).

[0062] Product validation: The specific surface area of ​​the obtained biochar (labeled BC-3) was 215 m². 2 / g, with a fixed carbon content as high as 58%.

[0063] The measured pH was 9.58, and the predicted value using the empirical formula was 0.011×650+2.4=9.55, showing a good match. The higher final temperature gave the product stronger alkalinity.

[0064] When BC-3 was applied at a mass ratio of 2% to acidic soil with pH=5.0, the soil pH rose to 6.5 after 30 days of cultivation, effectively neutralizing the soil acidity.

[0065] Comparative Example 1 The pyrolysis of single oily sludge was carried out using only the oily sludge from Example 1, under the same conditions of no biomass addition and other process parameters.

[0066] Results: The degree of light oil and gas conversion was low. The resulting solid residue was in block form with a specific surface area of ​​only 38 m². 2 / g, with a fixed carbon content of 35%, lacks a porous structure and has low resource utilization value.

[0067] Comparative Example 2 The pyrolysis of the mismatched composite raw materials involved mixing oily sludge and straw at a dry weight ratio of 60:40, with the remaining raw materials and process steps being the same as in Example 1.

[0068] The calculated (O / C) ratio is... 原料 / ω 粘土 The ratio is as high as 2.5; it is processed under the same pyrolysis procedure as in Example 1.

[0069] Results: The pyrolysis process was vigorous, resulting in high oil and gas production but low calorific value. The obtained solid product had a loose and brittle structure, although it possessed a certain specific surface area (190 m²). 2 However, it has poor mechanical strength and high ash content (R=0.82), making it unsuitable as a functional material.

[0070] Examples 1-3 and Comparative Examples 1-2 above fully demonstrate that the coupling method provided by this invention, through precise raw material ratio design and coordinated process control of temperature zones, can stably achieve efficient and high-quality recovery of oil and gas resources from oily sludge, and simultaneously convert pyrolysis residue into high-quality biochar with specific functions in situ. By adjusting the endpoint temperature of the second temperature zone, products suitable for different scenarios can be flexibly customized. The key performance indicators of the products obtained under all preferred schemes meet or exceed the set requirements, and the measured data are highly consistent with the empirical relationships disclosed in this invention.

[0071] Therefore, this invention employs the aforementioned coupled method of oil and gas recovery from oily sludge and biochar preparation, achieving a dual improvement in both the efficiency and quality of oil and gas recovery. By constructing an oily sludge-biomass composite raw material system and implementing segmented targeted pyrolysis, the catalytic effect of natural clay in the oily sludge is fully utilized in the first temperature zone to promote the cracking of heavy petroleum hydrocarbons. Compared with single oily sludge pyrolysis under the same conditions, this invention can systematically increase the yield of medium and light components in the pyrolysis oil and gas by more than 15%, significantly improving the quality and value of the recovered resources.

[0072] In-situ conversion of pyrolysis residue into high-quality biochar was achieved: through the synergistic design of raw material ratios and pyrolysis parameters, pyrolysis residue can be directly converted into high-quality biochar with application value without any exogenous additives or post-processing steps. The resulting biochar has a unique hierarchical porous structure formed by the interpenetration of clay mineral framework and biomass-derived carbon framework, with a stable specific surface area ≥200 m². 2 / g, fixed carbon content ≥45%, pH value can be adjusted within the ideal range of 8.0-9.5, meeting the physicochemical requirements for soil improvement or water adsorption.

[0073] A predictable and controllable precision process system was established: breaking through the traditional experience-based trial-and-error optimization model, and revealing for the first time the key quantitative relationship: by controlling the (O / C) ratio of composite raw materials. 原料 / ω 粘土 A ratio between 0.15 and 0.30 can fundamentally balance reactivity and structural stability, ensuring optimal synergistic effects. A linear relationship between the final pyrolysis temperature T and the pH value of biochar was established, enabling precise customization of product properties directly through process parameters.

[0074] This invention presents a win-win solution for both environmental and economic benefits: It treats waste with waste, co-converting oily sludge and inexpensive biomass waste into two products: high-calorific-value oil and gas, and high-performance biochar. This completely eliminates the hazardous waste properties of the residue and avoids landfill costs. The process requires no complex modifications and is particularly suitable for upgrading existing small and medium-sized pyrolysis units, achieving a significant reduction in processing costs and maximizing resource output value. This forms a complete environmental and economic closed loop with broad application prospects.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A coupling method for oil and gas recovery from oily sludge and biochar preparation, characterized in that, Includes the following steps: (1) Raw material construction: oily sludge and biomass waste are compounded to form a composite raw material with a clay-carbon precursor structure; The composite raw material obtained after compounding has an oil content of 15%–40% in the oily sludge, a natural clay mineral content of 10%–30%, and a water content of 50%–60%. The biomass waste is an agricultural or forestry processing byproduct, and its addition amount accounts for 5% to 25% of the total mass of the composite raw materials; (2) Coupled pyrolysis: The composite raw material is placed in an inert atmosphere and subjected to programmed temperature-controlled coupled pyrolysis; Slow pyrolysis is carried out in the first temperature zone of 200℃~400℃, with a heating rate of 3℃ / min~5℃ / min, and the temperature is held at the end of this temperature zone for 60~90 minutes. The temperature is raised to a second temperature zone of 500℃~700℃, the heating rate is increased to 10℃ / min~20℃ / min, and the temperature is held for 60~120 minutes; (3) Product output: collect and condense the oil and gas products generated in the first temperature zone and the second temperature zone, and collect the solid biochar obtained after the second temperature zone is completed.

2. The coupling method for oil and gas recovery from oily sludge and biochar preparation according to claim 1, characterized in that, In step (1), the oily sludge is a mixture of bottom sediment from crude oil and crude oil product storage tanks, fallen oily sludge, and dehydrated oily scum; the oil content of the bottom sediment from crude oil and crude oil product storage tanks is 30%–60%, the water content is 20%–40%, and the solid content is 3%–6%; the oil content of the fallen oily sludge is 5%–15%, the natural clay mineral content is 30%–70%, and the water content is 30%–50%; the oil content of the dehydrated oily scum is 8%–10%, the water content is 75%–80%, and the solid content is 6%–8%.

3. The coupling method for oil and gas recovery from oily sludge and biochar preparation according to claim 1, characterized in that, In step (1), the natural clay mineral is montmorillonite or bentonite with a layered structure; the biomass waste is selected from at least one of straw, sawdust, rice husk, and coconut shell.

4. The coupling method for oil and gas recovery from oily sludge and biochar preparation according to claim 1, characterized in that, In step (2), the heating rate of the first temperature zone is set according to the total volatile content of the composite raw material. For every 5% increase in the total volatile content, the heating rate is reduced by 1℃ / min.

5. The coupling method for oil and gas recovery from oily sludge and biochar preparation according to claim 1, characterized in that, In step (2), the endpoint temperature of the second temperature zone is set according to the application requirements of the target biochar: when used for acidic soil improvement, the endpoint temperature is controlled at 600℃~700℃; when used for water adsorption, the endpoint temperature is controlled at 500℃~600℃.

6. The coupling method for oil and gas recovery from oily sludge and biochar preparation according to claim 1, characterized in that, In step (2), the inert atmosphere is nitrogen.

7. The coupling method for oil and gas recovery from oily sludge and biochar preparation according to claim 1, characterized in that, In step (1), the ratio of the composite raw materials must satisfy the following relationship: 0.15 ≤ (O / C) 原料 / ω 粘土 ≤0.30, where (O / C) 原料 The oxygen-carbon atomic ratio of the composite raw material, ω 粘土 This represents the mass percentage of clay minerals in the composite raw material.

8. The coupling method for oil and gas recovery from oily sludge and biochar preparation according to claim 1, characterized in that, The endpoint temperature T of the second temperature zone and the pH value of the obtained biochar follow the following empirical relationship: pH = 0.011T + 2.4, where the value of T ranges from 500℃ to 700℃.

9. The coupling method for oil and gas recovery from oily sludge and biochar preparation according to claim 1, characterized in that, The heat preservation time t in the second temperature zone and the amount of biomass added B in the composite raw material satisfy a functional relationship: t=α×B, where α is a proportionality coefficient with a value range of 1.8~2.2min / wt.

10. The coupling method for oil and gas recovery from oily sludge and biochar preparation according to claim 1, characterized in that, The biochar produced has a multi-level porous structure formed by the in-situ cross-linking and interpenetration of a clay mineral framework derived from oily sludge and a carbon framework derived from biomass through pyrolysis; its specific surface area is ≥200 m². 2 / g, fixed carbon content ≥45%, pH value between 8.0 and 9.5; the mass ratio R of basic oxides to acidic oxides in its ash is between 0.25 and 0.65.

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