Hydrocarbon fuel oxidation coking acceleration test method based on multi-parameter cooperative reinforcement

Abstract

The invention relates to the technical field of hydrocarbon fuel thermal oxidation stability testing, and discloses a hydrocarbon fuel oxidation coking acceleration testing method based on multi-parameter synergistic intensification, which comprises the following steps: introducing oxygen into hydrocarbon fuel through a micropore dispersion device to enable the concentration of dissolved oxygen in the fuel to reach 30 ppm to 50 ppm; oxygen-containing fuel is pumped into a reaction tube with the inner diameter of 4.5 mm to 5.0 mm and the length of 80 cm at the flow speed of 0.08 g / s to 0.12 g / s; carrying out oxidation coking reaction under the conditions that the oil temperature at the outlet of the reaction tube is 450-500 DEG C and the pressure is 3.5 MPa; quantifying the mass of carbon deposited on the inner wall of the reaction tube by adopting a pipeline charking method; and the mass of the suspended carbon particles is collected and weighed through a rear-end filter. According to the method, accelerated testing and quantitative evaluation under the oxidation coking flowing state are achieved through coordinated regulation and control of three parameters including the dissolved oxygen concentration, the flow speed and the pipe diameter.

Description

Technical Field

[0001] This invention relates to the field of testing technology for the thermal oxidation stability of hydrocarbon fuels, and specifically to a method for accelerating the oxidative coking of hydrocarbon fuels based on multi-parameter synergistic enhancement. Background Technology

[0002] Oxidative coking of hydrocarbon fuels (aviation fuel, lubricating oil, etc.) in high-temperature fuel supply systems is one of the main reasons for the decline in the reliability of aircraft engines. Oxidative coking particles accumulate in pipelines, not only increasing flow resistance and reducing heat transfer efficiency, but also, in severe cases, directly clogging fuel lines and threatening flight safety.

[0003] Current industry standards, such as ASTM D3241, have fundamental limitations in coking testing methods. Firstly, efficiency and accuracy are difficult to balance: under normal conditions (300℃, 0.4g / s flow rate, Φ2mm tube), it takes 72 hours to accumulate 5–8mg of coking, and even trace amounts of coking result in weighing errors exceeding 30%, failing to meet the timeliness requirements of aero-engine manufacturers for fuel batch inspections. Secondly, coking types cannot be distinguished: traditional methods only obtain the total coking amount, but the formation mechanisms and engineering hazards of carbon deposits on the tube wall (causing localized overheating) and suspended carbon particles (causing filter clogging) are completely different.

[0004] To address the aforementioned shortcomings, existing improvement solutions have failed to overcome the inherent contradiction between efficiency and accuracy. While online detection optimization methods (such as flow resistance and thermal resistance methods) shorten the testing cycle, they can only indirectly estimate the equivalent coking thickness and cannot separate deposited and suspended carbon components. External intervention methods (such as the electric field suppression method in patent CN201810338543A) introduce non-physical conditions, altering free radical reaction pathways and causing the graphitization degree of the coking material to deviate from reality. The core contradiction lies in the fact that existing technologies either sacrifice accuracy for efficiency (ultra-high temperature / external field interference) or sacrifice efficiency to maintain accuracy (long-cycle, low coking amount), failing to establish a rapid evaluation system that conforms to the intrinsic coking laws of fuel. To address these shortcomings, existing improvement solutions have failed to overcome the inherent contradiction between efficiency and accuracy. Summary of the Invention

[0005] To address the aforementioned shortcomings in existing technologies, this invention provides an accelerated testing method for hydrocarbon fuel oxidation and coking based on multi-parameter synergistic enhancement. This method achieves accelerated testing and quantitative evaluation under oxidative coking flow conditions by synergistically controlling three parameters: dissolved oxygen concentration, flow rate, and pipe diameter. It is applicable to rapid stability assessment of fuels such as aviation fuel, biodiesel, and lubricating oil.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A method for accelerating the oxidation and coking of hydrocarbon fuels based on multi-parameter synergistic enhancement includes the following steps: Oxygen is introduced into hydrocarbon fuel through a microporous dispersion device to achieve a dissolved oxygen concentration of 30 ppm to 50 ppm in the fuel; Oxygenated fuel is pumped into a reaction tube with an inner diameter of 4.5 mm to 5.0 mm and a length of 80 cm at a flow rate of 0.08 g / s to 0.12 g / s. The oxidative coking reaction was carried out under the conditions of an oil temperature of 450℃ to 500℃ at the outlet of the reaction tube and a pressure of 3.5MPa. The quality of carbon deposited on the inner wall of the reaction tube was quantified using the pipe carbonization method. The suspended carbon particles are collected and weighed through a back-end filter.

[0007] Furthermore, the microporous dispersion device is an air bubble stone.

[0008] Furthermore, the micropore diameter of the microporous dispersion device is 30 μm to 50 μm, and it can withstand temperatures ≥600℃.

[0009] Furthermore, the quality of carbon deposited on the inner wall of the reaction tube was quantified using the pipe carbonization method, including: The reaction tube after oxidation and coking is placed in a tube furnace at 800℃ and calcined with pure oxygen to convert the coke on the inner wall of the reaction tube into carbon dioxide. The carbon dioxide content is then detected by an infrared analyzer, which is then converted into the quality of the deposited carbon.

[0010] Furthermore, the back-end filter is a sintered micron-sized filter element.

[0011] Furthermore, the filter element pore size of the back-end filter is 2μm to 4μm.

[0012] Furthermore, the mass of suspended carbon particles collected and weighed through a back-end filter includes: Place the back-end filter in a 500ml beaker, add anhydrous ethanol for an ultrasonic cleaning bath to transfer the carbon particles into the solution, and then transfer the carbon particles to a 0.8μm microporous filter membrane through a filtration device. Then place the microporous filter membrane in an 80°C oven to dry for 2 hours, collect the carbon particles and weigh them.

[0013] The present invention has the following beneficial effects: This embodiment achieves rapid enhancement and precise quantification of the coking process by synergistically controlling three key parameters: dissolved oxygen concentration, flow rate, and reaction tube diameter. It innovatively employs bubble stone microporous dispersion technology to increase the fuel dissolved oxygen concentration from the conventional 10 ppm to 40 ppm, simultaneously reducing the flow rate to 0.1 g / s and expanding the reaction tube inner diameter to 4.5 mm, constructing a synergistic enhancement system of high oxygen, low flow rate, and large tube diameter. This design extends fuel residence time, achieving coking volume within 2-4 hours at an outlet oil temperature of 450-500 degrees Celsius, reaching the level of conventional tests that take 20 hours. A dual coking quantification module (pipeline coking + back-end filter collecting suspended carbon particles) completes the precise separation and weighing of total coke volume, and coke structure characterization (SEM) confirms its consistency with actual working condition deposits. This invention solves the problems of long testing cycles and small coke volumes in traditional coking methods, leading to large evaluation errors, and is suitable for rapid oxidation stability evaluation of hydrocarbon fuels such as aviation fuel and lubricating oil. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a test method for accelerating the oxidation and coking of hydrocarbon fuels based on multi-parameter synergistic enhancement. Figure 2 This is a schematic diagram comparing the amount of oxygen-carrying carbon under different pipe diameters in the experiment. Figure 3 This is a schematic diagram comparing the amount of carbon at different flow rates in the experiment; Figure 4 This is a schematic diagram comparing the amount of carbon under different tube inner diameters in the experiment; Figure 5 This is a schematic diagram of carbon collection under the conditions of the blank group and the additive group in the experiment; Figure 6 This is a SEM image of carbon buildup inside the tube during a routine experiment (65 hours). Figure 7 SEM image of carbon deposits collected by the tail-end filter in the experiment. Detailed Implementation

[0015] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0016] Example like Figure 1 As shown, an embodiment of the present invention provides a method for accelerating the oxidation and coking of hydrocarbon fuels based on multi-parameter synergistic enhancement, comprising the following steps S1 to S5: S1. Oxygen is introduced into the hydrocarbon fuel through a microporous dispersion device to achieve a dissolved oxygen concentration of 30 ppm to 50 ppm in the fuel; In an optional embodiment of the present invention, the microporous dispersion device used in step S1 is an air bubble stone. The micropore diameter of the microporous dispersion device is 30 μm to 50 μm, and it can withstand temperatures ≥600°C.

[0017] This embodiment first performs oxygen pretreatment of hydrocarbon fuel. The aviation kerosene oxidation and coking experimental apparatus consists of four parts: a fuel supply system, a reaction system, a testing and analysis system, and a cooling and recovery system. An oxygen pretreatment device is added to the fuel supply system. The hydrocarbon fuel required for the experiment is poured into a device containing an air bubble dispersion device, through which oxygen is introduced. During the fuel experiment, the dissolved oxygen content in the fuel needs to be monitored in real time. In this embodiment, a Mettler Toledo InPro6850i polarographic oxygen sensor is used to measure the dissolved oxygen concentration in the fuel. This sensor uses an electrochemical method and has an accuracy of 1% ± 6 ppb. When the oxygen concentration stabilizes at approximately 40 ppm, the experiment is prepared.

[0018] S2. Pump oxygenated fuel into a reaction tube with an inner diameter of 4.5 mm to 5.0 mm at a flow rate of 0.08 g / s to 0.12 g / s; In an optional embodiment of the present invention, step S2 uses methylcyclohexane as raw material with a mass flow rate of 0.1 g / s and employs single-stage heating to conduct an oxidation and coking test of the fuel. The reaction section is a 304 alloy pipe with an inner diameter of 4.5 mm and a length of 800 mm. The outlet fuel temperature of the reaction section is controlled at 500 °C and the outlet pressure is 3.5 MPa. The conversion rate, gas production rate, and heat sink of methylcyclohexane during the reaction are recorded.

[0019] S3. The oxidation coking reaction is carried out under the conditions of an oil temperature of 450℃ to 500℃ at the outlet of the reaction tube and a pressure of 3.5MPa. In an optional embodiment of the present invention, step S3 involves conducting a hydrocarbon fuel oxidation coking experiment on a high-pressure oxidation coking test bench for a duration of 2-4 hours.

[0020] S4. The quality of carbon deposited on the inner wall of the reaction tube is quantified using the pipeline carbonization method. In an optional embodiment of the present invention, step S4 involves placing the reaction tube after oxidation and coking in a tube furnace at 800°C and introducing pure oxygen for calcination, so that the coke on the inner wall of the metal is converted into carbon dioxide. Subsequently, the carbon dioxide content is detected by an infrared analyzer, and then converted into the quality of the deposited carbon.

[0021] S5. Collect and weigh the suspended carbon particles through the back-end filter.

[0022] In an optional embodiment of the present invention, in step S5, the filter and filter element are placed in a 500ml beaker, anhydrous ethanol is added for ultrasonic cleaning, the carbon particles are transferred to the solution, and then the carbon particles are transferred to a 0.8μm microporous filter membrane through a filtration device. The microporous filter membrane is then placed in an 80°C oven to dry for 2 hours, and the carbon particles are collected and weighed.

[0023] This embodiment achieves rapid enhancement and precise quantification of the coking process by synergistically controlling three key parameters: dissolved oxygen concentration, flow rate, and reaction tube diameter. It innovatively employs bubble stone microporous dispersion technology to increase the fuel dissolved oxygen concentration from the conventional 10 ppm to 40 ppm, simultaneously reducing the flow rate to 0.1 g / s and expanding the reaction tube inner diameter to 4.5 mm, constructing a synergistic enhancement system of high oxygen, low flow rate, and large tube diameter. This design extends fuel residence time, achieving coking volume within 2-4 hours at an outlet oil temperature of 450-500 degrees Celsius, reaching the level of conventional tests that take 20 hours. A dual coking quantification module (pipeline coking + back-end filter collecting suspended carbon particles) completes the precise separation and weighing of total coke volume, and coke structure characterization (SEM) confirms its consistency with actual working condition deposits. This invention solves the problems of long testing cycles and small coke volumes in traditional coking methods, leading to large evaluation errors, and is suitable for rapid oxidation stability evaluation of hydrocarbon fuels such as aviation fuel and lubricating oil.

[0024] Compare with Example 1 The hydrocarbon fuel oxygenation pretreatment method described in the above embodiments shall be followed.

[0025] Using methylcyclohexane as the raw material, with mass flow rates of 1 g / s, 0.5 g / s, 0.25 g / s, and 0.1 g / s, a single-stage heating system was used to conduct oxidative coking experiments on the fuel. The reaction section consisted of a 304 alloy tube with an inner diameter of 1 mm and a length of 800 mm. The outlet fuel temperature of the reaction section was controlled at 500 °C, and the outlet pressure was 3.5 MPa. The conversion rate, gas production rate, and heat sink rate of the methylcyclohexane reaction were recorded. The oxidative coking experiment on hydrocarbon fuels was conducted on a high-pressure oxidative coking experimental platform for 2 hours.

[0026] Compare with Example 2 The hydrocarbon fuel oxygenation pretreatment method described in the above embodiments shall be followed.

[0027] Using methylcyclohexane as the raw material, and with mass flow rates of 1 g / s, 0.5 g / s, 0.25 g / s, and 0.1 g / s, a single-stage heating system was used to conduct oxidative coking experiments on the fuel. The reaction section consisted of a 304 alloy tube with an inner diameter of 2 mm and a length of 800 mm. The outlet fuel temperature of the reaction section was controlled at 500 °C, and the outlet pressure was 3.5 MPa. The conversion rate, gas production rate, and heat sink rate of the methylcyclohexane reaction were recorded. The oxidative coking experiment on hydrocarbon fuels was conducted on a high-pressure oxidative coking experimental platform for 2 hours.

[0028] Compare with Example 3 The hydrocarbon fuel oxygenation pretreatment method described in the above embodiments shall be followed.

[0029] Using methylcyclohexane as the raw material, and with mass flow rates of 1 g / s, 0.5 g / s, 0.25 g / s, and 0.1 g / s, a single-stage heating system was used to conduct oxidative coking experiments on the fuel. The reaction section consisted of a 304 alloy tube with an inner diameter of 3 mm and a length of 800 mm. The outlet fuel temperature of the reaction section was controlled at 500 °C, and the outlet pressure was 3.5 MPa. The conversion rate, gas production rate, and heat sink rate of the methylcyclohexane reaction were recorded. The oxidative coking experiment on hydrocarbon fuels was conducted on a high-pressure oxidative coking experimental platform for 2 hours.

[0030] Compare with Example 4 The hydrocarbon fuel oxygenation pretreatment method described in the above embodiments shall be followed.

[0031] Using methylcyclohexane as the raw material, and with mass flow rates of 1 g / s, 0.5 g / s, 0.25 g / s, and 0.1 g / s, a single-stage heating system was used to conduct oxidative coking experiments on the fuel. The reaction section consisted of a 304 alloy tube with an inner diameter of 4.5 mm and a length of 800 mm. The outlet fuel temperature of the reaction section was controlled at 500 °C, and the outlet pressure at 3.5 MPa. The conversion rate, gas production rate, and heat sink rate of the methylcyclohexane reaction were recorded. The oxidative coking experiment on hydrocarbon fuels was conducted on a high-pressure oxidative coking test bench for 2 hours.

[0032] Compare with Example 5 The experiment was repeated while keeping all other operating conditions the same, without performing the oxygenation pretreatment as in Control Examples 1-4.

[0033] like Figures 2 to 7 As shown, Figure 5 In this invention, MCH represents methylcyclohexane, BHT represents butyl-p-cresol, Ph2Se2 represents diphenyldiselenes, and THNone represents tetrahydronaphthone. From the experiments in the embodiments and control examples of this invention, it can be concluded that by increasing the dissolved oxygen concentration of fuel from the conventional 10ppm to 40ppm, simultaneously reducing the flow rate to 0.1g / s and expanding the inner diameter of the reaction tube to 4.5mm, under the constructed high oxygen-low flow-large tube diameter synergistic enhancement system, the coking amount can reach the level of conventional 20-hour tests within 2-4 hours.

[0034] This invention establishes a synergistic model of dissolved oxygen concentration (0.1-50ppm), flow rate (0.08-0.12g / s), and pipe diameter (4.0-5.0mm). At an outlet oil temperature of 450-500℃, it can obtain the equivalent coking amount of conventional methods that take 20 hours in just 2-4 hours. SEM analysis confirms that the coke lamellar structure (2.3±0.4nm) is highly consistent with the actual deposits under operating conditions (similarity >92%). Simultaneously, it achieves precise separation of deposited carbon / suspended carbon through pipeline carbonization and filtration, filling the technical gap in fuel additive evaluation.

[0035] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0036] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0037] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0038] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

[0039] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for accelerating the oxidation and coking of hydrocarbon fuels based on multi-parameter synergistic enhancement, characterized in that, Includes the following steps: Oxygen is introduced into hydrocarbon fuel through a microporous dispersion device to achieve a dissolved oxygen concentration of 30 ppm to 50 ppm in the fuel; Oxygenated fuel is pumped into a reaction tube with an inner diameter of 4.5 mm to 5.0 mm and a length of 80 cm at a flow rate of 0.08 g / s to 0.12 g / s. The oxidative coking reaction was carried out under the conditions of an oil temperature of 450℃ to 500℃ at the outlet of the reaction tube and a pressure of 3.5MPa. The quality of carbon deposited on the inner wall of the reaction tube was quantified using the pipe carbonization method. The suspended carbon particles are collected and weighed through a back-end filter.

2. The method for accelerating the oxidation and coking of hydrocarbon fuels based on multi-parameter synergistic enhancement according to claim 1, characterized in that, The microporous dispersion device is an air stone.

3. The method for accelerating the oxidation and coking of hydrocarbon fuels based on multi-parameter synergistic enhancement according to claim 1 or 2, characterized in that, The micropores of the microporous dispersion device have a pore size of 30 μm to 50 μm and can withstand temperatures ≥600℃.

4. The method for accelerating the oxidation and coking of hydrocarbon fuels based on multi-parameter synergistic enhancement according to claim 1, characterized in that, The quality of carbon deposited on the inner wall of the reaction tube was quantified using the pipe carbonization method, including: The reaction tube after oxidation and coking is placed in a tube furnace at 800℃ and calcined with pure oxygen to convert the coke on the inner wall of the reaction tube into carbon dioxide. The carbon dioxide content is then detected by an infrared analyzer, which is then converted into the quality of the deposited carbon.

5. The method for accelerating the oxidation and coking of hydrocarbon fuels based on multi-parameter synergistic enhancement according to claim 1, characterized in that, The back-end filter is a sintered micron-level filter element.

6. The method for accelerating the oxidation and coking of hydrocarbon fuels based on multi-parameter synergistic enhancement according to claim 1 or 5, characterized in that, The filter element pore size of the back-end filter is 2μm to 4μm.

7. The method for accelerating the oxidation and coking of hydrocarbon fuels based on multi-parameter synergistic enhancement according to claim 1, characterized in that, The mass of suspended carbon particles collected and weighed through a back-end filter includes: Place the back-end filter in a 500ml beaker, add anhydrous ethanol for an ultrasonic cleaning bath to transfer the carbon particles into the solution, and then transfer the carbon particles to a 0.8μm microporous filter membrane through a filtration device. Then place the microporous filter membrane in an 80°C oven to dry for 2 hours, collect the carbon particles and weigh them.

Images