Asphalt detection device and method based on Soxhlet extraction and speed control chromatography

Abstract

The invention discloses an asphalt detection device based on Soxhlet extraction and speed control chromatography. The asphalt detection device comprises a Soxhlet extraction system and a multi-channel stepless speed control chromatography system, the Soxhlet extraction system comprises a conical flask, a Soxhlet extractor, a snakelike condensation pipe and a heating jacket; the lower end of the Soxhlet extractor is connected with a conical flask, the upper end of the Soxhlet extractor is connected with a snake-shaped condensation pipe, and the conical flask is arranged in the heating sleeve; a vacuum pump connector is formed in the top of the S-shaped condensation pipe and connected with an external vacuum pump. The multi-channel stepless speed control chromatography system comprises four chromatography columns which are connected in parallel and an air peristaltic pump, and the air peristaltic pump is connected with the four chromatography columns respectively; an electromagnetic switching valve and an ultraviolet-visible spectrum detector are arranged at the bottom of each chromatographic column; and a conical flask is arranged below each chromatographic column. By improving the permeation efficiency of the solvent, accurate control of the chromatography flow rate and synchronous detection of multiple channels are realized.

Description

Technical Field

[0001] This invention relates to the field of petrochemical analysis and testing technology, and more specifically to an asphalt testing device and method based on Soxhlet extraction and rate-controlled chromatography. Background Technology

[0002] The separation and detection of the four components of asphalt (saturated components, aromatic components, resins, and asphaltenes) is a key analytical technique in the petrochemical industry, directly affecting asphalt performance evaluation and production process optimization. Currently, NB / SH / T 0509-2010 "Determination of Four Components of Petroleum Asphalt" is widely used both domestically and internationally as the testing standard. Its core steps include:

[0003] 1. Asphaltene precipitation: Asphaltene is separated by dissolving, precipitating, and filtering with n-heptane;

[0004] 2. Separation of soluble components: Saturated components, aromatic components and colloids are eluted sequentially using an alumina chromatography column.

[0005] However, this standard method has the following technical defects, which severely limit the detection efficiency and accuracy:

[0006] (1) Low efficiency of asphalt separation:

[0007] Extraction is time-consuming: Traditional extractors, due to their structural defects, have slow reflux rates and poor cleaning effects on asphalt. A single extraction takes 4-6 hours, and repeated manual washing of the sediment is required, bringing the total extraction time to at least 8-12 hours.

[0008] Severe solvent residue: insufficient penetration of n-heptane leads to asphaltenes encapsulating incompletely dissolved resins, resulting in a recovery rate of only 90%-97%, which affects the accuracy of subsequent component analysis.

[0009] The operation is cumbersome: it requires manual solvent replacement and temperature adjustment, involves many manual intervention steps, and has a high risk of error.

[0010] (2) Limited chromatography separation rate:

[0011] Natural flow rate dependence: elution of the chromatography column is entirely driven by gravity, with a flow rate of only 2-4 mL / min, and single sample detection requires 8-12 hours.

[0012] Manual monitoring error: Experimenters need to manually switch solvents and collection bottles, which can easily lead to cross-contamination of components due to delayed judgment (cross-contamination rate 3%-5%).

[0013] (3) Unable to meet batch testing requirements:

[0014] Single-channel design limitations: Traditional devices only support single sample processing. When faced with large-scale samples (dozens to hundreds of samples per day) from asphalt production quality inspection and research institutions, the testing cycle is too long and the cost soars.

[0015] To address the above issues, some technologies have been attempted to optimize the solutions, but all have significant drawbacks:

[0016] (1) CN201910123456.7 "A rapid extraction device for asphalt":

[0017] Technical solution: Accelerate solvent penetration by heating and pressurizing (0.2-0.5MPa) to shorten the extraction time to 3 hours.

[0018] Defects: The high-pressure environment causes uncontrolled volatilization of the solvent (n-heptane), resulting in a recovery rate fluctuation of ±3%, and poses a safety hazard.

[0019] (2) CN202010789012.3 "Multi-channel Asphalt Component Separation Device":

[0020] Technical solution: Use 3-channel chromatography columns in parallel to improve detection throughput.

[0021] Defect: The problem of consistent flow rate across multiple channels remains unresolved, with flow rate deviations in each column reaching as high as ±5%, leading to unreliable separation results.

[0022] (3) Other technical bottlenecks:

[0023] High solvent consumption: Traditional methods require more than 500 mL of solvent per sample, resulting in high detection costs.

[0024] Low level of automation: The lack of real-time monitoring and automatic switching technology makes it difficult to achieve unattended operation. Summary of the Invention

[0025] In view of this, this invention addresses the problems of low efficiency, insufficient accuracy, and inability to process batches of asphalt components in existing technologies. It proposes a highly efficient detection method and apparatus based on Soxhlet extractor vacuum optimization and a multi-channel intelligent chromatography system. By improving solvent penetration efficiency, achieving precise control of chromatography flow rate, and enabling simultaneous multi-channel detection, the following objectives are achieved:

[0026] 1. Improved testing efficiency: Processing 4 samples per batch reduces the total testing time from 20-30 hours using traditional methods to 6-9 hours, improving efficiency by more than 60%.

[0027] 2. Optimized detection accuracy: The asphalt recovery rate has increased from 90%-97% to ≥98.5%, and the cross-contamination rate of components has decreased from 3%-5% to ≤1.5%.

[0028] 3. Reduced operating costs: Solvent consumption is reduced by 40%, and manual intervention is reduced by 80%.

[0029] To achieve the above objectives, the present invention adopts the following technical solution:

[0030] An asphalt testing device based on Soxhlet extraction and rate-controlled chromatography includes a Soxhlet extraction system and a multi-channel stepless rate-controlled chromatography system;

[0031] The Soxhlet extraction system includes an Erlenmeyer flask, a Soxhlet extractor, a serpentine condenser, and a heating mantle;

[0032] The lower end of the Soxhlet extractor is connected to a conical flask, and the upper end is connected to a serpentine condenser. The conical flask is placed inside the heating jacket. The top of the serpentine condenser has a vacuum pump interface for connection to an external vacuum pump.

[0033] The multi-channel stepless rate-controlled chromatography system includes four parallel chromatography columns and an air peristaltic pump, with the air peristaltic pump connected to each of the four chromatography columns. Each chromatography column is equipped with an electromagnetic switching valve and an ultraviolet-visible spectroscopy detector at its bottom. Each chromatography column is also equipped with a conical flask below it.

[0034] Preferably, the serpentine condenser tube has a cooling medium outlet on its upper side and a cooling medium inlet on its lower side.

[0035] Preferably, the heating jacket has a built-in PID temperature controller with a temperature control range of 30-100℃ and an accuracy of ±1℃, to avoid local overheating that could lead to asphalt decomposition.

[0036] Preferably, the conical flask has a capacity of 150 or 250 mL, the Soxhlet extractor has a capacity of 150 mL, the serpentine condenser has a length of 30 cm, and it is resistant to high temperature (≤150℃) and solvent corrosion, with the diameters of each component being compatible with each other.

[0037] Preferably, the ultimate vacuum degree of the vacuum pump is -0.1MPa, which enables enhanced solvent penetration under negative pressure and an appropriate reduction in extraction temperature.

[0038] Preferably, the chromatography column includes an elution bottle and a chromatography tube fixedly connected vertically; the chromatography tube has a cooling medium outlet on its upper side and a cooling medium inlet on its lower side; the four chromatography columns are connected through the cooling medium outlet and the cooling medium inlet.

[0039] Preferably, each chromatography tube is filled with activated alumina (100-200 mesh, activity class II, packing density 1.2 g / cm³). 3 The filling height is 200mm±5mm, and the column jacket is temperature controlled at 50±1℃.

[0040] Preferably, the air peristaltic pump is equipped with a four-channel independent pump head, with a flow rate range of 0.1-10 mL / min, driven by a stepper motor, and a resolution of 0.01 mL / min.

[0041] The air peristaltic pump adopts PID closed-loop control with a flow rate resolution of 0.01 mL / min. The pump head is made of solvent-resistant fluororubber. The flow rate is monitored in real time (accuracy ±0.5%), and the motor speed is dynamically adjusted to ensure the consistency of the flow rate in the four channels (deviation ≤ ±0.5%).

[0042] Preferably, the light source of the ultraviolet-visible spectrometer is a dual-light source that switches between a deuterium lamp (190-400nm) and a tungsten lamp (400-900nm);

[0043] The detection wavelengths are: saturated components (254nm), aromatic components (280nm), and colloids (320nm), with a spectral bandwidth of 2nm.

[0044] The signal processing parameters are: 10 samples per second, automatic baseline correction, and noise <0.5mAU.

[0045] Preferably, the electromagnetic switching valve is a six-way valve structure, receiving four groups of bottles corresponding to saturated fraction, aromatic fraction, colloid, and waste liquid, with a switching response time of <0.1 seconds.

[0046] Triggering logic: When the UV absorption value exceeds the set threshold (e.g., the aromatic peak threshold > 50mAU), switch to the next receiving bottle.

[0047] Another object of the present invention is to provide a method for asphalt detection based on Soxhlet extraction and rate-controlled chromatography, comprising the following steps:

[0048] (a) The asphalt sample was extracted with n-heptane and toluene using a Soxhlet extractor to achieve asphalt separation and extraction. A vacuum pressure of -0.1 to 0 MPa was applied during the extraction process, and the extraction temperature was set in segments of 70℃→80℃→80℃.

[0049] (b) The soluble fraction after deasphalting is loaded into a multi-channel stepless rate-controlled chromatography system, and the flow rate of each channel is controlled by an air peristaltic pump to be 0.1-10 mL / min, and the flow rate deviation of each channel is ≤±0.5%.

[0050] (c) The components were sequentially eluted with a gradient of n-heptane, toluene, and toluene-ethanol mixed solvent. The elution peaks were monitored in real time using a UV-Vis detector with a wavelength range of 254-365 nm. Based on the characteristic absorption peaks (254 nm for saturated fractions, 280 nm for aromatic fractions, and 320 nm for colloidal fractions), an automatic switching valve was triggered to collect each component in stages.

[0051] Preferably, the sampling rate of the UV-Vis spectral detector in step (c) is 10 Hz, and the switching valve response time is ≤0.1 seconds. The switching trigger thresholds are: saturation fraction: absorbance >50 mAU, 254 nm; aromatic fraction: absorbance >30 mAU, 280 nm; colloid: absorbance >15 mAU, 320 nm.

[0052] The volume ratio of the toluene-ethanol mixed solvent is 9:1, and the elution flow rate is 1.5 mL / min.

[0053] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0054] High-throughput detection: Simultaneous processing of 4 channels reduces the detection time for a single batch from the traditional 12 hours to 5 hours, with a daily processing capacity of 16-20 samples.

[0055] Precise control: The PID algorithm achieves flow rate fluctuation ≤ ±0.5% and component cross-contamination rate <1.5%.

[0056] Intelligent judgment: Real-time identification of elution peaks using ultraviolet spectroscopy avoids component mixing caused by human misjudgment.

[0057] III. System Integration and Automation Control

[0058] 1. Hardware integration

[0059] Main control unit:

[0060] An industrial-grade PLC controller, integrating analog input / output modules, controls temperature, flow rate, and valve operation. In this invention, the vacuum level (vacuum pump) of the serpentine condenser and the temperature inside the heating jacket of the Soxhlet extraction system, as well as the column pressure (air peristaltic pump), electromagnetic switching valve switching, UV-Vis spectroscopy detection data, and conical flask switching of the multi-channel stepless speed-controlled chromatography system, are all controlled by the PLC controller. The connections are electrical connections that are easily understood by those skilled in the art.

[0061] The 7-inch touchscreen supports parameter settings, process monitoring, and data preview.

[0062] 2. Software Logic

[0063] Flow control logic:

[0064] (1) The user selects the detection mode (single sample / batch) and enters the sample number and parameters.

[0065] (2) System self-test (solvent balance, pump pressure, temperature), and alarm prompts for abnormal conditions.

[0066] (3) Perform extraction, chromatography and data recording according to the preset program, and automatically save the progress when abnormal interruption occurs. Attached Figure Description

[0067] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0068] Figure 1 This is a structural diagram of the Soxhlet extraction system of the present invention.

[0069] Figure 2 This is a structural diagram of the multi-channel stepless rate-controlled chromatography system of the present invention.

[0070] In the figure:

[0071] 1-Vacuum pump interface; 2-Serpentine condenser; 3-Soxhlet extractor; 4-Eragonal flask; 5-Heating mantle; 6-Air peristaltic pump; 7-Eluting flask; 8-Chromatography tube; 9-Solenoid switching valve; 10-UV-Vis spectrometer. Detailed Implementation

[0072] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0073] Example 1

[0074] This embodiment provides an asphalt testing device based on Soxhlet extraction and rate-controlled chromatography, including a Soxhlet extraction system and a multi-channel stepless rate-controlled chromatography system;

[0075] The Soxhlet extraction system includes an Erlenmeyer flask 4, a Soxhlet extractor 3, a serpentine condenser 2, and a heating mantle 5;

[0076] The lower end of the Soxhlet extractor 3 is connected to the conical flask 4, and the upper end is connected to the serpentine condenser 2. The conical flask 4 is placed inside the heating jacket 5. The top of the serpentine condenser 2 has a vacuum pump interface 1, which is connected to an external vacuum pump.

[0077] The serpentine condenser tube 2 has a cooling medium outlet on the upper side and a cooling medium inlet on the lower side;

[0078] The heating jacket 5 has a built-in PID temperature controller with a temperature control range of 30-100℃ and an accuracy of ±1℃.

[0079] The multi-channel stepless rate-controlled chromatography system includes four parallel chromatography columns and an air peristaltic pump 6, which is connected to each of the four chromatography columns. Each chromatography column is equipped with an electromagnetic switching valve 9 and an ultraviolet-visible spectroscopy detector 10 at its bottom. Each chromatography column is also equipped with a conical flask 4 below it.

[0080] The chromatography column includes an elution bottle 7 and a chromatography tube 8 fixedly connected at the top and bottom; the chromatography tube 8 has a cooling medium outlet on the upper side and a cooling medium inlet on the lower side; the four chromatography columns are connected through the cooling medium outlet and the cooling medium inlet.

[0081] Example 2

[0082] High-efficiency extraction of asphalt

[0083] 1. Sample preparation

[0084] Raw material: 70# road petroleum asphalt (compliant with GB / T 15180-2010), crushed to 180-200 mesh, sieved and weighed to 1.00g±0.01g.

[0085] Solvents: n-Heptane (analytical grade, aromatic content ≤0.1%), toluene (analytical grade).

[0086] 2. Extraction device parameters

[0087] Erlenmeyer flasks No. 1 and No. 2: Erlenmeyer flasks (250mL),

[0088] Heating jacket: Power 0-300W.

[0089] Soxhlet extractor: 150 mL.

[0090] Condenser: serpentine structure (30cm in length).

[0091] Vacuum interface: connects to the condenser tube and rotary vane vacuum pump (ultimate vacuum -0.1MPa).

[0092] 3. Extraction operation

[0093] (1) Asphalt separation

[0094] Sample loading: Load the sample into a quantitative filter paper tube (15 mm in diameter and 50 mm in height) and place it in a Soxhlet extractor.

[0095] Solvent injection: Add 100 mL of n-heptane to Erlenmeyer flask No. 1 and start the vacuum pump (pressure -0.05 MPa).

[0096] Temperature control:

[0097] Stage 1 (0-0.2 hours): Preheat at 70℃ to promote solvent penetration.

[0098] Stage 2 (0.2-1 hour): Maintain a constant temperature of 80℃ to accelerate the separation of asphalt.

[0099] (2) Eluent removal

[0100] Change bottle and solvent injection: Replace with Erlenmeyer flask No. 2 and add 100 mL of toluene.

[0101] Temperature control:

[0102] Stage 3 (1-2.5 hours): Add 80℃ constant temperature to the No. 2 conical flask to wash away the asphalt.

[0103] Endpoint determination: Extraction is terminated when the solvent in the extractor is colorless and transparent and there is no residue in the siphon tube.

[0104] 4. Result Verification

[0105] Extraction time: 2.5 hours (6 hours for traditional methods).

[0106] Example 3

[0107] Four-channel chromatography separation

[0108] 1. Chromatography System Configuration

[0109] Chromatography column: A four-channel parallel chromatography column for four-component detection, filled with Class II alumina (100-200 mesh, packing height 200mm±5mm).

[0110] Fluid drive: Air peristaltic pump (four-channel independent pump head, flow rate range 0.1-10mL / min, PID control accuracy ±0.5%).

[0111] Detection module: Ultraviolet-visible spectrometer (dual light source of deuterium lamp / tungsten lamp, wavelength 254-365nm, sampling rate 10Hz).

[0112] 2. Sample: Soluble fraction of deasphalted asphalt (load: 0.1g)

[0113] 3. Gradient elution procedure

[0114]

[0115] 4. Results Analysis

[0116] Consistency of recovery: The recovery rate of the 4-channel saturated fraction was 98.2%-98.7% (RSD = 0.3%).

[0117] Cross-contamination rate: Residual gum in aromatic fraction ≤1.2% (HPLC verification).

[0118] Total testing time: 6 hours (12 hours for a single sample using traditional methods).

[0119] Example 4: Comparative Experiment (Traditional Method vs. This Invention)

[0120] 1. Experimental Design

[0121] Traditional method group: Operate according to NB / SH / T 0509-2010, single-channel gravity chromatography (flow rate 2 mL / min).

[0122] This invention group: Four-channel PID rate-controlled chromatography (flow rate 3 mL / min).

[0123] 2. Data Comparison

[0124] index Traditional methods This invention Single sample detection time 24 hours 6 hours Asphalt recovery rate 94.5％±2.1％ 98.7％±0.5％ Solvent consumption 500mL / sample 300mL / sample Manual operation steps 15 interventions / samples 3 interventions / batch

[0125] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0126] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A bitumen testing device based on Soxhlet extraction and rate-controlled chromatography, characterized in that, Including Soxhlet extraction systems and multi-channel stepless rate-controlled chromatography systems; The Soxhlet extraction system includes an Erlenmeyer flask, a Soxhlet extractor, a serpentine condenser, and a heating mantle; The lower end of the Soxhlet extractor is connected to a conical flask, and the upper end is connected to a serpentine condenser. The conical flask is placed inside the heating jacket. The top of the serpentine condenser has a vacuum pump interface for connection to an external vacuum pump. The multi-channel stepless rate-controlled chromatography system includes four parallel chromatography columns and an air peristaltic pump, with the air peristaltic pump connected to each of the four chromatography columns. Each chromatography column is equipped with an electromagnetic switching valve and an ultraviolet-visible spectroscopy detector at its bottom. Each chromatography column is also equipped with a conical flask below it.

2. The asphalt testing device based on Soxhlet extraction and rate-controlled chromatography according to claim 1, characterized in that, The serpentine condenser tube has a cooling medium outlet on the upper side and a cooling medium inlet on the lower side.

3. The asphalt testing device based on Soxhlet extraction and rate-controlled chromatography according to claim 1, characterized in that, The heating jacket has a built-in PID temperature controller with a temperature control range of 30-100℃.

4. The asphalt testing device based on Soxhlet extraction and rate-controlled chromatography according to claim 1, characterized in that, The chromatography column includes an elution bottle and a chromatography tube fixedly connected at the top and bottom; the chromatography tube has a cooling medium outlet on the upper side and a cooling medium inlet on the lower side; the four chromatography columns are connected through the cooling medium outlet and the cooling medium inlet.

5. The asphalt testing device based on Soxhlet extraction and rate-controlled chromatography according to claim 1, characterized in that, The vacuum pump is a rotary vane vacuum pump with an ultimate vacuum of -0.1 MPa.

6. The asphalt testing device based on Soxhlet extraction and rate-controlled chromatography according to claim 1, characterized in that, The air peristaltic pump uses a PID closed-loop control algorithm with a flow rate resolution of 0.01 mL / min, and the pump head is made of solvent-resistant fluororubber.

7. The asphalt testing device based on Soxhlet extraction and rate-controlled chromatography according to claim 1, characterized in that, The ultraviolet-visible spectrometer uses a deuterium lamp or a tungsten lamp as its light source, with dual light source switching; the wavelength switching accuracy is ±1nm, and it integrates a noise filtering algorithm with a signal-to-noise ratio ≥50dB.

8. The asphalt testing device based on Soxhlet extraction and rate-controlled chromatography according to claim 1, characterized in that, The chromatography column is packed with alumina of activity level II, with a particle size of 100-200 mesh and a packing density of 1.2 g / cm³. 3 Furthermore, the temperature of the column jacket is controlled at 50±1℃.

9. A method for asphalt testing based on Soxhlet extraction and rate-controlled chromatography, characterized in that, Includes the following steps: (a) The asphalt sample was extracted with n-heptane and toluene using a Soxhlet extractor to achieve asphalt separation and extraction. A vacuum pressure of -0.1 to 0 MPa was applied during the extraction process, and the extraction temperature was set in segments of 70℃→80℃→80℃. (b) The soluble fraction after deasphalting is loaded into a multi-channel stepless rate-controlled chromatography system, and the flow rate of each channel is controlled by an air peristaltic pump to be 0.1-10 mL / min, and the flow rate deviation of each channel is ≤±0.5%. (c) The components were sequentially eluted with a gradient of n-heptane, toluene, and toluene-ethanol mixed solvent. The elution peaks were monitored in real time using a UV-Vis detector with a wavelength range of 254-365 nm. Based on the characteristic absorption peaks (254 nm for saturated fractions, 280 nm for aromatic fractions, and 320 nm for colloidal fractions), an automatic switching valve was triggered to collect each component in stages.

10. The method for asphalt detection based on Soxhlet extraction and rate-controlled chromatography according to claim 9, characterized in that, The sampling rate of the UV-Vis spectral detector described in step (c) is 10 Hz, and the switching valve response time is ≤0.1 seconds. The switching trigger thresholds are: saturation fraction: absorbance >50 mAU, 254 nm; aromatic fraction: absorbance >30 mAU, 280 nm; colloid: absorbance >15 mAU, 320 nm. The volume ratio of the toluene-ethanol mixed solvent is 9:1, and the elution flow rate is 1.5 mL / min.

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