In past decades, the electrostatics of granules and granular flows has obtained more and more attention due to many industrial problems and development of new technologies. The collisions between granule-granule and granule-wall generate electrostatics. The occurrence of electrostatic can be affected by a variety of factors. As the contact between the granular and the wall, the accumulation of electrostatic charge on their surfaces can reach to an equilibrium state. The present work reviewed electrostatic generation and electrostatic equilibrium in pneumatic conveying granules systems. Two main contact charging ways between granule and wall (collision electrification and friction electrification), granular flow pattern and dynamic analysis were analyzed emphatically. The factors affecting the charging process of granules were discussed, including external conditions (temperature, relative humidity), granules geometry conditions (size, shape, contact area, roughness) and stress conditions. Besides, the numerical calculations of electrostatics in pneumatic conveying granules systems were introduced briefly. Finally, in order to clarify the mechanism of electrostatics in the pneumatic conveying granules systems, the physical mechanism of electrostatics in single granules was analyzed. This review revealed that the working mechanism of electron transfer due to collision or friction remains was not fully understood. These issues is expected to be resolved gradually in the future.

Micro-liquid flow is widely used in microreactors, which has the advantages of high heat and mass transfer efficiency, high throughput, integration, and easy control. Micro-liquid flowmeter can achieve accurate control of samples. At meager flow rates (μL/min to nL/min), however, micro-liquid flowmeter has problems such as incomplete measurement standards and difficult calibration. Several calibration techniques used in the field of micro-liquid flow measurement are summarized, including the mass method and volumetric method. The calibration range and uncertainty of these techniques are given according to the existing research. The analysis shows that the current mass method calibration technology is still insufficient in the application of micro-liquid flow, and the influence of multiple action mechanisms needs to be further studied. The volumetric method can be achieved by different means. Although this method is still in the exploration stage, it is expected to become a more promising method in the future. Finally, combined with the development of micro-liquid flow measurement technology and the construction of an advanced measurement system, the development prospect of micro-liquid flow measurement is forecasted.

The imaging technique for particle online analysis can obtain parameters, including velocity, particle size, number, and concentration of the particle phase in sparse two-phase flow, and their three-dimensional distribution. This technique is non-invasive, simple to operate, and provides intuitive results. However, the limited depth of field in the imaging system can lead to defocus blur, which hinders its application in online particle measurement. In fact, the degree of defocus blur of the particle image contains the depth position information of particles, and the use of defocus blur to measure key particle parameters has attracted increasing attention from researchers. This paper reviews the development history of multi-parameter measurement of particles by defocusing image method. The principle of depth measurement of 3 typical defocus methods (special diaphragm method and astigmatism method based on a single camera, and two-imaging distance method based on two cameras) is briefly described. The advantages and disadvantages of different methods are analyzed. It is pointed out that with the support of advanced image processing algorithms, such as deep learning, defocus imaging method will be more widely used in the field of online particle measurement.

In recent years, particle size measurement has been widely studied at home and abroad, and the online measurement of high concentration two-phase flow of slurry has become the focus of attention. In order to measure the particle size distribution of limestone slurry during flow, ultrasonic attenuation spectra of slurry with mass concentrations of 10%—40% at different moments were obtained by an ultrasonic online measuring device. A weighted non-negative least squares algorithm (ORT-WTLS) based on optimal regularization was used to calculate the slurry particle size distribution based on the predicted theoretical spectra of Harker & Temple and BLBL scattering models. The results showed that the relative deviations of the particle diameters calculated from the theoretical attenuation spectra and the 10dB noise-containing attenuation spectra of different particle sizes were less than 5%. The attenuation coefficients did not increase linearly with slurry concentration, indicating that the Harker & Temple and BLBL nonlinear models were suitable for the theoretical prediction of high concentration slurry systems. The ORT-WTLS algorithm was used to weight the measurement errors in the slurry experimental attenuation spectrum and calculate the particle size distribution, and the measurement results were basically consistent with the image method, and the dynamic measurement deviation was less than 7%. Therefore, combining the experimental ultrasonic attenuation spectrum, the nonlinear acoustic theoretical model of particle measurement, and the ORT-WTLS inversion algorithm can accurately calculate the particle size distribution of highly concentrated slurry.

In order to investigate the instantaneous pressure oscillation characteristics of steam direct contact intermittent condensation under microscale conditions, experiments and spectral analysis were conducted on the measurement of intermittent condensation pressure in a T-shaped microchannel. It was found that under the working conditions of steam temperature 100℃, steam mass flow rate 0.45g/min, supercooled water temperature 40℃ and supercooled water mass flow rate 12.65g/min, the time domain signal of intermittent condensation pressure fluctuates between -29.5kPa and 8.8kPa, and the probability density of the pressure value near 2.5kPa was the largest. In addition, through spectrum analysis, it was found that the first dominant frequency of the pressure frequency domain signal was 10Hz, which was similar to the number of cycles experienced by intermittent condensation within one second.

Annular mist flow widely exists in natural gas and other industrial environments, in-depth exploration of the characteristics of disturbance waves is of significant importance for understanding the evolutionary patterns of annular mist flow. Experiments on gas-liquid two-phase flows were conducted in a vertical pipeline with an inner diameter of 15mm at different operating conditions. The liquid film thickness and droplet entrainment ratio were measured using a conductive ring sensor and a liquid film collection system respectively. The disturbance wave height data were extracted from the temporal signals of conductive ring sensor by using a dual-threshold method. The disturbance wave height and entrainment ratio with changes in gas-liquid flow rates and working pressure were investigated. It was found that both of them increased with increasing liquid flow rate, while they decreased with increasing gas phase flow rate and working pressure, indicating a close correlation between them. Then the scale parameters affecting the disturbance wave height were analyzed, and a disturbance wave height prediction model based on Kelvin-Helmholtz instability and interfacial shear was established. The model exhibited a relative root mean square error (rRMSE) of 4.05%, with 98.7% of data points falling within a ±10% error range, demonstrating good fitting performance. Finally, a comparison was made between the proposed model and existing disturbance wave height correlations, both prediction accuracy and scalability have been greatly improved.

Stirring leaching tank is the key equipment in vanadium extraction process of stone coal. The structure optimization of stirring tank is of great significance to improve solid-liquid suspension performance. The numerical simulation of vanadium shale mixing tanks with different configuration baffles was carried out to analyze the influence of different baffles on the solid-liquid two-phase flow in vanadium shale mixing tanks by comparing the flow field, phase distribution, dead zone distribution and other simulation results. The results showed that the installation of baffle was beneficial to the full diffusion of vanadium shale particles during agitation. The overall flow rate of the segmented baffle was about 0.65m/s, which was faster than that of the standard baffle, and the increase rate is about 15.00%. The optimized effect of the segmented baffle was similar to that of the standard baffle on the diffusion of vanadium shale particles in the mixing tank. Both baffles can reduce the dead zone of vanadium shale particles, in which the low concentration area of the standard baffle was reduced by about 99.14%, and the deposition area of the segmented baffle was reduced by about 91.21%. In addition, the segmented baffle can save 20.00% stirring power compared to the standard baffle. The segmented baffle can obtain the same stirring effect as the standard baffle. At the same time, it is more energy saving and had higher application and popularization value.

Flow pattern recognition plays a crucial role in the efficient operation and management of oil pipelines. However, the existing methods primarily focus on gas-liquid and oil-water two-phase flow, with limited accuracy in identifying flow patterns within the oil-gas-water slug flow segment. To address this limitation, this study proposed an ultrasound-based method for identifying flow patterns in the oil-gas-water slug flow segment using a radial basis function (RBF) neural network. The proposed method utilized the unique characteristics of phase distribution within the oil-gas-water slug flow segment and establishes a comprehensive set of 350 ultrasound test simulation models. By employing ultrasound transmission attenuation and reflection echo techniques, the response characteristics of the oil-gas-water slug flow segment within the pipeline were investigated. The transmission attenuation signals were then extracted to differentiate between the liquid film region, bubble entrainment region, and stable liquid slug region. To classify the flow patterns, the statistical features, such as the energy of reflected signal time series data, were extracted and utilized as inputs for the RBF neural network. The experimental results demonstrated that the proposed method achieves a high flow pattern recognition rate of 95.7% based on the ultrasound propagation mechanism and RBF neural network. This research provided a theoretical foundation for implementing flow pattern recognition of oil-gas-water slug flow in horizontal pipelines using ultrasound technology. The application of the RBF neural network-based recognition algorithm significantly enhanced the accuracy and efficiency of flow pattern identification, offering valuable insights for the effective operation and control of oil pipeline systems.

Aiming at the gas-liquid two phase flow in horizontal pipeline, a comprehensive method for flow pattern identification and flow velocity and phase fraction measurement was proposed, using only a single conductance sensor. Firstly, a conductance sensor composed of six ring-shaped electrodes was adopted to acquire flow information about the water holdup and cross-correlation velocity of gas-liquid two phase flow under different flow conditions. Secondly, based on the signal fluctuation analysis, the flow characteristics of different flow patterns were revealed. The mean and variance of the time series of normalized voltage and the cross-correlation velocity were calculated as a feature vector for flow pattern representation. Using support vector machine (SVM) method which was suitable for small samples, 15 binary classifiers with radial basis function as kernel function were constructed by “one-to-one”strategy. The parameters of the identification model were optimized by cross validation method, and 6 flow patterns (stratified flow, wavy flow, bubbly flow, plug flow, slug flow and annular flow) were identified with the identification rate of 93.1%. Thirdly, based on the identification results, the measurement models for calculations of phase fraction and mean velocity through normalized voltage and cross-correlation velocity were established for every specific flow patterns. Compared with reference values at inlet, dynamic experiments showed that the root mean square errors (RMSE) of water fraction and gas fraction were 2.56% and 2.73%, and the RMSE of mean velocity was 0.69m/s. The proposed method provides a simple, efficient, low-cost, and non-invasive flow pattern identification and process parameter measurement strategy for gas-liquid two-phase flow, which has important scientific and engineering significance.

The composite phase change materials with a porous medium metal skeleton can improve the low thermal conductivity of pure phase change materials and further improve the heat transfer rate of composite phase change materials, which has essential research significance. This research uses the finite element method to propose the construction of a two-stage backbone branch hierarchical structure metal skeleton and combines it with a paraffin square cavity. Form composite phase change heat transfer materials with better heat transfer performance and add finned tube structures on this basis to further optimize the heat transfer performance of composite phase change materials. The results show that the finned tube structure has a significant impact on the phase change heat transfer process, and the phenomenon of flow velocity protrusion near the transverse main stem can make the melting front more inclined, and the annular flow heat transfer in the cavity quickly moves towards the lower part of the square cavity. The optimized composite phase change material can shorten the solid-liquid phase transition time by 37.4% compared to the uniform skeleton composite phase change material. The trough of the instantaneous phase transition rate curve in the initial melting stage is increased by 1.88 times, and the temperature uniformity is improved, resulting in a 20.9% reduction in the maximum temperature difference at 800s after melting. This research modified the skeleton structure under a constant porosity and improved the heat storage rate of composite phase change materials through a more reasonable volume distribution of the metal skeleton.

The light field imaging technique can simultaneously record the spatial distribution information and propagation direction information of the incident light, and combined with relevant inversion algorithms, it can be used for the reconstruction of the three-dimensional temperature field of the flame. The least squares via QR factorization (LSQR) algorithm can effectively solve linear problems based on large sparse matrices, but it is difficult to ensure the nonnegativity and accuracy of the solution in the process of solving the flame radiation intensity. The non-negative least squares (NNLS) algorithm can guarantee the non-negativity of the solution, but the computational efficiency is too low. In this paper, we proposed to use the least square minimal residual (LSMR) method for three-dimensional temperature field reconstruction of flame light field imaging, and studied its reconstruction accuracy, computational efficiency, anti-noise performance and other indicators. Simulation experiments showed that the LSMR and NNLS algorithms can guarantee the non-negativity of solving the flame radiation intensity under different noise levels. In the case of noise of 5%, 10%, 15% and 20%, both LSMR and NNLS algorithms improved the accuracy of solving the radiation intensity by more than 10% compared with LSQR, and the solution time of LSMR algorithm was reduced by one order of magnitude and four orders of magnitude compared with LSQR and NNLS, respectively. It could be seen that the LSMR algorithm can significantly improve the computational efficiency while ensuring the solution accuracy. Finally, the LSMR algorithm was used to reconstruct the temperature field of the simulated light field flame, and the average relative errors were kept within 1.2% under different noise levels, which verified the accuracy and reliability of the LSMR algorithm in reconstruction.

As a new type of multiphase flow separation technology, supersonic swirling separation technology has a good application prospect in the field of natural gas dehydration and hydrocarbon removal. Liquid film characteristics in supersonic separators have a significant impact on separation performance. Therefore, the liquid film characteristics of its wet gas outlet was taken as research object, and a set of FPC conductive liquid film thickness measurement system was developed, and a calibration device was designed to obtain the actual output characteristics of the sensor. On the basis, an experimental tube section was constructed and gas-liquid two-phase separation experiments were carried out to investigate the effects of inlet liquid content and back pressure ratio on the liquid film thickness at the wet gas outlet of the supersonic separator. The calibration results showed that the sensor had high sensitivity at the liquid film thickness below 500μm, and the fitting error was within ±5%. A bimodal distribution of the liquid film thickness with a base layer thickness of about 70µm was analyzed statistically in the time domain. There was a significant difference in the trend of energy distribution between the 2nd and 3rd frequency bands after wavelet packet decomposition and the other frequency bands in the frequency domain, whereby the original signal was sequentially reconstructed, subjected to local mean decomposition, solved for approximate entropy and clustered. The liquid film fluctuation increased with increasing liquid content, and the approximate entropy can be clustered into three classes corresponding to three flow patterns. Last, the liquid film disturbance wave velocity was analyzed by using the cross-correlation algorithm, and both the flow direction component and the circumferential direction component showed an exponential growth trend with the increase of liquid content, and the flow direction component and its RMSE ranged from 84.7mm/s to 339.0mm/s and 1.15mm/s to 4.51mm/s, respectively, and the circumferential direction component and its RMSE ranged from 54.8mm/s to 186.4mm/s and 1.20mm/s to 3.38mm/s.

Alkaline water electrolysis (AWE) is currently the most widely applied and commercially scaled technology for water electrolysis. In AWE systems, breaking through the performance limitations of oxygen evolution reaction (OER) holds great significance for enhancing electrolysis performance. The behavior of bubbles in the gas evolution reaction causes an increase in electrode resistance, transport resistance during the reaction, and a decrease in the electrochemical active surface area (ECSA) of the electrode. This effect is particularly significant at high current densities, where bubbles impose substantial mass and charge transport resistance on the gas evolution reaction. Currently, there is a lack of research on the observation of internal bubble behavior in AWE systems. This study employed the Electric Discharge Machining (EDM) technique to fabricate nickel-based electrodes with order square corn holes (OSCH-Ni). Experimental observations revealed that OSCH-Ni electrodes inhibit bubble coalescence during the gas evolution reaction and restrict bubble adhesion and expulsion processes on the channel surface.Furthermore, OSCH-Ni electrodes exhibited excellent performance in the oxygen evolution reaction in alkaline water electrolysis. At the same high potential, the geometric current density of OSCH-Ni for OER was more than three times that of a typical industrial foam nickel electrode, and the normalized current density of ECSA exceeded 11 times. This work elucidates the behavior of internal bubbles in alkaline water electrolysis systems and how nickel-based ordered porous electrodes affect water electrolysis performance. It also provides an efficient and feasible solution for the design of industrial water electrolysis electrodes.

The method of reconstructing the flame temperature field based on convolutional neural network has been widely used in recent years, but the traditional convolutional neural network model is prone to overfitting or model degradation as the number of network layers increases, resulting in large reconstruction errors. This paper proposed an improved method, which used the ResNet18 network to reconstruct the flame temperature field, and introduced the attention mechanism and local importance pooling to optimize the extracted content, realized the full use of known information, and reduced the reconstruction error. The experimental results showed that after introducing the local importance pooling and attention mechanism at the same time, the average relative error of temperature field reconstruction was 0.13%, and the maximum relative error was 0.75%. Compared with the initial ResNet18 network, the average relative error was reduced by 31.58%. The maximum relative error was reduced by 34.21%. The influence of the two factors on the reconstruction accuracy was verified by ablation experiments. The results showed that the temperature field reconstruction accuracy after adding two improved modules at the same time was better than that after adding a single improved module, and the local importance pooling module had a significant effect on the accuracy improvement.

Signal analysis was used to investigate the interconnection and interaction between the subsystems in the two-phase flow system of dense-phase pneumatic conveying. Firstly, based on empirical mode decomposition (EMD), electrostatic signals of a gas-solid two-phase flow system were decomposed into several signal components, namely intrinsic mode function (IMF) and the IMF1—IMF4, which were determined as major components by comparing the energy ratios of each IMF component. Afterward, subsystems of the gas-solid two-phase flow system were identified based on the decomposition results of electrostatic signals, the distribution of particles in the conveying pipeline, and the differences in particle motion mechanisms. Finally, the relationship and interaction between subsystems were inspected by the variation regulars of the dominant frequency and variance of IMF1—IMF4, respectively. Results show that: there are four subsystems within the whole two-phase flow system in the horizontal pipeline, which are the particle-fluid mixture in the dilute-phase area, the junction area, the dense-phase area, and the wall-attached area. Subsystems are related to each other by particles traveling between them. There is also an interaction between subsystems, which is a competition between particle-dominated and airflow-dominated mechanisms, and the competition becomes more and more furious when particle suspension is weak. In contrast, the competition weakens when particle suspension is good.

The ternary lithium battery is increasing being used in the field of electric vehicles. Studying the jet velocity field of the jet valve during thermal runaway of the battery is crucial for deducing critical pressure and pressure changes inside the battery. This information holds significant importance in optimizing battery design and accurately predicting flame propagation. However, lithium batteries often have two ejections during the thermal runaway process. The ejections comprise chemical reaction gas production, electrolyte evaporation, as well as particles and fragments from various battery components. In addition, the evaporated electrolyte condenses after cooling, resulting in a gas-liquid-solid three-phase mixed state within the jet valve jet process. This complexity increases the difficulty of identifying and testing the velocity field. Therefore, in order to realize the visualization of the jet flow of the jet valve and the identification and calculation of the velocity field under high temperature conditions, an experimental bench composed of a high-speed camera, a laser system and a battery explosion-proof box was constructed in this study. The high-speed camera was used to capture and process the thermal runaway jet process of the battery. Firstly, a preliminary analysis of the flow field flow pattern was carried out. Then, the adaptive filtering algorithm effectively reduced imaging noise and enhanced droplet edge detail information. Histogram equalization was then used to further improve image contrast. Finally, the cross-correlation algorithm based on sub-pixel precision interpolation was used to analyze and calculate the velocity field of the jet flow field. This approach yielded velocity field data on a two-dimensional plane at different times intervals. The velocity characteristics of different regions at different times were further analyzed, which provides a foundation for the subsequent research on the mechanism of battery thermal runaway and the improvement of battery safety performance.

In many gas-solid rapid reaction processes, a turbulent jet is an ideal form for the mixing between gas-phase raw materials and solid particles. It is meaningful for understanding reaction processes by using effective measuring techniques and analysis methods to obtain the mixing behavior of jet and gas-solid two-phase flow. The dynamic data of particle concentration is obtained using fiber optic probe technology. On this basis, based on the traditional analysis method of particle clusters in the riser and combined with wavelet analysis, the procedure for identifying clusters in the mixing zone of jet and gas-solid two-phase flow was proposed. Furthermore, the instantaneous contact state between gas and solid in the jet influence zone was divided into three phases, i.e., the cluster phase, the dispersed particle phase, and the jet phase that was not thoroughly mixed with particles. By combining the theory of jet attachment and the gas tracing method, the centerline equation of the jet under ideal conditions was modified. The results obtained can be predict the development trend of jets in the gas-solid two-phase flow. By using ozone decomposition tracing technology, the local reaction results during the mixing process of feed jet and gas-solid two-phase flow were obtained. By combining this result with gas-solid dynamic mixing characteristics and jet trajectory model, the influence of flow parameters on the reaction can be analyzed.

Natural gas, a green, low-carbon and environmentally friendly energy source, is experiencing rapid growth and high-quality development due to energy transformation. At present, the system structure of natural gas industry is continuously evolving. However, traditional natural gas flowmeters struggle to meet the current requirements for measurement accuracy and real-time performance. The presence of liquid phase components in wet natural gas can distort measurement results, significantly increasing the complexity and cost of wet gas measurement. Therefore, there is an urgent need for an accurate, convenient and efficient online measurement method. This study aims to explore a dual-parameter method for measuring wet gas flow. A vane cyclone was employed to convert hard to measure liquid droplets or stratified manifold into a phase-isolation state of gas column and liquid ring. This process mitigates the influence of flow pattern on experiment error. By using a Venturi tube to measure two parameters: axial pressure difference and radial pressure difference, leading to the development of a dual-parameter wet gas measurement method. Taking into account factors such as phase distribution, pressure field, velocity field and other conditions related to high pressure closed gas transportation, a multi-factor correlation measurement model with strong applicability was established. This model was tested and calibrated in the field using the wet gas experimental platform at TH Oilfield. The results were good, with error margins of ±5% and ±9% for gas phase and liquid phase mass flow.

Detecting impurities of droplets in natural gas pipelines is challenging, and conventional off-line detection methods suffer from serious lag. In response, a two-parameter on-line measurement method of droplet concentration based on microwave resonance principle was studied. The simulation model of microwave resonance measurement sensor was established by COMSOL numerical simulation. Through parametric scanning, it is determined that with the diameter of the resonant probe R_C of 6mm, the maximum electric field intensity in the center area of the measurement pipeline could reach 14100V/m, and the average current density j_avg(x) was 1015.48. The maximum current density deviation I_max(x) was 0.95, indicating that the microwave resonant measurement sensor has reached the optimal structure parameter. The influence of droplet concentration changes on the microwave resonance measurement system was also studied. Experimental results showed that the method aligned well with the off-line weighing method. The shift of resonant frequency and the effective increment of response amplitude of the sensor were sensitive to the change of droplet concentration and showed a linear correlation trend. The repetition rate of the sensor fluctuated around 0.25%, demonstrating the good stability of the microwave resonance method. This research provides a new perspective and guidance for the on-line measurement of droplet concentrations in high pressure natural gas pipelines.

Measuring the thickness of liquid films has important applications in many scientific and engineering fields. In this paper, based on the transverse shear interferometry technique, the thickness distribution and time evolution of the triangular and rectangular vertical free-plane liquid films were investigated. The streak-tracking algorithm was used to process the interference images of the liquid film taken by a camera. Experimental results showed that the thickness of the triangular liquid film ranged 0.98—9.37μm, and the thickness of the rectangular liquid film ranged 0.1—13μm. Under the influence of gravity, the thickness of the liquid film gradually increased from top to bottom, and the thickness of the liquid film was uniformly distributed in the horizontal direction. With the passage of time, the overall thickness of the liquid film decreased gradually due to gravity drainage. The thickness of the weakest point at the top reached the minimum value of 0.08μm before the overall rupture of the rectangular liquid film. Further analysis of the rectangular liquid film reveals that the maximum volume of the film was 2.66mm³ and the maximum volumetric flow rate was 0.28mm³/s throughout the drainage process. In addition, the visualization of the surface flow field of the liquid film could be realized by the distribution change of the interference fringes, which provided a new research method for the study of the microscopic surface flow field of the liquid film.

Screw conveyor is widely used in chemical industry, metallurgy, grain and transport and other fields, and the movement of its screw blade has a direct impact on the conveying state. Most of the closed transport, and harsh operating environment, after a long time of work, easy to deformation of the spiral blade, or even broken shafts and other accidents, through real-time detection of the movement speed of the spiral blade, can be timely access to the operating status of the screw conveyor. For the lack of effective means of detecting the movement speed of the spiral blade, an electrostatic sensor was designed, and the problem of serious noise interference of the electrostatic signal was proposed based on the empirical mode decomposition (empirical mode decomposition, EMD) of the electrostatic signal filtering method, and the filtered signals could be obtained through the mutual correlation calculation of the rising speed of the spiral blade. The rising speed of the spiral blade could be obtained by the cross-correlation calculation of the filtered signal. The experimental results showed that the electrostatic signal detected at the pipe wall during the spiral conveying process was periodic and consistent with the frequency of the spiral blade passing through the electrodes, and the relative error of the spiral speed measurement was 0.67% after the filtering process based on EMD and the correction of the spiral speed.

The real-time monitoring of the flame in the furnace of coal-fired power plants is crucial for both the economics of power generation and the safe operation of the boiler. Traditional fire detection techniques based on energy signals such as light, heat and radiation can only detect the presence or absence of flame. These techniques are gradually unable to meet the increasingly stringent requirements for fine-grained "peaking" of thermal power generation. In this study, the features of flame images from actual power plants were analyzed from multiple perspectives. By leveraging an improved version of the Inception deep convolutional neural network (DCNN) for flame state classification, the multi-dimensional characteristics of flame were extracted. And a dataset was made by in-depth analysis of the flame image characteristics of the burner. At the same time, the preprocessed images of different categories of flames were used to create a flame image dataset. The Inception DCNN models were constructed to achieve flame state classification based on automatic feature extraction. It was proposed to classify the flame state of the burner based on the Siamese-Inception DCNN. It was found that the improved Siamese-Inception DCNN model, which converted the flame state classification problem into an evaluation of state similarity, was proposed indirectly to achieve the classification objective. The recognition accuracy of the network architecture reached 99.86%.

To investigate the measurement of phase holdup of oil-water annular flow by ultrasonic attenuation method, a model of oil-water annular flow was created using COMSOL simulation software. The ultrasonic sensor structure was in size of 6mm, and the ultrasonic emission frequency was 1MHz. The relationship between ultrasonic attenuation coefficient and oil content of oil-water annular flow was determined through analyzing the ultrasonic attenuation characteristics of oil-water annular flow, establishing the measuring range of linear relationship. Based on this, the correlation factors of non-ideal annular flow and their influence on ultrasonic attenuation characteristics were investigated further. The differential threshold of non-ideal annular flow was presented to quantify the effects of non-ideal annular flow parameters on the ideal annular flow ultrasonic attenuation method. The range for the differential threshold of 10% was proposed for the degree of concentric and ellipticity of the non-ideal annular flow. Finally, the static verification experiment of oil-water annular flow was carried out. The results showed that the phase holdup of oil-water annular flow was in the range of 5%—30%, which was linearly connected to the ultrasonic attenuation coefficient. The differential threshold of non-ideal annular flowed varies from 0.75—1 and from 0—5% in the range of ±10%, respectively. The trends in the experimental and simulation results were similar, attesting to the reliability of the simulation model.

Slug flow is a typical two-phase flow pattern of gas-liquid intermittent flow. The measurement of gas slug characteristic parameters is of great significance for the measurement of abrasion pressure drop in slug flow, sectional void fraction, and other flow parameters. In this paper, a gas slug parameter measurement sensor based on the acoustic emission principle was designed, and the noise signals of horizontal pipe slug flow under different flow conditions were measured. Whale optimization algorithm (WOA) was employed to optimize the variational modal decomposition (VMD) for noise signal processing. By analyzing the original signal from the perspectives of energy and entropy, the decoupling of noise signals from the horizontal pipe slug flow was achieved. The noise signals were divided into high-frequency gas-solid noise, medium-frequency gas-liquid noise, and low-frequency liquid-solid noise. The measurement of gas slug frequency and slug length was realized by analyzing the time-domain signals of acoustic emission. The CatBoost algorithm was used to select 8 feature values to construct predictive models for slug flow slug frequency and slug length. The mean absolute percentage error (MAPE) of the slug frequency prediction model was 5.12%, and the relative deviations of 95.25% of experimental points were within the range of ±15%. The mean absolute percentage error (MAPE) of the slug length prediction model was 7.77%, and the relative deviations of 90.48% of experimental points were within the range of ±15%.

Oil-gas-water multiphase flow is pervasive in oil and gas industry processes. However, the current phase fraction model for oil-gas-water multiphase flow limits to fully exploit the measurement information from ultrasonic transducers. To solve this problem, an optimized phase fraction model that employs an ultrasonic testing technique in water-based dispersed stratified flow was proposed. Using the maximum particle size model, the variations in particle size in water-based dispersed stratified flow was studied, and the particle size-wavelength ratio resides within the intermediate wavelength regime was determined. Moreover, a "one-transmitter-three-receivers" test system was adopted based on the ultrasonic pulse-echo method and developed a testing method for ultrasonic diffusion attenuation in water-based dispersed stratified flow. Subsequently, it was integrated Faran's elastic scattering theory to establish an ultrasonic testing model for oil fraction in oil-water dispersed flow. Utilizing time-of-flight measurement information, a modified parameter to account for fluctuations in the ultrasonic propagation path were proposed. This allowed to enhance the testing model for mixed sound velocity in oil-water dispersed flow and further optimize the gas fraction testing model. Simulation results showed that the mean relative error (MRE) and root mean square error (RMSE) for gas fraction prediction in water-based dispersed stratified flow were 0.43% and 0.23% respectively, while the MRE and RMSE for oil fraction prediction were 3.30% and 0.28% respectively. These results confirm the efficacy and precision of the proposed optimized testing model for phase fraction based on mixed sound velocity, thereby providing a theoretical foundation for ultrasonic testing methods in oil-gas-water multiphase flow.

The double-wavelength transmission method is a high precision method to detect the phase distribution parameters of multiphase flow. In order to improve the accuracy of phase distribution measurement, the gradient bosting decision tree (GBDT) algorithm was proposed in this paper. Optical simulation was used to simulate the propagation process of bubble light with wavelength of 445nm and 635nm in gas-liquid two-phase flow under different phase distribution. The light intensity distribution of detection plane was collected and the influence of bubble center location and bubble radius on the light intensity distribution curve under different phase distribution was analyzed. The measurement model was developed with GBDT, and the corresponding database between the characteristic parameters and the bubble phase distribution was established with the missing width and missing offset of light intensity as the characteristic parameters. A trained model was used to predict the phase distribution of bubbles. The mean square error of the measurement model was less than 0.0008mm, and the mean square error was reduced by 33.33%, which proved that the measurement model was more suitable for the measurement of the phase distribution. An experimental platform was built to predict the flow phase distribution parameters of vertically rising bubbles, and the movement trajectory of the central position of bubbles was tracked.

Gas-liquid two-phase flow is prevalent in various industries. The measurement and statistical analysis of bubbles characteristics are useful for the investigation of the bubbles motion and generation. Therefore, it can provide the fundamental data for physical mechanism and process control research. In this paper, bubble images were captured by a high-speed camera system at different liquid flow rates and aeration volumes in the circulating water tank. Given that bubble coalescence and breakup during motion could lead to overlapping and sticking issues in the images, these phenomena would cause significant measurement errors in bubble characterization parameters. To address these issues, this paper improved the marker extraction method of the watershed algorithm. The method obtained foreground markers by utilizing the extreme points of the distance transformed image for suppression and fusion, thereby improving the accuracy of the bubbles segmentation. Least squares ellipse fitting was conducted on the segmented bubbles to reconstruct the bubbles profile and obtain their parameters. Experimental results showed that the proposed method have obvious improvement on segmenting the adherent bubbles and extracting the bubble features. Compared to the methods of erosion operation and threshold segmentation for extracting markers, the proposed method increased the accuracy by 22.7% and 13.6%, respectively. Moreover, statistical analysis of the obtained data showed that the number of bubbles increases slightly with increased ventilation volume, while the average bubble size increased significantly. It was found that the ventilation volume mainly affects the size of the bubbles. On the other hand, the bubbles motion was affected by the liquid flow rate. It was noted that the increased liquid flow rate would generate more bubbles with small size due to bubbles breakup.

Ultraviolet differential absorption spectroscopy technology has been widely used in the monitoring of industrial flue gas emissions. The spectrometer, a core component of the UV flue gas analyzer, is susceptible to wavelength drift caused by temperature changes, which in turn affects the accuracy of pollutants monitoring results. In this paper, a soft wavelength calibration method for spectrometers is proposed. A standard SO₂ absorption spectrum peak wavelength database is established through experiments. When the wavelength drift exceeds 0.02nm, the corresponding function between the spectrometer pixel and wavelength will be re-fitted using the pixel of the SO₂ absorption peak in conjunction with the database. This method enables real-time calibration of the spectrometer wavelength. Experiments are conducted to validate the proposed calibration method. Results showed that with a 10℃ environmental temperature range, this method can reduce the measurement error of 993mg/m³ NO standard gas from 115.2mg/m³ to 21.4mg/m³, with an absolute error reduction of 93.8mg/m³. The best wavelength calibration effect is achieved when the measured SO₂ concentration is 1430mg/m³. For low-concentration measurement sites, the signal-to-noise ratio of the spectral signal can be amplified by increasing the number of spectral averages, thereby improving the effectiveness of the online wavelength calibration method.

In recent years, the reconstruction of the three-dimensional (3D) temperature field from the flame light-field image by the method of deep learning has been a new direction in radiation thermometry. The traditional temperature field reconstruction network still uses the feature extraction method of the plane image, which not only ignores the 3D ray information recorded in the light-field image but also fails to consider the classification of tracing rays. Therefore, the absence of prior information and the hybridity of different types of features have a negative impact on the reconstruction accuracy of temperature field. This article optimized the feature extraction process in the network. Firstly, the view angle information of the sub-aperture image was added to the network input. Then the spatial and angular features of the light-field were extracted by the double-branch convolution method. Finally, the attention mechanism was used to model the importance of features at different scales. The effectiveness of the above factors on the reconstruction accuracy was verified by orthogonal experiments. The simulation results showed that the Mean Relative Error (MRE) of the temperature field reconstructed by the optimization method was reduced by 44.82%, and the Maximum Relative Error (MMRE) was reduced by 34.76% compared to traditional networks.

The pressure drops characteristics of supercritical CO₂ fluid in a heating mini-channel with an inner diameter of 0.75mm under varying flow direction conditions were investigated experimentally. The results showed that the Different flow directions (horizontal flow, vertical upward flow, and vertical downward flow), the total pressure drop, frictional pressure drop, and accelerational pressure drop consistently decreased with the increase in system pressure, but increased with the rise of mass flow rate, heating power, and inlet temperature, irrespective of the flow directions. Conversely, the gravitational pressure drop increased with the increase of system pressure and mass flow rate, but decreased with the increase of heating power and inlet temperature in vertical flow directions. When the system parameters were held constant, the frictional pressure drop was the most significant proportion to the total pressure drop, while the gravitational pressure drop contributed the least. A comparison of the pressure drop data across two different inner diameters revealed that the total pressure drop of the supercritical CO₂ fluid was consistently higher in smaller diameters, highlighting the significant impact of tube diameter on total pressure drop changes.

The light field particle tracking velocimetry (PTV) can track the trajectories of the bubbles in the gas-liquid two-phase flow via a single camera. This method provide a solution for the measurement of bubble parameters in space-constraint applications. However, under the conditions of high bubble concentration and large bubble displacement, the matching accuracy of PTV bubbles in the light field is low, resulting in significant velocity measurement errors. In order to solve this problem, this paper proposed a bubble matching method based on global position iteration and polar coordinate system similar technology (GPPI-PCSS). The GPPI-PCSS method iteratively updated the positions of all bubbles in a single frame image through the three-dimensional displacement field obtained by the PCSS matching method. As a result, the bubble positions in the two frames gradually coincide and the accurate bubble matching results could be obtained. The performance of the GPPI-PCSS method was evaluated by experimental study of the bubble motion behavior in the bubbling bed through light field PTV. Results showed that the average bubble matching accuracy of the GPPI-PCSS method was 92.65% in the range of 0.5—7ms sampling interval and 0.15—0.35L/min air flow, which was higher than 81.38% of the traditional PCSS method and 84.12% of the relaxation method, respectively. In addition, the maximum motion velocity of bubbles measured by GPPI-PCSS method ranged from 38.34—49.87cm/s, which was consistent with the theoretical calculation value. These results indicate that the proposed GPPI-PCSS method could be used in light-field PTV technology to obtain accurate bubble velocity measurement results under the conditions of high bubble concentration and large bubble displacement.

In this research, based on virtual ECT sensors and flow-electric coupling simulation method, four typical oil gas two-phase flow patterns and their corresponding measurement signals were dynamically simulated. Time-series signals of pressure and capacitance were analyzed by applying multi-resolution analysis (MRA) and time-frequency analysis methods based on wavelet transform. Continuous wavelet transform can display the energy distribution in the time-frequency two-dimensional domain and effectively locate flow fluctuations. Based on the wavelet MRA method, the original signals were decomposed into different frequency bands within the same time range. As results, both pressure and capacitance signal analyses showed the similar migration pattern of main frequency banded from middle to low and then to high frequency with flow pattern changes, which provided flow pattern identification with a potential criterion. This method was validated through experimental measurements in the intermittent flow, effectively reflecting the changes in slug frequency, flow fluctuation, and liquid slug morphology under different flow rates. The research method and results in this paper are expected to provide reliable means for flow pattern identification and process monitoring in practical industrial processes.

Spraying technology is widely used in the fields of gas purification, dust control and chemical synthesis. Among them, droplet size control and improvement of spray uniformity are the challenges of this technology. For this reason, this paper intends to use surfactants to regulate the atomization characteristics of water mist to improve spray uniformity and further explore its promotion effect on fine particle removal. In this paper, an experimental study was conducted to analyze the atomization characteristics of three surfactants (sodium dodecylbenzene sulfonate, cetyltrimethylammonium bromide, and Tween 80) solutions with different properties, and to investigate the effects of surfactant type and concentration on the atomization characteristics. The results showed that compared with deionized water, the addition of surfactants could significantly improve the spray uniformity, the overall particle size of the spray decreased, and the nonionic surfactant Tween 80 (TW80) atomized the highest percentage of small droplets formed. The number of droplets of the three types of surfactant solutions peaked when the surfactant solution concentration reached the critical micelle concentration (CMC), which was taken as the optimal atomization concentration. In addition, the fine particulate removal experiments by spraying showed that spraying with surfactant solutions could accelerate the removal rate of fine particulate.

Existing techniques for heat flux field measurement are mainly limited to low resolution, slow transient response, and high cost. To solve this problem, a new technique for heat flux field measurement is proposed. Quantum dots are nanoscale photoluminescent semiconductor materials whose photoluminescence spectral intensity shows a linear trend with temperature. Based on this effect, a dual-film quantum dots sample was designed and fabricated, and an experimental system for heat flux field measurement was constructed. Through calibration and measurement experiments, the study demonstrates that the average photoluminescence intensity of the quantum dots film declines linearly with increasing temperature within the tested range. The average heat flux of the bottom during the thermal evaporation of the pure water droplet in 10s under the experimental conditions was measured to be about 3.4×10⁴W/m². And the uncertainty of the heat flux measurement was calculated to be 0.14. The spatial resolution of this method can be up to the 30μm level, and the response time is of the second level, which realizes the high-resolution and low-delay measurement of the heat flux field on the surface. Based on the advantages of high resolution and low latency, this study holds significant potential for challenging testing environments where traditional methods fall short, such as rotating blades, high-speed aircraft, and micro- and nano-components.

The proposal for achieving China's carbon dioxide peaking and carbon neutrality target has spurred progress in the green and low-carbon industries. The development of the hydrogen industry, particularly the use of green hydrogen in transportation, chemical industry, power industry and other fields, would be an effective strategy for achieving the “dual carbon” goals. Based on a recent comparative analysis of hydrogen industry development in the United States, European Union, Japan and China, a path for developing China's hydrogen industry was presented in this paper. Based on lessons learned from the advanced hydrogen industry development policies of developed countries, it was proposed that China should rely on its own national circumstances and establish a hydrogen industry chain from production, storage, transportation, refueling station construction to multi applications. Furthermore, it should be essential to expand the diversified use of green hydrogen, considering its attributes as a green energy source, green material and green ingredient. Additionally, it was recommended that China strengthened international cooperation to drive progress in crucial areas of technology, created worldwide standards surrounding hydrogen to foster development of the hydrogen sector and tackled the global warming problem.

Smart plant is an important way to develop smart manufacturing and achieve green and sustainable transformation in petrochemical industry. This paper proposed the planning of edge cloud platform and the key business scenarios to be built in the future construction of petrochemical smart plant from both business and technical aspects, and designed the technical methods for each scenario by combining data analysis and artificial intelligence, mainly including production planning and scheduling based on data and mechanism integration modeling, multi-objective evolutionary learning for modeling production process and operation optimization, smart operation monitoring and fault diagnosis for production equipment. The research results of this paper were of great significance to promote the construction of petrochemical smart plant and to realize the improvement of core capabilities such as intelligent petrochemical production control, intelligent quality control and intelligent equipment control.

In the 21st century, as China continues to witness a proliferation of chemical production facilities, the generation of oxygen-containing organic gases in various chemical processes has emerged as a critical concern. The safe disposal of these gases through deoxidation has become a pivotal challenge. However, the development of deoxidation technology faces numerous challenges, primarily due to the variability of conditions, intricate compositions, and substantial variations in deoxidation depth. This paper summarizes the application and recent research progress of chemical deoxidation technology of O₂-containing organic gases in chemical processes. The applicability and technical competitiveness for various technologies are analyzed based on the deoxidation requirements in different situations. In view of the high oxygen content, large flux and continuous O₂-containing gas deoxidation formed in chemical production process, it is pointed out that catalytic deoxidation exhibits distinct advantages of short process, strong operability and excellent deoxidation performance, which is more competitive in the current practical industrial application. Concurrently, it is imperative to focus on achieving deep deoxidation, addressing high-O₂-content gases, as well as implementing mild deoxidation techniques.

Rayleigh convection phenomenon caused by interfacial concentration gradient can significantly improve the mass transfer rate of CO₂ absorption process, but the mechanism of mass transfer enhancement in this process is not clear at present. In order to explore the enhancement mechanism of Rayleigh convection mass transfer process, water absorbing CO₂ process was selected as the research object, and realized the visualization and quantitative measurement of interfacial convection based on particle image velocimetry (PIV) and laser induced fluorescence (LIF) technology under different CO₂ partial pressure conditions. It was found that the average interface concentration would drop instantaneously at the critical time of the convection and would rise after the formation of the ordered self-organization structure, the final average interface concentration would descend with the decrease of CO₂ partial pressure in gas phase. After convection, the mass transfer capacity enhancement of the system was divided into two stages, vorticity field played a leading role before the formation of the ordered self-organization structure, but after the formation of the ordered self-organization structure, the mass transfer capacity enhancement was the result of the joint action of vorticity field and interface concentration. After the formation of the ordered self-organization structure, the average instantaneous mass transfer coefficients of different systems had a strong correlation with the corresponding average vorticity, indicating that the vorticity field formed by the interaction of concentration field and velocity field played an important role in the process of convective mass transfer enhancement.

With large-scale renewable power integrated into the grid, the status of traditional thermal power units as energy allocation has been significantly enhanced. The safety and stability of boiler peak-shaving operation become more and more important. This work coupled the heat absorption with the hydrodynamic characteristics and forms the temperature calculation model of water-cooled wall. Meanwhile, a SO _x generation model was developed to determine the process of the fuel sulfur release in a reducing atmosphere and the mutual transformation of sulfur components. Based on the numerical simulation of furnace, the temperature calculation model of water-cooled wall and the tube wall high-temperature corrosion model with time dimension, a high-temperature corrosion prediction model of water-cooled wall for boiler peak-shaving operation was proposed. The corresponding software was also developed using the Matlab GUI platform. A supercritical 600MW tangentially coal-fired boiler was selected as the research object. The results showed that the accuracies of the wall temperature distribution and H₂S concentration distribution near the wall obtained by coupling calculation of wall temperature and SO _x generation model were high, which provided a good basis for accurate prediction of high-temperature corrosion. The high-temperature corrosion characteristics of the water-cooled wall under different loads were different. The corrosion degree of the water-cooled wall decreases with the decrease of the boiler loaded as a whole. The area of front wall between the burner zone and SOFA zone was the most severely corroded under 100% BMCR and 75% THA load, with maximum corrosion depths of 276μm and 233μm per year, respectively. The high-temperature corrosion depths under 50% THA and 35% BMCR load rapidly increased to a maximum in the top of the burner zone, which were 224μm and 256μm per year, respectively. The high-temperature corrosion state of the water-cooled wall under multiple working operation was manifested as the spatio-temporal superposition of the corrosion state of each working condition. The spatio-temporal distribution of the high-temperature corrosion state of water-cooled wall could be predicted by boiler operation parameters and operation time through the prediction software.

Based on the flow heat transfer experimental data, the ability of different turbulence models to predict heat transfer on supercritical CO₂(S-CO₂) was evaluated and selected, and the SST k-ω turbulence model was confirmed as the optimal model. The effects of inlet temperature, heat flux, mass flux, buoyancy and flow acceleration on the convective heat transfer characteristics of S-CO₂ were analyzed in a vertical heating tube with an inner diameter of 10mm.The results showed that Bu<10^-5, Bu*<5.6×10^-7 and K_v<3×10^-6 were not satisfied in some working conditions, indicating the effects of buoyance and flow acceleration could not explain the heat transfer characteristic at high mass flux. Based on the supercritical boiling theory, the S-CO₂ boiling heat transfer model in vertical heating tube was established, and the deterioration of S-CO₂ heat transfer was described. The detailed distribution of S-CO₂ thermophysical properties and turbulence in the radial direction showed that the supercritical heat transfer was greatly affected by the thickness of the pseudo-gas film, the thermal properties of the quasi-gas film and the turbulent kinetic energy in the near-wall region. The heat transfer mechanism of S-CO₂ at high mass flux was explained successfully. By introducing the supercritical boiling number, a heat transfer correlation formula for high quality flow rate was proposed.

Hydrodesulfurization (HDS) catalyst is an indispensable part of hydrodesulfurization technology. Especially, as a typical hydrodesulfurization catalyst, the alumina supported metal sulfide catalyst is widely used in the industrial production. In this paper, the research progress of alumina supported metal sulfide catalyst, including the active phase model of the catalysts and the effects of various additives on the structure-activity relationship of hydrodesulfurization catalysts, is systematically reviewed. Thereinto, the research progress of active phase models, including 5 classical models, and their differences and correlations are emphatically discussed. Meanwhile, the effects of various additives (transition metals and main group elements including ⅠA, ⅡA, ⅢA, etc.) on the structure-activity relationship of hydrodesulfurization catalysts are discussed. Finally, the future development direction of hydrodesulfurization catalysts is prospected. Understanding the structure and morphology of the active phase and the complex catalytic mechanism of the catalyst on the atomic scale, creating controllably highly active and selective multi-functional catalysts with adjustable properties basing on the deep understanding of the catalytic mechanism and the active phase are important directions for hydrodesulfurization catalysts in the future.

The cotton fibers were pretreated with different concentrations of hydrochloric acid and then used as biological templates to prepare fibrous strip biomimetic Ru/Ba-MgO ammonia synthesis catalysts. The effect of cellulose hydrogen bonding in cotton fibers on Ru/Ba-MgO catalysts was investigated by characterization techniques such as XRD, FTIR, FE-SEM, EDS, BET, H₂-TPR and TG for cotton fibers, Ba-MgO carriers and Ru/Ba-MgO catalysts. The results showed that H⁺ in hydrochloric acid solution would break the intra-cellulose molecular hydrogen bonds in cotton fibers, which exposed a large number of highly reactive hydroxyl groups within the cellulose and enhanced the adsorption of Mg²⁺and Ba²⁺, and the specific surface area of the Ba-MgO carriers increased significantly and the pore size decreased significantly. Pretreatment of cotton fibers with suitable concentrations of hydrochloric acid can effectively regulate the particle size of the active component Ru in the catalyst and its dispersion, while the incorporation of co-catalyst Ba inhibited the production of RuO _x and improved the reduction performance of Ru/Ba-MgO catalyst, which ultimately led to the improvement of ammonia synthesis activity and thermal stability of Ru/Ba-MgO catalyst. When cotton fibers were pretreated with 3mol/L hydrochloric acid solution, the prepared Ru/Ba-MgO-3 catalyst had the best activity at 425℃, 10MPa and 10000h^-1 reaction conditions with an outlet ammonia volume concentration of 18.37%.

The development of electrochemical energy storage technologies and the large-scale application of electric vehicles are critical for the reduction of carbon emissions. Lithium-ion batteries are the core components of electric energy storage technologies and electric vehicles with high energy density and long cycle life, yet their capacity is mainly limited by cathode materials. Ternary cathode materials have the advantages of light pollution, low cost, high performance and large capacity. However, the conventional wet chemistry and high-temperature solid-state methods are usually multi-step procedures and time-consuming, which are the major hurdlers for commercialization. The flame spray pyrolysis (FSP) method has attracted wide attention, given that it can produce ternary cathode materials in one step without waste produced during the synthesis process and thus has little impact on the environment. The present study reviewed the research progress in the preparation of ternary cathode materials by FSP method in recent years. Firstly, the history, advantages, basic principles and typical devices of FSP were briefly introduced. Secondly, the effects of precursor solution composition, synthesis temperature and annealing conditions on the composition, structure, morphology and electrochemical properties of ternary cathode materials were analyzed. Then, the recent research progress in the modification and deposition technologies of terpolymer cathode materials was briefly described. Finally, the future development trend of ternary cathode materials prepared by FSP was prospected.

With the continuous promotion of ecological civilization construction, various oil-water separation materials and methods emerge as the times require in order to achieve efficient clean protection of oil-contaminated water. Modified melamine sponge is widely used in the field of oil-water separation due to its unique three-dimensional ultra-wetting characteristics. In this paper, the mechanism of ultra-wettable oil-water separation was outlined, the research progress of melamine sponge in the field of oil-water separation was discussed, and the materials and methods of hydrophobic modification of melamine sponge in recent years were summarized as well as some special properties, such as magnetism and corrosion resistance, which were endowed with melamine sponge after modification. At the same time, the above materials and methods were evaluated objectively, and the development direction of oil-water separation and hydrophobic modified melamine sponge were prospected, providing reference for promoting the application of low-cost and high-performance hydrophobic modified technology of melamine sponge in oily wastewater treatment.

With the rapid development of China's aerospace and electronics industries, high-performance pitch-based carbon fibers have attracted more and more attention because of its excellent properties such as high modulus and excellent thermal conductivity. Among these steps, the preparation of mesophase asphalt is the first step in the preparation of high-performance pitch-based carbon fibers. However, due to the complex structure of pitch and more heteroatoms, the properties of mesophase pitch products are not uniform. These facts lead to the situation that the industrial-scale production of spinning grade mesophase pitch has not yet been achieved in China, and thus seriously restricts the development of related industries. In this paper, the formation process and properties of mesophase pitch were reviewed. The composition and molecular structure of coal, petroleum and naphthalene were compared. The effects of complex components in raw pitch on the formation process of mesophase pitch and the common pretreatment methods were described, and the advantages and disadvantages of pretreatment methods were compared. The preparation process, advantages and disadvantages of direct thermal polycondensation, solvent separation, hydrogenation modification, catalytic modification, co-carbon method and other methods were analyzed, and the influencing factors in the formation of mesophase pitch were summarized. Finally, the development prospect of mesophase pitch was prospected, and suggestions were proposed to the current bottleneck problems. Researchers should start from the source of pitch raw materials to explore the influencing rules of their molecular structure and process conditions on the structure of mesophase pitch, and illuminate the proposed mechanism.

Lignin based porous carbon have been widely studied as the electrode materials for supercapacitors device owing to its low-cost, renewable and simple preparation process. In this paper, lignin nanoparticles (LNP) isolated from wheat straw biomass was used as the carbon precursor, pretreated by activation with ZnCO₃, and then prepared to LNP based hierarchical porous carbon (LPC) through slow pyrolysis at different temperatures (600—800℃). Furthermore, in-situ growth of δ-MnO₂ was loaded onto the surfaces of LPC by the lights of solution reaction method. The resultant MnO₂/LPC nanocomposite with three-dimensional (3D) nano-lamellar structure was successfully synthesized. The micromorphology, chemical composition, and electrochemical performances of MnO₂/LPC were characterized by means of SEM, XRD, FTIR and electrochemical tests. The study results suggested that the behaviors of MnO₂in-situ growing on LPC were significantly affected by the pyrolysis temperature of LPC preparation. As the pyrolysis temperature of LPC increased from 600℃ to 800℃, the pattern of δ-MnO₂ nanocrystals evolved from the clustered particles to 3D cross-linked porous lamellar nanostructure. In addition, the as-prepared MnO₂/LPC electrode had shown excellent electrochemical performances. The specific capacitance of MnO₂/LPC at 800℃ could reach 145F/g at 1A/g, yet maintained 110F/g as the current density increasing to 5A/g, indicating that it had also a better rate performance (75.9%). Meanwhile, the symmetric supercapacitor assembled from this composite material had a high specific capacitance of 87F/g and energy density of 3.03W·h/kg in the two electrode system.

Current conductive hydrogel materials have many shortcomings in practical application, and thus it is of great significance to design and prepare a hydrogel with high strength, high adhesion and high conductivity. Graphene oxide (GO) was used as synergistic component and introduced into the hydrogel matrix fabricated by N-hydroxysuccinimide (NHS) grafted polyacrylic acid (PAA). Subsequently, PAA-NHS/GO composite hydrogels were prepared by a photoinitiated one-step polymerization method. The introduction of GO improved the crosslinking degree of the hydrogel system, increased the stability of the hydrogel and endowed it with high conductivity. The tensile strength, elongation at break and conductivity of PAA-NHS/GO could reach 0.336MPa, 302.6% and 0.93S/m, respectively. The functional groups of the composite hydrogel could generate strong adhesion effect with the tissue surface, and the adhesion strength could reach to more than 40kPa. Additionally, PAA-NHS/GO possessed high biosafety and excellent biocompatibility. The composite hydrogel exhibited the ability of stable deformation sensing under external force. When used for electrocardiosignal (ECG) signal monitoring, the composite hydrogel showed high sensitivity and could achieve stable and clear signal transmission. As a novel conductive and adhesive hydrogel, PAA-NHS/GO was expected to be used in the fields of flexible wearable devices, biosensor and electronic skin.

The enzymatic hydrolysis lignin obtained from biorefinery industry retains the structural characteristics of the original lignin with rich active groups such as alcohol hydroxyl and phenolic hydroxyl, which can be used in the preparation of phenolic resin. The purity, alcohol hydroxylic group and the phenolic hydroxyl group were investigated for the synthesis and application properties of phenol-formaldehyde resin (PF). Limited by the complexity of the lignin structure,the reaction process could not be effectively tracked and optimized. The preparation process of lignin-PF was optimized by online ReactIR equipment, and the change pattern of formaldehyde amount in the system was studied by the infrared absorption peak of 1020cm^-1. The results showed that adding formaldehyde and sodium hydroxide in a multistep reaction with the system pH above 10.5 promoted the synthesis of the phenolic resin. When the ideal polymerization temperature was controlled at 88—95℃ and the maximum amount of lignin was added at 60%,the bonding strength of phenolic resin adhesive (0.90MPa) and the lowest formaldehyde release (0.142mg/L) could reach the E0 and I specified standard.

Linear polysulfide (P1) with a vinyl side group was obtained by ring-opening polymerization of 1-allyl oxygen-2,3-cyclothiopropane, which was then water-soluble by the introduction of sufficient carboxyl group by thiol-olefin click. Modified linear polysulfide (P2) reduced silver nitrate in situ to silver nanoparticles (Ag NPs), which was used as antibacterial agents. TEM test showed that Ag NPs were successfully prepared with the particle size of 5—20nm. Moreover, XPS analysis proved that Ag NPs formed a silver-sulfur coordination bond with sulfur element in P2 polymer chain. The composite crosslinking agent (Ag NPs@P2) was formed by the Ag-S coordination of P2 and Ag NPs, and with the initiation of potassium persulfate (KPS), the antibacterial hydrogel was prepared by free radical polymerization with acrylamide (Am) and Ag NPs@P2. The antibacterial experiments on Escherichia coli indicated that Ag NPs@P2/PAm had the synergistic antibacterial capability, and Ag NPs@P2 loaded with mass fraction of 2% had the best bacteriostatic effect. The hydrogels overcome the resistance problem of traditional antibiotic hydrogels and the poor compatibility of inorganic and organic components, and provided a new strategy for the design of novel synergistic antibacterial hydrogels.

In this work, a thermoplastic elastomer blend (TPV) with irradiation resistance for medical devices was prepared by the dynamic vulcanization of the blends of brominized poly(isobutene-co-p-methylstyrene) (BIMS) and styrene ethylene butylene styrene copolymer (SEBS). Besides, alkyl phenol disulfide was used as vulcanizing crosslinker and bio-based plasticizer was also added. After irradiated by different doses, basic physicochemical properties, headspace gas chromatography, Fourier transform infrared spectra, thermal stability, dynamic mechanical properties and mechanical properties of irradiated TPV were analyzed. The experimental results indicated that the performance of TPV irradiated within 40kGy dose did not change which met the irradiation resistance requirements of the normal elastomers for medical devices.

The ionic liquids 1-ethyl-3-methylimidazolium methyl phosphonate ([Emim][OMP]) and 1-ethyl-3-methylimidazolium ethyl phosphonate ([Emim][OMP]) were synthesized and characterized by nuclear magnetic resonance and elemental analysis. The thermal stability, phase behavior, density and viscosity (293.15—353.15K), and conductivity and surface tension (293.15—343.15K) were measured at atmospheric pressure, and correlated with established empirical equations. Some thermophysical properties such as the isobaric thermal expansion coefficients, molecular volume, standard entropy and lattice potential energy were determined using the measured density data, while the surface excess energy and entropy were estimated using the measured surface tension data. The thermal gravimetric analysis showed that the thermal decomposition temperatures (T_onset) of [Emim][OMP] and [Emim][OMP] were 271.0℃ and 259.2℃, respectively. Differential scanning calorimetry results revealed that [Emim][OMP] and [Emim][OEP] had no melting or freezing points, but only glass-transition temperatures (T_g), and the T_g of [Emim][OMP] and [Emim][OEP] were -84.87℃ and -85.00℃, respectively. The Walden rule analysis demonstrated that [Emim][OMP] and [Emim][OEP] ionic liquids complied with the Walden rule well, and were classified as "good ionic liquids".

1,2,4-Butanetriol (BT) is one of the high value-added compounds widely used in various fields, and the production of BT by fermentation using cellulose hydrolysate requires a strain that can tolerate the inhibitors present in the hydrolysate. In the presence of furfural, a common inhibitor in hydrolysates, the fermentation of Escherichia coli is severely limited. In this study, four furfural tolerance genes, yghA, thyA, mdtJI, and pntAB were overexpressed in the BT-producingstrain. In the presence of 0.4g/L furfural, all modified strains showed different degrees of growth. Among them, the strain overexpressing pntAB had the best growth, which also contributed to the enzymatic activity or transcriptional level of the enzymes in the BT pathway, yielding 11.0g/L BT. When corncob cellulose hydrolysate was used as the substrate, the strains overexpressing yghA, thyA, and pntAB all significantly improved the growth and BT production. The strain carrying yghA performed the best, yielding 3.36g/L BT in shake flasks and 15.3g/L BT in 5L fermenters, with a conversion of 63.8%. This strategy provided a reference for BT production by fermentation of corncob cellulose hydrolysate.

Herbicides have been used extensively in modern agricultural production, but the long-term application of herbicides has resulted in a large amount of residues in the soil, which pollutes water through precipitation, leaching and runoff, thus causing environmental pollution and food safety issues. Biochar, as a kind of green and efficient adsorbent, has been widely used for the remediation of organic-polluted water and soil. This review summarized the modification methods of biochar, such as acid-base, organic matter, and metal salt dipping, nano zero-valent iron and microbial load modification. The application of modified biochar in the remediation of herbicide pollution was introduced, and the remediation effects of pristine and modified biochar were compared and analyzed. The effects of modified biochar characteristics and environmental conditions on the remediation of herbicide pollution and their mechanism were discussed. In the future, the stability, long-term performance, and safety of modified biochar in the remediation process of herbicide pollution still need to be explored.

The pitch-based spherical activated carbon was used as support to load different amounts of citric acid into its pores by equivalent-volume impregnation method. The effect of citric acid modification on the activated carbon's ammonia adsorption was evaluated by a fixed bed dynamic adsorption device. The physicochemical properties of activated carbon before and after modification were characterized by SEM, XRD, FTIR, nitrogen adsorption and desorption. The results showed that the modified activated carbon had the best ammonia adsorption performance when the load of citric acid was 60%. The ammonia protection time was 194min, and the ammonia adsorption capacity was 42.8mg/mL (66.8mg/g), which was 24 times that of unmodified activated carbon. The total specific surface area, pore volume and pH of the adsorbent decreased with the increase of citric acid loading, and the correlation coefficients R² between the specific surface area and pore volume of the adsorbent, and citric acid loading were 0.9944 and 0.9842, respectively. As the loading capacity increased, the utilization rate of citric acid decreased. Ammonia reacted with citric acid to produce ammonium citrate. The products were mainly deposited in micropores, which were crucial for ammonia adsorption.

A membrane-contact ozone (O₃) mass transfer technology was developed by assembling hydrophobic PTFE hollow fiber membrane into a membrane contactor. The differences between bubble mass transfer and membrane contact mass transfer were compared. The main influencing factors and mass transfer mechanism of the technology were studied by O₃ mass transfer model and resistance model. The results showed that O₃ can be effectively transferred through the hydrophobic PTFE membrane. When the stirring speed reached 1500r/min, the apparent mass transfer coefficient of membrane mass transfer (0.3049min^-1) was comparable to that of bubble mass transfer (0.3109min^-1). At the same time, the hydrophobic structure of the membrane surface reduced the humidity of the exhaust gas to below 0.8g/m³, which was much lower than the bubble mass transfer (>11.5g/m³), which met the standard of entering the ozone generator and had the feasibility of recovering oxygen. The mass transfer flux of O₃ was affected by liquid flow rate, pH value, pollutant concentration, gas flow rate and inlet O₃ concentration. When pH=11, phenol concentration was 0 or pH=7, phenol concentration was 20mg/L, the mass transfer flux reached 0.16g/(m²·h). The mass transfer resistance of the O₃ mass transfer process was mainly composed of membrane resistance and liquid phase resistance, and the liquid phase resistance can be effectively reduced by controlling the liquid phase conditions. Therefore, further reducing the mass transfer resistance required the development of membrane technology.

The effect of low intensity ultrasound on the treatment of high-ammonia-nitrogen wastewater by Anammox-EGSB reactor was studied. The effects of ultrasound treatment on the nitrogen removal performance of the reactor, characteristics of Anammox granular sludge, extracellular polymer and microbial flora were investigated. The results showed that low intensity ultrasound could improve the nitrogen removal efficiency of Anammox reactor, and the nitrogen load of influent was 6.03kg N/(m³·d), the total nitrogen removal rate of ultrasonic group was increased by 11.40%, and the impact resistance of nitrogen load was also enhanced. After periodic ultrasonic irradiation, the particle size of granular sludge was maintained at 1.0—1.5mm, which was beneficial to improve mass transfer efficiency, enhance the activity of Anammox granular sludge and reduce particle floating. The total amount of EPS of sludge in ultrasonic group increased significantly, and the increase of TB-EPS was more obvious, which was helpful to maintain the structural stability of granular sludge. The types of functional groups on the sludge surface remained unchanged, but the groups such as hydroxyl, carboxyl, and amino groups increased. The specific Anammox activity of granular sludge increased by 33.2%. Through the simplified Gompertz equation model, it was found that the growth rate of Anammox bacteria in the ultrasonic group (0.0127d^-1) was higher than that in the control group (0.0107d^-1). High-throughput sequencing showed that ultrasound promoted Anammox bacteria and their symbiotic bacteria, among which Candidatus Brocadia increased by 22.03%. At the same time, some denitrifying bacteria were seriously inhibited, so that the substrate and living space of Anammox bacteria were more sufficient.