In the pursuit of high efficiency, compact and light aviation fuel heat exchanger, various working conditions and structural parameters affecting the heat transfer and pressure performance of mini channel were explored and optimized. By using orthogonal design of Taguchi method and loss function analysis, the contribution and influence of different factors on the performance index were obtained, and the conclusion was proved to be statistically significant by additivity test. The results showed that the inlet velocity and channel flow pattern contribute the most to the heat transfer and pressure performance of the mini channel, and the cylindrical vortex generator channel could obtain the best comprehensive performance. In addition, it was found that the change of physical property of the working medium in the process of heat transfer would affect the calculation of Prandtl number, resulting in different influence laws and different optimization parameter combinations of various evaluation indexes of heat transfer pressure and comprehensive performance. Therefore, it was necessary to select appropriate evaluation indexes according to practical problems.

In order to further improve the heat dissipation performance of microchannel heat sink (MCHS) with equal cross-section, a two inlet ports-one outlet port MCHS was proposed in this paper. The flow and heat transfer characteristics in MCHS where the inlet ports were arranged at the upper side or the left side walls with different angles were analyzed by numerical simulation. The results showed that the layout of inlet and outlet ports had a great influence on flow distribution of each channel in the microchannel heat sink, and the temperature distribution was directly influenced by flow distribution. When the inlet ports are located at side walls of the heat sink, the fluid distribution was more uniform, and the thermal resistance and pump work of heat sink were smaller. The decrease of inlet ports angle reduced the bottom temperature of MCHS and made the bottom temperature more uniform. When Re was at 365, the maximum plate temperature at θ=45° was 1.91℃ lower than that at θ=90°, but the pumping power increased significantly.

The characteristics of fluid injection process under transcritical/supercritical conditions which are different from the subcritical conditions were explored by using an improved phase-shifting interferometer with high temporal and spatial resolution. The transient density field of the phase transition interface in the process under different trans/supercritical injection was measured. The phase shift interferometer adopted the basic arrangement of the Mach-Zehnder type interferometer. Through the pixelated-array masked method, the multi-phase interference images could be obtained by a sensor. The spatial resolution reached 3.45μm, and the time resolution achieved was 0.001s. In the experiment, the phase-shifting interferometer was used to realize the visual study of the injection processes from liquid to supercritical phase and from supercritical to gas phase, the transient density field was quantitatively measured in real time. The results showed that when the liquid-phase fluid jet into the supercritical environment, the jet interface will not produce tiny droplets similar to the subcritical conditions. When the liquid-phase fluid jets into a supercritical environment (p_r=1.01, Re=79.738), the jet interface did not produce tiny droplets similar to subcritical conditions, but a highly wrinkled phase equilibrium layer appeared at the edge, and the results are consistent with the literature. The density of the jet fluid at the bottom in the visible cavity was initially at 712.82kg/m³. As the jet progressed, it interacts with the surrounding low-density fluid, which made the density decrease to 310kg/m³. When the supercritical fluid jet into the gas phase environment (p_r=0.98, Re=87.340), the interface of the injection was broken. As the high-density jet fluid (314.99kg/m³) flowed upward from the bottom, the density at the bottom gradually decreased to 288.12kg/m³. There was a large density gradient in the normal direction of the phase change interface, with the maximum value of 1.565×10⁴kg/m⁴.

The high water-cut oil-water two-phase flow in the oil field is complex and usually exists in closed pipelines, so it is difficult for on-line measurement. In this paper, a dual-parameter measurement method of high water-cut oil-water two-phase flow based on phase-isolation was proposed. The small, dispersed oil droplets that were difficult to measure were concentrated to the center of the pipeline by the cyclone to form the phase-isolation with a phase distribution of oil core-water ring. The axial differential pressure and the radial differential pressure were introduced and the experimental correlation of the ratio of the two differential pressures was established. Then the total flow rate and water-cut were measured combined electromagnetic flowmeter with differential pressure method. The pressure taking position was optimized by numerical simulation method. And the double-parameter measurement experiment was carried out in oil-water two-phase flow. The results showed that the measurement errors of the total oil-water flow rate and the water-cut were both within ±5% in the range of 84%—100% water-cut. This work provides a new dual-parameter measurement method and theoretical guidance for on-line measurement of high water-cut oil-water two-phase flow.

Erosion corrosion, which is affected by many factors, is one of the typical problems leading to local failures of long-distance crude oil pipelines. In order to study the influence of multi factors on erosion corrosion of pipeline steel, erosion corrosion loss of X80 Pipeline Steel with different particle concentration, impact angle, chloride ion concentration and pH were quantitatively compared by full factor experimental design method. The significance of single factor and interaction between factors were analyzed. The results showed that factors named above had significant effects on erosion corrosion loss, in which particle concentration and chloride ion concentration were positive effects, while pH and impact angle were negative effects. For cross effects among those four factors, only the interaction between particle concentration and chloride ion concentration and the interaction between particle concentration and impact angle were significant. In addition, the factors were arranged in order according to the significance of their effects on erosion corrosion weight loss of X80 pipeline steel. The material loss modes under different condition were analyzed through micrograph and interaction mechanism between factors was discussed and explained by schematic diagrams.

Annular mist flow is a kind of flow pattern widely existing in the field of petrochemical industry, and the measurement of its internal flow field measurement is of great significance. Combined with optical image method and high-speed photography technology, the atomization characteristics of the impaction-pin nozzle were measured. On this basis, the characteristics of the entrainment droplets in the Annular mist flow based on atomization mixing were studied. The spray morphology was visualized by high-speed photography, and the morphological changes were described visually. The single-frame single-exposure method was used to extract the distributions of droplet size and velocity. It was found that the droplet velocity decreases with the increase of the axial distance, and the droplet velocity reaches a peak at about 10mm in the radial position at the same axial distance. The results also showed that the Sauter mean diameter (SMD) increased with the increase of nozzle aperture, and was negatively correlated with the mass flow rate of liquid phase and the pressure drop. In addition, under the same gas pressure condition, SMD decreased with the increase of gas flow rate, while it increased with the increase of gas pressure at the same gas flow rate. Finally, the dimensional analysis based SMD prediction model of annular mist flow droplets was established by introducing the interphase slip and pressure coefficient, with gas Weber number and liquid Reynolds number as the main influencing parameters, and the MAPE is 11.4672%.

In view of the lack of traceability method for liquid film parameters measurement of gas-liquid two-phase annular flow, an online liquid film extraction device and an entrainment rate measurement method based on liquid film mass flow measurement were designed in the present paper. Liquid film extraction device used ultrasonic ranging sensor to monitor the liquid level of the liquid storage tank in real time and feedback to the control system. In order to make the liquid film extraction rate controllable, the single chip controlled the switch of the pumping pump to adjust the internal and external differential pressure. By using a commutator, metering and waste pipeline switching could be achieved and the time interval between the two switches could be recorded. The extraction liquid film could be weighed by the liquid film mass flow measurement module with a high precision electronic balance. Combined with the above time interval and the measurement results of liquid mass flow meter, the liquid film mass flow rate and droplet entrainment could be measured. 75 Groups of real flow verification experiments were carried out in the small-diameter high-precision gas-liquid two-phase flow simulation device, and the measurement system was evaluated scientifically by analyzing the predictive results of two typical entrainment rate models. The results showed that the measurement results of liquid film mass flow rate and droplet entrainment were traceable with high measurement accuracy, which provides a reliable experimental test method for the study of liquid film flow characteristics in gas-liquid two-phase annular flow.

By applying computational fluid dynamics (CFD) method, the large eddy simulation (LES) and Lagrangian particle tracking technology were used to calculate the flow field characteristics in the Rushton turbine stirred tank and the movement behavior of three kinds of St particles. The mean flow field (tangential velocity, axial velocity and radial velocity), particle velocity and concentration distribution were in good agreement with the experiment, which verified the reliability of the numerical simulation. The results showed that the stirred flow field and particle movement presented the characteristics of circulating flow. When the rotation speed N was constant at 313r/min, the small particles of St=0.24 were almost evenly distributed. However, the followability of large particles of St=37.3 with the fluid was poor, the bottom deposition rate was high, and a certain particle blank zone appeared on the top of the vessel. A series of turbulent vortex structures were generated near the impeller, and due to the violent particle-wall collision, the granular temperature at this location was the highest. The migration of small particles (St=0.24) was mainly controlled by the trailing vortices behind the blades, and they were evenly distributed in the low vorticity zone. Due to the large inertia of large particles (St=37.3), their motion was no longer dominated by the vortex, and was quickly thrown to the side wall by the impeller. They passed through the high vortex zone formed by the trailing vortices, so the impeller had a poor agitating effect on nearby large particles.

The inertial impact mechanism between particles and wall surface is one of the main reasons for ash deposition, and there are few researches on the impact process of micron particles at home and abroad. In this paper, the impact process of a single particle impacting the particle powdery layer was numerically calculated. The dynamic model of the normal collision between particles and walls was established to study the collision process between the particle and wall (or particle). For the impact process between the particle and wall (or particle), the theoretical calculation results were consistent with the numerical calculation results in the case of undamped dissipation. The existence of damping dissipation increased the critical velocity when only the work of adhesive peeling was considered. On this basis, the particle motion after particle collision with powdery layer was studied. The normal impact process of particle-particle (adhesive) -wall surface became more complicated due to the addition of adhesive particles. It was found that when the incident velocity was greater than 0.7m/s, the adhesive particles would detach from the wall surface during the collision process between silica particles-silica particles (adhesion)-stainless steel surface.

Three-dimensional flow field measurement using microscopic imaging is the foundation of research in microchannel flow, and one difficulty lies in the measurement of particle depth position. Due to the limited depth of field of the microscope, most particles in the microchannel will be out of focus during imaging. In this paper, based on the principle of geometrical optics, the characteristics of asymmetric defocus was analyzed for microscopic imaging. A particle depth prediction model was built based on the Inception V3 convolutional neural network, and the simulated microscopic images of ten sizes of particles with diameters 1—10μm in the depth range of -50—50μm were generated by the optical ray tracing method. The particle depth prediction model was trained and used for prediction with these synthetic images. The results showed that the relative error of prediction for 1—3μm particles was within ±13%, and less than ±5% for 4—10μm particles. Finally, the microscopic images of polystyrene microspheres with sizes of 2.6μm and 5μm in the depth range of -50—50μm were captured in the microchannel, and the same depth prediction model was used for training and prediction. The relative errors of depth prediction for the two sizes of particles were less than ±15% and ±5%, respectively. The microscopic defocused imaging method based on deep learning can measure the depth position of particles in microchannel effectively, adding new ideas to the imaging method for flow field measurement technology.

Electrical resistance tomography (ERT) technology has the advantages of non-disturbance, non-radiation and visualization. Based on this technology, a visual on-line monitoring system was proposed in the present study, which can monitor the particle distribution of LIB cathode slurry. The ERT monitoring system included an impedance analyzer (IM3570, HIOKI), a computer (PC), a multiplexer (34970A, Agilent) and an 8-electrode sensor. In the experiment, the stirring speed of the stirrer was 720r/min, the stirring time was shorter than 360s, the frequency of excitation current was f=1kHz, and the amplitude was 1mA. Phase-to-phase excitation method was adopted for current input, and 20 sets of measured voltage data were obtained. In addition, PD-IPM algorithm based on total variation (TV) regularization reconstructed ERT image, and defined average \stackrel{—}{\sigma }_ave and standard deviation s of conductivity to quantitatively analyze ERT reconstructed image. In order to qualitatively and quantitatively verify the feasibility of ERT measurement system, scanning electron microscopy (SEM) method and electrical impedance spectroscopy (EIS) method were used respectively. Comparison results showed that ①ERT reconstructed image was basically consistent with SEM apparent topography image. When the stirring time t was less than 120s, the agglomeration of particles in SEM apparent morphology image was serious, and the color change in ERT reconstructed image was obvious. When t≥120s, the particles tended to disperse in the SEM image, and the color of ERT reconstructed image was single orange. And ② The variation of resistance Z' and reactance Z" of EIS was consistent with the variation of \stackrel{—}{\sigma }_ave and s, and the electrochemical characteristics of cathode paste could correspond to ERT reconstructed image. Therefore, the ERT-based dynamic visualization monitoring system of cathode slurry distribution characteristics was feasible and could be applied to online dynamic monitoring of cathode slurry preparation in practical engineering.

In this paper, the method and device for on-line measurement of the density and particle size of limestone/gypsum slurry in the flue gas desulfurization based on the ultrasonic attenuation method were studied. Improved differential evolution algorithm with adaptive control parameters was used for particle size inversion, and simulations showed that the improved differential evolution algorithm had higher accuracy. Non-contact measurement section was designed, and the independent transducer mode was adopted to realize non-destructive measurement. An experiment on the relationship between temperature and sound attenuation was carried out, and the method for correcting the sound attenuation value was proposed. A differential evolution algorithm with adaptive control parameters was studied for particle size inversion. Laboratory results verified that the maximum deviation between the concentration measurement results of the method and the concentration analysis result of the sampling method was 1.75%, and the minimum deviation was 0.59%. The test results of the power plant showed that the particle size measurement results of the proposed method were in good agreement with those of the microscope image method and laser particle size analyzer, and the maximum deviation was less than 17%. The density measurement results were in good agreement with the sampling method, the maximum repeatability deviation was only 0.23%, and the maximum deviation between the single measurement result and the sampling method was 0.26%. Both indicators were better than the measurement results of the differential pressure density meter, which could meet the requirements for online measurement of the density and particle size of the limestone/gypsum slurry in the flue gas desulfurization.

The internal flow fields of most mechanical equipment, such as heat exchanger, steam turbine, and gas turbine have the characteristics of narrow internal space and complex flow field. At present, the two-dimensional particle image velocimetry (PIV) method is usually used to measure this kind of flow field, which is difficult to reflect the real velocity distribution. At the same time, most of the three-dimensional flow field measurement systems are complex and expensive, and it is difficult to be applied to the measurement for narrow space. Therefore, a set of three-dimensional flow field measurement system based on three cameras was built in this paper. The low-speed flow field of cylindrical wakes in a rectangular water pipeline was measured using Tomographic PIV. The three-dimensional Karman vortex street flow field generated by the cylindrical was successfully observed and reconstructed. The measurement area was about 30mm×30mm×5mm, the three-dimensional spatial resolution reached 20voxels/mm, and the reprojection error was less than 0.5%. The results showed that the three-dimensional vector field measured by the three-camera Tomographic-PIV system could reasonably reflect the flow structure of the cylindrical wake. Compared with the traditional MART (multiplicative algebraic reconstruction technique) algorithm, MLOS (multiplicative line-of-sight) algorithm could effectively reduce the reconstruction time and achieve the same reconstruction accuracy. The measurement system could also be used in other low speed fluid experiments, and the arrangement of three cameras provided the possibility to measure the complex flow field in small space.

Because of the complexity and opacity of multi-phase flow, it has always been a difficult problem to study the axial behavior of the riser of the gas-solid circulation fluidized bed. In this paper, a 32-electrode three-dimensional electrical capacitance tomography (ECT) sensor with eight planes was used, each of which contained four electrodes. The imaging was analyzed at different aspect ratios (the ratio of axial length to sensor inner diameter) and different electrode coverage. The simulation results showed that the maximum aspect ratio was achieved under the condition of ensuring imaging quality when the aspect ratio was 8.3 and the electrode coverage reached 69%. A 32-channel 3D ECT data acquisition system with an imaging speed of 120 frames per second was developed to reveal the flow detail in the axial direction. The imaging results showed that when the superficial gas velocity U_fis 2.34m/s, the slug flow broke due to the decrease of drag force caused by the decrease of the difference between the gas velocity and the particle velocity. The experiment indicated that the ECVT system could reveal the dynamic characteristics of the three-dimension circulating fluidized bed (CFB).

The fluidized bed has good heat and mass transfer efficiency, which is widely used in pulverized coal combustion, pneumatic conveying and other occasions. However, the fluidized bed will produce a certain vicious flow during the working process. Pulse vibration energy can effectively improve the heat transfer co-efficiency of the fluidized bed and reduce the occurrence of vicious flow. Therefore, an olefin fluidized bed experimental platform was designed and built, and a mixed pulsed gas flow was introduced. The bubble behavior was obtained by changing the relevant parameters of the pulsed airflow to analyze the power spectral density function of the electrostatic signal. The bubble size was estimated based on the electrostatic signal. The experimental results showed that the addition of pulsed airflow had a certain effect on the bubble size. As the pulse frequency increases, the bubble size would first decrease and then increase, and it reached the minimum when the pulse frequency was about 0.5Hz. Moreover, the addition of the pulsed airflow reduces the bubble size and improved the particle fluidization effect, so the agglomerated particles quality was significantly reduced after the completion of fluidization in the olefin fluidized bed.

In laminar mixing, the periodic perturbation of the impeller causes the enclosed and isolated annular flow field in the stirred tank. The isolated flow field seriously obstructs the effective exchange between the stirring medium and reduces the stirring efficiency. Therefore, an applied electric field was proposed in this paper to enhance the laminar mixing efficiency, and the electrohydrodynamic effect was employed to induce the polarization force of the mixed fluid. This effect changed the symmetrical structure of the flow field, and eliminated the isolated mixing regions. The real-time visualization of the flow field structure in the stirred tank was realized by using Planner laser induced fluorescence (PLIF) technology. The isolated flow region was identified and the percentage of the unmixed area was calculated in post-image processing by custom-made functions. The results showed that the mixing efficiency could be gradually increased to 98% under the electric field intensity of 1.5kV/cm. In addition, the simulation platform based on finite element method and concentration diffusion model was established. Through the simulation analysis, it was found that the secondary eddy appeared once the applied electric field intensity upon to 0.5kV/cm. The secondary eddy interacted with the radial mixing flow which diminished the isolated flow region. Under the condition of constant electric field strength, periodic electric field can further improve the mixing efficiency. Periodic electric field can make the mixing efficiency reach more than 98%, when electric field was at 1kV/cm.

In this paper, mercury emissions from coal combustion and coal chlorination were investigated by using a tubular furnace. The results showed that the percentage of simple substance Hg⁰ and oxidized Hg²⁺ in the flue gas after the combustion of raw coal is 74.3% and 25.7%, respectively. With the addition of Cl, the proportion of Hg²⁺ in the flue gas increased. When the chlorine was 0.015%, 0.030% and 0.045%, the ratio of Hg²⁺ in the flue gas increased by 32.7%, 36.1% and 40%, respectively, with the increase of chlorine, and its oxidation of mercury was also enhanced. In the field engineering demonstration test, mercury in the hydraulitis in the desulfurized wastewater was utilized to achieve the purpose of desulfurization wastewater and the mercury in the flue gas. With the increase of the amount of desulfurization wastewater sprayed on coal, the proportion of Hg²⁺ in the flue gas entering the SCR and passing through the SCR increased. Since the adsorption capacity of fly ash to Hg²⁺ was higher than that of Hg⁰, the mercury removal efficiency of the electrostatic precipitation system was improved. However, desulfurization wastewater spray coal on the demellular efficiency of wet electric dust removal system was not affected. Conclusively, with increase in the amount of the desulfurization wastewater spray, removal efficiency of mercury by flue gas purification equipment of coal-fired units could be raised.

The removal process of flue gas pollutants in the environmental protection island system of a 600MW coal-fired power unit was modeled with ASPEN Plus. Simulations were carried out to perform sensitivity analysis of ammonia-nitrogen molar ratio, pH of the circulating slurry, desulfurization tower liquid-gas ratio, flue gas temperature and flue gas flow from the perspective of system engineering. Further the static response characteristics of the environmental protection island system to these parameters were obtained. Results showed that the molar ratio of NH₃ to nitrogen should be slightly higher than 0.92 to reduce operating costs and NH₃ escape in SCR reaction based on vanadium-titanium catalyst. When the amount of escaped NH₃ was within the allowable range, increasing the pH of the circulating slurry is beneficial to enhance desulfurization and increase gypsum production. At the same time, the liquid-gas ratio should be as low as possible to reduce operating costs and nevertheless was not lower than 8. Otherwise, the desulfurization efficiency will be greatly decreased. The flue gas temperature at the outlet of the economizer should be less than 350℃, and within the range of 310—350℃, the system showed a comprehensive better desulfurization and denitrification efficiency. The environmental protection island system had strong adaptability to flue gas flow changes. The simulation results provided a quantitative reference for the optimal operation and intelligent control of the environmental protection island system.

The superhydrophobic surface is a type of important materials to prevent the surface of fan blades from freezing under low-temperature conditions and ensure the safe operation of the plant. In this paper, myristate ethanol solution and copper sheet were used as precursors, and copper myristate was grown in-situ on the surface of copper sheets based on solvothermal method. The hydrophobic surface with different wettability was obtained by adjusting the precursor concentration and reaction time, in terms of controlling the wettability of the hydrophobic surface. In addition, the microstructure and distribution of copper myristate clusters were observed by scanning electron microscope (SEM). The lattice composition of the cluster powders was verified by X-ray diffraction (XRD). The surface wettability of the sample under different conditions was quantified by a contact angle meter. Results showed that the contact angle between the droplet and the copper sheet increases with the increasing copper myristate clusters density on the copper sheet surface, and the wettability of copper sheet decreases. The concentration of the myristate ethanol solution and the reaction time can significantly change the distribution of copper myristate and then alter the surface wettability. The change in the wettability of the hydrophobic surface is due to the Ostwald ripening promotes crystal growth, so that the “seeding” polymer on the surface gradually grows into copper myristate microflowers.

It is necessary to quickly and accurately reconstruct the three-dimensional flame temperature field by the multi-light field camera system. However, the sampling information collected by the light field camera is usually low-rank and most of them are redundant in direction. In this paper, a novel approach was proposed to optimize the sampling of the multi-light field camera system based on the feature rays selection. According to the distribution of ray and angle characteristics, the proposed approach performed rays selection to obtain representative feature rays, which reduced the light field sampling redundancy. The anti-noise ability and applicability of the proposed approach were evaluated through numerical simulations, and the ethylene diffusion bimodal flame temperature was reconstructed experimentally. Results showed that the proposed approach can be well applied in the multi-light field camera system. The optimized sampling not only reconstructed the flame temperature successfully even with different noise levels, but reduced reconstruction errors in partial voxels. The reconstruction time was shorter for the optimized sampling which was 1/14 of the original sampling. Meanwhile, the proposed approach also could reconstruct the ethylene diffusion bimodal flame temperature with high spatial and temporal resolution.

To solve the problem of low separation efficiency for small particle size , which restricts the deep improvement of the cyclone separation efficiency, the liquid-liquid hydrocyclone was chosen as the analysis object. The key physical factors affecting the separation efficiency were summarized, including the residence time of discrete phase in the swirl field, particle size of discrete phase, rotation radius of discrete phase from the central axis, tangential rotation velocity of discrete phase, and the whole separation process system. Specifically, it was first analyzed and summarized in this work the current technical measures to improve cyclone separation efficiency, such as two-stage series hydrocyclone, dispersed phase coalescer, small-diameter hydrocyclone, and dynamic hydrocyclone that can increase the tangential velocity. Then, several new technical solutions to improve the separation efficiency were proposed from multiple aspects, which provides certain theoretical and technical support for the high-efficiency hydrocyclone design and system optimization for liquid-liquid, solid-liquid, gas-liquid, gas-liquid-solid and other multiphase mixtures.

The intelligent construction of the petrochemical industry is an important part of “Made in China 2025”. Strengthening the construction of CPS is an important guarantee for the realization of intelligence. Based on the CPS construction needs of a refining, this paper focuses on the modeling of transformation devices, and uses a hybrid modeling method to develop the model. Through the Aspen plus simulation of the production process and sensitivity analysis, a series of data were generated. A hybrid model was developed by mining the training set data to estimate the kinetic equation parameters of the R2204 reactor, and the model was validated using the prediction set data. Results showed that the relative deviation of the model in predicting the composition of CO at the reactor outlet was relatively small (the average deviation was 2.78%; the maximum deviation of a group does not exceed 10%), which proved that the model was reliable. Finally, based on this model, the temperature of the reactor inlet stream S2220 and the H₂O/CO ratio were optimized. Results showed that when the feed temperature was 201℃ and the H₂O/CO ratio was 51.35, the CO mole fraction at the outlet of the reactor was 0.406%, which met the technical production indicators. The model established by the hybrid modeling method in this paper can not only accurately predict the CO composition of the product composition of the reactor, but also can be integrated into the factory CPS system to provide a basis for subsequent decision-making optimization.

In order to enhance the comprehensive heat transfer performance of the spiral-winding tube heat exchanger, this paper presents a kind of vertically inserting space bars which is installed on the inner wall of the core tube of the spiral-winding tube heat exchanger along the radial direction. By means of numerical simulation, the flow and heat transfer performance of the spiral-winding tube heat exchanger with vertically inserting space bars were studied. Compared with traditional structure, it can also be used as a vortex generator while fixing the relative position of the tube bundle, affecting the wake field formed by the tube bundle, generating continuous turbulence on the boundary layer of the tube bundle, and enhancing the comprehensive heat transfer performance of the spiral-winding tube heat exchanger. Under the same imported conditions, the Nusselt number on the shell side of the spiral-winding tube heat exchanger with vertically inserting space bars was increased by 13.01% to 15.55% compared with the traditional structure, and the pressure drop is increased by 1.3% to 4.3%. And the comprehensive heat transfer performance can be increased by 7.4% to 10.5%. On this basis, the influence of different arrangements of the vertically inserting space bars on the flow and heat transfer performance was studied. The results showed that the comprehensive heat transfer performance of aligned arrangement was the best under the operating conditions of Reynolds number of 5000 to 24000, and the comprehensive heat transfer performance of staggered arrangement was the best under the operating conditions of Reynolds number of 24000 to 30000.

Self-inducing impeller is characterized by enhancing the mixing of multi-phase and homogeneous phase, which is widely used in the fields of chemical engineering and metallurgical engineering. In this article, a new type of self-inducing impeller was presented and its application in enhancing gas-liquid mixing and accelerating oxidation reaction rate was investigated. The influences of agitation speed, power consumption, tracer addition location, gas and liquid self-inducing behaviors on the mixing time were studied. The mixing time was determined by the change of the conductivity of the solution. The results indicated that the mixing time decreased with the increase of the stirring speed and remained relatively stable when the stirring speed exceeded the critical speed of 200r/min. Under the same condition, the self-inducing impeller, operated in gas suction mode at 200r/min, performed similarly with the common impeller running at 350r/min in the mixing time. In addition, when the input power was 0.27kW/m³, the self-inducing impeller operated in liquid suction got same mixing effect as the common impeller for over 1kW/m³. At the same time, the mechanism of the self-inducing impeller in the process of enhancing redox reaction was preliminarily explored with salicylic acid used as active oxygen collector. The result showed that hydroxyl radical was generated during the course of operation of the self-inducing impeller and the concentration of corresponding hydroxylated product reached 73.47μmol/L after 120min. Moreover, the application effect of the self-inducing impeller was systematically studied with ferrous iron as oxidant acceptor and the oxidation efficiency of ferrous iron as characterization parameter. The result suggested that the oxidation efficiency of the self-inducing impeller was better than that of aeration when the pH was 5.0. Under the condition of pH=4.0 and the common temperature, the oxidation efficiency of the self-inducing impeller was up to 30%, which was 10 times that of the conventional impeller. When the rotation speed was more than 300r/min, the increase of rotation speed had little effect on the end point of oxidation equilibrium, but had a great effect on the oxidation rate, that is, the oxidation rate of 400r/min was 30% higher than that of 300 r/min.

As a kind of flammable gas from by-products of ironmaking process, blast furnace gas (BFG) has obvious value of resource recovery, however, it has several problems such as low calorific value, complex composition, etc. What’s more, most current studies focus on removal of harmful components like carbonyl sulfide (COS), hydrogen sulfide (H₂S) and so on, but there are few studies or reports on the characteristic components of BFG. Researchers are not clear about the source and generation path of the characteristic components in BFG, and as a result, the interaction of complex components in BFG is neglected during the course of studies, which leads to problems frequently when the technologies are used in industry. In this paper, the source and generation path of characteristic components of BFG were expounded and analyzed, and then the influence of the characteristic components on desulfurization process is discussed. Complex chemical reactions take place between raw materials, fuels and air at high temperature, during the process of which, some characteristic components are produced and form raw gas together, such as dusts, N₂, O₂, CO, CO₂, H₂, CH₄, H₂O, HCl, HCN , sulfides etc. Chemical components such as O₂, CO_x, H₂, H₂O, HCl and sulfides in raw gas have an effect on the process of COS conversion or H₂S removal, and ultimately result in catalysts poisoning or conversion rate reduction. This paper provides some directions and references for the purification and recycling of BFG under the background of ultra-low emission by analyzing and discussing the regularity of interaction between characteristic components during the process of BFG generation and desulfurization.

Fast pyrolysis at high temperature and oxygen-free conditions generates bio-oil rich in high value-added chemicals and fuel components. Effective separation and extraction technologies play a vital role in bio-oil upgrading. In this paper, the properties of bio-oil and fast pyrolysis technologies are introduced, and much more attention are focused on various separation technologies such as distillation, liquid-liquid extraction, column chromatography, supercritical fluid extraction, membrane separation and so on, which are discussed in details. Traditional distillation and liquid-liquid extraction are technically mature and easy to be operated, but there are some problems such as poor thermal sensitivity of bio-oil, low solvent recovery and serious environmental pollution. Molecular distillation is safe and green, but its technical process is complicated and its equipment investment is high. Supercritical extraction and membrane separation are safe, environmentally friendly and technically mature, showing great potential in application. At the same time, research progress on the separation and extraction of multi-chemicals and single-chemical with high additional value is reviewed, which provides theoretical guidance for the effective separation and efficient utilization of bio-oil and points the way for the future development of bio-oil separation.

Organic Rankine cycle (ORC) power generation is one of the effective ways to convert medium and low temperature heat sources into high-grade electric energy. For the subcritical saturated organic Rankine cycle system with heat source temperature of 100—150℃, four kinds of organic working fluids are selected to study. Firstly, the variation trend of heat source temperature and working fluids on the exergy efficiency and heater exergy efficiency of single stage/two stage power generation system is analyzed, and then the influence of pinch temperature of two stage system on the exergy efficiency of system and heater is analyzed. The main conclusions are as follows: the exergy efficiency of dual cycle system and heater is significantly higher than that of single cycle system at the same heat source temperature, when R245fa is used as working fluid. For example, when the heat source temperature is 130℃, the exergy efficiency of the system is increased by 14.45%. The exergy efficiency of the system and heater decreases with the increase of the pinch temperature; when the pinch temperature increases at different heat source temperatures, the reduction of the exergy efficiency of the system and heater is nearly equal; when the narrow point temperature difference increases by 2℃, the exergy efficiency of the system decreases by about 1.9%. The exergy efficiency of the system and heater is analyzed when four kinds of organic working fluids are used in the dual cycle system, and the exergy efficiency increases with the increase of heat source temperature. When the temperature of heat source is 100℃ and 150℃, the difference of system exergy efficiency between working fluids R245fa and R601 is 0.89% and 3.54%, respectively, and the difference of exergy efficiency of the heater is 0.49% and 4.82%, respectively.

In order to reduce the production energy consumption and investment cost of hydrogen liquefaction plants and accelerate the development of hydrogen energy commercialization and civilian use in China, a novel dual-pressure Linde-Hampson (L-H) hydrogen liquefaction process using LNG pre-cooling is proposed. The designed liquid hydrogen output of the system is 5t/d and the method combining expansion and cooling with heat exchange is adopted to realize deep cooling of hydrogen. Aspen HYSYS software is used to carry out detailed simulation calculation and analysis for the process. The results show that the specific energy consumption and exergy efficiency of the hydrogen liquefaction process are 9.802 and 41.4%, respectively, and the total exergy loss of the process is 1373.3kW, of which the exergy loss of the heat exchange system accounts for the main part. It is found from the sensitivity analysis of the key parameters in the process that the change of the pre-compression pressure of the hydrogen in the range of 2—4MPa has a greater impact on the specific energy consumption and hydrogen liquefaction rate of the liquefaction process, while the pressure of LNG has little impact on the system. The novel hydrogen liquefaction process has simple equipment, low investment cost, and better liquefaction performance. It has advantages in the construction of small and medium-sized hydrogen liquefaction plants.

The Haber-Bosch process is of high energy consumption and high CO₂ emissions. Electro-catalytic nitrogen reduction reaction (NRR) is a novel process which works at room temperature and atmospheric pressure with N₂ input. It has the advantages of low cost, mild reaction conditions and environmental friendliness. However, due to its high overpotential, low current density and low selectivity, electrocatalytic NRR currently is still in the laboratory research stage. Particularly, the Faraday efficiency is severely limited by the hydrogen evolution reaction (HER). In this paper, we introduced the reaction mechanism of ammonia synthesis by electrocatalytic NRR. Moreover, we reviewed the competition mechanism between HER and NRR, mainly from the adsorption and activation of nitrogen and the specific reaction of electroreduction stages. This article focused on the latest research achievements in controlling HER by rational catalysts and reaction system design. Finally, we summarized the challenges in the development of electrocatalytic NRR for ammonia synthesis and gave the corresponding solutions. The potential application of electrocatalytic NRR ammonia synthesis under mild conditions is proposed.

Propylene is an important organic chemical feedstock and intermediate in organic chemical and petrochemical industry. In recent years, the demand in domestic and foreign markets has been increasing. The direct dehydrogenation of propane to propylene has the advantages of high yield, technological maturity, economic and environmental benefit, etc., and hence has attracted wide attention from researchers. Recent research progress of single-atom catalysts for direct dehydrogenation of propane to propylene is reviewed in this work. The dehydrogenation reaction mechanism of propane and catalyst deactivation with single-atom catalysts is discussed. The effects of active components, additives and carriers on the propane dehydrogenation performance of single-atom catalysts are summarized. And the existing problems of single-atom catalysts in current researches are also analyzed and discussed. Finally, in view of the fact that the single-atom catalysts have excellent propylene selectivity and stability but insufficient propane dehydrogenation activity, the principles for promoting the propane dehydrogenation activity of single-atom catalysts by adjusting the electronic structure are proposed, which provides guidance for the design of high-efficiency single-atom catalysts for dehydrogenation of propane to propylene in the future.

Alkylation of benzene with syngas was studied using a bi-functional ZnZr/HZSM-5 catalyst containing zinc oxide (ZnO), zirconium oxide (ZrO₂) and HZSM-5 zeolite. The catalyst was carefully characterized and the results showed that ZnO was the main active component for the synthesis of methanol while the addition of ZrO₂ not only helped the dispersion of ZnO but also generated large amount of oxygen vacancy that was beneficial to the adsorption and activation of CO. The combination of ZnO and ZrO₂ significantly affected the catalytic activity, and the highest ZnO dispersion and oxygen vacancy concentration were obtained when the solid solution (ZnZr_yO_x) was formed. The ZnZr₂O_x coupling with HZSM-5 zeolite with the mass ratio of 1∶2 exhibited the best catalytic performance, resulting in benzene conversion of 35.82%, CO conversion of 34.65%, and the total toluene and xylene selectivity of 85.24%.

This study used solvothermal method to synthesize two vanadium-doped bimetallic catalysts, and compared their heterogeneous Fenton degradation performance of Methylene blue. The samples were characterized by SEM, XRD, XPS, etc. The two catalysts showed good capacities for degradation of Methylene blue in both acidic to alkaline solutions (pH=3—10). The highest removal rate of Methylene blue by the Cu-V composite material was 95.60% at pH=10, while that by the Fe-V composite material reached 96.6% at pH=3. Both the Cu-V and Fe-V composite materials had good reusability. After six consecutive runs at pH=7, the removal rate of methylene blue remained at 79.16% and 68.22%, respectively. The mechanism of the catalytic reaction system has been preliminarily discussed. The hydroxyl radical is the main active species, but the catalytic mechanisms of the two catalysts are slightly different.

CO₂ and water vapor was converted into methanol with the catalyst of ZnO-ZrO₂ solid solution and the aid of negative corona plasma, which provided synergistic effect when employed together. The yield of methanol was 33.56μmol/h, which was 1.4 times of the sum of those under plasma alone and catalyst alone. The methanol yield increased with the increase of reaction current and steam flow rate, but decreased with the increase of CO₂ flow rate. The results of XRD, XPS and CO₂-TPD showed that the crystal plane spacing and oxygen vacancies of the catalyst increased under negative corona plasma condition, which enhanced the CO₂ adsorption on the catalyst. The CO₂-DRIFTs results showed that carboxylate (COO^-) was the main intermediate species during the methanol formation.

In order to improve the degradation of phenols in wastewater, a multi-needle plate catalysis system with high voltage pulsed gas-liquid two-phase discharge plasma was established for the removal of 4-chlorophenol. A series of catalysts were prepared and characterized, and the effects of various factors on 4-chlorophenol degradation were investigated by analysis of TOC, intermediate products and their concentrations in the degradation process. The results showed that catalyst roasting temperature and dosage had a great influence on the degradation rate of 4-chlorophenol. When the concentration of 4-chlorophenol was 150mg/L, under the conditions of electrode spacing 10mm, pulse voltage 26kV, pulse frequency 70Hz, aeration 4L/min, the discharge plasma with the Fe-TiO₂ catalyst of 0.05g calcinated at 500℃ gave the best degradation effect. The concentrations of byproducts such as p-phenol, p-benzoquinone and 4-chlorocatechol increased firstly and then decreased gradually and eventually disappeared with the increase of discharge time. Characterization results showed that the pulse discharge changed the crystal form and structure of the catalyst, and the Fe-TiO₂ modified with Fe had good catalytic performance, which further improved the degradation rate of 4-chlorophenol.

Silica (SiO₂) nanoparticles with small particle size and large specific surface area are widely used as fillers, paints, catalyst etc. However, due to the high surface energy and poor interface compatibility with polymer matrix, modification for the SiO₂ nanoparticles is necessary to solve the problems of the pool dispersion and easy agglomeration in application. Dopamine (DA) molecules possess the similar structure unit and strong adhesion as those of adhesive proteins secreted by mussels, and it can form polydopamine (PDA) coated layer on the surface of SiO₂ substrate in alkaline solution expeditiously, which results in the improvement of the chemical versatility and strong adhesion performance to substrate. PDA modification is a new modification method developed recently for particle surface. This paper reviewed the preparation and application of SiO₂@PDA nanoparticles and nanocomposite, as well as the secondary modification of SiO₂@PDA and the application. The characteristics and advantages of the PDA modification were summarized. The analysis indicated that SiO₂@PDA particle surface can easily graft functional polymer molecules and load metal nanoparticles, which expanded the multifunctional application of SiO₂ nanoparticles. However, the surface reaction mechanism, deposition kinetics and polymerization mechanism of SiO₂@PDA nanoparticles still needed to be further studied.

Starch is a kind of renewable natural macromolecule, possessing the advantages of good biocompatibility, biodegradation and non-toxicity, while hydrogel is a hydrophilic polymer network with the properties of water absorption and retention. In order to facilitate the researchers to understand the latest research progress of starch-based hydrogels, this paper summarized the research achievements of starch-based hydrogels in the past five years. This paper was divided into the following sections: The first part introduced the research background of starch-based hydrogels. The second part summarizes properties, formation principle and environmental responsiveness of starch-based hydrogels. The third part focused on the application of starch-based hydrogels in water purification, drug sustained release, 3D printing, agriculture and regenerative medicine. According to the facts mentioned above, there were few studies on the applications of starch-based hydrogels in self-healing materials and optoelectronic materials, and at the same time their performance cannot fully meet actual needs. Therefore, researchers needed to further study the interaction between the function and structure of starch-based hydrogel, improved its preparation strategy, expanded its application scope and quickly made it commercialization and marketization to bring huge economic and environmental benefits.

Intelligent imprinted polymers have stimuli-responsive molecular recognition and adsorption capability for template molecules under environmental stimuli. They have a broad prospect in the application encompassing the fields of adsorption separation, drug delivery, detection, solid phase extraction, catalysis and so on. In this paper, molecularly imprinted polymers (MIPs) were reviewed and the significant drawback of MIPs that it was difficult for MIPs to deform the binding sites for the sake of controlling binding characteristics was pointed out. To solve this problem, intelligent responsive imprinted polymers with flexible sites were proposed. Then, the response and identification mechanisms for intelligent imprinted polymers with magnetic, thermal, optical, pH, biological macromolecules and other dual-factors response functions were analyzed and summarized, respectively. It also reviewed the research progress of these intelligent imprinted polymers in different applications in recent years. Finally, based on the problems of different intelligent imprinted polymers, it prospected the intelligent imprinted polymers in the future from the aspect of preparation and theory, respectively.

Three new olefin-linked covalent organic frameworks were successfully constructed via Aldol condensation by using 2,4,6-trimethyl-1,3,5-triazine (TMT) with C₃-symmetry and aromatic aldehydes as building units. Under hydrothermal conditions, TMT-TFPT-COF [with 2,4,6-tris(4-formylphenyl)-1,3,5-triazine (TFPT)] and TMT-TFB-COF [with benzene-1,3,5-tricarboxaldehyde (TFB)] were successfully synthesized using NaOH as catalyst, while TMT-TFBA-COF [with 2,3,5,6-tetrafluorobenzene-1,4-dicarbaldehyde (TFBA)] was constructed via trifluoroacetic acid (TFA) catalyst. The COFs structures and olefin-linkages were illustrated by theoretical modeling, FTIR and other characterization methods. The results indicated that all these COFs were constructed via two-dimensional eclipsed structure, and the fluorescent COFs (TMT-TFPT-COF and TMT-TFB-COF) would show great potential applications in the photocatalysis and chemical sensors.

The continuous carbon fiber reinforced metal matrix composites with high specific strength and low density were prepared by additive manufacturing technology. The influences of process treatment methods and parameters, such as the surface modification of the continuous carbon fiber, the overlap rate of the path, the temperature of the print head and substrate, were studied on the tensile strength of the metal matrix composites. The results showed that well infiltration and compounding could be achieved between the molten metal matrix and the continuous carbon fiber while the surface of the carbon fiber was modified. At the same time, the tensile strength of the composite material was also improved. When the overlap rate of the printing path was increased, the volume fraction of the carbon fiber during composite material and its tensile strength were both increased. The surface tension of the molten metal was decreased, and its fluidity was better when the print head temperature, substrate temperature and printing speed were increased. This was conducive to the formation of re-fusion between the deposited layers, and could also effectively avoid the formation of pore defects at the surface cracks and the path overlap area, so that the tensile strength of the composite material could be further improved.

A worm-like micelle system with a dual response of CO₂/N₂-UV light was constructed by mixing N,N-dimethyldodecylamine (DMA), cetyltrimethylammonium bromide (CTAB) and sodium cinnamate (CA). Further research found that the system composed of DMA, CTAB and CA had low viscosity and could not form worm-like micelles. However, the introduction of CO₂ can lead to the formation of worm-like micelles, which was due to the protonation of DMA that changed the arrangement of surfactant molecules in the system. After passing N₂, the worm-like micelles would reversibly transform into spherical micelles. Ultraviolet light irradiation can transform worm-like micelles into spherical micelles with lower viscosity because CA can realize the transformation of trans-structure and cis-structure under the irradiation of ultraviolet light.

Polyethylene glycol (PEG) modified polyamide (PA) reverse osmosis (RO) composite membranes were fabricated via an interfacial polymerization of trimesoyl chloride (TMC) and m-phenylenediamine (MPD) with PEG using the polyacrylonitrile (PAN) ultrafiltration membranes as the supports. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FE-SEM) and atomic force microscope (AFM) were used to characterize the textural and physicochemical properties of the membranes. The effects of PEG molecular weight, PEG content, heat treatment temperature and time on RO performances of the membranes were investigated. Moreover, three typical pollutants, sodium dodecyl sulfate (SDS), dodecyl trimethyl ammonium bromide (DTAB) and bovine serum albumin (BSA) were used to examine fouling resistance of the membranes. Compared with the unmodified PA membranes, the salt rejection and flux recovery of PEG cross-linked PA membranes were improved. The PA/PEG1000-0.1 membranes delivered an observed NaCl rejection of 97.5% and a water flux up to 3.96kg/(m²?h). Moreover, the membrane exhibited high fouling resistance to SDS, DTAB and BSA with a flux recovery rate of 89.4% after fouling of SDS.

Bone defect repair still represents a challenging issue in clinic. Injectable composite materials for bone repair with good porosity and in situ solidification of arbitrary shape have shown great advantages in the treatment of clinical irregular bone defects. In this study, injectable porous nano hydroxyapatite/polyurethane (nHA/PU) composite scaffolds were fabricated with two-component design and using water as foaming agent. Furthermore, the morphology, chemical composition, internal structure, mechanical properties and curing time of the fabricated scaffold were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X ray diffraction (XRD), mechanical testing and Gilmore needle testing. The results showed that the injectable nHA/PU composite porous scaffolds were successfully prepared. The scaffolds had high porosity and good pore connectivity. The pore size distribution was 100—700μm, which was suitable for the growth of cells and tissues into the pores. The addition of 20% nHA significantly improved the mechanical strength of the PU porous scaffolds but reduced the porosity of the scaffolds. The injectable scaffolds solidified in 8h, which was suitable for clinical operation. The injectable nHA/PU composite porous scaffold prepared in this study has great potential in the field of irregular bone defect repair.

With the development of metabolic engineering, many chemicals can be produced by microbial cell factories. Production of chemicals by microbial cell factories has the advantages of mild reaction conditions and environmental friendliness, and is an important way to realize sustainable production. To improve the chemicals titer, yield and productivity in microbial cell factories, traditional metabolic engineering methods mainly depend on gene overexpression or gene knockout methods to increase the metabolic flux towards the target metabolic pathway. However, due to the insufficient accuracy of metabolic flux regulation, it is easy to lead to the decline of cell production capacity. Aiming at solving the bottlenecks during carbon flux regulation in microbial cell factories, this review systematically summarizes the latest progress from four perspectives: target selection of metabolic flux regulation, carbon flux balance between cell growth and chemicals synthesis, competition between by-product pathway and product synthesis, and pathway efficiency enhancement in product synthesis. The future development trend of building microbial cell factory is also prospected from the design of high-accuracy, bionic, intelligent, multi-task and quick-response tools.

The produced organic solid waste is increasing rapidly in recent years, and its treatment and disposal have attracted much attention. When aerobic technology is employed to treat the organic solid waste, the substrate of the feedstock is degraded very quickly at thermophilic temperature; however, aerobic biological system tends to be inhibited by many factors such as material composition, metabolic intermediate, or external environmental condition, and then the process may be adversely affected to some degree. This paper reviewed those inhibition factors such as ammonia nitrogen and digestion temperature which might significantly affect aerobic biological process of organic solid waste. Based on the variations of enzyme (such as protease and oxidase) activity and the transformation of metabolic products, the inhibition mechanisms under adversity conditions were proposed as following: acid-base imbalance in microorganisms, protein denaturation, and excessive oxidation of intracellular substances. After the comparison of enhanced biological treatment, inoculating functional microorganisms and adding exogenous reagents were suggested to alleviate the inhibition of aerobic process. In the end, this paper put forward the research directions to enhance aerobic performance of organic solid waste.

Enzymatic reactive distillation (ERD) is a process that combines reactive distillation (RD) with biocatalysis by using enzymes as reaction catalysts. Recently, this process is increasingly recognized for its high selectivity and environment-friendliness. In this paper, the enzyme-loaded packing was prepared by spraying the sol-gel solution with enzyme on the surface of plastic packing. As an indispensable structure in distillation column, the stability of enzyme-loaded packing was an important factor for the development of ERD. The relative content of the components in sol-gel formulation directly affected the performance of the gel matrix and the embedded enzyme. Hence, the gel formulation was optimized to improve the cracking problem of enzyme-loaded coating of plastic packing. The samples were characterized by Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Furthermore, the adhesion test, cycling stability, mechanical property, enzyme activity, and catalytic efficiency were studied. The results show that the brittleness of the gel coating on the surface of plastic packing has been improved, with the adhesion strength of the gel coating and packing increased by 14.2%, and the catalyst prepared by optimized formulation has excellent enzymatic stability. This work proved the feasibility of immobilizing enzymes on plastic packing and provided more potential for the industrialization of ERD.

Compared with traditional dioctyl phthalate (DOP) and polyether diethylene glycol dibenzoate (DEDB) plasticizers, the polyvinyl chloride (PVC) materials plasticized by polytetrahydrofuran dibenzoate (PTMGDB₅₀₀) plasticizer were investigated including FTIR, TG, mechanical properties, ethanol extraction resistance and migration resistance. In terms of mechanical properties, PVC material plasticized by PTMGDB₅₀₀ was between those plasticized by DOP and DEDB. Due to the stronger interaction between PTMGDB₅₀₀ and PVC, the properties of PTMGDB₅₀₀ plasticized PVC were better than those of DOP and DEDB in terms of resistance to migration, ethanol extraction, heat resistance and pressure resistance. Therefore, PTMGDB₅₀₀ can be used as a partial replacement of DOP and DEDB plasticizers.

The transformation and degradation of hydrophobic emerging contaminants (HECs) has become research hot spots due to the characteristics of widespread distribution, persistence, and refractory of HECs. Bioelectrochemical system (BES) is a flourishing technology for the remediation of various contaminants and has been proven to efficiently transform and degrade HECs. In this work, the effect of BES operational factors on HECs removal performance was analyzed, the effectiveness of BES technology in treating various HECs’was evaluated, and the feasibility and superiority of integrating BES into traditional treating technologies, such as anaerobic digestion, Fenton, wetlands, and photocatalysis, were discussed as well. Besides, the prospective development of functional electrode materials, the mechanism of HECs’transformation and degradation, and the engineering applications of BES technology were proposed. This review is expected to provide theoretical and technical supports for future research and promote the BES technology closer to the practical application.

Two-dimensional (2D) nanosheets are a kind of appealing porous materials. As a new type of highperformance adsorbent, the ultrathin 2D porous nanosheets have the advantages of high specific surface area, atomic thickness and abundant exposed active sites (organic or inorganic) in comparison with traditional adsorption materials. The pollutants can be selectively captured from aqueous solution quickly and effectively. This paper reviewed the latest progress of three representative 2D porous nanosheets [metal organic frameworks (MOFs) and covalent organic frameworks (COFs)] as excellent adsorbents for the removal of organic dyes, toxic heavy metals and radioactive elements from water environment. The structural characteristics and physicochemical properties of these compounds were introduced, and four commonly used synthetic methods were summarized. The advantages, disadvantages and challenges of the four methods were analyzed, and the characteristics of different synthesis methods were compared. The adsorption conditions and performance of ultra-thin 2D porous nanosheets for various pollutants in water were described, and the relevant adsorption mechanisms were systematically summarized and compared. The regeneration properties of materials were discussed, and the problems that may be encountered in the process of regeneration were introduced and analyzed. Finally, in view of the shortcomings and complex synthesis conditions of the ultra-thin 2D porous nanosheets, the optimization direction of the material synthesis, the development of green non-toxic or low-toxic new technologies and the improvement of reuse efficiency would be the development direction in the future.

Research progress of the commonly used materials for removing formaldehyde gas was described including adsorption materials, catalytic oxidation materials, photocatalytic degradation materials and biotechnological materials in this paper. Among them, carbon-based materials, molecular sieves and organic metal skeletons were often used to absorb volatile organic gases. They had rich pore structure and large specific surface area. There were abundant groups on the surface of carbon-based materials and molecular sieve, which can effectively increase the adsorption capacity of formaldehyde and improve the adsorption efficiency of formaldehyde. The metal on the organic metal skeleton surface was bonded with formaldehyde, which can effectively improve the chemical adsorption of the material. The materials with metal oxides as carriers were often used to catalyze the oxidation of formaldehyde molecules into non-toxic carbon dioxide and water, and semiconductor material TiO₂ was often applied as photocatalytic degradation material to remove formaldehyde, while others used biotechnology to remove formaldehyde gases. The advantages and disadvantages of removing formaldehyde from different materials were compared and the research on the modification of different removing materials was summarized.

Humic acid natural organic matter in water is an important factor affecting water quality, and it is difficult to remove humic substances from water by conventional process. Due to its high efficiency, low energy consumption and wide application range, oxidation and its combined technologies have gradually become pretreatment technologies for removing such pollutants. Ozone, potassium permanganate and other oxidants with strong oxidizing characteristics have replaced the traditional oxidant - chlorine, which can effectively decompose NOM into non-toxic small molecules, reduce the risk of mutagenesis of drinking water quality. Among oxidation technologies, ozone is advantageous in terms of safety and side effects, but the single oxidation technology has different degrees of limitations. According to different water conditions at home and abroad, the oxidation mechanism, synergistic effect, removal effect and application status of oxidation technology-coagulation process and other combined technologies to remove humic acid in water were compared in detail, and the research progress of different oxidation and its combined technologies to remove NOM in water was discussed. The analyses showed that oxidation technology combined processes have become the mainstream process to remove humic acid in water, and point out that the pre-oxidation-membrane combined technology has a wide application prospect because of its good synergistic property.

The sewage treatment plants are one of the important infrastructures of the cities. They are regarded as one of the important sources of greenhouse gases (GHGs) due to the mass production of CO₂, CH₄, N₂O and other gases during the operation. It has attracted widespread attention from scholars because of the great potential for emission reduction. The demand for GHGs emission reduction is driving the development of sewage treatment plants in a low-carbon direction that optimizes core operating parameters and resource and energy recovery. The main paths of GHGs generation, the main problems in present methodologies were described and the changes of different operating conditions of sewage treatment plants on their direct GHGs emissions were summarized. The analysis showed that the influent C/N, dissolved oxygen (DO) concentration, pH and nitrite concentration had obvious impacts on GHGs emissions, and these parameters are easier to be adjusted. Finally, the main problems existing in the relevant research and the prospects of the future research direction were summarized and prospected in order to provide a reference for the optimization of the operating conditions and GHGs emission reduction of the sewage treatment plants.

In order to solve the problems of poor oxidation rate and low utilization of organic wastewater ozonation treatment, a new technology of ozone microbubble was proposed. The microbubbles were prepared by pressure dissolved gas method and the organic wastewater were composed of phenol. The morphology size, oxidation effect, mass transfer characteristics and oxidation mechanism of ozone microbubbles were studied by means of microphotography, kinetic analysis, UV-vis absorption spectrum and free radical shielding. The relationship between ozone bubble diameter and interfacial pressure was also discussed in detail. Experimental and numerical results indicated that the average particle size of ozone microbubble was 20.37μm, the COD removal efficiency could reach 89% within 40min, the reaction rate could reach up to 3.61 times of aerator aeration, and the ozone utilization efficiency achieved was more than 99.19%. Oxidation process was an indirect oxidation process dominated by free radicals, and the final oxidation products of pollutants were small molecular hydrocarbons and carboxylic acids. Under the influence of microbubbles, the mass transfer rate and decomposition rate of ozone were increased. At the same time, higher interfacial pressure on the surface of ozone microbubbles was one of the reasons for their high mass transfer efficiency.

An experiment of antibiotic residue co-processing was carried on a 300MW pulverized coal fired boiler. The migration characteristics of chromium and arsenic were traced, and the environmental impact during the co-combustion was studied. The samples were measured by inductively coupled plasma mass spectrometry (ICP-MS) for their heavy metal content. At 9.09% residue-mixing ratio, chromium and arsenic added into the furnace increased to 1.46 and 1.44 times respectively. The results show that the mass balance coefficients of trace elements studied are 88.3%—96.2% and 75.8%—76.5%, respectively. Under co-processing condition, 92.73% chromium is enriched in fly ash, and chromium in flue gas exists in particles. The distribution of arsenic in fly ash is 49.83%, which is lower than that of chromium. The flue gas desulfurization (FGD) system can capture the arsenic escaped from the electrostatic precipitator. 24.64% of the - arsenic entering furnace is finally fixed in the FGD gypsum, and only 0.008% is still emitted with the flue gas. 87.2% of the flue gas arsenic is in particulate form and 12.8% is in gaseous form. Chromium and arsenic emitted through flue gas meet emission standards issued by the US Environmental Protect Agency. The leaching concentrations of chromium and arsenic of the solid byproducts are lower than the limit of hazardous waste identification standard. Co-processing antibiotic residue in a pulverized coal furnace turns out to be safe and feasible.

A series of nickel-based catalysts modified with alkali/alkaline-earth metals (Ni-M/Al₂O₃, M= K₂CO₃, Na₂CO₃, MgO, CaO) were prepared by step impregnation method. Effects of the doped alkali/alkaline-earth metals on CO₂ adsorption and methanation performance of the modified Ni-M/Al₂O₃ catalysts were investigated. Doping alkali/alkaline-earth metals increased the surface density of basic active sites of Ni/Al₂O₃ catalyst and therefore enhanced the CO₂ adsorption capacity. The doped alkali/alkaline-earth metals could also affect the distribution of the surface basic active sites, the transformation of NiO phase and the dispersion of Ni on the support, and therefore the Ni-M/Al₂O₃ catalysts exhibited different methanation performance. MgO doping would promote the transformation of NiO to β- and γ-type NiO phases, which exhibited strong interaction with the support. Besides, MgO doping reduced the proportion of strong basic active sites, which could be favorable for CO₂ adsorption and activation. Amongst the Ni-M/Al₂O₃ catalysts, Ni-MgO/Al₂O₃ exhibited the highest CO₂ adsorption capacity of 0.68 mmol CO₂/g, the maximum CO₂ conversion of 58.4% and the greatest CH₄ selectivity of 95.4%. The Ni-MgO/Al₂O₃ catalyst showed potential application in CO₂ capture from flue gas and in-situ methanation.

According to the parameters of an 8×10⁵t/a catalytic regenerated flue gas, combining with low-temperature slurry spray and heat pump technology, the FCC (fluid catalytic cracking) desulphurization wet flue gas wet plume elimination-purification system coupling heat pump was designed, and the heat recovery route of flue gas - slurry - heat pump was established. The process simulation and analysis were carried out using Aspen Plus and thermal model, the results showed that the system has a good ability of wet plume elimination in low temperature environment. Low temperature spraying enhances the desulfurization and dust removal performance of the desulfurizer,while promotes the recovery of water of flue gas. The recovered water of the system was 1.47t/h under the design condition. The flue gas could be dewhitened by its own heat drive without additional heat. The sensitivity analysis showed that the system could eliminate wet plume in the fluctuation range of volume flow from 82% to 124%. The new system could recover waste heat and make use of it. The surplus heat of the system was 1.87MW in simulation, the payback period of investment was 4.88 years, which reflected the good economic performance of the system. The system has certain reference significance for the FCC flue gas dewhitening transformation.