Table of Content

28 April 2024, Volume 24 Issue 4

Previous Issue   

Contents

Cover and Contents

The Chinese Journal of Process Engineering. 2024, 24(4):  0. 

Asbtract ( )   PDF (5249KB) ( )  

Related Articles | Metrics

Review

Key technologies and advances of positron emission particle tracking

Kun LI Liyun WU Ping CHEN Yan HAN

The Chinese Journal of Process Engineering. 2024, 24(4):  381-390.  DOI: 10.12034/j.issn.1009-606X.223266

Asbtract ( )   HTML ( )   PDF (2513KB) ( )  

Related Articles | Metrics

Measuring multiphase flow parameters and the understanding of multiphase flow mechanisms are of great importance value for the design, operation, and optimization of industrial process devices. Due to the inherent multiscale nature of multiphase flow, its flow field often has great complexity, which makes our understanding of its flow process relatively limited. There are still many key issues that need to be explored in the mechanism of multiphase flow. Positron emission particle tracing (PEPT) is a new undisturbed and non-destructive imaging method for complex multiphase flows in industrial processes. γ photon detection is used to perform 3D dynamic imaging of radioactive labeled tracer particles. Due to γ photons have high penetration and are not affected by electromagnetic fields, making PEPT a unique advantage in detecting non-transparent and complex industrial multiphase flows. Currently, it is mainly used for measuring multiphase flow phenomena and extracting system physical parameters in industrial fields such as chemical, food, and pharmaceutical industries. However, the difficulties in preparing miniaturized tracer particles and the poor localization effect of multiple tracer particles at the same time seriously hinder the further application and promotion of PEPT technology. In this work, basic principles of PEPT technology are firstly briefly introduced, then the key technologies and research progress of PEPT are discussed from the aspects of tracer particles, algorithms, hardware systems and data processing in applications. The existing problems and potential development directions are pointed out. Finally, the development and application of PEPT is summarized and prospected.

Research Paper

Heat and mass transfer simulation of gas-liquid two-phase flow in a distillation column based on OpenFOAM

Yunpeng JIAO Xiaoqing ZHOU Jianhua CHEN

The Chinese Journal of Process Engineering. 2024, 24(4):  391-402.  DOI: 10.12034/j.issn.1009-606X.223180

Asbtract ( )   HTML ( )   PDF (4117KB) ( )  

Related Articles | Metrics

For multiphase mass transfer processes in distillation columns, computational fluid dynamics can be used not only to simulate the flow phenomena, but also to study the heat and mass transfer processes and their interactions with the flow. Based on previous work on gas-liquid flow simulation in distillation trays, this work applied the multiphase flow solver of the OpenFOAM platform. The energy and species transport equations were considered to construct the heat and mass transfer models for the distillation system. The ideal system of cyclohexane-n-heptane and the non-ideal system of ethanol-water distillation were simulated respectively. The distribution of the gas-liquid two-phase flow, component and temperature on the column trays were analyzed. For the ideal system, the ideal solution mass transfer model can provide accurate predictions for the temperature and concentration fields on the trays. However, for non-ideal systems, it was necessary to introduce the activity coefficient model on the basis of the ideal model. To this end, the effects of two activity coefficient models, UNIQUAC and NRTL, were introduced and compared. In the current simulation framework, the activity coefficient models were able to improve the simulation accuracy of temperature and concentration field. The overall trends predicted by the two models were generally consistent with the results in the literature, and the UNIQUAC model agreed better with the literature. In addition, the comparative analysis of gas-liquid two-phase flow field and concentration field distribution showed that the circulating flow of liquid phase can enhance the local mass transfer efficiency of the column tray, resulting in higher efficiency at the liquid inlet and the weir than the tray center. However, the gas-liquid renewal in the circulating region renewed ly, which led to a reduction in the overall mass transfer efficiency of the column tray. This study can be used for the design and optimization of distillation columns, and it is also valuable for simulations of heat and mass transfer in other gas-liquid two-phase flow systems.

Study on solid-liquid suspension characteristics in a slurry polymerization reactor with different impeller combinations

Yang ZHAO Minghui XIE Jiawei XIANG Xiaoxiao LIU Shuailiang LI Shijun LÜ Liang WU Guozhong ZHOU Qinghua ZHANG Chao YANG

The Chinese Journal of Process Engineering. 2024, 24(4):  403-413.  DOI: 10.12034/j.issn.1009-606X.223210

Asbtract ( )   HTML ( )   PDF (5209KB) ( )  

Related Articles | Metrics

Slurry process is the main production method for high-density polyethylene. For slurry of high-density polyethylene stirred polymerizer, three-blade-backswept impeller HQ, parabolic disc turbine impeller BTD, three blade hydrofoil impeller KHX, pitched blade disc turbine impellers ZY with blade placement angle of δ=45° and δ=75°, and straight blade disc turbine impellers PY160 were used to form four types of impeller combinations. Solid-liquid suspension experiments were conducted in a cylindrical perspex stirred tank with a diameter of T=480 mm. The CFD software Ansys Fluent 2020R2 combined multiple reference frame method and Euler-Euler multiphase flow model were used to study the solid-liquid suspension of each impeller combination at 30.71% solid holdup. The results showed that when the rotating speed N≤ 250 r/min, a clear liquid layer formed at the top of the mixing tank with impeller combination 2 and 3. Due to the inhomogeneous of solid holdup, the power of impeller combination 3 and 4 showed an inflection point at the rotating speed N=350 r/min. When the rotating speed N≤350 r/min, the combined power of each paddle type from low to high was: 2, 4, 3, 1. When the rotating speed N>350 r/min, the mixing power from low to high was: 2, 3, 4, 1. Impeller combination 1 and 4 can achieve uniform mixing at lower speeds and power, and the power consumption of impeller combination 4 was about 30% lower than that of impeller combination 1, so impeller combination 4 was high efficiency and energy conservation. The simulated results of solid holdup were in good agreement with the experimental values which was measured by the sampling method. The simulated flow field indicated that the flow patterns of impeller combination 4 and 1 were similar, which can effectively avoid the clear liquid layer appearing in impeller combination 2 and 3 at low rotating speeds.

CFD simulation and temperature regulation of the coke drum

Boyan CHEN Yuting CAO Yong ZHANG Guogang SUN Yindong LIU Luhai WANG

The Chinese Journal of Process Engineering. 2024, 24(4):  414-424.  DOI: 10.12034/j.issn.1009-606X.223145

Asbtract ( )   HTML ( )   PDF (4792KB) ( )  

Related Articles | Metrics

Coke drum is the conventional reactor for processing heavy oil into light chemicals in petrochemical industry. Because of the high operation temperature within the reactor, experimental monitoring is particularly difficult. The complex processes within the coke drum involve the fluid flow, heat transfer and reaction, and the heterogeneous temperature distribution make it challenging for precise regulation. This study considers the distribution of gas phase, liquid oil, and solid coke in the reactor and adopts continuous medium model (Eulerian model) to simulate the motion of three phases and couples the heat transfer model and seven-lumped reaction kinetics model, so as to establish a multiscale model for the coke drum reactor. The accuracy of this model is validated by comparing the simulation and experiment results in the kettle reactor. Furthermore, the feeding process and the coke growth from mesoasphaltene are modelled, and the flow field, temperature distribution, and coke generation rate under different operating conditions are studied. The results show that the coking process and the heterogeneous distribution of multi-physical field in the reactor are greatly influenced by temperature. The mass fraction and growth rate of coke and gas products increase a lot at high temperature. In order to regulate the distribution and growth rate of the coke product, the mesoasphaltene, which is the precursor product of the coke, is generated with temperatures no more than 450℃ at feeding stage, so that the coke growth rate is restricted. Afterwards, the temperature is improved by heating reactor walls and injecting high-temperature steam, in which the reaction rate of mesoasphaltene towards coke product increases and the uniform distribution of coke can be obtained. This study provides an important case for regulating distribution and growth of coke product by coordinating the temperature field and flow characteristics within the coke drum.

Study on flow characteristics and clarification process of glass melt in 700 t/d float glass furnace

Mingfang JIN Feng HE Junlin XIE Shuxia MEI Quanliang LI

The Chinese Journal of Process Engineering. 2024, 24(4):  425-434.  DOI: 10.12034/j.issn.1009-606X.223215

Asbtract ( )   HTML ( )   PDF (3711KB) ( )  

Related Articles | Metrics

It is well known that the flow and clarification process of glass melt are critical to glass production control and product quality. To explore the flow characteristics and clarification process of glass melt in float glass furnace, the flow field and temperature distribution were studied. From a new perspective the numerical simulation of the flow and heat transfer process of glass melt were carried out for a glass tank under actual working conditions by using Ansys CFD software. In view of the simulation results on flow field and heat transfer of glass melt in float glass furnace, the temperature distribution and flow characteristics of glass melt in the furnace were analyzed and the clarification process of the bubbles in glass melt was further analyzed on this basis. It was found that along the furnace length, the temperature of the glass melt on the surface and at the bottom of the tank showed two mountain shaped distributions respectively, and the flow pattern of glass melt presented three large circulation flows in the tank. In the clarification section the forward and backward flow velocities of glass melt increased and then decreased. In the direction of tank depth from surface to bottom, the temperature of glass melt decreased in a gradient. At a depth of about 400 mm from the surface, the value of flow velocity was zero. After the hot spot, the flow above this surface flowed smoothly to the neck, and at the shortest time of 418 s. Within this time, bubbles larger than 1.2 mm in diameter can be eliminated before they reached the neck with the flow of glass melt, and whether the bubbles smaller than 1.2 mm in diameter can be eliminated or not needs further study on the pattern of bubble uplifting and changing.

Model development and validation of a structural two-fluid model for gas-solid bubbling fluidized beds

Jiewen LUO Yabin WANG Wen LI Guosheng WANG Bidan ZHAO Junwu WANG

The Chinese Journal of Process Engineering. 2024, 24(4):  435-444.  DOI: 10.12034/j.issn.1009-606X.223225

Asbtract ( )   HTML ( )   PDF (3392KB) ( )  

Related Articles | Metrics

Bubbling fluidized beds have been widely used in industrial applications because of its good mass and heat transfer behavior, where the heterogeneous structures such as bubbles are widely present, and these complex structures significantly affect the mass, momentum, and heat transfer as well as chemical reactions in the fluidized bed. The continuum model is selected to simulate the industrial fluidized beds by considering both of the computer cost and efficiency. In order to improve the accurate prediction of the continuum method simulation, it's very important to quantify reasonably the relationship between heterogeneous structures and three transfers/chemical reactions. The structure two-fluid model has been proposed as a novel continuum model, which has taken into account the influence of the heterogeneous structures such as particle clusters in the governing equations and the constitutive relations, therefore, this method is a complete and logically self-consistent in terms of heterogeneous structures. In this study, the structural two-fluid model is extended to the numerical simulation of bubbling fluidized bed: in the deducing the governing equations, the heterogeneous gas-solid system is divided as the particle-dominated emulsion phase and gas-dominated bubble phase, which are defined as two continuous fluids and permeate each other; for closing the constitutive relations, the involved bubble diameter, solid fraction in the emulsion phase and its viscosity have considered the influence of heterogeneous structures such as bubbles by some empirical correlations. As shown in the simulated results, the structural two-fluid model can successfully predict the hydrodynamics characteristics of gas-solid flow in the bubbling beds, thus validating the applicability of the structural two-fluid model in the simulation of bubbling fluidized beds. Moreover, the bubble size as an essential factor has an impact on the interaction between bubble phase and emulsion phase, which leading to the different simulation results with different bubble size correlations.

Research on heat dissipation characteristics of power battery with methanol-water binary working medium thermosiphon containing GNs

Jinli LU Shuaijie ZHOU Yafang HAN Yanhong SUN Ru HUANG

The Chinese Journal of Process Engineering. 2024, 24(4):  445-452.  DOI: 10.12034/j.issn.1009-606X.223231

Asbtract ( )   HTML ( )   PDF (2509KB) ( )  

Related Articles | Metrics

High operating temperature and large temperature difference of power battery will cause its performance to decline rapidly. For an effective battery thermal management system (BTMS), the maximum temperature and the surface temperature difference of power battery module should be controlled in the allowable range. With the scale and modularization of power batteries, the thermal safety problem is becoming more and more prominent, and it is urgent to develop more advanced and efficient BTMS. In this work, based on the research results of heat transfer characteristics of methanol-water binary working medium thermosiphon containing graphene nanoparticles (GNs), the experimental test system of battery thermal management was constructed with methanol-water binary working medium thermosiphon with filling rate of 50% and GNs concentration of 0.02wt%. The heat dissipation of power battery pack was researched under three discharge rate conditions of 1, 1.5, and 2 C, and were compared with natural cooling and forced air cooling results. The study results showed that, for methanol-water binary working medium thermosiphon containing GNs cooling system, the maximum battery temperature corresponding to discharge rates of 1, 1.5, and 2 C were 28.89, 32.12, and 35.76℃, respectively. Meanwhile, the average temperature rise rate of power battery pack was the lowest, which was only 0.525℃/min at 2 C discharge rate. In addition, at 2 C discharge rate, the power battery temperature of methanol-water binary working medium thermosiphon containing GNs cooling system decreased by 22.48% and 49.13% compared with forced air-cooling system and natural cooling, respectively. The heat dissipation efficiency of the methanol-water binary working medium thermosiphon containing GNs cooling system was the highest under three kinds of discharge rates, and all of them were more than 70%. The research results can provide theoretical basis and data support for the application of heat pipe cooling system in power battery thermal management system.

Theoretical calculation of surface tension and surface excess in liquid Ag-O system

Tiansu LI Jianxiong LIU Xianxiang SHAN Kanpeng LI

The Chinese Journal of Process Engineering. 2024, 24(4):  453-461.  DOI: 10.12034/j.issn.1009-606X.223179

Asbtract ( )   HTML ( )   PDF (2744KB) ( )  

Related Articles | Metrics

Surface tension, an important physical parameter of liquid metals, plays a crucial role in governing various surface phenomena. In this work, the surface tension and surface excess entropy of liquid silver were calculated using the proportion relationship between surface energy and cohesive energy. The results showed that as the temperature increased, the surface tension approximately linearly decreased, and the surface excess entropy also gradually decreased, which indicated that the liquid silver surface always maintained an ordered structure. On this basis, the liquidus line of the Ag-O system was calculated using the ideal solution approximation model, and its agreement with the experimental phase diagram validated that the system could be considered as an ideal solution. By simplifying the Butler equation, a predictive model for the surface tension of the liquid Ag-O system as a function of oxygen partial pressure and temperature was derived. The results demonstrated that at oxygen partial pressures below 10 kPa, the surface tension of the liquid Ag-O system showed a negative correlation with temperature. However, for oxygen partial pressures above 10 kPa, the surface tension initially increased and then decreased with the increasing temperature. Additionally, the surface tension of the liquid Ag-O system at 1350 K was calculated and compared with literature data, showing excellent agreement between the calculated values and experimental observations. Furthermore, the surface segregation behavior of oxygen atoms was also investigated. The study revealed that surface excess concentration was positively correlated with oxygen partial pressure and negatively correlated with temperature. It was observed that the surface segregation factor showed negative correlations with both temperature and oxygen partial pressure. At lower temperatures and oxygen pressures, oxygen atoms tend to accumulate on the surface. This research provides data support for deep exploration of the surface properties of the liquid Ag-O system and serves as a reference for optimizing predictive models of surface tension in metal-gas systems.

Effect of finish rolling temperature on microstructure and mechanical properties of bridge weathering steel with low yield ratio

Wensheng LIU Ke ZHANG Dangwei XU Shaobo MENG Zhong HUANG Zhisheng XIA Mingya ZHANG Xinjun SUN

The Chinese Journal of Process Engineering. 2024, 24(4):  462-469.  DOI: 10.12034/j.issn.1009-606X.223247

Asbtract ( )   HTML ( )   PDF (2801KB) ( )  

Related Articles | Metrics

The effect of the finish rolling temperature on the microstructure and mechanical attributes of Cu-Cr-Ni bridge weathering steel, characterized by a low yield ratio, was exhaustively explored in this study. Advanced testing methodologies including the Gleeble-3800 thermal simulation tester, tensile tester, and Vickers hardness tester were employed, in conjunction with characterization techniques such as optical microscope (OM) and electron backscattered diffraction (EBSD). This comprehensive approach aimed to elucidate the specific mechanisms governing these transformative changes. The results of the investigation unveiled pivotal transformations within the microstructure of Cu-Cr-Ni bridge weathering steel. Initially rolled at 880℃, the steel exhibited a granular bainitic microstructure. A reduction in the finish rolling temperature to 800℃ ushered in the formation of acicular ferrite, which gradually increased in prevalence. Simultaneously, the average size of the M/A islands expanded from 1.3 to 3.3 μm, accompanied by an increase in the area fraction from 21.7% to 32.3%. Notably, a marked elevation in dislocation density within the matrix was observed, primarily attributed to the considerable reduction in the degree of matrix restitution. Furthermore, these microstructural modifications were mirrored by notable enhancements in the material's mechanical properties. The hardness and yield strength of the Cu-Cr-Ni bridge weathering steel experienced a pronounced upswing with diminishing finish rolling temperatures. The yield strength, in particular, exhibited a remarkable increase from 435 to 496 MPa. Contrarily, tensile strength remained relatively stable at approximately 710 MPa. These mechanical variations were intricately linked to the prevalence of acicular ferrite within the microstructure, the presence of M/A constituents, and the heightened dislocation density. Importantly, the yield ratio exhibited an increasing trend, albeit generally maintaining a level below 0.7, indicative of a subtle improvement in plasticity. This research not only advances the understanding of materials science but also offers valuable insights for optimizing the manufacturing process of high-performance bridge steels, thereby contributing to the continued progress of the bridge structure.

Leaching process and kinetics of niobium-tantalum concentrate by HF-H₂SO₄ mixed acid

Gengyu LIANG Xuebin SU Huiwu LIU Kang LIU Hao CHENG

The Chinese Journal of Process Engineering. 2024, 24(4):  470-479.  DOI: 10.12034/j.issn.1009-606X.223211

Asbtract ( )   HTML ( )   PDF (2212KB) ( )  

Related Articles | Metrics

As rare precious metals, niobium and tantalum are widely used in the fields of high-precision instruments and military equipment due to their excellent physical and stable chemical properties. China is rich in niobium and tantalum resources, most of which are associated deposits that coexist with various metal minerals and have high comprehensive utilization value. In response to the separation and recovery of uranium, thorium, and rare earth resources in niobium and tantalum concentrates, the HF-H2SO4 mixed acid method is used to preferentially extract niobium and tantalum, while enriching uranium, thorium, and rare earth in the slag. In this research, the one-factor experimental design is applied to study the leaching behavior of niobium and tantalum, meanwhile, the process mechanism and kinetics are discussed. The results show that using high concentration hydrofluoric acid, increasing the amount of hydrofluoric acid and sulfuric acid is beneficial for the leaching rate of niobium and tantalum. Reducing the ore particle size, increasing temperature, and extending leaching time all has favorable effect on the leaching rate of niobium and tantalum. The optimal leaching conditions obtained are as follows: 40wt% HF 1120 g/kg, H2SO4 392 g/kg, average particle size -25 μm (75%), leaching temperature 80℃, and leaching time 4 h. In which the leaching rate of niobium is greater than 98%, and that of tantalum is greater than 97%. Uranium, thorium, and rare earth are retained in the slag, and the enrichment rate in the slag reaches 3.0 to 4.2. The kinetic research has shown that the leaching process of tantalum and niobium conforms to the shrinkage core model and belongs to the chemistry and diffusion mixed control. The apparent activation energy of Nb obtained from the experiment is 34.00 kJ/mol, and that of Ta is 36.26 kJ/mol. This method effectively extracted niobium-tantalum and enriched the other valuable elements, which build the foundation for the design of the separation and purification process.

Preparation of macroporous polymer heparin affinity chromatography medium by Schiff base method

Jiaru GU Nan WANG Lei MA Juan QIAO Haibo JIN Guangxiang HE Lan ZHAO Yongdong HUANG Rongyue ZHANG

The Chinese Journal of Process Engineering. 2024, 24(4):  480-488.  DOI: 10.12034/j.issn.1009-606X.223167

Asbtract ( )   HTML ( )   PDF (1859KB) ( )  

Related Articles | Metrics

The heparin affinity chromatography is widely applied for purification of proteins due to its high specificity and ease of operation. The heparin affinity chromatography medium was prepared through Schiff base method using heparin as the ligand, which was based on the macroporous polyacrylate microspheres. Firstly, the epoxy groups in the macroporous microspheres were hydrolyzed to be o-hydroxy through 0.5 mol/L H2SO4 aqueous solution. Secondly, the o-hydroxy was further oxidized to be aldehyde groups. Finally, the heparin was immobilized in the macroporous microsphere through the reaction between aldehyde groups and amino groups. The effects of operating conditions on the coupling reaction were investigated and optimized including the concentration of heparin, pH, buffer concentration, and reaction time. The effect of the reaction factor on the adsorption of proteins was evaluated using lysozyme as model protein. The optimal reaction conditions were found and the static binding capacity of the model proteins reached 40.3 mg/mL. This value was about 36% higher than that of the commercial GP-heparin. The protein recovery in this medium reached 95% with 1.0 mol/L NaCl as elution solvent. The morphology of the microspheres was observed by scanning electron microscopy. The result showed that the throughput pores were maintained in the affinity medium. The dynamic binding capacity of lysozyme on the affinity support was determined under different flow rates (31.8~318 cm/h). The result indicated the capacity at 318 cm/h decreased by about 12% in comparison with that at 31.8 cm/h. The dynamic binding capacity remained 81% of the initial value after 10 cycles. The synthesized affinity medium was used to isolate lactoferrin from mixtures. The results showed that it had a high separation efficiency.

Efficient recycling of Spirulina platensis culture medium and identification of its growth inhibitors

Yue ZHOU Yu WANG Leipeng CAO Yuhuan LIU Ruijuan FAN Zhenghua HUANG Zixuan WEN

The Chinese Journal of Process Engineering. 2024, 24(4):  489-500.  DOI: 10.12034/j.issn.1009-606X.223192

Asbtract ( )   HTML ( )   PDF (4341KB) ( )  

Related Articles | Metrics

Spirulina platensis (S. platensis) and its derivative products, have garnered considerable attention in the realms of food and biomedicine due to their high nutritional content. However, during the cultivation of S. platensis, copious amounts of water are required for both cell growth and nutrient suspension, leading to high water usage, increased costs, extensive nutrient waste, and substantial growth inhibition during the recycling process. This study aimed to assess the effectiveness of treating culture solution of S. platensis using four methods (0.45 μm filter membrane, 10 kDa ultrafiltration membrane, macroporous resin S-8, and activated carbon), evaluate the changes of growth and nutrient compositions of S. platensis after five recycles of culture solution, and identify the characteristics of extracellular inhibition and its constituents. The results showed that the circulation culture of Spirulina could greatly reduce the water consumption and culture cost, and improve the yield and quality of Spirulina. The culture solution pretreatment of S. platensis could effectively reduce the inhibition effect of extracellular organic matter, the negative effects can be effectively reduced, so that there was almost no difference between the microalgae obtained from the reused medium and the fresh medium and the order of treatment effects were 10 kDa ultrafiltration membrane>macroporous resin S-8>activated carbon>0.45 μm filter membrane. After five recycles of culture solution, the cell weight of S. platensis in the 10 kDa ultrafiltration membrane treatment group decreased only 5.9%, and that of the 0.45 μm filter membrane treatment group significantly decreased about 22% (p<0.05), but its intracellular polysaccharide content increased 217% due to the coercive effect of cell metabolism. In addition, the extracellular inhibitors in the culture solution were mainly extracellular polysaccharide, consisting of monosaccharides such as fucose (19.98%), rhamnose (15.61%), and glucose (14.75%). Therefore, this research holds significant implications for enabling sustainable, large-scale spirulina cultivation via the recycling of spirulina culture fluid. In addition, it contributes to nutrient accumulation, cost reduction, and decreased usage of nutrient salts.