Loading...
Welcome to visit The Chinese Journal of Process Engineering, Today is

Table of Content

    28 August 2022, Volume 22 Issue 8
    Previous Issue    Next Issue
    Contents
    Cover and Contents
    The Chinese Journal of Process Engineering. 2022, 22(8):  0. 
    Asbtract ( )   PDF (1806KB) ( )  
    Related Articles | Metrics
    Review
    Research progress of adsorption method to remove tetracycline from wastewater
    Xiong LAN Qin LIU Xintao ZHOU Zhongqiu LUO Xiaoteng ZHAO Yan LU
    The Chinese Journal of Process Engineering. 2022, 22(8):  989-1000.  DOI: 10.12034/j.issn.1009-606X.221261
    Asbtract ( )   HTML ( )   PDF (6695KB) ( )  
    Related Articles | Metrics
    Tetracycline (TC) is a broad-spectrum antibiotic with large production and application at present. Its chemical properties are relatively stable and difficult to metabolize, so it is easy to accumulate in soil and water. The abuse of antibiotics not only increases the drug resistance of bacteria, but also produces resistance genes and induces the production of super-bacteria. Therefore, the harmless treatment of wastewater containing TC is urgent. Adsorption method has the advantages of easy operation, high removal rate, economy, and environmental protection. It is widely considered as an efficient method to remove antibiotics. The adsorption materials used to remove tetracycline from wastewater are different and various. This work mainly summarizes three kinds of common adsorbents: carbon materials, metal organic framework materials, and mineral materials. The adsorption capacity of the above materials for TC is listed, and the effects of pH value, temperature, ionic strength and other factors on the adsorption process of TC are analyzed. On this basis, the fitting of different adsorption kinetics and thermodynamic models when these three kinds of materials adsorb TC is analyzed. It is found that the adsorption kinetics of most materials meets with the quasi-second-order kinetic model, and the adsorption thermodynamics of the Freundlich thermodynamic model are better to describe the adsorption process. In addition, the mechanism involved in the removal of TC is also described. Finally, the advantages and disadvantages of these three kinds of materials in the study of TC adsorption are compared, and the future research focus is prospected, which provides a reference for accelerating the preparation of more economical, efficient and renewable TC removal adsorption materials.
    Tribocharging mechanism and triboelectric separation technology of waste plastics
    Jilan SHI Yongqiang XU Haifeng WANG Yaqun HE
    The Chinese Journal of Process Engineering. 2022, 22(8):  1001-1010.  DOI: 10.12034/j.issn.1009-606X.221214
    Asbtract ( )   HTML ( )   PDF (1094KB) ( )  
    Related Articles | Metrics
    Plastics are widely used in the fields of engineering construction, food safety, transportation, and medical treatment due to the advantages of light material, stable chemical properties, low cost, wear resistance, and corrosion resistance. If it is not handled properly, it will cause serious environmental pollution and waste. The prevention and control of plastic pollution have become an environmental issue of global concern. At present, the recycling methods for processing waste plastics include primary recycling, energy recycling, mechanical recycling and chemical recycling. Mechanical recycling has become the most commonly used method for processing waste plastics due to its simple processing technology, low equipment cost, and low investment. Commonly used mechanical treatment methods include wind separation, flotation, electrostatic separation, optical separation, etc. As a new type of dry separation method, triboelectric separation has been paid more and more attention by researchers because of its advantages of simple process, less pollution, less investment and low cost. It uses the contact, collision, friction between minerals, or the friction between minerals and the feeding trough, to generate charges of different magnitudes and opposite signs. When fed into a high-voltage electric field, the resulting motion trajectories are also significantly different due to the different signs of the particle charges, separating the two minerals. It mainly includes two processes of triboelectric charging and electrostatic sorting. The materials to be sorted carry charges of different polarities after friction, which is the prerequisite for triboelectric sorting and separation. Aiming at the sorting and recycling of waste plastics, this work introduces the charging mechanism, influencing factors, charging device, and sorting device of triboelectric separation in detail, and points out the technical problems of recycling waste plastics by triboelectric separation. The future development direction of triboelectric separation technology is prospected. It is suggested that the theoretical study of turbocharging should be improved from a microscopic point of view with the help of modern analytical instruments. Develop and design an electrified sorting device that can precisely control humidity. Optimize the structural design of the charging device, enhance the charging effect, or fully charge the particles through multi-stage charging.
    Application and research progress of ionic liquids containing azobenzene moiety in smart materials
    Su MA Yi DAI
    The Chinese Journal of Process Engineering. 2022, 22(8):  1011-1018.  DOI: 10.12034/j.issn.1009-606X.221290
    Asbtract ( )   HTML ( )   PDF (810KB) ( )  
    Related Articles | Metrics
    As a new type of smart material, stimuli-responsive materials have many important applications both in daily life and industrial production. However, such materials are just applied in limited fields because of high energy consumption, difficulty in precise control, and poor cycle reversibility. Azobenzene compound, where there is a photosensitive functional group, is relatively simple to be synthesized. And they are of good cycle reversibility, easy precise control, and relatively energy saving. The ionic liquid that exists as the liquid is a new type of material with low vapor pressure, good thermal stability, and low pollution to the environment. Moreover, the structure of ionic liquid is designable. Therefore, ionic liquid containing an azobenzene moiety is a new type of functional material that exhibits dual characteristics as light stimuli-responsiveness and ionic liquids. Taking full advantage of the photoisomerization which is induced by ultraviolet and visible light irradiation, the physical and chemical properties of such materials can be tuned. The issue of light stimuli-responsive ionic liquids containing azobenzene moieties has been a hot topic in recent years. This article reviewed and summarized recent studies on the properties and performance of ionic liquids containing azobenzene group upon UV and visible light irradiation, which was furtherly applied in the field of smart materials. Specifically, examples of recent applications of ionic liquids containing azobenzene group across a multitude of fields such as light-controlled conductivity, light-controlled self-assembly, light-controlled phase behavior, light-controlled CO2 capture and release as well as light response controllable viscoelasticity of ionic gel are all described in detail, and their future development also prospects in this work. Ionic liquids containing azobenzene moiety have unique advantages and are expected to provide new ideas for the development of smart materials and green chemistry under the background of sustainable development.
    Research Paper
    Study on stability of surfactant-driven droplet spreading over topographic substrate
    Chunxi LI Haozhe SU Jiaming TONG Xuemin YE
    The Chinese Journal of Process Engineering. 2022, 22(8):  1019-1029.  DOI: 10.12034/j.issn.1009-606X.221311
    Asbtract ( )   HTML ( )   PDF (1537KB) ( )  
    Related Articles | Metrics
    When a droplet laden with surfactant landing on a thin film, spontaneous spreading driven by surface-tension gradient occurs. Affected by the non-linear impact, the initial small disturbances lead to an unstable fingering phenomenon during the spreading, which is closely related to the topographic substrates. Based on the evolution equations of liquid film height and surfactant concentration derived from the lubrication approximation, FreeFEM++ is employed for simulation coding, and the Microsoft MS-MPI runtime library is applied for parallel computing. The influence of the topographic substrates on the instability is examined, the power spectrum is employed to analyze the growth law of disturbance energy corresponding to different wavenumbers, the relation between the Marangoni effect, the capillary effect, and the disturbance energy is investigated, as well as the internal mechanism of the topographic substrate on instability is explored. The results show that the topographic substrates deal little influence on the fingers, but a lot on the region downstream. Disturbance energy with different wavenumbers present different evolution characteristics, and the dominant wavenumbers in this study are 20 and 7. On the notch base, wavenumbers selected from random disturbance is consistent with transient growth analysis (TGA), which means that notch base does not change the wavelength select mechanism. The maximum disturbance energy appears at the position setting the initial condition. Compared with the flat base, the notch base can inhibit the development of disturbances, and the total disturbance energy is reduced to approximately 80%. Whereas the corrugated base can promote the development of disturbances, and the total disturbance energy is increased to about 105%, and the corrugated base has a strong promotion on the disturbances corresponding to specific wavenumbers in the initial stage, which is consistent with TGA. In general, the topographic substrate affects the disturbance energy by changing the concentration distribution of surfactants, thereby influencing fingering phenomena.
    Analysis of flow characteristics of concave-wall jet in vertical cylinder with circumferential multi-inlets
    Jing ZHANG Shengchang WANG Zhiguo TIAN Jianhua WU Bin GONG
    The Chinese Journal of Process Engineering. 2022, 22(8):  1030-1039.  DOI: 10.12034/j.issn.1009-606X.221291
    Asbtract ( )   HTML ( )   PDF (3636KB) ( )  
    Related Articles | Metrics
    The material inlet was designed to be tangent to the cylinder wall and a concave-wall jet was formed in swirling-flow equipment. This work explored the influence of the concave-wall jets with circumferential multi-inlets in three-dimensional flow field. Realizable k-ε model was used and the turbulent flow near wall was dealt with by the non-equilibrium wall function, the superposition characteristics of circumferential multi-inlets flow field were numerically simulated. The study of the flow field showed that the superposition of flow parameter between front inlet and rear inlet increased firstly and then decreased with the increase of the inlet number. The area superposition of concave-wall jet was the strongest at the circumferential angle of 30°~40° behind the inlet cross-section, and the effect of the jet outside near the inlet was the greatest. The flow field in the vertical cylinder was more uniform because of the superposition of multiple jets, and the vortex structure was more stable near the axis. The superposition effects of circumferential multi-inlets concave-wall jet on the maximum values of tangential velocity, turbulent kinetic energy, and static pressure were greater than that of single inlet. The flow field of three inlets was closer to that of single inlet, and the superposition effect was the smallest. The research on the swirling-flow in multi-inlets structure with the same total flow rate showed that the centrifugal separation factor, turbulent kinetic energy, and static pressure had great correlation with the velocity of inlet cross-section, and the enhancement effect of superposition characteristics on the swirling-flow was not obvious. Therefore, the centrifugal separation factor and material handling capacity could be improved by increasing the multi-inlets jet velocity. Multiple-inlets effectively increased the fluid velocity in the swirling-flow device and the higher kinetic energy was produced near the inner wall. Increasing the number of inlets was an effective way to improve the swirling-flow effect. The research provided theoretical analysis and optimally designed references for the enhanced swirling-flow of related equipment.
    Numerical simulation of CO2 hydrogenation system in mixed catalyst bed at particle scale
    Bo JIN Yaxin ZHANG
    The Chinese Journal of Process Engineering. 2022, 22(8):  1040-1052.  DOI: 10.12034/j.issn.1009-606X.221292
    Asbtract ( )   HTML ( )   PDF (7777KB) ( )  
    Related Articles | Metrics
    The effective conversion of CO2 is important for achieving the goals of peak carbon dioxide emissions and carbon neutrality. Cylindrical particles have better thermal conductivity but smaller surface area when compared with heteromorphic particles, therefore, for better bed performance, the discrete element method (DEM) is used to perform particle-scale CFD simulations of a CO2 hydrogenation system in a mixed bed of heterogeneous particles, to investigate the effect of different stacking methods on the multi-physical field distribution, CO2 conversion and CH4 yield in the bed. The results show as follows: there is a diffusion resistance within the catalyst, as the reaction progress, the material within the particles changes from stratified distribution to uniform distribution. Compared to conventional beds, random mixed beds are less prone to hot spot fluctuations before steady state and has higher yields at steady state, while columnar bed have a more uniform radial heat field and higher hot spot. Of the four regular mixed beds, the two catalyst beds with 4 holes at bottom have more uniform overall flow fields, fewer high velocity zones, larger pressure drops, a larger proportion of high temperature zones and less fluctuation of hot spot before steady state than the two catalyst beds with columnar bottom. 2-layer mixed stacking-bottom 4 holes catalyst bed has maximum steady-state exit CO2 conversion and CH4 yield. The 4-layer mixed stacking-bottom 4 holes catalyst bed has high percentage of the high temperature region, which tends to increase as the reaction progress, resulting in significant decrease in CO2 conversion and CH4 yield.
    CFD simulation of thermal runaway esterification reaction in stirred tank
    Biqing CHEN Xiaoping GUAN Ning YANG Dingrong BAI
    The Chinese Journal of Process Engineering. 2022, 22(8):  1053-1060.  DOI: 10.12034/j.issn.1009-606X.221317
    Asbtract ( )   HTML ( )   PDF (4055KB) ( )  
    Related Articles | Metrics
    Thermal runaway is one of the common risks in chemical process safety. Thermal runaway accidents of various scales cause a lot of economic losses every year. The runaway of batch stirred reactor is particularly dangerous due to the single way to control the reaction rate.From the view point of intrinsic safety, optimal design of reactor and operating conditions can fundamentally prevent thermal runaway. In batch-operated stirred tank reactors, impeller rotation can enhance flow circulation, turbulence intensity, mixing degree, and heat transfer, thus effectively preventing thermal runaway. In this work, according to the esterification reaction of propionic anhydride and isopropanol to produce isopropyl propionate and propionic acid under the catalysis of concentrated sulfuric acid, CFD simulation was carried out to simulate the thermal runaway esterification reaction in stirred tanks. The effects of impeller type (Rushton impeller, 30° pitched blade turbine impeller and 60° pitched blade turbine impeller), rotation direction, and baffle on the temperature evolution were studied. The simulated flow structures were used to explain the effects. Furthermore, divergence criterion was used to compare the performance of resisting thermal runaway for different impellers. The simulation showed that the radial flow agitator performed better than the axial flow agitator at the same rotation speed, and the performance order was Rushton impeller>30° PBTD impeller>60° PBTD impeller. For the 30° PBT impeller, when the operating mode changed from PBTD to PBTU, the capability to resist thermal runaway weakens, though the number of circulation zone increased. The situation of 60° PBT impeller was similar to that of 30° PBT impeller. The addition of baffle can substantially improve the thermal control in the reactor. This research provided fundamentals for design, optimization, and scale-up of reactors.
    2D and 3D numerical study on the interaction of shock wave and sub-millimeter water droplet
    Honghui SHI Yixin ZHANG Shun SHI Ruoling DONG Shuangshuang PENG
    The Chinese Journal of Process Engineering. 2022, 22(8):  1061-1073.  DOI: 10.12034/j.issn.1009-606X.221240
    Asbtract ( )   HTML ( )   PDF (2930KB) ( )  
    Related Articles | Metrics
    The interaction of droplets with a shock wave widely exists in the fields of aerospace and fire fighting. And droplet breaking is the key process. At present, the initial diameter of droplet breakup is mainly at the millimeter level, and the research work on numerical study of sub-millimeter droplet deformation and breakup is still insufficient. For the purpose of studying the interaction process of sub-millimeter droplets with a shock wave, based on the existing experimental results, this work used VOF (Volume of Fluid) multiphase flow model and k-ε turbulence model to analyze the motion parameters of droplets in time and space. The influence of different Weber number (We) on the deformation and evolution of sub-millimeter droplets was analyzed by two-dimensional numerical simulation, and the explosive breaking mechanism of sub-millimeter droplets was revealed by three-dimensional numerical simulation. The results showed that Weber number can promote droplet deformation, and the greater the Weber number, the shorter the time required for droplet compression deformation. In the process of compression deformation, the dimensionless transverse deformation width of droplets with different crushing modes changed linearly with dimensionless time. Under the condition of constant aerodynamic force, the centroid acceleration of sub-millimeter droplets in the same crushing mode was inversely proportional to the initial diameter of droplets. The lateral spreading rate of droplets decreased with the increase of Weber number at low Weber number, while increased with the increase of Weber number at high Weber number. The breaking mechanism of sub-millimeter droplet explosive breaking mode was shear-induced entrainment mechanism. The numerical simulation results in this work were close to the comparative experimental results, which effectively illustrated the effect of Weber number on sub-millimeter droplet deformation.
    Simulation of carbon segregation during electroslag remelting of H13 die steel
    Yiru DUAN Baokuan LI Xuechi HUANG Zhongqiu LIU Yuying CHAI
    The Chinese Journal of Process Engineering. 2022, 22(8):  1074-1084.  DOI: 10.12034/j.issn.1009-606X.221357
    Asbtract ( )   HTML ( )   PDF (5841KB) ( )  
    Related Articles | Metrics
    Macrosegregation generally exists in the electroslag remelting (ESR) ingot, which seriously affects the homogeneity and quality of the ingot. A three-dimensional unsteady ESR mathematical model was established to study the macrosegregation phenomenon during ESR of large H13 die steel, and the interaction between alloying elements was considered. The anisotropic porous media model was used to simulate the momentum attenuation in the mushy zone. And solute redistribution behavior was calculated by the lever algorithm. The accuracy of the model was verified by experiments, and the distribution trend of carbon segregation index between simulation results and experimental results agree well. The simulation results showed that, at the beginning of melting, the metal pool was shallow and flat, and the metal rapidly solidified under the action of the cooling water in the bottom tank. With the progress of melting, the cooling effect of the bottom tank was weaker than the sidewall of the crystallizer, the metal pool profile deepened, and the carbon element was enriched at the bottom of the metal pool, and the concentration increased gradually. The bottom and edge of the ESR ingot showed negative segregation, while the center and top showed positive segregation. And the distribution of carbon segregation in ESR ingot did not change whether the initial element mass fraction and operating current were changed or not. When other initial elements were constant, the initial mass fraction of silicon increased from 0.8wt% to 1.2wt%, and the positive segregation index of carbon increased by 8.57%; The initial mass fraction of molybdenum increased from 1.1wt% to 1.75wt%, and the positive segregation index of carbon decreased by 1.89%. Under the condition of increasing the initial mass fraction of silicon and molybdenum, the distribution of carbon can be more uniform. When the working current decreased from 3700 A to 3100 A, the maximum positive segregation index of carbon decreased from 0.0856 to 0.0837, decreasing by 2.22%.
    Research on vibration regeneration of granular bed based on Brazil nuts effect
    Jianhong WANG Xiaoyan MO Huiqi ZHANG Minshu ZHAN
    The Chinese Journal of Process Engineering. 2022, 22(8):  1085-1093.  DOI: 10.12034/j.issn.1009-606X.221384
    Asbtract ( )   HTML ( )   PDF (2228KB) ( )  
    Related Articles | Metrics
    In order to explore a low-cost and environment-friendly regeneration method of the granular bed, the effects of the average particle size ratio and volume ratio of the granules/dust, vibration frequency, acceleration as well as amplitude on the vertical vibration separation of the granules/dust on Brazil nuts effects were studied by taking photos after vertical vibration. The results showed Brazil nuts could be formed when the average particle size ratio of slag/talc powder and slag/fly ash was not less than 75, and the average particle size ratio of quartz sand/talc powder and quartz sand/fly ash was not less than 65 and 15.3 respectively. When the vibration acceleration and amplitude of slag/dust exceeded the critical value at the vibration frequency of 20~100 Hz, slag/dust changed from mixed state to Brazil nuts. With the increase of vibration frequency, the critical acceleration first increased and then decreased, reached the lowest value at 45 Hz, and then continued to increase. The critical amplitude first decreased with the increase of vibration frequency, reached the lowest value at 45 Hz, and then continued to increase. The optimum vibration frequency of Brazil nuts formed by the slag/dust system was 45 Hz, which was not affected by the slag particle size, dust type, and slag/dust volume ratio. However, the larger the particle size of slag and the larger the volume ratio of slag/talc was, the easier the separation of slag/talc was, and the formation of Brazil nuts was easier in slag/talc than in slag/fly ash. At the optimal frequency of 45 Hz, slag/talc powder and slag/fly ash could realize vertical vibration separation at low amplitudes of 1.01 mm and 1.36 mm, respectively. The vertical vibration method based on Brazil nuts effect is feasible to separate the dust from the granules in the granular bed, which is beneficial to the reuse of the granular material and improves the ability of the granular bed to capture fine dust. The vertical vibration is a promising method of regeneration of the granular bed.
    Floating and sinking experiment and mechanism of calcite coating?acid reaction
    Rongdong DENG Dingquan XING Jianghui ZHOU Shiqi LI Ruiqi ZHAO
    The Chinese Journal of Process Engineering. 2022, 22(8):  1094-1102.  DOI: 10.12034/j.issn.1009-606X.221225
    Asbtract ( )   HTML ( )   PDF (2240KB) ( )  
    Related Articles | Metrics
    Calcite, as a major gangue mineral, is often found in other calcium-bearing minerals. Froth flotation is the main method to separate calcite from other calcium minerals. However, due to the similar physicochemical characteristics of calcium-containing minerals, it is difficult to separate these minerals effectively by the conventional flotation method. Different from non-carbonate minerals, calcite has the characteristics of reacting with an acid to generate CO2 bubbles. These CO2 bubbles can effectively reduce the apparent specific gravity of calcite in a short time. Polyvinyl alcohol film has selective permeability, which can allow H+ to pass through and as a barrier to CO2 bubbles. The high polymer film can bind the generated CO2 bubbles on the surface of calcite. When there are enough CO2 bubbles, the calcite particles will float spontaneously and be separated from the calcium-containing non-carbonate minerals. The coating effect directly affects the separation effect. Therefore, it is necessary to determine conditions of appropriate coating and acid reaction to improve the effectiveness of calcite coating-acid reaction. In this work, the main factors that affect the calcite coating-acid method were systematically studied through single factor experiments and orthogonal experiments. The optimum conditions of sulfuric acid concentration, PVA type and concentration, methyl isobutyl carbinol (MIBC), and sodium dodecyl sulfonate (SDS) concentration were screened by a single factor test. The orthogonal test was carried out for three factors, acid concentration, PVA concentration, and MIBC concentration. The results showed that the coating-acid reaction method can realize the self-floating of calcite particles (1 mm). The optimum conditions of the calcite coating-acid reaction method were sulfuric acid concentration of 2.0wt%, PVA type of P139546, PVA concentration of 2.4wt%, and 40 mg/L MIBC which was conducive to the floating of calcite. Under these conditions, the floating rate of calcite was 84.9%, and the average floating time was 28.8 s. The combination of SDS and PVA can effectively improve the floating time of calcite, while the floating rate was lower than that without SDS. PVA concentration and acid concentration were the main factors affecting the calcite coating-acid reaction method.
    Thermodynamic model for the phase equilibrium of cerium carbonates in the NaCl-H2O system
    Feng LUAN Daoguang WANG Junfeng WANG Jianwei ZHANG Penglei CUI
    The Chinese Journal of Process Engineering. 2022, 22(8):  1103-1114.  DOI: 10.12034/j.issn.1009-606X.221348
    Asbtract ( )   HTML ( )   PDF (3693KB) ( )  
    Related Articles | Metrics
    Cerium carbonates are important precursors for the production of CeO2, which have a decisive effect on the properties of CeO2. The crystal characteristics of cerium carbonate compounds depend on the control of supersaturating in reactive crystallization, and the solubility of cerium carbonate compounds in the NaCl-H2O system are important basic data. In this work, cerium carbonates were synthesized by homogeneous precipitation method at the temperature range of 298.15~363.15 K. The generated solids were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM) and thermogravimetric analyzer (TG). The results showed that Ce2(CO3)3?8H2O was obtained below 323.15 K and transferred to CeCO3OH above 343.15 K. The solubility of the two cerium carbonate compounds in the NaCl-H2O system were determined by the classical isothermal method. The results showed that the solubility of Ce2(CO3)3?8H2O increased with the increase of temperature and concentration of NaCl, while the solubility of CeCO3OH increased with the increase of concentration of NaCl, and decreased with the increase of temperature. The solubility of Ce2(CO3)3?8H2O in water at 298.15 K was 4.08×10-6 mol/kg, which was of the same order of magnitude as the solubility of cerium carbonate [Ce2(CO3)3] that was 2.17×10-7~2.17×10-6 mol/kg at 298.15 K. The results indicated the reliability of the experimental data measured in this work. A thermodynamic model for predicting the solubility of Ce2(CO3)3?8H2O and CeCO3OH in the NaCl-H2O system was finally established by using the ELEC-NRTL equation embedded in the Aspen Plus platform. The solubility products of Ce2(CO3)3?8H2O and CeCO3OH were obtained by regression of their solubility data in water on the basis of an infinite dilution assumption. The species such as CeCO3+, CeOH2+, CeHCO32+ were introduced into the thermodynamic model on basis of the speciation method and their equilibrium constants were calculated by Van't Hoff isothermal formula. The new ion pair parameters of Ce3+-HCO3- and Ce3+-Cl- were obtained by regression of the experimental data to improve the predictive ability of the new model. The predicted values of the established thermodynamic model were well in agreement with the experimental data.
    Study on oxyfuel combustion behavior and the intrinsic kinetics of typically sized coal particles
    Haolong BAI Liangliang FU Guangwen XU Dingrong BAI
    The Chinese Journal of Process Engineering. 2022, 22(8):  1115-1123.  DOI: 10.12034/j.issn.1009-606X.221256
    Asbtract ( )   HTML ( )   PDF (1151KB) ( )  
    Related Articles | Metrics
    Oxyfuel combustion is a promising technology to facilitate carbon capture from combustion-generated flue gases. Circulating fluidized beds (CFBs), the major commercial-scale boilers, will play a significant role in the energy industry's transition from today's carbon-intensive to carbon neutral in the future. The types of boilers combust coals of wide screening particle sizes of 0~10 mm. The difference in coal particle size inevitably leads to a considerable variation in combustion characteristics, which has not yet been fully understood. In particular, little is known about the dynamic evolution behavior of combustion gas products and the intrinsic kinetics of the in-situ produced nascent char particles when these typically sized coal particles are combusted in fluidized beds. For this reason, an advanced micro fluidized bed reaction analyzer (MFBRA), integrated with a fast-responding process mass spectrometry, was employed to investigate the oxyfuel combustion behavior of two typically sized coal particles (i.e., 1.7~3.35 mm and 0.12~0.23 mm), typical of those in dense region and dilute region in CFBs, at 790~900℃. The use of MFBRA enabled the successful detection and characterization of the dynamic combustion process-sequentially occurring devolatilization and combustions of the in-situ produced volatiles and the nascent char particles. The results demonstrated that the combustions of volatiles and nascent char particles can have similar or different rates depending on the coal particle size. The two major successively occurring dynamic processes were distinctively identified and characterized for the coarse particles but not for the fine particles, which were featured with similar reaction rates for the two processes. The combustion of coarse char particles was rate-controlled by kinetics at low temperatures and changed to interparticle diffusion control at high temperatures. The combustion kinetics of the volatiles and nascent char were analyzed, and the corresponding values of activation energy were 107.2 and 143.9 kJ/mol, respectively.
    Thermal performance analysis of closed heat pump membrane distillation electroplating wastewater system
    Youde PENG Chen YUE Wenbo YU Hao GE Shangjun YAO
    The Chinese Journal of Process Engineering. 2022, 22(8):  1124-1136.  DOI: 10.12034/j.issn.1009-606X.221322
    Asbtract ( )   HTML ( )   PDF (1627KB) ( )  
    Related Articles | Metrics
    Electroplating wastewater is one of the extremely harmful sewages, which must be pretreated before being discharged. The evaporation method can be used to pretreat the electroplating waste water and recover it waste resources, but its shortcomings of high energy consumption limit its use. Through coupling a closed heat pump cycle and the membrane distillation process, a novel electroplating wastewater treatment system is proposed in this work to pretreat the electroplating wastewater, the metal salts is recovered and the energy consumption is low. Based on the Aspen Plus simulation platform, the proposed system model is built. After verifying the key components model with the experimental data, the key operating parameters influences on the overall thermodynamic performance of the system have been investigated, and the following results are obtained. Increasing the feed rate caused a substantial increase in the power consumption of the system, but impacted little on the latent heat of the distillation membrane, so the feed rate had the greatest impact on the gain water ratio (GOR) of the system. Due to the increase in processing flow, the yield ratio (YRO) of the system increased slightly, but the feed rate showed almost no effect on the coefficient of performance (COP) of the system. The evaporation temperature had a great influence on the COP of the system, and the COP increased with the increase of the evaporation temperature. The downward trend of the system GOR decreased slowly and then steeply with the feed temperature increase. The GOR of the system was affected by the evaporation temperature and increased as the evaporation temperature was increased. YRO was affected by the combination of evaporation temperature and system power consumption, and showed different trends at high and low feed temperatures. The feed concentration played an important role in the YRO. YRO increased as the feed concentration was increased. The GOR at different concentrations was closer at the low feed temperature. Therefore, these results can provide significant references for the further implementation and optimization of the proposed system.
    A multi-objective optimization and decision?making method of carbon-hydrogen-oxygen symbiosis network in EIPs
    Hongchuan DENG Wenxu LU Xiaoyong LUO Yanlin LÜ Wan WANG
    The Chinese Journal of Process Engineering. 2022, 22(8):  1137-1146.  DOI: 10.12034/j.issn.1009-606X.221249
    Asbtract ( )   HTML ( )   PDF (1050KB) ( )  
    Related Articles | Metrics
    In view of the carbon-hydrogen-oxygen symbiosis networks (CHOSYNs) in eco-industrial parks (EIPs), a multi-objective optimization and decision-making method is proposed based on multi-scale atomic targeting method, considering economic and environmental factors and the reuse of by-product of carbon-hydrogen-oxygen compounds, and the optimal scheme is obtained from the alternatives. In this method, the mathematical programming method is adopted, and the global optimization is carried out with the minimum total annual cost (TAC) and carbon-dioxide annual emission (CAE) as the objective functions respectively, and the mixed-integer nonlinear programming (MINLP) model is established. Using the ε-constraint method, the CAE is transformed into constraint conditions, and the Pareto front of the TAC and CAE is obtained. It is found that the TAC is inversely proportional to CAE. The linear programming technique for multidimensional analysis of preference (LINMAP) and technique for order preference by similarity to ideal situation (TOPSIS) methods are used to make the optimal decision on the Pareto frontier. It is found that they choose the same point as the optimal decision. Based on the proposed method, an industrial park is optimized. The results show that the rational use of the existing by-product of carbon-hydrogen-oxygen compounds can reduce the cost of the raw materials, and reduce the TAC and CAE by 63.44% and 76.99%, respectively.