Table of Content

22 March 2020, Volume 20 Issue 3

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Contents

Contents and Cover

Chin. J. Process Eng.. 2020, 20(3):  0. 

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Reviews

Research progress in preparation and application of high-entropy oxides

Houzheng XIANG Feng QUAN Wenchao LI Xiaolei LIU Aiqin MAO Haiyun YU

Chin. J. Process Eng.. 2020, 20(3):  245-253.  DOI: 10.12034/j.issn.1009-606X.219228

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As a new type of oxide system, high entropy oxides have broken the traditional design concept of doped oxide and are composed of five or more kinds of oxides in equal or nearly equal mole. Because of its simple structure and excellent performance, it has been widely concerned by researchers at home and abroad in recent years. High-entropy oxides tend to form solid solution structures such as rock-salt type, calcium fluoride type, spinel type or perovskite due to the disordered arrangement of multiple principal elements. Therefore, it shows various excellent performances, especially in energy storage materials and magnetic materials, which has a very broad application prospect. However, there are few research on high-entropy oxides, especially on the application of high-entropy oxides. This work first introduced the preparation methods of high-entropy oxides at home and abroad, mainly including solid state reaction method, pyrolysis method, co-precipitation method, hydro-thermal synthesis method and solution combustion synthesis method. In addition, the advantages and disadvantages of each method were also discussed, and these offered a wide range of flexible approaches for different type of applications of high-entropy oxides. Then the applications of high-entropy oxides as Li-ion electrode materials, giant dielectric materials, magnetic materials and catalytic materials were summarized. At last, the problems of high-entropy oxides in the present research were pointed out, and the future developments were also prospected. This review had certain guiding significance for the expansion of the application of high-entropy oxides subjects in the future direction.

Flow & Transfer

Numerical simulation of the effect of split packing on gas flow field for rotation packed bed

Zhihong WANG Zhixi LIU Yongjun LI Shicheng WANG

Chin. J. Process Eng.. 2020, 20(3):  254-264.  DOI: 10.12034/j.issn.1009-606X.219215

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A simplified split packing rotation packed bed (SP-RPB) model was designed, and the computational fluid dynamics (CFD) method was used to simulate the steady-state gas flow field compared with the same size general rotation packed bed (RPB). The influence of different rotation speed and feed rate on gas phase pressure, relative velocity and turbulent kinetic energy distribution were compared and analyzed. The pressure drop across each mesh lap was examined as well. Counters of gas velocity and pressure of RPB and SP-RPB in steady state had been obtained, in order to understand the hydrodynamic and flow patterns deeply. The plots of different rotation speed or feed rate attribute to pressure, relative velocity and turbulent kinetic energy also were investigated. They pointed out that the relative velocity of the gas entering each packing rings was the highest in the vicinity, and the distribution of turbulent kinetic energy was the same. And the appearance of each peak was determined solely by the arrangement of the packing ring. Both results of them indicated that SP-RPB could have multiple end effect regions located at packing ring edge. The increase in rotation speed had a more pronounced effect on the peak level than the feed rate. And the larger feed rate caused the velocity of the gas in the filler fluctuate more intensively, the peak value of the turbulent kinetic energy increased. Due to the thinner thickness of the packing in SP-RPB compared with the same size of RPB, the SP-RPB exhibited a lower pressure drop over the entire equipment range. By increasing the feed rate and reducing the rotation speed, the high pressure in the RPB range between the two packing layers of SP-RPB could be reduced. In addition, the pressure drop of SP-RPB on unit mesh lap was larger than PRB with the same size.

Numerical simulation of solid-liquid flow in stirred tanks based on KTGF model

Ximing LI Shengli NIU Tongxin QU Kuihua HAN Chunmei LU Yongzheng WANG

Chin. J. Process Eng.. 2020, 20(3):  265-275.  DOI: 10.12034/j.issn.1009-606X.219238

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Based on the stirred vessel with baffles and disc turbine paddle, a three dimensional Euler–Euler simulation combined with kinetic theory of granular flow (KTGF) was carried out to explore effects of structure and impeller speed on flow behavior of particles. Furthermore, the simulated solid volume fraction was compared with the experimental solid volume fraction to verify the validity. Contour plots of particle temperature and turbulent kinetic energy on horizontal cross-section were obtained to comprehend the effects of flow patterns and hydrodynamic on solid phase concentration distribution. The results showed that the particle temperature distribution at the bottom of the stirrer vessel was consistent with the solid phase concentration distribution. Based on the kinetic theory of granular flow, the influence of the baffle obstruction and the impeller speed on the solid phase concentration distribution can be reasonably explained. As the impeller speed grew up, the two-phase turbulent motion in the vessel enhanced, the particle temperature, turbulent kinetic energy and axial velocity increased, and the particle distribution became more uniform, but the particle temperature tended to be stable after reaching the complete suspension state. The accumulation of particles at the bottom of the vessel and the baffle led to an increase in local solid volume fraction and a decrease in the average free path of the particles, which in turn reduced the particle temperature. Moreover, the baffles formed a two-loop flow pattern in the vessel, which enhanced the turbulence of the fluid. But it caused accumulation of particles at the baffle, which was not conducive to the uniform distribution of the solid phase at the baffle.

Thermal mechanical characteristics analysis of trough solar collector with microencapsulated phase change suspensions

Yu ZHANG Liting TIAN Xiaopeng YUE Kun WANG

Chin. J. Process Eng.. 2020, 20(3):  276-284.  DOI: 10.12034/j.issn.1009-606X.219213

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In view of the low heat transfer effect and high thermal stress of tube wall of traditional water-based and oil-based solar collectors, three-dimensional modeling of parabolic trough solar collectors was carried out with phase change microcapsule suspension as the working fluid. The optic-thermal- mechanical coupling problem of solar thermal tube was solved by combining the Monte Carlo ray-trace method, the finite volume method and the finite element method. The heat transfer and thermal stress of microcapsule phase change material slurries in a collector tube were numerically studied by using Eulerian?Eulerian multiphase flow model. The results showed that the microencapsulated phase change material slurries enhanced the convection heat transfer in the collector tube, reduced not only the temperature along the flow path of the collector tube, but also the circumferential temperature difference and homogenized the temperature distribution of the collector tube. The circumferential effective thermal stress on the collector wall was the petal shaped distribution, and the five regions (circumference angle θ=5°, 90°, 175°, 225° and 315°) with higher temperature gradient corresponded to the local maximum of the effective stress. The axial thermal stress at θ=90° on the wall surface behaved as compressive stress along the absorber tube, while the radial thermal stresses and tangential thermal stresses mainly behaved as tensile stress at the tube inlet and outlet ends. The more the mass fraction of the microencapsulated phase change material slurries was, the better the enhanced heat transfer effect was, and the smaller the thermal stress on collector was, but the resulting pressure drop also increased.

Analysis of resistance characteristic of non-woven fiber needle felting mat pleated filter bag

Can FANG Fuping QIAN Mengmeng YE Yunlong HAN Jinli LU

Chin. J. Process Eng.. 2020, 20(3):  285-293.  DOI: 10.12034/j.issn.1009-606X.219217

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In order to achieve optimization of the structure of pleated filter bag, the three-dimensional geometric models of pleated filter bag were correspondingly established under different pleat numbers based on ɑ, which was the ratio of pleat height to pleat width. Then the gas flow field characteristics of pleated filter bags were simulated with porous medium and standard k?? model under some circumstances that when the pleat number N=8, 12, 16, 20, 24 and bag length L=2.5, 3.0, 3.5 m. The results showed that under the same inlet velocity, the filtration resistance of pleated filter bag with the number of pleats N=12 (ɑ=1.12) was smallest, and the growth rate of the filtration resistance was significantly no larger than the other four number of pleats, the distribution of the flow field inside the bag house was more uniform, so the pleated filter bag with N=12 was better adaptable to different treatment air volumes. The filtration resistance of pleated baghouse precipitator with different bag lengths increased with the increase of inlet velocity in the form of a quadratic curve. When the air volume was small, the longer the pleated filter bag was, the smaller the pressure drop of system was, but the pleated filter bag was too short or too long to fit the operation condition of high air volume due to the large pressure drop of the system. The pressure gradient in vertical of the filter bag with L=3.0 m was relative less, both the pressure and velocity distribution in the bag house were relatively more homogeneous, which was beneficial to protect the filter bag and energy-saving.

Simulation on flow characteristics of spherical convex–concave structure in microchannel of pressure-filtered water electrolyzer

Juan WANG Jun LI Shuo ZOU Xingchen HE Jiayi WAN Yu ZHOU

Chin. J. Process Eng.. 2020, 20(3):  294-301.  DOI: 10.12034/j.issn.1009-606X.219232

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Pressure-filtered electrolyzer is the key equipment in the process of hydrogen production from water electrolysis. Spherical convex–concave structure is arranged in the microchannel of electrolyzer plate. The distribution of water flow in the microchannel directly affects the distribution of electrolyte and heat transfer, thus affecting the stability of the electrolyzer. In order to study the flow field characteristics in the plate channel of pressure-filtered water electrolyzer, the RNG k?? turbulence model was used to simulate the flow field in the single pole chamber of the electrolytic units, and the eddy generated in the channel and the uniformity of velocity distribution were analyzed. The results showed that the structure of the plate passage determined the location of the eddy, which affected the velocity distribution in the passage. With the increase of the mass flow rate, the intensity of the eddy increased and the disturbance degree increased. The velocity distribution of the flow was symmetrical, and the curve of velocity distribution caused by the spherical convex–concave structure had fluctuation. There were peak velocities at the edge positions of different spherical convex structures. The uniformity index of velocity distribution along the flow direction was different under various flow conditions. The disturbance effect of spherical convex–concave structure could improve the uniformity of velocity distribution, but the improvement effect was different under various flow conditions.

Flow behaviors of FT catalyst in gas-solid fluidized bed

Liuhai FENG Yuqi FENG Jie ZHAO Zhuowu MEN Xi LI Yifeng BU

Chin. J. Process Eng.. 2020, 20(3):  302-307.  DOI: 10.12034/j.issn.1009-606X.219147

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To study the flow process of the Fischer?Tropsch (FT) catalyst in the gas?solid fluidized bed, the main physical parameters of the catalyst were analyzed firstly. And then the flow behaviors of the FT catalyst in different superficial gas velocities in the fluidized bed with different diameters were measured. Finally the flow behaviors of the fluid catalytic cracking (FCC) catalyst, which was widely used in the field of catalytic cracking of petrochemical industry, were compared with that of the FT catalyst. It was found that, although the FT catalyst and the FCC catalyst were both Geldart-A particles, the FT catalyst had smaller stagnation angle (almost 75% of that of the FCC catalyst). This caused that the FT catalyst had lower minimum fluidization velocity, less expansion height, less surge height. The fluidization process of the two catalysts in the gas?solid fluidized bed were basically similar, including the expansion, bubbles, turbulent and other flow patterns, which appeared successively with the increasing superficial gas velocity. However, the critical velocities during the transition between different flow patterns were quite different. The results showed that the physical parameters of the catalysts affected the flow characteristics considerably. Comparing with the FCC catalyst, the FT catalyst was much stable in each step during the fluidization process, which was benefit to the uniform distribution of the catalyst in the gas–solid fluidized bed. Consequently, the contact performance of the FT catalyst was better than that of the FCC catalyst. Furthermore, with different ratios of bed height to diameter, the turning points of the surge height were related with the flow patterns. Therefore, the relationship between the surge height and the superficial gas velocity could be the estimation basis of the critical velocity in different flow patterns of the turbulent fluidized region.

Reaction & Separation

DFT study on the extraction and separation of copper and nickel with Metral54-100

Xingguo LUO Hui HUANG Chang WEI Xingbin LI Zhigan DENG Minting LI

Chin. J. Process Eng.. 2020, 20(3):  308-317.  DOI: 10.12034/j.issn.1009-606X.219231

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In order to discuss the extraction and separation mechanism of copper and nickel by 1-phennyl-1,3-sebacic-diketone (Mextral54-100) from ammonia solution, the binding energy, global activity indices, local activity indices and infrared spectrum (FT-IR) of copper complexes and nickel complexes were calculated by density functional theory DFT/B3LYP/6-31G+(d, p), based on quantum chemistry. The results showed that the extracting power of copper was beyond nickel with Mextral54-100. Global reactivity indexes pointed out that the order of the activity of the copper complexes was a>b>c, the order of the activity of the nickel complexes was d>e>f. The molecule frontal orbital analysis of the complexes indicated that the |Δe| (Δe=eHOMO?eLUMO) of a was |Δe|a=0.158, the |Δe| of d was |Δe|d=0.138, thus, the reaction activity of a was higher than that of d, and the copper complexes were easier than nickel complexes in the stripping process by the theoretical calculation results. Local activity indices showed out that the carbonyl exhibited the highest reactivity and was the active center. The more substitution number of ammonia molecules in the complexes, the stronger electron-donating ability of copper(II) and nickel(II), and the structure of the complex was similar to the stable octahedral structure. The ammonia molecules were replaced one by one by the carbonyl group in extractants, avoiding the co-extraction of ammonia effectively. The experimental results of extraction and stripping of copper and nickel from ammonia solution by Mextral54-100 were in good agreement with the theoretical calculation results by DFT, and which could be verified the accuracy of theoretical calculation results by FT-IR. What was more, DFT was expected a novel method to study the extraction and separation mechanism copper and nickel from ammonia solution in the future.

Phase equilibrium and separation of AlCl₃–FeCl₃–HCl–H₂O system

Lixiang WU Jing ZHAO Fangbin XUE Huaigang CHENG Fangqin CHENG

Chin. J. Process Eng.. 2020, 20(3):  318-323.  DOI: 10.12034/j.issn.1009-606X.219223

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In order to extract high purity AlCl3?6H2O from acid leaching solution of aluminum/iron-containing fly ash, it is necessary to determine the phase equilibrium data of AlCl3–FeCl3–HCl–H2O quaternary system under acidic condition. The phase equilibrium data of the AlCl3–FeCl3–HCl–H2O system with H+ concentration of 1.3 mol/L at 20 and 30℃ were determined using the isothermal dissolution equilibrium method. The phase diagrams and density?composition charts of the system were drawn. The results showed that the salt?water system was simply co-saturated at 20 and 30℃, and there was not any double salt and solid solution. The density of saturated solution increased gradually with the increase of FeCl3 concentration, and finally tended to be stable. After reaching the co-saturation, the density of solution at 30℃ was obviously higher than that of solution at 20℃. With the increase of temperature, the solubility of FeCl3 increased from 43.59% to 49.34%, the solubility of AlCl3 was about 30.70%, which was almost unchanged. It was also found that the crystallization zone of FeCl3?6H2O decreased and the crystallization zone of AlCl3?6H2O increased. According to the AlCl3–FeCl3–HCl–H2O phase diagram, the isothermal evaporation route analysis of the acid leaching liquor was carried out. The simulated acid leaching solution of aluminum and iron was used to evaporate and crystallize. The purity of AlCl3?6H2O directly separated from acid leaching solution reached 96.61%, and the recovery rate was 75.88%. Then the acid leaching liquor with different iron content was added to evaporate and crystallize, and the products were compared and analyzed. It was found that the purity of the product increased gradually with the decrease of iron content in the feed acid leaching liquor. When the contents of AlCl3 and FeCl3 in solution were 14.83% and 0.33%, the purity of AlCl3?6H2O crystals reached 99.61%, with the decrease of iron content in acid leaching solution, the purity of crystalline products was higher.

Process & Technology

Influence of temperature on on-line detection of particulate matter using OPC device

Mingxing WANG Xiaolin WU Zhongli JI Lifeng LU Xuan SONG

Chin. J. Process Eng.. 2020, 20(3):  324-331.  DOI: 10.12034/j.issn.1009-606X.219197

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In high temperature particles on-line detection experiments, with the spherical SiO2 particles as the research object, a high-temperature test bed was set up for this research. By utilizing optical particle counter (OPC), the quantity and cumulative distribution of particles with different particle sizes were measured under the operating condition of 25?800℃. The spherical SiO2 dust particles were observed and analyzed by SEM and XRD. The results showed that the particle size of spherical SiO2 particles first decreased, then increased and decreased later with the increase of heating temperature, while the shape and size of the particles at the corresponding temperature did not change. The XRD patterns showed that the diffraction intensity of spherical SiO2 particles became smaller, and the diffraction peak was broadened and shifted approximately at 2θ=25.5o. The unit cell volume of spherical SiO2 particles increased first and then decreased. Thus, a conclusion can be drawn that the connection between SiO2 unit cell volume and crystal dielectric constant led to the change of the internal structure of SiO2 particles, as a result the refractive index of the particles crystal changed, thus resulting in a change in the refractive index, making the measurement results have 2~3 size error and the measurement accuracy was affected.

Effect of Cu²⁺ on improvement of molybdenite floatability in magnetized distilled water

Jingwen XUN Yubin WANG Xiao WANG Zhen WANG Yan WANG

Chin. J. Process Eng.. 2020, 20(3):  332-337.  DOI: 10.12034/j.issn.1009-606X.219198

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Magnetized water can improve the flotation behaviors of sulfide minerals such as molybdenite effectively, but the beneficiation index was unstable in flotation process of molybdenite by use of magnetized water. In order to investigate the effect of Cu2+ on the improvement molybdenite floatability in magnetized distilled water, different samples were characterized by means of the flotation test of pure molybdenite, Zeta potential, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results showed that the floatability of molybdenite in magnetized distilled water was improved with the addition of copper ion when the amount of kerosene was 160 mg/L and the amount of 2# oil was 80 mg/L. Furthermore, the molybdenite recovery rate reached 83.06% when the concentration of dissolved copper ion in magnetized distilled water was 320 mg/L. Compared with Cu2+ concentration of 0 mg/L, the flotation recovery rate of molybdenite increased by 3.14 percentage point. The Zeta potential of molybdenite in magnetized distilled water obviously increased positively direction because Cu2+ and Cu(OH)+ adsorbed on the surface of molybdenite. The Zeta potential of molybdenite increased with the increase of copper ions dosage which was beneficial to the adsorption of kerosene on molybdenite surface in local positive charge. The Cu2+ and Cu(OH)+ adsorbed on the fracture surface of molybdenite interacted with MoO42? in magnetized distilled water formed copper molybdate which covered on molybdenite surface, which decreased amount and reaction probability of reactive molybdenum and sulfur on molybdenite surface then inhibited the oxidation of molybdenum and sulfur elements on molybdenite fracture surface and the dissolution reaction of molybdenum oxide into solution. Therefore it highly improved the flotation behaviors of molybdenite. This work provided a certain theoretical basis for improving the flotation efficiency of molybdenite with magnetized water, and it also provided some degree of reference for the application of magnetized water in the process of ore.

Analysis of inflow process of Fe, Ni and Cr impurities in Ti sponge

Zhuo SHENG Kaihua LI Xiaozhe CHENG

Chin. J. Process Eng.. 2020, 20(3):  338-346.  DOI: 10.12034/j.issn.1009-606X.219220

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The impurity concentrations of Fe, Ni and Cr in Ti sponge determine its quality and application areas. In order to analysis the inflow process of Fe, Ni and Cr impurities in Ti sponge during Kroll process, the concentration distributions and enrich phases of impurities were investigated by testing the samples that taken from different parts of the Ti sponge mass, and the mixing enthalpies of Ti?Mg?Fe, Ti?Mg?Ni and Ti?Mg?Cr were calculated by Miedema model. The results indicated that the Fe, Ni and Cr impurities from the reactor which manufacture material was stainless steel (1Cr18Ni9Ti), and the inflow process could be divided into two step while TiCl4 was feeding: Fe, Ni and Cr atoms dissoluted in liquid Mg, alloying with Ti sponge for strong atomic force between Ti?Fe, Ti?Ni and Ti?Cr atoms. In order to obtain high quality Ti sponge which has lower impurities contents of Fe, Ni and Cr, following steps should be taken: coating the reactor inner surface with a titanium film, controlling the reaction temperature strictly, using lower Fe, Ni and Cr content liquid magnesium as raw material, separating the edge and bottom part of the Ti sponge mass.

Environment & Energy

Safety analysis of stainless steel slag used to prepare foam concrete

Hao ZHANG Hua CHEN Lei ZHANG Xiuyu LIU

Chin. J. Process Eng.. 2020, 20(3):  347-353.  DOI: 10.12034/j.issn.1009-606X.219218

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Stainless steel slag foam concrete was prepared using the stainless steel slag, cement, fly ash, foaming agent and water as raw materials. Chemical composition, micro morphology, mineral composition, structural, free CaO content, grindability, internal exposure index and external exposure index, activity index of the stainless steel slag and foam concrete were tested. In addition, the main performance parameters of the prepared foam concrete, such as compressive strength, dry density and heat conduction coefficient, leaching concentration of heavy metals were also studied. The results showed that the stainless steel slag had certain cementitious activity and good grindability owing to mineral composition of Ca2SiO4. The internal exposure index and external exposure index of the foam concrete satisfied the requirements of the limits of radionuclides in building materials, although it contained Al and heavy metals of Ti, Cu, Pb, Ta, etc. The dry density was 597?621 g/cm3, compressive strength was 1.83?2.98 MPa after curing 28 d and heat conduction coefficient was 0.11?0.12 W/(m?K), which satisfied the requirements of foam concrete, when 25wt%?42wt% stainless steel slag was used in the foam concrete. The main heavy metals in the stainless steel slag mainly existed as stable solid metals. The leaching concentration of heavy metals from the foam concrete was much lower than the limit value of the identification standards for hazardous wastes. Therefore, it was safe and feasible to utilize the stainless steel slag to produce foam concrete.

Effects of SiO₂ nanoparticle fillers on the performances of ionogel electrolyte and high voltage supercapacitors

Jiahe ZHANG Chunxian XING Haitao ZHANG

Chin. J. Process Eng.. 2020, 20(3):  354-361.  DOI: 10.12034/j.issn.1009-606X.219181

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Quasi-solid capacitor composed of polymer gel electrolytes are thinner, lighter, cheaper, and more flexible. They can be used as energy devices for wearable and portable electronic devices, and have a very broad application prospect. In this work, the ionogel electrolyte separator was constructed by a simple solution casting method with silicon dioxide nanoparticles as filler. The effects of silicon dioxide nanoparticles on the ion transport were exploited. Based on the ionogel electrolyte separator, a quasi-solid capacitor was constructed, and the influence of silicon dioxide nanoparticles on the performance of the capacitor was evaluated. The electrolytes with different amounts of silicon dioxide were studied. The results showed that the addition of silicon dioxide did not change the microscopic morphology of the ionogel electrolyte, but it effectively improved the wettability and the ionic conductivity of the electrolyte. The electrochemical performance of the electrolyte with high silicon dioxide addition was more beneficial. The electrolyte exhibited the most excellent ionic conductivity when 8wt% silicon dioxide was added. Quasi-solid electric double layer capacitors were assembled using activated carbon as the electrodes and ionogel electrolyte as the separator. Because silica dioxide effectively promoted ionic conductivity and reduced electrolyte internal resistance, the addition of silicon dioxide improved the performance of activated carbon quasi-solid capacitor effectively, the specific capacitance increased nearly 15%. After 4000 cycles, the device?s specific capacity was maintained at 100%. Due to the excellent high temperature stability of the electrolyte, the quasi-solid capacitor maximum operating temperature up to 60℃. The specific capacitance of the device gradually increased with increasing temperature, and the energy density reached 81.36 Wh/kg at 60℃. This work provided an effective guidance for constructing a complex ionogel electrolyte-based quasi-solid supercapacitor.

Co-combustion characteristics and kinetics of municipal sludge and rice husk hydrochar

Cong YE Xianjun XING Xuefei ZHANG Tao CHEN Jiajia ZHANG

Chin. J. Process Eng.. 2020, 20(3):  362-370.  DOI: 10.12034/j.issn.1009-606X.219210

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In recent years, there is very little report on the characteristics of the co-combustion between municipal sludge and biomass charcoal. Therefore, the thermal characteristics and kinetics of municipal sludge, rice husk hydrochar and their blends in the combustion process were investigated in this work. The mass percentages of rice husk hydrochar of in the blends were 10wt%, 30wt%, 50wt%, 70wt% and 90wt%, respectively. The experiments were performed via a thermogravimetric simultaneous thermal analyzer at different heating rates (10, 20 and 40℃/min) with a changing temperature ranged from room temperature to 1000℃. Meanwhile, the Flynn-Wall-Ozawa (FWO) method was used to calculate the reaction kinetic parameters during these combustion processes. The results showed that the mass of volatility, ignition and burnout index of rice husk hydrochar were all higher than those of municipal sludge and rice husk hydrochar had good combustion characteristics. As the ratio of mixed rice husk hydrochar increased, the residual mass of the mixture reduced and the ignition performance worsened, however, the combustion performance enhanced. And the correlation coefficient of the activation energy of the combustion of rice husk hydrochar, municipal sludge and their mixture were all higher than 0.95. When the ratio of rice husk hydrochar blended in municipal sludge was higher than 50wt%, the average activation energy of co-combustion was lower than the average activation energy of rice husk hydrochar burned alone, when the ratio reached 70wt%, the lowest average activation energy of 85.48 kJ/mol appeared. There was a synergistic interaction during the co-combustion process, and compared with other mixed rice husk hydrochar ratios, the co-combustion effect of samples was better when the ratio was 50wt%. The research results provided a preliminary theoretical basis for co-combustion of municipal sludge and rice husk hydrochar.