The Chinese Journal of Process Engineering

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Chin. J. Process Eng.

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Editorial from the Editor-in-Chief

Suojiang ZHANG

Chin. J. Process Eng. 2021, 21 (1): 1-2. DOI: 10.12034/j.issn.1009-606X.221001

Abstract （413）

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故岁将于今宵尽，新年将于明旦来。站在岁月新旧交替的边缘，回首往昔，思绪飞扬，我们感慨万千,展望未来，山高水长，我们携手并进！过去的2020年，注定是不平凡的一年，有恐慌、有感动、有付出、有收获，尽管历尽艰难，但每个人都在用自己的方式拥抱希望、播撒温暖、坚持信念，值得我们铭记一生。今天，2020年就要画上句号，《过程工程学报》也即将昂首挺胸，生机勃勃地迈入新的一年！

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Adsorption of heavy metal ion by sodium alginate based adsorbent-a review

Cheng GUO Xiangpeng GAO Mingyang LI Junjie HAO Hongming LONG Zhuo ZHAO

Chin. J. Process Eng. 2021, 21 (1): 3-17. DOI: 10.12034/j.issn.1009-606X.220059

Abstract （1112）

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Heavy metal pollution is one of the most important environmental issues in current industrial development. Due to its simplicity and low-cost, adsorption is regarded as one of the green and environmental friendly methods to remove heavy metals from aqueous solutions. Sodium alginate is a natural polysaccharide which contains significant amount of hydroxyl and carboxyl functional groups that has high affinity towards heavy metal ions. Currently, sodium alginate and its derivatives have been widely used to remove heavy metal ions from aqueous solutions in laboratories. Synthesized by surface grafting, crosslinking, and modification, sodium alginate based adsorbents have high adsorption capacities and great metal removal efficiency, which suggests potential industrial applications. However, due to the weak stability and thermos resistance, sodium alginate based adsorbents were limited in industrial applications. In this work, the development of sodium alginate based adsorbents, introduced the structure and chemical properties of sodium alginate, the adsorption performance and affecting parameters of sodium alginate based adsorbents were summarized. Finally, the adsorption mechanism was analyzed. In future studies, material science and environmental engineering could be combined in the adsorbent synthetic process to enhance the structure and adsorption behavior, which could provide potential applications to remove heavy metals from industrial effluents.

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Simulation of flow characteristics of radial flow absorber for oxygen production by vacuum pressure swing adsorption

Yikun SHI Ruijiang LI Xuedong ZHU Haican FANG Zibin ZHU

Chin. J. Process Eng. 2021, 21 (1): 18-26. DOI: 10.12034/j.issn.1009-606X.220029

Abstract （544）

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Vacuum pressure swing adsorption (VPSA) for oxygen generation is a complicated dynamic process. Understanding the flow characteristics is essential for the design and improvement of radial flow adsorber. A two-dimensional radial flow adsorber model of VPSA for oxygen generation was established based on the Fluent porous medium model with user defined functions. The flow characteristics of the first and second cycle in radial flow adsorber were analyzed. The effects of particle diameter, the perforated-plate opening ratios and the cross section ratio of central channel to outer channel were discussed. The results showed that the flow distribution and adsorption efficiency of radial adsorber were affected by the volume of both the central channel and the outer channel, which needed to be carefully considered when designing. The concentration and recovery rate of oxygen can be increased when smaller particles were used, which also improved the flow distribution. The increase of the cross sectional area ratio of central channel and outer channel was beneficial to flow distribution. The radial non-uniformity of velocity reduced with the decrease of the perforated-plate opening ratio of the central channel and outer channel, and the influence of perforated-plate opening ratio of central channel was more significant than that of the outer channel.

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Calculation and experiment on optimum charge for a small CO ₂ transcritical heat pump water heater with void fraction method

Dong WANG Yaru LIU Zhuo CHEN Zunli KOU Fuping QIAN Xiangzhi WANG

Chin. J. Process Eng. 2021, 21 (1): 27-35. DOI: 10.12034/j.issn.1009-606X.220031

Abstract （399）

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The consumption of powerful greenhouse gases should be drastically reduced worldwide due to the serious problem of global warming. Natural refrigerants CO2 is the most promising refrigerants and has been widely applied in small refrigeration systems because of the low global warming potential (GWP) and no ozone depletion potential (ODP). It is universally acknowledged that an optimum refrigerant charge existing in a small refrigerant system can maximize the coefficient of performance (COP) of system. In the present work, the void fraction method with 6 classic models was used to predict the optimum refrigerant charge of a small CO2 water-source heat pump water heater. Based on an existing unit in the lab, the changes of system performance were studied with various refrigerant charges by a series of relevant experiments and the optimum charge was obtained to verify the accuracy of all the void fraction models in the references. The results indicated that each model had a relatively good accuracy in determining the optimum refrigerant charge of the tested unit with the error less than 9.80%. Hughmark model could be recommended to predict the optimum refrigerant charge of the studied system because of the negligible errors by less than 2.59%. Moreover, in the view of heating energy efficiency ratio (EERheat), the value calculated by the Hughmark model was almost the same with that obtained from the experimental measurement. On the basis of a small system with a transcritical cycle, the optimum charge calculated by void fraction method was more accurate than the ones from experimental data method and rated working condition method. The present work can provide the guidelines of predicting the optimum refrigerant charge in small CO2 systems.

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Numerical calculation and analysis of flow field and filtration resistance for fiber media with gas slip effect

Hui YANG Hui ZHU Yongping CHEN Haiming FU

Chin. J. Process Eng. 2021, 21 (1): 36-45. DOI: 10.12034/j.issn.1009-606X.220080

Abstract （458）

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A numerical method was developed to calculate the flow field and filtration drag around nanofiber/microfiber with consideration of gas slip effect, and the effects of Knudsen number Knf and the fiber volume fraction C on velocity distribution around the fiber surface and fiber filtration resistance were discussed and analyzed. The results indicated that significant differences could be found between flow field around the fiber in slip flow regime and in no-slip flow regime for nanofiber/sub- microfiber filtration, especially for the case of high fiber volume fraction where the maximum slip velocity along the fiber surface approached the filtration velocity, however, the gas slip effect had a negligible influence on flow field and filtration resistance for large-scale microfiber filtration. Moreover, existing filtration resistance coefficient models developed for fibrous filter were inadequate in predicting nanofiber filtration resistance coefficient in slip flow regime, and orders of magnitude deviation could be seen between the different filtration resistance coefficient expressions. Based on the simulation results, a reliable expression for the nanofiber/microfiber filtration resistance coefficient in the range of 0.01≤C≤0.1 and 0.013≤Knf≤2 was developed.

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Mass transfer dynamics and breakthrough characteristics of L-valine separation by ion exchange

Jianjun CHEN Junwei ZHANG Qianning SONG

Chin. J. Process Eng. 2021, 21 (1): 46-56. DOI: 10.12034/j.issn.1009-606X.220013

Abstract （427）

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The separation effects of different types of resins, the mass transfer kinetics and the rate-controlling step, the breakthrough behavior in a fixed bed were studied respectively in order to investigate the kinetics and the dynamic breakthrough characteristics for the L-valine separated by ion exchange. The results showed that the adsorption capacity of strong acidic cation exchanger resin, with a better separation effect, were five to eight times that of other resins, meanwhile their selectivity was from 1.3 to 1.8. L-valine with amphoteric ionic sates in a neutral (or slightly acidic) solution, was beneficial to its exchange adsorption. Moreover, the pseudo-second order kinetic model was found to describe adsorption process of the L-valine well with 001×7 resin as a separation media, such a process was affected by the particle and the liquid film diffusions together at early stage and then by multiple factors at medium-latter stage. Thomas and Yoon-Nelson models could describe breakthrough behaviors of the L-valine and the L-leucine well. The equilibrium adsorption capacity qe, volume adsorption capacity N0 and operation time τ decreased gradually with enhancing flow rate of the L-valine feed, whereas the equilibrium adsorption capacity qe and volume adsorption capacity N0 increased but operation time τ decreased gradually with increasing feed concentration of the L-valine. The ratio of height to diameter should be less than 5 and had an opposite trend to the effect of feed concentration change of the L-valine.

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Experimental and model analysis of hydrochloric acid recovery by dynamic diffusion dialysis

Shuai SUN Hongqian SUN Jing SONG Jingkui QU Yong WANG Tao QI

Chin. J. Process Eng. 2021, 21 (1): 57-63. DOI: 10.12034/j.issn.1009-606X.220052

Abstract （506）

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In recent years, membrane separation technology has become the focus of industrial waste acid treatment and recovery with many advantages. As a kind of environmentally friendly membrane separation technology, diffusion dialysis is widely used in the field of waste acid. The experiment was carried out with 0.55 mol/L hydrochloric acid as raw material. Besides, the effects of operating parameters such as the flow rate of feed acid (620 mL/min) and flow ratio of water and acid (0.61.4) were examined. The transport of hydrochloric acids through anion-exchange membrane DF-120 in a counter-current continuous dialyzer was investigated in detail. The important parameter, permeability coefficient of the membrane, was optimized by polynomial fitting. A simpler mathematical model of lumped parameters established, which could predict the hydrochloric acid recovery rate during the diffusion dialysis process. These obtained points were investigated to verify the mathematical model and it was proved excellent. The model was used for predictions under more detailed experimental operating conditions. It also provided reference methods and arguments for actual industrial production.

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Experiment and calculation for phase equilibria in quaternary system of ammonium dihydrogen phosphate-diammonium hydrogen phosphate-ammonium polyphosphate-water

Xiaofu Lü Dehua XU Zhiye ZHANG Xinlong WANG Lin YANG

Chin. J. Process Eng. 2021, 21 (1): 64-70. DOI: 10.12034/j.issn.1009-606X.220042

Abstract （612）

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Ammonium polyphosphate is widely used in water soluble fertilizer industry due to its excellent water solubility, slow-release property and chelation. However, ammonium polyphosphate is easily hydrolyzed into ammonium dihydrogen phosphate and diammonium hydrogen phosphate in storage, and the composition of its aqueous solution changes continuously. Its solubility decreases with decreasing polymerization rate, causing crystallization and precipitation in the storage solution, that increases the cost of transportation and application. The quaternary phase diagram of ammonium dihydrogen phosphatediammonium hydrogen phosphateammonium polyphosphatewater at 25℃ was established by using Schreinemaker wet slag method, and the mass distribution of each component in saturated liquid and wet slag phase was obtained by ion chromatography and mass conservation equation. The reasons of crystallization and precipitation of ammonium polyphosphate solution were explained, which was a guidance for storage and use of ammonium polyphosphate as a high efficiency water-soluble fertilizer. The polymerization degree of ammonium polyphosphate was diverse due to the variety of ammonium polyphosphate products produced by the manufacturers. There were different solution systems while the ammonium polyphosphate as a compound fertilizer raw materials, and it was time-consuming and laborious to obtain phase diagrams by experiments for each system. The calculation of watersalt phase diagram by mathematical model can save a lot of experimental work and provide the basis for the agricultural use of ammonium polyphosphate. In order to quickly obtain phase diagrams of other ammonium polyphosphate systems, local composition model of electrolyte solution was introduced to get solvent (salt)salt interaction energy parameters of the experimental system. The phase diagram calculated by regression parameters was in good agreement with the experiment, and it can be used to predict the phase diagram of other ammonium polyphosphate systems.

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Multi-objective optimization of separation unit for coal-based methanol aromatization

Yandong GUO Hang SU Songsong CHEN Feng HUO Junping ZHANG

Chin. J. Process Eng. 2021, 21 (1): 71-82. DOI: 10.12034/j.issn.1009-606X.220078

Abstract （428）

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The development of new technologies for synthesizing xylene from methanol has great significance in China, as the coal-based chemical products have been redundant and homogeneous seriously. Due to the challenge of high energy consumption in the chemical separation process, a multi-objective optimization research was carried out in the separation of non-aromatic hydrocarbons, benzene, toluene and xylene mixture using Aspen Plus and Matlab software in this work. The traditional two-column sequence separation process and the dividing wall column process had been simulated and optimized by NSGA-II algorithm respectively. Total annual cost (TAC), energy consumption per product flow rate (GEC), the productivity of benzene-toluene and the productivity of xylene were set as objective functions. The results showed that effect of the reflux ratio on TAC was critical. The two separation processes were compared based on the lowest TAC under the premise of satisfying the constraints. The results indicated that the lowest TAC, heat transfer cost and GEC of the dividing wall column process were reduced about 7.7%, 16.1% and 26.3% in comparison with the two-column sequence process, respectively. It implied that the dividing wall column process would be the best sustainable process in xylene production with lower TAC and GEC.

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Analysis of preparation factors of ROP-PLGA microspheres with high encapsulation efficiency based on response surface method

Kang WEN Yi WEI Guanghui MA

Chin. J. Process Eng. 2021, 21 (1): 83-91. DOI: 10.12034/j.issn.1009-606X.220050

Abstract （453）

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As a novel amide local anesthetic, ropivacaine (ROP) is widely used in postoperative pain management. However, ROP has a short half-life (t1/2=1.8 h), and multiple doses in clinical is needed to meet the demand for analgesia, resulting in poor patient compliance. In this study, ROP-PLGA microspheres were prepared by using the premix membrane emulsification technique combined with the double emulsion-solvent evaporation method. Finally, the uniform microspheres with particle size of 7.831 μm and Span value of 0.874 were prepared under 1.5% (w/v) of PVA in external aqueous phase, 1:7.5 of volume ratio of oil phase-external aqueous phase (O/W2), 300 r/min of stirring rate of pre-double emulsion as well as 10 kPa of trans-membrane pressure. Additionally, factors such as the pH of external water phase, PLGA concentration in oil phase and internal water phaseoil phase volume ratios (W1/O) on the effect of encapsulation efficiency (EE) and the drug loading (DL) were investigated based on response surface method (RSM). The optimal formulation and process parameters designed by RSM were as follow: the pH of the external water phase was 11, PLGA concentration in oil phase was 15%(w/v), internal water phaseoil phase volume ratios (W1/O) were 1:10. Moreover, the model predicted the DL of 17.6 μg/mg and the EE of 53.89% were predicted by RSM model. In the meanwhile, repeatability test showed that the DL was (18.0±0.5) μg/mg and the EE was (55.7±2.69)%. Eventually, the relative error was insignificant (less than 7%), which meant the model was reliable. In vitro release profile showed that the cumulative release of ropivacaine loaded microspheres at three and five days was about 50% and 70% respectively, which indicated that the prepared ROP-PLGA microspheres had a stable sustained release effect and microsphere bioformulation had great potential in the field of sustained release of local anesthetics.

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Direct separation of human serum albumin from Cohn fraction V supernatant by one-step ion exchange chromatography

Jie XIANG Songping ZHANG Guifeng ZHANG Jian LUO Rong YU

Chin. J. Process Eng. 2021, 21 (1): 92-99. DOI: 10.12034/j.issn.1009-606X.220073

Abstract （596）

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Fraction V supernatant is an effluent of Cohn fractionation in plasma protein industry. Due to its high ethanol concentration, further recovery of the residual protein has been regarded as non-economical. In this work, a recovery of human serum albumin (HSA) from fraction V supernatant by ion exchange chromatography was reported, which had not been reported in the literature to our knowledge. Firstly, bovine serum albumin (BSA) was used as model protein to compare the adsorption capacity of three different types of chromatographic media in different ethanol-aqueous solutions. The adsorption capacity of the hydrophobic medium to BSA in ethanol-aqueous solution was very weak, and the increase of ethanol concentration led to the adsorption capacity approaching to 0. The cation exchange medium had a high adsorption capacity at low ethanol concentration, but decreased quickly with the increase of the ethanol concentration. In contrast, the anion exchange medium showed the best adsorption performance, and the adsorption capacity in 40% ethanol-aqueous solution still reached 34.66 mg/mL. Further experiments showed that the adsorption of BSA on the anion exchange medium in the presence of ethanol could be described by Langmuir isothermal adsorption equation. The anion exchange medium DEAE Sepharose Fast Flow was packed into a chromatographic column. Real purification of Cohn fraction V supernatant was performed. The Cohn fraction V supernatant, containing about 40% ethanol, was directly loaded to the anion exchange column. A two-step elution strategy was used. The first elution was pH change from 7.0 to 4.5 to obtain the target product human serum albumin, and the second elution was to increase the concentration of sodium chloride from 0 to 1 mol/L to elute glycoproteins. The purity of HSA was 96.35% by electrophoresis, and the activity of binding to the ligand warfarin was comparable to that of commercial HSA product by Cohn fractionation. The total recovery was 43 mg/L Cohn fraction V supernatant.

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Preparation and performance of the 1,2,3-triazolium-based membranes with high ionic conductivity and CO ₂ permeability

Chao FU Xiuyun WANG Liqiang WAN Xinyue HAN Linxiao WANG Jianwei FANG Farong HUANG

Chin. J. Process Eng. 2021, 21 (1): 100-107. DOI: 10.12034/j.issn.1009-606X.220054

Abstract （393）

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The 1,2,3-triazole ring can be transformed into a 1,2,3-triazolium through the alkylation or protonation reaction. The research on the application of this novel poly(ionic liquid)s has only been valued recently even though 1,2,3-triazolium have been found long ago. 1,2,3-triazolium can be used in various fields. Compared with the linear triazolium cross-linked triazolium have rarely been reported. The special cross-linked structure makes the mechanical properties of cross-linked triazolium, better than linear triazolium. A series of novel cross-linked 1,2,3-triazolium-based membranes were prepared via 1,3-dipolar cycloaddition reaction between azides and alkynes along with N-alkylation and anion substitution reaction. Firstly, an alkynyl-terminated polytetramethylene ether glycol (DPPTMEG) was synthesized, and reacting with biphenyl dibenzyl azide (DAMDB) and bisphenol A dipropargyl ether (BADPE) along with alkylation and anion substitution reaction, the new kind of membranes were prepared. The structure of the cross-linked polytriazolium membranes were characterized by nuclear magnetic resonance (NMR). The thermal properties and mechanical properties of the cross-linked polytriazolium membranes were studied by dynamic mechanical thermal analysis (DMA), thermogravimetric analysis (TGA), and electronic universal testing machine. While the ionic conductivity and CO2/N2 permeability of the cross-linked polytriazolium membranes were measured by broadband dielectric spectroscopy (BDS) and isochoric gas permeation system. The results showed that the membranes had excellent ionic conductivity, the direct current conductivity at 30℃ up to 2.94×105 S/cm and CO2 permeability of up to 550.4 barrer. The Td10 of the 1,2,3-triazolium-based membranes with different formulations did not change significantly while the glass transition temperature (Tg) increased with the increase of the proportion of bisphenol A dipropargyl ether. The membranes showed great mechanical properties, the tensile strength would reach to 1.70 MPa and the elongation at break up to 136.8%.

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Combustion characteristics and kinetics during co-combustion of bituminous coal in Linhuan Mining Area, Anhui Province and municipal sludge

Ziwei XIA Liugen ZHENG Chuncai ZHOU Xiangping WEI Xianglin DONG

Chin. J. Process Eng. 2021, 21 (1): 108-115. DOI: 10.12034/j.issn.1009-606X.219375

Abstract （427）

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Coal samples from coal-fired power plants and sludge samples from domestic sewage treatment plant were collected in Linhuan Industrial Park in Huaibei, Anhui Province. The co-combustion experiments of coal and sludge under different mixing ratios were carried out by thermogravimetric analysis (TGA). The kinetics analysis of the mainly weightlessness stage of fuel was studied by five reaction kinetics models, and the combustion characteristics of coal and sludge were revealed. Results showed that the coal sample had one weight loss peak at the temperature of 529℃ while sludge had three ones at the temperature of 140, 293 and 430℃, indicated that the combustion process of sludge was divided into three stages of weightlessness while coal only had one stage of weightlessness. The flammability index and combustion characteristics index of coal were 11.36×10–6 mg/(K–2•min) and 47.1610–10 K–3•min–2. Compared with coal, the flammability index and combustion characteristics index of sludge were lower, 10.74×10–6 mg/(K–2•min) and 13.04×10–10 K–3•min–2, respectively. The combustion characteristics of the reaction was increased by adding sludge to coal, and the mixing ratio was preferably 90 (coal): 10 (sludge). As the heating rate increases, the weight loss of coal and sludge decreases, and the burning weight loss rate increases. The DTG curves of all samples were shifted to the high temperature side, resulting in thermal hysteresis. During the fixed carbon burnout phase, the activation energy of the blended fuel was between the two kinds of raw materials, and decreased with the addition of sludge, which proved that the addition of sludge can effectively improve the reactivity of coal and promote its combustion process.

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Thermodynamic analysis of droplet nucleation causing liquid-phase precipitation in air-hydrocarbon mixture gas

Shuxia YUAN Zhefeng ZHANG Yuguang FAN Xiong ZHANG

Chin. J. Process Eng. 2021, 21 (1): 116-124. DOI: 10.12034/j.issn.1009-606X.220017

Abstract （398）

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Air-hydrocarbon mixture gas is a combustible gas made by mixing the vaporized liquid light hydrocarbon and air with a specific ratio, which is a kind of clean fuel. However, the adopted light hydrocarbons are liquid state at standard condition, causing the high dew point of the mixing gas. In this work, the nucleation thermodynamic theory was used to study the phase transition or nucleation force caused by the changes of temperature and pressure on some zones, and the nucleation energy of droplets. The nucleation mechanism, nucleation energy and their relationships with the subcooled temperature and supersaturation of the air-hydrocarbon mixture gas were obtained from these studies. It was shown that the subcooled temperature and supersaturation required by phase transition or nucleation decreased with the increase of temperature and pressure. Although the subcooled temperature and supersaturation required for complete phase transition would unlikely be reached due to the fluctuation of the working condition, the subcooled temperature and supersaturation required for nucleation can easily take place. Therefore, it is important to control the occurrence from nucleation to complete phase transition for preventing the formation of dew point. The research results provided the reference for the research on the safety of storage and transportation of air-hydrocarbon mixture gas.

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Cover and Contents

The Chinese Journal of Process Engineering 2021, 21 (10): 0-.

Abstract （189）

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A review on the approaches to the production of vanadium metal

Weiliang LU Ying ZHANG Pei SUN Shili ZHENG Shan QIAO Yang ZHANG Ping LI Yi ZHANG

The Chinese Journal of Process Engineering 2021, 21 (10): 1117-1131. DOI: 10.12034/j.issn.1009-606X.220294

Abstract （1414）

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Vanadium metal, known as "industrial monosodium glutamate", is widely used in the fields of metallurgy, chemical engineering, aviation, energy, atomic energy, etc. Vanadium belongs to the rare reactive metals with a high melting point, and its production is difficult and costly. Currently, the main route for the production of high-purity V is the combination of the aluminothermic reduction of vanadium oxide and the vacuum melting purification of the crude V; however, this route is energy-intensive and low-yield. In order to reduce the production cost of metallic vanadium, many approaches to the production of crude vanadium have been proposed based on the thermodynamic stability of vanadium oxides and vanadium chlorides, including calciothermic reduction, magnesiothermic reduction, vacuum carbothermic reduction, silicothermic reduction, carbothermic reduction-nitridation-nitride thermal decomposition, molten salt electrolytic deoxidation, etc. The developed refining approaches includes molten salt electrolytic refining, iodide thermal decomposition, solid-state electro-transport purification, etc. This paper reviews the above methods comprehensively in terms of principles, technical features, effectiveness, and drawbacks. It is expected that this review will provide important guidance for the development and upgrading of the approaches for the production of high-purity V metal. It is believed that the application of vanadium will continue to expand with the achievement of high-end materials, which no doubt promotes the development of high-purity metallic vanadium production industry.

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Progress in numerical simulation of liquid-liquid cyclone separator

Yanni CHI Xianghai MENG Rui ZHANG Haiyan LIU Zhichang LIU

The Chinese Journal of Process Engineering 2021, 21 (10): 1132-1141. DOI: 10.12034/j.issn.1009-606X.220262

Abstract （338）

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The cyclone separator is a liquid-liquid separation device that has been developed very rapidly in recent years. The main advantages of cyclone separators are high efficiency, energy saving, economic space occupation, and low cost. It is widely used in such industries as mineral processing and metallurgy, sewage treatment, food, paper making, and petroleum chemistry. Therefore, it is particularly important to study the relevant characteristics of the cyclone separator. Besides, numerical simulation is an important method for the development and research of liquid-liquid cyclone separators. This work systematically introduced the research progress of the numerical simulation of liquid-liquid cyclone separators, where the effects of the selection of cyclone separator model, the variation of geometric structure (including the inlet, the cone section, the overflow pipe, the guide vane and the cylindrical section) and operating parameters (including the split ratio, the total flow and the feed ratio) on the separation efficiency as well as the flow field were analyzed, and the final evaluation indices (including the separation efficiency and the pressure drop) were also proposed. Besides, some opinions on the change of geometrical structure and operating parameters influencing the separation efficiency and the pressure drop were provided, and the numerical simulation of the vortex and the droplet breaking and coalescing, as well as the development of new separation efficiency evaluation formulas were prospected. New ideas for the following up research workers of the cyclone separator were provided.

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Theory of chemical reaction engineering on catalytic decomposition of propellant in packed bed for monopropellant thruster

Baolin HOU Xue LI Wentao WANG Ting LU Weimin CONG Haolong WANG Deyang GAO Chuande HUANG Jihong SHAN Liangen XIA Xiaodong WANG Tao ZHANG

The Chinese Journal of Process Engineering 2021, 21 (10): 1142-1155. DOI: 10.12034/j.issn.1009-606X.220304

Abstract （378）

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In 1960s, after the hydrazine based chemical monopropellant was developed, the liquid monopropellant technology has been widely applied in controlling the trajectory of satellite, adjusting the attitude of rocket and the emergency power supply. It is critical for chemical monopropellant to catalytically decompose the high energy liquid chemical propellant in the packed bed of particles. However, up to now, the kind of propellant technology had still been developed by performing a great deal of experiments under the direction of theoretical basement of thermal energy and air dynamics engineering and without considering from the viewpoint of chemical reaction engineering. In this work, from the viewpoint of chemical reaction engineering, the chemical engineering thermodynamics, the catalytic reaction kinetics, the diffusion-reaction in a single catalyst particle, the flow-reaction in the pore of porous catalyst, the flow-transport phenomena-reaction in the macroscopic porous media of packed bed and the meso-scale complicated geometry structure formed by the catalyst particles randomly stacking to be used in designing the component of propellant, optimizing the catalyst structure and the decomposition packed bed of monopropellant thruster were discussed. The review provides the fundamental theory of catalytic reaction engineering for designing, which is hoped as the theoretical direction for designing the propellant component, synthesizing the catalyst structure and the decomposition packed bed in developing the new green chemical monopropellant technology.

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Research progress in preparation of large pore pseudoboehmite and γ-Al2O3 carrier

Yongjia YANG Xinsheng ZHANG Jin LI Chunguang ZHANG Yuansheng ZHAO Shili ZHENG Ping LI

The Chinese Journal of Process Engineering 2021, 21 (10): 1156-1166. DOI: 10.12034/j.issn.1009-606X.220368

Abstract （461）

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γ?Al2O3 is widely used as catalyst carrier in petroleum processing realm, owing to its porosity, high dispersibility, adjustable surface acid/base characteristics, attractive mechanical properties and good thermal stability. As the quality of crude oil is increasingly heavy and inferior, more and more attention has been paid on the preparation of macro-mesostructured γ?Al2O3 since the γ?Al2O3 as the catalysts carrier, that used in the heavy oil processing, such as fixed-bed residue hydrotreating or RFCC, need more meso-and macroporous structures to reduce the internal diffusion resistance of large molecules and improve the catalytic activity. Commonly, pseudoboehmite as the raw materials turns decisive significance for the physiochemical properties of γ?Al2O3. For instance, the pore properties of γ?Al2O3 are greatly in?uenced by the size and morphology of pseudoboehmite crystallites and their aggregation. This manuscript thus reviewed the representative preparation methods of pseudoboehmite including precipitation method and aluminium alkoxide hydrolysis method. The advances of Al2(SO4)3?NaAlO2 method and carbonization method, as two main industrial technologies, were emphatically introduced. New reactors and technologies for the precipitation were developed in order to provide su?cient mixing intensity and recirculation of different reactants, which could bring about a homogeneous supersaturation distribution in the instantaneous neutralization reaction, and then lead to uniform crystallites size, thereby pseudoboehmite with large pore volume and narrow pore size distribution. Besides, the relative meso??and macroporous structures control technologies were also highlighted, such as pH swing method, pore-enlarging additives method, and hydrothermal treatment method, etc. The advantages and disadvantages of these methods were also briefly analyzed. At last, the development trend was introduced and some suggestions were proposed.

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Simulation of gas-liquid two-phase flow and atomization characteristics of Y-type nozzle for heavy oil burner

Zhiqi WANG Liuming CHEN Bingying XIAO Baoqi XIE

The Chinese Journal of Process Engineering 2021, 21 (10): 1167-1176. DOI: 10.12034/j.issn.1009-606X.220336

Abstract （334）

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Heavy oil burner is the key component of asphalt mixing equipment. However, heavy oil is not easy to atomize due to its high viscosity and surface tension, which results in low combustion efficiency and high pollutant discharge in heavy oil burners. Y-type atomizing nozzle is widely used in heavy oil atomization because of its simple structure and wide adjustment range. A large number of experiments and simulations were carried out on the atomization characteristics of heavy oil. However, the existing research only analyzed the atomization characteristics from the aspects of structure or atomization parameters, ignoring the gas-liquid two-phase flow characteristics in the nozzle. Therefore, the research on the gas-liquid two-phase flow and atomization characteristics of Y-type atomizing nozzle has an important guiding role in the design of heavy oil burner. In order to improve the quality of heavy oil atomization, computational fluid dynamics software were used to explore the influence of nozzle structure parameters (mixing chamber length, inlet diameter ratio, angle between air and fuel inlet) and atomization parameters (mass flow rate of oil, air inlet pressure, temperature of oil) on the gas-liquid two-phase flow and heavy oil atomization characteristics of Y-type nozzle. The results showed that the structure parameters and atomization parameters directly affected the oil film thickness and gas-liquid two-phase velocity difference in the nozzle. Under different parameters, the change rule of gas-liquid rate and droplet Sauter mean diameter was opposite. Considering the two atomization performance indexes, the optimal length of mixing chamber was 15~20 mm, the reasonable range of inlet angle was 60°~75° and the optimal inlet diameter ratio was 1.0~1.1. In order to ensure the better atomization effect of heavy oil, the air inlet pressure should be greater than 0.5 MPa, the above parameters obtained by simulation provide guidance for the structure optimization design and operation parameter setting of Y-type nozzle.

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Influence of inlet dust concentration on characteristics of a new cyclone particle bed coupling separator

Jinzhuang FU Ming CHANG Yiping FAN Chunxi LU

The Chinese Journal of Process Engineering 2021, 21 (10): 1177-1186. DOI: 10.12034/j.issn.1009-606X.220339

Abstract （290）

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Nowadays, the production and combustion of fossil fuels make the emission of particulate pollutants increasing day by day. Researchers are actively developing new high efficiency dust removal separator to reduce the emission of pollutants. The studies on the separation technology of single cyclone separator and single particle bed filter are extensive but on the coupling separator of cyclone separator and particle bed are scarce. Therefore, the study of the cyclone particle bed coupling separator has broad application prospect. In order to investigate the influences of the inlet dust concentration on the pressure drop and the dust removal efficiency of a new cyclone-granular bed coupling separator, a large scale cold model experiment was carried out. The results showed that with an increase of the inlet dust concentration, the pressure drop of the separator tenders large and the speed of pressure drop increased rapidly when reaching an equilibrium state. The reason is that the inlet dust concentration increases, the dust in the built-in particle bed increases, the bed porosity decreases and the pressure drop increases. With the decrease of the inlet dust concentration, the separation efficiency of the separator increased. The dust content in the particle bed of the separator was also related to the regeneration efficiency. As the concentration of the regeneration dust source decreased, the time duration of the pressure drop reaching equilibrium became short. Furthermore, based on the experimental data, the empirical formula of separator pressure drop and regeneration dust source concentration was given. When the concentration of regeneration dust source reduced from 58.18% to 23.67%, the pressure drop reduced from 1.5 kPa to 1.2 kPa. With the decrease of the concentration of the regeneration dust source, the dust removal efficiency of the separator decreased slightly. The influence of inlet dust concentration and the regeneration dust source concentration on the pressure drop of separator coincided with each other, while the effect on the separator efficiency was different.

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Dilution of Isa copper smelting slag by carbothermic reduction with waste cathode carbon

Guodong WU Lei LI Kongzhai LI Yong YU

The Chinese Journal of Process Engineering 2021, 21 (10): 1187-1195. DOI: 10.12034/j.issn.1009-606X.220327

Abstract （248）

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Massive waste cathode carbon block are produced from the electrolytic aluminum process each year, which is mainly composed of carbon, sodium fluoride and other compounds. The fluoride and cyanide components in it cause serious environment pollution if it accumulated and exposed to air for a long time. It is regarded as a hazardous waste by various environmental bodies. An innovative method for resource processing of this waste cathode carbon block was proposed in this work. Using this waste cathode carbon block as the reducing agent can realize the effective dilution and recovery of copper from the smelting slag of Isa copper through a reduction process. According to thermodynamic analysis, the influence of the amount of waste cathode carbon addition, reduction temperature, holding time and CaO addition on the recovery ratio of copper dilution in Isa copper smelting slag was studied. The results showed that the recovery ratio of copper dilution can reach 98.24% under the conditions of waste cathode carbon addition amount of 2.0%, reduction temperature of 1300℃ and holding time of 60 min. At the same time, the F in the waste cathode carbon can be transferred and fixed in the diluted tailings in the form of CaF2. The toxic leaching concentrations of F? and CN? in the tailings were far lower than the national permissible emission standard. The research has realized the high-efficiency recovery of copper from Isa copper smelting slag and the resource utilization of waste cathode carbon.

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Structure design and optimization of thin plate static mixer for dilution water mixing

Jianqiu LU Jiaqing CHEN Wenjin LIU Quan LUO Guodong DING Xiaoping WANG

The Chinese Journal of Process Engineering 2021, 21 (10): 1196-1206. DOI: 10.12034/j.issn.1009-606X.220322

Abstract （337）

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The dilution water blending is a key link in the crude oil electrical desalination system of oil fields or refineries, which directly affects the efficiency and operating energy consumption of electrical desalination. In order to further simplify the equipment structure, reduce costs and increase system efficiency, a thin plate static mixer for dilution water mixing was proposed. On the basis of the preliminary structural design of the thin plate static mixer, computational fluid dynamics (CFD) was used to perform three-dimensional numerical simulation of oil-water mixing, the square root of segregation strength (IOS0.5) in a uniform mixing state and pipeline pressure drop (Δp) were used as evaluation parameter, which can indicate the influence of structural parameters on the uniformity of oil-water mixing and the running energy. The structural parameters were the length of water injection pipe, the distance between water injection pipe and thin plate, thin plate guide position and the thickness of bending sheet. Subsequently, with the inner diameter D of the hybrid pipeline as a reference, the key structural parameters were optimized by the response surface method (RSM), and the mixing performance under the optimal combination of structural parameters was predicted. The optimal combination of structural parameters obtained by optimization was as follow: the length of the injection pipe was 1/3D, the distance between the center of the injection pipe and the orifice was 4/25D, the guiding position of the orifice was 1/8π, and the thickness of the orifice was 1/25D. By comparing and analyzing the mixing effect of the thin plate static mixer before and after optimization, it was found that the optimized structure of IOS0.5 was 43.06%, which was lower than before optimization. Qualitative analysis of the water phase velocity cloud diagram and streamline diagram in the thin plate mixer showed that when the water injection ratio was 2%, the oil and water two phases can reach a uniform mixing state at the 3D downstream of the water injection pipe. It can be seen that the thin plate static mixer can quickly achieve uniform mixing of oil and water at a small water injection ratio.

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Processing and characterization of Fe-(9~11)Cr-Y ₂ O ₃ as ITER structural material

Zhenzhen WANG Yi′na HUANG Yucheng WU Laima LUO

The Chinese Journal of Process Engineering 2021, 21 (10): 1207-1215. DOI: 10.12034/j.issn.1009-606X.220271

Abstract （311）

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Oxide dispersion strengthened (ODS) steel has excellent radiation properties and is considered a candidate for the first wall structure of fusion reactors. Adding Y element to the material can improve thermal stability, and Cr element can improve corrosion resistance, because the high oxide density inside will cause needle-like dislocations, the material has higher strength and lower toughness to brittle transition temperature. The nano-precipitation phase can trap helium and make it in the form of nano-scale helium bubbles, avoiding the production of large helium bubbles to reduce possibility of expansion. Reducing helium embrittlement can make the material have a longer service life in the fusion reactor. In this work, based on mechanical alloying (MA) and spark plasma sintering (SPS), binary alloys with Fe(9~11)Cr content and ODS alloys were prepared successfully. The morphology and phase analysis of MA powders were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), micro Vickers-hardness tester and energy dispersive spectrum (EDS), and the precipitation phase of the alloy sample was observed by transmission electron microscope (TEM). The results showed that the fine grain size enabled the material to have good tensile and creep properties at high temperatures. The MA powder was continuously refined after being crushed and deformed under a rotational speed of 300 r/min and the ball-to-powder mass ratio was 10:1. The MA powder reached the cold welding-crushing balance at 40 h. The powder grain size decreased to about 16.1 nm and tended to be stable with the increase of ball grinding time. After spark plasma sintering and solidification of the MA powder for 40 h, the grain size did not increase significantly, and the trace elements were uniformly distributed in the matrix. The Vickers-hardness of binary alloy samples increased with the addition of Cr content. The grain boundaries of ODS alloy samples proved to be fine and uniform after being eroded by corrosive liquid.

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Effect of pressurized carbonization system on the particle size and dispersion of nano calcium carbonate

Xixi LIU Xiaopeng CHEN Chenmin LIU Liubin SHI Dankui LIAO Cui LIU Zhangfa TONG

The Chinese Journal of Process Engineering 2021, 21 (10): 1216-1224. DOI: 10.12034/j.issn.1009-606X.220278

Abstract （338）

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Nano calcium carbonate with uniform particle size and high dispersion was prepared by pressurized carbonization system. The effects of calcium hydroxide concentration, surfactant addition amount, reaction temperature and CO2 pressure on the size and dispersion degree of prepared nano CaCO3 particles were investigated. X-ray diffraction (XRD), scanning electron microscope (SEM), Zeta potential and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the prepared nano CaCO3 particles. The results showed that the optimum conditions for pressure carbonization are Ca(OH)2 mass concentration of 2%, surfactant dosage of 3% (percentage of theoretical production of calcium carbonate), reaction temperature of 40℃ and CO2 pressure of 6 MPa, the average particle size of the cubed calcium carbonate was 117 nm, and the crystal type was calcite calcium carbonate. The addition of surfactant cetyl trimethyl ammonium bromide (CTAB) to the carbonization reaction increased the positive charge formed on the surface of CaCO3 to +37.7 mV and higher than the standard value of 30 mV, indicating that the prepared CaCO3 product has good dispersibility and stability. FT-IR and Zeta potential were used to characterize CaCO3 nanoparticles before and after the modification of CTAB, and the influence mechanism of CTAB on the dispersion of synthetic CaCO3 nanoparticles was discussed, providing a new method for the preparation of nano CaCO3 .

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Benchmarking analysis on energy efficiency performance of temperature swing adsorption carbon capture system

Lijin CHEN Shuai DENG Junyao WANG Ruikai ZHAO Li ZHAO Shuangjun LI Zhihao GUO

The Chinese Journal of Process Engineering 2021, 21 (10): 1225-1235. DOI: 10.12034/j.issn.1009-606X.220264

Abstract （321）

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An accurate and reasonable energy efficiency analysis is significant to the scale-up development of carbon capture technology. It is not only a preliminary preparation to the final energy-saving proposal of carbon capture technology, but also an important data basis to sustainable performance evaluation of carbon capture process with aims on green, clean and low-carbon. Therefore, in addition to exploring the mechanism on energy conversion of carbon capture process, it is urgent to establish a benchmarking analysis methodology of energy efficiency performance which features on easy-to-operate for the demand of engineering sector, so that the performance cognition of typical capture technologies could be accumulated and compared on a reasonable and unified evaluation platform. Based on the benchmarking analysis method, the methodology of energy efficiency performance on temperature swing adsorption (TSA) is presented, including processes, parameters, model, etc. The effect of adsorption temperature and desorption temperature on the energy efficiency performance of TSA was analyzed, the feasibility of proposed method is demonstrated and quantified, and the influence of boundary changes on the evaluation results was discussed as well. The proposed method could provide a generalized guidance to the benchmarking evaluation of energy efficiency performance of carbon capture with specific case.

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Analysis and optimization of air cooling performance of battery pack based on air volume regulated by filter plate

Guangxin CHU Mengtao YU

The Chinese Journal of Process Engineering 2021, 21 (10): 1236-1244. DOI: 10.12034/j.issn.1009-606X.220283

Abstract （241）

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With the global trend of advocating environmental protection, energy conservation and emission reduction, and low-carbon travel, electric vehicles have been vigorously developed. As the power source of electric vehicle, power battery pack is one of the core components of electric vehicle. At present, the mainstream battery used in electric vehicles at home and abroad is lithium-ion battery, which has the advantages of high power density and energy density, low cost, long service life and no memory effect. But its performance is greatly affected by temperature. Therefore, it is imperative to carry out thermal management of electric vehicles. Firstly, the capacity, resistance and temperature rise of 18650 lithium-ion battery were tested by building a test platform; then, the consistency between the simulation results of single temperature rise and the experimental results was compared; finally, the power lithium-ion battery pack model was established, through single factor analysis and orthogonal experiment, the effects of filter plate free area ratio, battery spacing, wind speed and battery bottom distance on the battery were studied. The influence of maximum temperature and temperature difference were studied. When the battery was discharged at 1 C, it was concluded that adding filter plate improves the consistency of temperature field of battery pack, and the temperature difference of battery pack was the minimum when the free area ratio of filter plate was 0.1, 0.9 and 0.9. With the increase of wind speed, the maximum temperature decreased,temperature difference of battery pack first increased and then decreased. With the increase of battery spacing, the maximum temperature of battery pack first increased and then decreased, the temperature difference first increased, then decreased and increased at last.With the increase of the distance from the bottom of the battery, the maximum temperature of the battery pack first decreased and then increased. Finally, the best combination of 6 m/s, 4 mm and 4 mm was obtained by orthogonal experiment, which decreased 22.5% and 74.8% respectively compared with the maximum temperature and temperature duffurence before optimization.

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Cover and Contents

The Chinese Journal of Process Engineering 2021, 21 (11): 0-.

Abstract （249）

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Peptide-drug conjugates improve the efficacy and safety of anticancer medicines

Xue LIU Jing ZHANG Bo LIANG Yao ZHANG Weiying WANG Chun ZHANG Yongdong LIU

The Chinese Journal of Process Engineering 2021, 21 (11): 1245-1258. DOI: 10.12034/j.issn.1009-606X.220303

Abstract （539）

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Cancer has become the biggest threat to human health in the world. Small-molecule chemotherapeutic drugs are widely used in clinical practice in cancer treatment, but systemic toxicity and drug resistance are common due to the lack of tumor targeting. One of the main challenges for the chemotherapeutic drug is how to directly transport sufficient drugs to tumor but not normal tissues. To solve this problem, antibody-drug conjugate (ADC) was proposed and has been the hot spot in tumor drug research for decades. Guided by the specific monoclonal antibodies, ADC can selectively deliver highly cytotoxic drugs to tumor sites therefore overcome the above shortcomings of small molecules. However, the molecule weight of antibodies is generally large that makes ADC low permeability in the tumor and seriously limits its therapeutic effect. In recent years, peptide-drug conjugate (PDC), using peptides with tumor targeting ability to replace antibodies, is emerging as another novel targeted delivery route of tumor drugs. A great number of tumor targeting penetration peptides have been investigated in PDC design and shown great potential in cancer treatment. Peptides could be easily prepared through chemical synthesis or expressed by prokaryotic systems. Therefore, compared with ADC, PDC has the advantages of higher drug loading, enhanced penetration capacity in solid tumors, easier multifunctional modification through chemical or genetic techniques, and lower production cost. With the deep study of intracellular transport pathway and drug release mechanism, PDC will be expected to be put into clinical application as soon as possible. In this review, the latest advances of PDC are summarized. Types and characteristics of different targeting peptides, cytotoxic molecules and linkers in PDC and their applications in cancer treatment are discussed. The advantages and disadvantages of current researches on PDC are reviewed, and future development prospected.

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Progress in boron recovery from salt lake brines by solvent extraction

Zhenya XU Hui SU Jian ZHANG Wensen LIU Zhaowu ZHU Jinggang WANG

The Chinese Journal of Process Engineering 2021, 21 (11): 1259-1268. DOI: 10.12034/j.issn.1009-606X.220366

Abstract （451）

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In this work, four types of solvent systems for boron recovery from salt lake brines including aliphatic alcohol (monohydric alcohol, diol, mixed alcohol), aromatic polyhydroxy compound, amine compound containing hydroxyl group and ionic liquid were systematically reviewed, focusing on the recent research and application progress. The extraction mechanism of boron by various extractant systems were highly summarized to clearly explain the effect of extractant structures on the extraction performance. The extraction performance of different extractants and the influence of coexisting ions on the extraction process were analyzed, and the future research and development direction of boron extraction from salt lake brines were discussed. The monohydric alcohol was suitable for extracting boric acid under the conditions of high salting-out and acidity. But it also had serious disadvantages including low extraction rate, and severe equipment corrosion. Diol had higher extraction efficiency than monohydric alcohol, but it was difficult to realize large-scale industrial production due to high viscosity, high solution loss and difficult stripping from the loaded organic phase. Therefore, the recycling performance of diol extractant was relatively poor. The mixed alcohol system was suitable for industrial application of boron extraction from acid salt lake brines because of its synergistic extraction effect and low cost, and can also reduce viscosity and solution loss. Other systems, such as hydroxyl-containing aromatic and amine compounds, had good extraction effects on boron from alkaline salt lake brines, but they were generally expensive and difficult for industrial application. Ionic liquid can be used for boron extraction and diluent because of its advantages such as low volatility, good chemical stability and designable structure, which had a certain application prospect.

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Comparative study of fluid residence time distribution and flow pattern in baffle equipment

Zhangfan GAO Muyi FAN Shaobei LIU Xiong ZOU Weixing HUANG

The Chinese Journal of Process Engineering 2021, 21 (11): 1269-1276. DOI: 10.12034/j.issn.1009-606X.220363

Abstract （386）

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The flow pattern in the equipment can be the main performance index for its internal structure. Innovation of process equipment is to optimize its internal structure for desired flow pattern. Numerical simulation, as a primary research approach of fluid flow pattern, is not easy and economical to perform in large-scale or complex equipment, but the residence time distribution (RTD) experiment has the advantages of simplicity and convenience. In order to estimate the flow pattern with RTD experiments, taking the typical baffle structure as an example, several groups of structures were designed to compare and analyze the residence time distribution and the flow patterns corresponding to the structures, which can provide clues for short circuits judgement and determination of reasonable structures. The results showed that the short circuit and dead zone in the equipment were relativistic. The peak time and tailing of the RTD density function curve can be used to judge the short circuit and dead zone in the equipment. This conclusion can provide a theoretical basis for equipment design. The number of tanks in the multi-tank series model and the peak time and variance of the RTD curve were used to analyze the influence of flow rate, baffle gap area and plate spacing on the fluid flow pattern in the equipment. With the study of the pressure drop and the comprehensive consideration of the energy consumption and performance of the equipment, the most suitable tanks number, peak time and variance were put forward based on RTD experiments to determine the reasonable structure of the equipment, which provided a reference for the structural design of industrial baffle equipment.

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Numerical study on performances of a super vortex quick separation system at riser outlet under oil steam conditions

Zhiliang ZHANG Haijun CHEN Tao CHEN Pei MOU Anjun LI Wenjun LI

The Chinese Journal of Process Engineering 2021, 21 (11): 1277-1286. DOI: 10.12034/j.issn.1009-606X.220408

Abstract （306）

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In recent years, there are many reports on super vortex quick separation (SVQS) system using air instead of oil steam, but the performance parameters such as separation efficiency are not very accurate, moreover the influence of oil steam properties on the performance of the system has not been studied. In order to promote the industrial application of SVQS system and accurately evaluate its performance, the flow fields at a series of oil steam model with different densities and viscosities in a ?600 mm×4150 mm SVQS system were simulated by the commercial software FLUENT 2019 R3. The influences of oil steam properties on the dimensionless tangential velocity and pressure drop were studied respectively by single factor analysis. The distribution law of residence time of different oil steam in SVQS were analyzed by employing the scalar transport equation. The simulation result showed that the dimensionless tangential velocity of oil steam in SVQS increased as the density increasing or decreasing of viscosity and the maximum dimensionless tangential velocity can reach 0.912. Both density and viscosity had logarithmic function relations with the dimensionless maximum tangential velocity. The residence time of oil steam in SVQS reduced with the increasing of density of oil steam or the decrease of viscosity that the minimum average residence time was 6.279 s. It was found that the pressure drop and drag coefficient were not only affected by the structural parameters of the SVQS system, but also impacted by the viscosity of oil steam. Both pressure drop and drag coefficient had a logarithmic function relationship with the viscosity of oil steam. Meanwhile, the formulas of dimensionless tangential velocity, pressure drop and resistance coefficient related to oil steam parameters were obtained by fitting, which had good universality and can provide data for the structural optimization of SVQS system.

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Analysis of characteristics of liquid falling film flow on corrugated sheet packing

Junhua LIAO Peng XUE Mengjing ZHAO Junjie LIU Ling JIN

The Chinese Journal of Process Engineering 2021, 21 (11): 1287-1296. DOI: 10.12034/j.issn.1009-606X.220422

Abstract （308）

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The falling film flow characteristics of the liquid in corrugated sheet packing are the key factors affecting its mass transfer performance. In this work, a falling film flow experimental bench was built and combined with computational fluid dynamics to study the falling film flow of the corrugated sheet, the influence of spray density and corrugation tilt angle on flow characteristics was analyzed, and quantitative information of average liquid film thickness and the effective wetting area was obtained through three-dimensional simulation. The results showed that the three-dimensional CFD model can accurately predict the liquid falling film flow behavior and calculate the characteristic parameters. The flow of liquid on the corrugated sheet was not homogeneous but was classified as two kinds of forms: groove flow and rivulet flow. As the spray density was low, the liquid flow formed a groove flow in the trough while it changed as rivulet flow along the adjacent ripples when the spray density reached 400 m3/(m2?h), compared with channel flow, the rivulet form was more beneficial to increase the contact area of gas and liquid. However, no matter which flowed mode, the overall wettability of the corrugated sheet was poor, and the thickness distribution of the liquid film was not uniform, which was not conducive to mass transfer. The tilt angle of the corrugation had a greater influence on the flow characteristics of the falling film, after extensive research on the tilt angle, it was found that when the tilt angle was 90°, it was more conducive to increasing the effective wetting area and reducing the average liquid film thickness. The results of this study have theoretical guiding significance for controlling the liquid film thickness and increasing the effective wetting area during the falling film flow, and also have application value for improving the corrugated sheet structure and increasing the mass transfer efficiency.

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Extraction of vanadium and zinc by sulfuric acid leaching from descloizite

Kelun ZHANG Bo LI Yonggang WEI Hongao XU

The Chinese Journal of Process Engineering 2021, 21 (11): 1297-1303. DOI: 10.12034/j.issn.1009-606X.220376

Abstract （389）

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Vanadium lead zinc ore contains a variety of valuable metals with high V grade and high economic value. In this work, vanadium and zinc were extracted from the mine by sulfuric acid leaching method, and the thermodynamics of the leaching process was analyzed. The effects of sulfuric acid concentration, liquid-solid ratio, leaching time, stirring rate and leaching temperature on the leaching rate of vanadium, lead and zinc were studied through conditional experiments. The results showed that the hydrolysis of V in the leaching solution and hydrolysis products containing V remained in the leaching residue at high pH and higher temperatures, which affected the leaching rate of V. The optimum leaching conditions were as follows: sulfuric acid concentration 200 g/L, liquid-solid ratio 3:1, leaching time 30 min, stirring rate 200 r/min and leaching temperature 30℃. Under the optimum conditions, the V leaching rate was 97.90%, the Zn leaching rate was 97.11%, the Fe leaching rate was less than 1%, and the Pb leaching rate was less than 0.01%. The results of kinetic analysis showed that the reaction rate of leaching process was controlled by diffusion process. In the acid leaching process, V and Zn entered the leaching solution, and Pb and Fe remained in the leaching residue. The resulting leaching solution can be separated by ion exchange or extraction. The leaching residue contained 0.41wt% vanadium, 0.61wt% zinc, 15.50wt% iron and 47.70wt% lead. The main components were PbSO ₄ and FeO(OH), which can be returned to the pyrometallurgical lead smelting system.

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The simultaneous recovery of lead and tin in zinc oxide dust by carbothermic reduction

Foguang LEI Minting LI Chang WEI Zhigan DENG Xingbin LI Gang FAN

The Chinese Journal of Process Engineering 2021, 21 (11): 1304-1314. DOI: 10.12034/j.issn.1009-606X.220399

Abstract （262）

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A carbothermic reduction peocess was used to achieve the simultaneous separation and recovery of lead, tin and zinc in zinc oxide dust. The effects of pretreatment to remove fluorine, chlorine and sulfur (Na2CO3-alkali washing and calcination) and adding additives (CaO and bentonite) on the volatilization rate of lead and tin in carbothermic reduction process were investigated. The results show that the volatilization rate of lead and tin were 78.58% and 95.97% respectively when the dust was not pretreated and the conditions were the temperature of 1300℃, the reductant dosage of 14.04% and the holding time of 120min. Under the same conditions, alkali washing and calcination could reduce the volatilization rate of lead and tin. After alkali washing, the volatilization rate of lead and tin reduced to 12.97% and 16.99% respectively. After calcination, the volatilization rate of lead and tin reduced to 30.46% and 57.83% respectively. Increasing the dosage of CaO is beneficial to reduce the volatilization rate of lead and tin. When the dosage of CaO was 5%, the volatilization rate of lead and tin drops to 32.16% and 57.7% respectively. Increasing the dosage of bentonite promotes the volatilization of lead, but has no obvious effect on volatilization of tin. When the dosage of bentonite was 5%, the volatilization rate of lead and tin drops to 37.44% and 83.25% respectively. Using this process, lead-tin alloy (Pb＞70%，Sn＞5%) and crude zinc (Zn＞63%，Pb＞9%) are finally obtained at the same time.

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Comparative study on typical vertical flame spread characteristics of EPS insulation material under concave structure

Xinjie HUANG Jinda GAO Zhijie ZHOU Xiaofeng ZHANG Junjie HU

The Chinese Journal of Process Engineering 2021, 21 (11): 1315-1322. DOI: 10.12034/j.issn.1009-606X.220315

Abstract （247）

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The vertical upward and downward flame spread characteristics of insulation material EPS in the concave structure were studied by building a small-scale flame spread experimental platform. The changes of parameters such as flame structure characteristics, flame spread speed, mass loss rate, flame temperature were comparatively analyzed. The research results showed that in the process of vertical upward spreading, EPS appeared stagnant combustion; this was mainly caused by the large gas flow generated by the chimney effect. However, in the process of vertical downward spreading, the flame spread speed was obviously accelerated due to the increase of EPS accumulated in the process of flame spread and the effect of the reverse stack effect. During the upward spreading process, the length of the pyrolysis zone was significantly longer than the pyrolysis zone spreading downwards. At the same time, the flame was basically inclined to both sides of the concave groove, and the molten dripping of the material can be clearly seen, but it was spreading downwards almost no molten spilled liquid. The mass loss rate in the process of flame spread was affected by the flame height to a great extent, which was mainly manifested in two stages: initial oscillation stage and stable oscillation stage. The influence of the stack effect on it was transient and temporary. In the unburned area, the flame temperature experienced two temperature peaks, and the first peak was larger than the second peak in the case of upward spread; while the first peak was smaller than the second peak for downward propagation. This was mainly due to the structure of the flame and the directional characteristics of the chimney effect, resulting in the generation of two different peak sizes. The research results of this work can provide early theoretical and reference value for the study of flame spread characteristics under actual concave structures.

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Effect of coordination of acoustic wave and chemical agglomeration on fine dust agglomeration in converter

Yuqing ZHANG Yimin YIN Haiying LI Qiudong HU

The Chinese Journal of Process Engineering 2021, 21 (11): 1323-1329. DOI: 10.12034/j.issn.1009-606X.220343

Abstract （302）

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At present, air pollution caused by heavy industrial products such as iron and steel, thermal power generation and cement is still very serious in China. The main reason is the low dust removal effect of PM2.5 and PM10 particles. To solve the problem of difficult treatment of fine dust in converter flue gas, the collaborative treatment method based on acoustic waves and chemical agglomeration was used to pretreat converter flue gas dust in an evaporative cooler to improve the dust removal efficiency of fine dust. Single-factor experiment and orthogonal experiment were used to study the agglomeration effect of fine dust under different factors, such as the type of flocculants [acrylamide (PAM), sodium carboxymethyl cellulose (CMC) and xanthan gum (XTG)], flocculant concentration, acoustic frequency and acoustic field time. The results of the single-factor experiment showed that the agglomeration effect of the three flocculants was PAM>CMC>XTG from large to small, taking the increase of the peak particle size of the fine dust as the evaluation standard. The agglomerating effect was the best when the concentration of agglomerating agent was 0.1 g/L, the effect was obvious when the acoustic frequency was 33 kHz, and the effect was the best when the acoustic residence time was 15 s. The synergistic effect of the acoustic wave and chemical agglomeration was better than that of chemical agglomeration and acoustic wave alone. The results of the orthogonal experiment showed that when the concentration was 0.1 g/L, the acoustic frequency was 33 kHz, and the acoustic residence time was 15 s, the agglomeration effect was the most significant. The peak particle size increased from 3.311 μm to 43.59 μm, and the dust removal efficiency of the corresponding electrostatic precipitator reached 97%. From the experimental comparison of the coordination mechanism and the single agglomeration mechanism, the synergetic mechanism combined the advantages of a single agglomeration mechanism such as chemistry and acoustic waves, and provided a feasible basis for multi-mechanism dust removal in the industry. The results can provide reliable basic data for improving the removal of fine dust in the flue gas of iron and steel production, and lay a foundation for improving the removal efficiency of fine dust in the industrial flue gas.

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Study on wettability difference of profiled fiber based on optical measurement

Feng CHEN Yuchen HU Jinjie LU Xiaolin WU Zhongli JI

The Chinese Journal of Process Engineering 2021, 21 (11): 1330-1337. DOI: 10.12034/j.issn.1009-606X.221226

Abstract （279）

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Gas-liquid coalescence filtration is widely used in process industry. The wettability of fiber material is the key factor affecting the filtration performance of coalescing element. Based on the optical measurement method, the wettability difference of liquid on the surface of single triangular, trilobal and cruciform fiber was studied. The change process of liquid contact angle and volume was analyzed, and the influence of liquid type, fiber inclination angle and profiled degree on wettability was investigated. The results showed that with the decrease of liquid surface tension, the contact angle reduced and therefore the wettability enhanced. However, the volatility of liquid was easy to cause the actual contact angle to be greater than the theoretical one. The contact angle of triethylene glycol, dioctyl sebacate and silicone oil did not change with time. The contact angle of water and ethanol gradually decreased with time, and the decreasing rate of ethanol was greater due to the higher evaporation rate. The contact angle of liquid presented a "V" shape distribution with the inclination angle of the profiled fiber, that was, there was a minimum point (inclination angle of 30°) to make the fiber wettability reach the best. When the profiled degree of the fiber increased, the contact angle difference between different liquid decreased and the overall wettability improved, which indicated that the fiber with higher profiled degree should be selected as the material of prefilter layer or drainage layer.

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Preparation and electrochemical performance investigation of molybdenum dioxide nanorods

Zengli GAO Shouzhi YI Haiyan TANG Hongbin XU

The Chinese Journal of Process Engineering 2021, 21 (11): 1338-1345. DOI: 10.12034/j.issn.1009-606X.220355

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With high conductivity, high melting point and large specific capacity, molybdenum dioxide (MoO2) nanorods have a wide application prospect in the field of electrode materials for supercapacitors. Although there are many methods to prepare MoO2 nanorods, most of them have disadvantages of a complicated process, low yield, high production cost and easy to introduce impurities. Moreover, the prepared MoO2 products have the characteristics of non-uniform morphology, poor dispersibility and inferior electrochemical performances. In this work, the precursor of peroxymolybdic acid prepared by hydrogen peroxide and molybdenum powder was used as the source of molybdenum, and PEG (8000) was used as the template. The molybdenum-containing hybrid with a band structure was prepared by mixing the precursor and template with stirring and thermal insulation. The nano-rod-shaped MoO2 was prepared through a two-stage hydrometallurgical process using the hybrid compound as raw material. X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), X-ray energy spectrometer (EDS) and scanning electron microscope (SEM) were used to analyze the phase, surface composition and morphology of the obtained MoO2 nanorods. The electrochemical capacitance behavior of MoO2 nanorods was studied using a three-electrode system and two-electrode system, and the performance of MoO2 nanorods as electrode assembly capacitors was also investigated. The results showed that the prepared MoO2 had a rod-like structure with 500 to 800 nm in length and with 100 to 200 nm in width. The MoO2 had uniform morphology and size with good dispersion and high purity. The specific capacitance of MoO2 nanorods was 366.7 F/g for the three-electrode system at the current density of 1 A/g, and the specific capacitance for the two-electrode system was 290.4 F/g, and the capacitance retention rate was higher than 72% after 2000 cycles of charging and discharging at 5 A/g current density, both showing the good electrochemical performance of MoO2 nanorods. The research results of this study can provide a new method for the preparation of other nano metal oxides.

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