The Chinese Journal of Process Engineering

Select

Cover and Contents

Chin. J. Process Eng.

Select

Editorial from the Editor-in-Chief

Suojiang ZHANG

Chin. J. Process Eng. 2020, 20 (1): 1-2. DOI: 10.12034/j.issn.1009-606X.220001

Abstract （531）

PDF （424KB）（119）

Save

四季更迭，岁去年来，才刚刚叹完红枫知秋，不知不觉又到了雪漫故园的时节。时光总是不慌不忙，不急不缓，见证了时空交替的神奇转换，时光承载了过去一年里的重担和升华，也满载着对未来的期望与寄托。在这样一个新旧更替、万象更新的时刻，《过程工程学报》也细细回首了一路走来的点滴，展望新的憧憬、新的企盼！

Related Articles | Metrics

Select

Prospects of process and bioreactors for large scale cultured meat production

Xueliang LI Guoqiang ZHANG Xinrui ZHAO Xiulan SUN Jingwen ZHOU Guocheng DU Jian CHEN

Chin. J. Process Eng. 2020, 20 (1): 3-11. DOI: 10.12034/j.issn.1009-606X.219179

Abstract （882）

PDF （776KB）（334）

Save

The idea of culturing animal muscle tissues in vitro as food stocks for human consumption was conceptualised as early as 1930s and patented in the 1990s, but the technique has not been proven at an industrially relevant scale as of today. In the past five years or so, cultured meat enjoyed a surge of popularity in terms of media coverage, particularly since the high profile taste-test event of the first lab-grown beef burger in 2013. Over two dozens of companies have joined the effort to bring cultured meat to the market, but a consumer-ready product is yet to be seen. In addition to regulatory requirements and socio-ethical implications, a major bottle-neck that is hindering the implementation of large scale cultured meat production is the lack of an understanding of the scaling-up effects on animal cells, including mass transfer, heat transfer, mixing and shear stress, etc. Conventionally, animal cells and tissues are mostly cultured in the high-value, low-volume pharmaceutical industry. Even production facilities that are considered high-throughput are typically clusters of small production lines under 2?20 m3 running in parallel, where the homogeneity of the culturing environment is relatively easily maintained. Cultured meat from animal muscle cell cultivation as a commodity to compete with the agriculture industry demands volumes of bioreactors and cell densities at least an order of magnitude higher than what the current technology can provide. Significant progresses in the development of bioreactor technology are required to make cultured meat a commercially viable alternative source of animal protein. In this review, the bioreactor aspects of cultured meat production, including reactor type and operation mode were covered, as well as existing drawbacks and potential solutions.

Reference | Related Articles | Metrics

Select

Mechanism analysis of refrigeration performance of gas wave oscillation tube influenced by high-temperature port pressure

Peiqi LIU Chuhan GAO Xiang LI Yang YU Dapeng HU

Chin. J. Process Eng. 2020, 20 (1): 12-19. DOI: 10.12034/j.issn.1009-606X.219129

Abstract （565）

PDF （1186KB）（142）

Save

The high-temperature port pressure is an important parameter affecting the refrigeration performance of the gas wave oscillation tube. By establishing a double-opening gas wave oscillating tube experimental platform, the relationship between the cooling temperature drop of the gas wave oscillating tube and the high-temperature port pressure was quantitatively measured. In order to analyze the internal mechanism of the phenomenon, an analysis model of the gas wave oscillating tube was established. It was found that the temperature drop of the whole machine increased first and then decreased with the increase of the high-temperature port pressure. The pressure of high-temperature port had the optimal value. When the high-temperature port pressure was low, the interface between the incident gas of the gas wave oscillating tube and the original gas in the tube was discharged from the high-temperature port of the oscillating tube, so that the reflux gas at normal temperature in the low-temperature port increased, and blended with the low-temperature incident gas after expansion in the tube, reducing the cooling performance of the oscillating tube. The simulation results showed that when the high temperature port pressure were 0.10 and 0.14 MPa, the ratio of high-pressure gas in HT to total high-pressure gas was 7.4% and 4.9%, respectively. As the pressure of the high-temperature port increased, the cooling performance was improved. However, the high-temperature port pressure also promoted the increase of the reverse compression wave intensity. The reverse compression wave pressures were 0.107 and 0.135 MPa at high-temperature port pressure of 0.11 and 0.14 MPa, respectively, which was not conducive to refrigeration. Therefore, the blending degree of the incident high pressure gas and the high-temperature side gas and the reverse compression wave pressure were the two factors why the high temperature port pressure had an optimum value.

Reference | Related Articles | Metrics

Select

Numerical simulation of mass transfer characteristics in an airlift reactor with a horizontal sieve plate

Zifan WANG Zhiyong ZHENG Minjie GAO Xiang LI Xiaobei ZHAN

Chin. J. Process Eng. 2020, 20 (1): 20-26. DOI: 10.12034/j.issn.1009-606X.219137

Abstract （526）

PDF （1576KB）（233）

Save

A CFD simulation of the mass transfer and flow field characteristics of gas–liquid two phases in an airlift reactor with a horizontal sieve plate was carried out by combining turbulent aggregation kernel with Lehr breakage kernel in the population balance model. The simulation results agreed well with the experimental results. The effects of horizontal sieve plate on the gas holdup, bubble diameter, volumetric mass transfer coefficient and gas–liquid flow field and velocity in the airlift reactor were investigated. It showed that the accumulation of the gas phase beneath the sieve plate increased the local gas holdup in the region, thereby increasing the overall gas holdup in the reactor. The forced re-distribution on the gas phase by the sieve plate attenuated bubble coalescence in the region between the sieve plate and the liquid surface, thereafter, decreased bubble diameter and increased the specific surface area of bubbles. A large number of bubbles smaller than the bubbles with the initial diameter were generated by the holes on the sieve plate with the breakup action, which increased the specific surface area of bubbles near the sieve plate. The velocity difference between the gas and liquid phases in the vicinity of the sieve plate was increased by the retardation on the liquid phase, thus improving the mass transfer coefficient of the liquid film in the region. The sieve plate reduced the flow velocities of liquid and gas in the reactor, thereby increased the contact time between the gas and liquid phases, increased the overall gas holdup of the reactor and enhanced the gas–liquid mass transfer. The volumetric mass transfer coefficient in the reactor was improved by assembling the horizontal sieve plate. The works would be beneficial to optimized internal structure of the airlift reactor and its applications.

Reference | Related Articles | Metrics

Select

Physical simulation on molten steel flow characteristics in the RH reactors with different arched snorkels

Zhifeng REN Zhiguo LUO Zongshu ZOU

Chin. J. Process Eng. 2020, 20 (1): 27-34. DOI: 10.12034/j.issn.1009-606X.219171

Abstract （525）

PDF （539KB）（114）

Save

In order to improve the vacuum refining efficiency of Ruhrstahl–Heraeus (RH), three new RH vacuum degassing vessels with arched snorkels were designed and the corresponding physical models were established. In the water simulation experiment, the circulation flow rate and mixing time of the RH with arched snorkels and rounded snorkels were researched from the aspects of snorkel shape, gas flow rate and the insertion depth of the snorkel. The results showed that, compared with conventional RH with rounded snorkels, the circulation flow rate of new RH reactors increased by 45%~218%, the mixing time decreased by more than 15%. When the maximum gas flow rate of RH with rounded snorkels reached, the circulation flow rate of the three RH with arched snorkels still increased linearly. Compared with the gas flow rate of traditional RH (60~130 m3/h), the maximum circulation flow rate of new RH reactor with arched snorkels increased by more than 48%, which would be convenient short-time and high-strength vacuum refining operation. For the three new type RH with arched snorkels, the circulation flow rate linear increased with the increase of gas flow rate and increased with the increase of immersion depth, and the mixing time decreased accordingly. In practical application, the immersion depth of two RH with relatively small arches should be greater than 545 mm, the immersion depth of RH with maximum arches should be greater than 818 mm, the maximum gas flow rate of three RH reactors with arched snorkels should be controlled at about 173 m3/h. Compared with a gas flow rate of traditional RH (60~130 m3/h), the circulation flow rate of 1#, 2# and 3# RH with arched snorkels increased about 100%, 42% and 112% respectively, mixing time reduced more than 30%, 15% and 34% respectively. In argon flow rate range of the experiment, the circulation flow rate of RH with unsymmetrical arched snorkels was the maximum, and its mixing time was the minimum.

Reference | Related Articles | Metrics

Select

Pressure drop of gas-solid parallel flow in an axial moving bed filter

Han Lü Yiping FAN Yafei ZHAO Chunxi LU

Chin. J. Process Eng. 2020, 20 (1): 35-43. DOI: 10.12034/j.issn.1009-606X.219184

Abstract （545）

PDF （1060KB）（131）

Save

The pressure drop characteristics of an axial moving bed were investigated by varying the operating parameters including the superficial activation energy gas velocity, the particle circulation rate and the dust concentration in the inlet gas. The results showed that when the circulation rate of particles increased from 0 to 2.26 kg/(m2?s), the pressure drop of the equipment decreased slightly by 0.03 kPa. Besides, the influence of press cake in bed on the stability of pressure drop was studied under the operating condition of dust load. When the dust concentration in the inlet was low, the dust deposited in the moving bed could not form a stable filter cake structure, and the pressure drop fluctuation of the equipment was considerable. When the inlet gas dust concentration increased to 89.10 g/m3, the formation of filter cake in the moving bed tended to be stable, and the pressure drop operation of the equipment gradually became stable. Under dust load condition, when the equipment was in the fixed bed operation state, the static pressure drop increased rapidly with filtration, and increased with the increase of the dust concentration in the inlet gas, and the pressure drop increased faster. In addition, the pressure drop of the equipment reached a stable state around 500 s, at which time the pressure drop increased by about 0.10?0.14 kPa, and the fluctuation amplitude of the pressure drop after 500 s gradually decreased with the increase of dust concentration. Furthermore, when the superficial activation energy gas velocity was 0.126 m/s and the dust concentration was 89.10 g/m3, the process of press cake forming and damaging present a dynamic balance. After filtering for 500 s, the pressure drop stabled at 0.88 kPa. At the same time, the equipment had a high dust removal performance, and the dust collection efficiency of the equipment was more than 96%.

Reference | Related Articles | Metrics

Select

Synthesis of the polyacrylic acid aluminum modified bentonite composite and its adsorption of Cr(VI)

Shuang WANG Hongfei GUO Bin ZHAO Xiuwu LIU Jilin CAO

Chin. J. Process Eng. 2020, 20 (1): 44-51. DOI: 10.12034/j.issn.1009-606X.219141

Abstract （631）

PDF （2319KB）（187）

Save

The pollution caused by toxic metal ions on ecosystems, agriculture and human health has attracted worldwide attention. Cr(VI) has detrimental effects on livers, lungs, kidney and nervous systems of mammals. Thus, the removal of Cr(VI) ions from wastewater are very important. Cr(VI) occurs as CrO42?, HCrO4?, Cr2O72? and HCr2O7? in aqueous solution. The surface of natural bentonite is negatively charged and has a small adsorption capacity for anions. The natural bentonite is powdery and difficult to separate from treated aqueous solutions. To improve the adsorption performance and application performance of bentonite to Cr(VI), the polyacrylic acid aluminum modified bentonite composite was prepared according to the following steps. Bentonite was modified with aluminum chloride hexahydrate, the polyacrylic acid-modified bentonite was prepared by polymerization of acrylic acid with aluminum modified bentonite in aqueous solution, and the polymer product were modified with hexadecyl trimethyl ammonium bromide (CTMAB) in aqueous solution. The characteristics of natural bentonite and modified bentonite were determined by XRD, FT-IR and SEM. Batch adsorption of Cr(VI) onto modified montmorillonite was investigated. The results showed that aluminum, acid monomers and CTMAB had intercalated into bentonite interlayers, and did not destroy the basic structure of natural bentonite. The adsorption capacity of Cr(VI) was 1.996 mg/g for 200 mL initial concentration of 20 mg/L by 0.5 g adsorbent at 25℃. The adsorption process to Cr(VI) was corresponding with the Lagergren secondary adsorption kinetics equation, chemical adsorption was the main control step. The adsorption capacity of the adsorbent increased with increasing the initial concentration of Cr(VI). The equilibrium adsorption capacity of the adsorbent for different concentrations of Cr(VI) was corresponding with the Freundlich isotherm equation. The adsorption of Cr(VI) onto the composite bentonite was multimolecular layer adsorption. The adsorption of Cr(VI) by granular adsorbent was mainly complexation reaction adsorption.

Reference | Related Articles | Metrics

Select

Simulation and optimization of methylchlorosilane distillation scheme

Xiongwei ZENG Jinxin PENG Zhenhao XI Ling ZHAO Weikang YUAN Changhong NIE Xiaohui ZHAO

Chin. J. Process Eng. 2020, 20 (1): 52-58. DOI: 10.12034/j.issn.1009-606X.219156

Abstract （746）

PDF （490KB）（193）

Save

Methylchlorosilane crude monomer is the mixture of several components with a close boiling point, which demands high mass purity in subsequent polysiloxane polymerization process. Traditionally, seven to ten distillation columns are used to separate these methylchlorosilane components with huge energy consumption. In the field of this research, prevailing industrial seven-column scheme was simulated by using Aspen plus software. The effect of distillation column bottom extraction ratio, reflux ratio, feed stage and top pressure on product concentration and heat duty were studied systematically for the optimization of operation conditions using the method of double factors sensitivity analysis. According to sensitivity analysis, the appropriate operation conditions of Me1 column were as follows, that molar bottom extraction rate was 0.92, molar reflux ratio was 130, feed position was at 210th theoretical stage and top pressure was 0.18 MPa, respectively. According to energy calculation of seven-column scheme, heavies removal column, low removal column and Me1 column took up 96.2% of total heat duty consumption. In order to reduce energy consumption, new energy saving scheme was studied and simulated. Thermodynamic analysis showed that pressure was a non-significant influencing factor for key components separation of heavies removal column and low removal column. So, a more energy-efficient distillation process, double effect distillation, had been studied for two columns to achieve heat integration between heavies removal column condenser and low removal column reboiler. The result of rigorous simulation showed that the new double effect distillation scheme, comparing to original two-column scheme, can reduce total annual cost (TAC) by 39.70%. The thermodynamic analysis of Me1 column showed that relative volatility of key binary components was near 1. So the heat pump distillation scheme had been developed to improve heat efficiency of Me1 column. The result of rigorous simulation showed that heat pump distillation scheme, comparing to original Me1 column scheme, can reduce TAC by 41.42%.

Reference | Related Articles | Metrics

Select

Estimation of surface tension of Al-Mg-Li ternary alloy

Shanshan LIU Bo WANG Ailin ZHOU Jieyu ZHANG Kuochih CHOU

Chin. J. Process Eng. 2020, 20 (1): 59-66. DOI: 10.12034/j.issn.1009-606X.219180

Abstract （551）

PDF （550KB）（169）

Save

The characteristics of the aluminum?magnesium alloy are light, good mechanical properties, corrosion resistance, low energy consumption, green and cheap, which make it more and more popular. Currently, aluminum?magnesium alloy has been widely used in automobile manufacturing, doors and windows sheet, medical apparatus and instruments, aerospace and marine transportation and other fields. The performances of aluminum?magnesium alloy are mainly affected by its thermophysical properties. It is important to study the surface properties involved in the presence of all liquid processes in the industrial process than other thermophysical properties. Surface tension, one of the key influence factors to the reaction of multiphase system and mass transfer, is a significant property of liquid metal, which plays a decisive role in the crystal growth of alloys, the microscopic appearance of welded joints and the cracking of metals during solidification. However, it is difficult to measure the surface tension at high temperature, only a small number of reference data can be referred to. In this work, the surface tensions of the Al?Mg, Al?Li and Mg?Li binary systems at 973 K were estimated on the basis of Butler?s equation, in combination with excess Gibbs energies, and the factors influencing surface tension were studied. The calculation results showed that the surface tension of aluminum melts decreased with the increase of magnesium or lithium content, the surface tension of magnesium melt decreased with increasing additions of lithium. On this basis, the surface tension of Al?Mg?Li ternary alloy at 973 K was calculated by using Chou model. The calculation results indicated that surface tension of Al?Mg?Li ternary alloy was approximately in the range of 0.326?0.851 N/m and its surface tension increased as the aluminum or magnesium content increased. Further, the essential factors that influence the surface tension were obtained. The results have important theoretical significance and practical application value for engineering research.

Reference | Related Articles | Metrics

Select

The regulation of electric field on CaO-SiO2-Al2O3 slag structure

Pan ZHANG Junhao LIU Kuixian WEI Zhi WANG Wenhui MA

Chin. J. Process Eng. 2020, 20 (1): 67-73. DOI: 10.12034/j.issn.1009-606X.219182

Abstract （504）

PDF （1624KB）（189）

Save

To development the photovoltaic industry for high-quality, high-end, the high-quality silicon raw materials are urgently required. Since boron (B) has a large separation coefficient and a small saturated vapor in the silicon, it is difficult to remove by directional solidification and vacuum melting or the like. B in silicon is one of the most difficult impurities to remove, slag refining is a mean to effectively remove B from silicon materials. In the slag refining process, the introduction of electric field can significantly improve the refining effect. The refining effect is closely related to the slag structure. In view of the difficult problem of removing B from silicon, this work studied on the structural level. The influence of electrical field on the structure was studied by observing the changes of different part of the slag structure and the high temperature quenching slag structural under different electric field conditions. It was found that the introduction of electric field caused the directional movement and redistribution of ions in slag, which caused the change of the slag structure. The upper structure of the slag was more completely depolymerized under the action of the electric field, but the slag structure was basically unchanged in the part which was from the interface of the slag. The electric field enhancement was beneficial to the depolymerization of the slag and when the electric field strength reached 10 V, the relative amount of Q0 structural unit with more non-bridge oxygen (NBO) increased. The upper structure of the slag was more sensitive to the change of the electric field. But the change of structure in the lower part of the slag was not obvious when the electric field changed.

Reference | Related Articles | Metrics

Select

Stability and biofouling behavior of plastic films in microalgae cultivation

Yixuan WANG Chenghu YAN Wei CONG

Chin. J. Process Eng. 2020, 20 (1): 74-83. DOI: 10.12034/j.issn.1009-606X.219175

Abstract （630）

PDF （2483KB）（188）

Save

The stability of six typical kinds of plastic films including polyethylene (PE), polypropylene (PP), ethylene/vinyl acetate (EVA), polyvinyl chloride (PVC), polyurethane (PU) and polyethylene terephthalate (PET) in NaClO, NaOH and HCl solutions and biofouling behavior in microalgae cultivation (Chlorella vulgaris) system were studied. The results showed that PVC film performed the poorest stability, and the transmittance decreased about 50% after immersing in NaClO, NaOH and HCl solutions. The transmittance of PU film and EVA film declined 10%?15% in NaClO and NaOH solutions, respectively. The transmittance of the other three kinds of plastic films has no significant change when immersed in NaClO, NaOH and HCl solutions for 24 h. Obvious microalgae biofouling behavior happened in six kinds of films, which was a typical biofilm formation process. Adhesion behavior of PVC surface was the most distinct, and the transmittance declined to about 0 on the 7th day, and the amount of adsorption solids increased with time and reached 3069 ?g/cm2 on the 45th day. However, the amount of adsorption solids on PU, EVA, PE, PP and PET film surface increased sharply and then decreased with time, the maximum amounts were 292, 375, 292, 194 and 236 ?g/cm2, respectively. The increase of chlorophyll content on the surface of the plastic films was not obvious in the first 4 d, which indicated that the initial stage of the adhesion was mainly the adhesion of protein and extracellular polymeric substances (EPS), and then microalgae cells began to adhere. The attachment of protein, EPS and microalgae cells on the plastic films was a typical biofilm formation process. The adhesion behavior of microalgae was affected by chemical structure and surface properties of the films, such as hydrophilicity, roughness and surface charge. For Chlorella vulgaris, polyolefin (PE, PP, etc.) and PET film surface with high hydrophilicity, low roughness and negatively charged will perform good anti-biofouling properties.

Reference | Related Articles | Metrics

Select

Preparation of biomimetic peptide attached supermacroporous poly(glycidyl methacrylate) microspheres for monoclonal antibody purification and its performance

Jia GE Xiangming NA Xuexing WU Weixing YANG Dongxia HAO Guanghui MA

Chin. J. Process Eng. 2020, 20 (1): 84-90. DOI: 10.12034/j.issn.1009-606X.219166

Abstract （588）

PDF （1346KB）（144）

Save

Recently, immunoglobulin G (IgG) has attracted great attentions in clinical medicine, biotechnology, stimulated the development of downstream purification technology of monoclonal antibodies. Now, the protein based affinity ligands during traditional chromatographic purification of IgG exist drawbacks including the high cost and low stability, which leads to the secondary contamination and biological toxicity to purified sample. Also the chromatographic agarose microspheres present shortcomings such as the gel compressibility and the mass transfer limitations. In this work, biomimetic peptide as the protein based ligands alternative, grafting on the supermacroporous dextran-poly(glycidyl methacrylate) microspheres (Dextran-PGMA) to overcome above drawbacks were prepared and to efficiently improve the IgG chromatographic separation. The hydroxy on dextran-grafted polymer chromatographic microspheres were converted to the epoxy groups in epichlorohydrin solution with 2 mol/L NaOH, and the epoxy groups were opened and coupled with biomimetic peptide, FYEILCH, to achieve the purpose of affinity modification. The SEM observed that the pore structure of macroporous was mostly maintained after coupling with the biomimetic peptide. The change of 10% dynamic binding capacity (DBC10%) of FYEILHC based on Dextran-PGMA microspheres and agarose microspheres under different flow rate (92~923 cm/h) was compared. The DBC10% of dextran-PGMA was declined only 8% under 923 cm/h, whereas the DBC10% of agarose was sharply declined about 25%. This phenomenon might be related to better mass transfer for IgG at higher flow rate on the Dextran-PGMA microspheres. The DBC10% of Dextran-PGMA microspheres maintained (21±1) mg/mL after cleaning-in-place (CIP) 40 cycles using 0.1 mol/L NaOH, indicating that the affinity medium had good chemical stability. The purity of recovered antibodies in plasma was 95.0%, demonstrating that this biomimetic peptide based affinity medium had great potential to purify IgG from complex biological samples. This biomimetic peptide grafted supermacroporous poly(glycidyl methacrylate) microspheres could meet the requirement for rapid and high-throughput separation of monoclonal antibody.

Reference | Related Articles | Metrics

Select

Optimization of enzymatic hydrolysis conditions for antioxidant peptide preparation from velvet antler collagen by response surface methodology

Yaru LAN Shuo HUANG Fei ZHAO Hongyu WU Yongxue GUO

Chin. J. Process Eng. 2020, 20 (1): 91-98. DOI: 10.12034/j.issn.1009-606X.219174

Abstract （546）

PDF （562KB）（129）

Save

It is believed that the velvet antler head has the best health benefits in traditional Chinese medicine. But its output is small, and the price is high. The first section of velvet antler is used frequently, and its protein/peptide content is highest among all sections. The polypeptide molecular weight is about 5 kDa. In this work, in order to make full use of the velvet antler resources, the water extract of the middle and low sections collagen of velvet antler was used as an enzymatic substrate to prepare an antioxidant peptide using papain. Enzymatic hydrolysis conditions (time, enzyme addition ratio, pH and temperature) were optimized by response surface methodology (RSM). The 1,1-diphenyl-2-picrylhydrazyl (DPPH?) radical-scavenging activity rate was used as an index. The target antioxidant peptide (molecular weight less than 5 kDa) obtained by separation through an ultrafiltration membrane was further separated by reversed-phase high-performance liquid chromatography. And 10 components, S1?S10, were obtained respectively and the components were lyophilized. Component S3 was further subjected by reversed-phase ultra-high performance liquid chromatography (UPLC) on-line electrospray ionization mass spectrometry (ESI-MS) for molecular weight determination. The polypeptide with the highest antioxidant activity was fractionated by ultrafiltration membranes of molecular weight cut off of 50, 10 and 5 kDa respectively. The results showed that the optimal experimental conditions were time of 56 min, enzyme addition of 1.40wt%, pH of 5.60, temperature of 60℃, DPPH? radical-scavenging activity rate was 83.09%. The molecular weight of polypeptide was 0.2?0.6 kDa. The resulting small molecule peptide has similar health benefits as the head section, is more easily absorbed by the body, and is easier to further process and store.

Reference | Related Articles | Metrics

Select

Molecular weight and molecular weight distribution of alginate determination by gel permeation chromatography

Ruixin ZHANG Zhihui WANG Wei CONG Fengji HUI Bin WANG

Chin. J. Process Eng. 2020, 20 (1): 99-107. DOI: 10.12034/j.issn.1009-606X.219177

Abstract （583）

PDF （464KB）（177）

Save

A method for the determination of molecular and molecular weight distribution of alginate by gel chromatography and conventional detector was proposed. Alginates in a wide range of viscosities extracted from two dominated raw materials—Lessonia nigrescence and Lessonia trabeculata were taken as the samples. The relative molecular weight of alginate was determined by high-performance gel permeation chromatography (GPC) combined with refractive index detector (RID) with pullulan served as a standard. The corresponding relations of relative weight average molecular weight ( ), relative number average molecular weight ( ) measured by GPC–RID and absolute weight average molecular weight ( ), absolute number average molecular weight ( ) measured by multi-angle laser scattering (GPC–MALLS) were obtained by least square method. The results showed that there was a good linear correlation between the relative molecular weight of alginate determined by GPC–RID and the absolute molecular weight of alginate determined by GPC–MALLS. The correlation index was more than 0.9. The relative error between the absolute weight average molecular weight determined by the established GPC–RID method and the absolute weight average molecular determined by GPC–MALLS was less than ?12%. The relative error between the absolute number average molecular weight determined by the established GPC–RID method and the absolute number average molecular determined by GPC–MALLS was less than ?12%. The polydispersity index calculated by the established GPC–RID method was less than ?12%, compared with that obtained by GPC–MALLS method. The GPC–RID method for the determination of the relative molecular weight of alginate can be used to determinate the absolute molecular weight and the polydispersity index of alginate. It manifested that it was feasible and economical to use the GPC–RID method provided in this work for the determination absolute of the absolute weight molecular weight, absolute number molecular weight and polydispersity index of alginate. The method can save the investment on the instrument and reduce the cost of determination the molecular weight of alginate.

Reference | Related Articles | Metrics

Select

Ionic liquids self-templating to synthesize nitrogen-doped porous carbon materials for CO ₂ adsorption

Jiahui LIU Huiting LIU Guoying ZHAO Zhenyu SUN

Chin. J. Process Eng. 2020, 20 (1): 108-115. DOI: 10.12034/j.issn.1009-606X.219164

Abstract （545）

PDF （2351KB）（180）

Save

With the increase of man-made emissions, CO2 capture after combustion has become a key component of greenhouse gas emission reduction. The search for a better CO2 capture material has caused great attention and nitrogen-doped porous carbon materials are considered as one of the most promising candidates. However, traditional preparation methods of nitrogen-doped porous carbon materials suffer from the shorts of complex process, harsh reaction conditions and low product yield. Using ionic liquids as the raw materials to synthesize nitrogen-doped porous carbon materials through ionothermal cyclotrimerization is a simplified and high-yield manner. In the present works, a series of nitrogen-doped porous carbon materials were synthesized directly by high temperature carbonization using cyano ionic liquids as raw material. By varying the structure and anions of the ionic liquid precursor and synthesis conditions, the pore architecture and surface functional groups of the materials could be controlled. The ionic liquid precursors were characterized by 1H-NMR, CHN element analysis and thermogravimetric analysis (TGA). The nanostructure of the porous carbon materials were observed by Transmission Electron Microscope (TEM) and the types of N-containing groups of the carbon material were investigated by X-ray photoelectron spectroscopy (XPS). The N element content was confirmed by elements analysis. The pore structures were evaluated by Brunauer–Emmett–Teller (BET) nitrogen sorption isotherms measured at 77 K. CO2 adsorption performance of these materials was carried out on a gravimetric microbalance (IGA). Combing the BET results and TGA analysis showed that the anions of ionic liquids acted as the template agent in the process of polymerization. These nitrogen-doped porous carbon materials mainly had mesoporous structure and the highest specific surface area reached to 732.6 m2/g. The highest N content reached to 9.9wt%. Owing to strong interactions between the CO2 molecules and nitrogen-containing basic sites, the highest CO2 adsorption quantity reached to 20.9wt% under 1.8 MPa at 25℃. The materials could be completely regenerated under the vacuum at 180℃, indicating its good stability.

Reference | Related Articles | Metrics

Select

Effect of Zn modification on hydroisomerization performance of the Fischer?Tropsch heavy diesel over Ni/ZSM-22 catalyst

Yiling BAI Lichuang FAN Tao LI Huimin CHEN Huaike ZHANG Yong YANG Guangjin ZHANG

Chin. J. Process Eng. 2020, 20 (1): 116-122. DOI: 10.12034/j.issn.1009-606X.219167

Abstract （590）

PDF （696KB）（111）

Save

The hydroisomerization catalyst is a metal-acid bifunctional catalyst that provides addition dehydrogenation function by metal component, and acidic component provides isomerization function. Hydroisomerization can effectively reduce oil pour point, provide low-temperature flow performance, and improve oil quality. The ZSM-22 zeolite was modified by ion exchange, molding and loading methods to obtain different Zn loadings. The physicochemical properties were characterized by X-ray diffraction (XRD), N2 physical adsorption-desorption (BET), X-ray fluorescence (XRF) and pyridine adsorption infrared (Py-IR). Ni-based hydroisomerization catalyst was prepared by using modified ZSM-22 zeolite as an acidic component and Ni as a metal component. The heterogeneous pour point depressing performance was evaluated by using Fischer–Tropsch heavy diesel oil as a raw material in the fixed bed reactor. Liquid and gas products were measured by off-line gas chromatography and on-line gas chromatography to calculate diesel yield. The results showed that ion exchange had little effect on the zeolite structure, and Zn species were highly dispersed on the surface of the zeolite. The Br?nsted (B) acid content of the catalyst had a significant effect on the activity. The higher B acid content, the higher activity of the catalyst. The introduction of Zn in the zeolite reduced the acidity ratio of B acid to Lewis (L) acid (B/L). With the increase of Zn content, the B/L value decreased, the yield of isomeric hydrocarbon increased, the cracking reaction was effectively inhibited, and the diesel yield was improved. Loading Zn could significantly reduce the cold filter point of heavy filter, and the cold filter point rose with Zn load content increased gradually. When the metal hydrogenation performance was the same, the matching of the metal and acid sites on the catalyst and the heterogeneous performance of the heavy diesel were improved with the decrease of B acid content. When the cold filter point of diesel reached the requirement of -10# diesel of China VI National Standard (cold filter point –5℃), the yield of prepared HI-3 catalyst reached 90.65%.

Reference | Related Articles | Metrics

Select

Cover and Contents

Chin. J. Process Eng.

Select

Research status of hydrodynamic characteristic parameters of flotation equipment

Jikang HAN Weizhi WANG Wei ZHANG Zhiwei SHAN Dong WANG

Chin. J. Process Eng. 2020, 20 (10): 1121-1133. DOI: 10.12034/j.issn.1009-606X.220139

Abstract （511）

PDF （1532KB）（294）

Save

Flotation equipment is an important gas–liquid reaction device in the field of mineral processing engineering. Flotation equipment has been used for one hundred years. With the rapid development of society, flotation equipment has gradually developed towards automation and large-scale. In recent years, more and more researches and analysis of hydrodynamic characteristic parameters in flotation equipment have been carried out, which has further promoted the reasonable enlargement and optimization of equipment. This work briefly introduced the current development and application status of flotation equipment, then summarized in detail the detection methods, principles and the current research status of three important hydrodynamics characteristic parameters in flotation equipment: bubble size, gas holdup and bubble velocity. According to the current development direction of mineral processing equipment, it was pointed out that how to accurately detect the parameters of the flotation bubble and improved the adaptability of the detection device, and widely applied in the industry to improve the flotation index are still a key issue that researchers faced at present. Image processing technology which can detect multiple characteristic parameters in the flotation equipment had been widely used, but bubble image processing methods which the majority of research scholars had put forward at present have limitations, and failed to involve many complicated details and the actual environment of concentrator, leading to the poor stability and low accuracy of bubbles when bubbles feature was extracted. Therefore, it was necessary to develop machine vision technology that was used in a variety of complex environments and had a strong ability to sort complex problems. At the same time, some sophisticated intrusion detection equipment such as conductivity probes still had certain defects in complex flotation environments. How to design and develop intrusive devices that are more conducive to complex flotation environments was one of the current research direction.

Related Articles | Metrics

Select

Review on magnetic droplet generation and manipulation in microchips

Chao LONG Rui CHEN Chi ZHAI Fei CHEN Chunxi YANG

Chin. J. Process Eng. 2020, 20 (10): 1134-1146. DOI: 10.12034/j.issn.1009-606X.219346

Abstract （457）

PDF （648KB）（117）

Save

In recent years, magnetic droplets with microscale, multiphase and contactless properties have received wide attentions from researcher of science and business for their successful applications in biological cell separation and targeted drug therapy. However, the main challenge is how to manipulate magnetic droplets approaching the set position accuracy. Therefore, three aspects including the current methods of generating and manipulating magnetic droplets, the basic mechanism of magnetic droplet manipulation and their control mechanism were summarized in this work. At present, the control methods for magnetic droplets can be divided into three categories. The first type was the permanent magnets-mechanical method where permanent magnets were placed on a mechanically mobile platform. By means of moving the platform, the distance between the permanent magnet and the microchip was changed and then the magnetic field intensity was also regulated. Moreover, the dynamic magnetic droplets were controlled. The second type was the electromagnet-electric method where the situation errors of droplets were detected by high-speed camera and sent to controller and the prebuilding mathematical model to obtain control output in order to regulate magnetic field intensity for manipulates the magnetic droplet. The third type was permanent magnets/electromagnet-electric mixed method where advantages of two methods mentioned above were combined to manipulate magnetic droplets for better control. Finally, the drawbacks and difficulties of current methods of magnetic droplets generating and manipulating were summarized and further possible research techniques and research fields were prospected.

Related Articles | Metrics

Select

Flow field simulation and structural optimization of purifier based on CFD-DEM method

Wenhao SHEN Yaxin ZHANG Jiang SONG

Chin. J. Process Eng. 2020, 20 (10): 1147-1155. DOI: 10.12034/j.issn.1009-606X.219356

Abstract （617）

PDF （3458KB）（374）

Save

The discrete element method (DEM) was used to establish the random stacking cylindrical activated carbon in the adsorption filter screen and the computational fluid dynamics (CFD) was used to simulate the flow field in the air purifier. On the basis of simulation and experimental verification, the hole shape, diameter and spacing of the filters with the least pressure drop and the most uniform flow field for air purifier were explored. The results showed that the pressure drop of the air purifier mainly occurred in the axial direction. The inlet gas could be averagely distributed by the pre-filter to improve the purification effect of the gas in the adsorption filter screen. There was a stable linear flow in the chemical filter, which was not conducive to adequate chemical reaction of harmful substances. And there was a phenomenon of reflux and retention in the gas chamber between the filters. The flow state of the activated carbon adsorption filter screen was extremely unstable, and the complex accumulation pattern of particles led to obvious high velocity and gully flow. The pressure drop of adsorption filter was three times higher than that of the other two filters, and it was also the main source of noise and energy consumption. The number of edges had no effect on the uniformity of the flow field and the pressure drop in the adsorption filter of the polygon filling hole structure. When the hole structure was changed to a circle, the pressure drop was reduced by 52 Pa and the energy was saved by 18.4% (49 W). When the diameter of the filling hole increased from 8 mm to 12 mm, the pressure drop was reduced by 48 Pa and the energy was saved by 19.4% (45 W). The filter spacing had no effect on the pressure drop of the air purifier, and the flow field in the adsorption filter with circular and small pore sizes was the most uniform.

Related Articles | Metrics

Select

Process and leaching kinetics of extracting copper and cobalt from high silicon low grade copper-cobalt ore by selective reduction ammonia leaching

Ao GONG, Xuangao WU, Xiaoqiang YU, Dingchun WANG, Zhifeng XU, Lei TIAN

Chin. J. Process Eng. 2020, 20 (10): 1156-1165. DOI: 10.12034/j.issn.1009-606X.219351

Abstract （467）

PDF （3028KB）（186）

Save

The leaching process and kinetics of African high silicon low grade copper cobalt ore in ammonia leaching system were studied. Firstly, the controllable variable method was used to systematically study the effects of leaching agent concentration, additive dosage, reaction temperature, reaction time and liquid/solid ratio on the leaching rate of copper and cobalt through single factor experiments. Secondly, the phase and chemical composition of high silicon low grade copper?cobalt ore and leaching residue were analyzed by X-ray diffraction (XRD), inductively coupled plasma (ICP) and scanning electron microscope-energy spectrum (SEM-EDS). The results showed that the leaching rate of copper and cobalt can reach 97.29% and 95.18% respectively, under the technological conditions of ammonium sulfate as leaching agent with the concentration of 300 g/L, reducing agent of 0.7 g, leaching temperature of 353 K, reaction time of 240 min and liquid/solid ratio of 6:1. Finally, by analyzing the kinetic model of copper extraction by high silicon low grade copper?cobalt ore ammonia leaching, the activation energy, reaction order of ammonium sulfate concentration and particle size are 76.06 kJ/mol, 1.50 and 0.25, respectively, indicating that it should follow the interface chemical reaction control, and the corresponding kinetic equation was established.

Related Articles | Metrics

Select

Preparation of magnetic coagulant aid from wastes for enhanced pollutant precipitation

Xiaofei MENG Rong HOU He ZHAO Bin XU Linhao YANG

Chin. J. Process Eng. 2020, 20 (10): 1166-1173. DOI: 10.12034/j.issn.1009-606X.219353

Abstract （398）

PDF （2307KB）（141）

Save

In recent years, with the increasing of water treatment, the production of coagulated sludge has a sharp rise. So, the realization of coagulated sludge resource utilization is necessary. In this research, the coagulated sludge treated by carbonization at high temperature and polymerized ferrous sulfate (PFS) were added together to remove Fe(CN)63? pollutants. And the mechanism of coagulation was further studied. The structure of the coagulated sludge materials was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and magnetic hysteresis curve. The pollutant of Fe(CN)63? coagulated by PFS and coagulated sludge was analyzed by the removal rate, particle size and shape. The results showed that the sludge materials contained a large amount of carbon and it had some functional groups like carboxyl on the surface. Iron and vanadium oxides which had complexation ability were formed on the surface carbonized sludge materials. The crystallinity and grain size of the coagulated sludge were more ordered and more uniform by carbonization at high temperature which could benefit to the growth of flocs in the process of coagulation. The removal of Fe(CN)63? increased by adding coagulated sludge. Especially, the removal of Fe(CN)63? increased to 99.45% by adding the sludge which was carbonized at 700℃ with PFS:RW700=1:1.43. By the analysis of particle size and shape, the coagulated sludge was beneficial to the enhancement of pollutants during coagulation process. By optimizing the ratio of sludge material to PFS, the removal of Fe(CN)63? pollutant was also close to 100% by reducing the dosage of PFS. Compared with the other coagulants, the cost of water treatment decreased. This study provided theoretical and technical basis for the resource recycling of coagulated sludge. This new type of sludge resource utilization had promising application in the field of cyanide removal.

Related Articles | Metrics

Select

Recovery of manganese from the mother liquor after vanadium precipitation during vanadium extraction with calcified roasting and acid leaching process

Juhua ZHANG Yue LIANG Wei ZHANG Zhengliang XUE

Chin. J. Process Eng. 2020, 20 (10): 1174-1181. DOI: 10.12034/j.issn.1009-606X.219354

Abstract （522）

PDF （1285KB）（209）

Save

Recovering manganese resource from the mother liquor on one hand can improve the economic benefit of the whole process, and on the other hand is beneficial to realizing closed cycle of mother liquor and then can increase the environmental interest of the whole process because it can avoid the enrichment of Mn in the solution during recycling mother liquor which will bring side effect to the quality of vanadium pentoxide. Using oxalic acid to effectively separate the Mn2+ from the mother liquor was proposed and the effects of the solution pH, adding amount coefficient of oxalic acid, reaction temperature and time on the recovery rate of Mn and phases composition of the precipitations were investigated, and the effect of the numbers of recycling mother liquor treated by oxalic acid to recover manganese on the leaching process was studied as well. The results showed that oxalic acid can effectively separate the manganese from the mother liquor and the recovery rate of manganese reached 94.33% under the conditions that the solution pH was 4.0, adding amount coefficient of oxalic acid was 1.5, reaction temperature was 50℃ and the reaction time lasted for 60 min. The obtained product was hydrated manganese oxalate with purity of 98%, present as tabular crystals and formed in flower cluster-like. After treated with oxalic acid to remove manganese, the mother liquor was recycled to leach the roasted slag, and it was found that the recycling numbers have little effect on the vanadium leaching rate and the concentration of manganese contained in the vanadium-bearing solution, indicating the proposed method was helpful for realization of closed-cycle of the waste water in the whole process of vanadium extraction with calcified roasting and acid leaching.

Related Articles | Metrics

Select

Effects of salt ions on the hydration and expansion characteristics of montmorillonite

Yuanqing TAO Kefeng YAN Xiaosen LI Hao CHEN

Chin. J. Process Eng. 2020, 20 (10): 1182-1189. DOI: 10.12034/j.issn.1009-606X.219364

Abstract （504）

PDF （786KB）（89）

Save

As an important component of natural gas hydrate reservoir, montmorillonite is of great research significance to the exploitation and application of natural gas hydrate. The inhibition of salt ions in seawater on the hydration expansion of montmorillonite has important effects on the distribution of free water and bound water in hydrate reservoirs. Water content in montmorillonite with NaCl solution was measured by thermogravimetric method combined with several pretreatment methods (the centrifugal method, the direct drying method and the freeze-dried method). The effects of salt concentration on bound water and free water content of montmorillonite were analyzed. The variations of total water content and bound water content in montmorillonite with different NaCl solution concentration were discussed. The hydration and expansion characteristics of montmorillonite and the inhibition of salt ions were studied. The results indicated that the hydration expansion of montmorillonite was inhibited by salt ions. The existence of salt ions reduced osmotic hydration force. Meanwhile, it affected the van der Waals force between water molecules, the hydrogen bonding force and the electrostatic attraction force between water molecules and the surface of montmorillonite. The total water content of montmorillonite decreased with the increase of salt ions concentration. In the same time, bound water content of montmorillonite was inverse related to the salt ions concentration, and approached the minimum when the salt ions concentration was 0.2 mol/L, as the inhibition effect of salt ions on the hydration expansion of montmorillonite reached the peak. When the ion concentration was greater than 0.2 mol/L, the content of free water and bound water did not change significantly with the increase of salt ion concentration. Therefore, the study on the influence of salt ions on hydration and expansion characteristics of montmorillonite, so as to further explore the influence of salt ions on the formation of hydrate in montmorillonite, has important guiding significance for the study of hydrate distribution characteristics in deep-sea sediments.

Related Articles | Metrics

Select

Thermodynamic and kinetic analysis of the process of preparing Al?Si alloy from polysilicon cutting waste by diamond-wire

Ting XIAO Guoqiang Lü Junpeng WANG Xiongdong YANG Wenhui MA

Chin. J. Process Eng. 2020, 20 (10): 1190-1197. DOI: 10.12034/j.issn.1009-606X.219333

Abstract （411）

PDF （2449KB）（222）

Save

The diamond wire saw powder composition and its silicon oxides were analyzed by X-ray diffraction analysis (XRD), X-ray fluorescence spectrum analyzer (XRF) and Fourier transform infrared spectrometer (FT-IR). The possible reaction process for alloying between aluminum and diamond wire saw powder was analyzed, and its thermodynamics were determined by HSC Chemistry 6.0 software. The kinetics process of aluminum thermal reduction of SiO2 was discussed, and the Al?Si alloy preparation by using diamond wire saw powder with aluminum was experimentally investigated. The results showed that the diamond wire saw powder melted with aluminum in different mole proportion during the alloying process at the temperature range of 800~1600℃ with the influence of electromagnetic stirring. Meantime, SiO2 impurities can be reduced to Si during aluminum thermal reduction. The apparent activation energy was 364.1 kJ/mol, while the reaction order was 0.91. Finally, phase composition of alloy and slag were analyzed by EPMA, XRD, and the results were in agreement with the thermodynamic and kinetic analysis. This work provided a new idea for effectively solving the problem of silicon waste recovery and utilization during the photovoltaic industry.

Related Articles | Metrics

Select

Vaccine particle integrity-based purification of recombinant hepatitis B surface antigen using silica gel adsorption/desorption

Shengjie HU Yongdong HUANG Lan ZHAO Kai ZHU Zhuang MIAO Fei WANG Hongchao JIN Jian LI Jun YANG Hemu WANG Guanghui MA Hongshui YUAN

Chin. J. Process Eng. 2020, 20 (10): 1198-1209. DOI: 10.12034/j.issn.1009-606X.219329

Abstract （573）

PDF （1198KB）（113）

Save

Low stability was one of the biggest problems during traditional purification process of recombinant hepatitis B surface antigen (rHBsAg). A combination process of silica gel adsorption/desorption and hydrophobic interaction chromatography was proposed in this work. The effect of pH on HBsAg stability was studied from the particle integrity of view using static light scattering, fluorescence spectrum and dynamic light scattering, respectively. HBsAg was purified by silica gel adsorption/desorption using response surface methodology for experimental design, followed by hydrophobic interaction chromatography, and both its morphology and particle integrity were studied. In acidic solution, the electrostatic repulsion of HBsAg particles decreased leading to aggregation when pH of solution was close to the isoelectric point of HBsAg. In alkaline solution, hydrophobic patches inside HBsAg particles were likely to be exposed leading to disaggregation. The silica gel adsorption/desorption process was optimized. When HBsAg activity recovery was taken as the response value, the optimum operating condition was as follows: adsorption pH was 7.43, desorption pH was 10.48 and desorption temperature was 55.4℃, and HBsAg activity recovery was 39.1%. When purification fold was taken as the response value, the optimum operating condition was as follows: adsorption pH was 7.16, desorption pH was 10.52 and desorption temperature was 55.1℃, and purification fold was 1.90. After hydrophobic interaction chromatography, HBsAg activity recovery was 49.73% and the particle integrity was 85.79% respectively. Compared with conventional hydrophobic interaction chromatography, the efficiency of HBsAg purification was improved greatly using this combination method, etc., HBsAg activity recovery increased by 31.99%, the particle integrity by 20.90%, and the particle stability by 22.93%, respectively. It provided a new idea for both high efficient recombinant HBsAg purification and improvement of antigen particle integrity.

Related Articles | Metrics

Select

Secretory of a multicopper oxidase in Escherichia coli

Tao YANG Jian CHEN Fang FANG

Chin. J. Process Eng. 2020, 20 (10): 1210-1217. DOI: 10.12034/j.issn.1009-606X.219370

Abstract （686）

PDF （1070KB）（272）

Save

Biogenic amines (BAs) are organic compounds that present in fermented foods. The excessive intake of BAs is harmful to human health. Some enzymes belonging to the multicopper oxidase (MCO) family exhibit the activity of degrading a variety of BAs. Thus, they may have good application prospects in reducing ammonia (amine) hazards levels in fermented foods. It is of great significance to accomplish the secretion of multicopper oxidase for the purpose of modification of enzyme catalytic properties for its industrial production and applications. In this work, the secretion of multicopper oxidase in Escherichia coli was achieved by fusing the signal peptide PhoA to the N-terminal of MCOB from Bacillus amyloliquefaciens with an extracellular activity of 69.8 U/L. Secretory of MCOB was improved by optimizing the induction and secretion conditions. The optimal fermentation conditions for MCOB were determined to be: the induction temperature was 25℃, the IPTG concentration was 0.05 mmol/L, induced when the cell density (OD600) reached 1.0, and 150 mmol/L glycine was added after 6 h of induction. After 40 h of fermentation, the extracellular activity of MCOB reached 238.1 U/L, which was 3.4 times of that before optimization.

Related Articles | Metrics

Select

Preparation of ceramic ultrafiltration membrane with high performance from dense ultrafine spherical Al2O3 powders

Pan LUO Yuge OUYANG Fei DING Junmei FAN Fangli YUAN

Chin. J. Process Eng. 2020, 20 (10): 1218-1226. DOI: 10.12034/j.issn.1009-606X.219378

Abstract （511）

PDF （1666KB）（223）

Save

Ceramic membranes with the advantages of excellent thermal, chemical and higher permeable properties have attracted more attention and have been applied in turbidity removal, sanitary wastewater and other important industries. However, the ceramic membrane required “coating-drying-sintering” process, in which the process inevitably leads to cracks and wide pore size distribution. In this study, ceramic ultrafiltration membranes with narrow pore size distribution and high permeability were prepared by the dip?coating method using ultrafine spherical alumina powders with high density and smooth surface synthesized by thermal plasma. The microstructure evolution of prepared membranes could be controlled by adjusting the sintering temperature, and the ceramic membranes with a narrow pore size distribution of 25?65 nm and a high pure water permeability of 986.4 L/(m2?h) were sintered at 1250℃. The sintering mechanism of the ceramic membrane was fully investigated and it was found that the narrow pore size distribution of membranes came from the spherical Al2O3 powders with the narrow particle size distribution and high density synthesized by thermal plasma, and the homogeneous sintering necks formed at 1250℃. The result indicated that the pure water flux of the membranes decreased as the sintering temperature increased. It can be explained that the surface of ceramic membranes became denser with the increase of the sintering temperature, resulting in the decrease in porosity and the average pore size. In addition, the prepared membranes were employed to filter the nano-silicon dispersion slurry to evaluate the performance of the membranes sintered under different temperatures. The result indicated that the membrane sintered at 1250℃ showed a higher removal rate of turbidity (99.96%), and the turbidity of the permeate was 0.231 NTU. Finally, the reduction of the permeate flux of the nano-silicon dispersion slurry were analyzed using pore blocking models, and it was found that the cake filtration model was suitable to the prepared membranes.

Related Articles | Metrics

Select

Effect of nano-Nb addition on microstructure and wear resistance of Fe-based alloy coatings by plasma transferred arc welding

Lulu XU Wenxu ZHANG Longsheng ZHAN Mingxi LI

Chin. J. Process Eng. 2020, 20 (10): 1227-1233. DOI: 10.12034/j.issn.1009-606X.219359

Abstract （459）

PDF （3521KB）（182）

Save

Plasma transferred arc welding is a kind of surface modification technology. Plasma transferred arc is used as a heat source and alloy powder is sprayed on the surface of metal materials to prepare a wear-resistant coating with excellent performance. In order to further improve the wear resistance of Fe-based alloy, hard particles are often used as the reinforcements of composite materials. At present, there are few researches on in-situ formed NbC reinforcements in Fe-based alloy coatings, and the density of NbC is very close to that of Fe-based alloy, which can be very evenly distributed in the coatings. In this work, Fe-based alloy coatings without nano-Nb and with mass fraction of 1wt%, 3wt% and 5wt% nano-Nb powder were prepared on Q235 surface by plasma transferred arc welding. The phase composition, microstructure, microanalysis and worn surface observation of the coatings were investigated by means of optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD), respectively. The microhardness and wear resistance of the coatings were tested using microhardness tester and pin-on-disc wear machine. The results showed that the main phases of Fe-based alloy coatings were composed of α-Fe, γ-Fe and Cr7C3. NbC phase was identified in the coating by adding nano-Nb powder, and Cr23C6 phase appeared with addition of 5wt% nano-Nb. The untransformed γ-Fe increased and the microstructure changed from approximately equiaxed microstructure to dendrite with addition of nano powder, and the greatly refined microstructure was obtained by adding 5wt% additive. The microhardness of coatings was improved, which was about 766 HV0.3 increased by about 250 HV0.3 with 1wt% and 3wt% nano-Nb. The wear resistance of coatings was also improved. The minimum friction coefficient of 0.48 was obtained by adding 3wt% nano-Nb. The wear mechanism changed from adhesive wear to abrasive wear.

Related Articles | Metrics

Select

New broaching exploitation method and feasibility analysis of marine gas hydrate reservoirs

Zhen SONG Kaili LI Jiahang SUN Zhonglei Lü

Chin. J. Process Eng. 2020, 20 (10): 1234-1240. DOI: 10.12034/j.issn.1009-606X.219377

Abstract （368）

PDF （1417KB）（136）

Save

At present, the main methods for extracting natural gas hydrates are thermal extraction, vacuum extraction and chemical reagent extraction. They are mainly used for the development of diagenetic hydrate reservoirs in tight cap rocks, and cannot be used to extract shallow non-diagenetic hydrates that account for 85% of deep water resources. Taking the Shenhu area of the South China Sea as the mining target area, a new type of broaching exploitation method was proposed on the basis of solid-state fluidization theory. A three-dimensional model of broaching exploitation method was established, the working principle, working steps and stope distribution of the new technology were explained in detail, and a broaching tube was designed for broaching, collecting and transportation mining tools. Use the knowledge of geotechnical mechanics to analyze the shear stress of the goaf produced by the broaching exploitation method can ensure that the goaf does not collapse and obtain the maximum stope volume. The force analysis of the broached pipe according to the mining conditions ensured that the broached pipe can work safely and stably. Finally, the daily gas production of the broaching technology was estimated. The results showed that the larger the goaf radius and the mining angle were, the more obvious the shear stress concentration in the goaf. The maximum shear stress occurred at the start and end positions of the upper part of the goaf. The maximum stress of the broaching tube during the mining process was less than the yield stress of the material. The daily gas output of the broaching technology was estimated to be 142000 m3, which had practical application potential.

Related Articles | Metrics

Select

Cover and contents

Chin. J. Process Eng.

Select

Application of ultrasonic intensification in hydrometallurgy leaching process

Jiewen YAN Dean PAN Bin LI

Chin. J. Process Eng. 2020, 20 (11): 1241-1247. DOI: 10.12034/j.issn.1009-606X.219357

Abstract （873）

PDF （1532KB）（349）

Save

In recent years, with the continuous scarcity of primary mineral resources, the decline in mineral levels, and the increase in secondary resources, how to efficiently recover precious metals from raw materials such as primary ore, concentrates or secondary resources is both an environmental issue and an economic issue that needs to be resolved. Hydrometallurgy, as a method of efficiently recovering metals, is leaching raw materials in acidic or alkaline solutions, transferring the metals to the solution in the form of ions, and then using extraction, solid?liquid separation and other means to recover the metals. Among them, leaching, as an important process in hydrometallurgy, has the advantages of high comprehensive recovery rate of valuable metals, higher recovery rate of low-grade ore than pyrometallurgy, and low operation difficulty. It has been widely used in metallurgy. At the same time, the leaching process has the disadvantages of high requirements on the concentration of the leaching solution, long reaction time, and slow reaction rate. To overcome the above disadvantages, it is an effective way to improve the existing metal hydrometallurgical process through various assisted leaching technologies. Among them, by adding ultrasonic to the external field, using ultrasonic cavitation mechanical effects and thermal effects to strengthen the reaction process together, it has the characteristics of improving the solid surface structure, uniform leachate system, and optimizing the reaction history. Compared with the traditional leaching process, the leaching time can be shortened, the leaching rate can be increased, and the amount of reagents can be reduced. The entire leaching process can be performed at room temperature, which greatly reduces the energy consumption. This work summarized the ultrasonic cavitation and its mechanism in the leaching process, highlighted the characteristics and advantages of the ultrasonic enhanced leaching process, put forward the limitations of ultrasonic itself, and prospected its future development in this field.

Related Articles | Metrics

Select

Experimental study on flow field and heat transfer performance of insert-spiral vertical upstream tube

Deqi PENG Chunxia YANG Jianping ZHANG Tianlan YU Weibiao YE Hao LI

Chin. J. Process Eng. 2020, 20 (11): 1248-1256. DOI: 10.12034/j.issn.1009-606X.219363

Abstract （412）

PDF （1609KB）（157）

Save

Through the particle image velocimeter (PIV) flow field experiment combined with heat transfer experiments, the effects of structural parameters such as spiral pitch, wire diameter and median diameter ratio of insert-spiral vertical upstream tube on the flow field and heat transfer performance were studied under different Reynolds number. The results showed that the insert-spiral can effectively disturb and mix the fluid in the tube, and a number of longitudinal vortexes were formed in the tube, and the vorticity of liquid increased near the wall of the tube, which was beneficial to the enhancement of heat transfer. When the Re number was the same, the average flow velocity v, Nu number and the comprehensive heat exchange performance (PEC) in the tube increased with the increase of the wire diameter, and increased with the decrease of the median diameter ratio. As the pitch increased, all three parameters tended to increase, and began to decrease when the pitch was greater than 20 mm. The resistance coefficient f of the fluid in the tube decreased with the increase of the wire diameter and the pitch, and increased with the increase of the median diameter ratio. In general, when the Re number was lower, the comprehensive heat transfer effect was best with a pitch of p=20 mm, a wire diameter of e=1.6 mm, and a median diameter ratio of D/d=0.75.

Related Articles | Metrics

Select

Feasibility study on intermittent operation of solution dehumidifier

Zhijia HUANG Heng ZHOU Feifei ZHUO

Chin. J. Process Eng. 2020, 20 (11): 1257-1264. DOI: 10.12034/j.issn.1009-606X.219379

Abstract （380）

PDF （613KB）（135）

Save

In order to solve the problem of air with liquid in the solution dehumidifier, a method of intermittent operation of the solution dehumidifier was proposed, which separated the air supply from the solution spray. The numerical model of dehumidifier was established, and the feasibility of the model was verified by comparing the experimental data and simulation data. Based on the model, the influence of operation parameters and design parameters of intermittent solution dehumidifier on dehumidification performance was studied and the operation effect of different air supply systems was simulated. The results showed that the static liquid holding capacity should be controlled in the range of 4.575~6.100 kg/kg and the packing height should be controlled in the range of 0.45~0.75 m, the intermittent operation method was more suitable to deal with the air with low temperature and high humidity (such as 20℃ and RH95%), which can solve the problem of traditional solution dehumidification with liquid. The dehumidification effect of the parallel staggered air supply system was the best, during the operation, the dehumidification rate was more than 5 g/kg, which can supply air continuously and meet the dehumidification demand.

Related Articles | Metrics

Select

Thermal performance analysis of seawater desalination system based on liquid gap heat pump membrane distillation

Qiyu ZHANG Le TONG Chen YUE

Chin. J. Process Eng. 2020, 20 (11): 1265-1272. DOI: 10.12034/j.issn.1009-606X.219350

Abstract （387）

PDF （705KB）（166）

Save

A novel brine solution concentration system based on the heat pump membrane technology was integrated to improve the membrane flux as well as reduce the consumption of cooling water. This proposed system was simulated by the Aspen Plus platform. After experimentally verifying the system simulation model, influences from the feed liquid temperature, temperature at permeate side and feed flow rate on the overall thermal performance indices of the system were studied. The results showed decreasing temperature at permeate side improved the permeability and decreased of the coefficient of performance (COP), and the change of temperature at permeate side played a great effect on the coefficient of performance under the fixed condition of the low temperature at permeate side. With increase of the temperature at permeate side, an optimal temperature value was obtained to maximize the water production ratio and minimize the energy consumption per ton of water, and the maximal water production ratio was 3.42, the minimal energy consumption per ton of water was 463 MJ/t under the working condition in this research. Besides, as the feed liquid temperature increased, the optimal temperature at permeate side increased. As the feed flow rate rised, permeability and coefficient of performance went up, while the energy consumption of tons of water rised and the water production ratio reduced. Moreover, when the feed flow rate was less than 3 L/min, the energy consumption of tons of water and the water production ratio reduced sharply as the feed flow rate increased. When the feed liquid temperature was 50℃, the feed flow rate increased from 1.5 L/min to 3 L/min, the value of GOR (Gained Output Ratio) decreased by 33.5%, while the rise of flow rate from 4.5 L/min to 6 L/min only caused GOR decrease by 10.6%.With increase of the permeation side temperature, an optimal temperature value is obtained to maximize the water production ratio and minimize the energy consumption per ton of water, and the maximal production ratio is of 3.42, the minimal energy consumption is of 463 MJ/t under the working condition in this research. Besides, as the feed temperature increases, the optimal permeation side temperature increases. As the feed liquid flow rises, permeability and energy efficiency ratio go up, while the energy consumption of tons of water rises and the water production ratio reduces. Moreover, when the feed liquid concentration is less than 3L/min, the energy consumption of tons of water and the water production ratio reduce sharply as the feed liquid flow increases.

Related Articles | Metrics

Select

Power characteristic of adhesive particles mixing in a stirred tank

Hao XIONG Yuyun BAO Jing WANG Ziqi CAI

Chin. J. Process Eng. 2020, 20 (11): 1273-1280. DOI: 10.12034/j.issn.1009-606X.220040

Abstract （410）

PDF （693KB）（160）

Save

Power consumption is an important parameter in the design and scale-up of stirred tank reactors. The effects of relative liquid volume, rotational speed and fill level on power consumption were experimentally investigated in a cylindrical stirred tank. The discrete element method (DEM) and Hertz-Mindlin with JKR model were used to investigate the effect of the adhesion force of particles with different relative liquid volumes on the power consumption. Results showed that the power consumption first increased and then decreased with the increase of the relative liquid volume, and reached a maximum when the relative liquid volume was 0.0162. With the increase of the rotational speed, the power consumption increased faster, but the rotational speed influence index on the power consumption decreased first and then increased with the increase of the relative liquid volume. The maximum power consumption was about 1.8 times of the power consumption with saturated particles. A new method for indirect measurement of cohesion between particles was proposed, and a linear relationship between power consumption and cohesion was obtained.

Related Articles | Metrics

Select

Effect of different particle sizes of modified fly ash on phosphate adsorption performance

Jianlin YANG Yuao ZHANG Shuhua MA Xiaohui WANG

Chin. J. Process Eng. 2020, 20 (11): 1281-1288. DOI: 10.12034/j.issn.1009-606X.219382

Abstract （365）

PDF （2547KB）（217）

Save

Excessive discharge of phosphorus in wastewater leads to increasingly serious water pollution. The fly ash was chemically modified into a hydrated calcium silicate adsorbent to explore its absorption effect on the phosphate. XRD, SEM, BET specific surface area and so on were used to characterize the adsorbents before and after particle size classification. Then the adsorption performance of the adsorbents with different particle sizes on phosphate was studied, and the adsorption mechanism was also investigated. The results showed that the chemical compositions of the adsorbents with different particle sizes showed significant segregation, and the pore structures were also significantly different. Specifically, compared to other adsorbent particles, the particles with the size of 50?75 μm had a higher content of calcium and silicon, lower content of aluminum, iron, and magnesium and thereof higher content of hydrated calcium silicate companied with aluminum-containing tobermullite crystals. The increase of calcium ions made it easy to combine with more phosphate to form a precipitate. At the same time, this particle had a higher specific surface area and more porosity and the loose and porous structure provided more active sites for calcium ions. When used as an adsorbent to adsorb phosphate, the saturated phosphorus adsorption capacity of the particles with the size of 50?75 μm can reach 17.1 mg/g, which was 19.58% higher than that of an unclassified adsorbent.

Related Articles | Metrics

Select

Treatment performance of ammonia-nitrogen wastewater containing high salt by copper-loaded resin

Ruoyu YIN Yunnen CHEN Caiqing HE Chen LIU

Chin. J. Process Eng. 2020, 20 (11): 1289-1295. DOI: 10.12034/j.issn.1009-606X.219368

Abstract （406）

PDF （947KB）（114）

Save

The ligand exchange adsorption method uses the ability of transition metal ions to form complexes. By supporting the transition metal on a certain adsorbent carrier, and then using the special complexation between the target pollutant and the transition metal, the target pollutant is adsorbed on the adsorbent. A ligand-loaded adsorbent was prepared by supporting Cu2+ with a resin as a carrier for the high-salt ammonia?nitrogen wastewater, and the ammonia nitrogen was selectively adsorbed onto the resin by the coordination of Cu2+ and ammonia nitrogen. Ammonia nitrogen is adsorbed to the resin in two ways: one is through the combination of NH4+ and OH? to generate NH3, which is coordinated with Cu2+on the resin; the other is that NH3 reacts directly with Cu2+ on the resin, so that ammonia nitrogen can be adsorbed. In this work, resins with different functional groups were selected as supports, modified with Cu2+, and their performance in treating high-salt ammonia nitrogen wastewater was studied. On the basis of selecting the best copper resin, the effects of pH, Na+ concentration, resin dosage and reaction time on the adsorption of ammonia nitrogen by copper resin were studied. In order to further explore the process of coordination adsorption, SEM, EDS and adsorption kinetics model were used to characterize the copper resin before and after ammonia nitrogen adsorption. The results showed that Cu2+ could combine with chelating resin D751 stably and exhibited salt tolerance and good adsorption effect of ammonia?nitrogen under wide pH value. Under the conditions of room temperature (25℃), pH=11, Na+ concentration of 4 g/L, resin dosage of 8 g/L, reaction time 60 min, the removal rate of ammonia?nitrogen by D751 copper-loaded resin was 34.8%. After adsorption of ammonia nitrogen by D751 copper resin, crystal structure substance appeared on its surface, which may be copper ammonia complex. In addition, the adsorption kinetics of D751 copper resin for ammonia nitrogen containing high saline was in good agreement with quasi-second-order kinetic model.

Related Articles | Metrics

Select

Flotation mechanisms of rutile in synergistic system composed by sodium oleate and sodium benzohydroxamide

Mingbao LIU Wanzhong GUO Siyu TIAN Mei CHEN

Chin. J. Process Eng. 2020, 20 (11): 1296-1303. DOI: 10.12034/j.issn.1009-606X.219332

Abstract （409）

PDF （879KB）（115）

Save

The flotation behaviors of rutile in combined regent system of sodium oleate (SO) and sodium benzohydroxamide (BHA) were studied via pure mineral flotation test. The interactions between reagents, reagents and mineral as well as the effect of the reagent combination on rutile flotation had been investigated through several measurements, including Zeta potential, contact angle, surface tension, UV diffuse reflectance spectroscope, concerning the interface chemistry properties at gas?liquid interface and solid?liquid interface. The results indicated that the reagent addition sequence influenced rutile recovery significantly and the combined use of reagent had a distinct positive-synergistic effect under different pH values. The flotation recovery of rutile and synergistic effect index followed the order: adding BHA prior to SO>pre-mixed before adding>adding SO prior to BHA. The electron-rich double bond in SO may interact with the electron-deficient benzene ring in BHA to form diverse interionic/intermolecular association complexes. The amount of the complex presented as the optimum configuration on mineral surface was critical for the synergistic effect of reagent combination and rutile flotation behavior. The effect of reagent combination on flotation recovery rate agreed well with that on the rutile bandgap width according to the UV diffuse reflectance spectroscope spectrum of rutile sample after interacted with the reagent combination under various conditions.with the electron-deficient benzene ring in BHA to form diverse interionic association complexes. The amount of the complex presented as the optimum configuration on mineral surface is critical for the synergistic effect of reagent combination and rutile flotation behavior. The effect of reagent combination on flotation recovery agree well with that on the rutile bandgap width according to the UV diffuse reflectance spectroscope spectrum of rutile sample after interacted with the reagent combination under various conditions.

Related Articles | Metrics

Volumn Content