The Chinese Journal of Process Engineering

Cover and Contents

The Chinese Journal of Process Engineering. 2023, 23(4): 0.

Asbtract ( )

PDF (4976KB) ( )

Related Articles | Metrics

Research review in regulating interfacial interaction on MOF-based mixed matrix membranes for gas separation

Lili GONG Ju BAI Can WANG Wei LAI Linglong SHAN Shuangjiang LUO Zhichang LIU

The Chinese Journal of Process Engineering. 2023, 23(4): 489-500. DOI: 10.12034/j.issn.1009-606X.223054

Asbtract ( )

HTML ( )

PDF (7406KB) ( )

Related Articles | Metrics

Mixed matrix membranes (MMMs) have attracted substantial attention for gas separation, combining the advantages of organic polymers and inorganic fillers, which are expected to solve the Trade-off effect. Metal organic frameworks (MOF), as a kind of innovative filler, provided promising development opportunities for MMMs, thanks to high surface area and porosity, adjustable pores, and low density, etc. These unique physical and chemical properties promoted the application in gas adsorption, separation, and storage. MOF is regarded as good compatibility with the polymer matrix because the organic linkers in MOF are more similar to the organic chain of the polymer compared with traditional inorganic materials (molecular sieve or metal oxide, etc.). Gas separation performance is improved by incorporating MOF into the polymer matrix, which is expected to balance the Trade-off effect. However, the separation performance of MMMs is not simply the sum of the two phases and is far below the predicted theoretical value by the material simulation in most cases. One of the key reasons for these non-ideal morphologies resulting from poor interfacial compatibility, including the non-selective interfacial voids, polymer rigidified, and pore blockage, which reduce the separation performance of MMMs. Therefore, good interfacial compatibility plays a key role in MMMs. Constructing effective interface interactions is a feasible strategy to improve interface compatibility. Thus, in this review, a comprehensive overview of the main technical challenges in developing MOF-based MMMs and a detailed description of the interface issues are provided. And constructing different interface interactions, including hydrogen bonds, covalent bonds, coordination bonds and others, has been expounded through various methods and strategies in the last five years. Finally, it aims to summarize the positive effects on the properties of MMMs through effective and strong interface interactions, guiding the future development of MOF-based MMMs.

Research progress on molding process of catalysts for fixed bed reactor

Shanshan LIU Qida DING Tao GUO Yaofeng WANG Baohua XU

The Chinese Journal of Process Engineering. 2023, 23(4): 501-511. DOI: 10.12034/j.issn.1009-606X.222088

Asbtract ( )

HTML ( )

PDF (1464KB) ( )

Related Articles | Metrics

The progresses obtained in the catalytic technology are driven by the social demands, such as environment, energy, chemicals, and fuels. The ultimate goal is to increase the process efficiency for scale-up. The molding catalysts are usually multicomponent material of millimetre-size consisting of the active phases, supports, and various molding additives suitable for commercial applications. Different from the powder catalysts, the molding catalysts should not only possess the catalytic activity of the powder catalyst but also consider the use of binder, lubricant, acid and pore-forming agent to satisfy the required mechanical strength and chemical stability to ensure that they can run smoothly and have a long life in industrial reactors. In addition, the shape and size of the molding catalysts affect the catalytic performance by affecting the flow state of the materials inside the reactor. Therefore, the molding process is complex and full of challenges. This review introduces the influence of molding conditions on both the mechanical and the catalytic properties at the fixed bed. Specifically, the effects of the types and amounts of additives, the addition sequence, the calcination conditions, the pulp ratio, and the shape and size of molding catalysts are focused. Weibull modulus can be used to measure the reliability of mechanical strength of brittle materials, and further judge and predict the reliability of catalyst strength value. In addition, this review also introduces the application of Weibull distribution in the reliability judgment and prediction of catalyst strength value, and the progress of computational fluid dynamics (CFD) simulation in assisting catalyst morphology design. The potential of Weibull distribution and CFD in future applications of molding catalyst are pointed out.

Bubble motion characteristics of gas-solid rolling fluidized bed

Xiaolei HAO Meng TANG Ruojin WANG Dewu WANG Shaofeng ZHANG

The Chinese Journal of Process Engineering. 2023, 23(4): 512-522. DOI: 10.12034/j.issn.1009-606X.222163

Asbtract ( )

HTML ( )

PDF (12096KB) ( )

Related Articles | Metrics

In the marine environment, it is necessary to additionally consider the influence law of the swing movement of the bed with the floating platform on the gas-solid flow. From the previous research, there has been a basic understanding of the phenomena such as uneven gas-solid fluidization, gas-solid phase aggregation and separation in the rolling fluidized bed, but there is still a lack of in-depth understanding of the movement and aggregation characteristics of bubbles. The bubble motion characteristics of two-dimensional rolling bed made of transparent plexiglass and Geldart B spherical glass beads are studied in detail based on image analysis and pressure analysis. Through the analysis of the image method, the research results on the spatio-temporal dynamic characteristics of the bubble rising process in the rolling fluidized bed show that when the bed is in the inclined attitude, the bubble rising and aggregation phenomenon is similar to the conventional inclined bed, and the bubble aggregation direction to the wall changes dynamically with the change of the bed attitude. The "hot zone diagram" method is used to analyze the bubble aggregation characteristics in the swing process. It is found that the conversion of bubble aggregation direction obviously "lags behind" the conversion of bed attitude at higher apparent gas velocity. The analysis reason is that the influence of Coriolis force on particles becomes greater at higher gas velocity, which makes particles tend to aggregate in the opposite direction of swing direction, resulting in the delay of gas phase conversion. The analysis results of bubble time averaged characteristics by pressure method show that the swing bed attitude is always "inclined ? vertical" dynamic change, the distribution of bubbles in the bed, the average size of bubbles, and the frequency of bubble generation and rupture are between inclined bed and vertical bed. The influence of operating conditions on the bubble characteristics of rolling bed is studied. The increase of operating gas velocity increases the average bubble size and bubble generation and rupture frequency. The increase of oscillation amplitude increases the frequency of bubble formation and rupture, and has little effect on the average bubble size. The influence of rolling period on both is not obvious.

Optimization design of bioreactor agitator blade based on orthogonal method and Kriging model

Shuxun LI Tingqian MA Yinggang HU Mengyao YU Bincai LIU

The Chinese Journal of Process Engineering. 2023, 23(4): 523-533. DOI: 10.12034/j.issn.1009-606X.222144

Asbtract ( )

HTML ( )

PDF (23933KB) ( )

Related Articles | Metrics

The stirred bioreactor is widely used in cell culture in the biopharmaceutical industry, but there is a lack of research on optimization of agitator blade in bioreactor based on the standard of agitator blade and the actual demand. Aiming at the problems that the design parameters interval in the agitator blade standard is large, the parameters of the bioreactor stirring paddle design are difficult to determine, and the shear force and power consumption lack reference in the design of the agitator blade. The agitator blade of the 200 L bioreactor was preliminarily optimized based on the orthogonal method and CFD, and the effects of different agitator blade diameters, agitator blade width, distance from agitator blade center to bottom, and rotational speed on agitator blade shear rate and agitation power of the tri-oblique blade were obtained by using the method of range analysis. Combined with the velocity dead zone distribution, streamline distribution, and shear force distribution, a design scheme that ensured the effect of cell culture was selected. This scheme was conducive to fluid circulation and could promote the mixing of culture medium and gas-liquid mass transfer. At the same time, the fluid needed sufficient kinetic energy and overall flow velocity. According to the orthogonal optimization scheme, the multi-objective optimization variables interval was determined, and the shear force and power consumption were taken as the optimization objectives. Based on the Kriging model and multi-objective genetic algorithm, the design variables interval of the tri-oblique blade propeller that is beneficial to cell culture was proposed. The optimal parameter combination of the agitator blade with average shear force of 0.789 Pa and power consumption of 0.395 W was obtained, which provided a method and data reference for the design and optimization of the bioreactor under different actual needs.

Effect of different types of feed injection on pressure drop characteristics in riser

Zhihang ZHENG Junnan MA Zihan YAN Chunxi LU

The Chinese Journal of Process Engineering. 2023, 23(4): 534-543. DOI: 10.12034/j.issn.1009-606X.222206

Asbtract ( )

HTML ( )

PDF (1056KB) ( )

Related Articles | Metrics

Riser reactor is the core equipment of the catalytic cracking process. In an industrial riser reactor, the feed oil is usually injected by multiple high-speed nozzles to mix and react with catalyst particles. As an important monitoring data, the pressure drop in riser not only reflects the fluidization state but also determines the energy consumption of the process. However, most studies on the pressure drop in riser do not consider the effect of feed injection. The model to predict the pressure drop in the feed injection zone of riser needs to be improved. In this work, the pressure drop in riser under the effect of different types of feed injection is investigated through large-scale cold mold experiments. The dynamic data of both total pressure drop and pressure drop from different sections in riser are collected. Results under the influence of upward injection and downward injection are compared. Besides, the pressure drop characteristics of each section in the riser are analyzed, and the influence of different operating conditions is analyzed. Generally, both the total pressure drop and the pressure drop from each section of riser are larger when the catalysts contact with feed injection by countercurrent way. For both upward and downward jets, the total pressure drop and the pressure drop of each section in riser decrease with the increase of the pre-lift gas velocity, increase wiht the increase of solid flux. When the jet velocity increases, the total pressure drop and the pressure drop of each section in riser do not change significantly when the catalysts contact with feed injection by cocurrent way. On the contrary, for the countercurrent contact situation, the total pressure drop of riser and the pressure drops in the feed mixing and fully developed sections increase significantly. Combined with the traditional riser pressure drop model and dimensional analysis, pressure drop models for the feed mixing and fully developed sections in riser are established, which can be used as a reference for engineering design.

Combustion characteristics and kinetic analysis of coated quasi-particles in iron ore fines sintering

Tao HAN Changqing HU Chaoqun LU

The Chinese Journal of Process Engineering. 2023, 23(4): 544-553. DOI: 10.12034/j.issn.1009-606X.222135

Asbtract ( )

HTML ( )

PDF (2449KB) ( )

Related Articles | Metrics

Iron ore fines sintering, as the main atmospheric pollution source of blast furnace-converter long process steel production, is facing the pressure and challenge of ultra-low emission under the background of carbon peaking and carbon neutrality. Solid fuel exists in the sintering layer of iron ore fines in various forms, and the mass fraction of the coated quasi-particles (S-type) is as high as 70%. Therefore, the S-type quasi-particles were taken as the research object, the influence of adhesion fines composition on coke combustion were analyzed, and the dynamic rate control link was clarified, which provided a theoretical basis for improving combustion efficiency. The coke particles with 2~3 mm particle size were used as the core particles, and Al2O3, SiO2, CaO, MgO, Fe2O3 pure reagents and synthetic CaO-Fe2O3 (CF) were used to replace iron ore fines as adhesion fines. Then, S-type with different composition adhesion layers were prepared respectively. The non-isothermal combustion test and combustion characteristics were studied by thermogravimetric analysis. The most probable mechanism function of combustion reaction was solved by Coats-Redfern method, and the kinetic physical model was established for kinetic analysis. The results showed that the combustion characteristics of quasi-particles were significantly affected by the composition of adhesive layer. CaO, CF and Fe2O3 had strong catalytic combustion effect. The ignition point and combustion temperature of coke particles were significantly reduced, and the combustion efficiency and conversion rate were improved. The catalytic ability of MgO was weak, and the catalytic ability from high to low was CaO>CF>Fe2O3>MgO. The most probable mechanism function of S-type quasi-particles in the rapid combustion stage was R3, the spherically symmetric unreacted shrinking nuclear model of quasi-particle combustion was established and analyzed. In the rapid combustion stage, the carbon-oxygen interface reaction advanced to the core, and the interface reaction rate was smaller than the internal diffusion rate, which was the control link affecting the combustion rate of quasi-particles.

Study on dissolution process and kinetics of palladium in Ce(NH₄)₂(NO₃)₆ solution

Zhanpeng YAN Minghui LIU Tianyan XUE Ying YU Zhongwei ZHANG Xuan DU Qinggui XIAO Hui ZHANG Tao QI

The Chinese Journal of Process Engineering. 2023, 23(4): 554-561. DOI: 10.12034/j.issn.1009-606X.222090

Asbtract ( )

HTML ( )

PDF (1309KB) ( )

Related Articles | Metrics

As an important strategic reserve metal, palladium (Pd) is widely used in chemical, automotive catalysts, aerospace and electronic products due to its excellent physical and chemical properties. However, due to the lack of mineral resources, it is difficult to meet the needs of social development, so it is of great significance to study the secondary recovery process of Pd to realize the recycling of Pd. In this work, a new leaching system of Ce(NH4)2(NO3)6 was proposed to solve the problems existing in the traditional leaching system. The dissolution behavior of Pd powder in acidic Ce(NH4)2(NO3)6 solution was studied in detail. The results showed that the dissolution of metallic Pd in the mixed system was significantly affected by the adsorption on the Pd surface. In the absence of Cl-, the surface of metallic palladium was passivated by the adsorption of oxygen or NO3- on the surface, which hindered the reaction between Ce4+ and Pd atoms since the dissolution ratio was only 0.2% in 5 h. The addition of Cl- was helpful to destroy the surface passivation layer through competitive adsorption and accelerated the dissolution reaction of Pd. The NO3- and Cl- constituted competitive adsorption, and higher concentrations of nitrate required higher concentrations of Cl- to initiate the dissolution reaction. The effects of different reaction conditions on the dissolution efficiency of Pd powder were investigated. The results showed that the efficiency of the dissolution of Pd powder reached 100% after 1.5 h at the concentration of Ce(NH4)2(NO3)6 of 1 mol/L, HNO3 of 1 mol/L, Cl- of 0.03 mol/L, reaction temperature of 80℃ and stirring speed of 200 r/min, which was the preferences condition of the dissolution of Pd powder. The dissolution kinetics of Pd powder in acidic Ce(NH4)2(NO3)6 solution showed that the dissolution reaction of Pd powder in solution conformed to the shrinking core model controlled by chemical reaction. The apparent activation energy of the dissolution reaction was 58.7 kJ/mol, and the kinetic equation was 1-〖(1-x)〗^(1/3)=2264806e^(-58732/RT) t.

Recovering molybdenum and vanadium from spent hydroprocessing catalyst by air roasting-alkaline leaching process

Yuen LI Bo YU Jianghua LING Cheng ZHANG Jiugang HU Mei LIU

The Chinese Journal of Process Engineering. 2023, 23(4): 562-570. DOI: 10.12034/j.issn.1009-606X.222146

Asbtract ( )

HTML ( )

PDF (2290KB) ( )

Related Articles | Metrics

With the rapid development of oil refining industry, the annual generation of global spent hydroprocessing catalysts is gradually increasing. Spent hydroprocessing catalysts are rich in organic pollutants and metals including molybdenum, vanadium, nickel, and aluminum, which will lead to not only serious deterioration of ecological environment but also waste a great amount of resource. In this study, a process featured by air roasting-alkaline leaching was proposed to treat the spent hydroprocessing catalyst in the purpose of recovering molybdenum and vanadium. Thermogravimetric (TG), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) techniques were employed to characterize the raw spent catalysts, the roasted product and the leaching residues. Air-roasting can make the metal sulfides convert to oxides which were able to be dissolved into leaching solution by sodium carbonate. Thermodynamic analysis showed that the low-temperature leaching can separate molybdenum and vanadium from aluminum and nickel in the spent catalysts. The effects of air roasting temperature, sodium carbonate concentration, reaction time, leaching temperature and liquid to solid ratio on the leaching rate of molybdenum and vanadium were investigated by the single factor experiments. The experimental results showed that the leaching rates of molybdenum and vanadium reached 98.02% and 94.36%, respectively, under the optimum conditions with roasting temperature of 500℃, sodium carbonate concentration of 4 mol/L, leaching temperature of 80℃, reaction time of 90 min and liquid-solid ratio of 20:1. In order to maximize the recovery of molybdenum and vanadium, the two-stage counter current leaching process was adopted subsequently, and the leaching rate of molybdenum and vanadium were able to maintain at 98% and 97%, respectively. The leaching residue mainly contained Al2O3, NiO and NiAl26O40, and most of molybdenum and vanadium transferred into leaching solution. The advantage of this process is that molybdenum and vanadium can be fully recovered and satisfactorily separated from nickel and aluminum with the mild leaching conditions, which is benefit for the following treatment of leaching residues.

Preparation and properties of piperazine pyrophosphate based flame retardant rigid polyurethane foam

Mengru LIU Fulin HUANG Junjie SUN Xiuyu LIU Qingming ZHU Gang TANG

The Chinese Journal of Process Engineering. 2023, 23(4): 571-579. DOI: 10.12034/j.issn.1009-606X.222160

Asbtract ( )

HTML ( )

PDF (2204KB) ( )

Related Articles | Metrics

The energy crisis has led to the development of building materials in the direction of high quality. Rigid polyurethane foam (RPUF) is an insulation material with many excellent performances. However, the rigid polyurethane foam has the defect of being extremely easy to be ignited, and there is a potential safety hazard in the actual use, so it needs to be treated with flame retardant. Piperazine pyrophosphate (PAPP) is a flame retardant that contains both phosphorus and nitrogen flame retardant elements, and it can be added to the RPUF system which can solve the problem of being weak in flame retardancy of RPUF. The limiting oxygen index (LOI), thermogravimetric (TG), and cone calorimetry (CCT) have been used to investigate the flame retardant properties and combustion performance of PPAP/RPUF composites. Scanning electron microscopy (SEM) demonstrated the microscopic vesicle structure of RPUF, and the results showed that the addition of PAPP increased the inhomogeneity and breakage of the vesicle structure. The flame retardant test indicated that the addition of PAPP could effectively inhibit the dripping of the composite, with the highest LOI value of the composite material at 22.7vol% and passing the UL-94 test at V-0 level with the addition of 50wt% PAPP. TG test conducted that the decomposition of PAPP was divided into three stages, and the decomposition rate of its second stage was the largest. The acid substances produced by the decomposition of PPAP made RPUF matrix have a higher char residue rate, in which the char residue of PAPP50/RPUF increased to 34.4wt% at 700℃, and the char residue plays a role in blocking heat and releasing combustible gas in the condensed phase. CCT test confirmed that PAPP could inhibit the release of the heat of combustion from the composite material, and the peak heat release rate (PHRR) and total heat release (THR) generated by PAPP50/RPUF combustion were 54% and 41% lower than those of pure sample. The mechanical properties test demonstrated that the addition of PAPP increased the thermal conductivity and reduced the compressive strength of the PPAP/RPUF composites.

Wolframite was applied to photocatalytic degradation of oxytetracycline

Jianfei SHEN Dong CHEN Tianhu CHEN Haibo LIU Xuehua ZOU Hanlin WANG Can WANG Luyao WANG

The Chinese Journal of Process Engineering. 2023, 23(4): 580-589. DOI: 10.12034/j.issn.1009-606X.222050

Asbtract ( )

HTML ( )

PDF (3852KB) ( )

Related Articles | Metrics

Oxytetracycline is widely used in animal husbandry and aquaculture because it can effectively inactivate Gram-positive and Gram-negative bacteria. However, 50%~80% of oxytetracycline is not fully absorbed and utilized, and enters the environmental units such as surface water, groundwater, and soil through sewage discharge, surface runoff, and landfill leachate in the form of livestock parent or metabolite. Therefore, it is urgent to take fast and efficient means to deal with oxytetracycline pollution. Photocatalytic technology is widely used in organic compounds due to its low energy consumption, high removal rate, low cost, and ability to convert organic pollutants into harmless small molecular organic compounds. Among the existing photocatalysts, tungstate photocatalysts stand out due to their wide absorption wavelength range, narrow band gap, and high stability. The natural semiconductor mineral wolframite was used as a photocatalyst for the degradation of oxytetracycline in wastewater. The effects of solid-liquid ratio, light intensity, and initial concentration on the degradation of oxytetracycline were investigated while the degradation mechanism and pathway were analyzed. The results showed that wolframite had a promising degradation effect on oxytetracycline under visible light, and the removal efficiency of oxytetracycline could reach 94.3% at 120 min under the conditions of concentration of 15 mg/L, pH=4.5, the solid-liquid ratio of 1.0 g/L and light intensity of 60 W; The degradation of oxytetracycline by wolframite is in accordance with the primary kinetic reaction law. The results of the quenching experiment and electron paramagnetic spectroscopy showed that hydroxyl radical (?OH) and superoxide anion radical (?O2-) were the main active oxidizing species causing oxytetracycline degradation, which degraded 20.4% and 10% oxytetracycline at 120 min, respectively. The results of liquid chromatography-mass spectrometry showed that oxytetracycline was degraded into intermediates through hydroxylation, demethylation, and decarbonylation, which was beneficial to the industrial application of wolframite in antibiotic treatment.

Preparation and adsorption properties of CCS-DETA hydrogel beads for methyl orange

Huiqing YIN Shaojie WU Mingyang LI Hongming LONG Songyue WANG Zhixin QIU Xiangpeng GAO

The Chinese Journal of Process Engineering. 2023, 23(4): 590-601. DOI: 10.12034/j.issn.1009-606X.222124

Asbtract ( )

HTML ( )

PDF (5279KB) ( )

Related Articles | Metrics

Chitosan is a polymer obtained by deacetylation of the natural polysaccharide chitin. It has various physiological functions such as biodegradability, biocompatibility, and non-toxicity. The hydroxyl and amino groups in their molecules can form active interfaces to adsorb dye molecules. However, direct application is limited due to its weak mechanical strength and chemical stability, thus requiring chemical modification. In this work, chitosan hydrogel beads (CCS-DETA) were prepared by sol-gel method using chitosan (CS) as matrix, glutaraldehyde (GA) as crosslinking agent, and diethylenetriamine (DETA) as modifier. The adsorption performance of CCS-DETA hydrogel beads on methyl orange (MO) dye in wastewater was studied. Effects of pH value, initial concentration, adsorption isotherm, and kinetics were discussed with mathematical model fitting results. The microstructure and adsorption mechanism of CCS-DETA hydrogel beads were characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), and X-ray photoelectron spectroscopy (XPS). The results showed that CCS-DETA was protonated under low pH values that electrostatically interacted with negatively charged MO molecules in the adsorption process. It was showed that CCS-DETA was protonated at low pH and electrostatically interacted with negatively charged MO molecules during the adsorption process. Furthermore, at higher pH, O and N ions on MO can form hydrogen bonds with hydroxyl groups on CCS-DETA. The adsorption results showed that CCS-DETA hydrogel beads had excellent adsorption effect on MO. When the dosage of CCS-DETA hydrogel beads was 30 mg, the initial concentration of MO was 20 mg/L, pH was 2, and the reaction time was 12 h, the MO removal rate could reach 91.33%, and CCS-DETA hydrogel beads had exhibited good stability. The adsorption kinetics and thermodynamics showed that the adsorption process was more consistent with the pseudo-first-order kinetics model and Langmuir isothermal adsorption model. The maximum adsorption capacity of MO reached 209.68 mg/g at 313.15 K. This study suggested that CCS-DETA can efficiently adsorb MO from aqueous solutions via amino and hydroxyl groups.

Effect of cationic properties of ionic liquids on the performance of platinum-based oxygen reduction electrocatalysts

Shuo BAI Hao WANG Guangwen XU Bingbing YANG Zhenye KANG Jiayao CUI Chenhao LI Qingjun CHEN Yanrong LIU

The Chinese Journal of Process Engineering. 2023, 23(4): 602-615. DOI: 10.12034/j.issn.1009-606X.222142

Asbtract ( )

HTML ( )

PDF (26451KB) ( )

Related Articles | Metrics

Ionic liquids (ILs) modified solid catalysts are considered to be an effective method for constructing efficient electrocatalytic interface. In order to investigate the cationic impacts of ILs on Pt surface towards the oxygen reduction reaction (ORR) performance, herein we selected and synthesized [NTf2]- based two hydrophobic protonic ILs ([EIM][NTf2], [BIM][NTf2]) and two hydrophobic non-protonic ILs ([EMIM][NTf2], [BMIM][NTf2]), and the synthesized ILs were used to modify the commercial Pt/C catalyst surface. Among the imidazolium-based hydrophobic ILs used in this study, the ORR activities of the protonic ILs modified catalysts were all higher than those of the non-protonic ILs modified catalysts, with the catalyst modified by 1-butylimidazolium bis(trifluoromethanesulfonyl)imide ([BIM][NTf2]@Pt/C) having the highest activity. The ORR half-wave potential in the acidic half-cell is as high as 0.913 V (vs. RHE), increasing the mass activity to 1.73 times than that of commercial Pt/C and the specific activity to 3 times than that of commercial Pt/C, while reaching a half-wave potential drop of only 12 mV after 5000 cycles, the performance is still higher than that of commercial Pt/C. Further material characterization and electrochemical tests were performed on the catalysts showed that the enhanced electrocatalytic activity of [BIM][NTf2]@Pt/C was attributed to the increased number of active sites on the Pt surface from the ILs modification, which enhanced plasmon and mass transfer on the Pt surface, and effective inhibition of Pt nanoparticle solubilization, thus enhancing the ORR activity and stability. This study deepens the understanding of the synergistic electrocatalytic mechanism at the ILs@Pt interface and provides a theoretical basis for the design of next-generation high-efficiency fuel cell catalysts.

Autothermal operation and parametric analysis of commercial demonstration unit of 3 MWth coal chemical looping gasification

Pengxing YUAN Qingjie GUO Xiude HU Jingjing MA Xintong GUO

The Chinese Journal of Process Engineering. 2023, 23(4): 616-626. DOI: 10.12034/j.issn.1009-606X.222154

Asbtract ( )

HTML ( )

PDF (1121KB) ( )

Related Articles | Metrics

Chemical looping gasification technology is an effective way to realize the efficient and clean conversion of solid fuel. The autothermal operation of MWth scale chemical looping gasification is an important basis for the commercial application of this technology. Aspen Plus is used for simulation research in order to realize the autothermal operation of the chemical looping gasification demonstration unit. The reliability of the process model is verified by experimental data. The mass and heat balance of the 3 MWth coal chemical looping gasification system is solved. By analyzing the effects of reactor temperature, steam flow rate and temperature, cyclone separator efficiency, oxygen carrier active component content, and other process parameters on syngas yield, syngas component concentration, syngas H2/CO, solid circulation flow rate, and other process performance of the system, the autothermal operating conditions for maximum syngas production are determined. The results show that the net heat power of a 3 MWth coal chemical looping gasification system is close to 0, and the system tends to autothermal operation. The optimum operating conditions are fuel reactor (FR) temperature of 850℃, air reactor (AR) temperature of 950℃, steam flow rate of 305.25 kg/h, steam temperature of 300℃, and cyclone efficiency of 98%. At the same time, the solid circulation flow rate of the system is the smallest, which is about 10 555~10 580 kg/h. The total concentration of syngas (CO+H2) is the largest, which is about 75.1%. In addition, the use of ilmenite particles with higher content of active components as oxygen carriers is beneficial to reduce the solid circulation flow rate of the system.

Fault diagnosis based on Bayesian network driven by parameter residuals for chiller

Boyang LIANG Jingjing GUO Zhanwei WANG Lin WANG Yingying TAN Xiuzhen LI Sai ZHOU

The Chinese Journal of Process Engineering. 2023, 23(4): 627-636. DOI: 10.12034/j.issn.1009-606X.222178

Asbtract ( )

HTML ( )

PDF (3467KB) ( )

Related Articles | Metrics

Chillers, as a major consumer, account for about 40% of the total building energy consumption. However, the failure of chillers will lead to additional energy waste accounting for 15%~30% of building energy consumption. Therefore, applying fault diagnosis technology to chiller plays an important role in reducing energy consumption and improving operation efficiency. On the other hand, considering that the residuals of parameters involve more information reflecting faults, a fault diagnosis method based on parameter residual-driven Bayesian Network (BN) is proposed by combining parameter residuals with BN for chiller, in order to furtherly improve the fault diagnosis performance. Being different from most of the conventional methods directly using the parameter measurement values to train the models, the proposed method uses the residuals, calculated through the actual values and reference values of parameters to train the BN model, thus to make full use of the fault information contained in parameter residuals. To evaluate comprehensively the effectiveness of parameter residuals referring to enhance the diagnostic performance, three models used to determine the reference values are developed and compared. Two are linear analysis methods, i.e., multivariate linear regression (MLR) and partial least squares regression (PLSR), and the other is a nonlinear analysis method, i.e., back-propagation neural network (BPNN). Finally, the proposed method based on parameter residual-driven BN is applied to a real experimental chiller, and the experimental data are used to verify its effectiveness. The results show that: (1) Compared with the diagnosis model driven by parameter measurement values directly, the proposed method has higher diagnosis accuracies for the considered seven common faults of chiller, and the diagnosis accuracy is increased by 22.51 percentage point at most; (2) Compared with the reference model based on MLR and PLSR, the diagnosis performance is better when the BPNN model is used to determine the reference value, and the diagnosis accuracy is increased by 12.35 and 12.05 percentage point at most, respectively; (3) The proposed method can effectively improve the diagnostic performance, especially for these faults at slight severity level.

Application of regeneration recycling water networks design in thermal power plant

Jun LIU Baodeng HOU Lihua CHEN Weihua XIAO

The Chinese Journal of Process Engineering. 2023, 23(4): 637-648. DOI: 10.12034/j.issn.1009-606X.222110

Asbtract ( )

HTML ( )

PDF (1594KB) ( )

Related Articles | Metrics

In order to resolve the problems existing in the application of the water networks integration optimization method in the thermal power plant, the transfer process of mass impurities from water regeneration units was expanded in this study. The complete mass transfer process was used to describe the process of water utilization of impurity load units, and the maximum mass transfer capacity and rate of regeneration are used to describe the processes of regeneration. In addition, a directed graph was used to describe the connections between units of water networks. Through analyzing the relationship between the maximum concentration, impurity load, and water supply process of water units, the mathematical mechanism of the optimization process was obtained so as to build a regeneration recycling water networks optimization model. A 3300 MW thermal power plant was chosen to conduct model application research. The water networks of the case power plant was divided into 9 water subsystems, and equivalently divided into 11 water units, then a concentration correction model had been constructed for the regeneration unit to achieve the maximum mass removal process. The chloride ion, entire solids of suspended matter, and sulfate ion were picked to perform a water-saving optimization design, and the model was simplified by solving the KKT conditions of the optimization problem. After optimization, the use of fresh water of the water networks was reduced by 6.7%, total emissions of sewage were reduced by 62.9%. The case study showed that the constructed regeneration recycling water networks model based on the "supply-utilization-consumption-discharge" process of water networks was successful, and it could realize the water-saving optimization design of the water networks in thermal power plants considering multiple impurities. Furthermore, it resolved the issues of inaccuracy in the description of the regeneration process in the use of the integrated optimization method of water networks in thermal power plants, as well as the inappropriate description of the water regeneration unit for water-saving reconstruction of water networks.

Table of Content