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Optimization of waste heat recovery power generation system for cement plant by combining pinch and energy analysis methods

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APPLIED THERMAL engineering 2018年 140卷 334-340页

作者： Han, Tao Wang, Chang'an Zhu, Chenzhao Che, Defu Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Waste heat recovery power generation system (WHRPGS) plays a significant role in cement plants for its contribution to the electricity supplement. Optimization of WHRPGS is very challenging when the WHRPGS is coupled with the cement producing system (CPS). In this paper, a new simplified model was proposed to characterize the integrated system (involving WHRPGS and CPS). By combining pinch analysis and energy analysis methods, the energy process of the integrated system was studied in details. In particular, pinch analysis was used to qualitatively evaluate the improvement potentiality of the integrated system, while energy analysis was employed to quantitatively evaluate the power generation capacity of the WHRPGS. By reducing the heat transfer across pinch points and energy destruction of the integrated system, an optimized mode of WHRPGS was identified and the power generation capacity of it can be increased by 7.559% theoretically. The optimized WHRPGS was applied in a 2500 t.d(-1) clinker production line in Northwest China. Comparing the operational results of WHRPGS in original and optimized modes for 24 h respectively, the power generation capacity of the optimized system was increased by 4.96% on average.

关键词： Waste heat recovery Model Pinch analysis Energy analysis Cement plant power generation

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Smart formaldehyde detection enabled by metal organic framework-derived doped electrospun hollow nanofibers

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SENSORS AND ACTUATORS B-CHEMICAL 2021年 326卷 128819-128819页

作者： Zhu, Lei Wang, Jianan Liu, Jianwei Nasir, Muhammad Salman Zhu, Jinwei Li, Shanshan Liang, Jidong Yan, Wei Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Dept Environm Sci & Engn 28 Xianning West Rd Xian 710049 Peoples R China Weinan Normal Univ Sch Phys & Elect Engn Chaoyang St Weinan 714099 Peoples R China Univ Agr Faisalabad Dept Struct & Environm Engn Faisalabad 38040 Pakistan Shaanxi Elect Equipment Inst Xian 710025 Peoples R China

In this work, the metal-organic framework (MOF)-derived Zn2+ doped SnO2 (ZZS) hollow nanofibers (HNFs) have been successfully synthesized via facile electrospinning and annealing techniques for achieving the low concentration of HCHO monitoring. As the hollow nanostructure and the optimized Zn(2+ )homogeneous doping behavior ensure all the smooth electrons transfer, abundant chemisorbed active sites and oxygen vacancies, the 15 wt% ZZS HNFs exhibited the excellent gas-sensing property with a sensing response value of 25.7 towards 100 ppm HCHO, fast response/recovery time (12 /45 s) and the detection capacity of HCHO down to 500 ppb in a rapid response/recovery time (10/2 s) compared with pristine SnO2 and other ZZS HNFs. Moreover, when assembled into a practical smart detection device for real-time monitoring and early warning of HCHO, the 15 wt % ZZS HNFs still presented high sensitivity of HCHO, highlighting its bright commercial prospect in the future of smart indoor air quality monitoring.

关键词： Gas sensor Formaldehyde Doping Hollow nanofibers Metal-organic framework

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Development of a turbulence scale controllable burner and turbulent flame structure analysis

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EXPERIMENTAL THERMAL AND FLUID SCIENCE 2019年 109卷 109898-000页

作者： Wang, Jinhua Yu, Qianqian Zhang, Weijie Zhang, Meng Huang, Zuohua Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

A turbulence controllable premixed turbulent Bunsen burner was developed to study the separate effects of turbulence intensity and integral scale on the premixed turbulent flame. Circular and slot perforated plates with adjustable plate positions were designed to produce quasi-isotropic and uniform turbulence field containing scale-expanded vortices with normalized turbulence intensity ranging from 5% to 40%. The method to attain the controlled turbulence with multi-layer perforated plates were discussed. Especially, the order of the plate and the distance between the plates were proposed to be vital. Eight burner configurations of the plates and twelve conditions of the CH4/air flames at two constant bulk velocities (corresponding to two Reynolds numbers 4000 and 6777) were adopted. The flame front structure of the flames was captured with OH-PLIF technique. Results show that under the same turbulence intensity, the increase of integral scale at the higher Reynolds number reduces the turbulent burning velocity and increases the flame volume, while at the lower Reynolds number it shows marginal effect. Turbulent burning velocity and flame volume both increase almost monotonously, but the flame brush thickness decreases with the increase of turbulence intensity. With both two Reynolds numbers, small integral scale leads to decreased brush thickness. Both strong turbulence intensity and small integral scale decrease the curvature radius to induce finer flame front, which should be the main reason of the increased turbulent burning velocity. However, the flame surface density seems to be ambiguously correlated with the turbulence intensity and integral scale. The turbulence intensity shows more direct and intensive effects on the flames compared to the integral scale according to the PDF distributions of the curvature radius. The present study is useful for the interpretation of the basic mechanism of turbulence intensity and integral scale as well as the evaluation of

关键词： Premixed turbulent burner Turbulence control Turbulence intensity Integral scale Turbulent burning velocity Flame front structure

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Enhanced photocatalytic hydrogen evolution by partially replaced corner-site C atom with P in g-C3N4

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APPLIED CATALYSIS B-ENVIRONMENTAL 2019年 244卷 486-493页

作者： Wang, Bin Cai, Hairui Zhao, Daming Song, Miao Guo, Penghui Shen, Shaohua Li, Dongsheng Yang, Shengchun Xi An Jiao Tong Univ Sch Sci State Key Lab Mech Behav Mat MOEKey Lab Nonequilibrium Synth & Modulat Condes Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Int Res Ctr Renewable Energy State Key Lab Multiphase Flow Power Engn MFPE 28 West Xianning Rd Xian 710049 Shaanxi Peoples R China Pacific Northwest Natl Lab Phys & Computat Sci Directorate Richland WA 99352 USA

Modifying the structure of photocatalyst to tune its electronic and physicochemical properties is an effective approach for efficient photocatalysis. Herein, we modify the structure of g-C3N4 by partially replacing the corner site C atom with P heteroatom via a simple thermal phosphorization method. Comparing with the pristine g-C3N4, the g-C3N4 after phosphorization shows an improved photocatalytic hydrogen activity, which is attributed to the narrowed bandgap and the upshifted conduction band edge, enhanced separation and transfer of photogenerated charges, and highly hydrophilic surface absorbing reactant molecule for photocatalysis. Various experimental characterizations are conducted to systemically explore the underlying essential mechanism behind the superior photocatalytic performance of g-C3N4 with phosphorization treatment. This work provides a simple approach to modifying the structure of g-C3N4, which could be applied to other semiconductors for designing photocatalyst with unique structure and enhanced activity.

关键词： g-C3N4 Surface phosphorization Photocatalysis Hydrogen evolution Solar energy

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Characteristics of hydrogen production from steam gasification of plant-originated lignocellulosic biomass and its prospects in Vietnam

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2022年第7期47卷 4394-4425页

作者： Anh Tuan Hoang Huang, ZuoHua Nizetic, Sandro Pandey, Ashok Xuan Phuong Nguyen Luque, Rafael Ong, Hwai Chyuan Said, Zafar Tri Hieu Le Van Viet Pham HUTECH Univ Inst Engn Ho Chi Minh City Vietnam Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Univ Split FESB Rudjera Boskov 32 Split 21000 Croatia CSIR Indian Inst Toxicol Res Ctr Innovat & Translat Res Lucknow 226001 Uttar Pradesh India Ctr Energy & Environm Sustainabil Lucknow 226029 Uttar Pradesh India Ho Chi Minh City Univ Transport PATET Res Grp Ho Chi Minh City Vietnam Univ Cordoba Dept Quim Organ Campus RabanalesEdificio Marie Curie E-14014 Cordoba Spain RUDN Univ Peoples Friendship Univ Russia 6 Miklukho Maklaya Str Moscow 117198 Russia Natl Yunlin Univ Sci & Technol Future Technol Res Ctr 123 Univ RdSect 3 Touliu 64002 Yunlin Taiwan Univ Sharjah Dept Sustainable & Renewable Energy Engn POB 27272 Sharjah U Arab Emirates Natl Univ Sci & Technol NUST US Pakistan Ctr Adv Studies Energy USPCAS E Islamabad Pakistan

Demands for the decline of CO2 emissions resulted in a significant transformation of the energy systems working on carbon sources towards more sustainable, clean, and renewable characteristics. Hydrogen is emerging as a secondary energy vector with everincreasing importance in the decarbonisation progress. Indeed, hydrogen, a green and renewable energy source, could be produced from steam gasification of plant-originated lignocellulosic biomass. In this current review, key factors affect the hydrogen production yield from steam gasification of plant-originated lignocellulosic biomass, including the design of the gasifier, temperature, pressure, and steam-to-biomass ratio, steam flow rate, moisture and particle size of fed biomass, and catalysts were thoroughly analysed. Moreover, the effects of the abovementioned factors on the reduction of tar formation, which is also a key parameter towards ensuring the trouble-free operation of the reactor, were critically evaluated. More importantly, the separation of produced hydrogen from steam gasification of biomass and challenges over technological, environmental, and economic aspects of biomass gasification were also presented in detail. In addition, this paper is also profiling the prospect of Vietnam in fulfilling its hydrogen economy potential because Vietnam has vast biomass due to its tropical weather and availability of arable land, providing abundant lignocellulosic biomass with 45% of agricultural waste, 30% of firewood, and 25% of other sources. Besides, some primary factors hindering the broad application of biomass for hydrogen production were indicated. Finally, some solutions for implementing the hydrogenization strategy in Vietnam have also been discussed. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Biomass Hydrogen production Steam gasification Affecting factors Techno-economic challenges Vietnam

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Exergy analysis of the regulating measures of operational flexibility in supercritical coal-fired power plants during transient processes

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APPLIED ENERGY 2019年 253卷 113487-000页

作者： Zhao, Yongliang Liu, Ming Wang, Chaoyang Wang, Zhu Chong, Daotong Yan, Junjie Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Operational flexibility improvement of coal-fired power plants has become a priority objective with the high penetration of renewable energy sources. The regulating measures applied frequently in improving the operational flexibility indeed affect the exergy efficiency of coal-fired power units during transient processes. In this study, the exergy efficiency evaluation of operational flexibility measures during primary frequency control processes was focused on, and the exergy analysis methods of the thermal system were used on the basis of the second law of thermodynamics to analyze the mechanisms for improving the flexibility at four regulation measures, and the exergy storage conversion efficiency and exergy destruction accumulation were quantitatively compared. It turns out that: among the throttling extraction steam of high-pressure heaters, feedwater bypass of high-pressure heaters, and condensate water decrease of low-pressure heaters measures, the exergy storage conversion efficiency and the exergy destruction accumulation increase with the regulating time of primary frequency control. The measure of throttling extraction steam of high-pressure heaters is the most potential option for improving operational flexibility, with maximum value of the maximal output power increment and maximal exergy storage change rate of 71.11MW and -89.84 MW, respectively. With respect to the economy, the measure of throttling extraction steam of low-pressure heaters is the best option due to its smallest exergy destruction accumulation among all the measures. This study provides a detailed guidance for the selection of the optimal regulating measures when considering the enhancement of exergy efficiency and flexibility comprehensively under different conditions and periods.

关键词： Exergy analysis Operational flexibility Dynamic simulation Coal-fired power plant

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Gasification of unsymmetrical dimethylhydrazine in supercritical water: Reaction pathway and kinetics

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2018年第18期43卷 8644-8654页

作者： Yi, Lei Guo, Liejin Jin, Hui Kou, Jiajing Zhang, Deming Wang, Runyu Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn SKLMF Xian 710049 Shaanxi Peoples R China

Unsymmetrical dimethylhydrazine (UDMH) is a high N-containing (as much as nearly 50%) substance. Traditional treatment methods such as incineration will inevitably cause the formation of nitric oxide and secondary pollution. Supercritical water is a preferred transformation medium due to its unique physicochemical properties. However, at present most of studies are limited to supercritical water oxidation (SCWO) which tends to produce hydrogen nitrate resulting in corrosion to the reactor. To conquer this problem, we propose supercritical water gasification (SCWG) technology which is in a reducing environment, realizing both harmless treatment and resource utilization. In order to promote its industrialization process, the reaction pathways and kinetic parameters should be studied. In this paper, the reaction pathways and kinetics of UDMH in supercritical water were conducted under the conditions of 400 C-degrees-550 C-degrees in quartz reactor, which avoids the catalytic effect on the reaction kinetics. From the resource utilization perspective, the most abundant quantitatively detectable gaseous product is methane, together with less hydrogen, carbon monoxide and ethane orderly. All these gaseous products are combustible. The maximum of carbon efficiency is 90.25% at 550 C-degrees, 10 min. In the point of view of harmless treatment, the organic compounds contained in the residual liquid are detected with H-1 NMR, FTIR and GC/MS. Results show that UDMH could be fully degraded within 3 min and the ultimate organic compounds in the residual liquid are mainly dimethylamino acetonitrile and trimethylamine. In addition, a reaction pathway for UDMH disposed in supercritical water is developed. Finally, the quantitative kinetic model for describing the gaseous products and ammonia-nitrogen in the residual liquid is brought forward. The pyrolysis activation energy for UDMH in supercritical water is 49.98 +/- 7.38 kJ/mol. (C) 2018 Hydrogen Energy Publications LLC. Published

关键词： UDMH SCWG Resource utilization Harmless treatment Reaction pathway Kinetics

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Flocculation of suspended cohesive particles in homogeneous isotropic turbulence

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JOURNAL OF FLUID MECHANICS 2021年 921卷 A17-A17页

作者： Zhao, K. Pomes, F. Vowinckel, B. Hsu, T. -J. Bai, B. Meiburg, E. UC Santa Barbara Dept Mech Engn Santa Barbara CA 93106 USA Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Tech Univ Carolo Wilhelmina Braunschweig Leichtweiss Inst Hydraul Engn & Water Resources D-38106 Braunschweig Germany Univ Delaware Ctr Appl Coastal Res Dept Civil & Environm Engn Newark DE 19716 USA

We investigate the dynamics of cohesive particles in homogeneous isotropic turbulence, based on one-way coupled simulations that include Stokes drag, lubrication, cohesive and direct contact forces. We observe a transient flocculation phase, followed by a statistically steady equilibrium phase. We analyse the temporal evolution of floc size and shape due to aggregation, breakage and deformation. Larger turbulent shear and weaker cohesive forces yield smaller elongated flocs. Flocculation proceeds most rapidly when the fluid and particle time scales are balanced and a suitably defined Stokes number is . During the transient stage, cohesive forces of intermediate strength produce flocs of the largest size, as they are strong enough to cause aggregation, but not so strong as to pull the floc into a compact shape. Small Stokes numbers and weak turbulence delay the onset of the equilibrium stage. During equilibrium, stronger cohesive forces yield flocs of larger size. The equilibrium floc size distribution exhibits a preferred size that depends on the cohesive number. We observe that flocs are generally elongated by turbulent stresses before breakage. Flocs of size close to the Kolmogorov length scale preferentially align themselves with the intermediate strain direction and the vorticity vector. Flocs of smaller size tend to align themselves with the extensional strain direction. More generally, flocs are aligned with the strongest Lagrangian stretching direction. The Kolmogorov scale is seen to limit floc growth. We propose a new flocculation model with a variable fractal dimension that predicts the temporal evolution of the floc size and shape.

关键词： suspensions sediment transport cohesive sediments

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Analysis on the behavior of dispersed plate-type fuel based on fluid-solid coupling method

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PROGRESS IN NUCLEAR ENERGY 2020年 126卷 103398-103398页

作者： Li, Chenxi Wu, Yingwei Wang, Yangyang Wang, Kunpeng Wang, Mingjun Tian, Wenxi Su, G. H. Qiu, Suizheng Xi An Jiao Tong Univ Sch Nucl Sci & Technol Shanxi Key Lab Adv Nucl Energy & Technol State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Minist Ecol & Environm Peoples Republ China Nucl & Radiat Safety Ctr Beijing 100082 Peoples R China

In this study, a three-dimensional bi-directional fluid-solid coupling method FLUENT-ABAQUS-MpCCI was used to analyze the behavior of the fuel plate. ABAQUS was used to simulate the solid domain, including the heat conduction, mechanical behavior and irradiation effects. Several subroutines were developed and validated, including CREEP, UHARD, USDFLD and UEXPAN. FLUENT was used to simulate the fluid domain, including pressure and temperature. FLUENT and ABAQUS were coupled by MpCCI to consider the interaction between fluid domain and solid domain. Many parameters were obtained, including fluid temperature distribution, Mises stress distribution and strain distribution. The influences of the fluid domain, particle volume fraction, creep behavior and burnup were analyzed. The results showed that the zero-dimensional model or one-dimensional model on fluid could not accurately simulate the mechanical behavior of the fuel plate. The results also showed that the creep behavior could reduce the Mises stress on the cladding.

关键词： Fluid-solid coupling analysis Irradiation effects Fuel behavior analysis

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Reactivity of Ni, Cr and Zr doped ceria in CO₂ splitting for CO production via two-step thermochemical cycle

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2018年第30期43卷 13754-13763页

作者： Zhu, Liya Lu, Youjun Li, Feng Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn SKLMF Xian 710049 Shaanxi Peoples R China

This work focuses on modification and screening of ceria-based oxides for solar H2O/CO2 splitting via two-step thermochemical cycle. Ce1-xMxO2-delta (M = Zr, Ni, Cr;x = 0, 0.05, 0.10, 0.15, 0.20) were synthesized via sol-gel method and tested for CO2-splitting via two-step thermochemical cycles. Reduction was conducted at 1500 degrees C through a ramp rate of 10 degrees C/min and oxidation was performed at 1000 degrees C isothermally. Both Ni and Cr showed low solubility in ceria and no or very limited promoting effect on CO productivity. Cr could be reduced in the first reduction step but cannot be oxidized by CO2 in the following oxidation step. Zr doped sample showed advantages in both CO productivity and lattice stability. 15% Zr doped exhibited the best performance with the CO productivity of 315.40 mu mol/g. However, the oxidation rate of Zr doped samples was much lower than that of pure ceria. Compromise between fuel productivity and fast kinetics should be made in practical application. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： CO2 splitting Thermochemical cycle Solar energy Ceria-based oxides

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