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DYNAMIC SIMULATION STUDY ON A COAL-FIRED power PLANT AIDED WITH LOW-TEMPERATURE SOLAR ENERGY

ASME power Conference 2019

作者： Li, Xin Zhao, Yongliang Liu, Ming Yan, Junjie Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

ISBN: (纸本)9780791859100

The concept of coal-fired power generation aided with solar energy uses stable fossil energy to compensate the instability and intermittently of solar power and reduces the cost of concentrated solar power (CSP) by decreasing the large-scale heat storage and turbine systems of CSP. In this study, trough solar collector system (TSCS) was integrated into the low-pressure heater side of a 660 MW coal-fired power generation system. In the system in which the 6# LP heater is completely replaced by TSCS, the variation value of the steam extraction flow rate of the LP heaters and the turbine output power decrease with the reduction in loads from 100% to 60% THA, and the output power increases by approximately 1 MW under 100% THA. When TSCS completely replaces the 6# LP heater under the load of 75%, the effects of direct normal irradiance (DNI) increase and flow ratio decrease on the main operating parameters of solar-aided coal-fired power plant (SCPP) were studied. Results show that the step increase of DNI decreases the 5# steam extraction flowrate and increases the output power by nearly 3 MW. When the flow ratio decreases by 139.87 kg/s, the output power decreases by around 0.35 MW The dynamic characteristics of SCPP under different parallel situations with the load of 75% were also studied As the number of parallel stage increases, the decrement in 5# steam extraction flowrate and the increment in output power decrease. The response time also decreases. Our study aims to provide detailed references for the control system design and optimization of coal-fired power units aided with solar energy.

关键词： Solar-aided coal-fired power plant Dynamic simulation Low-temperature solar energy Trough solar collector

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Novel all-solid-state Z-scheme SnO2/Pt/In2O3 photocatalyst with boosted photocatalytic performance on water splitting and 2,4-dichlorophenol degradation under visible light

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CHEMICAL engineering JOURNAL 2020年 390卷 124518-000页

作者： Sun, Yukun Zhu, Qi Bai, Bo Li, Yuliang He, Chi Changan Univ Sch Water & Environm Key Lab Subsurface Hydrol & Ecol Effects Arid Reg Minist Educ Xian 710064 Peoples R China Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Chinese Acad Sci Northwest Inst Plateau Biol Key Lab Tibetan Med Res Xining 810008 Peoples R China Qinghai Prov Key Lab Tibetan Med Res Xining 810001 Peoples R China Univ Chinese Acad Sci Natl Engn Lab VOCs Pollut Control Mat & Technol Beijing 101408 Peoples R China

Fabricating Z-scheme photocatalytic system is of great significance for water splitting and degradation of organic pollutants. However, it is highly challenging to select suitable materials to form Z-scheme photocatalysis systems due to the harsh requirement for band edge levels alignment and interfacial contact. In this work, a novel all-solid-state Pt-bridge SnO2/Pt/In2O3 Z-scheme photocatalyst was prepared by an ingenious in situ deposition and photo-reduction protocol. The physicochemical properties of prepared materials were characterized via SEM, TEM, BET, DRS, PL, and EIS. It is revealed that the visible light absorption capacity of prepared composites was remarkably enhanced due to the localized surface plasma resonance effect of Pt nanoparticles. Moreover, such Pt nanoparticles act as the electron mediator of photogenerated carriers, and the photogenerated electron hole pairs of SnO2/Pt/In2O3 Z-scheme photocatalysts can be effectively separated, which hence reserving the most favorable reductive and oxidative reaction sites. The photocatalytic degradation efficiency of 2,4-dichlorophenol (50 mg L-1) over SnO2/Pt/In2O3 under visible light reaches 90% in 180 min, and the optimal photocatalytic H-2 generation rate reaches 967.018 mu mol h(-1) g(-1), respectively more than 9.36 and 19.40 times higher than that of pure In2O3 (103.358 mu mol h(-1) g(-1)) and SnO2 (49.847 mu mol h(-1) g(-1)). In addition, the stability experiments showed that the H-2 generation rate of the SnO2/Pt/In2O3 Z-scheme photocatalyst after five cycles has only decreased by 8.96%. This work not only demonstrates a facile and eco-friendly strategy to prepare highly active and stable photocatalyst, but provides a new viewpoint about designing and constructing novel Z-scheme photocatalytic materials.

关键词： SnO2/Pt/In2O3 composite Z-scheme photocatalyst Visible light irradiation Water splitting 2,4-Dichlorophenol degradation

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Supercritical water synthesized Ni/ZrO2 catalyst and its application in the harmless treatment of oilfield wastewater in supercritical water

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JOURNAL OF ENVIRONMENTAL CHEMICAL engineering 2024年第5期12卷

作者： Kou, Jiajing He, Zigan Wang, Gaoyun Lu, Libo Wei, Wenwen Yanshan Univ Sch Vehicle & Energy 438 West Hebei Ave Qinhuangdao 066004 Hebei Peoples R China Yanshan Univ Hebei Engn Res Ctr Low Carbon Dev Resource Utilizat Fossil Energy Sources 438 West Hebei Ave Qinhuangdao 066004 Hebei Peoples R China Sinopec Shengli Oilfield Co Tech Inspection Ctr 480 Xier Rd Dongying 257000 Shandong Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn 28 Xianning West Rd Xian 710049 Shaanxi Peoples R China

Supercritical water (SCW) catalytic gasification is a clean and efficient technology with prominent advantages in treating oily wastewater generated in oilfields. SCW synthesis is a promising one-step preparation method for nano-catalytic materials, while the influence of organic matter on SCW synthesis materials remains to be studied. This study focuses on the synthesis of the Ni/ZrO2 catalysts by the supercritical water synthesis (SCWS) method, particularly examining how different types and concentrations of organic matter affect the catalysts' pore information and structural characteristics. It found that glycerol acted as a more effective precursor for generating reducing gases compared to glucose. This is attributed to glycerol's capacity in SCW to generate reducing gases for activating a greater number of Ni site within the catalyst, and the 5 wt% glycerol should be a proper concentration for SCWS of Ni/ZrO2. When employed in SCW treatment of oilfield wastewater, the Ni/ZrO2 catalyst demonstrated impressive results, achieving the carbon gasification efficiency of 99.1 % and a chemical oxygen demand (COD) removal efficiency of 100 % at 500 degrees C. These findings indicate that the SCW technique can effectively and harmlessly treat oilfield wastewater using the Ni/ZrO2 catalyst under relatively mild conditions, showing its potential as an innovative solution for wastewater management in the oil industry.

关键词： Supercritical water synthesis Ni/ZrO( 2 )catalyst Oilfield wastewater Supercritical water gasification Harmless treatment

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Grain-resolving simulations of submerged cohesive granular collapse

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JOURNAL OF FLUID MECHANICS 2022年 942卷 A49-A49页

作者： Zhu, Rui He, Zhiguo Zhao, Kunpeng Vowinckel, Bernhard Meiburg, Eckart Zhejiang Univ Ocean Coll Zhoushan 316021 Peoples R China Univ Calif 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

We investigate the submerged collapse of weakly polydisperse, loosely packed cohesive granular columns, as a function of aspect ratio and cohesive force strength, via grain-resolving direct numerical simulations. The cohesive forces act to prevent the detachment of individual particles from the main body of the collapsing column, reduce its front velocity, and yield a shorter and thicker final deposit. All of these effects can be captured accurately across a broad range of parameters by piecewise power-law relationships. The cohesive forces reduce significantly the amount of available potential energy released by the particles. For shallow columns, the particle and fluid kinetic energy decreases for stronger cohesion. For tall columns, on the other hand, moderate cohesive forces increase the maximum particle kinetic energy, since they accelerate the initial free-fall of the upper column section. Only for larger cohesive forces does the peak kinetic energy of the particles decrease. Computational particle tracking indicates that the cohesive forces reduce the mixing of particles within the collapsing column, and it identifies the regions of origin of those particles that travel the farthest. The simulations demonstrate that cohesion promotes aggregation and the formation of aggregates. Furthermore, they provide complete information on the temporally and spatially evolving network of cohesive and direct contact force bonds. While the normal contact forces are aligned primarily in the vertical direction, the cohesive bonds adjust their preferred spatial orientation throughout the collapse. They result in a net macroscopic stress that counteracts deformation and slows the spreading of the advancing particle front.

关键词： suspensions cohesive sediments particle/fluid flows

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Development of stable agar/carrageenan-Fe3O4-Klebsiella pneumoniae composite beads for efficient phenol degradation

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ENVIRONMENTAL RESEARCH 2022年 205卷 112454页

作者： Fang, Yuting Hu, Jun Wang, Haonan Chen, Duo Zhang, Anlong Wang, Xueqing Ni, Yonghao Shaanxi Univ Sci & Technol Coll Bioresources Chem & Mat Engn Coll Environm Sci & Engn Xian 710021 Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Univ New Brunswick Dept Chem Engn Fredericton NB E3B 5A3 Canada

It's of practical importance but highly challenging for cell immobilization supports to maintain mechanical strength and reduce microbial leakage in environmental and industrial applications. Herein, we developed an agar/kappa-carrageenan composite hydrogel to entrap Klebsiella pneumoniae with the combination of nano-Fe3O4 for processing phenol wastes. The agar/carrageenan-K. pneumoniae composite bead showed good pelletizing properties, superior material strength and high cell loading. Introduction of nano-Fe3O4 to the composite gel further enhanced phenol degradation rate by >10% owing to strengthened phenol oxidation by Fe3O4-induced hydroxyl radicals (center dot OH) and improved mass and electron transfers. 50 successive cycles of degradation and recycling using the agar/carrageenan-K. pneumoniae composite bead showed that 1500 mg/L phenol was fully degraded for all cycles with the highest rate of 55.12 mg L-1.h(-1) obtained at the 15th cycles. The improved stability and recyclability render the as-prepared immobilized phenol-degrading bacteria with great potential for industrial applications.

关键词： Phenol degradation Cell immobilization Agar kappa-Carrageenan Nano-Fe3O4

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STUDY ON HEAT STORAGE CHANGE CHARACTERISTICS OF A DOUBLE REHEAT BOILER DURING LOAD CYCLING PROCESSES

STUDY ON HEAT STORAGE CHANGE CHARACTERISTICS OF A DOUBLE REH...

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ASME power Conference 2019

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

ISBN: (纸本)9780791859100

The stability of the live and reheat steam temperatures is of great significance for the efficient, flexible and safe operation of coal-fired power plants. The double reheat boilers are large inertia, non-linearity and high coupling. Therefore, the temperature controls of live and reheat steams are very difficult during load cycling processes. The heat storage in the double reheat boiler changes during load cycling process, which will affect the performances of temperature control. In this study, dynamic simulation models of an ultra-supercritical double reheat tower boiler and its temperature control models are developed based on the GSE software. These models are validated Then, changes of the boiler system heat storage during different load cycling processes are studied Results reveal that the metal heat storage is more than working medium ones at steady state load. However, the changing quantities of working medium heat storage are more than the metal ones between different loads. During load cycling processes, the changing tendencies of reheat steam temperatures, the difference of heat storage between real-time and steady state values (DHSBRS) and the difference of coal feeding rate between real-time and steady values (DCBRS) are similar. The fluctuations of reheat steam temperatures have a delay compared with DHSBRS ones, and the fluctuations of DHSBRS fluctuation have a delay compared with DCBRS ones. The delay time increases with the load cycling rates. The results are aimed at providing some guidance for the control system design of the double-reheat boiler system and the safe and flexible operation of power plants.

关键词： Double Reheat Temperature Control Heat Storage Flexibility

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Experimental Investigation on Critical Heat Flux for Water flowing in a Vertical Uniformly Heated Rifled Tube under Near-critical Pressures

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Journal of Thermal Science 2018年第6期27卷 527-540页

作者： XIE Haiyan YANG Dong ZHAO Yunjie JIANG Huiqing QU Mofeng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

This study experimentally investigated the critical heat flux(CHF) of departure from nucleate boiling(DNB) of water flowing under near-critical pressures in a 2 m-long vertical upward rifled tube with the size of Φ35 × 5.67 mm. Operating conditions included pressures of 18–21 MPa, mass fluxes of 475–1000 kg·m^(-2)·s^(-1), inlet subcooling temperatures of 3–5°C, and wall heat fluxes of 40–960 kW·m^(-2). Tube wall temperature distribution and heat transfer performance in different test conditions were obtained. The effects of the operating parameters on CHF were analyzed. Four heat transfer coefficient correlations were evaluated against our experimental data for further investigation of the two-phase heat transfer characteristics. A heat transfer correlation based on Martinelli number utilized in two-phase region and two empirical correlations used to predict the CHF in rifled tube at near-critical pressures were proposed. Meanwhile, experimental CHF data in rifled tube were compared with six widely used correlations and a CHF look-up table. The CHF enhancement effect in rifled tube is obvious as compared with the CHF data in smooth tube. Results show that DNB occurs at low vapor quality and subcooled region in the rifled tube at near-critical pressures. The increase in pressure leads to the early occurrence of DNB and the decrease in CHF, whereas the increase in mass flux delays the occurrence of DNB and results in the increase in CHF. DNB presents a tendency to move toward the inlet of the rifled tube. At individual operating conditions, DNB and dryout coexist at different sections of the rifled tube.

关键词： critical heat flux near-critical pressure rifled tube DNB heat transfer

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Turning the unwanted surface bismuth enrichment to favourable BiVO4/ BiOCl heterojunction for enhanced photoelectrochemical performance

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APPLIED CATALYSIS B-ENVIRONMENTAL 2019年 241卷 506-513页

作者： Liu, Cong Zhou, Jinglan Su, Jinzhan Guo, Liejin Xi An Jiao Tong Univ Int Res Ctr Renewable Energy State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Bismuth enrichment as a common issue at the surface of bismuth vanadate (BiVO4) has been frequently reported as a severe limitation to its water oxidation kinetics. To address this problem, this study reports a novel approach to eliminate the surface bismuth enrichment by forming BiVO4/BiOCl heterojunction via surface hydrochloric acid treatment. Benefiting from type II band alignment of the BiVO4/BiOCl heterojunction, the treated photo-anode delivers excellent PEC performance with a photocurrent density of 1.83 mA/cm(2 )at 1.23 V (vs. Ag/AgCl), compared to 1.27 mA/cm(2) of untreated BiVO4 photoanode. This improvement could be attributed to the effective charge separation in heterojunction interface as the charge separation efficiency of BiVO4 increased from 28% to 41% at 1.23 V (vs. Ag/AgCl) after formation of BiVO4/BiOCl heterojunction.

关键词： Bismuth enrichment BiVO4/BiOCl heterojunction Water oxidation

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A comparative study of the pyrolysis and combustion characteristics of sodium-rich Zhundong coal in slow and rapid processes

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ENERGY SCIENCE & engineering 2019年第1期7卷 98-107页

作者： Huang, Zhong Li, Na Zhou, Qulan Wang, Duanyang Yin, Huaqiang Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian Shaanxi Peoples R China Tsinghua Univ Minist Educ Key Lab Adv Reactor Engn & Safety Beijing Peoples R China

Coal with high content of alkali metal has limited use in the combustion process. The slow and rapid pyrolysis and combustion characteristics of sodium-rich Zhundong coal were investigated using a thermal gravimetric analyzer and one-dimensional drop-tube furnace. The results show that the process was complete when the final temperature exceeds 900 degrees C in slow pyrolysis, while in rapid pyrolysis it lasts for short residence time in the whole furnace. The weight loss ratio in rapid pyrolysis was significantly higher than that in slow pyrolysis, and shows different trends at different reaction temperatures. There is an extremum value of weight loss ratio obtained at 800 degrees C in rapid pyrolysis, which is accompanied by the maximum value for the diameter of pores and the minimum value for specific surface area. Most alkali elements are released from the solid product, and the amounts of released alkali elements in combustion are higher than that in pyrolysis process. The apparent activation energy in the two pyrolysis processes and release of alkali in combustion were evaluated using different models, which demonstrates that the alkali release trend in combustion is easier than that of pyrolysis.

关键词： alkali release pyrolysis and combustion rapid process slow process sodium-rich Zhundong coal

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Synergistic promotions between high purity H2 production and CO2 capture via sorption enhanced chemical looping reforming

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FUEL PROCESSING TECHNOLOGY 2024年 254卷

作者： Liu, Mingkai Li, Yang Wang, Xuyun Gai, Zhongrui Rao, Qiong Yang, Tianlong Zhang, Jinrui Tang, Sanli Pan, Ying Jin, Hongguang Chinese Acad Sci Inst Engn Thermophys 11 Beisihuanxi Rd Beijing 100190 Peoples R China Univ Chinese Acad Sci 19A Yuquan Rd Beijing 100049 Peoples R China Univ Sci & Technol China Dept Thermal Sci & Energy Engn Hefei 230027 Peoples R China Xi An Jiao Tong Univ Int Res Ctr Renewable Energy Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

Hydrogen energy, a promising clean source, holds potential to combat global warming. To achieve efficient and low-carbon H-2 production, we proposed an isothermal sorption-enhanced chemical looping reforming (SE-CLR) process to realize the high-purity hydrogen production and in-situ CO2 capture at mild temperatures (550-650 degrees C). For practical application, the process is characterized to use Fe-Ni double metal oxide particles as steam methane reforming oxygen carriers, and K2CO3-promoted Li4SiO4 particles as CO2 sorbent. The oxygen transfer capacity of metal oxide matintained high at 57.4%, and the K-Li4SiO4 absorbents remained at 22.5% CO2 absorption capacity over 200 isothermal absorption-regeneration cycles. Conducting a synergistic conversion mechanism within double metal oxides and absorbents, and adjusting the absorbent-to-metal oxide mass ratio to 7:4, enhanced hydrogen purity to 92% and CO2 uptake to 95%. Furthermore, in-situ CO2 removal in CLR processes achieved methane conversion and H-2 production rates equivalent to conventional CLR processes under the same reaction conditions, but at temperatures similar to 60 degrees C lower. The effects of the reaction temperature, pressure, steam-to-methane and methane-to-solid ratios on SE-CLR performance were studied systematically. Finally, stable hydrogen production with a purity of 91%-89% and CO2 uptake of 94%-91% were obtained over 25 CLR cycles, with minimal changes in mechanical strength of particles.

关键词： Isothermal sorption-enhanced chemical looping reforming High-purity hydrogen production In-situCO2 capture Double metal oxide particles K-Li4SiO4 particles

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