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Performance Improvement of Combined Cycle power Plant Based on the Optimization of the Bottom Cycle and Heat Recuperation

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Journal of Thermal Science 2007年第1期16卷 84-89页

作者： Wenguo XIANG Yingying CHEN education ministry key laboratory of clean coal power generation and combustion technology Southeast University Nanjing 210096 China

Many F class gas turbine combined cycle （GTCC） power plants are built in China at present because of less emission and high efficiency. It is of great interest to investigate the efficiency improvement of GTCC plant. A combined cycle with three-pressure reheat heat recovery steam generator （HRSG） is selected for study in this paper. In order to maximize the GTCC efficiency, the optimization of the HRSG operating parameters is performed. The operating parameters are determined by means of a thermodynamic analysis, i.e. the minimization of exergy losses. The influence of HRSG inlet gas temperature on the steam bottoming cycle efficiency is discussed. The result shows that increasing the HRSG inlet temperature has less improvement to steam cycle efficiency when it is over 590℃. Partial gas to gas recuperation in the topping cycle is studied. Joining HRSG optimization with the use of gas to gas heat recuperation, the combined plant efficiency can rise up to 59.05% at base load. In addition, the part load performance of the GTCC power plant gets much better. The efficiency is increased by 2.11% at 75% load and by 4.17% at 50% load.

关键词： Heat Recovery Steam Generators (HRSG) Thermodynamic optimization Exergy analysis Combined cycle power plant Efficiency Heat rate

Chemical looping combustion of coal in interconnected fluidized beds

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Science China(Technological Sciences) 2007年第2期50卷 230-240页

作者： SHEN LaiHong ZHENG Min XIAO Jun ZHANG Hui XIAO Rui key laboratory of clean coal power generation and combustion technology of ministry of education Southeast UniversityNanjing 210096China

Chemical looping combustion is the indirect combustion by use of oxygen carrier. It can be used for CO2 capture in power generating processes. In this paper, chemical looping combustion of coal in interconnected fluidized beds with inherent separation of CO2 is proposed. It consists of a high velocity fluidized bed as an air reactor in which oxygen carrier is oxidized, a cyclone, and a bubbling fluidized bed as a fuel reactor in which oxygen carrier is reduced by direct and indirect reactions with coal. The air reactor is connected to the fuel reactor through the cyclone. To raise the high carbon conversion efficiency and separate oxygen carrier particle from ash, coal slurry instead of coal particle is introduced into the bottom of the bubbling fluidized bed. coal gasification and the reduction of oxygen carrier with the water gas take place simultaneously in the fuel reactor. The flue gas from the fuel reactor is CO2 and water. Almost pure CO2 could be obtained after the condensation of water. The reduced oxygen carrier is then returned back to the air reactor, where it is oxidized with air. Thermodynamics analysis indicates that NiO/Ni oxygen carrier is the optimal one for chemical looping combustion of coal. Simulation of the processes for chemical looping combustion of coal, including coal gasification and reduction of oxygen carrier, is carried out with Aspen Plus software. The effects of air reactor temperature, fuel reactor temperature, and ratio of water to coal on the composition of fuel gas, recirculation of oxygen carrier particles, etc., are discussed. Some useful results are achieved. The suitable temperature of air reactor should be between 1050–1150°C and the optimal temperature of the fuel reactor be between 900–950°C.

关键词： chemical looping combustion coal interconnected fluidized beds CO2 separation

Mechanism and Kinetics Analysis of NO/SO_2/N_2/O_2 Dissociation Reactions in Non-Thermal Plasma

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Plasma Science and technology 2008年第6期10卷 710-716页

作者：王心亮李婷婷魏冬香魏艳丽顾璠 key laboratory of clean coal power generation combustion technology of ministry of education School of Energy Engineering and Environmental EngineeringSoutheast UniversityNanjing 210096China

The kinetics mechanism of the dissociation reactions in a NO/SO2/N2/O2 system was investigated in consideration of energetic electrons＇ impacts on a non-thermal plasma. A model was derived from the Boltzmann equation and molecule collision theory to predict the dissociation reaction rate coefficients. Upon comparison with available literature, the model was confirmed to be acceptably accurate in general. Several reaction rate coefficients of the NO/SO2/N2/O2 dissociation system were derived according to the Arrhenius formula. The activation energies of each plasma reaction were calculated by quantum chemistry methods. The relation between the dissociation reaction rate coefficient and electron temperature was established to describe the importance of each reaction and to predict relevant processes of gaseous chemical reactions. The sensitivity of the mechanism of NO/SO2/N2/O2 dissociation reaction in a non-thermal plasma was also analysed.

关键词： non-thermal plasma chemical reaction kinetics Boltzmann equation rate coefficient

Removal of dust from flue gas in magnetically stabilized fluidized bed

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Particuology 2008年第2期6卷 116-119页

作者： Yinghui Wang Keting Gui Mingheng Shi Changfeng Li School of Energy and power Engineering Jiangsu University Zhenjiang 212013 Jiangsu China key laboratory of clean coal power generation and combustion technology of ministry of education Southeast University Nanjing 210096 Jiangsu China

A magnetically stabilized fluidized bed （MSFB,Ф 500mm×2100mm） was designed to study dust removal from flue gas. Based on the mechanism of dust removal in a fixed bed, the effects on collection efficiency of magnetic field intensity, ratio of flue gas velocity to minimum fluidization velocity, bed height, and particle average diameter, were investigated. Then feasible methods for MSFB to better remove dust were proposed. Over 95 % of dust removal with MSFB can be achieved, when stable fluidization is maintained and when magnetic particles are frequently renewed.

关键词： Magnetically stabilized fluidized bed (MSFB) Stable fluidization Dust removal Magnetic particles renewal

Experimental study on MSW gasification and melting technology

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Journal of Environmental Sciences 2007年第11期19卷 1398-1403页

作者： XIAO Gang JIN Bao-sheng ZHONG Zhao-ping CHI Yong NI Ming-jiang CEN Ke-fa XIAO Rui HUANG Ya-ji HUANG He key laboratory of clean coal power generation and combustion technology of ministry of education School of Energy and Environment Southeast University Nanjing 210096 China State key laboratory of clean Energy Utilization Zhejiang University Hangzhou 310027 China College of Life Science and Pharmaceutical Engineering Nanjing University of Technology Nanjing 210009 China

In order to develop municipal solid waste （MSW） gasification and melting technology, two preliminary experiments and a principle integrated experiment were fulfilled respectively. The gasification characteristics of MSW were studied at 500-750℃ when equivalence ratio （ER） was 0.2--0.5 using a fluidized-bed gasifier. When temperature was 550-700℃ and ER was 0.2--0.4, low heat value （LHV） of syngas reaches 4000-12000 kJ/Nm^3. The melting characteristics of fly ash were investigated at 1100-1460℃ using a fixed-bed furnace. It was proved that over 99.9% of dioxins could be decomposed and most heavy-metals could be solidified when temperature was 1100-1300℃. The principle integrated experiment was carried out in a fluidized-bed gasification and swirl-melting system. MSW was gasified etticiently at 550-650℃, swirl-melting furnace maintains at 1200-1300℃ stably and over 95% of fly ash could be caught by the swirl-melting furnace. The results provided much practical experience and basic data to develop MSW gasification and melting technology.

关键词： municipal solid waste (MSW) fluidized-bed gasification swirl-melting characteristics

Three-dimensional Simulation of Gas/Solid Flow in Spout-fluid Beds with Kinetic Theory of Granular Flow

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Chinese Journal of Chemical Engineering 2006年第5期14卷 611-617页

作者：钟文琪章名耀金保升袁竹林 education ministry key laboratory on clean coal power generation and combustion technology Thermoenergy Engineering Research Institute Southeast University

A three-dimensional Eulerian multiphase model, with closure law according to the kinetic theory of granular flow, was used to study the gas/solid flow behaviors in spout-fluid beds. The influences of the coefficient of restitution due to non-ideal particle collisions on the simulated results were tested. It is demonstrated that the simulated result is strongly affected by the coefficient of restitution. Comparison of simulations with experiments in a small spout-fluid bed showed that an appropriate coefficient of restitution of 0.93 was necessary to simulate the flow characteristics in an underdesigned large size of spout-fluid bed coal gasifier with diameter of lm and height of 6m. The internal jet and gas/solid flow patterns at different operating conditions were obtained. The simulations show that an optimal gas/solid flow pattern for coal gasification is found when the spouting gas flow rate is equal to the fluidizing gas flow rate and the total of them is two and a half times the minimum fluidizing gas flow rate. Besides, the radial distributions of particle velocity and gas velocity show similar tendencies; the radial distributions of particle phase pressure due to particle collisions and the particle pseudo-temperature corresponding to the macroscopic kinetic energy of the random particle motion also show similar tendencies. These indicate that both gas drag force and particle collisions dominate the movement of particles.

关键词： gas/solid flow CFD Eulerian multiphase model kinetic theory of granular flow spout-fluid bed

Research on low emission MSW gasification and melting system

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Frontiers of Environmental Science & Engineering 2007年第4期1卷 498-503页

作者： XIAO Gang NI Mingjiang CHI Yong JIN Yuqi ZHANG Jiaquan MIAO Qi CEN Kefa State key laboratory of clean Energy Utilization Institute for Thermal Power EngineeringZhejiang UniversityHangzhou 310027China key laboratory on clean coal power generation and combustion technology of MOE Southeast UniversityNanjing 210096China

In order to eliminate secondary pollution caused by municipal solid waste(MSW)incineration,a MSW gasification and melting process is *** process is expected to reduce the emission of pollutants,especially heavy-metals and *** this paper,the combustible components of MSW and simulated MSW were gasified in a lab-scale fluidized bed at 400°C-700°C when the excess air ratio(ER)was between 0.2 and *** experimental results indicated that the MSW could be gasified effectively in a fluidized bed at approximately 600°C-700°C when excess air ratio was *** melting characteristics of two typical fly ash samples from MSW incinerators were *** results indicated that fly ash of pure MSW incineration could be melted at approximately 1,300°C and that of MSW and coal co-combustion could be melted at approximately 1,400°*** temperature was over 1,100°C,more than 99.9%of the dioxins could be decomposed and most of the heavy-metals could be solidified in the *** on the above experiments,two feasible MSW gasification and mel-ting processes were proposed for low calorific value MSW:(1)sieved MSW gasification and melting system,which was based on an idea of multi-recycle;(2)gasification and melting scheme of MSW adding coal as assistant fuel.

关键词： municipal solid waste(MSW) low emission gasification and melting dioxins heavy-metal

Melt flow,heat transfer and solidification in a flexible thin slab continuous casting mold with vertical-combined electromagnetic braking

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Journal of Iron and Steel Research International 2024年第2期31卷 401-415页

作者： Lin Xu Ze-feng Han Christian Karcher En-gang Wang key laboratory of Electromagnetic Processing of Materials(ministry of education) Northeastern UniversityShenyang110819LiaoningChina key laboratory of Liaoning Province for clean combustion power generation and Heating technology Shenyang Institute of EngineeringShenyang110136LiaoningChina Institute of Thermodynamics and Fluid Mechanics Technische Universität IlmenauIlmenau98684Germany

During continuous casting of steel slabs,the application of electromagnetic braking technology(EMBr)provides an effective tool to influence solidification by controlling the pattern of melt flow in the ***,the quality of the final product can be improved considerably.A new electromagnetic braking(EMBr)method,named vertical-combined electromagnetic braking(VC-EMBr),is proposed to be applied to a flexible thin slab casting(FTSC)*** evaluate the beneficial effects of the VC-EMBr,the melt flow,heat transfer,and solidification processes in the FTSC mold are studied by means of numerical *** detail,a Reynolds-averaged Navier–Stokes turbulence model together with an enthalpy-porosity approach was *** numerical findings are compared with respective simulations using the traditional *** results demonstrate that the application of the VC-EMBr contributes significantly to preventing relative slab *** contrast to the Ruler-EMBr,the additional vertical magnetic poles of the VC-EMBr preferentially suppress the direct impact of jet flow on the narrow face of FSTC mold and considerably diminish the level fluctuation near the meniscus *** instance,by applying a magnetic flux density of 0.3 T,the maximum amplitude of meniscus deflection reduces by about 80%.Moreover,the braking effect of the VC-EMBr effectively improves the homogeneity of temperature distribution in the upper recirculation region and increases the solidified shell thickness along the casting *** this basis,the newly proposed VC-EMBr shows a beneficial effect in preventing relative slab defects for FTSC thin slab continuous casting.

关键词： Electromagnetic braking Mold Melt flow Heat transfer Solidification

Gas-Solid Flow,combustion Characteristics,and Gas Emissions in a 75 t/h CFB Boiler Based on the CPFD Method

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Journal of Thermal Science 2025年第1期 323-336页

作者： HUANG Xiankun BAI Zhang ZHU Xiaoli WANG Shuoshuo MU Lin GONG Liang College of New Energy China University of Petroleum (East China) key laboratory of Ocean Energy Utilization and Energy Conservation of ministry of education School of Energy and Power EngineeringDalian University of Technology

A 3D simulation using Computational Particle Fluid Dynamics（CPFD） methods was used to calculate coal combustion in a 75 t/h industrial-scale circulating fluidized bed（CFB） *** characteristics,gas-solid flow characteristics,and gaseous pollutant emissions of CFB boilers from combustion ignition to stable operation were systematically evaluated in this *** show that the temperature distribution is relatively uniform throughout the *** the combustion process unfolds within the boiler,the gas composition curve strikingly portrays the inverse correlation between CO2and *** the combustion reaction progresses,it becomes evident that the concentration of CO2progressively increases,while the concentration of O2concurrently *** inverse relationship underscores the fundamental combustion reaction,where carbon-based fuels react with oxygen to produce carbon dioxide and release ***,a comprehensive analysis has revealed that,from ignition to stable combustion,both nitric oxide（NO） and sulfur dioxide（SO2） emissions exhibit a declining *** reduction in pollutant generation is attributed to the improvement in combustion *** complete combustion leads to lower levels of unburned hydrocarbons,which are prone to NO ***,the sulfur content in the fuel is more efficiently oxidized to sulfur trioxide（SO3） or bound in sulfates,reducing *** steady state in the simulation,the SO2mass flow rate varies significantly with the furnace height,gradually increasing from 0.07 kg·s-1at 4 m at the bottom of the furnace to a peak of 0.078 kg·s-1at 8 m in the center,and then decreasing to 0.06 kg·s-1at 20m at the top of the furnace.

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