- YAO Yuan;WEI Xiaolin;CHEN Lixin;LI Sen;TAN Houzhang;State Key Laboratory of High Temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Sciences;School of Engineering Science,University of Chinese Academy of Sciences;Beijing Hinergy Clean Energy Technology Co.,Ltd.;School of Energy and Power Engineering,Xi'an Jiaotong University;
The key technologies for high energy efficiency and low emission of industrial furnaces can effectively improve the energy utilization efficiency and reduce pollutant emissions. In this paper,the research of common key technologies for energy conservation and emission reduction in industrial furnaces were reviewed,such as energy-saving management and waste heat utilization,oxygen-enriched calcination,staged combustion,particle separation and resource utilization,and their integrated applications in 2 500-5 000 t/d cement kilns. Based on the matching relationship between the material and energy flow of industrial furnaces,the design of an energy-saving management platform was carried out. New energy-saving technologies for optimization and reorganization of energy flow in cement kilns were developed to meet the requirements of multiple types process goals. The industrial demonstration of the energy-saving management platform matching the material and energy flow in cement kilns has been implemented. The oxygen-enriched calcination technologies in cement kilns was developed by organically combining low-energy pressure-swing-adsorption and cement clinker calcination,which can meet the wide threshold variation in production of product category and output quality,and their industrial demonstrations was carried out.In view of the problems of high emissions such as NOxand SOx,the stage combustion and SNCR denitration technologies in decomposition furnace were comprehensively optimized. The industrial demonstration of the technologies for the staged combustion and SNCR optimized denitrificationin cement decomposition furnace has been conducted. Aiming at emission reduction and resource utilization,the new technologies for particulate emissions purification,separation and reuse in deep cooling and dust removal of flue gas have been proposed. The industrial demonstration of efficient separation and clean utilization of gas-solid emissions in industrial furnaces has been put into effect. The clean emission and resource utilization of particulate matter have been realized.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 14645K] - WEI Xiaolin;LI Huixin;LI Sen;HUANG Junqin;LI Bo;CHEN Lixin;State Key Laboratory of High Temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Sciences;School of Engineering Science,University of Chinese Academy of Sciences;Beijing Hanneng Qingyuan Science & Technology Co.,Ltd.;
Industrial furnace is a huge energy consumption industry in China,which accounts for about 1/4 of the total energy consumption in China every year. In the increasing shortage of energy and environmental pollution today,the energy saving and emission reduction is very urgent for the industrial furnaces and kilns. The production of industrial furnaces is a process of collaborative works of different equipments and processes,including the conversion and transfer of material and energy between various systems. Therefore,the analysis of material flow and energy flow for industrial furnaces and kilns is the basis of realizing high efficiency and low emission. The general method is mainly analyzed from the perspective of energy or waste heat utilization of the furnace products,and the industrial furnace is not regarded as a total system to investigate the material flow and energy flow status. In this paper,based on the node calculation method and starting from the whole system of industrial furnaces,a mathematical model of matching material flow and energy flow was established,and the energy balance of different parts of a typical industrial furnace was obtained. Meanwhile,the exergy loss of furnace system was studied by the second law of thermodynamics,and the key parts of furnace energy saving were found. The material flow and energy flow of 3 200 t/d typical cement kiln were analyzed and calculated by this method. The results show that the heat loss of cement kiln mainly includes high-temperature loss and low-temperature loss. The high-temperature loss is mainly the heat loss of the kiln's walls and the carbon heat loss of unburned coal,accounting for 6.84% and 1.95% respectively,and corresponding to the loss of exergy as 4.17% and 2.59% respectively,which has a few energy-saving potential. The low-temperature heat loss includes the heat loss of flue gas at the tail of kiln and sensible heat from the clinker out of the cooler. The heat loss of AQC furnace and SP furnace accounts for 3.06% and 6.19% respectively,and corresponding to the loss of exergy as 1.26% and 1.45% respectively,which is still worthy of utilization. According to the different reasons for high temperature and low temperature heat loss,in this paper,the energy saving potential of furnace and kiln was evaluated and some new technologies,such as advanced heat insulation of furnace wall,oxygen enriched calcination,and low temperature waste heat utilization were proposed,which could further reduce the coal consumption of the kiln. In addition,some new technologies are recommended to reduce the electrical power consumption of the equipment,such as the use of high-efficiency fans and permanent magnet motors,combined with the technology of surplus steam-driven fan and energy-saving management,which is expected to achieve the goal of zero power consumption of clinker sintering system.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 2719K] - CHEN Jiahao;YUAN Ye;HE Yong;WANG Zhihua;TAN Jiaxin;ZHU Yanqun;CEN Kefa;State Key Laboratory of Clean Energy Utilization,Zhejiang University;
In order to realize the clean,efficient and low-carbon utilization of coal,combined with partial coal gasification and semi-coke combustion to realize the grading and separating utilization of coal-gas and electricity,the Aspen Plus process simulation software was used to simulate the partial pulverized coal gasification and semi-coke combustion of gas and electric power polygeneration system for 300 MW coal powder boiler. First,under certain assumptions,a coal gasification model based on the principle of reaction equilibrium was established by using Aspen Plus software,and the simulation results were compared with the experimental bench gasification results,and the simulation results were basically consistent with the experimental results. On the basis of this coal gasification model,the influence of oxygen-to-coal ratio and coal type on the gas composition at the outlet of the gasifier and the economic benefit of the 300 MW polygeneration system was explored. The calculation results show that the effective gas production rate of Shenfu Dongsheng coal gasification increases from 58.49% to 82.85% when the oxygen-to-coal ratio increases from 0.1 to 0.3,and the increased annual revenue of the polygeneration system increases from 160.84 million yuan to 622.46 million yuan; when the oxygen-to-coal ratio is 0.3,the effective gas production rates of Shenfu Dongsheng coal,Gongyi anthracite,Shenhua bituminous coal and Ximeng lignite coal gasification are 82.85%,74.51%,77.21%and 95.16%,respectively. The increased annual income of the polygeneration system by using the three coal types as raw materials is463.92 million yuan,289.1 million yuan and 62.46 million yuan,respectively. It is concluded that the gas quality,effective gas production rate,and the economic benefits of the polygeneration system are significantly improved within the simulated range of oxygen-to-coal ratio,as the oxygen-to-coal ratio increases; in the operating condition where the oxygen-to-coal ratio is 0.3,the economic benefits of the system are the best when using Shenfu Dongsheng coal as the raw material,followed by Shenhua bituminous coal and Gongyi anthracite. The semi-coke produced by coal gasification of Ximeng lignite is too low to be conducive to the operation of the polygeneration system.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 2789K] - WANG Xuyang;YU Jie;XU Linlin;SUN Lushi;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology;
In order to study the effect of coal water slurry(CWS) concentration and pyrolysis temperature on the formation of pyrolysis gas and the structure of coal char,the rapid pyrolysis of Inner Mongolia bituminous coal and coal water slurry with different concentrations(55%,60%and 65%) was tested at different temperatures(800,900 and 1 000℃),the change law of pyrolysis gas of coal water slurry with pyrolysis temperature and coal water slurry concentration was investigated,and the microcrystalline structure changes of coal char after pyrolysis of coal water slurry and coal powder were analyzed by XRD and Raman.The results show that under the constant concentration of coal water slurry,the production of CO,CH_4,CO_2,H_2,HCN and NH_3 gradually increases with the increase of temperature,and the production of HCN is much higher than that of NH_3.At a constant temperature,with the increase of the raw coal concentration in the coal water slurry,the production of CO and CH_4 gradually increases,while the production of CO_2,H_2,HCN and NH_3 gradually decreases.The results of XRD show that with the increase of pyrolysis temperature and the increase of water content in coal water slurry,the d_(002)of coal char of coal water slurry gradually decreases,and the L_cgradually increases.The results of Raman show that with the increase of pyrolysis temperature and the increase of water concentration,A_(D1)/A_G and A_(D3)/A_G gradually decrease,while A_G/A_(all)gradually increases.These show that the degree of ordering of the carbon microcrystal structure in coal char gradually increases with the increase of pyrolysis temperature and water concentration,and the graphitization degree of coal char increases.The correlation analysis between Raman and XRD shows that during the pyrolysis of coal water slurry,d_(002) is positively correlated with A_(D1)/A_G and L_c is positively correlated with A_G/A_(all)with the change of pyrolysis temperature and coal water slurry concentration.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 13323K] - XU Xinwei;TAN Houzhang;WANG Xuebin;YANG Fuxin;LIU Xing;ZHENG Haiguo;School of Energy and Power Engineering,Xi'an Jiao Tong University;Xi'an Green Power Technology Co.,Ltd.;
The increasingly strict emission standards on NO_x put forward higher requirements for the performances of the coal-fired industrial boilers. It is hard for the existing burners in industrial boilers to meet the emission restrictions by operation optimization. In this study,a new type of coal-fired low-NO_x swirling burner for industry boilers was developed. Through the experiments in a 25 t/h industry boiler,the effects of primary air ratio,secondary air distribution,swirling angle,recirculated flue gas( FGR) and over fire air( OFA) ratio on NO_x emission and combustion efficiency were studied. The results show that the NO_x emission increases when the primary air ratio increases from 7.8% to 8.5% and the inner/outer secondary air ratio increases from 0.67 to 1.32. As the angel of swirl vane increases from 30° to 60°,the NO_x emission decreases first and then increases. With the increase of FGR ratio from zero to 13.3%,the NO_x emission first decreases and then tends to be stable. The effect from OFA ratio on NO_x emission is slight,and with the increase of OFA ratio,the NO_x emission first decreases,and then increases. During the test process,the coal stream flame is stable and the unburned carbon content in fly ash( UBC) is always lower than 25%. The lowest NO_x emission is obtained as 171-178 mg/m~3( 9% O_2),with a UBC value of 14.9% and a boiler efficiency of 91.7%.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 4788K] - ZHANG Jiaming;WANG Zibing;GUO Shan;WANG Shaolong;LI Shicheng;College of Metallurgy and Energy,North China University of Science and Technology;
As an important equipment in the metallurgical industry,the regenerative heating furnace is mainly used for billet heating. Using the high gas and converter gas as fuel and adopting the periodic reversal combustion method,the burner emits off-gas into the atmosphere during the reversal combustion process. The gas emission rate caused by the reversing action reaches to 3%-7%,causing waste of resources and environmental pollution. In order to save resources,reduce pollution,and solve the problem of gas emission caused by regenerative heating furnaces during combustion reversal,the most direct way of recycling is to sweep the residual gas in public pipes into the furnace for combustion. Now,the 160 t/h regenerative reheating furnace of a steel plant is being modified,and a flue gas purge system is installed on the existing operating platform. The flue gas purge system is to lead all the way from the gas flue gas pipeline for purging.The gas flue gas as the purge gas source is pressurized by the induced draft fan,and the purge pipe is connected with the bottom of the gas reversing valve. By adjusting the original gas reversing program and cooperating with the fast response control valve,the start and stop of the scanning process is carried out. During the purge,the flue gas pressurized in advance in the pipeline is ejected,and the residual gas in the public pipeline is quickly blown into the furnace for combustion,so as to achieve the effect of gas emission reduction.At last,the engineering practice was carried out,and the system furnace temperature,furnace pressure,CO emission reduction effect and economy before and after the transformation were compared. For the renovated heating furnace,a single purge volume is 37.05 Nm~3. According to the single reversal cycle of the heating furnace for 60 s,the annual working time of the heating furnace is calculated based on 330 days and the annual purging volume is 17.606 2 million Nm~3. If the purging efficiency is calculated as 90%,the annual gas emission is 15.854 6 million Nm~3,and the corresponding factory gas price is 0.13 yuan/Nm~3,which can save 2.06 million yuan a year. With the application of the regenerative heating furnace backflushing system,the CO emission reduction rate is as high as 90%.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 5674K] - REN Sida;LIANG Wenjun;ZHANG Yiming;LI Qinglei;ZHU Yuxue;Key Laboratory of Beijing onRegional Air Pollution Control,Beijing University of Technology;
In view of the characteristics of low concentration and discontinuous emission of VOCs from industrial furnaces in small enterprises,the commercial activated carbon was chosen as adsorption material and the home-made Pd-Ce/Al_2O_3 binary catalyst was used as catalytic material to study the integrated purification technology of VOCs waste gas from industrial furnaces. BET,SEM and TG were used to characterize and test the adsorption performance of the activated carbon. Toluene was chosen as target pollutants to investigate the effects of the desorption time,the flue gas dilution ratio,the catalytic temperature and the flue gas cycle times on the purification performance of toluene exhaust gas. The results show that the adsorbed toluene in the active carbon can be removed with the thermal generation at 100 ℃ for 1 hour,and toluene be completely oxidized when the catalytic temperature is 320 ℃ .After 10-15 cycles of operation,the activated carbon material can be completely regenerated at 100 ℃ for 6 h,which has the best economic benefit. The characterization results show that after many times of thermal regeneration,the pore channel of activated carbon partially collapses,the specific surface area decreases from889 m~2/g to 688 m~2/g,and the pore volume decreases from 0.50 mL/g to 0.37 mL/g. But the pore diameter is still about 2.2 nm,which is consistent with the reduction of wrinkles on the surface of activated carbon observed by SEM,indicating that the pore of activated carbon collapses to a certain extent after thermal regeneration,but can maintained the mesoporous characteristics. The weight loss curve of activated carbon after regeneration in TG curve is slightly lower than that of fresh activated carbon,which further proves that multiple thermal regeneration has a certain destructive effect on the pore structure of activated carbon.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 10175K] - SONG Weiyi;ZHU Baozhong;SUN Yunlan;XIE Chaoyue;School of Petroleum Engineering,Changzhou University;
Calcination atmosphere has an important influence on the activity of catalyst. To optimize the preparation process of citric acid sol-gel iron oxide( Fe_2O_3/LA) low-temperature denitrification catalyst and clarify the effects of calcination atmosphere on the low-temperature denitrification performance of Fe_2O_3/LA catalyst,the Fe_2O_3/LA-Air and Fe_2O_3/LA-Ar catalysts were prepared by a citric acid( LA) sol-gel method and the catalysts were characterized by N_2 adsorption desorption( BET),X-ray powder diffraction( XRD),H_2 reduction by heating( H_2-TPR),NH_3-temperature desorption( NH_3-TPD) and X-ray photoelectron spectroscopy( XPS). The results show that Fe_2O_3/LA-Air catalyst has poorer denitrification activity at high temperature compared with Fe_2O_3/LA-Ar catalyst,while it has better denitrification performance at low temperature,especially at 120-240 oC,of which the NOxconversions can reach 80-100%. And its nitrogen adsorption-desorption curve is H_3 type hysteresis loop Ⅱ type isotherm with larger pores. The Fe_2O_3/LA-Air catalyst has a typical H_2 reduction peak of medium and low temperatures at 270 oC,which has strong reduction capacity. The main active ingredients of the catalysts calcined at two atmospheres are γ-Fe_2O_3. The contents of Fe~(3+) and surface adsorption oxygen Oβin Fe_2O_3/LA-Air catalyst are 3.24% and 48.24% higher than those of the Fe_2O_3/LA-Ar,repectively. For the Fe_2O_3/LA-Ar catalyst,its peaks of ammonia desorption at moderate and high temperatures all move towards high temperature,and the peak area of ammonia desorption at high temperature is larger than that of Fe_2O_3/LA-Air catalyst,so there are more Lewis acid sites. However,the Bronsted acid sites of Fe_2O_3/LA-Air catalyst are more than those of Fe_2O_3/LA-Ar catalyst. These factors are responsible for that the denitrification activity of Fe_2O_3/LA catalyst calcined in air atmosphere at low temperature is better than that of Fe_2O_3/LA catalyst calcined in argon atmosphere.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 8622K] - LI Sen;FANG Lijun;SUN Lichao;ZHAO Tuo;State Key Laboratory of High-temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Sciences;School of Energy & Mechanical Engineering,North China Electric Power University;
Cement kiln is a typical industrial furnace with high pollution emission,and the cement industry has become the third largest source of NO_xemission.At present,a lot of research has been done on the application of fuel staged combustion technology in utility boilers at home and abroad,but less on cement kiln.According to the characteristics of staging combustion for high calcium environment in cement precalciner,the experimental study on NO removal by reducing gas CO was carried out in fluid bed reactor,and the effects of CO concentration,Ca O and temperature on the denitrification process of CO were studied.The reaction path of NO reduction by CO was simulated in a one-dimensional plug flow reactor.The results indicate that CO has a strong denitrification effect in reducing atmosphere,and CO concentration has a great influence on denitrification.With the increase of CO concentration,the NO reduction efficiency increases.The NO emission is effectively reduced with the increase of CO concentration,and when the CO concentration increases from 1% to 5%,the efficiency of NO reduction increases by 37.8%.During NO reduction by CO,the intermediate products such as NH and H are produced,and NH and H play an important role in the NO reduction by CO.HCN can be adsorbed on Ca O surface and reacts with Ca O.In reducing atmosphere,NH_3adsorbs on Ca O surface and reacts to form Ca(N) and finally forms N_2.NO is reduced to N_2mainly through four pathways,and the paths of NO→N_2O→N_2 and NO→HNO→NH→N_2 are the most important reaction paths.In the experimental temperature range,the increase of temperature promotes the reduction and denitrification of CO.Ca O has a strong positive catalysis on CO denitrification at 850℃<T<1 050℃.Compared with the absence of Ca O,when CO concentration is 4% and the temperature is higher than 900℃,NO reduction efficiency significantly increases,which indicates that Ca O has effective catalysis in the high temperature region.At 1 050℃,the denitrification efficiency is increased by 7.56%.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 2809K] - LI Chengyu;GAO Zhenqiang;GAO Mingyun;GAO Shengtang;WANG Youtang;School of Transportation and Vehicle Engineering,Shandong University of Technology;Shandong Yancheng Air Conditioning Co.,Ltd.;
Large quantities of waste heat from medium and high temperature flue gas are generated from industrial kilns. However,the present power cycles or working fluids is difficult to effectively recover the waste heat of flue gas with the temperature drop. A cascading transcritical power cycle using CO_2 as working fluids was proposed. The maximum net power output per unit mass flue gas was selected as objective function. The effects of parameters on cycle thermodynamic performance were investigated under flue gas temperature of 400 and 500 ℃ .The influence of mass split flow ratio and high pressure on thermal matching in regenerator and cycle performance were mainly analyzed. The optimization and comparative analysis was conducted among basic transcritical cycle,regenerative transcritical cycle and cascading transcritical cycle. The results indicate that the thermal matching in regenerator is key influence factor on cycle performance of the cascade cycle. By adjusting mass split flow ratio x at the outlet of the working medium pump to improve the regenerative matching,the optimal value of of working medium is 0.6 and 0.7 under flue gas temperature of 400 and 500 ℃ . The increase of endothermic pressure is beneficial to the increase of net power output,and when the endothermic pressure increases from 20 MPa to 35 MPa under flue gas temperature of 500 ℃,the net power increases from 117.4 kW to 143.8 kW,with an increase of 22.49%. The higher pressure also promotes power output for both high-and low-temperature turbines,but the deteriorates heat exchange amount in regenerator. The ratio of low-temperature turbine power output to total ranges from 31.4% to 27.3% with high pressure increasing from 20 to 35 MPa,which means that the hightemperature turbine is more affected by high pressure. Compared with the three transcritical CO_2 cycles,the basic transcritical cycle has the lowest thermal efficiency and net power output. The regenerative transcritical cycle achieves the highest thermal efficiency. The cascading transcritical cycle outputs the maximum net power. The net power output of cascading transcritical cycle is 22.2% and 6.1% higher than that of basic and regenerative cycle under flue gas temperature of 400 ℃,respectively,and the values is 35.7% and 12.5% under flue gas temperature of 500 ℃ .
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 6860K] - HUANG Yuankai;ZHU Yanqun;SHAO Jiaming;TANG Hairong;HE Yong;WANG Zhihua;State Key Laboratory of Clean Energy Utilization,Zhejiang University;
Most of flue gas is washed by wet spraying to achieve efficient removal of pollutants in engineering projects. However,it is found that there is a large amount of aerosol produced during this process,which makes the tail gas unable to meet emission standards. Up to now,the relevant researches focus on the formation mechanism and corresponding control methods of SO_3 acid mist and sulfate aerosol,and there is no report or research focuses on the phenomenon of nitrate aerosol in some applications of ozone deNO_x technology. Therefore,through the establishment of ozone deNO_x system,the Gasmet flue gas analyzer was used to measure the gas components and concentration,the aerosol particle size distribution sampler and ion chromatography were used to measure the concentration of the nitrate aerosol. An experimental study on the formation mechanism and control of nitrate aerosol was carried out. The results show that the nitrate aerosol concentration is positively correlated with the initial NO concentration,which increases from 7.06 mg/m~3 to 18.66 mg/m~3 as the NO concentration increases from 200×10~(-6) to 400× 10~(-6). When O_3/NO molar ratio is 1.0,the presence of NH_4~+ in the slurry causes the nitrate aerosol concentration to increase. When the N_H4~+ concentration increases from 2 g/L to 4 g/L,the nitrate aerosol concentration remains at 8 mg/m~3,but the average particle size increases. Additionally,the aerosol concentration decreases with the increase of O_3/NO molar ratio without NH_4~+ addition. However,when 2 g/L NH_4~+ was added into the slurry,the aerosol concentration increases dramatically from 7.06 mg/m~3 to 161.94 mg/m~3 as the O_3/NO raises from 1.0 to 1.6. The addition of reducing additives X in the slurry significantly reduces the aerosol concentration with the maximum aerosol suppression efficiency of 47.7%. This method has a certain industrial application prospect as a nitrate aerosol suppression technology in the ozone deNO_x process.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 6097K] - DING Xiaohua;HUANG Kun;YANG Wen;NARI Technology Co.,Ltd.;
The cement manufacturing industry has always been one of the high energy consumption industries in China,which is highly dependent on energy. Energy consumption accounts for 40%-60% of production costs. In recent years,according to the " Thirteenth FiveYear Development Guidelines for the Building Materials Industry",cement companies have made great progress in energy conservation.However,compared with the world ' s advanced level,there is still a gap in the comprehensive energy consumption per ton of cement.The cement firing system is the main energy consumption part in the cement production process. The cement firing system carries out complex physical and chemical reactions,involving many links and equipment,and the collected data has the characteristics of nonlinearity,strong coupling,numerous variables and large lag. In recent years,with the development of artificial intelligence and the popularization of industrial data collection,distributed control system( DCS) has been widely used in various industries,and artificial intelligence analysis and optimization methods have become the mainstream of industrial data analysis and optimization. In order to improve the production efficiency of cement production enterprises,and based on the analysis of the historical operating variables and production energy efficiency data of the electric process of the cement clinker burning system,a data-driven energy hybrid algorithm for consumption optimization and parameters recommendation of the cement clinker burning system are used. First,for the parameter selection problem,the average influence value algorithm is used to analyze the energy consumption sensitivity,and the parameters that affect energy consumption are filtered. In the modeling phase,the improved BP neural network is used to model the energy consumption. After obtaining the system energy consumption model,the genetic algorithm is used to optimize it,so that the energy consumption model can be controlled to run with the optimization goal of the lowest power consumption per ton of clinker and can obtain the optimized values of the operating parameters. The algorithm has actually been deployed in the cement clinker firing system of Baishan Cement Plant. The operation results show that the algorithm effectively supports the energy consumption management of the cement clinker firing system. Before optimization,the cement energy consumption is always around 15 000 kWh. Through simulation optimization,the optimal energy consumption is 13 661 kWh,which reduces energy consumption by about 7%. At the same time,the recommended values of characteristic variables can be obtained.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 3395K] - ZHANG Wanjing;WEI Xiaolin;LI Teng;HUANG Junqin;State Key Laboratory of High Temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Sciences;School of Engineering Science,University of Chinese Academy of Sciences;Dalian National Laboratory for Clean Energy,CAS;
The large number of high-temperature dust-containing gases produced in the production of industrial furnaces carry a lot of waste heat and energy. If they can be reasonably recycled,it will create great economic and environmental value. Therefore,the purification and dust removal of high-temperature gas is a key technology to realize the effective utilization of resources and environmental protection.The new metal porous material has excellent applicability and superiority in high-temperature flue gas dust removal due to its good temperature resistance,mechanical properties,and thermal conductivity. In this paper,the metal wirework ash bag filter was selected as the research object. Through the combination of experiment and numerical simulation,the influences of the inlet air flow rate,dust concentration,and inlet temperature on the pressure drop of the dust removal system were explored. The experimental results show that the pressure drop of the system increases with the increase of the inlet air flow rate. When the inlet clean air flow rate increases from 0. 4 Nm~3/h to 34.3 Nm~3/h,the pressure drop increases rapidly from 12. 6 Pa to 1 989 Pa. The system pressure drop of dusty gas is higher than that of clean air under the same gas flow rate and the pressure drop increases with the increase of ash concentration in gas. When the dust concentration is higher than 53 g/m~3,the pressure drop decreases. The higher the inlet temperature is,the higher the average pressure drop of the system is. When the inlet temperature rises from 13 ℃ to 202 ℃,the pressure rises from 520.5 Pa to 941.5 Pa. The simulated pressure drops and outlet temperatures are in good agreement with the experimental results. Under the conditions of lower inlet temperatures( <300℃),the system pressure drop of dust collector is mainly affected by the surface pressure drop of the metal wirework filter bag. When the inlet temperatures increases,the pressure drop increases significantly. The pressure drop is approximately 3 000 Pa for the inlet temperature of 600 ℃,greatly higher than thesurface pressure drop of the bag filter. And thus the pressure drop of the structure of dust collector needs to be considered during the design of bag filter.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 8446K] - WANG Wenxia;ZHENG Zihan;ZHANG Xuan;QIAO Yu;XU Minghou;State Key laboratory of Coal Combustion,Huazhong University of Science and Technology;China Ship Development and Design Center;
In view of the treatment/disposal problem of coal fly ash,which is a solid waste with large output,wet milling method to synthesize zeolite was used to explore the high value utilization of fly ash as resource. Through the design of four factors,three levels orthogonal synthesis experiments,combined with the evaluation of cation exchange capacity,the best condition of synthesis of zeolite from fly ash under wet milling method was determined. In order to test the adsorption and removal effect of cation heavy metals of the zeolite synthesized by this method,the adsorption and removal of heavy metal Pb( Ⅱ) under nine orthogonal conditions were carried out,and the adsorption and removal of anionic groups with less attention under the orthogonal conditions were also studied. According to the average value and range of cation exchange capacity of different factors under different orthogonal conditions,the optimal combination to synthesize zeolite is Na OH concentration of 4 mol/L,liquid-solid ratio of 4 m L/g,grinding time of 24 h and rotating speed of 350 r/min. The range of cation exchange capacity demonstrates that the most important factor for zeolite synthesis is grinding time,followed by liquid-solid ratio and alkali concentration,and the speed of planetary ball mill has the least influence. The results of adsorption and removal of Pb( Ⅱ) by zeolite synthesized under the experimental conditions show that the adsorption of Pb( Ⅱ) is mainly physical adsorption,and the removal rate is more than 70%,up to 92.5%,which mainly depends on the cation exchange capacity of synthetic zeolite. The results of adsorption and removal of heavy metal Cr on the zeolite synthesized under the experimental conditions show that the adsorption and removal of heavy metal Cr is both physical and chemical adsorption. The adsorption and removal rate of Cr( Ⅵ) on the synthesized zeolites is up to 35.7%. The zeolite synthesized by wet milling method has certain adsorption and removal effect on heavy metal cations and anions.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 4250K] - HUANG Kun;YANG Wen;DING Xiaohua;NARI Technology Co.,Ltd.;
In order to improve the accuracy of energy consumption modeling and prediction in the cement production process,an integrated energy consumption prediction model for cement production based on neural network and Markov correction was proposed in this paper. In the data preprocessing stage,in order to reduce the scale of processing data,the average influence value method was used to reduce the data dimension,and the sensitive variables were filtered,six of the 12 variables that have a greater impact on the energy consumption output were selected to construct a 6-input single-output neural network,which made the energy consumption modeling stage selection. The structure of the neural network model is simpler,and could effectively reduce the time required to train the neural network. In the energy consumption modeling stage,in order to establish a better performance energy consumption model,the integrated learning idea was adopted on the basis of the neural network as the energy consumption modeling meta-learner,and several meta-learners were combined into a stronger performance. The average of the predicted output values of multiple neural networks was used as the prediction result of the integrated model. The dependent variables of the cement firing system and the corresponding furnace energy consumption value were used as experimental data for model training,verification and prediction. The experimental results show that the determination coefficient of the prediction results of the integrated model is improved by 0.019 compared with a single neural network. The mean value of the relative residual size between the predicted value and the true value is also reduced by 0.027 compared with the single neural network. The performance of the model is improved. In the energy consumption prediction stage,in order to further improve the prediction accuracy of the model,the Markov residual correction method is introduced,that is,the current predicted value is corrected based on the residual of the historical predicted energy consumption value and the actual energy consumption value to improve the prediction of the integrated energy consumption model accuracy. The experimental results show that the relative residual error of the predicted value corrected by Markov's correction method is reduced from-0.6% to-0.25%. The energy consumption predicted value is closer to the actual value,the prediction accuracy is significantly improved,and the law of electric energy consumption change and dependent variable of cement furnace firing system can be better excavated. The energy consumption is accurately predicted,which provides a more accurate reference basis for energy consumption supervision in the cement production process. Based on the description of the three stages of cement production energy consumption modeling,a cement production integrated energy consumption prediction model based on neural network and Markov correction is proposed in this paper,which has better prediction effects and higher prediction accuracy on cement production energy consumption.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 4179K] - KANG Running;WEI Xiaolin;BIN Feng;WANG Zibing;State Key Laboratory of High-Temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Science;School of Engineering Science,University of Chinese Academy of Sciences;Dalian National Laboratory for Clean Energy,Chinese Academy of Science;College of Metallurgy and Energy,North China University of Science and Technology;
CO,as one of the main atmospheric pollutants,comes from industrial furnaces,metallurgical industry and exhaust emission of motor vehicle,causing huge emissions of CO and serious environmental pollution. Currently,the catalytic combustion technology is an effective the mainstream technology to effectively limit and eliminate CO,which can realize low-temperature and high-efficiency conversion of CO by introducing catalyst. It has formed industrial application in low-temperature catalytic oxidation fields such as automobile exhaust emission and preferential oxidation of CO,and the effect is remarkable. The Cu-Ce complex oxide catalysts have attracted many researchers attentions due to its advantages of high efficiency at low temperature,long life and low cost,and widely used in the CO catalytic combustion. The research progress of CO catalytic combustion over Cu-Ce catalyst in recent years was reviewed,and the preparation methods,structure-activity relationship and carrier-active component interaction of Cu-Ce catalyst were summed up here. Based on the characterization techniques,in situ experiments and reaction kinetics models,the difference between various reaction pathways were discussed and the micro reaction mechanism of CO catalytic combustion was summarized. At the same time,according to the variation characteristics of CO concentration in different industrial waste gases,the relevant work progress in recent years carried out by high efficiency and clean combustion team from Institute of Mechanics,Chinese Academy of Science was introduced. Finally,the future development direction of CO catalytic combustion reaction is prospected. Taking the converter off gas( CO≤35%) produced during converter steelmaking process,the CO self-sustained catalytic combustion technology was proposed based on the CuCe_(0.75)Zr_(0.25)O_y and industrial honeycomb ceramic catalyst catalyst,and the rule of CO self-sustained combustion under a wide range of CO concentration( induction,flying hot temperature and self-sustaining stages),reaction paths( M-K and L-H mechanisms) and stable-combustion region( lean burn limit,steady temperature field and heat transfer characteristics) were established,which provided a feasible technical solution to realize two-way energysaving between the loss of converter gas from the gas ignition and its own energy recycling. The future research direction is also discussed:the research on CO catalytic combustion reaction mechanism can be further studied by the new efficient nano Cu-Ce catalyst,including a high utilization of active atom,lasting and efficient catalyst via a fine morphology of catalyst preparation method and large-scale production technology. It's good for investigating evolution rule of the support-active component interaction via advanced in situ characterization technology,simulating calculation method,and the quantitative study of CO adsorption-reaction-desorption reaction process is carried out.The catalyst is also encouraged to extend from laboratory to practical industrial application,in order to investigate various properties of catalyst for complex flue gas environment for a long time using. This analysis can be expected to enrich safety control theory of CO catalytic combustion and promote the development of energy saving and emission reduction.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 5654K] - LIU Hexin;YANG Fuxin;LI Zhenghong;TAN Houzhang;DU Yongle;FENG Peng;Key Laboratory of Thermo-Fluid Science and Engineering,Ministry of Education,Xi'an Jiaotong University;
The submicron particle agglomeration by atomized charged droplets is an effective method of multi-field synergistic agglomeration of fine particles. Many scholars have carried out a lot of theoretical and experimental studies on the characteristic of fine particle removal through charged droplets. However,few studies have been conducted on the study of fine particle agglomeration of atomized charged droplets with particle size diameter of about 5 μm. In this paper,a double-layer dielectric barrier discharge electrode was designed to effectively block the development of the discharge arc in the traditional corona discharge gap and charge the atomized droplets by producing a uniform and stable high-density low-temperature plasma. Meanwhile,an experimental platform of submicron particle agglomeration through the atomized charged droplets was built for the experimental study of electrode stability and agglomeration characteristics of fine particles. Three aspects of electrode volt-ampere characteristics,the influence of load voltage on the agglomeration efficiency,and the influence of water mist quantity on the agglomeration efficiency were compared and characterized. The results show that the structure of the double-layer barrier medium is beneficial to improve the uniformity of the gap between charged electrodes,and the existence of atomized droplets is beneficial to promote the discharge in air gap space. Both the initiation voltage and unstable operating voltage of charged electrode decrease with the increase of the water mist flow. When the water mist flow is 102.9 mg/min,the voltage range for stable operation is17.2-41.1 kV. The atomized charged droplets have obvious effect on the agglomeration of fine particles. The agglomeration efficiency of 30-70 nm particles can reach up to 40% under the action of 45.0 kV. With the increase of atomization amount,the particle size distribution curve moves towards the increase of particle size as a whole,which also indicates that the increase of atomization amount is conducive to the removal of fine particles by charged atomization droplets. Under the condition of the same voltage,the particle agglomeration effect is significantly improved with the increase of the water mist flow.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 9916K] - LI Xiaofeng;ZOU Jun;ZHANG Yang;WANG Zhining;ZHANG Hai;LYU Junfu;LIU Qing;ZHANG Shouyu;School of Energy and Power Engineering,University of Shanghai for Science and Technology;Shanxi Research Institute for Clean Energy Tsinghua University;Key Laboratory for Thermal Science and Power Engineer of Ministry of Education,Department of Energy and Power Engineering,Tsinghua University;
SCR and SNCR technology are commonly used to reduce NO_x emission of aluminum hydroxide gaseous suspension calciners(GSC). However,due to the problems of contamination on catalyst and ammonia slip,it is urgent to develop a new scheme to reduce NO_x emission. Fuel gas recirculation and air staged combustion are potential approaches to reduce NO_x emissions of aluminum hydroxide GSC.However,the effects of fuel gas recirculation and air staging on operating parameters of GSC are still unclear. In the present study,taking a 3 000 t/d aluminum hydroxide GSC as the research object,the effects of the flue gas recirculation and air staging on the GSC operating parameters were investigated. It is found that when the flue gas recirculation rate is 20%,the total excess air ratio of the system is reduced to about 1.1,which can maintain a large primary air volume,ensure the suspension roasting state,and make the lower part of the main roasting furnace( P04) achieve a reductive atmosphere,thus inhibiting the formation of NO_x. The changes in the separation efficiency of each cyclone in GSC caused by the flue gas recirculation and air staging ware negligible when the flue gas recirculation ratio are below 20% and the over fire air ratio of the air staged combustion are below 25%. The flue gas recirculation and air staged combustion result in a decrease of the calcination temperature if the fuel distribution is not well adjusted,which may have adverse effects on the quality of alumina products. However,by optimizing fuel distribution of the GSC calciner,the influence of flue gas recirculation and air staging on operating parameters can be largely reduced. When the flue gas recirculation ratio reaches 20% and the over fire air ratio reaches 25%,the lower part of the main furnace of the GSC calciner can achieve a reductive atmosphere while the aluminum hydroxide calcination temperature and overall thermal efficiency are still ensured,which provides the necessary condition for the low-NO_xcombustion design of the GSC process.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 4550K] - ZHU Shujun;ZHU Jianguo;LI Jiarong;LIU Jingzhang;Institute of Engineering Thermophysics,Chinese Academy of Sciences;State Key Laboratory of High-temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Sciences;University of Chinese Academy of Sciences;
A high-temperature vertical tube furnace experimental system,capable of real-time monitoring the sample quality,was built in this study. The combustion reactions of pulverized coal and the decomposition reactions of calcium carbonate( CaCO_3) can be performed simultaneously,and the mixed reaction characteristics can reflect the real situation in the precalciner. During the operating temperature range of 900-1 000 ℃,the variations in temperature had little effect on the combustion reactions of pulverized coal,but the temperature became an important factor affecting the CaCO_3 decomposition at lower temperature. With the mass ratio of CaCO_3 in the mixture increasing,the reaction rate was more sensitive to temperature. The BET( Brunauer,Emmett and Teller) specific surface area of decomposition product was largest when the mass ratio of coal to CaCO_3 was approximately 1 ∶ 9. The kinetic analysis of the experimental data shows that the reaction kinetics model of the mixture was different in different mass ratios. The activation energy value decreased with the increase in the mass ratio of coal to CaCO_3,and so did Arrhenius constant. To ensure the high decomposition ratio of CaCO_3 and the high combustion efficiency of coal in the cement precalciner,it is necessary to control the mass ratio of coal to CaCO_3 being higher than 1 ∶ 9. The activation energy data obtained from this study can provide support for the later simulation calculation of the precalciner.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 22897K] - YAN Quanying;LYU Yifan;PAN Lisheng;WEI Xiaolin;LI Bing;School of Environment and Energy Engineering,Beijing University of Civil Engineering and Architecture;State Key Laboratory of High-temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Sciences;
With the continuous global warming trend,reducing carbon emission from industry is imminent. In the production process of cement clinker,a large amount of tail gas in which consist over 30% CO_2 is emitted from the cement kiln. Therefore,it will contribute greatly to capture CO_2 from tail gas of cement kilns for carbon emission reduction of industrial field. Taking two ionic liquids,[M_4Gu]Ac( tetramethylguanidine acetate) and [TMG][Lac]( tetramethylguanidine lactate),as research objects,the absorption characteristics of pure CO_2 and CO_2 in simulated tail gas of cement kiln tail gas at 30 °C,50 °C and 70 °C were investigated. The results show that the maximum absorption capacity for pure CO_2 and CO_2 in simulated flue gas from cement kiln tail by ionic liquids decreases greatly with the increase of working temperature. The maximum absorption capacity of the two ionic liquids at 70 ℃ is 50% less than the maximum absorption capacity of the two ionic liquids at 30 ℃ . The absorption effect of [M_4Gu]Ac and [TMG][Lac]on CO_2 in simulated tail gas of cement kiln is obviously worse than that of pure CO_2. The maximum absorption of CO_2 by the two ionic liquids is only 22.3% and 20.9% of that of pure CO_2 under the same conditions. The five times absorption and regeneration cycle experiments of two kinds of ionic liquids were carried out at 70℃ . The results show that the absorption properties of the two ionic liquids are basically stable in five experiments,and the regeneration times have little effect on the CO_2 absorption capacity of the two ionic liquids.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 3365K] - PAN Lisheng;YANG Huan;LI Bo;WEI Xiaolin;CHEN Hongdi;SHI Weixiu;State Key Laboratory of High-temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Sciences;School of Environment and Energy Engineering,Beijing University of Civil Engineering and Architecture;
The energy consumption is very huge in metallurgical industry,and the rare earth smelting process has the same characteristic.When smelting rare earth metals by molten salt electrolysis,a large amounts of heat is released from the side wall and the upper surface of the smelting electrolyzer,producing some acid gas during the smelting process together. In the process of rare earth smelting,a large amount of waste heat is lost in the electrolytic cell by means of radiation and convection heat transfer. A rare earth smelting simulation experimental cell was built,and a similar temperature field in the cell was obtained by using coal-fired heat release. The cooling water was used to conduct convection heat transfer with the side wall of the simulated electrolytic cell and radiation heat transfer with the high temperature radiation surface of the simulated electrolytic cell. The experimental study on heat transfer of tank wall and top radiation in rare earth smelting process was carried out. The results show that the heat transfer rate in the side wall increases with the increase of the mass flow rate of cooling water and the influence of water flow rate on the heat transfer of tank wall is stronger than that of the distance between the radiant heating surface and the top surface of the simulated tank. In the experiments,when the distance between the radiation absorbing surface and the upper surface of the simulated electrolyzer is 0.2 m and the mass flow rate of the cooling water is 0.285 kg/s,the maximum heat transfer rate in the side wall is 2.256 kW. The capacity of the recovered radiation heat is greatly affected by the distance from the radiant absorbing surface and the top of the smelting groove and increases with decreasing the distance. With the distance of 0. 1 m and the mass flow rate of 0.292 kg/s,the recovered radiation heat reaches up to 19.541 kW and the total heat transfer rate is 21.114 kW. Based on the experimental data,the practical capacity of the recovered radiation heat and total heat deduced are 52.796 kW and 83.237 kW. The total heat recovered accounts for 55.5% of the total electricity consumption of the smelting process. The above results can be used to supply reference for developing energy saving technology and realizing reasonable utilization in rare earth smelting plant.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 5342K] - SONG Jialin;CHENG Xingxing;SUN Rongfeng;WANG Zhiqiang;GENG Wenguang;ZHANG Xingyu;ZHAO Gaiju;YUAN Dongling;WANG Luyuan;School of Energy and Power Engineering,Shandong University;Energy Institute of Shandong Academy of Sciences,School of Energy and Power Engineering,Qilu University of Technology (Shandong Academy of Sciences);Energy Afficiency and Low Carbon Engineering Laboratory of Shandong Pronvice;
In response to solve serious problems of air pollution,China has accelerated the implementation of the " coal-to-gas" policy in recent years. Coal-fired boilers have been gradually replaced by gas-fired boilers. It is important to develop and design the new low-nitrogen gas burners. In response to the national call of " low nitrogen and environment protection",a new micro flame low nitrogen burner was proposed. Numerical simulation method was used to optimize the corresponding aperture structure of the burners,and on this basis,the combustion conditions were simulated to select the optimal combustion conditions. The results show that as the air inlet diameter increases from 16 mm to 22 mm,the air flow rate slows down due to the diameter increase,the combustion time of the mixed reaction of gas methane and air becomes longer,and the combustion releases more heat. When the diameter continues to increase,because the small flame has a larger heat dissipation area and the heat is dissipated to the surroundings,the temperature in the high-temperature area at the center of the flame first increases and then decreases. The burner burns clean fuel methane,and the produced NO_x is mainly thermal NO_x that is greatly affected by temperature. Therefore,the amount of NO_x generated first rises and then falls. With the increase of excess air from 1.1 to 1.4,the high temperature area in the center of theflame obviously decreases,the temperature also decreases from 2 270 K to 2 042 K. As the temperature in the high temperature zone in the furnace decreases and the residence time of air in the high temperature zone becomes shorter,the production of NO_x decreases from 412 mg/m~3 to 52 mg/m~3. In conclusion,the new low nitrogen burner has a good combustion effect and can effectively reduce NO_x emission. Moreover,when the methane inlet diameter is designed to be 2 mm,the air inlet diameter is designed to be 16 mm,and the excess air coefficient is set to be 1.4,the new low-nitrogen burner can achieve low NO_x emission.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 8285K] - CHENG Mingkai;LI Chen;FU Jianhong;FENG Chao;XU Minghou;QIAO Yu;State key laboratory of coal combustion,Huazhong University of Science and Technology;
Smoldering is a new type of low calorific value organic solid waste heat treatment technology. According to the characteristics of sludge smoldering ash,the self-sustaining smoldering test ofsewage sludge( SS) was carried out to provide technical support for the promotion of smoldering disposal technology of SS. Based on a lab-scaled smouldering reactor,self-sustaining smoudering of SS was achieved with parameters of 50% water content of SS,3.5 cm/s of air Darcy flow rate,( wet) SS and sand mixing ratio of 1 ∶ 4. The process characteristics of SS self-sustaining smoldering treatment were analyzed by smoldering temperature curve. The mass lose profile was also calculated based on the temperature records and the basic properties of the raw SS. To compare with combustion and pryolysis,the SS was also sent to burn at 1 000 ℃ and pryolyzed at 500 ℃,followed by collection of the smouldering ash( ASH-1),combustion ash( ASH-2),and pryolysis produced char( CHAR). BCR sequential extraction method was then applied to study the occurrence forms of major elements( Na、K、Mg、Ca、Al、Fe、P) and trace elements( Zn,as,Cr,Cd,Pb,Ni,Cu) in the three residue samples. The study shows that the smouldering treatment can be divided into four periods: preheating,ignition,self-sustaining smouldering,and extinguishing; the highest temperature is678 ℃ of the bottom material combustion peak temperature in the ignition stage,and and the average temperature of the self-sustaining smoldering process is 517 ℃ . The median moving rate of burning front is 0.37 cm/min,and the average mass losing rate is 10.41 g/min during self-sustaining smouldering; the dominating mineral element in ASH-1,ASH-2,and CHAR,is Si,and the main trace elements are Zn,Pb,and Cr; Na,K,Al,Fe,P,and As、Cr、Cd、Pb in the three residues are dominated in residue form; the content of acid soluble form of Na,K,Mg,Ca,and Zn,As,Ni in ASH-1 are higher than those in ASH-2 and CHAR. Therefore,the further disposal of ASH-1,ASH-2,and CHAR in practice should take the differences of the occurrence forms of the inorganic elements into consideration.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 3985K] - LI Zhenghong;LIU Hexin;YANG Fuxin;FENG Peng;TAN Houzhang;Key Laboratory of Thermo-Fluid Science and Engineering,Ministry of Education,Xi'an Jiaotong University;
The emission of submicron particles in coal-fired industry will harm the environment and human health,and the agglomeration method is one of the main means for removing sub-micron particles. In this work,an experimental platform for the turbulent agglomeration of submicron particulates was built. The Scanning Mobility Particle Sizer( SMPS) was used to measure the concentration of the inlet and outlet particulates. The effects of different disturbing structure arrangement on the submicron particulates turbulent agglomeration efficiency were studied. Moreover,the effects of flow field on particulate agglomeration efficiency were further analyzed by Fluent software. The results show that the turbulent agglomeration efficiency of micron particles is related to the particle size. The agglomeration efficiency of submicron particles with smaller particle size is better than that of submicron particles. the agglomeration efficiency of small particulates( particulates size <30 nm) is from 10% to 90%,but it is less than 10% for large particulates( particulates size >30 nm),and when the particle diameter is greater than 502 nm,the agglomeration efficiency becomes negative at different flow rates; according to the analysis of flow velocity,it is found that the agglomeration efficiency of sub-micron particles increases first and then decreases with the flow velocity,which is caused by the intensity of turbulence in the turbulence zone and the residence time of particles. What's more,when exploring the influence of the arrangement and arrangement of the spoiler on the agglomeration efficiency,the agglomeration efficiency of sub-micron particles decreases with the increase of the spoiler,and gradually decreases with the increase of the lateral spacing of the spoiler,first becomes larger and then decreases with the increase of the longitudinal spacing,and increase with the increase of the number of rows. The effects of the disturbing structure on the agglomeration efficiency are mainly influenced by the strength and length of the vortex. The strength of the vortex street promotes the collision probability of particles,and the length of the vortex street can increase the residence time of the particles in the turbulent zone,thereby increasing the agglomeration efficiency.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 14684K] - FENG Peng;SHENG Hu;ZHOU Hu;WANG Chengliang;LIU Hexin;LI Zhenghong;TAN Houzhang;YANG Fuxin;Key Laboratory of Thermo-Fluid Science and Engineering,Ministry of Education,Xi'an Jiaotong University;Huadian Zhangqiu Power Generation Co.,Ltd.;
Submicron particles are one of the important sources of air pollutants,which are harmful to human health. Turbulence agglomeration is a promising technology to remove submicron particles from coal-fired flue gas. Based on the k-ε turbulence model and the discrete phase model( DPM),a numerical model of the agglomeration process of submicron particles that is affected by the turbulence effect and Brownian motion was established on the basis of the experimental platform of submicron particles turbulence agglomeration. The model was verified by the experimental data. The influences of the inlet velocity,the arrangement and the shape of the vortex generators on the agglomeration characteristics of particles were studied. The results show that the main areas of collision and aggregation are the windward side of the generator and the longitudinal wake area of the generator. The agglomeration efficiency of small particle size is significantly higher than that of large particle size,and the agglomeration efficiency is negative at 593.5 nm particle size. At different flow rates,the agglomeration efficiency of PM_(0.1) is higher than that of PM_1 due to the stronger following ability of smaller particle size in the vortex.The inlet velocity of the device should not be too large to ensure the required residence time of particles. The maximum agglomeration efficiency of the tripod staggered generator used in the simulation is observed when the velocity is 5 m/s. The agglomeration efficiency of submicron particles in the sequential and staggered structures is not different,but the interaction mechanism of the sequential and staggered structures on submicron particles is quite different. The vortex street in the wake area of the sequential structure spoiler has been fully developed. The staggered structure contains more windward faces,which increases the probability of particle collision,but it is more vulnerable to particle erosion. In addition,under the condition of a single generator,due to the stronger vortex generation capacity of Y-shaped spoiler,it has better turbulent agglomeration effect than the cylindrical and triangular generator.
2020 05 v.26;No.129 [Abstract][OnlineView][HTML全文][Download 10703K] 下载本期数据