2019年05期目次

  • Present situation analysis and prospect of classification and utilization of lignite pyrolysis at low temperature

    DING Xiaoxiao;LI Hongjuan;WANG Yatao;Coal Chemical R&D Center of Kailuan Group;

    The China's energy situation of " rich coal,poor oil and little gas" determines that China will still be dominated by coal for a long time. Medium and low grade coal accounts for more than 50% of the total proven reserves of coal. In order to make full use of medium and low grade coal( such as lignite) resources of China effectively,the distribution characteristics and physical characteristics of lignite resources in China,as well as the technology of drying,dehydration,compression molding and low-temperature pyrolysis processing and utilization were analyzed in the paper. The research status of low-temperature pyrolysis technology of lignite was emphatically reviewed,and the widely used pyrolysis technology of solid heat carriers,and the gas heat carriers and gas-solid heat carriers were summarized. Moreover,the reactors,types of heat carrier,application,feedstock,production,and degree of industrialization of the typical upgrading lignite pyrolysis techniques at home and abroad were also compared. Furthermore,the key technology issues of lignite upgrading and utilization including products with low-added value,low tar yield,waste heat recovery,and dust treatment were pointed out. The prospect of lignite pyrolysis and classification refining technology in the future was also discussed. In addition,it was necessary to extend the product chain by improving the added value of tar and other pyrolysis products,co-pyrolysis with other materials,design and development of reactor,the higher utilization rate of oxygen and other elements in lignite through process adjustment,and large-scale development. Finally,the suggestions of comprehensive utilization of low rank coal lignite in the future were pointed out. The ignite pyrolysis technology and the existing coal gasification,liquefaction,MTO and MTP coal chemical technology should be integrated. A variety of high value-added clean fuels,chemical raw materials and heat energy,electric power are obtained by setting the appropriate product objectives and designing reasonable technology route.The lignite industry chain should be effectively extendyed to realize the classification and quality utilization of low-grade coal,and promote the structural adjustment and optimization and upgrading of China's coal industry.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 1268K]

  • Research progress on the control of SO2 oxidation rate over vanadium based denitrification catalyst

    LI Wenhua;YIN Shunli;JIN Zhennan;XUE Dongwu;ZHOU Wen;ZHAO Huimin;Zhejiang Zheneng Wenzhou Electric Power Generation Co.,Ltd.;Zhejiang Zheneng Catalyst Technology Co.,Ltd.;

    Sulfur trioxide is one of the key pollutants in the flue gas of coal-fired units,which has an important influence on the stable operation,air quality as well as human health. In this paper,the research results about control of SO_2 oxidation over commercial SCR denitrification catalyst were summarized,including physical methods such as pore structure adjustment,isolation layer,wall thickness reduction and morphology adjustment,as well as chemical methods such as carrier,auxiliary agent,active component and surface acidity optimization.Due to the influence of kinetic factors( diffusion control),the denitrification reaction only occurs within the thickness of catalyst surface( denitrification area) of 75-100 μm,while the SO_2 oxidation reaction can occur within the whole wall thickness( area),so reducing the number of active components involved in the SO_2 oxidation reaction is the main technical content of the physical scheme. In vanadium denitration catalyst,the active component of V2 O5 can selectively catalyze the reduction of NOx,can also be the catalytic oxidation of SO_2 to SO3,and regulate the interaction of active component and carrier,and make the NH3 and SO_2 in the catalyst surface to form competitive adsorption,inhibit the catalyst for SO_2 adsorption,and reduce the redox capacity of the active species,which is an effective method of chemical solutions. The physical scheme is more suitable for plate denitrification catalyst,while the chemical scheme has no special requirements for catalyst structure,and the chemical scheme has better technical effect than the physical scheme. Based on the fact that denitrification belongs to a gas-solid heterogeneous catalytic reaction system,the catalyst formulation and physical structure were optimized and adjusted from the perspectives of the diffusion,adsorption,redox reaction of ammonia,SO_2 and other reactant,so as to achieve the balance between the denitrification activity K( NOx) and the oxidation activity K( SOx) of SO_2. In the development of commercial denitrification catalyst with low SO_2 oxidation rate,the influence of diffusion,adsorption,redox ability and other factors on the performance of the catalyst can be comprehensively considered. Meanwhile,the various schemes are adopted to modify the catalyst to significantly reduce the SO_2 oxidation rate of the catalyst under the condition of ensuring the denitrification performance of the catalyst. Under the requirement of ultra-low emission of coal-fired units,the amount of denitrification catalyst used or the content of active components in catalyst increased significantly,and the oxidation rate of SO_2 by denitrification system increased from 1% to 1.5%. At the same time,the oxidation rate of SO_2 of the new denitrification catalyst should be reduced by more than one third considering the pressure of SO3 removal by the back-end treatment equipment under the requirement of ultra-low emission.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 566K]

  • Research progress on direct blending biomass in pulverized coal fired boilers of large power plants

    LIU Jiali;WANG Zhichao;DENG Fengjiao;TU Jingyi;FANG Shunli;Xi'an Thermal Power Research Institute Co.,Ltd.;Xi'an Yitong Thermal Technology Services Co.,Ltd.;

    In order to improve the safety and economy of the direct blending biomass in large pulverized coal boilers,the differences of coal quality and combustion performance between typical biomass and coals were analyzed,and the influence of biomass blending on equipment adaptability and operation of main and auxiliary boilers was discussed comprehensively in this paper. Meanwhile,typical combustion modes and characteristics of directly blending biomass at home and abroad were comprehensively studied. The results show that the biomass had the advantages of high moisture,low density,high Vdafand oxygen,low sulfur,which has excellent environmental protection performance.When the large-scale pulverized coal-fired boiler is mixed with biomass,the influence on operation and the adaptability with auxiliary equipment need to be considered,especially the total moisture,calorific value,ash melting temperature,alkaline oxides such as Fe2 O3,Ca O,MgO and K2 O in ash composition on fuel preparation,storage and transportation,boiler efficiency,output of pulverizing system,load capacity and boiler slagging,fouling and corrosion and so on. Generally,the blending 5%-10% formed biomass has no significant impact on the operation of the boiler,combustion system,pulverizing system and other auxiliary systems,through the optimization of biomass types. Considering the technical feasibility,economy and operation safety,it is more economical to adopt independent combustion process2,i.e. to use the standby pulverizing system of boilers to realize the independent combustion of biomass. In order to prevent burning-out of biomass burner,it is required that the inlet air temperature of biomass mill should be less than 100 ℃ to ensure the primary air temperature of the mill outlet lower than 50 ℃,and 40-45 ℃ is appropriate. The co-grinding blending process can be considered when the biomass ratio is low or the blending time is short,but the spontaneous combustion of biomass needs to be controlled strictly to ensure the safety of biomass blending. Therefore,the safe operation of large-scale pulverized coal power plant boilers when blending directly with biomass can be guaranteed by optimizing the types of biomass,appropriate blending mode,blending proportion control and optimization of operation parameters. Blending biomass directly on large capacity and high parameter pulverized coal boilers has the advantages of less investment,less area covered,less or zero equipment modification,high thermal efficiency and no seasonal influence,while the main reason that restricts its large-scale application is the precisely measurement without human involvement at present.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 1372K]

  • Research progress and prospect of pulverized fly ash in rubber

    WANG Tingwei;ZHENG Zhengqi;HE Xingyang;LIU Yongming;School of Civil Engineering,Architecture and Environment Science,Hubei University of Technology;Hubei Province Building Water proof Engineering Research Center,Hubei University of Technology;Shanxi Shanming Environmental Protection Technology Co.,Ltd.;

    Fly ash is a waste powder material for thermal power plants. Carbon black is the main reinforcing filler used in rubber products,which is derived from petroleum and coal related industries. But from the perspective of energy conservation and environmental protection,the production of carbon black must be reduced. Due to the similar properties of fly ash and carbon black,fly ash can be used as a substitute for part of carbon black in rubber reinforcements. In this paper,the research progress of fly ash filled rubber reinforcing materials was discussed,including direct filling,physical separation,chemical extraction and surfactant modification. At the same time,the industrial application of fly ash in rubber filling materials was pointed out. In addition,the method of extracting reinforcing materials from fly ash for rubber,the treatment method of filling rubber,and the research direction of industrialization were prospected. The results show that the direct filling of fly ash will result in poor dispersion and less dosage. Although the chemical purification can improve the product quality,the purification process is complicated. The ultra-fined particles obtained by the physical modification method have the problem of dispersion.The wet modification method in the mechanical chemical modification method is more effective,but the production efficiency is low. And it needs to be used after drying,which makes it difficult to achieve industrialization. At present,the industrial applications of fly ash filled in rubber materials mainly include pressure rubber tubes,flame retardant rubbers,chlorinated polyethylene hoses,etc.,and there are some limitations in the application range. In order to realize the large-scale application of fly ash in rubber products,it is necessary to solve the above application problems and combine various modification methods to improve the modification effect and efficiency. For example,when combined with physical modification method,ball milling,ultrasonic time and the energy consumption should be reduced. When combined with chemical modification,a low-cost coupling agent can be introduced to enhance the modification effect and efficiency to find a low-cost,high value-added modified fly ash method.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 1244K]

  • Research progress on low tar fixed bed gasification

    ZANG Xuejing;CHEN Yafei;DONG Weiguo;DU Gang;GUO Liangyuan;China Coal Research Institute;State Key Laboratory of Coal Mining and Clean Utilization;Coal Chemistry Branch of China Coal Research Institute;

    With the increasingly strict requirements of environmental protection,the environmental problems caused by the fixed bed gasification tar have become a bottleneck for restricting the development of fixed bed gasification technology,and low tar gasification should be paid more attention to. This paper introduces the approach and influencing factors of low tar gasification in fixed bed gasification,analyzes the influence of various technological conditions on tar yield,and expounds the principle of reducing tar in two-stage gasifier,downdraft gasifier and two-stage air supply gasifier. It is more common to combine downdraft gasifier with two-stage gasifier to produce low tar content,high gas heat,low heat loss rate in the furnace,which is mostly used for biomass gasification technology development. The throat structure can not only increase the gas velocity,but also increase the temperature in the blast furnace and promote tar cracking in the furnace. Gasification raw materials,particle size,gasification process( gasification final temperature,pressure,gasification agent,catalyst,etc.) are important factors of affecting the yield of tar. The high volatile gasification raw materials( low rank coal,biomass,etc.) produce more tar,and the content of low volatile high rank coal tar is very little. The particle size affects volatile analysis precipitation and heat transfer,which affects tar yield. The influence of temperature mainly lies in tar cracking. When the tar cracking occupies the main reaction position of cracking reaction,the yield of tar gradually decreases with the rise of temperature. Therefore,some catalysts and subsequent de-tar technology need to reduce the tar content according to the thermal cracking effect of temperature on tar. Increasing pressure will inhibit volatile analysis,which is conducive to reducing tar. The suitable amount of water vapor can reduce tar content,and increase the hydrogen content,but will reduce the gasification temperature,and the quantitative parameters need to be adjusted. Various catalysts can effectively reduce the tar content and change the heat value of gas,but the strict catalyst reaction conditions will increase the cost of gasification. The realization of low tar gasification is an important breakthrough in fixed-bed gasification technology,which can not only improve the utilization rate of low-rank coal,but also solve the problem of high volatile biomass and urban waste gasification,and generate clean new energy. The content of tar in gas is reduced,the effective gas composition is increased,which can alleviate the problem of low heat value of gasification raw material.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 3204K]

  • Distribution characteristics and development and utilization prospect of lithium gallium aluminum in Shanxi coal system

    LIU Hanbin;MA Zhibin;GUO Yanxia;CHENG Fangqin;Institute of Resources and Environmental Engineering,Shanxi University;Shanxi Coal Geological Bureau;

    The coal-associated metal minerals refer to metal minerals with the industrial value or industrial utilization prospects in coal mining that are co-produced or associated with coal in coal-bearing strata. Shanxi is a large coal province in China,which has abundant coal resources and huge reserves. The annual coal output accounts for about 25% of the national annual coal output. The annual thermal power generation accounts for more than 90% of the total power generation in the province. The Shanxi coal and coal-based solid waste contain a large number of the metal minerals for industrial development and utilization,such as lithium,gallium and aluminum in coal. However,there is no research on the distribution of the associated metal minerals in Shanxi coal from the perspective of the province,which greatly limits the strategic development of the coal-related companion minerals from the macro policy level. Based on the existing research data of lithium,gallium and aluminum in Shanxi coal-bearing strata,the distribution characteristics and metallogenic prospects of lithium,gallium and aluminum in Shanxi coal system were analyzed and discussed. It is believed that the lithium content in Taiyuan Formation coal in Shanxi coal is significantly larger than that in Shanxi group,while the aluminum and gallium is smaller than that in the Shanxi group. The content of lithium gallium in coal seam gangue is significantly larger than that in coal seam. In Shanxi Ningwu Coalfield Pingshuo mining area,Qinshui coalfield Jincheng mining area,Huoxi coalfield Huozhou mining area,Xishan coalfield Gujiao mining area,Taiyuan Formation main coal seam and the gangue of Xishan coalfield,the Lithiumhas good mineralization potential for coal-related associated lithium; The abnormally high values of gallium and aluminum in Shanxi coal are common,and the gallium and aluminum widely are distributed in the central and northern parts of Shanxi Province,and decrease from from north to south as a whole. The Shanxi coal-based resources of lithium-gallium-aluminum have huge reserves of the fly ash and high-alumina coal gangue in Shanxi Power Plant,which has good prospects for industrial development. It is urgent to demarcate the boundary grade and minimum industry grade of lithium and gallium in coal seams and lithium and in Shanxi fly ash in order to achieve resource recycling and high value utilization. As two special mineral resources,the comprehensive utilization of fly ash and coal gangue should be made from the source to the top layer design,according to local conditions,classify and classify cascade utilization.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 2285K]

  • Experimental study on factors affecting the mechanical strength of coal pellets

    WANG Zixiang;FU Liangliang;SONG Ruiling;PANG Mingjin;XU Wenbo;WANG Chao;LAN Tian;The Research Center for Clean Coal Technology & Engineering,Yankuang Group;Yankuang Technology Co.,Ltd.;

    The low utilization efficiency of civil bulk coal and the large amount of pollutants produced in the combustion process are also one of the important reasons for haze. Promoting clean briquette is an effective way to control bulk coal. In order to study the optimum preparation conditions of rod-shaped coal pellets,with Pulverized Coal from the Nantun coal mines of Yankuang Group as raw material,the0-5 mm raw coal powder was prepared by hammering pulverizing system,and the ZLSP200 A flat die pelletizer was used to produce rodshaped coal pellets. The effects of raw material moisture,particle size distribution,mold taper angle and binder type and amount on crushing strength of rod briquette were experimentally studied. The results show that the moisture in the raw coal can wet the surface of pulverized coal particles and a stable bridge force is formed between pulverized coal particles during extrusion forming process. It also plays a lubricating role. When the moisture content of the raw coal is 15%,the briquetting process is smooth,and the initial strength of rod briquette is the highest. The too low moisture content cannot form or plug the die holes,and the too high moisture content cannot meet the storage and transportation requirements of rod briquette due to insufficient initial strength,deformation,adhesion. When the particle size distribution modulus( Gates-Gaudin-Schutzmann equation) is less than 0. 3,it can be found by electron microscope that fine-grained pulverized coal is compactly filled between coarse-grained pulverized coal,and the contact between pulverized coal particles is close,and the bridging force and meshing force between particles are strong,the strength of rod briquette reaches over 90%. It was found that although the pellets strength of rod-shaped briquette increases slightly with the mold cone angle,but the change of cone angle will lead to the increase of the component force of roller pressure in the direction perpendicular to the cone surface,and the component parallel to the cone becomes smaller and the friction is increased in forming process. With the increase of energy consumption and die wear,the briquette crushing strength and production smoothness should be taken into account in production,and the optimum mold cone angle is 16 degrees. Theuse of the binder can greatly improve the strength of the pellets,the best performance-price ratio is between 2% and 3%. From the TG curves of rod-shaped coal pellets with different binders,it can be seen that the organic binders can reduce the burning point of rod-shaped coal pellets and promote combustion process. Inorganic binders can increase the burning point of rod-shaped coal pellets,reduce the burning rate,increase the burnout temperature,increase the ash content,decrease the ash melting temperature and inhibit the combustion process. Considering the costs and its effects on pellets energy content and thermal stability,the comprehensive analysis about the binder type and adding amount are recommended.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 13675K]

  • Effect of lignite modification on its surface properties and pulping properties

    LIU Jinqiu;LYU Xiangyang;ZHANG Shengju;ZHANG Xiaoyu;China Coal Technology & Engineering Group Clean Energy Company Limited Department;

    The East Mongolia Shengli lignite,with the properties of high porosity,abundant oxygen functional groups on the surface,difficult storage and transportation and poor slurry properties,was modified with the anionic paraffin emulsion,and the change of the surface properties and the pulp properties of the modified lignite were studied. The thermo-gravimetric characteristics of the air dried lignite( ADL) and the modified air dried basis( BADL) of lignite was studied by thermo gravimetric analysis( TG). The change of surface functional groups,specific surface area and pore structure of dry basis lignite dried by hot wind and modified dry basis lignite were studied by X-ray photoelectron spectroscopy and nitrogen adsorption specific surface area test. The pulping property of lignite before and after modification was studied by slurry forming test. The results show that after the ADL modified by the anionic paraffin emulsion,the absolute mass change rate of BADL is less than that of ADL at the temperature range from 50 to 150 degrees centigrade. When the temperature is 117. 82 degrees,the absolute value difference is the maximum 0. 34%/min. When the DL is modified by anionic paraffin milk,the content of the surface inorganic oxygen is reduced from 0. 64% to 0. 20%,and the content of CO and COO— decrease from 13. 93% and12. 22% to 13. 11% and 12. 03%,respectively. The specific surface area changes from 8. 790 m2/g to 14. 995 m2/g; the pore volume decreases from 0. 041 cm3/g to 0. 032 cm3/g,and the average pore size decreases from 32. 697 nm to 17. 054 nm. The coal water slurry viscosity is less than 1 300 m Pa·s,and the liquidity is better than B-( 12 cm) as the standard,the modified lignite is pulped with fractal gradation process,and the maximum pulp concentration can reach 60. 59%. Compared with the single stick grinding process before the unmodified coal,the maximum slurry concentration increases by 10 percentage points,The apparent viscosity decreases from 1 059 to682 m Pa·s,which improves the stability of coal slurry.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 3323K]

  • Study on characteristics of the dense phase transportation of pulverized coal pressure

    FANG Xinhui;AN Haiquan;LIU Zhen;FENG Ziyang;PENG Baozi;WANG Yonggang;School of Chemical and Environmental Engineering,China University of Mining & Technology(Beijing);National Institute of Clean-and-Low-Carbon Energy,Beijing;

    As the upstream system of coal gasification process,the dense phase conveying of pulverized coal at high pressures directly affects the stabilization,reliability and safe operation of gasifier. The conveying characteristics of pulverized coal may be accordingly changed when the coal type of gasification is changed or blended with other types,which has a certain impact on the smooth operation of the pulverized coal conveying process. To study the operating characteristics of coal-providing system for a coal gasification unit,based on the mixed raw materials of a coal gasification unit,the characterization experiments were conducted on the powder fluidity through HR index and FF function. Then,the dense phase conveying experiments were done in the pipeline with inner diameter of 25 mm and 15 mm pipeline under the back pressure of 2,4 and 5 MPa.The influence law of the superficial gas velocity,and back pressure on the pulverized coal flow was discussed. Finally,the average fluctuation and maximum fluctuation of mass flow rate of the pulverized coal were used as evaluation index of stability for the pulverized coal conveying process and the fluctuation correlation between the various process parameters was compared and analyzed. The results show that the HR index of the raw coal is 1.42 and the FF function is 2-4. Combined with the fluidity classification table,the fluidity of the pulverized coal is located in the bonding area,but close to the easy fluidity area. With the increasing of superficial gas velocity,the mass flow rate of the pulverized coal first increases and then decreases,reaching the largest flow at the critical gas velocity. The pressure drop of particle phase decreases because the gas-phase pressure drop occupies the main body and the mass flow rate of pulverized coal starts to decrease after the apparent gas velocity exceeding the critical gas velocity. The back pressure has certain influence on the mass flow rate and flow-pattern transformation of pulverized coal. At the same superficial gas velocity,the back pressure increases and the pulverized coal flow has a downward trend,which is more obvious in the small pipeline with inner diameter of 15 mm. The higher the conveying pressure is,the more rapid the transition from dense phase to dilute phase is. According to the conveying phase diagrams of back pressure 2 and 4 MPa,the curvature of the phase diagram curve under 25 mm pipe diameter is about 2 times of that of the curve under 15 mm pipe diameter at the critical gas velocity. The average fluctuation and maximum fluctuation of mass flow rate of the pulverized coal can be used as evaluation criteria for transportation stability. Within the experimental range,the average fluctuation range of mass flow rate is less than 3%,and the maximum fluctuation range is less than 10%; the maximum fluctuation range of pulverized coal flow is about 3.4 times of the average fluctuation range,and the correlation coefficient between the two is 0.948.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 7889K]

  • Solvent extraction rules of heavy aromatics in products generated by hydrogenation of coal tar

    ZHAO Yuan;WANG Guangyao;Coal Chemistry Branch of China Coal Research Institute;State Key Laboratory of Coal Mining and Clean Utilization;

    In order to study the solvent extraction law of heavy aromatic hydrocarbons in coal tar,the experiment of single solvent,compound solvent,single stage extraction and multistage extraction were carried out with the fraction of 220 to 270℃in products generated by hydrogenation of coal tar as raw material.The results show that N,N-dimethylformamide(DMF)has the best solubility for aromatics among the six kinds of single extractants,the distribution coefficient of heavy aromatics is as high as 0.28,and the content of aromatics in the residual phase decreases from 40.00%of raw materials to 10.65%.Although the distribution coefficient of heavy aromatic hydrocarbons extracted by dimethyl sulfoxide(DMSO)is equivalent to that of sulfolane(SULF),the separation factor is as high as 75.00%,whichhas good selectivity for heavy aromatics.The DMSO and DMF belong to non-proton polar solvents,and the dielectric constant and dipole moment are larger,so the polarity is stronger,and their solubility and selectivity to aromatics are better than TRIG.The DMF contains N—C and C■O groups,which has strong solubility.But the solvent containing—S—group usually have good selectivity,so the selectivity of DMS is better than that of DMF,nevertheless,because the DMSO contains S■O conjugated double bond group,the solubility of DM-SO to aromatics is only inferior to that of DMF.When the blended solvent extraction experiment is carried out with DMSO as the main extractant and 20%DMF as assistant,the distribution coefficient of heavy aromatic hydrocarbons increases from 0.09 of the single extractant to 0.15,the separation factor decreases from 74.49%of the single extractant to 53.45%,and the extraction efficiency of heavy aromatics increases,but it also increases the loss of some cycloparaffin.The total heavy aromatics content decreases to 8.70%through three stages extraction of compound solvent,and the bicyclic aromatics and tricyclic aromatics are easier to be extracted,but the content of mono cyclic aromatic hydrocarbons is still as high as 8.20%.The content of the indan and tetralin in the mono aromatic hydrocarbons decreases to 2.80%from 18.20%of the raw materials and the total extraction rate is 84.60%.The content of indene is reduced from 14.90%to 1.30%,and the total extraction rate is 91.30%.However,the content of alkylbenzene in raw materials is only 6.70%.Through three stages extraction,the content of alkylbenzene dropps to 4.10%,and the total extraction rate is only 38.80%.The main reason for the low extraction efficiency is that alkylbenzene compounds in mono aromatic hydrocarbons are difficult to be extracted by conventional polar solvent.The main structural characteristics of alkylbenzene in the first ring aromatic hydrocarbon above C_9are that the side chain of benzene ring has long alkyl or naphthenic groups,such as phenyl cyclohexane,methyl phenyl cyclohexane,etc.For one thing,the side chains of non-aromatic hydrocarbons on the benzene ring are long or complex,which are quite different from the main extractant DMSO.For another thing,compared with the polarity of other cyclic aromatic compounds such as tetrahydronaphthalene and indene,the polarity of alkylbenzene has a greater difference with that of DMSO.Therefore,the solubility of alkylbenzene in DMSO is weaker than that of tetrahydronaphthalene and indene due to the difference of structure or polarity.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 5852K]

  • Numerical simulation of low NOx burner retrofit of a 420t/h tangentially lean coal-fired boiler

    CHEN Tao;YU Jie;ZHAO Peng;SUN Lushi;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology;Suzhou Branch,Xi'an Thermal Power Research Institute Co.,Ltd.;

    In order to meet the strict emission standards,most of the power station boilers have implemented NOxemission control technology. A 420 t/h tangential coal fired boiler of utilizing bituminous coal was retrofitted by replacing original burners with horizontal bias combustion( HBC) ones as well as introducing separated over-fire air( SOFA) to achieve the effect of low nitrogen combustion. The numerical simulation method was used to demonstrate the scheme. The effects of the primary air concentration ratio,SOFA air rate and SOFA air jet angle on the combustion status and NOxemission of the boiler were studied,and the optimum modification scheme was put forward. As the rich-lean ratios increasing,the furnace outlet temperature gradually increases,while the NOxcontent gradually decreases. When the richlean ratios is 4 ∶ 1,the carbon content in fly ash is the lowest. As rich-lean ratios increasing,the concentration of CO increases,which enhances the reduction of the main combustion zone and inhibits the oxidation of volatile nitrogen-containing intermediates into NO. Moreover,the increase of rich-lean ratios makes the rate of volatilization of concentrated coal powder increase. The volatile nitrogen-containing intermediates HCN and NH3 are used to reduce the produced NO to N2. At the same time,the lean side gas pulverized coal concentration is low,the amount of the nitrogen-containing group precipitation is small,and the amount of NO formed by reaction with oxygen is reduced.With the increase of SOFA ratios,the flue gas temperature of the furnace exit and the carbon content of the fly ash increase,and the NOxconcentration is higher at the 20% SOFA ratios,and the NOxconcentration remains basically unchanged when the SOFA wind rate increases from 30% to 40%. With the increase of SOFA ratios,the strong reducing atmosphere with low O2 and high CO concentration formed in the main combustion zone inhibits the oxidation of HCN and NH3 to NO,which in turn promotes the reaction with the generated NO to form N2. In addition,under the high SOFA ratios,the high temperature zone of the main combustion zone is reduced,and the thermal NOx is also reduced accordingly. As the SOFA jet angle increases,the reduction zone lengthens,which is conducive to reducing the NOxconcentration,but the flame center in the burnout zone rises,and the pulverized coal burnout time become shorter,and the furnace exit temperature and fly ash carbon content increase. As the jet angle increases,the O2 concentration decreases and the CO concentration increases. Because the increase of jet angle delays the pulverized coal burnout process and increases the chemical incomplete combustion loss. The strong reducing atmosphere with low O2 and high CO concentration greatly suppresses NOxgeneration. According to the numerical simulation results,the low-nitrogen combustion reforming scheme of the boiler is determined as: a horizontal rich-lean burner with a ratio of 4 ∶ 1 is selected as the transformation burner,the SOFA ratios is set at 30%,and the SOFA jet angle is raised by 15°. The on-site measurement after retrofitting showed that combustion characteristic of the furnace was stable. The NOxemissions decreased significantly to 220 mg/Nm3( The decline is 65%-70%). The unburned carbon content in fly ash was as low as 3%-4% at the same time. It shows that the retrofitting scheme can achieve good low nitrogen combustion effect.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 2805K]

  • Numerical simulation study on the structural characteristics of annular counterflow jets flow field

    LUO Wei;China Coal Research Institute Company of Energy Conservation;State Key Laboratory of Coal Mining and Clean Utilization;National Energy Technology & Equipment Laboratory of Coal Utilization and Emission Control;

    The counterflow jet is an important technical means for flame stability. In order to explore the effect of counterflow jet on steady burning of the reversed injection burner of coal particle combustor,the flow field structure of different annular and round jets into a counterflow were computationally investigated using the Realizable k-ε Model in Fluent platform. By computing the penetration length in variational velocity ratios of each jets,the results show that the penetration length of annular jet is larger than that of round jet,and it increases when the annular grows,The permeability of annular jet in ambient flow increases which is conductive to increase the backward propagation distance of pulverized coal and residence time and improve combustion stability. Unlike round jet,the penetration length of annular jet does not have a monotonic linear relationship with velocity ratio. There exists a smooth transition when velocity ratio between 7.5-12.5,which indicates that the decrease of velocity ratio does not cause significant decrease of penetration length within a certain interval and has guiding significance for the design of existing burners. By calculating the maximum zero velocity half-width of each jet tube at different velocity ratios,it is found that the half width of zero velocity of annular jet is wider than that of round jet,and increases with the increase of the inner diameter,which indicates larger radial expansion width and stronger suction capacity. The half width of zero velocity of annular jet increases linearly with the velocity ratio,and the slope increases with the increase of the inner diameter. The radial expansion capacity of annular jets in counterflow with high velocity ratio is stronger than that of annular reverse efflux with low velocity ratio. By plotting streamline according to the calculation result,it is found that the streamline of annular jet is similar with round jet at lower velocity ratio,At higher velocity ratio,although the axis velocity decreases to zero at the stagnation point,the fluid still propagates downstream in a certain area near the axis,and it takes some distance before the velocity drops to zero and return,the dividing streamline also becomes irregular. The circumferential flow has a certain degree of compression and obstruction effect on the annular jet in the axial direction,so that the radial expansion width of the jet increases and the suction capacity of the jet increases,which is helpful to promote the mixing of pulverized coal and combustion air in the burner. By studying the change of axial velocity along the reverse jet axis of different jet tubes,it is found that the velocity attenuation on the annular jet axis is more gentle than that on the circular jet axis,which indicates that the mixing with the environmental flow is not as strong as that of the round jet. As the inner diameter decreases,the peak value of the axial velocity of the annular jet increases and its position advances,and the attenuation velocity increases,which gradually approaches the attenuation on the central axis of the circular jet.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 4074K]

  • Study on ultra-low NOx emission technology of 660MW ultra-supercritical circulating fluidized bed boiler

    LI Yingping;XIN Shengwei;WANG Fengjun;Shenhua Guoneng Group Co.,Ltd.;Shenhua Group CFB Technology R&D Center;Harbin Boiler Co.,Ltd.;

    Circulating fluidized bed( CFB) power generation technology is one of the clean coal power generation technologies developed in recent decades. Because of its good advantages of desulphurization and nitrogen suppression in furnace,it has been widely popularized.With the increasingly serious environmental situation,the CFB boiler can not meet the NO_xultra-low emission requirement by means of the low-nitrogen combustion in the furnace,so it is necessary to study the low-nitrogen combustion theory of the CFB boiler,and the breakthrough should be realized in 660 MW high efficiency ultra-supercritical CFB boiler. In this paper,based on the design concept of flow pattern reconstruction energy-saving CFB boiler,the generation and reduction mechanism of NO_xin furnace and the technical scheme of NO_xremoval in furnace were studied by experiment and numerical simulation. The results show that the factors affecting NO_xemission of660 MW supercritical CFB boiler include burning coal quality,combustion temperature and uniformity,excess air coefficient( operating oxygen),graded combustion and so on. The 660 MW ultra-supercritical CFB boiler adopts the furnace structure of single furnace,single air distribution plate,M-type arrangement structure,four cyclones and four external heat exchangers. The hot primary air of the boiler is fed from the back side of the water-cooled air chamber at 6 points,which ensures the uniform distribution of the static pressure of the primary air of the boiler,and thus ensures the uniformity of the fluidization of the material. The coal feeding mode of " coal feeding on the front wall and sludge for the back wall" is adopted. The front wall is equipped with 12 coal falling ports,the rear wall is equipped with 8 sludge guns and 8 slag discharge ports to ensure the uniformity of coal feeding. The arrangement structure of the 4-cyclone separator ensures the uniformity of the material,the maximum deviation of flow rate between different cyclones is 7.9%,and the uniform arrangement of the four external heat exchangers ensures the uniformity of the bed temperature. The temperature field and excess air coefficient play a key role in NO_xemission. The boiler design bed temperature is 860 ℃,which not only ensures the boiler efficiency,but also reduces the NO_xemission,at the same time,it ensures the reaction temperature of selective non-catalytic reduction( SNCR) denitrification system under low load conditions. The excess air coefficient of boiler is 1.15,which further enhances the reductive atmosphere. The ratio of primary to secondary air is 4 ∶ 6 in staged combustion,and the position and inclination angle of boiler secondary tuyere are adjusted properly to form a large reductive atmosphere to ensure the furnace combustion atmosphere. The comprehensive effect of the above measures can realize high efficiency nitrogen suppression in the furnace,and finally make the original emission concentration of boiler NO_xless than 50 mg/m3,as The SNCR technology with urea as reductant outside the furnace is selected as the assistant denitrification method realize the final NO_xultra-low emission in the flue gas under the condition of low investment,low cost and full load.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 2325K]

  • Influence of low quality coal on the combustion performance in a 1000 MW swirl opposed firing boiler

    HAO Jian;PEI Jianjun;YOU Changfu;Sanhe Power Generation Co.,Ltd.;Department of Energy and Power Engineering,Tsinghua University;

    When the low quality coal is used in a swirl opposed firing boiler,it is difficult to ignite in time and burn out,which causes the temperature of the main combustion zone to be low.The unstable combustion of the furnace will lead to the high temperature corrosion and slagging in the water wall,and the overheating problems on the upper convection heating surface.the carbon content of fly ash is also greatly increased,thus the thermal efficiency of the boiler is significantly reduced.This is a major problem facing the operation of the power plant boilers.For a 1 000 MW opposed firing boiler,the combustion performance and the distribution of the characteristic parameters was studied by numerical simulation method when it was burned inferior coal,and the results were compared with the designed coal,so as to provide some basis for improving the coal adaptability of the boiler.The results show that,compared with the designed coal,the ash content of inferior coal is higher and the calorific value is lower.The classified air distribution mode of the original burner is not conducive ignited in time and maintain the stable combustion,and the fire point is postponed and the temperature distribution of the horizontal section of in the furnace is uneven.The high temperature area appears near the water wall.The large area of high concentration CO generates near the center of the water-cooled walls,and the high temperature zone in the furnace center also decreases for the incomplete combustion and the temperature of the convective heating surface rises up.That is,the flame center is close to the burnout zone,which is easy to cause the high temperature corrosion and slagging in the water-cooled wall,and the overheating of the convective heating surface.The fume temperature and carbon content in fly ash at the outlet also increases,that is,the boiler efficiency will decrease.In addition,due to the irrationality of the staged combustion organization,the production of NOxat the furnace outlet is also significantly increased.In the actual industrial application,the quality of the burning coal should be blent with the designed coal to improve the combustion characteristics of the low quality coal and ensure the combustion stability of the boiler.Also,the original swirl burner should be optimized and reformed,and the mixing of primary air and secondary air should be strengthened in advance,and the primary air velocity is reduced appropriately or the wall wind system is added near the water-cooled wall to ensure pulverized coal ignition in time and improve the ability of the boiler to burn the low quality coal.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 16004K]

  • Study on key factors of poor burnout characteristic of low-moisture Australian coal

    SONG Yucai;Zhejiang Zheneng Fuxing Fuel Co.,Ltd.;

    In recent years,a large amount of Australian coal has been imported to coal-fired power plants in China,which can be classified by high-moisture Australian coal and low-moisture Australian coal according to the coal characteristics.The coal quality index and combustion characteristic of high-moisture Australian coal is similar to that of the Shenhun coal in China,while the characteristic of low-moisture Australian coal is similar to that of the Youhun coal in China.It is usually found that the carbon content of fly ash increases and the boiler efficiency decreases when the low-moisture Australian coal is used in coal-fired boilers.In order to explore the key reasons for the poor burnout characteristics of low-moisture Australian coal and their discrimination methods,and provide guidance for the reasonable use of low-moisture Australian coal and the optimization of combustion adjustment,the low-moisture Australian coal and Youhun coal were sampled for research.By means of coal quality index analysis,grindability analysis,thermal analysis,porosity analysis and Malvine particle size analysis,the differences of coal quality index,combustion characteristics,porosity and particle size distribution between Australian coal and premium coal blends were studied.The results show that the coal characteristics are similar between the two coal samples,but the oxygen content of low-moisture Australian coal is lower than that of Youhun coal,which indicates that the coalification level of Australian coal is higher than that of Youhun coal. The Hardgrove grind ability index( HGI) or the oxygen content can be used to determine the burnout characteristics of Australian coal since the HGI decreases when the oxygen content increases.Besides,the defined burnout index C700 of thermal analysis is effective to describe the practical combustion characteristics too. The larger pulverized coal size under the same milling conditions is determined to be the main reason why the low-moisture Australian coal is hard to burn out.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 3335K]

  • Deformation analysis of wing wall superheater/reheater in a circulating fluidized bed boiler

    HUANG Zhi;GUO Xuemao;LI Jun;ZHANG Man;State Power Investment Co.,Ltd.;Taiyuan boiler Group Co.,Ltd.;Department of Energy and Power Engineering,Tsinghua University;

    The wing wall superheater/reheater located in the upper furnace is one of the important components of the circulating fluidized bed( CFB) boiler,which generally enters the furnace from the front wall and exits from the furnace roof. The tube metal temperature of the wing wall is different from that of the water wall,which results in the different expansion in thermal operation. The inlet and outlet of wing wall are sealed and connected with the water wall and therefore,the design of the expansion system is of great significance. The improper design may lead to the deformation of the heating surface of the wing wall due to their expanding difference,which results in lower safety.The expansion calculation is the key process in the design of the expansion system. In this study,the model of the tube wall temperature of the wing wall in the CFB boiler was suggested and the maximum tube wall temperatures under different loads were calculated. It is found that under 60% rather than 100% of the rated load,the tube wall temperature reached the maximum. However,the engineering practice shows that if the wing wall is designed according to this results,the wing wall deformation of the heating surface still happens in the tubes,which indicates that the maximum tube wall temperature predicted in steady state is not the highest working condition of the heating surface of the wing wall. Then the load of the maximum expansion was analyzed. Consequently,it was proposed that the maximum expansion of the wing wall superheater/reheater happened in the extreme hot start-up. Therefore,it was suggested that the maximum expansion of the wing wall superheater/reheater should be calculated under the working condition of the extreme hot start-up. A specific working condition is recommended: the 20% of the rated pressure,the saturation temperature under calculation pressure and the 15% of the steam flow rate under the boiler maximum continuous rating( BMCR). The practice of the CFB boiler,of which the expansion is designed according to the above,shows that the design of expansion system by calculating wall temperature of extreme hot start-up can solve the problem of the deformation of the wing wall superheater/reheater in the CFB boiler.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 927K]

  • Experimental analysis on combustion adjustment of 410t/h CFB boiler

    HAN Ying;HUI Xiaolong;LIU Dong;ZHANG Shixin;HUANG Haipeng;XU Haitao;Huaneng Clean Energy Research Institute Co.,Ltd.;Maoming Branch of China Petroleum Chemical Co.,Ltd.;Huaneng Yimin Coal Power Co.,Ltd.;

    Aiming at the problems of high carbon content in ash and poor operation stability of 410 t/h circulating fluidized bed( CFB)boilers in A power plant,the main operation parameters such as primary air volume,return air volume and coal particle size were optimized and adjusted,and the optimum combination of boiler operation parameters was explored.. The test results show that the size of the coal entering the furnace is slightly fine and the median diameter is only about 1 037.97 μm. The median diameter of the boiler bottom slag is only375.64 μm,which indicates that the ash-forming characteristics of the coal entering the furnace are better. The running picture shows that the differential pressure value of ash concentration in the upper part of the furnace is as high as about 2.5 k Pa. The excessive fine ash particles in the furnace make the circulating ash volume fluctuate greatly under the influence of primary air volume. In order to ensure the stable operation of the return material of the boiler,the primary air flow through the air distribution plate controlled by the operator is only102 300 m3/h,which is much lower than the design value of 183 000 m3/h,and is also seriously lower than that of the same type of units.The results show that the main reason for the high carbon content of ash slag is that the low primary fluidized air volume makes the combustion in dense phase zone seriously anoxic. In addition,the low primary air flow makes the resistance of the distributor only 2.1 k Pa.Compared with the resistance of the air distributor of the same type of boiler,the resistance of the air distributor is smaller,which results in poor local fluidization and uneven temperature distribution of the boiler. It is suggested that the combustion efficiency of the boiler can be effectively improved by adjusting the size of coal into the furnace reasonably,controlling the median diameter between 2 000-3 000 μm,optimizing the ash concentration distribution in the furnace and increasing the primary air flow.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 224K]

  • Emission characteristics of heavy metal during combustion of coal gangue and coal slime

    PENG Hao;WANG Baofeng;YANG Fengling;CAO Yan;CHENG Fangqin;Institute of Resources and Environment Engineering,Shangxi University;Chemical Department of Western Kentucky University;

    Coal gangue and coal slime are solid wastes produced in the process of coal washing and mining. A large number of the coal gangue and coal slime will cause a series of environmental and ecological problems. Combustion for power generation is one of the main ways to utilize coal gangue and coal slime efficiently. It is well known that coal gangue and coal slime contain a certain amount of heavy metals,such as Hg,As,Pb,etc. These harmful elements are released in the combustion process,which will cause serious harm to the environment. Therefore,it is of great significance to study the emission characteristics of heavy metals from coal gangue and slime during combustion. In order to investigate the emission characteristics of heavy metals from coal gangue and coal slime burning in O_2/CO_2 atmosphere and air atmosphere,Pingshuo coal gangue and coal slime was used for experiment and the emission characteristics of As,Hg,Pb and Se during combustion in O_2/CO_2 atmosphere( 20%,30% and 40% of O_2 concentration,respectively) and air at different temperatures( 500-1 000 ℃) were studied; and the Hydra-II mercury meter was used to measure the Hg content in coal gangue,coal slime and ash,and the ICP-AES was used to measure As,Pb and Se content in coal gangue,coal slime and ash. The results show that during combustion of coal gangue and coal slime,the ash ratio of coal gangue and slime decreases with the increase of temperature and the O_2 concentration,when the combustion temperature is 500-1 000 ℃ and the O_2 concentration is 20%-40%,the proportion of As,Hg,Pb and Se in the combustion flue gas increases with the increase of temperature and volume fraction of O_2,and the ash content decreases after combustion. The As,Hg and Pb are easier to volatilize into the gas phase with the increase of combustion temperature when coal slime is burned in O_2/CO_2 atmosphere. In addition,when the coal slime burns in air,the ratio of As,Hg and Pb in flue gas is slightly higher than that in flue gas in O_2/CO_2 atmosphere with the O_2 concentration of 20% at the same temperature.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 16303K]

  • Study on migration of mercury in the process of preparing activated coke

    ZHANG Haoqiang;Beijing Key Laboratory of Coal Based Carbon Materials;State Key Laboratory of Coal Mining and Clean Utilization;National Energy Technology & Equipment Laboratory of Coal Utilization and Emission Control;

    In order to study the migration of mercury in the process of industrial producing activated coke,the laboratory equipment that can simulate the process of industrial preparing activated coke was used to prepare the activated coke sample. And the mercury content of raw coal,carbonized samples and activated coke samples was determined by the mercury detector based on cold atomic absorption spectrometry and the amount of mercury that migrated in the preparing process was calculated. The results show that the mercury content of the raw coal for preparing activated coke is 42. 4 ng/g,the mercury content of the intermediate carbonized sample( TH) is 1. 0 ng/g and that of the activated coke sample( HXJ) is only 0. 8 ng/g. The results show that the form of mercury in raw coal is mainly composed of inorganic salts of covalent compounds and organic mercury in some humic acids,and the decomposition temperature of these mercury compounds is around 350 ℃. While the carbonization temperature can reach 650 ℃,the most of the mercury compounds in the raw coal have been decomposed and escaped to the atmosphere in the form of zero-valent mercury vapor. The carbonization process in preparing activated coke is the largest stage of mercury migration and evaporation,and 97. 6% of the mercury in the raw coal escapes into the air at this stage. In the industrialized process of preparing activated coke,it is necessary to control and remove the mercury emission in the exhaust gas generated by carbonization stage.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 4435K]

  • Flue gas desulphurization technology and economic analysis of coal-fired industrial boilers

    CUI Mingshuang;ZHOU Jianming;ZHANG Xin;LI Ting;NIU Fang;China Coal Research Institute Company of Energy Conservation;State Key Laboratory of High Efficient Mining and Clean Utilization of Coal Resources;National Energy Technology & Equipment Laboratory of Coal Utilization and Emission Control;

    Sulfur-containing flue gas emission from coal-fired industrial boilers is one of the main sources of atmospheric pollution. With the increasingly stringent requirements for different pollutants emission from boiler flue gas,the state has implemented the ultra-low emission standard for flue gas,the requirement for SO2 to be below 35 mg/m3,so the control of SO2 in boiler flue gas is imminent. In this paper,the characteristics of wet and semi-dry desulturization technologies were analyzed,the differences,advantages and disadvantages of different wet desulfurization technologies were compared,the limestone-gypsum method and NO Gap Desulfurization processes and desulfurization mechanism were elaborated in detail,and the feasibility and economy of the two desulfurization technologies were analyzed and compared. At present,the desulfurization efficiency of limestone-gypsum process is 95%. The limestone forced oxidation system is widely used. The scaling,blocking,corrosion and waste water are the main problems of this technology. The NGD desulfurization technology uses fly ash as desulfurizers. Due to the particularity of coal in Shendong area,there are more active substances in fly ash. Under the condition of water,the Si and Al in fly ash dissolve and hydrate with hydrated lime. The high hydrate produced greatly improves the desulfurization efficiency. The desulfurization efficiency is between 80% and 90%. The economy of NGD desulfurization technology is better than limestone-gypsum method,and the characteristics of coal-fired industrial boilers are different from those of power plant boilers. For medium and small coal-fired boilers,the NGD desulfurization technology has good adaptability and development prospects.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 2211K]

  • Theoretical calculation and experimental study of D-11D pulverizer output

    ZHANG Feng;YANG Kai;XU Long;Xi'an Thermal Power Research Institute Co.,Ltd.;Sanhe Power Generation Co.,Ltd.;Xi'an Yitong Thermal Technology Services Co.,Ltd.;

    A power plant equipped with foster wheeler D-11 D type double inlet and outlet pulverizing system has the problem of insufficient output. In this paper,based on the theoretical calculation of the pulverizer output and the test adjustment of the pulverizing system,the reason of the lack of the pulverizing output was analyzed,and the output of the pulverizing system was improved. The results of calculation and test show that the output of pulverizer is positively correlated with the ventilation rate,and only adjusting the operation mode of pulverizer to increase the ventilation rate of pulverizer can not really improve the grinding capacity of pulverizer. With the increase of the opening of the damper and the increase of the air flow of the pulverizer,the amount of grinding coal increases and the pulverized coal becomes coarser. If the pulverizer ventilation is insufficient,only increasing the steel ball loading capacity to improve the grinding capacity can not effectively improve the pulverizer output. After the change of coal quality,in order to improve the power of the pulverizer,in addition to increasing the load of steel balls and improving the grinding capacity of the pulverizer,it is necessary to increase the ventilation capacity of the pulverizer and enhance the capacity of carrying pulverized coal. The main reasons for the insufficient output of the pulverizer are that the operation mode of the pulverizing system is not adjusted correspondingly with the change of coal quality and the grinding capacity decreases due to the insufficient loading of steel balls of the pulverizer. According to the test results,by increasing the loading capacity of steel mill and increasing the pulverizer ventilation rate adjustment measures,the air pressure of the main pipe of the hot primary air remains unchanged at 7.0 k Pa,and A,B,C three coal mill run capacity when the damper opening at 75%,the total air flow in the pulverizing system reaches 209 t/h,the total output of the pulverizing system increases from 128 t/h to 137.89 t/h,and the loading capacity increases from 280 MW to 320 MW. When the damper opening is set at 90%,the total output of the pulverizing system increases to 144.84 t/h,and the load capacity increases to337 MW. The total output and load capacity of the pulverizing system were significantly increased.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 4624K]

  • Research on intelligent technology of large-scale coal preparation plant

    SONG Wenge;CHN Energy Shendong Coal Preparation Center;

    A large-scale coal preparation plant Shendong Coal Washing Center was taken as the research object. According to the intelligent demand of coal preparation plant,this paper put forward an all-round intelligent construction scheme. On the basis of closely integrating coal washing processing,process control and artificial intelligence,theoretical research was carried out from the aspects of intelligent perception,intelligent decision-making,intelligent diagnosis and management of equipment and intelligent production process. A set of intelligent construction technology of coal preparation plant was developed. Through intelligent decision-making system,the production rate and quality of commercial coal could be predicted by comparing different modes of production,so as to calculate product benefits,recommend the optimal mode of production,and make statistical analysis of production costs and benefits,which greatly promotedthe management innovation and intelligent construction of Shendong Coal Group. It realized the improvement of quality and efficiency,intelligent production and management. A structured private cloud database including washing process database,production model evaluation database and coal preparation expert database was established. On this basis,combined with artificial neural network and random search algorithm,according to the needs of user and the principle of maximum benefit,and on the basis of the original network,an intelligent diagnostic management system for coal preparation equipment was developed,which was based on industrial 4 G network and supported by fault characteristic data analysis. It realized real-time monitoring,online analysis,fault diagnosis and intelligent management of the whole life cycle of the equipment,and solved the existing problem of information island. On the basis of multi-dimensional intelligent monitoring,production environment perception,process system perception and production equipment perception were realized. Through intelligent statistics,analysis and prediction of production status,information management of washing daily business was carried out. Combining with mobile control and other means,the existing management institutions and production organization forms were optimized. The data-driven on-line intelligent parameter setting and precise control technology for gravity separation control was developed,and the intelligent and precise drug feeding technology based on the synergy of slurry feed characteristics and solid-liquid interface was developed,the intelligent power distribution,personnel intelligent positioning and automatic loading technology was developed to realize the intellectualization of coal preparation plant production process. The on-line intelligent setting of sorting parameters was realized by data-driven and expert decision-making. Through intelligent upgrade and transformation,the precise production and intelligent allocation of large-scale coal preparation plants with a capacity of 100 million tons could be realized,and the operation cost could be effectively reduced.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 6741K]

  • Study on the intelligent control system of slime water dosing in coal preparation plant

    TAO Yadong;PAN Yuejun;CHN Energy Shendong Coal Preparation Center;

    In order to further enhance the intelligent management level of slime water treatment in coal preparation plant,Shendong washing center integrated the online sensor with intelligent control system of sprinkler type dosing equipment. Combining with the feature of slime water of coal preparation plant technological process,based on slurry flocculation sedimentation test,the feeding concentration of concentrator was regarded as the relevant condition factor of dosage,and the sedimentary thickness parameter was regarded as feedback information interface,the control box program calculation analysis was carried out,and the dosage information was sent out by adjusting the adjusting control of electric valve,so as to realize the intelligent control of coal slime water dosing system. Through multipoint sprinkler irrigation dosing,the reagent was mixed with the slime water. Through the settlement of slime water state,the state of slime water layers in the concentrated tank settlement was judged. The matching degree of intelligent dosing system intelligent control and the slime settlement was analyzed. The built-in expert system was revised manually to ensure the continuous optimization and upgrading of the intelligent dosing system. Through a series of intelligent means to solve the problem of lack of slime water process digital management,the overall framework,on-line monitoring instrument,dosing control strategy,control devices of the intelligent control system of slime water dosing in modern coal preparation plant were built. The intelligent control system of slime water and charge has been applied to Shangwan coal preparation plant of Shendong Coal Preparation Center. With the increase of 100 t slurry water treatment capacity,the feed capacity can be increased by 100 t,the 230 t raw coal treatment capacity can be increased year-on-year,and the production efficiency can be increased by 10%.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 3431K]

  • Research and application of fully automated loading system

    SUN Jianrong;XIAO Wenyuan;CHN Energy Shendong Coal Preparation Center;

    Allthe 11 coal preparation plants of Shendong Coal Group Washing Center adopt the fast loading system with the annual loading capacity about 200 million tons. The rapid loading system has high loading efficiency,but the degree of automation is relatively low,the workload is large,and the waste of coal caused by subjective factors is serious,which affects the speed and accuracy of loading. In view of the above problems,the original rapid loading system was upgraded through the principle of programmable control technology and the application of sensors,and a new automatic loading system was developed. The specific measures were to add radar speed sensor and photoelectric sensor at a certain position of the loading station,the real-time loading speed of the train and the running position of the train were detected,respectively,and the programmable control technology was used to automatically adjust the opening time of the coal loading system point,so as to achieve fully automatic loading. Through the above technical measures,the loading accuracy of the loading system has been increased to over 99%,which is adapted to the automatic loading of different models. 80% of the labor of the loader is released by application of the fully automatic loading system,which reduces the loading cost of the coal preparation plant and saves about 15 million yuan/a of the economic losses caused by the problems such as maintenance costs,labor costs,overload and unbalanced load and labor loading quality caused by the collision between the loading chute and the vehicle. The accuracy of loading quantity control is improved,and the problem of poor loading quality,super and partial load caused by irregular operation is eliminated,and the stability and safety of the system are ensured.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 11560K]

  • Ultrasonic sensing technology of coal slime water deposition interface in the thickener of coal preparation plant

    ZHU Ziqi;LYU Yibo;CHN Energy Shendong Coal Preparation Center;School of Mining Engineering,Heilongjiang University of Science & Technology;

    The coal slime water deposition interface is an important technical parameter to describe the working state of the thickener. It is of great significance to guide the parameter control of slurry flocculant dosage. In this paper,the object is the rule of the distribution of coal slime concentration and particle size in the thickener of shendong coal preparation center coal preparation oil preparation plant. 14 points from 100 mm to 13 100 mm and 16 positions from 100 mm to 4 900 mm were selected along radial equidistance,and 195 sampling points were set altogether. The results show that the concentration of coal slime water in the thickener is higher as it goes down from the surface,the concentration of coal slime below 3 600 mm increases sharply and there is fluctuation. The concentration of coal slime water along the radial horizontal distribution of the thickener changes independently of the sampling radius. Ultrasonic testing platform is designed and manufactured by ultrasonic detection principle,the operating frequency of ultrasonic is set as 66 MHz. When ultrasonic wave propagates in coal slime water,the ultrasonic wave would attenuate affected by coal slime in coal slime water. This phenomenon was used to detect the concentration of coal slime water at different depths in the thickener,thus the depth of coal slime water deposition interface in the thickener was calculated. The results show that there is a good linear relationship between the concentration of coal slime water and the difference of ultrasonic transmitting and receiving frequency. The height of fresh water layer during the production and shutdown of the thickener was tested respectively,and the results were compared with the artificial detection of the height of the fresh water layer. The experiment shows that the index difference value between ultrasonic testing platform and manual testing is 46-57 mm. It can replace manual test and realize automatic detection of deposition interface parameters of thickener. This test platform provides an important basis for automatic control of the subsequent sedimentation process of coal slime water flocculation.

    2019 05 v.25;No.123 [Abstract][OnlineView][HTML全文][Download 2645K]
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