• Research progress on synthesis of hydrophobically modified polyacrylamides

    REN Bao;MIN Fanfei;CHEN Jun;DU Jia;College of Material Science and Engineering,Anhui University of Science and Technology;

    In order to develop the low cost hydrophobically modified polyacrylamide( HMPAM) and to solve the problem of efficient treatment of industrial wastewater,the synthesis of hydrophobically modified polyacrylamides was discussed in this paper.HMPAM,as an important branch of hydrophobic associating water-soluble polymers,has the characteristics of viscosity enhancement,salt resistance and shear resistance.HMPAM synthesis methods such as co-solvent method,micellar copolymerization method,emulsion polymerization method,free radical interfacial polymerization method,ultrasonic polymerization method and supercritical CO_2 polymerization method were also analyzed.Clearly,various synthesis methods have long R & D production cycle and high cost.Besides,the synthesis efficiency is low and the treatment effect is poor.By combining computational simulation technology with experimental results,a more scientific,rapid and low-cost HMPAM synthesis method is proposed by perfecting the system of synthesis monomer and synthesis method.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 2325K]

  • Research progress on influence of heavy metal occurrence mode on release behavior during coal conversion

    ZHOU Lingmei;WANG Xiaobing;GUO Hao;CHU Mo;SONG Zhao;ZHANG Guanjun;School of Chemical and Environmental Engineering,China University of Mining and Technology( Beijing);Thermal Power Department,China Datang Corporation Science and Technology Research Institute;

    In order to solve the harm of heavy metal release behavior in coal to environmental pollution and human health,the effects of the occurrence mode on migration behavior of heavy metal during coal separation,combustion,gasification,and pyrolysis processes was analyzed.The results show that the heavy metal in mineral phase can be removed greatly with the decrease of ash content in separation process,while the heavy metal in organic phase can't be removed easily.In the high temperature conversion process of coal,the organicbound heavy metal are more volatile than mineral-bound heavy metal,and the volatility of latter is affected by mineral types. The occurrence mode of heavy metal in coal are direct and indirect which can be combined with many methods.It is believed that the study of the occurrence mode and migration behavior of heavy metal helps to control the pollution caused by heavy metal during coal conversion process from the source,and the occurrence mode of organic heavy metal elements can be better revealed by pyrolysis process.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1080K]

  • Research on positive effect mechanism of pyrite on coal oxidation at low temperature

    CHEN Sihan;BAI Xiangfei;FANG Quanguo;Test Branch of China Coal Research Institute;State Key Laboratory of Coal Mining and Clean Coal Utilization;Coal Chemistry Branch of China Coal Research Institute;

    Pyrite more or less exists in coal,and it plays an important role in initial oxidation of coal due to its easy oxidation.In order to fully understand the process of coal oxidation,weathering and even spontaneous combustion,the mechanism of pyrite on coal initial oxidation need to be investigated deeply.Accordingly,the mechanism of pyrite oxidation was firstly studied in this paper,and the influence of pyrite on coal oxidation,the promoting effect of moisture on coal and pyrite oxidation and the facilitating role of pyrite on coal initial oxidation at low temperature was also discussed.It is showed that there is a synergistic effect between the appropriate moisture and pyrite in coal,which can accumulate heat in coal,causing the promotion of coal oxidation.In addition,the chemical activity of pyrite and the amount of oxygen adsorbed in coal are increased after the coal crushed by machine,thus promoting the slow oxidation process of coal at low temperature.This paper helps to understand the mechanism of coal oxidation comprehensively,and provides a theoretical support for the long-term storage of coal samples and the development of special-purpose samples.Specifically,for the long-term preservation of special-purpose coal samples,low-temperature oxidation reaction of coal should be delayed from two aspects: in the case of coal with larger oxidation value,the lower pyrite content is better,while more attention should be paid into the oxidation value of coal when it contained lower pyrite content.Besides,considering the total sulfur and pyrite content in coal,the appropriate preservation water or maximum preservation water in coal should be discussed.If the coal needs to be preserved for a long time,it should be pay more attention to the changes of environmental humidity and the influence of air flow.Further,it is better to keep the air clam.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1078K]

  • Progress and technology development of preparing high concentration coal water slurry from low-rank coal

    LI Falin;SHANG Qingyu;WANG Guofang;WANG Jianjun;China Coal Research Institute Company of Energy Conservation;National Coal Water Mixture Engineering Technology Research Center;State Key Laboratory of Coal Mining and Clean Utilization;National Energy Technology and Equipment Laboratory of Coal Utilization and Emission Control;

    In order to improve the concentration of coal water slurry prepared from low-rank coal and realize the efficient and rational utilization of low-rank coal,the research progress of preparation technology of high concentration coal water slurry from low-rank coal was introduced.The research and development process,technological characteristics,concentration enrichment effect and application status of coal water slurry preparation process from single grinder preparation process to graded grinding continuous gradation slurry preparation process and discontinuous granularity gradation slurry preparation process were analyzed.Finally,problems in application and development direction of coal water slurry preparation were analyzed. The pulping process with graded grinding only has a concentration effect of about 3% compared with the conventional pulping process with single grinding mechanism.Surprisingly,the pulping process with discontinuous gradation has a concentration effect of 6% to 8%.Therefore,discontinuous gradation pulping process is the preferred technology for the preparation of high concentration coal water slurry from low-rank coal.Coal water slurry preparation technology should be further innovated and pulping raw materials such as low-rank coal and low volatile coal,industrial waste water,sludge and industrial residues should be expanded as pulping raw materials in the future,and coal water slurry combustion application technology should be developed to industrial parks and cogeneration of thermal power,to realize coal efficient,energy-saving,environmental friendly utilization.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1884K]

  • Deep de-ashing influencing factors of typical ultra-low ash coal in China

    ZHU Chuan;BAI Xiangfei;TU Hua;CHEN Hongbo;Coal Chemistry Branch of China Coal Research Institute;School of Chemical and Environmental Engineering,China University of Mining and Technology( Beijing);State Key Laboratory of Coal Mining and Clean Utilization;

    Ultra-low ash coal( ash content <5.00%) is high quality raw material for ultra-pure coal.To obtain the optimum indices of raw coal for ultra-pure coal,the regional distribution and quality features of typical high-quality ultra-low ash coal in China was introduced in this paper.The washability and corresponding factors of typical low ash coals were studied using flotation de-ashing method under different granularity and chemical de-ashing method.The results show that most of the high-quality ultra-low ash coals,which mainly distributes in the northwest region in China,are low to middle metamorphic grade and difficult to medium grind coals.Compared with the inertinite-rich Nanlutian coal,the ash reduction of float coal from Taixi anthracite coal and Shendong coal are significant when they are grinded to size less than 6 mm or 0.2 mm.The flotation coal ash reduces 60.00% and 70.09% for the Taixi and Shendong coal with size less than 0.2 mm,respectively.After chemical de-ashing,the ash content is in order of Taixi coal <Shendong coal< Nanlutian coal,and the Taixi anthracite ash content reduces to 0.48%.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1531K]

  • Content and occurrence status of harmful elements in imported Mongolia coals

    KANG Fei;WANG Jingyuan;YANG Changqing;CHEN Hailin;JIANG Zhao;Tangshangang Branch ,Chian certification & Inspection Group Hebei Co.,Ltd.;Huhehaote Customs District P.R.China;

    To assess the impact of imported coal on the domestic environment,the contents of ash,sulfur,mercury,arsenic,fluorine,chlorine and phosphorus in the imported 360 batches Mongolia coals were detected by Atomic Fluorescence Spectrometry( AFS),Direct Mercury Analyzer and Potentiometric titration.The overall level of the seven elements was described by the robust statistics and then evaluated according to the China's coal related grading standards and enrichment factor.The results show that the Mongolia coals contains special low mercury and chlorine,low ash and sulfur,medium fluorine,arsenic and phosphorus.The average enrichment factor of arsenic is 16,which should be payed more attention to the risk of environmental pollution.The relevant analysis and cluster analysis were used to infer the occurrence status of sulfur,mercury,arsenic,fluorine,chlorine and phosphorus.360 batches Mongolia coals can be divided into three different veins sources,and has different characteristics.Comprehensive consideration of correlation analysis and factor analysis results,the main factor features cloud be described as organic arsenic associated factor,fluorine mineral factors( fluorophosphorite and aluminosilicate) and sulfur factor.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1168K]

  • Study of coal water slurry concentration technology based on three-peak fractal gradation

    DUAN Qingbing;LYU Xiangyang;XU Minglei;HE Guofeng;ZHANG Shengju;ZHAO Liming;LIU Yewei;CHEN Hao;China Coal Technology & Engineering Group Clean Energy Co.,Ltd.;

    Aiming at solving the problems of low concentration,poor fluidity and atomization of coal water slurry produced by single mill process,the theory and method of particle size gradation was systematically studied,and the three-peak fractal gradation of coal water slurry could be realized by adding fine slurry and ultra-fine slurry.Theory and industrial application of coal water slurry concentration technology based on three-peak fractal gradation in Shanxi Yangmei Fengxiquanzi Energy Co.,Ltd. were analysed. Results show that coal slurry concentration increases from 60.10% to 64.19%,and the effective gas content increases from 79.91% to 82.12%.Specific oxygen consumption and specific coal consumption decrease by 35 m~3/km~3 and 20 kg/km~3,while ammonia consumption per ton of ammonia decreases by0.05 t,and the amount of ammonia per ton of coal increases by 0.024 t.The three-peak fractal gradation concentration technology has advantage of high pulp concentration and efficiency,wide adaptability of coal types and lower energy consumption,which will instead of conventional bar mill pulping process.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1530K]

  • Study on steam gasification characteristics and dynamics of coal liquefaction residue

    DONG Weiguo;XU Chunxia;GUO Liangyuan;HAO Jifeng;Coal Chemistry Branch of China Coal Research Institute;Beijing Key Laboratory of Coal Based Carbon Materials;State Key Laboratory of Coal Mining and Clean Utilization;

    In order to achieve the efficient utilization of coal direct liquefaction residue,the effects of gasification temperature,water vapor content and catalyst residual on gasification reactivity of semi-coke of Shenhua coal direct liquefaction residue were investigated.The mixed reaction model was used to fit the experimental data and get the kinetic parameters.The results show that the gasification reactivity can be improved by elevating the gasification reaction temperature and increasing water vapor content in gasifier.The gasification reactivity of semi-coke residue with water vapor is stronger than that of de-ashing semi-coke residue.The gasification reactivity of the semi-coke residue expressed by the reactivity index R' is consistent with the reactivity expressed by fixed carbon conversion rate and reaction rate.The total reaction order of semi-coke residue with water vapor is between 0.635 8 and 0.721 7,and the activation energy is between 149. 43 k J/mol and 198.85 k J/mol obtained by the mixed reaction model.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1719K]

  • Study on viscosity-temperature characteristics of coal-oil slurry in heavy oil and low rank coal hydro-coprocessing

    HU Fating;ZHAO Yuan;YAN Bingfeng;Coal Chemistry Branch of China Coal Research Institute;State Key Laboratory of Coal Mining and Clean Utilization;

    In order to prevent settling and excessive resistance in the process of coal-oil slurry conveying,the characteristics and mechanism of viscosity of coal-oil slurry in FCC slurry,coal tar heavy oil and low rank coal co-processing were investigated by using Rotary viscosimeter and high temperature viscosity meter.The results show that temperature has a great influence on the viscosity of coal-oil slurry under normal pressure and low temperature.The viscosity of coal-oil slurry decreases rapidly at first,and then slows down with the increase of temperature.The activation energy of coal-oil slurry during FCC slurry is higher than that of coal tar heavy oil. Under the condition of high temperature and pressure,the viscosity of coal-oil slurry prepared by decreases with the increase of temperature,and increases slightly between 350 ℃ and 370 ℃.The viscosity of coal-oil slurry prepared by coal tar heavy oil initially decreases with the increase of temperature.When the temperature exceeds 140 ℃,the viscosity of coal-oil slurry begins to rise.Then the viscosity reaches the maximum value at the temperature of 338 ℃,and then decreases with the temperature further increases.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1990K]

  • Mineral change law of coal fly ash in the process of roasting activation

    HU Yongjian;WANG Zhigang;FU Shihui;LI Yunlong;ZHANG Xin;LI Junkun;Department of Chemistry,Dezhou University;

    In order to explore the activation mechanism of different activators on fly ash,fly ash from combustion and gasification industries was roasted and activated by mixing with sodium carbonate,calcium carbonate,ammonium sulfate and concentrated sulfuric acid,respectively.The changes of minerals after calcination and activation were analyzed by XRD. The results show that the aluminum in combustion ash is mainly in the form of mullite,while the gasification ash is mainly in diopside form.The sodium carbonate tendes to form nepheline after calcination and activation,and its optimum activation temperature is 1 000 ℃.Calcium carbonate is calcined to form calcium feldspar,and the optimum activation temperature is 1 300 ℃.Ammonium sulfate tendes to form aluminum ammonium sulfate,and its optimum activation temperature is 500 ℃.Aluminum ammonium sulfate could be decomposed into aluminum sulfate at 550 ℃; and ammonium sulfate activates to produce sulfuric acid and nitrogen containing gases.The aluminum sulfate is the predominant product after sulphuric acid calcination and activation,and the optimum activation temperature is 400 ℃.Calcium in gasification ash is easily to form anhydrite during activation,and this increases the amount of ammonium sulfate and sulfuric acid.The activation temperature of those four activators is in order of calcium carbonate> sodium carbonate > ammonium sulfate > concentrated sulfuric acid. Therefore,the concentrated sulfuric acid activation method with low activation temperature is more promising.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 2547K]

  • Numerical simulation on combustion optimization of tower furnace with change of oxygen content of fan mill

    ZHAI Yongqiang;YANG Yongwei;ZHANG Lutao;SUN Peibo;GAO Lei;CHENG Zhihai;North China Electric Power Test Research Institute Co.,Ltd.,China Energy Engineering Group;School of Energy and Mechanical Engineering,Shanghai University of Electric Power;

    The variation in the oxygen content at the fan mill outlet will directly affect the combustion efficiency of lignite and the formation of nitrogen oxides( NO_x ).In this paper,Fluent 15.0 software was used to calculate the flow,combustion and NO_x formation characteristics of the fuel in the tower furnace under the condition of 8%,10%,12%,14% and 16% of the oxygen output at the fan mill outlet of a 660 MW supercritical unit.The results show that the fuel gas temperature at the flame center and the furnace outlet decreases significantly with the increase of the oxygen content at the outlet of the fan mill.Adjusting the oxygen content at the outlet of the fan mill can effectively control the central position of the flame and the fuel gas temperature at the hearth,avoiding excessive temperature of the flue gas and causing coking at the smoke outlet.Meanwhile,the NO_x content at the outlet of the furnace increases with the increase of the oxygen content at the outlet of the fan mill.After comparing the combustion characteristics of the pulverized coal and the NO_x generation rules under different oxygen conditions at the fan mill outlet,it is concluded that the optimum oxygen content at the fan mill outlet is 10%.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 3517K]

  • Research on fluidization behavior of pulverized coal and oil shale particles

    LI Guozhi;WANG Songjiang;ZHANG Zhenqian;Luoyang R&D Center of Technologies,Sinopec Engineering( group) Co.,Ltd.;

    To clarify the flow characteristics of pulverized coal and oil shale particles,the different operating conditions of these irregular fine powder were investigated in this study base on a set of circulating fluidized bed cold model test equipment with diameter of 400 mm and 300 mm.Meanwhile,the fluidization characteristics of pulverized coal and oil shale particles were also compared.The results show that the initial fluidization velocity of the oil shale powder and pulverized coal are about 0.043 m/s and 0.023 m/s,respectively.The small particle take-out velocity of oil shale powder and pulverized coal are about 0.7 m/s and 0.6 m/s.Likewise,the velocity of the large particles take-out velocity of two kinds of materials are about 1.4 m/s.Additionally,the bed density decreases along the bed height when the apparent gas velocity of the bed layer is between 0.1 m/s to 0.7 m/s.In that case,the density of oil shale bed is between 800 kg/m~3 and 350 kg/m~3,and the density distribution of pulverized coal bed is ranging from 750 kg/m~3 to 300 kg/m~3.With the increase of the height of the riser and superficial gas velocity,the density of bed layer in the riser decreases from the bottom to the top,and it demonstrates a certain fluctuation similar S shape.In addition,the density of the bed layer in the riser is between 20 kg/m~3 and 110 kg/m~3.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1721K]

  • Optimization simulation of separator vortex finder of 300 MW CFB boiler and its effect on boiler

    YUAN Ye;LIN Weirong;SHI Zhenghai;GAO Hongpei;SUN Xianbin;XIAO Ping;Huaneng Clean Energy Research Institute;

    In order to solve the problems,i.e.,fine particles diffusion,pressure drop of boiler bed,low temperature of outlet flue gas and insufficient output,the vortex finder of a 300 MW CFB boiler was optimized and retrofitted.The separation efficiency of separator with vortex finder optimized and its influence on operation effect of boiler were verified by CFD method.The vortex finder was optimized by increasing the insertion depth of vortex finder to reduce the particle escape,reducing the diameter of vortex finder and eccentric layout of necking,lessen particles entering the exhaust pipe The CFD theoretical calculation and fly ash particle size distribution test show that the pressure drop of the separator increases by ca.370 Pa after optimizing the vortex finder shape,and the total separation efficiency of the separator increases to 99.45%,which Increases by 0.54%.The separation effect is good and the proportion of small particles is high.The average bed temperature decreases by 20 ℃ and the differential pressure of upper furnace increases by 0.3 k Pa after retrofitting the vortex finder.The median diameter of fly ash particles decreases from 23 μm to 12.6 μm.The boiler efficiency is improved and the urea consumption is reduced by 50%-70%.The theoretical calculation and field test prove that the design is reasonable and effective.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 50K]

  • Effect of bentonite binder on denitrification performance of activated coke

    WANG Yuhang;SUN Zhongchao;XIONG Yinwu;ZHANG Haoqiang;Coal Chemistry Branch of China Coal Research Institute;Beijing Key Laboratory of Coal Based Carbon Materials;State Key Laboratory of Coal Mining and Clean Utilization;

    Activated coke samples with different content of bentonite,i.e.,0,10%,20%,30% and 40%,was prepared to study the effect of bentonite binder on denitrification performance of activated coke.The effects of different mass fraction bentonite on iodine value,ash content,loading density,abrasion resistance,compressive strength,pore structure and denitrification efficiency were investigated by conventional index analysis,N2 adsorption-desorption method and denitrification evaluation in a fixed bed.The results show that bentonite can replace part of high temperature coal tar as binder for preparing active coke.When the addition amount is less than 20%,the iodine value,loading density,pore development degree and denitrification efficiency of active coke are improved. Meanwhile,the ash content and compressive strength of active coke are significantly affected by bentonite binder.Specifically,the ash content increases from 7.76% to 30. 75% and the compressive strength decreases from 682 N to 114 N with the addition amount of bentonite increasing from 0 to 40%.The performance of active coke with 20% bentonite is best,and the iodine value,loading density,ash content,compressive strength,abrasion resistance,specific surface and denitrification efficiency are 406 mg/g,616 g/L,19.33%,375 N,95.4%,329.70 m2/g and 73.2%,respectively.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1607K]

  • Dry high-efficiency technology for coal-fired flue gas pollutants control

    CHAI Shu;WANG Qian;MENG Li;ZHU Weiqun;School of Chemistry and Chemical Engineering,Shandong University;National Engineering Research Center of Colloidal Materails;

    In order to avoid water soluble salt emission from wet flue desulfurization brume in coal-fired power plant,a dry high-efficiency technology for coal-fired plants flue gas pollutants control was proposed in this paper.Pilot scale desulfurization test was carried out in a170 t/h pulverized coal fired boiler,and the denitrification tests were implemented in 75 t/h pulverized coal fired boiler and 220 t/h CFB boilers.Products quality and tech-economic were also analyzed.Results show that the concentration of SO2 after treated decreases to 20 mg/m~3 from 4 200 mg/m~3,and the content of NO_x reduces to 15 mg/m~3.Sulfur content in products is 0.73%,which meets the national standard.Investment cost is 1 million and running cost of desulfurization and denitrification in a 170 t/h pulverized coal fired boiler is 3. 582 million/year,meanwhile the revenue is 13.139 million/year due to electricity price compensation and economizes in charges for disposing pollutants.Further,the technology features lower the water consumption,none water soluble salt emission,less equipment investment and maintenance costs,thus it is thought be a appropriate approach to solve haze problem in China.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1520K]

  • Energy efficiency calculation of drum slag cooler

    HE Jianping;LI Jianfeng;FENG Bin;WANG Zhenshan;LYU Junfu;Shenhua Shendong Electric Power Shanxi Hequ Power Generation Co.,Ltd.;China Electricity Council;Beijing Guohua Economic Information Consulting Co.,Ltd.;Qingdao Jianenghainuo Power Equipment Co.,Ltd.;Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Tsinghua University;

    In order to further improve the utilization of the bottom slag residual heat of the drum slag cooler and increase the revenue of the circulating fluidized bed boiler unit,the energy efficiency calculation model of the drum slag cooler and the unit system were established and calculated based on a 350 MW supercritical CFB boiler unit.The calculation results show that for the present drum slag cooler,the bulk thermal efficiency will decrease after controlling the cooling water flow and increasing the outlet water temperature,while the unit power generation increases.When the outlet water temperature increases to 150 ℃,although the efficiency of the drum slag cooler reduces to less than 90%,the power generation capacity of the unit can increase exceed 1.1 MW since drum slag cooler can directly enter the deaerator.For the new unit,the thermal efficiency can be maintained while reducing the cooling water flow of the drum slag cooler.Further,the power generation value of the unit increases close to 1.2 MW when the outlet water temperature is also 150 ℃.Therefore,continuously increasing the outlet temperature is the most important technical development direction of the drum slag cooler.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1958K]

  • Study on the heating technology of wet and cold condensing steam turbine unit

    WU Junjie;MENG Tao;PAN Cuicui;GD Long Yuan Energy Conservation Technology Co.,Ltd.;

    The traditional heat and power combined heating unit uses the medium pressure steam to heat the hot water,and there is a partial loss at the cold end.The high backpressure heating scheme and the heat pump scheme can supply the heating from extracting low pressure cylinder exhaust and reduce the heat supply.Taking a 350 MW power plant as an example,through theoretical calculation and energy-saving analysis,pumping heat,high back pressure heating supply and heat pump heating supply were investigated from the viewpoint of heating capacity,power generation load,coal consumption and thermoelectric ratio.The coal consumption of power generation of three heating modes are the lowest when running in power setting in heat,namely in the minimum exhaust volume operation. The coal consumption of power generation by pumping heating and heat pump heating mode increases significantly when running inthermoelectric decoupling mode.Heat pump heating mode is superior to high back pressure heating mode in heating guarantee rate.The high back pressure heating scheme is suitable for high heating load and power setting in heat.Heat pump heating scheme has a high heat supply load,and it can realize thermoelectric decoupling.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1298K]

  • Experimental study on ultra-low emission of high-sulfur coal combustion in thermal unit by swirl atomization

    LIU Dingping;MA Peipei;ZHOU Jun;School of Electric Power,South China University of Technology;Guangdong Essen Environmental Technology Co.,Ltd.;

    Due to small diameter of desulfurization tower and high flow rate of flue gas,the flue gas desulfurization and de-dusting are difficult to achieve ultra-low emission.Taking a 300 MW thermal power generating unit as example,the swirling atomization desulphurization and de-dusting integrated technology was upgraded to study the effects of liquid-gas ratio and inlet flue gas temperature on desulfurization efficiency and dust removal efficiency. The results show that the dust concentration of inlet and outlet in desulfurization tower are30 mg/Nm~3 and less than 5 mg/Nm~3,respectively with the swirling atomization desulphurization and de-dusting integrated technology,and desulfurization and de-dusting can complete in the single desulfurization tower without humidification.At a certain liquid-gas ratio,the flue gas inlet temperature and SO_2 concentration have little effect on the efficiency of desulfurization tower,the desulfurization efficiency can be stabilized above 99.29%,and the desulfurization tower dust removal efficiency is as high as 90.84%,indicating the swirling atomization desulphurization and de-dusting integrated technology has good adaptability and system stability.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 52K]

  • Optimization of SNCR denitration technology in circulating fluidized bed boiler

    SHI Lei;ZHANG Shixin;Huaneng Clean Energy Research Institute;State Key Laboratory of Coal-based Clean Energy;

    In order to achieve NO_x emission standard of circulating fluidized bed( CFB) boiler,the current NO_x control method and application in China were described.Taking urea and ammonia as the reducing agents,and combining with CFB boiler denitration situation in a certain power plant in northwest of China,the principle,main SNCR denitration process flow and equipment were introduced.Besides,the advantages of SNCR denitration in 300 MW CFB boiler were analyzed.Combined with the characteristics of CFB boiler,the original SNCR equipment was modified and then the modified effect was analyze.The results show that,the action of reducing agent regulating valve is obviously more accurate and NO_x emission is more stable by adjusting the position of measuring points and optimizing control logic.The injection mode of horizontal flue is changed from horizontal twine to staggered twine,with a distance of 0.3 m staggered,so that more flue gas can contact with the reducing agent and improve reaction efficiency.By changing the operation mode,reducing the primary air volume and increasing the supply of secondary air,the original NO_x emissions can be reduced by 10%.After the modification,SNCR denitration device can control the NO_x emission value below 50 mg/Nm~3( calculated by NO2 and converted to 6% O_2 concentration),and denitration efficiency is higher than 85%.At the same time,the ammonia nitrogen ratio is not higher than 1.8,and ammonia escape value is reduced from 7×10~(-6) to 3×10~(-6),which can effectively improve the denitration efficiency and system stability.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 50K]

  • Optimization of determination method for slurry droplets carried by coal-fired flue gas after demister

    GAO Demin;WANG Zhongwei;Tongliao Huolinhe Pithead Power Generation Co.,Ltd.;SPIC Northeast Electric Power Co.,Ltd.;

    In order to measure the slurry droplet content at the outlet of demister in desulfurization system more accurately,the advantages and disadvantages of determination method for slurry droplets at the outlet of demister were analyzed,and the national standard slurry droplet sampling method was optimized. An improved slurry droplets sampling method was proposed,which can realize equal-speed velocity sampling and is a simplified method for measuring and calculating the concentration of slurry droplets. Furthermore,comparative experiments were carried out.The experimental results show that there is a large escape rate in the national standard slurry droplet trapping method.Compared with the improved slurry droplet sampling method,the escape rates of the national standard slurry droplet sampling method are 39.84% and 41.41% in Unit 1 and 2 respectively,and the average escape rate is 40.6%.The improved slurry droplet sampling analysis method can measure the slurry droplets entrained by purified flue gas after the demister more accurately,and it can provide the basis for the performance evaluation of desulfurization system.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 44K]

  • Research on control system of SCR in thermal power plant based on feedforward compensation

    ZHANG Chao;China Coal Research Institute Company of Energy Conservation;

    SCR system has the features of large delays and inertia which makes it difficult to realize the accurate control of ammonia injection based on traditional PID method during the process of start and stop of coal mill.In view of this problem,start and stop signal was selected by analyzing of operation data to build feedforward compensator for ammonia injection and SCR ammonia injection optimal control strategy was proposed based on cascade control method.The effect of the control strategy was confirmed through constant value disturbance test,variable load test and coal mill load test.The results show that ammonia injection optimal control strategy solves the problem of NO_x concentration exceeded discharge standard during the process of start and stop of coal mill,control performance of SCR system is improved and the timely and accurate control of the amount of injecting ammonia is achieved.Optimization control strategy has good performance on the efficiency of denitration and avoiding excessive injection of ammonia.Both of the dynamic and static regulating quality of SCR system could meet the relevant national standards.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1899K]

  • Analysis and precautionary on deposition and coking characteristics in coal direct liquefaction plant

    WANG Jianli;WANG Xiwu;Ordos Coal Liquefaction Company,China Shenhua Coal to Liquid and Chemical Co.,Ltd.;

    In order to reduce the influence of deposition and coking of coal direct liquefaction equipment on production process,efficient methods on mitigating or eliminating the deposition and coking during coal direct liquefaction was proposed by analyzing the deposition and coking sites and the regularity of the device.The results show that proper increase the flow rate of the medium,eliminating the local dead zone,reducing the amount of material adhesion can significantly mitigate or eliminate deposition and coking.Additionally,measures,such as reducing local temperature and improving filtration accuracy,are used to slow down or eliminate deposition or coking.Meanwhile,the effect of modification and optimization of relevant measures on prevention of deposition and coking has been verified.The coking amount of the hot medium pressure separator is reduced from 1.86 t to 0.27 t through the implementation of the above measures.The pulverized coal deposition in the cold and high pressure separator is reduced from 0.56 t to 0.05 t,and the vacuum furnace feed continuous operation.The time is extended from the original less than 2 months to more than 6 months,and the reactor operating time is increased from 200 days to 420 days.Therefore,the problem of deposition and coking of coal direct liquefaction equipment are effectively mitigated or eliminated.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 2448K]

  • Wear forms and selection principle of lining material for coal cyclone

    LIANG Hao;Test Branch of China Coal Research Institute;

    Cyclone is the main separation or concentration equipment in coal preparation plant.Based on the working principle of the cyclone,the causes and wear forms of the lining wear of the cyclone were analyzed.high-speed rotating friction of solid-liquid two-phase flow accompanied by impact damage is the main reason for the damage and wear of the cyclone lining.Impact wear and micro cutting wear are the main forms of wear damage of cyclone lining.The characteristics of metal and metal compounds,polyurethane products and non-metal wear-resistant materials used in the cyclone lining were analyzed in this paper,and the selection principle of the cyclone lining materials was proposed.Specifically,the polyurethane material can be used in the coal slurry heavy medium cyclone with an inner diameter less than350 mm,and the cyclone with an inner diameter less than 500 mm.The high chromium cast iron material is mainly used in the concentration cyclone with a diameter less than 500 mm,and the alumina material,toughened alumina or silicon nitride ceramics is recommended using in the separation heavy medium cyclone.

    2018 06 v.24;No.118 [Abstract][OnlineView][HTML全文][Download 1056K]
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