2020年06期目次

  • Research progress of the decarburization technology of coal gasification ash slag

    SHI Da;ZHANG Jianbo;YANG Chennian;QU Jiangshan;LI Shaopeng;LI Huiquan;HE Fayu;School of Resources and Civil Engineering,Northeastern University;Key Laboratory of Green Process and Engineering,Institute of Process Engineering,Chinese Academy of Science;National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology;University of Chinese Academy of Science;China Minmetals Corporation;

    Coal gasification technology is the foundation of modern coal chemical industry in China.In this process,the organic matter in coal is converted into chemicals,and the inorganic matter is discharged in the form of gasification slag.At present,coal gasification slag is mainly stored in piles,causing serious environmental and water pollution.In the process of dissipating coal gasification slag,because of the large amount of unburned carbon inside,the large-scale utilization channels such as construction materials and building materials are limited.Although the current carbon and ash separation methods at home and abroad have certain effects,they are basically in the stage of laboratory research and semi-industrial testing.Due to the problems of high cost and low separation efficiency,large-scale industrial applications have not been realized.The separation of carbon ash is affected by the mineral phase composition,phase composition,particle size distribution,micro-morphology and other factors of coal gasification slag.Different types of gasification slag need to adopt different separation processes to achieve efficient separation of carbon and ash.Combined with the main influencing factors of coal gasification slag decarburization,the main technology and equipment of coal gasification slag decarbonization were analyzed,the main separation methods of carbon and ash components of coal gasification slag were expounded from multiple angles,and the technological characteristics and shortcomings of each sorting method were further Summarized and compared.Finally,the development trend of various technologies in the decarbonization and separation of coal gasification slag was analyzed,and the development of new green,efficient,and low-cost flotation reagents was pointed out to solve the problem of unburned carbon-ash adsorption cover.The separation technology and equipment for the decarbonization of granular coal gasification slag and the realization of high-value utilization of decarbonization separation products is an important development direction of current coal gasification slag decarbonization technology.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 2190K]

  • Research progress on the fly ash ceramsite

    CHAI Chunjing;SONG Huiping;FENG Zhengjun;ZHANG Jincai;CHENG Fangqin;State Environmental Protection Key Laboratory of Efficient Resource Utilization Techniques of Coal Waste,Institute of Resources and Environmental Engineering,Shanxi University;

    Fly ash is the fine ash collected from the flue gas after coal combustion,which is the main solid waste discharged from coal-fired power plants,and has great harm to the environment and human health. The preparation of ceramsite by using fly ash is one of the important ways to recycle fly ash. Because of its excellent properties such as small density,light weight,heat preservation,heat insulation,good fire resistance,good anti-seismic performance,low water absorption,good anti-freezing performance and good durability,the fly ash ceramsite has wide application prospects in the fields of waste water treatment,waste gas treatment,noise control and building materials,etc. In this review,the latest development of fly ash ceramisite in recent years was reviewed and the feasibility of preparing fly ash ceramsite by roasting process and unburned process was analyzed. The related research results of fly ash ceramisite were introduced. The mechanism,raw materials,technological conditions and product properties of producing roasting ceramsite and unburned ceramsite by using fly ash were emphatically introduced. At the same time,the main problems and solutions in the comprehensive utilization of fly ash in China were put forward and the future development trend was forecasted,so as to provide reference for the research on the mechanism and technology of preparing ceramsite with fly ash. The results show that the preparation process of fly ash roasted ceramsite mainly includes batching,mixing,granulation,drying,pre-firing,roasting,cooling and screening. The main factors that affect the properties of the roasted ceramsite are raw material ratio,preheating time,preheating temperature,heating rate,calcination time,calcination temperature,etc. The preparation process of fly ash unburned ceramsite mainly includes batching,mixing,granulation,aging,drying,curing and cooling.The main factors that affect the properties of the unburned ceramsite are the properties of raw materials,the amount of activator,the amount of binder,the type and amount of foaming agent,curing method,steam curing temperature and curing time. The products with different properties and uses can be prepared by changing the process conditions. At present,fly ash ceramsite is mainly roasted ceramsite. Roasted ceramsite has the advantages of mature technology and high product strength,but it has the disadvantages of high energy consumption,large investment and complex process. Therefore,the development of fly ash unburned ceramsite has become a new trend. The unfired ceramsite is still in the development stage,and the products have the disadvantages of low strength and small specific surface area. It overcomes the disadvantages of high cost and pollution in the preparation of ceramsite by roasting method,and can be used in the situation where the requirements of cylinder compression strength is low and bulk density is high in the future. In order to improve the performance of ceramsite and reduce the cost,the selection of additives,technology and environmental safety of porous unburned ceramsite can be studied in depth. The preparation of ceramsite with fly ash not only solves the pollution problem of fly ash,but also solves the source of ceramsite raw materials,which has important practical significance.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 8913K]

  • Research progress of application of fly ash in coatings

    TANG Mingxiu;SONG Huiping;XUE Fangbin;State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources,Institute of Resources and Environment Engineering,Shanxi University;

    Fly ash is a kind of waste residue produced by coal-fired power plant. If it is not treated for a long time,it will harm human body and natural environment. Because of its own structure,pozzolanic effect and filling effect,fly ash can be used as secondary resource again. As a big fly ash emission country,China has been actively looking for more effective ways to use fly ash to improve the utilization rate of fly ash. In recent years,with the development of the coating industry,the demand for fillers is gradually increasing,and appropriate filler substitutes are needed at home and abroad to reduce the cost of coatings. Many scholars have used fly ash as raw material in the coating industry. According to the properties of fly ash,various functional coatings have been made and found to have good performance and economic effect. In this paper,the production of fly ash and its environmental problems,the basic characteristics of fly ash was introduced,and the coatings according to their functions were classified. The main principle,technology and product performance evaluation of various coatings were mainly described. The research progress of fly ash in coating industry at home and abroad was summarized. The main problems existing in the application of fly ash in coating industry were summarized. The results show that the low thermal conductivity of fly ash conforms to the heat barrier mechanism,and it can be combined with other thermal insulation materials to form a thermal insulation coating with multiple heat insulation mechanisms such as reflecting heat and blocking heat,which can be applied on the wall surface to improve the heat insulation effect. The physical and chemical properties of fly ash are stable and high temperature resistant,and its fire resistance can make fly ash act as smoke suppressor and flame retardant in flame retardant coatings,which is suitable for fire protection treatment of steel structure,wood surface and tunnel inner wall; fly ash has cementation effect,which can enhance the density of materials by interaction with other materials,and introduce electrochemical mechanism to improve the corrosion resistance,which can be used to reduce the corrosion degree of cement,metal and other surfaces; through the activation and modification of fly ash and the combination with crystalline materials,a more compact structure is formed,which has excellent resistance to penetration and waterproofing. Fly ash mixed with suspending agent,dispersant and binder can be used as a casting coating to protect castings on casting surface,so as to improve molding effect and facilitate demoulding. Polymer emulsion,cement and modifier are added to increase the bonding strength of coal ash and coal seam,thus opening up the ability of plugging coating as underground mine,and the compact coating effectively prevent the leakage of dangerous gas underground. Using fly ash as raw material,different types of functional coatings prepared by various processes,which the economic cost of raw materials is reduced and the waste resources are reused. Although fly ash has made more progress in the coating industry,there are still some problems due to technical limitations. The color,residual carbon and utilization rate of fly ash as coating filler are still the focus of the next research.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 10299K]

  • Influence of the physical and chemical composition of coal gangue on its resource utilization

    LI Zhen;WANG Junzhang;SHEN Liming;ZHAO Junji;SHI Pengfei;WANG Jie;ZHU Tao;Shanxi Lu'an Mining (Group) Co.,Ltd.;Institute of Atmospheric Environmental Management and Pollution Control,China University of Mining & Technology-Beijing;

    Coal gangue is a by-product of associated coal mining and sorting. The accumulated gangue cannot be properly used,which will cause serious environmental pollution and waste of resources. In recent years,the study of coal gangue utilization has been promoted due to the stricter environmental regulations and the potential use value of coal gangue in China. However,many studies have overlooked that due to the wide distribution of coal in China,the physical and chemical composition of coal gangue in different regions will be different. Based on the physicochemical composition of coal gangue,the importance of the physical and chemical properties of coal gangue on its utilization ways was elaborated from four aspects of the energy industry,construction industry,soil application industry and high-value application industry. The risk of secondary environmental pollution caused by different components was analyzed,and the potential problems and future research trends in the field of comprehensive utilization of coal gangue were pointed out. It is recommended that when choosing a way to use coal gangue,the requirements of the basic physical and chemical composition of the way should be considered,and increase the requirements for the physical and chemical components in the gangue that may cause secondary environmental pollution risks should be increased.In order to improve the utilization rate and economic benefits of the gangue,and reduce the risk of environmental pollution,the best use plan is selected based on the balance of the two,and the follow-up environmental secondary pollution risk assessment and follow-up investigation are established.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 1449K]

  • Study on the adaptive management of eastern grassland coal and power base based on regional ecological security

    MA Yan;MA Yan;LI Shuyi;WANG Ziyuan;SUN Xiang;ZHANG Meng;HAN Zhiyuan;TIAN Yuge;LU Zhaohua;School of Chemical and Environmental Engineering,China University of Mining and Technology-Beijing;Guorui Ward Low Carbon Economy and Technology Center;Guangzhou Sewage Purification Company Limited;School of Resource and Environment and Materials,Guanxi University;

    In order to achieve the best balance between regional ecological protection and economic development,the adaptive management theory of coal power base was discussed based on regional ecological security,starting from the systematicness and complexity of environmental problems in coal power base.The management objects,objectives and contents were discussed in depth,and the theoretical framework of adaptive management was constructed.The management objectives including resource development objectives,economic benefits objectives and ecological benefits objectives were determined; the management contents mainly include regional ecological security assessment,adaptive management suggestions and adjustment of management schemes; and the adaptive management framework with feedback function is established.Taking the coal power base in Xilinguole League of eastern grassland as an example,the adaptive management theory of coal power base based on regional ecological security is gradually clear and tends to be specific,which also provides reference for the evaluation and prediction of ecological security of coal power base in eastern grassland.The results show that: the coordination of ecological security in Xilinguole League is poor,and the overall ecological carrying capacity and ecosystem service value still need to be improved; in the view of the regional ecological security problems in Xilinguole,the coordination degree of ecological security in Xilinguole League should be further analyzed in terms of the coupling and coordination of ecosystem; the current situation of land use should be adjusted and a new land use pattern Bureau should be established to minimize human interference and destruction.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 2419K]

  • Dynamice valuation on eco-environmental quality of coal resource-based cities based on analytical hierarchy process

    LI Hanqing;CHEN Liqiang;ZHU Tao;Institute of Huai River Water Resources Protection;Institute of Atmospheric Environmental Management and Pollution Control,China University of Mining & Technology-Beijing;

    Coal resource-based cities refer to the cities built and developed relying on the exploitation and utilization of coal resources.With the long-term development and utilization of coal resources,the deterioration of the quality of the ecological environment has increasingly become an important factor restricting the development of coal resource-based cities. Therefore,the dynamic evaluation of the ecological environment quality of coal resource-based cities can enable decision-makers to clarify the changes in the ecological environment of coal resource-based cities,find out its restrictive factors,and provide technical support for the improvement of ecological environment quality and urban transformation and development.Taking Huainan City as an example,the dynamic evaluation index system and the comprehensive index model of ecological environment quality of coal resource-based cities were constructed from three aspects of the natural environment,social and economic environment,environmental pollution control by Using Analytic Hierarchy Process( AHP). On this basis,combined with the actual situation of Huainan City,the ecological environment quality of Huainan City from 2010 to 2018 was dynamically evaluated. According to the evaluation results,suggestions for further improving the ecological environment quality of Huainan City were put forward.The results show that the ecological environment quality of Huainan City shows a fluctuating upward trend from 2010 to 2018,which declines slightly from 2013 to 2015,and gradually increases after 2015. But overall,the ecological environment quality of Huainan City is improving. In order to further improve the quality of the ecological environment,Huainan needs to be based on the " 14 th Five-Year Plan",completes the top-level design,optimize the industrial structure,build a two-wheel drive modern industrial system,and actively promote the ecological environment construction focusing on the treatment of coal mining subsidence areas,pay equal attention to natural environmental protection and environmental pollution control,so as to guarantee the quality of the ecological environment continues to improve.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 1870K]

  • Research on aqueous TETA/AMP solution for CO2 capture

    SUN Luchang;LIAN Shaohan;WANG Kailiang;WANG Zhengrong;ZHANG Shiming;HAN Wenquan;SONG Chunfeng;China Huadian Engineering Co.,Ltd.;School of Environmental Science and Technology,Tianjin University;Jiangsu Huadian Jurong Power Generation Co.,Ltd.;

    As one of the main technologies in CCUs process,chemical absorption technologies have been widely used in CO_2 capture and purification process. However,traditional industrial MEA solution as absorbent has many disadvantages,such as high energy consumption,strong corrosion and degeneration. Therefore,the development of a new generation of composite amine absorbent has become the focus of current research. In this study,based on the sterically hindered amine 2-amino-2-methyl-1-propanol( AMP),a series of TETA/AMP composite water-based absorbents were synthesized for CO_2 capture in flue gas. Through the comparison test of absorption-desorption performance of solutions with different ratios,the absorption capacity,absorption rate,regeneration rate and other factors were comprehensively investigated,and finally the best ratio was obtained. And it is found that the TETA/AMP composite absorption liquid with a mass ratio of 1: 1 has the best absorption and desorption performance. Compared with pure AMP,its saturated absorption capacity is nearly doubled,and the maximum regeneration rate can reach 0.03 g/min. In the process of CO_2 absorption by the composite absorbent,the sterically hindered amine AMP with a faster absorption rate can quickly capture and activate CO_2 molecules,and then it is transfered to the alkenylamine TETA with multiple reaction sites for storage. In the desorption process,due to the steric hindrance effect of AMP,the connection with CO_2 molecules is easier to be broken,thereby increasing the regeneration rate. At the same time,quantum chemical calculations are used to simulate the monomers and compound unit,so as to deduce the formation process of the compound system. In this work,the relationship between the distribution of the electrostatic potential on the molecular surface and the monomers forming the compound system was discovered,the role of different functional groups in the formation of the compound system was analyzed,and the necessity of the hydroxyl group in the formation of the compound system was proposed.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 6350K]

  • Research on physico-chemical characteristics and its leaching toxicity of fly ash from a MSW incinerator in Northwest China

    YANG Chennian;ZHANG Jianbo;QU Jiangshan;SHI Da;LI Shaopeng;LI Huiquan;Key Laboratory of Green Process and Engineering,Institute of Process Engineering,Chinese Academy of Science;National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology;University of Chinese Academy of Science;School of Resources and Civil Engineering,Northeastern University;

    The chemical composition and mineral phase of waste incineration fly ash are the intuitive expression of its internal mineralogical information. In order to clarify the basic physical and chemical properties of waste incineration fly ash,X-ray fluorescence spectrometer,X-ray diffraction,BET specific surface area analyzer,scanning electron microscope,electron probe and other detection methods were used to study the chemical composition,mineral phase structure,pore and specific surface area,and element occurrence morphology of two typical waste incineration fly ash produced in Northwest China. The leaching toxicity of two typical waste incineration fly ash was analyzed by the toxicity characteristic leaching procedure( TCLP). The results show that the main chemical composition of fly ash produced after incineration of sludge garbage and domestic garbage are Ca O,SiO_2 and Al_2O_3,accompanied by heavy metal toxic elements such as Pb,Cr.The mineral phase of sludge incineration fly ash is mainly aluminum phosphate,quartz,calcium aluminosilicate,mixed with iron oxide ore phase,and its toxic metal species are less and dispersed in the fly ash,only a small part of Ti is combined with aluminum Silicates.The mineral phase of the fly ash from domestic waste incineration mainly exists in the form of calcium aluminosilicate phase and is mixed with some soluble chloride salts. S/Ca and Ca/Si/Al are relatively enriched in the fly ash from domestic waste incineration,other elements are combined with Cl,and toxic metals are various and dispersed. Through TCLP leaching experiments,it is found that there is the possibility of heavy metals leached in incineration fly ash. Therefore,it is necessary to properly dispose of waste incineration fly ash to reduce its environmental risks.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 14922K]

  • Experimental research on free fired bricks preparation using waste liquid after extracting aluminum and silicon from coal gangue

    ZHANG Ning;ZHANG Zepeng;SONG Huiping;State Environmental Protection Key Laboratory of Efficient Resource Utilization Techniques of Coal Waste,Institute of Resources and Environmental Engineering,Shanxi University;

    In order to solve the potential problem of waste liquid produced in the process of extracting aluminum and silicon from coal gangue,the waste liquid is used as a raw material to prepare free fired bricks which is a promising way of treatment. The effects of adding the aluminum and silicon extraction waste liquid on the main performance indexes of free fired brick,such as compressive strength,frost resistance and water absorption were studied and analyzed; the interal mechanism of the influence of aluminum and silicon extraction waste liquid on the above parameters were explained by SEM and XRD analysis. The result shows that when the waste liquid of aluminum and silicon extraction from coal gangue is used to prepare unfired brick,the compressive strength of the brick can be reduced by adding waste liquid. The compressive strength of unfired brick is 23.75 MPa,reduced by 4.93 MPa when adding 50% waste liquid as a substitute of water,and the compressive strength is 21.34 MPa,reduced by 7.34 MPa when the content is 100%. The salt ions in the waste liquid seep to the brick surface and the pores are formed during this process. Moreover,softer anhydrite and calcite appear with the addition of waste liquid,which can lead to the decrease of compactness and compressive strength of free fired brick. In the frost resistance tests,when the content is 50%,the strength loss rate of the free fired brick after 15 freeze-thaw cycles is 2.82%,and the mass loss rate is 0.35%;when the content is 100%,the strength loss rate after 15 freeze-thaw cycles is-28.12%,and the mass loss rate is 0.76%. Based on the dual effects of waste liquid,the positive effect of 100% waste liquid is exerted completely in tests,resulting in the increase of compressive strength instead of decreasing. In the water absorption tests,when the content is 50%,the water absorption rate is 28.29% after soaking for24 h; when the content is 100%,the water absorption rate of free fired brick is 29.99% after soaking for 24 h. The water absorption rate of free fired brick increases with the addition of waste liquid of aluminum and silicon extraction from coal gangue.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 10276K]

  • Research on removal performance of fluoride from coal chemical wastewater by activated alumina

    WANG Jikun;LI Yang;LIU Min;LI Wenbo;China Coal Research Institute;

    In order to make activated alumina more widely used in the field of coal chemical wastewater defluoridation,and ensure that the fluoride of effluent could meet the requirements of class Ⅲ water body in GB 3838—2002 environmental quality standard for surface water( the fluoride in the effluent is reduced to ≤1 mg/L). The experimental effect of activated alumina on the fluoride removal performance of coal chemical wastewater was studied. The continuous defluorination experiment of activated alumina with particle size of 1-2 mm was carried out. The effects of the dosage,pH value of influent,residence time and adsorption time of activated alumina on the defluorination rate were studied to obtain the best experimental conditions for the fluorine content of coal chemical wastewater effluent to be less than or equal to 1 mg/L. The " practicality" of activated alumina was investigated under the best technological conditions. Finally,the reaction kinetics of activated alumina for removing fluorine was studied. The experimental results show that the larger the activated alumina loading is,the greater the fluoride removal rate is,and the lower the fluoride content in the effluent is. When the loading amount of activated alumina is ≥60 g,the fluoride content in the effluent can still be maintained at ≤1 mg/L after 40 h of continuous adsorption; The smaller pH is,the greater the fluoride removal rate is. When the pH is ≤6,the fluoride content in the effluent can still be maintained at ≤1 mg/L after 40 h of continuous adsorption; The longer the adsorption time is,the lower the fluoride removal rate is. When the adsorption time is ≤45 h,the effluent fluoride content is less than or equal to 1 mg/L and when the adsorption time is more than 45 h,the content of fluoride in the effluent is more than 1 mg/L; The longer the residence time is,the higher the fluoride removal rate is. When the residence time is 6-8 min,the effluent will be continuously adsorbed after 40 h,and the fluoride content is ≤1 mg/L. When the activated alumina loading is 60 g,the influent pH is ≤6,the residence time is 6-8 min,and the adsorption time is ≤45 h,the fluorine content of the outlet water can be kept at≤1 mg/L. The activated alumina after defluorination is regenerated with aluminum sulfate and the experiment is repeated,the effluent fluorine content is still well maintained below 1 mg/L,indicating active oxidation aluminum has a good " practical application" for removing fluoride from coal chemical wastewater. At the same time,the reaction kinetic equation of activated alumina to remove fluoride is a first-order reaction,and the adsorption effect is best when the fluorine content is 3 mg/L.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 3616K]

  • Study on sulfur distribution of raw coal in Daliuta Coal Preparation Plant

    WANG Wei;Shendong Coal Group;

    With the long-term high-intensity development and the increase of mining depth,the quality of raw coal of Shendong mining area deteriorates gradually,and the sulfur content of commercial coal also increases gradually.Based on the above,the representative raw coal of Shendong mining area was selected as the research object.The grain size distribution,density distribution rule and the embedded structure of sulfur-bearing minerals of the raw coal,including total sulfur and morphological sulfur were comprehensively analyzed by screening,floating and sinking,and scanning electron microscope.The suggestions for the coal preparation plant to further improve the production process were put forward.The main conclusions are as follows.The results show that the gangue in the selected raw coal of Shendong mining area is brittle,and more fine particles are enriched in the mining process,resulting in a higher ash and sulfur content of fine particles in the raw coal.The ash content of < 0.5 mm partial fraction is more than 5 percentage points higher than other grain levels,and the sulfur content also reaches more than 0.7%.Lump coal of >13 mm grain size accountes for 52.13%,the ash content is lower than other grain size and the sulfur content increases significantly. On the whole,with the increase of floating and settling density,the total sulfur content of raw coal increases slowly at first,and then increases rapidly after exceeding 1.6 g/cm3.When the floating and settling density is consistent,the total sulfur content of coarse particles is higher than that of fine particles on the whole.While the sulfur content of coarse particles in the range of >1.8 g/cm3 is lower than that of fine particles,indicating that with the decrease of raw coal particle size,the degree of dissociation of sulfur-bearing minerals gradually increases,and the inorganic minerals concentrate to high-density materials. The sulfur content of raw coal in Shendong mining area is mainly pyrite sulfur,accounting for more than 60%,followed by organic sulfur. In low density,organic sulfur is the dominant sulfur content,while in high density,pyrite sulfur is the dominant sulfur content. Pyrite sulfur is mainly distributed in the form of veins and grains,and the disseminated particle size is about 0.1 mm. In the subsequent production,the coal preparation plant should further reduce the selected upper limit according to the actual situation and realize the sulfur in the raw coal mineral fully disintegrate.At the same time,it should be actively to develop the selective removal of fine material into the desulfurization techniques such as magnetic separation,fine classification desliming technology.Meanwhile,the online detection technology of sulfur content should be strengthened to guarantee the quality of coal.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 6185K]

  • Migration rule of coal macerals in coal-to-oil preparation plant

    ZHU Ziqi;CHN Energy Shendong Coal Preparation Center;

    The refined coal products produced by Shenhua coal-to-oil preparation plant are supplied to coal-to-oil companies as raw materials for oil production.In order to provide better raw materials and high quality raw coal for oil production,the migration law of coal macerals in the process of washing and processing was explored,and then a new idea was provided for the optimization of the following production process.Taking the process sample of coal-to-oil preparation plant as the test coal sample,and by using process samples,industrial analysis,microscope analysis and infrared spectrum analysis,and combined with on-line measuring tools,the migration of different organic components in the production process was analyzed,and the theoretical approach to improve product quality in coal preparation plant was given.The results show that the H/C ratio of Shenhua raw coal is 0.84,which is a good raw material for coal-to-liquids.The content of raw coal ash is 9.45%,vitrinite content is 57.88%,inertinite content is 38.18%.The content of 0.50-0.25 mm vitrinite is 55.97%.The existing technology does not effectively separate the coarse coal slime,so it is necessary to strengthen the separation of coarse coal slime.It is difficult to enrich vitrinite by crushing and sieving because the contents of macerals in different sizes are not very different.In vitrinite group,88% enter into heavy medium cleaned coal,7% into coarse slime,5% into fine slime,and in inertinite group,59% enter into heavy medium cleaned coal,25% into gangue,7% into coarse slime,9% into fine slime.The high efficiency separation between inertinite and vitrinite by the existing separation process needs to be improved,which includes improving the selectivity and reducing the separation density.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 4718K]

  • Adsorption performance of quinoline in coking polluted groundwater from Shendong long flame coal

    CONG Rihong;GAO Qieyuan;CHN Energy Shendong Coal Preparation centre;National Engineering Research centre of coal preparation and purification,China University of Mining and Technology;

    As a product of coal processing,the high quality utilization of slime is a key problem in the field of coal processing. Shendong mining area,as the main producing area of long flame coal in China,produces a lot of slime every year,and it's necessary to study the utilization way of high quality slime. In this paper,the adsorption of quinoline from coking tail water by long flame coal in Shendong mining area was studied. The properties of coal samples were analyzed by laser particle size analyzer,SEM,BET,XRF and XPS. The influence of factors such as the dosage of long flame coal,adsorption contact time and initial concentration on adsorption effect was investigated by single factor test. The relationship between surface structure,properties and adsorption performance of long flame coal was discussed. The results show that Shendong long flame coal is a natural carbon-based adsorbent with rough surface and developed pore structure,with a specific surface area of 17.53 m~2/g. The surface pore structure is mesoporous,the surface contains oxygen-containing functional groups,and there are inorganic minerals. Shendong long flame coal has good adsorption effect on quinoline. Under the optimal conditions of the dosage 6 g/L,the contact time 30 min,and the initial concentration 4 mg/L,the removal rate of quinoline in simulated wastewater by Shendong long flame coal is 81. 46%. The adsorption behavior is found to accord with Freundlich isotherm model,indicating that the adsorption process is mainly dominated by multi-layer adsorption on the coal surface. The adsorption behavior is related to the surface properties and pore size of quinoline and long flame coal. According to the fitting parameters,the adsorption of quinoline on Shendong coal slime is easy to occur,and the adsorption performance is good.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 5363K]

  • Effect of inorganic salts and surfactants on dewatering performance of fine low-rank coal slime

    YAN Yang;HUANG Luhua;CHN Energy Shendong Coal Preparation Centre;National Engineering Research Centre of Coal Preparation and Purification,China University of Mining and Technology;

    Aiming at the problems of high moisture content and the difficulty in dewatering of fine low rank coal particles in the Boertai coal preparation plant,in this paper,the dewatering performance of low rank coal slime was evaluated by using inorganic salts and surfactants.The results show that the coal samples from Boertai coal preparation plant have the characteristics of fine particle size,great high-density content,abundant surface oxygen-containing functional groups,and high gangue content. When FeCl_3 and PAC are used to dewater coal slime,the filtration rate increases significantly by 0.129 and 0.113 mL/( s·cm~2) respectively,and the moisture content of filter cake decreases to a certain extent; when using surfactant,DTAC and Tween 85 accelerate the filtration speed greatly and reduce the moisture content of filter cake,the moisture content of filter cake decreases by 0. 69% and 1. 03%,and the filtration rate increases by 0. 301 and0.152 mL/( s·cm~2); in the mixture of inorganic salt and surfactant,the dehydration effect of non-ionic Tween 85 and anionic sodium oleate is significantly improved.When Tween 85 co-existes with FeCl_3 and PAC,the cake moisture decreases by 1.39% and 1.52% respectively,and the filtration rate increases by 0.044 and 0.040 mL/( s·cm~2),respectively. When sodium oleate co-existes with FeCl_3 and PAC,the moisture content of filter cake decreases by 2.79% and 2.61%,and the filtration rate increases by 0.026 and 0.021 mL/( s·cm~2),respectively. FeCl_3 and PAC can decrease the surface activity of DTAC,and have little effect on the surface activity of Tween 85,but can increase the surface activity of sodium oleate significantly. The results show that the existence of three surfactants can improve the surface hydrophobicity of low rank coal,and the addition of inorganic salts promotes the adsorption of anionic and non-ionic surfactants on the surface of low rank coal,thus enhancing the improvement of surface hydrophobicity of low rank coal.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 9464K]

  • Current status and prospect of white moist plume elimination technology in coal-fired power plants

    YANG Xiaoyang;WANG Fei;YANG Fengling;ZHANG Chanbao;CHENG Fangqin;Collaborative Innovation Center of High Value-Added Utilization of Coal-related Wastes,State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources,Shanxi University;Shanxi HuaRenTong Electric Power Technology Co.,Ltd.;

    With the increasingly complete and strict environmental protection policies in China,the demand for the treatment of " white plumes" formed by the saturated wet flue gas discharged into the atmosphere after wet desulfurization in power plants has increased.Through the research on the formation and elimination mechanism of white plume,the advantages,disadvantages and application prospects of the current technology for eliminating white plume in coal-fired power plants were analyzed. The existing technologies for eliminating white moist plume at home and abroad mainly include flue gas condensation,flue gas heating,condensation reheating,swirling dehumidification,solution absorption,and membrane separation.All of the flue gas cooling,flue gas heating,and condensation reheating technologies use direct/indirect heat exchange to change the state of flue gas at the outlet to achieve whitening.The technology is relatively mature and has been applied in engineering,but it has high energy consumption and high anti-corrosion requirements of heat exchange equipment;GGH has high cost and high energy consumption.Although the cyclone dehumidification technology has a large load,pressure reduction and simple structure,its whitening effect is limited; The technology of solution dehumidification and membrane separation is still in the experimental research stage at present,and it has not been used in the wet flue gas treatment process of coal-fired power plants due to its own technical defects.Instantaneous pressure condensation dehumidification technology of flue gas uses the flow field structure to instantly increase the partial pressure of water vapor,so as to make it liquefied.At the same time,steam condensation and liquefaction will release a lot of latent heat,which can improve the flue gas outlet temperature.The synergistic effect of flue gas dehumidification and heating finally ensures the saturation of wet flue gas white.In this paper,the characteristics and adaptability of various treatment technologies were discussed and compared. Combined with experiments,it is found that the instantaneous pressurized condensation and whitening technology of flue gas can effectively recover the water vapor in the wet flue gas.The fine particles and other pollutants in the saturated steam are removed as condensation nuclei by the condensation droplets during the steam condensation process. At the same time,other heat exchange equipment is not needed,which reduces energy consumption.It is one of the potential technologies in the flue gas whitening technology.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 4362K]

  • A two-parameter prediction method for specific heat capacity of high-temperature inorganic crystal materials

    WEI Xiaolin;LI Teng;LI Bo;SUN Cen;State Key Laboratory of High Temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Sciences;School of Engineering Science,University of Chinese Academy of Sciences;

    High-temperature solid specific heat capacity is commonly used thermal property data in industrial process design,but it is difficult to obtain these data of solid with the temperature of thousands of degrees by actual measurement. Therefore,many solids with complex lattice often only have the measurement data of specific heat capacity within a limited temperature range. The Einstein and Debye models can be applied to simple mono-atomic crystals or some bi-atomic crystals for specific heat capacity prediction. However,it is difficult to accurately obtain the Debye and Einstein temperatures of polyatomic intricate lattice solids,making it difficult for Einstein and Debye models to predict these solids' specific heat capacity accurately. In this paper,based on the statistical thermodynamic method,and to determine the specific heat capacity for a solid with multiple atoms,a two-parameter prediction method for the high-temperature solid's specific heat capacity was proposed. In this method,the solid lattice vibration mode is divided into acoustic and optical branches. It is assumed that a single lattice cell has a unique Debye characteristic temperature Θ_D and Einstein temperature Θ_E.Moreover,the Debye characteristic temperature Θ_D is obtained through the basic parameters of crystallography. The Einstein temperature Θ_E of intricate lattice solid is calculated backward through the limited experimental data of the specific heat capacity of the solid or the thermal properties of simple substance. Then the solid's theoretical specific heat capacity can be predicted utilizing these two parameters at different temperatures.The two parameter prediction method is used to predict the specific heat capacity of typical monoatomic,diatomic and Polyatomic Crystals.The comparison between the calculation results and the experimental data results show that the two-parameter prediction method's error is mainly at the temperature inflection point and the high-temperature region. The prediction error of the specific heat capacity in the wide range of temperature range is less than 5%,which is expected to provide a reliable and straightforward method to determine the thermal and physical properties of solids for the process industries.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 4906K]

  • Comparative analysis on distribution difference and reactivity of the typical Shenhua coals/cokes functional groups

    XIANG Baixiang;XIONG Xiaohe;LU Xuchao;HUANG Jun;LYU Zhaomin;TAN Houzhang;Shenhua Guohua (Beijing) Electric Power Research Institute Co.,Ltd.;MOE Key Laboratory of Thermo-Fluid Science and Engineering,Xi'an Jiaotong University;

    Because of enormous reserves,good ignition and burnout characteristics,Shenhua coal has become a kind of important power coal used in China.The annual consumption is more thanten percent of the gross coal consumption. There are many kinds of Shenhua coal,which can be divided into high ash fusion point( e.g.,Carboniferous,Junggar coal) and low ash fusion point( e.g.,Shenhun) in terms of ash fusion temperature.The output of low ash melting point coal is large,which is generally the main coal for power plant.However,in order to prevent slagging,the high and low ash fusion coal are blended in appropriate proportions( e.g.,7 ∶ 3,8 ∶ 2).To date,the researches mainly focused on the engineering application of Shnehua coal,whereas the investigation on the microstructure difference of different Shenhua coal has rarely been reported. Thus,two typical Shenhua coals,such as Shenhun coal and Carboniferous coal,were selected to characterize and compare the functional group distribution of raw coal and coal char by infrared spectroscopy in this work.The results show that the distribution of the functional group in Shenhun coal is similar to that in Carboniferous coal.Both Shenhun and Carboniferous coal find the alkane group,including carbon-carbon double bond,carbon-carbon triple bond,methyl and methylene group,the nitrogen-containing and sufur-containing groups. In term of FTIR absorption strength,the functional groups of Carboniferous coal is higher than that of Shenhun coal.However,FTIR absorption strength measurements show that the carbon-carbon double bond,methyl and methylene group in Shenhun char is higher than that in Carboniferous char.This is probably because the fatty chain in Shenhun and Carboniferous coal are almost of the same length.The length of fatty chain of Carboniferous char increases significantly,meanwhile,that of Shenhun char shows little change.In addition,It is observed by SEM thatthere is obviously alternative banded rock-coal structure in Shenhun coal. However,the crystalline structure becomes in order,and the pore structure increases significantly after coking.The oxidation activity of Shenhun coke and Carboniferous char was compared by thermogravimetric reactor.Additionally,it is found that the reactivity of Shenhun char is obviously higher than that of Carboniferous char,and Shenhun coke is more flammable.Therefore,from the comparison of combustion characteristics,it is appropriate to choose Shenhun as the main fuel coal.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 10032K]

  • Study on process conditions on reactivity of catalytic liquefaction of Aiding lignite

    LIANG Jiangpeng;Coal Chemistry Branch of China Coal Research Institute;Beijing Key Laboratory of Coal Based Carbon Materials;National Energy Technology & Equipment Laboratory of Coal Utilization and Emission Control;State Key Laboratory of Coal Mining and Clean Utilization;

    In order to study the reactivity of Aiding lignite in direct liquefaction,the direct liquefaction of Aiding lignite was studied in the horizontal oscillating autoclave.The effects of reaction temperature,reaction time and H2 initial pressure on the direct liquefaction reactivity of Aiding lignite were investigated.The results show that the suitable reaction conditions of Aiding lignite liquefaction are as follows: reaction temperature is 430 ℃,reaction time is 60 min,initial hydrogen pressure is 8.5 MPa,catalyst addition is 1%( Fe/daf coal),solvent to coal ratio( weight ratio) is 55 ∶ 45; The increase of reaction temperature,initial hydrogen pressure and reaction time can promote the increase of oil yield and conversion,and the effect of initial hydrogen pressure on conversion is relatively small.The yield of asphaltene first increases and then decreases with the increase of reaction temperature and hydrogen initial pressure,and decreases with the increase of reaction time.With the increase of reaction temperature,hydrogen initial pressure and residence time,the yield of preasphaltene decreases.Asphaltene and preasphaltene have the characteristics of intermediate products,and the increase of reaction temperature,hydrogen initial pressure and reaction time is favorable for the conversion to oil and gas.The C_(daf),H_(daf)and the ratio of H/C atoms in residual coal decrease with the increase of reaction temperature.The higher the hydrogen content in coal is,the easier it is to liquefy.With the increase of reaction temperature,the inert structure with lower hydrogen content is difficult to liquefy and becomes the main component of residual coal. The C_(daf),H_(daf)and the ratio of N/C atoms in residual coal decrease with the increase of reaction temperature,When the reaction temperature reaches 430 ℃,the ratio of N/C atoms in residual coal changes significantly,the hydrogenation performance of nitrogenous structure in coal is remarkable,and the denitrogenation ability is improved obviously.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 5165K]

  • Study on actinomycetes screening and technological conditions for biodegradation of photooxidized lignites

    LI Jiantao;LIU Xiangrong;SHI Chen;ZHUANG Sukai;College of Chemical Engineering and Modern Materials,Shangluo University;Shaanxi Key Laboratory of Comprehensive Utilization of Tailings Resources;College of Chemistry and Chemical Engineering,Xi'an University of Science and Technology;

    Microbial degradation of coal is an effective way for efficient and clean utilization of low rank coal,and actinomycetes are one of the main microbes to degrade low rank coal.Photooxidation pretreatment of low rank coal can increase the oxygen content of low rank coal,which will help to improve the biodegradation rate of coal by microorganism.In order to obtain high-efficiency biodegradation strain of lignite,five actinomycetes and four photooxidized lignites were tested by actinomycete-coal matching experiments.After comparing the degradation effect of 5 kinds of actinomycetes and 4 kinds of photooxidation lignite,the dominant strain selected was Streptomyces viridosporous.Taking the absorbance value at 450 nm of the degradation solution obtained by Streptomyces viridosporous as the index,the single factor experiments were carried out to determine the technological condition of biodegradation of Inner Mongolia Shengli lignite by Streptomyces viridosporous. Finally,the determined optimum technological conditions were listed as follows: coal slurry mass concentration of 0.2 g/20 mL,inoculums size of 3.0 mL/20 mL,incubation time of 10 d,oscillation frequency of 160 r/min,coal particle size of 0.150-0.075 mm and incubation temperature of 28 ℃ .According to this condition,the degradation effects of Streptomyces viridosporous degrading GZTH,GHYH and GYBH were studied.The results show that under this condition,the degradation effects of Streptomyces viridosporous degrading the three lignites are all improved to some extent. It can be seen that the process conditions of photooxidation lignite degraded by Streptomyces viridosporous taking Shengli lignite in Inner Mongolia as the sample has a certain universality for the degradation process of different photooxidation lignite,which can be used as a reference for the study of the better process conditions for the degradation of photooxidation lignite by Streptomyces viridosporous.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 3348K]

  • Experimental research on preparation of active carbon using Yulin long flame coal

    ZHANG Xuhui;Beijing Guodian Futong Science and Technology Development Co.,Ltd.;NARI Group Corporation (Stated Grid Electric Power Research Institute);

    In order to optimize preparation parameters of coal based activated carbon using Yulin coal as the raw material,the carbonization and activation test equipment for preparation of activated carbon was designed and built. The experiment factors influencing the activated carbon performance were carried out.The orthogonal test method was used to test the carbonization process and activation process.The COD removal capacity of chemical wastewater was used as the main evaluation method to determine the optimal process parameters. The structure characteristic of the activated carbon obtained under the optimal process parameters were analyzed by BET and SEM test to find out the main factors affecting the COD removal ability. The results show that activated carbon is prepared by using Hongliulin coal as raw material by the pyrolysis activation method.The influence degree of raw coal pyrolysis process factors are pyrolysis temperature,heating rate,and pyrolysis residence time,successively.The semi-coke iodine adsorption value is 135.66 mg/g in the best pyrolysis process parameters with 600 ℃,2 ℃/min,and 30 min.It shows that the semi-coke formed by the coal pyrolysis process has owing preliminary adsorption capacity and pore structure,which is conducive to further activation to turn into the activated carbon. The influence degree of the semi-coke activation process factors in order are activation temperature,activation time,and steam penetration rate. The best activation process parameters are activation temperature of 850 ℃,activation time of 3 h,and steam introduction rate of 15 L/min.The highest chemical wastewater COD removal rate of the activated carbon obtained in the best activation condition is 70.97%,which can be treat effectively.The specific surface area of the activated carbon is 671.50 m2/g,and there are both micropores and mesopores in different quantity. The distribution of micropores is mainly 0.7 nm,and the distribution of mesopores is 5-20 nm.The research indicates that the Yulin coal can be processed to produce activated carbon with rich mesopores under optimizing process parameters,which can effectively remove chemical wastewater COD.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 8196K]

  • Research on CO2 separation of displacing coal-bed methane

    LI Xuefei;CHE Yongfang;GUO Haoqian;LI Xiaoliang;Coal Chemistry Branch of China Coal Research Institute;Beijing Key Laboratory of Coal Based Carbon Materials;State Key Laboratory of High Efficient Mining and Clean Utilization of Coal Resources;

    CO_2 sequestration enhancing coalbed methane recovery( CO_2_ECBM) is one of the important ways of CO_2 utilization.The underground storage and utilization of CO_2 can be realized,and recovery rate of coalbed methane can be improved by CO_2-ECBM.Affected by the complexity of coal seam geological conditions,CO_2 can't be completely sealed in coal seam after injection,and will gradually seep out with CBM drainage.The displacement of coal-bed methane containing CO_2 needs to be separated and removed before it could be transported to the pipeline network.Aiming at the production,composition and pressure conditions of displacement CBM,the adsorption characteristics of CO_2 and CH_4 on carbon molecular sieves were measured,and the equilibrium separation coefficients of CO_2/CH_4 were calculated.The separation and purification experiments of CO_2/CH_4 were carried out by pressure swing adsorption evaluation device,and the amount of adsorbent treated and the recovery of CH_4 were calculated.The results show that the adsorption of CO_2 and CH_4 on carbon molecule conforms to type I adsorption isotherm.The adsorption capacity of CO_2 is 1.27 mol/kg,the adsorption capacity of CH_4 is 0.48 mol/kg.The equilibrium separation coefficient of CO_2/CH_4 is 3.38,and the separation ratio of carbon molecular sieves is high,which is mainly based on the kinetic rate.CO_2 is got as adsorptive phase,CH_4 is got as non-adsorptive phase.With the condition of adsorption pressure of 600 k Pa,and adsorption time of 120 s,the concentration of CO_2 in the CO_2/CH_4 separation product gas was below 1% after pressure swing adsorption separation.With the condition of adsorption pressure of 500 k Pa,and adsorption time of 120 s,the concentration of CO_2 in the CO_2/CH_4 separation tail gas separation product gas was below 5% after pressure swing adsorption separation.The final product gas would be got with the mixing of the CO_2/CH_4 separated gas and the purified gas from the separation tail gas. CO_2/CH_4 is separated and purified by pressure swing adsorption,and the concentration of CO_2 in the product gas is below 1%.Taking 1 200 Nm~3/d of single well production as an example,treatment capacity of adsorbent per unit is about 100 Nm~3/h,and the recovery rate of CH_4 reaches 92.375%. The displaced CBM can be separated and purified by pressure swing adsorption to remove CO_2,and then transported to the pipeline network.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 7180K]

  • Numerical simulation of the performance of cyclone separator with adjustable efficiency in CFB boiler

    YUAN Donghui;SUN Shichao;ZHENG Xiuping;HAN Yi;WANG Yankai;DUAN Lunbo;Inner Mongolia Electric Power Research Institute Branch,Inner Monglia Electric Power (Group) Co.,Ltd.;Key Laboratory of Energy Thermal Conversion and Control,Ministry of Education,Southeast University;Inner Mongolia Jingtai Power Generation Co.,Ltd.;

    The holes are opened at the center point 50 cm away from the top of the conical cylinder on the inclined plane of the cyclone separator.The opening in the inlet direction of the cyclone separator is named as 0° hole which is rotated 90° clockwise from the inlet direction of the cyclone separator,and named as 90° hole,180° hole and 270° hole,respectively.The separator efficiency is adjusted by introducing interference wind into the opening of conical cylinder of cyclone separator,but the influence of the interference wind on the pressure drop of the cyclone separator is unkuown.In order to study the effect of the interference wind on the whole performance of the cycle including pressure drop,separation efficiency and bed temperature change,and get the best opening scheme,the pressure drop characteristics of a 300 MWe CFB cyclone with adjustable separation efficiency were studied by numerical simulation in this paper.Firstly,the pressure drop at different inlet velocities was simulated without interference wind,and the results were compared with the calculation results of empirical pressure drop model.The results show that the pressure drop increases with the increase of inlet velocity,and the simulation results are in good agreement with Chen-Shi model.Then the pressure drop is simulated when the inlet velocity is 7.48 m/s and the interference wind speed is 10,20 and 30 m/s at 0°,90°,180° and 270° holes,respectively.The results show that the pressure drop decreases with the increase of the interference wind speed in the 0° and 90° holes,and the pressure drop first increases and then decreases with the increase of the interference wind speed in the 180° and 270° holes.Combined with the variation of bed temperature when the interference wind is introduced into different holes,it can be considered that the 90° hole is a better reconstruction scheme.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 8078K]

  • Study on the reaction mechanism of thermal decomposition reaction of CaSO4 and graphite

    ZHAO Liang;Institute of Engineering Thermophysics,Chinese Academy of Sciences;University of Chinese Academy of Sciences;

    The reaction of carbothermal decomposition of calcium sulfate( CaSO_4) generally occurs in circulating fluidized bed boilers that use furnace desulfurization. It is of great significance to in-depth study the reaction mechanism for improving the sulfur fixation performance in the furnace. Based on the experiment of thermogravimetric and mass spectrometry,the equivalent characteristic spectrum( ECSA) method was used to deeply explore the reaction process of graphite thermal decomposition of CaSO_4. Besides,combined with the horizontal tube furnace experiment,the solid product after the reaction was characterized. The temperature range of the main reactions in the decomposition of CaSO_4 was comprehensively analyzed. The results show that based on the experimental data of thermogravimetric mass spectrometry combined with ECSA,the main reaction process of graphite thermal decomposition of CaSO_4 can be well analyzed. The selfdecomposition reaction of CaSO_4 occurs at about 1 100 ℃,and the addition of graphite reduces the decomposition of CaSO_4 temperature to about 900 ℃,while increasing the fastest decomposition rate and shortening the complete weight loss time. At about 1 050 ℃,the rate of thermal decomposition of CaSO_4 by graphite is the fastest,but the temperature corresponding to the maximum decomposition rate is not correlated with the amount of graphite added. With the increase of the molar ratio of graphite and CaSO_4 increases,the fastest reaction rate of the decomposition of CaSO_4 gradually increases,and the temperature of thermal decomposition of CaSO_4 decreases slightly and tends to be stable. In the process of thermal decomposition,the reaction of CO_2,SO_2 and Ca O is the most important reaction product. When the reaction temperature is higher than 1100℃,the reaction between graphite and residual CaSO_4 will also occur to generate Ca S and CO_2,but to a small extent.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 8994K]

  • Simulation and internal component optimization of active coke desulfurization and denitrification reactor

    ZHANG Yunlei;LIANG Daming;SUN Zhongchao;XIONG Yinwu;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;

    With the tightening of environmental protection policies,the requirements for flue gas emissions are becoming more and more strict,and the removal of industrial exhaust pollutants faces a serious situation.Compared with the traditional flue gas purification process,the activated coke flue gas purification process has the technical characteristics of water saving,energy saving and no secondary pollution.As the core of the process,the research of the reactor has become the key to restrict the development of this technology.Taking the active desulfurization and denitration reactor of a certain project as the research object,a numerical analysis model was established and the pressure drop values between the model and the field device under different working conditions were compared.The average deviation between the two is 5.9%.The model can reflect the actual operation of the device to a certain extent.On this basis,CFD software was used to simulate and analyze the flow field inside the reactor and the concentration field of key components. According to the simulation results,the flue gas flow in the inlet chamber of the reactor is turbulent,and eddy currents and cavities appear,which leads to a difference in the residence time of flue gas in the active coke layer.In addition,according to the distribution map of ammonia mass fraction in the ammonia injection area,it can be seen that the uneven distribution of ammonia gas has a negative impact on the removal efficiency of system pollutants.In view of the above problems,the method of adding internal components in the reactor is adopted to improve the removal efficiency of the system pollutants.In order to improve the uniformity of flue gas at the inlet of the reactor,a deflector was installed at the flue gas inlet of the reactor and the optimization effects of three different types of deflector were compared and analyzed.The results show that the equidistant stepped curved deflector is installed at the flue gas inlet,the effect of uniform distribution of flue gas is the best.The uniformity of air flow in the system is increased by 11% and the pressure drop is reduced by 267 Pa compared with that before adding deflector.As the ammonia selective catalytic reduction method is adopted for flue gas denitrification of activated coke,ammonia gas needs to be injected as a reducing agent during the denitration process.Under a certain amount of ammonia injection,whether the ammonia gas concentration distribution in the denitration zone of the reactor is uniform directly affects the final denitration efficiency of the system.In order to improve the uniformity of ammonia concentration distribution,a porous plate is added on the basis of the original ammonia spray grid,and the porous plate is used to split and distribute the ammonia gas to achieve the purpose of mixing ammonia gas and flue gas in a short distance.Compared with the traditional method of reducing the diameter of the ammonia injection hole and increasing the number of ammonia injection tubes,the installation of perforated plate can reduce the risk of grid blockage during operation of the device and improve the stability of the device.The simulation results show that addition of porous plates above the ammonia spray grid improves the uniformity of ammonia spray by 21%.After optimization,the system's pollutant removal efficiency has reached more than 85%,meeting pollutant discharge requirements and improving system's operating stability,reducing risk of ash and pipe plugging. The correlation between simulation results and actual field operation data is good,indicating that simulation results are highly reliable and have some reference significance for actual production.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 9752K]

  • Industrial experimental study on the multi-pollutant collaborative control with activated carbon for coke oven flue gas

    WANG Bin;LI Yuran;LIU Lianji;CHEN Peng;GUO Junxiang;LIN Yuting;ZHU Tingyu;Beijing Engineering Research Center of Process Pollution Control,National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology,Institute of Process Engineering,Chinese Academy of Sciences;Tangshan Iron & Steel Group Co.,Ltd.;

    Now the situation of air pollution in China is still serious.The multi-pollutant collaborative control with activated carbons can simultaneously remove multi-pollutant,such as SO_2,NO_x and H_2S without water consumption and secondary pollution.It has been used in the flue gas purification of iron-steel sintering and coke oven et al,but the purification efficiency needs to be improved.In the coking industry,the activated carbon technology demands a higher denitrification efficiency and effectively capturing multiple pollutants for the coke oven flue gas with the emission characteristics of low sulfur,high nitrogen and multi-pollutant coexisting.In order to explore the factors to improve the efficiency of coke oven flue gas purification,the industrial test platform was built for multi-pollutant collaborative control with activated carbon for coke oven flue gas purification.The flue gas flow rate was 33 000 Nm~3/h. The moving speed of activated carbon and ammonia injection quantity were adjusted to investigate and optimize the flue gas purification efficiency. The effect of moving process on physical properties of activated carbon,properties of activated carbon after regeneration and carbon consumption were analyzed.The results indicate that the desulfurization efficiency and denitrification efficiency of the multi-pollutant collaborative control technology with activated carbon are more than 99% and 80%,respectively.The emission indexes meets the special emission standards( NO_x≤150 mg/Nm~3,SO_2≤30 mg/Nm~3,PM≤15 mg/Nm~3).The compressive strength of activated carbon obviously decreases by 33%-55% during the moving process,especially for the smaller diameter activated carbon,while the abrasion resistance decreases slightly,but the decrease range is small.The decrease of these two parameters will increase the consumption of activated carbon.The recovery rate of elemental sulfur in the regeneration process is up to 90%,and the specific surface area of activated carbon after adsorption( before regeneration) is approximately20 percent lower than fresh activated carbon.The physical carbon abrasion of activated carbon mainly depends on the moving speed,and the chemical carbon consumption depends on decomposition of the functional groups.The total carbon consumption of activated carbon is approximately 10.7 percent per year of the first loading capacity.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 7035K]

  • Reseach on SO3 morphological characteristics in flue gas of coal-fired power plants based on thermodynamic equilibrium calculation

    YU Weijing;MA Chao;TAN Wenbin;CUI Lei;LI Changhao;China Huadian Engineering Co.,Ltd.;

    SO_3 is one of the common pollutants discharged from coal-fired power plants,which has a great impact on the stable operation of system equipment and the quality of atmospheric environment. In order to deepen the relevant research,SO_3 morphologic transformation calculation model was established based on thermodynamics and acid dew point theory. The morphologic characteristics of different flue gas temperature,humidity and SO_3 concentration were calculated,and the distribution characteristics of SO_3 morphologic characteristics in flue gas from conventional coal-fired power plants were determined. The results show that SO_3 in flue gas of coal-fired power plants is mainly composed of SO_3 gas,H_2SO_4 gas and H_2SO_4 aerosol. The transformation of SO_3 is based on chemical reaction and physical reaction. The chemical reaction is that SO_3 gas reacts with H_2O gas to H_2SO_4 gas and the physical reaction is that H_2SO_4 gas condenses to H_2SO_4 aerosol by homogeneous and heterogeneous nucleation when flue gas temperature is lower than dew point,respectively. In addition,assuming the valve of humidity is 8%,when the flue gas temperature is lower than 202 ℃,higher than 495 ℃ and lower than 95 ℃,SO_3 exists in the form of H_2SO_4 gas,SO_3 gas and H_2SO_4 aerosol,respectively. Furthermore,combined with the distribution of flue gas humidity and temperature in conventional coal-fired power plants,the distribution characteristics of SO_3 are as follows: SO_3 gas,SO_3 gas and H_2SO_4 gas,H_2SO_4 gas and H_2SO_4 aerosol,H_2SO_4 aerosol exist the section ahead denitrification device,between denitrification device and air preheater,between air preheater and rear section of desulfurization unit,respectively. What is more,the particle size of H_2SO_4 aerosol is less than 0.1 μm.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 5199K]

  • Influence of particle sizes of bed material and fuel on denitration reaction in circulating fluidized bed

    ZHANG Yao;YU Juan;LIN Chen;FENG Fan;ZHANG Zhongxiao;School of Mechanical Engineering,Shanghai Jiao Tong University;

    With the vigorous development of the energy power industry,the situation of air pollution becomes increasingly severe,and the relevant environmental protection standards for NO_x emission control become increasingly strict. Selective non-catalytic reduction technology( SNCR) can effectively reduce NO_x emission,but the production of NO_x needs to be reduced from the source in order to further reduce NO_x emission in circulating fluidized bed.Therefore,the influence law of bed material and fuel particle size on denitration reaction has great research value.The effects of reaction temperature,molar ratio of ammonia to NO_x ,particle size ratio of bed material and average particle size of pulverized coal on NO_x emission were investigated by using the circulating fluidized bed thermal experiment system.The results show that the temperature range of NO_x reduction with ammonia reducing agent is 860-950 ℃ .The denitration efficiency of ammonia increases first and then decreases with the increase of NSR at different reaction temperatures. Increasing the proportion of fine particle bed material can effectively reduce the production of NO_x ,improve the denitration efficiency,and reduce the SNCR active reaction temperature.Among them,the denitrification efficiency of the bed material with the largest proportion of fine particles increases with the increase of NSR.When NSR = 2.0,the denitrification efficiency reaches the highest 42%,and the NO_x emission decreases to 215 mg/m~3.By appropriately reducing the average particle size of pulverized coal,the production of NO_x can be reduced and the SNCR reaction can be carried out at a lower temperature.At each temperature,the NO_x generated by pulverized coal with an average particle size of 330 μm decreases by 10-30 mg/m~3 compared with that of pulverized coal with an average particle size of 425 μm.At high temperature,the denitration efficiency of ammonia reducing agent increases obviously with the increase of fuel particle size.At lower temperature,the denitration efficiency of ammonia may decrease with the increase of fuel particle size.At 910 ℃,the denitration efficiency of pulverized coal with an average particle size of 600 μm is significantly 20%-30% higher than that of pulverized coal with an average particle size of 425 μm under different NSR.At860 ℃,the denitration efficiency of pulverized coal with an average particle size of 425 μm is significantly lower than that of pulverized coal with an average particle size of 330 μm.The main reason for this phenomenon is that the reduction reaction of ammonia is related to the initial concentration of NO_x and the reaction temperature.Ammonia has different reaction selectivity at different initial concentration and temperature.After determining the fuel particle size,the appropriate process operating parameters should be matched to meet the NO_x emission requirements.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 5915K]

  • DFT study on the adsorption of SO2 and catalytic formation of SO3 on the α-Fe2O3 surface

    WANG Yongbing;DAI Gaofeng;SHAN Zhiliang;WANG Xuebin;YOU Hongjun;TAN Houzhang;Xinjiang Uygur Autonomous Region Special Equipment Inspection and Research Institute;School of Energy and Power Engineering,Xi'an Jiaotong University;

    A large amount of SO_2 and a small amount of SO_3 are emitted from coal-fired power plants.The generation of SO_3 is not only harmful to the environment,but also dangerous to the safe operation of the power plant.Current studies show that Fe_2O_3 contained in the fly ash and the boiler wall have a significant catalytic effect on the SO_3formation.However,the research on the path and mechanism of SO_3catalytic formation by Fe_2O_3 is not deep enough.In this paper,theα-Fe_2O_3(001) surface was established firstly,and the adsorption configuration of SO_2and O_2onα-Fe_2O_3(001) surface was studied by density functional theory(DFT).The stable adsorption configuration of SO_2 and the dissociation pathway of O_2on Fe_2O_3(001) surface were obtained.The reaction path and energy barrier of catalytic formation of SO_3 onα-Fe_2O_3 surface were studied by using transition state search method.Then the energy barrier of catalytic formation of SO_3 in gas phase reaction were compared.The results show that the most stable adsorption configuration of SO_2 is that O and S atom in SO_2 are adsorbed above Fe atoms onα-Fe_2O_3,while S atom is not easy to be adsorbed above lattice oxygen ofα-Fe_2O_3 crystal.The adsorption energy of O_2 onα-Fe_2O_3 surface is greater than the maximum adsorption energy of SO_2,which means that O_2 is more easily adsorbed onα-Fe_2O_3 surface.In addition,O_2 is easy to dissociate and form O atom on the defect Fe_2O_3 surface with oxygen vacancy,which indicates thatα-Fe_2O_3 with oxygen vacancy is easier to promote the dissociation of O_2 and the generation of adsorbed oxygen on the surface.The L-H mechanism of SO_3 formation is that SO_2 and O atoms in the gas phase are adsorbed firstly on theα-Fe_2O_3 surface,and then combine to form SO_3,and the reaction energy barrier is 231.65 kJ/mol.The E-R mechanism is that SO_2in the gas phase reacts with adsorbed oxygen onα-Fe_2O_3surface to form SO_3while the reaction energy barrier is 24.82 k J/mol,which is less than that of L-H mechanism and far less than that of SO_3formation in gas phase reaction.The above results confirm that Fe_2O_3has a significant catalytic effect on the formation of SO_3,and the E-R mechanism is the dominant reaction mechanism.The existence of oxygen vacancy promotes the dissociation of O_2on the surface ofα-Fe_2O_3,and the surface adsorbed oxygen plays an important role in the catalytic process.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 9278K]

  • Experimental study on simultaneous desulfurization and denitrification by steelmaking slag for coke oven flue gas

    MENG Ziheng;WANG Chenye;WANG Xingrui;CHEN Yan;LI Huiquan;CAS Key Laboratory of Green Process and Engineering,Institute of Process Engineering,Chinese Academy of Sciences;National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology,Institute of Process Engineering,Chinese Academy of Sciences;School of Chemical Engineering,University of Chinese Academy of Sciences;

    A large amount of flue gas is emitted from the coke production process,and sulfur dioxide(SO_2) and nitrogen oxides(NO_x) in the flue gas cause environmental pollution.With the increasingly strict air pollutant emission standard of coking industry,in order to solve the air pollution of SO_2 and NO_x from coke oven flue gas,the combined desulfurization and denitrification experiments of coke oven flue gas in the self-made bubbling reactor were carried out with steel slag as absorbent.The effects of reaction temperature,concentration of steelmaking slag slurry,gas flow,SO_2 content as well as NO content on SO_2 and NO removal efficiency were investigated,and the optimal operating condition was obtained.Results show that the increase in temperature will reduce the reaction rate of NO oxidation,resulting in the decrease in the concentration of NO_2 produced,thereby reducing the denitration efficiency.The increase of slurry concentration will increase the p H value of the slurry and promote NO removal;the increase of the flue gas flow,that is,the decrease of the residence time will reduce the gas-liquid contact time,resulting in the decrease in the desulfurization and denitration efficiency;when the optimal operating condition is reaction temperature of 30℃,steelmaking slag slurry concentration of 8% and gas flow of 400 m L/min,the denitrification efficiency can reach 50.7% and desulphurization efficiency is above 95%.Research on the mechanism of simultaneous desulfurization and denitration of steel slag show that:the OH~-dissolved from steel slag can keep the slurry alkaline and has a high p H buffering capacity,which is beneficial to the removal of SO_2 and NO_x;NO reacts with O_2 to form NO_2,and NO_2 reacts with OH~-to form NO_2~- and NO_3~-;NO_2 reacts with NO to generate N_2O_3,which is soluble in water,and N_2O_3 reacts with OH~-to generate NO_2~-,thereby achieving NO_xremoval.NO is oxidized to NO_2 through the gas-phase pre-oxidation method.The results NO_2 and N_2O_3generated by the reaction of NO_2 with NO can be absorbed efficiently by steelmaking slag slurry,thereby reaching the general or ultra-low emission standard of NO_x,and achieving industrial application for simultaneous desulfurization and denitration using steelmaking slag.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 4249K]

  • Analysis of influencing factors on water balance of desulfurization system in wet plume treatment

    YANG Aiyong;SHU Xi;WEI Fei;ZHU Yeqing;National Environmental Protection Research Institute for Electric Power;

    At present,local governments pay more and more attention to the treatment of wet plume. Coal fired power plants,iron and steel,coking and other industries have carried out wet plume treatment reform.However,there is a lack of systematic analysis on the factors affecting the desulfurization water balance,which leads to the difficulty of controlling the desulfurization water balance or the flue gas temperature exceeding the standard.Based on the historical online data,theoretical analysis and calculation,in this paper,the influencing factors of desulfurization water balance in coal-fired power plants were comprehensively summarized and quantitatively analyzed.For the first time,the influence of coal quality,environmental conditions,denitrification and other environmental protection facilities on the water balance of desulfurization was clarified.The results show that the total water and hydrogen content of coal are the most important factors,and the difference of flue gas temperature of several typical coals is more than 10 ℃ .The influence of environmental temperature and humidity is obvious. When the ambient temperature rises from 0 ℃ to 40 ℃( assuming the relative humidity is 60%),the difference of flue gas temperature is 4.6 ℃ .Air excess coefficient( or oxygen content) also has a great influence.When the oxygen content increases from4% to 8%,the difference of exhaust gas temperature is more than 2.5 ℃ .When SNCR and other processes are used,urea solution contains a lot of water,and the influence on flue gas temperature of desulfurization can reach 1 ℃ .The influence of flue gas temperature at desulfurization inlet on flue gas temperature is obvious,and the specific difference is related to flue gas temperature and coal quality.In addition,the unit load and other factors will also have a greater impact on the desulfurization water balance. In the scheme of zero discharge of wastewater,high salinity wastewater from cooling tower wastewater is often used for demister flushing,which determines that the desulfurization system must receive make-up water and ensure water balance. The influence of different wet plume treatment schemes on the water balance of desulfurization is also different. The flue gas condensation technology has no effect,while the slurry cooling technology has a great impact.Therefore,in the technical solution selection and parameter design of wet plume treatment,the above factors should be considered comprehensively.Selecting the appropriate technical solution and design parameters is of great significance to reduce the investment and operation cost and improve the reliable operation of the system.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 3932K]

  • Investigation on the occurrence of carbon in gasification filter cake and its feasibility of circulating combustion

    LI Jinfeng;China Shenhua (Baotou) Charcoal Chemical Industry Co.,Ltd.;

    Coal gasification technology is an important technology for the efficient and clean conversion and utilization of coal.Its inorganic components account for about 20%,which is mainly discharged in the form of gasification ash and slag( gasification filter cake and coarse slag),and especially the content ofcarbon in gasification filter cake is about 20-50%,which is the key technical bottleneck of resource utilization.Due to the lack of in-depth analysis of the microscopic physical and chemical properties of carbon in gasification ash and slag,the carbon removal efficiency is low and the cost is high,and the resource utilization is difficult.At present,it is mainly handled by stacking,resulting in serious environmental pollution. In the view of the above problems,the gasification filter cake obtained from entrained flow gasification of a company in Inner Mongolia was taken as the research object in this study.XRD spectrum refinement,particle size analyzer,scanning electron microscope,carbon and sulfur analyzer,thermogravimetric analyzer,ash melting point analyzer and other methods were adopted to study and analyze the elements/minerals phase composition,carbon crystallinity,the distribution of carbon in different particle sizes,the morphology and microstructure of carbon and inorganic phase,the weight loss range of carbon,and the reactivity of gasification filter cake.The results show that the carbon in the gasification filter cake is mainly composed of amorphous carbon with high reactivity and inert graphite carbon with the proportions of 92.94% and 7.06% respectively,which is mainly determined by the type of coal and gasification conditions.The morphology of carbon in the gasification filter cake includes flocculent carbon particles which exist alone and irregular carbon particles fused with inorganic components.The fine particles have a high carbon content and the coarse particles have a high inorganic component content.Under the condition of 500-700 ℃,a weight loss bythermogravimetric analysis is up to 27.38%,which is consistent with the results of carbon and sulfur analysis and muffle furnace loss of ignition,indicating that this part of the loss of ignition is mainly caused by the pyrolysis of carbon at high temperature.Through the analysis of ash melting point,it is found that the softening temperature is 1 130 ℃ and the flow temperature is 1 247 ℃ .The reactivity is high in the range of coal gasification temperature.It can be used for circulation of blending combustion to realize efficient recovery and utilization of carbon resources.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 4827K]

  • Theory and practice of ammonia production by hydrolysis of urea for flue gas denitration

    SUN Liqun;WU Chong;China Huadian Engineering Co.,Ltd.;

    Flue gas denitrification treatment must be carried out for flue gas in thermal power generation and petrochemical industries.When NOxis reduced to harmless N2,it is then discharged into the atmosphere. Denitrification reducers are usually liquid ammonia and urea. Due to the major security hidden danger of liquid ammonia,there are certain limits on storage and transport,and liquid ammonia has been listed as one of major hazards. Urea is the most choice for reducing agent at present. Ammonia production from urea decomposition includes urea pyrolysis and urea hydrolysis technology,and urea hydrolysis technology is divided into ordinary urea water solution urea and catalytic hydrolysis technology. By studying the reaction mechanism of urea ordinary hydrolysis technology without catalyst and urea catalytic hydrolysis technology with catalyst,as well as the change of reaction rate,hydrolysis rate and energy consumption random group load,it is found that adding urea catalytic hydrolysis catalyst manufacturing technology by adding ammonia catalyst changes the chemical reactions in the middle of the process. At the same temperature conditions,the addition of catalyst makes chemical reaction activation energy reduced,the reaction rate constant,reaction speed and response speed faster,so as to achieve the effect low-temperature operation,thus resulting in lower energy consumption and increasing urea utilization rate of more than 99%; Corrosion is reduced,which solves the rapid change of ammonia demand and corrosion caused by high temperature operation that the ordinary hydrolysis can not meet. It is found that an intermediate product is formed by the reaction between the catalyst and urea. And the intermediate product is decomposed into a catalyst,which is not consumed in the whole reaction and does not increase the operating cost of the system compared with the ordinary hydrolysis technology.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 4324K]

  • Cause analysis and countermeasure research on environmental protection parameter abnormity of CFB Unit

    DU Jiajun;ZHANG Peng;HAN Xinjian;Shenhua Group CFB Technology R&D Center;

    In recent years,with the increasingly strict requirements of air pollutant emission standards,most circulating fluidized bed units have added with desulfurization and denitrification facilities outside the furnace,and the combined mode of inside and outside the furnace is used to control pollutant emission concentration.However,due to the the characteristics of CFB boiler such as high thermal inertia and desulphurization lagging in furnace,the key equipment failures and poor operation adjustment control,abnormal environmental parameters are easy to occur in the start-up and shutdown of the unit,which will affect its safety and environmental protection operation.Based on the discussion of the pollutant control process and technical route of CFB Unit,the key influencing factors of pollutant original emission and the key points of removal process were analyzed,the abnormal phenomena and causes of SO_2,NO_x and soot were studied,and the countermeasures were put forward from the aspects of equipment failure,operation adjustment,automatic control,start-up and shutdown of the unit.The results show that the abnormal SO_2 of CFB unit is mainly caused by the large change of sulfur content in coal,coal blockage in coal bunker and poor return of material from the feeder,etc.The abnormal NOxis usually caused by low SNCR denitration efficiency during unit startup and shutdown,and CEMS system failure is the key reason for abnormal soot.Aiming at the abnormal environmental parameters,measures such as reducing the fluctuation of pollutant discharge concentration by strengthening the coal-burning quality and admixture management,using the anti-blocking technology of coal bin to solve the problem of coal blockage,eliminating the inconvenience of returner in unit load-lifting,strengthening the maintenance of pollutant control and monitoring system,automatically increasing the logic and feed-forward of pollutant estimation,setting the AGC adjustment rate and automatic blocking in different load sections,can effectively avoid abnormal environmental parameters in unit operation. In the start-up and shutdown of the unit,lime can be used as desulfurizer and flue gas recirculation can be used to control oxygen content,so as to further reduce the abnormal environmental parameters of the unit.

    2020 06 v.26;No.130 [Abstract][OnlineView][HTML全文][Download 3307K]



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