2023年12期目次

  • Research progress on CO2 reforming of biomass pyrolysis tar

    MA Xiaoqian;LIAO Yanfen;CHEN Xinfei;School of Electric Power,South China University of Technology;

    Pyrolysis technology for gas production in high temperature is an important research direction in the field of biomass resource utilization. However, the application of high temperature pyrolysis technology is limited due to the problems of clogging, corrosion, and difficult utilization of pyrolysis tar. The catalytic CO_2 reforming of pyrolysis tar can achieve the synergistic conversion of tar and CO_2 into H_2 and CO, reducing the content of pyrolysis tar and CO_2 and improving the energy recovery efficiency of the system. During catalytic CO_2 reforming of pyrolysis tar process, noble metal catalysts have high catalytic activity, but the large-scale industrial application of noble metal catalysts is limited due to the high cost. Among transition metal catalysts, nickel-based catalysts have high catalytic activity and low cost, but the reaction activity will decrease due to the problems such as sintering, agglomeration, and coke deposition of metal nickel particles at high temperatures, limiting the long-term operation of nickel-based catalysts. Due to the thermodynamic limitation, the active components of nickel-based catalysts are prone to agglomeration and sintering at high temperatures. Focusing on the sintering deactivation of nickel-based catalysts, the Taman temperature of nickel particle can be increased and the anti-sintering performance of nickel-based catalysts can be improved by doping a small amount of noble metals. On the other hand, constructing a core-shell structure on the surface of nickel particles can effectively limit the phase migration, agglomeration, and sintering deactivation of active metals by improving the dispersion of nickel metal particles in the shell layer. High temperatures in the catalytic CO_2 reforming of tar process can promote reactions, such as tar cracking and CO disproportionation to form coke deposition on catalyst surface. Considering the deactivation of coke deposition on nickel-based catalysts, metal doping modification, core shell structure modification, and air introduction can limit the deposition of filamentous and slow down the deactivation caused by coke deposition.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 12945K]

  • Research progress of the separation of carbon and ash in coal gasification fine slag

    ZHANG Ningning;ZHAO Fuqiang;HAN Rui;LI Zhen;ZHOU Anning;PANG Tian;College of Chemistry and Chemical Engineering,Xi′an University of Science and Technology;Key Laboratory of Coal Resources Exploration and Comprehensive Utilization,Ministry of Natural Resources of China;

    Coal gasification technology is widely used as the core technology for clean and efficient utilization of coal. Coal gasification fine slag(CGFS) is a solid waste consisting of ash components such as aluminosilicate and residual carbon produced by coal gasification process. At present, the treatment method of CGFS is mainly to stockpile and landfill, which not only pollutes the environment, but also causes waste of resources. The separation of carbon and ash is the basis for realizing the fractionated and high-value utilization of CGFS, and physical sorting is an important way to realize the separation of carbon and ash. Based on the analysis of the composition and structural characteristics of CGFS, the current research progress of carbon and ash separation of CGFS was reviewed, the advantages and main problems of each separation technology were pointed out, and the future development direction of carbon and ash separation of CGFS was prospected. Specifically, flotation has been most widely studied in carbon-ash separation of gasification fine slag, but there are drawbacks such as high consumption of chemicals and high cost of new flotation chemicals. The gravity separation method is not effective in separating fine-grained gasification slag. The electrical separation method is demanding on the water content of gasification slag samples. Dry separation technology has a better effect on the separation of carbon and ash from gasification slag, but it has not been promoted due to the difficulty of dehydration of gasification slag. The hydrophobic-hydrophilic two-liquid separation method is superior to flotation, but it is costly and potentially hazardous. In the future research on the separation of carbon and ash from gasification slag, it is very important to strengthen the basic research on the composition and structure of gasification slag, strengthen the research and development of new flotation chemicals and flotation technology, explore the realization path to improve the separation of carbon and ash through the multi-field and multi-process coupling, and construct a new type of classification standard for the separation of gasification slag products, so as to provide reference for the fine classification and high-value utilization of gasification slag.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 4155K]

  • Advances in preparation and properties of biomass-based carbon aerogel photocatalysts

    JIAO Yue;DING Jiaxuan;MEI Changtong;XIAO Huining;LI Jian;College of Materials Science and Engineering,Nanjing Forestry University;Chemical Engineering Department,New Brunswick University;Material Science and Engineering College,Northeast Forestry University;

    The efficient utilization of sunlight is an important research direction in the field of new energy. Photocatalysis, a technology harnessing sunlight for pollutants degradation, carbon dioxide reduction, water decomposition in hydrogen production, radioactive elements reduction and separation, photocatalytic nitrogen fixation and other difficult reactions under normal temperature and pressure, has the advantages of cheap, environmental protection, sustainable and so on. In the heterogeneous photocatalytic reaction, in order to prevent the solid phase photocatalyst from agglomeration or loss in the liquid phase or gas phase reaction environment, suitable supporting materials are needed to protect and fix the photocatalyst. Carbon aerogel has been widely studied in the field of photocatalysis because of its conductivity, chemical inertia and high specific surface area of carbon materials. Biomass-based carbon aerogels using biomass materials as precursors, have the advantages of environmental protection, lower cost, and wide sources of raw materials, compared to conventional carbon aerogels. In the paper, the characteristics of biomass-based carbon aerogels were summarized and the development status of biomass-based carbon aerogels as a new type of carbon aerogels was discussed. Finally, with the existing research, the feasibility and advantages of biomass-based carbon aerogels as photocatalyst supporting materials were proved, and suggestions for future research directions of biomass-based carbon aerogels were provided. Currently, biomass-based carbon aerogels have begun to show their prominence in many fields such as adsorption of heavy metals, oil-water separation, flexible capacitors, and electromagnetic wave absorption. In the field of photocatalysis, the method of loading photocatalysts on biomass-based carbon aerogels is still in its nascent stages, with a primary focus on the selection of biomass raw materials and the method of loading photocatalysts. Two main research directions include the preparation of carbon aerogels from cellulose aerogels and the preparation of carbon aerogels from porous plants as precursors. Compared with other biomass extracts such as protein and starch, cellulose aerogels stand out for the wide sources of raw materials, high carbon content, and easier construction of complex gel networks. The process of preparing carbon aerogels using porous plants as precursors can be faster and simpler, and the natural complex structure of biomass materials can become a natural template for carbon aerogels. These biomass materials contain a variety of P, S, and other elements, which can also provide natural heteroatom support for different subsequent development directions of carbon aerogels. Up to now, the actual effect of biomass-based supported photocatalysts has been verified. In the future, research on biomass-based supported photocatalysts can be based on existing results, analyze the elemental composition of different biomass precursors and the impact of three-dimensional pore structures on loading, and combine with other proven photocatalytic modifications and load method. At the same time, it can also try to give full play to the characteristics of biomass, such as cultivating plants as precursors of carbon aerogels to obtain better carbon aerogel templates. Ultimately, multi-faceted research results can be integrated to further improve the catalytic ability and loading capacity of biomass-based carbon aerogel-loaded photocatalysts, and provide new solutions for cheap and environmentally friendly photocatalytic systems.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 25904K]

  • Effect of Ce on the NOx removal performance of CoMnOx catalysts synergistic CO/NH3

    ZHANG Xingyu;LIU Qianqian;MI Shuqi;HAN Yunbin;XUAN Chengbo;GENG Wenguang;SUN Rongfeng;WANG Luyuan;School of Energy and Power Engineering,Qilu University of Technology(Shandong Academy of Sciences);

    The emission of CO and NO_x in sintering flue gas is the focus of current air pollution control. However, the traditional NH_3-SCR technology has problems such as unmatched flue gas temperature, uneconomical CO treatment, and serious ammonia slip. In order to explore the law of CO assisted NH_3-SCR denitrification technology, a series of de-NO_x catalysts with CoMnCe as the active component were developed by coprecipitation method. CO in the sintering flue gas can be used to synergize NH_3 to remove NO_x, which can improve the utilization of CO in the flue gas and reduce the use of NH_3. The performance test results show that when Ce molar ratio is 0.75, the catalyst exhibits the best synergistic NO_x removal efficiency, and the NO conversion efficiency is up to 98% at 125 ℃. The characterization results of XRD, Raman, XPS, TEM, H_2-TPR, etc. indicate that the increase of Ce molar ratio in the catalyst inhibits the growth of the grains in Co_3O_4. Although Co_3O_4 and CeO_2 still maintain the original lattice structure, there are still some Co or Mn atoms doped with Ce atoms, resulting in the distortion of the metal lattice, the formation of defect structures on the catalyst surface, and the generation of a large number of oxygen vacancies. At the same time, when the Ce molar ratio is relatively large, the catalyst surface structure is blocked by CeO_2. Moreover, the excess CeO_2 agglomerates on the catalyst surface, preventing Mn and Co species from participating in the catalytic reaction. The catalytic activity test finds that the prepared catalyst shows a certain anti oxygen inhibition ability, especially when the mole ratio of Ce is relatively low, the CO-SCR reaction activity is better at low temperature, and the anti-oxygen inhibition ability of the catalyst decreases with the increase of the mole ratio of Ce. At the same time, with the increase of temperature, the surface oxygen flows faster on the catalyst surface, thus promoting the reaction. At this time, the CMC2 catalyst with more Ce shows the best anti oxygen inhibition performance, and the NH_3-SCR denitrification activity is reduced by CO. However, its synergistic denitrification efficiency for the CMC0.75 catalystis still high at relatively low temperature, which may be due to the high oxidation capacity of the Co, Mn and Ce metal oxides contained in the catalyst, Therefore, reasonable control of the proportion and distribution of different metals can improve the oxidation capacity of the catalyst surface, enhance the flow of surface oxygen and the synergistic catalytic activity.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 21795K]

  • Heating technology of in-situ pyrolysis for tar-rich coal and its high efficiency process

    TANG Ying;WU Xiaodan;LI Lezhong;SU Zhan;WANG Ruoyi;Research & Development Center,CNOOC Gas & Power Group;CNOOC Research Institute Co.,Ltd.;

    China has abundant tar-rich coal resources.The use of in-situ pyrolysis can make a high efficiency and low-carbon utilization of tar-rich coal and it also extends the recover depth of coal greatly. In-situ heating technology is the core technology of in-situ pyrolysis of tar-rich coal and its efficiency determines whether the in-situ pyrolysis of tar-rich coal is economical. The development status of conduction heating, convection heating, chemical heating, and radiation heating technology were introduced, their characteristics and applicability on tar-rich coal based on thermo-physical property and pyrolysis characteristic studies were discussed. The advices on high efficiency process of in-situ heating were gived in the end. This paper argues that:(1) Tar-rich coal has low thermal conductivity, high specific heat capacity and low thermal diffusion coefficient, and its main pyrolysis temperature range is 350-650 ℃. Increasing the pyrolysis temperature of tar-rich coal is conducive to the production of combustible gases, especially H_2.(2) The conduction heating technology requires long time to heat the coal, which efficiency is very low. Convective heating technology has high heat transfer efficiency and its heat-carrying medium is conducive to both heat transfer and tar production. The reaction stability of chemical heating technology is difficult to control and its heat conduction also depends on heat-carrying medium. The heating range in radiation heating technology is generally limited.(3) Efficient heating technology, heat-carrying medium and heat transfer network are the high efficiency conditions of in-situ heating for tar-rich coal. Convection heating technology is recommended as the preferred technology for in-situ heating of tar-rich coal, steam as the heat carrying medium, and hydraulic fracturing as the preferred technology for coal seam fracturing.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 28331K]

  • Influence of CaO on furfural residue/coal co-gasification products

    CHEN Yuzhuo;SONG Yuncai;FENG Jie;State Key Laboratory of Clean and Efficient Coal Utilization, Taiyuan University of Technology;

    In order to reduce the tar content in the gasification syngas of industrial organic waste furfural residue, on the one hand, increased the gasification temperature in the furfural residue gasification by adding high energy density coal and organic solid waste furfural residue for co-gasification to achieve thermal cracking of gasification tar and improve the carbon conversion. On the other hand, CaO catalysts was introduced to crack the tar, which enabled the purification of the syngas and increased the elemental utilization of the furfural residues gasification. In this study, the effect of CaO addition on the products in co-pyrolysis stage and co-gasification stage was investigated to supplement the basic data of syngas purification in furfural residue gasification. The results show that CaO can improve the pyrolysis rate and promote the transformation of raw materials to light oil and syngas during the furfural residue pyrolysis stage. In the furfural residues and coal co-gasification, compared with no catalysis added gasification, 17.42% of tar can be thermal cracking when CaO is added in a mechanical mix as mechanical mixing, while the CaO is added by impregnation method can make the tar removal rate up to 69.41%, and the degree of tar lightening is improved. Both increasing temperature and adding CaO can decrease tar concentration and increase gas yield in co-gasification. In addition, X-ray diffraction spectroscopy(XRD) and scanning electron microscopy(SEM) were used to analyze the solid residue after gasification. Due to the fluxing effect of CaO, ash agglomeration occurs at 1 000 ℃.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 33980K]

  • Kinetics of pyrolysis and catalytic depolymerization of low rank coal

    LYU Jing;WANG Junli;ZHANG Jin;LI Shuying;LI Jinping;ZHAO Qiang;HAO Xiaogang;ZHAO Jianguo;College of Chemistry and Chemical Engineering,Shanxi Datong University;Engineering Research Center of Coal-based Ecological Carbon Sequestration Technology of the Ministry of Education,Shanxi Datong University;Shanxi Research Institute of Applied Chemistry;College of Chemical Engineering and Technology,Taiyuan University of Technology;

    The accurate description of low-rank coal pyrolysis and catalytic depolymerization process is the basis and key to multi-scale simulation, design and scale-up of reactors. Therefore, a simple, high-precision, and easily coupled low order coal depolymerization model with multi-scale reactor simulation was proposed based on the non-isothermal pyrolysis and catalytic pyrolysis experiments of low rank coal. The proposed model was compared with the one-step kinetic model and the distributed activation energy model(DAEM) which were most commonly used in reactor simulation. Finally, the adaptability of the model was verified by the experimental data of catalytic cracking of coal samples catalyzed by four catalysts. The results show that the new model proposed in this study can effectively simulate the whole process of low-rank coalpyrolysis. Compared with the one-step reaction model and the distribution activation energy model(DAEM), the model is not only simple, but also has a much higher simulation accuracy than those two models, reaching over 0.99. In addition, the pyrolysis simulation results of coal samples catalyzed by four catalysts show that the model can also simulate the catalytic depolymerization process very well, which further proves that the model is not only simple and accuracy, but also with wider range of application and higher applicability. It can be seen that the model proposed in this study has significant advantages in combining with multi-scale reactor simulation. The proposed model not only enrichs the kinetic system of coal pyrolysis, but also provides a simpler and more accurate method for the simulation and amplification of the reactor.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 14403K]

  • Research progress on the effect of preheating on coking coal properties

    XUE Qingguo;QIAO Zishen;ZHANG Linyang;WANG Jingsong;WANG Guang;SHE Xuefeng;State Key Laboratory of Advanced Metallurgy,University of Science and Technology Beijing;

    China is relatively rich in coal resources, but the proportion of coking coal resource is only 18.9%. Gas coal and 1/3 coking coal account for 47% in the identified resource reserves of coking coal, while high-quality coking coal accounts for less than 10%.In order to produce higher quality coke, many iron and steel enterprises add too much high quality coking coal, which brings great difficulties to the continuous supply of high quality coking coal resources and high quality coke. Rapid heating pretreatment technology is of great significance in expanding and saving the use of high quality coking coal resources, ensuring high and excellent coking production, reducing cost and improving coke quality. The improvement of coking coal properties by preheating treatment was reviewed. The focus is on the influence law of rapid preheating to improve coking coal adhesion. The results show that factors such as coal type, preheating temperature, and heating rate have a significant impact on its structural evolution during carbonization after preheating. During heat treatment, the aromatic structure of coal continuously develops, and graphitization increases. On the one hand, rapid preheating inhibits the thermal decomposition of coal, on the other hand, it relaxes the macromolecular structure of coal, which leads to enhance its fluidity during thermoplastic stage, improving its caking property. The shortcomings of rapid preheating technology in terms of mechanism research as well as industrial applications were summarized.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 18917K]

  • Research on the characterization methods of graphene carbon materials

    JIANG Xiaolin;LI Jun;LIU Zhen;WEI Linlin;WEI Hui;National Institution of Clean and-Low-Carbon Energy,CHN Energy;

    Due to the structural and performance disparities between graphene and graphene-like carbon materials, they exhibit distinct potential applications. Appropriate characterizations are important to analyze the properties of graphene materials and to guide their research. In this paper, four materials labeled as single-layer graphene(G1), few-layer graphene(G2), multilayer graphene(G3), and industrial-grade multilayer graphene(G4) were studied, and their physical and chemical structures were characterized by Raman spectroscopy, X-Ray Diffraction(XRD), Scanning Electron Microscopy(SEM), Transmission Electron Microscope(TEM), Atomic Force Microscopy(AFM) and N_2 adsorption/desorption methods. The means of characterization, data analysis and mutual verification of each characterization result were discussed. The results show that G1 has a relatively low number of layers with I_D/I_G=0.88. Validation through TEM, AFM, and XRD confirms an actual number of 10-20 layers, a specific surface area of 564.03 m~2/g, and the typical characteristics of graphene, placing it within the category of graphene. In contrast, G2-G4 have more than 100 layers with I_D/I_G=0.07-0.18. The specific surface area of G2-G4 is 30-50 m~2/g. Combining structural and morphological results, these materials are classified as the graphene-like category. This study provides reference and guidance for the analysis and quality assessment of graphene materials.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 45810K]

  • Analysis on low-carbon development path of coal-fired power generation industry

    XU Shunzhi;ZHAO Ruitong;WANG Xiaoquan;YANG Fengling;ZHANG Peihua;Institute of Resources and Environmental Engineering,Shanxi University;State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources,Shanxi University;Shanxi Guojin Coal and Electricity Co.,Ltd.;

    In order to achieve green and low-carbon development and improve its competitiveness in the new power system in the future, the coal-fired power generation industry urgently needs to undergo transformation and reform. This is due to the joint requirement of accelerating the construction of ecological civilization and the goal of "carbon peak and carbon neutralization". In this paper, three major challenges facing the coal-fired power generation industry in reducing carbon emissions in the context of "dual carbon" were discussed, including the traditional design parameters of the coal-fired power generation industry, the installed capacity of new energy sources, and the security of the power system. In order to assure the security of power system supply, the coal-fired power generation industry should transition from supplying base load power supply to regulatory power supply and take on the roles of "Ballast Stone" and "Stabilizer" in the new power system. In order to solve the contradiction between the stability of the power system and low-carbon development, the low-carbon development path of the coal-fired power generation industry must be analyzed from multiple perspectives. Then, the paths that the coal power industry can follow for the development of a low-carbon transition were examined from various angles, including those related to coal-fired generation units, coal fuel and combustion, clean coal power generation technology, carbon capture, carbon trading, and spot trading, providing various reference points for the coal-fired power industry to simultaneously carry out the development of a low-carbon emission reduction transition. At the same time, in the context of "Dual Carbon", it will strive for more survival opportunities for the coal power industry, which is undergoing a challenging phase-out. It is worth noting that these low-carbon transformation and development paths also need the relevant government departments to introduce relevant policies to provide support, such as regular government-enterprise co-operation, the coal-fired power generation industry can achieve high-efficiency, green and low-carbon transformation and development as soon as possible.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 7299K]

  • Element transformation rule of Xichagou ashless coal during the supercritical water oxidation process

    ZHANG Rong;ZHAO Xuechao;LIU Zhichang;GU Sumin;QU Xuan;CHEN Haokan;BI Jicheng;State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences;College of Chemical Engineering and Environment,China University of Petroleum(Beijing);

    The emission of pollutants during the coal combustion process has severely hindered the sustainable development of coal-fired power plant, and it is urgent to explore efficient and ultra-low emission coal-fired power generation technologies. By oxidizing coal powder in supercritical water, the chemical energy generated is directly released into the water, producing a supercritical water/CO_2 composite working fluid that drives the steam turbine to work and generate electricity. After working with the working fluid, high concentration CO_2 can be directly recovered, achieving near zero emission combustion and power generation of coal. The effects of mineral removal on coal structure was studied by FTIR. The oxidation reaction characteristics of ashless Xichagou coal and the transformation of carbon, sulfur and nitrogen in supercritical water were studied under the conditions of the temperature region of 400-600 ℃ and oxidant equivalence ratio region of 1.0-1.4. The results show that demineralization by the acid alkali combined method has little effect on the structure of Xichagou coal, with shorter side chains of coal macromolecular fat and a slight increase in aromatic carbon content. The Xichagou deashing coal is oxidized in supercritical water, and the temperature and amount of oxidant have a significant impact on the coal conversion rate. The gas phase products are mainly CO_2 during supercritical water oxidation, without producing NO_x and SO_x. Small amount of CO and H_2are detected at temperatures lower than 500 ℃. When the final reaction temperature exceeds 500 ℃, the converted carbon is completely oxidized to carbon dioxide. The conversion of carbon, nitrogen, and sulfur in coal increases with the increase of final temperature and the amount of oxidant. At the final reaction temperature of 550 ℃ and the oxidant being 1.4 times stoichiometric, the conversion rates of C, N and S reach 97.08%, 94.52% and 94.41%, respectively.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 24181K]

  • Experimental study on pyrolysis of semi-coke pure combustion in 60 t/h preheating combustion boiler

    ZHU Shujun;TIAN Jilin;ZHU Jianguo;LYU Qinggang;State Key Laboratory of Coal Conversion,Institute of Engineering Thermophysics,Chinese Academy of Sciences;Shanxi Key Laboratory of Coal Flexible Combustion and Thermal Conversion,Datong Institute of Coal Clean and Efficient Utilization;University of Chinese Academy of Sciences;

    Low rank coal reserves are abundant in China, and pyrolysis technology has rapidly developed as the core of cascade utilization of low rank coal. The pyrolysis of low-rank coals produces a large amount of semi-coke, constituting approximately 50% to 70% of the weight of raw coal and about 80% of the energy of raw coal. However, due to its low volatile content, pure burning semi-coke is restricted by its poor ignition stability, difficult burnout and high pollutant emission level.The preheating combustion technology emerges as an effective solution to address these issues. In this process, fuel is modified at high temperature in the preheating burner, converting from a single solid fuel to a binary high temperature gas and solid mixed fuel, and then sent into the boiler furnace for high efficiency and low nitrogen combustion. Relevant pilot tests have been carried out on the 2 MW test platform. In order to further verify the technical effect, the operating characteristics and NO_x emission characteristics of pure burning semi-coke with different loads were carried out on a 60 t/h preheating combustion boiler for pulverized coal, equipped with two preheating burners in hedged arrangement. The experiment results show that semi-coke run stably and satisfactory under boiler loads in the range of 50%-90%, with a rational distribution of furnace temperatures. The parameters of the 26 MW_(th) preheating burners are reasonable, exhibiting stable circulation states and good symmetry. After preheated, semi-coke achieves high efficiency combustion, the combustion and thermal efficiency of the boiler are above 98% and 92.5% under each load, respectively. By adjusting the air distribution, the original NO_x emission under each boiler load is lower than 200 mg/m~3(φ(O_2)=6%), indicating that low NO_x combustion effect is remarkable. The experimental results provide important support for the design and engineering scale-up of pure semi-coke preheating boiler and can directly provide theoretical data reference for the application of hedge boiler.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 17024K]

  • Research on compression, drying and liquefaction equipment selection in CO2 capture system of the coal-fired power plant

    LI Cai;GONG Haiting;YANG Yang;ZHENG Xufan;CHN Energy Taizhou Power Co.,Ltd.;CHN Energy New Energy Technology Research Institute Co.,Ltd.;

    The product processing devices of the flue gas carbon capture system of coal-fired power plants include compression, drying and liquefaction devices, and their selection determines the product gas quality. Based on the 500 000 t/a flue gas CO_2 wet capture project of a 1 000 MW thermal power plant, this paper conducted a comparative study and analysis on the selection of CO_2 compressors, refrigeration liquefiers and other equipment required for the compression, liquefaction and cooling processes of the CO_2 gas compression system in view of the characteristics of the wet absorption process, such as high CO_2 gas moisture content, large gas volume but low compression pressure, combined with the operating restrictions of power generation and heat supply of the power plant. The adaptability of chemical system equipment applied to power production units was also discussed. The results show that the type selection of CO_2 capture device for flue gas of coal-fired power plants is greatly different from that of petrochemical units. Compared with the pursuit of stability of the load of petrochemical units, the load fluctuation of modern thermal power plants during peak shaving operation is extremely strong. The CCUS project of thermal power plants uses power plant smoke as raw material, uses power plant waste heat steam, takes up the share of power consumption, and shares circulating water, closed water, compressed air and other production materials, leading to the fluctuation of flue gas volume, power steam parameters, flue gas CO_2 concentration, cooling water source, etc. The design boundary conditions for the selection of heat exchanger and compressor are different from those of petrochemical units. In general, coal-fired power plants and petrochemical enterprises are located in different locations. Most of the petrochemical enterprises are located in the same chemical industry zone as upstream and downstream enterprises. Thermal power plants are not adjacent to CO_2 consuming units. The product gas quality standards, gas packaging and transportation equipment of CCUS units of thermal power plants need to be differentiated from chemical units based on regional and market positioning. Compared with chemical units, the CCUS project of coal-fired power plant has the advantage of lower power source cost. Power plant projects should consider reducing the cost of absorbent loss more, instead of blindly pursuing to reduce energy consumption costs.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 5572K]

  • Removal process simulation on coal-pyrite of injection coal based on column fluidized bed

    YU Yanhui;SHI Changliang;Department of Mechanical and Electrical Engineering,Yongcheng Vocational College;College of Chemistry and Chemical Engineering,Henan Polytechnic University;

    The pyritecontent in the returned powder of coal millcan be effectively reduced and the SO_2 environmental pollution can be reduced due to high-gradient magnetic separation technology, as the embedded combination in the coal injection combustion system. Also, the pre-removal efficiency of coarse coal powder classifier is an important factor affecting the quality of magnetic separation and powder recovery. Coal-pyrite and coal-matrix were selected as mixed simulation samples. Based on a self-made column fluidized bed, the particles motion characteristics were simulated under the influence of particle size, fluidization speed and mixing ratio. The results show that the fluidization velocity is relatively uniform in column fluidized bed, and there are primary and secondary mismatching zones in the separation zone. In the actual separation process, the particles motion characteristics of each particle size are completely different. The increase of the particle size corresponds to a decrease response of the fluidization velocity. The simulation yield of coarse coal-matrix is 99.4%, and the yield of fine coal-matrix is 91.7%. The fine particles are obviously difficult to handle under different conditions, so the over-grinding phenomenon in the front section should be avoided. The loss of the coarsecoal-matrix in the heavy products and the entrainment of fine middling coal pyrite in the light products are the main reasons for the low separation efficiency of fluidized bed. Also, with the increase of the proportion of coal-pyrite, the movement characteristics of coarse particles do not change significantly, and the mixed materials in the medium particle size show a phenomenon of material return in the secondary mismatch zone of the sorting area. The comparison separation experiment under the simulation parameters was further carried out. The sulfur content of the enriched light products is greatly reduced at the optimal simulation parameters, and the experimental yield is close to the simulated yield. The research results are of positive significance for improving the coal injection combustion efficiency and finally reducing coal pollution.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 39291K]

  • Adaptive control of heavy medium coal preparation without modeling dynamic compensation drive

    LI Weitao;GOU Xiaodong;National Energy Group Wuhai Energy Co.,Ltd.,the Nei Monggol Autonomous Region;Guoneng Zhishen Control Technology Co.,Ltd.;

    The heavy medium coal preparation process is fraught with many uncertainties and disturbances, and its working conditions undergo complex dynamic changes. The traditional PID control falls short in effectively tracking and controlling ash content, which cannot meet production requirements. There is an urgent need for more advanced and intelligent control approaches to improve the performance of ash tracking and controlling, thereby facilitating improved energy conservation and consumption reduction. The technological process of heavy medium coal preparation process and the control property of coal ash content in heavy medium coal preparation process were analyzed. Aiming at the strong nonlinear and complex dynamic characteristics of heavy medium coal preparation process, a combination model of low-order linear model and high-order unmodeled dynamic term was used to describe the ash control system model of heavy medium coal preparation process. By using the projection algorithm and the adaptive fuzzy system(Adaptive Network-based Fuzzy Inference System, ANFIS) to alternately identify the parameters of the linear model and the unmodeled dynamic terms, an adaptive control system of heavy medium coal dressing driven by unmodeled dynamic compensation was designed to offset the influence of the unmodeled dynamic on the stability of the closed-loop system. Through heavy medium coal selection experiments, the control effects of unmodeled dynamic compensation driven heavy medium coal selection adaptive control and linear adaptive control were compared. The results show that the ash tracking control of the unmodeled dynamic compensation heavy medium coal selection process has a faster response, with an average output error absolute value of 0.316 5%, which is 13.67% lower than linear adaptive control, and has better steady-state performance. The study validates the effectiveness of estimation algorithm and adaptive control method of the proposed model for ash content control system.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 14051K]

  • High-shear condition for enhancing flotation of low rank coal and the associated mechanisms

    QIAO Erle;MIN Fanfei;SHEN Liang;LIU Lingyun;School of Material Science and Engineering,Anhui University of Science and Technology;

    In the flotation process of low rank coal, the adsorption behavior of collector on the particle surface has an important impact on the final flotation results. In order to strengthen the adsorption of oil collector on the surface of low rank coal, the strengthening mechanism of high intense condition on the flotation of low rank coal were investigated using theoretical calculation, molecular simulation and experimental analysis. The adsorption process of n-dodecane oil droplet on coal particle surface was studied by adsorption test and theoretical calculation. Collector-water-coal simulation system was constructed, and the influence of the initial distance between collector and coal surface on the final adsorption results was explored. The effect of impeller speed on the yield and ash content of clean coal was studied. The results show that the adsorption capacity of n-dodecane on the surface of low rank coal can be significantly increased by high shear mixing. When the impeller speed exceeds 2 000 r/min, the increase in adsorption gradually diminishes, reaching a stable level. An energy barrier exists between the n-dodecane oil droplet and the coal particle. After crossing the energy barrier, the total potential energy decreases rapidly. The initial distance between n-dodecane oil droplet and low rank coal surface has an important influence on the final simulation results. When the initial distance is closer, droplets can adsorb and spread on the coal surface, whereas a greater initial distance prevents adsorption. High-shear pulping significantly improves the flotation performance of low-rank coal. The yield of clean coal increased about 13% by high intense condition method compared with that of conventional flotation, while the ash content remains basically unchanged.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 25586K]

  • Optimization of swirling-disturbed flow field for flocculation and settlement of coal slime water

    HU Jinliang;LIN Zhe;Shenhua Zhunneng Group Co.,Ltd.,CHN Energy;School of Chemical Engineering and Technology,China University of Mining & Technology;

    Flocculating device has a significant impact on the flocculation process and effect by its inner flow field. According to the vortex flocculation dynamics theory, an integrated flocculation-sedimentation device with swirling-disturbed flow field was designed and used for the continual flocculation and sedimentation of slime water. Firstly, the appropriate reagent addition conditions were determined by the sedimentation tube flocculation sedimentation experiment: the mass concentration of polyaluminum chloride is 5 mg/L, and the mass concentration of polyacrylamide is 2 mg/L. Then, under this fixed agents addition condition, the underflow concentration and overflow turbidity were used as indicators to investigate the influence of height, number of groups and installation angle of isosceles triangle spoilers on the flocculation and settlement of slime water in an nnnular flow channel between the inner and outer diameter of 50 and 100 mm, respectively. The results show that the height of the spoiler and the number of groups have a significant effect on the flocculation settlement effect: within the experimental range, the height of the spoiler is the best under the condition of 5 groups of spoilerswhen the height of the spoiler is 15 mm, and the overflow turbidity is 142 NTU, which is better than 54 NTU that with none spoiler. When the number of spoiler groups is in the range of 0-5, the case of 3 groups is the best, and the overflow turbidity is reduced to 112 NTU. Under the condition of 3 groups of 15 mm spoilers, the change of the spoiler has little effect on the flocculation sedimentation effect, and the turbidity is between 107-125 NTU, of which 30° is the most one. The analysis suggests that the spoiler height influences particle collision and breakage by controlling the characteristic scale of the vortex guided by it and the energy dissipation, while the number of spoiler groups mainly affects the length of the coagulation zone, thereby changing the effective coagulation time of the particles.

    2023 12 v.29;No.160 [Abstract][OnlineView][HTML全文][Download 14417K]



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